Fixing Device Grounding Through Resistive Pressure Roller Connection
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses face issues with grounding the fixing belt and pressure roller, leading to potential dielectric breakdown and high-potential surge voltages, which are not adequately addressed by existing surge voltage discharge mechanisms.
Innovation Solution
A fixing device design that grounds the fixing belt and pressure roller through a single resistive element, using a torsion spring and conductive members to ensure safe grounding and stable potential equalization, simplifying the current paths and reducing device complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lightning arrester is provided to discharge surge voltage, then the heater is protected from high-potential surge voltage, but the device complexity and size increase
Solution Approach 1:
The patent extracts the grounding function from the complex lightning arrester system and implements it through a simple resistive element connected to the pressure roller. This resistive element provides both grounding and surge voltage limitation functions, eliminating the need for separate lightning arrester components while maintaining protection reliability.
Solution Approach 2:
The pressure roller is given a dual function: it serves both as the mechanical pressure component for image fixation and as the grounding path through the resistive element. This multi-functionality integrates the grounding mechanism into the existing structure, reducing overall device complexity while maintaining surge voltage protection.
2Reliability
If the pressure roller is grounded through a resistive element, then dielectric breakdown is prevented, but the grounding path complexity increases
Solution Approach 1:
The grounding path is merged with the pressure roller assembly by connecting the resistive element directly to the pressure roller. This integration combines the grounding function with the mechanical pressure function, creating a unified structure that prevents dielectric breakdown without adding separate grounding components or complex routing paths.
3Reliability
If voltage is gradually increased to the pressure roller, then pinhole leakage of the releasable layer is prevented, but the control system complexity increases
Solution Approach 1:
The patent changes the electrical parameter (resistance) of the grounding path by using a resistive element with specific resistance value. This resistance value is selected to gradually limit voltage increase to the pressure roller, preventing pinhole leakage of the releasable layer while maintaining a simple passive grounding structure without active voltage control mechanisms.
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
Ensures safe operation by grounding the fixing belt and pressure roller, preventing dielectric breakdown and maintaining stable potential, while simplifying the grounding mechanism and reducing device size and complexity.
Implementation Method 1
a resistive element connected to one end of the pressure roller shaft and having a specified resistance value
Implementation Method 2
a heater in contact with the inner periphery of the film, and a pressure roller forming a nip area through the film together with the heater, wherein the heater is grounded through the film, the pressure roller, and a resistive element to a frame ground
Data Source
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AI summary
A fixing device (20) includes: an endless fixing belt (21); a pressure roller (22) capable of being brought into tight contact against the fixing belt (21); a heater (23) which is provided on an inside of the fixing belt (21), receives through the fixing belt (21) a pressure due to tight contact against the pressure roller (22), and heats the fixing belt (21); a support sheet metal (25) which is provided in an interior of the fixing belt (21) and supports the heater (23); a first conductive member (33), a second conductive member (34), and a resistive element (35). The first conductive member (33) contacts an end of the support sheet metal (25) projecting laterally beyond an edge of the fixing belt (21). The second conductive member (34) contacts an end of the pressure roller (22). The first conductive member (33) is engaged and connected to the second conductive member (34) and the second conductive member (34) is connected through the resistive element (35) to a body (2) to which the fixing device (20) is mounted.