Fill-in Light Unit for Under-Display Optical Devices

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Solution Overview

Problem

The complex structure of backlight units in liquid crystal display (LCD) screens, including film layers, light guide plates, and iron frames, degrades the quality of optical devices like sensors and cameras when they are integrated under the screen, leading to brightness unevenness and a 'black hole' effect, which affects the display quality.

Innovation Solution

A fill-in light unit is introduced between the backlight unit and the optical device, comprising a first light source and a light guide member, such as a Fresnel lens, that diffuses or condenses light to create a transmission light path, reducing brightness differences and improving display effects by transmitting light through the display screen.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a complex backlight unit structure (including film layer, light guide plate, reflection layer, and iron frame) is used to provide uniform illumination, then the backlight can illuminate the display panel effectively, but the quality of optical devices (such as sensors and cameras) integrated under the screen is dramatically degraded due to brightness unevenness and black hole effects

Engineering Contradiction:
Improvebacklight illumination uniformityVSAvoidoptical device quality
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The backlight unit is divided into multiple independent light sources (first light source and second light source) positioned at different locations. Each light source illuminates specific regions, allowing independent optimization of illumination for display areas versus optical device areas, thereby reducing brightness unevenness and black hole effects while maintaining overall illumination uniformity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the backlight unit are designed with different illumination characteristics. The first light source provides illumination optimized for display panel regions, while the second light source provides illumination optimized for optical device regions. This local differentiation allows each region to receive appropriate light quality, improving both display effectiveness and optical device performance simultaneously

Inventive Principle:
Principle #3Local quality

2Reliability

If membrane materials in the light path (film layer, reflection layer, and iron frame) are bored or adjusted to eliminate micro structures, then the light path can be optimized for optical devices, but black holes inevitably appear at positions corresponding to the optical devices on the liquid crystal display

Engineering Contradiction:
Improveoptical device light path qualityVSAvoiddisplay brightness uniformity
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

A light guide plate is introduced as an intermediary component between the light sources and the display/optical device layers. The light guide plate diffuses and redirects light to fill in the black hole regions created by bored membrane materials, while still allowing sufficient light to reach optical devices through the modified light path. This intermediary structure reconciles the conflicting requirements of optical device access and display brightness uniformity

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the light path is adjusted based on established rules by boring film layer, reflection layer, and iron frame, then optical devices can function under the screen, but the display effect is affected due to black hole formation

Engineering Contradiction:
Improveoptical device integration capabilityVSAvoiddisplay visual quality
Core Design Contradiction:
Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

The illumination system is segmented into multiple light sources with different functions: one light source path is optimized for optical device illumination through bored regions, while another light source path provides compensation illumination for display regions. This segmentation allows the system to simultaneously support optical device integration and maintain display visual quality without compromising either function

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The illumination parameters (intensity, distribution, and spectral characteristics) are changed by using multiple light sources with different positions and characteristics. By adjusting these parameters, the system compensates for the black hole effects caused by light path modifications, maintaining both optical device functionality and display quality

Inventive Principle:
Principle #35Parameter changes

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 fill-in light unit enhances the display effect by reducing brightness differences between the transmission light path and other regions, thereby improving the overall display quality of the screen.

Implementation Method 1

a light guide member configured to transmit a light ray emitted by the first light source... The light guide member diffuses or condenses the light ray emitted by the first light source into the transmission light path

Methodology Applied
Scientific EffectLight diffusion: Scattering

Implementation Method 2

a light guide member configured to transmit a light ray emitted by the first light source... The light guide member diffuses or condenses the light ray emitted by the first light source into the transmission light path

Methodology Applied
Scientific EffectLight condensation: Focusing

Implementation Method 3

a light guide member, such as a Fresnel lens, that diffuses or condenses light

Methodology Applied
Scientific EffectFresnel lens: Fresnel Lens

Data Source

PatentEP3819898B1Display screen and terminal
Publication Date: 2023.08.30 HUAWEI TECH CO LTD
  • EP3819898B1 patent drawingFigure 1~3a
  • EP3819898B1 patent drawingFigure 3b~3g
  • EP3819898B1 patent drawingFigure 3h~5

AI summary

A fill-in light unit (30) and a display screen are provided. The display screen includes a display panel (10) and a back light unit (20), configured to provide a light source for the display panel (10), and further includes an optical device hidden under the display panel (10), where a transmission light path formed by light rays received or transmitted by the optical device passes through the display screen. The display screen includes the fill-in light unit (30), where the fill-in light unit (30) is disposed between the back light unit (20) and the optical device. The fill-in light unit (20) includes a first light source (31) and a light guide member configured to transmit a light ray emitted by the first light source (31). When display of the display screen is viewed, because the disposed light guide member transmits the light ray emitted by the first light source (31) to the transmission light path, a brightness difference between the transmission light path and another region on the display screen is reduced, thereby further improving a display effect of the display screen.