Image Forming Apparatus Charging Bias Voltage Control
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Solution Overview
Problem
In image forming apparatuses, especially those with two-component development systems, toner adherence issues arise due to insufficient charging of photoconductive elements, leading to image failures like carrier adhesion and stains, as the developing roller is often biased before the charging is complete, resulting in uneven toner distribution.
Innovation Solution
The image forming apparatus employs a charger to charge the photoconductive element, with a charging bias voltage applied in one step and developing bias voltage applied in multiple steps, matching the potential difference across the developing roller to the changing charging potential, thereby maintaining a constant potential difference and preventing toner adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the developing bias is applied to the developing roller at a timing earlier than when the charged photoconductive element faces the developing roller, then the developing roller is prepared in advance for image formation, but the developing roller faces a photoconductive element region with insufficient charging, causing toner to adhere to the region
Solution Approach 1:
The charging bias voltage is applied to the charger in advance before the photoconductive element reaches the developing roller, ensuring the photoconductive element is fully charged before the developing bias is applied. This preliminary charging action prevents toner adhesion issues that occur when developing bias is applied too early to an insufficiently charged surface.
Solution Approach 2:
The system controls the timing of developing bias application based on the charging status of the photoconductive element. By monitoring when the charged photoconductive element faces the developing roller, the system adjusts the developing bias application timing to coincide with adequate charging, preventing toner adhesion to insufficiently charged regions.
2Productivity
If the charging bias voltage is changed in one step, then the charging process is simplified and faster, but the developing bias voltage must be changed in multiple steps to match the changing charging potential, increasing device complexity
Solution Approach 1:
The developing bias voltage change is divided into multiple steps that correspond to different stages of the charging process. While the charging bias voltage changes in one step, the developing bias voltage is segmented into multiple adjustment stages to match the evolving charging potential, ensuring consistent potential difference throughout the process.
Solution Approach 2:
The system dynamically adjusts the developing bias voltage parameter in multiple steps to match the changing charging potential. By modifying the developing bias voltage parameter in response to the charging status, the system maintains optimal potential difference across the developing roller despite the simplified one-step charging bias voltage change.
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 approach effectively suppresses image failures such as carrier adhesion and stains by ensuring consistent voltage application across the developing roller, matching the changing charging potential, and maintaining image quality even with environmental changes.
Implementation Method 1
The charger charges a surface of an image carrier in a wide-angle by discharge
Implementation Method 2
The exposing device forms an electrostatic latent image in a charged image carrier
Data Source
AI summary
According to one embodiment, a charger charges a surface of an image carrier by discharge in a wide-angle. A charging bias voltage application section applies a charging bias voltage to the charger. An exposing device forms an electrostatic latent image in a charged image carrier. A toner carrier causes toner to adhere to the electrostatic latent image formed in the image carrier. A developing bias voltage application section applies the developing bias voltage to the toner carrier. In addition, the developing bias voltage application section changes the charging bias voltage in one step and changes the developing bias voltage applied to the toner carrier in multiple steps.