Backlight Support Posts With Floating Connections For Thermal Expansion
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Solution Overview
Problem
Direct-lit backlights in electronic devices often suffer from non-uniform light distribution due to variations in the distance between light-emitting diodes and the diffuser layer, caused by mismatch in coefficients of thermal expansion between the diffuser and the printed circuit, leading to hotspots and dark zones in the display.
Innovation Solution
The implementation of a backlight system with an array of backlight cells, each containing a light source and a cavity reflector, where support posts with floating connections are used to maintain a fixed distance between the diffuser and the printed circuit, allowing for lateral shifting to accommodate thermal expansion mismatches, and are designed to minimize shadowing and ensure uniform illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the diffuser is rigidly fixed to the printed circuit, then the structure is simple and easy to manufacture, but thermal expansion mismatch causes distance variations leading to non-uniform light distribution
Solution Approach 1:
The support post incorporates a floating connection at the printed circuit end that allows lateral movement while maintaining vertical positioning. This dynamic connection enables the diffuser to move laterally with thermal expansion while keeping the vertical distance to light sources constant, resolving the contradiction between structural simplicity and light uniformity
Solution Approach 2:
The support post changes its connection mode from rigid fixed to floating connection, allowing lateral displacement parameter to vary with thermal expansion while maintaining the critical vertical distance parameter constant. This parameter differentiation resolves the thermal expansion mismatch problem without requiring complex active control
2Manufacturing precision
If the distance between light sources and diffuser is tightly controlled, then light uniformity is improved, but the structure becomes more complex and difficult to manufacture
Solution Approach 1:
The support post is pre-formed with a specific height that establishes the correct vertical distance between the diffuser and light sources before assembly. This preliminary dimensioning ensures proper spacing is built-in during manufacturing, eliminating the need for complex post-assembly adjustments while maintaining light uniformity
Solution Approach 2:
The support post acts as an intermediary element between the printed circuit and diffuser, providing a mechanical reference that maintains consistent vertical spacing. This intermediary structure simplifies manufacturing by decoupling the distance control function from the connection function, allowing each to be optimized independently
3Manufacturing precision
If support posts are used to maintain fixed distance, then light uniformity is improved, but shadowing effects may occur reducing overall illumination
Solution Approach 1:
The support post uses a thin, transparent or translucent structure that minimizes light blocking while maintaining mechanical support function. This thin-film approach reduces shadowing effects compared to bulky support structures, preserving overall illumination intensity while ensuring uniform light distribution
Solution Approach 2:
The support post is designed with localized functionality - it provides rigid vertical positioning where needed while being minimally intrusive to light transmission. The post's cross-section is optimized to provide sufficient mechanical strength with minimal light blocking area, resolving the contradiction between structural support and illumination intensity
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 stabilizes the light intensity across the display, reducing hotspots and dark zones, and enhances the dynamic range and uniformity of the backlight illumination, resulting in improved image quality.
Implementation Method 1
a cavity reflector that reflects light from the light source outwardly through a diffuser
Implementation Method 2
The floating connections may allow the second ends to shift laterally relative to the printed circuit to accommodate mismatch in the coefficients of thermal expansion between the diffuser and the printed circuit
Data Source
AI summary
An electronic device may have a display with a backlight. The backlight provides backlight illumination for an array of pixels that is displaying images. The backlight may include an array of cells. Each cell may contain a light source with one or more light-emitting diodes and a cavity reflector that reflects light from the light source outwardly through a diffuser for use in forming the backlight illumination. The light sources may be mounted to a printed circuit. Support posts on the printed circuit may be used to maintain the diffuser at a fixed distance from the printed circuit. The support posts may have opposing first and second ends. The first ends may be attached to the diffuser with fixed connections such as adhesive connections. The second ends may be attached to the printed circuit using floating connections.