The invention relates to substituted 2-aminoimidazoles and their imidazo[1,2-a]pyrimidinium salts precursors being active against biofilm formation. The invention also relates to imidazo[1,2-a]pyrimidinium salts bearing an azidoalkyl substituent, and to substituted 2-aminoimidazoles wherein the amino group bears a terminal heterocyclic group such as a triazolyl group which are formed through azide-alkyne Huisgen cycloaddition starting from said imidazo[1,2-a]pyrimidinium salts bearing an azidoalkyl substituent. The invention also relates to a class of N-(azidoalkyl)pyrimidin-2-amines useful as starting materials for the synthesis of said imidazo[1,2-a]pyrimidinium salts bearing an azidoalkyl substituent. The invention also relates to antimicrobial compositions that include a microbial biofilm formation inhibiting amount of such substituted 2-aminoimidazoles or imidazo[1,2-a]pyrimidinium salts in combination with excipients. Methods for inhibiting or controlling microbial biofilm formation in a plant, a body part of a human or an animal, or a surface with which a human or an animal may come into contact are also disclosed.

Biofilms are defined in the art as structured communities or aggregates of microorganisms (e.g. bacterial cells) in which cells adhere to each other and/or to a living or inert (non-living) surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance. Biofilms represent a prevalent mode of microbial life in natural, industrial and hospital settings. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism. Biofilm cells exhibit profound changes in gene expression and cell physiology compared with planctonic cells, and multiple genetic pathways mediate the regulation of biofilm formation. Microorganisms in biofilms form microbial colonies or condominiums that make it easy to carry out chemical reactions that are impossible for individual microbial cells. Biofilms can contain many different types of microorganism, e.g. bacteria, archaea, protozoa, fungi and algae.
The use of effective antimicrobial compositions to avoid biofilm formation is recommended for any surface in contact with water, such as swimming pool liners, water cooling surfaces, hoses, water dispensers, water storage and distribution systems for drinking water or aquaculture, and for surfaces of medical devices such as catheters, medical implants, wound dressings and the like, especially when intended for patients with metabolic disorders.
Biofilms are known to provide cells with an array of advantages as compared with planktonic cells including the ability to resist challenges from predators, antibiotics, disinfectants and host immune systems. Biofilms offer a selective advantage to a microorganism to ensure its survival, or allow it a certain amount of time to exist in a dormant state until suitable growth conditions arise which for instance provide bacteria protection from antibiotics and from a host's immune system. This causes serious problems and costs in medical, hospital and industrial settings.
Biofilms are believed to be involved in 80% of human bacterial infections such as periodontitis, gingivitis, urethritis, endocarditis, benign prostatic hyperplasia, chronic prostatitis, biliary tract infections, urinary tract infections, cystitis, lung infections, sinus infections, ear infections (e.g. otitis media, otitis externa), acne and other skin infections, rosacea, dental caries, dental plaque formation, nosocomial infections, open wounds, chronic wounds and device-associated infections. There is thus a need in the art to control biofilm formation. A biofilm inhibitor may be useful to clear the way for a bactericide to penetrate the affected cells and eradicate the infection or it can provide an alternative treatment approach for certain types of infections.
Biofilms can contribute to contaminating food (food industry), decreasing flow through pipelines by colonization of the pipe interior or mild steel corrosion (oil industry), initiating biofouling on vessel hulls (shipping industry), and infesting hospitals, in particular surgery rooms and medical devices used therein. Biofilm formation in combination with mineral deposition may reduce heat transfer in water based cooling plants There is thus also a need in the art for compounds and methods for preventing biofilm formation regulated mineral deposition. Valuable plants such as those producing fruits and vegetables, forestry crops, corn, cotton, rice, soybeans and wheat are affected in a deleterious manner by biofilm formation and hence need protection from biofilm formation.
US 2003/100593 teaches, but without biological evidence, that certain substituted 2-aminoimidazoles are useful for treating various diseases including cardiovascular disorders, Kaposi sarcoma, cancer, bacterial infections, migraine, allergy and osteoporosis.
WO 2009/070304 teaches 2-aminoimidazoles useful for controlling biofilms and bacterial infections in plants. WO 2009/123753 teaches 2-aminoimidazoles useful for inhibiting bacterial biofilms.
Organic Letters (2006) 8:5781-4 and J. Org. Chem. (2008) 73:6691-7 disclose a few imidazo[1,2-a]pyrimidinium salts as precursors of substituted 2-aminoimidazoles, but do not attribute any utility to these compounds.
J. Org. Chem. (1993) 58:3736-3741 and U.S. Patent Application Publication both describe methods for the synthesis of azidoalkylamines. The azide-alkyne Huisgen cycloaddition is a well known 1,3-dipolar cycloaddition method between an azide and a terminal or internal alkyne to provide a 1,2,3-triazole ring.
One object of the present invention is to address one or more of the above listed needs by providing efficient agents for reducing, controlling or inhibiting biofilm formation, such agents being either specifically acting on biofilm formation without influencing the planktonic growth of microorganisms, or being acting both on biofilm formation and planktonic growth in the same concentration range. Another object of the present invention is to provide new synthetic methods for producing such efficient biofilm formation inhibitors and precursors thereof.

Compounds, compositions, and methods for controlling biofilms

Katholieke Universiteit Leuven, K.U.Leuven R&D


Where images are displayed such that unintended light is also included and that light cannot be fully subtracted from the displayed image, an image processor compensates by compensating for the remaining light using perceptual models. In some cases, the perceptual model includes a plurality of user sensitivities and computation is performed, at least in part, based on expected user sensitivity to light pollution in portions of the images. The perceptual model might include a contrast sensitivity function, threshold-vs-intensity, saliency prediction and visual masking. The model might include artist indications of view attention. A light pollution likelihood map might be used to reduce the amount of computation needed, using a likelihood measure to determine an amount of computation to perform.

In an ideal case, where a particular image is to be viewed by an audience, each area of a screen (or other projection-receiving surface) should reflect to the audience the desired color and intensity of light at the desired time. However, there are physical constraints that cause light pollution, where light pollution includes the reflection or re-reflection of light from one or more of those screen areas that includes light that was not intended to be reflected from that point. Typically, this "light pollution", an unintended leakage of light due to some physical property of the display system, might be due to curvature of the screen or ghosting in stereoscopic 3D display systems, wherein light intended for one eye is visible to the other eye and combines with the light that actually was intended for the other eye.
Light pollution in 3D display systems results in "ghosting"—an object that is slightly displaced between the two stereoscopic images in order to convey to the eyes its depth appears as a "ghosting image" when portions of on eye's image leak over to the other eye's image. In some cases, the light pollution is easily modeled. For example, it might be determined by empirical or other methods that a particular 3D display system leaks 10% of the right eye's image onto the left eye's image and 10% of the left eye's image onto the right eye's image due to imperfect polarization of projected or reflected light.
In a conventional approach to deghosting, the right eye's image is composited with a negative 10% of the left eye's image and the resulting composite is displayed. However, there is a problem for pixels in the right eye's image that are supposed to be darker than the light pollution from the left eye (or vice versa). This corresponds to attempting to subtract more light than is available, leaving the resulting composite image with negative light values. Of course, since negative light is impossible to achieve in any type of physical display device, the composite image retains some of the light pollution.
To deal with the remaining light pollution, some producers will modify the "black level" so that the darkest points of an image are not totally black, thus allowing for more subtraction. However, this reduces the dynamic range of the displayed images.
Another approach is to carefully direct and edit an image sequence that is being presented so that bright objects in the foreground of a scene do not appear in front of dark objects, thus lessening the instances of negative light values in the composite image. Unfortunately, this may unduly constrain directors, cinematographers, artists, etc. when they desire to use a large dynamic range of light in close proximity.
Yet another approach is to ignore the remaining light pollution and have the viewers mentally deal with the remaining ghosting. However, this can lead to optical fatigue, especially with feature length films.
The goal of most, if not all, display systems is to provide viewers with the highest possible quality viewing experience. Many factors determine the overall viewing quality, but an important one is quality reduction due to unintended light pollution onto (portions of) the intended image.
It is important to reduce the cognitive load on the viewers of the ghosting that cannot be eliminated by simple subtraction.

Perceptually-based compensation of unintended light pollution of images for projection display systems


For dividing a dividend of a first plurality of m-ary digits by a divisor of a second plurality of m-ary digits to provide a certain number K of m-ary quotient digits, where m represents 2.sup.N, a shift register comprises a most significant part, first and second higher parts for the second plurality less one of m-ary digits and one m-ary digit, and a least significant stage and holds an instantaneous content which is used as a current content during a last part of a preceding one of two consecutive machine cycles and is first a concatenation of an m-ary zero digit and the dividend m-ary digits. A carry save adder tree calculates a set of zeroth to (m-1)-th algebraic sums of a part of the current content held in the most significant and the first and the second higher parts minus zero through (m-1) times the divisor, respectively, plus a carry from a previous machine cycle. The sums are used in deciding a partial quotient of one m-ary digit and a sum datum of the second plurality of m-ary digits. In a leading part of a succeeding one of the consecutive machine cycles, the partial quotient and the sum datum are stored in the least significant stage and the most significant and the first higher parts. After lapse of K machine cycles, the shift register is loaded with an eventual quotient in its stages other than the most significant and the first and the second higher parts.

