An electrical supply or connecting terminal with a clamping spring and a metal part located in an insulating housing having a conductor inlet opening for an electrical conductor. The clamping spring has a clamping leg and a contact leg, and the clamping leg and the metal part form a spring force clamp connection for the electrical conductor. The contact leg of the clamping spring is arranged essentially perpendicular to the insertion direction of the electrical conductor and a recess is formed in the contact leg for insertion of the electrical conductor. The clamping leg and the contact leg of the clamping spring are bent toward one another with the end of the clamping leg extending through the recess. The metal part has at least one mounting section inserted through the recess of the clamping spring in a direction opposite the insertion direction of the electrical conductor.

1. Field of Invention
The invention relates to an electrical supply or connecting terminal with a clamping spring and with a metal part, the clamping spring and the metal part being located in an insulating housing which has an inlet conductor opening for entry of an electrical conductor which is to be connected, the clamping spring having a clamping leg and a contact leg, and the clamping leg and the metal part forming a spring force clamp connection for the electrical conductor to be connected.
2. Description of Related Art
Electrical terminal means or connecting means are used to establish an electrical terminal or electrical connection, specifically to produce an electrically conductive connection, a metallic connection, between a contact element and a mating contact element. Whether in the individual case there is a terminal means or a connecting means, is functionally relatively unimportant. It is often considered a terminal means when something locally movable is connected to something locally stationary, while often it is considered a connecting means when something locally movable is connected to something locally movable or even when something locally stationary is connected to something locally stationary.
The initially described supply terminal is known, for example, from German Patent Application DE 101 03 107 A1. In the known supply terminal, the metal part is made as a repeatedly bent contact element that has a first profile section which runs essentially perpendicular to the insertion direction of the conductor which is to be connected, with a plug opening for the conductor which is to be connected, and a second profile section which is bent away from it in the insertion direction. The clamping spring, is essentially U-shaped and projects with its clamping leg through the plug opening in the contact element so that the end of the clamping leg presses an electrical conductor which has been inserted into the plug opening against the second profile section of the contact element. The contact element and the clamping spring thus form a spring force clamp connection for an electrical conductor which is to be connected.
The clamping spring is connected to the contact element by the end of the second leg of the clamping spring being riveted securely to the contact element above the plug opening. In the known supply terminal, the fixing of the clamping spring to the contact element by means of riveting is comparatively involved. Moreover, the size of the known supply terminal is relatively large, in particular, the supply terminal is relatively tall since, by fixing the second leg of the clamping spring above the plug opening, the rear spring arc of the clamping spring is also located essentially above the approximately L-shaped contact element.
German Patent Application DE 196 54 611 A1 and corresponding to U.S. Pat. No. 5,975,940 disclose an electrical connecting terminal which also has an essentially U-shaped, open clamping spring and a conductor rail piece which is made as an angle bracket. The conductor rail piece has a retaining leg which is located perpendicular to the conductor entry direction, and a contact leg. In the retaining leg, a rectangular opening is formed through which the electrical conductor which is to be connected can be inserted. The U-shaped clamping spring, with the ends of its legs, is inserted and held in the opening such that the rear spring arc of the clamping spring in the conductor entry direction is located in front of the opening and the clamping leg of the clamping spring presses the inserted electrical conductor against the contact leg, so that, in this known plug-in connector, the clamping spring and the conductor rail piece also form a spring force clamp connection.
European Patent Application EP 1 391 965 A1 and corresponding U.S. Pat. No. 6,814,608 disclose a spring force clamp connection for an electrical conductor having a U-shaped clamping spring and a conductor rail piece. The conductor rail piece is made of a flat material and has a conductor insertion opening in the form of a rectangular material passage which has a perforated collar which extends in the conductor insertion direction and which together with the end of the clamping leg of the clamping spring forms the clamping site for the electrical conductor. In this conductor rail piece which is made as a flat current bar the clamping spring is inserted with the ends of its legs into the conductor insertion opening. When the clamping spring is opened, there is the danger that the clamping spring will slip or with the ends of its spring leg will even slip out of the opening so that proper positioning of the clamping spring, and thus, reliable contact-making of the electrical conductor, are no longer guaranteed under certain circumstances when an electrical conductor is being inserted.
Similar electrical supply terminals with an essentially U-shaped clamping spring and a metal part are known from German Utility Models DE 203 12 861 U1 and DE 202 10 105 U1. It is common to all these known supply terminals that the clamping spring is inserted in an opening of the metal part so that, when the clamping spring is opened, there is the danger that the clamping spring will slip.
In addition, loop-shaped clamping springs are also known in electrical supply or connecting terminals from the prior art, for example, from German Patent Application DE 197 11 051 A1 or German Patent DE 198 02 945 C2, specifically, as so-called tension springs in tension spring terminals. Tension spring terminals have become established on the market over time, in addition to screw terminals and recently also in addition to electrical terminals with insulation piercing terminal technology, and have been used millions of times especially as modular terminals. The advantage of tension spring terminals as compared to screw terminals consists in that the tension spring terminals enable faster and easier wiring. To actuate a tension spring terminal, only one actuating tool is necessary, for example, a screwdriver, which is pressed into the actuating shaft to open the terminal. In doing so, the tip of the screwdriver tensions the tension spring, by which the clamping site is opened. A conductor which is to be connected can then be inserted through the recess into the clamping leg, and it is clamped by the lower edge of the recess again a conductor rail which is connected to the tension spring after pulling out the screwdriver.
One special embodiment of a tension spring terminal is known from German Patent DE 35 14 099 C2 and corresponding U.S. Pat. No. 4,768,981. This tension spring terminal, besides a loop-shaped tension spring, has a specially made conductor rail with two lateral edges so that the conductor rail runs spaced apart from the contact leg of the tension spring. In this tension spring terminal, besides a connection of a flexible conductor in a recess in the clamping leg, in addition, a solid conductor can be pushed between the contact leg and the conductor rail. Since only a relatively small clamping force is applied to the solid conductor which is inserted into the terminal parallel to the contact leg and to the conductor rail, the electrical connection is very heavily dependent on the production tolerances and the diameter of the solid conductor.
One development of the tension spring terminal described directly above is disclosed by German Patent Application DE 199 03 965 A1. In this tension spring terminal, two electrical conductors can be inserted from the same side through the opening in the clamping leg, one conductor then being located underneath and one conductor being located above the conductor rail. The conductor which is located above the conductor rail is pressed against the conductor rail by the specially made contact leg of the tension spring.


An electronic device includes a central control unit and a waveguide device. The waveguide device includes a communication module having a communication function, and an attachment/detachment unit capable of attaching/detaching a high-frequency signal waveguide so that coupling between the module and the high-frequency signal is possible. The communication module includes a communication device, and a transfer structure configured to cause a high-frequency signal emitted from the communication device to be coupled to the high-frequency signal waveguide.

For example, when information is exchanged between semiconductor integrated circuits (ICs) within an electronic device, a connection is typically made using electrical wiring. As a technique of implementing high-speed signal transmission within the electronic device, for example, low-voltage differential signaling (LVDS) is known. However, with a recent further increase in the volume and speed of transmission data, increased power consumption, increased influence of signal distortion due to reflections and the like, increased unnecessary radiation, and the like, are problematic. For example, when video signals (including image signals) or signals of computer images or the like are transmitted at a high speed (in real time) within a device, LVDS has been reaching a limit.
In order to cope with the problems of the increased speed of transmission data, there is a method of increasing the number of wirings and parallelizing signals to reduce the transmission rate per signal line. However, this results in an increased number of input/output terminals. As a result, it is necessary to make a printed board or cable wiring more complex, increase the semiconductor chip size, and the like. Further, when high-speed/large-volume data is routed using wirings, so-called electromagnetic field disturbance becomes problematic.
All of the problems with the LVDS and the method of increasing the number of wirings result from the transmission of signals by electrical wiring. Therefore, as a technique of solving the problems resulting from the transmission of signals by electrical wiring, a technique of making electrical wiring wireless for transmission is proposed.
For example, as proposed in JP 2005-204221A and JP 2005-223411A, wireless signal transmission within a housing is performed and an ultra-wide band (UWB) communication scheme is applied.

