Avalanche Photodiode Bias Control for Stable Distance Sensing
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Solution Overview
Problem
In distance measurement systems using avalanche photodiodes, the bias voltage adjustment based solely on leakage current measurement can lead to decreased performance and increased power consumption, especially in environments with background light or short distances.
Innovation Solution
A distance measurement system that includes a light emitting device and a photodetection device with a pixel array of avalanche photodiodes, a current measurement circuit, and a bias voltage control unit, which adjusts the bias voltage and light emission based on the total pixel current to optimize performance and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If bias voltage is adjusted based solely on leakage current measurement, then device complexity is reduced, but distance measurement performance deteriorates and power consumption increases
Solution Approach 1:
The patent implements a feedback control mechanism where the total pixel current is continuously measured and used to dynamically adjust the bias voltage. The control unit receives the total pixel current value and adjusts the bias voltage to maintain optimal operating conditions, ensuring stable distance measurement performance while adapting to varying light conditions including background light and short distance scenarios.
Solution Approach 2:
The system performs self-adjustment by automatically measuring its own total pixel current and using this information to regulate the bias voltage without external intervention. This self-service mechanism enables the photodetection device to autonomously optimize its performance across different operating conditions.
2Ease of operation
If bias voltage is adjusted based solely on leakage current measurement, then adjustment simplicity is improved, but power consumption increases
Solution Approach 1:
The feedback control system continuously monitors total pixel current and dynamically adjusts bias voltage to optimize power consumption. By maintaining the total pixel current within a target range, the system prevents excessive power consumption that would occur with fixed or improperly adjusted bias voltages, especially in environments with background light or short measurement distances.
Solution Approach 2:
The patent dynamically changes the bias voltage parameter based on real-time total pixel current measurements. This parameter adjustment enables the system to adapt to varying operational conditions, reducing power consumption by lowering bias voltage when total pixel current is high and increasing it when needed for optimal detection performance.
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 system maintains distance measurement performance while reducing power consumption by dynamically adjusting bias voltage and light emission according to the total pixel current, effectively addressing issues with background light and short distances.
Implementation Method 1
a plurality of pixels respectively including a plurality of avalanche photodiodes that detects the reflected light
Data Source
AI summary
Distance measurement systems and devices that optimize avalanche photodiode bias voltage are disclosed. In one example, a distance measurement system a light emitting device that emits distance measurement light, and a photodetection device that receives reflected light of the distance measurement light. The photodetection device includes a pixel array with a plurality of pixels that respectively include avalanche photodiodes that detect the reflected light; a current measurement circuit that measures a total pixel current of the pixel array; and bias voltage control that controls avalanche photodiode bias voltage using a detection result of the current measurement circuit. The light emitting device also includes light emission control circuitry that controls a light quantity of the distance measurement light using the detection result of the current measurement circuit.