Temperature Abnormality Detection Circuit for Fixing Device Control
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Solution Overview
Problem
Existing temperature control devices for image forming apparatuses face challenges in accurately determining abnormalities in temperature sensors or control circuits, leading to inefficiencies in maintaining optimal temperature settings and potentially causing equipment failures.
Innovation Solution
A temperature control device incorporating a heater power supply circuit, temperature sensor, control signal generation circuit, temperature estimation circuit, and temperature abnormality detection circuit, which uses weighted average control to estimate temperatures and compare detected temperatures with threshold values to identify abnormalities, distinguishing between sensor and circuit issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the detected temperature exceeds a preset range, the existing system determines there is an abnormality in the fixing device and checks for breakage of the temperature sensor or heat source, but this approach cannot accurately distinguish between sensor abnormalities and circuit abnormalities
Solution Approach 1:
The abnormality detection function is segmented into two independent detection circuits: a temperature sensor abnormality detection circuit that specifically detects sensor failures, and a general abnormality detection circuit that detects circuit failures. This segmentation allows each circuit to specialize in detecting specific types of abnormalities, improving detection accuracy without requiring a single complex detection system to handle all cases.
Solution Approach 2:
The temperature sensor abnormality detection circuit acts as an intermediary that processes temperature sensor signals before they reach the general abnormality detection circuit. By filtering out sensor-specific abnormalities first, the general detection circuit can focus on circuit-level abnormalities, preventing false positives and improving overall detection precision.
2Reliability
If the system checks for multiple types of abnormalities (sensor breakage, heat source breakage, wiring abnormalities, control circuit abnormalities), then the coverage of abnormality detection is improved, but the time required for diagnosis and the complexity of the detection process increases
Solution Approach 1:
The detection system is divided into parallel detection pathways: the temperature sensor abnormality detection circuit immediately identifies sensor-specific issues, while the general abnormality detection circuit simultaneously checks for other abnormalities. This parallel segmentation allows multiple types of abnormalities to be detected concurrently rather than sequentially, reducing diagnosis time while maintaining comprehensive coverage.
Solution Approach 2:
The temperature sensor abnormality detection circuit performs preliminary detection of sensor-specific abnormalities before the general abnormality detection process begins. By identifying sensor issues first, the system prevents unnecessary further diagnosis steps for sensor-related problems, thereby reducing overall diagnosis time while maintaining comprehensive abnormality coverage.
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 enables precise detection of temperature abnormalities, ensuring accurate temperature control and preventing equipment failures by differentiating between sensor and circuit-related issues, thus enhancing the reliability and efficiency of the image forming process.
Implementation Method 1
The temperature sensor detects a surface temperature of the heat roller
Implementation Method 2
The fixing device includes a rotating body for fixing (heat roller), a pressure member (press roller), a heating member (lamp or IH heater, and the like)
Data Source
AI summary
According to one embodiment, there is provided a temperature abnormality detection circuit provided in a temperature control device includes a target temperature determination circuit, a difference arithmetic circuit, a temperature abnormality determination circuit, and a storage circuit. The temperature abnormality detection circuit is configured to determine the presence or absence of temperature abnormality by a response situation of a detected temperature by a temperature sensor, calculate a current temperature difference from the detected temperature acquired by the temperature sensor if it is determined that there is a temperature abnormality and an estimated WAE temperature value, and determine whether the temperature sensor is abnormal or the control circuit side is abnormal based on the result of comparison between the temperature difference and a preset threshold value.