Light Detecting Apparatus Background Noise Subtraction
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Solution Overview
Problem
Existing light detecting apparatuses face limitations in gain due to restrictions on capacitative element capacity, leading to insufficient amplification of signals, particularly when dealing with modulated light and background light components.
Innovation Solution
An image capturing device is designed with a first photoelectric converting unit for modulated light and a second unit to reduce background light, along with a signal processor that subtracts the background component from the first signal, enhancing the detection of modulated light by isolating it from background noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alternate current connection with capacitative element is used to remove background components, then background light component is reduced, but the capacity restriction on capacitative element results in insufficient amplifier gain
Solution Approach 1:
The invention divides the light detection function into two separate photoelectric converting units: one dedicated to detecting modulated light and another to detecting background light. This segmentation allows each unit to be optimized for its specific function, enabling the background light detection unit to use appropriate capacitative elements for effective background removal while the modulated light detection unit can achieve sufficient gain without being constrained by the same capacitative element capacity restrictions.
Solution Approach 2:
The invention extracts the background light detection function from the overall light detection system and implements it as a separate photoelectric converting unit. By taking out the background light component detection and processing it independently through subtraction, the system can apply different circuit configurations and capacitative element values to each function, resolving the contradiction between background removal effectiveness and amplifier gain requirements.
2Device complexity
If single photoelectric converting unit is used, then device structure is simple, but cannot effectively separate modulated light signal from background light
Solution Approach 1:
The invention segments the light detection function into two distinct photoelectric converting units with different operational characteristics. One unit detects the combined modulated light and background light, while the other detects only the background light component. This functional segmentation enables effective signal separation while maintaining relatively simple device architecture by using identical or similar photodetector structures for both units.
Solution Approach 2:
The invention applies different local qualities to different parts of the detection system by configuring the two photoelectric converting units with different circuit parameters, particularly different capacitative element values. The background light detection unit uses capacitative elements optimized for background light time constants, while the modulated light detection unit uses capacitative elements optimized for modulated signal frequencies, enabling effective separation of the two light components.
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 effectively reduces background light interference, allowing for improved detection and amplification of modulated light signals, thereby enhancing the accuracy and sensitivity of light detection and image capturing.
Implementation Method 1
a first photoelectric converting unit which outputs a first electrical signal in accordance with incident light including a modulated light component and a background light component
Implementation Method 2
a second photoelectric converting unit which outputs a second electrical signal resulting from the modulated light component being reduced in the incident light
Data Source
AI summary
Provided is a light detecting apparatus including: a first photoelectric converting element which outputs a first electrical signal in accordance with an incident light including a modulated light component and a background light component; a filter which outputs a second electrical signal resulting from the modulated light component being reduced in the incident light; and a signal processor which subtracts the second electrical signal from the first electrical signal to reduce a component corresponding to the background light component in the first electrical signal.