This invention relates to a dividing circuit for dividing a dividend of a plurality of m-ary digits by a divisor of at least one m-ary digit, where m represents 2.sup.N, where N represents, in turn, a predetermined decimal integer which is not less than one. Each m-ary digit of the dividend and the divisor is therefore a binary, a quaternary, an octonary, a hexadecimal, or a like digit. More particularly, the dividing circuit is for calculating a quotient together with a residue. In connection with this invention, it should be noted that each of the dividend and the quotient can be said to consist of a plurality of m-ary digits without loss of generality.
Such a dividing circuit is useful in many fields of application, such as in an electronic digital computer. More specifically, the dividing circuit is a fixed-point dividing circuit according to this invention.
In the manner which will later be described with reference to one of a few drawing figures of the accompanying drawing, many machine cycles are necessary on calculating the quotient by a conventional dividing circuit. An improved dividing circuit is disclosed in U.S. Pat. No. 4,725,974 issued to Takashi Kanazawa. The improved dividing circuit is capable of achieving a high throughput. However, the improved dividing circuit comprises a great amount of hardware.

Dividing circuit calculating a quotient of K m-ary digits in K machine cycles


A method of chip manufacturing, comprises of a design stage; a simulation stage; a foundry stage; a testing/packaging stage; a cutting stage; and a final coating stage. The present invention provides a method of chip testing comprises of disposing a substrate layer on a wafer having a plurality of chips; exposing a plurality of pads on the chips of the wafer; forming bumps on the pads of the chips of the wafer; performing tests from the bumps on the chips of the wafer. Alternatively, the present invention provides a method of chip testing comprises of disposing a substrate layer on a wafer having a plurality of chips; connecting a plurality of pads on the chips of the wafer to a plurality of corresponding pads on the substrate layer; planting bumps on the pads on the opposite side of the substrate layer; performing tests from the bumps on the substrate layer.

1. Field of Invention
The present invention relates to a method of chip manufacturing. More particularly, the present invention relates to a method chip testing and packaging during the process of chip manufacturing.
2. Description of Related Art
As electronic devices are becoming smaller and slimmer, IC chip manufacturing process is becoming more complex. FIG. 1 shows a flow chart of the conventional manufacturing process essentially consists of a design stage 101, a simulation stage 102, a foundry stage 103, a DC/RF probing stage 104, a cutting stage 105, a packaging/coating stage 106 and a final testing stage 107. Difficulties arise when the DC/RF probing stage 104 is not carried out in an easy, accurate and cost efficient manner. The current DC/RF probing stage 104 is done before cutting to ensure only the good dies are packaged. The primary purpose of such probing is to save packaging costs. Probes move to designated pads by an X-Y coordinate controlling scheme and probes each pad on the chip individually. The DC/RF probing stage 104, especially RF probing, lacks accuracy, as the result curves will shift over time creating high error rates in measurements. Even if accurate measurements can be obtained, the results may not be a good representation of the chip performance since packaging will introduce additional parasitics degrading the performance in the RF domain. This creates many problems in the design cycle since the designer will not discover many design flaws until after packaging. Re-designing the IC after packaging is a time consuming and painful process. The re-design cycle may take months and with the current DC/RF probing stage 104, it is hard for the simulation results to be a close estimation of the actual performance before packaging. Furthermore, the cost of DC/RF probing is very high. It may take thousands of probes to perform the DC probing test and the cost of RF probe is in the range of hundreds of dollars each. RF probes are also very fragile and wear off relatively fast. They also may damage the pads. Since a typical RF wafer yield is in between 50% and 70%, we cannot simply drop the wafer probing test to save the manufacturing cost.
As the trend also demands faster processing speed and ubiquitous communication, thus the IC design will require higher frequency and integrated multiple standards in a single chip, and inevitably becomes more difficult to verify due to increasing complexity and interferences. As a result, it will have a longer IC design cycle and lower yield rate.
For the forgoing reasons, there is a need for a new method of chip manufacturing. More particularly, a new method of testing and packaging to simplify and cost down the design cycle, especially at the DC/RF probing stage 104.


A position measuring system for determining the relative position of a first object and a second object movable relative to one another that includes an incremental track, associated with a first object and having a periodic line structure that has individual lines and a scanning unit, associated with a second object movable relative to the first object, that scans said periodic line structure and that generates a corresponding incremental signal. A sensor system that generates absolute position information pertaining to the relative position of the first and second objects, wherein the width of the individual lines, as measured along a longitudinal direction of the incremental track, varies over at least a portion of the breadth of the incremental track, as measured in a direction transverse to the longitudinal direction, in such a way that a structure with absolute position information is superimposed on the periodic line structure.

Applicants claim, under 35 U.S.C. xc2xa7 119, the benefit of priority of the filing date of Jun. 4, 1999 of a German patent application, copy attached, Serial Number 199 27 034.1, filed on the aforementioned date, the entire contents of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a position measuring system for determining the relative position of two objects relative to one another.
2. Discussion of Related Art
In one such incremental position measuring system, a code carrier in the form of a scale (in the case of a linear measuring system) or a graduated disk (in the case of a rotary measuring system) is associated with the first of the two objects movable relative to one another and has an elongated incremental track with a periodic line structure. The line structure of the incremental track is scanned with a scanning unit, associated with the second object, in the form of a suitable sensor system. From the output signals of the sensor system, using an evaluation unit, the amount of the displacement of the two objects relative to one another can be determined relative to the position at which the two objects were located when the position measuring system was turned on. This makes it possible (if the relative position of the objects when the position measuring system was turned on is known) to make a continuous determination of the position of the two objects relative to one another.
In many applications, it is necessary, in addition to the high-precision incremental position measurement, to make absolute position information available, to enable determining the position of the two objects relative to one another directly. To do so, it is usual to dispose an additional reference or synchronizing track on the code carrier next to the incremental track, and from this additional track the position of the objects movable relative to one another can be determined directly. However, the additional track means that increased space is required on the code carrier.
Another possible way of generating absolute position information in an incremental position measuring system is known from Japanese Patent Disclosure JP-A 59-22 6822 for an angle measuring system, which as a code carrier has a graduated disk on which an incremental track extends along its circumference. The width of the incremental track varies transversely to its longitudinal direction on the graduated disk. This variation leads to a modulation in the amplitude of the incremental signal that accordingly contains the absolute position information. Here, however, the problem is that electronically separating the incremental signal component from the absolute position component is very complicated.
An object of the present invention is to create an incremental position measuring system of the type defined at the outset in which with the simplest possible structure, absolute position information about the position of the two objects movable relative to one another can be obtained.
The above object is attained according to the invention by the creation of a position measuring system for determining the relative position of a first object and a second object movable relative to one another that includes an incremental track, associated with a first object and having a periodic line structure that has individual lines and a scanning unit, associated with a second object movable relative to the first object, that scans said periodic line structure and that generates a corresponding incremental signal. A sensor system that generates absolute position information pertaining to the relative position of the first and second objects, wherein the width of the individual lines, as measured along a longitudinal direction of the incremental track, varies over at least a portion of the breadth of the incremental track, as measured in a direction transverse to the longitudinal direction, in such a way that a structure with absolute position information is superimposed on the periodic line structure.
Accordingly, the width of the individual lines of the incremental track varies along the longitudinal direction of the incremental track in such a way that a structure with absolute position information is superimposed on the periodic line structure. The periodicity of the underlying line structure can be preserved by providing that the spacings of the longitudinal axes of the individual lines are kept constant along the longitudinal direction of the incremental track.
An embodiment of the present invention is based on the recognition that the desired absolute position information can be obtained directly from the line structure of the incremental track itself, if the width of the lines is varied while maintaining their periodic arrangement. In other words, as in a conventional incremental track, the lines are disposed at a constant spacing with respect to their individual longitudinal axes; only the width of the lines varies transversely to the longitudinal axes (hereinafter called variation of the line width). The integration of the absolute position information into the line structure of the incremental track makes an especially compact structure of the position measuring system possible, since only a single track has to be scanned.
An embodiment of the present invention appears at first glance, because of the variation in the breadth of the lines in the longitudinal direction of the incremental track, not to allow the generation of a periodic incremental signal. However, according to the present invention, there are many possible ways of varying the individual line width in such a way that with a suitable scanning system, it is readily possible both to generate the periodic incremental signal and to generate a signal containing the absolute position information.
The variation in the line width need not necessarily take place over the entire breadth of the incremental track as measured transversely to its longitudinal direction. Instead, the variation in the line width can also be provided over only part of the breadth of the incremental track. (In the claims, for the sake of conciseness and greater clarity of the claims, the breadth of the incremental track transversely to its longitudinal direction has been called the breadth of the incremental track, for short.)
In a preferred embodiment of the invention, the individual lines of the incremental track each have a plurality of portions of different line width; the widths of the individual portions of a line are each selected such that all the lines of the incremental track cover essentially the same area on the code carrier. Correspondingly (given a constant spacing of the longitudinal axes of the lines), the interstices (gaps) between the adjacent lines each cover substantially the same area. Thus, there is a constant ratio of line width to gap width along the incremental track, which allows the generation of an incremental signal with a constant amplitude.
The variation of the line width is preferably formed in accordance with an oscillating function, and, in particular, a periodically oscillating function. In the case of a rotary measuring system, this readily makes it possible to generate a piece of absolute position information, if the period of the oscillating function is at least as great as the length of the incremental track. In the case of linear measuring systems, by comparison, it can be expedient to superimpose at least two and preferably three periodically oscillating functions on the incremental track, the periods of which functions differ slightly from each other, so that the absolute position information is generated by the Nonius or Vernier principle.
To create the aforementioned portions of different width of the individual lines of the incremental track, the incremental track can be subdivided transversely to its longitudinal extent into two or more partial tracks that each has a characteristic variation of the line width.
In a preferred embodiment of the present invention, the variation of the line width of the lines in the individual partial tracks in each case occurs by the same mathematical function, but there is a phase difference between different partial tracks. As mathematical functions, periodically oscillating functions, and above all the trigonometric functions, are especially suitable.
If each partial track having a certain trigonometric function has the corresponding trigonometric function phase-displaced by one-half of a period associated with it, then an offset-free sensor signal for ascertaining the absolute position can be generated by jointly evaluating the signals originating in these two partial tracks.
If for each partial track having a certain periodically oscillating function, a further partial track is provided whose trigonometric function is phase-displaced by less than one-half of a period, and in particular by one-quarter of a period, then along with the position of the two objects movable relative to one another, their direction of motion can be ascertained as well.
In an advantageous embodiment of the present invention, at least four, and preferably five partial tracks are provided, and the trigonometric functions of adjacent partial tracks are each phase-displaced relative to one another by one-quarter of a period. As a result, cross-talk between the individual channels of the sensor system that are associated with side-by-side partial tracks can be compensated for.
To generate the absolute position, each partial track of the incremental track is assigned its own sensor on the other one of the two objects movable relative to one another, and preferably two sensors spaced apart from one another in the longitudinal direction of the incremental track are provided, which are disposed on both sides of the scanning unit for generating the incremental signals.
Advantageously, both the scanning unit for generating the incremental signals and the additional sensors for generating signals with absolute position information are each formed by photoelements, to which a common light source is assigned. Since according to the present invention the incremental track can at the same time also include the absolute position information pertaining to the position of the two objects movable relative to one another, the scanning unit for generating the incremental signals and the additional sensors for generating the absolute position information can be placed close together and supplied with light from a common light source. This light source illuminates the incremental track, and from there the light (in an incident light or transmitted light process) reaches the photoreceivers.
As the scanning unit for generating the incremental signals, a sensor matrix of the kind known from International Patent Disclosure WO 97/05457 can be used in particular. International Patent Disclosure WO 97/05457 corresponds to U.S. Pat. No. 5,841,134, the entire contents of which are incorporated herein by reference. With regard to the structure of the scanning unit for generating the incremental signals, this international application is hereby incorporated by reference.
Further advantages of the invention will become clear from the ensuing description of an exemplary embodiment in conjunction with the drawings.


