Rotary Developing Roller Contact Timing for Image Forming Apparatus
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Solution Overview
Problem
Rotary-type image forming apparatuses face challenges in size reduction and cost minimization due to the need for a driver and space to move developing-device support members radially, leading to image defects from premature toner contact with the image bearing member.
Innovation Solution
The apparatus employs a rotary-type configuration where developing rollers are rotated tangentially into and out of contact with the image bearing member, eliminating the need for a radial driver and additional space, and controls the rotation timing to ensure proper engagement of couplings for efficient toner transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the developing-device support member is moved radially to bring toner bearing member into contact with image bearing member, then proper toner contact is achieved, but apparatus size increases and manufacturing cost increases
Solution Approach 1:
Instead of moving the developing-device support member radially inward to achieve contact, the patent inverts the approach by moving the support member radially outward. The toner bearing member is carried by the support member which rotates and is moved radially outward to contact the image bearing member, eliminating the need for a cam mechanism and reducing apparatus size.
Solution Approach 2:
The patent extracts and eliminates the cam mechanism from the system. By using a radial movement approach instead of radial contact approach, the complex cam-driven radial movement system is simplified, removing the need for additional drivers and space, thereby reducing apparatus size and manufacturing cost.
2Ease of operation
If cam mechanism is used to move developing-device support member radially, then toner bearing member contact control is achieved, but device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent removes the cam mechanism entirely from the system. The contact control function is achieved through the radial movement of the support member itself rather than through a separate cam-driven mechanism, significantly simplifying the device structure and reducing manufacturing complexity.
Solution Approach 2:
The support member performs dual functions: it carries the toner bearing member and simultaneously provides the contact control through its own radial movement. This self-service approach eliminates the need for separate driver mechanisms like cams, reducing device complexity while maintaining operational ease.
3Reliability
If coupling engagement time is ensured by slowing rotation, then proper engagement is achieved, but productivity decreases
Solution Approach 1:
The patent applies preliminary action by moving the support member radially outward before the toner bearing member contacts the image bearing member. This ensures that the coupling engagement is completed in advance, allowing the toner bearing member to be properly rotated and engaged without delaying the overall image formation process, thus maintaining productivity while ensuring reliable coupling engagement.
Data Source
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AI summary
In a rotary-type image forming apparatus, rotation of a rotary is temporarily stopped or slowed down (STEP 1) at a position where a coupling member and a drive transmission member are engageable with each other, and a developing roller (STEP 2) is set in a rotating state. Subsequently, the rotary is rotated (STEP 3) so as to bring the developing roller into contact with a surface of a photosensitive drum.