APD Pixel Array Clock Selection for Synchronized Exposure
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Solution Overview
Problem
Existing photoelectric conversion devices with avalanche photodiodes (APDs) face challenges in efficiently controlling the exposure period and avalanche multiplication, leading to inconsistent image quality due to varying exposure times across pixels.
Innovation Solution
A device comprising a pixel unit with quenching circuits and a selection unit that receives multiple clock signals, allowing for the generation of different clock signals to control the exposure period of each pixel, enabling synchronized and adjustable exposure times across a pixel array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single clock signal is used to control all pixels, then the control circuit is simple, but the exposure period cannot be adjusted individually for each pixel leading to inconsistent image quality
Solution Approach 1:
The patent divides the control system into multiple independent clock signal generation units, with each pixel or pixel group having its own clock signal generation unit that can independently control the exposure period. This segmentation allows individual adjustment of exposure parameters for each pixel while maintaining overall system functionality.
Solution Approach 2:
The patent implements dynamic control of exposure periods by allowing each pixel's clock signal generation unit to adjust the exposure time based on real-time requirements. The clock signals can be dynamically modified without affecting other pixels, enabling flexible adaptation to varying imaging conditions while maintaining consistent image quality.
2Manufacturing precision
If different exposure periods are implemented for each pixel, then image quality consistency is improved, but the control circuit becomes more complex
Solution Approach 1:
The patent designs clock signal generation units that can serve multiple functions: they generate clock signals for exposure control, can be configured for different exposure periods, and operate independently for each pixel. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby managing complexity while achieving precise exposure control.
Solution Approach 2:
The patent achieves precise exposure period control by dynamically changing the operating parameters (frequency, period) of the clock signals generated by each clock signal generation unit. Instead of using complex hardware for each pixel, the system adjusts parameters software-controlled or through simple feedback mechanisms, achieving precision without proportional increases in hardware complexity.
3Manufacturing precision
If exposure periods are not synchronized across pixels, then each pixel can have optimal exposure time, but luminance variations increase
Solution Approach 1:
The patent incorporates feedback mechanisms where the output signal from each pixel's clock signal generation unit is fed back to control the exposure period. This feedback ensures that exposure periods are synchronized across pixels to maintain luminance uniformity while still allowing individual optimization. The feedback loop continuously adjusts exposure timing to prevent luminance variations.
Solution Approach 2:
The patent uses periodic clock signals that are synchronized across all pixels to control the exposure period. Each pixel's clock signal generation unit operates with a periodic signal that can be independently adjusted but remains synchronized with other pixels. This periodic action ensures that exposure periods are coordinated to maintain uniform luminance output while preserving the flexibility to adjust individual exposure parameters when needed.
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 ensures consistent image quality by allowing for precise control of exposure periods, reducing luminance variations and enhancing the overall performance of the photoelectric conversion device.
Implementation Method 1
In an APD, electric charge caused by incident light effects avalanche multiplication at the P-N junction region of the APD
Implementation Method 2
electric charge caused by incident light effects avalanche multiplication at the P-N junction region of the APD
Data Source
AI summary
A device includes a pixel unit, a selection unit, and a first generation unit. The pixel unit has a plurality of pixels arranged in a plurality of rows. Each pixel includes a quenching circuit configured to receive a signal for determining start and end of an exposure period and a photodiode coupled to the quenching circuit. The selection unit is configured to simultaneously receive a plurality of clock signals of different periods and select a clock signal to be outputted from the plurality of clock signals. The first generation unit is configured to generate the signal by using the outputted clock.