A dual actuator latch apparatus disposed in a direct access storage device for restraining a rotatably mounted actuator in a parked orientation in the presence of relatively low, moderate, and high levels of externally induced actuator acceleration is disclosed. An inertial latch assembly in preferably employed to prevent unrestrained actuator rotation from the parked orientation that would otherwise result from elevated levels of externally induced actuator acceleration. A separate magnetic latch assembly, or, alternatively, an electromagnetic latch assembly, is employed in tandem with the inertial latch assembly to prevent unrestrained actuator rotation and movement from the parked orientation in the presence of relatively low and moderate levels of externally induced actuator acceleration. The novel dual actuator latch apparatus is amenable for installation in standard form factor DASDs, and is particularly well-suited for incorporation in small and very small form factor DASDs.

In the data storage system manufacturing industry, various methods have been employed to minimize the detrimental influence of strong external rotational shock forces on the operation of the sensitive components comprising a direct access storage device (DASD). A typical DASD includes one or more data storage disks coaxially mounted on a hub of a spindle motor. The spindle motor rotates the disks at speeds typically on the order of several thousand revolutions-per-minute. Digital information is typically written to and read from the data storage disks by one or more magnetic transducer heads, or read/write heads, which are passed over the surfaces of the rotating data storage disks.
An actuator typically includes a plurality of outwardly extending actuator arms adapted to interleave one or more magnetic transducer heads mounted thereon into and out of the stack of data storage disks. During periods of DASD inactivity, the actuator is often restrained in a predetermined parked position by use of a passive locking or parking mechanism, such as a parking ramp apparatus, for example. The magnetic transducer heads are usually parked beyond the outer periphery of the data storage disks or over a dedicated portion of the disk surface, often termed a landing zone, situated away from the data storing portions of the disk.
Mishandling of either the DASD or a computer system into which the DASD is installed often results in displacement of the actuator from its parked position. Such direct and indirect mishandling often subjects the sensitive internal components of the DASD to significantly large rotational shock forces. The rotatably mounted actuator is generally susceptible to rotational forces and often rotates out of the parked position when the DASD is subjected to a sufficiently strong rotational shock force. Unrestrained movement of the actuator typically results in varying degrees of permanent damage to the sensitive surfaces of the data storage disks and to the magnetic transducers. A damaged region of the disk is generally unusable for subsequent storing of data. Also, any data stored at the damaged location may be irreparably lost.
Various methods and apparatus have been developed to reduce the potentially catastrophic results of unrestrained actuator rotation out of a preferred parked orientation during periods of DASD inactivity. In general, conventional latching mechanisms are designed to counteract detrimental actuator rotation within a limited range of acceleration. It is known in the art, for example, that commonly used inertial latching assemblies are generally effective for limiting unrestrained actuator rotation in the presence of high levels of externally induced actuator acceleration. It is also known in the art that commonly used magnetic or electromagnetic latch assemblies are generally effective for limiting such unrestrained actuator rotation in the presence of low levels of externally induced actuator acceleration.
A typical inertial latching assembly is designed to passively latch an actuator in a parked orientation until external rotational shock forces impinging the DASD are dissipated. Known inertial latches are typically mounted for rotation about a pivot axis in proximity to the actuator, and include a weighted portion and hook portion. In response to a sufficiently strong rotational shock force applied to the DASD, the hook portion of the inertial latch typically rotates about the pivot axis and engages a receiving hook or other capturing member protruding from the actuator. A biasing mechanism is generally employed to return the inertial latch to its original, non-engaged orientation after the external shock forces are dissipated.
Inertial latching mechanism are generally effective only at relatively high levels of externally induced actuator acceleration. Elevated levels of actuator acceleration must generally be present in order to overcome the force produced by the biasing mechanism required to maintain the inertial latching mechanism in its non-engaged orientation. Low to moderate levels of induced actuator accelerations are therefore not generally addressed when designing a conventional inertial latching mechanism.
In contrast, magnetic or electromagnetic latching mechanisms are generally effective only at relatively low levels of externally induced actuator rotational acceleration. In accordance with a conventional magnetic-type latching device, a magnetic coupling force of limited range is generally produced between the latching device and the actuator to restrain the actuator in an engaged or latched orientation. It is generally considered impractical to employ a magnetic-type latching device to counteract relatively high levels of externally induced actuator rotational acceleration. The intensity of the magnetic coupling force required to satisfactorily restrain a rotatable actuator in the presence of such high acceleration levels would typically require application of an excessively large force to free the actuator from the magnetic latch prior to initiating normal operation, and would likely interfere with the efficient operation of the actuator voice coil motor and other DASD operations. Also, electromagnetic latching mechanisms that employ a solenoid would require delivery of an appreciable amount of current to the solenoid in order to de-couple the latching device from the actuator. Such solenoids would generally be significantly larger than solenoids used in low-acceleration type electromagnetic latches, and would typically occupy an unacceptable amount of space within the relatively compact housing configurations of present and future small form factor DASDs.
A trend has developed in the DASD manufacturing community to miniaturize the chassis or housing of a DASD to a size suitable for incorporation into miniature personal computers, such as lap-top and hand-held computers, for example. Various industry standards have emerged that specify the external housing dimensions of small and very small form factor DASDs. One such recognized family of industry standards is the PCMCIA (Personal Computer Memory Card Industry Association) family of standards, which specifies both the dimensions for the DASD housing and the protocol for communicating control and data signals between the DASD and a host computer system coupled thereto. Recently, four families or types of PCMCIA device specifications have emerged. By way of example, a Type-I PCMCIA DASD must be fully contained within a housing having a maximum height dimension of 3.3 millimeters (mm). By way of further example, a Type-II PCMCIA device housing must not exceed a maximum height of 5.0 mm in accordance with the PCMCIA specification. A maximum height of 10.5 mm is specified for the housing of Type-III PCMCIA devices, and Type-IV devices are characterized as having a maximum housing height dimension in excess of 10.5 mm.
It is anticipated that the industry trend of continued miniaturization of DASDs will eventually result in the production of systems complying with the Type-II PCMCIA specification. Such Type-II PCMCIA DASDs will likely have external housing dimensions of approximately 54 mm.times.86 mm.times.5 mm, and include a data storage disk having a diameter of approximately 45 mm and a width dimension similar to that of a standard credit card. It will likely be highly desirable to employ an effective actuator latching assembly within such small and very small form factor DASDs, such as Type-II PCMCIA DASDs. Those skilled in the art, however, will appreciate the difficulties associated with employing an effective latching mechanism suitable for use within these very small form factor DASDs. The maximum allowable housing dimensions imposed by the Type-II PCMCIA specification, for example, necessarily results in a highly compact packaging configuration within the DASD housing, with minimal clearance and tolerances afforded between adjacent components.
Employment of prior art latching mechanisms within the compact environment of a small form factor DASD is generally considered problematic for a variety of reasons. A conventional inertial or magnetic-type latching mechanism generally occupies an appreciable amount of space within the compact DASD housing. More significantly, a conventional inertial or magnetic-type latching mechanism is generally effective within a relatively narrow range of externally induced actuator acceleration levels, thus rendering the actuator and other sensitive components of the DASD vulnerable to detrimental levels of induced acceleration outside the prescribed range. These and other characteristics of prior art actuator latching mechanisms generally represent significant limitations in the development and optimization of highly reliable, portable DASDs.
There exists within the DASD manufacturing community a need to provide effective protection against unrestrained actuator movement in the presence of a broad range of externally induced acceleration levels in order to minimize potential damage to the sensitive internal components of standard and miniaturized DASDs. There exists a further desire to incorporate the advantageous attributes of inertial and magnetic-type latching mechanisms within the compact packaging configurations of small and very small form factor DASDs. The present invention fulfills these and other needs.

Dual latch apparatus for restraining a direct access storage device actuator

International Business Machines Corporation


Methods for making optically blind reference pixels and systems employing the same. The reference pixels may be configured to be identical to, or substantially identical to, the active detector elements of a focal plane array assembly. The reference pixels may be configured to use the same relatively longer thermal isolation legs as the active detector pixels of the focal plane, thus eliminating joule heating differences. An optically blocking structure may be placed in close proximity directly over the reference pixels.

