A method and apparatus are provided for improving the leveling and, consequently, the focusing of a substrate such as a wafer during the photolithography imaging procedure of a semiconductor manufacturing process. The invention performs a pre-scan of the wafer's topography and assigns importance values to different regions of the wafer surface. Exposure focus instructions are calculated based on the topography and importance values of the different regions and the wafer is then scanned and imaged based on the calculated exposure focus instructions.

1. Field of the Invention
This invention relates to the manufacture of semiconductor substrates such as wafers and, more particularly, to improving the leveling and consequently the focusing of the substrate during the photolithography imaging procedure of the manufacturing process.
2. Description of Related Art
The manufacture of semiconductor substrates such as wafers and chips involve the use of high-resolution lithography systems. In such systems, the patterned mask (i.e., reticle) is illuminated with radiation (e.g., laser radiation or radiation from an arc lamp) that passes through the illumination system and achieves high-degree illumination uniformity over the illuminated portion of the mask. A portion of the radiation that passes through the mask is collected by a projection lens, which has an image field of a given size. The projection lens images the mask pattern onto an image-bearing substrate or workpiece such as a wafer. The workpiece resides on a workpiece stage that moves the workpiece relative to the projection lens so that the mask pattern is repeatedly formed on the workpiece over multiple "exposure fields."
Lithography systems include an alignment system that precisely aligns the workpiece with respect to the projected image of the mask thereby allowing the mask to be exposed over a select region of the workpiece. Two types of lithography systems are typically used in manufacturing. One system is the step-and-repeat system, or "steppers" and the other is the step-and-scan system, or "scanner." With steppers each exposure field on the workpiece is exposed with a single static exposure. With scanners, the workpiece is exposed by synchronously scanning the workpiece and the mask across the lens image field. An exemplary scanning lithography system and method is described in U.S. Pat. No. 5,281,996, which is incorporated herein by reference. The following description will be mainly directed to the step-and-scan system although it will be understood by those skilled in the art that the invention is applicable to any type imaging system.
As is well known, in a typical photolithographic process, a thin layer of a photosensitive material or photoresist is deposited over a semiconductor wafer. During the photolithography process, illumination such as ultra-violet light is illuminated through a lens system and a photolithographic mask or reticle to the semiconductor wafer. The reticle has a particular device pattern and the pattern is exposed over a portion of the wafer by the illumination to create exposed and unexposed regions on the wafer. These exposed or unexposed regions are then washed away to define circuit elements on the wafer. This photolithography process is repeated many times on different layers of the wafer to define many circuit elements on the wafer. At the end of the photolithography process, the wafer having an exposed device pattern is cut into semiconductor chips.
Typically, a reticle is made from a transparent plate and has a device exposure region and an opaque region. The plate is often made of glass, quartz, or the like and the opaque chrome region typically includes a layer of chrome. The device exposure region generally has a square or rectangular shape and is positioned in the center of the reticle. The device exposure region includes transparent portions and opaque portions defining a device pattern. The transparent portions in the device exposure region allow illumination from a light source to travel through them and reach the wafer. On the other hand, the opaque regions of the device region block the light and the light does not reach the wafer.
FIG. 1 shows a typical prior art reticle 80 having a square device region 82 surrounded by an opaque chrome region 84. For the sake of simplicity, a device pattern 88 in the device region is not illustrated in detail in the figure. There is a kerf region 86 at the periphery of the device region 82 between the device region 82 and opaque chrome region 84. The kerf region 86 typically contains important information regarding the photolithographic process of the wafer and usually includes test structures to verify the performance of a photolithographic process. For example, the kerf region may include alignment marks to check the accuracy of the reticle alignment and registration marks to measure the resolution of the device pattern during the photolithographic process.
Lithographic imaging is highly dependent on substrate uniformity. A lithographic process can tolerate a small range of topography variation through the "depth of focus" inherent in the process capability. However, unanticipated topography variation on the substrate is a known problem for lithography processes and can result in a faulty imaging process and a rejection of the imaged workpiece.
Modern exposure systems such as the step-and-scan exposure system utilize an optical lens leveling system to control the height (focus) of the scanning slit above the wafer. The exposure tool can adjust to fluctuations in step-height by a set of simple linear motions. The problem arises when major step-height changes occur across the reticle field as shown in FIGS. 2A and 2B. Even sophisticated leveling systems are faced with a conflict on where to place the imaging focal plane relative to the uneven topography and, in general, trade-offs are made in some form of minimizing the average focus displacement across the imaging field.
On most product chips the pattern density on any one layer is generally not uniform. This can lead to discrete topography patterns after processing several physical layers due to the response of polishing and other processes to the varying pattern densities. Lithography tools, which often sample the wafer topography before or during exposure, try to respond to the topography and sometimes in an undesirable fashion. A typical response can be a tilt in the focus plane relative to the wafer, which follows the overall topography of a chip, but can yield unsatisfactory results on both levels of topography. This problem is valid for both step-only and step-and-scan systems. Although with step-and-scan systems, the focus response of the image tool may also be affected in time as the tool scans over different levels of topography. In principle, topography effects in the scanning direction can be corrected by a positional movement of the wafer relative to the exposure apparatus, but this can potentially lead to either loss of throughput or degraded focus performance.
Further, in many cases, the pattern density in the test kerf is quite different than the product chips. Beyond this, product chips may also vary within the imaging field. As mask set costs escalate, it is increasingly common for customers to share these costs by coordinating a variety of different chips onto one reticle, sometimes even coordinating with other customers. Since these chips may have quite different design purposes, there is further opportunity for non-uniform pattern density. These pattern density offsets can eventually lead to a step height due to film application and CMP polishing variations over the different densities. Since the leveling spots of the leveling mechanism of the scanning exposure system are sampling different step heights, a stage (and focus) tilt is created as the slit scans over these areas. If the simple linear tilt leaves significant residual focus errors, these focus errors can cause critical failures in the product.
Such errors are difficult to predict, identify, and correct. Often, problematic step heights develop during back-end processing as additional layers build up on the chip. Identification of missing patterns attributable to focus errors in many of these levels can be challenging. In many cases, critical failures are not found with conventional in-line inspection techniques. Traditional fixes include improving the overall process latitude (often not feasible if step heights are excessive, or fixing the CMP/design issues that cause the step height). In any event, either of these are costly and time consuming.
U.S. Pat. No. 6,081,614 to Yamada et al. relates to a surface position detecting method applicable to a slit-scan type or scanning exposure type exposure apparatus, for continuously detecting the position or tilt of the surface of a wafer with respect to the direction of an optical axis of a projection optical system. As discussed therein, the focusing of a mask image in these apparatuses continuously performs corrective drive for auto-focusing and auto-leveling during the scanning exposure process. A level and surface positioning detecting mechanism uses an oblique projection optical system wherein light is projected to the surface of a wafer obliquely from above and wherein reflection light from the photosensitive substrate is detected as a positional deviation upon a sensor. From the measured values of level during the scans a corrective drive amount is made to the level (height) and tilt of the wafer as the measurement position passes the exposure slit region.
FIG. 1 of the patent is reproduced here as FIG. 5 and shown as a fragmentary and schematic view of a slit-scan type projection exposure apparatus to which a surface positioning detecting method of the patent is applicable. The figure of the patent is included herein for clarity to describe how the subject invention relates to a typical lithographic apparatus which provides a wafer level adjustment. As shown in FIG. 5, a reduction projection lens 1 has an optical axis AX and an image plane which is perpendicular to the Z direction. Reticle 2 is held by a reticle stage 3 and a pattern of the reticle 2 is projected by the reduction projection lens. Denoted at 4 is a wafer having a surface coated with a resist and 5 is a stage on which the wafer is placed. The wafer stage S comprises a chuck for attracting and fixing the wafer 4 to the stage 5, an X-Y stage moveable horizontally along an X-axis and a Y-axis direction, a leveling stage moveable along Z-axis direction (same plane as the AX direction) and also rotationally moveable about the X and Y axes and a rotatable stage being rotationally moveable about the Z axis.
Denoted as numbers 10–19 in FIG. 5, are components of the detection optical system for detecting surface position and tilt of the wafer 4. A light source is denoted as 10 and 11 is a collimator lens for transforming the light from the light source 10 into parallel light having a substantially uniform sectional intensity distribution. Denoted at 12 is a slit member of a prism-shape having a plurality of openings therein (typically five or six) to form level sensing spots 72 (39) on the wafer. Denoted at 13 is an optical system which serves to direct the independent light beams from the pinholes of the slit member 12 to independent measurement level sensing spots points on the wafer surface by way of a mirror 14. These are also called leveling spots or sensors as shown as number 39 in FIG. 3A and number 72 in FIG. 2A.
Next, a structure for detecting reflection light from the wafer 4 is shown by the structure elements 15–19. Denoted at 16 is a light receiving optical system which receives the light beams from the wafer surface 4 by way of a mirror 15. Stop member 17 is provided within the light receiving optical system 16 and the light beams that pass through the optical system 16 have their axes parallel to each other and are re-imaged upon a detection surface of a photoelectrically converting means unit 19 by means of separate correction lenses of a correction optical system unit 18.
Tilt correction of stage 5 (and hence wafer 4) is made so that the measurement (leveling) points on the wafer 4 surface and the detection surface of the photoelectrically converting means unit 19 are placed in an optically conjugate relation.
Main control unit 27 serves to control the whole system and provides output for the reticle position controlling system 22, surface position detection system 26 and wafer position controlling system 25. When the reticle stage 3 is scanned in the direction of arrow 3a, the wafer stage 5 is scanningly moved in the direction of an arrow 5a. As regards the alignment of the reticle pattern in a Z-axis direction, the leveling stage of the wafer stage is controlled through the wafer position controlling system 25 on the basis of the result of the calculation of the surface position detection system 26 that detects height data of the wafer 4. Specifically, height data related to height spots defined in the scanned direction and adjacent to the slit are calculated and the wafer is tilted in a direction perpendicular to the scan direction as well as the height with respect to the optical axis AX direction.
The Yamada et al. patent improves the wafer positioning by measuring beforehand errors to be produced with respect to the level detection points due to a difference in pattern structure among the level detection points disposed along the scan direction. The measurement error with respect to each level detection point is then used to correct the position of the wafer using the surface position detecting system.
Positional information of the reticle stage with respect to the X and Y directions is measured continuously by projecting laser beams from reticle interferometer system 21 to mirror 20. Likewise for positioning the wafer stage 5, using wafer stage interferometer 24, wafer positioning controller 25 and mirror 23.
Publication No. U.S.2003/0107719 to Chen also discusses the problem of focus variation in wafer fabrication. In this publication a method for correcting improper leveling tilt comprises determining the improper leveling tilt induced by a leveling sensor of a semiconductor equipment improperly detecting a semiconductor wafer having an asymmetrical semiconductor pattern as out of horizontal and applies a corrective leveling tilt to compensate for the improper leveling tilt induced by the leveling sensor.
In U.S. Pat. No. 6,172,757 to Lee a wafer level sensor apparatus is disclosed using an electrically adjustable, two-directional zoom lens. The adjustable zoom lens provides field-by-field alignment on a stepper by providing a variable field view and depth of focus on the viewed field.
As noted above, the subject patent application is applicable to any such leveling system.
All the above patents are hereby incorporated by reference.

