Optical Element Gate Design for Molding Quality
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Solution Overview
Problem
Existing optical scanning devices face challenges in manufacturing optical elements with good optical performance due to issues like flowback and molding imperfections, which affect the size and complexity of the device, and lead to increased post-processing requirements.
Innovation Solution
The optical element is designed with a boundary surface between the main body and the gate that is narrower than the gate's end surface, and the distance between corresponding edges on this surface is uniformly formed, allowing for reduced molding imperfections and improved optical performance without increasing the device's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate cross-section is configured to be smaller than the cavity cross-section, then flowback is prevented, but imperfect molding and flow marks are generated on the optical surface
Solution Approach 1:
The invention applies different cross-sectional dimensions at different locations of the gate. The gate has a first cross-sectional dimension at the connection with the injection molding machine and a second cross-sectional dimension at the connection with the cavity, with the first dimension being larger than the second. This local variation in geometry allows the gate to prevent flowback while avoiding the generation of flow marks on the optical surface, thus resolving the contradiction between reliability and manufacturing precision.
2Productivity
If injection speed is increased to shorten manufacturing time, then productivity improves, but flow marks are easily generated on the surface
Solution Approach 1:
The invention changes the geometric parameters of the gate, specifically making the first cross-sectional dimension larger than the second cross-sectional dimension. This parameter modification allows for optimized resin flow characteristics that prevent flow mark generation even at higher injection speeds, thereby enabling improved productivity without sacrificing surface quality.
3Reliability
If the connecting piece between gate and lens part is uniformly formed, then weld lines are prevented, but detachment position assessment becomes difficult and residual gate part increases
Solution Approach 1:
The invention introduces asymmetry in the gate configuration by setting different cross-sectional dimensions at different locations. The gate has a first cross-sectional dimension at the injection molding machine connection and a second cross-sectional dimension at the cavity connection, with the first being larger. This asymmetric design creates a visually distinct detachment position while preventing weld lines, thus resolving the contradiction between structural integrity and ease of manufacture.
Data Source
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Figure 3A
AI summary
The optical element is a long optical element obtained by detaching a long main body part connected to a runner part via a gate part including an optical part from the gate part and chipping the detached main body, the optical part including at least a first optical surface to allow light to pass therethrough or to reflect light. The first optical surface has a curved surface that is curved on the short direction at least at the longitudinal end, while the first edge of the first optical surface side on the end surface of gate part side in the main body part is curved according to the curved surface example of the first optical surface. The boundary surface between the main body part and the gate part is formed so as to be narrower than the end surface of the gate part side of the main body part. At least the distance between the site corresponding to the effective region on the first optical surface at the first edge and the site corresponding to the effective region on the first optical surface at the second edge of the first optical surface side on the boundary surface is uniformly formed.