Waveguide device, communication module and electronic device


This invention provides a molten salt, solar central smooth tube receiver that is able to effectively absorb a peak solar flux of 1.42 MW/M.sup.2 by constructing the receiver from low cycle fatigue 625 alloy. Although higher flux levels are attainable for a smooth tube receiver by reducing the tube diameter to increase the salt's heat transfer coefficient, the receiver's size is optimized at this flux level to minimize capital and performance costs. Analogously, material provides substantial performance and capital cost improvements for receivers constructed with internally enhanced film coefficient tubes. The receiver's cost is minimized by utilizing autogenously welded and drawn tubing with the weld located at the tube's neutral axis to provide minimal strain at the weld.

1. Field of the Invention
This invention relates to materials of construction for a solar central receiver and more particularly to the use of low cycle fatigue 625 alloy as the material used to fabricate a solar central receiver containing high temperature sodium-potassium nitrate salt as the heat transport fluid.
2. Description of the Related Art
Presently, materials used to contain 565.degree. C. sodium-potassium nitrate salt in solar central receiver applications include 304 and 316 austenitic stainless steels and Incoloy 800 nickel-iron-chromium alloy. This class of materials possesses: high coefficients of thermal expansion, low yield and creep strengths, low thermal conductivities, low thermal fatigue properties and are susceptible to chloride stress corrosion cracking. However, they do have; excellent salt corrosion resistant properties up to 600.degree. C., excellent weldability and fabricability, and are acceptable to the ASME Boiler and Pressure Vessel Code.
When used in a molten nitrate salt, solar central receiver the construction material for the solar absorption panel tubes should be: resistant to the molten salt's strong oxidation properties, resistant to chloride stress corrosion cracking, economically fabricated, weldable, acceptable to the ASME Boiler and Pressure Vessel Code and table to withstand the severe thermal strains caused by the through wall and across diameter temperature gradients. These strains, which are directly proportional to the material's thermal expansion coefficient, set the receiver's size by restricting the absorbed solar flux to a value determined by the material's allowable fatigue strain level for the imposed number of daily sun and cloud cover cycles over the receivers lifetime.
Because a receiver's radiation and convection thermal losses are directly proportional to its area and temperature distribution, a smaller receiver with equivalent temperatures has lower thermal losses. However, because the light reflected by the solar plant's sun collection field (heliostats) onto the receiver more easily misses a smaller receiver its light spillage losses are greater. Still, the reduction in thermal losses off-sets the light spillage losses except for very small receivers. Also, smaller receivers designed to achieve their reduced size by improved material properties, such as; a lower coefficient of thermal expansion combined with a greater thermal fatigue strength have lower fluid flow pressure losses and reduced capital costs because they have fewer shorter tubes of a diameter like the lesser material's larger size receiver.

Molten nitrate salt solar central receiver of low cycle fatigue 625 alloy


The present invention is an emplacement stand for holding explosive ordnance disposal tools that comprises a support base having tapered pegs evenly spaced around the outside of the support base extending outward at a downward angle. Detachable legs may be attached to the tapered pegs or each other to increase the height of the support base. A pivot arm slides through a hollow bearing ring within the support base and a set screw connector locks the pivot arm into a specific desired position after moving the pivot arm up or down within the support base. A pivot base, having a tool cradle connected to a disc shaped surface attaches to a clevis slot within the pivot arm through a pin that allows the disc shaped surface to freely pivot about the pin within the slot. A second set screw connector locks the disc shaped surface into place within the clevis slot. An explosive ordnance disposal energetic tool, countermeasure or warhead system of various shapes and geometries may then be placed and clamped into the tool cradle.

1. Field of the Invention
The present invention pertains to an inexpensive, disposable emplacement stand for orienting energetic tools, on a variety of surfaces and terrains, for precision targeting. More particularly, the present invention pertains to a device to: (a) orient a variety of energetic countermeasure tools for rendering safe or disrupting Unexploded Ordnance (UXO) and Improvised Explosive Devices (IEDs), and (b) orient offensive directed effects warhead/weapon systems.
2. Brief Description of the Prior Art
Disposing of unwanted UXO under military operational field conditions requires the ability to respond quickly and safely to threats under a myriad of different conditions. Numerous specialized countermeasure tools are used to neutralize the explosive main fill, to disrupt the firing train (i.e., disarm), or to detonate UXO and IEDs. The sizes and shapes of these countermeasure tools vary depending upon the mission, however, the emplacement of the tools is critical, particularly during a surgical render safe procedure used to disrupt the firing train of UXO and IEDs.
Currently explosive ordnance disposal (EOD) countermeasure tools are placed in their proper position by either developing tool-unique adapters to interface an EOD tool to a commercial stand items or by fashioning an emplacement device using a combination of materials available to EOD personnel. Placement stands for certain types of commercial items, such as camera tripods, have been tested or used for EOD tool placement with limited success. One popular design is a reasonably inexpensive, tripod with a ball and socket joint. This device has a thumbscrew that can be used to tighten the ball against the socket to avoid movement once positioned. However, this stand, like other commercial stands, has several limitations for use in emplacing EOD countermeasure tools. The ball and socket is set at a predetermined height limiting the range of direct targeting. Also, locking in on the precision targeting of an EOD tool using a freely rotating ball joint is cumbersome and time consuming.
Generally, commercial stands are rather bulky and heavy, are not designed to hold the diverse range of available EOD tools without significant modification, pose undo safety risks to the EOD operator due to poor balance of the tool on the stand, have a limited range of motion and adjustment capability to accommodate undulating terrain, are not designed to provide ready access to some potential threat targets, and require adapters to interface EOD tools with the commercial stand. The majority of the commercial stands also are comprised of metal components, which could result in potentially dangerous fragments upon initiation of the EOD energetic tools. While certain commercial stands have been designed to provide relief from some of the shortcomings listed above, they are generally too heavy and expensive, having not been designed to be consumable, and, therefore, are not practical alternatives for placement of EOD countermeasure tools.
Field fashioned stands may pose an undo safety risk to the EOD operator by exposing the EOD technician to an explosive event if the field fabricated stand tips over or structurally collapses due to a poor design, high winds, and deterioration of the fastening systems (for example, duct tape) under harsh environments, such as precipitation, extreme temperature, and salt fog.
Due to the above limitations with commercially available stands and field fashioned stands, EOD personnel often rely upon placement EOD tools using sandbags. Sandbags are fabricated on-site and stacked up to the proper height. However, application of this technique poses a potential for non-symmetrical tamping of explosive EOD tools, and thus potentially affects the tools"" ability to disrupt a threat target. Also, most EOD procedures require precision placement of a tool and accomplishing this with sandbags is extremely time consuming and hazardous. Any procedure which requires EOD personnel to be exposed to UXO or IEDs for long periods of time unnecessarily exposes the personnel to the risk of these threats functioning (detonating) as designed. Employing EOD tools using sandbags has the same limitations as field fashion stands. Sandbags take time to fabricate and they limit the range of motion and adjustment capability available to the EOD operator.
Due to the limitations of the current technology described above, a device is required by the military to support and precisely position EOD tools in order to neutralize, disrupt or render safe unexploded ordnance (UXO) and Improvised Explosive Devices (IEDs). To accomplish this mission, the present invention was developed. In general, the device comprises an emplacement stand to clamp explosive or propulsive energetic EOD tools, countermeasures or warhead systems of various shapes in a cradle, whereby the cradle may be adjusted vertically, horizontally, and angularly (in three dimensions) in order to carry out multiple mission requirements.
Preferred embodiments of the device should also be easily transportable in a collapsed condition for compact storage so that EOD personnel may easily use the device in numerous locations. The preferred embodiments of the device readily accommodate the emplacement of said device on undulating terrains and requires little time to assemble, setup, and deploy. The preferred embodiments are manufactured using plastic injection molded techniques which provides an inexpensive device if procured in large quantities.
Accordingly, it is an object of this invention to support and position EOD tools for use to disrupt or render safe unexploded ordnance (UXO) and Improvised Explosive Devices (IEDs).
It is a further object of this invention to be transportable in a collapsed condition for compact storage.
It is further the object of this invention to accommodate the emplacement of said device on undulating surfaces and terrains.
It is further the object of this invention to be of such a design as to accommodate plastic injection molded manufacturing techniques to provide an inexpensive device if procured in large quantities.
This invention accomplishes these objectives and other needs related to the support and positioning of EOD tools.

