Induction Heating Belt Temperature Detection via Intermediary Sensor
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Solution Overview
Problem
Existing image heating apparatuses using electromagnetic induction for fixing images on recording media face challenges in detecting abnormal temperature increases in the fixation belt, leading to potential thermal damage due to delayed detection and uneven thermal capacity distribution, which compromises safety and efficiency.
Innovation Solution
An image heating apparatus with a magnetic flux generating means outside the belt, temperature detecting elements positioned across the belt from the flux generating means, and electric power shut-off mechanisms to quickly interrupt power supply in case of abnormal temperature readings, ensuring early detection and prevention of excessive temperature rises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the coil is disposed to straddle the area between one end of the belt loop and the other end of the belt loop, then the belt heating area is widened and warmup time is reduced, but the temperature detection capability is compromised because thermistors can only be disposed in the adjacencies of the belt nip
Solution Approach 1:
A temperature detecting element is introduced as an intermediary component positioned between the coil and the belt, specifically disposed in the area where the coil opposes the belt. This mediator enables direct temperature measurement in the heat generation area without interfering with the coil's heating function or requiring relocation of the thermistors to suboptimal positions.
2Device complexity
If thermistors are disposed in the adjacencies of the belt nip, then the structure is simplified, but the temperature of the heat generation area cannot be detected promptly leading to delayed anomaly detection
Solution Approach 1:
The patent replaces the conventional thermistor-based temperature detection system with a non-contact temperature detecting element that uses optical or electromagnetic fields to measure temperature. This substitution eliminates the need to physically position sensors in the belt nip area, maintaining structural simplicity while achieving accurate real-time temperature monitoring in the heat generation area.
3Ease of operation
If the fixation belt is not rotated and electric power supply to the coil goes out of control, then the portion of the belt opposing the coil abnormally increases in temperature causing thermal damage, but there is no mechanism to prevent this
Solution Approach 1:
A feedback control system is implemented where the temperature detecting element continuously monitors the temperature in the area where the coil opposes the belt, and this temperature information is fed back to the control unit. The control unit uses this feedback to automatically interrupt electric power supply to the coil when abnormal temperature increase is detected, preventing thermal damage while maintaining operational simplicity.
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 effectively suppresses early-stage excessive temperature increases, enhancing the safety and efficiency of the image heating process by promptly detecting and addressing anomalies, thereby preventing thermal damage and ensuring consistent image fixation.
Implementation Method 1
magnetic flux generating means, disposed outside of the belt, for generating heat in the belt by a magnetic flux
Implementation Method 2
heating method based on electromagnetic induction, which directly heats a heating member of the heating apparatus
Data Source
AI summary
An image heating apparatus includes an endless belt for heating an image on a recording material; a plurality of supporting members on which the belt is trained; magnetic flux generating means, disposed outside of the belt, for generating heat in the belt by a magnetic flux, the magnetic flux generating means being effective to cause induction heating both in a region of the belt between the supporting members and in at least one of the regions of the belt trained on the supporting members; a temperature detecting element for detecting a temperature of the belt in the region between the supporting members at a position across the belt from the magnetic flux generating means; and electric power supply shut-off means for shutting off electric power supply to the magnetic flux generating means on the basis of an output of the temperature detecting element.