Fixing Device Nip Pressure Control via Sheet-Actuated Displacement
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Solution Overview
Problem
The existing fixing devices in image forming apparatuses face challenges in efficiently managing nip pressure, leading to issues such as sheet jamming and image quality degradation due to prolonged pressure on the pressurizing pad, which can result in operational inefficiencies and maintenance complexities.
Innovation Solution
A fixing device is designed with a displacement mechanism that adjusts the position of the pressurizing member relative to the fixing member, incorporating a release lever and a shim to control nip pressure, along with a detection system using a gate sensor to monitor the presence of the shim and facilitate easy pressure release, thereby preventing deformation of the pressurizing pad and improving operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressurizing member is kept in contact with the fixing member to maintain nip pressure, then the fixing function is improved, but the pressurizing pad deforms over time leading to image quality degradation
Solution Approach 1:
The pressurizing member is designed to be movable relative to the fixing member along the transport direction. The displacement mechanism allows the pressurizing member to move in response to sheet passage, dynamically adjusting the nip pressure to maintain optimal fixing while preventing pad deformation that would degrade image quality.
Solution Approach 2:
The displacement mechanism utilizes the passage of the sheet itself as the actuating force. As the sheet passes through the nip portion, it naturally triggers the displacement mechanism to adjust the pressurizing member position, eliminating the need for external control systems and maintaining self-regulating pressure.
2Manufacturing precision
If a complex detection and control system is added to manage nip pressure, then image quality is maintained, but device complexity increases
Solution Approach 1:
The displacement mechanism is designed to be automatically actuated by the passage of the sheet through the nip portion. The mechanical design allows the sheet itself to trigger the pressure adjustment, eliminating the need for sensors, controllers, or external power sources, thus maintaining image quality while avoiding added complexity.
Solution Approach 2:
The patent replaces electronic detection and control systems with a purely mechanical displacement mechanism. The mechanical design uses the sheet passage force and friction to automatically adjust the pressurizing member position, substituting complex electronic control with simple mechanical interaction.
3Device complexity
If the pressurizing member is fixed in position, then device complexity is reduced, but sheet jamming occurs due to improper pressure management
Solution Approach 1:
The pressurizing member is designed with movable capability along the transport direction, allowing dynamic adjustment of nip pressure during operation. This prevents sheet jamming by adapting pressure to actual operating conditions while maintaining a relatively simple mechanical structure without complex control systems.
Data Source
AI summary
Provided is a fixing device including a fixing member that fixes toner onto a recording material, a pressurizing member that forms a nip portion, through which the recording material passes, between the fixing member and the pressurizing member, a moving member that is disposed to be movable in response to passage of the recording material in a transport path of the recording material which passes through the nip portion, a detection unit that detects a presence or absence of the moving member, a displacement mechanism that changes a position of the pressurizing member with respect to the fixing member, and an attachment/detachment member that is disposed in a detachable manner at a facing position facing the displacement mechanism and comes into contact with the moving member.