Lexmark International, Inc.

Matthew Lowell McKay

Danny Keith Chapman

Paul Douglas Horrall

Gregory Lawrence Ream

Michael David Maul

Phillip Byron Wright

Edward Alan Rush

Philip Jerome Heink

Mark Andrew Omelchenko

Cyrus Bradford Clarke

Bryan Michael Blair

Robert Leonard Burdick

Steven Michael Turney

James Allen Lokovich

Thomas Wilbur Blanck

Kurt Matthew Korfhage

A single-pass color electrophotographic printer includes four imaging stations, yellow, cyan, magenta, and black, on a generally linear path. A toned image in each toner color is developed on an image bearing member or photoconductive drum. A plurality of electrically biased first transfer rollers associated with each imaging station is operative to transfer the developed images from the photoconductive drum to an intermediate transfer member (ITM) belt that travels sequentially past the imaging stations along the generally linear path in a first transfer operation. The image on the ITM belt is transferred to media at a second transfer operation at which the ITM belt passes through a nip between a backup roller and a further electrically biased transfer roller. A servo operation is used to set the voltages on the transfer rollers. Rollers at the second transfer are positioned to direct media downwardly out of the nip to a media transport belt and to a fuser assembly. A reverse roller is provided downstream of the second transfer operation to shift the path of the ITM belt away from the media guide plate and media transport belt. The ITM belt is formed of a resistive material having a uniform thickness and high tensile modulus.

Intermediate transfer member belt/roller configuration for single-pass color electrophotographic printer

An improved printing apparatus provides for very accurate synchronization between cut sheet print media and the unfixed image which is conveyed on an Intermediate Transfer Member (ITM) such as a belt or a drum, and which is targeted for said print media. The printing apparatus is constructed as a single-pass ITM-based electrophotographic (e.g., laser) printer, and the length of the input print media pathway prior to image-to-media transfer is significantly shorter than the sum of the lengths of the image travel along a photoconductive drum and ITM. The print media is typically launched after imaging has been initiated on the photoconductive drum by an imaging apparatus. Variance in the leading edge of the print media with respect to the leading edge of image can be introduced due to phenomena such as pick errors, velocity variation, and uncertainties in the paper stack height. The present invention minimizes this leading edge variance to a tightly targeted specification by accurately sensing the positions of the print media and the ITM image, and correcting the print media's position by controlling the velocity of the print media prior to arriving at the transfer nip. In addition, the present invention detects the presence of print media within the sheet feeder cassette tray before imaging is started in the ITM belt, thereby minimizing the amount of waste toner generated by the printing apparatus. The imaging procedure on the ITM belt typically begins at a time prior to the printer controller having precise knowledge as to the location of the &ldquo;next&rdquo; sheet of print media within the combination of the input print media pathway and sheet feeder cassette tray.

Method and apparatus for controlling media-to-image registration of a single-pass intermediate transfer member-based printing apparatus

A method of minimizing error in an estimate of a position of a sheet of print medium in an electrophotographic machine includes providing a transport system including a gearing system to drive a roll for moving the sheet of print medium along a print medium path. The gears are in constant mesh with each other and with an actuator. The electrophotographic machine is provided with a toner transfer point at which the toner can be transferred to the moving sheet of print medium. A sensor is placed at a set distance away from the transfer nip along the print medium path. This distance is approximately equal to an integer multiple of the resulting distance traveled by the medium during one revolution of the lowest frequency component of the transport system. The frequencies associated with all other components in the transport system, including the actuator and an encoder wheel, are designed to be an integer multiple of this lowest frequency. The gearing system is actuated with a rotating actuator such that the actuator rotates approximately an integer number of times during a corresponding rotation of the lowest frequency component. An encoder wheel is also used to provide feedback to a control algorithm. A position of the sheet of print medium is sensed with the sensor.

Method and apparatus for minimizing the open loop paper positional error in a control system for an electrophotographic printing apparatus

A toner fuser system suitable for producing high quality color transparencies is provided. The fuser system includes a media conditioning assembly located directly downstream of a fuser assembly, which may be a roll fuser or an instant-on belt fuser. The conditioner assembly includes a convective heat source, a heating zone, and a convective circulation path past the heat source and the heating zone to provide convective heat transfer to a transparency in the heating zone. A transparency (or other media) with toner to be fused travels on a media path first through the fuser assembly and then through the heating zone of the conditioner assembly. The fuser assembly causes toner to adhere to the transparency just well enough to allow the transparency to pass into the conditioner. In the conditioner, the toner is reheated, thereby causing the surface of the toner to reflow into a smooth, glossy, and uniform surface that increases light transmission efficiency of color transparencies. Additionally, the system eliminates the need for silicone oil, which is used in some prior art systems to prevent sticking of the transparency to the fuser assembly.

Toner fuser system having post-fuser media conditioner

A method of determining an output level of an output stack of print media in an image forming apparatus. The print media is transported, one print medium at a time, to the output stack. A sensor positioned in association with the output stack senses when the output level of the output stack has reached a near full level. At least one physical characteristic of the print media is identified which can affect the stacking of the print media. The number of the print media transported to the output stack is counted after the near full level is sensed. A determination that the output level of the output stack has reached a full level is made, dependent upon each of the at least one physical characteristic and the counted number of the print media.

Method and system of sensing an output level of an output stack of print

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Lexington, KY, United States of America

Matthew Lowell McKay