International Business Machines Corporation

Barry R Cavill

Charles David Malkemes

David F Dodgen

Samuel E Bigbie

Albert A Nawy

Kevin Michael Reinberg

John E Bateson

Raymond A Schulz

Earl T Brown

Robert B Steup

Raymond A Schultz

A wire fire control mechanism is provided for use in a wire matrix printer for controlling the firing of the print wires as the printhead moves across a print receiving medium. This wire fire control mechanism enables printing to be accomplished for a wide range of different printhead speeds. It also enables printing to be accomplished while the printhead is accelerating or decelerating. It further enables dots to be printed at positions which are not dependent on or limited to the fixed points defined by the emitter signals which are used to keep track of the position of the printhead as it moves across the print receiving medium. In a representative embodiment, the wire fire control mechanism includes emitter means for sensing movement of the printhead and producing emitter signals which define fixed points across the print receiving medium. The control mechanism also includes means for providing a target signal for determining a position at which a dot may be printed on the print receiving medium, such dot position not being dependent upon or limited to the fixed points defined by the emitter signals. The control mechanism further includes means for sensing the speed of the printhead and producing a flight time distance signal representing the distance the printhead will move while a print wire is in flight from the printhead to the print receiving medium. The control mechanism further includes means responsive to the target signal, the emitter signals and the flight time distance signal for producing a wire fire signal when the distance between the print wire position and the target becomes substantially equal to the flight time distance.

Wire fire control mechanism for a wire matrix printer

A control system for a printer having a print head bidirectionally movable at speeds selected from either a first group of speeds or a second group of speeds which employs a microcomputer to generate a digital signal representing the percentage of time a preselected voltage level should be applied to drive the motor which controls the print head speed. The motor includes an integral dual channel incremental optical encoder which generates a pulse each time an emitter is detected, the pulse being directed back to the microcomputer as measured speed information. The microcomputer compares the measured speed information with the desired speed information during predetermined time intervals and if they differ changes the value of the digital signal by an equal amount for each time interval until the desired speed is obtained or until a different print head speed is desired. A different method is used to determine both the measured speed information and the desired speed information depending on whether the desired speed falls within the first or second group of speeds.

Print head motor control system having steady state velocity compensation

A print head motor control system for a printer having a bidirectionally movable print head employs a microcomputer to automatically calculate print head motor parameters which are utilized to generate a motor drive voltage value for any desired print head speed. Upon powering-up of the printer, the print head is driven until contact with the left sideframe is made. A full pass from left to right is then made checking for obstructions. The print head motor is driven at a first default drive voltage value, which is assumed to drive the print head at a first preselected velocity while the first actual print head velocity is measured. The printhead motor is then driven at a second default drive voltage value, which is assumed to drive the print head at a second preselected velocity while the second actual print head velocity is measured. The first default value, first actual print head velocity, second default value and second actual print head velocity are then used to derive a voltage vs. velocity constant and a frictional value which are used to calculate the appropriate drive voltage value for any given desired print head velocity.

Print head motor control system with automatic drive parameter

A control system for a bidirectional printer having a print head carriage movable at different speeds on different printing lines employs a microcomputer which generates a desired velocity profile for the carriage motion. This desired velocity profile is continuously compared with the actual velocity and the error voltage generated is used to control pulse width modulator circuitry which supplies driving power to carriage drive motor.

Print head motor control system using analog and digital feedback

In a control system for a bidirectional printer capable of printing at different speeds on different lines, stored values representing the ideal velocities during the acceleration and deceleration of the print carriage for each direction and speed are compared with the actual values and any resulting difference is used to move the carriage velocity toward the ideal value.

Printer control system with controlled acceleration and deceleration

A control system for a bidirectional printer having a print head carriage movable at different speeds on different printing lines provides for equal stopping distance in the margin at both high and low speed operation. This is accomplished by delaying the initiation of stopping carriage motion when printing at low speed so that the carriage travels farther into the margin and this distance is controlled so as to be equal to the travel distance at the end of a line printed at high speed.

Print head motor control with stop distance compensation

In a control system for a bidirectional printer capable of printing at different speeds on different lines and in which the actual velocity of the print carriage is compared with a desired velocity profile to generate an error count, the error count is measured and averaged out for each direction and speed of carriage movement to compensate for the effect of changes in the printer system dynamics such as aging, wear, debris buildup, etc.

Printer control system with error count averaging

A microcomputer controls a ribbon drive assembly in a high speed wire matrix printer to eliminte ribbon slack, to insure proper ribbon positioning and to conduct diagnostics in conjunction with turning on the printer such as start-up time each day and after replacement of the ribbon with a new ribbon, the diagnostics checking to be sure that a ribbon is actually in the proper position, that it is threaded across the print line and also checking for proper operation of the ribbon drive, logic, and electronics. Tests are also made for proper ribbon drive during normal ribbon feeding operations.

Microcomputer control of ribbon drive for printers

A data processing system or printer subsystem is provided with facilities for detecting emitter changes that have occurred during operating intervals. In a typical operation, a microprocessor initiates a command to a moving assembly, such as a forms feed assembly, then once the operation is initiated the microprocessor transfers to other program responsibilities, meanwhile periodically checking the status of the forms feed assembly. The forms feed assembly supplies emitter signals to the processor which are utilized by the microprocessor to determine whether or not any emitter changes have occurred during the intervals between the checking operations. The microprocessor has a stored data table and logic responsive to emitter signal conditions that had previously occurred (WAS) and that is further responsive to emitter signals that are presently occurring (IS) to supply an output in numbers of emitters indicative of both the extent and direction of movement of the assembly during the intervening interval.

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Boca Raton, FL, United States of America

Barry R Cavill