Abstract: A dot matrix printer having a plurality of hammers on a hammerbank with a counterbalance for the hammerbank in adjacent parallel relationship to the hammerbank. The hammerbank and counterbalance are driven by a first crank arm connected to the hammerbank and a second crank arm connected to the counterbalance with looped circular portions having bearing surfaces for moving the crank arms in opposite relationship to each other. A single shaft with two eccentrics, each respectively in the bearing surfaces turns the two crank arms. The crank arms are in close parallel relationship to each other and close proximity to the hammerbank and counterbalance. The single shaft is connected to a motor for driving the hammerbank and counterbalance, and is formed with a stator having coils with a magnetic ring formed as a rotor portion surrounding the stator, and a flywheel surrounding and connected to the magnetic rotor ring.

Abstract: A dot matrix printer having a plurality of hammers forming in part a hammerbank, with a motor for driving the hammerbank, and a controller for releasing the hammers for printing on a print media. A counterbalance is mechanically linked to the hammerbank for balancing it during movement. Lands and grooves are connected for rotation with the motor. A sensor sends pulses corresponding to the lands and grooves for controlling the hammerbank movement. The hammerbank is linked to the position of the lands and grooves as mechanically connected to the motor.

Abstract: A dot matrix printer having a plurality of hammers on a hammerbank with a counterbalance for the hammerbank in adjacent parallel relationship to the hammerbank. The hammerbank and counterbalance are driven by a first crank arm connected to the hammerbank and a second crank arm connected to the counterbalance with looped circular portions having bearing surfaces for moving the crank arms in opposite relationship to each other. A single shaft with two eccentrics, each respectively in the bearing surfaces turns the two crank arms. The crank arms are in close parallel relationship to each other and close proximity to the hammerbank and counterbalance. The single shaft is connected to a motor for driving the hammerbank and counterbalance, and is formed with a stator having coils with a magnetic ring formed as a rotor portion surrounding the stator, and a flywheel surrounding and connected to the magnetic rotor ring.

Abstract: A hammer mechanism which undergoes reciprocating motion across platen-supported paper webs in a dot matrix printer effects printing by momentarily energizing coils associated with selected resilient hammer elements mounted on a common magnetic structure to neutralize a magnetic field from the common magnetic structure and release the hammer elements from a retracted position. Each end of the common magnetic structure extends to define dummy hammer positions adjacent the first hammer element on each end, providing uniform magnetic field strength to the end hammer elements and to all hammer elements in between. The hammer elements are fabricated and mounted as individual elements of resilient magnetic material with mounting of the elements being accomplished in pairs using a common plate for each pair and screws which have a portion of reduced diameter directly behind the head thereof to provide easy access to the shaft of the screw in the event of breakage during installation.

Abstract: Control of multiple hammer elements in a high speed printing system in which the hammer elements are individually operated by energizing pulses applied to electromagnets is effected by an improved regulation circuit with which additional safety features may be used in cooperative fashion. The additive combination of a full wave rectified signal and the voltage level of a storage capacitor which is being charged by the rectified signal is sensed, converted to a lower level, and compared to a voltage reference. A silicon controlled rectifier which controls charging of the storage capacitor is turned on by this circuit only when current is beginning to flow, thus providing the equivalent of zero crossing initiation and preventing high surge currents from developing. As a further feature, signals generated during times at which printing should not be taking place, such as paper advance, are used to alter the voltage reference level so as to effectively turn off the power during the turnaround interval.