Fixing Device Coil Extension for End Heat Uniformity
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses, such as electrophotographic copiers and printers, face inefficiencies in heat generation at the end portions of rotating members, where the amount of generated heat is insufficient, due to reduced magnetic flux contributing to heat generation.
Innovation Solution
A fixing device is designed with a cylindrical rotating member featuring an electrically conductive layer, a magnetic member inside the rotating member, and a coil wound around it. An alternating current is applied to induce a current in the conductive layer, generating heat, and the magnetic member and coil extensions beyond the rotating member's ends to optimize magnetic flux distribution, enhancing heat generation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the coil and magnetic member are limited to the length of the rotating member, then the device structure is compact, but heat generation at end portions is insufficient
Solution Approach 1:
The patent applies local quality by extending the coil and magnetic member beyond the rotating member's end portions specifically to address the heat generation deficiency at end portions. This localized extension ensures that the end portions receive sufficient magnetic flux and generated heat, while the central portions maintain their原有的 heating characteristics, thus resolving the temperature non-uniformity without requiring a complete redesign of the entire device structure.
Solution Approach 2:
The patent implements preliminary action by pre-extending the coil and magnetic member beyond the rotating member's boundaries before operation. This preliminary structural arrangement ensures that magnetic flux is adequately distributed to the end portions from the outset, preventing heat generation insufficiency before it occurs and eliminating the need for compensatory measures during operation.
2Use of energy by moving object
If alternating current frequency is increased to improve heat generation efficiency, then heat generation improves, but energy loss increases
Solution Approach 1:
The patent applies parameter changes by optimizing the alternating current frequency within the specific range of 20.5 kHz to 100 kHz. This parameter optimization balances heat generation efficiency with energy loss considerations, identifying a frequency range where the rotating member effectively generates heat through electromagnetic induction while minimizing excessive energy losses associated with higher frequencies.
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 improves heat generation efficiency at the end portions of the rotating member, ensuring effective heat fixation of images on recording media by optimizing magnetic flux distribution and reducing heat generation inefficiencies.
Implementation Method 1
an alternating current is caused to flow through the coil so as to induce a current in the electrically conductive layer
Implementation Method 2
the induced current causes the electrically conductive layer to generate heat
Implementation Method 3
the induced current causes the electrically conductive layer to generate heat
Implementation Method 4
improving heat generation efficiency by reducing the magnetic flux not contributing to the heat generation by the rotating member and increasing the magnetic flux contributing to the heat generation
Data Source
AI summary
In a fixing device, an alternating current is caused to flow through a coil so as to causes an electrically conductive layer of a rotating member to generate heat, and an unfixed image on a recording medium is heat fixed onto the recording medium by the heat generated by the electrically conductive layer. A frequency range of the alternating current is from 20.5 kHz to 100 kHz. With respect to a generatrix direction of the rotating member, a magnetic member and a spirally shaped portion of the coil have lengths, with which the magnetic member and the spirally shaped portion extend beyond both end portions of the rotating member.