A drawing instrument for drawing straight or dashed lines including a scriber support assembly composed of a body part slidable in a groove on a ruler and an arm part which extends beyond either edge of the ruler and carries at its outer end a scriber. The inner end of the arm part is connected to the body part by a hinge and a follower carried by the arm part follows shapes such as undulations in grooves in the ruler between the side edge thereof and the hinge whereby the outer end of the arm part and the scriber are raised and lowered to make dashed lines. One groove can be flat whereby the scriber produces a continuous line.

Instruments for drawing dashed or similar lines e.g. dot-dashed or, alternatively, continuous lines are known. The patent to Simmons U.S. Pat. No. 2,081,439 teaches an instrument for drawing dashed lines wherein a horizontal carriage has fixed along one edge a downwardly extending fin which is slideably received in a longitudinally extending, open-topped groove in a ruler. The carriage extends beyond one longitudinal edge of the ruler and at its outer end it carries a vertically adjustable scriber such as a drawing pen. Intermediate the one longitudinal edge of the ruler and the slot is a follower which engages a longitudinally extending changeable plate having on its upper edge undulations defining peaks and valleys. As the carriage is moved longitudinally the follower follows the undulations and periodically lifts the scriber point from the paper being marked whereby a dashed line is drawn. The lengths of the dashes, that is, the parts of the line drawn by the scriber as the carriage is moved relative to the ruler, can be controlled by adjusting the scriber relative to the carriage so that the scriber pointer is closer to or farther away from the carriage. If it is lowered a substantial distance, the carriage and the follower are lifted relative to the ruler and the follower may just hit only the tops of the peaks whereby only short blank portions appear in the line between long dashes. If the point is lowered still more the follower is lifted entirely clear of the peaks and a continuous straight line is drawn.
In theory, the Simmons unit performs as intended. However, because its guide fin rides in an open top groove and is rigidly fastened to the carriage, as the follower traverses the peaks and valleys on the plate edges, the carriage must perforce rock which causes the fin to periodically cock in the groove thus impeding movement of the carriage, or the groove must be wide enough to cater to this problem thus producing a zig-zag line, or the entire carriage and its fin must move vertically. It is difficult for an operator who is moving the carriage by a knob intermediate the groove and guide to control his manual vertical pressure on the knob so that the entire carriage can rise an fall and if he accidently lifts the carriage the pen can skip more than intended resulting in an uneven dashed line.

Instrument for drawing dashed lines or the like


The seat back for a bench vehicle seat is mounted for movement with an adjustable sector between an upright or dress-up position and a full reclining position, and may be positively locked in any intermediate position of adjustment. In addition, the seat back is releasably pivoted to the sector, and is automatically released for forward pivotal movement to a horizontal position when the sector is pivoted forwardly to a limiting position.

Field of the Invention
The present invention is concerned with adjustable seat backs for bench type automobile seats, normally provided in cars, vans and buses.
In accordance with the present invention, the seat back is movable relative to the seat bottom between a rearwardly extending horizontal full reclining position and a forwardly extending horizon position in which the back of the seat constitutes a horizontal support including an intermediate position in which the seat back is substantially erect herein referred to as the dress-up position.
Means are provided to retain the seat back positively locked in any intermediate position between its erect and its full reclining position. This includes sectors pivoted to a seat frame comprising spaced apart plates referred to as seat mounts and covers, the sectors having arcuate sections of ratchet teeth engageable with locking pawls pivoted between the plates constituting the seat mount and cover. The pawls are engaged by wedge cams connected to interconnected release handles to each end of the seat ratchet which are spring biased in a direction to wedge the pawls into engagement with the ratchet section on the sector.
The wedge angle is such that the locking action is irreversible by forces applied to the seat back. The release handle when moved to full release position by the operator includes a surface engageable with a finger on the pawl to provide for positive displacement of the pawl from the ratchet teeth.
The sectors are provided at both ends of the seat, and are connected to strong counterbalance springs effective to move the seat back to and slightly beyond its full erect or dress-up position. The seat back is adjustable by a seat occupant who releases the cam lock and applies pressure to move the seat back against the counterbalance springs to the desired position, at which time release of the handle permits its spring to move it and the wedge cam to sector locking position.
Since the locking hardware is provided at both ends of the seat and seat back, it is necessary to provide means for releasing the sectors for simultaneous movement. This is accomplished by a torsion tube extending between the ends of the seat back, with connections to the release handles, so that the seat back may be adjusted or manipulated from either end.
The sectors are each provided with hinge plates which are pivotally connected to the upper ends of the sectors, and which are fixedly secured to opposite ends of the seat back frame to provide for forward swinging movement of the seat back from its upward extending position to its forwardly extending position. During movement of the seat back between its erect position and its fully reclining position, the hinge plates are fixedly connected to the sectors by latch cams pivoted to the sectors and latched over studs connected to the hinge plates. The latch cams have camming pins extending into cam slots provided in the seat mounts. The seat mount slots include arcuate portions concentric with the pivot axis of the sectors and camming portions inclined to the arcuate portions operable during limited movement of said sectors forwardly from erect position to cam the latch cams to release the studs on the hinge plates. Thus, as the sectors are spring biased into their forward limiting position, the hinge plates with the seat back secured thereto are released for pivotal movement of the hinge plate relative to the sectors to permit the seat back to move to forwardly extending horizontal position. As the sectors move to release the latch cams, the tooth portions of the sectors move beyond the pawl teeth, which then slide on smooth arcuate surfaces on the sectors.
When the seat back is swung upwardly and rearwardly from its forwardly extending horizontal position, the studs on the hinge plates engage the latch cams, and further movement pivots the sectors, causing the latch cams to be cammed into latching position by the cam slots. When the sectors have pivoted sufficiently to engage the latch cams, the toothed ratchet portions are engaged by the pawls which are wedged in locking position by the spring biased wedge cams.


A tissue expander device is provided which permits insertion at a significant distance from the area to be expanded, preferably hidden in a skin crease or in some other inconspicuous place. A central removable firm member is disposed within the expanded device to facilitate subcutaneous passage from an insertion site to a remote tissue expansion site.

The invention relates to a tissue expander apparatus and tissue expansion methods enabling insertion at an insertion site which is remote from a tissue expansion site.
The invention permits remote subcutaneous insertion of a balloon-like tissue expander to eliminate currently-experienced difficulties with, for example, scar tissue and the like which results when an incision is made at or near the location where the tissue expander is to be placed. None of the art teaches or suggests remote subcutaneous insertion of a tissue expander, nor the novel expander apparatus of the invention.

Tissue expander apparatus, and methods of constructing and utilizing same


Apparatus and methods are described for highly attenuating vibrations of a drillstring assembly while drilling. In one embodiment, vibrations are attenuated by introducing one or more vibration attenuation modules at appropriate assembly locations. For example, vibration attenuation modules may be inserted at locations where vibration energy is expected to be maximal. In one embodiment the vibration attenuation modules include cavities loosely packed with particles of solid material such as sand or metallic powder. In one embodiment, the cavity walls are rough and/or include geometric features that enhance vibration energy transfer to the loosely packed particles in the cavity(ies). The vibration energy is dissipated via friction and inelastic particle-particle and particle-wall collisions that occur as a result of drillstring motion.

It is well known that during well drilling operations, drillstring assemblies can undergo potentially damaging vibrations. Axial (e.g. bit bounce), torsional (e.g. stick-slip), and lateral (e.g. flexing, whirling) vibrations are well known phenomena that can damage drilling assemblies. See Jardine S., Malone, D., and Sheppard, M., "Putting a damper on drilling's bad vibrations," THE OILFIELD REVIEW, Schlumberger, January 1994. Extensive study and engineering has been done over the years to better understand, monitor, and control these potentially damaging drillstring vibrations. See Rabia, H., "Oilwell drilling engineering principles and practice," Graham & Trotman, 1985; Clayer, F., Vandiver, J. K., and Lee, H. Y., "The effect of surface and downhole boundary conditions on the vibration of drillstrings," PROCEEDINGS 65 ANNUAL TECH. CONF. SPE, New Orleans, SPE 20447 1990; Tucker, R. W. and Wang, C., "An integrated model for drillstring dynamics," Lancaster University, 2000; Dykstra, M. W., Chen, D. C., Warren, T. M., and Azar, J. J., "Drillstring component mass imbalance: A major source of downhole vibrations," SPE DRILLING AND COMPLETIONS, December 1996; Lesso W. G. Jr., Chau, M. T., and Lesso, W. G. Sr., "Quantifying bottomhole assembly tendency using field directional drilling data and finite element model," SPE/IADC 52835, 1999.
Downhole monitoring and surface control techniques have been proposed to deal with some of the vibrations mentioned above. See Halsey G. W., Kyllingstad, A., and Kylling, A., "Torque feedback used to cure slip-stick motion," SPE 18049, 1988; Alley, S. D. and Sutherland, G. B., "The use of real-time downhole shock measurements to improve BHA component reliability," SPE 22537 1991; Aldred, W. D., and Sheppard, M. C., "Drillstring vibrations: A new generation mechanism and control strategies," SPE 24582 1992; Chen, D. C-K., Smith, M., and LaPierre, S., "Integrated drilling dynamics system closes the model-measure-optimize loop in real time," SPE/IADC 79888. However, it has become clear that in-situ damping of the vibrations would have a greater impact on limiting the extent of damage caused by the vibrations the drillstring is subjected to.
Accordingly, some have proposed in-situ damping techniques, although each has its limitations. APS Technology suggests use of an isolation sub, which includes two loosely threaded cylindrical members with rubber molded into the threaded cavity. The rubber between threaded cylindrical members is intended to damp the drilling induced vibrations. Nevertheless, the temperature-dependent properties of rubber, inter alia, make it difficult or impossible to obtain reliable performance across different drilling conditions. In addition, the huge torque and axial loads common to drilling operations must be transmitted through the rubber damping material, which is difficult. Cobern and Wassell propose a modified sub in which a magnetorheological fluid filling a narrow gap between two components of the drillstring assembly is used as the damping mechanism. Cobern, M. E., and Wassell, M. E., "Drilling vibration monitoring and control system," APS TECHNOLOGY INC. TECH. REPORT APS-DVMCS, 2004. The viscosity of the fluid is regulated by a magnetic circuit to tune the damping under different drilling conditions. It is not clear, however, that this proposal will be effective.
The present specification is directed to overcoming, or at least reducing the effects of, one or more of the problems outlined above.

