Abstract: Multiple scans of the same object are obtained, where for any given line on the object to be scanned, the angle of the illumination is different for each scan. The different scans are obtained from different rows of photosensors that are separated. Because the angles of illumination are different, the resulting shadows in each scan are different. The multiple scans may be combined into a single composite color image. In a composite image, a dust particle may generate a series of overlapping shadows, where each shadow is a different color. Searching the composite image for the unique pattern of colors may identify artifacts or defects. Alternatively, the data for one scanned image may be compared to the data for another scanned image, and any differences may be due to shadows, which may indicate defects.

Abstract: Image data in an image scanner is examined to determine whether lines (light or dark) are present in the image data. By examining whether the lines are present in image data for multiple colors, and whether calibration gains for corresponding photosensors are normal, it can be determined whether the lines are likely caused by a surface defect, on a calibration target, or on a platen, or on an image being scanned.

Abstract: A scanner is provided with a variable aperture lens system. High resolution scans use a relatively small aperture size, and scanning speed is relatively slow. Low resolution scans use a relatively large aperture size, and scanning speed is increased. Fast scans are limited to lower sampling rates, which in turn permit more optical blurring relative to high sampling rates. Accordingly, the incremental cost of the larger aperture is minimized by permitting the lens aberrations specifications to be relaxed at larger apertures. Preferably, an electronic variable aperture is provided, for example, by use of electronically controlled polarization plates or by use of electrochromic substances.

Abstract: Photosensor assemblies have, for each color, multiple line-arrays of photosensors. For each color, the spectral bandwidth received by each line-array is different. The additional spectral bandwidths are used to improve the spectral measurement accuracy, and to increase bit-depth. In one example, one row of a staggered array receives light having a first spectral bandwidth, and a second row of the staggered array receives light having a different spectral response. In a second example, photosensors with different sizes receive light having different spectral bandwidths.

Abstract: In an image scanner, multiple exposures are used for each scan line, and only part of the pixels for each scan line are used for each exposure. For example, with two exposures, half the pixels may be used for the first exposure, and half for the second exposure. For each exposure, half of the charges are shifted out rapidly and discarded, without waiting for the A/D conversion time. As a result, for each exposure, the time required to empty the charge shift register is greatly reduced, reducing the thermal noise for all pixels.

Abstract: A cache memory system can determine that an entry is stale if the entry has not been accessed or modified for a predetermined time. If an entry is stale, the entry may be preemptively evicted. The predetermined time is made dynamically variable. A computer system can adjust the time to optimize a measure of performance. In a specific example, evicted lines are temporarily stored in an eviction queue. The time is adjusted to be as short as possible without substantially increasing the number of lines that must be recalled from the eviction queue.

Abstract: In a digital image, for each pixel to be thresholded, a threshold is selected from a set of thresholds. Selection may be based on relative magnitudes of the thresholds. At least one of the thresholds may be dynamic, and one of the thresholds may be constant for at least a region of the image.

Abstract: Digital data is embedded in codes used to identify beginnings of regions of modulated data bit streams. Data may be designated by a choice of one code from a plurality of alternative codes, or data may be designated by a variable field within a code.

Abstract: Information is encoded, within a photosensor array, into photosensors which are not used for imaging. Some information encoding photosensors are permitted to receive unimpeded light, and for other photosensors the light is at least partially blocked or filtered. Alternatively, some photosensors may be disabled. When the photosensors are exposed to light, the resulting photosensor signals provide information. Alternatively, some photosensors may accumulate charge in the absence of light, and the resulting photosensor signals in the absence of light provide information. The information can be binary, or multiple-bit per pixel. Information can also be encoded into each individual color channel. Identification of vendor, part type, or other information can be encoded.

Abstract: A representative photosensor assembly comprises first through sixth arrays of photosensor elements and first through third arrays of charge shift registers. Each photosensor element in the first array, the third array and the sixth array of photosensor elements exhibit a first size, and each photosensor element in the second array, the fourth array and the sixth array of photosensor elements exhibit a size different than the first size. The first and second arrays of photosensor elements are operative to detect a first color of light, the third and fourth arrays of photosensor elements are operative to detect a second color of light, and the fifth and sixth arrays of photosensor elements are operative to detect a third color of light. The first, second and third arrays of charge shift registers are coupled between the first and second, third and fourth, and fifth and sixth arrays of photosensor elements, respectively.

Abstract: A scanner has an optical head that includes lenses and a photosensor array. The distance of the optical head, relative to a surface of a platen, is variable. As a result, the primary focal point for the lenses can be moved relative to a surface of the platen. The primary focal point can be continuously variable, or the primary focal point can be selected from one of multiple alternative primary focal points.

