A plural phase stepping motor control circuit in which damping is accomplished by energizing a previously energized phase prior to the expiration of the power cycle on a pair of other phases. The duration of the damping pulse is inversely proportional to the speed of operation. The logic involved allows for forward or reverse running. A sprocket latch circuit locks out spurious overshoot responses, such as may be caused by vibration, damaged tape, or other irrationality.
A bidirectional stepping motor drive circuit receives stepping pulses and a directional control signal. A binary up/down counter counts the stepping pulses in an up or down direction depending on the state of the directional control signal. A BCD to decimal decoder has inputs coupled to the counter and generates selected outputs in response to selected states of the counter. Logic means responds to the selected outputs and generates phase voltage pulses during which current is supplied to the motor coils. A high voltage starting pulse is applied at the beginning of each stepping cycle to establish the coil current.
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.
An electric motor drive system comprised of a main winding providing energizing current in a rectilinear wave form. The wave form has energization intervals. The electric motor drive system is also comprised of an auxiliary winding providing a first spiked pulse and a second spiked pulse which oppose each other, and each of which have an essentilaly instantaneous leading edge corresponding to a given energization interval. In a preferred embodiment, the leading edge of the first spiked pulse corresponds to the rise of the corresponding energization interval, and the leading edge of the second spiked pulse corresponds to the fall of the energization interval.
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.
A method of damping resonances in a rotating system is disclosed, which includes developing a representation of vibrating movement in the rotating system, taking the derivative of that representation and applying an out-of-phase active damping force based on the derivative to the rotating system to damp out the movement.
