A radio access network dynamically compiles history data regarding mobile wireless devices that tend to fail successful ranging, e.g., establishment of Layer 1 communication with a radio access node or base station. The history data is obtained from messages sent from the mobile device to the network which contain a count indicating the number of times the device has failed a ranging attempt. If the history (or count) data indicates that a wireless device has experienced ranging failures exceeding a threshold number of failures, the base station responsively blocks the device from attempting any additional ranging for a period of time. The period of time can be short-term period of time or a long term period of time. The methods avoid excessive use of air interface resources by excluding wireless devices which are unable to successfully range. That is, “bad” or “problem” wireless devices are excluded from access to the network.

A. Field
This invention relates to the art of wireless telecommunications between wireless devices and a base station, and more particularly to methods efficient management of network resources at the base station during ranging between the wireless device and the base station.
B. Related Art
In the wireless telecommunications art, there are known communications protocols by which mobile wireless devices may access a network of a wireless service provider. These include CDMA and GSM, of which persons skilled in the art are familiar.
Wireless service providers are developing additional technologies by which wireless devices may access their network. These include WiMAX (Worldwide Interoperability for Microwave Access), a broadband wireless access protocol based on the IEEE 802.16 standard, including extensions such as 802.16a, 802.16b, and 802.16e.
WiMAX chipsets which provide for communication in accordance with the WiMAX protocol are becoming increasingly prevalent as standard or optional equipment not only in traditional wireless communications devices, such as cellular phones and personal digital assistants, but also in devices which, heretofore, were not used for access to telephony networks. These devices include portable music players, entertainment devices such as game players, automobiles, domestic appliances and so on. It is expected that by the year 2009 there will be in excess of 100 million devices in use which have WiMAX chipsets in them. Thus, a virtual explosion of the number of WiMAX devices is expected to occur in the near future.
When WiMAX devices are turned on, a ranging process typically occurs by which the devices seek to establish a physical layer connection with a radio access node (referred to herein interchangeably as a base station) in a network which provides connectivity for the WiMAX device to either other WiMAX devices or a node on a computer network (e.g. Internet, or wireless service provider network). The possibility of millions of WiMAX devices all contending for limited resources in terms of radio access nodes presents acute problems of resource allocation on the network side. Furthermore, from a business standpoint, there is a desire to keep WiMAX technology simple and cheap and thus a solution to the resource allocation problem is preferably one that keeps cost to a minimum and avoids, to the extent possible, the deployment of additional radio access nodes.
To understand the resource allocation problem in more detail, it is helpful to provide additional background discussion of the ranging process by which WiMAX devices establish this physical layer connection with a base station.
Briefly, when a WiMAX device (chipset) starts up there is an initial system acquisition step in which the device is pre-programmed to look at a particular frequency, in search of a "preamble" that they can decode. The preamble is a signal broadcast from a base station and represents a particular base station. Thus, once the device finds the preamble, it has found a WiMAX base station.
After this initial step has occurred, a ranging step occurs in which the device asks for resources from the base station. This process functions to get OSI reference model Layer 1 (physical layer) connectivity and synchronization. It involves several messages passing between the base station and the device, to find a proper power level, frequency, timing (synchronization) and perhaps other parameters that will be used for communication between the device and base station. It also involves giving the network information about the device, negotiating with the network, and giving the network the device's Medium Access Control (MAC) identity so as to then facilitate higher layer communications.
More specifically, in the ranging step the WiMAX device that receives a preamble signal then tries to establish connectivity with the base station that issued the preamble signal. To do so, the WiMAX device sends to the base station an initial ranging request, in which the device provides (i) a MAC ID of the device, (ii) a ranging request subheader—to identify the message as a ranging request-type message, and (iii) PDU—i.e., a payload block, usable for anything. The device transmits this ranging request at a particular power level and with particular timing. The device then waits for a ranging response message from the base station.
If the device does not receive a ranging response, it will then ramp up its transmission power and send a new ranging request to the base station. It will keep doing this until it gets a ranging response from the base station.
The device may receive a ranging response from the base station that tells the device to adjust its power and timing in some manner. The device will then make the adjustment and send a new ranging request to the base station using the adjusted parameters. This back and forth process will continue until the base station is satisfied.
When the base station is satisfied with the power and timing parameters used by the device, the base station will send to the device a ranging response that specifies those power and timing parameters as initial parameters the device should use when it engages in session establishment communication, etc.
Note that, in practice, multiple devices may contend for use of a common set of resources. Thus, this process of assigning a device to an initial set of power/timing parameters is an effort by the base station to focus the device's operation in a way that will not interfere too much with other WiMAX devices but that are still sufficient to facilitate proper operation.
Note also that the timing synchronization process involves getting alignment between what the device is sending/receiving and what the base station is sending/receiving. The specifics of timing synchronization and power setting (and thus the specifics of how the base station would or would not be satisfied with the settings in a given instance) are defined in the WiMAX standard and are not at all critical to the present invention.
After the base station has sent the ranging response message, the base station then sends an "Uplink MAP" (UL-MAP) message to the WiMAX device. This message tells the device that ranging is done, and it moves the device from contention-based RF space to dedicated RF space. That is, the base station now has full control over the communication with the device. In an orthogonal frequency division multiple access (OFDMA) system like WiMAX, the base station gives the device a specific frequency, bandwidth, a specific timeslot, and specific coding (like CDMA) to use for communication. The base station provides that information to the WiMAX device in the UL-MAP message. This establishes a dedicated channel (called a "sub-channel") between the base station and the device.
After this occurs, the WiMAX device then sends a response/ack message back to the base station. At this point, the device has not yet registered with the network, e.g., undergone authentication or higher application levels in the OSI reference model. Rather, the ranging process establishes the OSI Layer 1 (RF) settings for communication. After the ranging step is completed, the device enters a session establishment step. This step occurs at Layer 2 of the OSI reference model and higher levels. This could involve the device registering with the network, registering with application servers, services, etc.
All of the ranging activity to accomplish a setting of the Layer 1 parameters consumes significant base station resources. That is fine if the ranging process works. However, if failures (particularly repeated failures) occur in the ranging process, it could be a problem, as more and more base station resources are then consumed, which could preclude other important uses of the resources. Thus, in a cell serving a large number of WiMAX devices, such as in an urban area, airport, shopping mall, or other type of location, a large number of WiMAX devices (devices having embedded WiMAX chipsets) may carry out this ranging process and thus consume base station resources, even without ever becoming registered with the network. This presents significant resource allocation problems for WiMAX base stations.
Moreover, an entity that provides WiMAX base station services, such as wireless communication service provider like Sprint Nextel or Verizon, may face the situation where devices that the service provider wants to be able to access its network (i.e., its subscribers) will be contending for base station resources with devices that the service provider does not want to have access to its network, i.e., non-subscribers. Therefore, there is a need in the art for ways of handing ranging request messages for large populations of WiMAX devices which impose less demands on base station resources, both in terms of consumption of available spectrum and processing power at the base station.

Ranging resource allocation for wireless devices in networks providing access by Wi-MAX and like protocols


A method of manufacturing an optical semiconductor device including forming an optical waveguide on a substrate and forming an alignment mark on the substrate simultaneously with the optical waveguide. The alignment marks do not transmit infrared light and, when the substrate is mounted on an infrared transmissive submount, precise alignment can be achieved by observing transmitted light. Thus, the optical semiconductor device including the substrate is soldered at the desired location.

