Fixing Apparatus Heater Thermal Conductive Member
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Solution Overview
Problem
Existing fixing apparatuses for image forming devices face issues with temperature imbalance in the heater, leading to potential damage and fixation failures when handling both small and large sheets of recording media, and there is a risk of short-circuiting patterned electrical wires due to the placement of thermally conductive members.
Innovation Solution
A fixing apparatus with a thermally conductive member positioned on the substrate opposite to the heat generating resistor, ensuring it contacts the patterned electrical wires without short-circuiting them, and extending from the end of the heat generating resistor towards the center to maintain even temperature distribution across the heater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermally conductive member is placed on the heater substrate to prevent excessive temperature increase in out-of-path portions, then temperature balance is improved, but the risk of short-circuiting patterned electrical wires increases
Solution Approach 1:
The patent applies local quality by making the thermally conductive member electrically insulative only in the specific region where it contacts the patterned electrical wires, while maintaining thermal conductivity in other areas. This is achieved by forming an insulative coating (such as resin or ceramic) selectively on the portions of the thermally conductive member that contact the electrical wires, allowing temperature balance to be maintained without causing short-circuits.
2Manufacturing precision
If the heater is designed to maintain uniform temperature across the substrate, then fixation quality is improved, but the complexity of temperature control increases
Solution Approach 1:
The patent applies self-service by using the thermally conductive member to automatically redistribute heat from the heat generating resistor to the out-of-path portions of the heater substrate. This passive thermal conduction mechanism eliminates the need for additional active temperature control systems (such as separate heating elements or complex control algorithms), thereby maintaining uniform temperature distribution while avoiding increased system complexity.
3Temperature
If a metallic plate is placed in contact with the heater substrate to improve thermal conductivity, then heat distribution is improved, but the cost of assembly increases due to additional components
Solution Approach 1:
The patent applies merging by integrating the thermally conductive member as part of the heater assembly structure itself, rather than using a separate metallic plate component. The thermally conductive member is formed as a substantially planar structure that is substantially in contact with the heater substrate, combining the thermal conduction function with the structural support function, thereby improving heat distribution while reducing assembly complexity and cost.
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 prevents excessive temperature increase in out-of-path portions of the heater, maintains balanced temperature distribution, and avoids short-circuiting of electrical wires, ensuring reliable fixation of toner images on large sheets and preventing temperature reduction at the end portions of the heater.
Implementation Method 1
a heater (52) including a substrate (52a) and a heat generating resistor (52b) provided on the substrate (52a)
Implementation Method 2
a thermally conductive member (54) positioned on the substrate (52a) opposite to the heat generating resistor (52b)
Data Source
AI summary
An image fixing device including a cylindrical film, a heater, and a heat conduction member. The cylindrical film is contactable with toner unfixed on a sheet. The heater includes a substrate and a heat generating resistor provided on the substrate. The heat conduction member has a thermal conductivity higher than that of the substrate and is on a side of the substrate opposite from the heat generating resistor. The substrate is provided with non-insulating wiring patterns on a side opposite from the side provided with the heat generating resistor with respect to a direction perpendicular to a recording material feeding direction. The heat conduction member is in contact with one of the wiring patterns and is in contact with the substrate from a position of the substrate outside of an end of the heat generating resistor toward a central portion.