Lexmark International, Inc.

Christopher David Strack

Matthew David Heid

Kermit Arnold Meece

Andrew Pryse Dale

Troy Dustin Tomson

Michael Craig Leemhuis

Brian Lester Boettcher

Douglas Anthony Able

Gina Marie Johns

Ahren Michael Hoy

Trey Dustin Gilliam

Jared Kuohui Lin

Christopher Michael Bennett

Jose Paul Sacoto Aguilar

Troy Dustin Smith Tomson

An imaging device includes a photoconductive drum charged by a charge roll and opposed by developer roll. The developer roll adds toner to the drum to develop a latent image on the drum for transfer to media or an intermediate transfer member at a transfer roll. One or more high voltage power supplies communicate with a controller to set voltages on the rolls. During times of non-imaging, but rotation of the drum, the charge roll charges the drum to less than a Paschen breakdown voltage of the drum. A voltage of the transfer roll is determined that corresponds to a temperature and relative humidity of an operating environment of the imaging device and the developer roll is charged based thereon. The charge of the transfer roll is set close to the charge of the drum, but higher in magnitude. A laser may also discharge the drum.

Reducing waste toner with electrophotographic voltage control in imaging devices

An imaging device includes a photoconductive drum charged by a charge roll and opposed by developer roll. The developer roll adds toner to the drum to develop a latent image on the drum for transfer to media. One or more high voltage power supplies communicate with a controller to set voltages on the rolls. The controller determines whether imaging of the media is to occur at a time when the drum is rotating. If not, a laser beam discharges the drum and the voltage on the charge roll is decreased to reduce the charge on the drum, but the controller maintains the voltage differential between the drum and the developer roll.

An imaging device has first image transfer from photoconductive drums to an intermediate transfer member (ITM) and second image transfer from the ITM to media. Transfer rolls oppose the drums from an opposite side of the ITM and electrically ground to a frame of the imaging device by mechanical connection. The rolls may be laterally offset from the drums. The ITM has relatively low surface and volume resistivity. An imaging subassembly may include the frame, the ITM, and the transfer rolls grounded to the frame.

Imaging transfer to intermediate transfer member

A cleaner assembly for an electrophotographic image forming device according to one example embodiment includes a cleaner blade having a pair of longitudinal ends and a cleaning edge that extends between the pair of longitudinal ends for contacting a surface of a photoconductive drum to remove toner from the surface of the photoconductive drum. An end seal is positioned at one of the pair of longitudinal ends of the cleaner blade. The end seal includes a front side positioned to contact the surface of the photoconductive drum and a rear side opposite the front side. A tab extends from the end seal across the cleaning edge of the cleaner blade for preventing a longitudinal end section of the cleaning edge of the cleaner blade from contacting the surface of the photoconductive drum. The tab does not obstruct the front side of the end seal.

Cleaner assembly for removing waste toner in an electrophotographic image forming device

Rubber charge roller cores are coated with loose particulate silicon carbide. Excess powder is removed, and the rollers are used in normal operation without an additional outer layer. Consistent, long-life operation of the charge roller is realized.

Coated charge roller

An improved electrophotographic printer is provided in which the voltage applied to the charge roller is automatically adjusted to compensate for its changing characteristics over its life span. A high voltage DC power supply includes an output that is connected to the charge roller, and the input side of this high voltage DC power supply is controlled by a microprocessor of the print engine. The print engine controls the output voltage of the high voltage DC power supply by changing the duty cycle of the pulse-width modulated control signal that is supplied to the input of the high voltage DC power supply. A look-up table contains the correct duty cycle for the pulse-width modulated control signal with respect to the number of prints that have been made. The result of the inspection of the look-up table is used by the microprocessor of the print engine to control the correct duty cycle for the pulse-width modulated signal. Over time, the charge roller characteristics begin to change, and after a predetermined number of prints have been made, the pulse-width modulated control signal has its duty cycle increased by a value that is provided in the look-up table. This increase in the duty cycle is performed several times over the operating life of the charge roller, in order to maintain the effective voltage applied to the photoconductive drum to a nominal value.

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Lexington, KY, United States of America

Christopher David Strack