Fixing Device Fluid Pressing Member for Uniform Pressure
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Solution Overview
Problem
Conventional fixing devices in electrophotographic systems, such as printers and copying machines, often experience local unevenness of pressing force due to gaps between components, leading to deteriorated image quality.
Innovation Solution
A fixing device with a pressing part that includes a pressing member, a sheet member, and a pressing fluid filled between them, forming an adhesion nip with the fluid and a separation nip without fluid, where the press amounts at both nips are individually adjustable, and controlled by a fluid distribution control member and driver, ensuring consistent pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure auxiliary pad with a heat-resistant elastic bag charged with heat-resistant liquid in vacuum condition is used, then deterioration of toner image by air or moisture is prevented, but local unevenness of pressing force occurs due to gap between the low-friction sheet and the elastic bag
Solution Approach 1:
The patent extracts the heat-resistant liquid from the vacuum-sealed elastic bag configuration and directly fills it into the pressing member cavity. This eliminates the need for the elastic bag and low-friction sheet interface, thereby removing the source of gaps that cause pressing force unevenness while maintaining the beneficial effects of the heat-resistant liquid
Solution Approach 2:
The pressing member is designed to integrate multiple functions: it serves as both the structural component and the fluid containment structure. The cavity within the pressing member directly holds the heat-resistant liquid, combining the functions of structural support and fluid sealing into a single component, eliminating the need for separate elastic bags and reducing interface gaps
2Device complexity
If the pressing part structure is simplified, then device complexity is reduced, but the ability to adjust press amounts at different nips is lost
Solution Approach 1:
The pressing part is segmented into distinct functional zones: the adhesion nip region and the separation nip region. Each region can be independently controlled through the fluid distribution control member, allowing different press amounts to be applied at different locations along the pressure belt, thereby providing adaptability without significant structural complexity
Solution Approach 2:
The pressing member incorporates a fluid distribution control member that can dynamically adjust the distribution of heat-resistant liquid within the cavity. By moving this control member, the system dynamically changes the press amount at different nips, providing adaptability through a relatively simple mechanical adjustment mechanism
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 prevents local unevenness of pressing force, enhancing image quality by maintaining consistent pressure across the nip area, even with varying paper types, and allows for precise adjustment based on the type of recording medium.
Implementation Method 1
a pressing fluid which is filled directly between the pressing member and the sheet member
Implementation Method 2
a fixing roller which is heated to a predetermined temperature by a heater
Data Source
AI summary
A fixing device includes a fixing roller heated to a predetermined temperature by a heater; a pressure belt in pressure contact with the fixing roller; and a pressing part which presses the pressure belt toward the fixing roller. The fixing device adopts a belt-nip system and fixes a toner image formed on a recording medium to the recording medium by heat and pressure while the recording medium is nipped and conveyed through a nip part. The nip part is formed by the fixing roller and the pressure belt and includes an adhesion nip and a separation nip. The pressing part includes a pressing member, a sheet member which covers the pressing surface of the pressing member along a conveying direction of the recording medium, and a pressing fluid which is filled at the adhesion nip between the pressing member and the sheet member.