Ambient light detection
US8878830B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Sep 17, 2010 |
| Grant date | Nov 4, 2014 |
| Priority date | — |
| Expiry date | Nov 9, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J1/46
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Ambient light is detected by a photodiode circuit by measuring the time taken for a digital output of the photodiode circuit to change state in response to exposure of a photodiode of the photodiode circuit to that ambient light. A nominal time for state change is calculated based on photodiode circuit characteristics. Furthermore, an effective time for the photodiode circuit digital output to change state is determined in a calibration mode where the photodiode has been disconnected and a reference current is applied to the circuit. An illumination value of the detected ambient light is then calculated as a function of: the measured time, the effective time and the nominal time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.