JP2002101621A - Magnetizing method of magnet for speed sensor of floppy (r) disk device and magnetizing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely magnetize a magnet for a speed sensor in a floppy disk device which is capable of producing an index signal with high precision. SOLUTION: A rotor assembly A is positioned with a positioning jig 80 in a condition that it is set on a turn table 61. The positioning jig 80 has a first hole 81 and a second hole 82 which have the same shape as the center hole and a drive hole of a metal center core of a floppy disk respectively and of which the relation of each relative position is equal. The first hole 81 and the second hole 82 support a base pedestal 60 in a state respectively with a spindle shaft 20 and a drive pin 36 inserted. Then the assembly A is positioned in the rotational direction by giving the turn table 61 a torque and hitting the drive pin 36 to two connection faces 82a, 82b of the second hole 82. Next the magnet for the speed sensor is obtained by magnetizing a ring magnetic material 34' into plurality of poles in the circumferential direction by using a magnetizing yoke 62.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and a device for magnetizing a speed detecting magnet of a floppy disk drive.

[0002]

2. Description of the Related Art Conventionally, a floppy disk device has a spindle motor for rotating a floppy disk, as disclosed in Japanese Patent Application Laid-Open No. 8-7462. The spindle motor includes a substrate serving as a stator, a spindle shaft rotatably supported by the substrate, and a rotor fixed to the spindle shaft and arranged to face the substrate.

[0003] The rotor has a disk-shaped rotor yoke having a first surface and a second surface. A spindle shaft is fixed to the center of the rotor yoke and protrudes from the first and second surfaces. The first surface of the rotor yoke is a surface on which the metal center core of the floppy disk is mounted, and the second surface is a surface facing the substrate. Rotary torque is applied to the rotor by the main magnet provided on the second surface and the air-core coil provided on the substrate.

[0004] A pivot arm having spring properties is rotatably connected to the second surface of the rotor yoke at a position away from the spindle shaft. A drive pin is fixed to the tip of the rotating arm, and the drive pin penetrates the rotor yoke and protrudes from the first surface. The rotating arm is driven by an urging spring arranged on the second surface side of the rotor yoke.
It is biased to rotate.

[0005] A hub magnet is attached to the first surface of the rotor yoke, and the hub magnet, the spindle shaft, the drive pin, the rotating arm, and the urging spring constitute chucking means. That is, the hub magnet attracts the metal center core of the floppy disk, and the spindle shaft and the drive pin engage with the center hole and the drive hole of the metal center core. While the floppy disk is chucked and rotated by the rotor, data is recorded and reproduced on the floppy disk by the magnetic head.

A speed detecting magnet (FG magnet) magnetized to have more poles than the main magnet is provided on the outer peripheral edge of the rotor yoke, and the FG is provided on the substrate side.
Speed detection coil (FG coil) facing the magnet
And a speed generator (Frequency Generator) as a speed detecting means by both.
r) is configured. This speed generator detects the rotation speed of the rotor, and by feeding back the detected speed, stable rotation of the floppy disk is ensured.

[0007] Recording and reproduction by the magnetic head are performed along a track composed of a large number of concentric circles of a floppy disk. When recording or reproduction is performed in one round of one track, the magnetic head is moved by a very small amount in the radial direction of the floppy disk by the stepping motor to perform recording or reproduction on an adjacent track.

By the way, the starting point of recording or reproduction on the above-mentioned track must not vary from one floppy disk device to another. This is because data recorded on one floppy disk device cannot be reproduced on another floppy disk device. Therefore, the starting point of the track is determined by the JIS standard.

[0009] The starting point of the track is determined by the index signal. That is, when the floppy disk reaches a predetermined angular position, an index signal is output from the index signal output means, and recording and reproduction are started based on the index signal.

[0010] The index signal output means is provided for the one of the rotors.
An index signal of one pulse is output for each rotation. In the floppy disk drive disclosed in Japanese Patent Application Laid-Open No. Hei 2-10569, the magnetic flux of one pole of the main magnet is reduced to modulate the magnetic field, and the magnetic field modulation is detected by a Hall element on the substrate side, and an index signal is output. Like that.

[0011] As in a floppy disk drive described in Japanese Patent Application Laid-Open No. Hei 2-10569, one of the main magnets is used.
If one pole is subjected to magnetic field modulation, the timing of the index signal is shifted due to the effect of temperature change, so a temperature compensation circuit is required.

Therefore, a floppy disk device (a type without a temperature compensation circuit) has been developed in which an index signal generating means is formed by adding FG to the magnetic field modulated main magnet and Hall element. In this device, a primary signal of one pulse is generated for each rotation of the rotor based on the output of the Hall element that has detected the magnetic field modulation, and among the FG pulses output from the FG coil for each rotation of the rotor, the primary signal is output. The index signal is output with reference to the timing of the FG pulse output immediately after the signal. This eliminates the need for a temperature compensation circuit.

In the above-mentioned floppy disk drive (type without a temperature compensation circuit), the above-mentioned JP-A-7-105 is used.
Unlike the floppy disk device disclosed in Japanese Patent Publication No. 69-69, in order to ensure the accuracy of the index signal generation timing, the chucking position of the floppy disk by the chucking means and the position of the magnetic pole of the FG magnet have a fixed positional relationship. You need to keep it.

