Solid-State Imaging Element Dynamic Range Expansion
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Solution Overview
Problem
Conventional solid-state imaging elements with differential amplifier circuits face challenges in widening the dynamic range without reducing frame rate, especially when ambient light fluctuations occur, such as in the presence of shadows or varying exposure times.
Innovation Solution
A solid-state imaging element that includes a reading circuit for differentially amplifying signals between pairs of pixels and a processing unit for synthesizing these signals, allowing for expanded dynamic range by combining differentially amplified and pixel signals, with options for reset and signal levels, and incorporating analog-digital conversion and switch-based control for optimal signal selection and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple frames with different exposure times are captured and synthesized to widen dynamic range, then the dynamic range is expanded, but the frame rate decreases
Solution Approach 1:
The pixel array is divided into first pixels and second pixels that are read out at different timings. The first pixels are read during the first period and the second pixels are read during the second period, allowing simultaneous capture of multiple exposure frames without reducing overall frame rate.
Solution Approach 2:
The patent introduces a temporal dimension by reading different pixel groups at different timings within the same frame period. This allows multiple exposure frames to be captured and synthesized while maintaining the original frame rate, as the reading occurs in the time dimension rather than requiring sequential frame capture.
2Measurement precision
If a differential amplifier circuit is used to increase pixel sensitivity, then the sensitivity is improved, but the dynamic range becomes insufficient when ambient light fluctuates greatly
Solution Approach 1:
The pixel array is segmented into first pixels and second pixels with different reading timings. First pixels are read during the first period and second pixels during the second period, enabling capture of both high-sensitivity differential signals and wide-dynamic-range signals through selective reading.
Solution Approach 2:
The patent implements dynamic reading control where the reading circuit selectively reads different pixel groups at different timings based on exposure requirements. This dynamic approach allows the system to adapt between high sensitivity mode and wide dynamic range mode within the same frame period.
Data Source
AI summary
To widen a dynamic range without reducing a frame rate in a solid-state imaging element provided with a differential amplifier circuit.The solid-state imaging element includes a reading circuit and a processing unit. The reading circuit performs processing of outputting a differentially amplified signal obtained by amplifying a difference between generated voltages of a pair of pixels and processing of outputting a pixel signal of the generated voltage of at least one of the pair of pixels each time the pair of pixels are exposed. The processing unit performs synthesis processing of synthesizing the output differentially amplified signal and the output pixel signal.