High-Voltage Power Supply Polarity Switching Control
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Solution Overview
Problem
The existing high-voltage power supply systems for image forming apparatuses face challenges in efficiently switching between positive and negative voltages during the transition period, leading to potential fluctuations in the photosensitive drum's potential and defective image generation, especially when the conveyance speed is increased to improve throughput.
Innovation Solution
A high-voltage power supply apparatus with a control unit that manages two high-voltage generation units to selectively output voltages of opposite polarities, using a correction value and period calculation to ensure smooth switching, even with changing load resistance values, thereby optimizing the bias switching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conveyance speed is increased to improve throughput, then the productivity is improved, but the switching time period of the transfer bias cannot be sufficiently secured, leading to potential fluctuations in the photosensitive drum's potential and defective image generation
Solution Approach 1:
The control unit performs preliminary switching of the transfer bias polarity before the trailing edge of the recording material reaches the transfer nip portion. By anticipating the need for polarity switching and executing it in advance during the margin part passage, the system ensures that the bias is already switched when the trailing edge exits, eliminating potential fluctuations without requiring extended switching time that would conflict with high conveyance speeds.
2Loss of time
If the switching of transfer bias is delayed until after the trailing edge passes through, then the switching time period can be extended, but the potential of the facing photosensitive drum is affected and defective images are generated
Solution Approach 1:
The control unit executes the polarity switching operation in advance during the period when the trailing edge margin part is passing through the transfer nip portion, rather than delaying it. This preliminary action ensures that the transfer bias is already switched to the appropriate polarity before the trailing edge completes its passage, preventing any potential fluctuations from affecting the photosensitive drum and eliminating the risk of defective image generation.
3Reliability
If a complex voltage switching control system is implemented to manage the transition period, then the potential fluctuations can be reduced, but the device complexity increases
Solution Approach 1:
The control unit integrates multiple functions into a single component: it detects the presence of recording materials, determines trailing edge passage timing, controls the polarity switching of transfer bias, and manages the timing coordination between conveyance and voltage switching. This multi-functional approach achieves reliable potential stability without requiring separate specialized components for each function, thereby avoiding excessive device complexity.
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 solution shortens the switching time period of voltage polarities, reduces potential fluctuations, and prevents defective image generation, while also simplifying the power supply configuration and reducing the number of circuit components, thereby enhancing the system's efficiency and miniaturization.
Implementation Method 1
a first high voltage generation unit configured to output a first high voltage having a predetermined polarity, a second high voltage generation unit connected to the first high voltage generation unit and configured to output a second high voltage having a polarity reverse to the polarity of the first high voltage
Implementation Method 2
during a transition period in which a state in which the first high voltage is output is switched to a state in which the second high voltage is output, the control unit sets a setting value in accordance with a voltage higher than a target voltage of the second high voltage as a setting value for outputting the second high voltage and then sets a setting value in accordance with the target voltage as the setting value for outputting the second high voltage
Data Source
AI summary
A high-voltage power supply that outputs high voltages having a predetermined polarity and a reverse polarity performs control in a manner that, during a transition period in which switching of a target voltage of the high voltage having the reverse polarity from the predetermined polarity is performed, a setting value in accordance with a voltage higher than a target voltage is set as the voltage having the reverse polarity, and then a setting value in accordance with the target voltage is set as the voltage having the reverse polarity.