1. Field of the Invention
The present invention relates to the devices semiconductor devices, such as a semiconductor laser chip, an endface incident type photodiode, or an endface incident-type semiconductor amplifier, which may be incorporated with high precision into an optical communication module, and methods of manufacturing the devices.
2. Description of the Related Art
Among the methods for incorporating a semiconductor laser chip into an optical communication module are an "active alignment method" and a "passive alignment method". In the active alignment method, the optical axis of a semiconductor laser chip, while emitting light, is aligned with an optical fiber, the semiconductor laser chip being fixed to a submount at a position where an optical output may be obtained.
In the passive alignment method, on the other hand, the semiconductor laser chip is positioned such that an alignment mark on the semiconductor laser chip is superimposed on an alignment mark on the submount, and the semiconductor laser chip is then fixed to a submount.
Since alignment of optical axes generally takes a long time, the passive alignment method not requiring alignment of optical axes results in a better throughput and allows the fabrication of an optical communication module at a lower cost as compared to the active alignment method where alignment of optical axes is required.
In the passive alignment method, however, the precision of the position of the alignment mark on the semiconductor laser chip with respect to a waveguide (emitting point) has a large effect on the coupling efficiency of an exiting laser beam to an optical fiber. Accordingly, an optical communication module having an excellent coupling efficiency cannot be achieved without improving the alignment mark positioning precision.
A known optical semiconductor device and passive alignment method are described with reference to FIGS. 26A to 27C. FIG. 26A is a plan view of a known semiconductor laser chip. FIG. 26B is a cross-sectional view of the known semiconductor laser chip taken along line 26B--26B of FIG. 26A. FIGS. 27A to 27C show a passive alignment method using a known semiconductor laser chip. The structures of FIGS. 26A to 27C are not known to the public but represent a created technology for explaining the invention.
Referring to FIGS. 26A and 26B, a known semiconductor laser chip 1 includes a substrate 2, an active layer 3 (optical waveguide 3a), a current blocking layer 6, a contact layer 7, an insulating film 8, a front surface electrode 9, a pair of alignment marks 10 formed at the same time as the front surface electrode 9, and a back surface electrode 11. The alignment marks 10 are the same material as the front surface electrode 9.
Referring to FIGS. 27A to 27C, a submount 20 includes a substrate 21, an optical fiber 22 on the substrate 21, a metal pattern 24 on the substrate 21 and having a pair of alignment marks 23, and a solder 25 on the metal pattern 24. The pair of alignment marks 23 are holes in the metal pattern 24 at symmetrical positions with respect to the center line of the optical fiber 22.
The known passive alignment method is now described. The semiconductor laser chip 1 of FIG. 27A, while being aligned by means of infrared light, is die bonded, as shown in FIG. 27C, to the submount 20 of FIG. 27B. As a coarse alignment step, the semiconductor laser chip 1 is placed on the submount 20, for example, with a vacuum tweezer. The coarse alignment uses pattern recognition with the metal pattern 24 indicating the mounting position of the semiconductor laser chip 1 on the submount 20, and infrared light transmitted through the front surface electrode 9 or back surface electrode 11 of the semiconductor laser chip 1. For example, infrared light incident on and transmitted through the semiconductor laser chip 1 is detected by a CCD (charge coupled device) disposed at the back surface of the submount 20.
The alignment mark 10 of the semiconductor laser chip 1, which does not transmit infrared light, and the alignment mark 23 on the submount 20, which transmits infrared light, are seen as overlapping, as shown in FIG. 27C, when infrared light is transmitted. Alignment is effected during transmission of the infrared light so that the respective centers of areas of the alignment marks 10 and 23 coincide. The metal pattern 24 and the back surface electrode 11 are then bonded to each other using the solder 25. Thereafter, an optical communication module is fabricated by mounting on the submount 20 an electrode for driving the semiconductor laser chip 1, a photodiode for monitoring an output laser beam, etc.
In the known semiconductor laser chip, the optical waveguide 3a and the alignment mark 10 are formed in different processes, i.e., the alignment mark 10 is formed together with the front surface electrode 9 in a processing step that is later than the processing step for forming the active layer 3. There has thus been a problem, reflecting a limit of precision in superposition of a mask aligner, that an offset B as shown in FIG. 26A necessarily occurs between the center line of the optical waveguide 3a and the center line (bisector) of the pair of alignment marks 10.
Further, since this offset B is usually on the order of several microns, it is very difficult to achieve a precision on the order of submicrons, as required, using the passive alignment method. If, as shown in FIG. 27C, the semiconductor laser chip 1 with the offset B is used, the coupling efficiency between the optical waveguide 3a and the optical fiber 22 is poor. It has thus been difficult to obtain an optical communication module having an excellent coupling efficiency at a high yield.

Method of making optical semi-conductor device


A toy figurine includes an internal lighting effect. The internal lighting is visible through the outer surface of the figurine and may be manipulated to produce various lighting effects. The internal lighting includes a lighting layer, a visual effects display layer and a diffusion layer. The light diffusion layer may include an external surface of the toy figurine.

Toy figurines have been and continue to be a stable source of amusement for children. Enhancements and features that spark a child's imagination and provide continued engagement of the toy figurine with the child add to its play value and build a bond between the child and the toy figurine.
U.S. Pat. No. 6,159,101 to Simpson ("Simpson") discloses interactive toy products including a controller and a casing in the form of a figurine having one or more articulated limbs. Sensors detect movement of the limbs and use the detection as input to the controller to control a game playing activity. A screen, such as a liquid crystal display (LCD) screen, is set in the torso of the figurine. The screen displays a representation of the toy figurine, and movement of the articulated limbs of the figurine generates a corresponding movement of the displayed figurine. The screen may be provided with a cover, which may be configured as a piece of clothing, armor, or other equipment carried by the figurine, such as a breast plate. The breast plate provides protection for the screen. Here, only when the cover is removed from the figurine is the LCD screen visible to the child, so that the child may play the game on the screen. Because the screen is exposed, the Simpson product lacks the sense of "magic" and wonder from any lighting effects.

This patent is subject to a terminal disclaimer.

Toy figurine with internal lighting effect


Head-mounted Displays (HMDs) are commonly used for virtual reality, mixed reality, and augmented reality. HMDs are, by definition, worn on the head of a user to provide a display in the line of sight of the user. By viewing the display, the user is able to experience one of the aforementioned types of reality. Oftentimes, HMDs are configured to integrate live video captured from the user's perspective, especially in the case of the HMD providing augmented reality where a virtual environment is combined with video of the real world. The present disclosure provides a configuration for a HMD having an array of image sensors to accurately capture image data to form the live video from the user's perspective.

Head-mounted Displays (HMDs) are commonly used for virtual reality, mixed reality, and augmented reality. HMDs are, by definition, worn on the head of a user to provide a display in the line of sight of the user. By viewing the display, the user is able to experience one of the aforementioned types of reality.
In general, two types of HMDs can be distinguished: so-called video-see-through HMDs and optical-see-through HMDs. In an optical-see-through HMD the user can observe the real environment directly and observes the virtual content as an overlay added by semitransparent mirrors and/or displays. For certain applications video-see-through HMDs are better suited which combine a live video stream with the virtual content and present the combination to the user using a display.
In order to capture the live video from the user's perspective, the HMD has traditionally been equipped with two cameras, each one for capturing video relative to a corresponding eye of the user. However, this traditional HMD configuration is unable to accurately capture the live video from the user's perspective. The correct perspective cannot be captured by using a regular camera directly as the required location for a regular camera is already occupied by the user's eyes.
In particular, when the cameras are placed on the HMD in front of the user's eyes, their lateral distance from the user's eyes allows the cameras to rotate in a larger circle, and capture a slightly different perspective than the user's eyes would be capable. When the cameras are placed slightly above the user's eyes (i.e. on the user's forehead) but on basically the same vertical plane as the user's eyes, the height of the cameras from the ground is not equivalent to the height of the user's eyes from the ground, such that the cameras capture video at an elevation that is higher than the actual view from the user's eyes.
There is a need for addressing these issues and/or other issues associated with the prior art.

Head-mounted display having an image sensor array


A core strengthening device includes a tray and a ball. The tray has first and second opposing sides. The first side of the tray has a recess formed therein. A ball is selectively positionable at least partially within the recess in the tray. The ball has a first hemisphere and a second hemisphere. The first hemisphere has a first radius and the second hemisphere has a second radius that is different than the first radius. The core strengthening device provides instability to exercises, which requires a user's core muscles to work harder to perform the exercises and maintain balance, which strengthens the user's core muscles.

Using exercise balls (also known as stability or balance balls) has become a popular way to increase core strength, abdominal fitness, and balance. Exercising with an exercise ball, as opposed to exercising directly on a hard flat surface, forces the user's body to respond to the instability of the ball in order to remain balanced. As a result, the user engages many more muscles, which become stronger over time, thereby improving the user's balance, strength, and fitness. Most frequently, the core body muscles—the abdominal muscles and back muscles—are the focus of exercise ball fitness programs.
Depending on the type of exercise being performed or the fitness or skill level of the user, the level of instability of an exercise ball may need to be adjusted. The level of instability of an exercise ball can be decreased by reducing the pressure within the exercise ball so that the curvature of the exercise ball decreases (i.e., flattens out), making the exercise ball less prone to rolling. Conversely, the level of instability of an exercise ball can be increased by increasing the pressure within the exercise ball so that the curvature of the exercise ball increases, making the exercise ball more likely to roll. Typically, the pressure within an exercise ball can be adjusted by pumping air into or releasing air from the exercise ball through a valve.
Properly adjusting the level of instability of an exercise ball can be difficult. For instance, a pump may be required to increase the pressure within the exercise ball. Using the pump may be complicated and physically challenging for some users. Additionally, it can be difficult to achieve a level of pressure in the exercise ball that corresponds to a desired level of instability. For example, it may be difficult to gauge how much air to pump into or release from the exercise ball in order to achieve the desired level of instability. As a result, a user may pump too much or not enough air into the exercise ball to achieve the desired level of instability. Similarly, a user may release too much or not enough air from the exercise ball to achieve the desired level of instability.
Other exercise devices designed to improve a user's core strength and balance are disclosed in U.S. Pat. No. 6,422,983, U.S. Pat. No. 6,575,885, and U.S. Pat. No. 7,344,488.


An inductor device and method of forming the inductor device are provided. In some embodiments the inductor device includes a post passivation interconnect (PPI) layer disposed and an under bump metallization (UBM) layer, each disposed over a substrate. The PPI layer forms a coil and dummy pads. The dummy pads are disposed around a substantial portion of the coil to shield the coil from electromagnetic interference. A first portion of the UBM layer is electrically coupled to the coil and configured to interface with an electrical coupling member.

Advances in semiconductor device performance are largely attributable to reductions in device dimensions. Initially, the photolithographic and other micro-electronic fabrication techniques enabling such device scaling were not amenable to inductors, capacitors and other passive components often employed in semiconductor devices. Nevertheless, inductor design eventually evolved to take similar advantage of the advances in micro-electronic fabrication processes and experience scaling to a degree similar to that of active devices.
By way of example, inductors are now typically created on the surface of a semiconductor device substrate in a spiral shape created in a plane that is parallel to the substrate surface. The inductor may have several of these spiral-shaped coils as necessary to attain adequate inductance values. Unfortunately, conventional methods used to create the spiral-shaped inductors may produce inductor devices having limited performance.
The performance parameter of an inductor is typically indicated by its quality factor, Q. The quality factor is defined as the ratio between the energy stored in the reactive portion of the inductor and the energy that is lost in the reactive portion. In general, the higher the quality factor the better the performance of the inductor.
In some circumstances, an ultra-thick metal (UTM) process is utilized to fabricate inductors. However, the UTM process is rather complex and requires a large chip area. In addition, the UTM process may limit or constrain the pursuit of a high quality factor.

