Spindle motor for driving disc

In an outer rotor type spindle motor for driving a disc with a relatively long axial dimension for mounting a large number of the discs, it is possible to reduce part cost and assembling work cost while increasing a rotational precision. The stator is disposed on an opening surface of a drum portion of the rotor rather than between a pair of bearings within the drum portion. The stator coil end may be led to the outside of the drum portion without passing through the bearing to dispense with the conventional works such as a processing of a shaft, an insertion of a lead wire through a tubular hole and the like. Also, a bush between the drum portion and the bearing, which conventionally causes the degradation of the rotational precision and the increases in the cost for the parts and the assembling work, is dispensed with. In order to elongate the distance between the bearings and reduce the axial direction of the stator, a magnet material having a magnetic energy product that is higher than that generally used to this type of motor is selected.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a longitudinal sectional view showing a disc driving spindle motor according to one embodiment of the present invention;

FIG. 2 is a longitudinal sectional view showing the disc driving spindle motor according to another embodiment of the invention;

FIG. 3 is a longitudinal sectional view showing the embodiment different from that shown in FIG. 2; and

FIG. 4 is a longitudinal sectional view showing a conventional disc driving spindle motor.

1. An outer rotor disc driving spindle motor in which a rotor having a magnet facing a stator comprising a coil and fixedly supported on a shaft, is located outside of said stator, mounted to a shaft via a first and a second bearings provided with a spacer means inbetween, characterized in that;

2. The disc driving spindle motor according to claim 1, wherein said spacer means is a flanged portion formed as a projection from an inner wall of the drum portion of the rotor.

3. The disc driving spindle motor according to claim 1, wherein integrally formed outer races of said first bearing and said second bearing provide a spacer means, and