A conventional method and apparatus for magnetizing an FG magnet will be described with reference to FIG. The magnetizing device is a base 9
0, a support base 91 and a magnetized yoke 95 are provided. The support base 91 has a support hole 92 formed at the center and a support pin 93 provided at a position deviated from the center. The magnetized yoke 95 has an annular shape and is arranged concentrically outside the support base 91.

The assembly A is installed on the support base 91. The assembly A includes a rotor yoke 31, a spindle shaft 20 fixed at the center thereof, and a hub magnet 32.
, An annular magnetic body ′, a drive pin, and the like. The assembly A inserts the lower end of the spindle shaft 20 into the support hole 92 and the positioning hole 31 d of the rotor yoke 31.
Is fitted to the support pin 93, so that the support pin 91 is non-rotatably positioned. In this support state, the annular magnetic body 34 ′ faces the magnetized yoke 95 and the magnetized yoke 9
5, the magnet is magnetized in a large number of poles in the circumferential direction, and an FG magnet is obtained.

[0016]

However, FIG.
In the magnetizing method, the dimensional error of each component of the chucking means, that is, the spindle shaft, the drive pin, and the like, and the error of the mounting position appear as an error in the output timing of the index signal. There was an inconvenience that appeared as an error.

According to the present invention, an F signal capable of accurately generating an index signal in a floppy disk device is provided.
An object of the present invention is to provide a method and a device for magnetizing a G magnet.

[0018]

SUMMARY OF THE INVENTION The present invention relates to a floppy disk drive which has a speed detecting magnet and uses an output pulse from a speed detecting means for detecting a rotation speed of a rotor as a reference of an output timing of an index signal. A method of magnetizing the speed detecting magnet, comprising: a disk-shaped rotor yoke having a first surface and a second surface; and a first surface fixed to a center of the rotor yoke.
A spindle shaft protruding from a second surface, a revolving arm having resiliency rotatably connected to the second surface of the rotor yoke at a position distant from the spindle shaft, and fixed to a tip end of the revolving arm An assembly comprising: a drive pin that is penetrated through the rotor yoke and protrudes from the first surface; a biasing spring that biases the rotation arm to rotate; and an annular magnetic body attached to an outer peripheral edge of the rotor yoke. Making the assembly rotatable on the base via the spindle shaft, and causing the annular magnetic body to face an annular magnetized yoke provided on the base, and a floppy disk. The first hole and the second hole of the positioning jig having the same shape and the same relative positional relationship as the center hole and the driving hole of the metal center core of And the drive pin are respectively engaged to support the positioning jig at a predetermined position on the base, and the drive pin is brought into contact with the two engagement surfaces of the second hole to rotate the assembly. A step of positioning in the moving direction; and a step of magnetizing the annular magnetic body to a large number of poles in the circumferential direction by the magnetizing yoke to obtain the speed detecting magnet.

In the magnetizing method according to the present invention, even if there is a dimensional error or a mounting error of the chucking means including the driving pin, the driving pin abuts on the engaging surface of the second hole while absorbing these errors. In addition, the speed detection magnet can be magnetized, and the accuracy of the index signal generation timing can be improved.

Further, in the magnetizing method of the present invention,
By applying a rotational torque to the assembly, the magnetizing is performed in a state where the drive pin is in contact with the engagement surface of the second hole. As a result, magnetization can be performed in a state in which errors caused by bending of the rotating arm and inclination of the drive pin when the floppy disk is rotationally driven are absorbed, and the accuracy of the generation timing of the index signal is further improved. Can be improved.

Further, in the magnetizing method of the present invention,
The rotation torque applied to the assembly is substantially the same as the rotation torque when the rotor, which is a completed product of the assembly, drives the floppy disk to rotate. As a result, it is possible to absorb errors such as the bending of the rotary arm and the inclination of the drive pin, which are substantially the same as in the state where the floppy disk is actually driven to rotate, and to maximize the accuracy of the index signal generation timing.

Further, according to the present invention, in the floppy disk drive, the magnetizing device of the present invention has a speed detecting magnet and uses an output pulse from a speed detecting means for detecting a rotation speed of the rotor as a reference of an output timing of the index signal. An apparatus for magnetizing a speed detecting magnet, comprising: (a) a base; and (b) a rotatable arm rotatably supported by the base and having a rotor yoke, a spindle shaft, a spring property, and a drive pin. A rotary table for mounting and supporting an assembly including a spring and an annular magnetic body; and (c) being mounted on the base so as to surround the rotary table coaxially with the rotary table and supported by the rotary table. An annular magnetized yoke facing the annular magnetic body of the assembly, and (d) a relative position having the same shape as the center hole and the drive hole of the metal center core of the floppy disk. The positioning jig has a first hole and a second hole which are equal to each other, and is supported by the base in a state where the first hole and the second hole are engaged with the spindle shaft and the drive pin of the assembly. And (e) torque applying means for applying a rotational torque to the turntable to apply the drive pin to two engagement surfaces of the second hole.

According to the magnetizing device of the present invention, the speed detecting magnet is magnetized while the driving pin is in contact with the engagement surface of the second hole with the rotational torque, so that the chucking means including the driving pin is provided. Even if there are dimensional errors and mounting errors of the rotary arm, the deflection of the rotating arm and the inclination of the drive pin when rotating the floppy disk, the magnetization can be performed with these errors absorbed, and the timing of generating the index signal Accuracy can be improved.

