DUAL SENSITIVITY IMAGE SENSOR
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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.
22 Citations
52 Claims
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1-32. -32. (canceled)
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33. 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 (34, 35, 36, 37, 38, 39)
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40. An image sensor comprising:
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A plurality of pixels arranged in rows and columns, at least one of the pixels comprising; high and low sensitivity photosensors for outputting a high and low sensitivity signals, respectively, wherein said high sensitivity signal is obtained by integration of the high sensitivity photosensor over a first integration period, and said low sensitivity signal is obtained by integration of the low sensitivity photosensor over a second integration period; and readout circuitry connected to the low sensitivity photosensor, wherein said high sensitivity photosensor is connected to the low sensitivity photosensor such that the high sensitivity signal can be sampled by the readout circuitry by transfer to and subsequent sampling of the low sensitivity photosensor after said low sensitivity signal has been sampled. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47)
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48. An image processor, comprising
a processor; - and
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 (49, 50, 52)
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52-1. The image processor of claim 48, further comprising a control circuit, operating to control said first and second integration periods such that the first integration period is at least as long as the second integration period and the overlap between the two periods is at least 80%.
Specification