Fixing Belt Push Pad Arc Geometry for Nip Stability
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Solution Overview
Problem
Conventional heat roller fixing types in electro-photographic image forming apparatuses suffer from low heat transmission efficiency, leading to high power consumption and long warmup times, and face issues with paper curl and jamming due to the shape of the fixing nip portion, while belt fixing types struggle with maintaining nip width and paper separation performance.
Innovation Solution
A fixing device using an endless fixing belt with a heat portion, a pressure roller, and a push member, where the push pad has a flat portion and an arc-shaped portion with a larger radius than the pressure roller, allowing the pressure roller to butt the arc-shaped portion via the fixing belt to form a fixing nip portion, ensuring efficient heat transfer and paper separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a heat roller fixing type is used with a halogen lamp heat source, then the fixing function is achieved, but heat transmission efficiency is low and power consumption is large
Solution Approach 1:
The patent replaces the conventional thermal conduction heating method with infrared radiant heating. The infrared heater emits infrared rays that directly heat the fixing belt through radiation, eliminating the need for thermal conduction through roller walls and significantly improving heat transmission efficiency. This substitution of heating mechanism reduces energy loss and power consumption while maintaining effective fixing temperature.
Solution Approach 2:
The patent utilizes the phase transition properties of toner (from solid to melted state) at the fixing temperature. The infrared heating system is designed to rapidly raise the fixing belt temperature to the toner melting point, enabling efficient toner fixation. The direct radiant heating accelerates the thermal process required for toner phase transition, reducing warmup time and energy consumption.
2Temperature
If a heat roller fixing type is used, then the fixing function is achieved, but it takes a long time for the roller surface to reach fixing temperature
Solution Approach 1:
The patent replaces conventional thermal conduction heating with infrared radiant heating. The infrared heater directly radiates heat to the fixing belt surface, which has much faster heating response compared to thermal conduction through roller walls. This substitution dramatically reduces the warmup time required to reach fixing temperature.
Solution Approach 2:
The infrared heating system operates with periodic control to rapidly achieve the required fixing temperature. The system can quickly cycle the heater on and off to maintain optimal temperature, reducing the overall warmup time compared to conventional gradual heating methods.
3Ease of operation
If the fixing belt is directly driven by rotating push members inside the belt, then the fixing function is achieved, but it is hard to freely set the shape and width of the nip portion
Solution Approach 1:
The patent extracts the push members from inside the fixing belt and relocates them to the outside. This allows the push members to freely adjust the nip portion shape and width without being constrained by the internal belt structure. The external positioning of push members provides design freedom while simplifying the overall drive mechanism.
Solution Approach 2:
The push members are designed to be adjustable and dynamic, allowing free setting of the nip portion shape and width according to different printing requirements. The external push members can be positioned and adjusted independently, providing flexibility in configuring the fixing system for various paper sizes and types.
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 enhances heat efficiency, reduces power consumption, maintains nip width, and secures paper separation performance over the device's lifespan by minimizing deformation and maintaining the shape of the fixing nip portion.
Implementation Method 1
an endless fixing belt which absorbs radiant light from a heat generation source and generates heat
Implementation Method 2
the belt support member and the inside surface of the fixing belt are slid by using frictional force between the pressure roller and the outer surface of the fixing belt
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A fixing device (13) includes: a fixing belt (21); a heat portion (25); a pressure roller (23); a push member (22) that pushes the fixing belt (21) against the pressure roller (23); and a push pad (40) that is disposed on a surface of the push member (22) that opposes the fixing belt (21). A slide surface (40a) of the push pad (40) has a flat portion (41) substantially parallel to a convey direction of the recording medium and an arc-shaped portion (43) that bends toward the pressure roller (23) in a more downstream side than the flat portion (41) in the recording medium convey direction, the arc-shaped portion (43) includes a radius R2 of curvature larger than a radius R1 of curvature of the pressure roller (23) and a center 02 of curvature that is situated in a more upstream side than a straight line which passes a center O1 of curvature of the pressure roller (23) and is perpendicular to the recording medium convey direction.