Light Guide Plate Recessed Structure for Backlight Brightness Uniformity

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Solution Overview

Problem

Edge-lit backlight modules in LCDs suffer from uneven brightness due to the light emitting angle of LEDs, resulting in hotspots and overall brightness inconsistencies, especially when using fewer LEDs.

Innovation Solution

A light guide plate design featuring a first recessed portion at the bottom for accommodating a light source and a second recessed portion at the top, with a spherical cap structure at the bottom surface and a cone-shaped second recessed portion, which effectively converges and reflects light to improve brightness uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If fewer LEDs are used in the edge-lit backlight module, then device complexity is reduced, but brightness uniformity deteriorates due to hot spots

Engineering Contradiction:
Improvenumber of LEDsVSAvoidbrightness uniformity
Core Design Contradiction:
Device complexityVSIllumination intensity

Solution Approach 1:

The patent applies local quality by creating recessed portions at specific locations where LEDs are positioned, and adding light converging structures (spherical caps) and light reflecting structures (conical surfaces) at targeted areas. This localized structural modification addresses the brightness uniformity problem at the light incident side without requiring additional LEDs, thereby maintaining brightness uniformity while reducing device complexity

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs spheroidality by incorporating spherical cap structures as light converging elements within the recessed portions. These spherical caps effectively converge light from the LEDs, and when combined with the conical reflecting structures, create optimized light paths that eliminate hot spots and improve brightness uniformity across the display surface

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Quantity of substance

If fewer LEDs are used, then manufacturing cost is reduced, but light distribution evenness deteriorates

Engineering Contradiction:
Improvenumber of LEDsVSAvoidlight distribution evenness
Core Design Contradiction:
Quantity of substanceVSIllumination intensity

Solution Approach 1:

The patent applies local quality by creating recessed portions at specific locations where LEDs are positioned, and adding light converging structures (spherical caps) and light reflecting structures (conical surfaces) at targeted areas. This localized structural modification addresses the brightness uniformity problem at the light incident side without requiring additional LEDs, thereby maintaining brightness uniformity while reducing device complexity

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs spheroidality by incorporating spherical cap structures as light converging elements within the recessed portions. These spherical caps effectively converge light from the LEDs, and when combined with the conical reflecting structures, create optimized light paths that eliminate hot spots and improve brightness uniformity across the display surface

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Ease of manufacture

If LEDs with certain light emitting angle are used, then ease of manufacture is improved, but brightness uniformity deteriorates due to hot spots at light incident side

Engineering Contradiction:
ImproveLED selectionVSAvoidbrightness uniformity
Core Design Contradiction:
Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent applies local quality by creating recessed portions at specific locations where LEDs are positioned, and adding light converging structures (spherical caps) and light reflecting structures (conical surfaces) at targeted areas. This localized structural modification addresses the brightness uniformity problem at the light incident side without requiring additional LEDs, thereby maintaining brightness uniformity while reducing device complexity

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs spheroidality by incorporating spherical cap structures as light converging elements within the recessed portions. These spherical caps effectively converge light from the LEDs, and when combined with the conical reflecting structures, create optimized light paths that eliminate hot spots and improve brightness uniformity across the display surface

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 design ensures even light distribution and prevents hotspots by reflecting light emitted from LEDs within the light guide plate, achieving uniform brightness and enhanced light intensity, even with a reduced number of LEDs.

Implementation Method 1

a light converging structure is provided at the bottom surface of the first recessed portion... the light converging structure is a spherical cap structure which protrudes away from the apex of the cone, such that light emitted from the light source directly arrives at the second recessed portion after passing through the light converging structure

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

the second recessed portion is a cone having an apex adjacent to the first recessed portion... reflecting light emitted from LEDs within the light guide plate

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2733415B1Light guide plate, backlight module and display device
Publication Date: 2020.03.18 BOE TECHNOLOGY GROUP CO LTD
  • EP2733415B1 patent drawingFigure 1~3
  • EP2733415B1 patent drawingFigure 4a~4b
  • EP2733415B1 patent drawingFigure 5a~5b

AI summary

A light guide plate for the edge-lit backlight module comprises a first recessed portion and a second recessed portion. The first recessed portion is provided at the bottom of a light incident end of the light guide plate for accommodating a light source. The second recessed portion is provided at the top of the light incident end of the light guide plate, corresponding to the first recessed portion.