US 3,950,685 A · DC motor position controller

Abstract

A system enables selective control of instantaneous motor armature position and, thus, the corresponding position of one or more elements driven by the motor. As utilized in a high speed printer, the system governs positioning of a printhead, enabling high speed movement of the latter from one location to the next and yet bringing it to a complete stop exactly at a selected or desired location. Additionally, the system enables position control with respect to movement over different predetermined distances such as, in the printing embodiment, of character or word spacings, carriage returns, tab sets and vertical indexing. Operationally, armature position-representative pulses are counted and analyzed to determine during acceleration when one desired position has been reached and, during subsequent deceleration, to determine when zero movement has been reached. At least during deceleration, the system also monitors corresponding change of position and adjusts the speed of movement as necessary so that, ultimately, a desired stop position is reached. As embodied, the count information also is utilized to accomplish such functions as carriage return and margin correction.

Claims20

Dependent claims

In apparatus in which a reversible motor drive controls a motor to an instrumentality at selected ones of a plurality of predetermined, successively spaced positions, a control system comprising:

sensing means responsive to movement of the rotor of said motor drive for developing pulses representative of the rate of movement of said rotor;
a counter responsive to said pulses for totalizing the number of said pulses;
a first decoder responsive to totalization of a predetermined number of said pulses for developing an acceleration limit signal;
a second decoder responsive to totalization of another predetermined number of said pulses for developing a deceleration limit signal;
and
direction sensitive means cyclically operable in response to said first and second decoders for effecting forward and reverse driving of said motor drive in an initial acceleration mode until occurrence of said acceleration limit signal and thereafter effecting a controlled deceleration of said motor correlated with its acceleration to the acceleration limit signal and for removing energization of said motor in response to said deceleration limit signal.

3 more elements

In a matrix printer in which a printhead driven by a motor is alternately accelerated and decelerated between successive print positions, a control system for said motor comprising:

means for developing pulses representative of motor armature position;
means for counting and analyzing said pulses to determine, during acceleration, when one desired location-related speed has been reached and to determine, during subsequent deceleration, when zero motor armature speed has been reached;
motor control means for controlling the forward and reverse direction of energization of said motor upon the reaching of said desired location-related speed;
and
monitoring means for monitoring the change in direction of energization of said motor armature, at least during deceleration, to regulate the rate of deceleration of said motor armature as necessary to effect occurrence of said zero motor armature speed precisely in correspondence with a predetermined print position.

2 more elements

In a matrix printer in which instantaneous printhead position is represented by the instantaneous rotational position of a driving motor, said printhead having a plurality of print wires arranged in at least one column, a control system comrising:

pulse means for developing motor movement-representative pulses;
incremental counter means responsive to the pulses developed to count up and down through each character as it is printed by said print wires;
means for accelerating said motor over a predetermined number of counts to a maximum velocity in printing each character;
means establishing a series of reference speeds for the remaining number of counts after reaching maximum velocity for controlled deceleration to zero at the end of each character;
monitoring means including means establishing a series of reference speeds including speed detector means to compare the speed of the motor with the reference speed at each of the remaining counts and to indicate an overspeed or underspeed condition;
and
means responsive to said speed detector means to effect a correction in actual motor speed causing it to correspond with the reference speed whereby to produce a controlled deceleration and ultimate cessation of motor rotation at the end of each character.

4 more elements

Dependencies are inferred from the claim text.

DC motor position controller

Life of this patent

DC motor position controller

Life of this patent

Abstract

Claims20