Cam-Gear Transmission Layout for Low-Backlash Press Switching
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Solution Overview
Problem
Existing drive transmission devices for image forming apparatuses face challenges in maintaining reliable engagement of gears when changing between pressure-release and pressed states, leading to increased backlash and noise due to the deformation of elastic layers and the need for increased rigidity, which results in larger and more costly units with potential mounting obstructions.
Innovation Solution
A drive transmission device featuring a first gear with teeth modifications for enhanced engagement, a cam system to change the state of two members between pressed and pressure-released states, and a second gear with specific tooth configurations to reduce backlash and noise, ensuring smooth transitions and reliable drive transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure-releasing cam is rotated in advance by the pressure from the pressure changing device when changing from pressure-released state to pressed state, then the rotational force of the cam is received reliably, but a force for outwardly moving the mounting and demounting unit generates, causing large impact noise due to play of the drive transmitting gears
Solution Approach 1:
The gear teeth are differentiated into two types: first teeth with standard thickness for regions where the cam rotates in advance, and second teeth with reduced thickness for the engaging region. This local differentiation allows the gear to have sufficient strength where needed while reducing mass and moment of inertia in the engaging region, thereby reducing impact noise during state transitions.
Solution Approach 2:
The tooth thickness parameter is changed based on the functional region of the gear. By reducing the tooth thickness of the second teeth in the engaging region compared to the first teeth, the gear's moment of inertia is reduced, which minimizes the impact noise generated during rapid state changes while maintaining adequate strength through the thicker first teeth in non-engaging regions.
2Reliability
If the tooth thickness of gears is increased to reduce play and improve engagement, then engagement reliability improves, but the gear becomes heavier and larger, obstructing mounting operations
Solution Approach 1:
Instead of uniformly increasing tooth thickness throughout the gear, the invention applies different tooth thicknesses to different regions: the first teeth maintain standard thickness while the second teeth in the engaging region have reduced thickness. This local quality approach ensures adequate engagement reliability at the critical interface while keeping the overall gear compact and easy to handle during mounting operations.
3Force
If the elastic layer is deformed under long-term press-contact load, then the fixing unit can maintain pressing force, but the deformation does not return to original state even when load is released, causing permanent deformation
Solution Approach 1:
The pressure changing device periodically changes the pressing force applied by the fixing unit. By regularly alternating between pressed and pressure-released states, the elastic layer is given periodic opportunities to recover from deformation, preventing permanent set while maintaining the necessary pressing force during image formation. This periodic action counteracts the cumulative effect of long-term loading.
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 improves the engaging performance of gears, reduces backlash, and minimizes noise during state changes, allowing for more efficient and cost-effective operation without obstructing mounting processes.
Implementation Method 1
a cam (28) configured to rotate in interrelation with rotation of the first gear (51) and capable of changing a state of two members (31, 32) between a pressed state and a pressure-released state
Implementation Method 2
a pressing member (22, 23) configured to press the cam (28)
Implementation Method 3
a second gear (61b) configured to transmit drive to the first gear (51) in engagement with the first gear (51)
Data Source
Figure 1
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Figure 3~4
AI summary
A drive transmission device (60) includes a first gear (51), a cam (28, 29) configured to rotate in interrelation with rotation of the first gear and capable of changing a state of two members (31, 32) between a pressed state and a pressure-released state, a pressing member (22, 23, 40) configured to press the cam, and a second gear (61) configured to transmit drive to the first gear in engagement with the first gear. At least one of the first and second gears includes first teeth provided at positions corresponding to an engaging region in which the first gear is engaged with the second gear when the state of the two members is changed from the pressure-released state to the pressed state and includes second teeth provided at positions corresponding to a region other than the engaging region. Tooth thicknesses of the first teeth are thicker than tooth thicknesses of the second teeth.