Image sensor and image sensor chips therefor including dummy photocells and internal discharge switches
US5268765A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 15, 1992 |
| Grant date | Dec 7, 1993 |
| Priority date | — |
| Expiry date | Apr 15, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N25/7013
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image sensor and image sensor chip therefor which generates a reference level for the dark output during the blanking period of the sensor and which provides internal switching for removing residual charge from a waveform shaping capacitor. In one embodiment, image sensor chips are arranged in a line and cascaded to form an image sensor and a dummy photocell is provided which is configured similarly to the image sensor photocells and which has its windows shielded from light. A dummy select switch selectively makes connections with a signal line to which the signals from the image sensor photocells are outputted. The dummy select switch remains closed after completion of the drive period of the photocells at the last image sensor chip and the output of the dummy photocell is used as the reference level for the dark output during the blanking period. In another aspect of the invention, a switch is provided within the chip to remove residual charge from the waveform shaping capacitor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.