Curved Light Guide Hole Edges for Uniform Backlight Distribution

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Solution Overview

Problem

Existing backlight units experience hot spots and irregular light distribution due to the insertion of LEDs into concave holes with sharp edges, leading to non-uniform brightness and degraded light characteristics.

Innovation Solution

The edges of the receiving holes in the light guide plate are curved to improve light distribution, allowing for enhanced light efficiency by directing light towards the sidewalls and creating a larger air gap for better light emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If LEDs are inserted into concave holes with sharp edges in the light guide plate, then the structural stability and LED positioning are improved, but hot spots occur at the surface adjacent to the LEDs due to heat concentration, resulting in non-uniform brightness distribution

Engineering Contradiction:
ImproveLED positioning stabilityVSAvoidbrightness uniformity
Core Design Contradiction:
Stability of the object's compositionVSIllumination intensity

Solution Approach 1:

The sharp edges of the concave holes in the light guide plate are replaced with curved surfaces. Specifically, the edges adjacent to the LED insertion position are formed with a predetermined curvature radius, which smooths the light path and prevents light concentration at sharp corners. This curvature modification eliminates hot spots while maintaining proper LED positioning and structural stability.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Ease of manufacture

If edges with predetermined angles are formed at the concave holes receiving the LEDs, then the manufacturing process is simplified, but the light emitted to the edges is reflected or irregularly travelled, causing degraded light characteristics

Engineering Contradiction:
Improvemold fabrication simplicityVSAvoidlight characteristic quality
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

Instead of using sharp angled edges that are easy to manufacture but cause light reflection and irregular light paths, the patent applies curved surfaces with predetermined curvature radii at the edges of the concave holes. This design choice prioritizes optical performance over manufacturing simplicity, as the curved geometry guides light more predictably and reduces unwanted reflections, thereby improving overall light characteristic quality.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent modifies the geometric parameters of the concave hole edges by introducing curvature radius as a critical parameter. By optimizing the curvature radius value, the design balances between manufacturing feasibility and optical performance, ensuring that the edges smoothly transition from the hole surface without creating sharp reflections while remaining manufacturable with appropriate tooling.

Inventive Principle:
Principle #35Parameter changes

3Area of stationary object

If multiple LEDs are aligned on a plane to uniformly emit light through the entire light emitting surface, then the coverage area is improved, but the heat from multiple LEDs creates hot spots at adjacent surfaces, reducing overall light efficiency

Engineering Contradiction:
Improvelight emitting surface coverageVSAvoidlight efficiency
Core Design Contradiction:
Area of stationary objectVSLoss of energy

Solution Approach 1:

The patent applies curved edges at the concave holes surrounding each LED in the array. This curvature design prevents heat and light concentration at sharp corners, reducing hot spot formation even when multiple LEDs are densely arranged. The curved geometry distributes the optical and thermal effects more evenly across the light guide plate, maintaining high light efficiency while achieving uniform full-surface illumination.

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

This solution enhances light efficiency by reducing hot spots and improving uniformity, resulting in improved brightness and light distribution across the LCD panel.

Implementation Method 1

the light emitted to the edges may be reflected or irregularly travelled

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

edges provided at receiving holes, which are formed at a lower portion of the light guide plate to receive LEDs, are curved to improve the light distribution

Methodology Applied
Scientific EffectLight refraction: Refraction

Data Source

PatentEP2641128B1Backlight unit
Publication Date: 2018.04.25 LG INNOTEK CO LTD
  • EP2641128B1 patent drawingFigure 1~2
  • EP2641128B1 patent drawingFigure 3(a)~3(b)
  • EP2641128B1 patent drawingFigure 4(a)~5

AI summary

Disclosed is a backlight unit. The backlight unit includes a printed circuit board formed thereon with a plurality of LEDs and a light guide plate having receiving holes to receive the LEDs. At least one round part having a predetermined curvature is formed at an edge defined in an intersection between an upper surface and an inner surface of the receiving hole. Since the round part is formed at the edge in the receiving hole receiving the LED at the portion of the light guide plate, the light distribution is improved so that the light efficiency is increased.