A photoelectric conversion apparatus includes a semiconductor substrate having a photoelectric conversion portion. An insulator is provided on the semiconductor substrate. The insulator has a hole corresponding to the photoelectric conversion portion. A waveguide member is provided in the hole. An in-layer lens is provided on a side of the waveguide member farther from the semiconductor substrate. A first intermediate member is provided between the waveguide member and the in-layer lens. The first intermediate member has a lower refractive index than the in-layer lens.

1. Field of the Invention
The present invention relates to a photoelectric conversion apparatus.
2. Description of the Related Art
Recently proposed photoelectric conversion apparatuses include optical waveguides and in-layer lenses so as to increase the quantity of light to be incident on photoelectric conversion portions.
FIG. 8 of Japanese Patent Laid-Open No. 2007-201091 illustrates the following solid-state image pickup element as a photoelectric conversion apparatus. A planarizing layer having a through hole is provided on a semiconductor substrate having a photoelectric conversion portion. A first highly refractive material is provided over the planarizing layer such that the through hole is filled with the first highly refractive material, which forms an optical waveguide. An inner lens, as an in-layer lens, made of a second highly refractive material is provided on the first highly refractive material. A top microlens is provided on the inner lens.
FIG. 1 of Japanese Patent Laid-Open No. 2008-192951 illustrates the following solid-state image pickup apparatus as a photoelectric conversion apparatus. A plurality of interlayer dielectric films are stacked on a semiconductor substrate having photoelectric conversion elements. Openings are provided in portions of the stack of interlayer dielectric films in such a manner as to overlap the respective photoelectric conversion elements. Optical waveguides are embedded in the respective openings. In-layer lenses are provided on the respective optical waveguides. Top lenses are provided on the respective in-layer lenses.
In a photoelectric conversion apparatus to which the solid-state image pickup element disclosed by Japanese Patent Laid-Open No. 2007-201091 is applied, a film made of a highly refractive material that is the same as a material forming the in-layer lens is interposed between the in-layer lens and the optical waveguide. Therefore, some of light transmitted through the in-layer lens may not enter the optical waveguide. In the photoelectric conversion apparatus disclosed by Japanese Patent Laid-Open No. 2008-192951, each of the optical waveguides is in contact with a corresponding one of the in-layer lenses. In such a configuration, some of light incident on a peripheral region of the in-layer lens may not enter the optical waveguide.
The above situations are noticeable with light rays that are obliquely incident on the in-layer lens with respect to the optical axis. Therefore, in such a photoelectric conversion apparatus, there may be a difference in sensitivity between a group of pixels around the center of the image pickup area and a group of pixels near ends of the image pickup area. This is because pixels near ends of the image pickup area tend to receive more oblique light rays than pixels around the center of the image pickup area. This phenomenon becomes more noticeable as the image pickup area of the photoelectric conversion apparatus becomes larger.


An adjustable carpentry trim gage includes a scribing block adjustably attached to a guide block. The guide block includes a guide surface, adapted to be placed against a jamb. The scribing block includes a scribing surface along which a scribing instrument, such as a pencil or an awl, can be drawn to mark guidelines on the jamb, to facilitate installation of a casing on the jamb. The position of the guide block with respect to the scribing block is adjustable to allow the position of the scribing surface on the scribing block, with respect to the guide surface on the guide block, to be set in such a manner that the scribing surface will be placed to indicate a desired reveal on the jamb, when the guide surface is bearing against the jamb. The scribing surface extends beyond the maximum reveal setting of the gage, in a direction parallel to the face of the jamb against which the guide surface is bearing, to facilitate making intersecting guidelines indicating corners of the casing.

As shown in FIG. 1, windows, doors, medicine cabinets, and the like, typically include an outer frame, commonly called a jamb 100, which is installed into a rough opening 102 in a wall 103, by installing a pair of wedge shaped shims 104 between the outside of the jamb 100 and the inner surface of the rough opening 102, and driving one or more finishing nails 106 through the jamb 100 and shims 104, and into framing of the wall 103 that defines the rough opening 102. This process leaves an unsightly gap 108 between the jamb 100 and the rough opening 102 that is typically covered, as shown in FIGS. 2 and 3, with several pieces of carpentry trim, that are known individually and collectively as a window or door casing 110.
Although having to deal with covering the gap 108 is bothersome, the gap 108 is necessitated by the fact that rough openings 102 are generally not square and plumb or closely dimensioned enough to eliminate the gap 108. Door and window jambs 100 must be installed substantially plumb and square, in order for the door or window to operate properly. Even if the rough openings 102 could be made square and plumb, there are also small variations in width and height of the outer periphery of the jambs 100 that would make it necessary to frame the rough opening 102 to much tighter dimensions than can practically be achieved.
The inner periphery of the jambs 100 may also vary slightly over the length and width of the jamb 100, due to small amounts of warpage, or uneven support between the shims 104. There are also unavoidable small dimensional differences in the width and height of the inside dimensions of the jambs 100, from one door or window to the next, even in doors and windows that are of the same nominal width and height.
In order to accommodate the above described variations and dimensional differences, it is also common practice to position the inner edges 111, 112 of the trim pieces 113, 114 forming the casing 110 slightly back from the inner surface 115 of the jamb 100, as shown in FIGS. 2 and 3, to form space known as a reveal 116 that allows a small strip of the face 118 of the jamb 100 to remain exposed, inside of the casing 110, in the finished installation. The reveal 116 allows the position of the casing 110 to be shifted slightly, with respect to the inner surface 115 of the jamb 100, and the opening 102, to compensate for the variations and dimensional differences described above, in a manner that can be readily accomplished by a carpenter installing the casing 100, and in a way that is essentially undetectable to the eye of a casual observer of the finished installation. The reveal 116 also provides an aesthetically pleasing architectural enhancement of the appearance of the installed jamb 100 and casing 110.
In order to cut the trim pieces forming the casing 110 so that they fit together properly and are positioned at a reveal 116 selected to cover the gap 108, it is desirable to have an adjustable trim marking gage for marking guidelines 120, indicating the selected reveal 116, at several points along the face 118 of the jamb 110, as shown in FIG. 4. It is especially desirable to have an adjustable trim marking gage that can conveniently be used for marking intersecting guidelines 120, adjacent to corners 124 of the jamb 100, to create a corner mark 122 precisely indicating where the inside corner 126 of the casing 110 should be located in the finished installation. Once these corner marks 122 are marked on the face 118 of the jamb 100, the dimension between them, and the distance from the corner marks 122 to the floor for a door casing, can be accurately and conveniently measured, and used to cut the parts 113, 114 of the casing 110 so that they will fit together properly in the finished installation.
In the past, carpenters sometimes utilized specially cut blocks of wood, for marking the guidelines 120 and corner marks 122 on the face 118 of the jamb 100. Because these blocks were not adjustable to accommodate the variations and differences described above, it was necessary to continually re-cut the blocks, or cut a separate block for each window or door. This is obviously a very time consuming and wasteful process. It is also necessary, in some cases, to use a different reveal 116 for horizontal trim pieces 113, than is used for vertical trim pieces 114, thereby making the use of specially cut wooden blocks even more difficult.
There have been, in the past, attempts made at providing adjustable carpentry trim marking gages that could be used for marking guidelines 120 and corner marks 122 on the face 118 of a jamb 100. U.S. Pat. Nos. 6,513,258; 5,737,844; and 5,123,172 show several prior approaches to providing an adjustable carpentry trim gage. None of these prior adjustable gages are entirely satisfactory for the desired purposes, however.
What is needed is an improved adjustable carpentry trim marking gage and method.


A molding system having a melt pathway configured to convey a molding material. The molding system includes a viscous-drag sensor having: (i) a pathway blockage, and (ii) an actuator. The viscous-drag sensor is interactable with the molding material. The pathway blockage is movable along the melt pathway. The pathway blockage is movable along a first direction to further open the melt pathway. The pathway blockage is movable along a second direction to further close the melt pathway. The actuator is coupled with the pathway blockage. The actuator biases the pathway blockage to vary the melt pathway while the molding material drags along and moves the pathway blockage. Responsive to the pathway blockage sensing viscous-drag force, the pathway blocks acts to: (i) further open the melt pathway if a viscosity of the molding material is high, and (ii) further close the melt pathway if the viscosity of the molding material is low.

