Image-Forming Fixing Heater Power Estimation for Offset Control
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Solution Overview
Problem
Existing image forming apparatuses face challenges in precisely controlling heater temperature due to variations in resistance and voltage, leading to issues such as hot offset and cold offset, which are not effectively addressed by systems lacking voltage or current detection units, resulting in image defects.
Innovation Solution
An image forming apparatus with a temperature detection unit, a control unit, and a storage unit to determine and adjust the energization rate of the heating member based on temperature-rise time periods, estimating maximum power supply to maintain target temperatures and correct for resistance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the heater is energized at the same energization rate, then the control system is simple, but power varies due to variations in resistance or voltage, making it difficult to precisely control the temperature of the heater
Solution Approach 1:
The system performs preliminary action by detecting the temperature-rise time period before adjusting the energization rate. The control unit measures how long it takes for the heater temperature to rise by a predetermined amount, and based on this measurement, proactively adjusts the energization rate to compensate for resistance variations, thereby achieving precise temperature control without complex real-time feedback systems.
Solution Approach 2:
The system implements feedback by using the temperature-rise time period as an indicator of heater resistance changes. The control unit continuously monitors the temperature rise rate and adjusts the energization rate accordingly - when temperature rise is slower than expected (indicating higher resistance), the system increases energization to maintain the target temperature, thus creating a closed-loop control system.
2Measurement precision
If a voltage detection unit or current detection unit is provided for maximum power detection, then the temperature control precision is improved, but the apparatus cost increases
Solution Approach 1:
The system uses temperature-rise time period as an intermediary parameter to indirectly detect heater resistance changes and infer maximum power capabilities. Instead of directly measuring voltage or current, the system measures the temperature rise rate, which serves as a mediator that reflects the actual power delivery condition, thereby achieving accurate temperature control without expensive voltage or current detection units.
Solution Approach 2:
The system replaces the electrical measurement approach (voltage or current detection) with a thermal measurement approach (temperature rise time detection). By substituting the sensing mechanism from electrical domain to thermal domain, the system achieves the same temperature control precision using simpler and less expensive temperature sensors rather than expensive voltage or current detection units.
3Ease of operation
If the heater temperature is not precisely controlled, then the apparatus is simple to operate, but image defects occur such as hot offset or defective fixing
Solution Approach 1:
The system implements self-service by automatically adjusting the energization rate based on detected temperature-rise time periods without requiring user intervention. The control unit autonomously monitors heater performance, detects resistance changes through temperature rise measurements, and self-corrects the energization rate to prevent image defects, maintaining both operational simplicity and image quality.
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 reduces or eliminates image defects by accurately controlling heater temperature, ensuring consistent image quality and reducing the occurrence of hot offset and cold offset.
Implementation Method 1
a heating member configured to heat the fixing member
Implementation Method 2
a temperature detection unit configured to detect a temperature of the heating member
Data Source
AI summary
Disclosed is an image forming apparatus that includes a fixing device including a fixing film, a heater disposed in the fixing film, a temperature detection unit configured to detect a temperature of the heater, and a pressure roller, a controller configured to control a rate of energizing the heater to raise the temperature detected by the temperature detection unit to a target temperature, and a storage unit configured to store temperature-rise time period information of the temperature detection unit. In use, the controller determines a temperature-rise time period of temperature detected by the temperature detection unit while energizing the heater at a predetermined energization rate, compares the determined temperature-rise time period with temperature-rise time period information, estimates maximum power to be supplied to the heater, and modifies, based on the estimated maximum power, the rate of energizing the heater.