Density-aware dynamic leveling in scanning exposure systems


An electro-static discharge protection circuit and a semiconductor device having the same is disclosed. The electro-static discharge protection circuit has a current control circuit. The current control circuit has a first capacitive element. When the external source voltage is applied to the external source voltage supply line, the booster circuit in the internal circuitry boosts the internal source voltage of the internal source voltage supply line. The external source voltage becomes transiently greater than the internal source voltage at the early stage of the boosting step when the booster circuit boosts the internal source voltage based on the external source voltage. The first capacitive element restricts a current from flowing from the second terminal of the thyristor rectifier circuit to the internal source voltage, even when the external source voltage becomes transiently greater than the internal source voltage at the early stage of the boosting step when the booster circuit boosts the internal source voltage based on the external source voltage. This prevents the thyristor rectifier circuit from malfunctioning and turning on.

1. Field of the Invention
The present invention relates to an electro-static discharge protection circuit to protect internal circuitry from electro-static discharge (ESD).
2. Description of the Related Art
An electro-static discharge protection circuit is established between an external source voltage supply line Vcc and internal circuitry of a semiconductor integrated circuit to protect the internal circuitry against a surge current caused by electro-static discharge (ESD) applied to the external source voltage supply line Vcc. As used herein, the term "internal circuitry" means one or more circuits to be protected against electro-static discharge (ESD) by an electro-static discharge protection circuit.
Electro-static discharge protection circuits using a rectifier with thyristors are known in the art, and one such circuit was disclosed in the 2004 EOS/ESD Symposium, "ESD Protection Solution for High Voltage Technologies", (C. Principle of ESD-on-SCR). The electro-static discharge protection circuit includes a thyristor and a substrate resistance. The thyristor further includes a vertical PNP bipolar transistor and a lateral NPN bipolar transistor. Application of electro-static discharge (ESD) to the external source voltage supply line Vcc causes a current to be injected or charged into a chip capacitance. The current triggers the electro-static discharge protection circuit into an "ON" state of a thyristor mode. This electro-static discharge protection circuit is disclosed as "ESD-on-SCR (ESD-on-Silicon Controlled Rectifier)". As used herein, the term "electro-static discharge protection circuit" means this type of circuit, that is, SCR.
When the external source voltage Vcc, for example 2.5 V, is applied to the external source voltage supply line Vcc, the booster circuit boosts the internal source voltage Vdd of the internal source voltage supply line Vdd up to 23.5 V. At the early stage of the boosting step, the external source voltage Vcc can be transiently greater than the internal source voltage supply line Vdd. At this early stage of the boosting step, a current which flows from the external source voltage supply line Vcc to the internal source voltage supply line Vdd can cause a thyristor included in a protection circuit to malfunction and turn on.
In view of the foregoing, an object of the present invention is to provide an electro-static discharge protection circuit which does not have the problems described above.
Another object of the present invention is to provide a semiconductor device with an electro-static discharge protection circuit which does not have the problems described above.

Electro-static discharge protection circuit and semiconductor device having the same


One embodiment disclosed relates to a method of detecting defects in a microminiature pattern repeated over a particular surface of an object. The method includes providing an image detector capable of resolving intensity data for each pixel of an array of m×n pixels of an image projected thereupon. An area of the surface of the object is illuminated with incident electrons, radiation from the illuminated area is detected, and image data from the detected radiation is retrieved into a data processor. If necessary, the image data is rotated for alignment purposes. The scale of the image data is then adjusted such that a dimension of a cell of the repeated pattern in the image data is equivalent to a distance across an integer number of pixels of the m×n pixel array. With the scale adjusted, then features in one cell of the repeated pattern are compared with features in another cell of the repeated pattern to detect said defects.

1. Field of the Invention
The present invention relates to electron beam inspection methods and apparatus.
2. Description of the Background Art
A variety of methods have been used to examine microscopic surface structures of semiconductors. These have important applications in the field of semiconductor chip fabrication, where microscopic defects at a surface layer can make the difference between a properly functioning or non-functioning IC. For example, holes or vias in an intermediate insulating layer often provide a physical conduit for an electrical connection between two outer conducting layers. If one of these holes or vias becomes clogged with non-conductive material, this electrical connection between layers will not be established.
Automated inspection of the semiconductors is used to ensure a level of quality control in the manufacture of the integrated circuits. It is desirable to improve the collection, processing, and analysis of image obtained during the automated inspection of manufactured substrates, such as semiconductor wafers, photomask reticles, flat panel screens, and the surfaces of other objects.

Method and apparatus for electron beam inspection of repeated patterns


A mop with a cleaning head consisting of a plurality of fluid absorbent material strands connected to a handle. A wringer rod is connected at one end to a slideable, manually operated sleeve located around the handle. The rod is pivotally connected at its other end to a roller wringer. The roller wringer is of ringed or closed polygon configuration, taking its shape from a flexibly biased support member. The support member is preferably a solid rod formed in a rectangular or other polygonal shape. The support member passes through roller elements positioned one on each of the sides of the member and completely surrounding it. As the sleeve is manually pushed down the handle, the roller wringer is forced over the mop head strands, causing the support member and rollers to expand around the strands. The biased nature of the support member ultimately causes the rollers to compress the strands, squeezing the strands and moisture from them. When the roller wringer has reached the end of the mop head strands, it pivots up. Manual movement of the sleeve back up the handle towards the user draws the roller wringer over the mop head and back to the lower end of the handle. The wringer then pivots down and, through an opening in the support member, it can be repositioned on handle.

Mops have long been used as effective tools for a variety of cleaning applications. Their use for cleaning floor surfaces and for mopping and absorbing liquid from surfaces is well known. One such common mop consists of a cleaning head with a plurality of strands made of cotton, cloth, sponge-plastic, or other fluid absorbent material. An elongated handle is normally attached to one end of the cleaning head.
Mops of this type work very well when their cleaning head strands are dry. However, the mop becomes ineffective when the strands become saturated with fluid. To remedy this problem, various mops with wringer devices have evolved with features which cause the strands to be wrung out, compressed, and squeezed of fluid. For instance, U.S. Pat. No. 5,675,857 employs the use of a sleeve to wring out moisture from a mop's cleaning head. U.S. Pat. Nos. 5,724,694 and 4,809,387, disclose sleeves in combination with rollers. U.S. Pat. No. 2,820,232 simply shows the use of rollers to squeeze wet mop strand elements. These prior devices, however, have a number of disadvantages. For instance, the wringers used on these mops have either cumbersome sleeve arrangements or are highly mechanized devices. Significantly they are inefficient for the purposes for which they were designed. Many of the devices do not provide sufficient uniform pressure to the mop head strands to wring a substantial amount of the moisture from the mop head.
U.S. Pat. Nos. 3,089,171, and 4,164,800 employ a solid annular ring attached to a support rod to apply pressure completely around the mop head. But since the ring is rigid, it also does not apply enough compressive force to fully wring dry the strands of the head. Further, the internal surfaces of the ring offer substantial resistence as the ring travels down the strands of the mop head. This makes it more difficult to move the ring all the way to the end of the mop head. In addition, the flapper on the bottom of the ring, designed to allow repositioning of the ring over the mop handle when it is pulled toward the user, is inefficient and prone to dysfunction and breakage, upon extended use.


The invention relates to a method for automatic proving theorems describing physical systems in first order logic. This method is used to produce complex systems and is implemented with the aid of a computer in whose memory a theorem to be proved is represented by at least one binary decision diagram (BDD). The method seeks to reduce the BDD to a constant T, symbolizing truth, by a substitution, by constructing and exploring a search tree of possible substitutions. The tree is constructed by minimizing the branching factor and is explored by maximizing in accordance with the Shannon theory, the information gain obtained at each node of the search tree.