Abstract: A photosensor assembly has at least one line array of photosensors with a first sensor size, and at least one line array of photosensors with a second sensor size, with the two sizes being different. In an example embodiment, for every band of wavelengths being sensed, there are two line arrays of sensors, with one line array having relatively small sensor areas and the other line array having relatively large sensor areas. The line arrays with relatively small sensor areas are used for high native input sampling rates, and the line arrays with relatively large sensor areas are used for high color accuracy and speed. To minimize cost and circuit area, each line array of sensors having large sensor areas shares a charge shift register with a line array of sensors having small sensor areas. If overflow drains are present, some pairs of sensor line arrays may also share overflow drains.

Abstract: A system and method for analyzing the effectiveness of a computer cache memory. A bus with memory transactions is monitored. A subset of addresses, along with associated transaction data, on the bus is captured and stored in a memory. The captured addresses are applied to a software model of a computer cache. The capture process is repeated multiple times, each time with a different subset of the address space. Statistical estimates of hit rate and other parameters of interest are computed based on the software model. Multiple cache configurations may be modeled for comparison of performance. Alternatively, a subset of addresses along with associated transaction data is sent to a hardware model of a cache. The contents of the hardware model are periodically dumped to memory or statistical data may be computed and placed in the memory. Statistical estimates of hit rate and other parameters of interest are computed based on the contents of the memory.

Abstract: A photosensor assembly has multiple rows of photosensors sharing a charge transfer register. Charges from one row of photosensors are transferred through another row of photosensors to the charge transfer register, and charges from both rows of photosensors are optionally added together in the charge transfer register. The photosensors in the two rows may have different light collecting areas.

Abstract: A method and apparatus for write protection of rewritable compact disks and digital video disks. A Power Calibration Area is covered to prevent the drive laser from completing a calibration procedure. In one embodiment, the disk has an indented area formed around the central hole in the disk. A ring shaped plug is inserted into the indented area, with an extended surface that covers the calibration area. In an alternative embodiment, an adhesive label, ink, dye or paint is used. In still another alternative embodiment, the calibration area is mechanically abraded to provide permanent write protection. Finally, the laser in the drive may be used to darken, damage or destroy the calibration area or a transparent label over the calibration area, for permanent write protection.

Abstract: A computer system maintains a list of tags (called a Global Ownership Tag List (GOTL)) for all the cache lines in the system that are owned by a cache. The GOTL is used for cache coherence. There may be one central GOTL. Alternatively, the GOTL may be distributed, so that every device that can request a copy of memory data maintains a local copy of the GOTL. The GOTL can be limited to a relatively small size. For a limited size list, a tag may need to be evicted to make room for a new tag. A line associated with an evicted tag must be written back to memory.

Abstract: A battery is inside an enclosure. A shim is inserted between the battery and at least one contact. The shim can be actuated externally without requiring the enclosure to be opened. The shim may be conductive on at least one face to provide a switch function, or may be non-conductive.

Abstract: An optical disc has spatial features (notches, bumps, etc.) that intentionally distort the analog Read Data signal. For a mark or space that is centered on a spatial feature, the distortion does not affect the resulting binary Read Data signal. If an edge of a mark or space is near the spatial feature, the resulting binary Read Data signal is altered. For calibration, marks or spaces are written adjacent to spatial features, with a range of times for initiating the writes. The result is a range of write times that do not alter the binary Read Data signal. From these known times and spatial locations, it is known when a mark or space must be written to ensure accurate spatial placement.

Abstract: A cache system improves performance by limiting the number of dirty entries in a cache. The cache system may be further improve performance by limiting the number of dirty entries in a cache that might be subject to a cache-to-cache transfer. In a first example, a cache system counts the total number of dirty entries in the cache and preemptively evicts at least one dirty entry when the count exceeds a predetermined threshold. In a variation, a cache system counts dirty cache entries that result from a cache-to-cache transfer, and evicts at least one dirty entry that results from a cache-to-cache transfer when the number exceeds a predetermined threshold. For either system, the predetermined threshold may be dynamically varied to determine a value that optimizes performance.

Abstract: In an optical disc drive, the read channel electronics and the wobble channel electronics are combined into one common channel, for reduced cost. When the drive is reading, the common channel is used for primary data and a read clock. When the drive is writing, the common channel is used for wobble data and a write clock. Two example embodiments are provided. In each example, a single front end amplifier, without automatic gain control, is used. In each example, a single PLL and a single data detector are used.