US 8,264,568 B2Granted

Image pickup device

AssigneeTexas Instruments Incorporated

InventorsJose Tejada, Rafael Dominguez-Castro, Fernando Medeiro-Hidalgo, Francisco J. Jimenez-Garrido

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Abstract

This invention is an image pickup device that realizes a wide dynamic range while minimizing circuit area using a pixel array that can pick up a low-sensitivity image and a high-sensitivity image. This invention obtains information (S1/S2) needed for generating a correction coefficient using one more than the number of pixels readout circuits (RC1 to RCn+1). This significantly reduces the circuit area compared with the case of using twice as many readout circuits as pixels for generating the correction coefficient.

Claims9

Dependent claims

An image pick up device comprising:

a pixel array including plural pixel circuits, each pixel circuit generating a first pixel signal having a first sensitivity level and a second pixel signal having a second sensitivity level, the second sensitivity level lower than said first sensitivity level;
N signal lines;
a pixel scanning circuit that sequentially selects N pixel circuits in said pixel array and outputs said first and second pixel signals from the selected N pixel circuits to said N signal lines in a time division manner;
a plurality of readout circuits in a number at least 1 larger than N;
a connection circuit connecting at least one pair of said readout circuits to one signal line of said N signal lines and connecting each other of said readout circuits to a corresponding one of other of said N signal lines, whereby each readout circuit selecting and outputting either said first pixel signal or second pixel signal input from said corresponding one of said N signal lines;
a correction coefficient generation circuit that generates a correction coefficient corresponding to the sensitivity ratio between said first sensitivity level and said second sensitivity level;
a correction circuit that corrects the level of said second pixel signal output from each of said readout circuits to a signal level corresponding to said first sensitivity level based on said correction coefficient;
wherein each of said readout circuits selects and outputs said first pixel signal if said first pixel signal is smaller than a threshold value corresponding to the saturation signal level of the first sensitivity level and selects and outputs the second pixel signal if said first pixel signal is larger than said threshold value;
wherein for said pair of readout circuits connected to one signal line, a first readout circuit of said pair of readout circuits selects and outputs said first pixel signal and a second readout circuit of said pair of readout circuits selects and outputs said second pixel signal;
and
wherein said correction coefficient generation circuit generates said correction coefficient corresponding to a signal ratio between first pixel signal output from a first readout circuit of a pair of readout circuits connected to one signal line and the second pixel signal output from said second readout circuit of said pair of readout circuits.

8 more elements

Dependencies are inferred from the claim text.

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Abstract

An image pick up device comprising:

a pixel array including plural pixel circuits, each pixel circuit generating a first pixel signal having a first sensitivity level and a second pixel signal having a second sensitivity level, the second sensitivity level lower than said first sensitivity level;
N signal lines;
a pixel scanning circuit that sequentially selects N pixel circuits in said pixel array and outputs said first and second pixel signals from the selected N pixel circuits to said N signal lines in a time division manner;
a plurality of readout circuits in a number at least 1 larger than N;
a connection circuit connecting at least one pair of said readout circuits to one signal line of said N signal lines and connecting each other of said readout circuits to a corresponding one of other of said N signal lines, whereby each readout circuit selecting and outputting either said first pixel signal or second pixel signal input from said corresponding one of said N signal lines;
a correction coefficient generation circuit that generates a correction coefficient corresponding to the sensitivity ratio between said first sensitivity level and said second sensitivity level;
a correction circuit that corrects the level of said second pixel signal output from each of said readout circuits to a signal level corresponding to said first sensitivity level based on said correction coefficient;
wherein each of said readout circuits selects and outputs said first pixel signal if said first pixel signal is smaller than a threshold value corresponding to the saturation signal level of the first sensitivity level and selects and outputs the second pixel signal if said first pixel signal is larger than said threshold value;
wherein for said pair of readout circuits connected to one signal line, a first readout circuit of said pair of readout circuits selects and outputs said first pixel signal and a second readout circuit of said pair of readout circuits selects and outputs said second pixel signal;
and
wherein said correction coefficient generation circuit generates said correction coefficient corresponding to a signal ratio between first pixel signal output from a first readout circuit of a pair of readout circuits connected to one signal line and the second pixel signal output from said second readout circuit of said pair of readout circuits.

8 more elements