Ungrounded Fixing Member Suppresses Toner Offset
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Solution Overview
Problem
Image forming apparatuses face the issue of electrostatic offset, where toner from the toner image adheres to the outer peripheral surface of the first fixing member and is transferred to subsequent sheets, causing image failure, despite the use of charge applying devices to mitigate this phenomenon.
Innovation Solution
A fixing device with a first fixing member in an ungrounded state, a second fixing member, a pressing member, and a heating device forms a nip portion, where the first fixing member is heated and pressed against the second member, preventing toner adhesion through electrostatic means without the need for complex charge applying devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a charge applying device is used to suppress electrostatic offset, then image quality is improved, but device complexity increases
Solution Approach 1:
The invention extracts and utilizes the electrostatic charge that naturally accumulates on the fixing member during operation. Instead of adding a separate charge applying device, the patent harnesses the inherent electrostatic phenomenon by controlling the grounding state of the fixing member, thereby suppressing offset while simplifying the device structure.
Solution Approach 2:
The fixing member serves dual functions: it performs its primary heating and pressing function while simultaneously generating and utilizing electrostatic charge to suppress toner offset. The ungrounded state of the fixing member allows it to self-charge during operation, eliminating the need for external charging mechanisms.
2Object-affected harmful factors
If a charge applying device is used to suppress electrostatic offset, then offset phenomenon is reduced, but production cost increases
Solution Approach 1:
The invention extracts value from the naturally occurring electrostatic charge on the fixing member rather than requiring additional charging components. By controlling the grounding state, the system utilizes existing electrostatic phenomena to suppress offset, avoiding the need for expensive charge applying devices and their associated maintenance costs.
3Object-affected harmful factors
If the first fixing member is in an ungrounded state, then electrostatic adhesion of toner is suppressed, but device configuration becomes simpler
Solution Approach 1:
The fixing member in an ungrounded state naturally generates and maintains electrostatic charge during operation, which actively suppresses toner adhesion. This self-charging mechanism eliminates the need for separate charging devices, simplifying the overall device configuration while effectively preventing offset.
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
The ungrounded state of the fixing member effectively suppresses electrostatic adhesion of toner, preventing image failure and reducing production costs by simplifying the device configuration, as demonstrated by experiments showing no offset phenomenon even after printing 500 sheets.
Implementation Method 1
With an outer peripheral surface of the first fixing member in a state of being heated to a predetermined temperature
Implementation Method 2
The pressing member presses the first fixing member against the second fixing member so as to form, at a contact portion between the first fixing member and the second fixing member, a nip portion
Implementation Method 3
The first fixing member is in an ungrounded state and comes into contact with a toner image on a sheet
Data Source
AI summary
A fixing device includes a first fixing member, a second fixing member, a pressing member, and a heating device. The first fixing member is in an ungrounded state and comes into contact with a toner image on a sheet. The second fixing member is arranged opposite the first fixing member. The pressing member presses the first fixing member against the second fixing member so as to form, at the contact portion between the first fixing member and the second fixing member, a nip portion through which the sheet passes. The heating device heats the first fixing member.