Methods and apparatus for attenuating drillstring vibrations


A data storage device involves a plurality of continuous sidewalls and corner portions of a tub cover overlapping with and hermetically sealed with a corresponding plurality of sidewalls and corners of an enclosure base using an epoxy adhesive. Base protrusions and/or cover dimples may be used to set a suitable gap between the parts. A robust hermetic seal provides for filling the HDD with a lighter-than-air gas. A tub cover may include corners having a tapered radius that decreases from the top to the bottom edge, and a base may include corners having a constant-radius outer surface and sidewalls having a sloped upper surface, whereby an assembly interference fit between the base and the tub cover is formed by forcing outward each sidewall of the tub cover while forcing inward at least a portion of each corner of the tub cover.

A hard-disk drive (HDD) is a non-volatile storage device that is housed in a protective enclosure and stores digitally encoded data on one or more circular disks having magnetic surfaces. When an HDD is in operation, each magnetic-recording disk is rapidly rotated by a spindle system. Data is read from and written to a magnetic-recording disk using a read-write head that is positioned over a specific location of a disk by an actuator. A read-write head uses a magnetic field to read data from and write data to the surface of a magnetic-recording disk. A write head makes use of the electricity flowing through a coil, which produces a magnetic field. Electrical pulses are sent to the write head, with different patterns of positive and negative currents. The current in the coil of the write head induces a magnetic field across the gap between the head and the magnetic disk, which in turn magnetizes a small area on the recording medium.
HDDs are being manufactured which are hermetically sealed with helium inside. Further, other gases that are lighter than air have been contemplated for use as a replacement for air in sealed HDDs. There are various benefits to sealing and operating an HDD in helium ambient, for example, because the density of helium is one-seventh that of air. Hence, operating an HDD in helium reduces the drag force acting on the spinning disk stack and the mechanical power used by the disk spindle motor. Further, operating in helium reduces the flutter of the disks and the suspension, allowing for disks to be placed closer together and increasing the areal density (a measure of the quantity of information bits that can be stored on a given area of disk surface) by enabling a smaller, narrower data track pitch. The lower shear forces and more efficient thermal conduction of helium also mean the HDD will run cooler and will emit less acoustic noise. The reliability of the HDD is also increased due to low humidity, less sensitivity to altitude and external pressure variations, and the relative absence of corrosive gases or contaminants.
Electronic systems that require a hermetically-sealed internal volume (e.g., a lighter-than-air gas-filled, sealed HDD) need a way of preventing the occurrence of leakage through the interface between the cover and the corresponding enclosure base to which the cover is coupled. One approach is to utilize two covers: (1) one (a "first cover") being the typical HDD cover coupled to the base with fasteners and with a gasket seal therebetween, but not hermetically-sealed, with (2) another cover (a "second cover") being welded to the base over the first cover, such as by laser welding. However, sealing approaches involving laser welding secondary covers to the base are a relatively costly process in the context of the mass production of HDDs, with strict surface finish requirements and the cost of the welding equipment being main contributors to the cost. Furthermore, the welded seam is often a weak point, which may be damaged in the field by rough handling of the devices, whereby consequent leaks may result in an increased drive failure rate as compared to non-sealed products. Based at least on the foregoing, challenges remain with welded covers for hermetically-sealed HDDs.
Any approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.

Adhesive cover seal for hermetically-sealed data storage device


The present invention relates to a semiconductor memory device and more particularly to a semiconductor memory device and a method for arranging a signal line therein which can realize a high bandwidth by embodying a chip architecture being comprised of a multi I/O line. A semiconductor memory device includes arrays comprised of a plurality of reference blocks for storing a plurality of memory cells, a plurality of word lines extending in the direction of length of a chip, a plurality of bit lines extending in a vertical direction of length of a chip, each pair of bit lines being comprised of a bit line and a complementary bit line, a plurality of data I/O lines arranged on the upper portion of the arrays and extending in the vertical direction, each pair of data I/O lines being comprised of a data I/O line and a complementary data I/O line and being one by one connected to each pair of bit lines, and a plurality of column selection lines arranged in the vertical direction and adjacent to the data I/O line and complementary data I/O line, for controlling connection of each pair of bit lines to the data I/O lines.

The present invention relates to a semiconductor memory device and more particularly to a semiconductor memory device and a method for arranging signal lines therein which can realize a high bandwidth by embodying chip architecture being comprised of a multi I/O line.
In designing a semiconductor memory device, one of the most important details is to select an appropriate chip architecture. Parameters indicating performance of the semiconductor memory device, for example, power-consumption, operation speed, chip size, etc. are dependent upon the chip architecture. In other words, an excellent flexibility of the chip architecture greatly contributes to satisfaction of the requirements of such parameters. In practical chip architecture, design, as apparent to one skilled in the art, it is further noted that flexibility of the chip architecture enables its base structure to be maintained without any changes, when changing or adding a peripheral circuit, or increasing the density of the semiconductor memory device. Also, the flexibility of the chip architecture can easily respond to these variations. Now, an object of developing a semiconductor memory device includes achieving a high bandwidth in proportion to the high density of a semiconductor memory device. In other words, a concept of the semiconductor memory device has been changed from one of a simple high density memory device to a new one in which the memory device has the high bandwidth and is synchronized with the speed of a system. For example, in the case of memory device having a capacity of 64M or more, in particular, RAM bus dynamic RAM or synchronous dynamic RAM with a mother version as 256M dynamic RAM, one operational cycle should process data of 256 bits. Therefore, to satisfy the development trend of semiconductor memory devices toward the high bandwidth, the architecture of the memory device to be used with a mother version of 256 bits should have an internal bandwidth of 256 bits (one cycle). Many memory device designers are studying an architecture having a possible high bandwidth. Meanwhile, the higher the density of the memory device is, the larger the size of the chip. As a result, reading and writing data is difficult due to the increment for loading of each line. This difficulty creates an absolute need for a new architecture.
FIG. 1 shows a construction of chip architecture for 256M in a conventional semiconductor memory device. Further, the circuit construction of internal columns based on the chip architecture shown in FIG. 1 is disclosed in, for instance, U.S. Pat. No. 5,247,482, entitled "Semiconductor Memory Device With High Speed Write Operation". When selecting a conventional folded bit line structure in order to constitute a 256M DRAM, 32K word lines and 16K bit lines are necessary. Of course, 512 cells will be able to be connected to one bit line, but it is common that 256 cells are connected to one bit line. Therefore, an array of 2M can be activated by one word line. Here, it is assumed that if a refresh cycle corresponds to 16K, two word lines would be enabled in the length direction of the chip by the activation of a row address strobe signal RAS. Thereby, the whole 256M, arrays of 8M would be activated. If the arrays are activated as depicted in FIG. 1 and two pairs of I/O lines are positioned in a sense amplifier area, the number of bits of data processed in a 2M array is 4, which corresponds to the number of I/O lines. Thus, in whole 256M, 16 bits of data can be possessed. Since this differs greatly from a desired internal bandwidth of 256 bits, a practical achievement of high bandwidth is impossible. Further, the high bandwidth can not be realized with the above-mentioned chip architecture. Also, in this chip architecture, loading of I/O lines as well as junction loading of gate transistors for connecting the I/O line to a bit line are great, which can lead to difficulties in developing a voltage on the I/O line upon performance of a read operation. Further, upon performance of a write operation, since the data I/O line shown in FIG. 1 is directly connected to the bit line through the gate transistor, the junction loading and bit line are hurt. For that reason, it is appreciated that the construction of FIG. 1 is not suitable for the high density memory device.
FIG. 2 shows another embodiment of a conventional semiconductor memory device, through which a high bandwidth can be achieved, compared with that of FIG. 1 and in which the line loading of FIG. 1 is greatly reduced. FIG. 2 is disclosed in "Circuit Techniques For a Wide Word I/O Path 64 Mega DRAM" on pp. 133-134 of a paper in "1991 SYMPOSIUM ON VLSI CIRCUITS". For details of FIG. 2, the above paper will be helpful. In the figure, the loading of I/O lines is reduced by using sub I/O lines and a local I/O lines. Also, a predetermined number of sense amplifiers are integrated to the sub I/O line, to transmit data to the local I/O line through a differential amplifier. This prior art may have an internal bandwidth to some extent, but it is disadvantageous in that the number of NMOS transistors through which data is transmitted is large, upon performance of a write operation. FIG. 3 is a block diagram illustrating the data I/O lines of FIG. 2. Upon performance of a write operation, data on the local I/O line is transmitted to a transistor 2 of FIG. 2 by the enable of a signal SEC SELECT having column information of a selected block, but if a signal YWRITE for determining sub I/O line is enabled, the data is transmitted to the sub I/O line through a transistor 4. If an information signal S/A SELECT of a predetermined bit line selected in a plurality of bit lines connected to a single sub I/O line is enabled, the data is transmitted to the bit line through a transistor 10. As mentioned above, when the write operation is performed, since the data transmission is made from the I/O line to the bit line only through three NMOS transistors, it is seriously disadvantageous in performing a write operation in a high integrated memory device having great line loading.

