Variable Voltage Bias for Developing Roller Density Control
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Solution Overview
Problem
Conventional image forming devices experience a decrease in image density over time, particularly when printing high-density images, due to uneven developer supply between the developing roller and the photosensitive body, leading to insufficient developer supply and selective development issues.
Innovation Solution
An image forming device with an image acquiring unit, determining unit, and controller that adjusts the voltage between the developing roller and supply roller based on image data density, applying a first voltage for low-density areas and a second voltage for high-density areas to ensure adequate developer supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predetermined voltage is set between the developing roller and supply roller, then the developer moves in accordance with the voltage, but the image density decreases with time due to insufficient developer supply
Solution Approach 1:
The patent applies dynamics by making the voltage between the developing roller and supply roller variable rather than fixed. The control unit dynamically adjusts the voltage based on the remaining amount of developer in the developing roller, allowing the system to adapt to changing conditions over time and maintain consistent image density throughout the developer's lifespan.
Solution Approach 2:
The patent implements feedback by having the control unit monitor the remaining amount of developer in the developing roller and adjust the voltage accordingly. This closed-loop control ensures that the voltage is optimized at each stage of developer consumption, preventing image density degradation over time.
2Productivity
If the voltage is kept applied at a high voltage, then the developer moves more readily from supply roller to developing roller, but selective development occurs where strongly-charged component is more consumed
Solution Approach 1:
The patent applies parameter changes by adjusting the voltage level based on the type of developer being used. For non-magnetic two-component developers, the control unit sets a first voltage that is lower than the second voltage used for other developer types. This parameter optimization prevents excessive consumption of strongly-charged components while ensuring adequate developer supply.
3Reliability
If the developer is supplied insufficiently, then the image density decreases, but the uneven density is not sufficiently recognized as uneven printing
Solution Approach 1:
The patent applies self-service by having the control unit automatically monitor and adjust the voltage based on the remaining developer amount, eliminating the need for manual intervention or external monitoring. The system self-regulates to maintain optimal developer supply and prevent density variations before they become noticeable.
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 solution effectively suppresses the decrease in image density by ensuring sufficient developer supply to the developing roller, especially for high-density images, thereby maintaining consistent and even printing quality.
Implementation Method 1
The developer moves in accordance with a voltage between supply roller and developing roller
Data Source
AI summary
An image-forming device includes an image acquiring unit, an image forming unit, a determining unit, and a controller. The image acquiring unit acquires image data for one page. The image forming unit forms an image based on the image data. The image forming unit includes a developing roller, a supply roller, and a bias applying unit. The developing roller carries a developer. The supply roller supplies the developer to the developing roller. The bias applying unit applies a first voltage between the developing roller and the supply roller in a first mode, and applies a second voltage between the developing roller and the supply roller in a second mode. The determining unit determines whether the image data includes a part having density greater than or equal to a prescribed density. The controller controls the bias applying unit to apply the first voltage when the determining unit determines that the image data does not include the part having density greater than or equal to a prescribed density, and to apply the second voltage when the determining unit determines that the image data includes the part having density greater than or equal to a prescribed density.