Developing Device Voltage Adjustment via PWM Duty Ratio Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image forming apparatuses require significant adjustment time to reduce waveform distortion in development voltage, which can damage electrostatic latent images and cause unintended leak currents, due to the need for separate adjustments of the OFF and ON periods in the drive signal.
Innovation Solution
A processor-controlled system that detects electrostatic capacitance and adjusts the duty ratio of a PWM signal applied to the power supply circuit, allowing immediate determination and adjustment of the development voltage waveform to reduce overshoot and distortion, thereby minimizing adjustment time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate adjustments of OFF period and second ON period are performed to reduce waveform distortion, then waveform distortion is reduced, but adjustment time increases significantly
Solution Approach 1:
The patent combines the adjustment of the OFF period and the second ON period into a single unified adjustment process. By detecting the waveform distortion characteristics and simultaneously determining the optimal durations for both periods based on the same detection result, the system reduces the number of separate adjustment steps while maintaining waveform quality, thereby reducing overall adjustment time.
Solution Approach 2:
The system performs preliminary detection of waveform distortion characteristics before finalizing the drive signal parameters. By measuring the actual waveform distortion and calculating the optimal OFF period and second ON period durations in advance based on this detection, the system prepares the corrected parameters beforehand, eliminating the need for iterative trial-and-error adjustments and reducing total adjustment time.
2Productivity
If development voltage is applied to developing member, then toner adhesion to electrostatic latent image is achieved, but waveform distortion may occur causing image damage or leak current
Solution Approach 1:
The system implements a feedback mechanism by detecting the actual waveform distortion characteristics during operation and using this information to dynamically adjust the drive signal parameters. The detection circuit monitors the development voltage waveform, and the control unit modifies the OFF period and second ON period based on detected distortion, creating a closed-loop control system that maintains image integrity while ensuring effective toner adhesion.
Solution Approach 2:
The patent introduces dynamic adjustment capabilities where the drive signal parameters (OFF period and second ON period durations) are not fixed but are dynamically modified based on real-time waveform distortion detection. This allows the system to adapt to changing conditions and optimize the balance between toner adhesion efficiency and image protection, preventing waveform distortion from reaching harmful levels.
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 reduces the time required for waveform adjustment and prevents damage to electrostatic latent images by dynamically adjusting the development voltage based on real-time electrical characteristics, ensuring stable and accurate toner adhesion.
Implementation Method 1
a detection circuit that detects an electrical characteristic, which is an electrostatic capacitance generated between the image carrier and the developing member caused by the gap
Implementation Method 2
a power supply circuit that applies, to the developing member, a development voltage that adheres a developing agent carried on the developing member to the electrostatic latent image
Data Source
AI summary
An image forming apparatus controls a power supply circuit by supplying a control signal to the power supply circuit, and detects an electrical characteristic, e.g. an electrostatic capacitance generated between an image carrier and a developing member or a current caused to run by applying a development voltage to the developing member. The apparatus determines a change pattern of a duty ratio of a PWM signal including the control signal on the basis of the electrical characteristic. The apparatus changes the duty ratio as time passes according to the determined change pattern and outputs the control signal to the power supply circuit.