Inductor for post passivation interconnect and a method of forming

Taiwan Semiconductor Manufacturing Company, Ltd.


A method for manufacture and assembly of a concrete structure includes manufacturing, at a first location, wall sections and floor/ceiling sections. The wall sections include interior form walls of adjustable separation, and may include interior and exterior finish features, interior rebar, electrical and water supply, and optional fabric forms. The floor/ceiling sections include forms that have adjustable components, and may include rebar, interior finish features, and electrical and heating components. Wall sections and floor/ceiling sections are rotatably and slidably/rotatably attached to one another to define structure segments. Structure segments may be placed in shipping containers for transport. Structure segments are transported to a construction site in a compact orientation, manipulated to an assembled position, and then concrete is inserted into forms defined by the segments and permitted to cure. Forms may be provided to permit formation of footings simultaneously with pouring of concrete for wall sections. Structure segments may be placed together to form structures.

The construction of buildings of concrete is typically accomplished by one of two methods. In a first method, forms are assembled at the construction site, typically from wood, in the shape of the desired object. The assembly of forms at the construction site is extremely labor intensive. Significant amounts of time are expended in the assembly of forms at the site, rendering construction schedules susceptible to delays from weather. The construction of forms corresponding accurately to plans requires careful measurement and alignment, which further increases the time involved in on-site processes.
In a second method, building elements of concrete, and generally of reinforced concrete, are constructed in a factory location. The use of a factory location overcomes some disadvantages, such as the need to properly align and construct forms at a construction site. However, transportation of concrete and reinforced concrete building elements is expensive, and is generally economical only for distances of, at most, a few hundred miles. The high cost derives from the fact that the concrete building elements are extremely heavy, often requiring specialized trucking equipment. The concrete building elements are also often not able to fit in standard truck beds, and require oversize load designations. Oversize load designations further increase the cost of transportation, by requiring special permits and accompanying vehicles to provide warnings.
It is an object of the invention to overcome the foregoing disadvantages of the prior art.
It is an advantage of the invention that the foregoing disadvantages of buildings and construction techniques of the prior art are overcome.
Additional objects and advantages of the invention will become evident from the detailed description which follows.

Transportable forms for concrete buildings and components and methods of manufacture and use of same


An integrated circuit or circuit board includes functional circuitry and a scan path. The scan path includes a test data input lead, a test data output lead, a multiplexer, and scan cells. A dedicated scan cell has a functional data output separate from a test data output. Shared scan cells each have a combined output for functional data and test data. The shared scan cells are coupled in series. The test data input of the first shared scan cell is connected to the test data output of the dedicated scan cell. The combined output of one shared scan cell is coupled to the test data input lead of another shared scan cell. The multiplexer has an input coupled to the test data output, an input connected to the combined output lead of the last shared scan cell in the series, and an output connected in the scan path.

In FIG. 1, a prior art example of a dedicated boundary scan path or register exists around a master circuit 102, a slave 1 circuit 104, and a slave 2 circuit 106. The master circuit, such as a DSP, CPU, or micro-controller, is a circuit that controls the slaves. The slave circuits are circuits being controlled by the master, such as RAM, ROM, cache, A/D, D/A, serial communication circuits, or I/O circuits. The master and slave circuits could exist as individual intellectual property core sub-circuits inside an integrated circuit or IC, or as individual ICs assembled on a printed circuit board or multi-chip module (MCM). The scan paths 108-112 around each circuit are connected together serially and to a test data input (TDI) 114, which supplies test data to the scan paths, and a test data output (TDO) 116, which retrieves data from the scan paths.
For simplification, only a portion of the scan paths 108-112 of each circuit is shown. The scan paths of FIG. 1 are designed using dedicated scan cells, indicated by capital letters (C) and (D) in circles. The word dedicated means that the cell's circuitry is used for testing purposes and is not shared for functional purposes. The scan cells are located between the internal circuitry and the input buffers 128 and output buffers 130 of the slaves and master circuit.
In FIG. 2, an example of a dedicated scan cell consists of multiplexer 1 (MX1) 202, memory 1 (M1) 204, memory 2 (M2) 206, and multiplexer 1 (MX2) 208. This scan cell is similar to scan cells described in IEEE standard 1149.1, so only a brief description will be provided. During operation in a functional mode, functional data passes from the functional data input (FDI) 212 to the functional data output (FDO) 214. In a functional mode, control inputs 210 to the scan cell can: (1) cause FDI data to be loaded into M1 via MX1 during a capture operation; (2) scan data from TDI 216 through MX1 and M1 to TDO 218 during a shift operation; and (3) cause data in M1 to be loaded into M2 during an update operation. Neither the capture, shift, nor update operation disturbs the functional data passing between FDI and FDO. Thus the scan cell of FIG. 2 can be accessed and pre-loaded with test data while the cell is in functional mode. The data scan cell (D) associated with the D31 output of slave 1 104 has connections corresponding to the FDI 212, TDI 216, FDO 214, and TDO 218 signal connections of the FIG. 2 scan cell.
During a functional mode of operation of the circuit in FIG. 1, data is transferred from one of the slaves to the master via a 32-bit data bus (D0-31), indicated by the wired bus connections 126. In a functional mode the scan cells are transparent, allowing functional control and data signals to pass freely through the cells. In this example, the master enables slave 1 to transfer data by the ENA1 control signal, which is output from the master to slave 1. Likewise the master enables slave 2 to transfer data by the ENA2 control signal, which is output from the master to slave 2. While only two slave circuits are shown, any number could be similarly connected to and operated by the master. Since all the scan cells of the scan paths 108-112 are dedicated for test, they can be scanned from TDI to TDO without disturbing the functional mode of the FIG. 1 circuit.
As mentioned, being able to scan data into the scan paths during functional mode allows pre-loading an initial test pattern into the scan paths. The initial test pattern establishes both a data test pattern in the data scan cells (D) and a control test pattern in the control scan cells (C). By pre-loading an initial test pattern into the scan paths, the circuits can safely transition from a functioning mode to a test mode without concern over bus contention between the slave circuit's data busses. For example, the ENA1 122 and ENA2 124 control scan cells (C) can be pre-loaded with control data to insure that only one of the slave's D0-31 data busses is enabled to drive the wired bus connection 126. Maintaining output drive on one of the slave data busses upon entry into test mode prevents the wired data bus 126 from entering into a floating. (i.e. 3-state) condition. Preventing bus 126 from floating is desirable since a floating input to input buffers 128 of master 102 could cause a high current condition.
When test mode is entered, functional operation of the master and slave circuits stop and the scan cells in the scan paths take control of the master and slave circuit's data and control signal paths. A data scan cell (D) exists on each of the 32-bit data signal paths of each circuit 102-106, and a control scan cell (C) exists on each of the ENA1 and ENA2 control paths of each circuit 102-106. Having dedicated data and control scan cells located as shown in FIG. 1, enables safe test entry and easy interconnect testing of the wiring between the master and slave circuits when the scan paths are placed in test mode. During interconnect test mode, a capture, shift, and update control sequence, such as that defined in IEEE standard 1149.1, can be used to control the scan paths.
To prevent contention between slave 1 and slave 2 data outputs 126 during the capture, shift, and update control sequence, the 3-state control outputs 118-120 of the ENA1 and ENA2 control scan cells 122-124 do not ripple during the capture and shift part of the control input sequence. This is accomplished by having the data in M2 of FIG. 2 be output, via MX2, during the capture and shift operation. Only during the update part of the control input sequence are the outputs 118-120 of the control scan cells 122-124 allowed to change state by new data being loaded into M2. Similarly, the outputs from the data scan cells (D) do not ripple during capture and shift operations, but rather change state only during the update part of the control input sequence.
In FIG. 3, a prior art example of a shared boundary scan path exists around a master 302 and slave circuits 304-306. As in FIG. 1, the scan paths 308-312 around each circuit are connected together serially and to a test data input (TDI), which supplies test data to the scan paths, and a test data output (TDO), which retrieves data from the scan paths. The scan paths of FIG. 3 are designed using shared scan cells (C) and (D), i.e. the scan cell memory is shared for both test and functional purposes. As an aid to indicate use of shared scan cells as opposed to dedicated scan cells, the shared scan cells of FIG. 3 and subsequent figures are shown positioned outside the boundary scan paths 308-312 and in the functional circuits. The dedicated scan cells of FIG. 1 were shown positioned inside the boundary scan paths 108-112. Again, for simplification, only a portion of each circuit's boundary scan path is shown.
In FIG. 4, an example of a conventional shared scan cell consists of a multiplexer (MX) 402 and a memory (M) 404. During a functional mode of operation, control inputs 406 form a path between FDI 408 and the data input of M 404 via MX 402, to allow functional data to be clocked from FDI to FDO 410. During a test mode, the control inputs 406 cause FDI data to be clocked into M via MX during a capture operation, and cause test data to be clocked from TDI 412 to TDO 414 during a shift operation. Since M 404 is used functionally, it cannot be accessed and pre-loaded with test data as can the scan cell of FIG. 2. Thus the ability to access and pre-load test data while the master and slave circuits of FIG. 3 operate functionally is one of the key distinctions between dedicated (FIG. 2) and shared (FIG. 4) scan cells.
In FIG. 3, the data scan cell associated with the D31 output of slave 1 304 is labeled to indicate the FDI 408, TDI 412, FDO 410, and TDO 414 signal connections of the FIG. 4 scan cell.
During the functional mode of the circuit in FIG. 3, as in FIG. 1, data is transferred from one of the slaves to the master via the 32-bit data bus (D0-31) through shared connections 326. The master enables data transfer from slave 1 or slave 2 via the ENA1 and ENA2 control signals, respectively. Since the scan cells of the scan paths are shared and used functionally, they cannot be scanned from TDI to TDO without disturbing the functional mode of the circuits. Not being able to scan data into the scan paths during functional mode prevents pre-loading an initial test pattern into the scan paths.
By not being able to pre-load an initial test pattern into the scan paths, the slave circuits are put at risk of not safely transitioning into the test mode from the functional mode. This situation occurs due to the timing domains of the functional and test modes not being synchronous to one another, which results in asynchronous functional to test mode switching.
For example, if the circuits of FIG. 3 switched from the functional mode timing domain to a test mode timing domain, a possibility exists that the D0-31 output buffers of slave 1 and 2 could both be enabled as a result of an asynchronous mode switch that caused scan cell ENA1 322 and scan cell ENA2 324 to both output enable conditions on wires 318 and 320. This would force a voltage contention situation between slave 1 and 2, resulting in the output buffers being damaged or destroyed. This voltage contention situation does not occur in the boundary scan path of FIG. 1 since an initial safe test pattern is pre-loaded into the scan cells prior to the functional to test mode switching step.
Once in a test mode, the scan path of FIG. 3 can be accessed to shift in test data. During shift operations the outputs 318-320 of the control scan cells 322-324 ripple as data shifts through the cells. This output ripple from the control scan cells can cause the D0-31 output buffers of the slaves to be enabled and disabled during the shift operation. This control output ripple causes the output buffers of slaves 1 and 2 to be simultaneously enabled, again creating bus contention between the slaves. This voltage contention situation does not occur in the boundary scan oath of FIG. 1 since M 206 maintains a safe control output via MX 208, during shift operations.
In FIG. 5, one prior art technique prevents the above-mentioned two voltage contention situations. The technique is based on providing additional circuitry and control inputs to enable or disable the slave's output buffers during test mode entry and again during each test mode shift operation. A signal gating circuit 528 is inserted into signal path 518 of slave 504 and a signal gating circuit 530 is inserted into signal path 520 of slave 506. A control signal C1 532 is added as an input to circuits 528 and 530. When C1 is in a first state, the ENA1 and ENA2 outputs from scan cells 522 and 524 are allowed to pass through circuits 528 and 530 to enable or disable the output buffers of slaves 504 and 506. However, when C1 is in a second state, the outputs of circuits 528 and 530 are forced, independent of ENA1 and ENA2, to disable the output buffers of slaves 504 and 506. By controlling C1 to the second state during the transition from functional mode to test mode, the first above mentioned voltage contention situation can be avoided. By again controlling C1 to the second state during each shift operation that occurs during test mode, the second above mentioned voltage contention situation can be avoided.
While the technique described above solves the voltage contention situations, it does so by introducing a floating (i.e. 3-state) condition on data bus 526. As described above, the output buffers of slaves 504 and 506 are disabled during test mode entry and during each shift operation. With the output buffers disabled, data bus 526 is not driven and may float to a voltage level that could turn on both input transistors of the input buffers of master 502. This could result in a low impedance path between the master's supply and ground voltages, potentially damaging or destroying the input buffers of master 502.

