Display device including a black level setting circuit
US5278476A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 29, 1992 |
| Grant date | Jan 11, 1994 |
| Priority date | — |
| Expiry date | Oct 29, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2320/043
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
One of the problems in display devices is that the black level is different for each type of display tube and is also dependent on temperature and ageing. The display devices hitherto known with black level setting circuits apply one control voltage to the relevant cathode during the field blanking interval, whereafter the cathode current is measured and subsequently compared with a reference current. Subsequently, the black level is adapted until the measured current approximately corresponds to the reference current. The display device now includes a black level setting circuit with a control circuit adapted to successively apply at least two control voltages in a predetermined ratio to the cathode. Moreover, the black level setting circuit includes a correction circuit for supplying a correction value dependent on the ratio between the currents generated in the relevant cathode in response to the at least two control voltages.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.