JPH0441487Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to a magnetic chuck device, in particular, a center core is attached to the center of a disc-shaped magnetic disk, and this center core is attached using the attraction force of the magnet. The present invention relates to a magnetic chuck device which is held on a chuck portion and rotated to magnetically write or read information using the magnetic disk.

〓Summary of the invention〓 The present invention covers at least the exposed surface of the magnet of a magnetic chuck device that attracts the center core of a disk-shaped magnetic disk with a coating means such as a resin coating layer or a coating ring made of a non-magnetic material. It is designed to prevent magnetic powder from being generated from the magnet.

<Prior Art> For example, when writing or reading information on a floppy disk, it is necessary to hold the floppy disk via a chuck device and to rotate it by a drive means. For example, as disclosed in Japanese Utility Model Application No. 59-71487, a magnetic chuck device is provided on the rotating shaft of the motor, and the center core attached to the center of the floppy disk is controlled by this chuck device. The floppy disk is attracted and held, and in this state, the floppy disk is rotated.

〓Problems to be solved by the invention〓 Conventionally, stamped rubber magnets or sintered rare earth magnets have been used as magnets for such magnetic chuck devices. If you use it, fine magnetic powder will fall off the magnet. Such magnetic powder scatters and adheres to the magnetic sheet constituting the floppy disk. If the magnetic powder adheres to the floppy disk in this way, that part will be locally demagnetized and an error will occur.

The present invention was devised in view of these problems, and an object of the present invention is to provide a magnetic chuck device in which the magnet for generating adsorption force and holding the object does not generate magnetic powder. It is something to do.

〓Means for Solving the Problems〓 The present invention is to attach a center core to the center of a disc-shaped magnetic disk, hold this center core on the chuck part using the attraction force of the magnet, and rotate it. A magnetic chuck device that magnetically writes or reads information using a magnetic disk, comprising: a chuck portion having a concave upper surface; the magnet housed and held inside the chuck portion; and the chuck portion. a reference surface that is formed on the chuck portion and is higher than the height of the magnet and receives the center core of the magnetic disk; The ball bearing is rotatably supported by the ball bearing, and the center core is centered by the outer peripheral surface of the outer ring of the ball bearing.

〓Operation〓 Therefore, when a magnetic disk is attached to a magnetic recording device having such a magnetic chuck device, the center core attached to the center of the disk is attracted by the magnet in the chuck portion, and the magnetic disk attached to the chuck portion is attracted by the magnet in the chuck portion. It can be received by the reference surface that is In this way, the magnetic disk is rotated while being held using the attraction force of the magnet, so that information can be written or read magnetically using this magnetic disk.

〓Example〓 The present invention will be described below with reference to an illustrated example.
5 and 6 relate to a motor equipped with a chuck device according to an embodiment of the present invention, and this motor is equipped with a motor base 10. FIG. A boss portion 11 is formed in the center of the base 10, and a shaft 12 is press-fitted into the boss portion 11 and fixed thereto. A rotor boss 13 is rotatably attached to this shaft 12. That is, the rotor boss 13 is rotatably supported by the shaft 12 via ball bearings 14 and 15 at its upper and lower ends. The outer ring of the upper bearing 14 is the rotor boss 1.
It is engaged with the step portion 16 of No. 3. Note that a stepped portion may also be formed on the lower end side of the inner diameter of the rotor boss 13, and the stepped portion may be engaged with the edge of the upper end of the outer ring of the lower bearing 15.

A chuck portion 17 is integrally attached to the rotor boss 13.
is formed into a ring shape, and this chuck part 1
A chuck magnet 18 is held in the recess 7. The upper end 19 of the chuck portion 17 protrudes above the upper surface of the chuck magnet 18, so that a gap is formed between the center core of the recording medium and the chuck magnet 18. This is to perform chucking using the upper end 19 of the chuck portion 17 as a reference plane.
By increasing the dimensional accuracy of this reference surface 19, surface runout of the recording medium is prevented.

Furthermore, a guide cap 20 is fixedly attached to the upper end of the shaft 12. This guide cap 20 has a sloped portion 21 formed on its outer peripheral surface, which guides the mounting of the recording medium. The recording medium guided by the inclined portion 21 is further guided by the outer peripheral surface of the ball bearing 14, and the upper end of the ball bearing 14 is
It protrudes further upwards than the upper surface 19 of the chuck portion 17. Further, the edge at the upper end of the outer ring of the ball bearing 14 has a curved cross-sectional shape to protect the recording medium during installation.

