Charging Roller Voltage Control for Image Deletion
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in accurately controlling the peak-to-peak voltage of alternating-current voltage applied to charging members, especially under varying ambient conditions such as temperature and humidity, which can lead to inconsistent charging and increased surface friction coefficients, potentially causing image deletion.
Innovation Solution
An image forming apparatus with a high-voltage generating circuit, voltage controller, and current detector that applies oscillation voltages with specific peak-to-peak values to determine an appropriate peak-to-peak voltage by analyzing DC current values, ensuring accurate control regardless of temperature and humidity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the peak-to-peak voltage Vpp of the AC voltage is raised to achieve uniform charging, then the charging voltage increases, but the charging potential becomes saturated and does not vary much even if Vpp is further raised
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the peak-to-peak voltage Vpp of the AC voltage based on detected DC current values. The control unit changes the voltage parameter adaptively to maintain optimal charging conditions across different operating states, resolving the contradiction between achieving uniform charging and maintaining charging potential variability.
Solution Approach 2:
The patent implements feedback by using a current detector to monitor the DC current value and feeding this information back to the control unit. The control unit then adjusts the peak-to-peak voltage Vpp based on this feedback, creating a closed-loop system that maintains appropriate charging potential while ensuring uniform charging across different conditions.
2Measurement precision
If the peak-to-peak voltage Vpp is increased to compensate for ambient condition changes, then charging accuracy improves, but surface friction coefficient increases causing image deletion
Solution Approach 1:
The patent uses feedback control where the current detector monitors DC current values at different peak-to-peak voltages, and the control unit adjusts Vpp accordingly. This feedback mechanism prevents excessive voltage application that would increase surface friction, while still achieving accurate charging by selecting the appropriate Vpp level based on real-time current detection.
Solution Approach 2:
The patent applies parameter changes by adaptively adjusting the peak-to-peak voltage Vpp based on detected operating conditions. Instead of using a fixed high voltage, the system changes the voltage parameter to the minimum necessary level that achieves accurate charging, thereby preventing excessive surface friction and image deletion while maintaining charging accuracy.
3Device complexity
If a fixed peak-to-peak voltage is used for charging, then the device complexity is reduced, but the charging performance becomes inconsistent under varying temperature and humidity conditions
Solution Approach 1:
The patent implements feedback control with a current detector that monitors DC current values and provides information to the control unit. This feedback mechanism enables the system to automatically adjust the peak-to-peak voltage Vpp in response to changing temperature and humidity conditions, maintaining consistent charging performance without requiring complex manual intervention or overly complicated fixed-voltage systems.
Solution Approach 2:
The patent applies dynamics by transitioning from a fixed voltage system to a dynamic voltage adjustment system. The control unit continuously adapts the peak-to-peak voltage Vpp based on real-time current detection and environmental conditions, making the charging system flexible and responsive to changing conditions while maintaining reliable charging performance.
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 allows for precise control of the peak-to-peak voltage, reducing surface friction and image deletion issues under high-temperature, high-humidity conditions, and maintaining accurate charging performance across different environmental conditions.
Implementation Method 1
a contact charging type charging device with little generation of ozone is used, in which the charging member (a charging roller or the like) is disposed in contact with, or close to, the photosensitive drum to charge the photosensitive drum
Implementation Method 2
The current detector detects a DC current value Idc between the charging member and the image carrier
Data Source
AI summary
An image forming apparatus includes a high-voltage generating circuit which applies to a charging member an oscillation voltage in which a DC voltage and an AC voltage are superimposed, a voltage controller which controls the DC voltage and a peak-to-peak voltage value Vpp of the AC voltage, and a current detector which detects a DC current value Idc between the charging member and an image carrier. The voltage controller detects an Idc(O′) when an oscillation voltage having a Vpp(O′) at an intersection point of a straight line L1 passing through coordinates A(Vpp(A), Idc(A)) and coordinates B(Vpp(B), Idc(B)) and a straight line passing through coordinates C(Vpp(C), Idc(C)) and parallel to a coordinate axis representing Vpp. Vpp(O) at an intersection point O of a straight line L2 passing through coordinates C and coordinates O′(Vpp(O′), Idc(O′)) and the straight line L1 is determined as an appropriate peak-to-peak voltage value.