Image acquisition and processing system
US6031570A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 19, 1997 |
| Grant date | Feb 29, 2000 |
| Priority date | — |
| Expiry date | Mar 19, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N25/78
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image acquisition and processing system that can eliminate or reduce the effects of offset voltage and threshold voltage is disclosed. The system contains a plurality of operational amplifiers each is used in an integrator. Each of the operational amplifiers has an offset voltage. The output of the integrator is sampled twice by a dual sampling circuit, one when connected to a photo-sensor and the other when not connected to the photo-sensor. The difference between the two samplings cancels out the effect of the offset voltage. The system also contains a plurality of transistors used as source follower. Each of the transistors is connected to an output terminal of the dual sampling circuit. These transistors have different threshold voltages. The output of a transistor is sampled. A predetermined voltage is then applied to the transistor and the output is again sampled. The difference between these two samples cancels out the effect of the threshold voltage. The effect of the predetermined voltage can be canceled out by taking a second difference between the twice sampled output originated from two transistors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.