Liquid Crystal Display Polarizing Plate Hole Design for Crack Prevention
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Solution Overview
Problem
Liquid crystal display devices with differently shaped polarizing plates face durability issues due to cracking during heat shock tests, caused by stress from contraction forces, especially when formed using the punching method, which affects reliability and design.
Innovation Solution
Designing differently shaped polarizing plates with shorter lengths in the transverse direction and larger holes at the rear, and smaller holes at the front, with specific curvature radii to minimize cracking and visibility, while maintaining durability and design integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If holes are formed in polarizing plates using the punching method, then differently shaped polarizing plates can be produced, but cracking occurs during heat shock tests due to stress from contraction forces
Solution Approach 1:
The invention changes the geometric parameters of the hole (size, position, shape) to optimize the stress distribution in the polarizing plate. By carefully selecting hole parameters, the stress concentration during thermal contraction is reduced, preventing crack formation while maintaining the desired non-rectangular shape
Solution Approach 2:
The invention introduces asymmetric hole configurations (different hole sizes, positions, or shapes in front and rear polarizing plates) to balance the stress distribution. This asymmetric design allows the structure to better withstand thermal contraction forces from different directions, preventing cracking during heat shock tests
2Shape
If the hole size is reduced to improve design appearance, then visibility of the hole is reduced, but cracking becomes more likely due to increased stress concentration
Solution Approach 1:
The invention optimizes the hole parameters (size, position, shape) to find the optimal balance between visibility and stress concentration. By adjusting these parameters within specific ranges, the design achieves both aesthetic appearance and structural durability
Solution Approach 2:
The invention uses similar hole configurations in both front and rear polarizing plates, creating a symmetric design that balances stress distribution. This copying approach ensures that stress is evenly distributed across the structure, preventing crack initiation while maintaining design consistency
3Length of stationary object
If the transverse direction length is increased to maintain structural integrity, then durability improves, but the polarizing plate becomes more prone to cracking in the machine direction
Solution Approach 1:
The invention introduces asymmetric hole configurations where the front and rear polarizing plates have different hole parameters. This asymmetry compensates for the increased transverse length by creating a stress distribution pattern that prevents crack formation in the machine direction
Solution Approach 2:
The invention applies different hole characteristics at different locations (front vs. rear polarizing plates) to address local stress concentration issues. By tailoring the hole parameters to specific positions, the design achieves overall structural integrity while preventing localized cracking
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 enhances the durability of polarizing plates, reduces light leakage, and prevents degradation of reliability and design in liquid crystal display devices by optimizing the shape and size of holes in polarizing plates.
Implementation Method 1
a durability test (heat shock test) causes cracking in the differently shaped polarizing plates
Implementation Method 2
When the polarizing plate 103 is subjected to a heat shock test to examine the durability, as shown in FIG. 7 (b), a crack 105 occurs from the hole 104 due to stress (contraction force) caused by contraction of the polarizing plate 103
Data Source
AI summary
The liquid crystal display device includes: a first differently shaped polarizing plate provided with a first hole; a liquid crystal display panel; and a second differently shaped polarizing plate provided with a second hole, wherein, when directions parallel to machine directions of the first and second differently shaped polarizing plates are defined as first and second directions, a first length of the first differently shaped polarizing plate in the second direction is shorter than a second length of the second differently shaped polarizing plate in the first direction, and a first radius of curvature of the first hole at a tangent point between a straight line extending in the second direction and the perimeter of the first hole is smaller than a second radius of curvature of the second hole at a tangent point between a straight line extending in the first direction and the perimeter of the second hole.