US 2020/0286945 A1 · IMAGE SENSORS WITH HIGH DYNAMIC RANGE AND FLICKER MITIGATION

Abstract

An imaging device may have an array of image sensor pixels. Each image sensor pixel of the array of image sensor pixels may have first and second photodiodes with different sensitivities. The photodiode having the lower sensitivity may be coupled to a storage diode and may alternately discard charge and transfer charge to the storage diode during an integration time for flicker mitigation. The length of time for which charge is discarded in each shutter cycle for flicker mitigation may be selected to adjust dynamic range of the imaging pixel. Upon conclusion of the integration time, charge from the storage diode may be sampled in a high conversion gain readout. Overflow charge from a dual conversion gain capacitor may then be sampled in a low conversion gain readout. Charge from the photodiode having higher sensitivity may finally be sampled in a high conversion gain readout.

Claims20

Dependent claims

An imaging system including an image sensor with an array of imaging pixels and processing circuitry, each imaging pixel comprising:

a first photodiode with a first sensitivity to incident light;
a second photodiode with a second sensitivity to incident light, wherein the second sensitivity is less than the first sensitivity;
a charge storage region;
a bias voltage supply terminal;
a first transistor interposed between the second photodiode and the charge storage region;
a second transistor interposed between the second photodiode and the bias voltage supply terminal, wherein the first and second transistors are alternately asserted during an integration time and wherein the processing circuitry is configured to adjust a ratio of a length of time for which the second transistor is asserted to a length of time for which the second transistor is not asserted during the integration time to control dynamic range.

3 more elements

A method of operating imaging pixel in an image sensor, wherein the imaging pixel includes a photodiode, a charge storage region, a first transfer transistor coupled between the photodiode and the charge storage region, a floating diffusion region, a second transfer transistor coupled between the charge storage region and the floating diffusion region, and an anti-blooming transistor coupled to the photodiode, the method comprising:

during an integration time, generating charge with the photodiode in response to incident light;
and
during the integration time, performing flicker mitigation operations, wherein performing the flicker mitigation operations comprises repeatedly asserting the anti-blooming transistor then asserting the first transfer transistor in cycles, wherein a ratio of a length of time for which the anti-blooming transistor is asserted compared to a length of time for which the anti-blooming transistor is not asserted in each cycle is set to control dynamic range.

Dependencies are inferred from the claim text.

Image sensors with high dynamic range and flicker mitigation

Life of this patent

Image sensors with high dynamic range and flicker mitigation

Life of this patent

Abstract

Claims20