Reflective Display Substrate Injection Molding and SiOx Coating
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Solution Overview
Problem
Conventional combiner manufacturing processes require multiple steps, including cutting and roughening, which reduce yield and increase manufacturing complexity due to issues with hard coat film uniformity and substrate material properties like birefringence and hygroscopy.
Innovation Solution
The manufacturing process is streamlined by eliminating the cutting step through injection molding of a cycloolefin-based resin substrate with specific surface roughness and corner geometries, combined with a vapor-deposited SiOx film, to enhance surface hardness and moisture resistance, and using an injection mold with movable and fixed mold sections to facilitate easy mold release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cutting and roughening steps are performed to manufacture the combiner substrate, then the substrate shape and surface roughness can be achieved, but the number of manufacturing steps increases and yield decreases
Solution Approach 1:
The invention combines multiple manufacturing steps (cutting, roughening, and molding) into a single injection molding process. The mold includes both cutting edges for shaping the substrate and roughening surfaces that contact the substrate to create the required surface roughness of 0.3μm or more, eliminating the need for separate cutting and roughening operations and thereby improving productivity while maintaining manufacturing precision
Solution Approach 2:
The roughening surfaces are pre-formed on the mold before the manufacturing process begins. When the substrate is molded, the roughening surfaces automatically impart the required surface roughness to the substrate during the molding process itself, so the roughening action is performed in advance as part of the molding operation rather than as a subsequent separate step
2Strength
If hard coat film is applied to the substrate, then surface hardness is improved, but uniformity of the hard coat film becomes difficult to control and manufacturing complexity increases
Solution Approach 1:
The invention changes the fundamental parameter of surface hardness achievement by eliminating the hard coat film application process entirely. Instead of applying a separate hard coat layer, the substrate surface itself is given the required hardness through the injection molding process and material selection, thereby improving surface hardness while reducing manufacturing complexity
Solution Approach 2:
The invention extracts and removes the hard coat film application step from the manufacturing process. By designing the mold and substrate to achieve surface hardness directly through molding rather than through a separate hard coat layer, the complex multi-step process of hard coat application is eliminated while maintaining the required surface hardness
3Ease of manufacture
If conventional substrate materials are used, then manufacturing is straightforward, but birefringence and hygroscopy issues occur reducing reliability
Solution Approach 1:
The invention uses a composite material structure consisting of a cyclic olefin polymer base resin with added inorganic particles. This composite provides both the ease of injection molding characteristic of polymers and the optical stability and moisture resistance provided by the inorganic particles, thereby improving reliability while maintaining ease of manufacture
Solution Approach 2:
The invention changes the material composition parameter by selecting specific cyclic olefin polymers and adding inorganic particles with controlled content and characteristics. This material parameter change eliminates birefringence and hygroscopy issues while maintaining good injection molding properties, thereby improving reliability without sacrificing ease of manufacture
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 reduces manufacturing steps, increases yield, and improves the antireflection and anti-fingerprint effects while preventing substrate cracking and birefringence issues, resulting in a more efficient and reliable reflective display device production.
Implementation Method 1
a vapor-deposited film formed of SiOx (x is 1 or more and 2 or less) formed on a first surface of the substrate
Data Source
AI summary
A reflective display device includes a substrate that has a side surface and that is formed by injection-molding, and a vapor-deposited film formed on a first surface of the substrate. Two corner portions on one side of the substrate each have a curved portion, and two corner portions on another side opposite to the one side of the substrate each have a bent edge portion. The substrate includes a level difference portion where a second surface side portion is formed recessed with respect to a first surface side portion with a parting line as a boundary, where the parting line is positioned in such a proportion that the first surface side portion becomes greater than the second surface side portion on an opposite side of the first surface side portion with respect to a width dimension of the side surface of the substrate.