Further, a shaft extending vertically downward through the base is fixed to the turntable of the magnetizing device of the present invention, and the torque applying means applies a rotational torque to the shaft. With this configuration, a rotational torque can be easily applied to the assembly via the shaft.

Further, the torque applying means of the magnetizing device according to the present invention further comprises: a first pulley fixed to an outer periphery of the shaft; a linear body having one end wound around the first pulley;
A second pulley that hangs the linear body and hangs the other end of the linear body downward; and a weight attached to the other end of the linear body. With this configuration, a desired rotational torque can be easily applied.

Further, a return lever is provided on the shaft of the magnetizing device of the present invention, and a first stopper for regulating the return lever at a first position and a second stopper for regulating the return lever at a second position are provided on the base. A stopper is provided, and when the return lever is at the first position, the positioning jig can be supported on the base in a state in which the positioning jig is engaged with a spindle shaft and a drive pin of the assembly; Return lever is first
The rotation torque acts in a direction from the position to the second position. With this configuration, the magnetizing operation can be easily performed.

Further, the rotary table of the magnetizing device of the present invention further comprises a support hole provided at the center of rotation, and a support pin which deviates from the support hole and projects vertically upward. Is supported by the turntable by accommodating the lower end of the spindle shaft in the support hole and engaging the support pin in a hole offset from the center of the rotor yoke. With this configuration, the assembly can be easily attached to the turntable.

Further, the base of the magnetizing device of the present invention is provided with a fitting pin vertically projecting outside the magnetizing yoke, and the positioning jig is provided with the first and second holes. The fitting jig has a fitting hole arranged on a straight line passing therethrough, and the fitting hole is formed by a long hole extending along the straight line, and the positioning jig is formed by inserting a fitting pin into the fitting hole. The base is horizontally rotatable and detachably supported. With this configuration, the positioning jig can be easily mounted on the base.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. First, the 3.5-inch floppy disk cassette 100 will be described with reference to FIG. The floppy disk cassette 100 includes a disk-shaped film made of polyethylene terephthalate (PET) or the like and a magnetic material applied to both sides of the disk-shaped film, a rectangular shell 102 for accommodating the floppy disk 101, and a floppy disk 101. Metal center core 103 attached to the center of the
And Metal center core 103 is shell 1
02 is exposed through a hole formed in the center of the lens. The shell 102 also has an elongated window 1 extending substantially in the radial direction.
02a is formed, and is opened and closed by a shutter (not shown). A portion of the floppy disk 101 is exposed from the open window 102a, and magnetic recording and reproduction are performed.

The metal center core 103 is made of a circular ferrite stainless steel plate and has a substantially square center hole 10.
5 and a substantially rectangular drive hole 1 offset from the center hole 105.
06. The drive hole 106 extends in a direction substantially perpendicular to the radial direction, and the side of the center hole 105 is inclined with respect to the longitudinal direction of the drive hole 106.

On both sides of the floppy disk 101, magnetic recording is performed along a number of concentric tracks 108. The starting point 108a for recording and reproduction of the track 108 is separated from a reference line 109 to be described later by a predetermined distance d (3.5 mm in the JIS standard).

Next, the overall configuration of the floppy disk device will be described with reference to FIG. The floppy disk device 1 performs magnetic recording and reproduction on a floppy disk 101. As shown in FIG. 4, a base 2, a holder 3 mounted on the base 2, an eject lever 4, and a recording / reproducing device. A mechanism 5, a step motor 6, a spindle motor 7, and the like are provided. The base 2 is in the form of a shallow box made of aluminum die-cast as shown in FIG.

The floppy disk cassette 100 is inserted into the floppy disk device 1 from the direction of arrow S in FIG.
Is discharged by the operation of.

The recording / reproducing mechanism 5 includes a carriage 5a, an arm 5b rotatably connected to a base of the carriage 5a via a thin plate spring in a direction perpendicular to the plane of FIG. 4, and a plate having high rigidity on the carriage 5a. , A magnetic head 5d attached to the distal end of the arm 5b via a spring material, and a load spring 5e for urging the arm 5b toward the carriage 5a. The pair of magnetic heads 5c and 5d are arranged so as to face each other in a direction perpendicular to the plane of the paper of FIG. 4, and sandwich the floppy disk 101 from both sides through the window 102a of the floppy disk cassette 100 to perform magnetic writing and writing. Perform reading.

A lead screw 6a, which is the output shaft of the step motor 6, is screwed to a follower (not shown) provided on the carriage 5a. When the step motor 6 rotates, the entire recording / reproducing mechanism 5 linearly moves by a minute amount, and accordingly, the magnetic heads 5c and 5d move by a minute amount substantially in the radial direction of the floppy disk 101. Recording and reproduction can be performed.

The spindle motor 7 is for rotatingly driving the floppy disk 101 at a predetermined number of revolutions, and is a planar opposed type brushless three-phase motor. As shown in FIGS. 5 and 6, the spindle motor 7 uses a printed board 10 made of a silicon steel plate as a stator, and the spindle 10 is rotated by a bearing (not shown). Supported as possible. A rotor 30 is attached to the spindle shaft 20. As shown in FIG. 5, the substrate 10 is fixed to the outer surface of the base 2 and the rotor 30 is
Is housed in the base 2 through the central hole 2a.

