Optical Sensor Circuit Reduces Error Probability Under White Ambient Light
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Solution Overview
Problem
Conventional optical sensor circuits face issues with ambient light resistance, leading to increased error probabilities and false alarms due to the decomposition of white ambient light into multiple color spectrum bands, which affects the Signal-to-Noise Ratio and correct detection of specific light sources.
Innovation Solution
The optical sensor circuit employs a configuration of transistors and capacitors with specific optical filters and a closed-loop circuit or leakage path to maintain the capacitor voltage level, distinguishing between red light and white ambient light by managing light currents and voltages through carefully timed driving signals, thereby minimizing error probabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical sensor circuits use light filters to detect specific light sources, then the detection capability for specific light colors is improved, but the error probability increases under strong white ambient light conditions
Solution Approach 1:
The patent segments the detection function by using multiple transistors (first transistor for red light detection, second transistor for green light detection, third transistor for blue light detection) each covered with corresponding light filters. This segmentation allows the circuit to distinguish between specific light sources and white ambient light by comparing signals from different color channels, thereby reducing false detections under ambient light conditions.
Solution Approach 2:
The patent introduces a capacitor as an intermediary element to store and compare light current signals. The capacitor holds the light current from a specific color channel and compares it with ambient light current, enabling the circuit to identify whether a detected light signal is from a specific source or merely from ambient light, thus reducing false alarms.
2Illumination intensity
If the intensity of white ambient light increases, then the red color component intensity increases proportionally, but the Signal-to-Noise Ratio of the detection mechanism decreases
Solution Approach 1:
The patent employs a feedback mechanism where the circuit continuously monitors and compares light current signals from different color channels. By comparing the red channel signal with green and blue channel signals, the circuit can determine whether a detected signal is from a specific red light source or from the red component of white ambient light, thereby maintaining detection accuracy even when ambient light intensity varies.
Solution Approach 2:
The patent changes the operational parameters of the transistors by applying different bias voltages and using different light filters for each transistor. This allows the circuit to selectively respond to specific light colors while ignoring ambient light components, maintaining Signal-to-Noise Ratio despite variations in ambient light intensity.
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 configuration effectively reduces the error probability of light detection by maintaining the capacitor voltage level and ensuring accurate identification of specific light sources even under strong white ambient light conditions.
Implementation Method 1
a light filter can be regarded as a band-pass filter for extracting/passing desired light photons with respect to a predetermined light spectrum band, exclusive of other light photons with respect to other light spectrum bands
Implementation Method 2
when an incident light is increased, a light current generated by the transistor is increased accordingly
Data Source
AI summary
An optical sensor circuit includes a capacitor, a first transistor, a second transistor, a third transistor, a fourth transistor, and a fifth transistor. The capacitor includes a first terminal and a second terminal. Each transistor includes a first terminal, a control terminal, and a second terminal. The second terminal of the capacitor is coupled to a reference voltage terminal. The first terminals of the third transistor and the fourth transistor are coupled to a first voltage terminal. The second terminal of the fifth transistor is coupled to a readout line.