Pixel-Level Exposure Control Circuit for Image Sensors
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Solution Overview
Problem
Existing photoelectric conversion devices face challenges in reducing circuit scale while allowing for different exposure periods to be set on a pixel basis, leading to increased complexity and element area requirements.
Innovation Solution
A photoelectric conversion device is designed with a plurality of pixel circuits and exposure control circuits, where each exposure control circuit includes a capacitor to hold a signal corresponding to an exposure period and a comparator to compare this signal with a threshold potential, controlling the exposure period by outputting a signal to a transistor, thereby reducing circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of circuit elements are used to control exposure period on a pixel basis, then different exposure periods can be set on a pixel basis, but the circuit scale increases
Solution Approach 1:
The exposure control circuit is designed as a universal circuit that can control exposure periods for multiple pixels. By using the same circuit structure for each pixel with shared control signals, the patent achieves pixel-level exposure control without requiring completely independent control circuits for each pixel, thus reducing overall circuit scale while maintaining the capability to set different exposure periods on a pixel basis.
Solution Approach 2:
The pixel array is divided into multiple pixel groups, and the exposure control is segmented into group-level control rather than individual pixel control. This segmentation allows for different exposure periods to be set for different pixel groups, providing sufficient versatility for many applications while significantly reducing the circuit scale compared to individual pixel control.
2Adaptability or versatility
If pixel-level exposure control is implemented, then different exposure periods can be set on a pixel basis, but the circuit configuration becomes complex
Solution Approach 1:
Multiple exposure control functions are merged into a single integrated exposure control circuit. The circuit combines charge accumulation control, exposure timing, and signal generation functions into one unified structure, simplifying the overall circuit configuration while maintaining pixel-level or pixel-group-level exposure control flexibility.
Solution Approach 2:
An intermediary control signal is introduced that mediates between the simple control input and the complex pixel-level exposure control requirements. This intermediary signal distributes control information efficiently to multiple pixels or pixel groups, reducing the complexity of the overall circuit configuration while maintaining flexible exposure control.
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 configuration allows for different exposure periods to be set on a pixel basis, reducing the circuit scale and enabling efficient exposure control, while maintaining a simple circuit configuration.
Implementation Method 1
a photoelectric conversion unit configured to generate charges by photoelectric conversion
Data Source
AI summary
Provided is a photoelectric conversion device including: a plurality of pixel circuits each including a photoelectric conversion unit configured to generate charges by photoelectric conversion and a transistor configured to transfer the charges from the photoelectric conversion unit; and a plurality of exposure control circuits each including a capacitor configured to hold a signal corresponding to an exposure period in the photoelectric conversion unit and a comparator circuit configured to compare a potential of a first terminal of two terminals of the capacitor with a threshold potential. Each of the plurality of exposure control circuits controls an exposure period of the photoelectric conversion unit by outputting a signal based on a comparison result caused by the comparator circuit to a control terminal of the transistor and driving the transistor.