Automatic Pattern Generation for Self-Testing Displays
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
In a CRT color display a pattern generator is activated when externally supplied horizontal sync pulses are absent and a test pattern is displayed. This provides self-test of a display at switch on and automatic self-testing in the event of system failure. The test pattern is a series of horizontal colored bars generated by a counter which is disabled by horizontal sync pulses. The attached circuit diagram shows a pattern generator for a color monitor. While the logic interface cable is connected, no pattern is generated, but when removed, a signal is generated which displays horizontal color bars on the screen. This enables diagnosis of horizontal scan, vertical scan and each of the three video amplifiers.