Dynamic AC Frequency Adjustment for Charge Removal in Electrophotographic Printers
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Solution Overview
Problem
Existing electrophotographic image forming apparatuses face challenges in effectively removing electrical charges from paper after toner transfer, leading to uneven potential and print quality issues due to the limitations of AC transfer and charge removing techniques, including phase shifts and potential differences between transfer and charge removing members.
Innovation Solution
An image forming apparatus with a transfer member applying a first AC voltage to transfer toner images and a charge removing member applying a second AC voltage, where the frequency of the second AC voltage is increased when the paper approaches the charge removing member, ensuring effective electrical discharge and charge removal without relying on phase alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the DC component voltage of the AC voltage is decreased to apply lower voltage to the image region, then the potential difference between transfer member and charge removing member is reduced, but the electrical charge is not effectively removed from the paper
Solution Approach 1:
The patent dynamically adjusts the frequency of the second AC voltage based on the position of the paper in the conveyance path. When the paper is in the charge removing region, the frequency is increased to enhance charge removal effectiveness. This dynamic adjustment resolves the contradiction by adapting the voltage characteristics to the specific operational needs at different locations.
Solution Approach 2:
The patent changes the frequency parameter of the second AC voltage from a fixed value to a variable value that depends on the paper position. By increasing the frequency when the paper approaches the charge removing member, the system achieves effective charge removal without requiring a fixed low DC component voltage throughout the entire path.
2Object-affected harmful factors
If the transfer voltage and charge removing voltage are set in phase with each other to prevent electrical discharge between members, then the potential difference between members is decreased, but the electrical charge is not effectively removed from the paper and paper conveyance fails
Solution Approach 1:
The patent introduces dynamic frequency adjustment for the second AC voltage based on paper position. When the paper is in the charge removing region, the frequency is increased to create sufficient potential difference for effective charge removal and stable conveyance, while maintaining phase alignment to prevent discharge between members. This dynamic approach resolves the contradiction by adapting to local requirements.
Solution Approach 2:
The patent applies different frequency characteristics to the second AC voltage at different locations in the conveyance path. In the charge removing region, the frequency is increased to enhance charge removal effectiveness, while other regions maintain appropriate frequencies. This local optimization resolves the contradiction by tailoring the voltage characteristics to specific operational needs.
3Reliability
If the frequency of the second AC voltage is increased to enhance electrical discharge and charge removal from paper, then charge removal effectiveness is improved, but the complexity of voltage control increases
Solution Approach 1:
The patent employs feedback control by detecting the paper position in the conveyance path and adjusting the frequency of the second AC voltage accordingly. The control unit receives position information and dynamically modifies the voltage frequency to match the operational requirements, thereby achieving effective charge removal while managing control complexity through intelligent regulation.
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 removes electrical charges from the paper, preventing uneven potential and ensuring stable paper conveyance and improved print quality by increasing the potential difference between the paper and the charge removing member.
Implementation Method 1
The application of the transfer voltage causes a reciprocating motion of toners, among which physical and electrical interactions occur. As a result, adhesion of the toners is reduced to result in improved transferability of the toner image from the image carrier to the paper.
Implementation Method 2
An AC charge removing technique that separates the paper from the image carrier is known as a technique of preventing such situation. In an AC charge removing process, an AC voltage which is opposite in polarity to the transfer voltage and on which a DC component and an AC component are superimposed is applied to the paper by a charge removing member. The electrical charge is removed from the paper as a result.
Implementation Method 3
a control unit configured to change a frequency of the second AC voltage when a distance between the medium being conveyed and the charge removing member becomes shorter than a predetermined distance
Data Source
AI summary
An image forming apparatus that transfers a toner image to a medium being conveyed includes: an image carrier configured to carry the toner image; a transfer member configured to apply, to the medium being conveyed, a first AC voltage which is opposite in polarity to the toner image and on which a DC component and an AC component are superimposed, and transfer the toner image to the medium; a charge removing member configured to apply, to the medium being conveyed, a second AC voltage which is opposite in polarity to the first AC voltage and on which a DC component and an AC component are superimposed after the first AC voltage is applied to the medium; and a control unit configured to change a frequency of the second AC voltage when a distance between the medium being conveyed and the charge removing member becomes shorter than a predetermined distance.