Under-display Fingerprint Sensing via Optical Filtering
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Solution Overview
Problem
Under-display fingerprint sensing devices face challenges with low sensitivity, resolution, and slow recognition speed due to interference from the touch screen, which affects the accuracy and efficiency of fingerprint recognition.
Innovation Solution
The proposed under-display sensing device incorporates a liquid crystal display (LCD) module with an optical filter unit and an optical sensing unit, where the optical filter filters light to specific wavelengths and the optical sensing unit detects this filtered light, improving sensitivity by reducing interference and enhancing light transmission to the optical sensing chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the fingerprint sensing module is disposed under the touch screen, then the device can achieve under-display sensing, but the sensing light is easily interfered or influenced by the touch screen, resulting in low sensitivity
Solution Approach 1:
The patent introduces an optical filter as an intermediary component between the light source and the optical sensing module. This filter selectively transmits specific wavelengths of light while blocking others, acting as a mediator that eliminates interference from the touch screen and other environmental factors, thereby improving sensitivity without compromising the under-display sensing capability
Solution Approach 2:
The patent applies local quality by making different parts of the optical system have different optical properties. Specifically, the optical filter has selective transmission characteristics for different wavelengths, allowing only certain wavelengths to pass through to the sensing module while blocking others, thereby optimizing the sensing performance in the specific region under the display
2Adaptability or versatility
If the fingerprint sensing module is disposed under the touch screen, then the device can achieve under-display sensing, but the resolution is low
Solution Approach 1:
The optical filter serves as an intermediary that improves measurement precision by eliminating wavelength-related interference. By selectively transmitting only specific wavelengths that are optimal for fingerprint sensing, the filter enhances the quality of the captured light signal, thereby improving resolution despite the under-display configuration
Solution Approach 2:
The patent employs parameter changes by selecting and transmitting light within specific wavelength ranges. The optical filter is designed to transmit light in the visible spectrum (approximately 400-700nm) while blocking other wavelengths, optimizing the light parameters for fingerprint sensing and thereby improving resolution
3Adaptability or versatility
If the fingerprint sensing module is disposed under the touch screen, then the device can achieve under-display sensing, but the recognizing speed is slow
Solution Approach 1:
The optical filter acts as a mediator that accelerates the recognition process by pre-filtering the light before it reaches the sensing module. This reduces the amount of processing needed to distinguish the fingerprint signal from background interference, thereby improving recognizing speed while maintaining under-display sensing functionality
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 enhances the sensitivity and accuracy of fingerprint recognition by ensuring only filtered light with predetermined wavelengths reaches the optical sensing unit, leading to improved resolution and faster recognition speeds.
Implementation Method 1
The optical filter unit is disposed on the backlight unit at a side opposite to the LCD unit for filtering the light to obtain a filtered light having predetermined wavelengths
Implementation Method 2
The optical sensing unit is disposed on the optical filter unit at a side opposite to the backlight unit for detecting the filtered light from the optical filter unit
Data Source
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AI summary
An under-display sensing device (1) includes a liquid crystal display (LCD) module (2) which includes an LCD unit (21), an optical filter unit (31) and an optical sensing unit (32) . The LCD unit (21) has a display surface (211) and a backlight unit (22) disposed at a side opposite to the display surface (211) for emitting a light. The optical filter unit (31) is disposed on the backlight unit (22) at a side opposite to the LCD unit (21) for filtering the light to obtain a filtered light having predetermined wavelengths. The optical sensing unit (32) is disposed on the optical filter unit (31) at a side opposite to the backlight unit (22) for detecting the filtered light from the optical filter unit (31).