Browse Prior Art Database

G1 Bias Circuit for Video Display Terminals (VDT)

IP.com Disclosure Number: IPCOM000038194D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Wolgin, NB: AUTHOR

Abstract

Disclosed is a method for automatically changing the G1 bias of a Cathode Ray Tube (CRT) during the manufacturing alignment of a VDT.

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G1 Bias Circuit for Video Display Terminals (VDT)

Disclosed is a method for automatically changing the G1 bias of a Cathode Ray Tube (CRT) during the manufacturing alignment of a VDT.

The manufacturing of a VDT involves two basic processes. The first process involves some simple assembly; mounting a CRT in a bezel, mounting a card assembly and attaching a rear cover. The second process is the actual alignment of the front-of-screen (FOS) which includes the screen geometry as well as the color balance (making 'white' appear white).

This disclosure describes a simple circuit that allows the CRT bias to be changed electronically via computer control with the machine's covers installed. This is considered advantageous to manufacturing. The need to change the CRT bias during alignment is dictated by the state of the art in the light meters used by manufacturing to adjust the color balance of the VDT. The circuit itself is a transistor switch that allows a higher voltage to be applied to the G1 grid of the CRT for the duration of the color balance adjustment. The circuit is driven by an LSI module that is compatible with the Philips I2C Bus, an inexpensive 2-wire bus that communicates with the manufacturing test equipment.

(Image Omitted)

Disclosed anonymously.

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