Dual-Surface Heater Segmentation for Film Temperature Uniformity
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Solution Overview
Problem
In fixing devices for image forming apparatuses, the use of film with low heat capacity leads to uneven surface temperatures due to differences in thermal resistance paths, resulting in fixing defects when the same target temperature is set for both surfaces of the heater, as the thermal resistance from the heating resistor to the temperature detection unit differs.
Innovation Solution
A fixing device with a heater having separate heat generating segments on each surface, where the temperature detection unit controls power supply to ensure the surface temperature of the film is maintained at a target temperature by adjusting power distribution between the segments based on the size of the recording material, with a higher target temperature set for smaller materials to compensate for thermal resistance differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same target temperature is set for both surfaces of the heater, then the temperature control is simplified, but the surface temperature of the film becomes uneven due to different thermal resistance paths, resulting in fixing defects
Solution Approach 1:
The heater is divided into two separate heat generating segments: a first heat generating segment on the first surface and a second heat generating segment on the second surface. This segmentation allows independent control of heat generation on each side of the heater, enabling compensation for different thermal resistance paths and achieving uniform surface temperature across the film.
Solution Approach 2:
Different target temperatures are set for the first and second heat generating segments based on their respective thermal resistance characteristics. The control unit supplies power to each segment independently, with the second segment receiving higher power when thermal resistance is higher, creating local quality adjustments that result in uniform overall temperature distribution.
2Volume of moving object
If the diameter of the film or roller is decreased to downsize the fixing device, then the device size is reduced, but the width of the heater must be narrowed, making it difficult to maintain adequate heat generation
Solution Approach 1:
Instead of increasing heater width in the lateral dimension to compensate for reduced diameter, the invention utilizes the third dimension by forming heat generating segments on both surfaces of the heater substrate. This allows heat generation capacity to be maintained or increased even when the heater width is narrowed, enabling downsizing of the fixing device while preserving heating performance.
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 ensures consistent surface temperatures on the film for both large and small-size recording materials, preventing fixing defects by optimizing heat generation and distribution, thus maintaining the quality of the toner fixation process.
Implementation Method 1
a heater (12) that contacts the film (11) to heat the film (11), and includes a substrate (301), a first heating resistor (309) formed on a first surface (302) of the substrate (301), and a second heating resistor (305) formed on a second surface (302) of the substrate (301)
Implementation Method 2
a thermistor (14) that detects a temperature of a surface on which the second heating resistor (305) is formed
Data Source
AI summary
A fixing device includes a film, a heater contacting the film which has a substrate, a first heat generating segment on a first surface of the substrate, and a second heat generating segment on a second surface opposite to the first surface, a pressure member forming the nip portion, a temperature detection unit detecting a temperature of the second surface, and a control unit supplying power to the heater so that the detected temperature becomes a target temperature, wherein the control unit can perform a first heater control so as to supply power only to the first heat generating segment, and a first heater control so as to supply power only to the second heat generating segment, and wherein the target temperature during performing the second heater control is higher than the target temperature during performing the first heater control.