Avalanche Photodiode Timing-Energy Detection for Disturbance Light Rejection
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Solution Overview
Problem
Scanning type measurement devices face mechanical failures and inaccurate target detection due to target movement during scanning, while flash type measurement devices struggle with reduced light intensity and distinguishing reflected light from disturbance light, requiring improved sensitivity and accuracy.
Innovation Solution
A light detection device with a semiconductor substrate and circuit substrate, featuring avalanche photodiodes operating in Geiger mode, quenching resistors, and signal processing units that measure timing and energy of incident light, allowing for improved sensitivity and distinction between reflected and disturbance light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a scanning type measurement device is used, then detection operation can be performed sequentially, but mechanical failures occur in the scanning unit and accurate detection is not achieved due to target movement
Solution Approach 1:
The patent replaces the mechanical scanning unit with a flash type light source that simultaneously illuminates the entire detection region. This eliminates mechanical moving parts that cause failures and target movement issues, achieving both high reliability and accurate detection by capturing all reflected light at once without sequential scanning.
Solution Approach 2:
The patent uses periodic pulsing of the flash light source to illuminate the detection region in controlled intervals. This periodic illumination allows simultaneous capture of reflected light from the entire region, eliminating the need for continuous mechanical scanning while maintaining detection accuracy even when targets move during the illumination period.
2Productivity
If a flash type measurement device is used, then detection operation in wide region can be performed simultaneously, but intensity of reflected light from each site becomes weaker
Solution Approach 1:
The patent merges multiple pixels into pixel groups, where each pixel group corresponds to a specific angular range. By combining the signals from multiple pixels within each angular range, the system maintains high detection speed while improving the effective light intensity through signal integration, thereby resolving the contradiction between simultaneous wide-region detection and reflected light intensity.
3Loss of time
If light is simultaneously projected to two-dimensional region, then detection operation time is shortened, but disturbance light is detected in addition to reflected light from target
Solution Approach 1:
The patent segments the detection system into multiple pixels arranged in a matrix, with each pixel corresponding to a specific angular range. This segmentation allows simultaneous detection across the entire field of view while maintaining the ability to distinguish reflected light from disturbance light through angular resolution and signal processing, thus resolving the contradiction between short detection time and disturbance light rejection.
Solution Approach 2:
The patent employs signal processing that analyzes the timing and intensity of signals from multiple pixels to distinguish reflected light from disturbance light. By using feedback from the spatial and temporal characteristics of detected signals, the system can identify and filter out disturbance light while maintaining simultaneous wide-region detection capability.
4Measurement precision
If multiple pixels are two-dimensionally arranged to detect reflected light simultaneously, then sensitivity in each pixel must be improved, but device complexity increases
Solution Approach 1:
The patent uses avalanche photodiodes operating in Geiger mode that provide high detection sensitivity through their inherent physical characteristics. This universal approach allows all pixels to achieve high sensitivity without requiring complex individual processing circuits for each pixel, thereby maintaining detection sensitivity while controlling overall device complexity through standardized component design.
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 device achieves enhanced accuracy and precision in light detection, reduces mechanical failures, and minimizes the influence of disturbance light, while maintaining a compact configuration.
Implementation Method 1
Each of the plurality of pixels U includes a plurality of avalanche photodiodes 11 arranged to operate in Geiger mode
Implementation Method 2
Each of the plurality of quenching resistors 21 is electrically connected to a corresponding one of the avalanche photodiodes 11 in series
Data Source
AI summary
In a light detection device, a circuit substrate includes a plurality of signal processing units which process a detection signal output from a corresponding pixel. Light-receiving regions of a plurality of avalanche photodiodes are two-dimensionally arranged for every pixel. In each of the signal processing units, a timing measurement unit measures timing at which light is incident on a corresponding pixel, based on the detection signal. An energy measurement unit measures energy of light incident on a corresponding pixel, based on the detection signal. A storage unit stores a measurement result in the timing measurement unit and the energy measurement unit. A light detection region where a plurality of the pixels are provided and a signal processing region where a plurality of the signal processing units are provided overlap each other at least at a part.