Developer Bearing Member Deceleration Control for Toner Scattering
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Solution Overview
Problem
Existing image forming apparatuses using electrophotographic systems face challenges in suppressing toner scattering during the stopping operation of the developer bearing member, leading to increased pressure inside the developer container and subsequent toner blowout, which is difficult to manage without extending the stopping time.
Innovation Solution
The apparatus incorporates a control unit that gradually reduces the rotational speed of the developer bearing member before stopping, allowing for a controlled deceleration to a specific peripheral speed that minimizes toner scattering, thereby stabilizing airflow and preventing toner ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the developer bearing member is stopped rapidly after image formation, then the stopping time is shortened, but toner scattering occurs due to pressure buildup inside the developer container
Solution Approach 1:
The control unit performs preliminary action by reducing the rotational speed of the developer bearing member to a predetermined low speed before stopping it. This preliminary deceleration prevents pressure buildup inside the developer container that would otherwise cause toner to scatter and adhere to surrounding devices, thereby resolving the contradiction between quick stopping and toner scattering prevention.
2Object-generated harmful factors
If the rotational speed of the developer bearing member is reduced before stopping, then toner scattering is suppressed, but the stopping operation time increases
Solution Approach 1:
The control unit changes the rotational speed parameter of the developer bearing member in a controlled manner before stopping. By reducing the speed to a predetermined value rather than stopping immediately, the system prevents pressure-induced toner scattering while keeping the additional time required minimal, thus resolving the contradiction between scattering suppression and time loss.
3Device complexity
If air inflow to the developer container is stopped before pressure stabilization, then the stopping sequence is simplified, but air including toner is blown out due to internal pressure
Solution Approach 1:
The control unit performs preliminary deceleration of the developer bearing member before stopping air inflow. This preliminary action allows pressure inside the developer container to stabilize naturally as the rotational speed decreases, preventing toner blowout when air flow is stopped, while maintaining a relatively simple stopping sequence.
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 approach effectively reduces toner scattering during the stopping operation without increasing the time required for stopping the developer bearing member, maintaining apparatus performance and preventing image failures like white lines and fogging.
Implementation Method 1
there is generated an airflow which flows from an inside to an outside of the developer container through a portion connecting the inside and the outside of the developer container
Implementation Method 2
the pressure inside the developer container tends to be increased by the airflow flowing into the developer container. At the time of stopping the drive of the bearing member, when the inflow of air to the inside of the developer container is stopped before the pressure inside the developer container is statically set, the air including toner is liable to be blown out to the outside
Data Source
AI summary
An image forming apparatus includes a controller to control a driving unit that rotates a developing rotary member. Rotation speed of the developing rotary member is controlled to become a first rotation speed in an image forming period. Rotation speed of the developing rotary member is decelerated from the first rotation speed in a first period of a non-image forming period so that the rotation speed becomes a second rotation speed lower than the first rotation speed, and rotation speed is decelerated from the second rotation speed in a second period subsequent to the first period of the non-image forming period so that the rotation of the developing rotary member is stopped. A deceleration amount per unit time of the developing rotary member in the first period is smaller than a deceleration amount per unit time of the developing rotary member in the second period.