Secondary Transfer Roller Pressure Stability via Dynamic Spring Support
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Solution Overview
Problem
In image forming apparatuses using the electrophotographic method, the pressure in the secondary transferring portion is affected by the thickness of the recording medium and frictional wear of the secondary transfer roller, leading to instability in image formation, especially when handling rigid cardstock.
Innovation Solution
An image forming apparatus with a secondary transfer roller that is supported by a movable bearing and urged toward an intermediary transfer belt by a compression spring, where the driving force is transmitted through a coupling member that maintains pressure balance, preventing pressure changes during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a position regulating method is used to fix the secondary transfer roller in position, then the structure is simplified, but the secondary transfer is affected by sheet thickness and frictional wear
Solution Approach 1:
The patent applies the dynamics principle by replacing the fixed position regulation method with a pressure regulation system. The secondary transfer roller is allowed to move dynamically within a range under the action of a spring, enabling the system to automatically compensate for variations in sheet thickness and frictional wear. This dynamic adjustment mechanism maintains stable secondary transfer pressure without requiring complex position regulation structures.
2Reliability
If a direct driving method is used to drive the secondary transfer roller, then the conveyance stability is improved, but the pressure in the secondary transferring portion becomes unbalanced
Solution Approach 1:
The patent applies segmentation by separating the driving function from the pressure regulation function. The driving gear is supported on a separate support shaft independent from the secondary transfer roller's support shaft. This segmentation allows the driving force to be applied without directly affecting the pressure balance in the secondary transferring portion, as the driving gear's rotation does not generate lateral forces that would disrupt the spring-pressure mechanism.
Solution Approach 2:
The patent uses an intermediary mechanism where the driving gear transmits rotational force through a belt or gear connection to the secondary transfer roller, rather than directly mounting the driver on the roller itself. This intermediary transmission path allows decoupling of the driving function from the pressure regulation function, maintaining pressure balance while enabling stable conveyance.
3Stress or pressure
If the secondary transfer roller is pressed toward the intermediary transfer belt by springs, then the pressure is maintained, but the pressure changes when driving force is inputted
Solution Approach 1:
The patent segments the support structure into two independent parts: the secondary transfer roller is supported by one shaft while the driving gear is supported by a separate shaft. This segmentation ensures that the spring force acting on the roller and the driving force applied to the gear do not interfere with each other, maintaining pressure stability throughout operation.
Solution Approach 2:
The patent employs a spring mechanism that acts as a counterbalancing force, continuously adjusting to maintain constant pressure between the secondary transfer roller and the intermediary transfer belt. The spring compensates for any pressure variations caused by driving forces, ensuring stable pressure maintenance during operation.
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
The solution ensures consistent pressure in the secondary transferring portion, maintaining stable image formation and reducing the impact of medium thickness and wear on the transfer roller, enhancing the apparatus's ability to handle diverse recording materials.
Implementation Method 1
a compression spring configured to urge the secondary transfer roller toward the intermediary transfer belt
Implementation Method 2
a coupling member configured to transmit the rotational force from the driving gear to the secondary transfer roller
Data Source
AI summary
An image forming apparatus includes a rotatable toner carrying member; a rotatable transfer member contactable to the image carrying member to transfer a toner image from the image carrying member onto a sheet; an urging member for urging the transfer member toward the image carrying member; a supporting member supporting the transfer member so as to be movable toward and away from the carrying member; a driving source for rotating the transfer member; and a coupling member provided opposed to the transfer member in an axial direction of the transfer member to engage with the transfer member to transfer a driving force from the driving source to the transfer member.