Semiconductor memory device for achieving high bandwidth and method for arranging signal lines therefor


An actuator system comprising a housing (2, 19) having at least one socket (6) for the insertion of an electrical plug (7). The housing (2, 19) is provided with an arrangement which is capable of retaining an electrical plug, preferably of the Jack, DIN or Minifit type, inserted into said socket, said arrangement comprising a union nut (8) which may be retained in a position above the opening of the socket (6), and which at the same time surrounds the plug (7), said union nut (8) being rotatable between an inoperative position in which the plug (7) may freely be inserted and removed, and another position which is a locked position, in which the plug (7) cannot be inserted and, if it is already inserted, cannot be removed.

1. Field of the Invention
The invention relates to an actuator system having at least one arrangement for an electrical plug, the arrangement including a socket and a rotatable union nut in connection with this, the union nut having an opening for inserting the plug into the socket.
2. The Prior Art
Low voltage plug connections are widely used in conjunction with apparatus, equipment and installations, and are well-known. As examples of plugs which are typically used for adjustable pieces of furniture with actuator systems, the conventional Jack or DIN types and the more modern Minifit type (trademark of Molex corp.) can be mentioned. The plugs are normally only fixed in the connection by the clamp connectors of the socket. A plug may therefore be inserted relatively easy into the socket, but it also has the disadvantage that it may unintentionally fall out, either completely or partially. This may e.g. happen when the bed is transported over an uneven surface, or when the cord gets caught in something. Sometimes it is desirable and at times required that a plug cannot readily be removed. If it is an electrically adjustable bed, it is very inconvenient for both the user of the bed and for the nursing staff when a plug falls out, as the bed then loses some of its functionalities e.g. that the resting surface of the bed cannot be adjusted. This also causes an extra strain on the service staff who have to solve the problem. At worst, it could be fatal e.g. when the bed with a patient who is in shock cannot be adjusted to a horizontal resting surface. If a plug is not secured in its socket in the housing, there is the further risk that water and disinfectants may penetrate into the housing during cleaning and cause damage to electronics and plug connections. Perhaps the damage does not appear right away, but can later on develop into e.g. inexplicable interruptions or break-down of the control unit.
EP 0 660 452 to LINAK A/S discloses a union nut having locking means for a plug, where the union nut is divided into two parts, where the first part forms an almost closed circle, and a second part serves to close the circle and surround the plug and lock this against a locking pin on the housing. The solution is usable, but nevertheless not quite practical, as the union nut has to be mounted after the insertion of the plug into the socket and is thereupon locked by inserting the locking means. As the mounting of cables is often carried out when the control unit or the actuator is mounted on the piece of furniture, it causes a good deal of time-consuming inconvenience. Further, there is a possibility that the many components may disappear, causing them not to be mounted, which results in the known disadvantages.
The object of the invention is to provide a simple solution to the outlined problem.


A method of performing data/information recording and retrieval utilizing a multilevel patterned magnetic medium, comprises providing a magnetic recording system including a read/write head and a multilevel patterned magnetic recording medium including a plurality of spaced apart data/information storage elements each comprising a stacked plurality n of magnetic recording cells with different magnetic properties and magnetically decoupled from overlying and/or underlying cells; providing relative movement between the write head and magnetic recording medium; and writing to the medium by supplying the write head with a modulated write current comprising a plurality n of pulses of different magnitudes while the head passes over each element, thereby applying n different magnetic field strengths to each element, such that the writing occurs in a single pass of the write head over each element.

Designers, manufacturers and users of electronic computers and computing systems require reliable and efficient equipment for storage and retrieval of information in digital form. Conventional storage systems, such as magnetic disk drives, are typically utilized for this purpose and are well known in the art. However, the amount of information that is digitally stored continually increases, and designers and manufacturers of magnetic recording media work to increase the storage capacity of magnetic disks.
In conventional magnetic disk data/information storage, the data/information is stored in a continuous magnetic thin film overlying a substantially rigid, non-magnetic disk. Each bit of data/information is stored by magnetizing a small area of the thin magnetic film using a magnetic transducer (write head) that provides a sufficiently strong magnetic field to effect a selected alignment of the small area (magnetic grain) of the film. The magnetic moment, area and location of the small area comprise a bit of binary information which must be precisely defined in order to allow a magnetic read head to retrieve the stored data/information.
Such conventional magnetic disk storage media incur several drawbacks and disadvantages which adversely affect realization of high areal density data/information storage, as follows:
(1) there are an infinite number of possibilities for the magnetic moments of the continuous magnetic film and, as a consequence, the write head must be able to write very precisely in order to precisely define, without error, the magnetic moment, location and area of each bit on the magnetic film;
(2) since the continuous film tends to link exchange and magnetostatic interaction between neighboring magnetic bits, when the bits are very close, writing of one bit can result in writing of neighboring bits because of the exchange and magnetostatic interaction, causing errors in reading;
(3) the absence of physical boundaries between many bits of the continuous magnetic film cause the writing and reading process to occur in a "blind" fashion, i.e., the location of each bit is determined by calculating the movements of the disk and the read or write heads instead of physically sensing the actual bit location;
(4) the boundaries between adjacent pairs of bits tend to be ragged in continuous magnetic films, resulting in noise generation during reading; and
(5) the requirement for increased areal recording density has necessitated a corresponding decrease in recording bit size or area. Consequently, recording bit sizes of continuous film media have become extremely minute, e.g., on the order of nanometers (nm). In order to obtain a sufficient output signal from such minute bits, the saturation magnetization (Ms) and thickness of the film must be as large as possible. However, the magnetization quantity of such minute bits is extremely small, resulting in a loss of stored information due to magnetization reversal by "thermal fluctuation", also known as the "superparamagnetic effect".
Regarding item (5) above, it is further noted that for longitudinal type continuous magnetic media, wherein the magnetic easy axis is oriented parallel to the film plane (i.e., surface), magnetization reversal by the superparamagnetic effect may occur even with relatively large magnetic particles or grains, thereby limiting increase in areal recording density to levels necessitated by current and future computer-related applications. On the other hand, for perpendicular type continuous magnetic media, wherein the magnetic easy axis is oriented perpendicular to the film plane (i.e., surface), growth of the magnetic particles or grains in the film thickness direction increases the volume of magnetization of the particles or grains while maintaining a small cross-sectional area (as measured in the film plane). As a consequence, onset of the superparamagnetic effect can be suppressed for very small particles or grains of minute width. However, further decrease in grain width in perpendicular media necessitated by increasing requirements for areal recording density will inevitably result in onset of the superparamagnetic effect even for such type media.
The superparamagnetic effect is a major limiting factor in increasing the areal recording density of continuous film magnetic recording media. Superparamagnetism results from thermal excitations that perturb the magnetization of grains in a ferromagnetic material, resulting in unstable magnetization. As the grain size of magnetic media is reduced to achieve higher areal recording density, the superparamagnetic instabilities become more problematic. The superparamagnetic effect is most evident when the grain volume V is sufficiently small such that the inequality Kμ V/kBT>40 cannot be maintained, where Kμ is the magnetic crystalline anisotropy energy density of the material, kB is Boltzmann's constant, and T is the absolute temperature. When this inequality is not satisfied, thermal energy demagnetizes the individual magnetic grains and the stored data bits are no longer stable. Consequently, as the magnetic grain size is decreased in order to increase the areal recording density, a threshold is reached for a given Kμ and temperature T such that stable data storage is no longer possible.
So-called "patterned" or "bit-patterned" magnetic media (the former expression will generally be utilized herein) have been proposed as a means for overcoming the above-described problems associated with continuous magnetic media, e.g., as disclosed in U.S. Pat. Nos. 5,820,769 and 5,956,216, the entire disclosures of which are incorporated herein by reference. In this context, the term "patterned" media refers to magnetic data/information storage and retrieval media wherein a plurality of discrete, independent regions of magnetic material form discrete, independent magnetic elements that function as recording bits are formed on a non-magnetic substrate. Since the regions of ferromagnetic material comprising the magnetic elements are independent of each other, mutual interference between neighboring elements can be minimized. As a consequence, patterned magnetic media are advantageous vis-a-vis continuous magnetic media in reducing recording losses and noises arising from neighboring magnetic bits. In addition, patterning of the magnetic layer advantageously increases resistance to domain wall movement, i.e., enhances domain wall pinning, resulting in improved magnetic performance characteristics.
Generally, each magnetic element has the same size and shape, and is composed of the same magnetic material as the other elements. The elements are arranged in a regular pattern over the substrate surface, with each element having a small size and desired magnetic anisotropy, so that, in the absence of an externally applied magnetic field, the magnetic moments of each discrete magnetic element will be aligned along the same magnetic easy axis. Stated differently, the magnetic moment of each discrete magnetic element has only two states: the same in magnitude but aligned in opposite directions. Each discrete magnetic element forms a single magnetic domain and the size, area and location of each element or domain is determined during the fabrication process.
During writing operation of such patterned media, the direction of the magnetic moment of the single magnetic domain or element is flipped along the easy axis, and during reading operation, the direction of the single magnetic domain or element is sensed. The direction of the magnetic easy axis of each single magnetic domain or element can be parallel or perpendicular to the surface of the domain or element, corresponding to conventional continuous longitudinal and perpendicular media, respectively. Stated differently, the nature (i.e., type) of the magnetic recording layer of the magnetic domains or elements is not critical in patterned media, and may, for example, be selected from among longitudinal, perpendicular, laminated, anti-ferromagnetically coupled (AFC), granular, superlattice, types.
Patterned media in disk form offer a number of advantages relative to conventional disk media. Specifically, the writing process is greatly simplified, resulting in much lower noise and lower error rate, thereby allowing much higher areal recording density. In patterned disk media, the writing process does not define the location, shape and magnetization value of a bit, but merely flips the magnetization orientation of a patterned single element or domain. Writing of data can be essentially perfect, even when the transducer head deviates slightly from the intended domain or element location and partially overlaps neighboring domains or elements, as long as only the magnetization direction of the intended domain or element is flipped. By contrast, in conventional magnetic disk media, the writing process must define the location, shape and magnetization of a bit. Therefore, with such conventional disk media, if the transducer head deviates from the intended location, the head will write to part of the intended bit and to part of the neighboring bits. Another advantage of patterned media is that crosstalk between neighboring domains or elements is reduced relative to conventional media, whereby areal recording density is increased. Each individual magnetic element or domain of a patterned medium can be tracked individually, and reading is less jittery than in conventional disks.
As indicated above, the escalating requirements for increased data/information storage capacity necessitate development of magnetic media with ultra-high areal recording density. In order to achieve a recording density of about 1 Tbit/in2 with patterned media, a nanostructure array of magnetic elements, domains, or "dots" (as with circular columnar-shaped elements or bits) with a period of about 25 nm over a full-patterned 2.5″ diameter disk surface is required. While fabrication methods supporting element or dot densities up to about 300 Gbit/in2 have been demonstrated, large area ultra-high density magnetic element patterns necessary for Tbit/in2 recording densities are currently unavailable or not achievable in a cost effective manner.
The use of multiple level (multilevel) magnetic storage media has been proposed as a means for increasing the areal storage density of continuous media (see, e.g., U.S. Pat. No. 5,583,727, the entire disclosure of which is incorporated herein by reference) and bit patterned media (see, e.g., M. Albrecht, et al., J. Appl. Phys. 97, 103910 (2005) or U.S. Pat. Nos. 6,865,044 B1, 6,882,488 B1, 6,906,879 B1, 6,947,235 B2, the entire disclosures of which are incorporated herein by reference). Multilevel patterned media offer an advantage over single level patterned media in that an increase in areal recording density is possible without further increase in element density, thereby facilitating manufacture. A disadvantage inherent with practical use of the multilevel continuous film media of e.g., U.S. Pat. No. 5,583,727, is that the number of magnetic grains, and hence the read signal and media noise, are divided into the multiple levels, thereby degrading the signal-to-media noise ratio (SMNR).
On the other hand, in multilevel patterned media comprising elements with a stacked plurality of magnetic cells, each cell including a magnetic recording layer is magnetically decoupled from overlying or underlying cells by non-magnetic spacer layers. Therefore, in the case of patterned media comprising a stack of cells with perpendicular magnetic recording layers of different coercivity, each cell of an element can have a magnetization moment or direction in one of two distinct directions, i.e., into or out of the plane of the magnetic layer of the cell, and this magnetization direction is independent of the magnetization direction of the other cells of that element. As a consequence, multiple magnetic states can be recorded in each element. In contrast with multilevel continuous film media, because each cell of the element constitutes a single magnetic domain, there is no increase in noise due to the multiple magnetic cells or levels. The plurality of magnetic cells or levels stacked in the bit or element generates a corresponding plurality of different readback signal levels, whereby the areal recording density is increased.
However, a disadvantage of the proposed scheme for utilizing multilevel patterned media arises from the requirement that each level be addressed individually. Stated differently, multiple passes of the write head over the media are necessary for writing data to each level. However, it is evident that, for such a write procedure, the data rate disadvantageously incurs a substantial decrease.
In view of the foregoing disadvantage/drawback associated with the use of multilevel patterned media, which disadvantage/drawback constitutes an impediment to implementation of multilevel media technology and methodology in ultra-high areal recording density applications, there exists a need for improved methodology that eliminates, or at least mitigates, the existing requirement for multi-pass writing of multilevel patterned media.

