Ramp-type analogue-digital conversion, with multiple conversions or single conversion, depending on the light level received by a pixel
US9736414B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 9, 2014 |
| Grant date | Aug 15, 2017 |
| Priority date | — |
| Expiry date | Oct 9, 2034 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M1/14
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a matrix image sensor, a method of reading a pixel of a column allows two modes of analogue-digital conversion of the voltage level provided by the column: a first mode in which are carried out a single analogue-digital conversion in a nominal conversion time window FCONV, of nominal duration dn and a counting which starts with a ramp of nominal duration dn and stops upon the toggling of the output SCMP of the comparator; and a second mode which provides for multiple conversions by comparison with a ramp of reduced duration dr, in the same nominal conversion time window. The selection of the mode of conversion to be applied is based on the observation of the state of the output SCMP of the comparator after a predetermined duration after the instant ti of ramp start: if the output has toggled, the useful level to be converted represents a low light level to which the second mode with multiple conversions will be applied; if the output has not toggled, the useful level to be converted represents a high light level and the first, conventional, mode with single conversion will be applied. The invention makes it possible to improve the signal-to-noise ratio at the output of the senso…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.