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US 7,741,589 B2Granted
Method and apparatus providing multiple transfer gate control lines per pixel for automatic exposure control
AssigneeMicron Technology, Inc.
InventorsJorgen Moholt, Sohrab Yaghmai
Life of this patent
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Abstract
An imager device includes a pixel array having some pixels providing output signals for automatic light control with other pixels providing image output signals. Multiple pixel cells of the array may be arranged to obtain sample data indicating the amount of light reaching the array, while image pixels in the array provide captured image data. An exemplary device includes a CMOS pixel array having 4T pixels arranged in rows and columns and having two transfer transistor control lines for each row of the array. Operation of the first transfer transistor line controls the pixels used for ALC operation while operation of the second transfer transistor line controls the pixels used for image capture.
Claims31
An imager comprising:
- a pixel array comprising:
- a plurality of pixels arranged in rows and columns, each of said pixels comprising a photosensor for generating charge in response to light and a transfer transistor for transferring said charge from said photosensor to an associated floating diffusing region;
- and
- first and second transfer transistor control lines associated with at least one row of pixels, at least one pixel in said at least one row having a transfer transistor gate connected to the first transfer transistor control line and a plurality of other pixels in said at least one row having respective transfer transistor gates connected to the second transfer transistor control line,
- a control circuit coupled to said first and second transfer transistor control lines for providing at least one first transfer control signal to said first transfer transistor control line during an integration period of said plurality of other pixels to transfer charges generated by said at least one pixel to an output circuit;
- and
- a light control circuit responsive to charges transferred to said output circuit for controlling a duration of said integration period of said plurality of other pixels,
- wherein said control circuit is configured to provide at least one second transfer control signal to the second transfer transistor control line at an end of said first integration period to transfer charges generated by the photosensors of said plurality of other pixels during said first integration period.
5 more elements
An imager comprising:
- at least one first pixel and a plurality of second pixels located in a row of pixels, each of said first and second pixels comprising:
- a photosensitive device;
- a transistor for transferring charge from said photosensitive device to a storage region;
- circuitry for reading out a signal from said storage region, the signal representing an amount of charge transferred to said storage region;
- and
- a reset device for resetting said storage region while said transistor for transferring charge is switched off to hold said charge at said photosensitive device,
- wherein said transistor in said at least one first pixel is constructed to receive at least one first transfer control signal over a first control line, and said transistor of each of said plurality of second pixels is constructed to receive a second transfer control signal over a second control line;
- a control circuit for providing said at least one first control signal to said first control line during an image frame to output a signal;
- and
- a light control circuit configured to control a duration of said image frame based on said signal.
7 more elements
An imager comprising:
- a pixel array comprising:
- at least one first pixel and a plurality of second pixels located in a row of pixels, each of said first and second pixels comprising:
- a photosensitive device;
- a transistor for transferring charge from said photosensitive device to a storage region;
- circuitry for reading out a signal from said storage region, the signal representing an amount of charge transferred to said storage region;
- and
- a reset device for resetting said storage region while said transistor for transferring charge is switched off to hold said charge at said photosensitive device,
- wherein said transistors for transferring charge in said first and second pixels are connected to respective first and second transfer control lines;
- a control circuit for providing least one first control signal to said first transfer control line to output a signal from said at least one first pixel during an integration period of at least one of said second pixels;
- and
- a light control circuit for controlling said integration period of said at least one second pixel based on said signal from said at least one first pixel.
8 more elements
A computer system comprising:
- a processor;
- and
- an imaging device connected to said processor and comprising:
- a pixel array comprising a plurality of pixels for producing an image and being arranged in rows and columns, said plurality of pixels comprising at least one row of pixels associated with first and second transfer control lines,
- wherein in said at least one row, at least one first pixel comprises a first transfer transistor gate that is connected to the first transfer control line and a plurality of said pixels have respective second transfer transistor gates connected to the second transfer control line, each of said first and second transfer transistors being configured to transfer photogenerated charge to an associated floating diffusion region;
- a control circuit for providing at least one first control signal to said first transfer control line to output a signal from said at least one first pixel during an integration period of at least one of said second pixels;
- and
- a light control circuit for controlling said integration period of said at least one second pixel based on said signal from said at least one first pixel.
5 more elements
A method of operating a pixel array comprising:
- applying a first control signal on a first transfer transistor control line to activate a first transfer transistor of a first pixel of a row during an integration period of a second pixel in the row, the first transfer transistor transferring charge to a charge storage region;
- reading out a signal from said first pixel based on said charge transferred by said first transfer transistor;
- using said readout signals from said first pixel to determine an end of the integration period of the second pixel;
- and
- applying a second control signal along a second transfer transistor control line to activate a second transfer transistor of the second pixel at the end of the integration period of the second pixel, the second transfer transistor transferring charge to a charge storage region,
- wherein said first control signal is applied along said first transfer transistor control line multiple times during said integration period.
3 more elements
A method of operating a pixel array comprising:
- transferring first photo-charges from a first photosensor in a row of pixels in the array during a frame to generate a light control signal by applying a first transfer control signal on a first transfer transistor control line to transfer charge to a charge storage region;
- and
- transferring second photo-charges from a second photosensor in the row of pixels during the frame to generate a pixel image signal by applying a second transfer control signal on a second transfer transistor control line at a time determined according to the light control signal to transfer charge to a charge storage region,
- wherein said light control signal is output to an input of a light control circuit,
- wherein said light control circuit causes a readout of pixel image signals from a row of pixels in said array when a threshold is reached, and
- wherein said light control circuit determines when said threshold is reached by comparing at least one light control signal to said threshold.
3 more elements
Dependencies are inferred from the claim text.