Avalanche Photodiode Counting Circuit for High-Luminance Photon Detection
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Solution Overview
Problem
Existing photon-counting photoelectric conversion apparatuses fail to accurately count the number of periods in which avalanche multiplication occurs due to incidents of high-luminance light during the recharging phase, leading to undercounting and reduced image luminance.
Innovation Solution
A photoelectric conversion apparatus comprising a photodiode capable of avalanche multiplication, a generation circuit for generating control signals, a first control circuit for managing the photodiode's states, and a second control circuit for accurately counting periods of avalanche multiplication by utilizing control signals and photodiode output signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the photodiode continuously performs avalanche multiplication to detect photons, then the photon detection capability is improved, but the counting accuracy deteriorates due to inability to distinguish between avalanche events during standby state and recharging state
Solution Approach 1:
The patent applies dynamics by making the counting function dynamic - the second control circuit is enabled to count avalanche events only during the standby state period and is disabled during the recharging state. This dynamic control of the counting function based on the operational state of the photodiode resolves the contradiction by ensuring accurate counting only when the system is in the appropriate state, preventing miscounting under high-luminance conditions.
Solution Approach 2:
The patent uses feedback by having the first control circuit generate control signals based on the charging state of the photodiode, and the second control circuit uses these control signals to determine when to count avalanche events. The control signal serves as feedback information that coordinates the counting operation with the photodiode's operational state, ensuring that counting occurs only during standby state and not during recharging, thereby maintaining counting accuracy and reliability.
2Device complexity
If the apparatus counts all avalanche multiplication events without state discrimination, then the counting process is simple, but the counting accuracy deteriorates due to inclusion of events during recharging phase
Solution Approach 1:
The patent applies dynamics by making the counting function dynamic - the second control circuit is enabled to count avalanche events only during the standby state period and is disabled during the recharging state. This dynamic control of the counting function based on the operational state of the photodiode resolves the contradiction by ensuring accurate counting only when the system is in the appropriate state, preventing miscounting under high-luminance conditions.
Solution Approach 2:
The patent uses an intermediary approach by introducing a control signal that acts as a gate between the avalanche detection and the counting function. The first control circuit generates this intermediary control signal based on the photodiode's charging state, and the second control circuit uses it to enable or disable counting. This intermediary mechanism adds minimal complexity while significantly improving counting accuracy by filtering out events that occur during recharging.
3Stability of the object's composition
If the photodiode is recharged frequently to maintain standby state, then the readiness for photon detection is improved, but the loss of counting periods increases due to recharging interruptions
Solution Approach 1:
The patent applies preliminary action by maintaining the photodiode in a ready-to-count state through proper management of standby and recharging periods. The first control circuit ensures the photodiode is recharged to standby state before photon detection is needed, and the second control circuit is prepared to count events immediately when the standby state is achieved. This preliminary preparation minimizes counting period loss by ensuring the system is always ready to count when photons are incident.
Solution Approach 2:
The patent uses feedback by having the first control circuit generate control signals based on the charging state of the photodiode, and the second control circuit uses these control signals to determine when to count avalanche events. The control signal serves as feedback information that coordinates the counting operation with the photodiode's operational state, ensuring that counting occurs only during standby state and not during recharging, thereby maintaining counting accuracy and reliability.
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 apparatus effectively detects and counts periods of avalanche multiplication, even during high-luminance conditions, thereby ensuring accurate photon counting and maintaining original image luminance.
Implementation Method 1
a photodiode configured to perform avalanche multiplication
Data Source
AI summary
A photoelectric conversion apparatus includes a photodiode, a generation circuit, a first control circuit, and a second control circuit. The photodiode is configured to perform avalanche multiplication. The generation circuit is configured to generate a control signal. The first control circuit is configured to be controlled by the control signal to be in a standby state where the avalanche multiplication by the photodiode is possible and in a recharging state for returning the photodiode having performed the avalanche multiplication to the standby state. The second control circuit is configured to count a number of periods in which the avalanche multiplication has occurred among a plurality of periods of the standby state by using the control signal and a signal corresponding to an output of the photodiode.