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Browse Prior Art Database

Testing Method for Video Signal

IP.com Disclosure Number: IPCOM000112571D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Tanda, K: AUTHOR

Abstract

Disclosed is a method for measuring the video image by judging the separate RGB signal of a display device.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Testing Method for Video Signal

      Disclosed is a method for measuring the video image by judging
the separate RGB signal of a display device.

      The signal of the video image to be measured is asynchronous to
the DOT CLOCK of the display device.  The image data is compared to
pre-prepared, expected data, and the video image is judged correct or
not.

      The analog RGB signal shown in Fig. 1 is converted to a digital
signal by a pre-set comparator.  The threshold level of the
comparator is set to measure the voltage (video intensity) of the RGB
signal by the digital-to-analog converter.

      This converted digital signal is output to the COUNTER CIRCUIT
with H-sync and V-sync.  The COUNTER CIRCUIT measures the pixel data
on each H-sync.

      Fig. 2 shows an example measuring the video image from a
Cathode Ray Tube (CRT).  When the Nth H-sync is measured, the output
from the comparator shown in Fig. 3 is counted Toff, Tm and NR by the
COUNTER CIRCUIT.  The image data which is measured at each H-sync is
compared to expected data, and judged correct or not.

      This measurement method can be utilized for function testing of
products including CRT controllers which until now have only been
visually tested.  This automatic testing method will remove human eye
variations and reduce testing cycle times and costs.