Heater Electrode Contact Design for Thermal Expansion
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Solution Overview
Problem
In image forming apparatuses, the end-portion temperature rise during continuous feeding of small-size sheets of paper can damage components like rollers and heaters, and the reliability of electrical contacts is compromised due to thermal expansion and differing linear expansion coefficients between the heater and holder members, leading to unstable electrical connections and wear.
Innovation Solution
The design incorporates a heater with multiple heat generating elements and electrodes arranged orthogonally to the paper conveyance direction, along with a connector system featuring elastically deformable contact portions that maintain contact with the electrodes at different positions, reducing the risk of sliding and improving reliability by accommodating thermal expansion and alignment changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the electrode width is shortened to reduce heater width and heat capacity, then the first printout time is reduced, but it becomes difficult to ensure space for arrangement of multiple contacts for one electrode
Solution Approach 1:
The electrical contact member is divided into multiple elastically deformable portions (first, second, third, fourth portions) that can be independently arranged to contact the electrode at different positions. This segmentation allows multiple contact points to be implemented within a compact width, maintaining reliable electrical connection while accommodating the shortened electrode geometry
Solution Approach 2:
The elastically deformable portions are arranged in the longitudinal direction of the electrode rather than only in the width direction. This dimensional reorganization allows multiple contacts to be distributed along the length of the electrode, effectively utilizing available space and enabling reliable electrical connection even when the electrode width is reduced
2Adaptability or versatility
If the heater and holder member have different linear expansion coefficients, then thermal expansion causes relative displacement between heater and holder member, but this leads to sliding between electrode and contact portion
Solution Approach 1:
The contact portions are designed to be elastically deformable rather than rigid, allowing them to dynamically adjust their position in response to thermal expansion and contraction of the heater. This elasticity enables the contact portions to follow the electrode's movement caused by temperature changes, maintaining continuous electrical connection without sliding or disconnection
Solution Approach 2:
The design explicitly accounts for differential thermal expansion between the heater and holder member by providing elastically deformable contact portions that can accommodate the resulting relative displacement. The contact portions are positioned and dimensioned to allow for expansion-induced movement while maintaining reliable electrical contact throughout the thermal cycle
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 effectively suppresses sliding between the heater electrodes and connectors, enhances the reliability of electrical contacts, and extends the lifespan of printers and copiers by maintaining stable connections despite thermal changes and mechanical stress.
Implementation Method 1
the power supplied from the electrodes on the substrate is supplied to the plurality of heat generating elements arranged on the substrate via the conductor on the substrate in the longitudinal direction, so that the heat generating elements on the substrate generate heat
Implementation Method 2
provides an elastically deformable portion obtained by processing a metal plate of, for example, copper on the electrical contact member, and presses the elastically deformable portion against the electrode to provide a contact
Data Source
AI summary
An image heating apparatus including: a heater including heat generating elements, and electrodes electrically connected to the heat generating elements, respectively and arranged in an orthogonal direction of a conveyance direction of a recording material; and connectors for supplying electric power to electrodes, wherein the connectors include contact portions that come into contact with one of the electrodes, a first supporting portion that supports a first contact portion, and a second supporting portion that supports a second contact portion, the first supporting portion and the second supporting portion are arranged to be spaced apart from each other in the orthogonal direction, the first contact portion extends in a direction toward the second supporting portion, the second contact portion extends in a direction toward the first supporting portion, and the first contact portion and the second contact portion are in contact with the one of the electrodes at different positions.