Charging Power Supply Circuit for Accurate DC Current Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrophotographic image forming apparatuses with AC charging systems face detection errors due to ripple voltage caused by AC current inflow into the DC current detector, leading to increased CPU occupancy and costs, especially when insufficient sampling rates are used.
Innovation Solution
A power supply device with an AC voltage generator, DC voltage generator, and a DC current detector, which includes an inflow reduction mechanism such as an AC current reducer and a reverse waveform applicator to minimize AC current inflow and apply a reverse phase waveform to the DC current detector, reducing detection errors and CPU load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the DC current detector is provided in the low voltage section to detect DC current inexpensively and easily, then the detection cost is reduced, but detection error increases due to ripple voltage caused by AC current inflow
Solution Approach 1:
An AC current reducer is introduced as an intermediary component between the AC voltage generator and the DC current detector. This mediator reduces the AC current inflow to the detector, thereby minimizing ripple voltage while allowing the detector to remain in the low voltage section for cost-effective implementation
Solution Approach 2:
The AC current component is extracted and reduced separately from the DC current detection path. By removing the harmful AC ripple component through the AC current reducer before it reaches the detector, the detector can focus on accurately measuring only the DC current component at low cost
2Measurement precision
If the sampling rate is increased to suppress detection error from ripple voltage, then detection accuracy is improved, but CPU occupancy increases
Solution Approach 1:
The AC current reducer is configured to preliminarily reduce the AC current inflow before it reaches the DC current detector. This preliminary action minimizes the ripple voltage amplitude, allowing accurate detection at lower sampling rates and reducing CPU occupancy while maintaining detection precision
3Device complexity
If the AC current inflow to the DC current detector is not reduced, then the circuit remains simple, but detection error increases due to ripple voltage
Solution Approach 1:
The AC current reducer serves as a simple intermediary component that minimally increases circuit complexity while effectively reducing AC current inflow. This mediator provides the necessary ripple voltage reduction to improve detection accuracy without significantly complicating the overall circuit structure
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A power supply device that applies a voltage in which a direct-current (DC) voltage and an alternating-current (AC) voltage are superimposed on each other to a charging member that charges an image bearer, includes: an AC voltage generator (810) configured to generate the AC voltage; a DC voltage generator (820) configured to generate the DC voltage; a DC current detector (840) provided on an output terminal side of the DC voltage generator (820) and configured to detect an output DC current flowing into the image bearer; and inflow reduction means (850) configured to reduce an inflow of an AC current to the DC current detector (840).