Single-pass recording of multilevel patterned media

The Bank of Nova Scotia, as Administrative Agent


An electronic telecommunications module has circuit components and conductors forming a telecommunications circuit having insertion points at which signals can be applied for test purposes and monitoring points from which responses can be tapped. The insertion and monitoring probes are mounted on the module and are connected to the respective points by shielded microcoaxial cables and the probes are connected by shield and microcoaxial cables on the connectors to allow interfacing between the particular module and the testing and diagnostic system.

A module is known from U.S. Pat. No. 5,252,914 which can be connected to such a system,
In electronic telecommunications equipment (e.g. switching exchanges) it is often necessary to check and test the behavior of the equipment or of parts thereof, both during the testing phase and during its regular operation. One of the tests carried out on the system consists in creating fault conditions and in monitoring and analyzing the response of the equipment. The fault condition is generally obtained by forcing some points of the equipment to a pre-set signal level, e.g. corresponding to logic 0 or logic 1, depending on the manufacturing technology employed for the logic circuits mounted on the module. Other tests may require injecting current noisew.
Hereinafter, the terms "actuation" (with no other specifications) or "signal insertions" shall be used to indicate both fault actuation and noise injection.
Tests need to be automated, and this requires that the equipment parts to be tested (hereinafter referred to as "modules") may be associated, at least temporarily, with interfacing means which on the one hand are driven by a testing and diagnosing system sending the signal insertion commands in a programmed fashion, and which on the other hand transfer the responses of the modules to the testing and diagnosing system. During the tests it is necessary to obtain conditions exactly corresponding, from the electrical point of view, with those which may occur during equipment operation, the normal operation of the equipment must not be disturbed in the absence of signal insertion and, conversely, the insertion commands and the responses must not be altered by signals present in a module under test. Moreover, mounting the interface means on the module must not require modifications to the construction or design of the module.
In the above-mentioned prior art In U.S. Pat. No. 5,252,914 which concerns a transceiver on a circuit board with a series of modules, diagnosis is carried out by coupling test equipment to some pins of the permanent connectors of the circuit board and additional pressure pins placed so as to provide for connections with the input and output pins of the modules on the board. The diagnosis facilities are thus restricted to what can be tested by contacting these pins.

Constructive module of an electronic telecommunications equipment, with an interface towards a testing and diagnosing system

Cselt- Centro Studi E Laboratori Telecomunicazioni S.p.A.


A tension-adjusting mechanism for the elongated earpieces of a stethoscope comprises a neckpiece and, for each earpiece, a pivot mechanism portion between the proximal end of the earpiece and the neckpiece, a spring mechanism portion between the proximal end of the earpiece and the neckpiece, and a tension-adjusting mechanism portion between the spring member and the neckpiece. For each earpiece, the pivot mechanism portion defines a pivot axis about which the earpiece pivots, and the spring mechanism portion comprises a resilient blade deforming upon spreading apart of the earpieces. This deformation produces a tension on the earpieces opposing to further spreading apart thereof. The tension-adjusting mechanism portion defines a plurality of interchangeable point of contacts with the resilient blades, which contact points having different positions relative to the neckpiece.

