Xerox Corporation

Louis H Chang

John C Fravel

Frank D Ruble

Carl E Herendeen

Harunori Yoshikawa

A serial printer comprises a carriage, a print member rotatably mounted to the carriage and including a plurality of character elements, a first drive coupled to the print member for rotating the print member to a desired rotational position in order to place a selected character element at a printing position adjacent a record medium to be printed upon, a second drive coupled to the carriage for moving the carriage along a predetermined path whereby the print member is caused to move to a desired printing position along the path, a first servo control coupled to the first drive and responsive to a first set of input data and instructions for controlling the direction and speed of rotation of the print member, a second servo control system coupled to the second drive and responsive to a second set of input data and instructions for controlling the direction and speed of movement of the carriage, and a programmed data processor coupled to the first and second servo control system for supplying at least some of the first set of input data and instructions under program control to the first servo control system and at least some of the second set of data and instructions to the second servo control system.

Control apparatus for serial printer

A serial printer comprises a carriage, a print member rotatably mounted to the carriage and including a plurality of character elements, a first drive coupled to the print member for rotating the print member to a desired rotational position in order to place a selected character element at a printing position adjacent a record medium to be printed upon, a second drive coupled to the carriage for moving the carriage along a predetermined path whereby the print member is caused to move to a desired printing position along the path, a first servo control coupled to the first drive means and responsive to a first set of input data and instructions for controlling the direction and speed of rotation of the print member, second servo control means coupled to the second drive and responsive to a second set of input data and instructions for controlling the direction and speed of movement of the carriage, and a programmed data processor coupled to the first and second servo control system for supplying at least some of the first set of input data and instructions under program control to the first servo control system and at least some of the second set of data and instructions to the second servo control system.

A serial printer comprises a carriage, a print member rotatably mounted to the carriage and including a plurality of character elements, a drive coupled to the print member for rotating the print member to a desired rotational position, a device coupled to the print member for generating a plurality of periodic position signals each indicative of the rotational movement of the print member, and a device for storing a count indicative of the actual rotational position of the print member, the device for storing including a device responsive to an increment pulse for incrementing the count by one and a device responsive to a decrement pulse for decrementing the count by one. An increment-decrement device is coupled to the device for generating and is responsive to the position signals for generating an increment pulse at a predetermined point during the period of a predetermined one of the position signals during rotation of the print member in one direction and a decrement pulse at said predetermined point during rotation of the print member in the opposite direction. The increment-decrement device includes a device for inhibiting the generation of a predetermined increment pulse that would normally occur when the print member has been rotated too far and overshoots the desired rotational position by a predetermined amount and then is returned to the desired rotational position. The printer further includes a device responsive to the count and to a signal representative of the desired rotational position of the print member for controlling the direction and speed of rotation of the print member.

Increment-decrement logic for serial printer

A serial printer comprises a carriage, a print member rotatably mounted to the carriage, drive means coupled to the print member for rotating the print member in a desired direction and at a desired speed, and control apparatus coupled to the drive means for generating a control signal to control the direction and speed of rotation of the print member. The control apparatus comprises means coupled to the print member for generating a first signal indicative of the rotational movement of the print member, means responsive to a second signal indicative of a command to position the print wheel at a predetermined reference rotational position for applying a predetermined control signal to the drive means to rotate the print member in a predetermined direction and at a predetermined speed, means operatively associated with the print member for generating a third signal each time a predetermined portion of the print member is rotated past a predetermined reference location, means coupled to the means for generating a first signal and to the means for generating a third signal for comparing the first signal with a predetermined third signal representative of a predetermined number of rotations of the print wheel portion past the predetermined reference location, and means coupled to the means for comparing and responsive to the first and predetermined third signals bearing a first relationship for disabling the means for applying in order to stop the print member at the predetermined reference rotational position and responsive to the first and predetermined third signals bearing a second relationship for enabling the means for applying to continue to apply the predetermined control signal to the drive means in order to continue to rotate the print member in the predetermined direction and at the predetermined speed.

Position retry apparatus for serial printer

In a serial printer comprising a carriage movable along a predetermined path, a print member rotatably mounted to the carriage and including a plurality of character elements, first drive means coupled to the print member for rotating the print member to a desired rotational position, second drive means coupled to the carriage for moving the carriage to a desired position along the path, and control apparatus coupled to the first drive means for controlling the direction and speed of rotation of the print member and coupled to the second drive means for controlling the direction and speed of movement of the carriage, the control apparatus comprising first means for receiving and storing a first signal indicative of the desired rotational position of the print member, second means for receiving and storing a second signal indicative of the desired linear position of the carriage, means coupled to the first and second means for receiving and storing for generating a third signal if the first signal was received before the second signal, and means coupled to the means for generating and responsive to the third signal for controlling the first drive means to rotate the print member to the desired rotational position before controlling the second drive means to move the carriage to the desired linear position.

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San Jose, CA, United States of America

Louis H Chang