Fixing Belt Grounding via Single Resistive Element
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Solution Overview
Problem
Existing image forming apparatuses face issues with grounding the fixing belt and pressure roller, leading to potential dielectric breakdown and pinhole leakage due to high-potential surge voltages, which are not adequately addressed by existing grounding mechanisms.
Innovation Solution
A fixing device with a single resistive element connects the fixing belt and pressure roller to the apparatus body, ensuring safe grounding through a simplified current path using a torsion spring, conductive plates, and a resistive element, maintaining stable potential equality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a general grounding mechanism is used for the fixing belt and pressure roller, then the device structure is simple, but high-potential surge voltages can cause dielectric breakdown and pinhole leakage
Solution Approach 1:
A resistive element is introduced as an intermediary component between the pressure roller and the grounding portion. This resistive element acts as a mediator that limits surge voltage while allowing normal grounding current to pass through, thereby preventing dielectric breakdown of the heater protective layer without requiring complex grounding mechanisms
Solution Approach 2:
The grounding mechanism is modified by changing the electrical resistance parameter. A resistive element with specific resistance value is inserted into the grounding path of the pressure roller, transforming the grounding system from a direct low-resistance connection to a controlled high-resistance connection that limits surge voltage while maintaining normal grounding function
2Reliability
If two resistive elements with different resistances are provided in parallel, then pinhole leakage is prevented, but the device complexity increases
Solution Approach 1:
The invention extracts and eliminates one of the two resistive elements from the parallel configuration. By removing one resistive element and retaining only a single resistive element in the grounding path, the design achieves pinhole leakage prevention while significantly reducing device complexity and the number of components
Solution Approach 2:
The single resistive element is designed to perform multiple functions simultaneously: it grounds the pressure roller, limits surge voltage, prevents pinhole leakage, and maintains potential equality between the fixing belt and pressure roller. This multi-functional design eliminates the need for multiple specialized components
3Ease of operation
If the heater protective layer is directly connected to ground through the film and pressure roller, then the grounding is direct, but surge voltage can still cause dielectric breakdown
Solution Approach 1:
The resistive element is installed beforehand in the grounding path of the pressure roller to provide surge voltage protection. This cushioning element is positioned in advance to absorb and limit any surge voltage that may occur during operation, protecting the heater protective layer from dielectric breakdown before the surge can cause damage
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 ensures safe user operation by grounding both components effectively, preventing dielectric breakdown and pinhole leakage, while simplifying the grounding mechanism to reduce device size and complexity.
Implementation Method 1
a power-supply line connected to the heater is provided with a lightning arrester capable of discharging at a stable voltage regardless of the polarity of the surge voltage
Implementation Method 2
The first conductive member is engaged and connected to the second conductive member
Data Source
AI summary
A fixing device includes: an endless fixing belt; a pressure roller capable of being brought into tight contact against the fixing belt; a heater which is provided on an inside of the fixing belt, receives through the fixing belt a pressure due to tight contact against the pressure roller, and heats the fixing belt; a support sheet metal which is provided in an interior of the fixing belt and supports the heater; a first conductive member, a second conductive member, and a resistive element. The first conductive member contacts an end of the support sheet metal projecting laterally beyond an edge of the fixing belt. The second conductive member contacts an end of the pressure roller. The first conductive member is engaged and connected to the second conductive member and the second conductive member is connected through the resistive element to a body to which the fixing device is mounted.