At present, the increasing complexity of industrial products presents numerous problems in terms of their design, realization and utilization. To create such products, the human being uses his imagination in the succession of phases up to the definitive development of these products. Some of these phases are currently assisted by machines, such as machine tools and computer-assisted design software, but this list is not exhaustive.
The intelligence that the human being proves to have for putting the succession of the various phases into proper order is based on his reasoning. Passing from one step in reasoning to the next, however rigorous it may be, is often, not to say always, somewhat subconscious, resulting from an intuitive train of thought inherent in the structure of human thinking. This has its advantage of allowing him to reach his objectives faster by ignoring what is currently considered obvious.
However, short-circuiting the fastidious processes of strict reasoning by overly frequent recourse to intuition leads to mistakes.
These mistakes can be expressed as faults in the functioning of the product made, faults which are all the harder to detect and hence eliminate, the rarer and more widely dispersed they are.


A method of and a system for stabilizing High Voltage Power Supply (HVPS) DC and AC voltages in multi-energy X-ray computed tomography scanners are provided. The method comprises generating filter ratios, computing DC and AC voltages, and feeding back the computed DC and AC voltages to the commanded voltages. The filtered ratios including an air ratio and a copper ratio are modeled as nonlinear functions of the DC and AC voltages. Computing DC and AC voltages include computing an m-ratio and an n-ratio. The parameters of the nonlinear model comprise an exponent parameter and a set of polynomial coefficients. The parameters are determined by a calibration procedure, which performs scanning at different combination of DC and AC voltages. The optimal parameters are obtained through a nonlinear least square minimization, which is solved through a brute force search over the exponent parameter and a closed form solution of the polynomial coefficients. Feeding back the computed DC and AC voltages include comparing the computed voltages with commanded voltages, integrating the difference between the computed voltages and commanded voltages, and adding the integrated voltage differences to the commanded voltages.

