Differential color sensor without filters
US7220959B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 16, 2004 |
| Grant date | May 22, 2007 |
| Priority date | — |
| Expiry date | Aug 16, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10F30/21
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A semiconductor color sensor implemented without the use of color filters. Fabricating photodiodes using different semiconductor materials provide photodiodes with different sensitivities vs. wavelengths. A first embodiment uses photodiodes with different junction depths. A shallow junction depth produces a photodiode with its sensitivity peak in shorter wavelengths, while a deeper junction depth produces a photodiode with its sensitivity peak in longer wavelengths. Amorphous as well as crystalline structures may be used. A second embodiment uses photodiodes with different materials, such as Silicon-Germanium (SiGe) which has a longer wavelength peak sensitivity, and Silicon (Si) which has a shorter wavelength peak sensitivity in comparison. More than two photodiodes having different wavelength sensitivities may be used. Sensing current ratios between pairs of diodes allows color balance to be maintained.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.