Trapezoidal Light Guide Plate for Stress-Free Mold Release
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge lies in manufacturing a thin light guide plate for liquid crystal display devices with high accuracy and stability, as existing methods face difficulties in removing the plate from a mold without generating stress and achieving uniform thickness, especially in mass production.
Innovation Solution
A trapezoidal-shaped light guide plate is designed with a wider light radiation surface compared to the bottom surface, allowing easy removal by pushing the bottom surface with an ejector pin, and chamfering the ejector pin mark to prevent unwanted light emission, facilitating accurate injection molding and reducing stress during removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of the light guide plate is reduced to achieve a thin backlight, then the thickness of the display device is reduced, but the removal of the light guide plate from the mold becomes difficult and manufacturing accuracy deteriorates
Solution Approach 1:
The light guide plate is designed with a trapezoidal cross-section where the width at the light radiation surface is greater than the width at the bottom surface. This asymmetric geometry creates a tapered shape that facilitates easy removal from the mold while maintaining structural integrity and manufacturing precision even at reduced thickness
2Length of moving object
If the thickness of the light guide plate is reduced to achieve a thin backlight, then the thickness of the display device is reduced, but stress or damage occurs during removal from the mold
Solution Approach 1:
The trapezoidal shape with greater width at the top than at the bottom creates a self-releasing geometry during ejection. The tapered walls reduce friction and mechanical interlocking with the mold, allowing thin plates to be removed without stress concentration or damage
Solution Approach 2:
The asymmetric geometry is built into the mold design itself, so the stress-reducing feature is present before removal occurs. The shape pre-conditioned the plate for stress-free ejection from the moment of formation
3Length of moving object
If the thickness of the light guide plate is reduced to achieve a thin backlight, then the overall device thickness is reduced, but mass production with high accuracy becomes difficult
Solution Approach 1:
The trapezoidal cross-section with asymmetric widths simplifies the molding process for mass production. The tapered shape allows for easier resin filling, uniform cooling, and stress-free ejection, all of which enhance manufacturing efficiency and consistency across large production volumes
Solution Approach 2:
The patent addresses the optical quality issue by treating the ejector pin mark with a reflective material or coating. This compensates for the visual defect caused by the mark, ensuring that mass-produced units maintain high aesthetic and optical standards despite the necessary ejection process
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 approach enables the production of thin, stable, and accurately formed light guide plates with reduced unwanted light emission, enhancing the manufacturing efficiency and quality of liquid crystal display devices.
Implementation Method 1
the light incident on the light guide plate is directed toward a light-radiation-surface side by a scattering member formed on the bottom surface of the light guide plate
Data Source
AI summary
A backlight which arranges light emitting diodes on a side surface of light guide plate adopts the structure which allows the easy removal of the light guide plate from a mold and makes it difficult for a stress or the like to influence the fine structure of a light incident portion of the light guide plate. In a liquid crystal display device having a backlight which radiates light to a liquid crystal panel, LEDs which constitute a light emitting element are mounted on a light guide plate which is mounted on a backlight, and edge portions of the light guide plate are tapered such that a width of the light guide plate is increased in the removal direction of the side surface of the light guide plate. Further, an ejector-pin mark is formed on a lower surface of the light guide plate by pushing an ejector pin in the removal direction of the light guide plate.