Abstract: A vector potential generation device includes a vector potential coil formed by a solenoid coil formed by a wound conductor and a power supply electrically connected between two terminals of the vector potential coil. The vector potential coil is wound circularly around a base body, of which at least a part contacting the solenoid coil has an insulating property. The vector potential generation device is configured to pass a current through the vector potential coil to place the inside of the internal space formed by the winding structure of the vector potential coil in substantially a non-magnetic field state and to generate a vector potential in the internal space.

Abstract: A vector potential generation device includes a vector potential coil formed by a solenoid coil formed by a wound conductor and a power supply electrically connected between two terminals of the vector potential coil. The vector potential coil is wound circularly around a base body, of which at least a part contacting the solenoid coil has an insulating property. The vector potential generation device is configured to pass a current through the vector potential coil to place the inside of the internal space formed by the winding structure of the vector potential coil in substantially a non-magnetic field state and to generate a vector potential in the internal space.

Abstract: An electrostrictive revolution type ultrasonic motor includes a piezoelectric ceramic disk shaped stator and a rotor. The piezoelectric ceramic disk shaped stator has an eccentric movement via excitation by two phase pulse like voltage. The rotor is fitted around the circumference of the stator and is transmitted by a rotating torque due to the eccentric movement via frictional contact therebetween. The rotor is formed of a plastic material by injection molding to achieve a reduction of a size variation of the rotor and a stable contact with the stator. A high and stable rotating torque is thereby obtained with a reduced production cost. Further, a driving device for the ultrasonic motor which varies the frequency of a voltage applied to the ultrasonic motor in a stepped manner discriminates the magnitude of the corresponding motor currents and drives the ultrasonic motor with the frequency which causes the maximum motor current.