Circuitry with multiplexed dedicated and shared scan path cells


A retainer for a crossover tube of a ball screw between a rack piston and a worm shaft of a motor vehicle power steering gear. The ball screw includes a helical passage between the rack piston and the worm shaft, a U-shaped crossover tube on the rack piston, and a plurality of bearing balls which roll in a ball circuit defined by the helical passage and the crossover tube. The crossover tube retainer is a molded plastic arch straddling a linear segment of the crossover tube having a web bridging the gap between the crossover tube and the rack piston bore. The thrust of the bearing balls urging dislodgment of the crossover tube from the rack piston is reacted against the rack piston bore through the web of the molded plastic arch across a bearing surface of the web having a contour complementary to the contour of the rack piston bore above the molded plastic arch. A pair of side walls of the molded plastic arch flare laterally outward in opposite directions from a throat of the molded plastic arch so that the retainer is compatible with ball screws having different helical lead angles.

U.S. Pat. No. 3,022,772, issued Feb. 27, 1962 and assigned to the assignee of this invention, describes a motor vehicle power steering gear including a housing, a pitman shaft linked to steered wheels of the motor vehicle, a sector gear on the pitman shaft, a worm shaft linked to a manual steering wheel of the motor vehicle, a rack piston having a rack gear thereon meshing with the sector gear on the pitman shaft, and a ball screw between the rack piston and the worm shaft which converts rotation of the worm shaft into linear translation of the rack piston in a bore in the steering gear housing. The ball screw consists of a helical passage between the rack piston and the worm shaft, a U-shaped crossover tube on the rack piston which cooperates with the helical passage in defining an endless ball circuit, and a plurality of bearing balls which roll in the ball circuit concurrent with rotation of the worm shaft relative to the rack piston. A metal strap clamped to the rack piston retains the crossover tube on the rack piston against thrust induced by the bearing balls urging dislodgment of the crossover tube from the rack piston. A crossover tube retainer according to this invention is a novel alternative to the metal strap described in the aforesaid U.S. Pat. No. 3,022,772.


An improved method for flushing the residue from internal surfaces of cavities in, for example, turbine blades. In accordance with one aspect of the invention, provision is made for simultaneously flushing the internal cavities of a plurality of turbine blades, with each blade having a plurality of cavities therein.

This invention relates generally to parts, such as turbine blades, that have internal cavities and, more particularly to a method and apparatus for cleaning the internal cavities thereof.
In the manufacture or repair of turbine blades of the type used in the high pressure turbine of a gas turbine engine, the internal cavities of the blade are left with a residue of undesirable foreign material such as salts, silicone and silk, which must be removed from the internal cavities in order to obtain proper performance therefrom. In addition, the foreign material can collect in corners or other such locations within the internal cavities. The usual method of cleaning these internal surfaces is to conduct an autoclave or ultrasonic cleaning operation, followed by a flushing out of the cavities by the use of a high pressure washing process.
The flushing process is commonly accomplished by using one or more probes to introduce a high pressure flow of a liquid such as water into one or more of the cavities in order to wash out the undesirable residue.
The apparatus for positioning the probes with respect to the blade cavity has generally been of two types. The one that has been used following the autoclave process was that of a single blade being flushed by a pair of probes simultaneously registering with their respective cavities, after which the probes were retracted and then indexed to the next blade for the same process.
Another prior art process that has been used after ultrasonic cleaning is that of a fixture having a pair of extended probes that separately register with individual cavities of two different blades. After the respective cavities have been cleaned, the fixture is retracted and then indexed to adjacent cavities in the same respective blades.

Method of simultaneously flushing internal cavities of multiple parts


A lens barrel device that includes optical parts holding frames, which hold optical parts so that the optical parts holding frames can linearly move in the optical axis directions, respectively, and an image capture device.

Patent Document 1, for example, discloses the type of lens barrel device. The Patent Document 1 discloses a lens barrel device that includes a plurality of movable lens. A lens barrel device disclosed in the Patent Document 1 is characterized in that "a lens barrel device includes a stationary barrel, a movable barrel moving in the optical axis direction, and a lens frame moving in the optical axis direction interlocked with the movable barrel, the stationary barrel includes a first cam inwardly protruded from an inner circumferential surface thereof, the movable barrel includes an opening portion including a second cam surface facing in the circumferential direction with a predetermined angle, and that the lens frame includes a plurality of cam followers engaged with the first cam in the circumferential direction, with the cam followers being engaged with the second cam at end portions in the circumferential direction".
According to the lens barrel device having the above configuration, it is expected that "since a structure to move a lens group used in the lens barrel can be achieved by decreasing the number of parts produced with integral molding of resin, an inexpensive lens barrel device can be produced with excellent assembly efficiency".
Further, Patent Document 2, for example, discloses another lens barrel device of this kind. The Patent Document 2 discloses a lens barrel device that can be used for a lens system of a video camera, or the like. The lens barrel device disclosed in the Patent Document 2 is characterized by "a lens barrel device, a lens disposed within the lens barrel device, a holding means for holding the lens, in which the holding means including a coil, a yoke disposed within the lens barrel device in response to the circumference of the holding means, a magnet disposed within the yoke to move the holding means within the lens barrel device, the magnet forming a linear actuator with the coil when the coil is conducted and a guide means for guiding the holding means of the lens along the lens barrel device by driving the linear actuator, the guide means located at the position inner side of the yoke, the magnet, and the coil in the radial direction".
According to the lens barrel device having the above configuration, it is expected that "external form of the lens barrel device can be simplified without externally providing the guide means of a guide shaft".
However, in the above-mentioned lens barrel device described in the Patent Document 1, while cam pins provided on a plurality of movable barrels holding respective lens groups are engaged with a plurality of cam grooves on a cam cylinder and allow the cam pins are caused to move along the respective cam grooves by rotating the cam cylinder, and thereby the movable barrel is caused to move in the optical axis direction; if the number of lens groups is increased, the number of barrels should increase to fit the lens groups into the respective barrels; thus, the lens barrel device will have complicated configuration since an external diameter of an entire lens barrel device increases. In addition, an optical design for lenses and mechanical design for as cam grooves should be compatible with one another, so that parts usually have complicated designs.
Moreover, when the lens barrel device received impact from the front thereof, such impact is immediately transmitted to the cam pins, so that the cam pins may be broken or disengaged from the cam grooves, or the grooves may collide with peripheral parts. Accordingly, the barrel holding the lens group may not move, or peripheral parts may be damaged. In addition, it may be difficult to secure impact-resistance against the lens barrel device.
Further, since the lens barrel device including numeral lens groups to move needs contact slide portions having the cam pins and the cam grooves, so that a large rotational torque is required to drive the lens barrel device; when the lens barrel device is driven, a motor of large torque is generally decelerated gear to rotate. However, if a large-sized motor and a gear box for decelerating gear are mounted on the lens barrel device, the lens barrel device may increase in size.
Moreover, in the lens barrel device disclosed in the Patent Document 2, while the linear actuator is driven to move a plurality of lens frames along the guide shafts in the optical axis direction, backlash may be observed between holes into which the guide shafts of a plurality of lens frames are inserted and the guide shafts, due to dimensional errors of respective parts such as lens frames and errors of mounting accuracy of parts. As a result, adjusting to eliminate backlash without affecting the control of lenses may be required, thereby decreasing operating efficiency.
Patent Document 1:
The Official Gazette of Unexamined Published Japanese Patent Application No. Hei-7-294793
Patent Document 2:
The Official Gazette of Unexamined Published Japanese Patent Application No. Hei-8-15593
The problem to be solved is that, when the cam grooves formed on the cam cylinder are engaged with the cam pins provided on the barrel holding the lens group, and the barrel holding the lens group is moved by rotating the cam cylinder, if the number of lens group is increases, the number of barrels should also increase to fit the lens groups into the barrels, so that the lens barrel device will have a complex design, and the external diameter of the lens barrel device will increase. Further, if the guide shafts support a plurality of lens frames such that the lens frames can move, backlash will be observed between the guide shafts and the guide holes of the lens frames. Accordingly, adjusting to eliminate backlash may be required, thereby decreasing operating efficiency.

