Computer graphics processing and selective visual display system – Display driving control circuitry
Reexamination Certificate
1999-01-26
2001-04-17
Hjerpe, Richard (Department: 2774)
Computer graphics processing and selective visual display system
Display driving control circuitry
C324S407000, C324S539000, C324S556000, C345S904000
Reexamination Certificate
active
06219039
ABSTRACT:
BACKGROUND
The disclosures herein relate generally to personal computer (“PC”) test devices and, more particularly, to a compact PC video subsystem test device.
In a PC manufacturing environment, a large number of PCs are produced daily. Understandably, therefore, it is highly desirable for factory testing personnel, as well as development engineers, to be able to quickly and reliably test the basic functionality of, for example, the video subsystem of every PC. One method of accomplishing the forestated task is to connect a monitor to the PC and boot it up. During POST, a audible “beep code” will be output to indicate the status of the video subsystem; however, often, the status indicated by this beep code does not reveal the true status of the video subsystem. Moreover, the need to connect and subsequently disconnect a monitor to and from each PC in order to test the video subsystem thereof slows down the testing process. In addition, testing of the energy saving modes of every PC manufactured also currently necessitates the connection of a monitor or oscilloscope to the PC.
Accordingly, what is needed is a simple, convenient, and reliable method of performing video subsystem testing of a PC in a manufacturing environment that does not require a monitor to be attached to the PC to perform such testing.
SUMMARY
One embodiment, accordingly, provides a method and apparatus for testing the video subsystem of a PC in a manufacturing environment. Hsync and Vsync signals from a VGA connector of the PC are input to first and second trigger inputs, respectively, of a monostable multivibrator (“MM”) of the test device to drive respective outputs thereof. In particular, the presence of Hsync at the first trigger input triggers the MM to output a positive pulse at a first output thereof; similarly, the presence of Vsync at the second trigger input triggers the MM to output a positive pulse at a second output thereof. Each of the first and second outputs is used to drive an LED, such that the presence of Hsync and/or Vsync results in the illumination of a corresponding LED. The test device is powered off of a +5V power supply from the video subsystem of the PC. When the subsystem is in one of the predefined energy saving modes, one or both of the Hsync and Vsync signals will be absent, resulting in the dimming of the corresponding LED(s).
A technical advantage achieved is that a monitor need not be connected to each PC to test the video subsystem thereof.
Another technical advantage achieved is that the test device is more reliable than a “beep code” during POST for indicating the status of the video subsystem of a PC.
Yet another technical advantage achieved is that the test device is highly compact and therefore easy to connect and disconnect from the PC before and after testing.
Still another technical advantage is that the test device is capable of determining the existence of these two signals regardless of their polarities, duty cycles, or frequencies.
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Chang Luke L.
Cooke Collin
Dell USA L.P.
Dinh Duc Q.
Haynes and Boone L.L.P.
Hjerpe Richard
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