Fixing Device Capacitor Resistor Circuit for Image Density Uniformity
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Solution Overview
Problem
The existing image forming apparatuses using electrophotographic technology face issues with uneven toner image density due to alternating voltage transfer during the printing process, leading to stripe-pattern nonuniformity, and the surface layer of the fixing film is prone to discharge phenomena during dielectric withstand voltage tests, causing streaks and defects.
Innovation Solution
The apparatus incorporates a capacitor between the pressure roller and the power supply line, reducing alternating impedance and voltage transmission to the transfer nip portion, and includes a fluororesin layer with a conductivity-imparting substance on the fixing film, along with a safety element to minimize discharge during voltage tests by adjusting the gap and using a resistor in series with the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a capacitor is inserted between the pressure roller and ground potential to reduce alternating voltage transmission, then transfer nonuniformity is reduced, but discharge phenomenon occurs during dielectric withstand voltage test altering the release layer
Solution Approach 1:
A resistor is inserted in series with the capacitor to act as an intermediary element that limits current flow during dielectric withstand voltage tests, preventing discharge phenomenon while maintaining the capacitor's ability to reduce alternating voltage transmission during normal operation
Solution Approach 2:
The circuit configuration changes the electrical parameters by adding series resistance, which modifies the current-voltage characteristics during voltage tests while preserving the capacitive impedance reduction effect during printing operations
2Object-affected harmful factors
If the fixing nip portion is separated to protect the release layer from discharge, then streaks are prevented, but impedance increases causing more alternating voltage to be applied to the gap
Solution Approach 1:
The resistor-capacitor series combination serves as an intermediary circuit that allows the fixing nip portion to remain in contact (maintaining low impedance) while limiting discharge current during voltage tests, thus preventing both streaks and release layer alteration
3Reliability
If the heater and pressure roller are pressurized continuously to maintain fixing performance, then fixability is improved, but uneven deformed portions are generated on the fixing film
Solution Approach 1:
The pressure application is made periodic rather than continuous, with the pressure roller pressing against the fixing film during printing operations and separating during idle periods, thus maintaining fixing performance while preventing cumulative deformation
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 suppresses uneven toner image density and protects the surface layer of the fixing film by reducing the voltage applied during dielectric withstand tests, minimizing discharge and preventing streaks and defects.
Implementation Method 1
Application of an alternating voltage to the resistance heating element causes the resistance heating element to generate heat
Implementation Method 2
Since the glass that covers the resistance heating element becomes a capacitor in an equivalent circuit, an alternating voltage is transmitted to the fixing nip portion
Implementation Method 3
a method for inserting a capacitor between a pressure roller or a fixing film and a ground potential to reduce alternating impedance between a fixing nip portion and the ground potential
Data Source
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AI summary
An image forming apparatus of the present invention is provided with, between a commercial alternating power supply and a pressure roller, a conductive path which is different from a power supply path from the commercial alternating power supply to a heater, and with a capacitive element on the conductive path.