Fixing Device Driver Mechanism for Pull-In Force Cancellation
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Solution Overview
Problem
Conventional image forming apparatuses with fixing devices experience issues due to uneven pull-in forces on rollers, leading to abnormal images and reduced durability, as the load difference causes stress on the nip formation members.
Innovation Solution
A driver mechanism incorporating a first and second rotator, a bearing, a housing, a drive gear, and idler gears is designed to cancel the pull-in force by adjusting the position of the rotation center of the idler gears within specific diametric ranges, ensuring balanced force distribution and reducing the pull-in force on the pressure roller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a gear is attached to a roller shaft to drive a roller in the fixing device, then the roller can be driven to rotate, but a pull-in force is generated that causes load difference and reduces durability
Solution Approach 1:
The patent introduces a counterweight mechanism that generates a counterbalancing force opposite to the pull-in force. The counterweight is positioned and dimensioned such that its gravitational force or elastic restoring force compensates for the pull-in force, thereby reducing the net load on the roller shaft and improving durability while maintaining rotation capability.
Solution Approach 2:
The patent modifies physical parameters such as the position of the roller shaft, the orientation of the drive gear, or the characteristics of supporting elements (springs, dampers) to change the force distribution. By adjusting these parameters, the pull-in force is minimized and load is evenly distributed, enhancing reliability without sacrificing driving function.
2Device complexity
If the driver drives a roller on one end, then the structure is simple, but the pull-in force is biased causing abnormal images
Solution Approach 1:
The patent divides the driving function into multiple segments or points of force application. Instead of a single drive gear on one end, additional idler gears or drive elements are introduced at different positions along the roller shaft. This segmentation distributes the driving force and eliminates the pull-in bias, ensuring uniform roller rotation and preventing image defects.
Solution Approach 2:
The patent introduces intermediary elements such as idler gears or force-transmitting mechanisms between the drive gear and the roller shaft. These intermediaries redistribute the driving force along the roller, eliminating the concentrated pull-in force at one end and ensuring uniform force distribution for high-quality image formation.
3Reliability
If a pull-in force cancelling mechanism is added to reduce pull-in force, then durability improves, but device complexity increases
Solution Approach 1:
The patent combines the pull-in force cancellation function with the existing driving mechanism. The counterweight or additional drive elements are integrated into the driver assembly, sharing common components such as the housing, mounting structure, and lubrication system. This merging approach reduces the overall complexity increase while achieving the durability improvement.
Solution Approach 2:
The patent designs components to serve multiple functions. For example, the housing not only provides structural support but also serves as a mounting structure for the counterweight mechanism. The idler gears both transmit driving force and act as structural elements that distribute load. This multi-functionality reduces the need for separate dedicated components, minimizing complexity increase.
Data Source
AI summary
A driver includes a first rotator, a second rotator, a bearing, a housing, a drive gear, a first idler gear, a pivot member, and a second idler gear. The first idler gear is meshed with the drive gear. The pivot member rotates around a rotation center axis in the housing and includes an idler gear support portion rotatably holding the first idler gear. The second idler gear is meshed with the first idler gear and disposed on the rotation center axis of the pivot member. A rotation center of the pivot member is present in a region outside a circle having a diameter of 1.5×L and inside a circle having a diameter of 1.8×L around a rotation center of the first idler gear, when a distance between a rotation center of the first rotator and the rotation center of the first idler gear is L.