Abstract: In a photosensitive device wherein a photodiode is operated by placing an initial fat zero charge thereon before the integration of a light-induced signal, the actual dark level signal created by the fat zero charge is sampled with each readout from the photodiode, and then retransferred to the photodiode. After integration, the sampled dark level is subtracted from the total signal level on the photodiode. In this way both fixed-pattern and thermally-induced noise is obviated.

Abstract: In a photosensitive apparatus having photodiodes, such as a photosensor chip used in digital office equipment, a “fat zero” initial bias is injected on the photodiode. With every cycle of operation, a first fat zero is placed on the photodiode and then sampled. Then, a second fat zero is placed on the photodiode just before the integration of a light signal from an image being recorded. The light signal plus the second fat zero is transferred out of the photodiode and the sampled signal is subtracted therefrom, leaving only the light signal. The system obviates both fixed-pattern and some thermal noise within the apparatus.

Abstract: An architecture and manufacturing method for photosensitive chips, such as used in office equipment and digital cameras, involves creating grooves between chip areas in a wafer, and then placing a light-transmissive planar layer over the main surface of the wafer. The planar layer, which may be acrylic-based, creates a substantially planar surface over both the photosites in the chip areas and the grooves. The planar layer in turn supports one or more light-transmissive filtering layers. The arrangement avoids damage to the filtering layers when the wafer is diced along the grooves.

Abstract: In a photosensitive device wherein voltages are read sequentially from a dark, or dummy, photosensor and a plurality of active photosensors with each of a series of scans, a circuit downstream of the photosensors resets the offset value of the voltage signals, based on successive voltage readings from the dark photosensor. An RC averaging circuit maintains a running average of readings from the dark photosensor over a large number of scans. Signals from the dark photosensors are read a first time into the averaging circuit, and then signals from the dark photosensors are read directly to downstream video circuitry. This double readout of dark-photosensor signals enables precise calibration of both on-chip circuitry and downstream video circuitry.

Abstract: A photosensitive device, such as would be found in a digital scanner or camera, includes at least two sets of photosensors, the video signals from which are multiplexed together. While the two video paths are separate, before the multiplexing step, an offset correction process is carried out on each video path. After multiplexing, a final offset correction process is carried out to the combined signals, to remove offsets associated with the combined video path.

Abstract: The present invention generally relates to electrical detection of V-groove width during the fabrication of photosensitive chips, which create electrical signals from an original image, as would be found, for example, in a digital scanner or facsimile machine.

Abstract: The present invention generally relates to electrical detection of V-groove width during the fabrication of photosensitive chips, which create electrical signals from an original image, as would be found, for example, in a digital scanner or facsimile machine.

Abstract: An apparatus detects the width of a V-groove formed on a semiconductor wafer. A resistor overlaps a chip area and an area upon which the V-groove is to be etched on the wafer. A pad etched on the silicon wafer is coupled to the resistor. A tester supplies voltage to the pad after the V-groove has been etched into the silicon wafer; and a circuit coupled to the pad determines the width of the etched V-groove.

Abstract: In a full-color image scanner having three parallel linear arrays of photosensors, each linear array of photosensors is sensitive to one primary color. With each readout cycle relating to a row of small areas on an original image moving past the scanner, the middle array of the three arrays of photosensors reads out its video data before the other two. This technique allows the arrays of photosensors to be spaced relatively close to each other, and in turn the close spacing of photosensors requires relatively fewer scan lines of video data to be temporarily buffered in the readout process.

Abstract: The present invention generally relates to electrical detection of V-groove width during the fabrication of photosensitive chips, which create electrical signals from an original image, as would be found, for example, in a digital scanner or facsimile machine.

Abstract: A CMOS-based photosensor array, having a plurality of photodiodes therein, includes a spillover protection circuit associated with each photodiode. The spillover protection circuit causes a potential to be applied to a photodiode in response to a charge spillover or “blooming” condition. The spillover protection device is momentarily disabled whenever a bias charge is injected onto the photodiode by the transfer circuit. Also, a reference voltage applied to the gate of a transistor forming the spillover protection device is higher than a threshold voltage of the transistor but is lower than a sum of the threshold voltage and a maximum light-intensity signal from the photodiode.