1. Field of the Invention
The present invention relates to a tension-adjustable mechanism for the earpieces of a stethoscope. The present invention also relates to a stethoscope headset comprising this mechanism.
2. Brief Description of the Prior Art
A tension-adjustable mechanism for the earpieces of a stethoscope has been proposed in the following prior art patent:
U.S. Pat. No. 5,561,275 (Savage et al.) Oct. 1, 1996
According to this prior art mechanism, the two earpieces comprise respective weakened proximal end portions inserted side by side in a longitudinally movable sleeve. Longitudinal movement of the sleeve on the weakened end portions of the earpieces change the amplitude of the tension on the earpieces when these earpieces are spread apart from each other.
Although this prior art tension-adjusting mechanism is efficient, further adjustment capability is often required to meet with the requirements, needs and/or preferences of a wide range of users.
Therefore, need exists for a more versatile tension-adjusting mechanism capable of fulfilling the requirements, needs and/or preferences of a wide range of users.
In accordance with the present invention, there is provided a tension-adjusting mechanism for an elongated stethoscope earpiece having a proximal end. This tension-adjusting mechanism comprises a stethoscope neckpiece, a pivot mechanism portion, a spring mechanism portion, and a tension-adjusting mechanism portion. The pivot mechanism portion is interposed between the proximal end of the earpiece and the neckpiece, and defines a pivot axis about which the earpiece pivots relative to the neckpiece. The spring mechanism portion is interposed between the proximal end of the earpiece and the neckpiece, and comprises a spring member which deforms upon pivoting of the earpiece about the neckpiece in an outward direction. Deformation of the spring member produces a tension on the earpiece opposing to further pivoting of the earpiece in the outward direction. Regarding the tension-adjusting mechanism portion, it is interposed between the spring member and the neckpiece and defines a plurality of interchangeable point of contacts with the spring member. These points of contacts with the spring member have different positions relative to the neckpiece.
The above mentioned pivot mechanism portion, spring mechanism portion, and tension-adjusting mechanism portion provide for the level of versatility required to fulfill the requirements, needs and/or preferences of a wide range of users.
Preferably, the pivot mechanism portion comprises abutment surfaces restricting, by abutment, free pivotal movement of the earpiece about the neckpiece within given limits.
According to other preferred embodiments of the tension-adjusting mechanism:
the pivot mechanism portion comprises a pivot pin pivotally mounted on the neckpiece, and a pivot tube pivotally mounted on the pivot pin and connected to the proximal end of the earpiece;
the spring member comprises a resilient blade having one end formed with the pivot pin;
the pivot tube has an open, axial slot through which the resilient blade extends when the pivot pin is inserted in that pivot tube, the resilient blade has a thickness, and the slot has a width larger than the thickness of the blade to allow limited pivotal movement of the pivot tube about the pivot pin; and
the pivot tube has an annular end face provided with a lug, the neckpiece has a pair of abutment surfaces situated on opposite sides of the lug, and the lug abuts on either abutment surface to restrict pivotal movement of the pivot tube about the neckpiece within predetermined limits.
The present invention further relates to a headset for electronic stethoscope, comprising first and second elongated stethoscope earpieces each having a proximal end, and the above described tension-adjusting mechanism for each elongated stethoscope earpiece.
Preferably, the stethoscope neckpiece is common to both the first and second elongated stethoscope earpieces, the neckpiece comprises a hollow shell formed with openings for the proximal ends of the earpieces, and the hollow shell comprises a front shell portion and a rear shell portion assembled together to form that hollow shell.
In accordance with a preferred embodiment:
the resilient blade associated to the first earpiece has a first distal end section opposite to the pivot pin;
the resilient blade associated to the second earpiece has a second distal end section opposite to the pivot pin;
the tension-adjusting mechanism portion associated to both the first and second earpieces comprises a tension-adjusting cam having a geometrical axis, rotatable about this geometrical axis and lockable in either first, second and third angular positions;
the tension-adjusting cam comprises an axial member having an outer tubular surface and two first points of contact with the first and second distal end sections, respectively, formed by two points of this outer tubular surface, respectively, when the tension-adjusting cam is locked in the first angular position;
the axial member of the tension-adjusting cam comprises, on its outer tubular surface, first and second diametrically opposite, axial and radial fins of intermediate height having respective first and second free axial edge surfaces, and two second points of contact with the first and second distal end sections, respectively, formed by these first and second free axial edge surfaces of the first fin, respectively, when the tension-adjusting cam is locked in the second angular position;
the axial member of the tension-adjusting cam comprises, on its outer tubular surface, third and fourth geometically opposite, axial and radial fins of larger height with third and fourth free axial edge surfaces, respectively, and two third points of contact with the first and second distal end sections, respectively, formed by these third and fourth free axial edge surfaces of the second fin, respectively, when the tension-adjusting cam is locked in the third angular position;
the neckpiece comprises a hole with peripheral notches, and the tension-adjusting cam comprises lugs engaging the peripheral notches of the hole in the neckpiece to lock the tension-adjusting cam in either the first, second and third angular positions; and
the tension-adjusting mechanism associated to both the first and second earpieces comprises a spring element interposed between the neckpiece and the tension-adjusting cam and spring biasing the lugs of this tension-adjusting cam in the notches of the hole in the neckpiece, whereby, to be rotated, the tension-adjusting cam is moved against the spring-biasing force produced by the spring element to disengage the lugs from the notches and is rotated and then released to engage the lugs with other notches.
The foregoing and other objects, advantages and features of the present invention will become more apparent upon reading of the following non-restrictive description of a preferred embodiment thereof, given for the purpose of illustration only with reference to the accompanying drawings.

Tension-adjustable mechanism for stethoscope earpieces


A flexible LED lighting device is disclosed that includes a flexible LED light bar surrounded by a flexible conduit. The flexible LED light bar fits within a inner channel of the flexible conduit in an elongated direction and includes sets of LED arrays on opposed sides of a flexible elongate circuit board formed from a continuous wire band and circuit board segments. Preferably, the flexible conduit includes a tubular outer sleeve that surrounds a tubular inner sleeve and the tubular inner sleeve and LED light bar are cable of being displaced in a radial directions relative to the outer sleeve or in directions that are substantially orthogonal to the elongated direction. The flexible conduit is translucent and/or patterned to diffuse or scatter light emitted from the LED light bar to provide full-body illumination.

Flexible elongated lighting strips with LED arrays or LED light strips have been used for a number of adaptable lighting applications including display lighting, edge or corner lighting and decorative lighting. There are a number of shortcomings with the currently available LED strip light.
Many of the LED strip lights include flexible circuit boards with LEDs mounted to a flattened surface. In some of these LED strip lights, the flexible circuit boards are only flexible in two directions, much like a flattened strip of metal, and are subject to damage when they are bent or twisted in other directions as a result of torsional stresses along the thickness directions.
Other LED strip lights have individual LEDs mounted onto sets of laminated wires. While such wire mounted LED strip lights do allow for more flexibility, making such LED strip lights with larger LEDs is prohibitive because the wires do not provide a stable support for the larger LEDs. Further, with these wire mounted LED strip lights, each LED must be individually soldered or connected to the wires, thereby making a wire mounted LED strip light labor intensive to produce.

Flexible LED device with whole body illumination


A cornice board constructed of a rigid material containing a plurality of openings located on a first side, front face, and second side. These openings may be selectively plugged, by various removable plugs. The rigid cornice board is adaptable to contain a decorative fabric interleaved through the selected plurality of openings in order to create the desired design effect.

Cornice structures have been used to hide valance or blind fixtures. The conventional cornice apparatus is frequently covered with a decorative fabric or material which does not provide flexibility for interior design, and makes changing the covering material difficult once a cornice device has been affixed to a wall. Disassembly and redesign of conventional cornice structures to achieve a new design effect is difficult, time consuming and costly.
Conventional cornice structures are comprised of basic curtain rods or wood frames covered entirely in a decorative fabric. These cornice structures often do not provide an ornamental look or style that improves the interior design of a room, and do not provide decorative flexibility in covering blind fixtures, nor do these devices provide aesthetic or functional utility in creating new interior design effects.
A decorator is unable to easily manipulate the surface designs of conventional cornice boards; the only design option is choice of a covering fabric.
The conventional cornice structure does not provide a convenient, efficient, and cost effective method of modification of a desired design fabric absent disassembly of the cornice unit from the wall. The prior art does not provide the decorator with flexibility in design of decorative cornice compositions.


The present invention provides an improved catalytic fast pyrolysis process for increased yield of useful and desirable products. In particular, the process comprises an improved catalytic fast pyrolysis process for producing aromatic compounds, such as, for example, benzene, toluene and xylenes, from biomass feedstock containing impurities, such as, for example alkali and alkaline earth metal, sulfur and nitrogen components.