Various X-ray baggage scanning systems are known for detecting the presence of explosives and other prohibited items in baggage, or luggage, prior to loading the baggage onto a commercial aircraft. A common technique of measuring a material's density is to expose the material to X-rays and to measure the amount of radiation absorbed by the material, the absorption being indicative of the density. Since many explosive materials may be characterized by a range of densities differentiable from that of other items typically found in baggage, explosives are generally amenable to detection by X-ray equipment.
Most X-ray baggage scanning systems in use today are of the "line scanner" type and include a stationary X-ray source, a stationary linear detector array, and a conveyor belt for transporting baggage between the source and detector array as the baggage passes through the scanner. The X-ray source generates an X-ray beam that passes through and is partially attenuated by the baggage and is then received by the detector array. During each measuring interval the detector array generates data representative of the integral of density of the planar segment of the baggage through which the X-ray beam passes, and this data is used to form one or more raster lines of a two-dimensional image. As the conveyor belt transports the baggage past the stationary source and detector array, the scanner generates a two-dimensional image representative of the density of the baggage, as viewed by the stationary detector array. The density image is typically displayed for analysis by a human operator.
Techniques using dual energy X-ray sources are known for providing additional information about a material's characteristics, beyond solely a density measurement. Techniques using dual energy X-ray sources involve measuring the X-ray absorption characteristics of a material for two different energy levels of X-rays. Depending upon the calibration of the scanner, dual energy measurements provide an indication of dual parameters of the material being scanned. For example, at one calibration setting, the dual parameters can be chosen to be the material's effective atomic number (Z is denoted as "effective atomic number") and the material's density. At another calibration setting, the dual parameters can be chosen to be the material's Photoelectric coefficients and the material's Compton coefficients. At yet another calibration setting, the dual parameters can be chosen to be an amount of a first material present (e.g., plastic) and an amount of a second material present (e.g., aluminum). Dual energy X-ray techniques for energy-selective reconstruction of X-ray Computer Tomography (hereinafter referred to as CT) images are described, for example, in Robert E. Alvarez and Albert Macovski, "Energy-selective Reconstructions in X-ray Computerized Tomography," Phys. Med. Biol. 1976, Vol. 21, No. 5, 733–744; and U.S. Pat. Nos. 4,029,963 and 5,132,998. One algorithm used to generate such dual parameters from dual energy X-ray projection data is known as the Alvarez/Macovski Algorithm (hereinafter referred to as AMA). Others are known in the art.
One proposed use for such dual energy techniques has been in connection with a baggage scanner for detecting the presence of explosives in baggage. Explosive materials are generally characterized by a known range of atomic numbers and are therefore amenable to detection by such dual energy X-ray sources. One such dual energy source is described in U.S. Pat. No. 5,661,774, entitled "Improved Dual Energy Power Supply," assigned to the present assignee and incorporated herein by reference. Other dual energy sources are known in the art.
Most explosives capable of significantly damaging an aircraft are sufficiently large in length, width, and height so as to be readily detectable by an X-ray scanner system regardless of the explosive's orientation within the baggage. Plastic explosives, however, present a particular challenge to baggage scanning systems. Due to their moldable nature, plastic explosives may be formed into geometric shapes that are difficult to detect. A plastic explosive powerful enough to damage an aircraft may be formed into a relatively thin sheet that is extremely small in one dimension and is relatively large in the other two dimensions. The detection of plastic explosives may be difficult because it may be difficult to see the explosive material in the image, particularly when the material is disposed so that the thin sheet is parallel to the direction of the X-ray beam as the sheet passes through the system.
Thus, detection of suspected baggage requires very attentive operators. The requirement for such attentiveness can result in greater operator fatigue, and fatigue as well as any distractions can result in a suspected bag passing through the system undetected. Accordingly, a great deal of effort has been made to design a better baggage scanner. Such designs, for example, have been described in U.S. Pat. No. 4,759,047 (Donges et al.); U.S. Pat. No. 4,884,289 (Glockmann et al.); U.S. Pat. No. 5,132,988 (Tsutsui et al.); U.S. Pat. No. 5,182,764 (Peschmann et al.); U.S. Pat. No. 5,247,561 (Kotowski); U.S. Pat. No. 5,319,547 (Krug et al.); U.S. Pat. No. 5,367,552 (Peschmann et al.); U.S. Pat. No. 5,490,218 (Krug et al.) and German Offenlegungsschrift DE 31 503 06 A1 (Heimann GmbH).
At least one of these designs, described in U.S. Pat. No. 5,182,764 (Peschmann et al.) and U.S. Pat. No. 5,367,552 (Peschmann et al.) (hereinafter the '764 and '552 patents), has been commercially developed and is referred to hereinafter as the "Invision Machine." The Invision Machine includes a CT scanner of the third generation type, which typically includes an X-ray source and an X-ray detector system secured respectively to diametrically opposite sides of an annular-shaped platform or disk. The disk is rotatably mounted within a gantry support so that in operation the disk continuously rotates about a rotation axis while X-rays pass from the source through an object positioned within the opening of the disk to the detector system.
The detector system can include a linear array of detectors disposed as a single row in the shape of a circular arc having a center of curvature at the focal spot of the X-ray source, i.e., the point within the X-ray source from which the X-rays emanate. The X-ray source generates a fan shaped beam, or fan beam, of X-rays that emanates from the focal spot, passes through a planar imaging field, and is received by the detectors. The CT scanner includes a coordinate system defined by X-, Y- and Z-axes, wherein the axes intersect and are all normal to one another at the center of rotation of the disk as the disk rotates about the rotation axis. This center of rotation is commonly referred to as the "isocenter." The Z-axis is defined by the rotation axis and the X- and Y-axes are defined by and lie within the planar imaging field. The fan beam is thus defined as the volume of space defined between a point source, i.e., the focal spot, and the receiving surfaces of the detectors of the detector array exposed to the X-ray beam. Because the dimension of the receiving surfaces of the linear array of detectors is relatively small in the Z-axis direction the fan beam is designed to be relatively thin in the Z-axis direction. Each detector generates an output signal representative of the intensity of the X-rays incident on that detector. Since the X-rays are partially attenuated by all the mass in their path, the output signal generated by each detector is representative of the density of all the mass disposed in the imaging field between the X-ray source and that detector.
As the disk rotates, the detector array is periodically sampled, and for each measuring interval each of the detectors in the detector array generates an output signal representative of the density of a portion of the object being scanned during that interval. The collection of all of the output signals generated by all the detectors in a single row of the detector array for any measuring interval is referred to as a "projection," or equivalently as a "view," and the angular orientation of the disk (and the corresponding angular orientations of the X-ray source and the detector array) during generation of a projection is referred to as the "projection angle." At each projection angle, the path of the X-rays from the focal spot to each detector, called a "ray," increases in cross section from an appropriate point source to the receiving surface area of the detector, and thus is thought to magnify the density measurement because the receiving surface area of the detector area is larger than any cross sectional area of the object through which the ray passes.
As the disk rotates around the object being scanned, the scanner generates a plurality of projections at a corresponding plurality of projection angles. Using well-known algorithms, a CT image of the object may be generated from all the projection data collected at each of the projection angles. The CT image is representative of the density of a two dimensional "slice" of the object through which the fan beam has passed during the rotation of the disk through the various projection angles. The resolution of the CT image is determined in part by the width of the receiving surface area of each detector in the plane of the fan beam, the width of the detector being defined herein as the dimension measured in the same direction as the width of the fan beam, while the length of the detector is defined herein as the dimension measured in a direction normal to the fan beam parallel to the rotation or Z-axis of the scanner. In general, the resolution of the CT image is inversely proportional to the width of the receiving surface of each detector in the plane of the fan beam.
Referring to the drawings, FIGS. 1, 2 and 3 show perspective, end cross-sectional and radial cross-sectional views, respectively, of a typical baggage scanning system 100, which includes a conveyor system 110 for continuously conveying baggage or luggage 112 in a direction indicated by arrow 114 through a central aperture of a CT scanning system 120. The conveyor system includes motor driven belts for supporting the baggage. Conveyer system 110 is illustrated as including a plurality of individual conveyor sections 122; however, other forms of conveyor systems may be used.
The CT scanning system 120 includes an annular shaped rotating platform, or disk, 124 disposed within a gantry support 125 for rotation about a rotation axis 127 (shown in FIG. 3) that is preferably parallel to the direction of travel 114 of the baggage 112. Disk 124 is driven about rotation axis 127 by any suitable drive mechanism, such as a belt 116 and motor drive system 118, or other suitable drive mechanism, such as the one described in U.S. Pat. No. 5,473,657 issued Dec. 5, 1995 to Gilbert McKenna, entitled "X-ray Tomographic Scanning System," which is assigned to the present assignee and, which is incorporated herein in its entirety by reference. Rotating platform 124 defines a central aperture 126 through which conveyor system 110 transports the baggage 112.
The system 120 includes an X-ray tube 128 and a detector array 130 which are disposed on diametrically opposite sides of the platform 124. The detector array 130 is preferably a two-dimensional array, such as the array described in U.S. Pat. No. 6,091,795 entitled, "Area Detector Array for Computed Tomography Scanning System." Other suitable arrays are known in the art. The system 120 further includes a data acquisition system (DAS) 134 for receiving and processing signals generated by detector array 130, and an X-ray tube control system 136 for supplying power to, and otherwise controlling the operation of, X-ray tube 128. The system 120 is also preferably provided with a computerized system (not shown) for processing the output of the data acquisition system 134 and for generating the necessary signals for operating and controlling the system 120. The computerized system can also include a monitor for displaying information including generated images. System 120 also includes shields 138, which may be fabricated from lead, for example, for preventing radiation from propagating beyond gantry 125.
The X-ray tube 128 may generate a pyramidally shaped beam, often referred to as a "cone beam," 132 of X-rays that pass through a three dimensional imaging field, through which conveying system 110 transports baggage 112. After passing through the baggage disposed in the imaging field, detector array 130 receives cone beam 132 and generates signals representative of the densities of exposed portions of baggage 112. The beam therefore defines a scanning volume of space. Platform 124 rotates about its rotation axis 127, thereby transporting X-ray source 128 and detector array 130 in circular trajectories about baggage 112 as the conveyor system 110 continuously transports baggage through central aperture 126, so as to generate a plurality of projections at a corresponding plurality of projection angles. When dual energy scanning mode is configured, the control system 136 supplies modulated high voltages with respect to alternating projection angles to the X-ray tube 128. The detector array 130 then receives data corresponding to high-energy and low-energy X-ray spectra in alternating projection angles.
Post-reconstruction analysis and pre-reconstruction analysis are the two prior art techniques generally recognized for using dual energy X-ray sources in materials analysis (e.g., in a baggage scanner for detecting the presence of explosives in baggage). In post-reconstruction analysis, the signal flow is as shown in FIG. 4. The scanner 120 is typically similar to the one shown in FIGS. 1–3 and has an X-ray source capable of producing a fan or cone beam at two distinct energy levels (i.e., dual energy). The DAS 134 gathers signals generated by detector array 130 at discrete angular positions of the rotating platform 124, and passes the signals to the pre-processing unit 206. The pre-processing unit 206 re-sorts the data it receives from the DAS 134 in order to optimize the sequence for the subsequent mathematical processing. The pre-processing unit 206 also corrects the data from the DAS 134 for detector temperature, intensity of the primary beam, gain and offset, and other deterministic errors. Finally, the pre-processing unit 206 extracts data corresponding to high-energy views and routes it to a high-energy path 208, and routes the data corresponding to low-energy views to a low-energy path 210. A first reconstruction computer 218 receives the projection data from the high-energy path 208 and generates a CT image IH 226 corresponding to the high-energy series of projections. A second reconstruction computer 220 receives the projection data from the low-energy path 210 and generates a CT image IL 224 corresponding to the low-energy series of projections. A post-processing unit 230 receives the high-energy CT image 226 and the low-energy CT image 224 and performs voxel-by-voxel processing to yield the effective atomic number (Z is denoted as effective atomic number) image Iz 232. The Z image 232 and the high-energy CT image 226 can be provided to operators on a display 240, and both images can be used for automatic explosive detection in 238 as well. The images from the post-reconstruction analysis usually do not yield accurate estimates of the material's effective atomic number, and suffer low SNR (Signal to Noise Ratio) and many artifacts as well.
In pre-reconstruction analysis, the signal flow is as shown in FIG. 5. As is described herein for pre-reconstruction analysis, the dual energy decomposition computer 212 receives the projection data on the high-energy path 208 and the low-energy path 210 and performs the Alvarez/Macovski Algorithm to produce a first stream of projection data Ac 214, which is dependent on a first parameter of the material being scanned, and a second stream of projection data Ap 216, which is dependent on a second parameter of the material scanned. The first material parameter is often the Compton coefficient ac, and the second material parameter is often the photoelectric coefficient ap. A first reconstruction computer 219 receives the first stream of projection data 214 and generates a Compton image Ic 227 from the series of projections corresponding to the first material parameter. A second reconstruction computer 221 receives the second stream of projection data 216 and generates a photoelectric image Ip 225 from the series projections corresponding to the second material parameter. The third reconstruction computer 218 receives the stream of projection data 208 and generates a high-energy CT image IH 226. The two images 225 and 227 are processed in the post-processing unit 230 to yield a Z image Iz 232. The High-energy CT image 226 and the Z image 232 can be provided to operators on a display 240, and both images can be used for automatic explosive detection in detection unit 238 as well. The pre-reconstruction analysis yields better estimates of material's effective atomic number than the post-reconstruction analysis. However the pre-reconstruction analysis requires one more reconstruction computer than the post-reconstruction analysis.
Various approaches have been used for decomposition of the input projection data PL and PH into Compton projections Ac and photoelectric projections Ap. For example, the AMA method approximates PL and PH using polynomial functions in terms of Ac and Ap. The coefficients of the polynomial functions are determined through a calibration procedure as follows. By measuring the projection values of the combination of various thicknesses of two known materials, the coefficients can be calculated through a polynomial least squares fitting between the measured and modeled PL and PH. Once the coefficients of the polynomial functions are determined, the decomposition of the Compton and Photoelectric projections Ac and Ap from projections PL and PH is usually solved using the Newton-Raphson method.
Another prior art method of performing decomposition is the direct approximation method, discussed in L. A. Lehmann, R. E. Alvarez, A. Macovski, W. R. Brody, N. J. Pelc, S. J. Riederer, and A. L. Hall, Generalized Image Combinations In Dual KVP Digital Radiography, Med. Phys. 8, 659–667 (1981). In the direct approximation method, Ac and Ap are approximated as polynomial functions in terms of PL and PH. The coefficients of the polynomial functions in the direct approximation method are determined through a calibration procedure by measuring the projection values of the combination of various thicknesses of two known materials.
In yet another prior art method, decomposition is accomplished using iso-transmission lines, described K. Chuang and H. K. Huang, A Fast Dual-Energy Computational Method Using Isotransmission Lines and Tables, Med. Phys. 14, 186–192 (1987). According to this method, for a given projection value, an iso-transmission line is represented by a linear equation in two basis functions. The iso-transmission line method requires a large amount of calibration data. Further, the iso-transmission line becomes increasingly non-linear as the projection value increases. In such a situation, the linear equations are not valid and the method causes large approximation errors.
CT images and Z (effective atomic number) images can be generated from both the pre-reconstruction and post-reconstruction analysis. The CT images measure the CT number of scanned materials, which approximates the density of the materials; and the Z image measures the effective atomic number of the scanned materials. The measurements of CT number and Z are used for automatic explosive detection. However the measurements vary over time on a scanner due to HVPS (High Voltage Power System) drifts and vary across scanners due to the components variations in the x-ray beam lines. Such measurement variations interfere with the automatic detection of explosives, resulting in a degraded detection rate and/or an increased false alarm rate.
The cause of the voltage drift in the HVPS is due to the nonlinear thermal effect of some of its components in the feedback control loop. This results in inaccurate measurements of the HVPS output voltages in its feedback control circuit. In other words, the measurements of the HVPS output voltages using its internal circuit do not reflect the actual output voltages.
The HVPS described in U.S. Pat. No. 5,661,774, entitled "Improved Dual Energy Power Supply," assigned to the present assignee and incorporated herein by reference, generates a high-energy voltage and low-energy voltage in alternating views by superimposing a AC (alternating current) voltage on a DC (direct current) voltage. Therefore the generated high-energy voltage and low-energy voltage are coupled functions of the DC and AC voltages: the changes in the DC voltage only, the AC voltage only, or both DC and AC voltages, result in the changes of both high-energy and low-energy X-ray spectra.
In U.S. Pat. No. 6,748,043 by John M. Dobbs assigned to the present assignee and incorporated herein by reference, a KV-meter is used to stabilize the CT numbers in a single-energy CT scanner. The KV-meter includes a principal detector and an auxiliary detector. The auxiliary detector is covered with an absorber that removes a large fraction of the lower-energy X-ray photons in the incident X-ray beam. The ratio between the X-ray intensities measured by the principal and auxiliary detectors is used as a reference for stabilizing the HVPS's voltage, hence the measured CT numbers. However, the method is not directly applicable to the dual-energy HVPS, since the high-energy voltage or low-energy X-ray spectrum is determined by both the DC voltage and AC voltage, not by the DC voltage or AC voltage alone.
In U.S. application Ser. No. 10/899,775, filed on Jul. 17, 2004, by Ram Naidu, et al., entitled "Method of and apparatus for X-ray spectral correction in multi-energy computed tomography," and assigned to the present assignee and incorporated herein by reference, an X-ray spectral correction method using a copper filter mounted on one of the corner of the two-dimensional detector array is used to compensate the Z images and CT images for the HVPS drift and the scanner beamline variation. A block diagram for describing such a system is illustrated in FIG. 6, which can be used with a scanner of the type depicted in FIGS. 1–3. Pre-determined DC voltage VDC and AC voltage VAC are commanded into HVPS 136, which in turn applies its output to X-ray tube 128, the latter yielding X-ray beam(s) of both desired high-energy and low-energy X-ray spectra. The detector array 130 with a mounted copper filter converts the X-ray intensities, which are attenuated by the scanned objects inside the scanner, into corresponding current. DAS 134 then integrates and digitizes the measured current into a scaled version of the X-ray photon energy. The DAS outputs are then used by the dual-energy decomposition and reconstruction system 301 to generate high-energy CT and Z (effective atomic number) images. Spectral correction 310 then compensates and outputs the CT images IH and Z images IZ for the spectral variation inferred from the measured copper ratios. However, the method uses a first-order Taylor series expansion approximation, and can only track and compensate for the HVPS voltage drifts which are less than some range, e.g., 10%. When the HVPS voltage drifts are outside such a range, the method yields large errors in the estimates of CT numbers and effective atomic numbers of scanned materials.

