Optical Pickup Light Flux Separating Unit Adhesive Stability
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Solution Overview
Problem
Conventional optical pickup devices experience physical deformation and positional instability due to adhesive shrinkage and thermal changes, leading to aberrations and deteriorated recording and reproducing characteristics, especially in vehicles where temperature fluctuations are significant.
Innovation Solution
The optical pickup device employs a light flux separating unit fixed with two adhesive agents of different hardnesses, one with a higher shore D value for the floor surface and a lower shore D value for the wall surface, along with support protrusions and step parts to maintain stability and accuracy during attachment and under temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a light flux separating unit is fixed to a casing using a single adhesive agent, then the attachment process is simple, but physical deformation such as distortion or torsion occurs due to adhesive shrinkage or adhesive strength during curing, generating aberrations and deteriorating recording and reproducing characteristics
Solution Approach 1:
The adhesive application is segmented into two distinct stages: first applying a low-viscosity adhesive agent to fill gaps and provide initial bonding, then applying a high-viscosity adhesive agent to prevent excessive spread and maintain precise positioning. This segmentation of the adhesive application process resolves the contradiction between simple attachment and precise positioning.
Solution Approach 2:
The invention changes the parameter of adhesive viscosity by using two adhesive agents with different viscosity characteristics. The first adhesive agent has low viscosity for easy filling, while the second has high viscosity for precise position holding. This parameter change enables both simple attachment process and high positioning accuracy.
2Reliability
If the light flux separating unit is fixed with adhesive agents, then attachment is achieved, but thermal degeneration or deterioration of the cured adhesive agent occurs under large temperature changes, causing position shift and light converging position variation
Solution Approach 1:
The invention uses a composite adhesive system comprising two different adhesive agents with complementary properties. The first adhesive agent provides strong bonding and gap filling, while the second adhesive agent provides dimensional stability and thermal resistance. This composite material approach resolves the contradiction between attachment stability and temperature resistance.
3Strength
If adhesive agents are applied generously to ensure strong bonding, then attachment strength is improved, but the light flux separating unit deforms due to adhesive shrinkage during curing
Solution Approach 1:
The first low-viscosity adhesive agent is applied preliminarily to fill gaps and provide a stable base layer before applying the second adhesive agent. This preliminary action prevents excessive shrinkage deformation by ensuring proper adhesive distribution and bonding foundation, while still achieving strong overall attachment strength.
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 prevents deformation and maintains the light flux separating unit's position reliably, improving shape and positional reliability over time, even under extreme temperature variations.
Implementation Method 1
a first adhesive agent having a low viscosity is used to fill gaps between a light flux separating unit and a floor surface
Implementation Method 2
a second adhesive agent having a high viscosity is then applied after the gaps are filled
Data Source
AI summary
A flux separating unit is maintained in a stable state with a high positioning accuracy relative to a physical deformation when the light flux separating unit is attached or a great temperature change after the light flux separating unit is attached, in an optical pickup device including in a casing a projection optical system, a light receiving optical system and the parallel flat plate shaped light flux separating unit that separates a light flux advancing in the light receiving optical system from a light flux advancing in the projection optical system.