Segmented Grid Electrode for Uniform Corona Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Scorotron charging devices face challenges in reducing size and increasing speed while maintaining charging performance and uniformity on the surface of photosensitive drums, leading to potential irregularities.
Innovation Solution
A charging device with a discharge electrode and a grid electrode divided into regions along the rotation direction of the photosensitive drum, where the opening ratio closest to the drum is greater than further regions, ensuring uniform charging and reducing discharge current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the width of the shield case is reduced to decrease the size of the charging device, then the device size is reduced, but charging performance and uniformity in the long direction deteriorate
Solution Approach 1:
The grid electrode is divided into multiple regions along the long direction, with each region having different opening ratios. The region closest to the photosensitive drum has a larger opening ratio to enhance charging performance, while other regions have smaller opening ratios to maintain uniformity. This local differentiation resolves the contradiction by optimizing each zone according to its specific charging requirements.
2Productivity
If the opening ratio of the grid electrode is increased to increase the speed, then the charging speed is improved, but charging irregularities arise on the surface of the photosensitive drum
Solution Approach 1:
Different regions of the grid electrode are assigned different opening ratios based on their position relative to the photosensitive drum. The region closest to the drum has the highest opening ratio to maximize charging speed, while regions farther away have progressively lower opening ratios to prevent over-charging and maintain uniformity. This spatially differentiated design enables high-speed charging without sacrificing quality.
3Productivity
If both the shield case width is reduced and the grid electrode opening ratio is increased to achieve compact high-speed charging, then device size is reduced and speed is increased, but charging irregularities occur
Solution Approach 1:
The grid electrode is segmented into multiple regions along the long direction, with each region having a customized opening ratio. The region closest to the photosensitive drum has the largest opening ratio to enable high-speed charging, while other regions have progressively smaller opening ratios to maintain charging uniformity. This local optimization allows the device to achieve both compact size and high-speed charging without introducing irregularities.
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
Enables a compact and high-speed charging device that suppresses charging irregularities on the photosensitive drum, maintaining performance even at high image formation speeds.
Implementation Method 1
a discharge electrode, which carries out corona discharge, applies a voltage to the surface of the photosensitive drum and charges the surface
Implementation Method 2
a grid electrode with a porous plate shape, which is disposed between the discharge electrode and the photosensitive drum so as to face the surface of the photosensitive drum and which controls a charging potential at the surface
Data Source
AI summary
To provide a charging device which can be reduced in size and increased in speed while suppressing the occurrence of charging irregularities on the surface of the photosensitive drum, a process cartridge, and an image forming apparatus. A charging device 311Y which charges a surface of a photosensitive drum 310Y, comprises a discharge electrode 610 which applies a potential to the surface of the photosensitive drum 310Y and charges the surface, and a grid electrode 670 with a porous place shape disposed between the discharge electrode 610 and the surface of the photosensitive drum 310Y so as to face the surface of the photosensitive drum 310Y and which controls the charging potential of the surface, wherein the grid electrode 670 is divided into a plurality of regions approximately parallel to a direction orthogonal to a direction of rotation of the photosensitive drum 310Y, and the plurality of regions is characterized in that an opening ratio of a midstream region 672 close to the photosensitive drum 310Y is greater than an opening ratios of an upstream region 671 and a downstream region 673.