As shown in FIGS. 1 and 2, the chuck magnet 18 attached to the chuck portion 17 has its exposed surface, that is, its inner peripheral surface and upper surface, covered with a resin coating layer 48. It's becoming like that. This is to prevent magnetic powder from being generated from the magnet 18 formed by sintering, and the exposed surface not covered by the chuck portion 17 is coated with the resin coating layer 48. I have to.
Note that instead of coating with the resin coating layer 48, the coating layer may be formed by painting.

3 and 4 show the structure of the chuck portion 17 according to a modified example, and in this modified example, the exposed surfaces of the chuck magnet 18 held in the chuck portion 17, that is, the upper surface and the inner circumferential surface. are covered by a covering ring 49 having an L-shaped cross section. This covering ring 49 is made of a non-magnetic material, and by covering it with the covering ring 49 made of such a non-magnetic material, the magnet 18 is shielded and the generation of magnetic powder is prevented. It is possible,
This produces the same effect as the magnet 18 shown in FIGS. 1 and 2.

Next, the structure of the rotor of this motor will be explained. As shown in FIG. 6, a rotor case 22 is fixed to the rotor boss 13 by press fitting. Note that this rotor case 22 may be formed integrally with the rotor boss 13. A main magnet 23 is fixedly attached to the lower surface of the rotor case 22. Also rotor case 22
A gear 24 is formed on the outer circumferential side of the motor, and the output of the motor can be directly taken out by this gear 24. Furthermore, a rotor yoke 25 is arranged below the main magnet 23. A boss portion 26 formed at the center of the rotor yoke 25 is fitted with the outer ring of the lower ball bearing 15, thereby determining the center position. The rotor yoke 25 comes into contact with the lower end of the rotor boss 13 and is held in this position by the suction force of the main magnet 23.

A double-sided printed wiring board 27 is arranged in an axial air gap formed between the main magnet 23 and the rotor yoke 25. This printed wiring board 27 is attached to a support stand 28 with screws 29. The support base 28 is made of a non-magnetic material, and the main magnet 2
It is designed to prevent static coking caused by the suction force in step 3. Further, the support stand 28 is fixedly attached to the base 10 in which a notch 30 for attaching the motor is formed. On the double-sided printed wiring board 27, an FG pattern is formed in addition to a pattern for coil wiring, and a Hall element for position detection is also attached. Further, on this printed wiring board 27, as shown in FIGS. 7 and 8, three coils 31, 3 are arranged at 120 degree intervals.
2,33 are attached.

Next, the drive circuit for these coils 31, 32, 33 will be explained with reference to FIG. 9. These coils 31, 32, 33 are connected to power supply terminals via transistors 34, 35, 36, respectively. There is. Also, these coils 31, 3
2 and 33 are transistors 37, 38, and
39 to the ground side. Further, the bases of the transistors 34 and 37 are connected to an inverting amplifier 40, and the bases of the transistors 35 and 38 are connected to an inverting amplifier 40.
The base of transistors 36 and 39 is connected to inverting amplifier 41, and the bases of transistors 36 and 39 are connected to inverting amplifier 42. The input sides of the amplifiers 40 to 42 are connected to a logic circuit 46.
This logic circuit 46 is connected to Hall elements 43, 44, 45 which cover the rotational position of the rotor case 22 including the main magnet 23.

In the above configuration, the three Hall elements 43 to 45 connected to the logic circuit 46 shown in FIG. 9 are designed to detect the rotational position of the main magnet 23 supported by the rotor case 22. The detection output is supplied to the logic circuit 46. The logic circuit 46 is
Based on the detection of these three Hall elements 43 to 45, three sine waves whose phases are shifted by 120 degrees are formed, and these are transmitted to the inverting amplifiers 40, 41, and 45.
2, respectively. A sine wave without delay is supplied to the first inverting amplifier 40,
The second inverting amplifier 41 is supplied with a sine wave whose phase is delayed by 120 degrees. and a third inverting amplifier 42
will be supplied with a sine wave with a phase delay of 240 degrees.

The three inverting amplifiers 40, 41, and 42 each amplify the input sine wave and output it as it is from the positive side terminal, and also invert the input sine wave and output it from the negative side terminal. That is, the first inverting amplifier 40 supplies an amplified output of the logic circuit 46 with no phase lag to the base of the transistor 34, and a sine wave obtained by inverting this output to the transistor 34. I am trying to supply it to 37 bases. Similarly, the inverting amplifier 41 supplies an output with a phase delay of 120 degrees to the base of the transistor 35, and also supplies a sine wave obtained by inverting this to the base of the transistor 38. Similarly, the inverting amplifier 42 supplies a 240 degree phase-shifted sine wave to the base of the transistor 36, and also supplies the inverted sine wave to the base of the transistor 39.

