Temperature Control Device for Image Forming Apparatus
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Solution Overview
Problem
Temperature control in image forming apparatuses is compromised due to detection inaccuracies caused by deformation, foreign matter, or contamination of the temperature sensor, leading to abnormal temperature readings and potential overheating of the heat roller.
Innovation Solution
A temperature control device employing weighted average control (WAE control) that estimates the heat roller's temperature based on its heat capacity and resistance, input energy, and detected temperature, allowing for real-time correction of target temperatures to maintain accurate heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensor is used to detect the heat roller surface temperature, then temperature control can be performed, but detection accuracy deteriorates due to sensor deformation, foreign matter, or contamination
Solution Approach 1:
The patent introduces a thermal diffusion model as an intermediary computational framework that bridges the heating member power input and the heat roller surface temperature. Instead of relying solely on direct sensor measurement, the system calculates temperature through thermal diffusion equations that model heat transfer from the heating member through the heat roller material, providing an alternative temperature estimation path that is immune to sensor contamination issues
Solution Approach 2:
The patent replaces the mechanical/direct contact temperature sensing approach with a computational thermal diffusion model. By substituting the physical sensor measurement system with a mathematical model that calculates temperature based on heating power, material properties, and thermal conductivity, the system eliminates the vulnerability to sensor deformation and contamination while maintaining temperature detection capability
2Productivity
If the detected temperature is abnormal (lower than actual), then temperature control continues without correction, but the heat roller temperature exceeds the target value causing image defects
Solution Approach 1:
The patent implements a dual-feedback mechanism where the thermal diffusion model continuously calculates expected temperature based on heating power input and material properties, then compares this calculated temperature with the target temperature. When deviations are detected, the system adjusts the heating power accordingly, creating a closed-loop control system that corrects temperature errors before they cause image defects
Solution Approach 2:
The patent performs preliminary temperature calculation and correction before the abnormal temperature causes image defects. By continuously monitoring the thermal diffusion model output and adjusting heating power in advance, the system prevents temperature excursions that would lead to poor image quality, rather than reacting after damage occurs
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
Prevents image defects by ensuring the heat roller operates within the correct temperature range, even when the temperature sensor detects inaccuracies, thereby maintaining print quality and preventing overheating.
Implementation Method 1
a heating member (a lamp, an IH heater, or the like)
Implementation Method 2
The temperature sensor detects a temperature of a surface of the heat roller
Data Source
AI summary
An image forming apparatus, temperature control method, and temperature control device are provided. The apparatus includes the device, which acquires a first temperature difference between a temperature estimation value of a fixer, which is obtained by simulating a member temperature of a temperature control target serving as a heat capacitor-resistor circuit at an initial stage of operation of the fixer, and a detected temperature detected by a temperature sensor, and acquires a second temperature difference between a temperature estimation value of the fixer, which is obtained during an operation after the first temperature difference is acquired, and a detected temperature. The device calculates a difference between the first temperature difference and the second temperature difference, determines that the detected temperature is abnormal in response to the difference being equal to or greater than a threshold value, and performs temperature control for correcting a target temperature of the member temperature.