Lens barrel device and image capture device


The present disclosure relates to a novel ejector apparatus for pluggable transceivers, such as transceivers defined by multi-source agreements (MSAs) including SFP, SFP+, XFP, and the like. The ejector apparatus utilizes a shrouded design where the ejector apparatus encapsulates the top, sides, and bottom of a pluggable transceiver thereby allowing an operator to grasp any side of the ejector apparatus to actuate engagement prongs. In keeping with MSA guidelines, the ejector apparatus utilizes prongs to disengage a locking mechanism in order for the kick out springs to release the module. Advantageously, the ejector apparatus enables high density placement of corresponding transceivers, allows access from all sides of the transceiver for ejection, and allows cables to remain connected to the transceiver during ejection.

A variety of devices utilize pluggable transceivers to provide connectivity. Exemplary devices include optical network elements (SONET, SDH, OTN, etc.), Ethernet switches, routers, video devices, and the like. In an effort to decouple transceiver design and manufacturing from the underlying devices, various multi-source agreements (MSAs) have been defined to standardize pluggable transceivers. MSAs are agreements for specifications of transceivers agreed to by two or more vendors and promulgated for other vendors and network operators to utilize. MSAs allow other vendors to design transceivers to the same specifications reducing risk for vendors and operators, increasing flexibility, and accelerating the introduction of new technology. Exemplary MSAs include XFP, XPAK, XENPAK, X2, XFP-E, SFP, and SFP+. Additionally, new MSAs are emerging to address new services and advanced technology. Each MSA defines the transceiver's mechanical characteristics, management interfaces, electrical characteristics, optical characteristics, and thermal requirements. Because of MSA specifications, MSA-compliant transceivers are standardized among equipment vendors and network operators to support multiple sources for pluggable transceivers and interoperability. As such, MSA-compliant transceivers have become the dominant form of transmitters and receivers in the industry.
Advantageously, MSA-compliant pluggable transceivers ensure engineering re-use and compatibility between various applications and the physical media dependent transceivers. Further, equipment vendors realize streamlined manufacturing and inventory control by removing wavelength specific decisions from the manufacturing process. For example, all line cards are manufactured the same, and the MSA-compliant transceiver module with the desired wavelength (e.g. 850 nm, 1310 nm, 1550 nm, dense wave division multiplexed (DWDM), etc.) is used as a function of the specific application or development configuration. Network operators and service providers have adopted MSA-compliant transceivers to reduce sparing costs. Further, significant cost reductions are realized by MSA standardization of MSA-compliant transceivers because of multiple independent manufacturing sources.
The MSA specifications tightly define the mechanical characteristics, management interfaces, electrical characteristics, optical characteristics, and thermal requirements of pluggable transceivers. However, the MSA specifications, such as in the case of SFP, SFP+, etc., do not specify how the pluggable transceivers are ejected from a host device. The SFP transceiver is specified by a MSA from the SFF committee (available at www.sffcommittee.com). The SFP was designed after the gigabit interface converter (GBIC) interface, and allows greater port density (number of transceivers per inch along the edge of a mother board) than the GBIC, which is why SFP is also known as mini-GBIC. The related Small Form Factor (SFF) transceiver is similar in size to the SFP, but is soldered to the host board as a pin through-hole device, rather than plugged into an edge-card socket. Small form-factor pluggable transceivers offer a great deal of flexibility in limited spatial constraints. The ability to densely populate such transceivers is highly marketable for to add system capacity.
MSAs, such as the SFP MSA, identify features that must be present with respect to an ejector methodology. The ejector is a mechanism to add/remove a pluggable transceiver from a host system. Conventional designs for ejectors utilize the enclosure side with either a tabbed or bail latch ejector system. Tabbed and single-arm ejector designs limit the ejector's accessibility in that the ejector can only be engaged from one direction thereby limiting the ability to densely populate modules. Bail-style ejectors include an arm that folds over the front of the transceiver that engages an ejection actuator. A key disadvantage of bail-style ejectors is that they require the user to disconnect any cables or fibers connected to the module prior to actuation. Other disadvantages of bail-style ejector systems are their complexity, cost, and their inability to work with longer neck connector styles.
Thus an improved ejector methodology is needed for pluggable transceivers, such as the SFP transceiver, that allows ease of access, supports high density, and allows ejection with connected cables.

Ejector apparatus and associated assembly method for pluggable transceivers


A receiver hitch arrangement includes a receiver tube, a mount having a shank portion received within the receiver tube and a hitch pin inserted through hitch pin apertures which are formed in both the receiver tube and the shank portion and which are aligned at assembly to maintain the mount in a position for towing. A rattling that is usually caused due to movement between hitch components. is prevented by forming a pair of through and threaded apertures in each vertical wall of the receiver tube and in close proximity to a free end thereof, threadeably engaging a threaded shank of a fastener with each of the pair of apertures and then operably advancing each fastener for direct contact with the shank portion of the mount inserted into the receiver tube until the shank portion is frictionally caged and immobilized.

One problem that is continuously experienced in use of the receiver type hitches is that since the receiver tube is slightly larger than the mount's shank, the hitch arrangement is characterized by a rattle effect due to the space formed between the outer peripheral surface of the shank and the inner peripheral surface of the receiver tube and, consequently, due to the shank selectively engaging side walls of the receiver tube during motion.
Prior to the present invention, efforts have been made to eliminate the rattling.
U.S. Pat. No. 6,105,989 issued to Linger discloses one type of a rattle eliminating device which includes a collar, an adjustment bolt, a lock nut and a second nut. The collar has a center wall and two side walls forming a U-shaped bracket that can fit over a reinforcing lip of the hitch receiver tube. A front wall on the collar has an opening for receiving a mount shank as it enters the receiver tube. An adjustment bolt extends through the center wall to tighten the collar onto the hitch receiver tube. When the adjustment bolt is tightened, the center wall of the collar moves upward and away from the receiver tube, causing the opening in the front wall to lift the shank against the inner wall of the tube and prevent it from moving within the tube. The lock nut then holds the entire anti-rattle assembly into position.
U.S. Pat. No. 5,735,539 issued to Kravitz discloses another type of the rattle eliminating device which includes a bridge element, a spaced pair of flanges secured to and projecting from the bridge element so that the bridge element and the flanges together straddle at least one of the receiver and shank, the flanges being connected to at least one of the receiver and shank, and the mechanism includes a spaced pair of projections each engaging a different one of the receiver and shank whereby to tighten the telescopic connection therebetween.
U.S. Pat. No. 6,974,147 issued to Kolda teaches a system which includes an engagement or locking member, which may be in the form of a cam, that is movably mounted within an interior defined by the shank. An actuator arrangement is carried by the shank and is interconnected with the cam, for moving the cam between an operative position and a release position. The cam bears against the receiver tube, and is configured such that movement of the cam from the release position to the operative position, in response to operation of the actuator arrangement, causes the cam to move laterally through an opening in the shank into engagement with an internal surface defined by the receiver tube. In this manner, the cam applies a lateral force that urges the shank laterally into engagement with an internal surface defined by the receiver tube. The actuator arrangement may be in the form of a rotatable knob secured to the shank, which is interconnected with an actuator rod that moves axially in response to rotation of the rotatable knob so as to cause pivoting movement of the cam between the operative position and the release position.
In U.S. Pat. No. 5,879,102 issued to Koliopoulos it is attempted to provide a clamp that locks two telescoping components such as a vehicle receiver hitch and a draw bar, for substantially reducing if not eliminating the "banging" or "rattling" between the two components. The clamp includes a standard sized U-bolt, whose throat rests in a seat formed by a receiver hitch collar and a receiver hitch tube. A bar has an arc-shaped cross-section and includes two holes adapted for receiving the threaded ends of the U-bolt. When the draw bar is inserted into the receiver hitch, the arc-shaped side of the bar is positioned within a seat formed by the receiver hitch collar and the draw bar. Standard locking style nuts are threaded onto the legs of the U-bolt and tightened, causing the arc-shaped side of the bar to be wedged against the receiver hitch collar and the draw bar, while wedging the U-bolt throat against the opposite side of the receiver hitch collar and the receiver hitch. This effectively "clamps" or locks the draw bar and the receiver hitch together, eliminating any movement of the two pieces.
U.S. Pat. No. 5,344,175 issued to Speer teaches a hitch shank that includes two apertures which a securing pin is indexed through. The first aperture is not within the receiver hitch and contains a threaded interior which coincides with a threaded exterior of a securing pin. The second aperture is located inside the receiver tube and includes an interior wedge member which extends towards the interior of the hitch shank and is parallel with the securing pin. The securing pin includes one tapered end for frictional engagement with both the wedge member and the interior wall of the receiver tube, and a second end for grasping, then rotating the securing pin. As the securing pin is rotated and tightened against the wedge member and the interior wall of the receiver tube, the hitch shank is pressed firmly against the receiver tube towards the side opposing the tapered securing pin end, thereby eliminating all undesired movement between the receiver tube and the hitch shank.
However, the prior art devices and systems are disadvantaged by higher than desirable complexity of installation and quantity of the required components and therefore are characterized by higher than desirable manufacturing and maintenance costs.
Therefore, there is a continuing need for an improved system for preventing rattling in a receiver hitch arrangement.