A method of determining whether a requested parameter reconfiguration of a connected call in a switched digital communication network complies with system constraints is described. Bandwidth related parameters, in particular, are subject to reconfiguration after a call is provisioned in order to optimize utilization of network resources. The implementation of a bandwidth reconfiguration involves an assessment of bandwidth utilization by the logical or physical links routing the connected call so that the reconfigured bandwidth does not negatively impact on the connected call. Once the reconfigured parameter is determined to be acceptable the reconfiguration data is propagated to the relevant network elements.

Switched digital communications networks such as Asynchronous Transfer Mode (ATM) and Frame Relay (FR) find particular application in the delivery of multimedia services. In such networks calls are transported across the network architecture by way of switching nodes within the network core. A network management system establishes and controls traffic flow between switching nodes.
Calls or logical links (trunk groups) connected in such a network have various associated call parameters. In the case of ATM, these parameters include Peak Cell Rate (PCR), Sustained Cell Rate (SCR), Maximum Burst Size (MBS), Cell Delay Variance Tolerance (CDVT), Traffic Descriptor, Traffic Policing methods etc. For Frame Relay, such parameters include Committed Information Rate (CIR), Committed Burst Size (Bc), Excess Burst Size (Be), etc. For Frame Relay calls travelling over ATM networks, many of the ATM call parameters are also required. Parameters associated with a call or a trunk group define the expected characteristics of data allowed to flow through them.
As such, these parameters are usually best guesses for the kind of data traffic expected through a call, or a trunk group. Once a call or a trunk group has been provisioned in a network, it might be discovered that some changes are required to some of the parameters in order to make better use of network resources. At this time, there might be customer data flowing through the calls, and hence any disruptions in that flow may be undesirable, or even unacceptable.
Reconfiguration of an already connected call requires a mechanism for the determination of the correctness of the new parameters, propagation of the new parameters to all the relevant network elements, and if there is a failure in propagation of such parameters, recovery from such failures.

Parameter reconfiguration of connected calls


Structure is provided for controlling the electrical stress on one or more optical fibers in a high voltage environment.

1. Field of the Invention
The present invention relates to stress control structure for optical fibers in regions of high electrical stress down to a lower electrical stress, or zero electrical stress or ground. In particular, it involves selections and arrangements of dielectric layers and other layers associated with optical fibers originating elsewhere or originating in or traversing regions of high electrical field strength and the control of the stress to which the optical fibers are exposed.
2. Description of the Art
The advantages of optical fibers over other media for the conveyance of digital and electrical signals are well known. However, optical fibers placed in regions of high electrical field strength are susceptible to damage and failure from localized dielectric breakdown of the electrical insulation system in the vicinity of the optical fibers. This condition is intensified when a discontinuity exists in the shielding of a high voltage cable, sensing device or other electrical equipment.
The following and all other referenced patents and applications are incorporated herein by reference in their entirety. Definitions herein prevail over definitions in such references.
Some of the prior art is very useful in pointing out solutions to various problem areas. U.S. Pat. No. 6,215,940, for High Voltage Insulator for Optical Fibers, issued Apr. 10, 2001, which reference is incorporated herein, describes the various embodiments of flexible insulator sleeves, characteristics of the insulative support rod, (corresponding to insulative central structural element herein), preserving integrity of the optical fibers, cushioning between the optical fibers and the support rod, problem of voids, (air gaps), moisture, and other aspects. This reference also points out that the length of the rod, (insulative central structural element herein), depends primarily upon the level of the (voltage) system on which it is used.
Also, U.S. Pat. No. 6,015,625, for Stress Control for Termination of a High Voltage Cable, issued Jan. 18, 2000, is incorporated herein by reference, providing test and design information as to stress control layers, including permittivity requirements, with improved corona discharge extinction, withstanding of power frequency voltage and impulse voltages, and in meeting the requirements of IEEE Standard Test procedures, STD 48-1990. That patent also provides helpful information as to exterior elastomeric coverings, (sleeves), and other types of exterior coverings, elimination of air pockets, as well as superiority of stress control material comprised of epihalohydrin rather than EPDM.
Elements:                1. Insulative Central Structural Element: The insulative central structural element is the innermost portion of the particular structure. Although other shapes may be used, it may be constructed of a longitudinal, central, circular, or somewhat circular, column, forming the body of the elongated portion of the structure. Whereas circular or near circular is the preferred shape, elliptical, triangular, square, hexagonal, octagonal and other multi-sided symmetric and asymmetric shapes might conceivably be used.                    The insulative central structural element is formed from a material with good insulative properties at high voltages. In various embodiments of the invention, the structure may be comprised of ceramic, glass, porcelain, plastic, polycarbonate, phenol, or other materials which are suitably insulative and provide the strength required to support the physical structure. Although it is not necessary, the insulative central structural element may be made of high dielectric material.            In one embodiment, such structure may be a high voltage cable with all it accompanying layers.            The thickness of the insulative central structural element is determined by the dielectric strength of the insulator material, the applied high-voltage and the needed safety factor as determined by the application. Typical thickness for the insulative central structural element is between 0.5 and 1.25 inches for an applied high-voltage of 35 kV.            Voltages in high voltage distribution systems range from 4 kV to 75 kV with common voltages of, say, only as examples, 15 kV, 25 kV, 35 kV, 46 kV and 69 kV. The dielectric capability and size of the insulative central structural element would, of course, take into account differences in intended use.                        2. Stress Control Layer: The stress control layer consists of a high permittivity material that is tightly-fitted around the insulative central structural element in such a way so as to create a void-free or substantially void-free interface. This high permittivity material manages the high-electrical stresses by creating a more evenly distributed e-field over the surface of the structure, significantly reducing the potential for insulation breakdowns that could result in partial discharge, withstand or Basic Insulation Level (BIL) failures. (Partial discharge occurs when a localized dielectric breakdown of the electrical insulation system under high voltage stress but not of sufficient magnitude to bridge the space between two conductors.)                    The thickness of the stress control layer is typically 50 to 200 mils and in various embodiments of the invention, the material may be comprised of Ethylene-Propylene (EP), Ethylene-Propylene-Diene-Monomer (EPDM), rubber or silicon or other suitable materials having properties, with various additives, fillers and conductive particles so as to provide the needed permittivity.                        3. Dielectric Layer: The dielectric layer consists of an elastomeric material with high dielectric strength that, in conjunction with a second layer of elastomeric material, form two layers that encapsulate the optical fibers, minimizing voids in the vicinity of the fibers. In one preferred embodiment, two dielectric layers are composed of the same material with self-fusing properties to minimize voids and with sufficient pliability to conform to the fiber radius; however the self-fusing property is not strictly required, but it is an advantageous embodiment.                    In various embodiments of the invention, the dielectric layer may be comprised of rubber, silicon, or other elastic materials with various additives and fillers to provide the needed dielectric material properties.                        4. Optical Fiber: The optical fiber is a cylindrical dielectric waveguide, typically made of low-loss glass or plastic comprised of a central core which guides the optical signal surrounded by a cladding material of slightly lower refractive index. Light impinging on the core-cladding interface at an angle greater than the critical angle undergoes total internal reflection and is guided through the core. Fiber optical cable is familiar to those skilled in the art. The optical fiber, in this application, is used for the transmission of analog or digital data through a region of high electrical stress. "Light" as used herein includes, of course, much more of the electromagnetic spectrum than visible light. Both infrared and ultraviolet frequencies might be used. Infrared and near infrared are most common. Such wider meaning is commonly known in the art.        5. Dielectric Layer: The dielectric layer consists of an elastomeric material with high dielectric strength that, in conjunction with a first layer of elastomeric material, form two layers that encapsulate the optical fibers, minimizing voids in the vicinity of the fibers.        6. External Insulator: An external layer of insulative material is placed around the structure. The external insulator is very tightly-fitting. The external insulator may include "skirts" or "sheds" or "wings" to decrease the susceptibility to external arcing or tracking; known to those skilled in the art, or, as described, for example in U.S. Pat. No. 6,215,940. The external insulator must prevent electrical tracking and must be strong, tight-fitting, hydrophobic and be an effective "weathershed", providing protection against weather and harsh environmental conditions. It may be composed of highly insulative rubbers, silicone, various polymers and other suitable materials.                    Depending of the application, the external insulator may not be required since this is primarily necessitated by exposure to weathering and harsh environmental conditions. In various embodiments of the invention, this layer can be eliminated or replaced with an alternate external layer suitable for the physical conditions to which the structure will be exposed.            In the preferred embodiment, the construction elements 1-6, as referenced above, describe the materials and methods used to construct the stress control insulating device of the invention. It is conceivable that either one or both of the dielectric layers (elements 3 and 5 above) could be omitted. In alternate embodiments of the invention, the various construction elements could be combined, performing the same physical and electrical functions, albeit with a reduced number of physical elements, but accomplishing the same functions.
A description of a current and voltage sensor, such as might be used in combination with the inventions herein, is found in patent application Ser. No. 135534886, filed Jul. 19, 2012, entitled, "OPTICAL SENSOR ASSEMBLY FOR INSTALLATION ON A CURRENT CARRYING CABLE. (Applicant will furnish updated information when received.) Such application is incorporated herein for reference purposes.
The various items used in the electrical constructions herein are commercially available. Most can be ordered by size, length, width, dielectric constant, conductivity and other characteristics. The needs for cable elements can be met over a wide range of voltages. Many suitable products are available from several suppliers. Of course, a wide range of optical fibers are also readily available.

