Imaging Device Multiple Readout Noise Suppression
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Solution Overview
Problem
In general imaging devices, achieving sufficient light capture under low-illuminance conditions requires signal amplification, which leads to digital gain multiplication, resulting in bit accuracy deterioration and increased quantization noise.
Innovation Solution
An imaging device that reads out image signals multiple times within one exposure period, calculates a target gain value based on the signal level of the last read-out image signal, and multiplies the added signal by this value to generate image data, thereby minimizing digital gain and suppressing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If digital gain multiplication is performed to amplify signals under low-illuminance conditions, then signal strength is improved, but bit accuracy deteriorates and quantization noise increases
Solution Approach 1:
The patent divides the exposure period into multiple segments and performs multiple reads during integration. By segmenting the exposure time and reading signals at different intervals, the system can accumulate signal strength through multiple readings while maintaining bit accuracy by processing signals in manageable segments rather than requiring excessive digital gain on a single reading.
Solution Approach 2:
The patent implements periodic reading of image signals during the exposure period. By periodically reading signals at multiple intervals throughout the exposure time, the system accumulates sufficient signal strength through repeated measurements while distributing the gain multiplication across multiple smaller operations, thereby reducing the impact on bit accuracy and quantization noise.
2Measurement precision
If multiple reads during integration are performed to extend dynamic range, then signal accuracy is improved, but readout time increases
Solution Approach 1:
The patent performs multiple reads during the exposure period itself, making the readout operation continuous and overlapping with the exposure process. By continuously reading signals at multiple intervals throughout the exposure time rather than performing reads sequentially after exposure, the system maintains signal accuracy through multiple measurements while minimizing additional readout time.
Data Source
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AI summary
An imaging device (1) includes: an imaging element (10) that outputs an image signal in a nondestructive manner; an image processor (160) that performs predetermined processing on the outputted image signal to generate image data; and a controller (20) that controls the image processor (160). Under control of the controller (20), the image processor (160) reads out image signals from the imaging element (10) a plurality of times within one exposure period (L), calculates a target gain value based on a target level and an added signal, and multiples the added signal by the target gain value to generate the image data. The target level is calculated based on a signal level of a last read-out image signal in one exposure period (L). The added signal being obtained by adding up the image signals read out the plurality of times.