Integrated sensor for correlated color temperature and illuminance sensing
US7604360B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 29, 2006 |
| Grant date | Oct 20, 2009 |
| Priority date | — |
| Expiry date | Dec 14, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J2001/4247
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A sensor for measuring the properties of light from a light source is disclosed. The sensor includes first and second photodetectors that are illuminated by the light. The first and second photodetectors generate first and second photodetector signals indicative of the first and second weighted averages of the intensity of light in a wavelength band between 400 nm and 700 nm. The first photodiode is more sensitive to light having wavelengths between 400 nm and 500 nm than the second photodetector. The sensor also includes a color temperature processing circuit that generates a first processed signal that is related to a ratio of the first and second signals. The color temperature processing circuit could include first and second logarithmic amplifiers that generate first and second logarithmic signals, respectively, from the first and second photodetector signals and a subtraction circuit that forms a signal indicative of the difference between the first and second logarithmic signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.