Browse Prior Art Database

Software Controlled Video Signal Regulation

IP.com Disclosure Number: IPCOM000109002D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Harley, M: AUTHOR

Abstract

Disclosed is a production method for accurately setting up video signal levels in color VDUs by software control sampling a single reference; a one-time modification to the graphics adapter hardware is required. Each red, green and blue signal is separately and independently adjusted at several common regulation points from peak video downwards using table entries stored in the program. It provides repeatable and automatable advantages over conventional manual signal adjustments or digi-pot programming.

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Software Controlled Video Signal Regulation

       Disclosed is a production method for accurately setting
up video signal levels in color VDUs by software control sampling a
single reference; a one-time modification to the graphics adapter
hardware is required.  Each red, green and blue signal is separately
and independently adjusted at several common regulation points from
peak video downwards using table entries stored in the program.  It
provides repeatable and automatable advantages over conventional
manual signal adjustments or digi-pot programming.

      For VDU set-up and inspection processes, the accuracy and
correlation of signals are required at only a few regulation points,
e.g., full video, 2/3 video, etc.  The method reduces the number of
digital values which give analog approximations within the video
signal-range and increases the DAC's step sizes.  It is most suitable
for use where hardware can be dedicated to the set-up/inspection
process but not for consistency between all graphics adapters.

      For software control of regulation, DAC reference circuitry
must be adjusted, by a one-off hardware modification, so that the
full-scale signal level is greater than the regulation max output
target, say 700 mV.  Precautions should be taken to ensure that the
reference signals do not exceed manufacturer's recommendations.  At
this point, some digital value, probably not the previous digital
maximum, can be converted to an approximation of the regulation
maximum output target.  By the same argument, the digital
representations of oth...