JP2001256624A - Magnetic head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic head device, suitable for high density recording which is capable of surely performing recording/reproducing in a narrow recording track. SOLUTION: This device is provided with a cylindrical fixed drum, a rotary shaft inserted into the center of the fixed drum, a rotating drum, disposed so as to be freely rotatable about the rotary shaft inserted into the fixed drum, and at least one or more magnetic heads disposed, so as to be protruded from the peripheral surface of the rotating drum. A ball bearing is disposed between the rotary shaft and the fixed drum, and a ball is disposed in the bearing, the ball having roundness as stipulated by JIS standard B1501, of 0.05 μm or smaller, and surface roughness (center line average roughness) regulated by JIS standard B1501, of 0.05 μm or smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head device for recording and / or reproducing signals on, for example, a tape-shaped magnetic recording medium.

[0002]

2. Description of the Related Art Conventionally, there has been known a magnetic head device provided with a rotating drum having a magnetic head for performing recording and reproduction on a tape-shaped magnetic recording medium. This magnetic head device is used for a recording / reproducing device of a so-called helical scan magnetic recording system. The magnetic head device is
For example, a cylindrical fixed drum that is not driven to rotate, a rotary drum rotatably disposed with respect to the fixed drum, a plurality of magnetic heads protruding from the peripheral surface of the rotary drum, and rotating the rotary drum And a motor. Also,
A lead guide portion is engraved on the peripheral surface of the fixed drum so that the tape-shaped magnetic recording medium is obliquely engaged with the tape-shaped magnetic recording medium.

[0003] The magnetic recording / reproducing apparatus has a running system for running a tape-shaped magnetic recording medium while attaching a magnetic head device. The traveling system draws the tape-shaped magnetic recording medium from a supply roll around which the tape-shaped magnetic recording medium is wound, ties the tape-shaped magnetic recording medium to a magnetic head device, and a lead guide section engraved on a fixed drum. The tape-shaped magnetic recording medium is caused to travel along.

In the magnetic head device, the rotating drum rotates while the tape-shaped magnetic recording medium travels along the lead guide portion, so that the tape-shaped magnetic recording medium moves at a predetermined angle with respect to the longitudinal direction of the traveling tape-shaped magnetic recording medium. The magnetic head is scanned while tilted. Thereby, the magnetic head device forms a recording track inclined at a predetermined angle with respect to the longitudinal direction of the tape-shaped magnetic recording medium.

[0005]

In recent years, with the increase in the amount of information to be handled, even in a helical scan magnetic recording system, it is necessary to perform high-density recording and reproduction of signals on a tape-shaped magnetic recording medium. . Therefore, the magnetic properties of the tape-shaped magnetic recording medium are required to be improved for high-density recording.
Improvements in various characteristics are required to perform stable high-density recording.

[0006] A magnetic head device is required to record a signal on a tape-shaped magnetic recording medium on a narrow recording track and to reliably reproduce a signal recorded at a narrow track pitch. However, in the conventional magnetic head device, an unstable position shift called “rotational non-periodic run-out” occurs with the rotation of the rotary drum. The magnetic head device has a problem that accurate recording and reproduction cannot be performed when the rotation aperiodic vibration occurs.

In particular, when recording and reproduction are performed on a narrow recording track using a conventional magnetic head device, the recording track fluctuates due to the non-periodic rotation of the rotation, and recording and reproduction are impossible. Sometimes it becomes. In other words, the conventional magnetic head device has a problem that high-density recording in which recording and reproduction are performed on a narrow recording track cannot be realized.

Accordingly, the present invention has been devised in view of the above-mentioned conventional circumstances, and enables a magnetic head device suitable for high-density recording that can reliably perform recording and reproduction on a narrow recording track. The purpose is to provide.

[0009]

In order to achieve the above-mentioned object, the present inventor has investigated the causes of the non-periodic rotation of the rotation, and has conducted intensive studies to solve the above problems. The present inventors have found that by improving the accuracy of the ball bearings arranged, it is possible to significantly reduce the non-periodic rotation of the rotation, and have completed the present invention.

