Laser Scanning Unit Resin Shrinkage Compensation
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Solution Overview
Problem
The existing manufacturing methods for laser scanning units face challenges in maintaining the focus position of laser light over time due to shrinkage of the synthetic resin support body, which affects image quality in electrophotographic image forming apparatuses.
Innovation Solution
The method involves press-fitting a semiconductor laser element with a flange portion into a through-hole in a synthetic resin support body, forming a step on the inner surface to prevent further movement and maintain the distance to the collimator lens, ensuring consistent focus even with resin shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the semiconductor laser element is press-fitted into the through-hole with the flange portion, then the mounting precision and focus position stability are improved, but the device complexity increases due to the additional step formation and press-fitting process
Solution Approach 1:
The through-hole is pre-formed with an externally-contacting hole portion that will generate a step when the flange portion is press-fitted. This preliminary preparation of the hole structure enables automatic positioning and depth control during the press-fitting operation, ensuring consistent focus positions without requiring complex real-time adjustment mechanisms
Solution Approach 2:
The flange portion of the semiconductor laser element serves a dual function: it provides mechanical retention within the through-hole and simultaneously generates a step on the inner surface of the externally-contacting hole portion during press-fitting. This self-generated step acts as a built-in depth stop and positioning feature, eliminating the need for separate positioning structures
2Ease of manufacture
If the support body is made of synthetic resin, then the ease of manufacture and cost are improved, but the reliability deteriorates due to shrinkage in high-temperature environments affecting focus position
Solution Approach 1:
The support body is designed with heterogeneous structural characteristics: the vertical wall portion containing the through-hole provides rigid mechanical support and precise positioning, while other portions of the support body maintain the benefits of synthetic resin manufacturing. This localized structural optimization ensures dimensional stability in critical areas without sacrificing the overall ease of manufacture and cost-effectiveness of using synthetic resin
Solution Approach 2:
The collimator lens is positioned at a predetermined distance from the semiconductor laser element during assembly, establishing the correct focus position before any thermal shrinkage occurs. This preliminary positioning, combined with the step structure that prevents further movement, ensures that the focus position is set correctly and remains stable even when the resin support body shrinks in high-temperature environments
Data Source
AI summary
A flange portion of this semiconductor laser element is press-fitted, with a front face of the semiconductor laser element serving as the leading head, into an externally-contacting hole portion of a through-hole in a vertical wall portion. The externally-contacting hole portion contacts an outer peripheral surface of the flange portion. A collimator lens is mounted to a support body before or after the flange portion is press-fitted into the externally-contacting hole portion. The press-fitting of the flange portion into the externally-contacting hole portion is stopped at a position where an edge portion, of the flange portion, on the front face side of the semiconductor laser element rests within the externally-contacting hole portion. The collimator lens is mounted to the support body in a path of emitted light in front of the semiconductor laser element.