Discharging Device Angles for Image Fluctuation Control
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Solution Overview
Problem
Conventional image forming apparatuses using electrophotographic methods face challenges in effectively discharging excessive charges on recording sheets, leading to poor separation from photosensitive drums and image fluctuations, especially when the sheet charging polarity is negative.
Innovation Solution
The apparatus employs a discharging device with a first and second discharging unit, both grounded and oriented at specific angles, to efficiently discharge electric charges from the recording medium, ensuring effective separation and minimizing image fluctuations regardless of the sheet's charging polarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a negative voltage is applied to discharge excessive positive charges from the sheet, then the separating ability of the sheet from the photosensitive drum is improved, but image fluctuation occurs due to ions generated from the discharging unit flowing into the transfer portion
Solution Approach 1:
The discharging unit is divided into multiple discharge electrodes (first discharge electrode and second discharge electrode) arranged at different positions and angles. This segmentation allows different regions of the sheet to be discharged by different electrodes, enabling effective discharge of both positive and negative charges while controlling ion flow to prevent image fluctuation.
Solution Approach 2:
Different discharge electrodes are configured with different orientations and positions relative to the sheet conveyance direction. The first discharge electrode is arranged to discharge positive charges effectively, while the second discharge electrode is arranged to discharge negative charges. This local differentiation in electrode configuration enables effective discharge regardless of the sheet's charging polarity without causing image fluctuation.
2Reliability
If a discharging unit is disposed downstream to eliminate excessive positive charges, then the separating ability is heightened, but the unit cannot effectively discharge negative charges, causing image fluctuation
Solution Approach 1:
The discharging unit is segmented into multiple discharge electrodes with different orientations. The first discharge electrode is arranged to effectively discharge positive charges, while the second discharge electrode is arranged to effectively discharge negative charges. This segmentation enables the system to adapt to different charging polarities of the sheet.
Solution Approach 2:
The discharging unit is designed with multiple discharge electrodes that can handle both positive and negative charging polarities of the sheet. By incorporating electrodes with different orientations and configurations, the system achieves universal discharge capability regardless of the sheet's charging property, making it adaptable to various operating conditions.
3Adaptability or versatility
If multiple discharging units are added to handle both positive and negative charges, then discharge effectiveness is improved, but device complexity increases
Solution Approach 1:
Multiple discharge electrodes with different functions are merged into a single integrated discharging unit structure. The first and second discharge electrodes are arranged in close proximity and work together as a unified system, achieving effective discharge of both positive and negative charges without requiring separate independent discharging devices.
Solution Approach 2:
The discharging unit is designed as a multi-functional component that can discharge both positive and negative charges using multiple electrodes with different orientations. This universal design eliminates the need for separate discharging devices for different polarities, maintaining structural simplicity while achieving comprehensive discharge effectiveness.
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 allows for efficient discharging of both positive and negative charges, enhancing the separation ability of the sheet from the photosensitive drum and reducing image fluctuations, while maintaining a simple and cost-effective design.
Implementation Method 1
a discharging device being disposed downstream from the transfer portion in a recording medium conveyance direction and configured to discharge an electric charge of a surface of the recording medium
Data Source
AI summary
An image forming apparatus includes a discharging device that discharges a sheet to which a toner image is transferred. The discharging device is disposed on a side opposite to a transfer surface of the sheet to which the toner image is transferred downstream from a nip portion between an intermediate transfer belt and an external secondary transfer roller in a sheet conveyance direction. The discharging device includes a grounded first discharging plate, and a grounded second discharging plate which is disposed downstream from the first discharging plate in the sheet conveyance direction at an angle different from an angle of the first discharging plate.