Fixing Heater Temperature Control With Sensor Fault Detection
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Solution Overview
Problem
Existing temperature control devices for image forming apparatuses struggle to accurately determine abnormalities in temperature sensors or control circuits, leading to potential failures in maintaining optimal temperature settings for fixing devices.
Innovation Solution
A temperature control device that includes a heater power supply circuit, a temperature sensor, a control signal generation circuit, a temperature estimation circuit, and a temperature abnormality detection circuit. This device compares the current temperature difference between the detected temperature and the estimated WAE temperature value with threshold values to determine if there is an abnormality in the temperature sensor or on the circuit side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the temperature control device uses simple threshold comparison for abnormality detection, then the detection process is simple and fast, but the accuracy in determining whether the abnormality is in the temperature sensor or control circuit is insufficient
Solution Approach 1:
The abnormality detection is segmented into multiple stages: first comparing detected temperature with target temperature to identify abnormality occurrence, then comparing temperature difference with threshold values to locate the abnormality source (sensor vs. circuit). This segmentation allows accurate diagnosis without requiring complex diagnostic systems.
Solution Approach 2:
The system performs preliminary temperature comparison to detect abnormality occurrence before performing detailed threshold comparison to locate the abnormality source. This preliminary action structure enables systematic diagnosis flow, improving detection accuracy while maintaining simple comparison operations at each stage.
2Reliability
If the temperature control device continuously monitors and compares temperature values with threshold, then the reliability of temperature control is improved, but the computational load and processing time increase
Solution Approach 1:
The system performs partial monitoring by only initiating detailed threshold comparison when the detected temperature deviates from the target temperature. This partial action approach maintains high reliability for abnormality detection while avoiding continuous full-scale processing, thereby reducing unnecessary computational load and processing time.
3Measurement precision
If the temperature control device uses multiple threshold values for different abnormality levels, then the detection precision is improved, but the control system becomes more complex
Solution Approach 1:
The temperature difference analysis is segmented into multiple precision levels using different threshold values. The first threshold detects general abnormality, while the second threshold provides finer localization precision. This segmentation achieves high measurement precision through simple comparative operations rather than complex control circuitry.
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
The proposed solution enables effective detection of temperature sensor and circuit abnormalities, ensuring that the fixing device operates within the desired temperature range and preventing potential failures.
Implementation Method 1
a heater power supply circuit that supplies power to a heater of the fixing device
Implementation Method 2
The temperature sensor detects a surface temperature of the heat roller
Implementation Method 3
controlling a temperature control target to which heat is propagated from the heater
Data Source
AI summary
A device to supply power to a heater of a fixing device with a heater power supply circuit configured to supply power to the heater; a temperature sensor to measure a detected temperature from the temperature control target; a temperature estimation circuit to estimate an estimated temperature value of the temperature control target by the detected temperature; a control signal generation circuit to output a control signal for controlling the power supplied by the heater power supply circuit based on the estimated temperature value of the temperature control target estimated by the temperature estimation circuit and the target temperature; and a temperature abnormality detection circuit to determine whether an abnormality exists in the temperature sensor or on a circuit side based on a comparison result of the detected temperature acquired by the temperature sensor and the estimated temperature value.