Hewlett-Packard Company

Hewlett-Packard Development Company, L.p.

Christopher M Lesniak

Algird M Gudaitis

Rick Minoru Tanaka

Donald R Bloyer

Stephen A Smith

Beverly Loh

Steven H Walker

Mark S Hickman

Richard Alan Kelley

Steven P Downing

Paul William Martin

Gary L Miller

Sandra Y Okazaki

David K Klaffenbach

Jason Grosse

Cathy A Rotering

Jeffrey S Mathena

A media handling system for delivering media sheets to be printed from a staging location to a drum along a media path, including: at least one drive roller positioned along the media path between the staging location and the drum; a sensor positioned along the media path between the at least one drive roller and the drum; and, an encoder that provides an output responsive to the sensor; wherein, when the at least one drive roller advances a media sheet from the staging location to engage the drum, the sensor detects a position of the advancing media sheet prior to engaging the drum, and the rate of further advancing of the media sheet to engage the drum by the at least one drive roller is dependent upon the encoder output.

Media handling system and method

In one embodiment, a system and method pertains to detecting a position of a sheet of media that has been loaded onto the print surface, determining from the detected position a current loading error with which the media sheet has been loaded onto the print surface, and calculating a loading offset that can be used to adjust the position at which a future media sheet will be loaded onto the print surface.

Systems and methods for adjusting loading of media onto a print surface

Various embodiments of a sheet separation system are disclosed.

Sheet separation using two torque motors

An optical encoder includes a planar surface comprising an insulator material. An optical encoder pattern partially occupies the planar surface. The encoder pattern has at least one continuous geometry and is made from a conductive material.

Optical pattern for an optical encoder

Two motors are used to provide motion control in a transport drive system. A primary motor, or a primary and secondary motor, provides primary power for accelerated motion. PWM signals are used to drive the motors according to predetermined fixed functions related to acceleration, deceleration and hold of a load. Alternatively, during onset of large or high speed moves, the primary and secondary motors are on in tandem. During deceleration of a move, the torque provided by the secondary motor is reversed, providing active braking and ensuring the drive train remains loaded wherein backlash is eliminated. During a driver hold phase, the primary and secondary motor push against each other to actively control positioning.

Active damping and backlash control for servo systems

Discussed herein is a method of positioning a printer's drive roller relative to the printer's printhead. The printhead has rows of individual print elements arranged to apply transverse dot rows to a print medium. To print at a desired location on the print medium, the printer initiates a first drive roller advance to the desired location, at a relatively fast slew speed. Assuming some overshoot or undershoot occurs, the printer then determines the actual position error of the drive roller, and selects a set of the printhead rows that correspond most closely in position to the desired print location. The printer then initiates a second drive roller advance, at a relatively slow speed, to position the selected group of printhead rows accurately over the desired print location on the print medium. These printhead rows are then used to perform the actual printing. The slow speed of the second drive roller advance ensures high positioning accuracy. However, the distance of this advance is limited because of selecting the closest set of printhead rows. This decreased distance decreases the overall time consumed by drive roller advances.

Printer drive roller positioning

A simple, yet accurate way of determining calibration values for correcting the characteristic sinusoidal feed errors of a printer or other recording device (such as a fax machine, plotter, etc.). A sheet of calibration media is employed for facilitating the calculation of the calibration values. The sheet is used in a way that prevents the calibration media errors from affecting the calculation. In particular, the sheet of calibration media is fed twice through the printer, and position data is collected each time. The data is processed in a way that cancels the attendant calibration media errors so that the calculated calibration values precisely correct the characteristic sinusoidal feed errors of that printer.

Calibration of a media advance system

Calibration of a media advanced system

A method of controlling a media-advance drive motor of a printer in a manner that preserves accuracy in the incremental advances of print media between printing swaths, while optimizing throughput and accounting for variations in printer system response characteristics. A printer control algorithm commences each media-advance step by accelerating the media-advance drive motor to a maximum velocity. The motor is thereafter decelerated by controlling the drive voltage to the motor as needed to conform to a predetermined decaying velocity versus position function that is representative of a specimen system. The velocity versus position function is correlated to the required media position so that a media-advance motor following that function will arrive at a zero velocity at the precise instant that the media arrives at the position representing the end of its incremental advance.

Media advance system for a printer

A method of calibrating a media advance mechanism in a printer utilizes an optical sensor of the printer to detect printed marks on a calibration sheet. The marks on the calibration sheet are spaced at actual longitudinal intervals. The calibration sheet is advanced longitudinally past the printhead carriage, and the calibration marks are detected with the optical sensor. The printer determines the apparent or measured longitudinal intervals and compares them to the actual intervals to determine errors in positioning the calibration sheet.

Linefeed calibration using an integrated optical sensor

A print media ejection system actively pushes a media sheet trailing edge into an output tray. The ejection system includes a movable pivot which supports a media sheet within a print zone during printing. Upon completion of printing the pivot moves downward allowing the current media sheet to slide from the pivot into the output tray. After the pivot completes the downward rotational stroke, the pivot rotates back upward to be in position to support the next media sheet. The upward motion of the pivot mechanism actuates a kicker device to rotate toward an output region. The kicker device drives any remaining portion of the media sheet into the output tray.

Print media ejection kicking after paper drop

A printer mechanism to control pen-to-print medium spacing during printing is described. The preferred embodiment of the mechanism includes a printhead and an adjacent platen. The platen includes differentially yieldable structure adapted to resiliently support the print medium thereby to inhibit uncontrolled bending of the print medium during printing. The yieldable structure preferably extend along a line generally perpendicular to a direction of feed of the print medium. The platen may further include a transition region located adjacent the yieldable structure, the transition region adapted to facilitate smooth transition of the leading edge of the print medium onto the yieldable structure.

Print medium handling system including cockle springs to control

This invention involves to a method for measuring drop-volume in an ink-jet printhead. A series of print samples comprised of multiple drops of ink are printed on a recording media. The number of ink drops per sample is reduced for subsequent print samples to produce a series of print samples with varying amounts of ink content. The samples include a solid character to help contrast the increasingly ink depleted regions. The series is visually or optically analyzed to detect changes in optical density among the individual print samples. From these changes, the drop-volume for an ink-jet printhead can be determined. A printing system for automatically self-analyzing and self-correcting for drop-volume is also described.

Growing community of inventors

Vancouver, WA, United States of America

Christopher M Lesniak