Abstract: The present invention relates to electro optical devices with a reduced filter thinning on the edge pixels and a method for reducing the thinning of filter layers on the pixels closest to the edge of an electro optical device such as a photosensitive chip, as would be used, for example, in a full-color digital copier or scanner. A semiconductor wafer includes a main surface defining a plurality of chip areas and tab regions separated by grooves, wherein the chip areas include inner photosites, outer photosites and bonding pads. A plurality of dams are deposited over the main surface in the tab regions, and a clear layer is deposited over the main surface exclusive of the bonding pads. Alternatively, a clear layer is deposited over the main surface exclusive of the bonding pads, and a plurality of tabs is then deposited in the tab regions on the main surface.

Abstract: A full-color scanning array uses CMOS active pixel cells, or photogates, as photosensors. A set of photogates, each photogate being specifically filtered for one primary color, is associated with a common node. A clearing gate downstream of the common node applies a relatively high potential to a selected photogate, for the purpose of clearing any charge from the photogate. In this way, the integration time for the photogate can be started at a precise time, and the effective exposure time of each photogate can thereby be precisely controlled. Alternately, one of the set of photogates can be repeatedly cleared without a signal being read therefrom, allowing the array to operate in a monochrome mode.

Abstract: The present invention relates to electro optical devices with a reduced filter thinning on the edge pixels and a method for reducing the thinning of filter layers on the pixels closest to the edge of an electro optical device such as a photosensitive chip, as would be used, for example, in a full-color digital copier or scanner. A semiconductor wafer includes a main surface defining a plurality of chip areas and tab regions separated by grooves, wherein the chip areas include inner photosites, outer photosites and bonding pads. A plurality of dams are deposited over the main surface in the tab regions, and a clear layer is deposited over the main surface exclusive of the bonding pads. Alternatively, a clear layer is deposited over the main surface exclusive of the bonding pads, and a plurality of tabs is then deposited in the tab regions on the main surface.

Abstract: The present invention relates to photosensitive chips for creating electrical signals from an original image, as would be found for example in a digital scanner, copier, facsimile machine, or other document generating or reproducing device. More specifically, the present invention provides a way of shielding the edge photosites with an opaque layer that overlaps the diced region and preserves the integrity of the filter layers while eliminating the need for a guardring to decrease the dead space and consequently reduce the undesirable effects of Moire patterns.

Abstract: A system by which defective circuitry associated with a single photosensor in an image sensor array can be readily detected, without the defect being "covered" by a good signal from a neighboring photosensor. The output line onto which a series of photosensors and their transfer circuits output video signals is grounded via a pulldown resistor. When a defective photosensor circuit fails to place a bias on the output line, the bias on the output line quickly drifts towards zero. By detecting this relatively sudden drift towards zero bias, a defective photosensor or its associated circuitry can be identified.

Abstract: A test circuit incorporated as part of an image sensor array having a plurality of image sensors and associated transfer circuits includes a test line associated with each photosensor. In a test mode, a signal output from a photosensor can be substituted with a predetermined voltage from an external source. By providing a predetermined test voltage to the transfer circuits and then reading out signals from the transfer circuits, faults in the transfer circuits can be isolated from faults in the photosensors.

Abstract: In a full-color image scanner having three parallel linear arrays of photosensors, each linear array of photosensors is sensitive to one primary color. With each readout cycle relating to a row of small areas on an original image moving past the scanner, the middle array of the three arrays of photosensors reads out its video data before the other two. This technique allows the arrays of photosensors to be spaced relatively close to each other, and in turn the close spacing of photosensors requires relatively fewer scan lines of video data to be temporarily buffered in the readout process.

Abstract: In a CMOS-based photosensor chip, the area between the last photosensor in a linear array of photosensors and the edge of the chip can be a source of unintended charge generation affecting the last photosensor. A guardring, in the form of a biased diffusion area, prevents the unwanted leakage of charge from the edge area to the end photosensor.

Abstract: An image sensor array includes a plurality of photosensor chips, which are butted end-to-end to form a single linear array of photosensors. Each individual chip in the array is provided with an independently-addressable output enable line and video output line. This configuration allows individual chips to be addressed to output image data at specific times and in a specific manner suitable for any kind of downstream circuitry.