The United States of America as represented by the Secretary of the Navy


A support structure to aid in the creation of a corner joint between two planar perpendicularly-situated workpieces. The support structure of the invention consists primarily of a horizontal and vertical support surface, with the vertical support surface displaced from the horizontal surface and separated therefrom by a clearance area, such clearance area designed to accommodate excess material present at the formation of the corner joint between the two workpieces. The support structure of the invention may be used to create a single corner joint, or a second support structure may be implemented in conjunction with the first support structure to simultaneously create multiple corner joints. A variety of clamping and fastening implements are disclosed to maintain the workpieces attached to the support structure.

1. Field of the Invention
The present invention relates generally to jigs for use in the woodworking industry, and more particularly, to a multi-purpose jig which provides a right-angle foundation against which two workpieces may be clamped and joined together to form an exact corner joint between the two workpieces.
2. Preliminary Discussion
Carpenters, woodworkers and the like comprise some of the most creative minds when it comes to problem solving. There is a reason these people are often associated with the term "handyman," or "handywoman" as the case may be, since they often strive to find the easiest and most efficient way to do things. Woodworkers, in general, are always creating specialized tools, devices, gadgets, and such, to fulfill a specific need, or meet a specific condition.
A "jig", defined as a device for guiding a tool or for holding machine work in place, carries a much broader connotation in the woodworking industry. Often characterized as a handyman's helper, it provides a user with the ability to produce results not ordinarily accomplished by hand, such as, for example, using a power saw to make a perfect 45.degree. cut. Jigs are primarily used or thought of as work holders, either holding the workpiece in a semi-permanent fastening arrangement, or temporarily guiding the workpiece as it is operated or worked upon, usually by the use of a saw, lathe or the like.
Holding multiple planar objects in a 90.degree. relationship to each other, whether it be to produce a simple two-piece corner, or a four-walled box structure, often involves the implementation of multiple clamping structures and multiple clamping surfaces to accommodate both the workpieces and such clamping structures. Prior art structures that have been developed to aid in the fastening together of multiple planar objects are generally more complicated than they need to be. Multiple clamps, as well as multiple clamp holders, are usually necessary to effectuate a proper hold, and this may require a fair amount of manipulation on the part of the user, as well as a fair amount of working space needed to accommodate such devices.
The creation of a corner joint between two planar workpieces requires a certain amount of skill, not only in the placement of the support members, but in the actual preparation and design of the workpieces which results in the corner joint. Slapping two pieces of wood together with some glue and a couple of screws may be enough for the novice carpenter. The experienced craftsman, however, often demands a greater attention to detail, and the production of a "clean" corner joint, especially when producing cabinetry and the like, is a true art form. The objective in producing a clean corner joint is to create the appearance of a single continuous piece with a single grain, and not to have an obvious seam indicating the junction of two dissimilar pieces. One way to produce a clean corner joint is to cut a "seat" in one piece, into which the other piece will be glued into place, such that, if the objects are pieces of wood, the surface grains of the two pieces will meet at the corner, as opposed to the edge grains, so that once the corner is finished off, it will appear like one continuous grain piece. The creation of the "seat" is done by slicing out a strip along the edge of the first joined piece, and housing the edge of the second piece against such strip with some glue therebetween, such that the edge of the second piece is hidden by the strip of the first piece. This "housing" often results in a surplus of material extending beyond the location where the second piece is introduced, which surplus is then removed and the corner joint is subsequently finished and polished. Consequently, when two perpendicularly-situated planar objects are fastened together at a 90.degree. angle in this fashion, there is a need to not only provide the actual perpendicular support, but to accommodate the initial surplus of material extending from one of the pieces when forming a joint of this type. A corner joint of this quality usually involves multiple support surfaces and multiple clamping arrangements upon such support surfaces.
The present inventor, who has been intimately associated with the use of various supporting and clamping devices, has ascertained a need, and has designed a simple device, which easily, efficiently and in an uncomplicated manner, provides the support structure to produce quality corner joints with the least amount of tools. The present inventor has consolidated and reduced the unwieldy concepts underlying the prior art devices into a one-piece support device which is superior to the prior art in both function and form. The simplicity and effectiveness of the device of the present invention readily distinguishes it from the prior art.
3. Description of Related Art
The clamping and securing art, and more particularly, the devices or tools used to achieve planar 90.degree. corners, has followed or undergone an interesting evolution. The joining together of perpendicularly-oriented planar objects in a secured fashion often involves the necessity for the use of multiple tools, usually one to support the horizontal object, one to support the vertical object, and another device to maintain such objects in a secured arrangement. The prior art is, in fact, replete with clamps, vices, angles, "T"-squares and the like. However, there is no device which addresses the particular concerns of the present inventor, that is, to provide a simple device with which to produce quality corner joints.
The evolution of such clamping and securing devices has exhibited a relatively static or slow progression, and the present state of the art is not that far removed from those devices patented around the turn of the century. One of the earliest two-dimensional joining devices is disclosed in U.S. Pat. No. 600,370 issued to A. Kohler on Mar. 8, 1898 entitled "Miter Clamp." The Kohler reference discloses a more or less conventional miter clamp, which is used to aid in securing two ends of mitered molding in place during the fastening process. The Kohler reference demonstrates a device which is used to join two perpendicularly positioned pieces of material extending along the same plane using a pair of clamps integrated along the device. A miter clamp is functional when creating a corner joint from two similarly-situated planar objects as disclosed by the Kohler reference. However, such clamp is non-functional when such planar objects are not similarly-situated, i.e. are perpendicular (90.degree.) or at some other angle along an extended joint. A three-dimensional joint often requires a more sophisticated tool or instrument which is capable of providing the necessary support along all such dimensions.
U.S. Pat. No. 683,184 issued to J. P. Rockwell on Sep. 24, 1901 entitled "Clamp", discloses a four-member clamp with adjusting screws in all four directions and provides for a variety of fastening and clamping applications. This particular reference addresses multi-dimensional clamping, and illustrates some of the basic concepts that underlie the most sophisticated clamping devices of today. The Rockwell device utilizes the compression of multi-dimensional oppositely-driven vice members connected by screw means to create the necessary support. Contemporary clamps all follow a similar basic principle, with the only real difference being in the manufacture of the housing for the clamping and screw-driven elements. Whether it be a "C" clamp, bar clamp, or the like, the necessary elements are nearly always the same, i.e. a pair of oppositely-situated compression members, a track or support upon which such compression members move, and means by which such members are brought together or extended apart.