That is, the magnetic head device according to the present invention comprises a cylindrical fixed drum, a rotating shaft inserted through the center of the fixed drum, and a rotatable shaft around the rotating shaft inserted through the fixed drum. A magnetic head device comprising: a rotating drum provided; and at least one or more magnetic heads disposed so as to protrude from a peripheral surface of the rotating drum. , A ball bearing is provided, and the ball bearing is provided with JIS standard B1501.
Characterized in that balls having a sphericity of not more than 0.05 μm and a surface roughness (center line average roughness) of not more than 0.005 μm specified in JIS B1501 are provided. Things.

In the magnetic head device according to the present invention configured as described above, a ball bearing having a ball having a defined sphericity and surface roughness is disposed between the fixed drum and the rotating shaft, and the ball bearing Supports the fixed drum. This ball bearing reduces frictional resistance between the rotating shaft and the fixed drum. In this magnetic head device, it is possible to prevent the rotation aperiodic run-out due to the ball in the ball bearing.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of a magnetic head device according to the present invention will be described in detail with reference to the drawings.

In the following example, as shown in FIG. 1, a recording track is formed obliquely inclined at a predetermined angle with respect to the longitudinal direction of a tape-shaped magnetic recording medium 1 (hereinafter referred to as a magnetic tape 1). A magnetic head device 3 used in the recording / reproducing device 2 of a so-called helical scan magnetic recording / reproducing system will be described.

The recording / reproducing apparatus 2 is disposed at one end of a traveling path of the magnetic tape 1 and is disposed at a supply reel 4 around which the magnetic tape 1 is wound, and is disposed at the other end of the traveling path, and travels on the traveling path. A take-up roll 5 for winding the magnetic tape 1;
And a capstan motor 7 and a capstan 8 for moving the magnetic tape 1 at a predetermined tension and speed. That is, the magnetic tape 1 is sent at a predetermined tension and speed by a capstan 8 that is driven to rotate by a capstan motor 7, and is sent from the supply reel 4 through the guide roller 6 and wound around the magnetic head device 3. The recording and reproduction are performed by the magnetic head device 3. The magnetic tape 1 recorded and reproduced by the magnetic head device 3 is sent to the take-up roll 5 through the guide roller 6, the capstan 8, and the guide roller 6 in this order.

As shown in FIGS. 2 and 3, the magnetic head device 3 comprises a cylindrical fixed drum 10, a cylindrical rotary drum 11, a motor 12 for driving the rotary drum 11, and a rotary A pair of inductive magnetic heads 13a and 13b mounted on the drum 11;
And a pair of MR heads 14a and 14b mounted on the.

The fixed drum 10 is a drum that is held without rotating. On the side surface of the fixed drum 10, a lead guide 1 is provided along the running direction of the magnetic tape 1.
5 are formed. As described above, the magnetic tape 1 travels along the lead guide 15 on the traveling path. The rotating drum 11 is disposed so that the center axis of the fixed drum 10 coincides with the center axis.

The rotary drum 11 is a drum that is driven to rotate at a predetermined rotation speed by a motor 12 during recording and reproduction on the magnetic tape 1. The rotating drum 11 is formed in a cylindrical shape having substantially the same diameter as the fixed drum 10, and is arranged such that the center axis of the rotating drum 11 coincides with that of the fixed drum 10. Then, a pair of inductive magnetic heads 13a, 13
b and a pair of MR heads 14a and 14b are mounted on the side of the rotating drum 11 facing the fixed drum 10.

Inductive magnetic heads 13a, 13
Reference numeral b denotes a recording magnetic head in which a pair of magnetic cores are joined via a magnetic gap and a coil is wound around the magnetic core, and is used when recording a signal on the magnetic tape 1. . The inductive magnetic heads 13a and 13b are respectively formed on the rotating drum 11 such that the angle formed therebetween with respect to the center of the rotating drum 11 is 180 °, and their magnetic gap portions protrude from the outer periphery of the rotating drum 11. It is installed. In addition,
These inductive magnetic heads 13a, 13b
Is to perform azimuth recording on the magnetic tape 1,
The azimuth angles are set to be opposite to each other.

