Browse Prior Art Database

LASER RASTER OUTPUT SCANNER EXPOSURE CONTROL

IP.com Disclosure Number: IPCOM000026705D
Original Publication Date: 1993-Apr-30
Included in the Prior Art Database: 2004-Apr-06
Document File: 2 page(s) / 100K

Publishing Venue

Xerox Disclosure Journal

Abstract

It is a goal in xerographic laser printers to automatically adjust the exposure control of a raster output scanner (ROS) to match whatever photoreceptor is currently installed in the machine. Copy quality stability requirements place certain demands on the ROS light output that include: (1) a short warm-up time of less than one minute, (2) a light output that remains stable within k2.5% over a long term period of 24 hours, and (3) the ability to settle to new exposure settings within 100 milliseconds.

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XEROX DISCLOSURE JOURNAL

LASER RASTER OUTPUT Proposed Classification SCANNER EXPOSURE CONTROL U.S. C1.358/285 Joseph C. Chiang
Timothy M. Hunter Int. C1. H04N 11040 Larry A. Kovnat
Vittal U. Shenoy

XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarcWAprill993 215

[This page contains 1 picture or other non-text object]

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LASER RASTER OUTPUT SCANNER EXPOSURE CONTROL (Cont'd)

It is a goal in xerographic laser printers to automatically adjust the exposure control of a raster output scanner (ROS) to match whatever photoreceptor is currently installed in the machine. Copy quality stability requirements place certain demands on the ROS light output that include: (1) a short warm-up time of less than one minute, (2) a light output that remains stable within k2.5% over a long term period of 24 hours, and (3) the ability to settle to new exposure settings within 100 milliseconds.

Accordingly, the present invention is directed toward a control feedback loop, the control cooperating with the included elements to produce automatic correction to the ROS. As shown in the Figure, the supervisory loop 10 is comprised of a summing amplifier 12, an automatic gain control (AGC) circuit 14, a single component block 16; and a sensor device 18 that responds to physical light stimulus and transmits a resulting feedback signal back to the summing amplifier 12.

Light emitted from the ROS laser is modulated and focused onto a rotating polygon mirror to generate a scan. Warm up characteristics exhibited by the laser contained in b...