Fingerprint Sensor Light Transmission Area Design
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Solution Overview
Problem
Fingerprint sensors embedded in display devices, particularly those using the light sense method, face challenges in reducing manufacturing costs and module thickness while maintaining effective fingerprint sensing capabilities.
Innovation Solution
A fingerprint sensor design that integrates a light transmission area with the circuit element layer and light emitting layer, utilizing a substrate with conductive layers, light emitting elements, and light sensors, where the light transmission area is optimized to maximize the effective image area by forming opening portions in the pixel definition layer, allowing for selective light reception without a separate light shielding layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate light shielding layer is added to the fingerprint sensor, then light reception control is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent combines the light shielding function with the pixel definition layer, eliminating the need for a separate light shielding layer. The pixel definition layer is designed to define both pixel boundaries and provide light shielding, merging two functions into one structure, thereby reducing manufacturing cost and device complexity while maintaining light reception control
Solution Approach 2:
The pixel definition layer is designed to serve multiple functions: defining pixel boundaries, providing light shielding, and enabling light transmission pathways. This multi-functional design eliminates the need for additional dedicated light shielding components, reducing overall device complexity
2Area of stationary object
If the light transmission area is increased, then effective image area is maximized, but manufacturing precision requirements increase
Solution Approach 1:
The light transmission area is segmented into multiple opening portions distributed across different layers (pixel definition layer, circuit element layer). This segmentation allows each opening to be smaller and easier to manufacture with precise alignment, while collectively providing a large effective image area for light transmission
3Reliability
If multiple conductive layers are used in the circuit element layer, then electrical functionality is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs a nested structure where multiple conductive layers are stacked vertically within the circuit element layer, with each layer serving specific electrical functions (signal transmission, power supply, grounding). This nested arrangement provides complete electrical functionality while organizing the manufacturing process in a systematic sequence, making it easier to produce despite the multiple layers
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 design reduces the module thickness of display devices, improves the efficiency and reliability of fingerprint sensing by maximizing the effective image area and eliminating the need for a separate light shielding layer, thereby lowering manufacturing costs.
Implementation Method 1
a light emitting element layer on the circuit element layer and including light emitting elements
Implementation Method 2
capable of selectively receiving reflection light from a user's finger
Implementation Method 3
a light sensor layer on a second surface of the substrate and including light sensors
Data Source
AI summary
A fingerprint sensor includes: a substrate; a circuit element layer on a first surface of the substrate and including a plurality of conductive layers; a light emitting element layer on the circuit element layer and including light emitting elements and a light shielding layer; and a light sensor layer on a second surface of the substrate and including light sensors, wherein the light shielding layer includes contact holes exposing first electrodes of the light emitting elements, and first opening portions exposing a portion of the circuit element layer, and the circuit element layer includes second opening portions formed in the plurality of conductive layers and includes a light transmission hole of which at least a portion overlaps the first opening portions.