Liquid Crystal Cell Bonding Structure for Stable Cell Gap
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Solution Overview
Problem
The challenge of maintaining a stable cell gap and ensuring strong adhesion between substrates in liquid crystal cells while preventing pressing and overflow phenomena during bonding with outer substrates, particularly due to uneven pressure distribution, is addressed.
Innovation Solution
The optical device incorporates intermediate layers with specific distance relationships (L1-L2 ≥ 20 mm) between outer substrates and intermediate layers to disperse local pressure, using polarizers or polymer films with adhesive layers to maintain cell gap and adhesion, and employs adhesive layers with higher elastic moduli to stabilize the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a pressure-sensitive adhesive layer is formed on the upper substrate to maintain cell gap and provide adhesion, then adhesion force between substrates is improved, but during autoclave bonding the low storage elastic modulus of the outer layer at high temperature causes uneven pressure concentration on the liquid crystal cell edge region, leading to cell gap collapse and liquid crystal overflow
Solution Approach 1:
The patent introduces a support layer with specifically controlled elastic modulus parameters (higher than the pressure-sensitive adhesive layer) to alter the mechanical properties of the bonding structure. This parameter change ensures that during autoclave bonding, the support layer can withstand and distribute the bonding pressure uniformly, preventing the pressure concentration that causes cell gap collapse and liquid crystal overflow, while maintaining the adhesion function of the pressure-sensitive adhesive layer.
Solution Approach 2:
The patent creates a composite structure combining the pressure-sensitive adhesive layer (for adhesion) with a support layer (for mechanical strength and pressure distribution). This composite material approach allows the system to simultaneously achieve strong adhesion between substrates and structural stability during high-temperature bonding, as the support layer compensates for the weak mechanical properties of the adhesive layer at elevated temperatures.
2Ease of manufacture
If the outer layer has low storage elastic modulus at high temperature to maintain flexibility, then ease of bonding is improved, but uneven pressures are concentrated on local regions causing cell gap collapse and liquid crystal overflow
Solution Approach 1:
The patent introduces a support layer with controlled elastic modulus parameters that are higher than those of the outer layer at bonding temperatures. This parameter change allows the support layer to maintain structural integrity and distribute bonding pressures uniformly, preventing local pressure concentration that would cause cell gap collapse, while the outer layer retains its flexibility and ease of bonding characteristics.
Solution Approach 2:
The support layer acts as an intermediary between the outer layer and the liquid crystal cell. It mediates the bonding process by distributing the bonding pressure uniformly across the cell surface, preventing direct concentration of pressure on the cell gap region. This intermediary structure enables both ease of bonding (through the flexible outer layer) and manufacturing precision (through the pressure-distributing support layer).
Data Source
AI summary
The present application relates to an optical device, comprising: a first outer substrate; a liquid crystal cell and a second outer substrate sequentially, wherein the liquid crystal cell comprises an upper substrate including a first base layer and a pressure-sensitive adhesive layer; a lower substrate including a second base layer and spacers; and a liquid crystal layer including a liquid crystal compound between the upper substrate and the lower substrate, and the optical device further comprises: a first intermediate layer between the first outer substrate and the liquid crystal cell, and a second intermediate layer between the second outer substrate and the liquid crystal cell, wherein the optical device of the present application can properly maintain a cell gap of a liquid crystal cell, have excellent adhesion between an upper substrate and a lower substrate, and solve the pressing and overflow phenomena of the liquid crystal cell during bonding with an outer substrate.