Fixing Device Heat Generation Member Switching
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Solution Overview
Problem
In high-speed image forming apparatuses, the switching of heat generation members during printing reduces throughput due to the need for extended sheet intervals to complete the switching operation, leading to a decrease in productivity.
Innovation Solution
A fixing device with multiple heat generation members of different lengths, where the control unit switches the power supply path to the shorter heat generation member during continuous printing when the recording material is nipped in the nip portion, allowing for efficient switching without interrupting the heating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat generation member is switched during printing to prevent temperature increase in non-sheet-passing portions, then the temperature control is improved, but the sheet interval needs to be extended to complete the switching operation, which reduces throughput
Solution Approach 1:
The heat generation member is divided into multiple segments (first heat generation member and second heat generation member) with different lengths. This segmentation allows selective activation of appropriate segments based on sheet size, enabling temperature control without requiring full shutdown and switching of a single long heater, thus reducing the impact on throughput.
Solution Approach 2:
The system dynamically selects which heat generation member to activate based on the detected sheet size. When a small-sized sheet is detected, the system switches to the second heat generation member with length matching the sheet size, while the first heat generation member remains inactive. This dynamic adaptation eliminates the need for extended sheet intervals.
2Reliability
If the switching relay contact is switched after stopping power supply to avoid contact sticking, then the reliability of switching relay is improved, but the temperature of fixing device components decreases during switching operation, which may affect fixing quality
Solution Approach 1:
The system performs preliminary detection of sheet size before the switching operation. By detecting the sheet size in advance and pre-planning which heat generation member to activate, the system can execute the switching operation smoothly without abrupt temperature changes, maintaining component temperature while ensuring reliable switching relay operation.
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 prevents productivity reduction by enabling seamless switching of the power supply path, maintaining fixability and increasing output speed while preventing image degradation and deformation of the fixing device components.
Implementation Method 1
a heater having at least a first heat generation member and a second heat generation member
Implementation Method 2
an unfixed toner image borne on a recording material is fixed with heat in the nip portion
Data Source
AI summary
The fixing device includes a film that is heated by a heater having at least two heat generation members, a pressure roller that forms a fixing nip portion together with the film, a heat generation member switching device that switches a power supply path for supplying power to the at least two heat generation members; and a CPU that controls the heat generation member switching device. In continuous printing on small-size sheets, the CPU causes, while a small-size sheet is held in the fixing nip portion N, the heat generation member switching device to start the operation of switching the power supply path so that power is supplied to one of the at least two heat generation members.