Segmented Heater for Image Fusing Overheating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image heating apparatuses experience overheating in no-media passage portions, leading to potential damage and toner offset issues, as existing solutions like PTC heating elements do not fully prevent current flow in these areas.
Innovation Solution
The apparatus features a heater with independently controllable heating blocks and a configuration where electrodes are disposed on the back surface, allowing for symmetrical heat generation and reduced electrical resistance, thereby minimizing overheating in no-media passage areas without increasing the heater's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a PTC heating element is used to suppress overheating in no-media passage portions, then the resistance increases with temperature to reduce current flow, but a certain amount of current still flows through the heating element in the no-media passage portion causing insufficient overheating suppression
Solution Approach 1:
The heating element is divided into multiple independent heating sections along the longitudinal direction, each with its own conductors. This segmentation allows independent control of heat generation in different regions, enabling the media passage portion to be heated while the no-media passage portion remains cool, thereby resolving the overheating issue that PTC elements cannot fully address.
Solution Approach 2:
Different regions of the heater are given different functional properties: the media passage portion is designed to generate heat for toner fixation, while the no-media passage portion is designed to minimize heat generation to prevent overheating. This local differentiation of thermal properties solves the contradiction between needing heat where media passes and avoiding heat where media does not pass.
2Object-affected harmful factors
If the heater size is increased to accommodate additional cooling mechanisms or larger PTC elements, then overheating suppression may improve, but the heater size increases which is not desirable
Solution Approach 1:
The heater is segmented into multiple heating sections with independent electrical control along the longitudinal direction. This allows the heater to maintain its original compact size while achieving regional temperature control - the media passage section heats appropriately while the no-media passage section remains cool, eliminating overheating without increasing overall heater dimensions.
3Device complexity
If conventional heating elements are used that heat the entire surface uniformly, then the structure remains simple, but overheating occurs in no-media passage portions where heat is not needed
Solution Approach 1:
The heating element is divided into multiple independent heating sections along the longitudinal direction, each controlled by separate conductors. This segmentation enables selective heating of only the media passage portion while keeping the no-media passage portion cool, solving the overheating problem with minimal increase in structural complexity.
Solution Approach 2:
The heater transitions from static uniform heating to dynamic regional heating control. By independently controlling the electrical supply to different heating sections, the system can adaptively heat only where needed (media passage) and avoid heating where not needed (no-media passage), eliminating overheating while maintaining structural simplicity.
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 overheating in no-media passage portions, preventing damage and toner offset, while optimizing heat distribution and reducing the warm-up time of the heater.
Implementation Method 1
a heating element disposed between the first conductor and the second conductor and configured to generate heat by power supplied thereto via the first conductor and the second conductor
Implementation Method 2
A heating resistor (hereinafter referred to as a 'heating element') on a substrate of a heater is formed of a material having a positive temperature coefficient of resistance. As the temperature of the no-media passage portion increases, the resistance of the heating element in the no-media passage portion increases, suppressing current flowing through the heating element
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
The present invention relates to an image heating apparatus that includes a heater including a plurality of independently controllable heating blocks in a longitudinal direction thereof, each including a first conductor, a second conductor, and a heating element. At least one of electrodes corresponding to the respective heating blocks is disposed in an area where the heating element is located in the longitudinal direction on a second surface of the heater that is opposite to a first surface that comes into contact with an endless belt. An electrical contact is arranged so as to face the second surface of the heater. An overheating occurring in a no-media passage portion when an image formed on a recording material having a small size is heated is suppressed or reduced.