JPS6222269A - Magnetic disc device - Google Patents

Abstract

PURPOSE:To from an efficient magnetic circuit by coupling directly a stator coil to an external circuit board at the outside of the title device via a connection part installed to the stator coil. CONSTITUTION:A stator coil 29 comprising a stator yoke 27 made of a hollow cylindrical magnetic material and a coil 28 formed as a thin cylinder is fitted to the outer periphery of a projected part 22b. Further, a rotor magnet 38 comprising a torus magnet 35 and torus magnetic shield members 36, 37 to prevent generation of leaked magnetic flux from the magnet 35 is fixed to the inner periphery of a cylinder 30a ofa spindle hub 30. Then components 29, 38 constitute an inside hub type spindle motor. Further, a drive motor 41 driving a carrier, an external circuit board 60 fitted to an outer bottom face of a base 22 and a through-slot 22C of connecting a connection part 51B to the external circuit board 60 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnetic disk drive, and more particularly to a spindle mechanism for a magnetic disk drive that allows the device to be made thinner even when the number of disks is increased.

[Prior Art] In recent years, so-called Winchester disk devices have been widely used as storage devices for office automation equipment.

FIG. 6 is a partial sectional view showing the configuration of this type of disk device equipped with two disks. In the figure, 1 is a disk, 2 is an outer rotor type spindle motor that rotationally drives the disk 1, 3 is a head that writes and reads information on the disk 1, 4 is a head arm that supports the head 3, and 5 is a helad arm. 4 is a gear rear that moves the disk 1 in the radial direction, 6 is a stator coil of the spindle motor 2, 7 is a rotor magnet of the spindle motor 2, 8 is a spindle hub that rotates while supporting the disk 1, and 9 is a spindle hub that moves the disk 1. 10 is a top cover, 11 is a base, and 12 is a printed circuit board.

[Problems to be Solved by the Invention] In such a disk device, if an attempt is made to increase the capacity by increasing the number of disks without changing the dimensions of the device, the height of the spindle motor 2, the thickness of the disk l, and the It is necessary to reduce the height dimension of the spindle system, which is determined by the spacing. However, if a conventional outer rotor type spindle motor 2 is used, the height will increase as the number of disks increases, and the outer rotor and printed circuit board 12 will interfere, making it impossible to mount components. It was necessary to make a hole in the board 12 that was larger than the outer rotor part.

Figure 7 shows an attempt to improve these shortcomings.
The spindle motor 2 shown in the figure adopts a so-called inside hub type spindle motor 15 in which the rotor magnet 7 and stator coil 6 that were in the outer rotor part are housed in the spindle hub 8, and the rotor magnet 7 is surrounded by a magnetic shielding member 13. This is a device that has

In this device, by adopting the inside hub type spindle motor 15, the height dimension of the spindle system is reduced.
Although it has become possible to mount a large number of disks, the following problem has arisen in order to accommodate the rotor magnet 7 and stator coil 6 within the spindle hub 8.

(1) Since the stator coil 6 is located inside the spindle hub 8, the temperature of the device increases.

(2) Since the rotor magnet 7 and stator coil 6 are housed in the spindle hub 8, which originally does not have enough space, the output torque decreases and structural regulations are tightened, making it necessary to reduce the spindle shaft diameter and bearing dimensions. This may cause new problems such as reduced strength, shortened lifespan, and increased rotational runout.

(3) Although not shown in FIG. 7, there is a circuit board made of glass epoxy or the like on which a rotor position detection sensor is mounted, and a relay board that connects this circuit board to an external printed circuit board 12. Since it is inside the equipment, it causes an increase in dust generation. That is, the materials such as crow evoquin that make up these substrates contain glass fibers and have the potential to generate dust. In addition, the windings of the stator coil 6 are impregnated with an insulator such as a fest to improve electrical insulation and mechanical adhesion, but this fest may generate dust. It causes an increase in dust.

This invention was made against this background, and is based on the structure of an inside hub spindle motor that allows the device to be made thinner even when the number of disks is increased. have,
The purpose of the present invention is to provide a magnetic disk device with improved reliability by solving problems such as heat generation, dust generation, low strength, and short life.

[Means for Solving the Problems] In order to solve the above problems, the present invention includes a base on which a cylindrical protrusion is erected, a pair of bearings fitted into a hollow part of the protrusion, and a base having a cylindrical protrusion. A spindle shaft fitted into a bearing, a spindle hub fixed to the spindle shaft concentrically surrounding the spindle shaft and having a magnetic disk attached to its outer periphery, and a spindle hub fixed to the inner periphery of a hollow part of the spindle hub. The stator coil includes a rotor magnet, and a stator coil that is fixed to the outer circumference of the protrusion and whose outer circumferential surface faces the inner circumferential surface of the rotor magnet. A band-shaped insulating film formed with an interval of A connecting portion is formed extending in the axial direction of the coil, and this connecting portion is connected to an external circuit board attached to the outside of the base via a through groove provided in the base.

Moreover, a plurality of sensors for detecting the position of the rotor magnet are provided on the surface of the insulating film.