Examples of known molding systems are the: (i) HyPET™ Molding System, (ii) Quadloc™ Molding System, (iii) Hylectric™ Molding System, and (iv) HyMet™ Molding System, all manufactured by Husky Injection Molding Systems Limited (Location: Bolton, Ontario, Canada; WWW-URL: www.husky.ca).
U.S. Pat. No. 3,863,001 (Inventor: Thumudo; Published: 1975 Jan. 28) discloses an improvement in a method of making a generally flat circular transfer preform from a polymeric extrudate. The method includes steps (a), (b) and (c). Step (a) includes an improved breaker plate that has oppositely disposed surfaces, and each of the surfaces generally defines a portion of a sphere, a center of curvature and a radius of curvature. The centers of curvature are both located on the upstream side of the breaker plate. The plate defines a plurality of orifices that extend through the plate and cover a major portion of the surface area of the plate. The orifices nearer the center of the plate are longer than those nearer the periphery, to compensate for the frictional drag exerted on the extrudate by the surface of the barrel. Step (b) includes forcing the extrudate through the improved breaker plate thereby forming a plurality of individual extrusions. Step (c) includes permitting the individual extrusions to nest together.
U.S. Pat. No. 3,969,055 (Inventor: Buckethal; Published: 1976 Jul. 13) discloses a system and method for controlling the injection of material through two or more gates into the cavity of injection-molding apparatus. In this system, a sensor develops an indication of unbalanced flow conditions produced by the injection of the material into the cavity of the mold. A regulator also forms part of the system and serves to adjust the relative amounts of material passing through the gates. The method includes sensing unbalanced flow conditions produced by the material injected into the cavity and adjusting the relative amounts of materials injected into the cavity through the various gates.
U.S. Pat. No. 4,965,028 (Inventor: Maus et al; Published: 1990 Oct. 23) discloses a method for improving a thermoplastic's melt quality and increasing melt temperature entering a gate of each cavity of a multicavity mold and thereby improving molded part quality. The improvement is achieved by steps (a), (b), (c) and (d). Step (a) includes injecting a plasticated melt under pressure through a nozzle seated in a sprue bushing into a multicavity moldset, melt-delivery system. The delivery system includes melt passageways maintained continuously in fluid communication between the sprue bushing on an upstream end. Runner bushings feed into each mold cavity on a downstream end. The melt contained in the delivery system is intermittently pressurized and depressurized with each injection cycle. The melt always retains sufficient fluidity to flow as required when next pressurized. Step (b) includes displacing the melt contained in the delivery system downstream toward the mold cavities. Upon each cycle's melt pressurization, the melt must pass through en route melt conditioning elements located upstream of each gate and downstream of each melt passageway. Each conditioning element consists of a male device member. The male device is generally torpedo shaped, and housed concentrically within a generally cylindrically shaped female bushing member. The conditioning element also includes a precisely dimensioned annular clearance space between the male and female members. Each conditioning element defines at least one inlet melt channel which is substantially blocked at its downstream end and at least one outlet melt channel which is substantially blocked at its upstream end. The inlet and outlet melt channels are maintained in fluid communication through the precisely dimensioned clearance space, such that melt transferring between the inlet and outlet melt channels must pass over the constrictive land. Furthermore, the melt transferring therebetween must undergo substantial angular change in flow direction as the inlet and outlet melt channels are not coaxially aligned. Each melt conditioning element feeds the melt directly into the gate. Step (c) includes shearing the melt as it flows during the intermittent pressurization of each cycle, thereby increasing the melt temperature and mixing the melt by angular flow direction change as the melt is transferred through the melt conditioning elements. Step (d) includes heating at least one of the male and female members of each melt conditioning element to a temperature greater than a temperature of the melt measured upstream of the melt conditioning elements. Forcing intimate contact between the melt and the heated members thereby increasing heat transfer between the melt and the heated members and increasing melt temperature downstream of the melt conditioning elements. This results in the melt entering each mold cavity to have substantially greater homogeneity, fluidity, and heat content with very minimally increased heat history.
U.S. Pat. No. 5,069,403 (Inventors: Marentic and Morris; Published: 1991 Dec. 03) discloses a method for providing a drag reduction article. The method includes three steps: (a), (b) and (c). Step (a) includes applying a layer of a first radiation curable composition to a carrier. Step (b) includes forming a first patterned surface on the radiation curable composition. Step (c) includes curing the first radiation curable composition by exposure to activating radiation to provide a first cured patterned surface that is capable of reducing drag resistance (that is, when a fluid flows thereacross).
U.S. Pat. No. 5,192,556 (Inventor: Schmidt; Published: 1993 Mar. 09) discloses a plastic molding apparatus for delivering a melt stream of moldable plastic material under pressure through a flow passageway and into a mold cavity. The apparatus includes a distributing plate having a distribution channel for conveying a plastic melt. A nozzle has a nozzle channel that communicates with the distribution channel. A mold cavity communicates with the nozzle channel. The mold cavity includes a connecting channel that connects the distribution channel with the nozzle channel. The connecting channel includes a flow entry portion, a reservoir portion and a flow restriction portion. The melt flows from the distribution channel to the flow entry portion, to the reservoir portion, to the flow restriction portion, and to the nozzle channel. The flow entry portion comprises a varying height channel that distributes the melt substantially equally. The reservoir portion has a larger capacity than the flow restriction portion so that the flow restriction portion holds back the melt flow from the reservoir portion. The connecting channel substantially equalizes flow pressure and flow velocity of the plastic melt to the nozzle channel.
U.S. Pat. No. 5,421,715 (Inventor: Hofstetter et al; Published: 1995 Jun. 06) discloses an apparatus for the simultaneous production of preforms, consisting of polyethylene terephthalate (PET) fed and distributed to a plurality of cavities. In order to reduce the occurrence of acetaldehyde formation in a cavity, for example, a heated distributor block used in the production of preforms of the PET material, the material flowing through a channel is subjected to additional turbulence. To this end, an element, preferably of metal, is installed in the channels, such element being provided with sets of radial spokes which are azimuthally offset in relation to each other in the axial direction. Besides inducing turbulence, such spokes act as homogenizing elements serving to diffuse heat over the cross section of the flowing process material.
U.S. Pat. No. 5,527,499 (Inventor: Miley; Published: 1996 Jun. 18) discloses an extrusion apparatus for producing a composite profile strip. The apparatus includes an extrusion head that has flow channels extending to an extrusion die. At least two extruders feed respective components at respective different pressures into the flow channels for passage to the extrusion die. The extrusion die has a common die outlet from which the components are discharged to form the composite profile strip. Respective flow restriction devices are disposed in the flow channels between the extruders and the extrusion die. The flow restriction devices are operative to decrease a difference in pressure between the components at the extrusion die to about 250 psi (pounds-per-square inch) or less prior to the components being brought together.
U.S. Pat. No. 6,343,922 (Inventors: Kazmer and Moss; Published: 2002 Feb. 05) discloses an injection molding apparatus. The apparatus including four components: (a), (b), (c) and (d). Component (a) is a manifold that has an inlet for receiving material injected from an injection molding machine. Component (b) is a plurality of injection nozzles coupled to the manifold for distributing the material to a corresponding plurality of gates to one or more mold cavities. Component (c) is a plurality of sensors respectively coupled to each of the plurality of nozzles, each sensor to sense a condition related to the rate of material flow at a location between the inlet and the plurality of gates. The last component (d) a controller to individually control respective rates at which material flows out of each of the plurality of injection molding nozzles and into the one or more cavities based on signals the controller receives from the plurality of sensors.
U.S. Pat. No. 5,683,731 (Inventor: Deardurff et al; Published: 1997 Nov. 04) discloses a redistributing device for use with melt flow exhibiting boundary layer and centralized flow. The device includes: (i) a body including a melt flow inlet end and a plurality of melt-flow outlets, said body engaging a melt flow channel, (ii) first means in said body for distributing at least said boundary layer among said plurality of melt flow outlets, (iii) second means in said body for distributing at least said centralized flow among said plurality of melt flow outlets, wherein said body has a central opening therein defining a central flow channel in fluid communication with said outlets comprising said second means for distributing, and said first means for distributing comprises inlets leading to a plurality of diverters positioned on said body and adjacent said opening, said diverters extending from said inlet end and into fluid communication with said plurality of melt-flow outlets, andwherein the material flowing in the central channel meets the material flowing in the diverters and emerges at the outlets.
U.S. Pat. No. 5,688,462 (Inventor: Salamon et al; Published: 1997 Nov. 18) discloses, in an injection molding process for making thermoplastic articles, an in-runner static mixer that is positioned near the gate to a mold cavity to mix molten thermoplastic such that said thermoplastic exiting the in-runner static mixer is more homogeneous with respect to temperature than that entering the in-runner static mixer. Passing the more homogeneously mixed molten thermoplastic through the gate to the mold cavity and allowing said cavity to fill and thermoplastic to cool, will result in an article aesthetically superior to one made by a process where no in-runner static mixing device is employed.
U.S. patent application Ser. No. 2002/0,149,135 (Inventor: Choi et al; Published: 2002 Oct. 17) discloses a multiple cavity injection molding system. The system includes a feed source that provides flowable polymeric material at conditions suitable for producing molded products therefrom. Mold cavities are adapted to receive flowable polymeric material from the feed source and produce molded products. A primary sprue extends from the feed source. A runner system extends between and providing fluid communication between the primary sprue and the plurality of mold cavities. The runner system has a feed inlet in communication with the primary sprue and a plurality of discharge ports in communication with the mold cavities. The runner system has a symmetrical configuration with respect to the primary sprue. The runner system includes at least two turbulence-inducing components. The turbulence components are selected from the group consisting of turbulence-inducing runners, turbulence-inducing steps, and turbulence-inducing angles. Upon performing an injection molding operation, the shear rate of polymeric material exiting the runner system is at least 50% of the shear rate of the polymeric material entering the runner system at the feed inlet.
U.S. Pat. No. 6,382,528 (Inventor: Bouti; Published: 2002 May 07) discloses, in an injection molding machine, a mixer that reduces the flow imbalances inherent in the melt as the flow branches within a manifold or other part of the injection machine. The mixer increase melt homogeneity by gradually mixing and changing the melt flow from all helical flow to all annular flow. The mixer provides an improved means for reducing flow imbalances that results in the elimination of weld lines and other part non-uniformities.
U.S. Pat. No. 6,544,028 (Inventor Wright et al; Published: 2003 Apr. 08) discloses a mixer method and apparatus for use generally in injection molding machines. The apparatus and method is generally comprised of a mixer insert that retains a mixing element that is sealingly inserted in the injection molding machine, for example a hot runner manifold. The mixing element reduces the melt imbalances in a flowing melt stream for the formation of improved molded parts.
U.S. Pat. No. 6,572,361 (Inventor: Gould et al; Published: 2003 Jun. 03) discloses a hot runner subsystem for an injection molding machine. The hot runner subsystem includes (i) a heated manifold having at least one primary melt channel disposed therein, (ii) an adapter plate rigidly affixed to said manifold, said adapter plate having at least one first melt channel communicating with said at least one primary melt channel, and (iii) a mixer having an inlet and an exit, said inlet communicating with said first melt channel, and said exit communicating with a secondary melt channel.
U.S. Pat. No. 6,575,729 (Inventor: Godwin et al; Published: 2003 Jun. 10) discloses a heater for an injection molding runner nozzle. The heater includes a cylindrical, heat-conducting band substrate adapted to be placed over an outer surface of the nozzle. A first dielectric layer directly is deposited on an outer cylindrical surface of the band. A conductive-ink resistive heating element is directly deposited on the first dielectric layer. The heating element is formed in a pattern to apply heat through the band to the nozzle. The heating element has first and second ends. Each end has an electrical terminal. A second dielectric layer is directly deposited over the heating element, but not over the terminals.
U.S. Pat. No. 6,923,638 (Inventor: Chen; Published: 2005 Aug. 02) discloses a hot melt distribution manifold. The manifold includes a body and a main runner. The main runner is located in the body. The body has an inlet for receiving hot melt from a source of supply. A plurality of branches located in the body has intersections with the main runner at spaced locations along its length so that at least certain intersections are farther away from the inlet than others. A plurality of nozzle assemblies is located on the body and the nozzles communicate with the branches. Selectively-adjustable restrictor devices are associated with a plurality of the branches for adjustably constricting the space available for melt flow. The restrictor devices are located upstream from the corresponding nozzle assembly in spaced relation. Each of the restrictor devices are devoid of structure projecting from the restrictor device into the corresponding nozzle assembly.
U.S. patent application Ser. No. 2004/0130062 (Inventor: Sicilia; Published: 2004 Jul. 08) discloses a mixing device for use with a manifold in an injection molding apparatus. The mixing device includes a body having a melt channel therethrough. The melt channel has a plurality of increasing sections which have an increasing cross-sectional area in a downstream direction. A plurality of decreasing sections have a decreasing cross-sectional area in a downstream direction, and the increasing and decreasing sections alternating with each other.
U.S. patent application Ser. No. 2004/0256768A1 (Inventor: Olaru; Published: 2004 Dec. 23) discloses a stack injection molding apparatus that includes a melt homogenizing element provided between a first transfer nozzle, which is coupled to a melt source, and a second transfer nozzle, which is coupled to a manifold. The melt homogenizing element is used for redistributing a melt stream in order to provide a homogenized melt stream having a generally uniform temperature and viscosity profile or sectional distribution.
Known hot-runner balancing techniques appear to include geometric and/or thermal balancing of molding material channels leading into a mold cavity of a mold. These techniques have problems associate with them. Geometric balancing is used to maintain equal pressures across all drops of the hot runner. Flow control may be achieved in two ways by: (i) making the molding material travel a longer distance before it reaches the nozzle tip, or (ii) by opening a restriction near the nozzle tip (which would increase the flow out of the nozzle for the same inlet pressure).


