Heater with Independent Heat-Generation Lines for Image Heating
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Solution Overview
Problem
Existing heater configurations for image forming apparatuses face challenges in simultaneously suppressing non-sheet-passing portion temperature rise and maintaining fixability, leading to reduced throughput when trying to control heat-generation distributions.
Innovation Solution
A heater with a substrate featuring a first heat-generation line and a second heat-generation line, where the first line has a heat-generation distribution that decreases in lengthwise direction and the second line has a distribution that increases, both with positive resistance-temperature characteristics and connected in parallel, allowing independent control to manage heat generation effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If more power is supplied to the first heat-generation line to suppress non-sheet-passing portion temperature rise, then the temperature rise of non-sheet-passing region is suppressed, but the fixability of end portion of sheet-passing region is lowered
Solution Approach 1:
The patent applies local quality by creating distinct heat-generation characteristics in different regions of the heater. The first heat-generation line has resistance decreasing from center to ends (higher heat at ends), while the second heat-generation line has resistance increasing from center to ends (higher heat at center). This allows localized heat generation to be optimized for different functional requirements: end regions for preventing temperature rise and central regions for ensuring fixability.
Solution Approach 2:
The heater is segmented into two independent heat-generation lines with different resistance distributions. The first heat-generation line (with electrodes 12a, 12b and resistors 14a, 14b) and the second heat-generation line (with electrodes 12c, 12d and resistors 14c, 14d) can be controlled independently through separate power supply circuits, allowing differential power control to simultaneously address non-sheet-passing portion temperature suppression and sheet end fixability.
2Reliability
If more power is supplied to the second heat-generation line to improve fixability of sheet end portion, then the fixability is improved, but the temperatures of non-sheet-passing portion region will rise
Solution Approach 1:
The second heat-generation line is designed with resistance increasing from center to ends, creating higher heat generation at the central region where sheet passing occurs. This localized heat concentration improves fixability at sheet ends while the first heat-generation line simultaneously manages temperature at non-sheet-passing portions through its opposite resistance distribution.
Solution Approach 2:
By segmenting the heater into two independently controllable heat-generation lines with complementary resistance distributions, the system can allocate power dynamically: the second line provides enhanced heating for sheet fixability while the first line compensates by controlling temperature rise in non-sheet-passing regions.
3Reliability
If processing is performed to lower throughput to simultaneously secure fixability and suppress temperature rise, then both fixability and temperature control are achieved, but productivity is reduced
Solution Approach 1:
The patent changes the electrical parameters (resistance distribution) of the heat-generation lines to achieve optimal heat generation patterns. By varying resistance along the length of each line and controlling power supply parameters independently, the system achieves both temperature control and fixability without requiring throughput reduction.
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 configuration effectively inhibits non-sheet-passing portion temperature rise while maintaining fixability, enhancing the overall performance of the image heating device.
Implementation Method 1
a plurality of heat-generation resistors having positive resistance-temperature characteristics and electrically connected in parallel between the first electro-conductive element and the second electro-conductive element
Data Source
AI summary
In order to suppress excessive temperature rise at a non-sheet-passing region while suppressing the deterioration of fixability in case of heating small size sheets, a heater includes a first heat-generation line and a second heat-generation line, which are independently controllable, wherein the first heat-generation line is configured so that a plurality of heat-generation resistors having positive resistance-temperature characteristics is electrically connected in parallel to each other between a first electro-conductive element and a second electro-conductive element, and the heat-generation resistors are adjusted so that a heat-generation amount per unit length of the first heat-generation line in a lengthwise direction of the heater decreases from a recording material conveyance reference towards a end portion in the lengthwise direction, and an image heating device having the heater.