Arc-Shaped Slit Bush Member for Photosensitive Drum Stability
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Solution Overview
Problem
Conventional image forming apparatuses using ring-shaped bush members to support photosensitive drums experience increased geometric tolerance due to temperature variations, leading to radial runout and unstable rotation, which results in image defects like deviation and density variation.
Innovation Solution
The use of arc-shaped bush members with slits extending in the axial direction between the shaft portions and bearing holes, which maintain a constant sliding clearance and prevent outer diameter expansion, ensuring stable rotation regardless of temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a ring-shaped bush member is used to support the shaft portion, then resistance with the bearing portion is reduced, but the outer diameter of the bush member expands due to temperature variation, causing increased geometric tolerance and radial runout
Solution Approach 1:
The bush member is designed with a slit that divides the continuous ring structure into segments, allowing the bush member to expand radially without increasing its outer diameter. This segmentation enables the bush member to accommodate thermal expansion while maintaining precise geometric tolerance and reducing radial runout.
Solution Approach 2:
The bush member's structural parameter is changed by introducing a slit, which fundamentally alters its thermal expansion behavior. Instead of expanding outward, the slit allows the material to expand inward or along the slit length, thereby maintaining a constant outer diameter that preserves manufacturing precision despite temperature variations.
2Temperature
If the outer diameter size of the bush member is increased to accommodate expansion, then temperature variation tolerance is improved, but the sliding clearance increases, causing less stable rotation
Solution Approach 1:
By segmenting the bush member structure with a slit, the invention allows the bush member to tolerate temperature variations without increasing its outer diameter. The slit provides the necessary expansion space while maintaining the original sliding clearance, thereby preserving rotation stability.
Solution Approach 2:
The slit acts as an intermediary element that mediates between the bush member's thermal expansion and the shaft portion. It provides a controlled path for expansion that prevents direct radial expansion, thereby maintaining both temperature variation tolerance and rotation stability.
3Ease of operation
If the bush member is made highly slidable to reduce resistance, then ease of operation is improved, but the bush member expands radially due to temperature variation, causing runout and image defects
Solution Approach 1:
The slit-based segmentation allows the bush member to maintain its highly slidable properties for easy rotation while preventing radial expansion that would cause runout. The segmented structure accommodates thermal expansion without compromising the sliding contact quality or rotation stability.
Solution Approach 2:
The structural parameter change (adding a slit) fundamentally alters the thermal expansion characteristics of the highly slidable bush member, allowing it to maintain both its low-friction sliding properties and its dimensional stability during temperature variations, thereby ensuring reliability.
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 maintains consistent sliding clearance and prevents radial runout, ensuring stable rotation and preventing image defects such as deviation and density variation due to temperature fluctuations.
Implementation Method 1
the bush member expands or contracts in the radial direction due to variation in the ambient temperature
Data Source
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AI summary
This image forming apparatus (10) includes a photosensitive drum (11), a shaft portion (65C, 75C), a support portion (71, 72), and a bush member (80). The photosensitive drum (11) is configured to hold a toner image to be transferred to a sheet member. The shaft portions (65C, 75C) are connected to both ends in an axial direction of the photosensitive drum (11), and project outward in the axial direction from a center of the photosensitive drum. The support portions (71, 72) have shaft holes through which the shaft portions (65C, 75C) are inserted, and are configured to rotatably support the shaft portions (65C, 75C). The bush members (80) are interposed between inner surfaces of the shaft holes and outer circumferential surfaces of the shaft portions (65C, 75C), and are each formed in an arc shape having a slit (82) extending in the axial direction.