Clamping devices and the like will only work if the support surface is amenable to the workpieces, or the objects to be clamped and/or joined together. For example, clamps to aid in the creation of a 90.degree. corner joint between two perpendicular planar objects must be provided with a perpendicular foundation, or the clamps will lack the necessary support to maintain the perpendicular relationship. U.S. Pat. No. 2,461,733 issued Feb. 15, 1949 to C. J. Stark entitled "Gauge for Collocating Pipe Sections," is an example of a perpendicular support specifically designed to accommodate a particularly shaped workpiece. The Stark reference shows a pipe flange gauge with an offset in the gauge to accommodate the side extensions of such pipe flange. The Stark arrangement for providing a three-dimensional perpendicular support illustrates a desirable feature for such device, namely an offset portion to accommodate the flange of a pipe coupling. Such offset portion is two-dimensional rather than three-dimensional as in the present applicant's invention, where an extended intersection between two right angularly connected guide members is an integral feature to the device, and such offset distinguishes both the Stark device and the device of the present invention from a mere 90.degree. angled support structure (an angle plate). The three-dimensional offset feature of the jig device of the present invention is designed specifically to accommodate an extension or surplus of material usually found on one of the two perpendicularly-situated planar objects that are to be joined together to form a corner joint.
U.S. Pat. No. 2,761,476 issued to P. J. Gunas on Sep. 4, 1956 entitled "Adjustable Corner Clamp", discloses a conventional corner clamp adjustable along its base to accommodate varying workpiece widths. The Gunas reference is more akin to the previously discussed Kohler reference, than to the device of the present invention, since it joins two workpieces along a miter cut arrangement and operates in a single dimensional plane.
A perpendicular angle plate is shown in U.S. Pat. No. 2,835,978 issued to F. Krisel on May 27, 1958 entitled "Double Face Angle and Set Up Plate." The Krisel reference discloses an angle plate with handles, forming a perfect 90.degree. angle with a variety of applications. The walls of the plate are raised to accommodate exterior fixation means, such as clamps, and a cylindrical clearance recess is provided where the interior walls meet. The Krisel device is in essence a mere angle plate with means for easily toting such plate, and the cylindrical recess formed between the two plates does not approach the function of the recess area provided in the device of the present invention. Even if the Krisel apparatus were to be implemented in the creation of corner joints in the field of cabinetry and the like, the clearance recess of the Krisel device would not provide the necessary space to accommodate the overhang of a glued corner joint.
U.S. Pat. No. 3,363,377 issued to M. H. Beckman on Jan. 16, 1968 entitled "Metal Intersection Stud", discloses a connection device for interior and partition walls, such device being used to join two corners together in a parallel arrangement. The channel section of the Beckman device maintains a first wall section in perpendicular arrangement with a second wall section, with such wall sections positioned to permanently overlap in order to fit within the stud and to provide enhanced stability at the corner joint. Two recessed sections are opposed in the Beckman arrangement to provide a reinforced overlapping intersection joint. The recess area in the device of the present invention, on the other hand, is provided to accommodate and reinforce a temporary overlap of two joined workpieces, which need not fill the offset as in Beckman, and therefore, there is no functional similarity between the device of the present invention and the Beckman device, and the only structural similarity is the cross-sectional shape of one side of the Beckman design.
U.S. Pat. No. 3,914,871 issued to R. Wolff on Oct. 28, 1975 entitled "Doweling Boring Gauge for Two Workpieces to be Dowelled Together on Their Front Flat Sides", discloses an alignment clamp system for the creation of boring holes along the corner of two joined workpieces into which will be placed dowel connections. The clamping system maintains the two workpieces in a perpendicular arrangement while the holes are drilled into the workpieces, with one clamp being longitudinally moveable along the length of the corner while the other clamp is fixed to a workbench, table or the like, and the resulting workpieces may be joined to form a corner with precise dowel connections. The device of the present invention is a corner joint facilitator, while the Wolff device is a corner joint preparer and does not actually assist in the joinder of the two perpendicularly situated workpieces. Wolff does have a similar offset arrangement on his clamps to accommodate overlaps on two intersecting sections of a corner joint.
U.S. Pat. No. 4,138,819 issued to G. J. Sosin on Feb. 13, 1979 entitled "Outside Corner Square", discloses a corner square with a clearance area for irregular, non-smooth corner joints. The measurement and squaring of outside corners requires a device with a similar recess area to accommodate such outside corners and the like, and therefore, the cross sectional design between the Sosin square and the device of the present invention are somewhat similar. The Sosin design employs a recess area in the vertical and horizontal planar directions. However, the preferred device of the present invention requires a recess area in only one planar direction. The Sosin device is essentially constructed as a two-dimensional device while the device of the present invention is essentially a three-dimensional device. The functions of the two-dimensional Sosin measurement device and the planar three-dimensional support device of the present invention are also completely different.
U.S. Pat. No. 4,209,164 issued to A. O. Brothers on Jun. 24, 1980 entitled "Tool for Use in Constructing Paneled Ornaments", discloses an angled jig for the connection of three-dimensional workpieces at obtuse angles. The Brothers reference does not demonstrate a clearance area to accommodate an irregular corner or an overhang or excess material, although it does demonstrate the joinder of planar workpieces at an adjustable angle.
U.S. Pat. No. 4,300,754 issued to B. N. Lawrence on Nov. 17, 1981 entitled "Welding Clamp", discloses a clamp for maintaining an angle member in a perpendicular relationship with a flat plate upon which the angle member is to be welded. The Lawrence clamp could not be used to form a corner joint in the same manner as the device of the present invention between a vertically and horizontally situated workpiece because the Lawrence clamp assumes that the workpiece is already in the form of an angle, and therefore, does not provide the proper support to accomplish such task. The Lawrence clamp also does not provide a recess area, which is critical to the formation of such joints.
U.S. Pat. No. 4,361,964 issued to J. W. Hennessee on Dec. 7, 1982 entitled "Lay Out Square", discloses a folding square for laying out the location of tees and corners as shown in the figures of the reference patent. The Hennessee reference demonstrates a conventional square device and does not provide a clearance area as previously mentioned and discussed.
One of the most recent devices designed to position angularly situated workpieces is U.S. Pat. No. 5,360,212 issued to J. West on Nov. 1, 1994 entitled "Jointing Jig." The West reference discloses a hinged jig with angularly positioned channels for the placement and connection of a variety of angularly situated beam-like workpieces. The West reference does not provide elongated planar support surfaces necessary for the joining of planar workpieces in a corner relationship, as provided for in, and is necessary with, the device of the present invention.
Another recent device, U.S. Pat. No. 5,456,015 issued to R. L. Butcher on Oct. 10, 1995 entitled "Construction Framing Square", discloses a device which is similar in design to the previously mentioned Hennessee '964 reference, and this being so, is only similar to the device of the present invention in its profile, not function. The Butcher reference could not accommodate a corner joint situation since it lacks the clearance area necessary to form a corner joint.
Design U.S. Pat. No. 346,225 issued to J. C. Bancroft on Apr. 19, 1994, entitled "Exterior Trim," discloses an extruded exterior trim section having a recess at the intersection of two right angularly related flanges. The section is designed for use as exterior trim rather than a jig or tool and, in any event, the two flanges are not precisely at right angles, so the device could not be used in the same manner as applicant's device.
The prior art has yet to exhibit a handyman's tool which will facilitate the efficient creation of a smooth, accurate corner joint, in the demandingly accurate manner prescribed and expected by a skilled craftsman. The present inventor, frustrated by such a deficiency in the prior art, has recognized a need to fill this void, for both the benefit of himself and those skilled in the art. The prior art devices in the clamp, jig, and vice classifications have been fairly static in functional evolution over the years, with their mechanical operation changing only slightly. The one-piece support device of the present invention is, however, so simplistic, in light of the large number of prior art devices which have merely grown more complicated over time without a proportional increase in efficiency of function, that one skilled in the art will readily recognize such innovation as being clearly unobvious in the art particularly in light of the trend toward complexity in the art. The novel jig device of the invention is in fact of such increased efficiency in the facilitation of the production of neat, accurate corner joints as to be a major advance in the art.


