Development Device Magnetic Flux Density Uniformity
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Solution Overview
Problem
Existing image forming apparatuses using a two-component development system face challenges in achieving uniformity of the developer layer density, requiring high precision in the arrangement of the second development blade to prevent developer overflow or non-contact issues, which affects image quality.
Innovation Solution
A development device with a developer bearing member, a magnet, and a regulation portion where the magnetic flux density is positive upstream and downstream of the development region, ensuring uniform developer layer density and improved image quality by optimizing the placement of the development blade relative to the magnetic flux distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a second development blade is disposed closer to the development sleeve to compress the developer layer, then the density uniformity is improved, but developer overflow occurs at the upstream side
Solution Approach 1:
The first development blade performs preliminary regulation of the developer amount before the second development blade compresses the developer layer. This preliminary action prevents overflow by controlling the developer quantity in advance, allowing the second blade to focus on compression without causing upstream accumulation and overflow.
Solution Approach 2:
The first development blade acts as an intermediary between the developer supply and the second development blade. It regulates the developer amount before compression, serving as a buffer that prevents direct overflow while enabling effective compression by the second blade for density uniformity.
2Quantity of substance
If a second development blade is disposed farther from the development sleeve to avoid developer overflow, then developer overflow is prevented, but the regulation effect is lost due to non-contact
Solution Approach 1:
The first development blade performs preliminary regulation upstream, controlling the developer amount before it reaches the second development blade. This allows the second blade to be positioned optimally for compression without causing overflow, as the developer quantity is already regulated.
Solution Approach 2:
The developer regulation function is segmented into two stages: the first development blade regulates the developer amount upstream, and the second development blade compresses the layer downstream. This segmentation allows each blade to perform its specific function optimally without interfering with the other.
3Manufacturing precision
If high precision arrangement of the second development blade is implemented to achieve uniform density, then the density uniformity is improved, but the device complexity and adjustment difficulty increase
Solution Approach 1:
The first development blade performs preliminary regulation of the developer amount, which simplifies the requirements for the second development blade's positioning. Since the developer quantity is already controlled, the second blade only needs to perform compression, reducing the overall arrangement precision requirements.
Solution Approach 2:
The regulation function is divided between two blades with different functions: the first blade handles amount regulation upstream with more relaxed positioning requirements, while the second blade handles compression downstream. This segmentation distributes the precision requirements across multiple components rather than concentrating them on a single critical component.
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 enhances the uniformity of the developer layer density, leading to improved image quality, particularly in halftone images, by preventing non-uniform developer rearrangement and maintaining consistent contact between the developer and the photosensitive drum.
Implementation Method 1
a magnet that is stored in the developer bearing member and has a development pole for developing the electrostatic latent image formed on the image bearing member
Implementation Method 2
when a magnetic flux density of the development pole in the normal direction with respect to a surface of the developer bearing member is defined as positive, a magnetic flux density becomes positive in the entirety of a region which is upstream of a development region
Implementation Method 3
electrostatically adsorbed on the photosensitive drum with the developer being napped in a brush chain due to the magnetic force of the magnet roller
Data Source
AI summary
A development device includes a developer bearing member and a magnet which is fixed inside of the developer bearing member. The magnet includes a first magnetic pole for developing a latent image, a second magnetic pole adjacent to the first magnetic pole and being an opposite pole to the first magnetic pole, and a third magnetic pole adjacent to both the first and second magnetic poles and having an opposite pole to the first magnetic pole. A developer regulation portion is disposed such that when a maximum peak amount of a magnetic flux density of the first magnetic pole in a normal direction of the developer bearing member is defined as positive, the magnetic flux density of the first magnetic pole becomes positive in an entire region from a downstream side of the regulating member in a rotary direction of the developer bearing member and through a developing area.