JP2598683Y2 - Direct drive motor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct drive motor used in, for example, an FD drive device, and more particularly to a structure of a direct drive motor for obtaining a synchronization signal of a rotor initial position and a rotation angle.

[0002]

2. Description of the Related Art As is well known, in a direct drive motor for driving a magnetic disk such as a floppy disk, it is necessary to obtain a synchronization signal of an initial position and a rotation angle of the magnetic disk, that is, a rotor. FIG. 4 shows a main part of a conventional 3.5-inch FD drive device. A floppy disk X can be inserted into a front portion of a device frame 3A in which a rotor spindle 2A of a direct drive motor is rotatably supported by a bearing 1A. A resin bezel 4A having an insertion opening 4a formed therein is fixed, and a floppy holder 6 which is vertically moved by a lift cam 5A is provided above the apparatus frame 3A.
A supports.

A collet 7A which can be engaged with a magnetic disk of a floppy disk X is fixed to an upper end of the rotor spindle 2A, and a metal cup-shaped rotor 8A for magnetically shielding is provided at a lower end of the rotor spindle 2A.
Is fixed, and a rotor magnet 9A polarized in the circumferential direction is fixed to the inner surface of the cup-shaped rotor 8A. That is,
The rotor magnet 9A has a plurality of stator coils 11A on the surface of a printed circuit board 10A fixed to the lower surface of the apparatus frame 3A in a state facing the cup-shaped rotor 8A.
And drives the rotor spindle 2A.

A ring-shaped FG magnet cooperating with an FG pattern 12A (FIG. 5) for detecting a rotation angle formed in an arc shape on the surface of the printed circuit board 10A is provided on an outer peripheral portion of the cup-shaped rotor 8A. 13A is fixed, but the FG magnet 13A is subdivided and polarized in the circumferential direction of the cup-shaped rotor 8A so as to correspond to the pitch of the rectangular wave-shaped FG pattern 12A.

Further, in order to detect the initial position of the magnetic disk or the rotor spindle 2A, the conventional direct drive motor has a small permanent magnet on the outer surface of the peripheral wall 8a of the cup-shaped rotor 8A as shown in FIGS. An index magnet 14A composed of a magnet is fixed with an adhesive or the like, and an index sensor 15A composed of a magnetically sensitive element is fixed on the surface of the printed circuit board 10A facing the range of movement of the index magnet 14A. An index signal is transmitted from the index sensor 15A.

[0006]

However, according to the structure of the conventional direct drive motor as described above, the index magnet 14A is specially required to detect the initial position of the rotor spindle 2A. Production cost is higher due to the parts cost of the index magnet 14A
Requires a step of fixing the substrate with an adhesive or the like, and there is a problem that the manufacturing process becomes complicated. SUMMARY OF THE INVENTION An object of the present invention is to provide a direct drive motor structure capable of omitting an index magnet which causes an increase in parts cost and complicates a manufacturing process in view of the above-mentioned conventional problems.

[0007]

In order to achieve this object, the present invention provides a printed circuit board in which a metal cup-shaped rotor is fixed to one end of a rotor spindle, and which is disposed close to the cup-shaped rotor in an apparatus fixing portion. A rotor magnet that cooperates with a plurality of stator coils on the surface of the cup-shaped rotor and is polarized in the circumferential direction of the cup-shaped rotor is fixed to the inner surface of the cup-shaped rotor, and faces the FG pattern on the surface of the printed circuit board. In a direct drive motor for fixing an FG magnet that is subdivided and polarized in the circumferential direction of a cup-shaped rotor around the rotor magnet, an opening through which a part of the FG magnet can be exposed to a part of a peripheral wall of the cup-shaped rotor. The FG magnet formed from a flexible band-shaped rubber magnet is formed into a “C” shape along the inner peripheral surface of the peripheral wall. The present invention proposes a direct drive motor in which a gap formed between both end surfaces of the FG magnet by bending is positioned in the opening, and an index sensor is positioned on the surface of the printed circuit board within a range of leakage magnetic flux leaking from the opening. .

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an embodiment of the present invention; FIG. The illustrated embodiment is an example in which the present invention is applied to a 3.5-inch FD drive device. A floppy disk is provided at the front of a device frame 3 in which a rotor spindle 2 of a direct drive motor is rotatably supported by a bearing 1. It is the same as the conventional one in that a resin bezel 4 having an insertion opening 4a into which X can be inserted is fixed, and a floppy holder 6 which is moved up and down by a lift cam 5 is supported on the upper part of the apparatus frame 3.

At the upper end of the rotor spindle 2, a collet 7 that can be engaged with the magnetic disk of the floppy disk X is fixed, and at the lower end of the rotor spindle 2 is a metal cup-shaped rotor 8 that performs magnetic shielding. Is fixed to the inner surface 8b of the cup-shaped rotor 8, and a rotor magnet 9 made in a disk shape is fixed. That is, the rotor magnet 9 polarized in the circumferential direction of the cup-shaped rotor 8 is fixed to the lower surface of the apparatus frame 3 in a state facing the cup-shaped rotor 8 and a plurality of stator coils 11 on the surface of a printed circuit board 10. They cooperate to drive the rotor spindle 2.