Method of and system for stabilizing high voltage power supply voltages in multi-energy computed tomography


Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for intelligently cancelling user inputs. In one aspect, a requests input by a user is received by a dialog engine. A prompt or notification regarding the request is output by the dialog engine. That the user has taken an action in response to the prompt or notification is determined by the dialog engine. Based on the action taken by the user, that the response corresponds to a potential cancellation command is determined by the dialog system.

User devices, such as mobile telephones or computers, implement a variety of techniques through which users can find information or perform actions. For example, some user devices implement spoken dialog systems, which may be able to audibly provide answers to questions provided by users or to perform actions based on user commands.


Provided is a slider for slide fastener. A pull-tab has a cam portion, and when the pull-tab is rotated from a laid-down state where the pull-tab is laid down toward one side of a slider main body to an erected state, the pull-tab is urged with using the cam portion in a direction in which the pull-tab reruns to the laid-down state by an elastic force of a spring part. The slider has a restraining part configured to prevent the pull-tab from rotating further from the erected state and prevent the pull-tab from being laid down toward the other side of the slider main body.

A slider for slide fastener of the related art includes a slider main body, a pull-tab attached to a pair of right and left pull-tab attachment posts which are erected on the upper surface of an upper blade of the slider main body, and a spring part disposed between the pair of right and left pull-tab attachment posts and having a locking claw at one end thereof (e.g. see Patent Document 1).
In addition, in the related art, there is a slider for slide fastener that is configured such that the pull-tab is maintained in the laid-down state with respect to the slider main body (e.g. see Patent Document 2). In the slider for slide fastener disclosed in Patent Document 2, a pin is fitted into bearings which protrude from an upper blade of the slider main body through the pull-tab, and a hinge spring is provided on this pin such that the pull-tab is always maintained in the laid-down state by the elastic force of the hinge spring. In addition, the slider is provided with the slider main body, a locking claw with a spring, the pull-tab provided with a cam surface, a leaf spring which applies an elastic force to the cam surface, and a cover body engaged with the slider main body to accommodate the leaf spring. The pull-tab is always maintained in the laid-down state by the elastic force of the leaf spring acting on the cam surface.


This invention accomplishes these and other objectives with a wind wheel (1) having at least one planetary gear wheel (10) affixed rigidly to a wind-wheel axle (2) from which gear trains for each of a plurality of wind-wheel plates (9) are rotated to maximum plate frontage in wind flow (30) by gear belts (21) intermediate the gear trains and axes of the plurality of wind-wheel plates. The gear trains each have a second gear wheel (12) with a 0.50-to-1.0 gearing ratio to the planetary gear, a third gear wheel (15) with a 2.0-to-1.0 gearing ratio to the planetary gear, a first gear-belt wheel (18) extended concentrically from a side of the third gear wheel and having a 0.60-to-1.0 gearing ratio to the planetary gear and, a second gear-belt wheel (20) having a gearing ratio that is equal to the first gear-belt wheel. The plurality of wind-wheel plates with corresponding drive trains is preferably six but can be any number appropriate for design preferences. The wind wheel can be structured with either a horizontal axis or a vertical axis with appropriate structural modifications. Directional control can be provided by eccentric positioning of the wind-wheel axis in order for the wind-wheel plates to have a weather-vane effect.

This invention relates to wind wheels and in particular to wind wheels having paddle plates which are rotated to face wind in wind-direction travel and rotated edgewise in windward travel circumferentially.
For centuries ways have been sought and devised to make paddle plates of a wind wheel face wind in its direction of travel and avoid facing the wind in return portions of rotational travel. None, however, have provided the wind-use efficiency and low cost of rotational facing of paddle plates to face wind in a manner taught by this invention.
Different but related wind wheels are described in the following patent documents. U.S. Pat. No. 4,507,049, issued to Strandgren, taught a wind wheel with wing-shaped paddles that were positioned to utilize air foil for rotation. Japanese Patent Disclosure Number 57-186069, dated Nov.16, 1982, described a wind wheel with paddle plates rotated by shafts extended from a worm type of planetary gear. Japanese Patent Number 61-38171, issued on Feb.24, 1986 taught a hydraulic means for positioning wind buckets or paddles in and out of the path of wind in rotational travel of a wind wheel. French Patent Number 2,291,379 taught a wind turbine with wing-shaped airfoils that were rotated with central gearing from-foil-to-foil for positioning the airfoils optimally for utilization of air current to rotate the wind turbine. U.S. Pat. No. 1,790,175, issued to Spencer, described a wind wheel with paddle plates rotated by shafts extended from a worm type of planetary gear in a slightly different manner than taught by the above Japanese Patent Disclosure Number 57-186068. U.S. Pat. No. 1,618,549, issued to O'Toole taught rotational paddle plates that were sprocket driven with a sprocket gear affixed to a rigid axle of a wind wheel. In 1867, U.S. Pat. No. 69,374, issued to Thornton, taught a wind wheel with a stationary planetary sprocket gear that rotated sprocket gears on axles to which paddle plates were attached.
Positioning a return-rotational portion of a wind wheel below or behind a surface was taught by other patents to direct wind against only a portion of the wind wheel that traveled with the wind. Included in this type of wind wheel were U.S. Pat. No. 5,472,311, that was issued to Davis; U.S. Pat. No. 5,348,443, that was issued to Roberts; and U.S. Pat. No. 4,678,394, that was issued to Willoughby.

Wind wheel with rotationally faced plates


The present invention relates to a process for obtaining the hydrocarbon from a hydrocarbon-rich gel based on an ionic surfactant by treatment of the gel with a laminar mineral.

Storage and transportation of liquid hydrocarbons, for example fuels, via road, rail and on the waterways present a considerable potential hazard. Thus, for example, the high flammability and explosiveness in mixtures with air has led in the past to serious accidents which have caused considerable damage. Serious ecological damage moreover is constantly arising due to fuels being discharged from leaking storage or transportation tanks.
It is already known that hydrocarbons can be converted into so-called hydrocarbon-rich gels. These are understood as meaning a system which consists of polyhedrons which are formed from surfactant and are filled with hydrocarbon, water forming a continuous phase in the narrow interstices between the polyhedrons (Angew. Chem. 100 933 (1988) and Ber. Bunsenges. Phys. Chem. 92 1158 (1988)).
Hydrocarbon-rich gels are distinguished by the occurrence of a yield value. This yield value is reached when the gel no longer withstands a stress imposed on it (shear, deformation) and starts to flow. Below the yield value, the gel structures have the properties of solids and obey Hooke's law. Above the yield value, in the ideal case, the system is equivalent to a Newtonian fluid. This means that although hydrocarbon-rich gels can be pumped in a simple manner, because of their properties as solids they cannot flow in the state of rest.
Provided that a process is available which allows the hydrocarbon to be recovered, hydrocarbon-rich gels are an outstanding form of storage and transportation. They cannot be discharged from defective storage or transportation tanks and danger to the environment is virtually excluded.
It has now been found, surprisingly, that the structure of hydrocarbon-rich gels which contain ionic surfactants can be broken down with the aid of laminar minerals and the hydrocarbon can be recovered.

Process for obtaining the hydrocarbon from a hydrocarbon-rich gel


An apparatus comprising a stake with a first end portion configured to support a component and a second end portion, an anti-twist device formed on the second end portion, and a stabilizing component formed on the second end portion between the anti-twist device and the first end portion. Corresponding systems and methods also are disclosed.

