Heating Belt Temperature Control via Cantilevered Leaf Spring
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Solution Overview
Problem
Existing image heating apparatuses face challenges in maintaining consistent surface temperature of external heating belts during contact and retreat positions, leading to potential fixation failures, especially when using cardstock as the recording medium, due to variations in temperature detection by thermistors.
Innovation Solution
The apparatus incorporates a thermistor placement mechanism that ensures consistent temperature detection by positioning the thermistor to maintain contact with the external heating belt in a manner that minimizes positional deviations, using a cantilevered leaf spring to maintain contact with the belt's surface, and employing a moving mechanism to adjust the belt's tension and contact position, ensuring accurate temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the external heating belt is placed in contact with the fixation roller to heat the roller, then the heating performance is improved, but the thermistor contact position with the external heating belt changes, causing temperature detection accuracy to deteriorate
Solution Approach 1:
A pressing member is introduced as an intermediary component between the thermistor and the external heating belt. This pressing member maintains constant contact pressure on the thermistor, ensuring stable temperature detection regardless of whether the external heating belt is in contact with or retreated from the fixation roller. The pressing member acts as a mediator that isolates the thermistor from the positional changes caused by the heating belt's movement.
Solution Approach 2:
The pressing member is positioned beforehand to apply constant pressure on the thermistor, cushioning against the potential loss of contact or variable contact that would occur when the external heating belt moves. This pre-applied pressure ensures the thermistor maintains reliable contact with the heating belt in both contact and retreated positions, preventing temperature detection inaccuracies before they can occur.
2Force
If the supporting rollers are made movable to provide tension to the external heating belt, then the belt tensioning is improved, but the thermistor contact position varies, causing temperature measurement precision to deteriorate
Solution Approach 1:
The pressing member serves as a mediator between the movable supporting rollers and the thermistor. While the supporting rollers move to adjust belt tension, the pressing member ensures the thermistor maintains stable contact with the external heating belt, isolating the measurement system from the mechanical movements of the tensioning mechanism.
Solution Approach 2:
The pressing member is positioned in advance to apply constant pressure on the thermistor, cushioning against the effects of supporting roller movement. This ensures that even when the supporting rollers move to provide belt tension, the thermistor's contact position remains stable and accurate.
3Duration of action of moving object
If the external heating belt is retreated from the fixation roller, then the heating cycle is completed, but the thermistor contact position changes significantly, causing temperature detection to become unreliable
Solution Approach 1:
The pressing member acts as a mediator that maintains thermistor contact stability throughout the entire heating cycle, including during the retreat phase. While the external heating belt retreats from the fixation roller, the pressing member ensures the thermistor remains in consistent contact with the belt, preventing detection reliability issues.
Solution Approach 2:
The pressing member is positioned beforehand to apply constant pressure on the thermistor, cushioning against the contact position changes that occur during belt retreat. This pre-applied pressure ensures continuous reliable temperature detection throughout the complete heating cycle, including the retreat phase.
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 maintains the surface temperature of the external heating belt close to the target level in both contact and retreat positions, preventing 'hot offset' and ensuring reliable fixation of toner images, even with cardstock, by accurately controlling the belt's temperature and reducing temperature detection deviations.
Implementation Method 1
a thermistor for detecting the temperature of the external heating belt
Implementation Method 2
using a cantilevered leaf spring to maintain contact with the belt's surface
Data Source
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AI summary
An image heating apparatus includes first and second rollers; an external heating unit including a heating belt, first and second belt supporting rollers for urging the belt toward the first roller, an urging member for urging the first supporting roller away from the second supporting roller, a holder for the first and second supporting rollers and for permitting movement of the first supporting roller relative to the second supporting roller, and a temperature sensor, provided interposing the belt between itself and the first supporting roller; and a moving mechanism for moving the unit between a first position where the belt contacts the first roller and a second position where the belt does not. The temperature sensor is disposed such that when a detected temperature at a predetermined position between the first position and the second position is higher than those at the first position and the second position.