Abstract: A printer hammer bank for a dot matrix or other type printer is reciprocated at high speed along a printing position by a low mass, low inertia servo-controlled drive. Precise control is maintained even though a positive drive structure is not used. A reciprocable drive mechanism supporting the hammer bank is mounted to undergo free flight with low friction along a selected axis parallel to a printing line. At each limit of movement, the drive mechanism encounters resilient stop members which reverse the direction of motion of the drive mechanism and included hammer bank following a natural cosine function of the spring mass of the stop members and with low kinetic energy loss. Losses occurring during reversal are compensated by an energy impulse from a coupled linear electromagnetic drive and an associated velocity servo system which eliminates the need for close servo control during reversal, allowing the drive mechanism to rebound naturally.

Abstract: Method and system for the constant amplitude control of an electromechanical oscillator utilizing a phase locked oscillator to generate a secondary a-c setpoint which is compared to the oscillator output to provide a difference signal which is passed as a fast-acting negative feedback signal to stabilize the amplitude.

Abstract: A solid state switching circuit for an electromagnetic pump is disclosed herein. The circuit comprises a Darlington amplifier controlling the current flow through the pump's solenoid in response to the state of a piston position sensitive electrical switch, a Zener diode and capacitance in the base circuit of the Darlington amplifier in parallel with the electrical switch and an inductive clamp circuit in parallel with the pump's solenoid coil.

Abstract: A switch control system particularly well suited for use in a electromechanical vibrator drive. Solid-state switches and diodes are used in combination with a DC power supply to alternately switch energy between the electric field of the power supply filter capacitor and the magnetic field of the actuator coil of a vibrator in a power resonant mode. The control system includes a variable frequency oscillator and a controllable pulse generator which respectively provide signals for controlling the closing and opening of the switches whereby the frequency and amplitude of movement of a vibratory feeder may be adjusted.

Abstract: An electrically damped oscillation motor having a stator component, a rotor component, a permanent magnet which provides a magnetic field across the annular gap transverse to the axis of rotation of the rotor and a drive winding for passing an electric current that interacts with the magnetic field to produce rotational deflection of the rotor. Both a tachometer winding and a compensation winding are provided in fixed relation to the drive winding, the compensation winding being located at a greater radial distance from the annular gap than the tachometer winding, and the tachometer and compensation windings being connected together in circuit so that the signal induced in the tachometer winding due to electric current flow in the drive winding is cancelled by a similar signal induced in the compensation winding, while the tachometer and compensation windings provide a net velocity signal that is used to modify the electric current flow in the drive winding to electrically damp rotational motion of the rotor.

Abstract: A hybrid blocking oscillator for an electromagnetic fuel pump is disclosed herein. The blocking oscillator embodies a temperature regulated bias control and two current dissipators for controlled dissipation of the currents induced in the solenoid and detection coils when the oscillator is in a blocked state. The disclosed hybrid circuit is capable of 5,000 hours of operation with a 99 percent reliability.

Abstract: A bearing free oscillation motor has a stator component that defines a cylindrical cavity and a rotor component with a cylindrical portion disposed within the cavity and spaced from the cavity wall by an annular gap of radial width in the range of one-five percent of the diameter of the cylindrical portion. The rotor is supported for rotation about its axis by attachment to one end of a torsion shaft that is fixed at its other end to the stator. The motor may be of either the moving coil or the moving magnet type, that is a permanent magnet provides a magnetic field across the annular gap and electric current flow through a drive winding interacts with the magnetic field to produce a torque that rotationally deflects the rotor. Disposed in the annular gap between the stator and rotor is a low viscosity liquid that produces essentially no viscous damping, for example a hydrocarbon oil, a silicone oil or a polymeric liquid.

Abstract: An electromagnetic vibrator that is resonant at a frequency below one third of the frequency of an alternating current power source is driven by a linear electromagnetic motor, the airgap of which varies with the vibration of the vibrator, in which motor current flow from the power source is established during the first half cycle of the power line voltage that occurs after the airgap is a maximum, is maintained independently of the power source during at least a major portion of the next half cycle, and is reduced to zero during the next following half cycle of power source voltage. Preferably two electromagnetic motors are employed, one for each direction of relative motion between the vibrator parts.

Abstract: A dynamic mechanical system is driven at its resonant frequency by a drive system which maintains the vibrational amplitude of the system constant. A displacement transducer senses the mechanical displacement of the system and provides a displacement signal which is used to generate a control signal related to the energy necessary to maintain the mechanical system in resonance. The zero crossover points of the displacement signal are shifted in-phase 90.degree. and used to selectively switch the control signal to provide an in-phase drive signal for the system. An offset correction system senses any asymmetry present in the displacement signal and adjusts the drive signal to compensate for such asymmetry so that the mechanical system operates about a zero point of the displacement transducer.

Abstract: An electrical vibration type compressor comprising a drive coil vibratably supported in a mechanical vibration system, a piston driven by the drive coil, at least one main semiconductor element with a control electrode which performs the switching control of a drive current to the drive coil, and a detecting means consisting of at least one detecting semiconductor element with a control electrode detecting the vibration of the drive coil to control the conduction and cutoff of the main semiconductor element with a control electrode and at least one timeconstant circuit; whereby the feedback transformer which has so far been used in a device of this type to supply a feedback current to the main semiconductor element with a control electrode is eliminated, and the switching operation is properly performed at the top and bottom dead centers of the piston.

Abstract: An electromagnetic reciprocating motor is disclosed having a minimum number of moving parts. The motor consists of a hollow, tubular guide having a first drive coil mounted about a first end, a second drive coil mounted about a second end, and a third drive coil mounted about a central portion thereof. A ferromagnetic piston is mounted in sliding engagement within the hollow guide and a ferromagnetic pivot plate is pivotally mounted on the central portion of the guide with a switching means attached thereto for alternately energizing the first or second drive coils.