Cathode ray tube drive circuitry
US4463288A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 31, 1981 |
| Grant date | Jul 31, 1984 |
| Priority date | — |
| Expiry date | Jul 31, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N3/2335
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Cathode ray tube drive circuitry in which non-linearity of the line scan is corrected by varying the frequency of the pel clock oscillator in accordance with anticipated variations in scanning speed. Predetermined speed corrections are stored in a digital store 23 and, by means of digital to analog converter 24 and integrator 25, are applied to the control input of a voltage controlled oscillator 13. Synchronization of the pel clock with the X-deflection waveform is effected by means of a parallel phase-locked loop comprising counter 15, sample and hold 18, amplifier 20 and low pass filter 21. Preferably a sinusoidal waveform is applied to the X-deflection coil in such a manner as to have a bidirectional raster scan, the X-deflection coil forming part of a tuned circuit of the sinusoidal waveform generator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.