Display Substrate Light Guide Layer Stray Light Filtering
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Solution Overview
Problem
Existing optical fingerprint sensing technologies face challenges in achieving high-definition images due to interference from strong light, leading to blurred and low-definition fingerprint images.
Innovation Solution
A display substrate is designed with a first light guide layer containing light-shielding material and through holes that form collimated light paths, and a second light guide layer with light-shielding material and through holes, both configured to enhance light acquisition by photosensitive sensors, reducing stray light and improving image clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light-shielding material and through holes are introduced to form collimated light paths, then image clarity and definition are improved, but device complexity increases
Solution Approach 1:
The light guide layer is segmented into multiple functional layers (first light guide layer with light-shielding material and through holes, second light guide layer) to control light paths. Each layer performs a specific function: the first light guide layer blocks stray light while the second guides collimated light to the photosensitive sensor, thereby improving image clarity without requiring complete redesign of the entire optical system
Solution Approach 2:
The light guide layer acts as an intermediary component between the light source and the photosensitive sensor. It introduces light-shielding material and through holes to mediate the light transmission path, converting divergent light into collimated light paths that reach the sensor perpendicularly, thus improving fingerprint image definition while maintaining a relatively simple overall structure
2Measurement precision
If light-shielding material is used to block stray light, then fingerprint image definition is enhanced, but light acquisition efficiency may be reduced
Solution Approach 1:
The light-shielding material is applied locally in specific regions of the light guide layer rather than uniformly across the entire structure. The through holes are strategically positioned to allow collimated light passage while the light-shielding material blocks stray light from specific angles. This localized application ensures that useful light is transmitted efficiently while only problematic stray light is blocked, maintaining light acquisition efficiency while enhancing image definition
3Object-affected harmful factors
If collimated light paths are formed through through holes in light guide layer, then stray light interference is reduced, but manufacturing complexity increases
Solution Approach 1:
The light guide layer is designed to perform multiple functions simultaneously: it guides light transmission, blocks stray light through light-shielding material, and forms collimated light paths through through holes. By combining these functions into a single integrated component rather than separate elements, the design reduces the number of assembly steps and simplifies manufacturing processes while effectively reducing stray light interference
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 improves the accuracy and area of the obtained fingerprint image, reducing interference and enhancing definition by using collimated light paths and light-shielding materials to filter out stray light and external natural light.
Implementation Method 1
A material of the first light guide layer includes a light-shielding material
Implementation Method 2
the first light guide layer is provided with a plurality of first through holes therein, and an orthogonal projection of at least one first through hole on the substrate is located within a range of an orthographic projection of a photosensitive sensor
Implementation Method 3
Each photosensitive sensor is configured to acquire light that is emitted by at least one light-emitting device and reflected by a finger
Data Source
AI summary
A display substrate includes a substrate, a plurality of photosensitive sensors disposed on a side of the substrate, and a first light guide layer disposed on a side of the plurality of photosensitive sensors away from the substrate. A material of the first light guide layer includes a light-shielding material. The first light guide layer is provided with a plurality of first through holes, and an orthographic projection of at least one first through hole on the substrate is located within a range of an orthographic projection of a photosensitive sensor of the plurality of first through holes on the substrate.