This disclosure relates generally to a ground anchoring apparatus, and more particularly to a ground anchoring apparatus for posts.
Ground anchoring apparatuses for mailboxes, signs, etc. are generally known. An anchoring apparatus has various features including a post. It is problematic when the post lacks stabilization when in use, as is often the case if the post is not mounted in a cement base.
It would be useful to develop a ground anchoring apparatus with improved stability.

Anchoring apparatus, system, and methods of making and using same


A decoding apparatus is provided. The decoding apparatus has a first decoding part for decoding a code word obtained by encoding an input signal using a Code-Excited Linear Prediction encoding method. A second decoding part decodes a code word obtained by encoding a signal with an encoding method other than the Code-Excited Linear Prediction encoding method. A rising-transition detection and notification part has a detection part that detects the existence of a rising-transition of amplitude of the input signal based on time variation of a gain of excitation vectors obtained by the first decoding part, and a notification part that notifies the second decoding part that the rising-transition of the amplitude exists.

1. Field of the Invention
The present invention relates to a decoding apparatus, an encoding apparatus, a decoding method and an encoding method. More particularly, the present invention relates to a decoding apparatus, and an encoding apparatus in which an input signal is compressed highly-efficiently and encoded or decoded, and a decoding method and an encoding method in which the input signal is compressed highly-efficiently and encoded or decoded.
2. Description of the Related Art
Presently, there are various kinds of encoding and decoding apparatuses and methods that highly-efficiently compress speech and acoustic signals. One of such encoding and decoding methods is a scalable encoding method in which a part of an encoded sequence can be decoded according to a required quality or status of a network because it has scalable encoding characteristics. The scalable encoding process has an architecture to successively encode an input signal in such a way that an error signal between the input signal and a decoded signal of a lower layer encoder is further encoded by a higher layer encoder. The lowest layer is called a core layer and higher layers than the lowest layer are called enhancement layers. An example of a representative scalable encoding method is described in ISO/IEC14496-3, which is called MPEG-4 Audio, standardized by ISO/IEC. FIG. 1 shows a block diagram of the scalable encoding process. In FIG. 1, the Code-Excited Linear Prediction (CELP) encoding method, a parametric encoding method, such as for example, the Harmonic Vector Excitation Coding (HVXC) method and the Harmonic Individual Line with Noise (HILN) method or, a transform coding method, such as, for example, the Advanced Audio Coding (AAC) method and the Transform Domain Weighted Interleave Vector Quantization (TwinVQ) method is used in a core layer encoder 101. The encoders that perform the transform coding method are used in enhancement layer encoders 104.
FIG. 2 shows a block diagram of a CELP encoder. The CELP encoder as shown in FIG. 2 mainly has a linear prediction analyzer 201, a linear prediction coefficient quantization part 202, a linear prediction synthesis filter 203, an adaptive code book 204, a fixed code book 206, a perceptual weighting filter 208, a controller 209, an adder 212 and a subtracter 213. An input signal 200 is supplied to the CELP encoder every 5 to 40 ms and linear prediction analysis is performed on the input signal by the linear prediction analyzer 201. Then, the linear prediction coefficients 210 obtained by the linear prediction analysis are quantized by the linear prediction coefficient quantization part 202. The linear prediction synthesis filter 203 is constructed using the quantized linear prediction coefficients obtained as described above. Excitation vectors 211 to drive the linear prediction synthesis filter 203 are stored in the adaptive code book 204. The adaptive code book excitation vector is output from the adaptive code book 204 and the fixed code book excitation vector is output from the fixed code book 206 according to an output signal from the controller 209. Each of the vectors is multiplied by an adaptive code book gain 205 or a fixed code book gain 207, respectively. Then, the excitation vector 211 is generated at an output of an adder 212 by means of adding the results multiplied by each of the gains. The excitation vector 211 generated as described above is supplied to the linear prediction synthesis filter 203. An output signal of the linear prediction synthesis filter 203 is a synthesis signal, and an error signal between the input signal and the synthesis signal is calculated by the subtracter 213 and then, the error signal is supplied to the perceptual weighting filter 208. The perceptual weighting filter 208 supplies the perceptually weighted error signal to the controller 209. The controller 209 searches the excitation vector 211 so that the power level of the perceptually weighted error signal has minimum value and then, determines the adaptive code book gain 205 and the fixed code book gain 207 using the selected adaptive code book excitation vector and the selected fixed code book excitation vector, respectively, by the searches so that the power level of the perceptually weighted error signal has minimum value.
FIG. 3 shows a block diagram of a CELP decoder 300. In the decoder 300 as shown in FIG. 3, the coefficients for a linear prediction synthesis filter 305, an adaptive code book 301, an adaptive code book gain 302, a fixed code book 303, and a fixed code book gain 304 are extracted from a code word sequence 311. The adaptive code book excitation vector and the fixed code book excitation vector are respectively multiplied by each of the gains and then, they are added by the adder 307 and then, the signal is an excited vector 306. The linear prediction synthesis filter 305 is driven by the excitation vector 306 and a decoded signal 312 is supplied as an output signal.
On the other hand, FIG. 4 shows an encoder 400 for transform coding. The encoder 400 mainly has an orthogonal transformation part 401, a transform coefficient quantization part 402 and a quantized transform coefficient encoding part 403. The transform coefficients 405 are calculated by performing the orthogonal transform for the input signal at the orthogonal transformation part 401. The transform coefficients 405 are quantized by the transform coefficient quantization part 402 and then, the quantized transform coefficients 406 are encoded to an encoded code sequence 407 by the quantized transform coefficient encoding part 403.
FIG. 5 shows a block diagram of a decoder 500 for decoding a transform-encoded code sequence 504. In the decoder as shown in FIG. 5, the encoded code sequence 504 is decoded to the quantized transform coefficients by the quantized transform coefficient decoding part 501 and then, the quantized transform coefficients are de-quantized to the transform coefficients by the transform coefficient de-quantization part 502. The transform coefficients obtained as described above are inverse-orthogonally-transformed to a decoded signal by the inverse orthogonal transformation part 503.
As described above, in the transform coding, the input signal in the time domain is orthogonally transformed into the coefficients in the frequency domain and then, the quantization and the encoding are performed. Therefore, when the encoded code sequence is inversely-transformed into the signal in the time domain, quantization noise that is generated by the quantization in the frequency domain spreads over a whole transform block (that is an unit of the transform coding) at approximately the same level. Therefore, if there is steep rising-transition of amplitude, which is so called 'attack', in a part of an input signal within the transform block, a pre-echo that is a jarring noise will occur at a part prior to the steep rising-transition of the amplitude. For example, if a transform block length is long, the interval in which the pre-echo occurs is also long. Therefore, the subjective quality is further degraded. When the transform coding is used in the scalable encoding as described above, the same problem as the problem generated by the transform coding arises.
To solve this problem, a technology of an adaptive block length conversion is used in the MPEG-4 Audio (ISO/IEC14496-3) as described above. In the technology, if there is a steep rising-transition of the amplitude in the input signal, a short transform block is used and, if there is not a steep rising-transition of the amplitude in the input signal, a long transform block is used. However, it is necessary to detect whether a steep rising-transition of the amplitude in the input signal exists or not in order to perform switching of the length. There is an example of such a detection method below. At first, the input signal is divided into the transform blocks and a Fourier transformation is performed on the transform blocks. Next, the obtained Fourier transform coefficients are divided to some frequency bands. Then, a parameter called perceptual entropy is calculated based on a signal to masking ratio (SMR) that is a ratio between the minimum audible noise calculated using a psychoacoustic model and the input signal power for each of the frequency bands. The steep rising-transition of the amplitude is detected by comparing the perceptual entropy with a predetermined threshold value. This method is used in the scalable encoding in the MPEG-4 Audio (ISO/IEC14496-3).
However, in the prior art method as described above, the length of the transform block is only adjusted to become short in order to shorten the interval in which the pre-echo exists. Further, because the transform block length varies, supplementary information that indicates the transform block length is required in order to decode the encoded code sequence at the decoding side. Therefore, the structure of the system becomes complex.

Encoding and decoding method and apparatus using rising-transition detection and notification


The film acoustically-coupled transformer (FACT) has a first and second decoupled stacked bulk acoustic resonators (DSBARs). Each DSBAR has a lower film bulk acoustic resonator (FBAR), an upper FBAR atop the lower FBAR, and an acoustic decoupler between them FBARs. Each FBAR has opposed planar electrodes and a piezoelectric element between the electrodes. A first electrical circuit interconnects the lowers FBAR of the first DSBAR and the second DSBAR. A second electrical circuit interconnects the upper FBARs of the first DSBAR and the second DSBAR. In at least one of the DSBARs, the acoustic decoupler and one electrode of the each of the lower FBAR and the upper FBAR adjacent the acoustic decoupler constitute a parasitic capacitor. The FACT additionally has an inductor electrically connected in parallel with the parasitic capacitor. The inductor increases the common-mode rejection ratio of the FACT.

