Display Panel Transparent Optical Layer for Fingerprint Contrast
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Solution Overview
Problem
Conventional techniques face challenges in improving fingerprint recognition performance in full-screen display products due to limitations in integrating sensors and materials.
Innovation Solution
A display panel with an optically transparent layer having a refractive index greater than air and less than a finger's, and a thickness set to an even multiple of a fingerprint recognition light ray's half-wavelength, enhancing contrast between ridges and valleys through half-wave loss and light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional materials and techniques are used in full-screen displays, then the display area can be maximized, but fingerprint recognition performance deteriorates due to insufficient contrast between ridges and valleys
Solution Approach 1:
An optically transparent layer is introduced as an intermediary between the finger and the display panel. This layer has a refractive index specifically designed to be between that of air and human skin, enabling it to mediate light reflection differences between fingerprint ridges and valleys, thereby enhancing recognition contrast without adding significant structural complexity
Solution Approach 2:
The refractive index of the optically transparent layer is precisely controlled to fall between the refractive index of air (approximately 1.0) and human skin (approximately 1.4). This parameter optimization enables the layer to create sufficient optical path differences for ridge-valley contrast while maintaining high light transmittance, solving the fingerprint recognition problem without complicating the display structure
2Measurement precision
If the optically transparent layer is added to enhance fingerprint recognition, then contrast between ridges and valleys improves, but light transmittance may deteriorate
Solution Approach 1:
The refractive index of the optically transparent layer is optimized to be between that of air and human skin, which minimizes light reflection losses at interfaces while maximizing optical path differences for fingerprint contrast. This parameter selection ensures high light transmittance is maintained despite the additional layer
Solution Approach 2:
The optically transparent layer is constructed using composite materials such as silicon dioxide doped with metal oxide particles or acrylate doped with metal oxide particles. These composite materials provide both the required optical properties for fingerprint recognition and high light transmittance, preventing deterioration of illumination intensity
3Measurement precision
If the optically transparent layer is made thicker to enhance light interference effects, then fingerprint contrast improves, but the layer becomes more susceptible to damage
Solution Approach 1:
The thickness of the optically transparent layer is precisely controlled to be an even multiple of half-wavelengths of the fingerprint recognition light. This parameter optimization achieves sufficient light interference effects for high fingerprint contrast while minimizing the thickness to enhance structural strength and damage resistance
Solution Approach 2:
The optically transparent layer is designed as a thin-film structure that provides its optical function efficiently at minimal thickness. While not literally disposable, the thin design prioritizes durability and resistance to damage over maximum possible thickness, aligning with the principle of using minimal material for optimal function
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 increases reflection difference between ridges and valleys, improving fingerprint recognition performance by enhancing contrast and intensity, while maintaining high light transmittance and wear resistance.
Implementation Method 1
a thickness of the optically transparent layer is an even multiple of a half-wavelength of a fingerprint recognition light ray
Implementation Method 2
a half-wave loss occurs when light is incident from an optically thin medium to get reflected at an optically dense medium
Implementation Method 3
a refractive index of the optically transparent layer is greater than a refractive index of air and less than a refractive index of a finger
Data Source
AI summary
The present application discloses a display panel and a display device. The display panel includes a fingerprint recognition area. The display panel includes a cover plate and an optically transparent layer. The optically transparent layer at least covers a portion of the cover plate located in the fingerprint recognition area. A refractive index of the optically transparent layer is greater than a refractive index of air and less than a refractive index of a finger. A thickness of the optically transparent layer is an even multiple of a half-wavelength of a fingerprint recognition light ray. Half-wave loss and interference of light are used to improve fingerprint recognition performance.