As shown in FIGS. 6 and 7, the rotor 30 of the spindle motor 7 has a disc-shaped rotor yoke 31
Hub magnet 32, main magnet 33, FG
And a magnet 34.

The rotor yoke 31 is formed by pressing a galvanized steel plate. As will be described later, a first surface 31x on which the floppy disk 101 is mounted and a second surface 31y facing the substrate 10 are provided. have. The rotor yoke 31 is fixed to the spindle shaft 20 by press-fitting the spindle shaft 20 into a central hole 31a. The spindle motor 20
The rotor yoke 31 protrudes from the first surface 31x and the second surface y.

The center of the rotor yoke 31 is
It has a convex portion 31b protruding toward the x side. The hub magnet 32 has an annular shape, and the first surface 31x has a convex portion 31b.
It is attached so that it surrounds. A thin resin sheet 35 is laid on the convex portion 31b, and the hub magnet 3
2 slightly higher than the surface of metal center core 10
3 is mounted. The hub magnet 32 is magnetized to a large number of poles (for example, 20 poles) in the circumferential direction in order to stably attract the metal center core 103.

The main magnet 33 is made of a sintered Nd-Fe-B magnet having a high energy product, has an annular shape larger in diameter than the hub magnet 32, and is attached to the second surface 31 y of the rotor yoke 31. The main magnet 33 is magnetized in, for example, a large number of poles (for example, 16 poles) in the circumferential direction. As shown in FIG. 9, the magnetic flux of one pole 33a of the main magnet 33 is reduced compared to the other poles, and the magnetic field is modulated.

The FG magnet 34 has an annular shape larger in diameter than the main magnet 33, and is attached to the outer peripheral edge of the rotor yoke 31. As shown in FIG. 9, the FG magnet 34 has more poles than the main magnet 33,
For example, it is magnetized to 96 poles in the circumferential direction.

Further, the rotor 30 has a drive pin 36. The drive pin 36, as best shown in FIG.
On the second surface 31y side of the rotor yoke 31, it is supported by a rotating arm 37 having spring properties. More specifically, the base end of the rotating arm 37 is rotatably connected by a stepped pin 38 at a position offset from the center of the rotor yoke 31. The direction in which the rotation arm can rotate is a direction along the second surface 31y. Rotating arm 37
The drive pin 36 is attached to the tip of the. The drive pin 36 is inserted into an insertion hole 31 c formed in the rotor yoke 31.
And has a play, and protrudes from the first surface 31x and also protrudes from the hub magnet 32 (see FIG. 6). The rotating arm 37 is urged by a linear urging spring 39 in a direction indicated by an arrow in FIG. 7, that is, in a direction away from the center. The biasing spring 39 has an intermediate portion wound around the stepped pin 38, one end of which is locked by the locking pin 39a,
The other end is hooked on the rotating arm 37.

The spindle shaft 20, hub magnet 32, drive pin 36, rotating arm 37, biasing spring 39
Constitutes a chucking means 40 for positioning and chucking the floppy disk 101. The rotor yoke 31 has a positioning hole 31d formed at a position deviated from the center to perform an operation described below.

As shown in FIG. 6, a plurality of, for example, 1
Two air-core coils 11 are annularly mounted at equal intervals in the circumferential direction. Further, for example, one Hall element 12 is disposed on the substrate 10 so as to face the main magnet 33. Further, a control IC 15 is attached to the substrate 10 at a position away from the rotor 30.

Rotation torque is generated by the magnetic flux generated from the main magnet 33 and the current flowing through the coil 11, and the rotor 30 rotates about the spindle shaft 20. A control IC in which the rotation position of the rotor 30 is detected by the Hall element 12 and receives this rotation position detection signal.
15 controls switching of the current flowing through the coil 11.

Further, as shown in FIG.
The FG coil 13 facing the G magnet 34 is printed. The pitch of the zigzag pattern of the FG coil 13 is the same as the pole of the FG magnet 34. The FG magnet 34 and the FG coil 13 constitute an FG (velocity detecting means) 50 of an all-round integral type. Since the FG coil 13 is constituted by a zigzag pattern and a return pattern, and noise is applied to these patterns in the same phase, substantially noise compensation is performed and a sufficient S / N is obtained.

Next, the operation of the floppy disk drive 1 will be described mainly with respect to the recording / reproducing mechanism 5 and the spindle motor 7. The floppy disk cassette 100 is inserted into the floppy disk device 1 and set. The metal center core 103 of the floppy disk 101 is attracted to the hub magnet 32 of the rotor 30 and the metal center core 1
The spindle shaft 20 enters the central hole 105 of 03. The drive pin 36 is located at a position where the drive pin 36 is pushed backward by the metal center core 103.

The floppy disk 101 has the magnetic head 5
When the rotor 30 rotates while being sandwiched between c and 5d,
The drive pin 36 of the rotor 30 is
11 and protrudes from the first surface 31x of the rotor yoke 31 by the elastic force of the rotating arm 37.
As shown in FIG. Thus, the floppy disk 101 can be rotated with the rotation of the rotor 30.

