Ambient light sensing method and apparatus
US5003288A · kind A · utility
357Cited by
2References
7Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Oct 25, 1988 |
| Grant date | Mar 26, 1991 |
| Priority date | — |
| Expiry date | Oct 25, 2008 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB60Q2300/314
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A telltale for sensing and responding to ambient light levels. A photosensor monitors light levels and causes a bulb or other controlled element to be energized if ambient levels reach a threshold. In one embodiment a time delay is instituted between sensing the threshold light level and bulb energization. This prevents false triggering on transitory conditions. An additional embodiment has a threshold level that uses hysteresis to avoid unstable sensing near the threshold level. A preferred use for the telltale is in apprising a motor vehicle operator when to turn on the vehicle headlamps.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.