On the other hand, the MR heads 14a and 14b are reproducing magnetic heads having an MR element as a magnetic sensing element for detecting a signal from the magnetic tape 1, and are used when reproducing a signal from the magnetic tape 1. . These MR heads 14a and 14b form an angle of 180 ° with the center of the rotating drum 11 so that the magnetic gap portion protrudes from the outer periphery of the rotating drum.
It is installed in. Note that these MR heads 14a,
14b is set so that the azimuth angles are opposite to each other so that signals recorded in azimuth on the magnetic tape 1 can be reproduced.

The magnetic recording / reproducing apparatus 2 records signals on the magnetic tape 1 and reproduces signals from the magnetic tape 1 by sliding the magnetic tape 1 on such a magnetic head device 3.

At this time, the rotary drum 11 is driven to rotate by a motor 12 as shown by an arrow A in FIG. On the other hand, the magnetic tape 1 is moved along the lead guide portion 15 of the fixed drum 10 and the fixed drum 10 and the rotating drum 1.
It is sent to slide diagonally to 1. That is,
The magnetic tape 1 is fed along the tape running direction from the tape inlet side along the lead guide portion 15 so as to be in sliding contact with the fixed drum 10 and the rotating drum 11 as shown by an arrow B in FIG. 2 As shown by an arrow C in FIG.

Next, the internal structure of the magnetic head device 3 will be described with reference to FIG.

A rotary shaft 16 is inserted through the center of the fixed drum 10 and the rotary drum 11. Note that the fixed drum 10, the rotating drum 11, and the rotating shaft 16 are made of a conductive material, are electrically conductive, and the fixed drum 10 is grounded.

Further, inside the sleeve of the fixed drum 10, two ball bearings 17a and 17b are provided.
Thus, the rotating shaft 16 is rotatably supported by the fixed drum 10. That is, the rotating shaft 16 is rotatably supported by the fixed drum 10 by the ball bearings 17a and 17b. On the other hand, the rotating drum 11 has a flange 18 formed on the inner peripheral portion thereof, and the flange 18 is fixed to the upper end of the rotating shaft 16. Thus, the rotating drum 11 is configured to rotate with the rotation of the rotating shaft 16.

In particular, in the magnetic head device 3, a plurality of balls 19 disposed inside the ball bearings 17a and 17b are provided.
Is that the sphericity defined by JIS standard B1501 is 0.0
The surface roughness is not more than 5 μm and the surface roughness (center line average roughness) specified in JIS B1501 is not more than 0.005 μm. Also, this ball 19 is JIS standard B1501
Is preferably 0.05 μm or less.

A rotary transformer 25, which is a non-contact type signal transmission device, is disposed inside the magnetic head device 3 for transmitting signals between the fixed drum 10 and the rotating drum 11. . This rotary transformer 25
A stator core 26 attached to the fixed drum 10,
And a rotor core 27 attached to the rotating drum 11.

The stator core 26 and the rotor core 27
A magnetic material such as ferrite is formed in an annular shape around the rotation axis. The stator core 26 includes a pair of inductive magnetic heads 13a and 13b.
A pair of signal transmission rings 26a, 26b corresponding to
A signal transmission ring 26c corresponding to the pair of MR heads 14a and 14b, and a power transmission ring 26 for supplying power required for driving the pair of MR heads 14a and 14b.
d are arranged concentrically. Similarly, the rotor core 27 also has a pair of inductive magnetic heads 13.
a, a pair of signal transmission rings 27a corresponding to 13b,
27b, a signal transmission ring 27c corresponding to the pair of MR heads 14a, 14b, and a pair of MR heads 14a,
A power transmission ring 27d for supplying power required for driving the 14b is arranged concentrically.

These rings 26a, 26b, 26c,
Reference numerals 26d, 27a, 27b, 27c, and 27d each include a coil wound in an annular shape around the rotation axis, and each of the rings 26a, 26b, 26c, and 26d of the stator core 26.
And each ring 27a, 27b, 27 of the rotor core 27
c and 27d are arranged to face each other.
The rotary transformer 25 is connected to the stator core 2
6, each ring 26a, 26b, 26c, 26d and each ring 27a, 27b, 27c, 27d of the rotor core 27.
, Signals and power are transmitted in a non-contact manner.