1. Field of the Invention
This invention relates generally to focal plane arrays, and more particularly to reference pixels for focal plane arrays
2. Description of the Related Art
Microelectromechanical systems (MEMS) are integrated micro devices or systems combining electrical and mechanical components. Some MEMS devices may be fabricated using standard integrated circuit batch processing techniques and have a variety of applications including sensing controlling and actuating on a micro scale. MEMS devices may function individually or in arrays to generate effects on a macro scale.
Certain MEMS devices require a vacuum environment in order to obtain maximum performance. The vacuum package also provides protection in an optimal operating environment for the MEMS device. Examples of these MEMS devices are infrared MEMS such as bolometers. In addition to the necessity of a vacuum or otherwise controlled environment for an infrared bolometer, infrared MEMS devices require an infrared-transparent cover, or lid structure. These lids are often coated with an anti-reflective coating to reduce the reflective properties and increase the infrared transmission properties of the lid.
Over the years, various types of infrared detectors have been developed. Many include a substrate having thereon a focal plane array, the focal plane array including a plurality of detector elements that each correspond to a respective pixel. The substrate contains an integrated circuit which is electrically coupled to the detector elements, and which is commonly known as a read out integrated circuit (ROIC) and which is used to integrate the signal from each detector element and multiplex the signals off the chip with appropriate signal conditioning and processing.
Each detector element includes a membrane which is suspended at a location spaced above the top surface of the substrate, in order to facilitate thermal isolation. The membrane includes a thermally sensitive material, such as amorphous silicon (a-Si) or vanadium oxide (VOx). The membrane also includes two electrodes, which are each coupled to the thermally sensitive material, and which are also coupled to the ROIC in the substrate. As the temperature of the thermally sensitive material varies, the resistance of the thermally sensitive material also varies, and the ROIC in the substrate can determine the amount of thermal energy which has been received at a detector element by sensing the corresponding resistance change of that detector element.
Uncooled infrared focal plane arrays operating at ambient temperature and without the use of active temperature stabilization require infrared optically blind reference pixels that do not absorb incident infrared radiation. These infrared optically blind reference pixels are used to determine ambient temperature of the focal plane which is required in the calibration of the focal plane array over the operating temperature of the focal plane array. This involves implementation of a gain and offset correction algorithm at any given temperature (sensed by the reference pixels) to the active detector elements in order to correct the image for ambient temperature drift effects, e.g., in an imaging focal plane array.
In the past, reference pixels have been made infrared optically blind by using short thermal isolation legs for the suspended infrared absorbing element in combination with placement of an infrared reflecting aluminum metallization directly on the reference pixel. However, reference pixels fabricated in this way have less Joule heating (e.g., in a voltage-biased suspended microbolometer structure) due to the shorter legs and to a lesser extent the added thermal mass of the aluminum reflector. As such, the output of the reference pixel as read out using a ROIC tends to diverge from the output of the infrared responsive suspended pixel detector elements, thereby limiting dynamic range both in terms of scene temperature and ambient temperature operating ranges.

Optically blocked reference pixels for focal plane arrays


An asphalt composition comprising 0.5 to 50 parts by weight of a block copolymer component (I), 100 parts by weight of an asphalt (II) and 0.01 to 10 parts by weight of at least one vulcanizing agent (III) selected from the group consisting of sulfur and a sulfur-containing compound, wherein the block copolymer component (I) comprises at least one modified block copolymer comprising an unhydrogenated or hydrogenated base block copolymer comprising at least one vinyl aromatic polymer block (A) and at least one conjugated diene polymer block (B), and a functional group-containing modifier group bonded to the base block copolymer.

1. Field of the Invention
The present invention relates to an asphalt composition. More particularly, the present invention is concerned with an asphalt composition comprising a block copolymer component (I), an asphalt (II) and at least one vulcanizing agent (III) selected from the group consisting of sulfur and a sulfur-containing compound, wherein the block copolymer component (I) comprises at least one modified block copolymer comprising a base block copolymer comprising at least one vinyl aromatic polymer block (A) and at least one conjugated diene polymer block (B), and a functional group-containing modifier group bonded to the base block copolymer. The asphalt composition of the present invention is advantageous not only in that it has a high softening point and excellent properties with respect to ductility, storage stability at high temperatures and flexural properties at low temperatures, but also in that, when the asphalt composition is used in road paving, there can be formed a pavement layer having excellent dynamic stability and excellent aggregate-gripping properties. Therefore, the asphalt composition of the present invention is very suitable for use in road paving. Thus, the asphalt composition of the present invention can be advantageously used as a binder for road paving, especially as a binder for forming a drainage pavement.
2. Prior Art
Conventionally, an asphalt composition has been used in a wide variety of fields, such as the fields of a material for use in road paving, a material for a waterproof sheet, a material for a sound insulating sheet and a roofing material. In these fields, a number of attempts have been made to improve the properties of the asphalt composition by adding various polymers to the asphalt composition. As examples of such polymers, there can be mentioned an ethylene/vinyl acetate copolymer, an ethylene/ethyl acrylate copolymer, a rubber latex, and a block copolymer comprising conjugated diene monomer units and vinyl aromatic hydrocarbon monomer units.
However, in recent years, due to the expansion of traffic and the increase in the number of expressways, there is a growing demand for an asphalt mixture (which is comprised of a plurality of aggregates and an asphalt composition as a binder) having excellent strength and excellent abrasion resistance. Further, there is a growing demand for an asphalt mixture which not only has excellent strength and excellent abrasion resistance, but also can be used to form a highly open graded pavement layer which can improve the drainage properties and noise reduction properties of expressways. For achieving the above-mentioned excellent properties, the asphalt composition is required to have a high softening point and high mechanical strengths (such as high flexural stress and excellent aggregate-gripping properties). For meeting this requirement, it has been attempted, for example, to employ a method in which a block copolymer having a high molecular weight is incorporated into the asphalt composition. However, such method is disadvantageous in that the resultant asphalt composition containing a high molecular weight block copolymer incorporated therein has unsatisfactory storage stability at high temperatures and, hence, its melt viscosity becomes increased under high temperature conditions, thus rendering poor the workability of the asphalt composition during the road paving.
For improving the storage stability of an asphalt composition at high temperatures, it has generally been attempted to add an aromatic process oil to the asphalt composition, or effect a crosslinking of the asphalt composition by the use of sulfur or a peroxide. For example, Examined Japanese Patent Application Publication No. Sho 57-24385 (corresponding to U.S. Pat. No. 4,145,322) discloses a crosslinking using sulfur. On the other hand, Examined Japanese Patent Application Publication No. Hei 1-13743 (corresponding to U.S. Pat. Nos. 4,554,313 and 4,567,222) discloses a crosslinking using a polysulfide having a specific structure. Further, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 3-501035 (corresponding to U.S. Pat. No. 5,508,112) discloses a crosslinking using a combination of sulfur as a vulcanizing agent and a sulfur-containing compound as a vulcanization accelerator. However, any of the above-mentioned techniques is still unsatisfactory in improving the storage stability of an asphalt composition at high temperatures. Also, it has been desired to develop an asphalt composition which not only has excellent storage stability at high temperatures, but also can be used for forming a pavement layer having excellent dynamic stability and excellent aggregate-gripping properties.


A method to make a tubular element to transfer abrasive materials such as concrete, inert materials or suchlike, where the tubular element includes an external tubular component made of steel and an internal tubular component, coaxial to the external tubular component, where the internal tubular component is made of chromium carbide, or other similar material resistant to wear.

In the field of construction in its widest sense the use of modular tubular elements is known, which are connected together to make a pipe that allows to transfer construction materials, such as for example concrete, inert materials, or suchlike, which are very abrasive, from a container, such as for example a cement mixer truck, to a casting zone, by means of pumping devices.
Known pipes normally consist of one or more tubular elements, or segments, rectilinear and/or curved, connected together in sequence by means of tubular joints, or connection elements, which have standardized angles of longitudinal development, such as for example 15°, 30°, 45°, 60° or 90°.
The tubular elements are subjected to an action of abrasion of their internal surfaces, mainly due to the action that the transported material exerts on said internal surfaces, especially in the case of curved elements, in the part that during use is on the outside of the curve, that is, along the extrados.
Normally, each tubular element comprises an external tubular component, which defines the external layer, and an internal tubular component, coaxial with the external tubular component and which defines the internal layer.
The function of the internal tubular component is to resist wear and it is made, for example, of tempered steel, for example C60. The function of the external tubular component, on the other hand, is to mechanically resist internal pressure and protect the internal tempered part from the impacts that can occur during normal use. It is made, for example, of common carbon steel, for example non-tempered steel S355. Furthermore, the tubular element in question, consisting of an internal tubular component and an external tubular component, must be sized to withstand an internal working pressure, therefore continuous, typically equal to 85 bar.
The method to make a tubular element of this type requires multiple steps known in the state of the art, amongst which the most significant in terms of costs and time is certainly the tempering step. In fact, this is performed by heating and cooling the two coaxial tubular components together, which constitute the tubular element, so that, due to the type of materials with which they are made, only the internal tubular component is tempered, while the external one is not.
The internal tubular component, once tempered, is extremely fragile, therefore the presence is necessary of the external tubular component which, on the contrary, not being tempered, remains ductile.
Given the extreme fragility of the internal tubular component, a very important aspect that determines the quality of the final product is the degree of coupling between the internal and external tubular components. The precision of the coupling, in fact, determines the maximum working pressure of the product obtained.
The joining of the two tubular components normally takes place in a step, called flaring, which precedes the tempering step. The flaring occurs by means of the mechanical deformation of the internal tubular component, by means of a punch that deforms it and thrusts it against the internal wall of the external tubular component.
Therefore, normally, the flaring step entails a plastic deformation of the internal tubular component against the external tubular component. As an alternative, it is known to deform the external tubular component using a matrix, that is, by simultaneously thrusting the two tubular components inside a cone, crushing the external wall on the inside before tempering.
Methods are also known which are able to obtain the same result by plastically deforming the external tubular component against the internal one.
The extent of the contact pressure between the two tubular components, due to various factors, such as the original ovalization of the unworked tubular components, the imperfect concentricity of the two tubular components and the local deformations, can lead to an incorrect adhesion of the two tubular components.
The known method to make a complete tubular element is therefore very complex and expensive, as multiple processes are provided, some of which, such as tempering, are relatively critical for the repeatability of the production process.
The Applicant's international patent application WO-A-2016/151370 discloses a method and an apparatus to make a tubular segment comprising obtaining an external tubular element and an internal tubular element made of a material with a resistance to wear greater than that of the external tubular element, and with a cross-section that covers at least part of the internal surface of the external tubular element. This known document also provides to insert the internal tubular element inside the external tubular element, after the latter is heated by means of a pre-heating system which uses a suitably sized furnace or inductor. Furthermore, in order to shape the external tubular element on the exact geometry of the internal tubular element, the use of a molding unit and a cooling unit is provided, to obtain a tubular segment without empty spaces between the external tubular element and the internal tubular element. However, this known method, although effective and reliable, is complex and requires long execution times.
A method to make a curved tubular joint is also known from document WO-A-2012/017286, which comprises the use of a curved anti-wear insert which, during use, is disposed inside the curved tubular element and through which the abrasive material to be transferred passes. During the production of the curved tubular joint, the curved anti-wear insert is disposed inside a mold and molten steel is cast around its peripheral surface to produce an external jacket which, once solidified, forms the external part of the tubular joint. However, this method to is complex and requires long execution times.
CN 102 278 550 describes a pipe to transfer concrete comprising an internal anti-wear layer and an external layer resistant to impacts. WO 2013/004018 also describes a pipe to transfer concrete comprising an internal anti-wear layer and an external layer resistant to impacts.
One purpose of the present disclosure is to provide a tubular element to convey construction materials, such as for example concrete or other abrasive materials in a fluid state, which is reliable and maintains its resistance to wear for a long time, and which is also simple to produce, relatively light and economical.
Another purpose of the present disclosure is to perfect a method to produce a tubular element to transfer abrasive materials, for example concrete, or other abrasive materials, which is relatively simple, economical and fast in terms of execution time.
The Applicant has devised, tested and embodied the present disclosure to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

