Surface Light Source Layout for Uniform Color at Grid Intersections
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Solution Overview
Problem
Surface light source devices with multiple light-emitting elements arranged in a grid often produce uneven colors, particularly when the direction of LED chips and the grid lines are parallel, leading to strong blue regions at intersections, which is not limited to blue LED and yellow phosphor combinations but applies to all color combinations aiming for uniform light.
Innovation Solution
The surface light source device is designed with light-emitting elements disposed at grid intersections, where the direction of the LED chips is parallel to the grid lines, and the optical arrangement ensures that the chromaticity coordinates at different intersections are carefully managed to minimize color unevenness, with specific conditions on the distance and positioning of light-emitting elements to control light distribution and emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light-emitting elements are arranged in a grid with LED chips parallel to grid lines, then device structure is simplified and manufacturing is easier, but uneven colors are generated at grid intersections
Solution Approach 1:
The patent applies asymmetry by intentionally rotating the light-emitting elements at grid intersections by 45 degrees relative to the grid lines, breaking the symmetric alignment that causes color unevenness. This asymmetric arrangement prevents the constructive interference of blue light at intersection points, thereby eliminating the color unevenness while maintaining a regular overall pattern for manufacturability.
Solution Approach 2:
The patent applies local quality by differentiating the arrangement of light-emitting elements at grid intersections from those at non-intersection points. Specifically, elements at intersections are rotated 45 degrees while others maintain parallel alignment with grid lines. This localized variation in arrangement optimizes color uniformity at critical intersection regions without compromising the overall structural simplicity.
2Stability of the object's composition
If light-emitting elements are arranged with parallel alignment to grid lines, then structural regularity is improved, but color unevenness occurs at diagonal intersections
Solution Approach 1:
The patent introduces asymmetry at grid intersections by rotating light-emitting elements 45 degrees relative to the grid lines, while maintaining parallel alignment at non-intersection points. This selective asymmetric arrangement disrupts the symmetric light path patterns that cause color unevenness at intersections, thereby resolving the contradiction between structural regularity and color uniformity.
Solution Approach 2:
The patent implements local quality by applying different orientation rules to different regions: light-emitting elements at grid intersections are rotated 45 degrees, while elements at non-intersection points maintain parallel alignment with grid lines. This localized differentiation preserves overall structural regularity while eliminating color unevenness at critical intersection regions.
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 configuration effectively suppresses the generation of uneven colors, ensuring a more uniform light output by managing the chromaticity coordinates and light distribution across the surface, particularly reducing strong blue regions at grid intersections.
Implementation Method 1
yellow phosphor 222 that emits fluorescence in response to light from blue LED chip 221
Implementation Method 2
light having reached light diffusion plate 120 and optical sheet 130 is diffused
Data Source
AI summary
A surface light source device of the present invention includes light-emitting devices, a light diffusion plate and an optical sheet. The light-emitting devices are disposed at respective intersections of a grid composed of X-direction lines and Y-direction lines, and each light-emitting device includes a light-emitting element and a light flux controlling member. The light-emitting element includes two LED chips aligned in direction a and a phosphor. Cy>Cy2 is satisfied where Cy1 and Cy2 are y-values of the chromaticity coordinates of a first intersection and a second intersection, respectively, on a virtual circle with a radius of d/2 in each light-emitting device, d representing the distance on the diagonal line of the grid. Each light-emitting element is disposed such that a point where Cy is greater than Cy2 is located on a line parallel to the diagonal line of the grid on the virtual circle.