A telescopic grandstand is provided including a central support structure and two sets of interconnected telescopic grandstand seating tiers. One set of tiers is located adjacent one side of the support for telescopic movement between a closed position adjacent the vertical upright portion of the support and an open use position wherein the tiers of the set form a stepped configuration which extends outwardly from the adjacent side of the support and downwardly from the top of the vertical portion of the support. The second set of telescoping seating tiers is similarly located adjacent the other side of the vertical portion of the support. The entire unit is movable in directions normal to the sides of the vertical portion of the support, and means are provided for rotating the unit about a vertical axis. A method for using the grandstand also is provided such that the seating configuration of the open central area of an arena or the like may be readily, easily, inexpensively and safely converted among various desired configurations.

1. Field of Invention
The present invention relates generally to grandstand seating systems. More particularly, the invention relates to a grandstand seating system suitable for use with exhibition areas of different sizes and shapes.
2. Summary of the Prior Art
The majority of the grandstand seating configuration of an arena-like facility is substantially fixed. Typically, such seating is arranged in tiered, permanent rows built on one or more upwardly sloping reinforced concrete levels surrounding a central open area. The central open area is usually quite large. For example, it is common for the open central area of an arena to be large enough to accommodate a three ring circus or a political convention or a trade show. It will be understood, however, that when the facility is used for the presentation of a basketball game; an ice hockey game; an arena football, lacrosse, or soccer game; an ice show; or any other similar exhibition intended to draw numerous spectators, the floor space utilized by the playing or exhibition surface may be substantially smaller than the open central area of the arena. In order to maximize the number of possible spectators (and thus the revenue derivable from the event), seating between the permanent tiered seats and the exhibition floor must be provided. Heretofore, this has been accomplished in numerous ways.
The simplest of these configurations has been the provision of rows of seats directly on the floor of the central area surrounding the exhibition area. This solution is easily implemented, but is satisfactory only in those cases wherein the exhibition area is built up above the floor of the central area, as is often done for musical concerts. When the exhibition surface is formed on the floor of the central area, only those in the first few rows of seats surrounding the exhibition area will be able to see the exhibition easily. Obviously, such a situation is unacceptable for general application.
Another solution to this problem is the use of temporary grandstands which are assembled and disassembled as necessary to provide grandstand seating between the permanent tiers of seats and the exhibition floor. The assembly and disassembly of temporary seating and its associated scaffolding to achieve tiered rows of spectator seating between the permanent seats and the exhibition floor is a time consuming, expensive and potentially dangerous task. Even if the scaffolding is partially pre-assembled, it is heavy and unwieldy. Therefore, there is not only a potential for accidents during the assembly/disassembly operation, but also the time required for the assembly/disassembly may be quite long and expensive. Additional expense arises from the need either to provide storage for the scaffolding and related seating (assuming it is owned by the arena), or to rent same (if it is not owned by the arena). Similarly, a minor error during assembly, such as the failure to attach or to fully tighten a bolt, can result in injury to numerous spectators if the temporary unit fails during the exhibition. Accordingly, while temporary seating is sometimes still used by some arenas, it is not preferred in the art.
Yet another attempted solution to the problem of providing seating between the permanent seats of an arena and an exhibition floor smaller than the open central area of the arena is the use of telescopic grandstand seating. Telescopic seating systems are well known in the art as shown for example by U.S. Pat. Nos. 4,041,655; 3,667,171; and 3,364,637. In this type of seating, each of the tiers of seats is mounted on a rectangular support frame including upright rear posts, horizontal seat and deck supports connecting the top ends of the upright rear posts, brace members extending between the upright posts and the horizontal seat and deck supports, and horizontal wheeled carriages connected to the lower ends of the respective posts and extending normally to the plane of the remainder of the substantially rectangular support frame. Each of the separate tiers moves independently on its associated carriages, but interlocks with the tiers above and below it when the unit is expanded into its open position. In the closed position, the various tiers nest together such that the deck/seat support/seat rows are located substantially one on top of the other to thereby create a closed unit having a width only slightly greater than the width of one tier. In the open position, on the other hand, the unit displays the common stepped configuration of a grandstand. The interlocking of the tiers generally facilitates the opening operation and prevents over-expansion of the unit. Similarly, numerous locking devices have been utilized to prevent unintended movement of the tiers toward the closed position while the unit is in use. Many installations of such seating units have minimized the extension of the closed unit into the open central area of the arena by providing recesses in the walls of the central area beneath the front rows of the permanent seats into which the telescoping grandstand seating may be closed. The advantages of these systems are numerous. They are easy to open and close. They are safe. They may be stored when not in use directly adjacent the area in which they are used with little or no loss in the usable central area of the arena.
A problem with the use of telescopic grandstand seating in the arena context remains, however. Telescopic grandstand seating of the type just described is customarily designed for use with an exhibition floor area of a particular size and shape. For example, the conversion of an open central area from a configuration suitable for a convention or trade show to a configuration suitable for a basketball game may involve locating a basketball playing surface (court) centrally on the floor of the open central area of the arena, and providing telescopic grandstand seating which extends from the permanent seating at a downward angle to a point adjacent the basketball playing surface. In that case, the respective telescopic seating units are simply opened from their closed configuration in the storage recesses in the walls of the central area. Individual seats thereafter are added to the seat supports if they are not integrally incorporated into the telescopic seating system itself. The units lock together tier to tier by means of internal mechanisms generally provided as part of the units. Similarly, the units are easy to attach together one unit to the next for added stability, if desired.
If one assumes the need to provide seating extending between the permanent seating of the arena and playing surfaces of two different sizes (such as an ice rink and a basketball court), however, the conversion of the arena amongst its various desired seating configurations becomes more complex. This is particularly true because the boards surrounding a hockey rink are a fairly permanent structure, and the required conversion time between a hockey game in the afternoon and a basketball game the same evening is on the order of two and one-half hours. A telescopic grandstand adapted to extend from the permanent seats to a point adjacent the ice will not reach a point adjacent the smaller dimensions of a basketball court. Similarly, a telescopic grandstand adapted to extend from the permanent seats to a point adjacent a basketball court cannot be fully opened to provide seating extending between the fixed seats and a point adjacent the edge of the ice. The pitch of the tiers of seats extending downward from the permanent seats is different in each case, and standard telescopic grandstand seating cannot solve both situations simultaneously. This circumstance is diagrammatically illustrated in FIG. 1 wherein a conventional telescopic grandstand located adjacent a hockey rink is shown in solid lines, and the typical location of a basketball or other smaller exhibition surface and the desired grandstand pitch for use therewith are shown in phantom.
Attempts have been made to adapt telescopic grandstand seating to solve this problem. One such proposal is to adjust the pitch of the telescopic seating from the shallow pitch used for a basketball game, for example, to the steeper pitch required for a larger playing surface, such as for a hockey game for example, by telescoping some of the tiers of the telescopic seating unit beneath the tiers directly above them (see, for example, U.S. Pat. No. 3,364,637). This so-called "double decking" approach can also be utilized to alter the configuration of a unit designed to extend to a point adjacent a smaller exhibition surface such that a preselected number of the lower tiers are all telescoped inwardly. In this configuration, the pitch of the seating changes and the lowermost row of useable seating might be located adjacent to the top of the hockey boards. In that case, temporary seating modules are placed inwardly of the boards to provide seating from the top of the boards down to a point adjacent the basketball court. It will be understood however that this so-called double decking introduces complexity in locking the various tiers together in the desired configuration. The few times that it has been tried commercially, it has proven to be undesirable.
Separate telescopic seating units could be constructed for each of the required seating configurations and substituted for each other as the situation warranted. Devices for moving telescopic seating units from place to place are well known in the art. This solution is impractical because the exchange of telescopic seating units one for another is both time consuming and expensive. Further, the necessity of providing storage outside the arena for the units not in place along the walls of the central area is cumbersome and expensive. Accordingly, this alternative also is not entirely satisfactory.

