Heating Member Temperature Control in Image Forming Fixing Devices
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Solution Overview
Problem
Image forming apparatuses face challenges in controlling the heating member's temperature during start-up, leading to excessive or insufficient heating, which affects the warming-up period and lifespan of components, due to instability in ambient temperature and inaccurate temperature measurement by non-contact sensors.
Innovation Solution
An image forming apparatus with a non-contact temperature sensor that commences measuring after a waiting period, an acquiring unit that records heating conditions, and a fixing control unit that performs temperature control based on estimated temperatures to prevent overheating and ensure efficient warming-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If temperature control is performed using a non-contact temperature sensor during the waiting period, then the warming-up period can be shortened, but the temperature measurement accuracy deteriorates due to unstable ambient temperature
Solution Approach 1:
The system performs preliminary temperature measurement before the waiting period to acquire initial temperature information. This preliminary action allows the control unit to estimate temperature during the waiting period without relying on unstable ambient temperature readings, thus shortening the warming-up period while maintaining measurement accuracy.
Solution Approach 2:
The control unit acts as an intermediary by estimating the heating member's temperature during the waiting period based on the relationship between power supply amount and temperature, rather than directly measuring with the non-contact sensor. This mediation avoids the measurement accuracy problem caused by unstable ambient temperature while still enabling temperature control.
2Speed
If heating is performed at high power during the waiting period, then the warming-up speed increases, but the risk of excessive temperature and thermal degradation increases
Solution Approach 1:
The system dynamically adjusts the power supply amount to the heating member based on the estimated temperature and the relationship between power and temperature. During the waiting period, the control unit can safely apply higher power to accelerate warming-up, then transitions to precise control once the non-contact sensor begins measuring, thus optimizing both warming-up speed and preventing thermal degradation.
Solution Approach 2:
The control unit uses feedback from the relationship between power supply amount and temperature to control the heating process. By monitoring how temperature responds to power changes, the system can adjust power levels to achieve fast warming-up while preventing excessive temperature and thermal degradation of components.
3Measurement precision
If a contact temperature sensor is used to measure heating member temperature, then the measurement accuracy improves, but the lifespan of the sensor decreases due to friction and toner attachment
Solution Approach 1:
The control unit serves as an intermediary by estimating temperature based on power supply relationships rather than requiring direct physical contact measurement. This allows the system to use a non-contact temperature sensor that does not suffer from friction and toner attachment problems, thereby maintaining measurement capability while extending sensor lifespan.
Solution Approach 2:
The patent replaces the mechanical contact-based temperature measurement system with a non-contact optical measurement system (non-contact temperature sensor). This substitution eliminates the mechanical friction and toner attachment issues that reduce contact sensor lifespan, while the control unit compensates for measurement limitations through estimation algorithms.
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 precise temperature control of the heating member, reducing waiting times and preventing thermal degradation, thus enhancing the efficiency and lifespan of the apparatus.
Implementation Method 1
a non-contact temperature sensor configured to commence measuring temperature of the heating member once a waiting period of a certain length has passed after power supply commences to the fixing device
Implementation Method 2
a fixing device configured to thermally fix, through use of a heating member, an unfixed image formed on a recording sheet
Data Source
AI summary
An image forming apparatus includes a non-contact temperature sensor that commences measuring temperature of a heating member in a fixing device once a waiting period of a certain length has passed after power supply commences to the fixing device, and acquires information indicating a heating condition of the heating member when the fixing device transitions to a non-power supplied state. Once the waiting period has passed, the apparatus controls to increase the heating member temperature to a target temperature, while monitoring the heating member temperature using the non-contact temperature sensor. During the waiting period, the apparatus estimates the heating member temperature at a present time using the information, and controls to increase the heating member temperature when the estimated temperature does not exceed a threshold temperature, and prevent increase of the heating member temperature when the estimated temperature exceeds the threshold temperature.