Browse Prior Art Database

Method of Using Frequency And Phase of Commercial Power to Shift Image Interference to Blanking Time

IP.com Disclosure Number: IPCOM000100794D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Sakurai, A: AUTHOR [+2]

Abstract

Disclosed herein is a technique for preventing display systems from mutual image interference between two or more display systems by synchronizing the frequency and phase of vertical deflection oscillation with those of commercial power.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 69% of the total text.

Method of Using Frequency And Phase of Commercial Power to Shift Image Interference to Blanking Time

       Disclosed herein is a technique for preventing display
systems from mutual image interference between two or more display
systems by synchronizing the frequency and phase of vertical
deflection oscillation with those of commercial power.

      Display systems which have this technique have the same
frequency of vertical refresh rate as that of commercial power, 60 Hz
in the U.S., and use a "Zero Crossing" signal as a trigger of
vertical deflection oscillation to align the phase of vertical
oscillation to that of commercial power. Thus, it does not only mean
to synchronize display systems with commercial power but also to
synchronize display systems with each other.  The source of mutual
image interference is pulse- like magnetic flux generated by the
vertical deflection yoke of another display system during a blanking
("pump-up") period.  Hence, to synchronize the frequency and phase of
each display system means to shift mutual image interference to their
blanking time.

      The figure shows an exemplary block diagram for implementing
the technique.  The following is a description of the technique.

      A "Zero Crossing" detection circuit originates a pulse signal
every time that commercial power crosses the "Zero Line" at the
rising (or falling, selectable) edge.  The system logic picks up the
"Zero Crossing" signal to initialize counters in...