Deflection apparatus for raster scanned CRT displays
US5420484A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 5, 1993 |
| Grant date | May 30, 1995 |
| Priority date | — |
| Expiry date | Apr 5, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N3/223
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Deflection apparatus for a raster scanned cathode ray tube display comprises a ramp generator (210) for producing a current ramp signal synchronised to a raster synchronisation signal. A ramp regulator (230) is connected to the generator (210) for varying the amplitude of the scan signal as a function of the difference between a reference input and a feedback signal. A feedback circuit (220) connected to the generator (210) and to the regulator (230) for generating the feedback signal as a function of the amplitude and frequency of the line scan signal. A multiplier (250) is connected to the regulator and for varying the reference input as a function of an integer multiple of the frequency of the raster synchronisation signal. Any scan signal frequency component in the feedback signal is cancelled at the input to the regulator by introducing, via the multiplier (250), a scan signal frequency component to the reference input. Because the displayed picture size is thus made independent of scan signal frequency, the deflection apparatus can maintain a constant picture size despite variations in scanning signal frequency without the bandwidth limitations of the prior art.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.