A low-cost alignment system suitable for aligning a wafer to a test fixture includes a bundle of optical fibers wherein at least one fiber serves to deliver illumination to the alignment target from an end thereof, and a plurality of receiver fibers, each having ends with a known spatial relationship to the end of the illuminator fiber. The ends of the fiber bundle have a known spatial relationship to the fixture. In some embodiments, the fiber bundle is disposed within the fixture such that there is an unobscured optical path between the wafer and the receiving and illuminating ends of the fibers. In some embodiments, the fiber bundle is coupled to a light source and a light sensor mounted on the fixture. In some embodiments the alignment target is one or more bonding pads disposed on a wafer.

Advances in semiconductor manufacturing technology have resulted in, among other things, reducing the cost of sophisticated electronics to the extent that integrated circuits have become ubiquitous in the modern environment.
As is well-known, integrated circuits are typically manufactured in batches, and these batches usually contain a plurality of semiconductor wafers within and upon which integrated circuits are formed through a variety of semiconductor manufacturing steps, including, for example, depositing, masking, patterning, etching, implanting, annealing, planarizing and so on.
Completed wafers are tested to determine which die, or integrated circuits, on the wafer are capable of operating according to predetermined specifications. In this way, integrated circuits that cannot perform as desired are not packaged, or otherwise incorporated into finished products.
It is common to manufacture integrated circuits on roughly circular semiconductor substrates, or wafers. Further, it is common to form such integrated circuits so that conductive regions disposed on, or close to, the uppermost layers of the integrated circuits are available to act as terminals for connection to various electrical elements disposed in, or on, the lower layers of those integrated circuits. These conductive regions are typically referred to as pads. In testing, these pads are commonly contacted with a probe card. Unfortunately, the dimensions, or area, of pads have been decreasing which makes contacting such pads with a conventional probe card difficult and time consuming.
What is needed are lower-cost, less-complex apparatus and methods to increase the efficiency of operations associated with testing the integrated circuits of a wafer.


A fabrication of a capacitor in a semiconductor is simplified by using nitrogen plasma in forming an aluminum nitride layer functioning as an insulation layer on the aluminum layer disposed in a capacitor region. Subsequently, a planarized IMD (inter-metal dielectric) layer is obtained, facilitating via etching process.

Integration density of a memory cell in a semiconductor device is on the rise due to growing demands for higher capacity. In case of a memory cell in DRAM, which includes a MOS transistor and a capacitor, higher integration density thereof results in a reduction of capacitor region. Consequently, as the area of the capacitor is reduced, the electrostatic capacity thereof is also reduced.
As current state of the art, Ta2O5 (tantalum pentaoxide) or Si3N4 (silicon nitride) has been conventionally used for its high dielectric constant in fabricating capacitors in semiconductors. Recent growth in demands for dielectric material having higher dielectric constant has been reflected in the field of research in developing capacitors yielding high capacitance at a low voltage. In case of DRAM having a high integration density, since it is important to reduce the area of a capacitor, many studies have been done to replace Ta2O5 and Si3N4 with materials such as BST (barium strontium titanate), PZT (lead zirconium titanate) and PLZT (lead lanthanum zirconate titanate) having high dielectric constant.
Further, in an effort to increase the integration density, a trench type capacitor is used in DRAM whereas a stack type capacitor is used in system integrated circuits, which has relatively fewer limitations in terms of the area and voltage requirement, compared to DRAM. However, the system integrated circuits require higher standards in quality in uniformity and frequency dependence than that of DRAM.
However, in order to obtain stable characteristics of the capacitor in a device, e.g., a system integrated circuit, rather than having such a highly dielectric material, it is preferable to use silicon oxide or silicon nitride having an adequate dielectric constant, thereby providing chemical stability. Since spatial limitations are less of a concern in the system integrated circuit than DRAM, adjusting the area of the capacitor or the distance between layers thereof can suitably control its capacitance.
FIG. 1 shows a cross-sectional view of a conventional capacitor in a system integrated circuit.
In a typical capacitor structure, as shown in FIG. 1, an aluminum layer 100 and a TiN layer 102 are sequentially deposited and patterned into bottom electrodes on a substrate 98, which includes MOS transistors (not shown) or the like, and an IMD (inter-metal dielectric) layer 104 is formed on the exposed substrate and the TiN layer 102. Thereafter, via holes 106 and 108 are formed, and are then filled with a conductive material, e.g., W.
Subsequently, a metal-insulator-metal (MIM) stack structure is obtained by sequentially depositing bottom metal layers 110 and 112, an insulation layer 114, and a top metal layer 116. The bottom metal layers 110 and 112 are made of about 3000–10000 Å thick Al and about 600 Å thick TiN, respectively, and formed by sputtering. The TiN layer 102, 112 and 116 also serves as anti-reflection layers as well known in the art. The insulation layer 114 is formed of a silicon nitride fabricated by CVD (chemical vapor deposition) and has a thickness of about 300–600 Å. The top metal layer 116 has a thickness of about 1000 Å.
Thereafter, the insulation layer 114 and the TiN layer 116 are photolithographically defined and patterned to form the capacitor forming region, and then the Al layer 110 and the TiN layer 112 are defined and patterned in the same manner described above. Thereafter, a planarized IMD layer 118 is formed on the structure thus treated.
Subsequently, via holes 120 and 122 are formed and then filled with a conductive material, e.g., W, and thereafter first and second metal lines 124-1 and 124-2 are formed on top portions of the via holes 120 and 122.
The conventional capacitor described above suffers from certain drawbacks. First, the capacitor structure requires rather complex film forming and patterning processes and therefore is costly. That is, the structure necessitates the formation of the TiN layer 112 serving as an ARC (anti-reflective coating) layer, Si3N4 layer 114, and the top capacitor electrode 116.
Consequently, there occurs a great deal of non-uniformity in the thickness of the IMD layers deposited on the capacitor region and the remaining regions, which has an adverse effect on the planarization of the IMD layer and the via etching process. Further, the conventional MIM capacitor structure described above is produced by two etching steps: i.e., one for the layers 116, 114 and the other for the layer 112, thus generating a step between the layers 112 and 114 at which etching residues may be collected, which in turn contributes to the generation of leakage current and deteriorates the characteristics of the capacitor.

