Browse Prior Art Database

COPIER OPTICS SCANNING SERVO IMPLEMENTED BY MICROPROCESSOR

IP.com Disclosure Number: IPCOM000026687D
Original Publication Date: 1993-Apr-30
Included in the Prior Art Database: 2004-Apr-06
Document File: 4 page(s) / 162K

Publishing Venue

Xerox Disclosure Journal

Abstract

A copier optics servo system uses a microprocessor to provide phase-locking, speed feedback, phase compensation and pulse width modulation. As shown in Fig. 1, a DC motor 2 drives the scan s stem. Attached to the

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XEROX DISCLOSURE JOURNAL

COPIER OPTICS SCANNING SERVO IMPLEMENTED BY MICROPROCESSOR
J. A. MacAndrew

Proposed Classification
U.S. C1.3551233
Int. C1. G03g 15/28

Ch.A+ Ch.B

7

FIG. I

XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarcWAprill993 161

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Page 2 of 4

COPIER OPTICS SCANNING SERVO IMPLEMENTED BY MICROPROCESSOR (Cont'd)

   Master 1. Encoder Factored Encoder

Motor Encoder CNA

PLL

F-v

*- Master

I

3.

4.

5.

6.

FIG. 2

162 XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarcWApril 1993

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COPIER OPTICS SCANNING SERVO IMPLEMENTED BY MICROPROCESSOR (Cont'd)

A copier optics servo system uses a microprocessor to provide phase-locking, speed feedback, phase compensation and pulse width modulation.

As shown in Fig. 1, a DC motor 2 drives the scan s stem. Attached to the

from the encoder are fed to a microprocessor 6 (signals 3 & 4, Fig. 21, to ether with the output from a master (or photoreceptor) encoder 8 (signal 1, fig. 2). The master encoder signal is factored in frequency within the micro rocessor 6

channel of the motor encoder 4 when d e motor is driving the scan system at precisely the required speed (signal 2, Fig. 2).

The hase-locked loop (PLL) is realised as follows: on every risin

ei er channel A or channel B chan es state (signals 3 & 41, ge same constant

value, which grows larger with time if the times.4 motor frequency is less than the master frequency, and larger if this frequency is greater. Whenever these two frequencies are equal, the contents of the register oscillate between two values, of which the mean value is roportional to the phase difference between the two signals (signal 5, Fig. 8 .

Speed feedback is realised by adding the constant to the register at a fixed interval after the constant has been extracted from it because of a change of state of channel A or B. The mean value of the register is thus inversely proportional to the motor speed (signal 6, Fig. 2).

The command signal to the motor consists of the superposed signals 5 and 6 (signal 7, Fig. 2). This constitutes the scan network.

Rescan or fl back is realised by making the co...