AC Charging Voltage Determination via Discharge Current Complex Number
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Solution Overview
Problem
Conventional methods for setting the charging voltage in electrophotographic image forming apparatuses, particularly using AC voltage charging, face challenges in accurately determining the proper AC voltage value due to noise influences and detection errors, leading to surface abrasion and non-uniform discharge issues.
Innovation Solution
An image forming apparatus that includes a charging member with a power source applying a superimposed oscillating voltage, utilizing waveform acquisition and fast Fourier transformation to calculate complex numbers from current and voltage waveforms during non-discharge and discharge, allowing for precise determination of the AC voltage value for optimal charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the discharge current amount is excessively large, then the surface potential uniformity is improved, but the surface abrasion of the photosensitive member increases
Solution Approach 1:
The patent implements feedback control by detecting the discharge current amount through waveform acquisition and Fast Fourier Transformation, then using this information to adjust the charging voltage. The controller modifies the AC voltage component based on the detected discharge characteristics, creating a closed-loop system that maintains uniform surface potential while preventing excessive discharge current that would cause abrasion.
Solution Approach 2:
The patent changes the electrical parameters of the charging system by adjusting the AC voltage component and charging frequency. By modifying these parameters dynamically based on discharge detection results, the system optimizes the balance between achieving uniform charging and avoiding excessive discharge current, thereby reducing surface abrasion while maintaining potential uniformity.
2Object-affected harmful factors
If the discharge current amount is excessively small, then the surface abrasion is reduced, but the surface potential uniformity deteriorates
Solution Approach 1:
The feedback mechanism detects discharge current characteristics and uses this information to adjust charging voltage parameters. When discharge current is found to be insufficient, the system increases the AC voltage component or adjusts frequency to enhance discharge, thereby improving surface potential uniformity while avoiding excessive abrasion through controlled adjustment rather than arbitrary high-voltage application.
Solution Approach 2:
The patent introduces dynamic adjustment of charging voltage parameters based on real-time discharge detection. Rather than using fixed voltage levels, the system adaptively modifies the AC voltage component and charging frequency according to the detected discharge characteristics, enabling optimal balance between uniform charging and abrasion prevention.
3Stability of the object's composition
If the AC voltage value is increased to improve charging uniformity, then the discharge current amount increases, but the detection accuracy decreases due to noise
Solution Approach 1:
The patent replaces direct voltage measurement with waveform-based detection and Fast Fourier Transformation analysis. Instead of measuring discharge current directly at high voltage conditions where noise interferes, the system analyzes the temporal waveform characteristics and transforms them into the frequency domain, enabling accurate extraction of discharge current information even in noisy high-voltage environments.
Solution Approach 2:
The patent transforms the discharge current measurement from the time domain to the frequency domain through Fast Fourier Transformation. By converting the time-domain waveform into frequency-domain spectral components, the system can accurately identify and measure discharge current characteristics at specific frequencies, separating signal from noise and improving detection accuracy in high-voltage conditions.
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 enables accurate detection of discharge current and setting of the charging voltage, reducing surface abrasion and ensuring uniform discharge, thereby improving image formation quality and extending the lifespan of the photosensitive member.
Implementation Method 1
a power source portion configured to apply, to the charging member during image formation, a charging voltage which is a superimposed oscillating voltage including a DC voltage and an AC voltage
Implementation Method 2
positive and negative voltages are alternately applied, so that negative discharge and positive discharge ('AC discharge') are repeated
Implementation Method 3
by subjecting each of the current waveform in non-discharge and the voltage waveform in non-discharge to fast Fourier transformation
Implementation Method 4
a charging device for charging the photosensitive member under application of a charging voltage to a charging member by causing the charging member to be in contact with or in proximity to the surface of the photosensitive member
Implementation Method 5
a deteriorated portion of the surface of the photosensitive member is abraded and worn by friction with a contact member such as a cleaning blade contacting the photosensitive member
Data Source
AI summary
An image forming apparatus executes processing for calculating a complex number of a discharge current waveform which is a discharge current component of a current waveform in discharge based on a first complex number at an analyzing frequency near a charging frequency of a current waveform in non-discharge, a second complex number at the analyzing frequency of the current waveform in non-discharge, a third complex number at an analyzing frequency of the current waveform in discharge, and a fourth complex number at the analyzing frequency of the current waveform in discharge, and then for determining an AC voltage value of a charging voltage during image formation based on a calculation result of the complex number of the discharge current waveform. The controller controls a power supply portion to apply, to the charging member, the charging voltage including an AC voltage component with the determined value.