Tubular element to transfer abrasive materials, in particular concrete, and method to make it


A mill blank assembly for a dental prosthesis includes a milling section and a support section for supporting the assembly in a milling machine. In certain embodiments, the milling section is adhesively bonded to the support section by a direct chemical bond that provides enhanced resistance to unintentional detachment of the milling section from the support section during a subsequent machining operation. Optionally, the support section includes a passageway that receives a quantity of flowable dental restorative material used to make the milling section, such that the restorative material that is located in the passageway provides additional resistance when hardened to unintentional detachment of the milling section from the support section.

1. Field of the Invention
This invention broadly relates to a mill blank assembly used in the field of dentistry to create an inlay, onlay, crown, veneer, coping, bridge, bridge framework, implant, implant abutment or other restoration or restoration component. More specifically, the present invention is directed to a mill blank assembly that is especially adapted for use with computer-aided design and machining processes to create a dental prosthesis. The present invention is also directed to a method for making a dental mill blank assembly.
2. Description of the Related Art
A variety of dental procedures are known for replacing or repairing damaged, weakened or missing tooth structures. For example, a dental prosthesis commonly known as a filling is often used to fill cavities in teeth caused by tooth decay or caries. Somewhat larger prosthetics also used to fill cavities are known as inlays and onlays. Fillings, inlays and onlays may also be utilized to restore the shape of teeth that have been chipped or broken.
Other types of dental prosthetics include bridges, full crowns and partial crowns. Typically, these prosthetics are much larger than fillings and as a result are often more visible in the oral cavity. Full and partial crowns may be supported by remaining portions of the original tooth structure and/or by a post extending toward the bony region of the jaw. Bridges, on the other hand, are structures that connect to adjacent tooth structure and provide an artificial tooth or tooth crown to replace corresponding, missing structure.
In the past, fillings and some inlays and onlays were often made of a silver-colored metal alloy known as amalgam due to its relatively long life and relatively low cost. Another advantage offered by amalgam is that it allows a dental practitioner to fit and fabricate the restoration during a single session with a patient. Unfortunately, amalgam is not considered aesthetic since its silver color sharply contrasts to the appearance of natural teeth in the oral cavity.
Another material used for dental prosthetics, and particularly for larger inlays and fillings, is gold. However, like amalgam, the color of gold sharply contrasts with the appearance of natural teeth and is highly visible in the oral cavity. In addition, gold is relatively expensive in comparison to other dental materials.
As a consequence, many dental practitioners are increasingly turning to ceramic or polymer-ceramic composite materials for use to make dental prosthetics. Dental ceramic materials and dental polymer-ceramic composite materials can provide an appearance that closely matches the appearance of natural teeth. Such materials are also available in various color shades so that the practitioner can select a color that closely matches the color of adjacent tooth structure.
Dental polymer-ceramic composite materials for use as restoratives are available from various manufacturers in paste-type form. Such materials are often supplied in capsules that are releasably received in a receptacle of a hand-held dispenser. The dispenser typically includes a lever that, when depressed, extrudes a quantity of the material from the capsule and directly onto the tooth structure. The material includes a polymerization initiator that serves to harden the material once it has been placed on the tooth structure and shaped by the practitioner to resemble natural tooth structure.
A variety of techniques may be employed to help shape the unhardened restorative paste to a desired configuration once dispensed onto the patient's tooth structure. For example, if the material is used to fill a relatively small cavity, the material can be dispensed directly into the cavity and then shaped by hand. A hand instrument such as a dental pick is used to help pack the material in the cavity and to blend the external surface of the paste with adjacent, external portions of the patient's tooth. As another example, if a portion of one or more sides of a tooth is to be restored, the practitioner may elect to use a matrix band or sectional matrix band next to the tooth structure to help hold the material in place while it hardens. The matrix band or sectional matrix band serves as a formwork, similar to formwork used in concrete, to help hold the material in place and also to help define an outer surface of the composite material while it hardens.
However, larger prosthetics are often fabricated outside of the oral cavity and then placed in the patient's oral cavity once completed. For these types of prosthetics, an impression is often taken of the patient's tooth structure of interest along with adjacent regions of the gingiva, using an elastomeric impression material that provides a negative physical image of the tooth structure and gingival region. Next, a cast positive model is made by pouring a quantity of plaster of Paris into the impression and allowing the plaster of Paris to harden. The resulting plaster of Paris or "stone" model is then used in the laboratory to make a prosthetic that is ultimately transferred to the patient's oral cavity.
The laboratory procedure for making the prosthetic may be somewhat involved, depending on the type of prosthetic that is needed. In one method, for example, a wax replica of the desired crown is built on the stone model. The wax replica is then embedded in a refractory investment material and fired to create another negative physical image of the oral structure of interest. Porcelain is then forced into the investment material under pressure and heat in order to make the crown.
However, a number of disadvantages arise when the foregoing procedure is followed to make a crown. In such a procedure, the patient typically travels to the practitioner's office two times: a first time to enable an impression to be taken, and a second time a few days later after the stone model has been made and the crown has been fabricated in the dental laboratory. Moreover, if the completed crown must be returned to the laboratory because its shape, fit or appearance is not satisfactory, the patient is often then required to return to the dental office for a third visit. In many dental practices, the crown is not made in a laboratory that is part of the office but is instead sent to a central laboratory in another area of the town or region.
Furthermore, the fabrication of custom dental crowns and other prosthetics by hand from stone models is an art that involves a high degree of skill and craftsmanship, as well as intensive labor. Moreover, prosthetics that are placed in the anterior regions of the patient's oral cavity are often highly visible. It is widely considered difficult to make a porcelain prosthetic that exactly matches the translucency and color of natural teeth.
Recently, increased interest has been directed toward the use of computer automated machinery for fabricating dental prosthetics, using far less labor than prior methods such as the method for making a crown described above. For example, several systems are known for collecting a set of electronic data that is representative of the patient's tooth structure of interest. The data is then used by an automated mechanical milling machine (such as computer-aided milling machine) to fabricate a prosthetic that, when completed, closely matches the shape of natural tooth structure.
Examples of computer-aided milling machines used in the field of dentistry include the CEREC 2™ and CEREC 3™ machines available from Sirona Dental Systems of Bensheim, Germany, the DICEM™ machine from Dentronix, the VITA CELAY™ machine from Vita Zahn Fabrik of Bad Säckingen, Germany, the PRO-CAM™ machine from CadCam Ventures, of Dallas, Tex. and the PROCERA ALL CERAM™ machine from Nobel Biocare USA of Westmont, Ill. U.S. Pat. Nos. 4,837,732, 4,776,704 and 4,575,805, as well as PCT Patent Application No. WO 96/37163 also disclose systems for making dental prosthetics using computer-aided milling machines.
The fabrication of a dental prosthesis using a computer-aided machining system typically involves the use of a "mill blank", a block of material from which the prosthetic is cut. Dental mill blocks are often made of a ceramic material. Commercially available dental mill blanks include VITA CELAY™ porcelain blanks from Vita Zahn Fabrik, VITA NCERAM™ ceramic blanks from Vita Zahn Fabrik, MACOR™ micaceous ceramic blanks from Corning, and DICOR™ micaceous ceramic blanks from Dentsply. A dental mill blank made of a ceramic silica material as described in U.S. Pat. No. 4,615,678. An improved ceramic dental mill blank is described in applicant's co-pending PCT application entitled "CERAMIC DENTAL MILL BLANKS", PCT US00/19887, filed Aug. 26, 1999.
Dental mill blanks may also be made of resinous materials. An example of a dental mill blank made of a polymeric resin and a filler is described in applicant's co-pending PCT patent application entitled "DENTAL MILL BLANKS", PCT US99/10966, filed Jan. 8, 1999. Dental mill blanks made of such material exhibit superior milling characteristics such as hardness and cutting properties relative to previously known dental mill blanks.
Many commercially available dental mill blanks are made of a two-piece construction that comprises a support stub section and a milling blank section. The support section is cylindrical and adapted to fit into a collet or a Jacobs chuck of a milling machine. Often, the support section is made of metal, since the support section is ultimately detached from the milling section and does not form part of the finished prosthetic. The support section is typically made of a relatively soft metallic material such as an aluminum alloy that is easy to machine to precise tolerances.
The milling section of conventional two-piece dental mill blank assemblies is often made of one of the aesthetically-pleasing restorative materials described above so that the resulting prosthetic provides a natural appearance once placed in the oral cavity. The milling section of conventional assemblies has a flat face that is joined to a flat face of the support section by an adhesive. An example of one type of two-piece construction is described in U.S. Pat. No. 4,615,678.
It has been observed, however, that conventional dental mill blank assemblies occasionally fracture during the milling process. In some instances, the fracture occurs in the joint between the support stub section and the milling section. It is suspected that lateral forces exerted by the milling tool on the milling section create a shear force that exceeds the strength of the adhesive bond of the joint.
Unfortunately, if the milling section has broken away from the support section before the milling process has been completed, the mill blank assembly must be discarded and replaced with a new assembly. Consequently, the fracture of dental mill blank assemblies represents a time-wasting nuisance to the personnel operating the milling system and possibly to the patient. Replacement of the dental mill blank assembly with a new assembly also represents an additional cost to the dental laboratory, the dental practitioner and the patient that is best avoided if at all possible.
Applicant's previously filed patent application, U.S. Ser. No. 09/653,230 entitled "DENTAL MILL BLANK AND SUPPORT STUB ASSEMBLY" describes an improved two-piece mill blank assembly. In that assembly, a projection extends from the milling section or the support section into the remaining section and helps resist unintentional detachment of the sections from each other during a machining operation. While the inventions described in that patent application represent a significant improvement over past practice, there is a continuing need to further advance the state of the art with respect to dental mill blank assemblies.


