Elongated Elliptical Lens Patterns for Backlight Uniformity

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Solution Overview

Problem

Conventional diffusion plates in liquid crystal display devices lower brightness levels, thereby deteriorating image quality due to the presence of light diffusing agents.

Innovation Solution

An optical plate with elongated lens patterns forming a part of an ellipse shape, arranged in parallel, and an embossing pattern on its surface, which is used between the light source and the liquid crystal display panel to provide uniform brightness without a diffusing agent, enhancing light transmission efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a diffusion plate with light diffusing agent is used, then light diffusion is achieved, but brightness level is lowered and image quality deteriorates

Engineering Contradiction:
Improvebrightness levelVSAvoidimage quality
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent removes the light diffusing agent from the optical plate composition. Instead of using a diffusion plate with diffusing agents, the invention uses an optical plate with a specific lens pattern structure that achieves uniform illumination through geometric optics rather than scattering, thereby eliminating the brightness-lowering effect of diffusing agents while maintaining image quality

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs a lens pattern with a specific curved surface structure where the cross-section forms part of an ellipse shape with a semi-major axis to semi-minor axis ratio of 1.65 to 1.75. This specific curvature design enables effective light diffusion and uniform illumination without requiring light diffusing agents, thus resolving the contradiction between brightness maintenance and image quality

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Loss of energy

If conventional diffusion plates are used, then light diffusion is provided, but light transmission efficiency is reduced

Engineering Contradiction:
Improvelight lossVSAvoidproduction simplicity
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent uses a lens pattern with a specific elliptical cross-section curvature (semi-major axis to semi-minor axis ratio of 1.65 to 1.75) that optimizes light transmission efficiency. This curved surface structure directs light more effectively compared to conventional diffusion plates, reducing light loss while maintaining manufacturing feasibility through standard molding processes

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent changes the structural parameters of the optical plate by defining specific geometric characteristics of the lens pattern, including the elliptical cross-section with a 1.65 to 1.75 axis ratio and base angles of 38° to 44°. These parameter optimizations improve light transmission efficiency without complicating the manufacturing process

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 optical plate improves brightness uniformity and reduces light loss, resulting in enhanced image quality and reduced production costs by minimizing the need for multiple light sources.

Implementation Method 1

a plurality of lens patterns formed on a first surface of the main body plate... the lens patterns are elongated in a first direction and arranged in parallel with each other in a second direction crossing the first direction

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

An embossing pattern may be formed on a second surface of the main body plate opposite to the first surface

Methodology Applied
Scientific EffectScattering: Scattering

Data Source

PatentEP1855151B1Optical plate, method of manufacturing optical plate, backlight assembly and liquid crystal display device
Publication Date: 2013.02.20 SAMSUNG DISPLAY CO LTD
  • EP1855151B1 patent drawingFigure 1
  • EP1855151B1 patent drawingFigure 2
  • EP1855151B1 patent drawingFigure 3

AI summary

An optical plate (40) includes a main body plate (41), and a plurality of lens patterns (42) formed on a first surface of the main body plate, wherein the lens patterns are elongated in a first direction and arranged in parallel with each other in a second direction crossing the first direction, wherein a cross section of the lens patterns form a part of an ellipse shape, the ratio of a semi-major axis to a semi-minor axis of the ellipse shape ranging from about 1.65 to about 1.75.