Transformers are used in many types of electronic device to perform such functions as transforming impedances, linking single-ended circuitry with balanced circuitry or vice versa and providing electrical isolation. However, not all transformers have all of these properties. For example, an autotransformer does not provide electrical isolation.
Transformers operating at audio and radio frequencies up to VHF are commonly built as coupled primary and secondary windings around a high permeability core. Current in the windings generates a magnetic flux. The core contains the magnetic flux and increases the coupling between the windings. A transformer operable in this frequency range can also be realized using an optical-coupler. An opto-coupler used in this mode is referred to in the art as an opto-isolator.
In transformers based on coupled windings or opto-couplers, the input electrical signal is converted to a different form (i.e., a magnetic flux or photons) that interacts with an appropriate transforming structure (i.e., another winding or a light detector), and is re-constituted as an electrical signal at the output. For example, an opto-coupler converts an input electrical signal to photons using a light-emitting diode. The photons pass through an optical fiber or free space that provides isolation. A photodiode illuminated by the photons generates an output electrical signal from the photon stream. The output electrical signal is a replica of the input electrical signal.
At UHF and microwave frequencies, coil-based transformers become impractical due to such factors as losses in the core, losses in the windings, capacitance between the windings, and a difficulty to make them small enough to prevent wavelength-related problems. Transformers for such frequencies are based on quarter-wavelength transmission lines, e.g., Marchand type, series input/parallel output connected lines, etc. Transformers also exist that are based on micro-machined coupled coils sets and are small enough that wavelength effects are unimportant. However such transformers have issues with high insertion loss.
All the transformers just described for use at UHF and microwave frequencies have dimensions that make them less desirable for use in modern miniature, high-density applications such as cellular telephones. Such transformers also tend to be high in cost because they are not capable of being manufactured by a batch process and because they are essentially an off-chip solution. Moreover, although such transformers typically have a bandwidth that is acceptable for use in cellular telephones, they typically have an insertion loss greater than 1 dB, which is too high.
Opto-couplers are not used at UHF and microwave frequencies due to the junction capacitance of the input LED, non-linearities inherent in the photodetector, limited power handling capability and insufficient isolation to give good common mode rejection.
Above-mentioned U.S. patent application Ser. No. 10/699,481, of which this disclosure is a continuation-in-part, discloses a film acoustically-coupled transformer (FACT) based on decoupled stacked bulk acoustic resonators (DSBARs). A DSBAR is composed of a stacked pair of film bulk acoustic resonators (FBARs) and an acoustic decoupler between the FBARs. FIG. 1A schematically illustrates an embodiment 100 of such FACT. FACT 100 has a first decoupled stacked bulk acoustic resonator (DSBAR) 106 and a second DSBAR 108 suspended above a cavity 104 in a substrate 102. DSBAR 106 has a lower FBAR 110, an upper FBAR 120 stacked on lower FBAR 110, and an acoustic coupler 130 between them, and DSBAR 108 has a lower FBAR 150, an upper FBAR 160 stacked on lower FBAR 150, and an acoustic coupler 170 between them. Each of the FBARs has opposed planar electrodes and a piezoelectric element between the electrodes. For example, FBAR 110 has opposed planar electrodes 112 and 114 with a piezoelectric element 116 between them.
FACT 100 additionally has a first electrical circuit 141 interconnecting the lower FBAR 110 of DSBAR 106 and the lower FBAR 150 of DSBAR 108 and a second electrical circuit 142 interconnecting the upper FBAR 120 of DSBAR 106 and the upper FBAR 160 of DSBAR 108.
In the embodiment of the above-described FACT shown in FIG. 1A, electrical circuit 141 connects lower FBARs 110 and 150 in anti-parallel and to terminals 143 and 144 and electrical circuit 142 connects upper FBARs 120 and 160 in series between terminals 145 and 146. In the example shown, electrical circuit 142 additionally has a center-tap terminal 147 connected to electrodes 122 and 162 of upper FBARs 120 and 160, respectively. This embodiment has a 1:4 impedance transformation ratio between electrical circuit 141 and electrical circuit 142 or a 4:1 impedance transformation ratio between electrical circuit 142 and electrical circuit 141.
In other embodiments, electrical circuit 141 electrically connects the lower FBARs 110 and 150 either in anti-parallel or in series, and electrical circuit 142 electrically connects the upper FBARs either in anti-parallel or in series.
All embodiments of the above-described FACT are small in size, are capable of linking single-ended circuitry with balanced circuitry or vice versa, and provide electrical isolation between primary and secondary. The embodiments specifically described above are also nominally electrically balanced.
The embodiment shown in FIG. 1A is of particular interest for a number of applications. However, although this embodiment is nominally electrically balanced, its common mode rejection is less than many potential applications require. The common-mode rejection of a differential device is quantified by a common-mode rejection ratio (CMRR), which is the ratio of the differential-mode voltage gain to the common-mode voltage gain of the differential device.
One approach to increasing the common-mode rejection ratio is to increase the thickness of the acoustic decoupler. However, increasing the thickness of the acoustic decoupler causes the frequency response of the FACT to exhibit spurious artifacts caused by the ability of the thicker acoustic decoupler to support more than a single acoustic mode. Such spurious response artifacts are undesirable in many applications.
What is needed, therefore, is an FACT that has the advantages of the FACT described above, but that has an increased common mode rejection ratio and a smooth frequency response.

Film acoustically-coupled transformer with increased common mode rejection


Provided herein is a magnetostriction element having a large power output and a high power density. The magnetostriction element is comprised of a magnetostrictive material that is a monocrystalline alloy represented by the following formula (1),Fe(100-α-β)GaαXβ,  Formula (1)wherein α and β represent the Ga content (at %) and the X content (at %), respectively, X is at least one element selected from the group consisting of Sm, Eu, Gd, Tb, Dy, Cu, and C, and the formula satisfies 5≤α≤40, and 0≤β≤1.

Recent years have seen the arrival of the Internet of things (IoT), a world where "things" equipped with autonomous communication functions automatically control one another by exchanging information. The spread of IoT means a society with increasing numbers of IoT devices featuring communication functions. IoT devices, such as sensors, require a power supply to operate. However, the needs for wirings and service time, and the cost make it difficult to provide power supplies for these proliferating numbers of devices. This has created a need for a power supply technology suited for IoT devices in the coming era of IoT. Against this background, an important consideration is a technology called "energy harvesting", a process by which small amounts of energy from the everyday environment are converted into electrical power. Vibration is a form of energy source that is constantly produced by moving objects such as automobiles, trains, machinery, and humans in many places, and represents an energy source that is not influenced by weather or climate. It is therefore envisioned that a system that enables vibration-based power to be used as a power supply to applications coupled to movement of moving objects such as above can open the door to more effective IoT.
Vibration-based power generation can be divided into four categories: magnetostrictive, piezoelectric, electrostatic induction, and electromagnetic induction. In magnetostrictive power generation, a leakage magnetic flux due to a change in magnetic field inside a magnetostrictive material in response to applied stress is converted into electrical energy through a coil wrapped around the magnetostrictive material. The magnetostrictive power generation involves a smaller internal resistance, and generates more power than the other types of vibration-based power generation. Another characteristic of the magnetostrictive power generation is the desirable durability due to the metal alloy used as magnetostrictive material. This makes the magnetostrictive power generation a desirable mode of power generation that could overcome an issue associated with magnetostriction-type vibration powered generators or elements, namely, the durability of magnetostriction-type vibration powered generators or elements.
An example of a magnetostriction-type vibration powered generator is one having a cantilever beam structure. A traditional magnetostriction-type vibration powered generator having a cantilever beam structure has a magnetostrictive rod (or a magnetostriction element) formed of a magnetostrictive material; a coil wrapped around the magnetostrictive rod; a magnetic rod disposed parallel to the magnetostrictive rod; a frame curved in a U shape; and a magnet attached to inside of the frame (see WO2015/141414). The frame is a magnetic material with two ends. One of the ends on either side of the U-shaped bent portion is a fixed end, and the other end is a free end. In this way, a part of the frame works as a back yoke, and the frame forms an air gap between the magnet and the inner surface of the frame where the magnet is not attached.
In such a cantilever beam structure having a fixed end, the magnetostrictive rod is subjected to tensile and compressional stress when an external force (vibration) is applied within a horizontal plane, and this creates an alternating magnetic field in the magnetic field lines. Voltage is extracted in the form of electrical energy as the coil generates voltage in accordance with the law of electromagnetic induction, which states that voltage occurs in proportion to changes occurring in magnetic flux density over time.
In a magnetostriction-type vibration powered generator, power output P is represented by P=NI·d/dt(∫BdA), and power density B is represented by E=P/v. Here, N is the number of turns in the coil, I is the value of the current through the coil, B is the magnetic flux density of the magnetostriction element, A is the cross sectional area of the magnetostriction element, and v is the volume of the magnetostriction-type vibration powered generator. However, in the magnetostriction-type vibration powered generator above, the stress exerted on the magnetostriction element in response to an external force (vibration) applied within a horizontal plane in the cantilever beam structure is greater at the fixed end than at the free end, and this creates a stress distribution as a result of the stress not being exerted throughout the magnetostriction element in a uniform fashion. The stress distribution creates a distribution in the magnetic field lines running inside the magnetostriction element, and changes in the magnetic flux density B of the magnetostriction element become smaller as a whole, with the result that the power output P also becomes smaller. That is, the power density E (power output P per volume) is too small to achieve the high output (high power output) needed for IoT. Indeed, the power density F of the magnetostriction-type vibration powered generator needs to be improved for practical applications. For example, a magnetostriction-type vibration powered generator requires a consumed power density of about 1.0 mW/cm3 in applications such as tire air pressure monitoring systems, and sensor networks for factories.

Magnetostriction element and magnetostriction-type vibration powered generator using same

PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.


