Eccentric Cam Fixing Device Nip Pressure Control
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses cannot effectively restrain the overrunning of the eccentric cam, leading to impulsive sounds during the changing operation of nip pressure between the heating and pressuring rollers.
Innovation Solution
The fixing device incorporates an eccentric cam with a rotating shaft, tensile springs, and a gear train, where the eccentric cam's posture is changed to adjust the nip pressure, and a protrusion on the shaft prevents overrunning by engaging with an inclined face, reducing the likelihood of impulsive sounds through the use of a coil spring and pin mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the following member is allowed to overrun the driving member with predetermined play, then the pressure contact state of the fixing film and pressuring roller can be released, but impulsive sound occurs due to overrunning
Solution Approach 1:
The patent introduces a buffering member that provides predetermined play between the driving member and following member, allowing controlled overrun while cushioning the impact. This buffering mechanism prevents direct hard contact during pressure release, thereby reducing impulsive sound generation while maintaining operational functionality.
Solution Approach 2:
The patent introduces a cam mechanism as an intermediary between the driving member and following member. The cam face guides the following member through a controlled motion path during pressure release, mediating the transition and preventing direct abrupt contact that would generate impulsive sound.
2Object-generated harmful factors
If the following member is restrained from overrunning, then impulsive sound is reduced, but the pressure release function is compromised
Solution Approach 1:
The buffering member is designed with predetermined play that allows the following member to overrun the driving member in a controlled manner. This cushioning mechanism permits the pressure release function to occur while preventing excessive overrun that would generate impulsive sound.
Solution Approach 2:
The patent changes the parameter of play distance between the driving member and following member by introducing the buffering member. This controlled parameter adjustment allows sufficient overrun for pressure release while limiting it to prevent impulsive sound generation.
3Adaptability or versatility
If the eccentric cam is rotated to change nip pressure, then pressure adjustment is achieved, but overrunning causes impulsive sound
Solution Approach 1:
The buffering member provides predetermined play that cushions the overrun of the eccentric cam during rotation. This allows the cam to change nip pressure effectively while preventing abrupt contact that would generate impulsive sound during pressure adjustment operations.
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 restrains the overrunning of the eccentric cam, minimizing impulsive sounds and ensuring smooth operation by maintaining contact with the inclined face, thus enhancing the reliability and quietness of the fixing device.
Implementation Method 1
The tensile spring is connected between the first supporting body and the second supporting body at its both ends to pull the first supporting body to a side of the second supporting body
Implementation Method 2
The eccentric cam is rotatably supported at a position between the first supporting body and the second supporting body in the lateral plate, in which a through hole and a depression having an inclined bottom face along a circumference direction are formed, comes into contact with the roller and is rotated in a positive rotation direction to change a posture of the second supporting body
Implementation Method 3
The driving part includes a gear train connected to the rotating shaft to transmit torque rotating the eccentric cam to the rotating shaft and a driving source driving the gear train
Implementation Method 4
The protrusion is fixed to the rotating shaft, is in a protrusion direction of a diameter direction of the rotating shaft and comes into contact with the bottom face
Data Source
AI summary
A fixing device includes a heating body, a pressuring body, a lateral plate supporting the heating or pressuring body, a first supporting body supporting the heating or pressuring body, a second supporting body including a roller, a tensile spring between the first and second supporting bodies, an eccentric cam, a rotating shaft, a protrusion, a driving part, and a pressing member. The cam is supported between the first and second supporting bodies swingable in the lateral plate and has a depression gradually inclined from an upstream side to a downstream side in a rotation direction. The protrusion is protruded from the rotating shaft and meets the depression. The pressing member presses the cam opposite the protrusion. The cam rotates and meets the roller to shift the second supporting body and to extend and contract the spring, and changes a nip pressure from a first pressure to a lower second pressure.