Stress control structure for optical fibers in a high voltage environment


An integrated capacitive device has a thin-film capacitor formed of first and second electrode layers, electrically separated by a dielectric layer formed of a hydrogen-degradable compound. To protect the dielectric layer from degradation due to hydrogen diffusion, at least one layer of a getter material is provided, selected from alloys of zirconium, vanadium and iron, optionally containing minor quantities of manganese and/or a rare earth group element, and alloys of zirconium with at least one metal of the group of iron, cobalt and nickel, optionally containing up to about 15% by weight of elements of the rare earth group.

The present invention relates in general to integrated circuits and in particular to storage devices whose structure comprises a dielectric layer of capacitive coupling having ferroelectric features and/or a high dielectric constant, both in the case that the storage device employs the features of residual polarization of the ferroelectric oxide or the capacitive coupling through the dielectric oxide for storing information in the form of electric charge.
Ferroelectric and particularly dielectric compounds based on mixed oxides or equivalent compounds with ferroelectric features are materials used in different fields and particularly in the manufacture of integrated structures on a semiconductor or dielectric substrate. Piezoelectric filters, ultrasonic transducers which employ the piezoelectric features, infrared transducers, optical sensors employing features of pyroelectricity, optical modulation devices, and optical diaphragms based on the employment of electro-optical features are some applications of these materials.
The possibility of manufacturing extremely thin dielectric films of materials having ferroelectric features has favored the development of nonvolatile storage devices with ferroelectric capacitors, which employ the stability in time of the residual polarization of the thin layer of ferroelectric material of the capacitor. These devices (storage cells) have been developed by virtue of their potential to be manufactured in extremely compact size, so as to increase the storage capacity and the level of integration of the whole integrated device or their marked ability to preserve the information even in particularly hard conditions.
Ferroelectric dielectrics which are commonly used in the manufacturing processes of integrated devices are lead zirconate titanates, PbZr(1-x)Ti(x)O3, commonly known with the acronym PZT, bismuth and strontium tantalate or Sr2Bi2Ta2O9, commonly known with the acronym SBT or YI, and the lanthanum and bismuth titanates, commonly known with the acronym BLT. These are among the most used materials for manufacturing the so-called FeRAM storage devices.
Another similar dielectric material (also with ferroelectric features) used as a dielectric layer, in particular as dielectric interpoly of capacitive coupling between a control gate structure (wordline) and the floating gate of the cell in DRAM cell structures, is barium and strontium titanate, Ba(x)Sr(1-x)TiO3, also known with the acronym BST.
The materials preferably used for exploiting the ferroelectric features thereof in FeRAM are the above mentioned PZT and also the SBT or the BLT, whereas the BST is most frequently used in the DRAMs by virtue of an increased possibility of depositing extremely thin films thereof, having a high dielectric constant, free from defects.
The techniques of deposition of the layers of dielectric compounds with ferroelectric features can be various, such as by xe2x80x9csputteringxe2x80x9d, or by chemical deposition from the vapor phase (CVD) wherein a decomposable compound, commonly an organometallic compound of precursor metals, is deposited from the vapor phase on a suitable substrate.
Another method of formation of these layers is the so-called xe2x80x9csol-gelxe2x80x9d method, wherein a solution of precursor compounds is used in order to form a film on substrate, commonly by thermal decomposition of several applications of sol-gel. There is also a method based on the creation of a xe2x80x9cmistxe2x80x9d of ionized drops of a solution of a metallo-organic precursor compound, which are deposited on the wafers. Once the solvent is evaporated, the metallo-organic compound is decomposed at high temperature in a strongly oxidizing environment, so as to form a film of composite oxide. This technique is known in the literature as xe2x80x9cLiquid Source Misted Chemical Depositionxe2x80x9d or briefly LSMCD. Other methods of preparation are known in the literature.
Leaving out of consideration the particular function of the thin-film capacitor of dielectric material with high dielectric constant, optionally also with marked ferroelectric features, and the relevant integrated structure to which it belongs, whether that of a FeRAM, of a DRAM or other, the formation of the thin-film capacitor in the course of a manufacturing process of a common semiconductor integrated device, for example in CMOS technology, entails a number of problems due to a precise risk of exposure of the thin layer, generally based on oxides, to hydrogen. As a matter of fact, in the common course of a manufacturing process of integrated devices, there are a number of operations where hydrogen is present that remains partly trapped or incorporated in the wafer during the manufacture, typically in the semiconductor silicon substrate.
For example in a CMOS process, the devices (transistors) defined in the active areas can be exposed to an annealing treatment in hydrogen atmosphere for neutralizing bonds which are left xe2x80x9cdanglingxe2x80x9d in the semiconductor, in order to reduce problems of superficial charge at the interface between the semiconductor and the gate oxide. During this annealing treatment, hydrogen can remain trapped in the substrate, which thus becomes a source of hydrogen diffusion during the working life of the integrated device. Other sources of exposure to hydrogen can be identified in the so-called xe2x80x9cback-endxe2x80x9d steps of the process, during the formation of metallizing aluminum layers, the steps of formation of tungsten plugs for the contacts and formation of the IDL layers, wherein the process conditions are such that the presence of hydrogen is implicated.
Hydrogen can also be present during the sealing and encapsulating steps of the integrated device, in the case of ceramic xe2x80x9cpackaging.xe2x80x9d Also, during the working life of the devices, a certain diffusion of hydrogen inside the device can take place.
The effects of degradation of a dielectric film, optionally with ferroelectric features, generally formed of an oxide or more frequently of mixed oxides or equivalent compounds, upon exposure to hydrogen are well-known and discussed in the literature. In particular, a hydrogen degradation of the ferroelectric film of an FeRAM causes a contraction of the hysteresis curve, thus reducing the separation between the logical values 1 and 0 on the ordinate axis, which effect can bring about a difficulty in the discrimination criteria in the reading step of the information stored in the ferroelectric film capacitor. In the case of a DRAM, the degradation of the thin dielectric film of interpoly capacitive coupling determines a loss of electric charge stored in the floating gate through the wordline.
The suggestions made until now in order to overcome this critical aspect of the dielectric and ferroelectric materials having a high dielectric constant against a hardly avoidable hydrogen exposure have been several.
European published patent application EP-A-0 605 980 discloses a growth PECVD technique of a Si3N4 and SiON layer having a low hydrogen content, as an inter-dielectric state of an FeRAM device, using TEOS (Si(OC2H5)4) and N2, instead of the common mixture of SiH4/NH3/N2.
U.S. Pat. No. 5,523,595 discloses the sputtering of a TiN or TiON layer on the FeRAM device using a PZT deposited via sol-gel, with functions of a barrier-layer against hydrogen and humidity.
U.S. Pat. No. 5,481,490 discloses the deposition of a thin layer of nitride of aluminum, silicon or titanium on the ferroelectric capacitor, in order to prevent the degradation of the ferroelectric film of the capacitor during the annealing treatments which are foreseen in the manufacturing process of the device, during which the gases H2 and N2 are used.
U.S. Pat. No. 5,591,663 discloses a particular sequence of a manufacturing process of an FeRAM device using conventional materials, which avoids the hydrogen degradation during the annealing treatment.
European published patent application EP-A-0 837 505 discloses a structure comprising a ferroelectric capacitor, wherein a second layer of ferroelectric material PZT is deposited on the already defined structure of the ferroelectric capacitor, so that the second layer of PZT acts as a sacrificial layer, thus preventing hydrogen from reaching and degrading the PZT layer of the capacitor.
European published patent application EP-A-0 911 871 discloses the formation of a thin layer of tantalum and silicon nitride on the ferroelectric capacitor structure, with the function of a barrier layer against the possible diffusion of hydrogen against the ferroelectric layer of the capacitor.
U.S. Pat. No. 5,760,433 discloses the use of a sacrificial layer of a material chemically reactive towards hydrogen which is arranged on the capacitor structure as a protection of the ferroelectric layer of the capacitor. The sacrificial material can contain Sr, Nb, Ta and/or Bi, bismuth oxide, palladium oxide.
