Abstract: A raster input scanner in which a dither generator introduces a random error signal to artificially increase the calibration signal accuracy during calibration of the scanner.

Abstract: A programmable screening circuit with memory for storing at each address location both a pixel screen value and the memory address of the screen value for the next pixel to be screened, and a control including a latch pair for separating data from each memory location addressed into a screen value for screening the pixel and an address for addressing the memory location for the next screen value.

Abstract: A scanner with scanning array on a movable carriage, a control for regulating the scanning speed of the carriage, a small buffer between the scanner and a workstation, a buffer capacity sensor for continuously monitoring the residual capacity of the buffer, a motion sensor for actuating the array to scan an image line each time the carriage moves a distance of one scan line, and a controller for regulating scanning speed of the carriage to substantially match the image signal output rate of the array with the image signal input rate of the workstation while maintaining a predetermined level of buffer residual capacity, the controller reducing carriage scanning speed as buffer residual capacity decreases in order to maintain the scanner operating as long as possible in the event workstation demand ceases and minimize carriage acceleration/deacceleration forces on scanner noise, vibration, and image quality.

Abstract: A scanner with high intensity source beam, a modulator for modulating the source beam to provide a zero order beam and first order writing beam in response to an image signal input, a polygon for scanning the writing beam across a moving recording member to write images thereon, a sensor in the path of the zero order beam providing a first black beam intensity signal while scanning between pages and a second white beam intensity signal while the writing beam scans an image background area, a circuit for differencing the first and second beam intensity signals from one another to provide a composite intensity signal representing the intensity of the source beam, and a second circuit for differencing the composite beam intensity signal from an intensity setpoint signal to provide a correction signal for adjusting the rf power to the modulator to maintain a substantially constant writing beam intensity.In a second embodiment, the correction signal is determined by a successive approximation register.

Abstract: A printer having holographic scanning disc for scanning the imaging beam from a laser diode across a recording member, the diode having diode biasing and modulating current inputs for modulating the diode and thereby exposing and creating images on the recording member, a heating-cooling device in heat exchange relation with the diode for controlling diode temperatures, and a current sensor for monitoring the diode biasing and modulating currents and operating the heating-cooling device to adjust diode temperatures to maintain diode temperatures within a non-mode hopping temperature range.

Abstract: A linear image sensor array with a row of photodiodes and a transfer circuit for each photodiode, the circuit having a pair of transistors for two stage transfer of the image signal charge from the photodiode to the gate of one transistor of a two transistor source follower, a transistor for applying a bias charge to the photodiode, a multiplexing transistor for connecting the source follower output to an output line, a reset transistor for resetting the source follower, and clock signals for operating the transfer circuits in succession to serially output image signals to the output line.

Abstract: A method and apparatus for fabricating long full width scanning arrays for reading or writing images. For this purpose, smaller scanning arrays are assembled in abutting end-to-end relationship, each of the smaller arrays being provided with a pair of V-shaped locating grooves in the face thereof. An aligning tool having predisposed pin-like projections insertable into the locating grooves on the smaller scanning arrays upon assembly of the smaller arrays with the aligning tool is used to mate a series of the smaller arrays in end-to-end abutting relationship, there being discretely located vacuum ports in the aligning tool to draw the smaller arrays into tight face-to-face contact with the tool. A suitable base is then affixed to the aligned arrays and the aligning tool withdrawn.

Abstract: A printer having holographic scanning disc for scanning the imaging beam from a laser diode across a recording member, with a detector for detecting a shift in wavelength of the diode utilizing the zero order beam passing through the holographic scanning disc and a temperature control for controlling diode temperatures, the detector actuating the temperature control to adjust the temperature of the diode when a shift in the wavelength of the zero order beam from a non-mode hop wavelength to another wavelength is detected, adjustment of the diode temperature shifting the beam wavelength back toward the non-mode hop wavelength region.

Abstract: A scanning system with unpolarized laser, a birefringent beam splitter to split the unpolarized beam into dual orthogonally polarized beams, a polarization insensitive unitary dual beam modulator for separately modulating the beams in accordance with discrete image signal inputs, and a control for operating the modulator at optimum acoustic power levels.In an alternate embodiment, a quarter wave plate is inserted in the optical path between laser and beam splitter.

Abstract: A system for enhancing the use of digitized documents as information transmitting and storage objects in connection with an electronic printer having an image input scanner for scanning documents and converting the image content to image signals. In one embodiment, a bar-coded document has an encoded image representing a secret message, and the printer is equipped with a recognition circuit that uses the bar code to distinguish the encoded document from other non-coded documents to be printed and readies a decoder which upon proper authentication, automatically decodes the encoded image signals output by the array so that the printer provides a print with the decoded message.In a second embodiment, the digitized image comprises an auxiliary software program to be loaded into the printer memory, with a selector circuit for loading the software signals output by the array into the printer memory, with a selector circuit for loading the software signals output by the array into the printer memory.

Abstract: The stop for the Schlieren imaging optics which are used in an electro-optic line printer to image a multigate light valve onto a photosensitive recording medium has smoothly tapered sides to reduce crosstalk between the pixels of the image. As a result, the transmittance of the imaging aperture, as viewed along the modulation axis of the printer, rolls off relatively gradually and more or less continuously along the edges of the stop, thereby reducing the high angle diffraction off the stop so that the troublesome sidelobes of the coherent amplitude point spread function of the imaging system are suppressed. The stop preferably is in the shape of a parallelogram selected to substantially attenuate either the zero order or the higher order diffraction components of the phase front modulated light beam exiting from the light valve so that the intensity profile of the remaining or unattenuated light has the required image characteristics.

