Segmented Induction Heating for Fixing Belt Temperature Control
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses face challenges in temperature control, leading to overheating or underheating issues when handling printing sheets of varying widths, resulting in defective fixation and uneven image quality due to the limited heat capacity of the fixing belt and the inefficiency of current heating methods.
Innovation Solution
A fixing device with a separate induction heat unit that divides the fixing belt into sections and integrates multiple heaters within the press roller, using a center coil and side coils for electromagnetic induction heating, along with temperature sensors and a heater control unit to dynamically adjust heating based on the sheet width and temperature readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single heat source is used in the press roller, then the structure is simple, but temperature control precision deteriorates when handling sheets of varying widths
Solution Approach 1:
The press roller heating system is segmented into multiple independent heating zones (first heating zone and second heating zone) along the width direction. Each zone has its own heater that can be independently controlled, allowing precise temperature management for different sheet widths without requiring a completely complex overall structure.
Solution Approach 2:
Different regions of the press roller are provided with different heating characteristics - the first heating zone and second heating zone can be independently adjusted to provide appropriate heat distribution. This local differentiation enables precise temperature control for various sheet widths while maintaining a relatively simple overall heating structure.
2Stability of the object's composition
If the fixing belt has large heat capacity, then temperature stability is improved, but startup heating time increases significantly
Solution Approach 1:
The system performs preliminary heating of the press roller using the first heating zone before the fixing belt requires full temperature. This preliminary action pre-warms the system components, reducing the overall startup time while the fixing belt's heat capacity continues to provide temperature stability during operation.
Solution Approach 2:
The heating system operates in periodic stages - initial heating phase using first heating zone, followed by temperature maintenance phase. This periodic operation allows the fixing belt to gradually accumulate heat, achieving both faster startup and stable operating temperature.
3Loss of time
If induction heating is used for fast heating, then startup time is reduced, but temperature control precision deteriorates due to rapid heating
Solution Approach 1:
The induction heating system is divided into multiple independently controllable heating zones. This segmentation allows the rapid heating capability of induction to be applied locally to specific areas, while the overall temperature distribution is managed through coordinated control of multiple zones, maintaining precision despite speed.
Solution Approach 2:
The heating system dynamically adjusts the power and timing of induction heating in different zones based on real-time temperature feedback and sheet detection. This dynamic control enables the system to exploit the fast response of induction heating while preventing overheating, achieving both speed and precision.
4Device complexity
If heating is applied uniformly across the press roller, then the structure is simple, but temperature uniformity deteriorates when processing small width sheets
Solution Approach 1:
The press roller heating system is segmented into multiple independent heating zones that can be selectively activated. When processing small width sheets, only the necessary heating zones are activated, reducing overall heat input and improving temperature uniformity across the narrower contact area without requiring a completely complex control system.
Solution Approach 2:
The system applies partial heating action by activating only the necessary heating zones based on sheet width detection. This prevents excessive heating in areas outside the sheet contact region, maintaining temperature uniformity across the sheet while keeping the control system relatively simple through selective zone activation.
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 solution ensures precise temperature control across the width of the fixing belt, preventing overheating or underheating, thereby maintaining consistent image quality and reducing the startup time for the image forming apparatus.
Implementation Method 1
a center coil and side coils provided at a center portion and both side portions thereof in terms of a vertical direction with respect to the direction of movement of the printing medium for heating the fixing medium by induction heating
Data Source
AI summary
A fixing device configured to fix a toner image on a moving printing medium includes: a fixing heat generator that generates heat by electromagnetic induction; a fixing medium that rotates and is heated while being carried by the heating medium; and a pressing member that presses a back surface of the printing medium coming into contact with the fixing medium, the fixing heat generator including a center coil and a pair of side coils provided at a center portion and both side portions thereof along a direction perpendicular to the direction of movement of the printing medium for heating the fixing medium by induction heating, the pressing member including a center heater and a side heater that heat a center portion and both side portions thereof in a direction perpendicular to the direction of movement of the printing medium integrated therein.