Avalanche Photodiode Pulse Counting With Dynamic Threshold Control
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Solution Overview
Problem
Existing photon counting type photoelectric conversion devices face issues with high power consumption during high luminance conditions and inaccuracies in image signal representation when the subject changes, leading to increased errors in pulse counting.
Innovation Solution
A photoelectric conversion device incorporating an avalanche photodiode, pulse generation, pulse counting, time counting, and threshold calculation units to dynamically adjust the counting process based on the pulse count value, reducing power consumption and error by terminating counting when the value exceeds a threshold and using time count values for accurate estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse counting is continuously performed to ensure accurate image signal representation, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent applies dynamics by making the counting operation adjustable rather than fixed. The control unit dynamically switches between continuous pulse counting and stopped counting modes based on luminance conditions. When luminance is low, counting continues to maintain precision; when luminance is high, counting stops to reduce power consumption while still providing usable image data through alternative processing paths.
Solution Approach 2:
The patent changes the operational parameters of the photoelectric conversion device based on luminance conditions. By monitoring luminance levels and adjusting the counting operation state (continuous vs. stopped), the system adapts its measurement behavior to match environmental conditions, thereby optimizing the balance between precision and power consumption across different operating scenarios.
2Use of energy by moving object
If a fixed threshold value is used to stop counting to reduce power consumption, then power consumption is reduced, but measurement precision deteriorates when the subject changes
Solution Approach 1:
The patent implements feedback by continuously monitoring luminance conditions and using this information to control the counting operation. The control unit receives feedback about current luminance levels and adjusts the counting state accordingly. This closed-loop control ensures that counting is stopped only when appropriate (high luminance with stable conditions), preventing precision loss when subjects change while still achieving power savings during stable high-luminance periods.
Solution Approach 2:
Rather than using a fixed threshold, the system dynamically adjusts its behavior based on real-time luminance monitoring. The decision to stop or continue counting is made adaptively based on current conditions, allowing the system to respond appropriately to subject changes while maintaining power efficiency during stable conditions.
3Use of energy by moving object
If pulse counting is stopped early to reduce power consumption, then power consumption is reduced, but loss of information increases
Solution Approach 1:
The control unit uses feedback from luminance monitoring to determine when stopping counting is safe. By continuously assessing luminance conditions, the system ensures that counting is only stopped when high luminance has been confirmed, preventing premature termination that would cause information loss. The feedback mechanism validates that stopping will not compromise the integrity of the image data.
Solution Approach 2:
The system performs preliminary luminance monitoring and confirmation before stopping the counting operation. This preliminary action ensures that the conditions for stopping are truly met, preventing premature termination. By checking luminance conditions in advance and confirming they are appropriate, the system avoids stopping too early and losing valuable photon count information.
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
The solution effectively reduces power consumption and minimizes errors in image signal representation by dynamically managing the counting process, ensuring accurate image signals even under varying luminance conditions.
Implementation Method 1
When a reverse bias voltage higher than a breakdown voltage is applied to the avalanche photodiode, a carrier generated by incident of a single photon causes avalanche multiplication, and a large current is generated.
Implementation Method 2
a carrier generated by incident of a single photon causes avalanche multiplication
Data Source
AI summary
A photoelectric conversion device according to an embodiment of the present disclosure includes an avalanche photodiode, a pulse generation unit that converts an output from the avalanche photodiode into a pulse signal, a pulse count unit that counts the pulse signal and outputs a pulse count value, a time count unit that outputs a time count value indicating a time from the start of operation of the pulse generation unit, an output unit that, when the pulse count value does not exceed a threshold value, outputs the pulse count value, and when the pulse count value exceeds the threshold value, ends counting in the pulse count unit and outputs the time count value at the time of the pulse count value exceeding the threshold value, and a threshold calculation unit that calculates the threshold value using the time count value.