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Browse Prior Art Database

Display Error-Sensing Device

IP.com Disclosure Number: IPCOM000100593D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 126K

Publishing Venue

IBM

Related People

Breyfogle, FW: AUTHOR [+2]

Abstract

The disclosed system detects when a gross failure of a display device, particularly a cathode-ray tube (CRT), has occurred. Common failures of this nature include such things as rolling screens, all white or all dark screens, or severe misalignment.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Display Error-Sensing Device

       The disclosed system detects when a gross failure of a
display device, particularly a cathode-ray tube (CRT), has occurred.
Common failures of this nature include such things as rolling
screens, all white or all dark screens, or severe misalignment.

      The system has several sensors mounted in a frame for
monitoring intensity of light emitted by the face of the display at
several points on the screen.  Test cases drive the display so that
an image appears under each sensor in a predetermined sequence and
combination.  The sensor outputs are compared with anticipated values
derived from the test case at key points in the test procedure.  If
improper outputs are detected, an error is recorded detailing the
nature and time of the failure.

      Installation of the sensor frame on the display to be tested
requires an initial "set-up pattern" which is used to verify that at
least some image can be displayed and also features strategically
placed "markers" to be used for aligning the sensor frame to the
screen.  Suction cups may be used to attach the sensor frame to the
face of the display, thereby facilitating quick set up and removal
with minimal potential for damaging the display.

      Many different physical shapes for the device can yield
satisfactory results.  A "hoop" shape has the advantage of minimizing
the area of the display masked from direct observation yet still
offers sufficient sensing area.  The sensors in the device that
actually detect light emitted from the display would feature rubber
or foam gasket material allowing ambient light to be blocked out.

      Depending upon the sensor type, sensitivity, and geometry,
applications for this system may be extended from detecting gross
failures to the realm of detecting less obvious failures related to
specification limits, such as phosphor degradation in CRTs.

      Fig. 1 illustrates a sample sensor frame design.  Each block
represents a housing which contains an optically sensitive
semiconductor, such as a photodiode or phototransistor, embedded in a
soft opaque material (such as foam rubber) which can conform to the
curvature of the display screen and block out ambient light not
emitted by the display.  An aperture is made in the opaque material
so that light from a graphic on the display screen illuminates the
photosensitive device.  The individual sensor assemblies are held in
position b...