A dental material delivery system includes an applicator having a proximal segment, a median bending segment and a tip; an elongated handle; and a cap. The proximal segment of the applicator is nonremovably frictionally mounted within a proximal bore section of the handle, the median bending segment of the applicator is aligned generally longitudinally with an annular weakened wall line of the handle, and the tip of the applicator extends into a distal bore section of the handle. A quantity of dental material is disposed within the distal section of the handle. The cap is mounted to the handle adjacent the distal end of the handle to seal the handle. The wall of the handle is separable at the annular weakened wall line to permit withdrawal of the applicator tip and transfer of the dental material to a surface.

This invention relates to a unit dose dispenser (i.e., delivery system) that includes an applicator for applying a composition to a surface. The invention also relates to a method for forming the dispenser.
Applicators for applying compositions to surfaces are in widespread use in a variety of medical, commercial and household applications. Typical examples of such applicators include brushes and swabs having an overall stick-like configuration. Applicators that are relatively inexpensive represent a significant convenience to the user, in that the applicator can be disposed of after a single use.
In some instances, disposable applicators are individually packaged in closed, sealed containers. Individually packaged applicators are an advantage in medical and dental operations because sterility of the applicator can be assured until such time as the applicator is removed from the package in preparation for use. Examples of known packaged applicators include swabs that are contained between two sheets of a plastic or paper film, and swabs that are contained within a plastic tube or casing.
In some procedures, the composition to be applied by the applicator is provided in bulk containers. In those instances, the users may elect to dip the swab or brush tip of the applicator directly into the container in order to coat the tip with a small quantity of the composition. The tip is then removed from the container and moved across the desired surface in order to transfer the composition from the tip to the surface.
However, the practice of dipping the applicator tip directly into a bulk container is not satisfactory in many medical and dental applications due to the possibility of cross-contamination between patients. For example, if the applicator is used in a dental procedure to apply an adhesive to the surface of tooth structure, the practitioner may unknowingly transfer infectious disease from one patient to another if the applicator is returned to the bulk container after initial use in the oral cavity. The issue of cross-contamination can be avoided by using a new applicator in those instances where additional composition is needed, but such practice represents an additional expense and also requires a certain amount of time for retrieving, opening and preparing a new packaged applicator for use.
The problems of cross-contamination as mentioned above can be avoided by use of a dispensing well or pad. For example, in dental procedures a small quantity of composition is dispensed from the bulk container onto the well or pad, and the tip of the applicator is then used to transfer the composition from the well or pad to the patient's tooth structure. Such practice avoids the need for returning the applicator to the bulk container so that issues of cross-contamination between patients can be avoided. Once the procedure has been completed, the well or pad is disposed of or cleaned for reuse.
In recent years, there has been increased interest in packaged, disposable applicators having a tip that is pre-supplied with a quantity of a composition. These prepackaged applicators are a significant advantage in that the time that would otherwise be associated with handling of a bulk container and a disposing well or pad can be avoided. Moreover, such packaged applicators are a particular advantage when used with compositions that are messy or that are considered hazardous. Current single dose applicator assemblies are of a single size and only permit a specific quantity of composition to be pre-supplied to the applicator tip. However, not all procedures require the same amount of composition, and tip lengths and tip materials of the applicator for various procedures can vary.
Furthermore, in packaged applicator assemblies including a handle, applicator and receptacle portion, the applicator is typically removable from the handle to interchange applicators for various procedures. However, practitioners desire a single dose delivery system whereby an applicator removable from the handle is not desired to prevent problems with attaching the applicator or the applicator falling out of the handle.
One example of a packaged applicator assembly is described in U.S. Pat. No. 6,413,087 and includes an applicator having a tip that is pre-supplied with a single dose quantity of composition material. The applicator includes a cap initially extending over the tip and detachably connected to the applicator. The applicator includes a flexible portion that can be bent as the cap is detached from the applicator.
There is still a need to protect the packaged, disposable applicator and container from moisture and other contaminants. Thus, the packaged applicator and container are individually wrapped in a foil pouch for storage to protect the applicator and container and extend the shelf-life of the assembly. However, the foil pouch, or other suitable packaging increases the cost of the assembly.
Although a variety of applicators and application methods are known in the art, there exists a need for an improved applicator such that manufacture, use and storage of applicators and containers are enhanced. Such improvements should facilitate handling of the applicator, dispensing of the composition and result in manufacture ease without increasing the overall cost of the assembly or resulting in contamination of the composition.

Dental material storage and delivery system and method


The current disclosure describes techniques for managing vertical alignment or overlay in semiconductor manufacturing using machine learning. Alignments of interconnection features in a fan-out WLP process are evaluated and managed through the disclosed techniques. Big data and neural networks system are used to correlate the overlay error source factors with overlay metrology categories. The overlay error source factors include tool related overlay source factors, wafer or die related overlay source factors and processing context related overlay error source factors.

With the evolving of semiconductor technologies, semiconductor dies are becoming increasingly smaller, while increasingly more functions are integrated into a single die. Accordingly, increasingly greater number of I/O pads need to be included in an integrated circuit ("IC") package together with smaller areas of die surfaces. Fan-out type wafer level packaging ("WLP") became a promising packaging technology to tackle this challenging scenario. In fan-out WLP, dies are severed from the original front-end wafers before they are positioned on a carrier wafer to package with connection wirings and I/O pads. In the fan-out WLP process, an advantage is that the I/O pads associated to a die can be redistributed to a greater area than the surface of the die itself. As such, the number of I/O pads packed together with a die can be increased.
The fan-out WLP package may be used to pack one die, multiple dies side-by-side or multiple dies in a package-on-package ("POP") vertical configuration. The POP configuration in fan-out WLP is achieved through interconnection features, such as a via, that connect multiple dies vertically.
Overlay metrology processes are used to monitor and control vertical alignments in various semiconductor manufacturing processes. An overlay metrology generally specifies how accurately a first patterned layer or a feature thereon aligns with respect to a second patterned layer disposed at a different vertical level from the first patterned layer, e.g., vertical alignment. An overlay error refers to a misalignment between a first part on the first patterned layer to a second part on the second patterned layer. An overlay error metrology, e.g., measurements, may be measured based on an offset between the first part and the second part or between an actual position of the first part and a target position of the first part. The target position may be determined based on advanced process control ("APC") in wafer processing.
In fan-out WLP, tested-good dies are positioned onto a carrier wafer. Layers of interconnection features are formed connecting the die to the associated I/O pads and among the various layers of interconnections themselves. The interconnections are formed through wafer level processes, where photoresist and photolithography processes are used similarly as in the front-end wafer fabrication processes. Therefore, vertical alignments between or among sequential layers of the interconnections need to be managed.

Machine learning on overlay virtual metrology

Taiwan Semiconductor Manufacturing Go., Ltd.


A method and apparatus for catalytically processing a gas stream passing therethrough to reduce the presence of NOx therein, wherein the apparatus includes a first catalyst composed of a silver-containing alumina that is adapted for catalytically processing the gas stream at a first temperature range, a second catalyst composed of a copper-containing zeolite located downstream from the first catalyst, wherein the second catalyst is adapted for catalytically processing the gas stream at a lower second temperature range relative to the first temperature range, a hydrocarbon compound for injection into the gas stream upstream of the first catalyst to provide a reductant, and a reformer for reforming a portion of the hydrocarbon compound into H2 and/or oxygenated hydrocarbon for injection into the gas stream upstream of the first catalyst. The second catalyst is adapted to facilitate the reaction of reducing NOx into N2, whereby the intermediates are produced via the first catalyst reacting with NOx and hydrocarbons.

