Compact Developing Device with Segmented Magnetic Poles
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Solution Overview
Problem
Compact developing devices for image forming apparatuses face challenges in producing high-quality images with uniform image density due to difficulties in generating sufficient magnetic fields with small-diameter developing sleeves, leading to non-uniform developer distribution and image quality issues.
Innovation Solution
A compact developing device with a cylindrical, rotatable developer bearing member featuring a magnetic field generator with three magnetic poles, including a developing pole, a pre-developing pole, and a post-developing pole, along with a divider to separate the developer into upper and lower chambers for uniform developer supply and collection, ensuring consistent image development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the developing sleeve diameter is reduced to achieve compactness, then the size of the image forming apparatus is reduced, but the magnetic field strength becomes insufficient leading to non-uniform developer distribution
Solution Approach 1:
The magnetic field generator is segmented into three distinct magnetic poles (first, second, and third poles) arranged at specific intervals around the developing sleeve. This segmentation creates multiple localized magnetic fields that collectively ensure uniform developer distribution across the entire developing area, compensating for the reduced overall magnetic field strength in compact designs.
Solution Approach 2:
Each magnetic pole is positioned to create a localized magnetic field in specific regions: the first pole in the developer supply area, the second pole in the developer separation area, and the third pole in the developing area. This local quality approach ensures that each critical region receives appropriate magnetic field strength for its specific function, maintaining developer distribution uniformity despite the small developing sleeve diameter.
2Volume of moving object
If the developing sleeve diameter is reduced, then the device becomes more compact, but the ability to contain sufficient magnets for reliable developer supply, conveyance, and separation deteriorates
Solution Approach 1:
The patent merges multiple functions into the three magnetic poles: developer supply, conveyance, and separation are all achieved through the coordinated action of these three poles. The first pole supplies developer, the second pole separates developer, and the third pole facilitates conveyance, combining what would traditionally require more separate magnetic components into a compact three-pole configuration.
Solution Approach 2:
Instead of increasing the number of magnets in the radial direction (which would increase diameter), the patent utilizes the circumferential dimension by strategically positioning three magnetic poles around the developing sleeve at specific angular intervals. This dimensional approach allows sufficient magnetic field generation in a compact radial space.
3Device complexity
If developer is supplied from the upper side of the developing sleeve, then the device structure is simplified, but image density uniformity deteriorates due to non-uniform pressure distribution
Solution Approach 1:
The patent changes the magnetic field distribution parameters by positioning the first magnetic pole in the developer supply area and the second magnetic pole in the developer separation area. This parameter change in magnetic field positioning compensates for the non-uniform pressure distribution caused by upper-side developer supply, ensuring that developer ears are formed with sufficient uniformity across the developing area to produce uniform image density.
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 enables the production of high-quality images with uniform image density by maintaining consistent developer distribution and pressure across the developing sleeve, addressing the challenges of compactness and image uniformity in existing technologies.
Implementation Method 1
a magnetic field generator having multiple magnetic poles
Implementation Method 2
The multiple magnetic poles include a developing pole, a pre-developing pole, and a post-developing pole
Implementation Method 3
the cylindrical and rotatable developer bearing member is disposed facing an electrostatic latent image bearing member to form a developing area therebetween
Data Source
AI summary
A developing device including a developer bearing member containing a magnetic field generator having multiple magnetic poles and a developer containing chamber is provided. The developer containing chamber contains a two-component developer comprising magnetic carrier particles having a saturated magnetization of 58 to 70 emu/g in a magnetic field of 1KOe and toner particles, and has a divider to define an upper supply chamber and a lower collection chamber. The supply chamber includes a supply conveyer to supply the two-component developer to the developer bearing member at an upstream side from the developing area. The collection chamber includes a collection conveyer to collect the two-component developer from the developer bearing member at a downstream side from the developing area. The multiple magnetic poles includes three developer bearing poles capable of bearing the developer on its surface.