Automotive LCD Backlight Light Guide Fixation
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Solution Overview
Problem
Automotive liquid crystal display devices face issues with vibrations causing rattling noise and thermal expansion leading to warping of the light guide, resulting in color and brightness unevenness due to inadequate fixation and thermal management of the light guide in the backlight.
Innovation Solution
A liquid crystal display device design that includes a light guide with locking projections inserted into L-shaped recesses in a resin frame, combined with a rubber bush for additional stabilization, effectively suppressing movement and warping caused by vibrations and thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light guide is firmly fixed to prevent rattling noise from vibrations, then reliability is improved, but the light guide may warp or deform permanently due to thermal expansion differences between resin and metal
Solution Approach 1:
The container's inner wall is divided into multiple regions: a first region with a first width and a second region with a second width greater than the first width. This segmentation allows the light guide to be fixed at multiple positions with different degrees of constraint, preventing both rattling and warping by distributing thermal expansion stresses across different segments of the fixation structure.
Solution Approach 2:
Different portions of the container's inner wall provide different fixation characteristics. The first region with smaller width provides tighter fixation to prevent rattling, while the second region with larger width allows for thermal expansion accommodation. This local differentiation of fixation quality resolves the contradiction between preventing vibration-induced noise and accommodating thermal expansion.
2Reliability
If adhesive is used to fix the light guide, then fixation reliability is improved, but manufacturing complexity and assembly time increase
Solution Approach 1:
The container structure itself provides the fixation function through its geometric design with varying widths. The container's inner wall configuration automatically constrains the light guide in the desired position without requiring external adhesives or additional fixation components. This self-fixing mechanism simplifies the assembly process while maintaining reliable fixation.
Solution Approach 2:
The adhesive fixation method is extracted and replaced by a purely mechanical fixation system. The container's geometric structure alone provides the necessary fixation, eliminating the need for chemical adhesives and simplifying both the manufacturing process and assembly operations.
3Ease of manufacture
If the light guide is not firmly fixed, then assembly simplicity is maintained, but rattling noise occurs due to vibrations
Solution Approach 1:
The fixation structure accommodates dynamic thermal expansion while maintaining static fixation stability. The varying width configuration allows the light guide to expand and contract dynamically with temperature changes while remaining firmly positioned to prevent vibration-induced rattling noise.
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 solution provides stable fixation and prevents warping of the light guide, ensuring high reliability and uniform brightness and color across a wide temperature range, reducing assembly time and costs by eliminating the need for adhesives.
Implementation Method 1
an elastic body is inserted between the second inner wall of the container and the second side surface of the light guide
Implementation Method 2
a projection is formed at the third side surface or the fourth surface, the projection is inserted in a recess formed in the third inner wall or in the fourth inner wall
Data Source
AI summary
The purpose of invention is to suppress rattling in a backlight for the automotive display. The invention is: the backlight has a light guide, a container, and a light source; the light guide has a first side surface, where the light source opposes, a second side surface opposing to the first side surface, a third side surface and a fourth side surface extending in a second direction, the container has a third inner wall opposing to the third side surface and a fourth side surface opposing to the fourth side surface, a projection is formed at the third side surface or the fourth surface, the projection is inserted in a recess formed in the third inner wall or in the fourth inner wall, the recess has an eave, under which the projection is inserted; thus, movement of the light guide in up and down is suppressed.