System and method for preventing rattling in receiver hitch arrangement


A process for fabricating a sharp corner-free shallow trench isolation structure. First, a SiON layer and a mask layer are successively formed on a semiconductor substrate. The SiON layer and mask layer are patterned to form an opening, exposing the substrate region on which a shallow trench isolation region will be formed. Next, an oxide spacer is formed on sidewalls of the SiON layer and mask layer. A trench is formed in the semiconductor substrate using the spacer and mask layer as a mask. Next, a liner oxide layer is formed on the surface of the trench by thermal oxidation, such that the liner oxide layer near the SiON layer is in a bird""s beak form. An isolating oxide layer is filled in the trench. Finally, the mask layer and SiON layer are removed. The present invention forms a short and thick bird""s beak structure and rounded trench corner. Therefore, the thickness of the tunnel oxide is even and the tunnel oxide integrity remains. Thus, the electric current is not accumulated on the trench corner, and parasitic transistors and current leakage can be prevented.

1. Field of the Invention
The present invention relates to a process for fabricating a shallow trench isolation structure, and more particularly to a process for fabricating a sharp corner-free shallow trench isolation structure.
2. Description of the Prior Art
Process technology has evolved to submicron geometries, and shallow trench isolation (STI) has been gradually replacing conventional semiconductor device isolating methods such as, for example, local oxidation of silicon (LOCOS). STI provides several major advantages over LOCOS methods. For example, STI methods allow higher device density by decreasing the required width of the semiconductor device isolation structure. As yet another benefit, STI enhances surface planarity which, in turn, considerably improves critical dimension control during photolithography steps.
FIGS. 1a to 1c are cross-sections illustrating the process flow of fabricating an STI structure according to a conventional method. First, referring to FIG. 1a, a pad oxide layer 120 and a nitride layer 130 are successively formed on a semiconductor substrate 100, which are then patterned to form an opening 200.
Subsequently, referring to FIG. 1b, the semiconductor substrate 100 is etched to a predetermined depth using the patterned nitride layer 130 as a mask, thus forming a trench 210. In FIG. 1b, the corner defined by a vertically oriented sidewall 110 and the top surface of semiconductor substrate 100, which is called trench corner, is a sharp corner 300.
Subsequently, referring to FIG. 1c, an insulating material, such as silicon oxide, is filled into the trench 210 to form an insulating layer 420. Next, a densification step such as annealing is performed to densify the insulating layer 420. After this, the nitride layer 130 is removed. Next, a wet-etching process is performed to remove the pad oxide layer 120. Since this wet-etching process is isotropic, it also causes a lateral part of the oxide layer 420 to be etched away. Also, the. stress induced by sharp corners 300 accelerates the etching rate of the insulating layer 420. As result, a recess 460 is formed in the insulating layer 420 near the sharp corner 300.
When a dielectric layer such as tunnel oxide layer is formed during subsequent steps, the tunnel oxide layer is formed to be thinner near sharp corners 300. The reduction in the thickness of tunnel oxide layer results in poor tunnel oxide integrity. Also, this causes electric field reversion, thus forming parasitic transistors. A very high electric field is accumulated at the sharp corners 300, thus causing current leakage.
Many attempts have been made to fabricate an STI structure with a rounded corner in order to prevent the above-mentioned sharp corner effect. Joyner in U.S. Pat. No. 6,228,747 muses a disposable spacer of an organic material or low-temperature inorganic material to prevent the sharp corner effect. Chatterjee et al. use the LOCOS method to form a bird""s beak structure to prevent the sharp corner effect. The process is very complicated (IEEE, 1996).
The object of the present invention is to solve the above-mentioned problems and to provide a process for fabricating a sharp corner-free shallow trench isolation structure. The corner formed from the sidewall and top surface of the silicon substrate is rounded. When a dielectric material such as tunnel oxide is formed afterwards on the active region, the corner thinning effect is prevented due to the rounded corner. The thickness of the tunnel oxide is even and the tunnel oxide integrity remains. Thus, the electric field is not accumulated on the trench corner, and parasitic transistors and current leakage can be prevented.
To achieve the above-mentioned object, the process for fabricating a sharp corner-free shallow trench isolation structure of the present invention includes the following steps. First, a SiON layer and a mask layer are successively formed on a semiconductor substrate. The SiON layer and mask layer are patterned to form an opening, exposing the substrate region on which a shallow trench isolation region will be formed. Next, an oxide spacer is formed on sidewalls of the SiON layer and mask layer. A trench is formed in the semiconductor substrate using the spacer and mask layer as a mask. Next, a liner oxide layer is formed on the surface of the trench by thermal oxidation, such that the liner oxide layer near the SiON layer is in a bird""s beak form. An isolating oxide layer is filled in the trench. Finally, the mask layer and SiON layer are removed.

Process for fabricating sharp corner-free shallow trench isolation structure


A force limiting workpiece holding device for holding a workpiece in a workpiece processing assembly having a spindle and a closer that applies a force, comprises a workpiece holder slidably mounted to the spindle. The workpiece holder includes a plurality of circumferentially-spaced gripping segments that are movable between expanded and contracted positions to grip and release a workpiece. A force limiting coupling structure includes a biasing structure having a spring force. The coupling structure is operatively mountable between the workpiece holder and the closer such that a force applied by the closer to move the gripping segments of the workpiece holder between the expanded and contracted positions is transferred to the workpiece holder through the coupling structure and the biasing structure thereof, whereby a resultant force being applied to the workpiece holder by the closer is limited to the spring force of the biasing structure.

1. Field of the Invention
The present invention relates to workpiece holding devices for holding a tool or workpiece in a workpiece processing assembly.
2. Description of Related Art
Workpiece holding devices, such as collet and jaw chucks, are used to clamp or grip workpieces or tools in workpiece processing assemblies such as turning machines. The workpiece holding devices include a number of circumferentially-spaced gripping segments that are movable between expanded and contracted positions to grip or release a workpiece or tool. A closer is operatively connected to the workpiece holding device to apply a force for moving the segments of the workpiece holding device between the expanded and contracted positions. Typically, a draw bar is rigidly coupled between the workpiece holding device and the closer such that actuation of the closer applies a force to the workpiece holding device via the draw bar.
The closer is often times in the form of a hydraulic closer. Hydraulic closers are advantageous in that they can exert large forces (with respect to pneumatic closers, for example), which in turn will grip the workpiece or tool very securely for a processing operation. However, when a delicate workpiece, such as a thin walled ring, is to be processed, the large forces exerted by the hydraulic closer easily distort the delicate workpiece. Typically, the operating force in hydraulic closers cannot be lowered enough to eliminate distorting the workpiece. Moreover, lowering the operating force to low levels causes the hydraulic closer to move extremely slow, thereby dramatically slowing down the cycle time for gripping the workpiece.
The present invention provides an improved workpiece holding device that is structured to limit the force that may be applied by a closer to the workpiece holding device so that thin walled or delicate workpieces may be gripped which may be otherwise subject to distortion.


A calibration circuit includes a single-wire memory and a transmission line. The single-wire memory includes a power/interrogation terminal and a ground terminal. The single-wire memory is configured to store calibration data for a sensor. The transmission line is configured to be coupled between the sensor and a sensor reader. The transmission line includes first and second conductors. The first conductor is coupled to the power/interrogation terminal and is configured to provide the calibration data and a sensor output signal to the sensor reader. The second conductor is coupled to the ground terminal and is configured to provide a ground reference for the first conductor, the single-wire memory, and the sensor.

The field of the disclosure relates generally to calibration circuits and, more particularly, to a calibration circuit having a single-wire memory device and a method of use thereof.
Many known radio frequency (RF) sensor systems operate using RF near-field coupling at frequencies ranging from 1 kilohertz (kHz) to 300 gigahertz (GHz). Such sensor systems typically include, for example, and without limitation, a first component in direct contact with an environment to be measured, and a second component not in direct contact with the environment. The first component typically includes a transducer component for sensing some aspect of the environment and an RF component for coupling to the second component. The second component typically includes an interface through which measurements are transmitted to an interrogator. The interrogator is any system suitable for reading an output signal from the sensor.
These known RF sensor systems typically utilize calibration data. Some known RF sensor systems provide calibration data using radio frequency identification (RFID) systems, where an RFID tag is placed on a particular component or machine. Certain other RF sensor systems provide calibration data through firmware updates, which generally entails a manual process. These known RF sensor systems are expensive and complex. In many cases, such as, for example, and without limitation, RF torque sensors, it is desirable for the calibration data to accompany a particular field-replaceable component rather than the interrogator, otherwise referred to as the sensor reader system. A calibration circuit is desirable that provides calibration data for an RF sensor in a cost-effective and non-complex manner, while facilitating the calibration data to accompany a particular component and be physically separated from the sensor reader system.