A continuing effort has been made over the years for developing methods and systems for removing pollutant gases from exhaust gases produced by combustion equipment. In recent years, environmental regulations have been made law in numerous countries around the world in an effort to reduce the emission of pollutant gases into the atmosphere from combustion equipment. Of major concern is the production of nitrogen oxides (NOx) by motor vehicles driven by internal combustion engines, such as gasoline driven engines, and particularly diesel engines. Other combustion apparatus are also of concern, such as furnaces installed in factories, commercial and home heating devices, power plant equipment, and so forth.
During the combustion process in such equipment when nitrogen in the air reacts with oxygen within a combustion chamber, under the high temperature and pressure conditions that typically exist therein, such as in the cylinder of an internal combustion engine, nitrogen oxides (NOx) are produced, which typically include either one or a combination of nitrogen monoxide and nitrogen dioxide, commonly referred to as NOx emissions. The NOx emissions are major atmospheric pollutants that cause smog, and acid rain. The major industrialized countries throughout the world have instituted regulations for reducing NOx emissions.
As a result, a major effort has been ongoing over an extended period of time for developing methods and systems to substantially eliminate the emission into the atmosphere of nitrogen oxides or NOx via exhaust gas streams from combustion equipment. Recognizing that automobile emissions are a major source of air pollution, in the 1966 automobile model year, the state of California passed regulations requiring the use of exhaust emission control systems in vehicles sold in California. Similar regulations were instituted throughout the United States by automotive model year 1968.
In combustion processes, the "perfect mixture" of a fuel and air is referred to in thermodynamics by the term "stoichiometric." This is the point at which the amount of air is just enough to combust all of the fuel, with no excess oxygen remaining. For many reasons, internal combustion engines cannot be run stoichiometrically, and are typically run lean, where there is an excess of oxygen to fuel relative to the stoichiometric condition. Although both gasoline and diesel internal combustion engines are typically run as lean-burn engines, such a condition is most often found in operating diesel engines, and leads to the emission of undesirable amounts of NOx in the exhaust gases from such engines. At times engines may run rich, that is with an excess of fuel relative to oxygen. Note that for gasoline, the stoichiometric mixture is 14.6:1. Even under these conditions, some nitrogen from the air can react with oxygen to form NOx.
The exhaust gas stream from lean-burn engines contain significant amounts of oxygen, thereby preventing the efficient removal of NOx from the gas stream through use of conventional exhaust catalysts such as a "3-Way Catalyst." As a result, NOx trap or NOx storage/reduction systems have been developed to assist in removing NOx from current lean-burn engines. However, these systems must rely on close engine control for alternating between rich and lean conditions in the exhaust gas stream. During the lean phases, the catalyst employed stores NOx. During the rich phases, the catalyst reduces NOx to N2. Also, HC-SCR systems have been developed as retrofits for use in reducing NOx from the exhaust gas stream of internal combustion engines, but such systems have found only limited use.
An attractive aftertreatment technology for active NOx control from an implementation point of view is one based on a catalyst system that utilizes on-board hydrocarbon (e.g. diesel fuel) as the source of the required supplemental reductant. The advantages of a Lean-NOx catalyst technology are its simplicity in terms of engine control, aftertreatment system and infrastructure implementation requirements compared to other technologies, such as NOx adsorbers or urea SCR. However, the state-of-the-art Lean-NOx technology for diesel engine applications is only able to achieve approximately 25-30% NOx reduction when supplemental diesel fuel is injected into the exhaust stream. Zeolites and noble metal based catalysts are the most common catalyst materials for Lean-NOx technology developed by catalyst suppliers for real applications with full size bricks. Poor hydrothermal stability, low NOx reduction selectivity and high sulfate formation are major issues of these materials for application as NOx control of diesel exhaust, particularly when applied to diesel exhaust at engine modes that produce low temperatures.
Accordingly, there is a need in the art for improved methods and apparatus for removing NOx from the exhaust gas stream of a combustion device, such as internal combustion engines.


An embodiment of the present invention relates to a worldwide network of differential GPS reference stations (NDGPS) that continually track the entire GPS satellite constellation and provide interpolations of reference station corrections tailored for particular user locations between the reference stations Each reference station takes real-time ionospheric measurements with codeless cross-correlating dual-frequency carrier GPS receivers and computes real-time orbit ephemerides independently. An absolute pseudorange correction (PRC) is defined for each satellite as a function of a particular user's location. A map of the function is constructed, with "iso-PRC" contours. The network measures the PRCs at a few points, so-called reference stations and constructs an iso-PRC map for each satellite. Corrections are interpolated for each user's site on a subscription basis. The data bandwidths are kept to a minimum by transmitting information that cannot be obtained directly by the user and by updating information by classes and according to how quickly each class of data goes stale given the realities of the GPS system. Sub-decimeter-level kinematic accuracy over a given area is accomplished by establishing a mini-fiducial network.

1. Field of the Invention
The invention relates generally to the global positioning system (GPS) and specifically to methods and devices that allow a user to reduce GPS navigation errors.
2. Description of the Prior Art
The global positioning system (GPS) is a United States funded satellite system consisting of sixteen to twenty-four satellites in a constellation that beams highly accurate timed signals to earth. GPS receivers can process these signals from anywhere in the world and provide a user with position information that can be accurate to within twenty meters. Each GPS satellite moves through a known orbit and the time that individual GPS satellite transmissions take to reach a user's position are used in solving a triangulation problem. The individual signal paths from each satellite to the user's position must pass through the troposphere and ionosphere. Position solution errors can occur when there is not accurately accounted for radio signal propagation delays caused by the troposphere and ionosphere. The ionosphere introduces its maximum delays about 2:00 PM local time and has practically no effect at night. Thus, the local time may be important to a position solution. The troposphere can introduce delays that are a function of barometric pressure, temperature, humidity and other weather variables. Variations in the actual orbit of each GPS satellite can also have an impact on position solution accuracy. Drifts in the clock of each GPS satellite will also impact user position solution accuracy. Service bureaus and agencies have been established to sell or otherwise provide differential data. Such data range from real-time local information to sometimes very complex mathematical models based on long-term observations. US Government agencies issue orbit correction information on a satellite-by-satellite basis.
Dual frequency carrier GPS receivers continuously track P-code L1 and L2 carriers of a GPS satellite to generate accumulated delta-range measurements (ADR) and at the same time track L1 C/A-code to generate code phase measurements. Each carrier is modulated with codes that leave the GPS satellite at the same clock time. Since the ionosphere produces different delays for radio carriers passing through it having different radio frequencies, dual carrier receivers can be used to obtain real-time measurements of ionospheric delays at a user's particular position. (L1 is typically 1575.42 MHz and L2 is typically 1227.6 MHz.) The L1 and L2 ADR measurements are combined to generate a new L1 ADR measurement that has an ionospheric delay of the same sign as the ionospheric delay in the L1 pseudorange. Accurate ionospheric delay figures, if used in a position solution, can help produce much better position solutions. Without such real-time ionospheric delay measurements, mathematical models or measurements taken by third parties (which can be old) must be used instead. The communication of this information to a user's site can be costly and require wide communications channel bandwidths.
Commercial and private users have been able to make use of GPS satellite transmissions even though they use so-called "unauthorized" receivers. "Authorized" receivers are able to receive special information (P-code) that can remarkably improve position solution accuracy. Since an enemy could use GPS to fly and target missiles and artillery shells to better than one meter of accuracy, the United States Department of Defense occasionally engages a selective availability (SA) mode, spoofing and encryption of the GPS signals that deliberately introduce solution errors into user receivers that lack an authorization code needed to see through the masking. A "codeless" unauthorized GPS receiver is able to cross-correlate the L1 and L2 signals and extract enough information to measure the ionospheric delay (although not enough to overcome SA or to read P-code encrypted by Y-code to secure transmissions.)
With differential GPS, a stationary reference receiver is placed at a very accurately known point location. The reference receiver generates corrections which are sent to a transmitter, which in turn broadcasts the corrections to users within the area of the transmission broadcast. A differential GPS user receives these corrections through a radio/modem and applies them to the direct GPS measurements. This gives the user a position measurement of very high accuracy, e.g., from one meter to ten meters.
However, as a user's receiver is moved away from a reference receiver, the corrected accuracy will gradually deteriorate. Thus, the region of usefulness is finite. By employing a network of reference stations, the accuracy achievable by users near a reference station can be had throughout a region of several hundred miles.
While advantages of differential GPS networks have been well known, the basic problems to realization of them are many. A means of reducing the communications volume between the reference stations is needed in order to keep the cost of service down and thus to be competitive. A means of reducing the communications volume between the reference station and the user population is needed. Also needed are effective techniques and algorithms that enable a minimum number of reference stations to be employed. Effective techniques and algorithms are needed that provide high accuracy throughout a large operating region, for example, worldwide in a band of latitudes that include most of the populated areas.
A paper written by Alison Brown, titled "Extended Differential GPS," published by Navigation: Journal of the Institute of Navigation, in Vol. 36, No. 3, Fall 1989, pp. 265-285, presents an extended differential GPS concept that uses a network of differential GPS stations. A differential GPS message can be computed that provides corrections for the different components of the pseudorange error. This is reported to extend differential GPS navigation accuracy to one thousand nautical miles from a master differential station.


A measuring device includes a first measuring hopper, a first supply portion arranged above the first measuring hopper to supply the objects to the first measuring hopper, a second measuring hopper, a second supply portion fixedly arranged above the second measuring hopper to supply the objects to the second measuring hopper, a plurality of accommodating hoppers circumferentially arranged below the first and second measuring hoppers, and a control portion configured to control the second supply portion and the plurality of accommodating hoppers such that an accommodating hopper discharges the objects only if the total weight of the objects in the accommodating hopper that are discharged from the first and second measuring hoppers is substantially and no smaller than the predetermined weight. The plurality of accommodating hoppers are intermittently circulated such that each of the accommodating hoppers successively receives the objects from the first and second measuring hoppers.