The magnetic head device 3 is provided with a motor 12 for driving the rotary drum 11 to rotate. The motor 12 includes a rotor 28 as a rotating part,
And a stator 29 which is a fixed portion. Rotor 2
8 is attached to the lower end of the rotating shaft 16 and includes a driving magnet 30. On the other hand, the stator 29
Is attached to the lower end of the fixed drum 10 and includes a driving coil 31. And the driving coil 3
By supplying a current to the rotor 1, the rotor 28 is driven to rotate. Thus, the rotating shaft 16 attached to the rotor 28 rotates, and accordingly, the rotating drum 11 fixed to the rotating shaft 16 is driven to rotate. The fixed drum 10 has ball bearings 17a, 17b
The rotational force is not transmitted because the rotating shaft 16 is inserted through the shaft.

Next, recording and reproduction by the magnetic head device 3 as described above will be described with reference to FIG. 4 which shows a schematic circuit configuration of the magnetic head device 3 and its peripheral circuits.

When recording a signal on the magnetic tape 1 using the magnetic head device 3, first, a current is supplied to the driving coil 31 of the motor 12, whereby the rotating drum 1
1 is driven to rotate. Then, while the rotating drum 11 is rotating, a recording signal from the external circuit 40 is supplied to the recording amplifier 41 as shown in FIG.

The recording amplifier 41 amplifies the recording signal from the external circuit 40, and transmits the signal from the stator core 26 corresponding to the inductive magnetic head 13a at the timing when the signal is recorded by one of the inductive magnetic heads 13a. Supply the recording signal to the
At the time of recording a signal by the other inductive magnetic head 13b, a recording signal is supplied to the signal transmission ring 26b of the stator core 26 corresponding to the inductive magnetic head 13b.

Here, the pair of inductive magnetic heads 13a and 13b are connected to the rotating drum 11 as described above.
Are arranged so that an angle formed between them is 180 ° with respect to the center of the magnetic heads, and these inductive magnetic heads 13a and 13b perform recording alternately with a phase difference of 180 °. That is, the recording amplifier 41
The timing at which the recording signal is supplied to one inductive magnetic head 13a and the timing at which the recording signal is supplied to the other inductive magnetic head 13b are 18
Switching is performed alternately with a phase difference of 0 °.

The recording signal supplied to the signal transmission ring 26a of the stator core 26 corresponding to the one inductive magnetic head 13a is transmitted to the signal transmission ring 27a of the rotor core 27 in a non-contact manner. The recording signal transmitted to the signal transmission ring 27a of the rotor core 27 is supplied to the inductive magnetic head 13a, and the inductive magnetic head 13a records a signal on the magnetic tape 1.

Similarly, the recording signal supplied to the signal transmission ring 26b of the stator core 26 corresponding to the other inductive magnetic head 13b is transmitted to the signal transmission ring 27b of the rotor core 27 in a non-contact manner. The recording signal transmitted to the signal transmission ring 27b of the rotor core 27 is supplied to the inductive magnetic head 13b, and a signal is recorded on the magnetic tape 1 by the inductive magnetic head 13b.

When reproducing a signal from the magnetic tape 1 using the magnetic head device 3, first, a current is supplied to the drive coil 31 of the motor 6, whereby the rotary drum 11 is driven to rotate. You. And the rotating drum 11
While the is rotating, a high-frequency current is supplied from the oscillator 42 to the power drive 43 as shown in FIG.

The high-frequency current from the oscillator 42 is converted into a predetermined alternating current by the power drive 43 and then supplied to the power transmission ring 26 d of the stator core 26. Then, the alternating current supplied to the power transmission ring 26d of the stator core 26 is transmitted to the power transmission ring 27d of the rotor core 27 in a non-contact manner. Then, the AC current transmitted to the power transmission ring 27d of the rotor core 27 is rectified by the rectifier 44 to become a DC current, which is supplied to the regulator 45, and the DC current is set to a predetermined voltage by the regulator 45.

The current set to a predetermined voltage by the regulator 45 is applied to the pair of MR heads 14a, 1
4b is supplied as a sense current. Note that a pair of MRs
The heads 14a, 14b include the MR heads 14a, 1
A reproduction amplifier 46 for detecting a signal from 4b is connected, and the current from the regulator 45 is also supplied to the reproduction amplifier 46.