Obtaining useful chemicals, fuels, and energy from renewable biomass represents an important challenge as conventional fossil sources of these materials are slowly depleted. Lignocellulosic biomass is being studied widely as a viable feedstock for renewable liquid biofuels and chemicals because of its low cost and global availability. Biomass-derived fuels and chemicals are projected to substantially reduce net CO2 emissions as well, if produced with minimal use of fossil fuels.
To meet this challenge, there have been extensive efforts to convert biomass to fuels and other useful chemicals. Producing fuels and chemicals from biomass requires specialized conversion processes different from conventional petroleum-based conversion processes due to the nature of the feedstock and products. High temperatures, solid feed, high concentrations of water, unusual separations, contaminants, and oxygenated by-products are some of the features of biomass conversion that are distinct from those encountered in petroleum upgrading. Thus, there are many challenges that must be overcome to efficiently produce chemicals from biomass.
Lignocellulosic biomass (wood, grasses, agricultural residues, etc.) is an alternative, renewable, and sustainable source of feed with significant potential to address the increasing demands for alternative liquid fuels and 'green' chemicals. These feedstocks do not directly compete with the food supply, but have limited utility due to their inherent characteristics and storage limitations. Feedstock supply and the logistics of lignocellulosic biomass upgrading are challenging due to the low bulk density, low energy density, and high ash content of the feed. The chemical and physical inconsistencies of feedstocks are substantial barriers that limit the ability of designing a single, widely applicable process for the upgrading of biomass to fuels and chemicals.
Biomass materials generally comprise cellulose (35%-60%), hemicellulose (15%-40%) and lignin (10%-40%) as major components, a variety of lesser organic materials, water, and some mineral or metallic elements. A range of biomass derived materials can be pyrolyzed to produce mixtures of hydrocarbons, oxygenates, CO, CO2, water, char, coke, and other products. A particularly desirable form of pyrolysis is known as catalytic fast pyrolysis (CFP) that involves the conversion of biomass in a fluid bed reactor in the presence of a catalyst. The catalyst is usually an acidic, microporous crystalline material, usually a zeolite. The zeolite is active for the upgrading of the primary pyrolysis products of biomass decomposition, and converts them to aromatics, olefins, CO, CO2, char, coke, water, and other useful materials. The aromatics include benzene, toluene, xylenes, (collectively BTX), and naphthalene, among other aromatics. The olefins include ethylene, propylene, and lesser amounts of higher molecular weight olefins. BTX aromatics are desirable products due to their high value and ease of transport.
The minerals or metallic elements present as contaminants in biomass, sometimes collectively referred to as alkali and alkaline earth elements (AAEMs) although they may contain many other elements, present a challenge to catalytic processes. These elements can deactivate the catalyst or interfere with the smooth operation of a CFP process by a number of mechanisms. It is thus desirable to limit the amount of the AAEMs that are introduced into the CFP process, or remove the AAEMs, or both, in order to provide a commercially viable process for upgrading biomass to fuels and chemicals. Other impurity elements, primarily sulfur and nitrogen, present in biomass are also detrimental to the conversion of biomass to useful chemicals and fuels. Sulfur and nitrogen can inhibit catalyst activity, complicate product purification, and contaminate effluent streams. Processes for removing sulfur and nitrogen are also needed. The present invention addresses methods to reduce impurities including the AAEMs and sulfur and nitrogen in biomass feed to a CFP process.
In U.S. Pat. No. 8,022,260, a process is described that utilizes an activating step of introducing an additive to make a biomass more susceptible to conversion, and then converting the activated biomass to a product comprising bio-oil. Magnesium and aluminum salts are introduced into the biomass in a wet milling step in one example.
U.S. Patent Application Publication 2013/0340746 describes a process for converting AAEMs present in biomass into thermally stable, catalytically inert salts using hydrochloric, sulfuric, or phosphoric acids in preparation for a biomass pyrolysis process.
In U.S. Pat. No. 8,168,840, a process is described comprising: (i) swelling biomass with a solvent, optionally aided by pH control, application of mechanical action, the incorporation of additive(s), and temperature control; (ii) removing solvent from the swollen solid biomass material by applying mechanical action to the solid biomass material to form a solid modified lignocellulosic biomass material having an increased bulk porosity; and (iii) subjecting the solid modified lignocellulosic biomass material to enzymatic hydrolysis, thermoconversion, or combinations thereof. Optionally the material can be modified by incorporation of a soluble catalyst before it is upgraded. Catalytically upgrading of the swollen, modified, and dried biomass in a fixed or fluid bed of solid catalyst is not discussed.
In U. S. Patent Application Publication 2012/0301928, a method is described for pretreating lignocellulosic biomass prior to hydrolysis, comprising: immersing lignocellulosic biomass in water to swell the biomass; wet-milling the swelled biomass; and popping the wet-milled biomass. Neither minerals removal nor catalytic pyrolysis is mentioned. In U.S. Patent Application Publication 2014/0161689, a process is described for digesting biomass to remove sulfur or nitrogen compounds, reforming the resulting solution with a soluble catalyst to form oxygenate compounds, and then catalytically producing a liquid fuel from the reformed solution. In U.S. Pat. No. 8,940,060, a method is described for forming a pyrolysis oil wherein the feed biomass is washed with a portion of the pyrolysis condensate to produce a washed biomass having a reduced level of metals, and thermally pyrolyzing the washed biomass. Catalytic reaction is not discussed.
Experimental results have been presented (see V. Paasikallio, C. Lindfors, E. Kuoppala, Y. Solantausta, A. Oasmaa, "Experiences from an extended catalytic fast pyrolysis production run", Green Chem., 2014, 16, 3549-3559) in which the amount of 'Alkalis' deposition as a function of time on stream in a CFP process showed a linear increase with time. 'Alkalis' are defined to include K, Ca, Mg, and P. After a four day test of pine sawdust catalytic fast pyrolysis with H-ZSM-5 catalyst, the catalyst had accumulated 1.1 weight % of the 'alkali metals' including K, Ca, Mg, and P. The acidity of the catalyst decreased and the O/C ratio of the produced bio-oil increased, which were interpreted to indicate a reduction of catalytic activity. No attempts to remove alkali metals from the feed or from the process were discussed.
Oudenhoven et al in "Demineralization Of Wood Using Wood-Derived Acid: Towards a Selective Pyrolysis Process for Fuel and Chemicals Production" J Anal Appl Pyrolysis 103 (2013) 112-118, describe the use of a raw pyrolysis water product phase to wash biomass prior to a thermal pyrolysis. Increased yields of bio-oil rich in oxygenated products, i.e. levoglucosan, are reported for the washed wood experiments. Catalytic pyrolysis or the production of aromatics was not discussed. By contrast, Kasparbauer in his PhD thesis entitled "The effects of biomass pretreatments on the products of fast pyrolysis" (2009), Graduate Theses and Dissertations, Paper 10064 at Iowa State University, concludes on page 127 that: "The water wash pretreatment showed no significant difference when compared to unwashed biomass in terms of product yields."
It has been often reported that improved yields of useful products are obtained when AAEMs are introduced into, or not removed from, biomass. U.S. Pat. No. 5,865,898 describes a process for "pretreating a lignocellulose-containing biomass comprising the steps of adding calcium oxide or hydroxide and water and an oxidizing agent to the biomass" to obtain better yields of sugars, ketones, fatty acids, and alcohols.
Wang et al have reported that AAEMs reduce the yields of aromatics and olefins in ex situ catalyzed pyrolysis reactions in "The deleterious effect of inorganic salts on hydrocarbon yields from catalytic pyrolysis of lignocellulosic biomass and its mitigation", Applied Energy 148 (2015) 115-120. Their studies used separate pyrolysis and catalytic upgrading reactors to show that pretreatment of the AAEM-infused cellulose can improve aromatics and olefins yields. No attempts were made to react biomass in the presence of a catalyst in a single reactor.
Among other methods of pretreating biomass, wet milling of corn is routinely used in the industry to separate the various components. Typically the hemicellulose and cellulose are hydrolyzed for further upgrading to ethanol or other products. Wet milling is not used for minerals removal. As it is applied in extracting sugars from corn, wet-milling is a process in which feed material is steeped in water, with or without sulfur dioxide, to soften the seed kernel in order to help separate the kernel's various components. The hydrolysis of the hemicellulose and cellulose is detrimental for a feed that will be upgraded by the CFP process of the present invention.
U.S. Pat. No. 7,503,981 teaches the removal of minerals from biomass as part of a biomass saccharification process that produces dimeric and monomeric saccharides (sugars) from cellulose and hemicellulose using sulfuric acid.
Pretreatment of biomass has been developed broadly for the production of monomeric sugars as precursors in fermentation processes to produce ethanol. These pretreatment processes are optimized for the hydrolytic deconstruction of cellulose and hemicellulose, separation of lignin, and the removal of contaminant materials to provide a sugar rich solution for fermentation. For a catalytic fast pyrolysis process in which all of the cellulose, hemicellulose, and lignin contribute to the yield of valuable materials such as BTX, the processes adapted for ethanol are not applicable since in the production and separation of the sugars a very significant amount of organic material is lost in the lignin and other minor components. The yields of BTX obtainable from these deconstructed feeds in a CFP process are fundamentally limited by the loss of carbon.
Conversion of wood or other cellulosic feedstocks into paper has been commercial for more than a hundred years. The Kraft process is the dominant process used to convert wood into wood pulp, which consists of almost pure cellulose fibers. Wood pretreatment processes have been developed to improve the quality of the wood pulp obtained in the subsequent Kraft process. For example, Lundquist et al in "Removal of Nonprocess Elements From Hardwood Chips Prior to Kraft Cooking," presented at the 59th Appita Conference, 16-19 May 2005, in Auckland, New Zealand, reported that a 24-hour acid leaching of birch or eucalyptus chips in sulfuric acid solution of pH 2.5 at room temperature (22° C.) resulted in thorough removal of K ions and partial removal of Ca ions. However, the extremely long leaching times required make the process unacceptable for large scale, continuous or semi-continuous manufacture of chemicals such as BTX.
In light of current commercial practices and the disclosures of art, a simple, economical, rapid process for enhancing production of aromatic compounds, such as, for example, benzene, toluene and xylenes, from a catalytic pyrolysis process utilizing biomass containing impurities such as alkali and alkaline earth metal components, sulfur compounds and/or nitrogen compounds is needed. The present invention provides such a process.

Catalytic fast pyrolysis process with impurity removal


A semiconductor package includes a metal flange having a lower surface and an upper surface opposite the lower surface. An electrically insulating window frame is disposed on the upper surface of the flange. The electrically insulating window frame forms a ring around a periphery of the metal flange so as to expose the upper surface of the metal flange in a central die attach region. A first electrically conductive lead is disposed on the electrically insulating window frame and extends away from a first side of the metal flange. A second electrically conductive lead is disposed on the electrically insulating window frame and extends away from a second side of the metal flange, the second side being opposite the first side. A first harmonic filtering feature is formed on a portion of the electrically insulating window frame and is electrically connected to the first electrically conductive lead.

RF power amplifiers are used in a variety of applications such as base stations for wireless communication systems, etc. The signals amplified by the RF power amplifiers often include signals that have a high frequency modulated carrier having frequencies in the 400 megahertz (MHz) to 60 gigahertz (GHz) range. The baseband signal that modulates the carrier is typically at a relatively lower frequency and, depending on the application, can be up to 300 MHz or higher. Many RF power amplifier designs utilize a semiconductor switching device as the amplification device. Examples of these switching devices include power transistor devices, such as a MOSFET (metal-oxide semiconductor field-effect transistor), a DMOS (double-diffused metal-oxide semiconductor) transistor, a GaN HEMT (gallium nitride high electron mobility transistor), a GaN MESFET (gallium nitride metal-semiconductor field-effect transistor), an LDMOS (laterally diffused metal-oxide semiconductor field-effect transistor) transistor, etc.
Highly power efficiency is an important design consideration in modern RF applications. Class D, E, F and J amplifiers are popular choices in modern RF applications in due to their highly efficient operation. Highly efficient operation is achieved by mitigating harmonic oscillations at the input and the output of the amplifier. For example, in a class F amplifier, the output of the amplifier should ideally present a short circuit path to the even ordered harmonics (e.g., 2F0, 4F0, 6F0, etc.) of the fundamental frequency F0, and the output of the amplifier should ideally present an open circuit to the odd ordered harmonics (e.g., 3F0, 5F0, 7F0, etc.) of the fundamental RF frequency F0. For this reason, harmonic filtering components such as resonators and open circuits can be used to selectively filter harmonic components of the fundamental RF frequency F0.
Known techniques for improving amplifier efficiency include incorporating RF filters into the impedance matching networks of RF amplifiers. These RF filters can be incorporated into the printed circuit board (PCB) level impedance matching network and/or the package level impedance matching network. In either case, the impedance matching networks can include LC filters that are tuned to the harmonics of the fundamental frequency F0 so as to provide an electrical short or open circuit, as the case may be.
One drawback of conventional harmonic tuning designs is that higher order harmonics become increasingly difficult to filter with increasing separation from the current source. For example, in the above described configurations, parasitic reactance of the package level and board level conductors substantially influences the propagation of higher frequency signals. As a result, the ability to tune high frequency harmonics, which may be in the range of 4 GHz or higher in modern RF applications, is very limited at the board level.

