Dual sensitivity image sensor
First Claim
1. A dual sensitivity pixel comprising:
- first and second photosensors, the first photosensor being of a higher light sensitivity than the second photosensor;
a transfer gate positioned between the first and second photosensors; and
readout circuitry connected to the second photosensor operable to produce output signals corresponding to charge produced by each of the first and second photosensors during respective first and second overlapping integration periods,wherein the first photosensor is readout by sampling charge stored in the second photosensor after the transfer gate positioned between the first and second photosensors is activated to cause charge produced by the first photosensor to be transferred to the second photosensor.
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Accused Products
Abstract
A system of taking images of different sensitivities at the same time uses both an image sensor, and an auxiliary part to the image sensor. The image sensor element can be a photogate, and the auxiliary part can be the floating diffusion associated with the photogate. Both the photogate and the floating diffusion accumulate charge. Both are sampled at different times. The floating diffusion provides a lower sensitivity amount of charge than the photogate itself. The system can have a photogate and floating diffusion in each pixel along with a select transistor, a reset transistor, and a follower transistor. All of this circuitry can be formed of CMOS for example. The system can also operate in a column/parallel mode, where each column of the photo sensor array can have a column signal processor which samples and holds the reset signal, the floating diffusion signal and the photogate signal.
17 Citations
12 Claims
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1. A dual sensitivity pixel comprising:
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first and second photosensors, the first photosensor being of a higher light sensitivity than the second photosensor; a transfer gate positioned between the first and second photosensors; and readout circuitry connected to the second photosensor operable to produce output signals corresponding to charge produced by each of the first and second photosensors during respective first and second overlapping integration periods, wherein the first photosensor is readout by sampling charge stored in the second photosensor after the transfer gate positioned between the first and second photosensors is activated to cause charge produced by the first photosensor to be transferred to the second photosensor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An image processor, comprising a processor;
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an imager, comprising; a pixel array arranged in rows and columns, at least one pixel in the array comprising; high and low sensitivity photosensors; a transfer gate positioned between the high and low sensitivity photosensors; and readout circuitry connected to the low sensitivity photosensor operable to produce output signals corresponding to charge produced by each of the high and low sensitivity photosensors during respective first and second overlapping integration periods, wherein the high sensitivity photosensor is readout by sampling charge stored in the low sensitivity photosensor after the transfer gate positioned between the high and low sensitivity photosensors is activated to cause charge produced by the high sensitivity photosensor to be transferred to the low sensitivity photosensor. - View Dependent Claims (9, 10, 11, 12)
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Specification