Here, each of the MR heads 14a and 14b includes an MR element whose resistance value changes according to the magnitude of an external magnetic field. In the MR heads 14a and 14b, the resistance value of the MR element changes due to the signal magnetic field from the magnetic tape 1, whereby a voltage change appears in the sense current.

Then, the reproducing amplifier 46 detects this voltage change and outputs a signal corresponding to the voltage change as a reproduced signal. The reproduction amplifier 46 outputs a reproduction signal detected by the MR head 14a at the time of reproducing a signal by the one MR head 14a, and outputs the reproduction signal by the other MR head 14b at the time of reproducing the signal. And outputs a reproduction signal detected by the MR head 14b.

Here, a pair of MR heads 14a, 14b
Are arranged so that the angle between them with respect to the center of the rotating drum 11 is 180 °, as described above, these MR heads 14a and 14b alternate with a phase difference of 180 °. Will be played. That is,
The reproduction amplifier 46 is configured to output a reproduction signal from one of the MR heads 14a and output the reproduction signal from the other MR head 14a.
The timing at which the reproduced signal from b is output is 180 °
Alternately with a phase difference of

The reproduction signal from the reproduction amplifier 46 is supplied to a signal transmission ring 27c of the rotor core 27, and the reproduction signal is transmitted to the signal transmission ring 26c of the stator core 26 in a non-contact manner. Stator core 26
The reproduction signal transmitted to the signal transmission ring 26c of FIG.
Supplied to Then, the reproduction signal is subjected to predetermined correction processing by the correction circuit 48, and then output to the external circuit 40.

In the case of the circuit configuration shown in FIG. 4, a pair of inductive magnetic heads 13a, 13a
b, a pair of MR heads 14a, 14b, a rectifier 44, a regulator 45, and a reproducing amplifier 46
1 and rotates together with the rotating drum 11. on the other hand,
Recording amplifier 41, oscillator 42, power drive 4
3. The reproducing amplifier 47 and the correction circuit 48 are disposed in a fixed portion of the magnetic head device 3 or are external circuits configured separately from the magnetic head device 3.

Next, the MR heads 14a and 14b mounted on the rotary drum 11 will be described in detail with reference to FIG. The MR head 14a and the MR head 14b have the same configuration except that the azimuth angles are set to be opposite to each other. Therefore, in the following description, these MR heads 14a and 14b are collectively referred to as the MR head 14.

The MR head 14 is mounted on the rotating drum 11 and is a read-only magnetic head for detecting a signal from the magnetic tape 1 by a helical scan method using a magnetoresistance effect. Generally, MR heads are more suitable for high-density recording because they have higher sensitivity and higher reproduction output than inductive magnetic heads that perform recording and reproduction using electromagnetic induction. Therefore, higher density recording can be achieved by using the MR head 14 as the reproducing magnetic head.

As shown in FIG. 5, the MR head 14 has a pair of magnetic shields 51 and 52 made of a soft magnetic material such as Ni—Zn polycrystalline ferrite and a pair of magnetic shields 51 and 52 through an insulator 53. A substantially rectangular MR element portion 54 sandwiched between the magnetic shields 51 and 52 is provided. In addition, a pair of terminals are led out from both ends of the MR element unit 54, and a sense current can be supplied to the MR element unit 54 through these terminals.

The MR element section 54 includes an MR element having a magnetoresistance effect, a SAL (Soft Adjacent Layer) film,
An insulator film disposed between the R element and the SAL film is laminated. MR element has anisotropic magnetoresistance effect (AMR)
, The resistance value of which varies with the magnitude of the external magnetic field
It is made of a soft magnetic material such as i-Fe. SAL membrane is
This is for applying a bias magnetic field to the MR element by a so-called SAL bias method, and is made of a magnetic material having a low coercive force and a high magnetic permeability such as permalloy. The insulator film is used to insulate the MR element and the SAL film from each other and to prevent electrical shunt loss, and is made of an insulating material such as Ta.

The MR element portion 54 is formed in a substantially rectangular shape, and a pair of magnetic shields 51 and 52 form an insulator 5 so that one side surface is exposed to the magnetic tape sliding surface 55.
3. More specifically, the MR element 54 has a pair of magnetic shields such that the short axis direction is substantially perpendicular to the magnetic tape sliding surface 55 and the long axis direction is substantially perpendicular to the magnetic tape sliding direction. 51 and 52 sandwich the insulator 53 therebetween.

