Heat Roller Temperature Control via Sensor-Based Estimation
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Solution Overview
Problem
Image forming apparatuses face challenges in detecting and controlling the surface temperature of portions of the heat roller not facing the print medium, leading to uneven heating and prolonged processing times due to the limited number of temperature sensors, which affects the quality of toner image fixation on larger sheets like A4 portrait sheets.
Innovation Solution
A control device with multiple heaters arranged along the conveyance path, including a center heater and side heaters, and a temperature sensor, which uses a control circuit to estimate and correct temperatures, and adjust the energizing pulses to ensure proper temperature control and conveyance speed based on the estimated temperatures, allowing for efficient temperature management without the need for extensive temperature sensor coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single temperature sensor is used to detect heat roller surface temperature, then the cost is reduced and the structure is simplified, but the temperature distribution uniformity deteriorates because the sensor cannot detect temperatures at all positions
Solution Approach 1:
The patent uses a single temperature sensor to detect temperature at one position, then copies this measurement data to represent and control temperatures at other positions through computational modeling. The system creates virtual temperature measurements for undetected positions based on the actual sensor reading and heat transfer calculations, enabling control without physical sensors at all locations.
Solution Approach 2:
The patent replaces the mechanical approach of using multiple physical temperature sensors with a computational system that uses mathematical models and algorithms to estimate temperatures. The control circuit performs heat transfer calculations and temperature distribution modeling to substitute for the function of multiple sensors, reducing hardware complexity while maintaining control precision.
2Manufacturing precision
If the conveyance speed is reduced to prevent excessive heating of the heat roller, then the temperature uniformity is improved, but the processing time increases
Solution Approach 1:
The patent implements dynamic control of the conveyance speed based on real-time temperature measurements and predictive modeling. Instead of using a fixed low speed for all conditions, the system dynamically adjusts the speed according to the detected temperature and calculated heat distribution, allowing faster conveyance when temperatures are appropriate and slower conveyance when cooling is needed, thus optimizing both temperature uniformity and processing time.
Solution Approach 2:
The patent employs a feedback control mechanism where the temperature sensor continuously monitors heat roller surface temperature, and the control circuit uses this feedback to adjust both the heater output and conveyance speed. The system calculates the temperature distribution based on sensor readings and feeds this information back to modify operating parameters, creating a closed-loop control system that maintains temperature uniformity while minimizing processing time.
3Temperature
If the heater output is increased to maintain target temperature at the sensor position, then the temperature at the sensor location is maintained, but the temperature at other positions becomes excessively high
Solution Approach 1:
The patent applies local quality control by calculating and controlling heater output based on the specific thermal characteristics of different positions on the heat roller. The system determines the appropriate heater power by considering the local heat dissipation conditions at each position, using the temperature sensor reading combined with heat transfer models to adjust heating locally rather than applying uniform heating across the entire roller surface.
Solution Approach 2:
The patent introduces computational modeling and heat transfer calculations as an intermediary between the temperature sensor measurement and the heater control. Rather than directly controlling the heater based solely on sensor reading, the system uses thermal models to predict temperature distribution and determine the appropriate heater output that will achieve target temperatures without causing excessive heating at other positions.
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 enables precise temperature control across the heat roller, preventing excessive heating and reducing processing time by allowing for dynamic adjustment of print speed based on temperature estimates, thereby improving the quality and efficiency of the printing process.
Implementation Method 1
a heating member (e.g., heater)
Implementation Method 2
The temperature sensor detects the surface temperature of the heat roller
Implementation Method 3
a fixing device that fixes a toner image on a print medium by applying heat and pressure to the print medium
Data Source
AI summary
A control device for controlling heat applied to a medium conveyed along a path, includes: first and second heaters arranged along a first direction crossing the path, the first heater overlapping the medium and the second heater not overlapping the medium when viewed in a direction crossing the path and the first direction; a sensor; and a circuit configured to determine estimated temperatures of the heaters based on power supplied thereto, determine a corrected temperature of the first heater based on the estimated temperature thereof and a temperature measured by the sensor, determine a corrected temperature of the second heater based on the estimated temperature thereof and the corrected and estimated temperatures of the first heater, energize the heaters based on the corrected temperatures, and issue a command for controlling a conveying speed based on the corrected temperature of the second heater.