Browse Prior Art Database

ZERO CROSSING DETECTOR/CLOCK GENERATOR FOR 60/60 HZ. OPERATION

IP.com Disclosure Number: IPCOM000023570D
Original Publication Date: 1978-Feb-28
Included in the Prior Art Database: 2004-Mar-31
Document File: 2 page(s) / 262K

Publishing Venue

Xerox Disclosure Journal

Abstract

A zero-crossing detector and programmable phase-locked loop oscillator for a copier controller logic system to synchronize effectively the same usable controller clock frequency from either 50 or 60 hertz line frequencies, and to provide 60 hertz output control pulses in both cases. Using the same zero-crossing detector circuit, comparator pulses are gener-ated at 120 hertz from a 60 hertz AC line and 100 hertz from a 50 hertz AC line (as in the U.K.). However, by selecting appropriate different frequency dividers (counters) in the feed-back comparison circuit for the clock oscillator for the two different line frequencies, and appropriate clock frequen-cies, almost the same clock frequency can be synchronized with the different line frequencies. That is, a 0.921600 megahertz frequency divided by 9216 can be phase-locked to the 100 hertz comparator pulses and a 0.983040 megahertz clock rate divided by 8192 can be phase-locked to the 120 hertz comparator pulses. Thus, effectively the same clock frequency (effec-tively 1 megahertz) can be used in the same basic copier controller with either line frequency by a simple circuit switching change by having both circuits on the same board. To generate 60 hertz output control pulses with the 50 hertz line connection, the .921600 megahertz clock frequency used in that case is divided by 15360.

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XEROX DISCLOSURE JOURNAL

ZERO CROSSING DETECTOR/CLOCK Proposed Classification
GENERATOR FOR 60/60 HZ. OPERATION U.S. Cl. 355/3
Dale C. Thomas mt. Cl. G03g 15/00

A zero-crossing detector and programmable phase-locked loop
oscillator for a copier controller logic system to synchronize
effectively the same usable controller clock frequency from
either 50 or 60 hertz line frequencies, and to provide 60
hertz output control pulses in both cases. Using the same
zero-crossing detector circuit, comparator pulses are gener-
ated at 120 hertz from a 60 hertz AC line and 100 hertz from a
50 hertz AC line (as in the U.K.). However, by selecting
appropriate different frequency dividers (counters) in the
feed-back comparison circuit for the clock oscillator for the
two different line frequencies, and appropriate clock frequen-
cies, almost the same clock frequency can be synchronized with
the different line frequencies. That is, a 0.921600 megahertz
frequency divided by 9216 can be phase-locked to the 100 hertz
comparator pulses and a 0.983040 megahertz clock rate divided
by 8192 can be phase-locked to the 120 hertz comparator
pulses. Thus, effectively the same clock frequency (effec-
tively 1 megahertz) can be used in the same basic copier
controller with either line frequency by a simple circuit
switching change by having both circuits on the same board.
To generate 60 hertz output control pulses with the 50 hertz
line connection, the .921600 megahertz clock frequency used in
that case is divided b...