Movable Lens Support for Thermal Expansion in Optical Scanning
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Solution Overview
Problem
Resin optical lenses in image forming apparatuses face thermal distortion and potential peeling due to mismatched thermal expansion coefficients with their supporting members, especially with increased heat from faster polygon mirror rotations, affecting image stability and quality.
Innovation Solution
The optical scanning apparatus employs a lens supporting unit with a movable supporting portion that allows the optical lens to move in the direction of thermal expansion, while restricting movement perpendicular to the light beam path, ensuring the lens remains aligned and fixed in the optical axis direction, thus minimizing distortion and peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the optical lens is firmly fixed to the lens supporting member, then the lens position is held inexpensively with precision, but thermal expansion causes lens distortion and potential peeling
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a fixed lens support structure to a movable one. The lens supporting member is designed to move in the optical axis direction in response to thermal expansion, allowing the lens to expand freely without distortion while maintaining proper positioning. This dynamic adjustment resolves the contradiction between initial positioning precision and long-term stability under thermal conditions.
Solution Approach 2:
The patent employs parameter changes by making the support structure's positional parameters variable rather than fixed. The lens supporting member's position along the optical axis is allowed to change with temperature variations, accommodating thermal expansion of the lens. This parameter change enables the system to maintain reliability across different thermal conditions while preserving manufacturing precision at operating temperature.
2Reliability
If the linear expansion coefficient of the optical lens is matched with that of the lens supporting member, then thermal distortion is reduced, but it is very difficult to perfectly match the coefficients and peeling may still occur with higher calorific values
Solution Approach 1:
The patent extracts the constraint of matched thermal expansion coefficients by allowing the lens and supporting member to have different materials with different expansion properties. Instead of requiring material matching, the design extracts the thermal expansion effect and accommodates it through the movable support structure that can adjust its position independently of material coefficient matching.
Solution Approach 2:
The patent uses parameter changes to decouple the reliability requirement from material coefficient matching. By making the support structure's position a variable parameter that adjusts with temperature, the system achieves lens stability without requiring complex material selection or perfect coefficient matching, even under higher calorific value conditions.
3Productivity
If the number of revolutions of the rotating polygon mirror is increased for faster image formation, then productivity is improved, but the calorific value from the driving device increases, causing greater thermal expansion differences
Solution Approach 1:
The patent applies dynamics by designing a lens support system that can dynamically respond to varying thermal loads. As the polygon mirror rotation speed increases and generates more heat, the movable lens supporting member automatically adjusts its position to accommodate the increased thermal expansion of the lens, maintaining reliability across different productivity levels.
Solution Approach 2:
The patent addresses periodic thermal variations caused by high-speed polygon mirror operation by enabling the lens support structure to periodically adjust its position. The movable support responds to cyclic thermal expansion and contraction during high-speed rotation, maintaining lens stability throughout the operational cycle despite varying thermal loads.
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 stabilizes the optical lens position and reduces thermal distortion, maintaining image quality and preventing peeling, even with varying thermal expansion coefficients between the lens and supporting member.
Implementation Method 1
an optical lens configured to guide the light beam scanned by the scanning unit onto the photosensitive member
Implementation Method 2
Heat from a driving device driving the polygon mirror raises the temperature of an optical lens arranged near the polygon mirror, which in turn expands the optical lens thermally
Data Source
AI summary
An optical scanning apparatus includes a light source configured to emit a light beam, a scanning unit configured to deflect the light beam from the light source so as to scan a photosensitive member, an optical lens configured to guide the light beam scanned by the scanning unit onto the photosensitive member, and a lens supporting unit having a fixing portion configured to fix the optical lens, wherein the lens supporting unit includes a movable supporting portion configured to restrict movement of the optical lens in a direction perpendicular to a scanning direction of the light beam and an optical axis direction of the optical lens, to restrict movement of the optical lens in the optical axis direction, and to support the optical lens movably in the scanning direction.