Capacitor and fabrication method thereof


A customer service machine, such as a self check-out terminal, includes a visual indicator and a proximity sensor associated with certain functional components or stations of the terminal, such as itemization, bagging and payment stations. The visual indicator is configured to provide a visual signal to either encourage or deter customer activity at the particular station, depending upon whether any activity is required to further a transaction being conducted at the terminal. The proximity sensor at each station determines whether the customer is about to take action at that station. A controller determines whether the action is appropriate, and if not activates the visual indicator to deter such action, or if so activates the visual indicator to encourage such action. In one embodiment, the visual indicator includes a red light that is illuminated to deter action and a green light that is activated to encourage action.

In the retail industry, labor is the number one expense after cost of goods sold. Employees working as "checkout personnel" or "cashiers" are the single largest category of labor. This is particularly true for those retailers in the food segment. On average, the retailer must have three or more cashiers trained for every checkout lane in a food store.
One problem for retailers is the cost associated with the recruiting, hiring, training, scheduling, managing, etc. of cashiers. This cost is exacerbated in that turnover in the food segment can easily exceed 100% annually, especially in metropolitan areas. It is not uncommon for food retailers to have significantly fewer cashiers on hand in a retail establishment than is optimally required. The constant recruiting, hiring, training, and scheduling of cashiers customers leads to significant management time and expense. Scheduling alone can make or break a retailer's performance on any given day and significantly impact customer service. By scheduling too many cashiers, the retailer has excess capacity and a higher cost of sales for the day. By scheduling too few cashiers, checkout queues grow long with angry customers who may not return due to poor customer service. Other customers may enter the store and go elsewhere due to the long lines. Checkout problems are typically the leading customer dissatisfaction issue for retailers.
Self Checkout (SCO) Terminals offer benefits to both the retailer and the customer. For the retailer, SCO terminals reduce the retailer's need for cashiers, thereby reducing the costs associated with them. Since SCO terminals are rarely closed, the job of predicting and scheduling cashier demand is made easier. For the customer, SCO terminals offer the perception of faster checkout, privacy, control, etc., and a significantly enhanced shopping experience.
Typical SCO solutions have adapted the technologies used in other customer service arenas, such as automated teller machines, bill paying kiosks and the like. In many cases, these customer service machines are perceived as lacking support for the customer throughout the transaction. In the case of an SCO system, the retailer must keep a cashier or clerk on hand to assist customers having difficulty navigating their way through a self-service checkout. In the case of other types of customer service machines, human assistance may be unavailable, leaving the customer no choice but to abort an attempted transaction when problems are encountered.
In using a typical SCO terminal the customer scans individual items for purchase across a scanner and then places the scanned item into a grocery bag, if desired. The customer then pays for his or her purchase either at the self-service checkout terminal if so equipped, or at a central payment area which is staffed by a store employee. Thus, SCO terminal permits a customer to select, itemize, and in some cases pay for his or her purchase without the assistance of the retailer's personnel.
However, a customer typically has little or no training in the operation of an SCO terminal or other types of customer service machines. One concern that retailers have when evaluating an SCO terminal is the level of supervision provided to inexperienced customers. Another concern is that a customer may attempt to shortcut a transaction when problems are encountered, resulting in irregularities in the transaction. A mutual concern for SCO terminals as well as unattended customer service machines is that customer frustration will lead them to abandon the self-service features and insist on conducting their transactions before a live cashier, clerk or teller. This frustration is felt not only by the customer having trouble completing a transaction, but also by other customers waiting in line for access to the customer service machine.
Most customer service or self-service machines include a screen which displays instructions intended to guide the customer through the transaction. Some displays include a picture or simulation of the necessary activity. Nevertheless, in spite of the comprehensiveness of the visual display, customers will still make errors or become intimidated of frustrated. What is needed therefore is customer service machine, such as an SCO terminal, which assists or otherwise interactively guides a customer in the use machine.

Self-guiding interface for customer service machines


The present invention relates to an arrival direction estimation method using an array antenna and a DS-CDMA receiver unit using this method. The method produces an accurate estimate of the arrival direction of a desired signal regardless of reception level and high interference. In a DS-CDMA communication system for performing a transmission by a spreading process using a code having a period longer than a symbol length, received signals from an array antenna are subjected to a despreading process by despreading units. A cross-correlation function with time lags of the recieved signals is obtained by inverse-modulating despread output signals by a known symbol in an inverse modulator. An arrival direction of a received signal is estimated by an arrival direction estimation unit based on the cross-correlation function. A beam former combines the despread output signals depending on the arrival direction and outputs an output signal to a channel receiver.

