In-Display Fingerprint Sensor Layout to Reduce Light Diffraction
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Solution Overview
Problem
Fingerprint sensors embedded in display devices increase device thickness and manufacturing costs, and cause light diffraction at opening portions, affecting accuracy.
Innovation Solution
A fingerprint sensor integrated with a display device that reduces module thickness by incorporating a light transmission area with circuit elements and minimizes light diffraction using a light blocking layer with pinholes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light source, lens, and light sensor array are added to provide fingerprint sensing function, then fingerprint sensing capability is improved, but module thickness and manufacturing cost increase
Solution Approach 1:
The display panel pixels are made to serve dual functions: both display and fingerprint sensing. The light emitting element layer and sensor layer are integrated into the display panel structure, allowing the same physical structure to perform both display and biometric authentication functions, thereby eliminating the need for separate dedicated fingerprint sensor components that would increase thickness
Solution Approach 2:
The fingerprint sensor components (light emitting element layer, sensor layer, opening portions) are merged with the display panel structure. The circuit element layer is integrated within the display panel, and the opening portions are formed within the circuit element layer itself, combining multiple functions into a single integrated structure that reduces overall module thickness
2Illumination intensity
If opening portions are provided to control incident light, then light transmission control is improved, but light diffraction at edges increases
Solution Approach 1:
The opening portions are designed with curved boundaries instead of sharp angular edges. The curved shapes of the opening portions reduce light diffraction at the edges by creating smoother transitions in the light path, thereby maintaining effective light transmission control while minimizing harmful diffraction effects that would interfere with fingerprint sensing accuracy
3Ease of manufacture
If opening portions with sharp edges are used, then manufacturing is simpler, but light diffraction increases and sensing accuracy decreases
Solution Approach 1:
The opening portions are designed with curved boundaries instead of sharp angular edges. The curved shapes of the opening portions reduce light diffraction at the edges by creating smoother transitions in the light path, thereby maintaining effective light transmission control while minimizing harmful diffraction effects that would interfere with fingerprint sensing accuracy
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 achieves a thinner display device with improved reliability and accuracy by integrating a fingerprint sensor with the display, reducing light diffraction and enhancing recognition precision.
Implementation Method 1
a light emitting element layer disposed on the circuit element layer and including at least one light emitting element
Implementation Method 2
a sensor layer disposed on a second surface of the substrate and including at least one light sensor corresponding to the opening portion
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A fingerprint sensor and a display device include a substrate. A circuit element layer is disposed on a first surface of the substrate and includes a semiconductor layer, conductive layers and at least one opening portion. A light emitting element layer is disposed on the circuit element layer and includes at least one light emitting element. A sensor layer is disposed on a second surface of the substrate and includes at least one light sensor corresponding to the opening portion. The opening portion is defined by non-overlapping of the semiconductor layer and the conductive layers, the opening portion has a closed loop shape in plan view, and at least a portion of the closed loop shape includes a curve, or an internal angle of the at least a portion of the closed loop shape is an obtuse angle.