Curved LCD Light Leakage via Adhesive Modulus Control
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Solution Overview
Problem
Conventional liquid crystal display devices in normally black mode exhibit light leakage when curved, particularly around the corners of a black display screen, due to stress-induced photoelastic retardation effects.
Innovation Solution
A liquid crystal display device structure featuring a liquid crystal panel with a first adhesive layer bonding the second polarizing plate and a supporting substrate at outer edges, where the Young's modulus of the first adhesive layer is equal to or higher than that of the second adhesive layer, and all layers are formed from the same material, ensuring balanced stress distribution and reduced curvature deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a liquid crystal panel in normally black mode is curved, then the panel can be applied to curved display applications, but light leakage appears in the black display state due to stress-induced photoelastic retardation
Solution Approach 1:
The patent applies different Young's modulus values to different adhesive layers at specific locations. The first adhesive layer (between second polarizing plate and supporting substrate) has a higher Young's modulus than the second adhesive layer (between first and second substrates), creating localized mechanical property differences that control stress distribution specifically at the curved panel's outer edges where light leakage occurs
Solution Approach 2:
The patent changes the mechanical parameter (Young's modulus) of the adhesive layers to control stress distribution. By setting the Young's modulus of the first adhesive layer to be equal to or higher than that of the second adhesive layer, the patent modifies the mechanical properties to minimize stress-induced photoelastic retardation and eliminate light leakage in curved display applications
2Device complexity
If the first substrate and second substrate have the same thickness in a curved panel, then the structure is simplified, but stress distribution becomes unbalanced causing photoelastic retardation and light leakage
Solution Approach 1:
The patent introduces adhesive layers as intermediary elements between the substrates and supporting structures. These adhesive layers act as mediators that control stress transmission and distribution, with the first adhesive layer (having higher or equal Young's modulus) specifically mediating the stress between the second polarizing plate and supporting substrate to prevent unbalanced stress distribution and light leakage
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 effectively suppresses light leakage in the black display state by minimizing stress-induced retardation effects, maintaining a stable curvature and reducing light leakage intensity, even when the device is curved.
Implementation Method 1
the first substrate 121 has a tensile stress and the second substrate 122 has a compressive stress, with the liquid crystal layer 123 serving as a boundary (a position without stress). This causes the first substrate 121 and the second substrate 122 to have a photoelastic retardation.
Implementation Method 2
liquid crystal molecules 160 in the liquid crystal layer 123 with no voltage applied
Data Source
AI summary
A liquid crystal display device of the present invention includes in the following order: a liquid crystal panel in a normally black mode; a first adhesive layer; and a supporting substrate. The liquid crystal panel includes, in the order toward the first adhesive layer, a first polarizing plate, a liquid crystal cell, and a second polarizing plate. The liquid crystal cell includes a first substrate, a second substrate facing the first substrate, a liquid crystal layer held between the first substrate and the second substrate, and a second adhesive layer that surrounds the liquid crystal layer and bonds the first substrate and the second substrate at outer edges. The first adhesive layer bonds the second polarizing plate and the supporting substrate at outer edges. A Young's modulus of the first adhesive layer is equal to or higher than a Young's modulus of the second adhesive layer.