Semiconductor package with integrated harmonic termination feature


An electronic building block set with a metal layer on the outer surface of each building block includes a main and an auxiliary building block. The top of the main building block includes plural main hollow posts, each with a main sensing contact, and has a main metal layer on the outer surface. The main sensing contacts and the main metal layer are electrically connected to opposite-polarity main electrode circuits respectively. The bottom of the auxiliary building block includes a first sensing element and has an auxiliary metal layer on the outer surface. The first sensing element and the auxiliary metal layer are electrically connected to opposite-polarity auxiliary electrode circuits respectively. When the building blocks are engaged, the first sensing element is electrically connected to the corresponding main sensing contact, and the auxiliary metal layer, to the main metal layer to enable electricity or signal transmission between the building blocks.

Electronic building blocks are building blocks provided therein with electronic components of different functions such as capacitors, resistors, inductors, and light-emitting diodes. Serving now as a fun teaching aid to encourage learning, they are stackable in various ways so that children can learn the principles of circuitry through the stacking process. In earlier times, however, electronic building blocks were viewed only as a variation of solderless breadboards and therefore were not designed as "smart devices". Most of the former electronic building blocks were capable only of transmitting electricity, meaning they were provided therein with metal conductive components to be connected when a plurality of such blocks are stacked to transmit electricity sequentially through the blocks.
Seeing that the electricity-transmitting building blocks had very limited functions, The Lego Group of Denmark and the Massachusetts Institute of Technology (MIT) of the USA jointly developed "MINDSTORMS", an electronic building block product that includes the "brain" building block RCX, a sensing system (e.g., sensors for sensing such external environment factors as light, temperature, and touch), an infrared communication element, and 700 conventional Lego building blocks. A user can code a software program using a personal computer, transmit the program to the "brain" building block RCX through the infrared communication element, and thereby save the program into the "brain" building block RCX, which is then electrically connected to the sensing system and mounted with the conventional Lego building blocks to form a robot of the desired configuration, in order for the robot to operate according to the user's program and execute the corresponding procedures.
However, the applicant of the present patent application has found that additional transmission lines are required to connect the "brain" building block RCX to the components mounted thereon in order to transmit signals and electricity therebetween. If pulled by accident during operation or while the robot is played with, the transmission lines may break, causing the "brain" building block RCX to malfunction, whose repairment can be costly and time-consuming. The applicant has also found that the "brain" building block RCX as well as a conventional electronic building block capable only of electric power transmission has its contacts for positive-electrode circuits and its contacts for negative-electrode circuits provided on the same circuit board, and that therefore specific assembly modes are essential for proper transmission of electricity but result in difficulties in assembly and hence inconvenient of use. That is to say, while the conventional electronic building blocks advantageously integrate education into fun activities, they still have limitations in use. The issue to be addressed by the present invention is to solve the foregoing problems effectively and provide better user experience.

Electronic building block set with metal layer on outer surface of each building block


A vertically adjustable glass pane for automobiles, especially a door window pane, is of laminated glass consisting of two thermally toughened single glass sheets, each 1.5 to 3 mm thick, and of a thermoplastic intermediate layer. Both the glass sheets have, in their edge region, tensile stresses in the core having a value from 27 to 57 MN/m.sup.2 for a sheet thickness of 1.5 mm and 20 to 47 MN/m.sup.2 for a sheet thickness of 3 mm. In the middle area within the peripheral region the glass sheets have tensile stresses in the core which, in the case of a glass sheet of 1.5 mm thickness, have values of 25 to 42 MN/m.sup.2 and, with a glass thickness of 3 mm, values of 17.5 to 33 MN/m.sup.2. Laminated glass panes of this type have a comparatively high strength in the peripheral region and low strength in the middle area. They possess excellent properties both from a structural design standpoint and also from the standpoint of safety in case of accident.

Field of the Invention
This invention relates to an automobile glass pane, especially a vertically adjustable side pane of laminated glass composed of two thermally toughened single glass sheets, bonded together by a thermoplastic intermediate layer.
Description of the Related Art
An automobile glass pane which can be lowered of this type is known from DE-GM 89 10 916. In this known lateral pane, the outer glass sheet of the laminated glass pane has a thickness of 3 to 4 mm and possesses, as a whole, the usual prestress of a monolithic safety glass pane. The inner glass sheet of the laminated pane has a thickness of 1.5 to 2.5 mm and has no, or very little, prestress. The inner glass sheet also has smaller dimensions than the outer, prestressed glass sheet, and the projecting edge region of the prestressed outer glass sheet serves for guiding the laminated pane in the guide rails of the window frame. The two glass sheets are bonded together by means of a film of thermoplastic 0.8 to 2.0 mm thick.
This known glass pane, as a consequence of its construction, is to a large extent burglar-proof and also has good acoustic insulation properties. The burglar-resistant and penetration-resistant effect is based both upon the relatively thick thermoplastic intermediate layer and upon the feature that the not, or only slightly, prestressed inner glass is not destroyed even if the outer toughened glass sheet is destroyed, due to the thick intermediate film or, in the case of destruction, breaks only into very large fragments so that the window opening in all cases remains closed. This means, however, that even in those cases in which it is necessary to break through the side window panes, namely in the case of an accident, the high resistance of this known lateral glass pane impedes rapid breakage and thereby rapid access to the occupants of the automobile.
In DE-P 40 27 035, which is not admitted to be prior art except as required under 35 U.S.C. 102, each glass sheet in an automobile glass pane of laminated glass has a thickness of 2.0 to 3.0 mm and a prestress lower than the prestress of monolithic safety glass and varying over the area of the glass sheet in such a way that, all around in the edge region, the average tensile stress in the core is 5 to 15% lower than the tensile stress required for breakage behavior in accordance with the standards for the same thickness of pane and that, in the region of the pane area within this edge region, the average tensile stress in the core is 20 to 40% lower than the tensile stress required for breakage behavior in accordance with the standards for the same thickness of pane.
Corresponding to these lower prestress values, which differ from the edge to the central region in these laminated glass panes, the tensile stresses in the core, for a thickness of the glass sheets of 2.0 mm, are 54 to 76 MN/m.sup.2 in the edge region and, with increasing thickness, decrease linearly to 46.7-71.2 MN/m.sup.2 for a sheet thickness of 3 mm, and in the central region, for a glass sheet 2 mm thick, have the values 38 to 64 MN/m.sup.2 and decrease linearly with increasing thickness down to 33-60 MN/m.sup.2 for a sheet thickness of 3.0 mm.
A laminated glass pane having this stress arrangement of its individual glass sheets has the advantageous characteristic that compared with a laminated glass pane of fully prestressed glass sheets, the strength in the middle area of the laminated pane has been reduced to a sufficient extent that, in emergency, the laminated glass pane can be pressed inwards from outside and thus the window opening can be exposed comparatively quickly. Whereas the central region of the two single glass sheets of the laminated glass pane then breaks into very large pieces, and the edge zone disintegrates into comparatively small fragments, which facilitates the removal of the laminated pane from its mounting. The reduction in the strength in the central zone also has a favorable effect, in the case of collision accidents, upon the biomechanical properties of the laminated glass pane, whereas the comparatively higher prestress in the edge zone has the favorable effect that the laminated pane withstands the higher mechanical loadings in the edge region without problems.

Vertically adjustable lateral glass pane for automobiles


An alarm panel of a security system is additionally provided with an interference circuit for evaluating the possible presence of a large electromagnetic interference signal such as lightning. The earth ground connection of the alarm panel to a power source is used to provide an input to the interference circuit. The earth ground connection receives large transient signals caused by such naturally occurring events. The alarm panel uses this additional information to modify the reporting of alarm conditions. This has particular application for addressing problems associated with motion detectors falsely triggering when a large electromagnetic signal is received. The solution of the alarm panel sensing this condition in contrast to each detector sensing this condition is more reliable, allows combining of detector information and is more cost effective.

It is now common for businesses and homeowners to have a security system for reporting of alarm conditions to a security station. One of the primary functions of such a security system is to provide an alarm report to the security station when the owner is absent and one or more of the detectors reports an alarm condition. The type of detectors vary from relatively simple hard wired detectors, such as door or window contacts, to more sophisticated battery operated sensors such as motion and glass break detectors.
The security alarm system located in the premise being protected includes a series of different types of sensors all of which report to an alarm control panel. The control panel is typically installed in a safe location and is directly connected to the power supply. The alarm control panel is connected either by hardwires to the individual sensors or communicates or receives signals from individual detectors as part of a wireless communication. The communication between the alarm panel and the sensors can be a one way communication where the detectors merely transmit to the alarm panel or can be two way communication.
It is known that certain natural events can cause some sensors, in particular motion sensors and glass breakage sensors to falsely trigger. Lightning produces a broadband electromagnetic signal which produces a signal in the detector or causes a change in the monitored space leading to a false activation of the detector. Thunder associated with lightning can also cause a large acoustic signal which can lead to false alarms. Lightning and thunder are two examples of naturally occurring events which produce high energy which can lead to false alarms in security detectors.
The occurrence of false alarms is a major concern to the security industry. As can be appreciated, naturally occurring events such as lightning typically do not affect a single alarm system but affect a number of alarm systems in a certain proximity to the natural occurring event. The alarm panels report to the security system the detection of an alarm condition which is then processed by the security station. Processing of each false alarm incurs a certain expense but more importantly, it also reduces the confidence that a reported alarm condition is in fact an alarm condition which requires prompt investigation.
To overcome the above problems, some motion detectors have been provided with additional circuitry for detecting a naturally occurring event such as lightning. U.S. Pat. No. 5,920,259 discloses a motion detector unit having additional circuitry for detecting the occurrence of lightning. Basically, the detector circuitry acts as a receiver and produces a signal of a magnitude to the sensor when exposed to the electromagnetic signal caused by lightning. To overcome this problem, each detector is provided with redundant circuitry which is also affected by this electromagnetic interference. By subtracting the signal from the motion sensor circuitry from the signal of the redundant circuit, the effect of the electromagnetic signal is eliminated or reduced.
Unfortunately, this arrangement requires each motion detector to include additional redundant circuitry and additional processing of the signals from the two different circuits. This significantly adds to the cost of each sensor, thereby increasing the cost of the overall system.
U.S. Pat. No. 5,977,762 discloses a lightning detector suitable for protection of electronic equipment in a home. The detector receives an electromagnetic signal, through an antennae and applies signal conditioning to produce a series of pulses corresponding to peaks in the signal above a specified threshold. The pulse data is compared with a predetermined criteria that distinguishes lightning produced interference from other electrical interference.
It has been recognized that certain natural occurring events produce electromagnetic interference or radio frequency interference which negatively affect the performance of motion detectors and security systems.
There remains a need to provide a cost effective solution for reducing or modifying the processing of signals from an alarm system when such interference is detected.


