Avalanche Photodiode Recharging Control for High-Illuminance Counting
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Solution Overview
Problem
Existing light detecting apparatuses using avalanche photodiodes face issues with power consumption and dynamic range under high-illuminance conditions, as passive quench circuits can reverse the illuminance-counted value relationship, leading to signal generation failure and narrow dynamic range.
Innovation Solution
A photodiode control circuit with a recharging circuit and control signal generating circuit that switches between connection states based on clock and mask signals, using different inactive periods to manage power consumption and maintain accurate counting under varying illuminance levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a passive quench circuit is used to reduce power consumption, then power consumption is reduced, but the relationship between illuminance and counted value may be reversed and dynamic range becomes narrow
Solution Approach 1:
The patent applies dynamics by making the recharging circuit's operation period adjustable based on detected light intensity. The circuit transitions from a static passive quench approach to a dynamic system where the inactive period is modified according to illuminance levels, allowing the system to adapt its power consumption and counting behavior to match environmental conditions, thereby resolving the contradiction between power saving and dynamic range
Solution Approach 2:
The patent implements feedback by using the counted value from the counter to control the recharging circuit's operation. The control signal generating circuit receives the counted value and adjusts the inactive period accordingly - when counted value exceeds a threshold, the inactive period is increased to reduce power consumption while maintaining accurate counting capability, creating a closed-loop system that resolves the contradiction
2Use of energy by moving object
If the inactive period is increased to reduce power consumption, then power consumption is reduced, but signal generation may fail under high illuminance
Solution Approach 1:
The system dynamically adjusts the inactive period based on real-time counting feedback. When illuminance is low and counted value remains below threshold, the inactive period stays short ensuring reliable signal generation. When illuminance is high and counted value exceeds threshold, the inactive period is extended to reduce power consumption. This dynamic adaptation resolves the contradiction between power saving and signal generation reliability
Solution Approach 2:
The patent changes the temporal parameter (inactive period duration) of the recharging circuit based on operating conditions. By adjusting this parameter from a fixed value to a variable value controlled by the counted value, the system can optimize both power consumption and signal generation reliability for different illuminance levels
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 increases the dynamic range and reduces power consumption by appropriately setting inactive periods, ensuring accurate photon counting even under high illuminance, thereby enhancing the apparatus's performance.
Implementation Method 1
a light detecting apparatus is known, which uses an avalanche photodiode (APD) that can detect single-photon-level weak light using avalanche (electron avalanche) multiplication
Data Source
AI summary
An apparatus includes a photodiode that performs avalanche multiplication, a recharging circuit, a control signal generating circuit that generates a control signal to control the recharging circuit, a count pulse generating circuit that generates a pulse signal from a signal output from the photodiode, and a counter that counts the pulse signal output from the count pulse generating circuit. The control signal generating circuit is configured to output, based on a clock signal and a mask signal, the control signal having a first period and the control signal having a second period longer than the first period. In a case where a counted value of the counter reaches a threshold, the signal to be output from the control signal generating circuit can be switched from the control signal having the first period to the control signal having the second period.