Imaging Device Pixel Readout Circuit Frame Rate
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Solution Overview
Problem
Existing imaging devices face challenges in reading out multiple images based on signals with different accumulation times within a single frame period, leading to a decrease in frame rate.
Innovation Solution
An imaging device with a plurality of pixels, each including a first and second photoelectric conversion unit, and signal holding units, where the readout circuit reads out the first image signal during the second accumulation period, ensuring synchronization and efficient frame rate maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple images with different accumulation times are read out within one frame period, then simultaneous shooting of moving images and still images is enabled, but the frame rate decreases due to extended readout time
Solution Approach 1:
The pixel array is divided into multiple independent pixel groups, each capable of independent signal charge transfer and readout. This segmentation allows parallel processing of multiple images with different accumulation times, enabling simultaneous shooting while maintaining frame rate by avoiding sequential readout delays.
Solution Approach 2:
Signal charges are transferred to signal holding units in advance during the accumulation period, before readout is required. This preliminary transfer action allows the readout circuit to immediately read out signals from holding units when needed, eliminating readout wait time and maintaining high frame rate during simultaneous shooting operations.
2Adaptability or versatility
If signal charges are accumulated for different durations in multiple pixel elements, then diverse image data (HD moving image and still image) can be obtained, but the readout time increases
Solution Approach 1:
Signal holding units serve as intermediary storage between the photoelectric conversion units and the readout circuit. These holding units temporarily store signal charges from pixel elements with different accumulation times, allowing the readout circuit to retrieve signals at optimized times without causing time loss, thus enabling diverse image data acquisition while maintaining efficient readout.
3Measurement precision
If a pair of photodiodes with asymmetric pupil shapes is used, then HDR imaging is achieved, but the device complexity increases
Solution Approach 1:
The imaging device achieves multi-functionality by enabling a single pixel structure to perform multiple functions: standard imaging, HDR imaging, slow-motion imaging, and still image capture. The pixel elements and signal holding units can be configured for different accumulation times and readout patterns, providing diverse imaging capabilities without requiring separate specialized structures for each function.
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
Enables easy readout of multiple images without sacrificing frame rate, allowing for simultaneous capture of high-definition moving images and still images with different accumulation times.
Implementation Method 1
a first pixel element including a first photoelectric conversion unit, and a second pixel element including a second photoelectric conversion unit lower in sensitivity than the first photoelectric conversion unit
Data Source
AI summary
An imaging device includes a plurality of pixels, each of which including a first pixel element including a first photoelectric conversion unit, and a second pixel element including a second photoelectric conversion unit lower in sensitivity than the first photoelectric conversion unit, a readout circuit configured to read out a first image signal based on signal charge generated in the first pixel element during a first accumulation period, and a second image signal based on signal charge generated in the second pixel element during a second accumulation period longer than the first accumulation period, the second image signal being synchronized with the first image signal, and a control unit configured to control the readout circuit so that a first readout period for reading out the first image signal is performed during the second accumulation period.