Stacked-Chamber Development Device With Controlled Magnetic Release
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Solution Overview
Problem
Existing image forming apparatuses face challenges in size reduction, particularly in color-printing models, where the development devices occupy significant space, and there is a need for a configuration that allows for compact design without compromising developer conveyance efficiency.
Innovation Solution
A development device is designed with a first and second conveyance chamber stacked vertically, utilizing a first and second stirring-conveyance member to convey developer, along with a developer carrying member and regulation blade, adhering to specific magnetic force relationships to ensure efficient developer release and conveyance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the first and second conveyance chambers are disposed horizontally, then the developer conveyance is easy to implement, but the development device occupies large horizontal space
Solution Approach 1:
The patent transitions from a horizontal arrangement of conveyance chambers to a vertical stacking configuration. The first conveyance chamber is positioned below the second conveyance chamber, utilizing the vertical dimension to reduce horizontal footprint. This spatial reconfiguration allows the development device to occupy less horizontal space while maintaining functional effectiveness through gravity-assisted developer flow and controlled conveyance paths.
2Area of stationary object
If the conveyance chambers are stacked vertically, then the horizontal size is reduced, but the developer release becomes difficult to control
Solution Approach 1:
The magnetic member is designed with non-uniform magnetic pole distribution, creating localized magnetic fields at specific positions. The release pole generates a magnetic field that specifically targets and releases developer at controlled locations, while other regions maintain different magnetic characteristics for attraction and conveyance. This localized magnetic quality enables precise control of developer release in the vertically stacked configuration.
Solution Approach 2:
The patent optimizes the magnetic field strength parameters by controlling the peak magnetic force of the attracting pole (Y) and the magnetic force at the release start position (5 mT or less). By adjusting these magnetic parameters and their spatial distribution, the system achieves reliable developer release while maintaining stable conveyance in the vertical chamber arrangement.
3Reliability
If the magnetic force at the release pole is strong, then the developer attraction is effective, but the developer release is inhibited
Solution Approach 1:
The magnetic member is segmented into distinct functional regions with different magnetic pole configurations. The attracting pole provides strong magnetic force for reliable developer attraction, while the release pole creates a separate magnetic zone with controlled field strength (5 mT or less) that enables efficient release. This segmentation allows independent optimization of attraction and release functions without interference.
Solution Approach 2:
Instead of using a uniform strong magnetic field throughout, the patent inverts the approach by creating a weak magnetic field zone (5 mT or less) at the release position. This inverted magnetic field strength at the release pole, compared to the stronger attracting pole, enables smooth developer release while maintaining reliable attraction during conveyance.
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 achieves size reduction of the development device and image forming apparatus while maintaining satisfactory developer release and stability, ensuring consistent toner concentration and reduced mechanical stress on components.
Implementation Method 1
a magnetic member that is fixed inside the development sleeve so as not to be rotatable and that has, along the rotation direction of the development sleeve, a plurality of magnetic poles including a regulation pole opposite the regulation blade, a main pole opposite the image carrying member, a release pole releasing developer carried on the developer carrying member, and an attracting pole attracting developer onto the developer carrying member
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A development device (3a to 3d) includes a developer container (22) having a first conveyance chamber (22b) and a second conveyance chamber (22c) above it, a first stirring-conveyance member (43), a second stirring-conveyance member (44), a developer carrying member (20), and a regulation blade (27). The developer carrying member (20) includes a magnetic member (20b) having a regulation pole (N1), a main pole (S1), a release pole (N3), and an attracting pole (N1). A release start position (P1) at which the magnetic force of the release pole (N3) becomes 5 [mT] or less is below a straight line L1 horizontally passing through the center of a rotation shaft (44b) of the second stirring-conveyance member (44) and when the central angle of a developer releasing region (R) where the magnetic force between the release pole (N3) and the attracting pole (N1) is 5 [mT] or less is represented by X [°] and the peak magnetic force of the attracting pole (N1) is represented by Y [mT], Y ≤ 2.1X - 32.7 is satisfied.