U.S. Pat. No. 5,716,875 discloses an FeRAM structure wherein, after annealing in N2+H2, a layer of silicon nitride Si3N4 is deposited on the integrated structure of the transistor and on the back of the substrate wafer for encapsulating (isolating) the structure and preventing in the future the possible effects due to hydrogen retention after the annealing treatment. On a structure so xe2x80x9cisolatedxe2x80x9d with regards to the diffusion of the hydrogen therein sorbed, there is formed the ferroelectric capacitor, which can be therefore advantageously annealed in an oxygen atmosphere without causing degradation of the transistor features. On the other hand, the hydrogen possibly trapped in the so xe2x80x9cinsulatedxe2x80x9d wafer structure will not be able to reach and to degrade the ferroelectric film of the capacitor, thanks to the barrier offered by the nitride layer.
European published patent application EP-A-0 951 059 discloses a particular manufacturing process wherein a final annealing in oxygen would solve the hydrogen degradation which could have taken place during the metallization processes.
U.S. Pat. No. 5,990,513 describes the formation of an inter-level dielectric layer with hydrophilic properties covered by a dielectric layer having reduced hydrophilic properties for protecting the ferroelectric layer during the annealing treatment in hydrogen atmosphere in the case of a ceramic encapsulated device. Ceramic encapsulation requires generally an annealing process at 440 xe2x96xa1.
Japanese published patent application JP-11-293089 describes the formulation of an epoxy resin usable for encapsulating an FeRAM device having features of low hydrogen release at 175 xe2x96xa1 for 90 minutes.
Japanese published patent application JP-11-087633 discloses the use in an FeRAM device of a metal layer formed of a material capable of storing hydrogen during the manufacturing steps. Then, the sorbed hydrogen is expelled by means of thermal treatment under vacuum. The used material can be Pd, V, Ni, Nb, Ti, Fe, Mg, TiFeLaNi2, Ti2Mn3 VNb, TiCo, ZrMn2, Mg2Cu, Mg2Ni, LaCo3, Ti2V8, Ti2C, Ti2Fe, Ti2CoMn.
Japanese published patent application JP-1140761 discloses the use of a layer of Ta or V or Nb deposited on the ferroelectric capacitor for protecting the latter from hydrogen degradation.
Japanese published patent application JP-118355 discloses the use of a hydrogen barrier layer formed of titanium dioxide or silicon nitride arranged under the lower electrode of the ferroelectric capacitor and of a barrier layer arranged over the upper electrode of the ferroelectric capacitor of the same materials or alternatively of titanium nitride or of TiOSi.
Japanese published patent application JP-2000-40799 discloses that, by making a reactive layer of Pbxe2x80x94Ptxe2x80x94Tixe2x80x94O between the PZT ferroelectric layer and the Pt upper electrode of a ferroelectric capacitor, it is possible to prevent the diffusion of hydrogen towards the dielectric and often ferroelectric film of the capacitor.
Until today, the most commonly followed approach is interposing a barrier layer against the diffusion of hydrogen as a protection of the preformed structure of the thin-film capacitor. Obviously, the barrier layer is effective only against the hydrogen coming xe2x80x9cfrom abovexe2x80x9d, that is, the hydrogen which is present in the back-end steps of the manufacturing process of the integrated device. However, the barrier layer is not effective against a possible diffusion of hydrogen xe2x80x9cfrom belowxe2x80x9d, that is, from the hydrogen which has been trapped in the wafer during the annealing treatment and hydrogen of the active structures, which have been formed before making the capacitor. Some known solutions entail the formation of a barrier layer against the diffusion of hydrogen even under the lower electrode of the thin-layer capacitor.
In most of the suggested solutions the approach is anyway protecting the thin layer of dielectric and/or ferroelectric material of the capacitor by means of barrier layers which insulate it against a possible hydrogen diffusion.
The barrier layers tend to stop hydrogen diffusion toward the electrodes and therefore toward the dielectric and/or ferroelectric or having a high dielectric constant material in a passive way. In the case for example of oxides, in addition to the passive effect there is also the chemical reaction between hydrogen and oxide which produces water. This reaction eliminates hydrogen, producing the hydrogen compound.
Also, the materials disclosed in the further Japanese published patent application JP-11-087633 for retaining hydrogen, which is then removed by thermally treating the device under vacuum before the final encapsulation thereof, are capable of sorbing hydrogen in a significant way only at atmospheric pressure.
The main object of the present invention is to provide a thin-film capacitor structure, wherein the dielectric is formed of a material having a high dielectric constant and optionally having also ferroelectric features, protected from the risk of degradation of the dielectric material due to hydrogen diffusion in a more effective way than it is obtainable with the known techniques and without the above mentioned drawbacks and limitations.
This important result is obtained by providing, under the lower electrode and over the upper electrode of the thin-film capacitor, a layer of getter material which is capable of sorbing and retaining hydrogen even at sub-atmospheric pressures without giving rise to chemical bonds (reacting) with hydrogen and/or to morphological modifications of the material.
The sorbing action exerted toward hydrogen by the getter material, in addition to sequestering the hydrogen remaining in the finished device, retains it, thus avoiding degradation of the dielectric-ferroelectric film, without giving rise to generation of water and without chemically reacting with hydrogen.
However, in order to obtain this result, it is necessary that the getter material have hydrogen equilibrium pressures less than 1 mbar at room temperature and that the thickness sufficient for retaining the hydrogen present is compatible with the stringent requirements of compactness of the integrated structures.
Basically, the getter material is an alloy made of zirconium, vanadium and iron, optionally containing minor quantities selected from manganese and the group of rare earth elements, or an alloy of zirconium and at least one of the metals of the group consisting of iron, cobalt, nickel, and optionally containing up to about 15% by weight of rare earth elements.
One layer of getter material is deposited over the layer of material forming the upper electrode of the capacitor and, more preferably, also under the layer forming the lower electrode of the thin-film capacitor, optionally deposited on a first layer of adhesion, for example titanium, interposed between the laminated structure of the capacitor and the support layer.
The getter layer provided under the lower electrode of the thin-film capacitor intercepts the hydrogen which may diffuse from the substrate, if it has been sorbed by the substrate during a previous step of annealing of the wafer in hydrogen. Typically, the lower getter layer can have a lesser thickness (of the order of about 50-100 nm) than the upper getter layer, which can have a thickness also up to about 200 nm.
The lower getter layer can effectively also contribute to sensibly increase the adhesion between an electrode layer, for example of a noble metal or alloy of a noble metal, and the underlying support layer, often in an FeRAM or DRAM device, an amorphous layer of silicon oxide doped with boron and phosphorous (BPSG). In many cases, it can provide the necessary adhesion, thus avoiding the need to interpose a specific adhesion layer with the support layer.
The getter layer which is provided over the upper electrode of the ferroelectric capacitor intercepts and traps the hydrogen which can diffuse through the insulating, metallizing and passivating layers, commonly placed over the defined structure of the ferroelectric thin-film capacitor during the subsequent steps of the fabrication process of the integrated device, in some cases also including the encapsulating steps of the device (packaging).
Both the getter layer formed over the upper electrode of the capacitor and the getter layer optionally formed under (deposited before) the lower electrode of the capacitor can be defined through appropriate masking and attacking steps together with other layers of the structure. In particular, the upper getter layer can result in being self-aligned to the perimeter of definition of the capacitor. Alternatively, the getter layer can be defined through a suitable masking step, also with a wider perimeter than the perimeter of the capacitive coupling area.

Integrated capacitive device with hydrogen degradable dielectric layer protected by getter layer


This invention is a micromachined sensor pixel structure that can be fabricated either as a discrete sensor or in array form with application to thermal sensing of radiation receive from various wavelength emitters. The transmissivity of a thermally-isolated microplatform is a sensitive function of temperature. This transmissivity is modulated by incident radiation from sources including infrared sources. The transmissivity of a micromachined structure is interrogated by means of an optical carrier. Readout is obtained by means of conventional silicon optical sensors or imagers. A multiplicity of micromachined pixels can be tailored for specific wavelengths permitting the array to operate as a multispectral imager with windows ranging from ultraviolet to millimeter wavelengths.