[Function] According to the above structure, the stator coil is formed by winding a sheet coil (an insulating film with a spiral coil formed thereon), and the stator coil is formed by winding a copper wire insulated with polyurethane, polyester, etc. Compared to conventional stator coils, the radial thickness is reduced to about 1/10 to 1/20, so the gap between the rotor magnet, which forms the magnetic circuit, and the stator yoke, which forms the core of the stator coil, can be minimized. Can be made smaller. This improves the efficiency of the motor and reduces the amount of heat generated.

The radial thickness of the above stator coil is very thin (1 m
m), it is possible to increase the diameter of the spindle shaft and the diameter of the bearing, thereby preventing a decrease in strength, life, etc., and an increase in rotational runout.

Further, since the 'f7SQ-shaped coil is formed on a flat surface, the number of turns of the coil can be increased, and a decrease in output torque can be prevented.

Furthermore, since the stator coil is configured to be directly connected to the external circuit board using the connection part provided on the stator coil, it is no longer necessary to use a relay board made of glass epoxy, etc., which is necessary in the past and has the potential to generate dust. It can be eliminated.

As a result, air can be passed through the spindle hub as part of the equipment's air circulation system, and the heat generated within the spindle hub can be quickly dissipated without increasing dust generation. .

Finally, the present invention can realize further miniaturization by integrating the base of the device and the housing of the spindle motor.

[Example code] Hereinafter, the present invention will be described in detail with reference to the drawings.

In FIGS. 1 and 2, reference numeral 21 denotes a housing whose interior is sealed to prevent dust from entering, and the housing 2 is composed of a base 22 and a cover 23. A cylindrical protrusion 22b having a through hole 22a is erected on the base 22, and a pair of bearings 25, 25 that support the spindle shaft 24 are inserted and fixed into the through hole 22a, and the seal member 26 seals the protrusion 22b. has been done.

On the other hand, a stator coil 29 consisting of a hollow cylindrical stator yoke 27 made of a magnetic material and a thin cylindrical coil 28 is fitted into the outer periphery of the protrusion 22b.

Next, 30 is a spindle hub on which a plurality of magnetic disks 31 are mounted. This spindle hub 30 is made of a non-magnetic lightweight metal material such as aluminum, and a plurality of magnetic disks 31, 31, .
... are held at a predetermined distance in the axial direction,
It is clamped and fixed by a clamp 33. On the other hand, an annular ring magnet 35 and a ring magnet 3 are provided on the inner peripheral surface of the cylindrical portion 3Qa of the spindle hub 30.
A rotor magnet 38 constituted by annular magnetic shielding members 36 and 37 for preventing generation of leakage magnetic flux is fixed. And the above component 29
．． 38 constitutes an inside hub type spindle motor, and A
There is. In addition, in FIG. 1, 41 is a drive motor that drives the carrier, 6o is an external circuit board attached to the external bottom surface of the base 22, and in FIG. 2, 22c is a connecting portion 5 which will be described later.
This is a through groove for connecting 1B to the external circuit board 60.

Next, FIG. 3 is a diagram showing the structure of a sheet coil 50 that constitutes the coil 28.

In the figure, 51 is a base film serving as a substrate of the sheet coil 50. This base film 51 is, for example, a so-called FPC (flexible printed circuit board) made of a polyimide film with a thickness of about 25 to 50 μm, and on both sides there is a spiral shape made of copper foil with a thickness of about 50 to 80 μm. A coil is formed. That is, the base film 51 includes a linearly extending strip portion 51A,
It consists of a connecting portion 50B that extends in a direction perpendicular to this strip-shaped portion 51A and is electrically connected to the external circuit board 60 in FIG.
(52A-52F), 53(53A-53F), 54(
54A to 54F) are linearly formed and arranged, and coils 52A and 52B formed on both sides of the base film 51,
53A and 53B... are electrically connected at the center.

In addition, three sensors 55, 56.5 are provided in the strip portion 51A.
Notches 51C to 51G are formed to expose 7.

Upper 8 self-sensors 55, 56, and 57 are sensors for detecting the position of the low-return magnet 35, and
1A is arranged near the part connected to the connecting part 51B. Further, a protrusion 59a is formed on one side of the connecting portion 51B, and a rotation sensor 59 is provided.

FIG. 4 shows the connection of the three-phase coil 52, 53, 54, three sensors 55, 56, 57, and rotation sensor 59, each end of which is connected to the external circuit board 60 through the connection part 51B. It is now connected. and,
The external circuit board 60 learns the position of the rotor magnet 3B from the signals from the sensors 55, 56, 57, and sequentially supplies current to the coils 52, 53, 54 to rotate the spindle motor.

FIG. 5 is a sectional view showing the thin cylindrical coil 28 formed by winding the sheet coil 50. This coil 28 is connected to one end of the strip portion 5IA (the connecting portion 5
The coils 52B, 52G, 52G, 52D, 52E, and 52F are wound so as to overlap one another. As a result, the coils 53A to 53F
The coils 54A to 54F are also sequentially stacked. Then, the coil 52 changes from coil 52B to coil 52A.
→ Coil 52C → Coil 52D → Coil 52F → Coil 52E.
Connected to terminal B. Also, the other coil 53.5
The same applies to 4.