Multiple configuration grandstand seating system


An article with an operative liquid-bearing surface is adapted for transferring that liquid to a substrate material or printing plate. The entire operative surface of the article is provided with a pattern of microscopic discrete depressions which are usually laser-engraved into the surface so that a substantially continuous wall structure remains which surrounds and defines the depressions. In particular the depressions are of a cross-sectional shape which is symmetrical about one or both of a lateral and a medial axis perpendicular thereto, and arranged adjacent one another in offset fashion, and above and below one another so that the pattern thus formed is substantially uniform and repeating. Each of at least one of the pairs of lateral or medial sidewalls of any one depression are contoured, the contour of one of the pair being generally the mirror image of the other.

Anilox/Gravure rolls are used in print machinery for applying a measured amount of a liquid printing ink, varnish, lacquer or in some cases, an adhesive to a substrate material typically either in sheet form or on a reel, and as such, they are one of the most important components of such machinery as it is the Anilox/Gravure rolls which fundamentally dictates both the quantity of liquid applied to the substrate material and the uniformity of that application. Most commonly the Anilox/Gravure roll is of a steel or aluminum construction, in some cases taking the form of a sleeve, the outer cylindrical surface of which is coated with a layer of an industrial ceramic (Chromium(III) oxide, Cr2O3, being most common, but other Oxides, Carbides, and Tungsten and Molybdenum-based coatings are also known) by one of a variety of application techniques, such as plasma application, flame-spraying, chemical deposition, and application by electrolysis. The ceramic coating is then laser-engraved so as to provide a substantially uniform pattern of microscopic cells, depressions or channels therein. The manner in which the Anilox/Gravure roll is coated with a layer of a print liquid is not relevant to this Application, except to mention that the aim of the known liquid transfer mechanisms (e.g. ink fountains, chamber doctor blade systems, metering rollers, doctor blades and the like) is to ensure that the liquid is applied to the Anilox/Gravure roll in an even and repeatable fashion every time it rotates or reciprocates. In any event, it is the manner in which the liquid is retained on the Anilox/Gravure roll after application thereto, and the manner in which it is released therefrom, which ultimately determine both the evenness of the liquid coating ultimately transferred to the substrate, and the thickness (commonly referred to as dry coat or film weight) of that coating.
As such, it is understood that the cell pattern, dictated by the shape configuration of each individual cell within that pattern, the depth of the cells and the resulting volume (usually expressed as cm3/m2 or BCM/in2), are all crucial factors in determining the efficacy of the Anilox/Gravure roll, and in turn the overall quality and characteristics of the printed substrate material. Indeed it has been proposed that the particular cell shapes and their corresponding patterns can, at least to some extent, be custom-tailored for particular printing techniques and applications, for different printing inks and other liquids, and also for the particular substrate materials to be printed. For example, different cell shapes and patterns have been proposed for                gravure or flexographic printing, metal decoration and laminating applications,        applications requiring particularly high or low dry coat weights, or different opacities,        applications requiring high or low definition, resolution or precision of images and other content printed on the substrate material,        different substrates, for example paper, board and card, or plastics, particularly polymer plastics films,        ultra-violet (UV) cured inks, varnishes and lacquers, dry- or heat-cured liquids, including adhesives.
Specific examples of engravings available from the Applicant herefor include the HVS (High Volume Solids), i-Pro, HOW (high opacity white), and HVP (High Volume Process) engravings.
Despite the number and variety of cell shapes, dimensions, depths, and their corresponding cell patterns, there are a number of problems commonly encountered when printing or coating with Anilox/Gravure and other rolls with laser-engraved cell patterns. Such problems are manifested firstly in terms of the quality of the printed substrate material, on which issues such as pin-holing, haze, moiré effects and absorption can arise, such generally being the direct result of an uneven transfer of print or coating liquid from the engraved roll. Secondly, in terms of the Anilox/Gravure roll itself, the most common problem is blocking, particularly where cells are relatively deep and a residue of print or coating liquid remains in the lower reaches of the cell after each transfer, eventually solidifying therein and effectively completely compromising the transfer characteristics of the roll.
As performance demands for Anilox/Gravure and other rolls are increasing, particularly with regard to operative speeds, it is becoming increasingly difficult to ensure that each and every cell of the engraving contains exactly the same amount of the printing liquid after it is applied to the surface of the Anilox/Gravure roll. The viscosity and surface tension characteristics are different for every liquid, and these affect the extent to which the liquid can flow over the surface of the Anilox/Gravure roll and the extent to which it is retained and contained within any one cell. Such factors also importantly affect the liquid transfer characteristics of the Anilox/Gravure roll, that is the extent to which the liquid content of any one cell within the engraving on the Anilox/Gravure roll is transferred either to the substrate material or (more commonly) to an offset print cylinder or plate. In practice, it is simply impossible to achieve either a perfectly uniform liquid distribution over the entire surface of the Anilox/Gravure roll. Furthermore, it is also proving impossible to achieve complete transfer of the entire volume of liquid in each and every cell to the substrate or the offset print cylinder.
The present invention therefore has as one of its objectives the provision of an engraved, embossed, etched or incised liquid bearing article which seeks to improve both the uniformity of liquid retention on that article, and the extent to which the liquid borne by the article is subsequently transferred either to a substrate material or an offset or transfer roll or plate.
It is a further object of the invention, in some embodiments, to provide an article on a liquid-bearing surface of which is provided a generally uniform repeating pattern of individual cells being of a relatively shallow depth to mitigate against blocking, but which have a relatively large cross-sectional shape so that the volume of print or coating liquid contained within each cell (and thus by the entire liquid-bearing surface of the article) is sufficient to meet modern demands for high coat weights without compromising, and in some cases actually improving, the transfer characteristics of the article.

Liquid-bearing articles for transferring and applying liquids

SANDON GLOBAL ENGRAVING TECHNOLOGY LIMITED


Method and apparatus are provided for polishing conductive materials with low dishing of features and reduced or minimal remaining residues. In one aspect, a method is provided for processing a substrate by polishing the substrate to remove bulk conductive material and polishing the substrate by a ratio of carrier head rotational speed to platen rotational speed of between about 2:1 and about 3:1 to remove residual conductive material. In another aspect, a method is provided for processing a substrate including polishing the substrate at a first relative linear velocity between about 600 mm/second and about 1900 mm/second at the center of the substrate, and polishing the substrate at a second relative linear velocity between about 100 mm/second and about 550 mm/second at the center of the substrate.