The floppy disk 101 has the rotor 30
Is positioned on the rotor 30 while being rotated together with. The details will be described below. Before the drive pin 36 is engaged with the drive hole 106, the drive shaft 36 is rotated by the force of the biasing spring 39.
It is urged away from zero, but its movement is restricted by the peripheral surface of the insertion hole 31c of the rotor yoke 31,
It is at a maximum distance from the spindle shaft 20.
When the drive pin 36 rotates clockwise in FIG. 12, the drive pin 36 enters the left end of the rectangular drive hole 106. When the drive pin 36 further rotates clockwise, the peripheral surface thereof comes into contact with the engagement surface 106 a of the drive hole 106 (a surface constituting a long side remote from the spindle shaft 20). When the drive pin 36 further rotates, the drive pin 36
, And in this process, approaches the spindle shaft 20 against the urging force of the urging spring 39. Eventually, the drive pin 36 comes into contact with the engagement surface 106b of the drive hole 106 (the surface constituting the right short side of the rectangle). Thus, the floppy disk 101 is positioned with respect to the rotor 30.

As described above, the drive pin 36 and the engagement surface 1
06a is secured by the biasing force of the biasing spring 39, and the drive pin 36 and the engagement surface 106b are in contact with the rotor 3
It is ensured by a rotation torque of zero. In addition, the spindle shaft 20 is provided with a center hole 105 of the metal center core 103.
The play is inserted with play, but by the biasing force of the biasing spring 39 (the force for separating the distance between the spindle shaft 20 and the drive pin 36) and the component force from the rotational torque,
The engaging surfaces 105a, 105 of the center hole 105 which are orthogonal to each other.
hit b. Thus, the rotation center of the floppy disk 101 is also positioned.

As described above, the FG 50 plays the role of detecting the instantaneous rotational speed of the rotor 30, and constitutes an index signal output means together with the pole 33a of the main magnet 33 and the Hall element 12 subjected to the magnetic field modulation. The index signal is used as a reference when formatting the floppy disk 101 so that the floppy disk 101 can be used, and necessary output timing accuracy is required to maintain data compatibility between the floppy disk devices.

The leading edge of the index signal shown in FIG.
Each track 1 of the floppy disk 101 shown in FIG.
08 is a signal for indicating the start position 108a. At the timing of the leading edge of the index signal, the magnetic heads 5c,
The position of the magnetic gap of 5d is determined by the JIS standard so as to be apart from the reference line 109 by a predetermined distance d (0.35 mm). It should be noted that the reference line 109 of the floppy disk 101 corresponds to the center hole 105 of the spindle shaft 20 having accurate dimensions and the drive pin 36.
Engaging surfaces 105a, 105b of the driving hole 106
The line connecting the center of the spindle shaft 20 and the center of the drive pin 36 in a state where it hits 06a and 106b.

The generation of the index signal will be described in detail. As shown in FIG. 10, the output (pulse shaped into a rectangular wave) from the Hall element 12 is
3 and is output as 16 pulses per rotation of the rotor 30 because the main magnet 33 is magnetized to 16 poles. Since one pole 33a of the main magnet is magnetically modulated (index magnetized) so as to have a low magnetic flux density, the output VB corresponding to the magnetically modulated pole 33a is higher than the output VA corresponding to the other pole. Output VA of index magnetized part
Lower. A control circuit (not shown) latches a zero-cross point after detecting the output VB. Then, the falling edge of the next FG output (pulse shaped into a rectangular wave) is used as the starting point of the index signal. The width of the index signal is two cycles of the FG output. The index signal is generated in this process. That is, a primary signal is obtained by detecting magnetic modulation (index magnetization), and this primary signal is re-created as an index signal with reference to the timing of FG output.

The rotation speed of the spindle motor is 300 revolutions per minute, and the time required for one revolution is 200 ms.
The allowable error of the output timing of the index signal is 40
0 μs, which is 0.72 ° in terms of mechanical angle. Note that this allowable error is defined for scanning on the track 108 located in the middle in the radial direction.

FIG. 12 is a diagram for explaining the error of the index signal. When the driving pin 36 has an accurate diameter shown by a solid line, a line connecting the center 36a and the center 20a of the spindle shaft 20 becomes a reference line 109 determined by the standard. However, when the drive pin 36 has a diameter as shown by the imaginary line in FIG. 12 due to a dimensional error, the center 36a of the drive pin 36 is shifted, and this center 36a
line 1 connecting a to the center 20a of the spindle shaft 20
09 ′ deviates from the reference line 109, and an angle error Δe occurs. This angle error Δe leads to an error in the output timing of the index signal. A similar error occurs when the drive pin 36 is fixed to the rotary arm 37 by being inclined and caulked.

Further, when the driving pin 36 contacts the engagement surfaces 106a and 106b in a state where the rotation torque is applied, the bending of the rotating arm 37 and the inclination of the driving pin 36 occur. This may cause an output timing error. Such bending of the rotation arm 37 and the inclination of the drive pin 36 are also affected by the play between the stepped pin 38 and the hole of the rotation lever 37 and the mounting position accuracy of the stepped pin 38.

Next, the assembly of the rotor 30 will be described. In particular, the description will focus on the magnetization of the FG magnet 34 that can eliminate the error in the output timing of the index signal. First, an annular magnetic body for a hub magnet and an annular magnetic body for an FG magnet are provided on the rotor yoke 31 by outsert molding. Both annular magnetic bodies use ferrite plastic magnets having the same composition.

