Device and method of fitted variable gain analog-digital conversion for an image sensor

A technology of image sensor and conversion equipment, applied in the direction of analog/digital conversion, image communication, code conversion, etc., can solve problems such as inability to adapt to voltage or current signal conversion, and achieve the effect of reducing energy consumption

Inactive Publication Date: 2005-02-02
ASULAB SA
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  • Claims
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Problems solved by technology

[0016] A drawback of the conversion device of the above patent is that it cannot accommodate the conversion of a voltage or current signal as a function of the voltage or current level of the analog signal to be converted

Method used

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  • Device and method of fitted variable gain analog-digital conversion for an image sensor
  • Device and method of fitted variable gain analog-digital conversion for an image sensor
  • Device and method of fitted variable gain analog-digital conversion for an image sensor

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Embodiment Construction

[0037] In the following description, electronic components and conversion steps of a variable gain analog-to-digital conversion device known to those skilled in the art will not be explained in detail.

[0038] exist figure 2 Among them, an image capture system 10, notably of the APS type, comprises a variable gain analog-to-digital conversion device 1 according to the invention. The system essentially comprises: an image sensor 11 consisting of a photosensitive unit 2 with a matrix of pixels to capture an image 12, a device 1 for analog-to-digital conversion of the signals provided by the pixels in the sensor, an illuminance averaging unit 5, a scale adapter 4 , means for storing digitized images 6 , microprocessor unit 7 and captured image display device 8 . For example, the pixel matrix of an APS Video Graphics Array (VGA) image sensor includes 640x480 pixels, operating in a dynamic range of approximately 1.5V.

[0039] The transformation device 1 , subject of the present...

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Abstract

The variable gain analog-to-digital conversion device (1) for an image sensor comprises at least one N-bit non-linear coarse first converter (21) receiving a pixel voltage signal (Vpix) and at least one M-bit linear fine second converter (22) connected to the first converter (21) in order for the device to supply a binary word of N+M bits relating to the voltage level of the pixel. The first converter (21) comprises comparison means (33) for comparing the voltage level of the pixel with one or more voltage thresholds (V0 to V4) delimiting voltage ranges within the voltage dynamic range of the sensor. The successive voltage ranges represent areas of illumination of the pixel ranging from a weakly lit area to a strongly lit area. The first comparator supplies an N-bit binary word relating to the area of illumination determined for the pixel. The second converter comprises conversion adaptation means for converting the voltage pixel signal to a number of bits less than or equal to M, depending on the N-bit binary word from the first converter.

Description

technical field [0001] The present invention relates to a suitable variable gain analog-to-digital conversion device. The conversion device preferably digitally converts a signal generated by a photosensitive cell of the image sensor. The photosensitive unit consists of a matrix of pixels. Background technique [0002] Therefore, the conversion device comprises at least one N-bit first converter receiving a voltage or current signal of a pixel, and at least one M-bit second converter connected to the first converter, the first and second converters convert the pixel's Voltage or current level conversion is N+M bits. The voltage or current level of the signal generated by each pixel is dependent on the light energy levels the pixel will obtain over the sensor's dynamic range of particular voltage or current levels. [0003] The first converter of the device comprises comparison means for comparing the voltage or current level of the pixel with one or more voltage or curren...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03M1/20H03M1/08H03M1/14H03M1/18H04N5/235H04N5/335
CPCH04N5/335H03M1/187H04N5/235H04N23/70H04N25/00H03M1/20
Inventor F·埃比L·格尼罗德
Owner ASULAB SA
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