1. Field of the Invention
Aspects of the invention generally relate to the fabrication of semiconductor devices and to chemical mechanical polishing and planarization of semiconductor devices.
2. Description of the Related Art
Reliably producing sub-half micron and smaller features is one of the key technologies for the next generation of very large-scale integration (VLSI) and ultra large-scale integration (ULSI) of semiconductor devices. However, as the fringes of circuit technology are pressed, the shrinking dimensions of interconnects in VLSI and ULSI technology has placed additional demands on the processing capabilities. The multilevel interconnects that lie at the heart of this technology require precise processing of high aspect ratio features, such as vias, contacts, lines, and other interconnects. Reliable formation of these interconnects is important to VLSI and ULSI success and to the continued effort to increase circuit density and quality of individual substrates and die.
In order to further improve the current density of semiconductor devices on integrated circuits, it has become necessary to use conductive materials having low resistivity for conductors and materials having low dielectric constant (low k, defined herein as having dielectric constants, k, less than about 4.0) as insulating layers to reduce the capacitive coupling between adjacent interconnects. Increased capacitative coupling between layers can detrimentally affect the functioning of semiconductor devices.
One conductive material gaining acceptance is copper and its alloys, which have become the materials of choice for sub-quarter-micron interconnect technology because copper has a lower resistivity than aluminum, (1.7 μΩ-cm compared to 3.1 μΩ-cm for aluminum), a higher current and higher carrying capacity. These characteristics are important for supporting the higher current densities experienced at high levels of integration and increased device speed. Further, copper has a good thermal conductivity and is available in a highly pure state.
One difficulty in using copper in semiconductor devices is that copper is difficult to etch and achieve a precise pattern. Etching with copper using traditional deposition/etch processes for forming interconnects has been less than satisfactory. Therefore, new methods of manufacturing interconnects having copper-containing materials and low k dielectric materials are being developed.
One method for forming vertical and horizontal interconnects is by a damascene or dual damascene method. In the damascene method, one or more dielectric materials, such as the low k dielectric materials, are deposited and pattern etched to form the vertical interconnects, i.e., vias, and horizontal interconnects, i.e., lines. Conductive materials, such as copper-containing materials, and other materials, such as barrier layer materials used to prevent diffusion of copper-containing materials into the surrounding low k dielectric, are then inlaid into the etched pattern. Any excess copper-containing materials and excess barrier layer material external to the etched pattern, such as on the field of the substrate, is then removed.
As layers of materials are sequentially deposited and removed, the uppermost surface of the substrate may become non-planar across its surface and require planarization. Planarizing a surface, or "polishing" a surface, is a process where material is removed from the surface of the substrate to form a generally even, planar surface. Planarization is useful in dual damascene processes to remove excess deposited material and to provide an even surface for subsequent levels of metallization and processing. Planarization may also be used in removing undesired surface topography and surface defects, such as rough surfaces, agglomerated materials, crystal lattice damage, scratches, and contaminated layers or materials.
Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique used to planarize substrates. In conventional CMP techniques, a substrate carrier or polishing head is mounted on a carrier assembly and positioned in contact with a polishing article in a CMP apparatus. The carrier assembly provides a controllable pressure to the substrate urging the substrate against the polishing media. The article is moved relative to the substrate by an external driving force. Thus, the CMP apparatus effects polishing or rubbing movement between the surface of the substrate and the polishing article while dispersing a polishing composition to effect both chemical activity and mechanical activity.
Conventionally, in polishing copper features, such as dual damascene features, the copper-containing material, and a portion of the barrier layer, is polished to the level of the barrier layer, and then the barrier layer is polished, with a portion of the dielectric layer and copper features, to a level of the underlying dielectric layer using abrasive polishing solutions. However, such a polishing process often results in uneven removal of copper in features and the dielectric layer resulting is the formation of topographical defects, such as concavities or depressions in the features, referred to as dishing, and removal of dielectric material surrounding features, referred to as erosion.
FIG. 1 is a schematic view of a substrate illustrating the phenomenon of dishing. Conductive lines 11 and 12 are formed by depositing conductive materials, such as copper or copper alloy, in a feature definition formed in the dielectric layer 10, typically comprised of silicon oxides or other dielectric materials. After planarization, a portion of the conductive material is depressed by an amount D, referred to as the amount of dishing, forming a concave copper surface. Dishing results in a non-planar surface that impairs the ability to print high-resolution lines during subsequent photolithographic steps and detrimentally affects subsequent surface topography of the substrate and device formation. Dishing also detrimentally affects the performance of devices by lowering the conductance and increasing the resistance of the devices, contrary to the benefit of using higher conductive materials, such as copper.
One solution is to polish copper material by using abrasive-free polishing compositions. However, abrasive-free polishing compositions may be unable to sufficiently remove all of the desired copper materials from a substrate surface, such as at the interface between copper and the barrier layer, which is generally non-planar. Such copper materials retained on the substrate surface, or residues, can detrimentally affect device formation, such as creating short-circuits within or between devices, and thereby reduce device yields and reduce substrate throughput, as well as detrimentally affect the polish quality of the substrate surface.
One solution to ensure removal of all the copper material including copper residues before removing the barrier material is to overpolish the copper and the interface. However, overpolishing of the interface with abrasive-free polishing compositions have not been successful in removing copper residues, and removal of those residues often require extensive polishing times, which have resulted in increased operating costs and decreased substrate throughput.
Therefore, there exists a need for an apparatus, and method that facilitates the removal of copper-containing material from the surface of a substrate with minimal or reduced dishing and with essentially no residues remaining after polishing.

Method of chemical mechanical polishing with high throughput and low dishing


A method and computer system for deriving and applying normal moveout corrections to seismic survey traces is disclosed. In each common midpoint (CMP) gather, a stacking velocity function of travel time is first determined for near-offset traces. For each reflective event, a time window about a depth point is selected. Time anisotropy and velocity anisotropy values are then determined for the depth point, for example by way of a semblance analysis applied to envelopes of the traces over the full offset range. Normal moveout corrections are then determined by a weighted sum expression of travel time (zero-offset time plus moveout correction) The weighted sum adds a first travel time expression corresponding to a Dix equation expression with a second travel time expression corresponding to a skewed hyperbolic expression that includes the time and velocity anisotropy values, with the weighting dependent upon the offset of the particular trace. Near-offset traces receive relatively higher weighting of the Dix equation expression, while far-offset traces receive relatively higher weighting of the skewed hyperbolic expression. Because higher order power expressions are eliminated according to this approach, improved moveout correction accuracy is obtained over near and far offsets, with reduced sensitivity to measurement error.

