Differential random color switch for beam penetration CRT
US4442451A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 1, 1981 |
| Grant date | Apr 10, 1984 |
| Priority date | — |
| Expiry date | May 1, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/27
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A color switch for a beam penetration CRT can display a randomly selected color in a first color write period, and immediately after the first color write period the magnetizing current in the high voltage transformer is reset during a second write period in a complementary color. A high voltage power supply has an output voltage selected to provide a baseline color whose voltage level is intermediate the voltage range of the CRT anode. A pair of drivers are connected to either end of the primary winding of the high voltage transformer and generate a voltage differentially across the primary winding that drives the voltage level either upwardly or downwardly from the baseline level. Immediately after the first color write period, a second color write period is formed in a complementary color by transitioning a pair of input switches. This causes the color switch to change to the voltage level on the opposite side of the baseline voltage level so that the flux level in the core of the transformer is reset to a balanced DC condition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.