Next, as shown in FIG.
1 and the drive shaft 36, the rotating lever 37, the stepped pin 38, the urging spring 39, and the locking pin 39a are assembled together to form an assembly A.
Next, the hub magnet 32 is obtained by magnetizing the annular magnetic body attached to the first surface 31x of the rotor yoke 31 at 80 V and 500 μF.

Next, the FG magnet 34 is magnetized using the magnetizing device shown in FIGS. The magnetizing device includes a base 60, and a turntable 61 is supported on the base 60 so as to be horizontally rotatable. The turntable 61 has a support hole 61a formed at the center, and a support pin 61b provided at a position offset from the center. The turntable 6 is provided on the base 60.
An annular magnetized yoke 62 is installed so as to be coaxial with 1 and surround the turntable 61. On the upper surface of the base 60, a fitting pin 63 that is perpendicular to the outside of the magnetized yoke 62 is provided.

From the turntable 61, a shaft 64 is attached to the base 60.
And extends vertically downward. This shaft 64
Is provided with a torque applying mechanism 65 (torque applying means). The torque applying mechanism 65 includes a first pulley 66 fixed to the outer periphery of the shaft 64, a thread 67 (linear body) having one end wound around the first pulley 66, and the other end of the thread 67 A second pulley 68 for hanging the portion downward, and a thread 6
7 and a weight 69 attached to the other end.

A return lever 70 is horizontally fixed to the shaft 64. The return lever 70 is firstly attached to the base 60.
A first stopper 71 that regulates at a position and a second stopper 72 that regulates at a second position are provided.
Is movable only between the first and second positions. According to the movement range of the return lever 70, the shaft 64,
As a result, the rotation range of the turntable 61 is also restricted. Although a torque is applied to the shaft 64 by the weight 69 of the rotation torque applying mechanism 65, the turntable 61 is stationary because the return lever 70 contacts the second stopper 72.

Further, the magnetizing device has an elongated plate-shaped positioning jig 80. This positioning jig 80
Metal center core 103 of floppy disk 101
The first hole 81 and the second hole 82 have the same shape as the center hole 105 and the driving hole 106 and have the same relative positional relationship.
The first hole 81 is provided with the engagement surfaces 105a, 105 of the center hole 105.
b. Second
The hole 82 has engagement surfaces 82a, 82b corresponding to the engagement surfaces 106a, 106b of the drive hole 106. The positioning jig 80 further has a fitting hole 83 that fits into the fitting pin 63 of the base 60, and an arc-shaped play hole 84 through which the support pin 61 b of the turntable 61 is inserted. The fitting hole 83 is disposed on a straight line passing through the first hole 81 and the second hole 82,
It is an elongated hole extending along this straight line.

The magnetization of the FG magnet 34 is performed as follows. First, the assembly A is set on the turntable 61. That is, the lower end of the spindle shaft 20 of the assembly A is fitted into the center support hole 61a of the turntable 61, and the positioning hole 31d of the rotor yoke 31 is inserted through the support pin 61b. In this state, the annular magnetic body 34 ′ of the assembly A faces the magnetized yoke 62 and is in contact with or approaching.

In the setting state of the assembly A, the operator turns the return lever 70 against the weight 69 to rotate the first lever 7.
1, the turntable 61 and the assembly A are also rotated. In this state, the positioning jig 80 is set on the base 60 and the assembly A. That is, the fitting pin 63 of the base 60 is fitted into the fitting hole 83 of the positioning jig 80, and the first
The spindle shaft 20 and the drive pin 36 are set so as to be fitted in the holes 81 and the second holes 82.

Next, when the operator releases the return lever 70, the weight 69 rotates the shaft 20 and the turntable 61, and eventually the assembly A rotates. As a result, the drive pin 36 comes into contact with the engagement surfaces 82a and 82b of the second hole 82. Metal center core 1 of floppy disk 101
As in the case of 03, the contact between the drive pin 36 and the engagement surface 82a is ensured by the urging force of the urging spring 39, and the contact between the drive pin 36 and the engagement surface 82b is ensured by the rotational torque of the weight 69. At this time, the spindle shaft 20
Due to the force acting on the positioning jig 80, that is, the biasing force of the biasing spring 39 and the component force from the rotational torque, the contacting surfaces 81 a and 81 b of the first hole 81 are orthogonal to each other. The positioning jig 80 is rotatable with respect to the base 60, and the fitting pin 63 has a play in the fitting hole 83 in the longitudinal direction, so that the positioning pin 80 moves in a straight line direction in which the spindle shaft 20 and the driving pin 36 pass. Of the first hole 81 can be moved.
Engagement of the spindle shaft 20 and the drive pin 36 with the engagement surfaces 82a and 82b of the second holes 82 is secured.

The positioning jig 12 stops at a predetermined position after the spindle shaft 20 hits the engaging surfaces 81a and 81b, and the driving pin 36
When engaging with 2a, 82b, the rotation of the assembly A is also stopped and positioned.

With the assembly A positioned, the magnetized yoke 6
2 is operated at 350 V, 500 μF, and the annular magnetic body 3
4 ′ is magnetized to obtain a multi-pole FG magnet 34. A large relative position of the assembly A and a large number of magnetized portions of the magnetized yoke 62 can be ensured irrespective of the dimensional error and the mounting error of the chucking means 40.
The G magnet 34 can be magnetized with high precision.

