Developer Transporting Member Velocity and Bias Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In image forming apparatuses using an electrophotographic system, high-density mode operations often result in uneven density images due to uneven toner supply from the supply roller to the developing roller, especially when an elastic sponge is used as the supply roller material, leading to toner exhaustion and uneven toner layer thickness.
Innovation Solution
The apparatus performs two distinct image forming operations with different peripheral velocity ratios and adjusts the developing and supply biases to control the urging force direction, ensuring consistent toner supply by altering the potential difference between the developing and supply biases, thereby preventing toner exhaustion and uneven density images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of supplied toner per unit area is increased to increase density or color gamut (high-density mode), then the image density and color gamut are improved, but the toner inside the supply roller is exhausted and uneven density images occur
Solution Approach 1:
The patent applies dynamics by making the peripheral velocity ratio of the developing roller variable rather than fixed. The control unit adjusts the rotation speed of the developing roller to set different peripheral velocity ratios (first, second, third ratios) corresponding to different image density requirements. This dynamic adjustment allows the system to optimize toner supply characteristics for different operating modes, preventing toner exhaustion and uneven density images while maintaining the ability to produce high-density images when needed.
2Adaptability or versatility
If the rotation speed of the developing roller is changed to change the peripheral velocity ratio, then the selection range of tinge is increased, but the toner supply uniformity deteriorates in high-density mode
Solution Approach 1:
The patent applies parameter changes by systematically varying the peripheral velocity ratio parameter across multiple discrete values (first, second, third ratios). Each velocity ratio corresponds to specific image formation requirements, allowing the system to adapt toner supply characteristics to different operating conditions. This parameter-based control enables the system to maintain toner supply uniformity while providing versatility in image density and tinge selection.
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 effectively reduces the occurrence of uneven density images during high-density mode operations by optimizing toner supply, ensuring consistent image quality and preventing toner exhaustion within the supply roller.
Implementation Method 1
a bias applying portion that applies a bias to the supply roller and the developing roller; the urging force is generated by a potential difference between a supply bias and a developing bias
Implementation Method 2
the toner is supplied to the developing roller while being friction-charged by the mechanical rubbing between the supply roller and the developing roller. The supplied toner is controlled to have a certain thickness on the developing roller by a developer control member, and then transported to a developing region
Data Source
AI summary
An image forming apparatus is capable of performing a second image forming operation in which a peripheral velocity ratio of a developer bearing member to an image bearing member becomes greater than that in a first image forming operation, and in which a potential difference between a developing bias applied to the developer bearing member and a supply bias applied to a supply member becomes a potential difference at which a urging force causing a developer at the contact portion between the developer bearing member and the supply member to move from the supply member to the developer bearing member becomes smaller than that in the first image forming operation, or becomes a potential difference at which a urging force causing the developer to move from the developer bearing member to the supply member is generated.