Xerox Corporation

John C Dunfield

Andrew Gabor

Richard G Crystal

George W Bowers

Keith L Gnutzman

Michael G Demeny

An impact mechanism for an improved serial impact printer for delivering a printing force to drive a character element against a platen by means of a print tip movable toward and away from the platen. The print tip is supported upon a carriage mounted upon the printer for reciprocating movement in a path substantially parallel to the axis of the platen. The impact mechanism includes a bail bar extending substantially across the printer and mounted for rocking movement toward and away from the platen, its axis of rocking being substantially parallel to the axis of the platen. A prime mover is connected to the bail bar for imparting controlled rocking movement thereto. The print tip and the bail bar are interconnected so as to move the print tip toward and away from the platen as the bail bar is rocked.

Impact mechanism for quiet impact printer

An impacting element for an impact printer having a platen, selectable character elements and means for driving the impacting element to impart a printing force to a selected character element, to drive it against said platen for a contact period, the impacting element including a sensor thereon for generating a signal indicative of the initiation of the contact period.

Print tip contact sensor for quiet impact printer

An improved serial impact printer designed to substantially reduce impact noise generation during the printing operation. The printer includes a print tip relatively movable with respect to a deformable platen, with a print element, a marking ribbon and an image receptor sheet interposed between the print tip and the platen which are urged together during a controlled contact period. Movement is subject to control by a kinetic drive mechanism which applies a first force for moving the print tip relative to the platen, prior to the initiation of the contact period, for closing the gap therebetween and then applies a second force for accelerating the print tip relative to the platen, subsequent to the initiation of the contact period, for causing the print tip to deform the platen.

Quiet impact printer

A circuit for controlling the hammer velocity of an impact printer is described. A velocity sensor generates a signal which is a function of hammer position. This is compared to a reference voltage, and a drive pulse is generated if a velocity correction is needed. The sensor can be located at the backstop and used to control the hammer velocity toward zero as the position nears the backstop. If the sensor is located at the backstop, the sensor output will remain constant for following velocity as its position approaches the backstop, allowing a constant reference voltage. A table look-up can be inserted in the circuit to supply corrections, for a sensor that does not have a position dependent velocity output.

Adaptive print hammer damper

Apparatus is disclosed for controlling the movement of a movable element to bring said movable element to rest at a desired stopping position. The apparatus comprises a multi-phase drive motor having a drive shaft coupled to the movable element for driving same, a plurality of electrically conductive coils mounted in position-displaced relationship about the shaft, and means coupled to the drive shaft and responsive to the selective energization of the coils by respective motor drive signals for causing the corresponding rotation of the drive shaft and movement of the movable element. A sensor is coupled to the drive shaft and is responsive to the rotation thereof for generating an electrical signal containing information indicative of the direction, speed and distance of movement of said movable element. Further, means are included for detecting from the distance information indicated by the electrical signal whether the movable element is within a predetermined distance of the desired stopping position. When it is, a controller controls the levels of the motor drive signals in dependence upon the direction information indicated by the electrical signal.

Motion damping apparatus

Apparatus is disclosed for controlling the movement of a movable element to bring the movable element to rest at a desired stopping position. The apparatus comprises a multiphase drive motor having a drive shaft coupled to the movable element for driving same, a plurality of electrically conductive coils mounted in position displaced relationship about the drive shaft, and means coupled to the drive shaft and responsive to the selective energization of the coils by respective motor drive signals for causing the corresponding rotation of the drive shaft and movement of the movable element; a sensor coupled to the drive shaft and responsive to the rotation thereof for generating an electrical signal containing information indicative of the direction, speed and distance of movement of the movable element; means for detecting from the distance information indicated by the electrical signal whether the movable element is within a predetermined distance of the desired stopping position; and control means for controlling the levels of the motor drive signals in dependence upon the direction information indicated by the electrical signal following detection of the movable element being within the predetermined distance of the desired stopping position, the motor and thus the movable element being brought to a final stop with only a single one of the motor drive signals on.

Apparatus is disclosed which is responsive to the movement of a movable element for generating a plurality of electrically phase-displaced signals containing information indicative of the direction, speed and distance of movement of said movable element. The apparatus comprises a plurality of position-displaced electrically conductive coils and a permanent magnet mounted adjacent each of said coils for producing a path of normally substantially constant magnetic flux adjacent each of said coils. A flux varying device is coupled to the movable element and is responsive to the movement of the movable element for varying the level of the magnetic flux adjacent each of the coils in dependence upon the direction, speed and distance of movement of the movable element, whereby the resultant electromotive force induced in each of the coils defines the plurality of electrically phase-displaced signals.

Motion sensing apparatus

Apparatus is disclosed which is responsive to the movement of a movable element for generating a plurality of electrically phase-displaced signals containing information indicative of the direction, speed and distance of movement of the movable element. The apparatus comprises a plurality of position-displaced electrically conductive coils; a permanent magnet mounted adjacent each of the coils for producing a path of normally substantially constant magnetic flux adjacent each of the coils; and a flux varying device coupled to the movable element and responsive to the movement of the movable element for varying the level of the magnetic flux adjacent each of the coils in dependence upon the direction, speed and distance of movement of the movable element, whereby the resultant electromotive force induced in each of the coils defines the plurality of electrically phase-displaced signals. The flux varying device includes a rotor having a plurality of spaced teeth about the periphery thereof, the rotor being coupled to the movable element such that the rotor will rotate in a direction and at a speed corresponding to the direction and speed of movement of the movable element. The flux varying device also includes a plurality of pole pieces about which the coils are respectively wrapped, the pole pieces being mounted adjacent the path of travel of the rotor teeth such that a first gap of predetermined longitudinal extent is defined between the path of travel and each of the pole pieces, the longitudinal extent being perpendicular to the axis of rotation of said rotor.

Growing community of inventors

San Jose, CA, United States of America

John C Dunfield