Optical Filter for Near-Infrared Noise Reduction in Touch Sensing
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Solution Overview
Problem
Silicon-based PIN photodiodes in optical sensing devices have high responses to near-infrared light, leading to noise interference and affecting the quality of touch display sensing, such as fingerprint recognition, due to the high penetration of near-infrared light from the ambient environment.
Innovation Solution
Incorporating a filter that reduces the light intensity of near-infrared light within the optical sensing device, specifically designed to filter out or diminish the near-infrared wavelength band before it reaches the sensing unit, thereby minimizing noise and improving sensing quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If silicon-based PIN photodiodes are used for optical sensing, then the sensing device can detect light signals, but the device produces high noise due to high response to near-infrared light from the ambient environment
Solution Approach 1:
An optical filter is introduced as an intermediary component between the ambient light environment and the photodiode sensing unit. The filter selectively transmits visible light wavelengths while blocking near-infrared wavelengths, thereby mediating the interaction between the harmful near-infrared radiation and the photodiode to prevent noise generation while maintaining useful light detection capability
2Adaptability or versatility
If the photodiode responds to near-infrared light, then more light wavelengths can be detected, but noise increases affecting touch sensing quality
Solution Approach 1:
The optical filter is designed with wavelength-selective properties that create local quality differentiation in the light transmission characteristics. The filter allows specific wavelength bands (visible light) to pass through while blocking other wavelength bands (near-infrared), thereby achieving selective adaptability for different light wavelengths and ensuring reliable touch sensing by eliminating problematic wavelength ranges
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 filter effectively reduces the intensity of near-infrared light, decreasing noise in the optical sensing device and enhancing the accuracy of touch-based sensing applications like fingerprint recognition.
Implementation Method 1
a filter, wherein light to be detected passes through the filter before being collected by the sensing unit, and the filter reduces the light intensity of the light to be detected in the near-infrared light wavelength band
Data Source
AI summary
An optical sensing device is provided. The optical sensing device includes a thin-film transistor, a sensing unit driven by the thin-film transistor, and a filter. Light to be detected passes through the filter before being collected by the sensing unit. The filter reduces the light intensity of the light to be detected in the near-infrared light wavelength band.