Heating Roller Temperature Sensor Positioning for Orientation-Dependent Convection
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Solution Overview
Problem
Image forming apparatuses, especially electrophotographic devices, face challenges in precisely controlling the temperature of heating rollers when changed from a horizontal to an upright position due to changes in air convection patterns affecting non-contact temperature sensors.
Innovation Solution
The temperature detector is positioned above the horizontal plane passing through the rotational axis of the heating roller in both orientations, ensuring smooth heat conduction and precise temperature detection, with optional switching mechanisms and correction tables for different orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the image forming apparatus is placed in the upright position to save space, then the installation space requirement is reduced, but the temperature detection precision of the heating roller deteriorates due to changed air convection patterns
Solution Approach 1:
The patent applies the dynamics principle by making the temperature sensor's detection point movable relative to the heating roller. The sensor can switch between a first detection point (above the heating roller) and a second detection point (at a different position), allowing the system to adapt its detection configuration based on the apparatus orientation to maintain measurement precision in both horizontal and upright positions
Solution Approach 2:
The patent applies parameter changes by modifying the detection point position parameter of the temperature sensor. By changing which detection point is active (first or second), the system adjusts the sensor's spatial relationship to the heating roller, compensating for orientation-induced convection changes and maintaining accurate temperature detection
2Device complexity
If the temperature sensor is positioned beside the rotational center for compact design, then the device complexity is reduced, but the temperature detection precision deteriorates when the apparatus is in the upright position
Solution Approach 1:
The patent applies segmentation by dividing the temperature detection function into multiple detection points (first detection point and second detection point). Each detection point is optimized for specific orientation conditions, allowing the system to segment the detection task across different spatial locations rather than relying on a single fixed sensor position
3Measurement precision
If correction coefficients are modified to compensate for orientation changes, then the temperature control accuracy may be improved, but the device complexity increases due to multiple correction tables
Solution Approach 1:
The patent applies dynamics by implementing a switchable correction coefficient system. Rather than maintaining multiple independent correction tables, the system dynamically selects and switches between different correction coefficients based on the detected apparatus orientation, achieving accurate temperature control while simplifying the management of correction data through automated switching logic
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 approach allows for precise surface temperature detection and adjustment of the heating roller regardless of the apparatus's orientation, maintaining accurate temperature control and fixing performance.
Implementation Method 1
the temperature of the circumferential surface of the heating roller is detected with a temperature sensor such as a thermistor located near the circumferential surface, without contact with the circumferential surface
Implementation Method 2
such a non-contact temperature sensor is generally configured to detect the temperature of the conductive heat due to the natural convection of the air existing between the heating roller and the temperature sensor
Data Source
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AI summary
An image forming apparatus that is orientatable in either a first position or a second position, the second position being different from the first position in inclination with respect to a horizontal plane, comprising: a fixing unit (30) that includes a heating roller (31) and a pressurizing member (32), presses the pressurizing member (32) against a surface of the heating roller (31) to form a fixing nip, and thermally fixes a toner image formed on a recording sheet passing through the fixing nip; at least one temperature detector (34) that detects temperature of the surface of the heating roller (31) without contact with the surface; a heater (33) that applies heat to the heating roller (31); and a controller (50) that controls the heater (33) according to the temperature detected by the at least one temperature detector (34), and thereby controls the temperature of the surface of the heating roller (31), characterised in that: a detection point of the at least one temperature detector (34) is located above a horizontal plane passing through a rotational axis of the heating roller (31) regardless of whether the image forming apparatus is in the first position or in the second position.