Development Roller Pressing Mechanism for Image Quality Stability
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Solution Overview
Problem
Existing process units in image forming apparatuses face challenges in maintaining a stable pressing force between the photoconductor drum and the development roller, especially when the torque acting on the development cartridge increases due to higher printing speeds, leading to issues like fogging and uneven image density.
Innovation Solution
The process unit incorporates a development frame with a coupling joint and a support portion, allowing the development roller to be pressed against the photoconductor drum by the rotation moment from the coupling joint, which is disengageably engageable with an external driving force. This configuration ensures stable contact and prevents oscillation of the development frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the development cartridge is not fixed relative to the photoconductor drum, then the development roller can rotate freely, but the development cartridge oscillates under torque causing unstable pressing force
Solution Approach 1:
A pressing mechanism is introduced as an intermediary component between the development cartridge and the photoconductor drum. This pressing mechanism includes a pressing member that can be elastically deformed, serving as a mediator to transmit force while accommodating the oscillation of the development cartridge, thereby maintaining stable pressing force despite the unfixed state of the cartridge.
Solution Approach 2:
The pressing mechanism utilizes elastic deformation of the pressing member to change its physical state dynamically. When the development cartridge oscillates under torque, the pressing member deforms elastically to absorb the oscillation energy, and then returns to its original shape to maintain consistent pressing force, effectively changing the parameter of the pressing member's physical state to stabilize the system.
2Manufacturing precision
If the development cartridge is pressed against the photoconductor drum, then uniform surface contact is achieved, but excessive pressing force causes fogging and uneven density
Solution Approach 1:
The pressing mechanism is designed with a pressing member that can dynamically adjust its pressing force through elastic deformation. Instead of a rigid fixed pressing force, the system allows the pressing member to flex and recover, creating a dynamic pressing force that maintains uniform contact while preventing excessive force at any single moment, thus avoiding fogging and density unevenness.
Solution Approach 2:
The elastic pressing member acts as a cushioning element that anticipates and absorbs excessive pressing force before it can cause harm. When the development cartridge oscillates or when torque varies, the pressing member deforms elastically to cushion the impact, preventing the transmission of excessive force to the photoconductor drum surface, thereby preventing fogging and density defects.
3Productivity
If the development roller rotates at higher speeds, then productivity increases, but torque increases causing oscillation and pressing force instability
Solution Approach 1:
The invention converts the harmful oscillation caused by high-speed rotation into a beneficial effect. The elastic pressing member utilizes the oscillation energy from the development cartridge's high-speed rotation to maintain stable pressing force. The oscillation that would normally cause instability is instead harnessed to keep the pressing member engaged, transforming the harmful vibration into a stabilizing force that maintains consistent contact between the development roller and photoconductor drum.
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 solution maintains a stable pressing force between the development roller and the photoconductor drum even at higher torques, preventing issues like fogging and ensuring high-quality image formation. The use of a coupling joint and support portion distributes the rotation moment evenly, preventing gear disengagement and maintaining image quality.
Implementation Method 1
a center of rotation of the development roller is located in a position shifted from a line segment connecting a center of rotation of the coupling joint and a center of rotation of the photoconductor drum to an upstream side with respect to a direction of rotation of the coupling joint as viewed in an axial direction of the development roller, such that the development roller is pressed against the photoconductor drum by the action of the rotatory force received by the coupling joint
Data Source
AI summary
A process unit includes a drum frame supporting a photoconductor drum and a development frame supporting a development roller. The development cartridge is swingably supported by the drum frame at a coupling joint provided at a first side of the development frame and a support portion provided at a second side of the development frame. A center of rotation of the development roller is located in a position shifted from a line segment connecting a center of rotation of the coupling joint and a center of rotation of the photoconductor drum to an upstream side with respect to a direction of rotation of the coupling joint as viewed in an axial direction of the development roller, such that the development roller is pressed against the photoconductor drum by the action of the rotatory force received by the coupling joint.