Dual Heater Image Heating Apparatus for Sheet Size Adaptation
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Solution Overview
Problem
Image heating apparatuses with heating films face inefficiencies when handling small sheets of recording medium, as the portions outside the sheet path unnecessarily increase in temperature due to uneven heat distribution.
Innovation Solution
The apparatus employs two elongated heat generating elements with different heat generation patterns, where the ratio of heat generation at the end portions to the central portion is adjusted by a controller to match the size of the recording material, ensuring efficient heat distribution and minimizing temperature increase outside the sheet path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single heat generating element is used to heat the rotatable member, then the structure is simple, but the heat distribution is uneven when handling small sheets of recording medium, causing unnecessary temperature increase outside the sheet path
Solution Approach 1:
The single heat generating element is divided into two separate heat generating elements (first and second heat generating elements). Each element can be independently controlled to generate heat at different rates, allowing the system to match the heat distribution pattern to the size of the recording medium being processed. This segmentation enables selective heating of only the regions that come into contact with small sheets, preventing unnecessary temperature rise in areas outside the sheet path.
Solution Approach 2:
Different regions of the heater are assigned different heat generation characteristics. The first heat generating element is designed with a heat generation pattern suitable for larger sheets, while the second heat generating element has a heat generation pattern optimized for smaller sheets. By selecting and activating only the appropriate element based on sheet size, the system provides localized heat quality that matches the actual processing requirements, avoiding uniform overheating of the entire heater surface.
2Loss of energy
If the heater portions outside the sheet path are reduced in heat generation to prevent unnecessary temperature increase, then energy efficiency improves, but the overall heating capability may be insufficient for larger sheets
Solution Approach 1:
The system dynamically selects which heat generating element to activate based on the detected size of the recording medium. When small sheets are detected, only the second heat generating element is activated, reducing energy consumption. When large sheets are detected, the first heat generating element is activated to provide sufficient heating capability. This dynamic adaptation ensures that the heater always operates at the minimum necessary power level while maintaining adequate heating performance for the current task.
Solution Approach 2:
The system changes the operational parameters of the heat generating elements based on sheet size detection. By switching between different heat generating elements with different heat generation patterns, the system adjusts the thermal parameters to match the processing requirements. This parameter change allows the same physical heater structure to provide different heating characteristics, optimizing both energy efficiency and heating capability for different sheet sizes.
3Adaptability or versatility
If multiple heat generating elements with different heat generation patterns are used, then heat distribution can be optimized for different sheet sizes, but the device complexity increases
Solution Approach 1:
The heater is segmented into two distinct heat generating elements, each with a specific heat generation pattern optimized for different sheet sizes. This segmentation provides the adaptability to handle various sheet sizes effectively. The complexity is managed by keeping each segment relatively simple and using a selection mechanism rather than attempting to create a single complex element that could adapt to all conditions.
Solution Approach 2:
The dual-element heater structure serves multiple functions: it can handle both small and large sheets of recording medium, providing universal adaptability. Rather than requiring separate heating systems for different sheet sizes, this multi-functional heater uses two elements that can be selectively activated. The complexity is justified by the versatility gained, as the same heater structure replaces what would otherwise require multiple specialized heating systems.
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 effectively reduces unnecessary temperature increases in the heating apparatus, maintaining optimal heat levels for fixing toner images on various sheet sizes, preventing unsatisfactory fixation and hot offset issues.
Implementation Method 1
a first heat generating element and a second heat generating element, for heating said rotatable member
Data Source
AI summary
An image heating apparatus includes: a rotatable member; and a first heater and a second heater, for heating the rotatable member. The ratio of the second-heater heat generation amount at an end portion thereof to that at a central portion thereof is larger than that of the first heater at an end portion thereof to that at a central portion thereof with respect to the longitudinal direction. The apparatus also includes: a back-up member; a sensor; and an electric power supply controller capable of controlling the heaters independently. The controller effects switching to decrease the ratio of the power to the second heater to the power to the first heater, when heating a small width sheet. Immediately after the switching, the power to the second heater is smaller and the power to the first heater is larger than those immediately before the switching.