Rotary driving apparatus

A rotary driving apparatus comprising:

• a housing;
• a rotor arranged in the housing;
• a shaft connected to the rotor;
• supporting means for rotatably connecting the shaft to the housing;
• a permanent magnet member;
• a first plate member extending transversely with respect to the shaft and fixedly connected to the shaft at an end remote from the rotor, said permanent magnet member being mounted on one side of the plate member remote from the rotor, said permanent magnet member being provided with axially superimposed two disk portions magnetized in mirror fashion along a common diametric line;
• stopper means for allowing limited rotation of the rotor between first and second positions which are angularly spaced from each other at an angle smaller than 180.degree., said stopper means comprising a second plate member fixedly connected to said housing so as to axially and spacedly face with the other side of said first plate member remote from said magnet member and abutting means arranged between said first and said second plate members for effecting a movement of said first member with respect to said second member in said limited angle range;
• a core made of magnetic material stationarily arranged on one side of the permanent magnet member remote from the rotor, said core being provided with a pair of diametrically spaced end portions located adjacent to the poles to the permanent magnet in a side-by-side relationship;
• and
• coil means on the core for magnetizing, when energized, the portions of the core to become different poles so as to generate a torque for obtaining rotation of the permanent magnet in a desired direction of accordance with the direction of the electric current to be applied to the coil means in order to change-over the rotor between the first and the second positions;
• said permanent magnet member beng so arranged with respect to the portions of the core so that a residual torque is generated in the permanent magnet member during the de-energization of the coil means for engaging the stopper means to maintain the selected one position of the rotor.