This will be described with reference to FIG. Drive pin 3
When 6 has the exact diameter shown by the solid line, the line connecting its center 36a and the center 20a of the spindle shaft 20 is denoted by 8
9. When the drive pin 36 has a diameter as shown by an imaginary line due to a dimensional error, the engagement surfaces 82a, 82b
The center 36a of the drive pin 36 is displaced in the state in which the
9 'deviates from line 89. However, even if there is an angular error Δe between the lines 89 and 89 ′, the positional relationship between the first hole 81 and the second hole 82 and the magnetization yoke 62 is the same as when the drive pin 36 has an accurate diameter. Therefore, in the assembly A positioned as shown in FIG. 3, the FG magnet 34 can be accurately magnetized. For the same reason, even when the drive pin 36 is fixed to the rotary arm 37 by caulking while tilting, the mounting error can be absorbed and accurate magnetization can be performed.

Further, the weight of the assembly A is
At the time of actual use, the rotor 30 is
Since the FG magnet 34 is magnetized in a state in which the same rotational torque (0.29 N-cm) as the rotational torque applied to the metal center core 103 of FIG.
Accurate magnetization can be performed by also compensating for the bending of the rotating arm 37 and the inclination of the drive pin 36 caused by the reaction force of the rotating torque.

After the FG magnet 34 has been magnetized, the positioning jig 80 and the assembly A are removed from the base 60. Turntable 61
Stops at the position where the return lever 70 hits the second stopper 72, and enters a standby state.

Next, the main magnet 33 is mounted on the rotor yoke 31 of the assembly A. Since the sintered magnet of Nd-Fe-B having a high energy product is used for the main magnet 33, when the rotor yoke 31 is magnetized with the back yoke, the rotor yoke is saturated, and the main magnet 33 cannot be fully magnetized. . For this reason, before being mounted on the rotor yoke 31, soft iron having a sufficient thickness is used as a back yoke and magnetized alone (1500).
V / 1000 μF).

The rotor yoke 31 of the main magnet 33
The attachment to the device is performed using the positioning hole 31d. In order to ensure the accuracy of the output timing of the index signal, the mounting accuracy of the main magnet 33 only needs to be less than the pole pitch of the FG magnet 34, so that the positioning can be easily performed.

In this manner, the rotor 30 is assembled and assembled to the substrate 10 via the spindle shaft 20, whereby the spindle motor 7 is completed.

As described above, the floppy disk 10
Positioning jig 80 simulating one metal center core 103
As if the spindle shaft 20 and the drive pin 36 are engaged with the engagement surfaces 105a and 105b of the center hole 105 of the metal center core 103, the engagement surfaces 106a of the drive hole 106,
In the state where the FG magnet 34
Therefore, even if there is a dimensional error or a mounting error of the chucking means 40, the magnetization can be performed accurately. As a result, the position of the pole of the FG magnet 34 and the floppy disk 1 chucked by the rotor 30 and positioned by the drive pin 36 and the spindle shaft 20
01 means that a certain positional relationship can be maintained with high accuracy, and the index signal based on the FG output can accurately indicate the start point of the track 108.

The present invention is not limited to the above-described embodiment, but can adopt various forms. For example, the hub magnet may be magnetized after the FG magnet is magnetized. FG
The magnet can be re-magnetized and corrected.
At this time, since the energy product of the main magnet is high, it is not affected by the re-magnetization of the FG magnet.

[0076]

As described above, according to the present invention, the error of the chucking means can be absorbed and the speed detecting magnet can be magnetized with high accuracy. Can be made highly accurate.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an upper structure and a rotor assembly of a magnetizing device according to an embodiment of the present invention.

FIG. 2 is a side view showing, in partial cross section, a magnetizing device according to an embodiment of the present invention.

FIG. 3 is a plan view showing a positioning state of the assembly by the magnetizing device according to the embodiment of the present invention.

FIG. 4 is a plan view of the floppy disk device.

FIG. 5 is an exploded perspective view of a base and a spindle motor of the floppy disk device.

FIG. 6 is a perspective view showing a spindle motor with a part cut away.

FIG. 7 is an exploded perspective view of a rotor of the spindle motor.

FIG. 8 is a plan view showing an FG coil of the spindle motor.

FIG. 9 shows a main magnet and FG of a spindle motor.
It is a bottom view showing the magnetized state of the magnet.

FIG. 10 is a time chart showing an index signal and a signal related thereto.

FIG. 11 is a plan view showing the floppy disk mounted on the rotor.

FIG. 12 is an enlarged plan view showing a state in which a spindle shaft and a drive pin of a rotor are engaged with a center hole and a drive hole of a floppy disk, respectively.