The present invention includes an event detector for detecting selected events occurring in a computer system which are programmed to automatically move a cursor image from a viewing area of a video display to an overscanned area of a video display. The invention further includes a cursor controller for generating the cursor image and controlling movement of the cursor image on the video display. The cursor controller automatically places the cursor image in the overscanned area of a video display when the event detector detects the occurrence of a selected event. Alternatively, the event detector can include a timer for delaying the notification of detection to the cursor controller of the selected event.

A personal computer/television (PC/TV) convergence device is a fully functional computer integrated with television functionality, providing television viewing (via broadcast, cable, Digital Satellite, or other broadcast media) and personal computing functionality. This convergence of computer and television functionalities provide a user with combined access to television program information and computer and Internet information.
Since the PC/TV convergence device is controlled by the computer's operating system, the PC/TV convergence device can, among other things, display personal computer (PC) applications and television programs on a single monitor. The convergence of the personal computer and the television into a single device also permits the utilization of the communications bandwidth, mass storage and graphics of the computer to deliver, store and display applications during a traditional television viewing environment.
The PC/TV convergence device is a user interactive device. For example, if a user is watching a television program, the PC/TV convergence device will enable the user to download information about that particular program, such as from a web site where additional information about or related to the program might be located. In general, the PC/TV convergence device can be operated in a variety of modes including, but not limited to, a personal computer mode, a television mode, or a combined personal computer and television mode. Often, images displayed on the television functionality include an image of a cursor. Following certain events, such as when switching to the television mode for viewing full motion video images, it is desirable for the cursor to be removed from the viewing area. Currently, this requires the user to manually move the cursor off the viewing area. It would be advantageous, therefore, to devise an apparatus and method whereby the cursor image is automatically placed out of sight in an overscanned area of a video display when these events occur.

Automatic cursor parking to hide a mouse pointer


The present invention provides Methyl- (or Mutant-) Differential Display (MDD) methods and nucleic acid probes for detecting mutations and the methylation patterns of nucleic acids. The methods of the present invention are particularly useful for detecting and isolating genomic DNA fragments which are near coding and regulatory regions of genes and which are differentially mutated or methylated relative to the corresponding DNA from normal cells. Genes are frequently not methylated in the cells where they are expressed but are methylated in cell types where they are not expressed. Moreover, tumor cell DNA is frequently methylated to a different extent and in different regions than is the DNA of normal cells. The present invention is used for identifying which regions of the genome are methylated or mutated in different cell types, including cancerous cell types. The present invention is also used for diagnosing whether a tissue sample is cancerous, and whether that cancerous condition is non-metastatic or metastatic.

DNA is often methylated in normal mammalian cells. For example, DNA is methylated to determine whether a given gene will be expressed and whether the maternal or the paternal allele of that gene will be expressed. See Melissa Little et al., Methylation and p16: Suppressing the Suppressor, 1 NATURE MEDICINE 633 (1995). While methylation is known to occur at CpG sequences, only recent studies indicate that CpNpG sequences may be methylated. Susan J. Clark et al., CpNpGp Methylation in Mammalian Cells, 10 NATURE GENETICS 20, 20 (1995). Methylation at CpG sites has been much more widely studied and is better understood.
Methylation occurs by enzymatic recognition of CpG and CpNpG sequences followed by placement of a methyl (CH.sub.3) group on the fifth carbon atom of a cytosine base. The enzyme that mediates methylation of CpG dinucleotides, 5-cytosine methyltransferase, is essential for embryonic development--without it embryos die soon after gastrulation. It is not yet clear whether this enzyme methylates CpNpG sites. Peter W. Laird et al., DNA Methylation and Cancer, 3 HUMAN MOLECULAR GENETICS 1487, 1488 (1994).
When a gene has many methylated cytosines it is less likely to be expressed. K. Willson, 7 TRENDS GENET. 107-109 (1991). Hence, if a maternally-inherited gene is more highly methylated than the paternally-inherited gene, the paternally-inherited gene will give rise to more gene product. Similarly, when a gene is expressed in a tissue-specific manner, that gene will often be unmethylated in the tissues where it is active, but will be highly methylated in the tissues where it is inactive. Incorrect methylation is thought to be the cause of some diseases including Beckwith-Wiedemann syndrome and Prader-Willi syndrome. I. Henry et al., 351 NATURE 665, 667 (1991); R. D. Nicholls et al., 342 NATURE 281, 281-85 (1989).
The methylation patterns of DNA from tumor cells are generally different than those of normal cells. Laird et al., supra. Tumor cell DNA is generally undermethylated relative to normal cell DNA, but selected regions of the tumor cell genome may be more highly methylated than the same regions of a normal cell's genome. Hence, detection of altered methylation patterns in the DNA of a tissue sample is an indication that the tissue is cancerous. For example, the gene for Insulin-Like Growth Factor 2 (IGF2) is hypomethylated in a number of cancerous tissues, such as Wilm's Tumors, rhabdomyosarcoma, lung cancer and hepatoblastomas. Rainner et al. 362 NATURE 747-49 (1993); Ogawa, et al., 362 NATURE 749-51 (1993); S. Zhan et al., 94 J. CLIN. INVEST. 445-48 (1994); P. V. Pedone et al., 3 HUM. MOL. GENET. 1117-21 (1994); H. Suzuki et al., 7 NATURE GENET 432-38 (1994); S. Rainier et al., 55 CANCER RES. 1836-38 (1995).
The present invention is directed to a method of detecting differential methylation at CpNpG sequences by cutting test and control DNAs with a restriction enzyme that will not cut methylated DNA, and then detecting the difference in size of the resulting restriction fragments.
While methylation-sensitive restriction enzymes have been used for observing differential methylation in various cells, no commercial assays exist for use on human samples because differentially methylated sequences represent such a minute proportion of the human genome that they are not readily detected. The human genome is both highly complex, in that it contains a great diversity of DNA sequences, and highly repetitive, in that it contains a lot of DNA with very similar or identical sequences. The high complexity and repetitiveness of human DNA confounds efforts at detecting and isolating the minute amount of differentially methylated DNA which may be present in a test sample. The present invention remedies the detection problem by providing new procedures for screening a selected subset of the mammalian genome which is most likely to contain genetic functions.
The present invention provides techniques for detecting and isolating differentially methylated or mutated segments of DNA which may be present in a tissue sample in only minute amounts by using one or more rounds of DNA amplification coupled with subtractive hybridization to identify such segments of DNA. DNA amplification has been coupled with subtractive hybridization in the Representational Difference Analysis (RDA) procedures disclosed in U.S. Pat. No. 5,436,142 to Wigler et al. and Nikolai Lisitsyn et al., Cloning the Differences Between Two Complex Genomes, 259 SCIENCE 946 (1993). However, for the subtractive hybridization step of such RDA procedures to proceed in a reasonable time and with reasonable efficiency, only a subset of the genome can be examined. To accomplish this necessary reduction in the complexity of the sample DNA, Wigler et al. and Lisitsyn et al. disclose cutting DNA samples with restriction enzymes that cut infrequently and randomly. However, selection of enzymes which randomly cut the genome, means that the portion of the genome which is examined is not enriched for any particular population of DNA fragments. Thus, when RDA is used, only a random subset of the human genome, which includes repetitive elements, noncoding regions and other sequences which are generally not of interest, can be tested in a single experiment.
In contrast, the present invention is directed to methods which use enzymes that cut frequently and that specifically cut CG-rich regions of the genome. These enzymes are chosen because CG-rich regions of the genome are not evenly distributed in the genome--instead, CG-rich regions are frequently found near genes, and particularly near the promoter regions of genes. This means that the proportion of the genome that is examined by the present methods will be enriched for genetically-encoded sequences as well as regulatory sequences. Moreover, unlike the RDA method, the present methods selectively identify regions of the genome which are hypomethylated or hypermethylated by using enzymes which specifically cut non-methylated CG-rich sequences. The present invention therefore represents an improvement over RDA methods because of its ability to select DNA fragments which are likely to be near or to encode genetic functions.

Identification of differentially methylated and mutated nucleic acids

North Shore University Hospital Research Corp.


The semiconductor device si formed by forming a first metal film over a first main surface of a semiconductor wafer having a first thinkness, performing back grinding to a second main surface of the semiconductor wafer thereby making a second thickness thinner than the first thickness and forming an insulation film pattern having a first insulation film and containing an annular insulation film pattern along the periphery of a second main surface of the semiconductor wafer over the second main surface along the periphery thereof. The second main surface of the semiconductor wafer is bonded to a pressure sensitive adhesive sheet thereby holding the device semiconductor wafer by way of the pressure sensitive adhesive sheet to a dicing frame in a state where the insulation film pattern is present.