1. Field of the Invention
The present invention relates to a measuring device for an object or an article.
2. Background Information
Measuring devices have been conceived in which a plurality of hoppers are arranged circumferentially, and operations of supplying, measuring and discharging the objects are performed while circulating these hoppers.
According to the invention of the Japanese Utility Model Publication No. H4-069731 (pp. 4-5, FIG. 1), three operations, i.e., supplying, measuring and discharging the objects are performed intermittently in a circular manner for obtaining objects having a predetermined weight quickly. According to this prior art, however, since the measuring is performed after the objects are supplied, it is difficult to supply objects accurately. Therefore, it is difficult to ensure the accuracy in the weight of objects obtained.
According to the invention of the Japanese Laid-Open Patent Publication No. 2000-185719 (p. 4, FIG. 2), although the intermittent operation is performed likewise, two measuring portions and two supply portions are arranged so that an operation of supplying a large amount of objects is performed together with a supplying operation whereby an error in the weight is corrected. Thereby, objects having a predetermined weight can be obtained quickly with improved weight accuracy. According to this arrangement, however, the supplying and measuring operations are performed at different positions on the circular path, respectively. Therefore, it is difficult to achieve sufficiently high accuracy in supply amount. Furthermore, the weighing device tends to have large sizes.
According to the invention of the Japanese Laid-Open Patent Publication No. H9-002401 (pp. 2-3, FIG. 1), supplying and measuring of a large mount of objects are performed simultaneously, and thereafter, supplying (for the purpose of correcting error in weight) and measuring of a smaller amount of objects are performed simultaneously. Further, these supplying and measuring operations are continuously performed. Thereby, higher accuracy is ensured in weight of objects obtained, and the fast operation is achieved. However, this device requires many measuring devices and many supplying devices for achieving the fast operation. Further, the device must control many devices, and thus requires complicated control. Still furthermore, since the measuring device moves, accurate measuring is difficult as compared with the measuring in a stationary position.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for improved measuring devices that overcome the aforementioned problems of the conventional art. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.


A socket connector includes a housing extending along a longitudinal axis between opposed ends. The housing includes a mounting face configured to be received on the circuit board and a slot configured to receive the mating edge of the card edge module. A latch member is pivotably connected to the housing. The latch member is movable between an open position and a closed position. A biasing member is connected between the housing and the latch member. The biasing member biases the latch member toward the closed position.

The invention relates generally to socket connectors for retaining card edge modules and, more particularly, to a socket connector that limits movement of the card edge module within the socket.
Computers and servers may use numerous types of electronic modules, such as processor and memory modules (e.g. Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), or Extended Data Out Random Access Memory (EDO RAM), and the like). The memory modules are produced in a number of formats such as, for example, Single In-line Memory Modules (SIMM's), or the newer Dual In-line Memory Modules (DIMM's) and Fully Buffered DIMM's.
Typically, the modules are installed in one or more multi-pin sockets mounted on a system board or motherboard. Each memory module has a card edge that provides an interface generally between two rows of contacts in the socket. Conventionally, the card edge interface is a separable card edge interface. These card edge interfaces, however, are generally not high reliability interfaces. The modules are generally held in the socket by latches on the socket and by contact normal forces. These card edge interfaces may fail when subjected to shock and vibration. Under extreme vibration, the latches may be jarred open allowing the module to become dislodged. During vibration, the module may also experience sufficient motion within the socket to cause fretting of the gold on gold contact interfaces which increases resistance and may cause failures.
One approach for increasing reliability of the card edge interface is to directly attach the module via an inseparable interface. This is sometimes done when it is desirable that the end user not be able to remove processors or memory modules from the system so that problems that might arise from reconfiguration of the system do not occur. The provision of a high reliability interface that limits motion of the module within the socket remains difficult.

Socket connector having latch biasing member


A method for selective deposition of self-assembled monolayers to the surface of a substrate for use as a diffusion barrier layer in interconnect structures is provided comprising the steps of depositing a first self-assembled monolayer to said surface, depositing a second self-assembled monolayer to the non-covered parts of said surface and subsequently heating said substrate to remove the first self-assembled monolayer. The method of selective deposition of self-assembled monolayers is applied for the use as diffusion barrier layers in a (dual) damascene structure for integrated circuits.

Copper is the preferred metal for creating multilevel interconnect structures in ultra-large-scale-integrated circuits because of its high electrical conductivity and electromigration resistance. One of the major challenges in Cu metallization technology is the prevention of the rapid diffusion of Cu into adjoining layers of SiO2 and related low-dielectric-constant materials (e.g., fluorinated SiOx, SiOCH) during device operation. This is because Cu incorporation into the dielectric degrades the dielectric properties of the insulating layer, causing increased leakage currents, and leading to inferior device performance and failure.
The current industry standard is 10-30-nm-thick metallic diffusion barrier layers of Ti- or Ta-based compounds (such as Ta, TaN, TiSiN and TiN) or Cu-based alloys to alleviate this problem. While these approaches have been successful thus far, barriers with thicknesses below 5 nm will be needed at sub-100-nm feature sizes and in advanced future device architectures (e.g. three-dimensional integrated multiple-wafer devices) to fully realize the advantage of Cu interconnects. It is difficult to obtain such thin barriers with acceptable step coverage by conventional metal deposition methods (Plasma Vapor deposition (PVD) or Chemical Vapor Deposition (CVD)) without compromising the barrier-layer microstructure and/or their conformality in high-aspect-ratio features. Additionally thick diffusion barrier layers take up the volume meant for low-resistivity Cu, reducing the advantages of scaling (miniaturization).
Newly emerging methods such as atomic layer deposition (ALD) have the potential to obviate some of these concerns. However, to obtain conformal films with thicknesses below 5 nm of conventional barrier materials, it is not clear if they will be effective due to high defectivity. Hence, there is a great deal of interest in exploring alternative materials and processing methods.
Recently, Self-Assembled Monolayers (SAM) are reported to act as thin (generally <2 nm) Cu diffusion barrier layers (US 2002/0079487). With SAM layers comprising organo-silane molecules, Cu diffusion into the dielectric is inhibited and a good Cu adhesion at the Cu/SiO2 interface is achieved. The use of said SAM layer in integrated circuit structures such as dual damascene structures wherein electrical contact is required between the metal line of interest to metal lines above or below the situation is more complicated. Deposition of said SAM layer (comprising organo-silane molecules) to the already existing metal structure will lead to poor adhesion of Cu seed layers prior to further Cu deposition and poor electrical conductivity later on in the finalized dual damascene structure.

Method for selective deposition of a thin self-assembled monolayer


A zoom lens having four lens groups, the lens groups having refractive power, in order from the object side, of: fixed positive, variable negative, variable positive or negative, and fixed positive. The first lens group from the object side is composed of three lens subgroups, the middle subgroup of which is moved to perform focusing. The second lens group is moved to vary the amount of zoom, and the third lens group moves when the amount of zoom is varied in order to correct for movement of the image plane resulting when the second lens group is moved. Thus, the optical performance of the zoom lens is favorably maintained over the entire image plane. Further, by satisfying certain conditional equations a system that is compact and can focus objects at very near distances is obtained.

In the prior art, a focus method for a zoom lens is well known that moves the whole body of a first lens group having positive refractive power when there is a focal adjustment while moving another lens group. However, when the whole body of the first lens group is desired to be moved and focused on a very near object, the effective diameter of the first lens group invariably must be made larger in order to maintain a constant luminous flux at the perimeter of the image plane. This occurs because the first lens group is moved to the object side when focusing on a very near object. This becomes apparent in that the image becomes a wide angle image. Because the lens weight increases when the effective diameter of the first lens group becomes larger, this causes an inconvenience in the case of a zoom lens intended for use on a portable television camera.
As a technique for resolving this problem, the first lens group has been divided into three lens subgroups of negative, positive, and positive refractive power, respectively, in order from the object side. Methods that cause the intermediate subgroup of positive refractive power to move and focus are shown in, for example, Japanese Patent Publications 59-4686 and 6-242378.
Generally, a zoom lens of the inner focusing type moves the first lens group. As compared to a front focus zoom lens that performs the same focusing, the effective diameter of the first lens group becomes smaller than that of the corresponding front focus zoom lens, making it easy to miniaturize the entire body of the lens system when using a zoom lens of the inner focusing type.
On the other hand, a greater variety of photographing construction diagrams have recently been sought. Photographing of very near objects, which requires a wide angle change of the focal distance, has been desired. However, when a wide angle change is attempted, there is a tendency for the effective diameter of the first lens group to become larger.
Generally, when a zoom lens of the inner focusing type is employed, a miniaturization of the zoom lens becomes easy, as stated above. However, when a wide angle change is attempted, a problem develops in that it becomes difficult to obtain a high optical performance while attempting to miniaturize the zoom lens.


Two transmission devices connected to a link in which a failure occurs turn back a ring. Other transmission device changes a transmission ring of an NNI packet which is a UNI packet whose transmission source is its own transmission device and which had been transmitted through the link before the failure occurs to have a reverse direction. In addition, each transmission device, upon receiving an NNI packet whose transmission destination NNI address is one or any one of a plurality of NNI addresses applied to its own transmission device, outputs the packet to a self-owned tributary port irrespectively of whether it is sent through an inner ring or an outer ring.

