Vehicle headlamp control circuits
US4117453A · kind A · utility
11Cited by
3References
10Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Feb 4, 1977 |
| Grant date | Sep 26, 1978 |
| Priority date | — |
| Expiry date | Feb 4, 1997 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB60Q2300/3321
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
An automatic vehicle headlamp intensity adjustement circuit includes a high sensor. A tuned rectifier circuit for producing a d.c. signal of magnitude dependent on the amplitude of the 50Hz (or other local supply frequency) component of the signal picked up by the sensor. A lamp current modulating circuit is controlled by this d.c. signal through the intermediary of an averaging circuit. The averaging circuit has a relatively long time constant and a timer is connected to reduce this time constant if the d.c. signal continues to fall for more than a predetermined period of time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.