Developing Voltage Control for Toner Fogging and Carrier Development
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Solution Overview
Problem
Existing image forming apparatuses using two-component developer face issues with inconsistent toner charge amount leading to toner fogging and carrier development, resulting in image defects.
Innovation Solution
The apparatus incorporates a control portion that adjusts the blank-part potential difference between the image carrying member and developing voltage based on predicted fogging toner and carrier development amounts, using first and second potential difference adjustment modes to prevent toner fogging and carrier development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the blank-part potential difference is adjusted based on toner charge amount, then toner fogging is suppressed, but carrier development may occur causing image defects
Solution Approach 1:
The invention dynamically adjusts the blank-part potential difference by changing the direct-current component of the developing voltage based on detected toner charge amount. This parameter change allows suppression of toner fogging while preventing carrier development by optimizing the potential difference within a specific range
Solution Approach 2:
The invention uses a feedback mechanism where the toner charge amount is detected by a current sensing portion, and this detected value is used to adjust the blank-part potential difference through the developing voltage power supply. This closed-loop control ensures optimal suppression of both toner fogging and carrier development
2Manufacturing precision
If the blank-part potential difference is increased to suppress toner fogging, then image quality improves, but carrier development increases causing patchiness
Solution Approach 1:
The invention optimizes the blank-part potential difference by dynamically adjusting the direct-current component of the developing voltage. By maintaining the potential difference within a specific range (50-150 V) based on toner charge amount, it achieves high image quality while preventing carrier development and patchiness
Solution Approach 2:
The invention makes the blank-part potential difference dynamic rather than fixed. The potential difference is continuously adjusted based on the detected toner charge amount, allowing the system to adapt to varying conditions and maintain optimal image quality without causing carrier development
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 toner fogging and carrier development, thereby improving image quality by setting optimal blank-part potential differences through predictive adjustments.
Implementation Method 1
The charging device electrostatically charges the image carrying member
Implementation Method 2
The exposure device forms an electrostatic latent image by shining light to the image carrying member electrostatically charged by the charging device
Implementation Method 3
a developer carrying member that carries two-component developer containing magnetic carrier and toner
Implementation Method 4
The developing voltage power supply applies to the developer carrying member a developing voltage having an alternating-current voltage overlaid on a direct-current voltage
Data Source
AI summary
In the first potential difference adjustment mode, the fogging toner amount is predicted from a toner charge amount and a fogging toner current sensed by a current sensing portion with a zero surface potential on the image carrying member. In the second potential difference adjustment mode, the carrier development amount is predicted from a toner concentration, a carrier charge amount calculated based on the toner charge amount, and a carrier development current sensed by the current sensing portion with a zero surface potential on the image carrying member.