Nec Corporation

Tadao Uchikawa

Osamu Myohga

Takeshi Inoue

Osamu Ohnishi

Sadayuki Takahashi

Takashi Oota

Kazutoshi Wakamatsu

Naoto Okihara

Kunio Kitagawa

Yoshiki Aihara

Isao Kagaya

Sadayuki Ueha

An ultrasonic motor comprises a stator which generates a combined ultrasonic elliptic vibration which is a combined vibration of longitudinal and torsional vibrations, and a rotor which is in press-contact with the stator and driven by the ultrasonic elliptic vibration via a friction force between the rotor and the stator. The stator comprises a first piezoelectric element for generating the longitudinal vibration, a second piezoelectric element for generating the reacting vibration, a headmass having a large stiffness against said longitudinal vibration and a large inertial mass against the torsional vibration, and a rearmass. In the ultrasonic motor, the resonance frequencies of the longitudinal and torsional vibrations are equal, so that the ultrasonic elliptic vibration is generated efficiently on the rotor in a high power state which is adapted in practical use.

Ultrasonic motor

In an ultrasonic motor which uses, as a stator, a longitudinal-torsional composite vibrator in which longitudinal and torsional piezoelectric elements are sandwiched between two blocks, and urges a rotor against the stator, a member is arranged on a piezoelectric element side of the block located near the rotor, so that an inertial mass of the member becomes larger with respect to torsional vibration than that of a rotor side.

An ultrasonic motor has a longitudinal-torsional composite transducer, a stator constituted by an ultrasonic vibrator sandwiching the transducer, and a rotor urged against the stator. The stator excites longitudinal-torsional ultrasonic vibrations to rotate the rotor by a frictional force. The motor includes a vibration adjusting rod for matching resonance frequencies of longitudinal and torsional ultrasonic vibrations of the stator with each other.

Ultrasonic motor and method of adjusting the same

This invention provides an ultrasonic motor using a bolt-tightened Langevin type torsional vibrator as a stator. The stator produces a vibrational energy to be converted into a rotational energy for a rotor contacted with the stator. The rotor is provided between a piezoelectric actuator and the torsional vibrator so that the contact state between the rotor and the torsional vibrator is controlled either one of loose contact and tight contact therebetween. According to the present invention, since the piezoelectric actuator is slidingly combined to the rotor, the rotation energy is not applied to the piezoelectric actuator and thus the life time of the actuator becomes long.

In a printing hammer which is for use in a printer head and comprises a piezoelectric actuator (16) coupled to a base member (15) by a resilient coupler (23), an arm (19) carrying a printing wire (26), and a first resilient hinge (21) coupling the piezoelectric actuator to the arm, first and second resilient parts (221, 222) are used collectively as a second resilient hinge which couples the arm to the base member. The first and the second resilient parts are both sides of the first resilient hinge on a single plane which has a step of a predetermined size relative to the first resilient hinge in a direction of its thickness. The piezoelectric actuator may be fixed directly to the base member in order to give the printing hammer a high printing speed. Preferably, the first resilient hinge and the first and the second resilient parts are manufactured separately of the arm and/or the base member and brazed in grooves formed in a thick arm end with a spacing of the predetermined size, in a groove formed in an actuator block of the piezoelectric actuator, and in grooves formed in a pair of side legs of the base member. The first resilient hinge may have a T form with the top stroke of the T form brazed in the groove. The first and the second resilient parts may be both branches of a U form.

Printing hammer comprising two hinge parts coupling an arm to a base

A piezoelectric transducer for a printing pin of a dot-matrix or an armature of a relay drives a mechanical amplification mechanism having a base plate with a reference wall that is to be fixed to a frame. An elongated piezoelectric transducer element extends in the direction of its expansion between the base plate and a lever arm. A lever arm has a first end portion coupled to an end of the piezoelectric transducer element, which is remote from the base plate. The lever arm is fixed to the second portion of the base plate by a fulcrum member located at a position near the first end. A band spring has one end coupled between the second end portion of the lever arm and the base plate. An actuating element is fixed to substantially a central portion of the spring. The actuating element may be either a printing pin of a dot-matrix or the moving contact of a relay.

Mechanical amplification mechanism for electromechanical transducer

Disclosed is a piezoelectric actuator comprising a pair of piezoelectric elements, bistable snap-action means, and projectile means attached to the snap-action means in an impact receiving relationship alternately with the piezoelectric elements. The projectile means has a mass sufficient to acquire an acceleration upon impact from each of the piezoelectric elements to cause the snap-action means to change state. The snap-action means may comprise an elongated bending element squeezed endwise between supports, the projectile means being carried by bending element at a point intermediate its ends.

Piezoelectric latching actuator having an impact receiving projectile

A mechanical amplification structure has a pair of L-shaped lever arms mounted for rotational motion about individually associated pivot points on a frame. An elongated transducer (e.g. piezoelectric or electrostrictive) expands or contracts responsive to electrical signals, the transducer being coupled to swing the lever arms about the pivot points. Thus an excursion distance between the swinging ends of the lever arms is equal to the expansion or contraction of the transducer multiplied by an effective length of the lever arms. An elastic support is coupled between the swinging ends of the arms to experience controlled mechanical excursions responsive to the electrical signals. A mechanical actuator is mounted on the elastic support for giving a mechanical action in response to an operation of the actuator means. As shown, the actuator is a printing needle in one embodiment and a relay contact in another embodiment.

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Tokyo, Japan

Tadao Uchikawa