This invention is in the field of seismic prospecting, and is more specifically directed to the analysis of seismic survey signals obtained in such exploration.
The use of seismic survey techniques is commonplace in the prospecting for subsurface reservoirs of hydrocarbons such as oil and gas. As is fundamental in the art, seismic surveys are typically obtained by imparting acoustic energy into the earth, either at a land surface or into the water in a marine survey, and detecting the energy at other surface or marine locations away from the source. The detectors sense the arrival of the acoustic energy after reflection from subsurface strata and interfaces, such that the time delay between the imparting of energy by the source and its receipt by the detectors will be indicative of the depth below the earth surface at which the reflecting interface is located. Conversion of the time-domain reflection signals into depth will thus provide a survey of the subsurface geology.
FIG. 1 illustrates a conventional land-based seismic survey in a portion of the earth having multiple subsurface strata 2, 4, 6, 8. In the example of FIG. 1, a reflective geological interface is present in the earth between subsurface strata 6,8 along which a particular depth point DP of interest for this description is located. Of course, many depth points, both along the interface between strata 6,8 and also from other interfaces in the region, will be analyzed in a typical survey.
In the typical land-based seismic survey, an array of receivers are deployed at the surface of the earth, and acoustic energy is imparted into the earth at varying surface source locations; in the typical marine seismic survey, the seismic source is towed by a vessel and activated at selected locations, and the receivers are either deployed in the water at fixed locations or are also towed by the source vessel. In either survey, the imparted energy is reflected from interfaces between subsurface strata, and this reflected energy is detected by the receivers in the array. In the simplified land-based example of FIG. 1, acoustic energy is reflected from depth point DP along multiple source-receiver paths that have varying angles of reflection at depth point DP. As such, the reflected energy is detected at receiver locations that have varying offset distances from the vertical, "zero-offset", path above depth point DP. The so-called "zero-offset" location is the surface location which is directly above depth point DP (i.e., the zero-offset location is the location at which reflected energy from depth point DP would reflect back to the source location). Typically, a zero-offset signal is not actually obtained in a survey, but is instead extrapolated from the other traces of varying offset.
Two source-receiver paths P.sub.n, P.sub.f are illustrated in the simplified example of FIG. 1. Near-offset path P.sub.n corresponds to energy imparted at source location S.sub.n and detected by receiver R.sub.n after being reflected from depth point DP, while far-offset path P.sub.f corresponds to energy imparted at source location S.sub.f and detected by receiver R.sub.f, also after reflection from depth point DP. The offset distances of paths P.sub.n, P.sub.f are illustrated in FIG. 1 as offsets x.sub.n, x.sub.f, respectively. Because the overall length of far-offset path P.sub.f is significantly greater than that of near-offset path P.sub.n, the travel time of acoustic energy along far-offset path P.sub.f is much greater than that along near-offset path P.sub.n, despite the paths having a common depth point DP.
A well-known technique in the art for eliminating random noise from the survey signals is referred to as common midpoint (CMP), or common depth point (CDP), gather and stack. In this technique, the signals from each source-receiver path having the same depth point are selected from the survey data, forming a group of traces known as a CMP (or, equivalently, CDP) gather. Elimination of random noise is then performed by summing the traces in the gather into a "stack". This summation will tend to reinforce the signal portion of the traces corresponding to the reflection event, which should be common among all traces having the same reflection midpoint, while the random noise will tend to cancel in the summation.
As noted above for the example of FIG. 1, in the CMP gather for depth point DP.sub.i, the seismic traces detected by receivers R.sub.n, R.sub.f will have different reflection times for energy reflected from the same reflection point DP, because their paths P.sub.n, P.sub.f are of different length. Specifically, the time at which energy reflected from depth point DP will appear in the trace for receiver R.sub.f will be later than the time at which energy reflected from depth point DP will appear in the trace for receiver R.sub.n. This time-delay effect of varying offset must be taken into account in the CMP stack process in order for the signal portions of traces of varying offset to properly align and provide an accurate indication of the depth of the reflector. This is typically handled by way of "normal moveout correction", or NMO (also NMOC), in which the traces corresponding to source-receiver paths of various lengths are time-shifted relative to one another so that their detected reflection events are aligned in time. The amount of the time shift for a given trace will, of course, depend upon its offset distance and upon the velocity with which the acoustic energy travels in the strata along the shot-receiver path. Normal moveout correction therefore requires the estimation or determination of a velocity, commonly referred to as the "stacking" velocity, for deriving the necessary time shift as a function of offset.
By way of further background, another well-known survey approach is commonly referred to as vertical seismic prospecting (VSP). In a VSP survey, energy is imparted into the earth from subsurface locations within a wellbore, and detected at surface detectors. The time delay between the imparting of energy by the wellbore source and its receipt by the surface detectors, in the VSP survey, will be indicative of attributes, such as acoustic velocities, of the subsurface strata, and may also be indicative of discontinuities and interfaces among the various strata. Of course, similarly as in the case of the surface-source seismic survey, the offset distance between the wellbore and the surface detectors will directly affect the time delay at which acoustic energy is detected at the surface. As such, normal moveout corrections are also necessary to process seismic signals obtained in VSP surveys. For purposes of clarity, the following discussion will refer to the conventional surface-based source seismic surveys, it being understood that similar concerns are applicable for moveout correction in VSP surveys.
In the ideal geological situation of a homogenous and isotropic medium, the wave surface of the acoustic energy imparted into the earth is spherical. Assuming reflection of the spherical wave surface from a horizontal reflecting surface in this ideal case, the relationship between arrival time t of the energy at a given surface detector R, and the offset distance x of detector R corresponds to a centered hyperbola; the relationship between offset distance x and travel time t is thus a straight line in the t.sup.2 versus x.sup.2 domain. The NMO time correction .DELTA.t.sub.x for a given seismic reflection event in a seismic trace may be derived according to the well-known Dix equation: ##EQU1## where t.sub.0 is the zero offset reflection time of a given reflection, where x is the offset distance of the trace to be corrected, and where V.sub.v is the acoustic velocity in the homogeneous isotropic medium. Solving this relationship for .DELTA.t.sub.x will produce the NMO time shift for the reflection event in the trace being corrected. In practice, the stacking velocity V.sub.v is typically determined as a root-mean-square velocity, or as a best-fit average velocity by way of a semblance analysis or other technique, to account for the multiple strata (e.g., strata 2, 4, 6 in the example of FIG. 1) through which the acoustic energy travels.
As noted above, the Dix equation hyperbola assumes the ideal condition of isotropic velocity in a homogenous medium. In practice, however, the subsurface of the earth often exhibits variations in velocity that depend upon the angle of propagation of the acoustic energy from the vertical, zero-offset, axis. In particular, the horizontal ray velocity (V.sub.h) generally differs from the vertical ray velocity (V.sub.v) along the zero-offset path. These effect of these variations, which is commonly referred to in the art as transverse isotropy, is due to the heterogeneity of velocities among the subsurface strata in the survey, and also to the anisotropic response of the earth to acoustic energy. Physical factors that cause anisotropic response include preferential orientation of rock properties, such as in sedimentary rocks with aligned crystals and sand grains, and also rocks with directional microcracks induced by regional stress fields. A simple modification of the Dix hyperbolic equation accounts for differences between the vertical and horizontal ray velocities V.sub.v, V.sub.h, respectively, as follows: ##EQU2## This expression of the Dix equation corresponds to an elliptical wave surface of acoustic energy traveling through the earth, with different velocity components in the vertical and horizontal directions.
The propagation of long-wavelength acoustic energy has been observed to exhibit apparent transverse isotropy in stratified regions of the earth, even in cases where each layer in the stratified region is itself individually isotropic. This apparent transverse isotropy is due to the dominance, at long offsets, of high velocity layers in the travel time of acoustic energy through multiple layers in the region, which causes the apparent horizontal velocity to be higher than the zero-offset, vertical, velocity. Sedimentary rocks that are formed through sand-shale stratification and other cyclic sedimentation processes typically exhibit transverse isotropy. In transversely isotropic regions, the accuracy of the Dix equation is practically limited to relatively short offset distances, such as offsets ranging up to on the order of the depth of the reflecting interface. For example, referring to FIG. 1, each of paths P.sub.n, P.sub.f pass through multiple strata 2, 4, 6. While the acoustic velocities are uniform within each of strata 2, 4, 6, the relative distances traversed by each path P.sub.n, P.sub.f vary with increasing offset distance. Therefore, even assuming that strata 2, 4, 6 are each individually transversely isotropic (i.e., having the same acoustic velocity in all horizontal directions therewithin), the stacking velocity will typically not be constant over the range of offsets obtained in the survey. Accordingly, the Dix equation hyperbolic assumption remains valid only over near-offset traces, as the time-distance relationship is no longer hyperbolic at large offsets in vertically anisotropic regions, such as those including transversely isotropic strata as shown in FIG. 1.
An example of the skewing of the horizontal velocity in transversely isotropic regions is illustrated in the plot of FIG. 2. FIG. 2 is a plot of vertical velocity V.sub.v versus horizontal velocity V.sub.h, illustrating the elliptical wavefront of acoustic energy, according to the Dix equation modified to incorporate different horizontal and vertical velocities V.sub.v, V.sub.h, as described above. In FIG. 2, ellipse E.sub.d is a plot of the wavefront of acoustic energy in accordance with the Dix equation, using the hyperbolic assumption described hereinabove. In this example, a horizontal velocity V.sub.he is estimated from the Dix equation. Skewed ellipse E.sub.s illustrates the actual horizontal velocity V.sub.ha that occurs in transversely isotropic media. As illustrated in FIG. 2, the actual horizontal velocity V.sub.ha is slightly larger than that estimated from the Dix equation according to the hyperbolic assumption. This discrepancy from the Dix equation will be most evident in far-offset traces, of course, considering the longer path distances presented therein. Accordingly, use of the Dix equation in conventional normal moveout processing is therefore not adequate to derive accurate normal moveout correction values for far-offset data in transversely isotropic regions, due to the discrepancy between the actual horizontal velocity and that which would be applied through solution of the Dix equation using conventional methods.
Conventional approaches for determining normal moveout corrections for far-offset seismic traces in transversely isotropic media are known. One approach utilizes a truncated Taylor series expansion to model the t.sup.2 -x.sup.2 relationship in the survey region. As described in Hake et al., "Three-term Taylor Series for t.sup.2 -x.sup.2 Curves of P- and S-Waves over Layered Transversely Isotropic Ground", Geophysical Prospecting 32 (1984), pp. 828-850, a three-term Taylor series expansion of t.sup.2 as a function of x.sup.2 may be used to calculate the elastic parameters of the transversely isotropic media. Quartic Taylor series expansion, using exact coefficients, has also been applied to the transversely isotropic layered media problem, as described in Tsvankin, et al., "Nonhyperbolic reflection moveout in anisotropic media", Geophysics, Vol. 59, No. 8 (August 1994), pp. 1290-1304.
The truncated Taylor series expansion has been successful in deriving nonhyperbolic moveout correction for long-offset reflection seismic data, particularly in improving the results of CMP stacking to improve the image of reflection signals. However, it is also desirable to derive estimates of the anisotropy parameters from the moveout analysis, to permit inversion of subsurface parameters that are indicative of the nature of the various strata in the survey region. It has been found, in connection with the present invention, that truncated Taylor series analysis is not well-suited for subsurface parameter inversion, because of the sensitivity of the Taylor series coefficients to measurement errors. The heightened error sensitivity is primarily due to the higher order (third order and higher) terms used in the Taylor series analysis.
By way of further background, another approach toward estimation of stiffness coefficients for multiple transversely isotropic layers in a seismic survey region is described in Byun et al., "Transversely isotropic velocity analysis for lithology discrimination", Geoexploration 28 (Elsevier Science Publishers B. V., 1991), pp. 269-292, incorporated herein by this reference. According to this approach, a skewed hyperbolic moveout formula is applied to pressure waves to derive three measurement parameters which, when combined with two shear wave measurement parameters, enable inversion for the five stiffness coefficients by way of a model-iterative optimization scheme.

Method and system for determining normal moveout parameters for long offset seismic survey signals


A low density parity check (LDPC) code that is particularly well adapted for hardware implementation of a belief propagation decoder circuit (38) is disclosed. The LDPC code is arranged as a parity check matrix (H) whose rows and columns represent check sums and input nodes, respectively. The parity check matrix is grouped into subsets of check sum rows, in which the column weight is a maximum of one. The decoder circuitry includes a parity check value estimate memory (52). Adders (54) generate extrinsic estimates, from immediately updated input node probability estimates, and the extrinsic estimates are applied to parity check update circuitry (56) for generating new parity check sum value estimates. These parity check sum value estimates are stored back into the memory (52), and after addition with the extrinsic estimates, are stored in a column sum memory (66) of a corresponding bit update circuit (60) as updated probability values for the input nodes.

