Xerox Corporation

James C Traino

Leon C Williams

Douglas L Keene

Joseph F Stephany

Kwok-Leung Yip

Joseph P Taillie

Thomas R Beikirch

Richard C Hogestyn

Felice A Micco

J Terrence Flynn

In a raster input scanner adapted to perform multiple scans of a document through a series of color filters, a mechanism exploits the reciprocating motion of the scanner relative to the document platen to effect the changing of filters between scans without the addition of a separate motor.

System for positioning multiple filters in a color raster input scanner

Process and apparatus for allowing a raster input scanner with scanning array to operate asynchronously in which timing of the fixed rate shift pulses which delineate the integration period of the array is changed to maintain the shift pulses in timed synchronization with a random integration signal.

System for synchronizing integration pulses with integration signal in

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.

Modulator control for automatically overcoming intensity variations in a

A system for detecting and measuring fast scan jitter having first and second photosensors combined in a unitary detector positionable in the path of a scanning beam; means for generating a packet of test pixels for modulating the scanning beam for jitter through a succession of scan lines; said first and second photosensors outputting signal pulses representing the intensity of said scanning beam following modulation by said test pixels; a differential integrator for integrating the signal pulse outputs of said first and second photosensors with one another to provide a test signal for each line scanned; a filter for smoothing said test signal, an amplifier for amplifying said test signal, a peak to peak detector for comparing the test signal of one scan line with the test signal from the succeeding scan lines to provide a jitter signal where said test signals are different; and a meter for converting said jitter signal to a visual readout.

Fast scan jitter measuring system for raster scanners

A control for modulating the scanning beam of a raster output scanner in response to both video image signal levels and beam intensity signal levels through a single port modulator driver with linear balanced amplifier. A control circuit combines the video image signals with an analog beam intensity signal to provide a composite image/intensity control signal which is input to the modulator port to regulate scanning beam intensity. The image intensity signals are derived from a memory previously loaded with data reflecting image beam intensity variations across the scan line, the memory output being updated by a signal representing current beam intensity prior to use by the control circuit.

Intensity control for raster output scanners

A raster output scanner having a movable imaging member and high intensity imaging beam for exposing the imaging member to create images thereon. A rotating polygon scans the beam across the imaging member in line by line fashion while a modulator astride the beam path modulates the beam in accordance with image signals or pixels input thereto. A clock provides clock pulses for clocking the image pixels to the modulator. To assure uniform image size despite variations in the velocity of the imaging member, a control signal representative of imaging member velocity is used to control polygon velocity and maintain a predetermined velocity relationship between imaging member and polygon. Means are provided to servo clock frequency with polygon rotation, with a control to shift the clock servo midpoint frequency in response to changes in imaging member velocity.

Image size control for raster scanners

A raster scanner has a laser as a source of a scan beam, an optical system including a rotating polygon for scanning the laser beam across the object to be scanned, and a detector pair for identifying the start-of-scan (SOS) and end-of-scan (EOS) positions of the beam scanning path. One or both detectors are modified to incorporate a peak responding circuit which produces a signal whose voltage level represents the maximum light intensity of the scan beam as the scan beam scans across the detector or detectors. The peak responding circuit includes an output tap permitting the peak signal to be read by a suitable voltage reading meter.

Beam intensity measurement system for raster scanners

A clock circuit for clocking video image signals in a raster scanner. The clock circuit includes an inverting gate enabled during scanning with gate output feedback to gate input through an adjustable time delay, the delay inherent in the gate being summed with the delay of the adjustable time delay to provide gate switching and clock output. A register compares clock scan line frequency with preselected scan line resolution and a phase comparator compares scan duration with register output to control clock frequency.

Pixel clock for scanner

Apparatus for automatic control of an image storage device. The image storage device, of the type employing a liquid crystal, is utilized in an intermediate processing step during electrostatographic reproduction of the image. An automatic sequence of voltages and illuminations are applied to the image storage device for erasing previously stored images and for preparing the device for storage of an image. The stored image can be applied to a photoreceptor element of an electrostatographic machine for reproduction of the image. The liquid crystal image storage device can be utilized in conjunction with apparatus for displaying signal encoded data. The display of the signal encoded data can be in a format inconvenient for direct application to the photoreceptor, the image storage device serving as a buffer memory for the image. The stored image can be utilized in conjunction with the electrostatographic machine to provide single or multiple copies of the image.

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Fairport, NY, United States of America

James C Traino