Flat Panel Display Optical Sensor with Directional Light Unit
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Solution Overview
Problem
Conventional optical fingerprint sensors face limitations in recognizing exact fingerprint patterns due to the use of diffused lights with low directivity, while capacitive sensors are hindered by complexity and thickness issues, making them unsuitable for portable devices with protective films or hardening glass.
Innovation Solution
A flat panel display with an ultra-thin optical image sensor utilizing a directional optical unit that includes a cover plate, light radiating and incident films with holographic patterns, and a low refractive layer to provide collimated infrared laser beams over a large area, maximizing light efficiency and accuracy by eliminating light noise through selective input of sensing lights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If diffused lights are used in optical fingerprint sensors, then the sensing area can be covered, but the directivity is very low and exact fingerprint pattern recognition is limited
Solution Approach 1:
The patent changes the optical parameter from diffused light to collimated light by introducing a directional optical unit with holographic patterns. This parameter change in light directionality enables both wide area coverage and high measurement precision for fingerprint recognition
2Measurement precision
If collimated lights such as infrared laser are used to improve directivity, then fingerprint recognition accuracy improves, but it is very hard to generate sensing lights to cover wider area
Solution Approach 1:
The patent segments the collimated light beam into multiple directional beams using a holographic diffuser. This segmentation allows the single collimated light source to cover a wide sensing area while maintaining the directional properties needed for accurate fingerprint recognition
Solution Approach 2:
The patent introduces a directional optical unit with holographic patterns as an intermediary between the collimated light source and the fingerprint sensing area. This intermediary device transforms the collimated light into multiple directional beams that cover wide area while maintaining precision
3Area of stationary object
If specific scanning structure is required to radiate collimated lights over wider scan area, then area coverage improves, but the system becomes not suitable for portable or personal display apparatus
Solution Approach 1:
The patent extracts the scanning function from the optical system by using a holographic diffuser that inherently creates multiple directional beams. This eliminates the need for mechanical scanning structures, reducing device complexity while maintaining wide area coverage capability
4Length of stationary object
If capacitive fingerprint sensor is used in portable devices, then device thickness can be reduced, but the structure becomes complex with push button assembly and non-display area increases
Solution Approach 1:
The patent merges the fingerprint sensing function with the display area by using optical sensing through the display panel. This eliminates the need for separate capacitive sensor assemblies and push buttons, reducing both device thickness and structural complexity
5Measurement precision
If high resolution sensor array and IC are formed on same silicon wafer for capacitive sensor, then fingerprint detection capability improves, but the assembly structure becomes very complex and non-display area increases
Solution Approach 1:
The patent replaces the mechanical capacitive sensing system with an optical sensing system. This substitution eliminates the need for complex silicon wafer assemblies and high-resolution sensor arrays, achieving fingerprint detection through optical reflection patterns
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 enables high-resolution, sensitive, and accurate fingerprint recognition across a large area without increasing device thickness, improving sensing performance even with protective films, and maintaining light intensity for precise image sensing.
Implementation Method 1
a light radiating film corresponding to the display area, the light radiating film positioned under the cover plate; a light incident film positioned under the cover plate and disposed outside of the display area adjacent to a lateral side of the light radiating film
Implementation Method 2
a low refractive layer disposed under the light radiating film and the light incident film, the low refractive layer attached on the top surface of the display panel, and having a refractive index that is lower than a refractive index of the cover plate and that is lower than a refractive index of the light radiating film
Implementation Method 3
an image sensor disposed under the sensing light control film
Data Source
AI summary
The present disclosure relates to a flat panel display having an optical imaging sensor such as a fingerprint image sensor. The present disclosure provides a flat panel display having an image sensor comprising: a display panel including a display area and a non-display area, the display panel having a top surface; a directional optical unit attached to the top surface of the display panel, the directional optical unit having a length along a length axis of the display panel, a width along a width axis of the display panel and a thickness along a thickness axis of the display panel; a sensing light control film disposed under the display panel; and an image sensor disposed under the sensing light control film.