1. Field of the Invention
The present invention relates to a technique for packet protection in a packet transfer ring.
2. Description of the Related Art
With an increase in data system traffic whose representative is IP, efficient transmission of data is demanded from conventional communication service providers (hereinafter referred to as carriers) which provide transmission service mainly for voice. Together with the demand, as highly reliable protection method as "SONET, GR-1230-Core, Issue 3 Dec. 1996 Bellcore" on which conventional transmission networks base is demanded also in a data transmission network. Among highly reliable protection methods in data transmission networks is Spatial Reuse Protocol (hereinafter referred to as SRP)(RFC 2982 IETF).
With reference to FIGS. 22 to 25, a protection method using the conventional SRP will be described.
FIG. 22 is a block diagram showing an example of a structure of a transmission device which executes protection using the SRP. A transmission device 100 includes link monitors 110 and 111, a failure information collection unit 120, Add/Drop 130 and 131, Wrap switches 140 and 141, frame conversion units 150 and 151, inverse frame conversion units 152 and 153, Trb-UNI switches (UNI tributary packet switches) 160 and 161 and a UNI forwarding table 170.
The link monitors 110 and 111 each monitor a failure condition of an input link 101-IN of an inner ring and an input link 102-IN of an outer ring and when detecting a failure, notify the failure information collection unit 120 of link failure information indicative of the detected failure.
When notified link failure information by the link monitors 110 and 111, the failure information collection unit 120 generates a ring network failure information notification packet containing the link failure information and transmits the packet to other transmission device through the Add/Drop 130 and 131, as well as switching an operation mode of the Wrap switch 140 or the Wrap switch 141 from a pass mode to a Wrap mode according to the input link having the failure. When the failure occurs in the input link 101-IN, switch the Wrap switch 141 to the Wrap mode and when the failure occurs in the input link 102-IN, switch the Wrap switch 140 to the Wrap mode.
When a ring network failure information notification packet sent from other transmission device indicates that a failure occurs in an output link of the inner ring or the outer ring directly connected to its own transmission device 100, the failure information collection unit 120 switches the operation mode of the Wrap switch 140 or the Wrap switch 141 from the pass mode to the Wrap mode according to the output link in which the failure occurs. When the failure occurs in an output link 101-OUT of the inner ring, switch the Wrap switch 140 to the Wrap mode and when the failure occurs in an output link 102-OUT of the outer ring, switch the Wrap switch 141 to the Wrap mode.
The Add/Drop 130 and 131 decipher a kind of an NNI packet (packet for use in a ring) applied from the link monitors 110 and 111, the Wrap switches 140 and 141, the Trb-UNI switches 160 and 161 or the failure information collection unit 120 and a transfer destination NNI address of the NNI packet and when the kind indicates a ring network failure information notification packet, drop the packet into the failure information collection unit 120, when the kind indicates a data packet which is an NNI packet to be terminated at its own transmission device, drop the packet into the inverse frame conversion units 152 and 153 and when the kind indicates other kind of NNI packet, pass the packet through the Wrap switches 140 and 141. Here, to the transmission device 100, two MAC addresses #A and #B are assigned and the Add/Drop 130 drops only an NNI packet whose transfer destination NNI address is #A into the inverse frame conversion unit 152, while the Add/Drop 131 drops only an NNI packet whose transfer destination NNI address is #B into the inverse frame conversion unit 153.
The Wrap switches 140 and 141 have their modes controlled by the failure information collection unit 120 and transfer NNI packets applied from the Add/Drop 130 and 131 to the output links 101-OUT and 102-OUT of the inner ring and the outer ring, respectively, at the time of the pass mode and transfer the same to the Add/Drop 131 and 130, respectively, at the time of the Wrap mode.
When a UNI packet (user packet sent from a network or a terminal connected to a tributary port) is sent through the Trb-UNI switch 160, the frame conversion units 150 and 151 derive a transmission destination NNI address based on its transmission destination UNI address, convert the packet into an NNI packet having the transmission destination NNI address and a predetermined transmission source NNI address and transfer the obtained packet to the Add/Drop 130 and 131. The frame conversion unit 150 applies #A as a transmission source NNI address of the NNI packet and the frame conversion unit 151 applies #B as a transmission source NNI address of the NNI packet.
The inverse frame conversion units 152 and 153 convert an NNI packet into a UNI packet and send the converted packet to a tributary port 103-OUT.
The Trb-UNI switches 160 and 161 transfer a UNI packet to a desired output port with reference to a transfer destination address of the UNI packet and the UNI forwarding table 170.
FIGS. 23A and 23B show two-fiber rings with transmission devices 100-1 to 100-6 connected in a ring through an inner ring 101 and an outer ring 102. Each of the transmission device 100-1 to 100-6 has the same structure as that of the transmission device 100 shown in FIG. 22. In addition, the inner ring 101 is composed of links 101-1 to 101-6 to transfer a packet counterclockwise and the outer ring 102 is composed of links 102-1 to 102-6 to transfer a packet clockwise.
With reference to FIGS. 23A and 23B, description will be made of an SRP protection method in a case where a failure occurs in the links 101-5 and 102-5 between the transmission devices 100-5 and 100-6. It is assumed that before the failure occurs, a UNI packet sent from a terminal 210 is converted into an NNI packet at the transmission device 100-1 and after being transferred to the transmission device 100-4 through the inner ring 101, again converted into a UNI packet and then transferred to the terminal 211 as indicated on a path 201 shown in FIG. 23A.
When detecting failures in the links 101-5 and 102-5, respectively, the link monitors 110 and 111 of the transmission devices 100-5 and 100-6 notify the failure information collection units 120 in their own devices of the failures.
Responsively, the failure information collection unit 120 of the transmission device 100-5 switches the Wrap switch 141 from the pass mode to the Wrap mode. The failure information collection unit 120 also generates a ring network failure information notification packet indicative of a failure occurring in the link 101-5 and sends the packet to the inner ring 101 through the Add/Drop 130.
In the same manner, the failure information collection unit 120 of the transmission device 100-6 switches the Wrap switch 140 from the pass mode to the Wrap mode. The failure information collection unit 120 also generates a ring network failure information notification packet indicative of a failure occurring in the link 102-5 and sends the packet to the outer ring 102 through the Add/Drop 131.
The failure information collection units 120 of other transmission devices than 100-5 and 100-6 refer to the ring network failure information notification packets notified through the inner ring 101 and the outer ring 102 to transfer the packets as they are to the subsequent transmission devices.
Upon receiving the ring failure information notification packet indicating that a failure occurs in the link 102-5 which is sent from the transmission device 100-6, the failure information collection unit 120 in the transmission device 100-5 switches the Wrap switch 141 to the Wrap mode when the switch is at the pass mode. Since the switch is already at the Wrap mode in this case, no mode switching processing is conducted. Squelching of the ring network failure information notification packet is also conducted.
Similarly, upon receiving the ring failure information notification packet indicating that a failure occurs in the link 101-5 which is sent from the transmission device 100-5, the failure information collection unit 120 in the transmission device 100-6 switches the Wrap switch 140 to the Wrap mode when the switch is at the pass mode. Since the switch is already at the Wrap mode in this case, no mode switching processing is conducted. Squelching of the ring network failure information notification packet is also conducted.
As a result, the NNI packet sent from the transmission device 100-1 is transferred from the transmission device 100-1 to the transmission device 100-6 by using the inner ring 101, then turned back at the transmission device 100-6 as indicated in the path 202 shown in FIG. 23B, passed in the outer ring 102 through the transmission devices 100-1 to 100-4, again wrapped by the transmission device 100-5 and transferred to the transmission device 100-4 by using the inner ring 101. The NNI packet applied through the inner ring 101 to the transmission device 100-4 is converted into a UNI packet and then transferred to the desired terminal 211.
By thus using the SRP protection method, even when a fiber failure occurs, packets can be transferred to a desired transmission device by detouring around a failure section.
Since in SRP protection, a packet is wrapped by transmission devices at opposite ends sandwiching a failure point, at a section between one wrap point and a transmission source transmission device (i.e. a section between the transmission device 100-6 and the transmission device 100-1 in FIG. 23B) and a section between the other wrap point and a reception side transmission device (i.e. a section between the transmission device 100-4 and the transmission device 100-5 in FIG. 23B), twice a band is required for transferring a certain NNI packet to result in deteriorating band efficiency.
In the SRP protection method, when the transmission device 100-4 has a transmission failure as shown in FIG. 24A or when a multiple failure occurs at the links 101-3, 101-4, 102-3 and 102-4 as shown in FIG. 24B, an NNI packet transferred from the transmission device 100-1 to the transmission device 100-4 is wrapped at the transmission devices 100-3 and 100-5 at the opposite ends sandwiching the failure occurring position, so that it can not reach the transmission device 100-4 and makes a round of the network to be terminated at the input link 101-1 of the transmission source transmission device 100-1. When the NNI packet is thus unable to reach the transfer destination transmission device (when the NNI packet becomes an unreachable packet), the NNI packet wastefully uses a network band.
Also when the network is arranged such that a terminal 211 is connected to an Ethernet switch 410, and the Ethernet switch 410 and the transmission devices 100-4 and 100-3 are connected (dual homing) through an actual use port 401 and a spare port 402, respectively, as illustrated in FIG. 25, since a transmission destination address of an NNI packet to be transmitted to the terminal 211 is a MAC address applied to the transmission device 100-4, the transmission device 100-3 is unable to recognize the NNI packet as a self-addressed NNI packet and is therefore unable to process the NNI packet. As a result, when the transmission device 100-4 connected to the actual use port 401 has a transmission device failure, although a transfer path exists from the terminal 210 to the terminal 211 using the spare port 402, the packet becomes an unreachable NNI packet to result in deteriorating a failure recovery rate.