The magnetic tape sliding surface 5 of the MR head 14
5 is cylindrically polished along the sliding direction of the magnetic tape 1 so that one side of the MR element portion 54 is exposed on the sliding surface 55 of the magnetic tape. Cylindrically polished along the direction perpendicular to the direction.
Thus, the MR head 14 is configured such that the MR element portion 54 or a portion in the vicinity thereof protrudes most.
In this way, by making the MR element portion 54 or the vicinity thereof most protrude, the contact characteristics of the MR element portion 54 with respect to the magnetic tape 1 can be improved.

When reproducing a signal from the magnetic tape 1 using the MR head 14 as described above, the magnetic tape 1 is slid on the MR element 54 as shown in FIG. The arrows in FIG. 6 schematically show how the magnetic tape 1 is magnetized.

Then, with the magnetic tape 1 slid in the MR element section 54, the MR element section 5 is connected via the terminals 54a and 54b connected to both ends of the MR element section 54.
4 is supplied with a sense current, and a voltage change of the sense current is detected. Specifically, a predetermined voltage Vc is applied from a terminal 54a connected to one end of the MR element 54, and a terminal 54b connected to the other end of the MR element 54 is
Connected to the rotating drum 11. Here, the rotating drum 1
1 is electrically connected to the fixed drum 10 via the rotating shaft 16, and the fixed drum 10 is grounded. Therefore, one terminal 54 connected to the MR element unit 54
b denotes the rotating drum 11, the rotating shaft 16, and the fixed drum 10
Grounded.

When a sense current is supplied to the MR element section 54 while the magnetic tape 1 is slid, the M formed on the MR element section 54 in response to the magnetic field from the magnetic tape 1.
The resistance value of the R element changes, and as a result, a voltage change occurs in the sense current. Therefore, by detecting the voltage change of the sense current, the signal magnetic field from the magnetic tape 1 is detected, and the signal recorded on the magnetic tape 1 is reproduced.

In the MR head 14 used, M
The MR element formed in the R element section 54 may be any element that exhibits a magnetoresistance effect. For example, a so-called giant magnetoresistance in which a larger magnetoresistance effect is obtained by laminating a plurality of thin films. An effect element (GMR element) can also be used. The method of applying a bias magnetic field to the MR element may not be the SAL bias method, for example, a permanent magnet bias method, a shunt current bias method, a self-bias method, an exchange bias method, a barber pole method, a split element method, Various methods such as a servo bias method can be applied.

The magnetic head device 3 configured as described above
In the above, the ball bearings 17a and 17b arranged in the sleeve of the fixed drum 10 have a sphericity defined by JIS standard B1501 of 0.05 μm or less, and a surface roughness defined by JIS standard B1501 ( The ball 19 having a center line average roughness) of 0.005 μm or less is provided. Therefore, in the magnetic head device 3, it is possible to suppress the occurrence of the so-called rotational aperiodic vibration.

As shown in FIG. 7, the rotation aperiodic run-out
A displacement meter 60 is provided so as to face the rotating drum 10 of the magnetic head device 3, and the displacement of the rotating drum 11 generated when the rotating drum 11 is rotated is measured by the displacement meter 60, and the rotation time, ie, the rotation time, is measured. This is a displacement that occurs independently of the period. FIG. 8 is a characteristic diagram showing the relationship between the displacement of the rotating drum in the magnetic head device 3 measured by the displacement meter 60 and the rotation cycle. In FIG. 8, the vertical axis indicates the amount of displacement of the rotary drum 11, and the horizontal axis indicates the rotation cycle, that is, the rotation time.

As shown in FIG. 8, the rotating drum 1 is generally not rotated by the rotating
It can be seen that a position shift (indicated by M in FIG. 8) has occurred in No. 1. The position shift amount indicated by M in FIG. 8 is defined as “rotational non-periodic shake amount”.

