JPH02280651A - Spindle motor - Google Patents

Abstract

PURPOSE:To prevent erroneous reading of track by arranging a magnet chip for generating index signal in a tubular section fitted with stator. CONSTITUTION:A recess 23 is formed at one end portion(lower end portion) of the outer circumferential face 22 of a tubular body 8, and a magnet chip 24 for generating index signal is fitted in the recess 23. The magnet chip 24 is arranged at the inside of a tubular section 5 fitted with a stator 6. Consequently, relatively long distance can be provided between the magnet chip 24 and a magnetic disc 17 and the magnetic disc 17 is not subjected to bad influence of the magnet chip 24. Furthermore, since the magnet chip 24 is arranged at the inside of the tubular section 8, effective track forming area can be enlarged.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a spindle motor.

[Problems to be solved by conventional techniques and inventions] Generally,
As shown in FIG. 2, a spindle motor (in-hub type) having a magnet piece for generating an index signal includes a stator a, a rotor magnet b that closely faces the stator a,
The rotor magnet b has an inner peripheral surface d of the holder C.
The index signal generating magnet piece e was disposed on the outer peripheral side of the rotor magnet b. In other words, 0g attached to the lower surface of the peripheral wall r of the holder C is a sensor, and is attached to a bracket h having a cylindrical portion on which a rotating shaft (not shown) is rotatably supported.

Furthermore, a magnetic disk i is attached to the holder C.

Therefore, the magnetic disk i and the magnet piece e are disposed close to each other, and there is a risk that the magnetic disk i will be affected by the magnetic flux of the magnet piece e, causing a malfunction in track reading.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a spindle motor in which a magnetic disk is not affected by the index signal generating magnet piece and trunk reading errors can be prevented.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the spindle motor of the present invention has an index signal generating magnet piece disposed inside a cylindrical part to which a stator is fitted and fixed. This is what I did.

[Effect]

Since the index signal generating magnet piece is arranged inside the cylindrical part into which the stator is fitted, the magnetic flux is less likely to leak to the outside of the hub, etc., and furthermore, the magnet piece is placed further away from the magnetic disk. The magnetic flux leakage from the magnet piece does not affect the magnetic disk.

〔Example〕

Examples will be described below with reference to the drawings.

Figure 1 shows a spindle motor (in-hub type) according to the present invention.
This motor includes a pivot shaft 1, a holder 3 rotatably supported on the pivot shaft 1 via bearings 2, 2, and a bracket 4 to which one end of the pivot shaft 1 is fixed. The rotor magnet 7 is provided with a stator 6 which is fixed to the cylindrical portion 5 in an externally fitted manner, and a rotor magnet 7 which is attached to the holder 3 so as to closely face the stator 6.

Thus, the holder 3 includes a cylindrical body 8 whose one end is fitted into the cylindrical part 5, and a magnet holder 10 fixed to the outer flange part 9 of the cylindrical body 8.

That is, the holder 10 includes a ring-shaped upper wall 11 and a ring-shaped upper wall 11.
The upper wall 11 is fitted into a circumferential groove 13 formed in the outer flange 9 and fixed thereto.

The cylindrical body 8 is rotatably supported via bearings 2, 2. Further, an inner flange 14 is provided on the inner circumferential surface of one end edge of the cylindrical body 8, and a hanging piece portion 15 is further provided at the tip of the inner flange 14. This hanging piece portion 15 is loosely fitted into a concave circumferential groove 16 provided in the bracket 4.

Further, the magnetic disk 17 is attached to the holder 3, and specifically, the magnetic disk 17 is placed on the back of the holder 10 at the end 19 of the holding member 18, which is attached to the holder 3 so that a film can be freely deposited. The magnetic disk 17 is held down. In addition,
This holding member 18 is attached to the holder 3 with a screw 21 screwed into a screw hole 20 of the collar portion 9.

A recess 23 is formed at one end (lower end) of the outer peripheral surface 22 of the cylindrical body 8, and an index signal generating magnet piece 24 is fitted into the recess 23.

That is, this magnet piece 24 is disposed inside the cylindrical portion 5 to which the stator 6 is fitted and fixed. 25
is a sensor for the magnet piece 24, and a part of the cylindrical part 5 or a part of the upper surface of the bracket 27 is cut out, and this sensor 25 is
is installed. 28 is a lid body for covering the cylindrical body 8;
29 is a blind cover for the screw hole 20.

Therefore, in the spindle motor configured as described above, the distance between the magnet piece 24 and the magnetic disk 17 can be made relatively large, and the magnetic disk 17 is not adversely affected by the magnet piece 24. Furthermore, by disposing the magnet piece 24 inside the cylindrical portion 8, the effective track forming area can be expanded when compared with a conventional spindle motor having the same outer diameter.

Therefore, in the above embodiment, the holder 3 is provided with the hanging piece 15, and the bracket 4 is provided with the recessed circumferential groove 1-6 into which the hanging piece 15 is loosely fitted. This prevents grease from the bearing 2 and the like from scattering onto the stator 6 and the like.

Note that the present invention is not limited to the above-described embodiments, and the design may be changed without departing from the gist of the present invention. For example, the cylindrical body 10 of the holder 3 and the holding body 11 may be integrated. Furthermore, although the holder 11 is made of a magnetic material, it may be made of a non-magnetic material and a yoke.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

The magnetic flux of the index signal generating magnet piece 24 may leak to the outside (because the stator 6 is fitted onto the cylindrical portion 5), and the magnetic flux may leak between the magnet piece 24 and the magnetic disk 17. The distance between the magnetic disk 17 and the magnetic disk 17 can be increased, and the negative influence of the magnet piece 24 on the magnetic disk 17 can be eliminated.
Eliminates track reading malfunctions. Moreover, when compared with conventional products having the same outer diameter, there is an advantage that the range in which tracks can be effectively formed is expanded.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention. FIG. 2 is a sectional view of a main part of a conventional example. 5... Cylindrical part, 6... Stator, 24... Magnet piece for index signal generation.

Claims (1)

[Claims] 1. Place the index signal generation magnet piece 24 on the stator 6.
1. A spindle motor characterized in that the spindle motor is disposed inside a cylindrical portion 5 to which a cylindrical portion 5 is fixedly fitted.