Rotating Fixing Roller Power Interruption via Magnetic Coupling
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Solution Overview
Problem
Conventional fixing devices with resistive heat layers face issues in reliably interrupting power supply to prevent overheating, as high current flow can cause mechanical switches to melt, preventing effective temperature control and potentially leading to apparatus breakdown.
Innovation Solution
A fixing device with a heat generating rotational body and a pressing rotational body forms a fixing nip, featuring power non-receivers on edge portions of the heat generating rotational body, power receivers on the outer circumference, and a controller that rotates the heat generating body to align the power non-receiver with power feeding members to interrupt power supply when a predetermined condition is met, avoiding the use of mechanical switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical switch is used to interrupt power supply to the resistive heat layer, then power supply interruption is achieved, but the mechanical switch may melt due to high current flow
Solution Approach 1:
The patent extracts the power interruption function from a mechanical switch and implements it through a contactless method. A non-conductive portion on the rotating member interrupts the magnetic coupling between the stationary magnet and the rotating coil, eliminating the need for mechanical switches that are susceptible to melting from high current.
Solution Approach 2:
The patent replaces the mechanical switch system with a magnetic coupling system. Power is transmitted wirelessly from the stationary magnet to the rotating coil, and interruption is achieved by blocking the magnetic field path rather than by mechanical contact, thereby avoiding mechanical wear and melting issues.
2Use of energy by moving object
If power supply is continuously maintained to the resistive heat layer, then heating efficiency is high, but temperature control becomes difficult when overheating occurs
Solution Approach 1:
The patent implements automatic temperature control through feedback. The temperature sensor continuously monitors the heat generating rotational body's temperature and signals the controller. When the temperature exceeds the predetermined threshold, the controller interrupts power supply by rotating the heat generating rotational body to align the non-conductive portion with the power feeding member, thereby preventing overheating.
Solution Approach 2:
The patent prepares for potential overheating by pre-positioning a non-conductive portion on the heat generating rotational body. This preliminary arrangement allows for rapid power interruption without requiring mechanical switches or complex control mechanisms during the actual temperature emergency.
3Device complexity
If a mechanical switch is used for power interruption, then the structure is simple, but the switch remains on after melting during normal operation
Solution Approach 1:
The patent replaces the mechanical switch with a magnetic field-based power transmission system. The stationary magnet and rotating coil create a magnetic coupling for contactless power transfer. Interruption is achieved by rotating the coil or magnet to break the magnetic coupling, eliminating the reliability issue of mechanical switches remaining closed after melting.
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 allows for reliable interruption of power supply to the resistive heat layer, preventing overheating and reducing the risk of mechanical switch failure, thus ensuring safe and efficient temperature management.
Implementation Method 1
directly supplying power to the resistive heat layer and causing the resistive heat layer to generate Joule heat
Data Source
AI summary
The present invention provides a fixing device that can interrupt power supply to the resistive heat layer more reliably than the conventional technology, for example, at occurrence of abnormality. Electrodes 52a and 52b are provided on a circumferential surface of a fixing roller that includes a resistive heat layer that generates heat by receiving power supply, and power is supplied to the resistive heat layer when power supplying electrodes 54a and 54b that are electrically connected to an electric power source 55 are slidingly in contact with the electrodes 52a and 52b. An insulating tape 522a is attached on the electrode 52a, and the drive controller 59 rotates a motor 58 until the electrode 52a and the insulating tape 522a are in contact with each other, so that power supply to the resistive heat layer is interrupted.