On the other hand, the notches 51'C to 51G of the band-shaped portion 51A overlap the sensors 55, 56.57, and the sensor 55, 56.5
7 is placed opposite to the rotor magnet 38 in FIG. 1 through the thickness of the coil 28. In addition, in order to prevent each spiral coil 52 to 54 from being short-circuited when the sheet coil 50 is wound, a cover film 58 having the same quality as the base film 51 is wound so as to overlap the base film 51.

The coil 28 created in this way is fitted and fixed to the outer periphery of the stator yoke 27, and is fixed to the outer periphery of the protruding parts 22b of the bases 2, 2. It is connected to an external circuit board 60 attached to the external bottom surface of the housing 21 through the groove 22c. The rotation sensor 59 is fixed to the upper surface of the base 22, faces a rotation detection magnet (shown in the drawing) embedded in the bottom surface of the spindle hub 30, and detects rotation of the spindle hub 30.

Further, the gap between the through groove 22c and the connecting portion 51B is sealed with a sealing material.

Although the spindle motor configured in this manner is an inside hub type, the risk of dust generation is extremely small because the coil 28 is made of FPC (flexible printed wiring board), which has an extremely low possibility of dust generation. Therefore, even if heat generation in the coil 28 becomes a problem, by circulating air within the spindle hub 30, the heat can be quickly dissipated. In addition, since the thickness of the coil 28 in the radial direction can be made approximately 1 mm, the spindle shaft 2
There is no need to reduce the diameters of the bearing 4 and the bearing 25, and a decrease in strength and an increase in vibration can be avoided.

Furthermore, since the rotation sensor 59 is provided within the sheet coil 50, the installation of the rotation sensor 59 is extremely simplified. Here, the output of the rotation sensor 59 is used as an index signal and also used to detect the rotation speed of the spindle motor.

In the above embodiment, a three-phase case has been described, but the present invention can be applied to any phase such as two-phase or four-phase.

[Effects of the Invention] As explained above, the present invention configures a thin cylindrical stator coil by winding an insulating film having a spiral coil formed on its surface, and connects the connecting portion provided on this stator coil. Since the stator coil is directly connected to an external circuit board outside the device through the above-mentioned device, the following effects can be achieved.

(1) Since the stator coil is thin, an efficient drowsiness circuit can be formed, and since the spiral coil is planar, it is possible to have a sufficient number of turns. Therefore, the efficiency of the motor can be improved and the amount of heat generated can be suppressed, and a decrease in output torque can be prevented.

(2) Since the stator coil is thin, it is possible to increase the diameter of the spindle shaft and the diameter of the bearing.

Therefore, it is possible to prevent a decrease in strength and life, and also to prevent rotational vibration.

(3) Air can be circulated inside the spindle hub because the relay board, which could have generated dust, can be removed. Therefore, the heat generated inside the spindle hub can be quickly diffused. is possible.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing the configuration of an embodiment of the present invention;
Figure 2 is an exploded perspective view showing the configuration of the main parts of the same embodiment;
The figure shows a sheet coil 50 constituting the coil 28 of the same embodiment.
A top and bottom view and a side view showing the configuration of the coil 28, FIG.
Figure 5 is a circuit diagram showing the electrical equivalent circuit of the same coil 2.
8, FIGS. 6 and 7 are partial sectional views showing the structure of a spindle motor in a conventional magnetic disk device. l, 31...Magnetic disk, 22...
Base, 22b...Protrusion, 22c...
・Through groove, 24...Spindle shaft, 25...
... bearing, 29 ... stator coil, 30.
...Spindle hub, 38...Rotor magnet, 51...Base film (insulating film), 51B...Connection part, 52-54...
...Spiral coil, 55-57...Sensor, 5
9... Rotation sensor, 60... External circuit board.

Claims (3)

[Claims] (1) A base on which a cylindrical protrusion is erected, a pair of bearings fitted into the hollow part of the protrusion, a spindle shaft fitted with the bearings, and a shape concentrically surrounding the spindle shaft. a spindle hub that is fixed to the spindle shaft and has a magnetic disk attached to its outer periphery; a rotor magnet that is fixed to the inner periphery of the hollow part of the spindle hub; The stator coil is provided with a stator coil that faces the inner circumferential surface of the rotor magnet, and the stator coil is formed by winding a strip of insulating film into a cylindrical shape, on which a plurality of spiral coils are formed at predetermined intervals, and laminating each of the strips. The stacked spiral coils are electrically connected in series, and the insulating film is formed with a connecting portion extending in the axial direction of the cylindrical stator coil, and this connecting portion is connected to the base. A magnetic disk device, characterized in that the magnetic disk device is connected to an external circuit board attached to the outside of the base via a provided through groove. (2) The magnetic disk drive according to claim 1, wherein a plurality of sensors for detecting the position of the rotor magnet are provided on the surface of the insulating film. (3) A magnetic disk drive according to any one of claims 1 to 2, characterized in that a detector for detecting the number of rotations of the rotor magnet is provided on the surface of the insulating film.