Photodetection Device Ambient Light Subtraction Circuit
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Solution Overview
Problem
Current photodetection systems face challenges in enhancing detection accuracy, particularly in distinguishing reflected light from ambient light, which affects the precision of distance measurement in Time OF Flight (TOF) methods.
Innovation Solution
The proposed solution involves a photodetection device and system that utilize multiple light-receiving sections, counters, and processors to generate pulse signals, perform count processing, and apply subtraction and threshold adjustments to isolate the reflected light signal, thereby improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light-receiving sections are used to detect reflected light, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The photodetection device is divided into multiple independent light-receiving sections, each capable of detecting light and generating pulse signals. This segmentation allows parallel processing of light detection tasks, improving overall detection accuracy while maintaining manageable complexity through modular design
Solution Approach 2:
Multiple light-receiving sections are combined with shared counters and processing circuits. The counters and subtraction processors are共用 among multiple light-receiving sections, reducing the overall circuit complexity compared to having dedicated processing circuits for each section
2Measurement precision
If count processing is performed on all pulse signals, then detection precision is improved, but processing time increases
Solution Approach 1:
The subtraction processor performs preliminary subtraction of ambient light components from the count values before final distance calculation. This preliminary processing eliminates the need for repeated subtraction operations, reducing overall processing time while maintaining detection precision
Solution Approach 2:
The system skips unnecessary count processing for light-receiving sections that are not currently detecting reflected light or for time periods when no light reception occurs. This selective processing reduces total processing time while ensuring accurate detection when needed
3Measurement precision
If ambient light components are subtracted from count values, then detection accuracy is improved, but circuit complexity increases
Solution Approach 1:
The subtraction processor extracts and removes ambient light components from the total count values by performing subtraction operations. This extraction isolates the reflected light signal from the ambient light background, improving detection accuracy through a dedicated but simple subtraction circuit
Solution Approach 2:
The subtraction processor is designed to handle multiple count values from different light-receiving sections using the same processing logic and circuitry. This multi-functional design reduces overall circuit complexity compared to having separate subtraction circuits for each light-receiving section
4Reliability
If threshold values are dynamically adjusted, then detection reliability is improved, but processing complexity increases
Solution Approach 1:
The threshold setting section dynamically adjusts threshold values based on feedback from the count values and detection results. This feedback mechanism allows the system to adapt to varying ambient light conditions and maintain high detection reliability through automated threshold optimization
Solution Approach 2:
The threshold values are made dynamic rather than fixed, allowing them to change based on detection conditions. This dynamic adjustment improves reliability in varying environments while the automated nature of the adjustment reduces the need for complex manual processing
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
This approach enhances the accuracy of distance measurements by effectively subtracting ambient light components, securing the signal amount of reflected light and reducing circuit complexity, leading to improved detection precision and efficiency.
Implementation Method 1
one or a plurality of light-receiving sections 31, each including a light-receiving element PD, and configured to generate a pulse signal PLS including a pulse corresponding to a result of light reception by the light-receiving element
Data Source
AI summary
A photodetection device according to the present disclosure includes: one or a plurality of light-receiving sections that each includes a light-receiving element, and generates a pulse signal including a pulse corresponding to a result of light reception by the light-receiving element; a plurality of first counters that each performs count processing on the basis of one or a plurality of the pulse signals generated by the one or plurality of light-receiving sections, thereby generating a plurality of count values; and a subtraction processor that performs subtraction processing for subtracting a predetermined value from each of the plurality of count values, on the basis of one or more count values of the plurality of count values.