In the magnetic head device 3 described above, the amount of non-periodic rotation can be greatly reduced as compared with the prior art. Specifically, when the conventional magnetic head device is compared with the above-described magnetic head device 3, according to the above-described magnetic head device 3, the amount of non-periodic rotation generated in the conventional magnetic head device is It has become possible to significantly reduce the amount of rotational aperiodic runout. In a conventional magnetic head device, a ball bearing using balls of the third grade specified by JIS B1501 is used.

In the above-described magnetic head device 3, since the rotational aperiodic vibration can be greatly reduced, the magnetic tape 1 can be formed by using the inductive magnetic heads 13a and 13b.
It is possible to form a recording track without fluctuation on the top. Further, in the magnetic head device 3, since the rotational aperiodic vibration can be greatly reduced, the MR heads 14a, 1
The recording tracks formed on the magnetic tape 1 can be reliably reproduced using the 4b.

The balls 19 inside the ball bearings 17a, 17b
Is sphericity defined by JIS standard B1501 is 0.05
μm or less, the surface roughness (center line average roughness) defined by JIS standard B1501 is 0.005 μm or less, and the diameter difference defined by JIS standard B1501 is 0.05 μm or less. Is preferred. In other words, by regulating the sphericity, surface roughness, and diameter irregularity specified in JIS B1501 to be equal to or less than predetermined values, it is possible to more reliably suppress the non-periodic rotation of the magnetic head device 3. it can.

In particular, according to the magnetic head device 3, reliable recording and reproduction can be performed even when high density is to be achieved by narrowing the recording track width and track pitch. Specifically, 6.0 μm is obtained by using a pair of inductive magnetic heads 13a and 13b.
Even when a track pitch of m or less is formed, rotation aperiodic vibration can be suppressed, so that reliable recording and reproduction can be performed. Therefore, by using the magnetic head device 3 described above, it is possible to construct a helical scan magnetic recording / reproducing system that performs recording / reproducing at a track pitch of, for example, 6.0 μm or less.

[0061]

As described in detail above, the magnetic head device according to the present invention has a sphericity and a surface roughness specified by JIS B1501 which are not more than predetermined values. , The occurrence of rotational aperiodic vibration can be suppressed. For this reason, according to the magnetic head device, it is possible to perform reliable recording / reproducing even with a particularly narrow track pitch.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a configuration example of a recording / reproducing device including a magnetic head device according to the present invention.

FIG. 2 is a perspective view schematically showing a magnetic head device.

FIG. 3 is a sectional view showing an internal structure of the magnetic head device.

FIG. 4 is a diagram schematically showing a circuit configuration of the magnetic head device and its peripheral circuits.

FIG. 5 is a perspective view showing an example of an MR reproducing head mounted on the rotary drum, with a part cut away.

FIG. 6 is a diagram schematically showing how a signal from a magnetic tape is reproduced using an MR reproducing head.

FIG. 7 is a schematic configuration diagram showing an outline of a measuring device when measuring a non-periodic rotation of a magnetic head device using a displacement meter.

FIG. 8 is a characteristic diagram showing rotational aperiodic run-out measured by the measuring device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 magnetic tape, 2 recording / reproducing device, 3 magnetic head device, 10 fixed drum, 11 rotating drum, 12 motor, 16 rotating shaft, 17a, 17b ball bearing, 19 balls

Claims (3)

[Claims] 1. A fixed drum having a cylindrical shape, a rotating shaft inserted through the center of the fixed drum, a rotating drum disposed rotatably about a rotating shaft inserted through the fixed drum, and the rotating drum A magnetic head device comprising at least one magnetic head disposed so as to protrude from a peripheral surface of a drum, wherein a ball bearing is disposed between the rotating shaft and the fixed drum; The ball bearing has a sphericity specified by JIS standard B1501 of 0.05 μm or less and a JIS standard B1.
The surface roughness (center line average roughness) specified in 501 is 0.5.
A magnetic head device comprising a ball having a size of 005 μm or less. 2. The magnetic head device according to claim 1, wherein the balls arranged in the ball bearing have a diameter difference defined by JIS standard B1501 of 0.05 μm or less. 3. 6.0 μm for a tape-shaped magnetic recording medium.
2. The magnetic head device according to claim 1, wherein recording and / or reproduction is performed at a track pitch of m or less.