Optical Laminate Dimensional Control for Sharper VR Lens Bonding
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Solution Overview
Problem
Existing virtual reality display apparatuses using optical laminates experience reduced image sharpness due to slight unevenness in the optical laminate, leading to image distortion.
Innovation Solution
An optical laminate comprising a reflective polarizer with controlled dimensional change upon heating, an absorptive polarizer with an anisotropic absorption layer, adhesive layers with specific elastic modulus, and optionally a λ/4 retardation plate, ensuring high image sharpness when bonded to a lens or used in a virtual reality display apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical laminate including a reflective polarizer and absorptive polarizer is used to separate polarized light, then the separation function is improved, but slight unevenness in the optical laminate causes image distortion and reduced sharpness
Solution Approach 1:
The patent applies parameter changes by controlling the glass transition temperature of the reflective polarizer to be 80°C or higher and the adhesive layer's glass transition temperature to be 100°C or lower. This temperature parameter optimization ensures the reflective polarizer maintains dimensional stability (contraction of 0% or more and less than 0.8%) during bonding processes, preventing unevenness that would cause image distortion while maintaining effective polarized light separation.
Solution Approach 2:
The patent uses composite materials by combining the reflective polarizer with specific adhesive layers having controlled glass transition temperatures. This composite structure allows the reflective polarizer to maintain its polarized light separation function while the adhesive layer provides dimensional stability during bonding, eliminating unevenness and ensuring high image sharpness in the final optical laminate.
2Ease of manufacture
If the reflective polarizer is heated to bond the optical laminate, then the bonding process is improved, but dimensional change causes expansion or breakage
Solution Approach 1:
The patent applies parameter changes by setting the glass transition temperature of the reflective polarizer at 80°C or higher and the adhesive layer's glass transition temperature at 100°C or lower. This creates a temperature window where the adhesive layer becomes flexible for bonding while the reflective polarizer maintains dimensional stability (contraction of 0% or more and less than 0.8%), enabling successful bonding without expansion or breakage.
Solution Approach 2:
The patent applies beforehand cushioning by pre-controlling the dimensional change characteristics of the reflective polarizer through glass transition temperature selection. This pre-prepared dimensional stability (contraction of 0% or more and less than 0.8%) acts as a cushion against thermal expansion during bonding, preventing structural integrity issues while allowing the bonding process to proceed.
3Stability of the object's composition
If the glass transition temperature of the reflective polarizer is increased, then dimensional stability is improved, but bonding difficulty increases
Solution Approach 1:
The patent applies parameter changes by optimizing the glass transition temperature of the reflective polarizer to be 80°C or higher for dimensional stability, while simultaneously setting the adhesive layer's glass transition temperature to 100°C or lower. This coordinated parameter optimization ensures the reflective polarizer remains dimensionally stable during bonding while the adhesive layer becomes sufficiently flexible, resolving the contradiction between stability and ease of bonding.
Solution Approach 2:
The patent uses the adhesive layer as an intermediary with controlled glass transition temperature (100°C or lower). This intermediary material facilitates bonding by becoming flexible at lower temperatures, while the reflective polarizer with higher glass transition temperature (80°C or higher) maintains dimensional stability. The adhesive layer mediates between the conflicting requirements of bonding ease and dimensional stability.
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 optical laminate maintains high image sharpness and smoothness, preventing expansion or breakage during bonding and heat resistance tests, enhancing the overall display quality.
Implementation Method 1
A reflective polarizer is a polarizer having a function of reflecting one polarized light in incidence ray and transmitting the other polarized light
Implementation Method 2
An absorptive polarizer is a polarizer having a function of absorbing one polarized light in incidence ray and transmitting the other polarized light
Implementation Method 3
separating a part of light from external light or an image display device into two orthogonal polarized lights, reflecting one polarized light, and transmitting the other polarized light, thereby generating a virtual image and a real image
Data Source
AI summary
An object of the present invention is to provide an optical laminate which includes a reflective polarizer, an absorptive polarizer, and at least one adhesive layer, and exhibits high image sharpness in a case of being bonded to a lens or the like of a virtual reality display apparatus. The optical laminate of the present invention includes a reflective polarizer, an absorptive polarizer, and at least one adhesive layer, in which, in a case where the reflective polarizer is heated for 1 minute at a temperature higher than a glass transition temperature of the reflective polarizer by 20° C., the reflective polarizer exhibits a dimensional change of a contraction of 0% or more and less than 0.8% in at least one in-plane orientation, and the reflective polarizer is a reflective linear polarizer formed by alternately laminating two or more different types of birefringent layers.