Abstract: An electronic reprographics/printing machine having a scanner for scanning documents where at least one of the documents contains control instructions for operating the machine in the form of a coded image in the margins; a counter for tolling a preset time interval at the start of each scan during which the coded image is looked for, where no coded image is found within the preset time interval, scanning the remainder of the document normally, where a coded image is detected, prematurely terminating scanning of the document at the end of the coded image to speed up scanner throughput rate; and a decoder for decoding any coded image detected to provide control instructions for operating the machine.

Abstract: A circuit for supplying power to the a.c. corotrons of copying or printing machines using a high leakage inductance type transformer both as a power transformer and as a low pass filter; a d.c. power source coupled to the transformer primary winding center tap; a push-pull amplifier having a MOSFET gate pair controlling energization of the transformer primary winding halves by the d.c. power source; a pulse width modulator for supplying alternating signal pulses to the MOSFET pair at a fixed frequency; a voltage doubler network for monitoring corotron current, the modulator adjusting the pulse width of the signal pulses in response to the network control signal to thereby adjust the power output of the circuit and maintain a constant corotron current; and a capacitor at the transformer output cooperable with the transformer to form said low pass filter.

Abstract: A method and apparatus for fabricating long full width scanning arrays for reading or writing images. For this purpose, smaller scanning arrays are assembled in abutting end-to-end relationship, each of the smaller arrays being provided with a pair of V-shaped locating grooves in the face thereof. An aligning tool having predisposed pin-like projections insertable into the locating grooves on the smaller scanning arrays upon assembly of the smaller arrays with the aligning tool is used to mate a series of the smaller arrays in end-to-end abutting relationship, there being discretely located vacuum ports in the aligning tool to draw the smaller arrays into tight face-to-face contact with the tool. A suitable base is then affixed to the aligned arrays and the aligning tool withdrawn.

Abstract: An IR LED array and method of fabrication having a GaAs wafer with one surface metallized to form a common LED contact. Epitaxially formed on this wafer is a GaAs/GaAlAs heterostructure with successive layers of Ga.sub.1-x Al.sub.x As-n, GaAs-p, and Ga.sub.1-y Al.sub.y As-p on the other surface, followed by an electrical contact layer of GaAs-p+ and an insulating layer of SiO.sub.2, discrete areas of the contact and insulating layers being removed by etching to form viewing windows for the individual LEDs, and with the area of the contact layer bordering the viewing windows being exposed and metallized to provide individual LED electrical contacts. In a second embodiment, the GaAs-p+ layer is dispensed with and the transparent electrically conducting coating is applied directly on both the insulating layer bordering the Ga.sub.1-y Al.sub.y As viewing windows and over the viewing windows.

Abstract: A dynamic power control for an external cavity stabilized laser diode adapted for use with a Raster Output Scanner employing a photodiode to convert light emitted from the rear facet of the diode internal cavity to an electrical signal, and a comparator for comparing the light intensity signal with a reference signal and adjusting the drive current input to the diode to maintain diode output pwer constant. In a second embodiment, diode power is taken from the zero order beam at the external cavity transmissive wavelength selecting grating, in a third embodiment from the external cavity output beam, and in a fourth embodiment, from the zero order beam that passes through the holographic disc facets.

Abstract: An image sensor array and method of fabrication which facilitates replacement of a defective one in a series of arrays butted together to form a longer scanning array in which a (110) silicon wafer having a row of photosites has separation lines etched thereon by orientation dependent etching along the (111) planes, with the separation lines for the opposite ends of the array each consisting of first and second partial boundary lines longitudinally offset from one another connected by a third boundary line so that the ends of the array have a has a generally L-shaped offset permitting bi-directional separating and aligned inserting movement when replacing a defective array.In a second embodiment, the arrays are formed on (100) silicon with alternating `nail` head and `mesa` head shapes to facilitate removal and replacement of a defective array.

Abstract: Apparatus and method of fabricating a sensor array from a (110) silicon substrate having a row of photosites to provides a sensor array chip with uniformly smooth and angled ends designed to permit the chip to be lock butted end to end with other like chips to form a full length scanning array in which the substrate is etched for separation along the (111) planes at the desired boundaries of the chip, the etched boundaries delimiting the chip ends running between selected pairs of photosites to provide whole photosites right up to the ends of the chip so as to avoid any cap or interruption between the photosites at the junctions with other chips.In a second embodiment, the chip ends are formed with complementary irregular shapes to enhance locating and butting of the chips with one another, and in a third embodiment, grooves are etched between each of the photosites in the row to assure photosite uniformity and prevent cross talk between photosites.

Abstract: A compact xerographic copying or printing machine with fuser and xerographic sections placed close together, an air manifold separating the fuser and xerographic sections having plural air passages through which cooling air flows and forming one leg of a U-shaped thermal air curtain, an air baffle between the manifold and fuser sections and cooperating with the outside of the manifold to form the second leg of the air curtain so that air leaving the manifold undergoes a 180.degree. turn and passes through the second leg to a filter and the inlet of an exhaust fan.

Abstract: A reproduction machine having a recording member, a developer housing with sump, a magnetic brush roll for bringing developer from the sump into developing relation with the recording member, a stripper plate in the developer housing for removing returning developer from the magnetic brush roll, the stripper plate being inclined and having a row if holes extending thereacross to allow the removed developer on the stripper plate to pass to the sump, and a chevron above the row of holes and closely spaced to the surface of the stripper plate for intermixing the removed developer as the developer is returning to the sump.