Electrophotography – Diagnostics – Consumable
Reexamination Certificate
2000-11-28
2002-10-15
Tran, Hoan (Department: 2852)
Electrophotography
Diagnostics
Consumable
C399S053000, C399S258000, C399S259000
Reexamination Certificate
active
06466749
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to image forming devices.
2. Description of Related Art
Toner particles are used with a transfer drum or development roll to create patterns on a recording medium. To enable electrostatic charging and transfer of toner particles, the toner is mixed with carrier beads of opposite polarity. Carrier material generally comprises low friction beads that interact with the toner particles to ensure proper charging and even toner flow.
Developer results when toner particles are mixed with carrier material in the appropriate ratio. Developers in cartridges or in housings are replaced when either the toner or the carrier degrades to an unacceptable level. Conventionally, toner and carrier are mixed at a ratio of 75% carrier to 25% toner, initially forming a mixture called replenisher. Replenisher can then be added to developers in cartridges or in housings to extend the life of the developer by replacing the carrier material at the same time toner is added. Spent developer is gathered into a waste container for disposal.
SUMMARY OF THE INVENTION
This invention relates to systems and methods for dynamically adjusting the ratios of toner and carrier added to a developer mixture.
For example, low area coverage images require little toner. However, the developer is churned the same amount regardless of the amount toner used, to ensure good quality printing. Thus, when forming a low area coverage image, the carrier is aged more than in a high area coverage image. The systems and methods of this invention adjust the ratios of toner and carrier added depending on the area coverage or density of a particular image. Thus, the time between replacement of the developer or developer cartridge can be increased, leading to better quality images at a lower cost.
These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention.
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Tran Hoan
Xerox Corporation
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