Fixing Heater Layout for Earlier Overheat Detection in Image Forming
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Solution Overview
Problem
Existing fixing devices fail to timely detect abnormal temperature rises in the small heat distributed area, leading to potential breakdown due to excessive heating.
Innovation Solution
A fixing device with a heater divided into short and long regions, where temperature detection members are strategically placed to monitor and control temperature, including a heat source detection member in the short region and a power interrupting member in the long region, ensuring timely detection and prevention of excessive heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the end-side thermistor is provided in the small heat distributed area to detect the temperature inside the fixing device, then the temperature detection capability is improved, but the detection timing is delayed because the temperature in the small heat distributed area rises later than in the large heat distributed area
Solution Approach 1:
A heat conduction member is introduced as an intermediary between the heater and the temperature detection member. This heat conduction member rapidly conducts heat from the heater to the temperature detection member, enabling timely temperature detection without being constrained by the heat distribution characteristics of the original heater structure. The heat conduction member acts as a thermal bridge that overcomes the delay in temperature rise in the small heat distributed area.
2Area of stationary object
If the heater has a large heat distributed area to provide sufficient heating, then the heating coverage is improved, but the temperature control precision deteriorates because the temperature distribution becomes non-uniform
Solution Approach 1:
The heating system is segmented into multiple independent heating zones with separate heating elements. Each heating zone can be independently controlled to maintain uniform temperature distribution across the large heat distributed area. The temperature detection member is positioned to monitor the temperature in each zone, enabling precise control of each segment while maintaining overall large-area heating capability.
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 solution effectively prevents damage from excessive heating by timely detection and control, maintaining optimal temperature for proper fixing processes and reducing downtime.
Implementation Method 1
The heat generating part is formed at a position shifted in one direction from a center in the axial direction on one surface of the substrate facing the pressure region, and generates heat when being powered
Implementation Method 2
The heat source temperature detection member detects a temperature of the heater
Data Source
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AI summary
A fixing device (7) includes a fixing belt (20), a pressure member (21), a heater (22), and a heat source temperature detection device (41). The heater (22) includes a substrate (30) and a heat generating part (31). The substrate (30) extends in an axial direction of the fixing belt (20). The heat generating part (31) is formed at a position shifted in one direction from a center in the axial direction on one surface of the substrate (30) facing the pressure region. The heater (22) is divided into a short region (B1) having a shorter length in the axial direction and a long region (B2) having a longer length in the axial direction by the center of the heat generating part (31) in the axial direction as a boundary. The heat source temperature detection member (41) is disposed in the short region (B1) of the heater (22) .