Planar Heater Sensor Abnormality Detection via Thermal Equalization
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Solution Overview
Problem
The accuracy of abnormality detection in temperature sensors, such as thermistors, is low due to uneven temperature distribution in planar heat generators, leading to erroneous detections and potential overheating issues in inkjet printers using UV ink, which can cause image quality issues and ink deterioration.
Innovation Solution
A heater system with a planar heat generator, a power supply circuit, and multiple temperature sensors that detect abnormality only when a significant temperature difference between sensors exceeds a threshold after a predetermined waiting period following power cessation, improving detection accuracy without increasing threshold values unnecessarily.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple temperature sensors are provided on a planar heat generator to monitor temperature distribution, then the ability to detect abnormality is improved, but false detections increase due to uneven temperature distribution caused by sensor placement positions
Solution Approach 1:
The system performs preliminary action by waiting for a predetermined period after stopping power supply to the heat generator before detecting abnormality. This allows the temperature distribution to equalize across the planar heat generator, eliminating the uneven temperature differences caused by sensor placement positions. The abnormality detection is then performed on equalized temperature data, ensuring accurate detection without false positives.
Solution Approach 2:
The system changes the timing parameter of temperature measurement by performing abnormality detection at a specific time point (after predetermined waiting period) rather than during active heating. This parameter change transforms the temperature distribution state from uneven to equalized, enabling accurate abnormality detection that is not confounded by placement-position-induced temperature differences.
2Measurement precision
If the abnormality threshold value is increased to reduce false detections, then false positives decrease, but the detection capability for actual abnormalities is reduced
Solution Approach 1:
The system performs preliminary equalization of temperature distribution by waiting for a predetermined period after power cessation before performing abnormality detection. This preliminary action ensures that temperature differences are due to sensor abnormalities rather than placement positions, allowing the use of a fixed threshold value without compromising detection capability.
Solution Approach 2:
The system uses multiple temperature sensors to obtain multiple temperature values, then performs abnormality detection based on the relationship between these copied measurements. By comparing temperature values from multiple sensors after equalization, the system can reliably detect abnormalities using a fixed threshold without false positives from placement-position variations.
3Temperature
If power is continuously supplied to the planar heat generator to maintain heating, then the heating function is maintained, but the risk of overheating and fire increases when sensor abnormalities occur
Solution Approach 1:
The system performs periodic abnormality detection after predetermined waiting periods following power supply cessation. This periodic detection approach allows the system to monitor sensor functionality without continuous power supply, reducing overheating risk while maintaining the ability to detect abnormalities when they occur.
Solution Approach 2:
The system uses the temperature sensors to self-diagnose abnormality conditions. When a sensor detects abnormal temperature readings after equalization, the system automatically identifies the faulty sensor and can adjust power supply accordingly, preventing overheating and fire hazards without requiring external monitoring.
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
Enhances the accuracy of abnormality detection in temperature sensors by accounting for initial temperature disparities caused by sensor placement, preventing overheating and maintaining image quality while reducing false positives.
Implementation Method 1
the surface temperature of the rubber heater is measured by a thermistor
Implementation Method 2
The heat generator generates heat when power is supplied
Implementation Method 3
The rubber heater heats the UV ink by conducting heat to the ink through the ink carriage made of metal or the like
Data Source
AI summary
A heater includes: a planar heat generator; a power supply circuit that controls supply of power to the planar heat generator; a plurality of temperature sensors that is provided on the planar heat generator and measures a temperature; and a hardware processor that detects abnormality of the temperature sensor in a case where a difference in temperature measured by each of two of the temperature sensors out of the plurality of temperature sensors exceeds an abnormality threshold value after a predetermined waiting time has elapsed since the supply of power to the planar heat generator is stopped.