This invention relates generally to thermal sensing of low-level radiation of infrared or millimeter wavelengths and more particularly to a pyro-optical pixel structure and focal plane array with means for maintaining a nominal temperature. This invention describes a method of sensing incident radiation using a highly sensitive thermal thin film structure. In its embodiment as an array, a thermal image obtained typically from infrared wavelengths is interrogated using an optical carrier beam and readout with conventional CCD or CMOS silicon imagers.
Work leading to this invention was not funded by the US Government.
Thermal-based sensor systems typically use a pixel that is highly sensitive to temperature differentials. This minute temperature differential is read out using conversion techniques into an electrical signal. The basic components for a thermal imaging system generally include optics for collecting and focusing the incident irradiation from a scene onto an imaging focal plane. A chopper is often included in a thermal imaging system to produce a constant background radiance which provides a reference signal. The electronic processing portion of the thermal imaging system will subtract the reference signal from the total radiance signal to produce an output signal with a minimum background noise level.
The concept of using a pyro-optical material as a sensor to detect radiation by modulating a carrier beam was first disclosed by Elliott in U.S. Pat. No. 4,594,507. This concept is cited as prior art in FIG. 1 as an architectural representation of a system with an optical carrier source 1 and an external radiation source 2 illuminating a pyro-optical pixel 3 with a photodetector 4 to monitor the amplitude of the carrier source 2 modulated by the transmissivity of the pyro-optical pixel 3. In this example the low level radiation source is focused onto the pyro-optical plane 3 through refractory lens 5. The present invention is an improved sensor pixel based on the concept of FIG. 1. The present invention describes a micromachined pixel containing a pyro-optical film integral to a thermally isolated platform and positioned above a temperature-referenced substrate.
The thermal imager of Elliott (U.S. Pat. No. 4,594,507) includes a preferred embodiment of an optically active nematic crystal with a polarizer analyzer that is illuminated from an external light source of unspecified type. This thermal imager operates with an external photodetector of unspecified type illuminated by the external light source through the nematic, temperature-sensitive crystal. The result is an image converter operating with the nematic crystal as the modulator. The system detailed by Elliott operates within an oven typically at 28 deg C. and is specified for imaging infrared irradiation only. Individual pixel structures are not disclosed or claimed and thus items such as separate pixel heaters and micromachined structures are not embodied in this invention. The Elliott system does not use compactness of construction since the external light source and photodetector are not integrated into the structure containing the nematic liquid crystal. Thermal isolation structures surrounding the nematic crystal film and any specific type of optical light source are not mentioned. Performance-enhancing interferometric structures are not mentioned.
Hanson in U.S. Pat. No. 5,512,748 discloses a thermal imaging system containing a focal plane array in which a visible or near-infrared source is used to transfer an image from a transmissivity-modulated pyro-optical film layer onto an associated integrated circuit photodetector. The photodetector integrated into the substrate generates a bias signal representing the total radiance imaged from a remote low-level scene. A thermal sensor is described which contains infrared-sensitive material supported by two bifurcated support arms and nonflexing posts to maintain this film layer above the substrate with a gap therebetween. The thickness of the infrared-sensitive material is not mentioned except to note that it is preferably xe2x80x9cvery thin to enhance it""s response to incident infrared radiation and to allow transmission of electromagnetic energy therethroughxe2x80x9d (col. 7, line 8) without mention of Fabry Perot characteristics. The gap under the sensitive film is said to preferably correspond to xc2xc wavelength of the selected infrared incident radiation wavelength to provide maximum reflection of the infrared from the semiconductor substrate to the infrared-sensitive film. Hanson does not disclose or claim the use of electrical heater elements or any means of temperature control within or without the infrared sensitive pixel. Hanson does not disclose or claim the use of vacuum surrounding the infrared-sensitive pixel.
Owen in U.S. Pat. No. 6,087,661 describes a structure with electrically conducting tetherbeams forming a signal flow path for readout from a pyroelectric pixel material. The tetherbeams further provide a thermal isolation for the pyroelectric sensor microplatform.
Ruffner et al in U.S. Pat. No. 4,751,387 describes the use of a silica foam called aerogel as a solid, thermal isolation film formed between the pyroelectric capacitor and an underlying substrate as part of a specific infrared-sensitive pixel design without claims describing components external to the pixel. The use of pyro-optical sensitive materials is not disclosed or claimed. The Ruffner patent does not mention heating elements or ovens, vacuum conditions, the use of any optical carrier interrogation beams, pyro-optical materials, or the use of performance-enhancing interferometric structures.
Robillard in U.S. Pat. No. 4,751,387 describes an infrared imaging system comprising a pyro-optic film consisting of dichroic liquid crystal coated on a membrane with a means of polarized visible light illumination onto the crystal film. In addition a means for analyzing the polarization of the visible light carrier after reflection from or transmission through the crystal film is included in a system where the readout described is the human eye. Robillard does not disclose or claim any micromachined structures, thermal isolation structures, the use of partial vacuum, ovens, or pixel heaters.
Cross in U.S. Pat. No. 4,994,672 describes an infrared imaging system including a sandwich structure of polarizing pyro-optic material formed over an optically transparent, thermally insulating foam such as silica aerogel. The reflectance (not transmission) of an interrogating light beam is modulated by the temperature of the material and is used to illuminate a pixel image onto a CCD. A container means is provided for enclosing the pyro-optical material and maintaining a stable temperature. The Cross system requires the use of polarized light. The present invention does not utilize the polarization of light. Cross does not modulate the transmission of the interrogating optical beam. Cross does not disclose the use of micromachined pixel structures, performance enhancing interferometric structures, vacuum conditions surrounding the pyro-optic material.
Tuck in U.S. Pat. No. 5,100,218 describes a specific thermal imaging system based on the thermal rotation of polarized light as it is modulated with transmission through a thermally-sensitive liquid crystal. The pyro-optical liquid crystal is separated from the optical source and photodetector by multiple lenses and thus is not a composite, sandwich structure integrating the optical carrier source and photodetectors. Liquid crystal is the only pyro-optical material mentioned. Pyro-optical materials that do not require polarization are not disclosed. Tuck does not disclose any micromachined structures, interferometric structures, any means of controlling ambient temperature, or operation with partial vacuum conditions.
Carr in U.S. Pat. No. 6,091,050 describes a micromachined platform that elevates automatically and without continuing power requirement which is useful for implementing pixels in the present invention. The platform is elevated to a desired level as a result of design and manufacturing controls to create the desired gap between the pyro-optical film and the underlying substrate thereby providing a Fabry Perot interferometric means of enhancing the absorption of incident low-level radiation. Prior state of the art low-level radiation sensors are generally operated using a means of synchronously chopping the incoming low-level radiation to provide an image signal and a reference signal. Electronics for receiving the biased signal and the reference signal and for subtracting the reference signal from the biased signal to obtain an unbiased signal representing radiance differences emitted by objects in the scene is typically implemented in these systems. Carr and Sun in U.S. Pat. No. 5,781,331 describe a micromachined shutter array that can serve as a means of synchronously chopping the incoming low-level radiation with the present invention.
Hanson et al in U.S. Pat. No. 5,486,698 describe an actuation means for periodic thermal coupling of a bolometer or ferroelectric sensing platform to a thermal reference substrate. This actuator operates by electrostatic force which is derived from an external voltage source and eliminates the need for an external mechanical chopper. Hanson does not disclose the use of microactuation as in the present case of a platform with a pyro-optical film.
It is one object of the present invention to provide an improved uncooled, micromachined sensor pixel structure which utilizes a monolithic and self-aligned pixel which responds to thermal radiation. The visible or near infrared transmissivity or reflectivity of the thermally-isolated platform within the pixel is a parameter sensitive to temperature and therefore provides the means of detecting incident, absorbed radiation. The parameters of the pyro-optical film contained within the platform that are temperature sensitive are the optical index of refraction, bandgap absorption, and free carrier absorption. In the schematic system of FIG. 1, the incident low-level radiation 2 typically of wavelength greater than 2 micrometers, when absorbed into the subject pixel, typically heats with a power ranging from femtoWatts to nanoWatts. The high intensity optical beam from source 1 is modulated by the pyro-optical transmissive structure 3 and detected in the readout 4. The resulting thermal modulation index obtained in the readout signal from 4 ranges up to 10 percent. The readout 4 is a photodetector and control circuits for gating and time multiplexing the output signal. For imaging applications, the output electrical signal is a video signal that is processed within 4 to include such functions as synchronous detection. When the optical source 1 is pulsed periodically and then detected synchronously by 4, noise from stray optical sources is eliminated thereby reducing the overall system noise level.
One embodiment of the invention includes a resistive heater element within the thermally-isolated platform integral with the pixel used to maintain a nominal temperature which is modulated by absorbed, incident radiation. The use of a resistive heater element integral with the platform also permits high speed thermal dithering to reduce the effects of thermal response hysteresis.
An advantage of the present pixel is that no polarizing or extinction analyzers are utilized as optical components. An interrogating visible or near infrared light beam is modulated by the platform and signal readout is obtained using an underlying photodetector.
A further uniqueness of the invention is that the resulting thermal modulation index of the signal readout for a given absorbed, incident radiation power is maximized by the use of a first and a second Fabry-Perot film and sandwich structure integral to the pixel illustrated in the FIG. 2 embodiment. Both Fabry Perot structures enhance the response to low-level radiation. The pyro-optical film 31 is itself a first Fabry-Perot structure with an optical thickness to maximize the index of modulation. The thickness optimum for film 31 is less than a wavelength of the carrier beam 21 and is a function of the pyro-optical film dielectric constant and the free carrier absorption at the wavelength of the low-level radiation. The pyro-optical film is typically of high index of refraction and is the primary modulator of optical carrier beam transmissivity. A second Fabry Perot structure is formed by the gap between the micromachined planar platform 31 and the substrate mirror 25 to further increase the index of thermal modulation. The second Fabry Perot structure by creates a node of maximum amplitude for the incident low-level radiation 22 within the platform structure and thus enhances absorption of said low level radiation.
The embodiments of the present invention include an optical focal plane array having thermal sensors formed by a multiplicity of the pixels and with a high degree of reticulation between adjacent pixel platforms to minimize thermal spreading between adjacent pixel elements and to improve the spatial modulation transfer function of the resulting thermal sensors. Tetherbeams are used to support the platform structures above the substrate and with shared support posts to reduce the total array area and to increase the fill factor of pixel utilization. The pixel array processes a low-level image in parallel without the need for line and row scanning circuits within the pixel structures. The image formatting is accomplished by an underlying photodetector array which is typically a CCD or optical CMOS imager.


