Automatic convergence and gray scale correction for television _receivers and projection television systems
US4485394A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 27, 1982 |
| Grant date | Nov 27, 1984 |
| Priority date | — |
| Expiry date | Sep 27, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N17/04
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A system for the automatic correction of convergence and gray scale in color television employs light sensors, either singly or in an array, on the beam landing face of a cathode ray tube or on the screen of a projection receiver. The sensors can be placed in the overscanned area of the raster, such that they are outside the normal viewing area, or in the viewing area if the sensors are made sufficiently small. In the vicinity of a sensor, two of the three cathode ray tubes or electron guns are blanked. As the light beam, in the case of a projection system, crosses the sensor, an output is produced. This output is processed to obtain accurate timing characteristics. Since the position of the sensor is known in terms of counts in both the vertical and horizontal directions, error signals can be developed by comparing the timing of the sensor output with the proper count. These error signals are used to develop vertical and horizontal correction signals to correct the convergence of the one cathode ray tube or gun. The process is then repeated for the remaining two cathode ray tubes or guns. The output of the sensor is also amplified by gated amplifiers for each of the cathode ray tu…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.