FIG. 13 is a perspective view showing a conventional magnetizing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Floppy disk 7 Spindle motor 10 Substrate 13 FG coil (speed detection coil) 20 Spindle shaft 30 Rotor 31 Rotor yoke 31x First surface 31y Second surface 32 Hub magnet 33 Main magnet 34 FG magnet (Speed detection magnet) 34 'Annular Magnetic body 36 Drive pin 37 Rotating arm 39 Urging spring 40 Chucking means 50 FG (speed detecting means) 60 Base 61 Rotary table 61a Support hole 61b Support pin 62 Magnetization yoke 63 Fitting pin 64 Shaft 65 Torque applying mechanism (Torque applying means) 66 First pulley 67 Thread (linear body) 68 Second pulley 69 Weight 70 Return lever 71 First stopper 72 Second stopper 80 Positioning jig 81 First holes 81a, 81b Engagement surface 82 Second Hole 82a, 82b engagement 83 fitting hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 21/24 H02K 21/24 M 5H622 G 29/12 29/12 // G11B 17/028 611 G11B 17 / 028 611 F-term (Reference) 5D038 BA04 CA04 DA02 5D109 BA03 BA12 BA37 BB12 5H002 AA09 AB07 AC04 AE08 5H019 BB09 BB15 BB19 BB23 CC02 CC07 DD06 EE07 5H621 GA02 HH05 HH10 JK08 JK14 JK15 CA01B06 PP06 Q06 CB09

Claims (9)

[Claims] 1. A floppy disk drive having a speed detecting magnet and using an output pulse from a speed detecting means for detecting a rotation speed of a rotor as a reference of an output timing of an index signal, wherein the speed detecting magnet is magnetized. A disk-shaped rotor yoke having a first surface and a second surface, a spindle shaft fixed to a center of the rotor yoke and protruding from the first surface and the second surface, and separated from the spindle shaft. A resilient pivot arm rotatably coupled to the second surface of the rotor yoke at a position;
A drive pin fixed to the tip of the rotating arm and penetrating the rotor yoke and protruding from the first surface, a biasing spring for biasing the rotating arm to rotate, and attached to an outer peripheral edge of the rotor yoke. Forming an assembly including an annular magnetic body; and an annular magnetized magnet provided on the base such that the assembly is rotatably mounted on the base via the spindle shaft. Opposing the yoke; and positioning the first and second holes of the positioning jig having the same shape and the same relative positional relationship as the center hole and the driving hole of the metal center core of the floppy disk with the spindle shaft of the assembly. By engaging with the drive pins respectively, supporting the positioning jig at a predetermined position on the base, and applying the drive pins to two engagement surfaces of the second hole, Positioning the three-dimensional body in the rotation direction, and magnetizing the annular magnetic body to a large number of poles in the circumferential direction by the magnetized yoke to obtain the speed detecting magnet. Method for magnetizing the speed detecting magnet of a floppy disk drive. 2. The magnetizing device according to claim 1, wherein the magnetizing is performed by applying a rotational torque to the assembly so that the driving pin is in contact with the engaging surface of the second hole. A magnetizing method for the speed detecting magnet of the floppy disk device according to the above. 3. The rotating torque applied to the assembly is substantially the same as the rotating torque when a rotor, which is a completed product of the assembly, drives and rotates a floppy disk. The method for magnetizing the speed detecting magnet of the floppy disk device of the present invention. 4. A floppy disk drive having a speed detecting magnet and using an output pulse from a speed detecting means for detecting a rotation speed of a rotor as a reference of an output timing of an index signal, wherein the speed detecting magnet is magnetized. A rotating base having a rotor yoke, a spindle shaft, a spring property, a driving pin, an urging spring, and a ring-shaped magnetic body. And (c) the annular magnetic member of the assembly mounted on the base so as to surround the turntable coaxially with the turntable and supported by the turntable. An annular magnetized yoke facing the body; and (d) a first hole and a second hole having the same shape and the same relative positional relationship as the center hole and the drive hole of the metal center core of the floppy disk. A positioning jig having a hole and supported by the base in a state where the first and second holes are engaged with the spindle shaft and the drive pin of the assembly;
(E) torque applying means for applying a rotational torque to the turntable to apply the drive pin to the two engagement surfaces of the second hole. Magnet magnetizing device. 5. The rotary table according to claim 4, wherein a shaft that extends vertically downward through the base is fixed to the turntable, and the torque applying unit applies a rotational torque to the shaft. Magnetizing device for speed detection magnet of floppy disk drive. 6. The torque applying means includes: a first pulley fixed to an outer periphery of the shaft; a linear body having one end wound around the first pulley; The speed detecting magnet according to claim 5, further comprising a second pulley for hanging the other end of the body downward, and a weight attached to the other end of the linear body. Magnetizer. 7. A return lever is provided on the shaft, and a first stopper for restricting the return lever at a first position and a second stopper for restricting the return lever at a second position are provided on the base. When the return lever is at the first position, the positioning jig can be supported on the base while being engaged with a spindle shaft and a drive pin of the assembly, and the return lever can be moved from the first position to the first position. 6. The magnetizing device according to claim 5, wherein the rotational torque acts in a direction toward two positions. 8. The rotary table has a support hole provided at the center of rotation and a support pin that is deflected from the support hole and vertically projects upward, and the assembly includes a lower end portion of the spindle shaft. 5. The floppy disk drive according to claim 4, wherein the support hole is accommodated in the support hole and the support pin is engaged with the hole deviated from the center of the rotor yoke to be supported by the turntable. Magnetization device for speed detection magnet. 9. A fitting in which the base is provided with a fitting pin vertically protruding outside the magnetized yoke, and wherein the positioning jig is arranged on a straight line passing through the first and second holes. Having a mating hole, the fitting hole is formed of an elongated hole extending along the straight line, and by inserting a fitting pin into the fitting hole, the positioning jig can be horizontally rotated with respect to the base and The magnetizing device for a speed detecting magnet of a floppy disk drive according to claim 4, wherein the magnet is supported detachably.