Transfer Belt Front-End Current Control for Sheet Separation
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Solution Overview
Problem
Belt-transfer type image forming apparatuses face challenges in maintaining sheet separation performance under high humidity environments due to decreased surface resistance of the transfer belt, leading to increased separation failure rates and reduced adsorption force between the transfer belt and recording sheets.
Innovation Solution
An image forming apparatus with a control system that sets a front-end current to flow through the transfer member when a voltage with a polarity opposite to the transfer polarity and an absolute value equal to or greater than the surface potential of the image bearing member is applied, enhancing the adsorption force between the transfer belt and recording sheets by controlling the voltage application during the sheet conveyance process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transfer belt is left in a high humidity environment for long periods, then the transfer belt absorbs moisture and its surface resistance decreases, but the adsorption force between the transfer belt and recording sheet is reduced, causing separation failure
Solution Approach 1:
The control section performs preliminary measurement of the transfer belt's surface resistance before the actual transfer process. Based on this measurement, the system pre-adjusts the front-end transfer current to an appropriate value that compensates for the reduced adsorption force caused by high humidity, ensuring reliable separation performance from the outset
Solution Approach 2:
The system dynamically changes the front-end transfer current parameter based on the measured surface resistance of the transfer belt. When humidity causes resistance to decrease, the control section automatically adjusts the current to maintain optimal separation performance, transforming a static parameter into a dynamically adaptive one
2Reliability
If the surface resistance of the transfer belt decreases due to moisture absorption, then the transfer electric charge diffuses, but the conventional control method cannot sufficiently improve separation performance
Solution Approach 1:
The control section establishes a feedback loop that continuously measures the transfer belt's surface resistance and uses this information to adjust the front-end transfer current. This closed-loop control ensures that the system automatically compensates for charge diffusion caused by decreased resistance, maintaining precise charge control despite environmental variations
3Reliability
If the use history of the transfer belt increases, then discharge products form on the inner periphery surface, increasing hygroscopic property, but separation performance is further degraded
Solution Approach 1:
The control section performs preliminary measurement of surface resistance at the start of each day or before printing operations begin. This preliminary assessment allows the system to proactively adjust the front-end transfer current to compensate for accumulated discharge products and increased hygroscopicity, maintaining separation performance throughout the transfer belt's service life
Solution Approach 2:
The system enables the transfer belt to effectively serve itself by using its own surface resistance characteristics as the basis for automatic current adjustment. The control section uses the measured resistance to self-regulate the front-end transfer current, allowing the system to adapt to the transfer belt's aging and hygroscopic changes without external intervention
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 improves the separation performance of recording sheets from the image bearing member by maintaining an effective electrostatic attraction between the transfer belt and recording sheets, even in high humidity conditions, thereby reducing separation failure rates and maintaining print quality.
Implementation Method 1
A transfer voltage having a polarity opposite to a charging polarity of toner (transfer polarity) is applied to the transfer belt to transfer the toner image on the photoconductor drum onto the recording sheet by electrostatic attraction
Implementation Method 2
when the transfer belt is left in a high humidity environment for long periods of time, the transfer belt absorbs moisture in the air, and the electric resistance thereof decreases
Data Source
AI summary
An image forming apparatus includes: a rotatable image bearing member; a transferring member that forms a transfer nip portion with the image bearing member; a voltage application section that applies a voltage to the transferring member in such a manner that a certain amount of current flows through the transferring member; and a control section that sets a front-end current to a current that flows through the transferring member when a voltage having a polarity opposite to a transfer polarity and an absolute value substantially the same as or greater than an absolute value of a surface potential of the image bearing member is applied to the transferring member, the control section controlling the voltage application section in such a manner that the set front-end current flows through the transferring member when a front-end portion of a recording sheet in a conveyance direction passes through the transfer nip portion.