NTC Heater Resistor Segmentation for Commercial Power Compatibility
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Solution Overview
Problem
Image heating apparatuses in electrophotographic devices experience non-sheet-passing-portion temperature rise issues, leading to potential part deterioration and high-temperature offset, which existing technologies with negative temperature coefficient (NTC) resistors fail to adequately suppress, especially when using commercial power sources.
Innovation Solution
An image heating apparatus with an elongated substrate featuring two parallel heat-generating lines of NTC resistors connected in series, allowing for efficient heat distribution and resistance adjustment to suppress non-sheet-passing-portion temperature rise, utilizing ruthenium oxide and silver/palladium as electroconductive components to achieve a suitable resistance value for commercial power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a heat-generating resistor with NTC characteristic is formed in a linear hand-like shape on the ceramic substrate, then the heater can be used with commercial power sources, but it is difficult to obtain the resistance in the usable range
Solution Approach 1:
The heat-generating resistor is divided into three or more portions along the longitudinal direction of the substrate, with each portion having a specific resistance value. These divided portions are electrically connected in series to achieve a total resistance value suitable for commercial power sources (100V or 200V), while maintaining the NTC characteristic for temperature control.
2Reliability
If the heat-generating resistor is divided into three or more portions connected in series, then the resistance value is in the usable range for commercial power sources, but the non-sheet-passing-portion temperature rise is not adequately suppressed
Solution Approach 1:
The resistor portions are non-uniformly arranged along the longitudinal direction of the substrate, with different numbers of resistor portions distributed in different regions. Specifically, the sheet-passing portion has a different number of resistor portions compared to the non-sheet-passing portion, enabling localized temperature control to suppress non-sheet-passing-portion temperature rise while maintaining overall resistance suitability for commercial power sources.
3Adaptability or versatility
If paper with width smaller than maximum-sized paper is passed through the fixing device, then small-sized paper can be processed, but non-sheet-passing-portion temperature rise occurs accelerating part deterioration
Solution Approach 1:
The non-uniform arrangement of resistor portions creates different heat generation characteristics in different longitudinal regions of the heater. When small-sized paper is processed, the reduced sheet-passing portion allows adequate heating of the paper, while the non-sheet-passing portion generates less heat due to fewer resistor portions, thereby suppressing temperature rise and preventing part deterioration.
4Temperature
If the non-sheet-passing-portion temperature is excessively increased, then the heater can maintain high temperature for image fixation, but deterioration of parts in the fixing device is accelerated
Solution Approach 1:
By arranging different numbers of resistor portions in different longitudinal regions, the heater achieves localized temperature control. The sheet-passing portion maintains high temperature for effective image fixation, while the non-sheet-passing portion has reduced heat generation to prevent excessive temperature rise that would accelerate part deterioration, thereby extending the service life of fixing device components.
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 suppresses non-sheet-passing-portion temperature rise, ensuring the apparatus operates within the range of commercial power sources while maintaining the necessary heat-fixing properties, thus preventing part deterioration and offset.
Implementation Method 1
a first heat generating line provided on the substrate along a longitudinal direction of the substrate, the first heat generating line including a plurality of first heat-generating resistors having a negative temperature coefficient of resistance
Implementation Method 2
heat-generating resistors having a negative temperature coefficient of resistance
Data Source
AI summary
An image heating apparatus includes: an endless belt; a heater, contacted to a surface of the endless belt, provided so that a longitudinal direction thereof is parallel to a generating line direction of the endless belt; and a pressing member for forming a nip together with the endless belt. The heater includes: an elongated substrate; a first heat generating line, provided on the substrate along a longitudinal direction of the substrate, including first heat-generating resistors having a negative temperature coefficient of resistance and being electrically connected in series; and a second heat generating line, provided on the substrate along the longitudinal direction of the substrate, electrically connected to the first heat generating line in parallel. The second heat generating line includes a plurality of second heat-generating resistors having the negative temperature coefficient of resistance and being electrically connected in series.