Image Sensor Noise Cancellation via Correlated Dual Sampling
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Solution Overview
Problem
Image sensors in imaging devices often suffer from noise during the readout process, which can degrade the actual resolution of captured images.
Innovation Solution
The implementation of a pixel array with correlated dual sampling units and analog-to-digital converters, where the dual sampling units convert both digital and electric signals into correlated dual sampling signals to denoise the signals, effectively reducing noise generated by the image sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the image sensor reads out signals from pixel cells, then the image data is obtained, but noise is introduced during the readout process
Solution Approach 1:
The patent applies preliminary action by performing correlated dual sampling before the final signal output. The circuit samples the reset signal and the image signal separately, then subtracts the reset signal from the image signal to remove noise components before the signal is fully processed and output. This preliminary noise cancellation improves image quality without adding complexity to the overall readout process.
Solution Approach 2:
The patent introduces an intermediary correlated dual sampling circuit that acts as a mediator between the pixel array and the output. This circuit includes sampling capacitors and subtraction circuits that process the signals intermediate to the raw pixel output and final image data, effectively removing noise while preserving the image information.
2Object-generated harmful factors
If correlated dual sampling units are added to convert signals and reduce noise, then noise is reduced, but device complexity increases
Solution Approach 1:
The patent merges the correlated dual sampling functionality directly into the existing pixel array structure. The sampling capacitors and subtraction circuits are integrated with the pixel cells and readout circuitry, combining multiple functions (signal storage, noise cancellation, and readout) into a unified circuit design. This reduces the overall device complexity compared to adding separate noise cancellation modules.
Solution Approach 2:
The correlated dual sampling circuit performs multiple functions: it stores the reset signal, stores the image signal, subtracts the reset signal from the image signal to remove noise, and outputs the cleaned signal. This multi-functional approach eliminates the need for separate noise cancellation hardware, thereby reducing device complexity while achieving effective noise reduction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly improves image quality by effectively removing noise from the image sensor, leading to enhanced resolution and fidelity of captured images.
Implementation Method 1
Each of the pixel cells is configured to convert light into an electric signal
Data Source
AI summary
An image sensor with noise-reduction circuitry includes a pixel array, many analog-to-digital converters, and many correlated dual sampling units. The pixel array includes rows and columns of pixel cells. Each of the pixel cells converts light into analog electrical signal. Analog-to-digital converters convert the electric signals output from the pixel cells into digital signals. The correlated dual sampling units convert the digital signals and/or the electric signals into correlated dual sampling signals to denoise the output of the image sensor by subtraction from the analog content. An electronic device is also provided.