Photosensor Light Shielding Layer for Ambient Light Management
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Solution Overview
Problem
Photosensors used in applications like fingerprint identification face sensitivity loss and potential damage due to strong ambient light, leading to reduced service life and inaccurate light contrast.
Innovation Solution
A photosensor design incorporating a light shielding layer that shields a partial area of the photo-sensing layer, maintaining sensitivity and extending service life by reducing exposure to intense light, with the shielded area ranging from 55% to 99% of the total photo-sensing layer area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the photo-sensing layer is exposed to strong ambient light to maintain photoelectric conversion efficiency, then the sensitivity of the photosensor is maintained, but the service life is reduced due to material deterioration and irreversible damage
Solution Approach 1:
The photo-sensing layer is divided into a shielded portion and a photo-receiving portion. The shielded portion is covered by the light shielding layer to protect it from strong ambient light, while the photo-receiving portion remains exposed to detect light signals. This segmentation allows different regions to serve different functions, extending service life while maintaining sensitivity.
Solution Approach 2:
Different regions of the photo-sensing layer are given different light exposure characteristics. The shielded portion is protected from harmful strong light to maintain material integrity, while the photo-receiving portion is optimized for light detection. This local differentiation resolves the contradiction by applying appropriate light exposure conditions to different areas.
2Measurement precision
If the photo-sensing layer is fully exposed to light to maximize sensing area, then the light detection capability is improved, but the contrast of light cannot be correctly reflected under high-intensity light conditions
Solution Approach 1:
The photo-sensing layer is segmented into shielded and photo-receiving portions. The shielded portion is protected from high-intensity light that causes saturation, while the photo-receiving portion detects light signals. This segmentation prevents saturation effects and maintains accurate light contrast reflection.
Solution Approach 2:
The light shielding layer is positioned over the shielded portion of the photo-sensing layer before light exposure occurs, preventing harmful high-intensity light from reaching and saturating those regions. This preliminary protection ensures that the photo-sensing layer maintains its ability to correctly reflect light contrast even under varying illumination conditions.
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 photosensor maintains sensitivity and extends service life by controlling dynamic range decay to 40% or less, even under strong ambient light conditions, while allowing adjustment of backlight intensity to maintain performance.
Implementation Method 1
the light shielding layer is disposed on the second electrode... the photo-sensing layer has a shielded portion shielded by the light shielding layer
Implementation Method 2
Most of the photosensors sense light by using materials with photoelectric conversion characteristics
Data Source
AI summary
A photosensor includes a substrate, a sensing device, and a light shielding layer. The sensing device is disposed on the substrate and includes a first electrode, a photo-sensing layer, and a second electrode. The first electrode is disposed on the substrate. The photo-sensing layer is disposed on the first electrode. The second electrode is disposed on the photo-sensing layer, and the photo-sensing layer is interposed between the first electrode and the second electrode. The light shielding layer is disposed on the second electrode. Here, the photo-sensing layer has a shielded portion shielded by the light shielding layer and a photo-receiving portion not shielded by the light shielding layer, and an area of the shielded portion is 55% to 99% of an entire area of the photo-sensing layer.