Planetary Gear Switching for Stable Duplex Sheet Discharge
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Solution Overview
Problem
Existing image forming apparatuses face instability and increased time in switching the rotational direction of sheet discharge rollers during double-sided printing due to the reduction of the distance between the pressure roller and the sheet discharge roller, leading to inefficient operation and potential paper jams.
Innovation Solution
A driving force transmitting apparatus with a first and second planetary gear unit, a rotation switching member, and a solenoid, where the rotation switching member can lock specific gear portions to stabilize the rotational direction switching, and the solenoid's design includes an urging member to ensure efficient switching without repelling the locking mechanism, thereby minimizing the time required for direction change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between the pressure roller and the sheet discharge roller is reduced to downsize the image forming apparatus, then the apparatus size is reduced, but the switching operation becomes unstable and the switching time increases
Solution Approach 1:
The locking mechanism is segmented into multiple locked portions (first locked portions and second locked portions) arranged at different angular positions on the locked gear. This segmentation allows the locking member to engage with different portions during the switching process, providing stable positioning even when the overall apparatus size is reduced.
Solution Approach 2:
The locking member is designed to engage with the locked portions in a predetermined sequence during the switching operation. The urging member pre-positions the locking member to ensure it engages with the appropriate locked portion before the switching action is completed, preventing instability during the transition.
2Speed
If the solenoid spring force is reduced to increase the solenoid attraction force, then the switching speed increases, but the locking member is repelled by the gear claw during return movement
Solution Approach 1:
The locked portions are designed with asymmetric engagement characteristics. The engagement between the locking member and locked portions during the forward switching action is designed to be more secure than during the return action. This allows the locking member to firmly engage during switching while permitting smooth disengagement during return when the spring acts.
Solution Approach 2:
The urging member is designed to gradually increase its force during the return movement of the locking member, cushioning the impact that would otherwise cause repulsion between the locking member and gear claw. This prevents instability during the return phase while maintaining high switching speed.
3Loss of time
If the interval between locked portions is reduced to enable faster switching, then the switching time decreases, but the locking member cannot be reliably engaged
Solution Approach 1:
Different regions of the locked gear have different angular intervals between locked portions. The first locked portions are arranged with a smaller angular interval to enable fast switching in one direction, while the second locked portions are arranged with a larger angular interval to ensure reliable engagement in the opposite direction. This local differentiation of quality allows the system to achieve both fast switching and reliable engagement.
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 stabilizes the switching operation of the rotational direction and reduces the time needed to switch, preventing paper jams and improving operational efficiency while using a compact and cost-effective solenoid with reduced power consumption.
Implementation Method 1
a solenoid configured to move the rotation switching member
Implementation Method 2
an urging member configured to urge the rotation switching member to the second stop position
Data Source
AI summary
A driving force transmitting apparatus includes first and second planetary gear units and switching and urging members. The first planetary gear unit includes a first mesh gear and a first locked gear provided with first locked portions. The second planetary gear unit includes a second locked gear provided with second locked portions, and a second mesh gear meshing with the first mesh gear. The switching member includes first and second locking portions and can move to (i) a first stop position at which the first locking portion stop the first locked gear, and, urged by the urging member, (ii) a second stop position at which the second locking portion stops the second locked gear. An interval between the second locked portions in a rotational direction of the second locked gear is larger than an interval between the first locked portions in a rotational direction of the first locked gear.