One end of the three coils 31, 32, and 33 is connected to each other, and the other end is connected to a connection point between transistors 34 and 37, and a connection point between transistors 35 and 38.
and the connection point of transistors 36 and 39, respectively. Therefore, these coils 31, 32, and 33 are switched to be energized so as to be shifted from each other by 120 degrees, and the direction of current flow is reversed. For example, transistor 34 and transistor 3
8 is made conductive, a current flows from the power supply side to the coil 31 through the transistor 34, and further this current flows through the coil 32 and the transistor 38 to the ground side. On the other hand, when the transistor 35 and the transistor 37 become conductive at a certain rotational angle when the rotational position is shifted,
Current flows from the power supply side to the transistor 35, coil 32, coil 31, transistor 37, and ground in this order, and the direction of the current is reversed from the above case.

In this way, three coils 31, 32, 33
The current flowing in each of the rotor case 22 interlinks with the magnetic flux generated by the main magnet 23 held in the rotor case 22, so that the rotor case 22 receives the rotational force and rotates. In this way, the 3-phase brushless motor with 3 coils, 8 poles, and 120-degree bidirectional energization comes to generate rotational force, and this output rotates the recording medium via the chuck unit 17 or is installed in the case 22. It is now possible to take it out to the outside via the gear 24.

Furthermore, the chuck magnet 18 of the chuck portion 17 provided in the motor according to this embodiment is
As described above, the magnet 18 is not used as it is, but at least the exposed surface, that is, the inner peripheral surface and the upper surface, are covered with the resin coating layer 48. Therefore, it is possible to prevent the magnet 18 from being locally damaged and causing the magnetic powder to scatter. Therefore, it is possible to prevent such magnetic powder from entering the jacket and demagnetizing the sheet of the floppy disk, thereby causing errors.

Effects of the invention As described above, according to the invention, the magnet, which is housed and held inside the chuck portion and magnetically attracts the center core of the magnetic disk, has at least its exposed surface covered by the covering means. There is. Therefore, such a coating means can prevent the generation of magnetic powder from the magnet, and can prevent the negative effects of the magnetic powder. Therefore, such a magnetic chuck device makes it possible to prevent errors caused by magnetic powder generated by the magnet when writing or reading information to or from a magnetic disk.

In addition, the center core, which is attracted and held on the chuck by the attraction force of the magnet, is received by the reference surface formed on the chuck in a state that is higher than the height of the magnet, so that surface runout occurs when the magnetic disk rotates. It becomes possible to prevent
It becomes possible to write or read information using a magnetic disk in a stable state.

In addition, the center core attached to the center of the magnetic disk is centered by a ball bearing that rotatably supports the chuck relative to the stationary side, so it has an extremely simple structure. It becomes possible to center the magnetic disk accurately.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a chuck device according to an embodiment of the present invention, FIG. 2 is a plan view of the same, FIG. 3 is an exploded perspective view of a modified chuck device, and FIG. 4 is a plan view of the same. Figure 5 is a plan view of the motor, Figure 6 is a longitudinal sectional view of the same, Figure 7 is a plan view of the printed wiring board provided in this motor, Figure 8 is a side view of the same, and Figure 9 is the drive of the motor. It is a circuit diagram showing a circuit. In addition, in the symbols used in the drawings, 13... rotor boss, 14... ball bearing, 17... chuck part, 18... chuck magnet, 19
...Top end (reference surface), 20...Guide cap,
21... Inclined portion, 48... Resin coating layer,
49...Covering ring.

Claims (1)

[Claims for Utility Model Registration] A center core is attached to the center of a disk-shaped magnetic disk, and this center core is held and rotated on the chuck part using the attraction force of the magnet, and information is transmitted using the magnetic disk. A magnetic chuck device configured to magnetically write or read data, comprising: a chuck portion having a concave upper surface; the magnet stored and held inside the chuck portion; and the magnet held inside the chuck portion. a covering means that covers at least an exposed surface of the magnet; a reference surface formed on the chuck section at a height higher than the height of the magnet and receiving the center core of the magnetic disk; and a reference surface that allows the chuck section to rotate with respect to a fixed side. 1. A magnetic chuck device comprising a supporting ball bearing, wherein the center core is centered by an outer peripheral surface of an outer ring of the ball bearing.