Packet protection method and transmission device in ring network, and program therefor


Contrast compensation for a liquid crystal display projection system including a light source, a first polarizer, a liquid crystal display panel, and a second polarizer is provided using a tilted compensating plate. The compensating plate includes a first birefringent element having an optic axis oriented at a first angle to the plate normal, where the first angle is greater than zero degrees (e.g., an A-plate or O-plate), and a second birefringent element having an optic axis oriented at a second angle to the plate normal, where the second angle is substantially equal to zero degrees (e.g., a C-plate). The compensating plate is tilted relative to a plane of the liquid crystal display panel. The tilted compensating plate has been shown to provide improved contrast compensation for twisted nematic liquid crystal displays.

Several micro-display projection (MDP) technologies are currently available in the market place targeting 40″ to 70″ TV screen diagonal sizes. For example, digital light processor (DLP) based projectors incorporate binary intensity modulation at the pixel level and typically rely on a single panel to temporally multiplex (in a time-sequential manner) red, green and blue (RGB) color channel information of an image. On the other hand, both transmissive liquid crystal display (xLCD) and liquid crystal on silicon (LCOS) projectors utilize the electro-optic effect of a switchable LC layer to provide pixel-level modulation. Since the fabrication of polarization-based xLCD and LCoS MDP panels are typically lower cost and higher yield than the fabrication of millions of hinged micro-mirrors on a DLP backplane, both XLCD and LCoS optical engines are often configured with a three-panel architecture, where the RGB color channels are simultaneously displayed and converged before being projected to a screen. While LCoS panels may be based on either twisted-nematic (TN) or vertical-aligned nematic (VAN) liquid crystal (LC) layers, VAN-mode LC technology is generally more prevalent in commercial LCoS based projectors. Although the industry is transitioning to VAN-mode LC in xLCD panels, the prevalent LC mode of operation in xLCD panels is TN.
Optical engines using three TN xLCD panels have been promoted under the "3LCD" industry forum. A sub-system of the 3LCD architecture is schematically illustrated in FIG. 1, which shows an image modulation segment of a typical 3-panel light engine. The optical sub-system 100 includes input pre-polarizers 101a, 101b, 101c, retarder compensators 103a, 103b, 103c, xLCD panels 104a, 104b, 104c, and exit clean-up polarizers 105a, 105b, 105c. The center element of the optical sub-system 100 is an X-cube 110, where three separate light beams 120a, 120b, 120c are aggregated and emitted as a converged light beam 130, which is projected onto a screen (not shown). The three separate light beams provide the RGB channel data. In general, the green channel often corresponds to the first light beam 120a so that it is directed at the transmitted port of the X-cube. For each color channel, the xLCD panel 104a/104b/104c is positioned between a set of crossed polarizers (e.g., between an input pre-polarizer 101a/101b/101c and an exit clean-up polarizer 105a/105b/105c, respectively). In the schematic shown, the input pre-polarizers 101a, 101b, 101c have their transmission axes aligned horizontal (parallel to plane of drawing), while the exit clean-up polarizers 105a, 105b, 105c have their transmission axes aligned vertical. The arm of the optical sub-system 100 corresponding to the green or 'a' channel typically includes a half-waveplate (HWP) 106 to convert the modulated vertically polarized light to horizontally polarized light so that it appears as P-polarized light with respect to the X-cube hypotenuse and is transmitted through the X-cube. Alternatively, if the xLCD panel 104a rotates the incoming vertical polarization to horizontal polarization in the on-state, the HWP 106 may be positioned in another arm of the optical sub-system 100.
The retarder compensators 103a, 103b, 103c are compensating elements used to improve the contrast level of the xLCD MDP system, which is otherwise reduced when the panel is viewed obliquely. For example, it is well known that the refractive index anisotropy in TN-mode LCD panels degrades the viewing angle characteristic of the xLCD MDP system. In the absence of retarder compensators 103a, 103b, 103c, the xLCD native panel contrast is typically a few hundred to one. With the retarder compensators 103a, 103b, 103c, the compensated xLCD panel contrast is substantially higher.
Conventionally, the retarder compensators 103a, 103b, 103c have been fabricated out of stretched organic foil, such as Fuji's Wide View (WV) film, which consists of a discotic layer on a triacetate cellulose (TAC) substrate. The use of stretched organic foils as retarder compensators in MDP systems is likely rooted to the use of the same in the direct view LCD industry, where large screen areas (e.g., 2.5 inches or larger) need to be compensated for contrast and/or to improve viewing angle. However, in MDP applications, the increased light flux may result in premature degradation of these organic retarder compensators. In addition, the uniformity and surface quality specifications required for small screen areas (e.g., 2.5 inches or smaller) is not always met with these organic retarder compensators. Accordingly, a more reliable retarder technology as a contrast enhancement solution is desired.
One such solution was proposed in US Pat. Appl. No. 20060268207, the entire contents of which are hereby incorporated by reference. In this reference, Tan et al disclose using a tilted C-plate retarder as a contrast enhancer in both transmissive (e.g., XLCD) and reflective (e.g., LCoS) MDP systems. The tilted C-plate retarder is fabricated with vacuum coated dielectric layers, and thus exhibits high reliability and high retardance uniformity. Notably, using vacuum coated dielectric layers to form a C-plate element is also described in U.S. Pat. No. 7,170,574, with is also hereby incorporated by reference.
Referring to FIG. 2, the optics of one arm of the prior art xLCD MDP system using a tilted C-plate retarder compensator is shown. In this sub-system 200, a cone of light output from a prior stage light pipe (or other homogenizer such as Fly's Eye Array, not shown), is linearly polarized by the pre-polarizer 201. The transmission axis 220 of the pre-polarizer 201, which can be aligned arbitrarily over the entire circle, is typically aligned at ±45′, 0° or 90° with respect to the x-axis (shown aligned at 0°). Light transmitted through the pre-polarizer 201 is passed through the retarder compensator 203 and the xLCD imager 204, the latter of which typically has its slow axis 230 aligned at ±45° azimuthal offset 235 versus the pre-polarizer transmission axis 220. Light passed through the xLCD imager 204 is then transmitted to a post-analyzer 205, which typically has its transmission axis 221 aligned perpendicular to the pre-polarizer axis 220.
While this optical system 200 is shown to include only one retarder compensator 203, which is disposed between the pre-polarizer 201 and the xLCD imager 204, alternate embodiments provide one or more stages of retarder compensator that may be inserted anywhere between the pre-polarizer 201 and the post-analyzer 205. For example, in another embodiment the retarder compensator 203 is disposed between the xLCD imager 204 and the post-analyzer 205. In yet another embodiment a first retarder compensator 203 is provided between the pre-polarizer 201 and the xLCD imager 204, while a second retarder compensator (not shown) is provided between the xLCD imager 204 and the post-analyzer 205.
In each case, the retarder compensator 203 includes a C-plate retarder mounted at an angle to the x-y plane. More specifically, the C-plate retarder 203 is tilted such that it is aligned at a polar angle tilt 211 with respect to the system x-axis and at a polar angle tilt 212 with respect to the system y-axis. This two-dimensional tilt sets the axis of rotation 240 at azimuthal angle 245 with respect to the x-axis. The axis of rotation 240 is parallel to the plane of the xLCD imager 204 and parallel to the system x-y-plane. The z-axis is the propagation axis of the principal ray, which is also referred to as the transmission axis.
The assignment of fast/slow axes of the tilted C-plate retarder 203 relative to the axis of rotation 240 is dependent on the sign of C-plate retardance. For a −C-plate, the slow axis (SA) lies on the tilted surface at azimuthal angle 245, which is nominally perpendicular to the imager SA 235. For a +C-plate, the fast axis (FA) lies on the tilted surface at azimuthal angle 245, which is nominally parallel to the imager SA 235. The terms "nominally perpendicular" and "nominally parallel" are used to reflect the common practice in retardation compensation of rotating or clocking the retarder compensator SA from perpendicular alignment relative to the imager SA 235 by small value.
Advantageously, the tilt of the −C-plate introduces a net retardance, as seen by the principal ray, having a magnitude that provides compensation for the residual in-plane retardance of the xLCD panel in the dark state. In addition, the form-birefringent coating on the tilted C-plate provides a retardance profile (with incident angle) that provides compensation for the residual out-of-plane retardance of the xLCD panel in the dark state. In other words, a single −C-plate-only component is used to provide both on-axis and off-axis retardance compensation for the xLCD MDP system, thus providing a high contrast image with minimal components.
While the tilted C-plate-only retarder compensator has shown potential for use in both LCoS and xLCD MDP systems, where its durability in high light flux environments and highly uniform retardance characteristics are advantageous, it is limited in that it does not allow for the decoupling of the fast/slow axes from the geometric tilt-plane. In fact, the tilted C-plate retarder is a geometric retarder, wherein the FA and SA are set by the plane of incidence (e.g., as discussed above, the SA plane in the tilted −C-plate is the tilt plane).
Since the SA and FA are set by the plane of incidence, it is more challenging to fabricate a geometric retarder having a linear retardance profile that matches the linear retardance requirements of a given panel (e.g., which may exhibit a characteristic asymmetry in its conoscopic linear retardance profile along one of the slow or fast axes).
It would be advantageous to provide a retarder compensator that provides similar durability and/or retardance uniformity characteristics provided by the tilted C-plate retarder compensator, wherein the FA and SA are not determined by the plane of incidence.

Twisted nematic xLCD contrast compensation with tilted-plate retarders