Image Sensor Pixel Circuit for Exposure Control Without Fill Factor Loss
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Solution Overview
Problem
Conventional image sensors require separate power sources for each pixel to control exposure time, leading to a reduction in aperture ratio and increased complexity, which complicates the manufacturing process and reduces yield.
Innovation Solution
An image sensor design where a single common power supply unit provides a negative voltage to multiple pixels, eliminating the need for individual power supplies and simplifying the circuit configuration, allowing for controlled exposure time without reducing the fill factor of the photodiode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If separate power sources are provided for each pixel to control exposure time, then exposure time control is achieved, but the aperture ratio is reduced
Solution Approach 1:
Multiple pixels share a common power supply unit that provides negative voltage to transfer transistors. This merging of power supply resources eliminates the need for separate power sources in each pixel, thereby maintaining high aperture ratios while still enabling individual exposure time control through shared control signals.
Solution Approach 2:
The common power supply unit serves multiple pixels simultaneously, providing universal power distribution. This multi-functional approach allows a single power supply structure to control exposure times across numerous pixels, achieving both aperture ratio preservation and exposure control capability.
2Extent of automation
If separate power sources are provided for each pixel, then exposure time control is achieved, but device complexity increases
Solution Approach 1:
The power supply circuitry is merged into a shared resource that serves multiple pixels. By combining what would otherwise be duplicate power supply units into a single common unit, the overall device complexity is reduced while maintaining the ability to control exposure times individually through control signals.
Solution Approach 2:
The common power supply unit is designed to serve multiple pixels universally, reducing the need for pixel-specific power management circuits. This universal approach simplifies the overall device architecture by eliminating redundant power supply components across different pixel regions.
3Extent of automation
If separate power sources are provided for each pixel, then exposure time control is achieved, but manufacturing yield is reduced
Solution Approach 1:
By merging power supply units into a common shared resource, the number of manufacturing steps and quality control checkpoints is reduced. Fewer individual power supply components mean fewer potential failure points during manufacturing, thereby improving overall production yield while maintaining exposure control functionality.
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 design enables efficient control of exposure time for each pixel while maintaining a high fill factor, improving light utilization efficiency and reducing manufacturing complexity, thus enhancing image sensor performance and miniaturization potential.
Implementation Method 1
a photodiode 31 that photoelectrically converts incident light into electrical charge
Data Source
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AI summary
An image sensor includes a first voltage source that supplies a first voltage and a plurality of pixels supplied with the first voltage. The pixel includes a photoelectric conversion unit that photoelectrically converts incident light, an accumulation unit to which an electric charge resulting from photoelectric conversion by the photoelectric conversion unit is transferred and accumulated, a transfer unit that transfers the electric charge from the photoelectric conversion unit to the accumulation unit; a second voltage source that supplies a second voltage, and a supply unit that supplies the transfer unit with a transfer signal based on either the first voltage supplied by the first voltage source or the second voltage supplied by the second voltage source.