Asymmetric Developing Voltage Circuit for Banding Elimination
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Solution Overview
Problem
Voltage generating devices in image forming apparatuses experience banding due to frequency differences between switching regulators, leading to undesirable patterns on recording paper.
Innovation Solution
Configuring the drive frequencies of the first and second switching regulators to ensure an absolute difference of at least a predetermined frequency, using a bridge circuit and a voltage conversion unit to generate a developing bias voltage with distinct positive and negative pulse waveforms, and employing a timing capacitor to maintain consistent oscillation frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two switching regulators are used to generate developing voltage, then the voltage generation capability is improved, but frequency differences between the regulators cause banding patterns on recording paper
Solution Approach 1:
The patent changes the frequency parameter of the switching regulators. Specifically, it sets the drive frequencies of the first and second switching regulators to be different (first frequency f1 and second frequency f2), thereby preventing the formation of beat frequencies that cause banding patterns on the recording paper
Solution Approach 2:
The patent introduces asymmetry in the operating parameters of the two switching regulators by deliberately setting their drive frequencies to be unequal. This asymmetric frequency configuration prevents synchronous interference and eliminates the periodic banding defects that would occur with identical frequencies
2Productivity
If high voltage is applied to the development gap, then the toner develops the latent image more easily, but ring marks are produced on the recording paper
Solution Approach 1:
The patent employs periodic alternating current voltage with asymmetric amplitude characteristics. The AC voltage component has a positive amplitude |Vp+| and a negative amplitude |Vp−| where their absolute values are different. This periodic asymmetric voltage application prevents ring mark formation while maintaining effective latent image development
Solution Approach 2:
The patent applies asymmetric voltage amplitudes in the AC component of the developing voltage. By setting the positive amplitude absolute value |Vp+| to be different from the negative amplitude absolute value |Vp−|, the system prevents ring mark formation on the recording paper while still achieving effective toner development of the latent image
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 configuration reduces banding in the image forming process, ensuring that the frequency difference is beyond human perception, thereby enhancing image quality by eliminating visible banding patterns.
Implementation Method 1
A voltage conversion unit is configured to convert a voltage inputted from a primary side to a voltage of a different magnitude and outputs to a secondary side
Data Source
AI summary
A power supply apparatus outputs a developing voltage in which a pulse wave shape at a time of positive amplitude is different from a pulse wave shape at a time of negative amplitude. Voltages are supplied from two switching regulators respectively to a bridge circuit for driving a transformer. Here, an absolute value of a difference between a drive frequency of a first switching regulator and a drive frequency of a second switching regulator is configured to be not less than an invisible frequency at which a banding cannot be recognized by humans.