Drive Gear Meshing Stability in Image Forming Apparatus
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Solution Overview
Problem
In image forming apparatuses, the instability of the force urging the developing unit towards the image bearing member leads to difficulties in maintaining a consistent gap between the developer bearing member and the image bearing member, potentially causing image defects due to the movable drive transmission gear's interaction with the drive gear.
Innovation Solution
The implementation of a contact-separation mechanism and dual drive input portions with urging portions ensures that the drive transmission gears mesh with the drive gears in a way that the force components cancel each other out, maintaining a stable gap between the developer bearing members and the image bearing member, even when the drive force is not input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a movable drive transmission gear is used to transmit drive force to the drive gear, then the drive force transmission is enabled, but the gap between the developer bearing member and the image bearing member becomes unstable
Solution Approach 1:
The drive transmission mechanism is segmented into two separate input portions (first drive input portion and second drive input portion), each with its own drive transmission gear and urging portion. This segmentation allows the forces to be independently controlled and positioned to cancel each other out, preventing instability in the developing unit's pressing force while maintaining reliable drive force transmission.
2Reliability
If the drive transmission gear is urged toward the drive gear to ensure meshing, then drive force transmission is ensured, but the force causes instability in the developing unit's pressing force
Solution Approach 1:
The patent applies the counterweight principle by configuring two urging portions that generate forces in opposite directions. The first urging portion urges the first drive transmission gear in a first direction, while the second urging portion urges the second drive transmission gear in a second direction that has a force component opposite to the first direction. These opposing forces cancel each other out, eliminating instability in the pressing force while ensuring reliable gear meshing.
3Device complexity
If a single drive input portion is used, then the structure is simple, but the force components cannot cancel each other out leading to gap instability
Solution Approach 1:
The drive input structure is segmented into two separate input portions, each with its own drive transmission gear and urging portion. This segmentation is necessary to achieve the force cancellation effect that stabilizes the gap. The two input portions are configured such that their force components cancel each other out, providing the manufacturing precision required for stable gap maintenance.
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 effectively stabilizes the gap between the developer and image bearing members, reducing the likelihood of image defects by ensuring consistent force direction and magnitude during both mounting and operation.
Implementation Method 1
a first urging portion configured to urge the first drive transmission gear toward the first drive gear... and a second urging portion configured to urge the second drive transmission gear toward the second drive gear
Data Source
AI summary
A direction in which a first drive transmission gear urges a first drive gear using a first urging portion when a drive force is not input to a first drive input portion is defined as a first direction. A direction in which a second drive transmission gear urges a second drive gear using a second urging portion when a drive force is not input to a second drive input portion is defined as a second direction. The second direction has a force component in a direction opposite to the first direction with respect to a straight line connecting a rotation center of the first drive gear and a rotation center of the second drive gear.