PURPOSE: To omit a sheet of core and also to omit one of assembling proesses by forming recessed grooves on both sides of a core at the rotor side, and sharing a rotary core for both sound and video uses.

CONSTITUTION: Coil grooves 19 and 20 are formed to the lower surface side of a video/sound rotary core 15, and video coils 19b and 20b are put into the grooves 19 and 20 respectively. In the same way, coil grooves 21 and 22 are provided on the upper surface side of the core 15. Then sound coils 21b and 22b are put into the grooves 21 and 22 respectively. In such a constitution, the conventional four sheets of core can be reduced down to three sheets.