Prism Unit Thermal Expansion Management
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Solution Overview
Problem
Conventional reflective liquid crystal projectors face issues with image quality deterioration due to relative positional changes of prisms caused by temperature variations and differences in the coefficient of linear expansion between prisms and their bases, leading to optical performance degradation.
Innovation Solution
A prism unit with a prism base featuring multiple symmetrically arranged seating surfaces and a groove to prevent adhesive spread, allowing for precise bonding and minimizing stress-induced positional changes, while the groove absorbs excess adhesive to prevent strong bonding and maintain optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If prisms are bonded to a prism base made of a material different from that of the prism, then the prism unit can be manufactured with high precision and reliability, but elastic deformation occurs due to difference in coefficient of linear expansion, causing the adhesive to absorb relative movements and potentially deteriorate optical performance
Solution Approach 1:
The patent changes the physical parameters of the adhesive by selecting a material with specific elastic modulus and coefficient of linear expansion that matches the prism base material. This parameter matching prevents differential thermal expansion between the adhesive and prism base, eliminating the root cause of prism orientation changes and optical performance deterioration under temperature variations.
Solution Approach 2:
The patent applies homogeneity by ensuring the adhesive material has uniform properties throughout its structure and matches the thermal expansion characteristics of the prism base. This homogeneous material selection prevents internal stress concentration and differential deformation that would otherwise cause prism positioning errors and optical axis shifts.
2Stability of the object's composition
If the prism is bonded firmly to the prism base, then the positional relationship is maintained, but the adhesive absorbs thermal expansion differences causing prism orientation changes and optical performance deterioration
Solution Approach 1:
The patent modifies the adhesive's physical parameters to match the prism base's coefficient of linear expansion. This parameter alignment ensures that both materials expand and contract at the same rate during temperature changes, preventing relative movement and orientation changes of the prism while maintaining firm bonding for positional stability.
3Reliability
If a groove is formed in the seating surface bonded part, then adhesive overflow is controlled and optical performance is protected, but the bonding area is reduced
Solution Approach 1:
The patent applies local quality by creating a groove only in the peripheral region of the seating surface bonded part, leaving the central bonding area intact. This localized feature prevents adhesive overflow at the boundaries where it would cause harm, while preserving the full bonding strength in the central region. The groove acts as a barrier that contains the adhesive within the desired bonding zone.
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 effectively maintains the positional relationship of prisms, ensuring high environmental reliability and preventing optical performance deterioration due to temperature changes, while controlling adhesive flow to prevent accidental strong bonding.
Implementation Method 1
prisms are bonded and fixed onto the prism base by a UV-curing (ultra violate curing) adhesive
Implementation Method 2
elastic deformation due to a difference in coefficient of linear expansion needs to be considered
Implementation Method 3
A groove is formed between the seating surface and the seating surface bonded part
Data Source
AI summary
A prism unit includes a prism having at least one optical surface in its inside, and a prism base disposing the prism, the prism base including at least three seating surfaces that are attached to a surface orthogonal to the optical surface of the prism, a seating surface bonded part that is bonded to the prism by an adhesive. At least the three seating surfaces and the seating surface bonded part are symmetrically arranged on the optical surface of the prism.