Optical Sensing Circuit Color Filtering Ambient Light Interference
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Solution Overview
Problem
Existing optical sensing circuits sensitive to red light experience erroneous touch control events due to ambient light interference, as red light is a component of white light, leading to incorrect touch indications.
Innovation Solution
The implementation of an optical sensing circuit with color filtering components and photosensitive transistor switches that selectively establish current paths based on the presence of specific colored lights, allowing the circuit to distinguish between red, blue, and other colored lights, thereby reducing ambient light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical sensing circuit is made sensitive to red light for touch detection, then the touch sensitivity is improved, but false touch events occur due to ambient white light interference
Solution Approach 1:
The optical sensing circuit is divided into multiple independent sensing components, each sensitive to different wavelengths of light. Specifically, first sensing components detect red light, second sensing components detect green light, and third sensing components detect blue light. This segmentation allows the system to distinguish between monochromatic red light (touch input) and white light (ambient interference containing multiple wavelengths) by analyzing the pattern of responses across different wavelength channels.
Solution Approach 2:
The patent utilizes color filtering components with different spectral transmission characteristics to create sensing components with selective wavelength sensitivity. By employing color filters that transmit specific wavelength ranges, the circuit can differentiate between light of different colors, enabling it to recognize red light from touch inputs while rejecting green and blue components of ambient white light.
2Reliability
If color filtering components are added to distinguish light wavelengths, then ambient light interference is reduced, but the device complexity increases
Solution Approach 1:
The patent achieves multi-functionality by having each sensing component serve dual purposes: detecting both touch inputs and ambient light characteristics simultaneously. The same sensing components used for touch detection also provide ambient light sensing capability, eliminating the need for separate ambient light sensors and reducing overall system complexity.
Solution Approach 2:
The patent merges the touch sensing function and ambient light sensing function into a single integrated circuit structure. By combining multiple sensing components with different wavelength sensitivities in one circuit, the system achieves both touch detection and ambient light rejection capabilities without requiring separate functional blocks, thereby minimizing device complexity.
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 solution effectively eliminates interference from ambient light, ensuring accurate touch control by differentiating between monochromatic and white light, thereby enhancing the reliability and precision of optical-touch control systems.
Implementation Method 1
a first current path between a first end and a second end of the first sensing component is selectively established according to whether the first sensing component receives first colored light
Implementation Method 2
a second current path between a first end and a second end of the second sensing component is selectively established according to whether the second sensing component receives the first colored light
Implementation Method 3
a third current path between a first end and a second end of the third sensing component is selectively established according to whether the third sensing component receives second colored light
Data Source
AI summary
An optical sensing circuit has a plurality of optical sensing units arranged so that the optical sensing circuit is ambient light insensitive or sensitive to light within certain spectrum. The sensitive spectra corresponding to the plurality of optical sensing units are different from one another.