On the inner peripheral surface of the peripheral wall 8a of the cup-shaped rotor 8, an FG magnet 1 composed of a band-shaped rubber magnet is provided.
3 is fixed with an adhesive or the like in a state of being bent in a “C” shape. That is, the FG magnet 13 is formed on the surface of the printed circuit board 10 in a circular arc shape for detecting the rotation angle of the FG.
It cooperates with the pattern 12 (shown in FIG. 2) and is subdivided in the circumferential direction of the cup-shaped rotor 8 so as to correspond to the pitch of the FG pattern 12 having a rectangular wave shape. A gap 16 is formed. Of course, the actual F
The gap 16 of the G magnet 13 may be formed in a ring shape in advance with a gap material interposed between both end surfaces and fixed to the peripheral wall 8 a of the cup-shaped rotor 8.

In the illustrated embodiment, an opening 17 is formed in a part of the peripheral wall 8a of the cup-shaped rotor 8 in order to detect the initial position of the magnetic disk or the rotor spindle 2 as shown in FIGS. . Since the position of the opening 17 is a position where the above-mentioned FG magnet 13 gap 16 can be exposed to the outside, a part of the magnetic flux of the FG magnet 13 whose magnetic flux density is improved by the gap 16 is formed on the outer periphery of the cup-shaped rotor 8. Leak. The printed circuit board 10
An index sensor 15 composed of a magnetically sensitive element is fixed to a position near the peripheral wall 8a of the cup-shaped rotor 8, and an index signal is transmitted from the index sensor 15.

Since the direct drive motor of the illustrated embodiment has the above-described structure, in the cup-shaped rotor 8 that performs magnetic shielding, the F
Since the magnetic flux of the G magnet 13 leaks outside, the leak magnetic flux can be detected by the index sensor 15 and used as an index signal. In this case, the FG magnet 1 having the magnetic flux density enhanced by the gap 16 is provided in the opening 17.
Since the portion 3 is located, the index signal can be obtained without error even with the index sensor 15 having low sensitivity. Therefore, the conventional index magnet can be omitted, and not only the cost of parts can be reduced and the assembly process can be simplified, but also the initial position signal can be obtained with the index sensor 13 having low sensitivity.

[0013]

As is apparent from the above description, according to the present invention, a small opening is formed in a part of the peripheral wall of the cup-shaped rotor, and the gap of the FG magnet is exposed to the outside through the opening. Since the function of the index magnet is obtained, the index magnet is omitted, the manufacturing cost is low, and the assembling process can be simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an FD drive device according to the present invention.

FIG. 2 is a bottom view of the FD drive device.

FIG. 3 is an enlarged view of a main part of a rotor of the FD drive device.

FIG. 4 is a sectional view corresponding to FIG. 1 of a conventional FD drive device.

FIG. 5 is a bottom view corresponding to FIG. 2 of the FD drive device.

FIG. 6 is an enlarged view of a main part of a motor of the FD drive device.

[Explanation of symbols]

 Reference Signs List 2 rotor spindle 8 cup-shaped rotor 8a peripheral wall 8b inner surface 9 rotor magnet 10 printed circuit board 11 stator coil 12 FG pattern 13 FG magnet 15 index sensor 16 gap 17 opening

Continuation of the front page (56) References JP-A-58-39257 (JP, A) JP-A-1-64977 (JP, U) JP-A-61-46886 (JP, U) JP-A-5-11777 (JP) , U) Japanese Utility Model Hei 5-67155 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02K 29/00 H02K 21/00

Claims (1)

(57) [Scope of request for utility model registration] 1. A cup-shaped rotor made of metal is fixed to one end of a rotor spindle, and cooperates with a plurality of stator coils on a surface of a printed circuit board arranged on an apparatus fixing portion in close proximity to the cup-shaped rotor. A rotor magnet polarized in the circumferential direction of the rotor is fixed to the inner surface of the cup-shaped rotor, and the FG magnet that is subdivided and polarized in the circumferential direction of the cup-shaped rotor in a state facing the FG pattern on the surface of the printed circuit board. In a direct drive motor fixed around the rotor magnet, an opening through which a part of the FG magnet can be exposed to the outside is formed in a part of a peripheral wall of the cup-shaped rotor, and the opening is formed from a flexible band-shaped rubber magnet. A gap formed by bending the FG magnet along the inner peripheral surface of the peripheral wall into a “C” shape and forming between both end surfaces of the FG magnet. A direct-drive motor, wherein an index sensor is located on a surface of the printed circuit board within a range of leakage magnetic flux leaking from the opening.