Image Forming Apparatus Developing Bias Control
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Solution Overview
Problem
In conventional image forming apparatuses, the common use of an AC power circuit for all colors during monochromatic printing operations leads to toner movement from developing devices intended for color printing, affecting image quality.
Innovation Solution
An image forming apparatus with separate DC power circuits for each color and a common AC power circuit, where a constant voltage with opposite polarity to the toner is superimposed on the developing biases for colors other than black, preventing toner movement during monochromatic printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common AC power circuit is used for all colors to output AC components of developing biases, then device complexity is reduced, but toner movement from developing devices to image supporting members occurs during monochromatic printing, degrading image quality
Solution Approach 1:
The patent segments the power circuit configuration by introducing separate DC power circuits for each color (Y, M, C, K) while maintaining a common AC power circuit. This segmentation allows independent control of DC components for each color, preventing toner movement during monochromatic printing while preserving the simplicity of the common AC power circuit design.
Solution Approach 2:
The patent applies local quality by providing color-specific DC power circuits with independently controllable DC components for each color (yellow, magenta, cyan, black). This allows localized adjustment of developing bias characteristics for each color, enabling prevention of toner movement during monochromatic operations without affecting other colors.
2Manufacturing precision
If separate DC power circuits are provided for each color to prevent toner movement, then image quality is improved, but device complexity increases
Solution Approach 1:
The patent merges the power circuit design by combining separate DC power circuits for each color with a common AC power circuit. This hybrid approach provides color-specific DC control to prevent toner movement while sharing the AC power supply infrastructure, thereby improving image quality without proportionally increasing overall device complexity.
3Adaptability or versatility
If DC power circuits are provided for all colors including black, then developing bias control is improved, but unnecessary circuits are provided during monochromatic printing operations
Solution Approach 1:
The patent implements dynamic control by enabling or disabling DC power circuits for specific colors based on the printing mode. During monochromatic printing, only the necessary DC power circuit for the specific color is activated, while during color printing, all DC power circuits are activated. This dynamic adaptation prevents unnecessary circuit operation and reduces power consumption.
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 or prevents toner movement from developing devices to image supporting members during monochromatic printing, enhancing image quality by avoiding issues like white stripes and toner adhesion.
Implementation Method 1
an element provided for at least one of the colors other than black and configured to maintain a constant voltage independently from the outputs from the DC power circuits, the developing bias source configured to generate the developing biases by superimposing the AC voltage output from the AC power circuit on the DC voltages output from the respective DC power circuits and to apply the developing biases to the respectively corresponding developing devices; wherein: the constant voltage has a potential of an opposite polarity to a potential of the charged toner
Data Source
AI summary
An image forming apparatus having image supporting members and developing devices provided for a plurality of colors respectively, and a developing bias source. The developing bias source includes DC power circuits provided for the colors respectively, an AC power circuit provided for use in common for all of the colors, and an element provided for at least one of the colors other than black. The developing bias source generates developing biases by superimposing an AC voltage output from the AC power circuit on DC voltages output from the DC power circuits and applies the developing biases to the respectively corresponding developing devices. The element maintains a constant voltage having a potential of an opposite polarity to a potential of charged toner used for the development. The developing bias source further superimposes the constant voltage on the developing bias for the at least one of the colors other than black.