Xerox Corporation

Douglas G Wiggins

James C Stoffel

Richard H Tuhro

William Kingsley

Robert F Allis

Ronald G Matteson

John F Moreland

Edward L Kushall

Pierre Elie, Jr

A raster input scanner having a movable carriage bearing at least one scanning array, illumination lamp, lens, and mirrors, the carriage being operatively disposed in scanning relation to a transparent glass platen on which the document original to be scanned rests, and with a platen cover for overlaying the platen and the document original thereon during scanning, the inside surface of the platen cover being corrugated and covered with a highly reflective material to expose, through specular reflection, the scanning array to intensely bright light whenever the cover inside surface is scanned enabling the boundaries of the document original to be identified and image signals not associated with the document original to be discarded.

Platen cover for document boundary detection in raster scanners

An image input terminal (IIT) with automatic document handler for feeding documents to be scanned into registered position on the IIT platen. The IIT includes a pair of multi-element scanning arrays with cooperating scan lamp and optics on a movable carriage disposed in scanning relationship with the platen. Analog image signals generated by the scanning arrays are initially processed in separate channels and then combined into a serial stream. The stream of analog image signals may optionally be thresholded or screened to provide binary level image signals or converted to multi-bit gray scale. A control system including microprocessor provides timing and control signals for synchronizing operation of the scanning carriage, document handler, and image signal reading and processing together with electronic crossover between arrays to avoid loss of data, automatic signal gain and deletion of bad image signals or pixels. On board array alignment apparatus permits adjustment of array focus, skew, height, position and overlap.

Multiple mode raster scanner

A raster input scanner of the type having a linear array for scanning a relatively moving document line by line, there being lamp means to illuminate at least a line-like portion of the document and optical means to transmit image rays from the document to the array. To provide uniform illumination and obviate illumination degradation due to the effects of cosine 4th law, flare light, lamp fall-off, etc., an apertured mask is provided between the array and the document, the mask aperture uniformly changing in size from a minimum at the array center to a maximum at the array ends. To obviate system M.T.F. degradation, the height of the mask aperture is made less than the width of the array photosites.

Illumination control for raster input scanners

An image thresholding system employing a ROM look up table to make threshold decisions. A plurality of shift registers are used to convert a digital pixel input which includes the pixel to be processed to an address for use in addressing the ROM look up table to provide a thresholded value for the pixel being processed. The output of the ROM look up table is utilized, together with other pixels from the pixel input, to address a second ROM look up table to provide a further refined threshold decision.

Image thresholding system

An image input terminal (IIT) with automatic document handler for feeding documents to be scanned into registered position on the IIT platen. The IIT includes a pair of multi-element scanning arrays with cooperating scan lamp and optics on a movable carriage disposed in scanning relationship with the platen. Analog image signals generated by the scanning arrays are initially processed in separate channels and then combined into a serial stream. The stream of analog image signals may optionally be thresholded or screened to provide binary level image signals or converted to multi-bit gray scale. A control system including microprocessor provides timing and control signals for synchronizing operation of the scanning carriage, document handler, and image signal reading and processing together with electronic crossover between arrays to avoid loss of data, automatic signal gain control, and deletion of bad image signals or pixels. A defocused calibration strip is scanned to provide shading signals for calibrating the individual scanning elements of the arrays, the shading signals being processed in successive blocks each of which comprises a preset number of shading signals. Following processing, the shading signals are stored in memory and accessed during normal scanning. The shading signals are employed in all operational modes to compensate the image signals produced by the IIT for deficiencies in the scanning components.

Shading compensation for scanning apparatus

An image input terminal (IIT) with automatic document handler for feeding documents to be scanned into registered position on the IIT platen. The IIT includes a pair of multi-element scanning arrays with cooperating scan lamp and optics on a movable carriage disposed in scanning relationship with the platen. Video image signals generated by the scanning arrays are initially processed in separate channels and then combined into a serial stream. The stream of video image signals may optionally be thresholded or screened to provide binary level image signals or converted to multi-bit gray scale. A control system including microprocessor provides timing and control signals for synchronizing operation of the scanning carriage, document handler, and image signal reading and processing together with electronic crossover between arrays to avoid loss of data, automatic signal gain control, and deletion of bad image signals or pixels. On board array alignment apparatus permits adjustment of array focus, skew, height, position and overlap.

Carriage speed control for a raster scanner

An image input terminal (IIT) with automatic document handler for feeding documents to be scanned into registered position on the IIT platen. The IIT includes a pair of multi-element scanning arrays with cooperating scan lamp and optics on a movable carriage disposed in scanning relationship with the platen. Analog image signals generated by the scanning arrays are initially processed in separate channels and then combined into a serial stream. The stream of analog image signals may optionally be thresholded or screened to provide binary level image signals or converted to multi-bit gray scale. A control system including microprocessor provides timing and control signals for synchronizing operation of the scanning carriage, document handler, and image signal reading and processing together with electronic crossover between arrays to avoid loss of data, automatic signal gain control, and deletion of bad image signals or pixels.

Gain control for scanning arrays

A system for restoring image signal levels and setting signal gain for charge coupled imaging devices (CCDs). Following the last image signal or pixel in a line of image data, a predetermined sequence of dark level signals (D) and light level signals (L) are shifted out of the CCD. The dark level signals are the absence of all image information, while the light level signals represent signals introduced at the appropriate time early in the shifting cycle. At the CCD output, the dark and light level signals are isolated and processed by an MPU in accordance with pre-established functions to provide an offset potential and gain multiplicand. The offset potential and gain multiplicand determined are used to remove the offset and set signal gain for the next succeeding line of image signals. The process is repeated as each line of image signals are output from the CCD.

Signal restoration and gain control for image viewing devices

A control device in which the dispensing of particles from a storage container to a mix is regulated. At predetermined sampling intervals, the concentration of particles in the mix is detected and a signal indicative thereof generated. These signals are summed and processed by a program to develop an actuating signal. The actuation signal energizes the storage container to dispense particles into the mix.

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Penfield, NY, United States of America

Douglas G Wiggins