Abstract: A rotary solenoid includes a swing yoke to which two magnets are fixed and a fixed yoke including projection portions at opposite sides thereof. An electromagnetic coil including a major magnetic pole is arranged at a center of the fixed yoke. The rotary solenoid is arranged to define a magnetic circuit extending through one of the magnets, the major magnetic pole, the fixed yoke, the projection portion, and the other magnet at a shortest distance.

Abstract: A magnetic circuit suitable for a self-held type rotary solenoid while maintaining properties, reducing cost, e.g., a material cost, and making the rotary solenoid smaller in size is provided. The rotary solenoid includes a swing yoke to which two magnets are fixed and a fixed yoke including projection portions at opposite sides thereof. An electromagnetic coil including a major magnetic pole is arranged at a center of the fixed yoke. The rotary solenoid is arranged to define a magnetic circuit extending through one of the magnets, the major magnetic pole, the fixed yoke, the projection portion, and the other magnet at a shortest distance. Therefore, even if a magnet made of a material having a low grade is used, it is possible to maintain sufficient magnetic properties.

Abstract: A brushless DC motor including a rotor capable of minimizing demagnetization of a magnet even when a short-circuit brake operation is performed by short-circuiting motor coils includes two kinds magnets differing in coercive force from each other which are alternately arranged into an annular shape along a circumferential direction. A magnet having a high coercive force is arranged in the portion where a diamagnetic flux is strongly generated. The portion where a diamagnetic flux is generated is the salient pole portion of a stator. A counter electromotive force becomes greatest when the center of the salient pole portion of the stator comes closer to the border of an N-pole and an S-pole of the magnet. Since the diamagnetic flux has a maximum value in that position, the magnet having a high coercive force is arranged near the border of an N-pole and an S-pole.

Abstract: A motor driving circuit for full-wave single-phase driving a motor includes a position detection unit, a turn-on signal generation unit, and switching devices that define an H-bridge circuit. The turn-on signal generation unit includes a differential amplifier arranged to produce a trapezoid wave signal, and a square wave generation circuit arranged to produce a square wave signal, wherein the trapezoid and the square wave signals are respectively supplied to control terminals of lower switching devices in the H-bridge circuit. Further, one of the lower switching devices is turned on and off according to a voltage level of the square wave signal, and the remaining lower switching device is turned on and off when a voltage of the trapezoid wave signal becomes higher than an operation voltage of the remaining lower switching device, wherein a non-conducting interval is provided for the motor coil according to the operation voltage.

Abstract: A manufacturing method of a hybrid permanent magnet type electric rotating machine including a stator that is constructed by winding excitation coils around respective main poles. A rotor is constructed by fixing a first rotor unit, which consists of a pair of rotor cores and a magnetic material sandwiched between the rotor cores, and a second rotor unit, which has the same construction as the first rotor unit, to a rotation shaft. The rotor is assembled to the stator to form an assembled body. The magnet material of the first rotor unit is magnetized in the axial direction by a magnetizing flux passing through a half of the assembled body in the axial direction. The magnet material of the second rotor unit is magnetized in the axial direction in an opposite polarity by a magnetizing flux passing through the remaining half of the assembled body in the axial direction.

Abstract: A stepping motor includes: a stator having main magnetic poles each having small stator teeth on its tip, a core-back portion that connects outer portions of the poles, and windings wound around the poles; and two sets of rotor units that are arranged in an axial direction and face the stator with an air gap therebetween. Each rotor unit consists of two rotor cores that are separated in the axial direction and a magnet sandwiched thereby and magnetized in the axial direction. Each rotor core has small rotor teeth around its outer surface. The rotor cores of each rotor unit are deviated by ½ pitch of the small rotor teeth, and the two rotor units are arranged to make the magnetic polarities of the small rotor teeth of the adjacent two rotor cores identical. A magnet thickness Tm and a rotor core thickness Tc satisfy 0.25?Tm/Tc?0.45.

Abstract: A motor driving circuit for full-wave single-phase driving a motor includes a position detection unit, a turn-on signal generation unit, and switching devices that define an H-bridge circuit. The turn-on signal generation unit includes a differential amplifier arranged to produce a trapezoid wave signal, and a square wave generation circuit arranged to produce a square wave signal, wherein the trapezoid and the square wave signals are respectively supplied to control terminals of lower switching devices in the H-bridge circuit. Further, one of the lower switching devices is turned on and off according to a voltage level of the square wave signal, and the remaining lower switching device is turned on and off when a voltage of the trapezoid wave signal becomes higher than an operation voltage of the remaining lower switching device, wherein a non-conducting interval is provided for the motor coil according to the operation voltage.

Abstract: A stator is constructed by winding excitation coils around respective main poles. A rotor is constructed by fixing a first rotor unit, which consists of a pair of rotor cores and a magnetic material sandwiched between the rotor cores, and a second rotor unit, which has the same construction as the first rotor unit, to a rotation shaft. The rotor is assembled to the stator to form an assembled body. The magnet material of the first rotor unit is magnetized in the axial direction by a magnetizing flux passing through a half of the assembled body in the axial direction. The magnet material of the second rotor unit is magnetized in the axial direction in an opposite polarity by a magnetizing flux passing through the remaining half of the assembled body in the axial direction.

Abstract: A stepping motor includes: a stator having main magnetic poles each having small stator teeth on its tip, a core-back portion that connects outer portions of the poles, and windings wound around the poles; and two sets of rotor units that are arranged in an axial direction and face the stator with an air gap therebetween. Each rotor unit consists of two rotor cores that are separated in the axial direction and a magnet sandwiched thereby and magnetized in the axial direction. Each rotor core has small rotor teeth around its outer surface. The rotor cores of each rotor unit are deviated by ½ pitch of the small rotor teeth, and the two rotor units are arranged to make the magnetic polarities of the small rotor teeth of the adjacent two rotor cores identical. A magnet thickness Tm and a rotor core thickness Tc satisfy 0.25?Tm/Tc?0.45.