This invention is in the field of digital data communications, and is more specifically directed to decoding of transmissions that have been coded for error detection and correction.
High-speed data communications, for example in providing high-speed Internet access, is now a widespread utility for many businesses, schools, and homes. At this stage of development, such access is provided according to an array of technologies. Data communications are carried out over existing telephone lines, with relatively slow data rates provided by voice band modems (e.g., according to the current v.92 communications standards), and at higher data rates using Digital Subscriber Line (DSL) technology. Another modern data communications approach involves the use of cable modems communicating over coaxial cable, such as provided in connection with cable television services. The Integrated Services Digital Network (ISDN) is a system of digital phone connections over which data is transmitted simultaneously across the world using end-to-end digital connectivity. Localized wireless network connectivity according to the IEEE 802.11 standard has become very popular for connecting computer workstations and portable computers to a local area network (LAN), and often through the LAN to the Internet. Wireless data communication in the Wide Area Network (WAN) context, which provides cellular-type connectivity for portable and handheld computing devices, is expected to also grow in popularity.
A problem that is common to all data communications technologies is the corruption of data due to noise. As is fundamental in the art, the signal-to-noise ratio for a communications channel is a degree of goodness of the communications carried out over that channel, as it conveys the relative strength of the signal that carries the data (as attenuated over distance and time), to the noise present on that channel. These factors relate directly to the likelihood that a data bit or symbol received over the channel is in error relative to the data bit or symbol as transmitted. This likelihood is reflected by the error probability for the communications over the channel, commonly expressed as the Bit Error Rate (BER) ratio of errored bits to total bits transmitted. In short, the likelihood of error in data communications must be considered in developing a communications technology. Techniques for detecting and correcting errors in the communicated data must be incorporated for the communications technology to be useful.
Error detection and correction techniques are typically implemented through the use of redundant coding of the data. In general, redundant coding inserts data bits into the transmitted data stream that do not add any additional information, but that indicate whether an error is present in the received data stream. More complex codes provide the ability to deduce the true transmitted data from a received data stream, despite the presence of errors.
Many types of redundant codes that provide error correction have been developed. One type of code simply repeats the transmission, for example repeating the payload twice, so that the receiver deduces the transmitted data by applying a decoder that determines the majority vote of the three transmissions for each bit. Of course, this simple redundant approach does not necessarily correct every error, but greatly reduces the payload data rate. In this example, a predictable likelihood remains that two of three bits are in error, resulting in an erroneous majority vote despite the useful data rate having been reduced to one-third. More efficient approaches, such as Hamming codes, have been developed toward the goal of reducing the error rate while maximizing the data rate.
The well-known Shannon limit provides a theoretical bound on the optimization of decoder error as a function of data rate. The Shannon limit provides a metric against which codes can be compared, both in the absolute and relative to one another. Since the time of the Shannon proof, modern data correction codes have been developed to more closely approach the theoretical limit. An important type of these conventional codes are "turbo" codes, which encode the data stream by applying two convolutional encoders. One convolutional encoder encodes the datastream as given, while the other encodes a pseudo-randomly interleaved version of the data stream. The results from the two encoders are interwoven to produce the output encoded data stream.
Another class of known redundant codes is the Low Density Parity Check code. According to this class of codes, a sparse matrix H defines the code, with the encodings, or codewords, c of the payload data satisfying:Hc=0  (1)over Galois field GF(2). Each codeword c consists of the source message s combined with the corresponding parity check bits for that source message s. The encodings c are transmitted, with the receiving network element receiving a signal vector r=c+n, n being the noise added by the channel. Because the decoder at the receiver knows matrix H, it can compute a vector z=Hr. However, because r=c+n, and because Hc=0:z=Hr=Hc+Hn=Hn  (2)The decoding process thus involves finding the sparsest vector x that satisfies the equation:Hx=z  (3)over GF(2). The vector x becomes the best guess for noise vector n, which can be subtracted from the received signal vector r to recover encodings c, from which the original source message s is recoverable. There are many examples of LDPC codes that are known in the art, some of which have been described as providing code performance that approaches the Shannon limit, as described in Tanner et al., "A Class of Group-Structured LDPC Codes", ISTCA-2001 Proc. (Ambleside, England, 2001).
However, high-performance LDPC code decoders are difficult to implement into hardware. While Shannon's adage holds that random codes are good codes, it is regularity that allows efficient hardware implementation. To address this difficult tradeoff between code irregularity and hardware efficiency, the technique of belief propagation provides an iterative implementation of LDPC decoding that can be made somewhat efficient, as described in Richardson, et al., "Design of Capacity—Approaching Irregular Low-Density Parity Check Codes," IEEE Trans. on Information Theory, Vol. 47, No. 2 (February 2001), pp. 619–637; and in Zhang et al., "VLSI Implementation-Oriented (3,k)-Regular Low-Density Parity-Check Codes", IEEE Workshop on Signal Processing Systems (September 2001), pp. 25.–36. Belief propagation decoding algorithms are also referred to in the art as probability propagation algorithms, message passing algorithms, and as sum-product algorithms.
In summary, belief propagation algorithms are based on the binary parity check property of LDPC codes. As mentioned above and as known in the art, each check vertex in the LDPC code constrains its neighboring variables to form a word of even parity. In other words, the product of the correct LDPC code word vector with each row of the parity check matrix sums to zero. According to the belief propagation approach, the received data are used to represent the input probabilities at each input node (also referred to as a "bit node") of a bipartite graph having input nodes and check nodes. Within each iteration of the belief propagation method, bit probability messages are passed from the input nodes to the check nodes, updated according to the parity check constraint, with the updated values sent back to and summed at the input nodes. The summed inputs are formed into log likelihood ratios (LLRs) defined as:
                              L                                (            c            )                          =                  log                                (                                          P                                                  (                                      c                    =                    0                                    )                                                            P                                                  (                                      c                    =                    1                                    )                                                      )                                              (        4        )            where c is a coded bit received over the channel.
In its conventional implementation, the belief propagation algorithm uses two value arrays, a first array L storing the LLRs for j input nodes, and the second array R storing the results of m parity check node updates, with m being the parity check row index and j being the column (or input node) index of the parity check matrix H. The general operation of this conventional approach determines, in a first step, the R values by estimating, for each check sum (row of the parity check matrix) the probability of the input node value from the other inputs used in that checksum. The second step of this algorithm determines the LLR probability values of array L by combining, for each column, the R values for that input node from parity check matrix rows in which that input node participated. A "hard" decision is then made from the resulting probability values, and is applied to the parity check matrix. This two-step iterative approach is repeated until the parity check matrix is satisfied (all parity check rows equal zero, GF(2)), or until another convergence criteria is reached, or a terminal number of iterations have been executed.
By way of further background, the code design approach described in Boutillon et al., "Decoder-First Code Design", Proc.: Int'l Symp. on Turbo Codes and Related Topics (Brest, France, September 2001) defines the decoder architecture first, and uses this architecture to constrain the design of the LDPC code itself. Sridhara, et al., "Low Density Parity Check Codes from Permutation Matrices", 2001 Conference on Information Sciences and Systems (Johns Hopkins University, Mar. 21–23, 2001) describes the LDPC code as constructed from shifted identity matrices (i.e., permutation matrices).
However, it has been observed that these prior approaches are somewhat limited, in that these approaches are limited to a single code or a small selection of codes. Practically useful communications receivers require some amount of flexibility in code rates, and in optimizing their operation for varying noise levels and channel conditions. As a result of this observation, my copending and commonly assigned application Ser. No. 10/329,597 filed Dec. 26, 2002, published as U.S. Patent Application Publication No. US 2004/0034828 A1, and incorporated herein by this reference describes a low density parity check (LDPC) code that is particularly well adapted for efficient hardware implementation in a belief propagation decoder circuit. As described in this copending application, the LDPC code is arranged as a macro matrix whose rows and columns represent block columns and block rows of a corresponding parity check matrix. Each non-zero entry corresponds to a permutation matrix, such as a cyclically shifted identity matrix, with the shift corresponding to the position of the permutation matrix entry in the macro matrix. The block columns of the macro matrix are grouped, so that only one column in the macro matrix group contributes to the parity check sum in any given row. The decoder circuitry includes a parity check value estimate memory which may be arranged in banks that can be logically connected in various data widths and depths. A parallel adder generates extrinsic estimates that are applied to parity check update circuitry for generating new parity check value estimates. These parity check value estimates are stored back into the memory, and are forwarded to bit update circuits for updating of probability values for the input nodes.
By way of further background, my copending and commonly assigned application Ser. No. 10/724,280, filed Nov. 28, 2003 published as U.S. Patent Application Publication No. US 2004/0148560, and incorporated herein by this reference, describes encoder circuitry for applying a low-density parity check (LDPC) code, such as that described in the above-referenced Patent Application Publication US 2004/0034828 A1, to information words to be transmitted.
By way of still further background, Li et al., "Generalized Product Accumulate Codes: Analysis and Performance", Global Communications Conference (Globecomm) (IEEE, 2001), pp. 975–79, describe a layered approach to the outer code of product accumulate codes. It is observed that these outer codes (referred to in the paper as "turbo" product codes) are layered LDPC codes, with each layer decoded by way of belief propagation. It is also observed that, because the column weight in each layer is at most one, only a single iteration is possible within each layer.
By way of still further background, Mansour, et al., "Turbo decoder architectures for low-density parity check codes", Global Communications Conference (Globecomm) (IEEE, 2002), pp. 1383–88; and Mansour, et al., "On the Architecture-Aware Structure of LDPC Codes from Generalized Ramanujan Graphs and their Decoder Architectures", 2003 Conference on Information Sciences and Systems (Johns Hopkins University, Mar. 12, 2002), also describe a layered, or "turbo", approach for LDPC decoding. In these articles, the LDPC parity check matrices are block partitioned into columns and rows, with a maximum column weight of one in each layer. These articles assert that the layered approach reduces the number of iterations necessary for decoding, relative to belief propagation decoding that does not use layered decoding.

Layered low density parity check decoding for digital communications


According to one embodiment, a liquid crystal display device comprises first and second substrates and a liquid crystal layer. The first substrate includes a base member, a sensor between the base member and the liquid crystal layer, a collimation layer between the sensor and the liquid crystal layer, an insulating layer between the sensor and the collimation layer, an insulating layer, and a light shielding layer between the sensor and the base member. The sensor is configured to output a signal corresponding to light incident from a liquid crystal layer side. The light shielding layer overlaps with an outer peripheral part of the first collimation layer.

