Browse Prior Art Database

VDU Screen Front Adjustment by Photosensing

IP.com Disclosure Number: IPCOM000112164D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Fenton, B: AUTHOR [+3]

Abstract

Disclosed is a system to enable automatic Front of Screen Geometry Setup of a CRT VDU. Photosensitive devices are positioned on a specially designed frame that fits over the screen, and interfaces with a microcontroller resident in the VDU. Setup is accomplished automatically at manufacture, and any drift over a period of time, easily rectified by a customer engineer. Benefits are the automatic adjustment of: Image Size, Centering, Black Level; with compensation for white level and ambient light throughout life of monitor together with skill and cost savings.

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VDU Screen Front Adjustment by Photosensing

      Disclosed is a system to enable automatic Front of Screen
Geometry Setup of a CRT VDU.  Photosensitive devices are positioned
on a specially designed frame that fits over the screen, and
interfaces with a microcontroller resident in the VDU.  Setup is
accomplished automatically at manufacture, and any drift over a
period of time, easily rectified by a customer engineer.  Benefits
are the automatic adjustment of:  Image Size, Centering, Black Level;
with compensation for white level and ambient light throughout life
of monitor together with skill and cost savings.

      After a computer monitor has been assembled and a CRT
installed, the monitor is powered up to test it.  One job after
initial power up test is to set the front of screen (FOS) geometry
which involves setting the picture to the correct width, and
adjusting any horizontal or vertical displacements, to comply with
specifications.  Conventional methods of FOS setup is by a technician
on the production line.  A test program is displayed, and the picture
is aligned manually by adjusting monitor potentiometers until the
image is correct without vertical or horizontal displacements.  The
back cover is then fitted and the monitor packed for shipping.  But
low cost microprocessors with analogue input capability has made the
use of inexpensive photoresistive light sensors built inside a
monitor economically feasible.  Photoresistive sensors can be mounted
under the edge of the bezel and provide a range of benefits to the
user and manufacturer alike.

      The new system is controlled by a microcontoller resident
inside the monitor.  The Figure shows in block for...