Fixing Device Nip Forming Member Geometry
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Solution Overview
Problem
Existing fixing devices with thin, energy-efficient belts are prone to damage or breakage due to hard contact with nip forming members during high-speed rotation, especially when reduced in thickness for energy conservation and reduced warm-up times.
Innovation Solution
A fixing device configuration with a nip forming member having a longer upstream portion and shorter downstream portion, supported by a reinforced stay with elongated arms, guides the fixing belt into the nip portion, reducing friction and contact stress, and includes a halogen heater for direct heating of the belt, minimizing heat capacity and enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the fixing belt is reduced in thickness to reduce heat capacity and warm-up time, then energy consumption and first-print time are improved, but the belt becomes more prone to damage or breakage due to hard contact with the nip forming member
Solution Approach 1:
A guide member is introduced as an intermediary component between the fixing belt and the nip forming member. This guide member has a contact surface that guides the fixing belt into the nip portion, preventing direct hard contact between the thin fixing belt and the nip forming member. The guide member absorbs the mechanical stress and protects the thin belt from damage while maintaining the reduced thickness design for fast heating.
2Use of energy by moving object
If the fixing belt is reduced in thickness to reduce heat capacity, then energy consumption is reduced, but the belt strength is reduced making it more susceptible to damage
Solution Approach 1:
The guide member serves as a protective intermediary that compensates for the reduced belt strength. By providing a gentle guiding surface, it prevents the thin belt from experiencing concentrated stress points that would cause damage, thereby enabling the use of thinner, more energy-efficient belts without sacrificing reliability.
Solution Approach 2:
The guide member's contact surface is designed with specific geometric parameters (radius, length, position) that optimize the distribution of mechanical stress. The contact surface extends in the sheet feeding direction and has a controlled radius that ensures smooth belt entry into the nip, reducing stress concentration on the thin belt structure.
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 prevents belt damage, improves mechanical strength, and reduces energy consumption while maintaining efficient first-print times and image quality by stabilizing the belt's entry into the nip portion and optimizing heat transfer.
Implementation Method 1
a plate-shaped nip forming member 500 provided at a position facing the pressure roller 400. In this case, a portion of the endless belt 100 other than a portion of the endless belt 100 contacting the nip forming member 500 is directly heated by the heat source 300
Implementation Method 2
the metal heat conductor 200 guides the movement of the endless belt 100. Further, the endless belt 100 is heated, via the metal heat conductor 200, by the heat source 300 inside the metal heat conductor 200. Thereby, the entire endless belt 100 is heated.
Data Source
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AI summary
A fixing device (20) for fixing an image on a recording medium (P) includes an endless fixing rotary member (21) which is formed into a loop and comes into contact with the image on the recording medium, an opposed rotary member (22) which is in contact with the fixing rotary member, a nip forming member (24) provided inside the loop of the fixing rotary member to be in contact with the opposed rotary member via the fixing rotary member to form a nip portion to which the recording medium is fed in a feeding direction, a support member (25) which supports the nip forming member, and a heating source (23) which heats the fixing rotary member. The nip forming member includes a downstream portion extending downstream in the feeding direction from a center of the nip portion and an upstream portion extending upstream in the feeding direction from the center and longer than the downstream portion.