Enclosing Flange Design for Electrical Insulation in Fixing Devices
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Solution Overview
Problem
The downsizing of image forming apparatuses has made it challenging to maintain an adequate electrical insulation distance between the rotatable member and the frame in fixing devices, compromising the prevention of bias voltage leakage.
Innovation Solution
The design incorporates an enclosing portion on the flange that extends towards the central portion of the film, ensuring an electrical insulation distance without contacting the film's outer peripheral surface, thus preventing voltage leakage while allowing for downsizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flange is designed with a larger rotatable member end portion regulating surface to ensure electrical insulation distance, then the electrical air clearance and creepage distance are ensured, but the device size increases and downsizing is hindered
Solution Approach 1:
The flange structure transitions from a simple planar regulating surface to a three-dimensional configuration with an enclosing portion that extends radially inward. This enclosing portion creates a protective cage around the rotatable member's end portion, providing electrical insulation through multiple spatial dimensions (radial, axial, and circumferential) rather than relying solely on a larger planar surface area.
Solution Approach 2:
The enclosing portion of the flange is designed to radially enclose the rotatable member's end portion, creating a nested structure where the flange's enclosing portion surrounds the rotatable member within its radial profile. This nesting approach provides electrical insulation by creating multiple layers of separation between conductive elements without requiring additional external space.
2Volume of moving object
If the flange is designed with a smaller rotatable member end portion regulating surface to enable downsizing, then the device size is reduced, but the electrical air clearance and creepage distance cannot be ensured
Solution Approach 1:
The flange structure transitions from a simple planar regulating surface to a three-dimensional configuration with an enclosing portion that extends radially inward. This enclosing portion creates a protective cage around the rotatable member's end portion, providing electrical insulation through multiple spatial dimensions (radial, axial, and circumferential) rather than relying solely on a larger planar surface area.
Solution Approach 2:
The enclosing portion of the flange is designed to radially enclose the rotatable member's end portion, creating a nested structure where the flange's enclosing portion surrounds the rotatable member within its radial profile. This nesting approach provides electrical insulation by creating multiple layers of separation between conductive elements without requiring additional external space.
3Volume of moving object
If the enclosing portion is positioned close to the film's outer peripheral surface to minimize device size, then downsizing is achieved, but the electrical insulation distance is compromised
Solution Approach 1:
The enclosing portion acts as an intermediary structural element between the flange and the rotatable member. It provides a controlled gap that maintains electrical insulation while allowing the enclosing portion to extend radially inward for compact design. The enclosing portion serves as a mediator that balances the conflicting requirements of electrical insulation and device miniaturization.
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 effectively maintains an electrical insulation distance between the film and the frame, preventing voltage leakage and enabling the downsizing of the fixing device while ensuring efficient operation.
Implementation Method 1
a heater (heating member) 30... By applying an electrical bias voltage to the rotatable member
Implementation Method 2
a fixing device of a film type including a fixing film moving in contact with a heating member (heater)... good heat transfer efficiency
Implementation Method 3
a pressing roller for forming a nip in cooperation with the rotatable member
Data Source
AI summary
An image heating device includes a cylindrical film, an opposing member opposing the film, an electroconductive frame, and a preventing member provided on the frame to prevent movement of the film and including a preventing surface contacting an end edge of the film when the film moves in a longitudinal direction thereof. The preventing member includes an enclosing portion extending from the preventing surface toward a central portion of the film with respect to the longitudinal direction so as to enclose an outer peripheral surface of a longitudinal end portion of the film, the enclosing portion being provided at a position at which the enclosing portion is in non contact with the outer peripheral surface of the film with respect to a radial direction of the film.