Abstract: A depleted-gate photosensor, or photogate, structure includes a polysilicon layer disposed over a silicon substrate. The polysilicon layer occupies only a portion of each exposure area of the substrate, and is preferably in the form of a ring around the exposure area. By having a portion of the exposure area not covered by the polysilicon, the blue-light-attenuation effects of a polysilicon layer are reduced.

Abstract: A photosensitive chip, such as used in a scanner or facsimile, defines a linear array of photosites, each photosite being covered with a filter formed from a cured translucent liquid. At the critical ends of the chip, between the end photosite in the array and the edge of the chip, there is provided a ridge which protrudes over the thickness of the filter. This ridge maintains the physical integrity of the filter.

Abstract: In a hard-copy scanner in which a set of photosensitive silicon chips are abutted to form a single page-width array of photosensors, the photosites at the critical ends of each chip are irregularly spaced, relative to the other photosites on the chip. This irregular spacing enables compensation for imprecisions in the dimensions of individual chips. The spacing principle can be applied as well to LED's or portions of ink-jet ejectors.

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 circuit in parallel with the video line maintains a running average of readings from the dark photosensor over a large number of scans. This averaging of many dark-pixel readings averages out short-term thermal noise on the dark photosensor, for a truer offset value.

Abstract: In a photosenstive device wherein video voltage signals are output from a plurality of photosensors, the photosensors are divided into odd and even subsets. Odd photosensors output video into an odd video channel, and even photosensors output video into an even video channel. The two video signals are time-staggered from each other by one-half cycle. The signals on the odd and even video channels are then multiplexed into a single high-speed channel.

Abstract: A photosensitive device includes a plurality of active photosensors, for receiving light from an original image, and at least one dark photosensor. The dark photosensor is shielded with a light shield so that it receives no light, and is used to establish a dark offset for the device. Each active photosensor and the dark photosensor have associated therewith an individual transfer circuit, including a reset node having a capacitance associated therewith. The capacitance of the reset node for the dark photosensor is selected to compensate for the extra capacitance created by the light shield.

Abstract: An input scanner for converting original hard-copy images into digital signals is adapted for efficient scanning of simple "business color" documents. Three linear arrays of photosensors, each linear array corresponding to one primary color, are moved relative to the original image. One linear array of photosensors operates on a full cycle and converts every single scan line of the original image into digital signals. Simultaneously, the other primary-color-sensitive linear arrays operate on half cycles and record only signals corresponding to an evenly-distributed subset of small areas of the original image.

Abstract: A photosensitive apparatus comprising a plurality of sets of photodiodes and a plurality of amplifiers, each amplifier being operatively connected to one set of photodiodes. A transfer circuit is associated with each photodiode for loading a charge from the photodiode to a storage node associated therewith. Readout means sequentially unload charges from each storage node in the set of transfer circuits through the amplifier, so that multiple photodiodes may operate through a single amplifier.

Abstract: In an input scanner for recording hard-copy images by exposing areas of the image to an array of photosensors, a system ensures sensor array uniformity. With each cycle of passing a discrete image signal through an amplifier associated with each photosensor, a low standby current is applied to certain transistors within the amplifier until the next signal is to be output. Critical nodes within the amplifier are caused to settle to known charge values before each image signal is passed therethrough.

Abstract: A test system for a photosensitive array includes an on-board test circuit with a single input terminal, wherein the output of the test circuit directly affects the value of a bias charge placed on a selected photodiode. The test circuit enables a quick test for the presence of a desired bias charge when a digital-high voltage is entered on the single input terminal, and also enables a more precise test of photodiode response linearity by application of a predetermined analog voltage to the single input terminal.

Abstract: A raster input scanner comprises a linear array of photosensors arranged on a plurality of butted chips. The analog video signal from the first photosensor on each chip is read out for an extended period relative to the readout of the other photosensors on the chip, to provide extra settling time for the signal.

Abstract: A process for separating image sensor dies and the like from a wafer in which pairs of separation grooves separating each row of dies are formed in the active side of the wafer, with the tab between each groove pair being substantially equal to the width of the dicing blade, cutting a single bottom groove in the inactive side of the wafer opposite to and spanning each pair of separation grooves, and aligning the dicing blade with the midpoint of the wall of one groove in each pair of grooves so as to cut between the rows of dies. In a second embodiment, a two-pass separation process is enabled in which the tab between separation grooves is slightly larger than the width of the dicing blade, with the dicing blade first aligned with the midpoint of one separation groove to cut one row of dies from the wafer together with part of the tab, with the blade realigned with the midpoint of the other separate groove to cut a second row of dies and the remainder of the tab.

Abstract: A linear image sensor and process having a two stage transfer circuit in which split clock transistor actuating pulses are used to cancel cell-to-cell variations and neutralize undesired couplings of the rising edge of the charges into the transistors.