Optical polishing pitch formulations include synthetic polymers or other synthetic resins. As alternatives to traditional optical pitches, these materials offer improved stability in use, storage, and processing. In addition, these pitch compositions may be masterbatched and manufactured with precision to ensure superior reproducibility and quality control in polishing performance.

In the fabrication of precision optical components (telescope mirrors, lenses for imaging systems, laser windows, etc.), achievement of surface form and finish is critical. To rough out the basic optical form, any number of processes may be employed including diamond machining, abrasive grinding, or even molding. Such processes, however, produce only imprecise surface form and leave a rough surface finish. Even extremely fine grinding, using grit sizes in the few micron range, yields a microscopically pitted and frosty surface. Precision optical fabrication, therefore, requires a finishing step to achieve near molecular level smoothness and extreme accuracy in final surface figure. This final operation, commonly referred to as polishing, is generally critical within the field of precision optical fabrication.
Within the last few decades, tremendous advances have been made in the general art of surface polishing. Techniques such as chemical mechanical planarization (CMP) are now available for economical achievement of nanometer scale smoothness in semiconductor manufacturing. For optical polishing, magnetorheological finishing has proven value in specific precision finishing applications. For the manufacture of most precision optical components, however, traditional lap polishing remains the most economical and viable approach.
Remarkably, Sir Isaac Newton is credited with inventing the lap polishing method, which in essential respects is the basis for most modern precision optical finishing. Newton found that although fine grinding leaves optical surfaces microscopically pitted, an incredibly smooth finish might be obtained on glass (and like surfaces) if worked against a pitch material in the presence of a slurry containing soft abrasive particles. In the roughly 300 years since Newton originally published this technique, the basic methodology has become a staple optical finishing technique.
In pitch lapping, a hard support is typically coated with a layer of natural pitch, comprised of pine rosin or petroleum based resin, to form a lap of cut or molded pitch facets. Often, the pitch is melted, cast directly onto the support, cut into facets or, in some other fashion, molded into facets attached to the rigid support. Pitch, formulated for this application, displays slow creep or flow under the action of stress (although it outwardly appears as a hard resinous solid much like amber or hard sugar candy). Pressed against an optical workpiece, pitch facets slowly conform to provide an intimate mate with the surface. Subsequent working against the lap, in the presence of a particle slurry leads to charging of the lap surface with embedded particles. As a result, particles entrapped at the pitch surface are delicately dragged over the work and, through complex mechanisms, smooth the surface to produce an extremely high polish. Beyond polishing, lapping also delicately removes material from the optical surface and, thus, enables extremely fine adjustment of surface figure at the final stages of finishing.
Although the underlying mechanisms of pitch polishing remain a subject for investigation, pitch flow or creep is accepted as an important enabling phenomenon. Apparently, flow of the lap to mate with the optical surface is needed for the achievement of both uniform polish, and control of surface figure. Certainly, it is widely accepted that materials, which do not flow and conform to the optical work must either be preconditioned to provide conformance, or produce poor polishing results. Waxes, for example, produce a polishing effect but often with characteristic non-uniform lemon peel texture. Materials such as TEFLON fluorocarbon polymers may also be used for lapping but only following exhaustive diamond conditioning to provide close mating. Flow in pitch, thus, offers a practical means to achieve intimate microscopic lap mating and consequent polishing uniformity/control.
Due to the importance of flow in lap performance, optical polishing pitches are commonly formulated to possess levels of flow appropriate for a given application. The so called hardness of a pitch, or its resistance to flow in response to stress, is determined by mixing resins with different characteristics or plasticizing a given material with additives. Generally, pine rosin, plasticized with turpentine or other similar materials, has long been used as a polishing pitch. For example, one published account of a pitch formulation containing pine rosin dates back to the 1940s.
Currently, several brands of optical polishing pitch, blended to achieve different levels of hardness, are available commercially. Swiss manufactured GUGOLZ pitches, based on proprietary pine derivatives, are used extensively within the field of precision optics. Universal Photonics, Inc. of Hicksville, N.Y., also offers similar polishing pitches formulated across a very broad range of hardness. Beyond pine derivatives, Cycad Products, of Las Vegas, N. Mex., offers a range of pitches based on proprietary petroleum refining residuals and these pitches also find specific applications in optical finishing.
While the use of pine and petroleum resins as a base for optical polishing pitches has a long history, associated technology has specific limitations, which are addressed by the current invention.
Pine based pitches are typically derived from gum pine rosin, or similar related materials which, chemically, are largely comprised of materials refined from the sap of pine trees. While these materials are dominantly comprised of resin acids (such as abietic acid), exact weight distribution among these acids vary and many residual compounds are present depending on pine species, harvest location, and growing conditions. Consequently, the exact chemical makeup of pitches thus derived is difficult to control and, inherently, comprises an extremely complex blend of compounds, which are difficult to reproduce consistently over time. Similarly, petroleum based pitches, derived from refining residuals, contain a complex blend of isomers, oligimers, cyclic anthracitic compounds, and the like, depending on exact crude source.
While in principle it is possible to manufacture consistent optical pitches derived from either pine resin or petroleum pitch, chemical complexity and inconsistency in raw natural constituents present significant practical barriers the achievement of precise physical properties. Pine derivatives from a given source, such as Hercules, Inc. in Brunswick, Ga., for example, contain variable fractions of low molecular weight compounds, which, like turpentine added to deliberately induce creep characteristics, induce varying levels of hardness. Since even a fraction of one percent (by weight) of low molecular weight constituents changes flow characteristics dramatically, precise blending with additives to achieve precise pitch hardness is hampered by associated variability. Similarly, pitches derived from petroleum residuals contain small fractions of low molecular weight compounds, which vary in concentration and composition, leading to analogous difficulty in precision control of hardness.
Variability in the physical properties of natural pitches, particularly hardness, is a serious issue in the manufacture of precision optics. Since reproducibility in polishing operations depends upon the properties of the pitch employed, lot-to-lot variability in pitch characteristics translates into costly and unwanted process troubleshooting.
Notwithstanding ongoing efforts to characterize and track the lot-to-lot properties of existing natural pitches, variability is a major current issue for most manufacturers of precision optics. While quality control measurements of natural pitch characteristics may be employed to select and screen lots of material for a given finishing operation, such screening is time consuming and generally costly. Consequently, lower variability alternatives would represent a fundamental advancement in the art of optical polishing.
Beyond the issue of chemical purity and consistency in manufacture, existing pine and petroleum pitches are relatively unstable both during melt molding to produce laps and in use. Since the base resins typically comprise low molecular weight components, melting or long-term exposure to air can lead to significant changes in hardness due to loss of low boiling volatiles. For this reason, opticians must take great care in the melting of pitch (to fabricate laps) such that exposure to high temperature and drying/hardening of the material is limited. In addition, laps constructed of such pitches have a limited life in part due to drying of volatiles from the material and consequent hardening.
It is also important to recognize that many existing natural pitch formulations, particularly those comprising pine derivatives, are subject to reactions with oxygen over time. Most pine derivatives, for example, become rancid much like unsaturated fats or cooking oils, within a few weeks on exposure to air due to oxidative reactions. Although formulation with additives may inhibit such reactions to some extent, oxidation is another inherent instability associated with natural resins.
In large part due to the above issues, current practitioners in the art of pitch polishing face many practical complexities and must, in general, develop considerable formulation and processing expertise to achieve success. Blending of different commercial pitches is often required to overcome variability in hardness and or polishing performance. All too often, trial and error blending to modify hardness, enhance surface wetting, or insure proper charging with polishing agents, is necessary. In addition, extreme care is required in molding of natural pitches to prevent, degradation or drying of the material during melt processing, requires considerable care and experience. While many opticians have developed remarkable skill and intuition in the general art of pitch manipulation, more stable and pure materials, having precise and controlled properties, would enable more systematic, and less costly, optical process engineering. In general, the ability to scientifically formulate exact hardness targets, utilizing materials having known chemistry in combination with additives yielding well-characterized effects, would be of great value in many optical polishing applications.
What is needed, therefore, are pitch materials comprising chemically pure substances, which may be precisely formulated to yield precision control of physical properties including pitch hardness. In addition, such materials are needed which do not contain significant volatile content and, thus, are not susceptible to drying over time or during melt processing. Finally, optical polishing pitches, which are impervious to oxidation on exposure to air, are generally needed in the art.