Curved Luminance Equalizer Sheet for Thermal Alignment Stability
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Solution Overview
Problem
Light emitting devices with luminance equalizer sheets experience deterioration in luminance uniformity due to misalignment caused by temperature changes, particularly in vehicles with large temperature fluctuations, resulting from differences in linear expansion coefficients between the light emitting substrate and the luminance equalizer sheet.
Innovation Solution
The light emitting device incorporates a luminance equalizer sheet with a curved shape and a light emitting substrate, where the sheet with the larger linear expansion coefficient has a more pronounced curvature, reducing positional shifts by incorporating an orthogonal direction component in its expansion, and a holding member with a curved shape to maintain the desired curvature and improve assemblability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a holding member is used to fix the relative positions of the light emitting element and the luminance equalizer sheet, then the relative positional relationship is maintained at the positioning point, but misalignment occurs at positions away from the positioning point due to differential thermal expansion
Solution Approach 1:
The patent changes the geometric parameter of the luminance equalizer sheet from flat to curved, specifically designing it with a curvature that compensates for differential thermal expansion. This parameter change allows the sheet to maintain proper alignment across its entire surface despite temperature variations, resolving the contradiction between fixed positioning and overall alignment stability.
Solution Approach 2:
The patent applies curvature to the luminance equalizer sheet to counteract the linear expansion differences between the light emitting substrate and the sheet material. The curved shape creates a geometric compensation mechanism where expansion in one direction is offset by the curvature geometry, maintaining the relative positional relationship between light emitting elements and through-holes across the entire surface.
2Reliability
If the luminance equalizer sheet is made with a curved shape to compensate for thermal expansion, then misalignment is reduced, but the complexity of assembly and manufacturing increases
Solution Approach 1:
The patent optimizes the curvature parameter of the luminance equalizer sheet to achieve the minimum necessary compensation for thermal expansion. By carefully selecting the curvature radius and shape, the patent achieves alignment compensation while keeping the manufacturing complexity manageable, balancing reliability improvement against fabrication difficulty.
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 deterioration of luminance uniformity by reducing misalignment caused by temperature changes, maintaining the desired curvature of the luminance equalizer sheet, and enhancing the light emitting device's luminance uniformity and assemblability.
Implementation Method 1
having a linear expansion coefficient different from a linear expansion coefficient of the light emitting substrate... When the light emitting substrate and the luminance equalizer sheet expand or contract due to temperature changes
Data Source
Figure 1~2
Figure 3
Figure 4A~5B
AI summary
A light emitting device comprises a light emitting substrate with a plurality of light emitting elements, and a luminance equalizer sheet provided opposite the light emitting substrate, having a plurality of through holes for transmitting light irradiated from the light emitting elements and having a linear expansion coefficient different from a linear expansion coefficient of the light emitting substrate, the light emitting substrate and the luminance equalizer sheet being positioned relative to each other at a predetermined position, at least one with a larger linear expansion coefficient among the light emitting substrate and the luminance equalizer sheet having a curved shape, and a degree of curvature of the one with the larger linear expansion coefficient being larger than a degree of curvature of one with a smaller linear expansion coefficient among the light emitting substrate and the luminance equalizer sheet.