The present invention relates to an arrival direction estimation method using an array antenna for estimating an arrival direction of a desired signal. The present invention further relates to a DS-CDMA receiver unit in a Direct Sequence Code Division Multiple Access (DS-CDMA) system.
In a base station of a DS-CDMA communication system, signal reception is performed by utilizing an array antenna. Further, an arrival direction of a desired signal is estimated from signals received from the array antenna. By transmitting and receiving in a beam directed in the estimated arrival direction, it is possible to reduce both interference and required transmission power due to an increase in antenna gain. Therefore, it is desirable that the arrival direction of the desired signal is estimated accurately.
FIG. 7 is a diagram showing a receiver unit of a base station using an array antenna. In particular, FIG. 7 shows array antenna elements 71-0 through 71-(Mxe2x88x921) forming a receiving antenna, reception processors 72-0 to 72-(Kxe2x88x921), despreading units 73-0 to 73-(Mxe2x88x921), beam forming unit 74, a channel receiver 75, an arrival direction estimation unit 76 and a beam former 77.
Received signals r(0) to r(Mxe2x88x921) from the array antenna elements 71-0 to 71-(Mxe2x88x921) are input to the reception processors 72-0 through 72-(Kxe2x88x921) corresponding to the different channels. In addition, the reception processor 72-0 carries out a despreading process with respect to the received signals by the despreading units 73-0 to 73-(Mxe2x88x921), which are input with a spreading code C0. The despreading units 73-0 to 73-(Mxe2x88x921) provide despread output signals x(o) to x(Mxe2x88x921) to the arrival direction estimation unit 76 and the beam former 77 of the beam forming unit 74. The arrival direction estimation unit 76 estimates an arrival direction of a desired signal based on a cross-correlation function among the received signals received by adjacent antenna elements.
The beam former 77 multiplies a weighting coefficient obtained by estimating the arrival direction by the arrival direction estimation unit 76 to the despreading output signals x(0) through x(Mxe2x88x921). Further, the beam former 77 then combines the products to provide an output signal to the channel receiver 75.Therefore, received data of the kth channel is re-generated by the reception processors 72-0 to 72-(Kxe2x88x921) corresponding to channels 0 through Kxe2x88x921.
FIG. 8 is a diagram showing a conventional beam forming unit 74 including the arrival direction estimation unit 76. In particular, FIG. 8 shows the beam forming unit 74 including an arrival direction estimation unit 76 and a beam former 77 having multipliers 78-0 to 78-3 and an adder 79.
Received signals x(0)(n) to x(3)(n) from the antenna elements 71-0 to 71-3 (refer to FIG. 7) are input to the arrival direction estimation unit 76 and the beam former 77. The arrival direction estimation unit 76 outputs to the beam former 77 weighting coefficients a0 to a3 obtained by the estimation of the arrival direction of the desired signal. The weighting coefficients a0 to a3 are respectively input to the multipliers 78-0 to 78-3 of the beam former 77 to be multiplied with signals x(0)(n) to x(3)(n) and then coherently summed by the adder 79. An output signal y(n) of the adder 79 is then input to the channel receiver 75 (refer to FIG. 7).
FIG. 9 is a diagram showing a conventional arrival direction estimation unit. In particular, FIG. 9 shows an arrival direction estimation unit 76 including correlation calculators 81-0 through 81-2, an adder 82, and an array weighting coefficient calculator 83. A correlation calculator 81 is shown in the lower part of FIG. 9, wherein each of the correlation calculators 81-0 to 81-2 include a multiplier 84 and an averaging filter 85. Further, received signals x(m)(n) and x(m+1)(n) from mth and (m+1)th adjacent antenna elements are input to the multiplier 84. In this case, one of the received signals is a complex conjugate (indicated by *), and a complex conjugate product between the received signals from the adjacent antenna elements (cross-correlation function of the zero lag) is obtained. A temporal average is also performed by the averaging filter 85 so that a cross-correlation function R(m) is output.
A received signal r(m) (t) from a mth antenna element at a time t satisfying (nxe2x88x921)Txe2x89xa6t less than nT is described by the following formula (1), where xc3x8i(m) for I=0 to Nxe2x88x921 in formula (1) is described by formula (2), N denotes a number of users, Ai denotes a received amplitude of an ith user signal, ci (t) denotes a spreading code of the ith user, xcfx84i denotes a relative delay of the ith user, bi denotes an ith user transmission symbol, d denotes a distance between the antenna elements, xcex8i denotes an arrival angle of the ith user signal, N(m)(t) denotes a noise signal, T denotes a symbol length, and a multipath is not taken into consideration for the sake of convenience.                                           r                          (              m              )                                                      xe2x80x83                                          (            t            )                          =                                            ∑                              i                =                0                                            N                -                1                                                                xe2x80x83                                                                  A                i                                                          xe2x80x83                                                          c                i                                                          xe2x80x83                                                          (                                  t                  -                                      τ                    I                                                  )                                                          xe2x80x83                                          b                                            xe2x80x83                                                          (                                  t                  -                                      τ                    i                                                  )                                                          xe2x80x83                                          exp                                            xe2x80x83                                                          (                                                      -                    j                                                                          xe2x80x83                                                                          φ                                          (                      m                      )                                                                      )                                              +                                    N                              (                m                )                                                                xe2x80x83                                                  (              t              )                                                          (        1        )                                          φ          i                      (            m            )                          =                  2                                xe2x80x83                              π                                xe2x80x83                              md                                xe2x80x83                              sin                                xe2x80x83                                          θ            i                                              (        2        )
A despreading output signal x(k)(m)(n) which is obtained by subjecting the received signal r(m) (t) from the mth antenna element to a despreading process by the spreading code c(k) (t) of the kth user is described by the following formula (3), where wij(n) in the formula (3) is described by the formula (4).                                                                                x                  k                                      (                    m                    )                                                                                xe2x80x83                                                                  (                  n                  )                                            =                              xe2x80x83                                                                            ∫                                                            (                                              n                        -                        1                                            )                                                                                xe2x80x83                                                            T                                                        n                                                              xe2x80x83                                                            T                                                                                r                                          (                      m                      )                                                                                xe2x80x83                                                                          (                    t                    )                                                                          xe2x80x83                                                                          c                    k                                    *                                      (                                          t                      -                                              τ                        k                                                              )                                                                          xe2x80x83                                                                          ⅆ                    t                                                                                =                              xe2x80x83                                                                                A                    k                                                                          xe2x80x83                                                                          b                    k                                                                          xe2x80x83                                                                          (                    n                    )                                                                          xe2x80x83                                                      exp                                                        xe2x80x83                                                                          (                                                                  -                        j                                                                                xe2x80x83                                                                                φ                                                  (                          m                          )                                                                                )                                                  +                                                                                xe2x80x83                                                                                ∫                                                                  (                                                  n                          -                          1                                                )                                                                                xe2x80x83                                                                  T                                                              n                                                                    xe2x80x83                                                                  T                                                                                [                                                                        ∑                                                                                i                              =                              0                                                                                i                              ≠                              k                                                                                N                            -                            1                                                                                xe2x80x83                                                                                A                            i                                                                                xe2x80x83                                                                                c                            i                                                                                xe2x80x83                                                                                (                                                          t                              -                                                              τ                                i                                                                                )                                                                                xe2x80x83                                                                                c                            k                                                    *                                                      (                                                          t                              -                                                              τ                                k                                                                                )                                                                                xe2x80x83                                                                                b                            i                                                                                xe2x80x83                                                                                (                                                          t                              -                                                              τ                                i                                                                                )                                                                                xe2x80x83                                                                              exp                                                                                xe2x80x83                                                                                (                                                                                -                                j                                                                                xe2x80x83                                                                                φ                                                                  (                                  m                                  )                                                                                )                                                                                ]                                                                                ⅆ                      t                                                                      +                                                                                xe2x80x83                                                                            N                                      (                    m                    )                                                                                xe2x80x83                                                                  (                  n                  )                                                                                =                              xe2x80x83                                                                                A                    k                                                                          xe2x80x83                                                                          b                    k                                                                          xe2x80x83                                                                          (                    n                    )                                                                          xe2x80x83                                                      exp                                                        xe2x80x83                                                                          (                                                                  -                        j                                                                                xe2x80x83                                                                                φ                                                  (                          m                          )                                                                                )                                                  +                                                                                xe2x80x83                                                                                ∑                                                                  i                        =                        0                                                                    i                        ≠                        k                                                                                N                      -                      1                                                                                [                                                                        ∫                                                                                (                                                              n                                -                                1                                                            )                                                                                xe2x80x83                                                                                T                                                                                n                                                                                xe2x80x83                                                                                T                                                                                c                            i                                                                                xe2x80x83                                                                                (                                                          t                              -                                                              τ                                i                                                                                )                                                                                xe2x80x83                                                                                c                            k                                                    *                                                      (                                                          t                              -                                                              τ                                k                                                                                )                                                                                xe2x80x83                                                                                b                            i                                                                                xe2x80x83                                                                                (                                                          t                              -                                                              τ                                i                                                                                )                                                                                ⅆ                            t                                                                                xe2x80x83                                            ]                                                            exp                                                              xe2x80x83                                                                                (                                                                        -                          j                                                                                xe2x80x83                                                                                φ                                                      (                            m                            )                                                                                )                                                                      +                                                                                xe2x80x83                                                                            N                                      (                    m                    )                                                                                xe2x80x83                                                                  (                  n                  )                                                                                ≅                              xe2x80x83                                                                                A                    k                                                                          xe2x80x83                                                                          b                    k                                                                          xe2x80x83                                                                          (                    n                    )                                                                          xe2x80x83                                                      exp                                                        xe2x80x83                                                                          (                                                                  -                        j                                                                                xe2x80x83                                                                                φ                                                  (                          m                          )                                                                                )                                                  +                                                      ∑                                                                  i                        =                        0                                                                    i                        ≠                        k                                                                                N                      -                      1                                                                                xe2x80x83                                                                          [                                                                  A                        i                                                                                xe2x80x83                                                                                w                        ij                                                                                xe2x80x83                                                                                (                        n                        )                                                                                xe2x80x83                                                                  exp                                                                    xe2x80x83                                                                                (                                                                              -                            j                                                                                xe2x80x83                                                                                φ                            i                                                          (                              m                              )                                                                                )                                                              ]                                                  +                                                      N                                          (                      m                      )                                                                                xe2x80x83                                                                          (                    n                    )                                                                                (        3        )                                                                    w              ij                                                  xe2x80x83                                                  (              n              )                                ≡                      xe2x80x83                                                        ∫                                                (                                      n                    -                    1                                    )                                                                  xe2x80x83                                                T                                            n                                                  xe2x80x83                                                T                                                                                c                I                                                          xe2x80x83                                                          (                                  t                  -                                      τ                    i                                                  )                                                          xe2x80x83                                                          c                k                            *                              (                                  t                  -                                      τ                    k                                                  )                                                          xe2x80x83                                          bi                                            xe2x80x83                                                          (                                  t                  -                                      τ                    i                                                  )                                                          xe2x80x83                                                          ⅆ                t                                                                      xe2x80x83                                    (        4        )
In addition, the correlation calculator 81 of FIG. 9 calculates a correlation Rk(m) between the received symbol x(m)(n) of the mth antenna element and the received symbol x(m+1)(n) of the (m+1) th antenna element based on the following formula (5), where brackets xe2x80x9c less than   greater than xe2x80x9d indicate averaging and the terms inside the brackets xe2x80x9c less than   greater than xe2x80x9d are shown in the formula (6).                                           R            k                          (              m              )                                =                       less than                                           x                k                                  (                  m                  )                                                                          xe2x80x83                                                          (                n                )                                                          xe2x80x83                                                          x                k                                                      (                                          m                      +                      1                                        )                                    *                                                                          xe2x80x83                                                          (                n                )                                       greater than
                                    (        5        )                                                      x            k                          (              m              )                                                      xe2x80x83                                          (            n            )                                          xe2x80x83                                          x            k                                          (                                  m                  +                  1                                )                            *                                                      xe2x80x83                                          (            n            )                          =                                                            "LeftBracketingBar"                                  A                  k                                "RightBracketingBar"                            2                                                  xe2x80x83                                                                  "LeftBracketingBar"                b                "RightBracketingBar"                            2                                                  xe2x80x83                                                  exp                                            [                                  j                                                        xe2x80x83                                                                          (                                                                  φ                        k                                                  (                          m                          )                                                                    -                                              φ                        k                                                  (                                                      m                            +                            1                                                    )                                                                                )                                                  ]                                              +                                    (        6        )                                                      ∑                                          i                =                0                                            i                ≠                k                                                    N              -              1                                                      xe2x80x83                                                                        "LeftBracketingBar"                                  A                  i                                "RightBracketingBar"                            2                                                  xe2x80x83                                                                  "LeftBracketingBar"                                                      W                    ik                                                                          xe2x80x83                                                                          (                    n                    )                                                  "RightBracketingBar"                            2                                                  xe2x80x83                                                  exp                                            [                                  j                                                        xe2x80x83                                                                          (                                                                  φ                        k                                                  (                          m                          )                                                                    -                                              φ                        k                                                  (                                                      m                            +                            1                                                    )                                                                                )                                                  ]                                                    +                              N                                          (                m                )                            *                                                      xe2x80x83                                          (            n            )                                          xe2x80x83                                          N                          (              m              )                                *          n                                    xe2x80x83
The correlation Rk(m) is then averaged for each of the antenna elements and a cross-correlation function Rk among the adjacent antenna elements is obtained based on the following formula (7), where M denotes the number of antenna elements.                               R          k                =                              [                          1                                            /                                                          (                                  M                  -                  1                                )                                      ]                                                        ∑                              m                =                0                                            M                -                2                                                                xe2x80x83                                                  R              k                              (                m                )                                                                        (        7        )
FIG. 9 shows a structure for adding the correlations R(0) to R(2) from the correlation calculators 81-0 to 81-2 by the adder 82. However, no calculation function related to the term [1/(Mxe2x88x921)] in the formula (7) is shown. Since (Mxe2x88x921) is a fixed value, it is clear that an averaging process can be carried out based on the addition.
In formula (6) as described above, the second term on the right hand side of the equal sign is an uncorrelated signal and the term |Wik(n)| is a small value. Hence, if there is no significant difference among the received signal amplitudes Ai of each of the users, it is possible to extract by averaging a phase error of a desired signal (kth user) of the first term on the right hand side of the equal sign of the formula (6). Accordingly, based on a ratio of an imaginary part Im(Rk) and a real part Re (Rk)using the cross-correlation function Rk of the formula (7), it is possible to estimate, from the following formula (8), an arrival angle xcex8k of the kth user signal.
xcex8k=sinxe2x88x921[(xc2xdxcfx80d)tanxe2x88x921{Im(Rk)/Re(Rk)}]xe2x80x83xe2x80x83(8)
According to the conventional arrival direction estimation method described above, the arrival direction is estimated from the strongest signal received after the despreading process, regardless of whether or not the desired signal exists. For this reason, it is difficult to estimate the correct arrival direction of the desired signal in cases where the reception amplitude of the desired signal is small and in cases where large interference signals exist.
For example, when a multi-rate transmission including a high-speed rate and a low-speed rate in the DS-CDMA communication system is made, the received signal of the high-speed rate user becomes an interference signal for the received signal of the low-speed rate user since the transmission power of the high-speed rate signal is large. Consequently, a problem exists in that it is difficult to estimate the arrival direction of the desired signal of the low-speed rate user.
Accordingly, it is an object of the present invention to enable estimation of the correct arrival direction of the desired signal in a DS-CDMA communication system using a code having a period longer than the symbol length of the spreading code, even when a interference signal exists.
These and other objects are met in accordance with an arrival direction estimation method of the present invention, using an array antenna in a DS-CDMA communication system for performing a transmission by performing a spreading process including a code having a period longer than a symbol length. The method also includes to subject received signals from the array antenna to a despreading process. A cross-correlation function of lags other than the zero lag for signals corresponding to adjacent antenna elements is obtained by inverse-modulating despead output signals by a known symbol. Further, an arrival direction of a desired signal based on the cross-correlation function is estimated.
It is also possible to use an average value of the cross-correlation function for a plurality of different lags as the cross-correlation function of the lags among the inverse modulated signals corresponding to the adjacent antenna elements, wherein the zero lag is excluded from this function. It is also possible to obtain the cross-correlation function using both positive and negative lags excluding the zero lag among the inverse modulated signals corresponding to the adjacent antenna elements. A pilot symbol may be used as the known symbol to inverse-modulate the received signals. It is also possible to provide a decision feedback symbol as the known symbol to inverse-modulate the received signals.
A DS-CDMA receiver unit according to the present invention is also provided for a DS-CDMA communication system, which carries out a transmission by performing a spreading process using a code having a period longer than a symbol length. The DS-CDMA includes despreading units for subjecting received signals from array antenna elements to a despreading process. Further included is a beam forming unit 4 for inputting despread output signals from the despreading units and a channel receiver for inputting output signals of the beam forming unit. The beam forming unit includes an inverse modulator for inverse-modulating the despread output signals by a known symbol, an arrival direction estimation unit for receiving signals from the inverse modulator and a beam former. The beam former provides an output by multiplying a weighting coefficient from the arrival direction estimation unit to the despread output signals and then adding such products.
The inverse modulator may be configured to use either a pilot symbol or a decision feedback signal, as the known symbol. The arrival direction estimation unit may include a correlation calculator for obtaining a cross-correlation among output signals of the inverse modulator corresponding to the adjacent antenna elements and an array weighting coefficient calculator for obtaining and averaging the cross-correlation functions with respect to a plurality of lags excluding a zero lag. The array weighting coefficient calculator then outputs a weighting coefficient obtained as a result of estimating the arrival direction based thereon. In this case, the cross-correlation function with respect to the plurality of lags may be calculated by providing first and second shift registers.

Arrival direction estimation method using an array antenna and DS-CDMA receiver unit using the method