In a terminal device, contents data from an attachment mounted on the device is received by a transmission/reception section and replayed by a first playback section. A detection section detects the mounting or removing of the attachment during the playback of the contents data. As an output destination for the contents data, a selection section selects the first playback section when the attachment has been mounted, or selects a first storage section when the attachment has been removed. In the attachment, the contents data is outputted to one of the first storage section and the first playback section based on the selection result of the terminal device. Accordingly, the usage mode of contents data can be readily changed with the mounting or removing of an attachment as a trigger.

In recent years, portable terminals have been disclosed in which a detachable panel member or a multifunctional dongle is attached to the main body of the portable terminal so that additional functions corresponding to the panel member and the like are added.
For example. Patent Documents 1 and 2 disclose a technology in which a portable terminal that is used with a panel member being attached thereto is operated in accordance with information stored in the attached panel member. As a result of this technology, by the panel member being replaced, the operations can be changed in accordance with uses or owners.
Also, in Patent Document 3, a technology has been disclosed in which back panels are replaced in accordance with additional functions such as a camera function, a light emitting function, and a sound function.
Also, in Patent Document 4, a multifunctional dongle structured to be detachable from a portable terminal device has been disclosed, whereby functions such as a mobile financial transaction service, battery charging for the terminal device, and an FM transmitter can be selectively used.
Furthermore, in Patent Document 5, a portable terminal has been disclosed where a module embedded with an Internet communication module and a digital broadcasting reception module is connected to the portable terminal by means of USB (Universal Serial Bus), thereby receiving the digital broadcasting.

Contents reception system, attachment, and terminal device


Methods for making polyaminoboric acid compounds are provided. The polyaminoboric acid compounds are made by reacting a polyamine with boric acid in the presence of a solvent to produce polyaminoboric acid compounds with more than one boron-nitrogen bond. The polyaminoboric acid compounds are useful as crosslinking agents for fracturing fluids.

Hydraulic fracturing techniques are widely used to enhance oil and gas production from subterranean formations. During hydraulic fracturing, a fluid is injected into a wellbore under high pressure. Once the reservoir partition pressure is exceeded, the fracturing fluid initiates a fracture in the formation that grows during pumping. The treatment design generally requires the fluid to reach a maximum viscosity as it enters the fracture, thereby affecting the fracture length and width. The viscosity of most fracturing fluids is generated from water-soluble polysaccharides, such as galactomannans or cellulose derivatives. Linear gels that can be operated at ambient temperature do not have the necessary viscosity for proper proppant transferring at elevated temperature. The use of crosslinking agents or crosslinkers, such as borate, titanate, or zirconium ions, can further increase the viscosity. The gelled fluid can be accompanied by a proppant that results in its placement within the fracture that has been produced. The proppant remains in the fracture to prevent its closure and to form a conductive channel extending from the wellbore into the formation once the fracturing fluid is recovered.
Guar-based fracturing fluids are the most commonly used fluids in reservoir stimulation. As indicated, stimulation of oil and gas wells has been improved by the ability to crosslink the fracturing fluids to increase their viscosity. Some common crosslinking agents include boron and zirconium or other metallic compounds. Boron crosslinked gels are more commonly used due to their reversibility to mechanical shearing and less harmful environmental properties.
Common boron crosslinkers include boron anhydrides, borate esters, and inorganic borates. Generally for boron crosslinkers, the effective crosslinking species is B—OH, often formed after hydrolysis. For crosslinking, the B—OH moieties must be able to come into proximity with the functional groups on the polymer chains to form a chemical bond and bind the chains together.
U.S. Patent Publication Nos. 2010/0099913 A1 and 2010/0099586 A1, herein incorporated by reference, disclosed a family of poly(aminoborates) that can be used as effective crosslinkers. These applications provided a method to synthesize the poly(aminoborates) through a reaction between polyamines and trialkylborates.
However, this reaction is limited by the boiling point of the trialkylborate, usually trimethylborate. The reaction must be performed in a pressure vessel to increase the temperature and reaction rate to allow the reaction to be driven towards completion but prevent evaporation of the trialkylborate. A closed reaction system makes the reaction more difficult to perform and to monitor, which is a concern for quality control. Furthermore, the commonly used, trimethylborate, is moisture-sensitive and highly flammable with a low flash point. The storage of it requires special conditions, especially for humid climates, which adds to the cost of the final product.
It would be a significant improvement to find a reaction route to synthesize polyboronic crosslinker compounds without the shortcomings associated with using trialkylborate reagents.

Preparation of boron crosslinking agents for fracturing fluids


A circuit 8 reduces noise on a video signal from an imager 6 for a TV monitor 7. The noise reduction circuit includes a video frame store connected so as to integrate the corresponding picture elements of several frames in order to reduce noise. The amount of noise reduction applied depends on the noise on the incoming video signal but, whereas this has been assessed previously by comparing differences between incoming frames, in the invention it is assessed from the gain, information on which is encoded on the video signal. The gain of the imager gives a more accurate reflection of video noise than does comparing successive frames, since movements on the image can produce the same effect as noise fluctuations.

It has been proposed to reduce noise on the video signal from an imager by integration of a number of frames using a frame store. For example in one known arrangement (FIG. 1) a frame store 1 is connected in a recursive digital filter arrangement and receives a digitised video input. The digits that are read out of the frame store are delayed by one frame relative to those written in, and so digits representing pixels of any particular line of a given frame appearing at the input have subtracted from them digits representing respective pixels of the corresponding line of the previous frame. This difference signal is fed to a PROM k configured as a look-up table, the output of which may be attenuated compared to the input, and the output of the look-up table is added to the output of the frame store to produce the video output. A manual control enables one of the characteristics shown in FIG. 2 for the PROM k to be selected. The characteristic k.sub.1 (k or kernel=1) corresponds to no integration, while the characteristic k.sub.4 corresponds to maximum integration. It will be seen that, in case of no integration, the video output is equal to the video input, since the input has the output of the frame store both subtracted from it and added to it. In the case of k=4, corresponding pixels for any line are averaged over a number of rames in the video output. The manual control is adjusted to accommodate different levels of random noise corresponding to different scene conditions. In the case of a noise impulse on a single pixel in a single frame, this will be averaged to a lower and less obtrusive value over several frames. Clearly, however, integration will also have the undesired effect of averaging the position of an object that changes its position between several frames, so-called motion smear,
To mitigate such impairment of dynamic resolution, it has been proposed (GB-A-1515551) to make the value of k vary with signal level i.e. noise reduction at level k=4 only takes place when the input to the PROM 2 (the difference between the video input and the video output) is below a certain threshold (FIG. 3): it is assumed that small variations between successive video frames stem from noise while larger variations stem from motion. Consequently, the pixels in a line which were very similar in value to those in that line in previous frames, would be subject to noise reduction, whereas those in a line which differed significantly from those in the same line in preceding frames, would not. However, the threshold needs to be set above the level of fluctuations to the difference signal that is caused by noise, but the level of noise can itself vary.
The applicants considered constructing an adaptive system (FIG. 4) in which several different characteristics (FIG. 5) could be selected dependent on the magnitude of the difference signal (between the output and the input to the noise reduction circuit) and hence dependent on the level of noise (but averaged over many frames). Differences which would correspond to a good signal to noise ratio e.g. better than 39 dB (band a) produce a characteristic A, differences which would correspond to a medium signal to noise ratio lying in the next band b(33 db-39 dB) produce a characteristic B, those in a next band c (27 dB-33 dB) would result in a characteristic C, differences corresponding to a poor signal to noise ratio, worse than 27 dB (band d) would produce characteristic D. The signal resulting from the difference between each new incoming frame and the output of the frame store which would be dependent on the average of several recent frames passes through a rectifier 3 and low pass filter 4 before being converted in an analogue-to-digital converter 5 to one of a number of codes controlling PROM 2. Thus, for example, if the signal to noise ratio lay within band b over several frames, difference signals to PROM 2 below the threshold would be attenuated, those above the threshold would not. If the signal to noise ratio then became worse, the higher threshold of characteristic C would apply.
However, such an arrangement would be prone to error since the measurement of signal to noise ratio would be by comparing successive frames and any change due to motion would make the result inaccurate. For this reason, it has been proposed for the control of noise reduction in a noise reduction circuit to be dependent on the gain of a stage of the imager, which gain is related to the noise generated by the imager (EP-A-0328346 and U.S. Pat. No. 4,851,911).

Apparatus and method for noise reduction of video signal dependent upon video gain


In the construction of a hot blast stove, walls are made of pre-formed and baked bricks. At the joint between two walls, cast joining elements of complex shape are incorporated. The cast joining elements may be cast in situ. This avoids the need for pressing joining bricks of a variety of shapes.

