Raster width correction apparatus for multi scan frequency monitors
US4677350A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 18, 1986 |
| Grant date | Jun 30, 1987 |
| Priority date | — |
| Expiry date | Aug 18, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N3/233
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a deflection circuit that operates in any scan frequency selected from a plurality of frequencies, the supply voltage that is DC-coupled to a first terminal of a trace capacitor is increased when the scan frequency increases. The deflection circuit includes a diode modulator that is controlled by a modulation voltage having an AC component voltage that varies at a vertical rate. The increase in the supply voltage causes an increase in a DC component voltage of the modulation voltage that is coupled to a second terminal of the trace capacitor such that the voltage in the trace capacitor increases in the same proportion as the supply voltage. The proportional increase in the trace capacitor voltage maintains the raster width unchanged when the scan frequency increases.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.