Fixing Unit Heater Layout for Thermal Expansion Stability
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Solution Overview
Problem
Existing fixing units face issues with positional deviation and deformation of heat conducting members due to thermal expansion, which can lead to damage and reduced fixing performance.
Innovation Solution
A fixing unit design featuring a heater with protrusions that extend towards the heater holder, positioning the heat conducting member between these protrusions to restrict its movement in the longitudinal direction, allowing thermal expansion without deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the heat conducting member is fitted to the heater or support member using bent portions or grooves, then positional deviation is suppressed, but the heat conducting member may be deformed or damaged due to excessive thermal expansion
Solution Approach 1:
The heater is divided into multiple independent heating elements arranged in the longitudinal direction. Each heating element can expand independently without causing excessive stress on the heat conducting member, as the expansion is distributed across multiple segments rather than concentrated in a single fitted structure.
Solution Approach 2:
The fitting structure (bent portions or grooves) is removed from the heat conducting member. Instead of fitting the heat conducting member to the heater, the patent positions the heat conducting member between protrusions that extend from the heater toward the heat conducting member, allowing thermal expansion without deformation.
2Measurement precision
If the heat conducting member is subjected to bending processing or punching processing to create fitting structures, then positioning is achieved, but the heat conducting member may be deformed or damaged when thermally expanding due to residual stress
Solution Approach 1:
Instead of creating fitting structures on the heat conducting member through bending or punching, the patent inverts the approach by providing protrusions on the heater that extend toward the heat conducting member. This eliminates the need for complex processing of the heat conducting member while achieving the same positioning effect.
Solution Approach 2:
The complex bending and punching processing steps are removed from the manufacturing process. The positioning function is achieved through the protrusions on the heater rather than through fitted structures on the heat conducting member, simplifying manufacturing.
3Stability of the object's composition
If the heat conducting member is tightly fitted to restrict movement, then positional deviation is prevented, but thermal expansion causes excessive stress and deformation
Solution Approach 1:
The protrusions are positioned at specific locations that extend from the heater toward the heat conducting member, providing localized positioning without complete restriction. This allows the heat conducting member to expand thermally while maintaining positional stability through the strategically placed protrusions.
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
The design effectively prevents deformation and damage to the heat conducting member while maintaining stable fixing performance, ensuring accurate and reliable toner fixation on sheets.
Implementation Method 1
a heating element provided on the substrate and configured to heat the rotary member by being energized
Implementation Method 2
when the temperature of the bent portion or the groove of the heat conducting member becomes high, excessive thermal expansion may occur
Implementation Method 3
a heat conducting member having high heat conductivity is attached to a surface of the heater opposite to the surface contacting the film, and the heat conducting member levels out the temperature of the heater in the longitudinal direction
Data Source
AI summary
A fixing unit includes a rotary member, a pressure member configured to form a fixing nip, a heater disposed in an internal space of the rotary member, the heater including a substrate, and a heating element provided on the substrate and configured to heat the rotary member by being energized, a heater holder configured to hold the heater, and a heat conducting member disposed between the heater and the heater holder. The fixing nip conveys the sheet in a direction parallel to a short direction perpendicular to a longitudinal direction of the heater. The heater includes a protrusion extending toward the heater holder from a surface, of the heater, provided on a side opposite to the fixing nip. The protrusion faces the heat conducting member in the longitudinal direction and is disposed so as not to overlap the heat conducting member as viewed in the short direction.