Square-Shaped LED Emission for Uniform Backlight Luminance

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Solution Overview

Problem

In direct type LED backlight devices, the arrangement of point-like light sources in a lattice leads to decreased light intensity at overlapping areas due to diffused light rays, resulting in non-uniform luminance and color unevenness, which affects the display quality of liquid crystal display devices.

Innovation Solution

The use of point-like light sources with square-shaped light emission distributions, arranged in a manner where neighboring light sources' emissions overlap parallel to each other, ensuring uniform planar emission without intensity loss at overlapping areas, achieved through specific diffusing lens designs and support base configurations that direct light emissions in desired directions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If point-like light sources are arranged in a lattice pattern, then the device structure is simplified and manufacturing is easier, but light intensity decreases at overlapping areas causing non-uniform luminance

Engineering Contradiction:

Improveease of arranging light sourcesVSAvoiduniformity of light intensity

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent applies local quality by shaping the light emission distribution of each LED light source into a specific square-like pattern with controlled intensity profiles. The diffusing lens is designed to create a light distribution where the intensity varies in a controlled manner across different regions, ensuring that overlapping areas maintain uniform brightness while edge areas provide adequate illumination coverage.

Inventive Principle:

Principle #3Local quality

2Device complexity

If conventional diffusing lenses are used, then the device complexity is reduced, but color unevenness occurs due to non-uniform light emission distribution

Engineering Contradiction:

Improvecomplexity of diffusing lens designVSAvoidcolor uniformity

Core Design Contradiction:

Device complexityVSIllumination intensity

Solution Approach 1:

The patent applies parameter changes by carefully controlling the refractive index distribution and geometric parameters of the diffusing lens. The lens is designed with specific curvature radii and thickness variations that transform the point-like light emission into a square-like distribution pattern, achieving uniform color and intensity without requiring complex multi-element lens systems.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If more light sources are arranged to cover the display area, then illumination coverage is improved, but the number of components increases and costs rise

Engineering Contradiction:

Improveillumination coverage areaVSAvoidnumber of light sources

Core Design Contradiction:

Area of stationary objectVSQuantity of substance

Solution Approach 1:

The patent applies merging by designing each LED light source to emit light in an extended square-like pattern rather than a narrow point-like beam. This allows adjacent light sources to have their emission patterns overlap and merge smoothly, creating continuous uniform illumination across the display area with fewer discrete light source elements required.

Inventive Principle:

Principle #5Merging (Combining)

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 approach enables uniform planar emission with stable light intensity across the display area, improving display quality and reducing the number of light sources needed, thereby lowering costs and enhancing reliability in liquid crystal display devices and television receiving devices.

Implementation Method 1

light emitted from the point-like light source is diffused to have a square-shaped light emission distribution

Methodology Applied

Scientific EffectLight refraction and diffusion: Refraction

Implementation Method 2

optical members such as a diffusing plate and a lens sheet are disposed

Methodology Applied

Scientific EffectLight diffusion: Diffusion

Data Source

PatentUS8783890B2Illumination device, display device, television receiving device, and LED light source utilizing square shaped emission distributions

Publication Date: 2014.07.22 SHARP KK

AI summary

Disclosed are an illumination device to be located immediately below an object to be illuminated, wherein a plurality of point-like light sources are arranged, and a display device provided with the illumination device. Even in a structure wherein the light emitted from point-like light sources is diffused and planarly emitted, in order to provide an illumination device which can uniformly and planarly emit the light without reducing the light intensity at the overlapped portion of the light emitted from the point-like light sources, point-like light sources (LED light sources) each diffusing the light to be emitted in a square-shaped light emission distribution, and an illumination device (LED backlight device) wherein the point-like light sources are arranged in a planar manner so that the square-shaped light emission distributions of the light diffused by the point-like light sources are overlapped in parallel.