1 . Field of the Invention
The invention relates to a hot blast stove having a refractory structure of two or more walls consisting mainly of bricks, which walls are joined together with joining elements connecting into them, and to a method for constructing such a hot blast stove.
2. Description of the Prior Art
Hot blast stoves are well known and are used for heating the air blown into a blast furnace. One known form of hot blast stove consists of a surrounding wall within which there is a combustion shaft and a checker work shaft, which shafts are separated by a partition wall joined to the surrounding wall on both sides by means of joining elements. In the case of this known hot blast stove the bricks and the joining elements are preformed, pressed and burned bricks. These joining elements in the form of bricks frequently have a complex shape and serve to provide the various connections, for example between the surrounding wall and the partition wall. Because the walls are erected in a brickwork bond, the joining bricks also have differing shapes for differing courses of which the wall is composed. For constructing the known hot blast stove the joining bricks are made in advance by pressing them in specifically designed heavy press molds. The variation arising in shape of the different joining bricks necessitates corresponding variation of press molds which causes considerable costs. FIGS. 1A, 1B and 1C of the accompanying drawings serve to illustrate that different joining bricks are used in one hot blast stove; in practice the number is greater than 35, and so the same number of differing press molds are needed for making them. In addition, the shaping possibilities and the shape of the prefabricated joining bricks which have to be fitted so that they link well into the brickwork limit design and construction possibilities of the known hot blast stove.
Constructions and brickwork of hot blast stoves are illustrated in articles Stahl und Eisen Vol. 95 (1975) No. 17, pages 802-806 and Metallurgist, Vol 23, no. 1/2 (1979), pages 97, 98.

Hot blast stove and method for constructing a hot blast stove


A composite scaffolding plank made from a plurality of wooden boards positioned in side to side parallel abutment. At least one of such boards is a whole natural wooden board, and at least one of such boards is a laminated wooden board. A plurality of spaced pins extend transversely through the wooden boards. A cam on the pins pulls and holds the boards together. In addition, my invention is a method of forming wide wooden planks from two or more narrow wooden boards (as described) by positioning the boards in side to side parallel abutment and embedding a plurality of spaced pins transversely through the boards. Further, a method of increasing the strength of a wooden plank is to cut the plank longitudinally into sections, add at least one laminated wooden board, position the sections in side to side parallel abutment, and subsequently embed a plurality of spaced pins in the sections.

1. Field of Invention
This invention relates to scaffolding planks. More specifically, this invention is directed to a composite scaffolding plank and a method for forming the same. The composite scaffolding plank is an improved, low cost wide scaffolding plank formed by pinning and anchoring a plurality of narrow wooden boards, at least one of which is a whole natural wooden board and at least one of which is a laminated wooden board. In addition, the strength of a wooden plank may be improved by cutting the plank longitudinally into sections, adding at least one laminated wooden board and pinning the plank sections together as described above.
2. Related Art
Prior to this invention, two types of scaffolding planks existed in the prior art: the solid single board plank and the laminated plank. The solid single board plank comprises one wide wooden board. The laminated plank is constructed from multiple layers of wooden strips glued together. Each of the two types of prior art scaffolding planks have advantages and disadvantages.
With respect to the disadvantages, due to the limited resources of old growth forests and the harvesting schemes for new growth timber, the yield of wooden boards wide enough from which to construct a solid single board plank is decreasing. Typically, only the center portion of a large tree is sufficiently broad to produce a solid single board plank. Thus, with decreasing yield, the solid single board planks are becoming more costly and difficult to make. The main disadvantage of laminated planks is that laminated planks primarily consist of glued layers of wooden strips, which glued layers of wooden strips absorb substantial amounts of moisture. After absorbing enough moisture, the wooden fibers of the laminated plank soften and the moisture hastens decay in the scaffolding board. Likewise, any time one of the veneers of the laminated plank cracks, the laminated plank looses its strength and consistency and can also no longer be used as a scaffolding.
With respect to the advantages, the solid single board planks are comparatively stronger and easier to manufacture than the laminated planks. In turn, the laminated planks, if oriented correctly, are comparitively more rigid than the solid single board planks. Moreover, laminated planks, when used in dry conditions, do not shrink as much as solid single board planks.
Co-pending application entitled Composite Scaffolding Plank and Method for Forming Same, which was filed on even date herewith, provides a safe third alternative to the solid single board plank and the laminated plank and reduces, if not eliminates, the disadvantages of the two types of prior art planks. However, the plank disclosed in Applicant's co-pending application does not benefit from the advantages inherent in the prior art solid single board plank and laminated plank.
It would be beneficial to the prior art to construct a scaffolding plank that optimizes and combines the advantages of both the single solid board plank and the laminated plank while greatly reducing, if not eliminating, their respective disadvantages.
Scaffolding planks are however strictly regulated. The Occupational Safety and Health Administration, OSHA, as well as the Southern Pine Inspection Bureau, SPIB, outline strict standards for scaffolding planks. Pursuant to such regulations, scaffolding boards must comply with certain width, breakage, and quality standards. The OSHA and SPIB standards are strict because workers entrust their lives to the scaffolding. The prior art would thus benefit from a scaffolding plank, as described above, that meets and preferably exceeds the OSHA and SPIB standards. The OSHA standards found at 19 C.F.R. .sctn. 1926, Subpart L, including Appendix A, recommends scaffolding for typical medium loads to be 2".times.10" (nominal). (Dimensions described in this specification are nominal dimensions, unless otherwise noted. Nominal dimension units are typically 1/2" greater than actual size dimensions.)
Because the lives of workers hinge on the integrity of scaffolding planks, any safety factors that can be added to a scaffolding plank greatly enhance the value of the scaffolding plank. It would be beneficial to the prior art to provide a scaffolding plank, as described above, which also includes an additional worker safety factor.
Moreover, so workers do not slip while stepping on the scaffolding planks, it is important for the scaffolding planks to have a non-slippery top surface. Natural wooden boards are typically smooth, and must be manipulated to be provided with an artificial non-slippery top surface. However, such manipulation normally also weakens the board. It would thus be beneficial to the prior art to provide a scaffolding plank that includes a non-slippery top surface. It would also be beneficial to the prior art to provide such a non-slippery scaffolding plank that includes natural wooden boards that have not been weakened during any artificial surface texturing.
Manufactured wide boards for scaffolding are unknown to the prior art. Prior references, however, disclose structural wood assemblies formed from a plurality of smaller wood boards. Illustrative of such wood assemblies are U.S. Pat. No. 2,650,395 that issued to de Anguera on Sep. 1, 1953, U.S. Pat. No. 5,120,378 that issued to Porter et al. on Jun. 9, 1992, U.S. Pat. No. 4,534,448 that issued to Trainer on Aug. 13, 1985, U.S. Pat. No. 1,167,988 that issued to Faulkner on Jan. 11, 1916, U.S. Pat. No. 2,569,450 that issued to Bouton on Oct. 2, 1951.
The assembly shown in U.S. Pat. No. 2,650,395 discloses a method of forming wood flooring from relatively narrow pieces of wood having varying lengths. The pieces of wood are placed in a number of parallel rows wherein the pieces are placed end to end. A plurality of spaced thin connector keys are driven into lateral bores in the aligned pieces and hold the pieces together.
U.S. Pat. No. 5,120,378 discloses an apparatus and method for producing a prestressed wood material beam. The wood beams are held together using adhesives or mechanical fasteners such as nails or staples.
U.S. Pat. No. 3,144,892, issued Aug. 18, 1964 to Webster, discloses and claims a method of fabricating panels that are formed by attaching a plurality of boards with relatively soft metal dowels. The dowels are driven into aligning bores that have been drilled through the narrow boards. Webster differs or teaches away from the present invention by having at least three significant limitations. First, Webster orients the plurality of boards such that their wider sides are contiguous. The present invention orients the boards so that their narrower sides are contiguous. This orientation is difficult to achieve without splitting the boards, but is achieved by the disclosed method. Second, Webster uses boards that have a tongue-and-groove channeling between boards to align them. The present method uses flat boards that are aligned with flat sides adjacent and tightly positioned together by the disclosed board pinning machine. Webster further requires tongue-and-groove channeling for releasing cuttings from bores during the drilling operation. Third, Webster uses the groove channels in the boards to "function as lead holes for starting the drill tips into each succeeding panel component" when drilling bores for the securing metal dowels. The present invention, due in part to its board pinning machine securely holding the boards, bores holes directly through the smaller boards without the need for pilot or lead holes.
U.S. Pat. No. 2,118,048, issued to Landsem, discloses a combined use of natural and laminated boards for fabricating structural beams, joists, girders, airfoils and other support components. U.S. Pat. No. 2,230,628 issued to Sahlberg likewise teaches the use of natural wood and laminate boards to fabricate box beams and I-beams girders. However, such mixing of natural and laminate boards is novel in the area of scaffolding boards. Landsem and Sahlberg teach structures having relatively large height versus width ratios. Adapting such structures to a scaffolding plank would result in a heavy, thick plank that would not be useful or commercially viable.
British Patent No. 720,603, issued to Elvins discloses a plank that comprises a metal frame formed by a pair of side members having stepped ends and end members shaped to overlap the said ends, one or more longitudinal metal partition strips, and wood pieces situated in the spaces between the said strips and frame. The strength in the design disclosed by Elvins is in the metal frame and metal partition strips, making the wooden slats inserts for the walking surface. The Elvins invention does not utilize the strength is characteristic of the wood used, and requires the use of metal frames that are heavier than wood, and are more difficult to maintain and use. The planks taught by Elvins have indented ends that may not be useful in standard scaffolding frames, especially those used in the U.S.
Though the above mentioned devices and assemblies may be helpful for their intended purposes, none disclose a manufactured scaffolding plank that meets OSHA and SPIB requirements and that optimizes and combines the advantages of both the single solid board plank and the laminated plank while greatly reducing, if not eliminating, their respective disadvantages.

Composite scaffolding plank including natural wooden and laminated wooden boards and method of forming same