Image Heating Apparatus Current Correction for Uniform Startup
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Solution Overview
Problem
The existing image heating apparatuses face challenges in maintaining a uniform temperature distribution along the heating regions during startup, leading to variations in temperature rising speed, which can result in image failures and delayed first print out time (FPOT) due to factors like resistance variations and thermal capacity differences.
Innovation Solution
An image heating apparatus with a substrate-based heater having multiple heat generating elements, temperature detecting portions, and a power supply control system that adjusts current to each element based on detected temperatures, ensuring a uniform temperature rise across regions at the start of the heating operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If power is supplied to multiple heating regions simultaneously during startup, then heating efficiency is improved, but temperature distribution uniformity deteriorates due to variations in temperature rising speed among regions
Solution Approach 1:
The control device detects temperatures from multiple temperature detecting portions corresponding to different heating regions, calculates temperature rising speeds for each region, and uses this feedback information to determine appropriate power supply timing. This feedback mechanism enables the system to adjust power distribution dynamically, supplying power to regions that are heating slower while delaying or reducing power to regions heating faster, thereby maintaining uniform temperature distribution across all heating regions during startup.
Solution Approach 2:
The system transitions from static simultaneous power supply to dynamic adaptive power supply. The control device continuously monitors temperature rising speeds and adjusts power supply timing and magnitude for each heating region based on real-time conditions. This dynamic adjustment allows the system to optimize both heating efficiency and temperature uniformity by adapting power distribution to the actual thermal response characteristics of each region.
2Stability of the object's composition
If power supply timing is adjusted to achieve uniform temperature distribution, then temperature uniformity is improved, but first print out time (FPOT) increases due to delayed heating start
Solution Approach 1:
The control device performs preliminary detection of temperature rising speeds in each heating region during the startup phase. Based on this preliminary information, it pre-calculates and determines the optimal power supply timing for each region before actual heating begins. This preliminary action allows the system to prepare the heating schedule in advance, minimizing delays while ensuring uniform temperature distribution is achieved from the start of the printing process.
Solution Approach 2:
The system changes the power supply parameters (timing, duration, magnitude) for each heating region based on detected temperature rising speeds. By adjusting these parameters dynamically, the system can optimize the heating process to achieve uniform temperature distribution without excessive delay. The control device modifies power supply parameters region-by-region, allowing faster-heating regions to receive delayed or reduced power while faster power is supplied to slower-heating regions, thereby balancing overall heating time and temperature uniformity.
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 reduces temperature variation among heating regions, thereby decreasing FPOT and ensuring a good output image by maintaining a stable temperature distribution during startup.
Implementation Method 1
a heater constituted of a substrate and a plurality of heat generating elements disposed on the substrate in a longitudinal direction of the substrate, and that is configured to heat an image formed on a recording material by using the heat of the heater
Data Source
AI summary
An image heating apparatus includes a heater having a plurality of resistors, and a power supply control circuit that controls power supplied to the plurality of resistors so as to selectively heat a plurality of heating regions. A plurality of thermistors detect a temperature of each of a plurality of regions of the image heater, and a processor functions as a current amount correcting portion that corrects an amount of current supplied to the plurality of resistors. The current amount is corrected based on the temperature detected by each of the plurality of thermistors, so that a difference of a temperature rising amount per unit time among the plurality of heating regions at the start of an image heating operation becomes small and a total amount of power supplied to the plurality of heat generating elements is kept to within a predetermined limited power amount.