In recent years, liquid crystal display devices storing sensors to read biometric information such as a fingerprint sensor, a vein sensor, and the like have been developed. The sensors may be optical sensors using, for example, photoelectric conversion elements. Above the sensors, one or more collimation layers to block diagonal incident light are arranged.
The sensors detect light from a light source such as a backlight and reflected by a target object. The light going toward the target object may be reflected by the back surface of the collimation layer, and if the reflection light is incident on the sensor, noise will occur, and accuracy of detection will decrease.


A gas safety valve includes a main body having a longitudinal through-hole consisting of a first section, a second section, and a third section with different inner diameters. A ball and a restraining member are mounted in the first section. A spring is mounted in the second section, with an end of the spring protruding out of the second section for biasing the ball away from the second section. An outer sleeve is force-fitted in the third section of the main body. A hollow adjusting block is mounted in the outer sleeve and has an outer threading for threadedly engaging with an inner threading of the outer sleeve. The other end of the spring abuts against the adjusting block. Adjustment of a position of the hollow adjusting block in the outer sleeve changes a distance between the ball and the second section.

1. Field of the Invention
The present invention relates to a gas safety device. In particular, the present invention relates to a gas safety device including a main body and a ball that can block a gas passageway defined by a longitudinal through-hole of the main body when excessive flow occurs, thereby preventing mass leakage.
2. Description of the Related Art
Pressure difference has already been utilized in gas safety devices for assuring safety use of gas. U.S. Pat. No. 5,983,928 discloses a gas safety valve comprising a valve body with a longitudinal through-hole for receiving a ball. The longitudinal through-hole of the gas safety valve comprises several sections of various inner diameters such that when mass leakage occurs, the ball is moved to compress a spring and to block the longitudinal through-hole as a result of a pressure difference between two sides of the ball. Such a structure can be applied to gas sources of different pressure by means of simply changing the spring. However, the elastic constant of springs cannot be always identical even if they are manufactured under the same condition and thus fail to meet the requirement of precision. Namely, the ball might be incapable of blocking the longitudinal through-hole of the valve body, as the elastic constant of the spring is not within the predetermined operational range.
U.S. Pat. No. 6,405,751 discloses a gas safety valve comprising a main body, a valve seat, a restraining member, and an engaging member. The valve seat and the restraining member are threadedly engaged in the main body. The valve seat includes a valve block, a spring, and an adjusting element. When gas leakage occurs, the valve block blocks a longitudinal through-hole of the valve body, preventing mass leakage. Operation of the gas safety valve can be precisely achieved within a predetermined operational range. The structure of this gas safety valve is, however, complicated. When adjustment is required, the valve seat and the restraining member have to be troublesomely removed from the main body. And the valve seat and the restraining member have to be threadedly reengaged in the main body. As a result, the precision after adjustment may still has an error.


Implementations of the present disclosure disclose a device support stand assembly. According to one implementation, the assembly includes a removable support stand member having an attachment feature for coupling to a corresponding mating element formed on a rear side of a portable electronic device. In addition, the support stand member includes a tension spring configured for dual operating positions with respect to the portable electronic device.

The emergence and popularity of mobile computing has made portable electronic devices—due to their compact design and light weight—a staple in today's marketplace. Mobile devices such as tablet personal computers and smartphones involve advance computing functionality and are utilized for multiples tasks such as email, internet surfing, gaming, and media capture/playback. During these times, user's often place their device on a normal operating surface for easier operation or viewing.

Hewlett-Packard Development Company, L.P.


PRACTICE TARGET FOR BALL GAMES is a means to improve scoring or throwing skills in games utilizing a ball or propelled device including but not limited to lacrosse, baseball football, hockey and soccer. The system as described comprises a metal ring encircled by a colored material which is amenable to being positioned at any desired location on a support. This support could be either a goal-post for any of the games mentioned earlier or an eassily assembled structure that could be provided along with the practice target ring. The size of the ring would be proportional to the size of the porpelling device used in the game being practiced. The metal ring is attached to a metal plate of variable length which is in turn provided with a bracket for attachment to a vertical or horizontal support.

1. Field of Invention
The present invention as described relates to a device which comprises a metal ring attached to a plate of variable length. Which in turn is attached with a bracket to a horizontal or vertical support and is amenable to being positioned at any desired location along the support. This support could be either a goal-post for games with goals or an eassily assembled structure that could be provided along with the practice target device.
2. Description of Related Art
Adjustable and demountable practice targets for ball games devices are known in the art. The known devices generally comprise a bracket secured to a standard or a framework usually provided in conjunction with the device. Although these known devices are usually made adjustable and in some instances can be disassembled for portability they are nevertheless limited in their applcation to the paticular purpose for which they were designed.


A method for the rapid measurement of polarization dependent properties of an optical device under test uses a novel technique to generate light in four different polarization states in which each state is individually sensed at a different interference frequency.

Polarization measurements such as Polarization Mode Dispersion (PMD)/Differential Group Delay (DGD) and Polarization Dependent Loss (PDL) play a critical role in the design of current high-speed optical communication systems. These parameters are usually determined by algorithms that require a set of measurements for a number of polarization states. In general, it is desired to measure both DGD and PDL as a function of wavelength since the parameters typically vary with wavelength for an optical device.
In conventional measurement systems, a separate scan for each polarization state across the wavelength region of interest is required. Furthermore, averaging of multiple scans for each state may be necessary to achieve the desired signal-to-noise ratio in the measurement. This can yield relatively long measurement times during which the device must not be disturbed. In addition, long measurement times can limit the manufacturing throughput.
There are known several methods to determine the PDL and PMD/DGD of an optical device. The most important techniques are based on applying a set of well-known polarization states to the device under test (DUT) and measuring the transfer function (amplitude and phase of the signal as a function of optical wavelength) at the receiver for each of these states. In the so-called Mueller method (C. Hentschel and D. Derrickson in Fiber Optic Test and Measurement, ed: D. Derrickson, Prentice Hall, pp.356+, 1998), the PDL of the DUT can be calculated from the measured optical power transmission at linear horizontal (0°), linear diagonal (45°), linear vertical (90°) and right-hand circular polarization states only. Similarly, in the method developed by Williams (P. A. Williams, Electronic Letters, 36, 1578 (1999), the DGD of the DUT is derived from phase delay measurements at these four states only. Generally, a separate measurement is performed for each of the four polarization states.
Related solutions are disclosed in European publications EP 1191320A1 and EP 1207377A2.
A method allowing the determination of polarization dependent parameters in an interferometric approach by measuring only two orthogonal polarization states in two detectors simultaneously, has recently been proposed in European patent EP 1113250 and in a paper by Van Wiggeren (G. D. Van Wiggeren et al., OFC 2002 Technical Digest pp. 253). The invoked algorithm is based on the assumption that the DGD of the DUT is, to the first approximation, independent of wavelength.
One of the objects of the invention is to provide an apparatus and algorithm that allow the determination of both parameters, DGD and PDL, in a single wavelength sweep using a single detector without this approximation.

Polarization state frequency multiplexing

Abstract: The device for executing this method includes a Mach-Zehnder interferometer (M-Z) having a reference arm and a signal arm. In the signal arm, a device called a “polarization state frequency multiplexer” (PSFM) splits the light into four ports, transforms each part into one of four predetermined polarization states and then combines the light in the different polarization states together. The combined light is then passed through the device under test and combined/interfered with the light propagating through the reference arm at the output of the M-Z interferometer. Since the optical frequency of the input light to the M-Z interferometer is scanned through a range of wavelengths at a fixed repetition rate, the output light intensity (reference pattern) from the interferometer is modulated. By analyzing the M-Z interferometer output in the frequency domain, the signal levels of each polarization state can be identified and measured.


A wind turbine has a housing, multiple cross-flow fan assemblies, a turbine generator assembly, an air guide and multiple wind-driven fans. The housing has a chamber having top and bottom openings. The cross-flow fan assemblies are mounted on the housing and each has a casing, a cross-flow fan blade and a transmission shaft. The cross-fan blade rotates to provide airflow to the chamber. The turbine generator assembly is mounted in the chamber and has a generator, a generator shaft mounted on the generator and a turbine blade mounted on the generator shaft and driven by the airflow to activate the generator. The air guide is mounted on the transmission shafts and guides airflow outwards. The wind-driven fans are mounted respectively on the transmission shafts and are driven by outward airflow. The wind turbine derives energy from the airflow exiting out of the wind turbine for improved energy extraction efficiency.

1. Field of the Invention
The present invention relates to a turbine, and more particularly to a wind turbine that transfers external airflow to improve power generating efficiency.
2. Description of Related Art
Conventional wind power generators such as windmills and wind turbines have a generator and rotor. The rotor is connected to the generator and has cross-flow fan blades so that airflow over the cross-flow fan blades rotates the rotor and drives the generator.
However, the conventional wind power generators cannot utilize slow moving output airflow to fully derive kinetic energy therefrom.
However, conventional wind turbines are customized to remove a percentage of energy from the airflow according to average annual wind speeds. Therefore, during relative light wind, the wind turbine may not turn, or may turn too slowly to generate power and during high relative wind speeds, the airflow passes the wind turbine, but only transfers a relatively low amount of energy. Therefore, operating efficiency and annual generation time of the wind turbine is reduced.
To overcome the shortcomings, the present invention provides a wind turbine to mitigate or obviate the aforementioned problems.