Patent Document 1 describes a technique of appending a seal member to the periphery of a wafer thereby leaving a thick peripheral portion as it is for preventing cracking or bending of the wafer upon etching the wafer rear face for lowering the on resistance of a vertical type MOSFET (Metal Oxide Semiconductor Field Effect Transistor).
Patent Document 2 describes a technique for improving the strength and the durability of the wafer in a vertical power device by forming a rim-shaped hard mask with a silicon nitride film or the like at the periphery of a wafer rear face and conducting etching using the same as a mask, thereby leaving a thick peripheral portion as it is.
Patent Document 3 discloses a technique of leaving a thick periphery of a wafer in a ring shape as it is for ensuring the strength of the wafer upon reducing the film thickness of a silicon wafer in the process for producing a semiconductor device, and filling a silicon oxide film, a silicon nitride film, etc. in a lattice-shape at the rear face of the wafer previously and etching the silicon portion so as to leave them thereby reducing the thickness.
Patent Document 4 and Patent Document 5 disclose techniques of forming a patterned silicon oxide film, a silicon nitride film, etc. for relieving warping of a wafer.
Patent Document 6 and Patent Document 7 disclose a technique of using a silicon nitride film pattern as an etching mask and removing the silicon nitride film pattern after etching upon reducing the thickness of a wafer.    [Patent Document 1] Japanese Unexamined Patent Publication No. 2003-243356    [Patent Document 2] Japanese Unexamined Patent Publication No. 2001-44088    [Patent Document 3] Japanese Unexamined Patent Publication No. 2007-317950    [Patent Document 4] Japanese Unexamined Patent Publication No. 2005-322839    [Patent Document 5] US Unexamined Patent Publication No. 2005-0253235    [Patent Document 6] Japanese Unexamined Patent Publication No. 2007-335659    [Patent Document 7] Japanese Unexamined Patent Publication No. 2008-53595

Manufacturing method of semiconductor device


It is an object of the present invention to provide a rare earth magnet that will not decompose due to hydrogen embrittlement when used in a hydrogen gas atmosphere, and furthermore, does not pose the risk of contaminating a reaction bath with the surface treated film of the magnet. The present invention provides a sealed rare earth magnet comprising: a rare earth magnet; and a case of aluminum or aluminum alloy, wherein the case covers entirety of the rare earth magnet and is sealed by HIP; and the methods for manufacturing the same.

1. Field of the Inention
The present invention relates to sealed rare earth magnets and methods for manufacturing the same, and more specifically relates to sealed rare earth magnets used in motors or semiconductor manufacturing devices, and methods for manufacturing the same.
2. Description of Related Art
Rare earth magnets have utilized in various fields such as motors and semiconductor manufacturing devices. For example, when rare earth magnets are utilized in motors for fuel cell vehicles, there is a risk that the rare earth magnets will be exposed to a hydrogen gas atmosphere. In addition, etchers and the like in semiconductor manufacturing devices sometimes utilize hydrogen gas as the reacting gas. In such a case, there is a possibility that when rare earth magnets are used in semiconductor manufacturing devices, there is a risk that they will be similarly exposed to the hydrogen gas atmosphere. Rare earth magnets suffer from hydrogen embrittlement. Therefore, even if various anti-oxidation surface treatment methods such as nickel plating, copper plating, aluminum ion plating and resin coating are utilized on the magnet surface, when in a hydrogen atmosphere, there is the problem of the risk that the magnet will be destroyed due to hydrogen embrittlement. As a rare earth magnet in which countermeasures are taken against hydrogen embrittlement, Japanese Patent Application Unexamined Publication No. H11-087119/1999 A, which is herein incorporated by reference, discloses a rare earth magnet that has a hydrogen storage alloy, which shows a plateau pressure of 0.001 to 0.1 MPa at a temperature of 400 K and above, as a surface treatment film, wherein the rare earth magnet is preferably Nd2Fe14B1, and wherein the surface treatment film is preferably made by providing a Pd plating on the surface of the Nd2Fe14B1.

Sealed rare earth magnet and method for manufacturing the same


A device for enhancing interpersonal communication over distance through use of touch. A vibrotactile (touch-and-vibration) interface is used to improve existing remote communication by allowing tactile cues to augment the audio-visual information in real-time. The pressure exerted by each finger of the transmitter produces patterns of vibration against the corresponding finger of the receiver. A hand-held device using the interface allows a user to transmit and receive patterns of vibration to and from a remote user and signify tactile gestures, or expressive uses of touch.

Conventional communication systems allow people to connect to each other in real-time while being physically separated. The ability to instantaneously exchange sound, text and images over great distances has become almost commonplace. However, commercial communication devices do not ordinarily convey a sense of touch. With rare exceptions, communicating using touch only occurs when people are face-to-face.
Touch conveys meaning and information in interpersonal communication. Touch acts as an extension of the physical body. Hand shakes between business partners signify agreement and commitment, the supportive squeeze of your hand by a friend, or even a quick tap of interruption from a stranger conveys a wealth of contextual information that is rarely present in real-time remote interpersonal communication. The goal of "reaching out to touch someone" suggests that touch is a powerful and meaningful part of interpersonal communication.
It is accordingly a principal object of the present invention to use touch to communicate between people at remote locations, and to use touch signal transmission to enhance conventional forms of communication, such as voice telephony.

Methods and apparatus for vibrotactile communication


An integrated circuit system (70) includes a processor (130) and a system bus (12) with a first complexity coupled to the processor. Apparatus for enabling communication between the processor and one or more devices through the system bus include a first device (90), a second device (80), and a first bus interface (72) coupled to the system bus (12), coupled to the first device (90) through a first bus (92) with a second complexity less than the first complexity and coupled to the second device (80) through a second bus (82) with a third complexity less than the first complexity.

This invention relates to control of busses and more particularly relates to such control employing busses of different complexities.
A modern integrated circuit may embody a system on a chip (SoC) that includes bus architectures composed of a few key components:
A complex system bus (or "backbone") that connects all modules;
A standard interface bridge which bridges the system bus to one or more relatively simple busses; and
Bridges/switches that may segment the system bus.
Busses in a typical SoC use many bus protocols of differing levels of complexity. A bus typically employs an address, data, and control.
Since all busses must have address and data, the difference between a low-complexity (or "simple") bus, and a high-complexity (or "complex") bus is the control. A reasonable measure of control complexity is state-space, or the number of states the bus may be in.
A typical SoC includes a multiple-master bus that supports multiple bus masters, also called "initiators" and "requesters," and one or more single-master busses that support only one bus master.
A bus bridge is used to connect two (or more) separate busses. Bridges may connect two busses with the same protocol (for example, a PCI-to-PCI bridge,) or busses with different protocols (for example, a PCI-to-USB bridge or a bridge that translates between a first bus that operates in a first plurality of states and a second bus that operates in a second plurality of states that may form a subset of the first plurality of states.)
It is difficult to design devices for a complex bus, like PCI. For this reason, bus interfaces employing bus bridges are commonly available to simplify the task. A bus interface can be used as a bridge between a relatively simple bus and a relatively complex bus. A bus interface allows a designer to access a complex bus from a simple, single-master bus. This simplifies the designer's task.
A multiple-master or complex bus is usually significantly more complex than a single-master or simple bus. A multiple-master bus may include facilities for:
Arbitration of the multiple masters;
Resource conflicts, such as, for a segmented bus, arbitration leading to an impasse in which the transaction on segment one cannot proceed until segment two is available, but the transaction on segment two cannot complete until segment one is available;
A BACKOFF/RETRY mechanism to resolve such conflicts;
Bus sharing to prevent one master from monopolizing the bus by using strict timing rules;
TIMEOUT/ABORT mechanisms to enforce the timing rules;
Bus locking for masters requiring a set of transactions to proceed without interruption from other masters; and
A bus LOCK mechanism to support the locking functionality.
A single-master bus or simple bus does not usually require most of the functions described in the preceding paragraph.
A simple bus may have a few states for "read," "write," or "idle." A complex bus may have a very large state-space with controls and states for arbitration, errors, configuration, timing, bursts, termination, and interrupts.
It is important to understand the range of bus complexities, and how significantly bus complexity affects chip design. A simple read/write/address/data bus can be defined with a few states, and a few sheets of paper. A complex bus, like PCI, has hundreds of states and requires many hundreds of pages to describe. This difference in complexity translates directly into hardware costs in terms of gates, development time and verification time.
FIG. 1 shows one form of an existing SoC bus architecture. An integrated circuit 10 employing an SoC includes a complex system bus 12 comprising an address bus 14 and a data bus 16. Circuit 10 also includes master devices 31–32 and slave devices 35–37. Simple single-master busses 41–42 comprise address busses 44–45 and data busses 47–48. Simple slave busses 51–53 include address busses 54–56 and data busses 57–59. Busses 51–53 also comprise single-master busses.
The system bus 12 may have a very complex multiple-master protocol. Most SoC architectures define modules with a simple single-master local bus, and use bus interfaces, such as interfaces 21–25, to translate the local bus transactions to the complex system bus protocol.
FIG. 2 illustrates another form of an existing SoC bus architecture in which a bus bridge 50 divides system bus 12 into segment 1 and segment 2. For complex SoCs with many bus masters, the system bus quickly becomes overloaded, and performance suffers. Bus bridge 50 can be used to segment the system bus.
Segmenting the system bus has several effects:
Each bus segment is shorter, and has fewer clients, which may allow the bus to run at a faster clock rate;
Some transactions may occur in parallel (e.g., Master 31 may access Slave 32, while Master 35 accesses Slave 36 simultaneously;
If Master 31 accesses Slave 36, the communication must go through the bus bridge, which will add some delay to the transaction, and will require arbitrating for both bus segments 1 and 2;
If Master 31 tries to access Slave 36, and Master 35 tries to access Slave 32, there is a potential for a resource conflict, and one master will need to backoff, and allow the other master to proceed;
The bus bridge may be used to restrict access to some devices (e.g., the bridge may prohibit Master 35 from accessing Slave 31) due to security reasons.
As systems become more complex, more levels of bus segmentation may be used. Bus topologies may grow very complex, and be very difficult to analyze.
Complex bus topologies, are a problem because:
System bus bridges, crossbars, and switches add cost to the system;
Resource conflicts can be difficult to manage;
Bus performance can be difficult to analyze; and
Changes to the bus topology can have large effects on the system performance.
The present invention addresses the foregoing problems and provides a solution.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.

Bus architecture techniques employing busses with different complexities