A device for needle-by-needle selection in circular stocking knitting machines is disclosed. An elastic lock pin or segment (19) is provided for each lower needle (13) of the type having an elastic deflection tail. The segment is carried by a crown (22) fixed with the cylinder and usually in a position shifted downwards away from the tail of the lower needle. A thruster (20) is provided under the lock segment, which can be moved upwards and is intended to deflect the lock segment (19) up to the level of interception with the tail of the lower needle (13). This results in a locking of the lower needle in the deflected, inoperative position. A selection electromagnet (21) is provided which can be activated and deactivated according to a program to hold or release the lock segment. The activation/deactivation keeps the inoperative lower needle locked or releases it because it is moved towards the outside into the operating position.

Systems for selecting needles using electromagnets as selection actuators have already been proposed in the field of stocking knitting machines. These electromagnets cooperate, by means of mechanical elements, with the deflected lower needles in order to control their passage from a deflected, inoperative position to a released, operating position, in which they can control the corresponding needles.
A circular knitting machine is disclosed in U.S. Pat. No. 5,165,259 to Negri et al. In this device the inactivation or activation of a vertical jack below each needle is determined by a flexible fork located radially above the cylinder within a ring structure completely surrounding the machine cylinder and rigid therewith. A number of forks and radial grooves equal to the number of needles is provided. The forks are able to flex within the grooves and are selected by magnetic force. The jacks are kept in position by one or more circular springs surrounding the upper part of the jacks. The springs must be sufficiently shrunk to oppose the forces which flex the jack shank, so that the flexing forces acting on the foot effect the flexture without causing the upper end of the jack to leave the trick.

Device for needle-by-needle selection in circular stocking knitting machines


Apparatus and method for positioning a head in a disc drive using a dual stage actuator having a primary actuator motor for coarse head positional control and a microactuator motor for fine head positional control. The microactuator motor includes a strain gauge affixed to a piezoelectric transducer measuring actual dimensional change of the microactuator motor resulting from response by the piezoelectric transducer to a request for head repositioning. A closed loop servo control circuit generates control inputs for the dual stage actuator to carry out track following and seek operations while adjusting head position by correcting piezoelectric transducer hysteresis and reducing seek and settle times.

This invention relates generally to the field of magnetic data storage devices, and more particularly, but not by way of limitation, to an apparatus and method for controlling correction of microactuator induced hysteresis errors and microactuator assisted seeks of a disc drive actuator.
Disc drives are used as primary data storage devices in modern computer systems and networks. A typical disc drive comprises a head-disc assembly (HDA) which houses mechanical portions of the drive, and a printed circuit board (PCB) mounted to an outer surface of the HDA which supports electronic circuitry used to control the HDA.
Typically, a HDA comprises one or more magnetic discs that are affixed to and rotated by a spindle motor at a constant high speed and an actuator assembly, which supports an array of heads adjacent tracks defined on the disc surfaces. The surface of each disc is a data recording surface divided into a series of generally concentric recording tracks radially spaced across a band having an inner diameter and an outer diameter. The data tracks extend around the disc and store data within the tracks on the disc surfaces in the form of magnetic flux transitions. The flux transitions are induced by an array of transducers, otherwise commonly called read/write heads or heads. Typically, each data track is divided into a number of data sectors that store fixed-size data blocks.
The head includes an interactive element such as a magnetic transducer, which senses the magnetic transitions on a selected data track to read the data stored on the track. Alternatively, the head transmits an electrical signal that induces magnetic transitions on the selected data track to write data to the track. As is known in the art, each read/write head is mounted to a rotary actuator arm and is selectively positionable by the actuator arm over a selected data track of the disc to either read data from or write data to the selected data track. Each head includes a slider assembly with an air-bearing surface that causes the read/write head to fly above the disc surface. The air bearing is developed as a result of load forces applied to the read/write head by a load arm interacting with air currents that are produced by rotation of the disc.
An actuator motor, such as a voice coil motor (VCM), rotates the actuator assembly, and hence the heads, across the disc surfaces. The control circuitry on the PCB includes a read/write channel which interfaces with the heads to transfer data between the tracks and a host computer, and a servo control system which drives the VCM to provide head positional control, based on the information contained in the servo field.
Continued demand for disc drives with ever increasing levels of data storage capacity and data throughput have led disc drive manufacturers to seek ways to increase the storage capacity of each disc surface and improve operating efficiencies of the disc drive. High performance disc drives of the present generation typically achieve areal bit densities measured in several gigabits per square centimeter, Gbits/cm2. Higher recording densities can be achieved by increasing the number of bits stored along each track, and/or by increasing the number of tracks per unit width across each disc. Storing more bits along each track generally requires improvements in the read/write channel electronics to enable the data to be written (and subsequently read) at a correspondingly higher frequency. Providing higher track densities generally requires improvements in the servo control system to enable the heads to be more precisely positioned over the discs. Improved operating efficiencies or throughput performance, for any given bit density, results from reduced cycle times in performing functions or through elimination and/or incorporation of functions internal to the other.
Throughput performance is enhanced during read/write cycles by stabilizing the ability of the servo system to hold the head on track under adverse conditions such as an occurrence of servo field thermal asperity; rotational vibration; resonance of rigid bodies at frequencies sympathetic to the servo frequencies; or components of runout, velocity and acceleration (commonly referred to as RVA) drifting out of tolerance.
To improve on track performance and seek performance for disc drives of higher track densities, disc drive manufacturers are increasingly moving to implement so-called xe2x80x9cmicroactuator motorsxe2x80x9d or xe2x80x9cmicroactuators,xe2x80x9d which are secondary motors suspended by actuator assemblies to provide fine (secondary) positional adjustment of the heads over and above the coarse (primary) positional adjustment provided by the VCMs. A variety of microactuator constructions have been recently proposed in the art, including the use of an inductive rotor/stator arrangement as exemplified by U.S. Pat. No. 5,657,188 issued to Jurgenson et al.; the use of piezoelectric transducers as exemplified by U.S. Pat. No. 6,002,549 issued to Berman et al.; and microelectronic machine (MEM) implementations as discussed in U.S. Pat. No. 5,711,063 issued to Budde et al.
The basic operational concept of an actuator assembly with both primary and secondary motors (also referred to as a xe2x80x9cdual-stagexe2x80x9d actuator) is relatively straightforward; the primary motor is used to bring the selected head within a given range of tracks or to a selected track, after which the secondary motor operates to bring the head over track center of the selected track. While improvements have been made within dual stage actuator technology that dramatically improve head positioning, essentially through the introduction and integration of microactuators into the servo system, challenges remain with maximizing microactuator capability and correcting head position deficiencies stemming from microactuator motor hysteresis.
The present invention provides an apparatus and method of effectuating microactuator assisted seeks and hysteresis corrected head positioning functions for expanding microactuator utility in improving disc drive read/write head placement position relative to a data track.
In accordance with preferred embodiments, a disc drive is provided with a rotatable actuator which supports an array of read/write heads adjacent a corresponding number of recording surfaces in a rotatable disc stack. A servo controller providing a closed loop primary servo control circuit with a closed loop piezo servo circuits generates control inputs for the actuator to carry out track following operations wherein a selected head is caused to follow a corresponding track.
The actuator is characterized as a dual-stage actuator having both a primary actuator motor (VCM), which controllably moves all heads simultaneously, and an array of secondary microactuator motors which controllably move each head individually. Each microactuator preferably has a piezoelectric transducer (PZT) construction and undergoes a dimensional change in response to application of an electric field. Attached to each microactuator is a sensor, such as a strain gauge, which provides a changed electrical resistance in response to a dimensional change imparted to the strain gauge. Hence, actual dimensional change in the microactuator can be directly measured by the sensor.
Control inputs for the motors are determined in relation to an actual position signal for the head, a desired position signal or target track seek request from a control processor and a set of control limits. The control limits are individually determined and loaded into a volatile memory for the selected head at start-up and then as needed for subsequently selected heads throughout the operation of the disc drive. The control limits are initially captured and stored in a head accessible nonvolatile memory location on the disc drive. The control limits are developed by measuring voltage output responses for each microactuator in response to voltage inputs applied to the individual microactuators and the response of each head disc pairing to seek commands.
Each set of control limits comprises the results of the voltage measurements and calculations made on those voltage measurements. The measurements are made during the manufacturing process. The use of a different set of control limits by head enables a servo controller to be adapted for each head/disc combination. That is, as each new head is selected, a new set of control limits appropriate for the new head is loaded into a volatile memory of a servo engine thereby providing accurate, adaptive control.
The primary servo control circuit is a closed loop control circuit that serves, primarily, to control functions of the dual stage actuator during track following and seek requests. A closed loop piezo servo circuit is integrated into the primary servo control circuit and has the ability to operate separately from the primary servo control circuit, having once received input from the primary servo control circuit.
Included within the closed loop piezo servo circuit is a hysteresis correction circuit that monitors and adjusts the position of the head relative to the data track based on an actual physical response of a microactuator to a request for a head positional adjustment. The hysteresis correction circuit monitors the actual physical response of the microactuator to the head position adjustment request and adjusts the input voltage to the microactuator until the actual physical response of the microactuator matches the theoretical physical response of the actuator inherently intended by the original head reposition request. Microactuator hysteresis correction occurs absent servo fields supplied head position data and can occur simultaneous to data transfer functions.
These and various other features and advantages, which characterize the present invention, will be apparent from a reading of the following detailed description and a review of the associated drawings.

Microactuator assisted seek and hysteresis correction method and apparatus for a disk drive