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US 8,575,533 B2Granted
High dynamic range imager circuit and method for reading high dynamic range image
AssigneePixArt Imaging Incorporation, R.O.C.
InventorsWen-Cheng Yen, Ching-Wei Chen, Chao-Chi Lee
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Abstract
The present invention discloses a high dynamic range imager circuit and a method for reading high dynamic range image with an adaptive conversion gain. The high dynamic range image circuit includes a variable capacitor. The capacitance of the variable capacitor is adjusted according to sensed light intensity or by internal feedback control, to adaptively adjust the conversion gain of the high dynamic range image circuit as it reads a signal which relates to a pixel image sensed by an image sensor device. In each cycle, the signal can be read twice or more with different dynamic ranges, to enhance the accuracy of the signal.
Claims20
A high dynamic range imager circuit, comprising:
- an image sensor device formed in a first conductive type substrate, including:
- a photosensor unit for receiving a light signal to generate and accumulate photo-generated charges;
- a floating diffusion node for storing floating diffusion charges;
- a transfer gate for coupling the photosensor unit to the floating diffusion node to transfer at least portion of the photo-generated charges to the floating diffusion node as the floating diffusion charges;
- at least one variable capacitor having a capacitance which is adjustable according to an adjustment voltage;
- and
- a dual conversion gain transistor coupled between the floating diffusion node and the variable capacitor, for receiving a conversion gain signal and electrically coupling the floating diffusion node to the variable capacitor in response to the conversion gain signal, for adjusting a gain of reading the floating diffusion charges;
- and
- a signal reading circuit coupled to the image sensor device, for converting the floating diffusion charges to a signal which indicates a pixel image sensed by the image sensor device.
6 more elements
A high dynamic range image sensor device, comprising:
- a photosensor unit for receiving a light signal to generate and accumulate photo-generated charges;
- a floating diffusion node for storing floating diffusion charges;
- a transfer gate for coupling the photosensor unit to the floating diffusion node to transfer at least portion of the photo-generated charges to the floating diffusion node as the floating diffusion charges;
- at least one variable capacitor having a capacitance which is adjustable according to an adjustment voltage;
- and
- a dual conversion gain transistor coupled between the floating diffusion node and the variable capacitor, for receiving a conversion gain signal and electrically coupling the floating diffusion node to the variable capacitor in response to the conversion gain signal, for adjusting a gain of reading the floating diffusion charges.
3 more elements
A high dynamic range imager apparatus, comprising:
- an image sensor device array, including:
- a plurality of image sensor devices arranged in a plurality of rows and columns, each of the image sensor devices including:
- a photosensor unit for receiving a light signal to generate and accumulate photo-generated charges;
- a floating diffusion node for storing floating diffusion charges;
- a transfer gate for coupling the photosensor unit to the floating diffusion node to transfer at least portion of the photo-generated charges to the floating diffusion node as the floating diffusion charges;
- at least one variable capacitor having a capacitance which is adjustable according to an adjustment voltage;
- and
- a dual conversion gain transistor coupled between the floating diffusion node and the variable capacitor, for receiving a conversion gain signal and electrically coupling the floating diffusion node to the variable capacitor in response to the conversion gain signal, for adjusting a gain of reading the floating diffusion charges;
- a signal reading circuit coupled to the image sensor device, for converting the floating diffusion charges to a signal which indicates a pixel image sensed by the image sensor device;
- a digital-to-analog conversion circuit coupled to the signal reading circuit, for converting the signal indicating the pixel image sensed by the image sensor device to a digital image signal;
- and
- an image process circuit coupled to the digital-to-analog conversion circuit, for processing the digital image signal.
9 more elements
A method of reading a high dynamic range image, comprising:
- receiving a light signal to generate and accumulate photo-generated charges;
- transferring at least portion of the photo-generated charges to a floating diffusion node as floating diffusion charges according to a transfer signal;
- electrically coupling the floating diffusion node to a variable capacitor according to a conversion gain signal, for adjusting a gain of reading the floating diffusion charges, wherein the variable capacitor has a capacitance which is adjustable according to an adjustment voltage;
- and
- reading the floating diffusion charges as a first signal, which indicates a sensed pixel image.
2 more elements
Dependencies are inferred from the claim text.