Instrument panel illumination dimming control
US4029991A · kind A · utility
27Cited by
3References
3Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Apr 14, 1976 |
| Grant date | Jun 14, 1977 |
| Priority date | — |
| Expiry date | Apr 14, 1996 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/30
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The brightness of an LED display on an automobile instrument panel is independent of the battery voltage but does depend on the position of the instrument panel illumination dimmer potentiometer. The voltage applied to the LED is limited to a maximum by a zener diode control circuit and that voltage is reduced by a voltage detector circuit which senses the difference between the battery voltage and the dimmer potentiometer output voltage to reduce the LED voltage in proportion to that difference. The voltage detector circuit is disabled when vehicle parking lamps are turned off to insure maximum LED brightness in daytime driving.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.