Wedge-Shaped Light Guide Plate for Thin Backlight Modules
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Solution Overview
Problem
Conventional backlight modules have a significant thickness difference between the light source and the light guide plate, leading to fabrication challenges and reduced yield in injection molding, particularly for portable information products where thinness is crucial.
Innovation Solution
A wedge-shaped light guide plate with a widened edge plane opposite to the light entrance plane, allowing for non-uniform thickness and increased material injection area during molding, which reduces fabrication difficulties and improves yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the light guide plate thickness is reduced to meet thinness requirements, then the overall module thickness is reduced, but the injection molding yield decreases
Solution Approach 1:
The light guide plate transitions from a uniform thickness design to an asymmetric wedge-shaped design, where the thickness varies from one end to the other. This asymmetric structure allows the thinnest part to meet the overall thinness requirement while the thicker region provides sufficient material for successful injection molding, thereby resolving the contradiction between reducing thickness and maintaining molding yield.
Solution Approach 2:
Different regions of the light guide plate are given different thicknesses to serve different functions. The region near the light source maintains a smaller thickness to achieve the thin profile, while the opposite end has a larger thickness to ensure adequate material for injection molding and structural integrity, thus resolving the contradiction locally across different zones of the component.
2Length of stationary object
If the light guide plate thickness is reduced, then the overall module thickness is reduced, but the housing design becomes more complex with winding portions
Solution Approach 1:
The asymmetric wedge-shaped light guide plate eliminates the need for symmetric winding portions in the housing. By concentrating the thickness variation in the light guide plate itself, the housing can maintain a simpler, more uniform structure without requiring complex winding sections to accommodate thickness differences, thus resolving the contradiction between thinness and housing simplicity.
3Length of stationary object
If the light guide plate thickness is reduced below 0.8mm, then the thinness requirement is met, but the injection molding process becomes difficult with reduced yield
Solution Approach 1:
The asymmetric wedge design allows the light guide plate to have an average thickness below 0.8mm to meet thinness requirements, while the thicker end provides sufficient material depth for the injection molding process to succeed. This resolves the contradiction by allowing the thinnest critical regions to be under 0.8mm while ensuring the molding process can still accommodate areas with adequate material.
Solution Approach 2:
The light guide plate features local quality variation where different regions have different thicknesses. The region that requires thinness for the final product specification is made thin, while the region that requires sufficient material for successful injection molding is made thicker, thus resolving the local contradiction between thinness and manufacturability.
Data Source
AI summary
A backlight module has a light guide plate and a light source. The light guide plate contains a top plane, a bottom plane opposite to the top plane, a light entrance plane positioned between the top plane and the bottom plane, and a widened edge plane opposite to the light entrance plane. The widened edge plane is slanted relative to the light entrance plane.