Elliptical Cross-Section Coupling for Photoreceptor Drum Rotation Stability
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Solution Overview
Problem
Existing rotation driving force transmitting members in electrophotographic image forming apparatuses suffer from backlash and damage due to misalignment of polygonal cross-section centroids, leading to inefficient transmission of rotation force to photoreceptor drums.
Innovation Solution
A rotation driving force transmitting member with a convex member having an elliptical cross-section and a concave member with a matching elliptical cross-section, both twisted, which aligns centroids upon fitting, allowing smooth rotation without eccentricity and reducing impact damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polygonal cross-section convex portion is used in the rotation driving force transmitting member, then the photoreceptor drum can be rotated without eccentricity by aligning centroids during rotation, but the tips of the corners are easily damaged due to impact when starting rotation and during operation
Solution Approach 1:
The patent changes the cross-sectional shape from a polygonal form with sharp corners to an elliptical form with curved surfaces. The convex portion and concave portion both have elliptical cross-sections, eliminating the corner tips that are susceptible to damage. The curved elliptical surfaces distribute stress more evenly during rotation and engagement, preventing the corner damage that occurs in polygonal designs while maintaining centroid alignment for stable rotation.
2Productivity
If the convex portion and concave portion are fitted tightly to transmit rotation force efficiently, then rotation force transmission is improved, but the tips of the corners are more easily damaged due to increased contact pressure
Solution Approach 1:
The elliptical cross-section design replaces sharp corners with curved surfaces that distribute contact pressure more evenly. The curved elliptical surfaces maintain tight fitting for efficient force transmission while avoiding concentration of stress at corner tips, thereby reducing impact damage during operation.
3Reliability
If a polygonal cross-section is used to enable centroid alignment during rotation, then backlash is reduced, but the misalignment of centroids before rotation causes impact when starting
Solution Approach 1:
The elliptical cross-section eliminates the sudden corner-to-corner engagement characteristic of polygonal shapes. The curved surfaces allow for smoother engagement and gradual alignment of centroids, reducing the impact force at startup while maintaining the ability to suppress backlash during rotation through proper centroid alignment.
Solution Approach 2:
The curved elliptical surfaces provide a cushioning effect during the engagement process, absorbing the impact that occurs when the convex and concave portions come together. This beforehand cushioning prevents the sudden impact force that damages polygonal corner tips during startup rotation.
Data Source
AI summary
A rotation driving force transmitting member is disposed between a motor section and a main body of a photoreceptor drum. The rotation driving force transmitting member has a convex member which is provided on the photoreceptor drum side and includes a twisted convex portion with an elliptical cross-section and a concave member which is provided on the motor section side and includes a twisted concave portion with an elliptical cross-section, the concave portion being fitted in the convex portion. The rotation driving force transmitting member transmits rotation driving force by the motor section to the photoreceptor drum via the convex member and the concave member in a state where the convex member is subjected to a drawing force toward the concave member side, due to rotation of the motor section in a state where the convex portion and the concave portion are fitted in each other.