Browse Prior Art Database

Color Display Convergence

IP.com Disclosure Number: IPCOM000099255D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Hillan, JM: AUTHOR [+2]

Abstract

A device is described to measure the convergence a CRT color display which provides a combination of portability and modest cost. An aperture box is across a displayed line, and points at which the level crosses a predetermined threshold are measured. color red, green and blue is displayed in turn for Similarly orthogonal lines are displayed to convergence in the other direction.

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Color Display Convergence

       A device is described to measure the convergence a CRT
color display which provides a combination of portability and modest
cost.  An aperture box is across a displayed line, and points at
which the level crosses a predetermined threshold are measured. color
red, green and blue is displayed in turn for  Similarly orthogonal
lines are displayed to convergence in the other direction.

      The device, as shown in the figure, consists of a head 1 which
is a simple aperture box arrangement front and rear apertures 2, 3
behind which a photocell is placed.  A drive motor 5 accurately
controls movement head 1 relative to CRT face 6.  By scanning this
across a displayed line, the relative position the line can be
measured by noting the points in the scan the light level reaches and
falls to a predetermined (the nominal center being half-way between
these points).

      The device has a front aperture 2 and slightly smaller aperture
3.  This device is moved at right angles to optical axis using a
miniature motor 5, having some kind positional measuring (multiturn
potentiometer, linear transducer, rotary etc.).  This device is
housed in an enclosure 7 is attached to the front of a display 6
using a method (vacuum chuck, stand, etc.).

      An electronic drive system would contain the motor drive and
position measuring system, an amplifier for the output, a comparator,
and some type of readout.

      A suitable display of horizontal or vertical lines is on the
monitor/CRT under test.  The measur...