Heat Conductive Sheet with Selective Light Transmittance for Optical Fingerprint Sensors
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Solution Overview
Problem
Display devices using light emitting elements face challenges in integrating an optical fingerprint sensor due to heat equalization issues, as conventional heat equalizing sheets have low light transmittance, preventing the sensor's placement below them and compromising heat distribution.
Innovation Solution
A heat conductive sheet with alternating light transmittance and non-transmittance areas is used, allowing heat equalization while enabling optical fingerprint sensing by incorporating heat conductive material in areas overlapping the sensor and maintaining light transmittance for sensing purposes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat equalizing sheet is provided to prevent local deterioration of the light emitting element, then heat equalization is improved, but light transmittance deteriorates, preventing the optical fingerprint sensor from being arranged below it
Solution Approach 1:
The heat equalizing sheet is divided into a first area with light transmittance (for fingerprint sensor placement) and a second area without light transmittance (for heat equalization), allowing both functions to coexist in different regions of the same component
Solution Approach 2:
Different areas of the heat equalizing sheet are assigned different optical properties: the first area has light transmittance to enable sensor operation, while the second area has no light transmittance to maintain heat equalization performance, making each part optimized for its specific function
2Illumination intensity
If an opening corresponding to the optical fingerprint sensor is formed in the heat equalizing sheet, then the optical fingerprint sensor can be arranged below it, but heat cannot be equalized in the opening area
Solution Approach 1:
The heat equalizing sheet merges two previously separate components (heat equalizing layer and light transmissive layer) into a single integrated structure where the first area provides both heat equalization and light transmittance, eliminating the need for openings while maintaining both functions
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 solution allows for effective heat equalization and simultaneous optical fingerprint sensing within the display area, ensuring both heat management and sensor functionality.
Implementation Method 1
a heat conductive sheet overlapping the display circuit layer below the second surface
Implementation Method 2
an optical fingerprint sensor inside the display area below the heat conductive sheet and overlapping the display circuit layer
Data Source
AI summary
A display device includes a display circuit layer including a first surface and a second surface and including a display area in which an image is displayed on the first surface, a heat conductive sheet overlapping the display circuit layer below the second surface, and an optical fingerprint sensor inside the display area below the heat conductive sheet and overlapping the display circuit layer. The heat conductive sheet includes a first area overlapping the optical fingerprint sensor and a second area overlapping the display area around the optical fingerprint sensor. The heat conductive sheet includes a heat conductive material, has a shape having a light transmittance required for sensing by the optical fingerprint sensor in the first area, and has no light transmittance in the second area.