JP2001084508A - Floppy disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the starting torque without degrading the friction characteristics of a magnetic head and a magnetic recording medium. SOLUTION: In this floppy disk device, a plurality of magnetic heads 8 provided with a core composed of a soft magnetic material and a slider composed of a non-magnetic material and provided around the core are abutted to both side faces of the magnetic recording medium 4, information is recorded on the magnetic recording medium 4 by the magnetic heads 8 and the information recorded in the magnetic recording medium 4 is reproduced. In this case, the surface coarseness of the surface of the core to be in contact with the magnetic recording medium 4 is 10 nmRa or less and the surface coarseness of the surface of the slider to be in contact with the magnetic recording medium 4 is in the range of 5-50 nmRa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floppy disk device used as an external storage device for a personal computer or the like.

[0002]

2. Description of the Related Art Conventionally, as this type of floppy disk device, for example, a device described in Japanese Patent Application Laid-Open No. H8-7465 is known.

In the above-mentioned conventional floppy disk drive, when a magnetic recording medium called a floppy disk is inserted into the floppy disk drive, a spindle motor provided in the floppy disk drive rotates the magnetic recording medium and the magnetic head rotates the magnetic recording medium. The medium is sandwiched from both sides, and information is recorded on the magnetic recording medium by the magnetic head, and the recorded information is reproduced.

In recent years, with the miniaturization of magnetic recording media and the increase in recording density, the surface roughness of magnetic recording media has been improved, and the surface roughness of magnetic recording media has been reduced to a mirror surface of about 5 to 15 nm Ra. The slider on the magnetic head side for recording and reproducing information on and from this magnetic recording medium is also finished to about 1 to 5 nmRa in accordance with this.
Spacing loss caused by a gap between the magnetic head and the magnetic recording medium is greatly reduced.

On the other hand, as the wear characteristics of the magnetic recording medium have been improved, so-called pathware on the same track has been improved to such an extent that it does not matter at all, and the miniaturization of the magnetic recording medium has led to the miniaturization of floppy disk drives. On the other hand, a floppy disk device is generally used in a standby mode in which the power is automatically turned off except during actual operation.

[0006]

However, when the surface roughness of a magnetic head or a magnetic recording medium is improved, the magnetic head and the magnetic recording medium come into close contact with each other to increase the coefficient of static friction, and the use environment of the floppy disk device is high temperature and high humidity. When this happens, the magnetic head and the magnetic recording medium are attracted to each other, and as a result, the load torque of the spindle motor increases, so that the magnetic recording medium cannot be rotated, or it takes longer than necessary at startup, and the startup characteristics are deteriorated. Has occurred.

Further, as the load torque increases due to the attraction between the magnetic head and the magnetic recording medium, and the difference between the dynamic friction coefficient and the static friction coefficient increases, the magnetic head and the arm on which the magnetic head is mounted are caused by stick-slip or the like. Unnecessary vibrations cause information write errors and read errors, and when the load torque of the spindle motor increases, a large start-up torque is required at start-up, resulting in increased power consumption and expensive magnets. There are also problems such as the need for the used spindle motor.

The present invention has been made in order to improve such a conventional problem, and has reduced power consumption at the time of starting by reducing the starting torque without deteriorating the frictional characteristics of the magnetic recording medium. It is an object of the present invention to provide a floppy disk drive at low cost.

[0009]

In order to achieve the above object, the present invention provides a magnetic head having a core made of a soft magnetic material and a slider provided around the core and made of a nonmagnetic material. A floppy disk device that is in contact with both side surfaces of the magnetic recording medium, records information on the magnetic recording medium by the magnetic head, and reproduces information recorded on the magnetic recording medium. The surface roughness of the surface in contact with the magnetic recording medium is 10 nm Ra or less, and the surface roughness of the surface in contact with the magnetic recording medium of the slider is in the range of 5 to 50 nm Ra.

According to the above configuration, the starting torque at the time of starting the magnetic recording medium can be reduced, so that the power consumption at the time of starting can be reduced.

Further, even when the operating environment is high temperature and high humidity, the magnetic head does not stick to the magnetic recording medium, so that the magnetic recording medium cannot be rotated by the spindle motor, or much time is required for starting. In this way, it is possible to solve problems such as deterioration of the startup characteristics in the standby mode.

According to another aspect of the present invention, there is provided a magnetic recording medium comprising: a magnetic head; It is smoother than the surface roughness.

According to the above configuration, even if the recording wavelength of the recording head provided on the inner peripheral side of the magnetic recording medium is set to be short, the resolution is not easily reduced and the influence of the spacing loss is small.

[0014]

Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an overall plan view of a floppy disk drive, FIG. 2 is a sectional view of the vicinity of a head carriage, FIG. 3 is an enlarged perspective view of a magnetic head, and FIG. 4 is an enlarged view in an A circle of FIG. 5 is a sectional view taken along the line BB of FIG. 4, and FIG. 6 is a diagram showing the relationship between the slider surface roughness, the starting torque, and the number of wear generation passes.

In FIG. 1, reference numeral 1 denotes a base plate constituting a base of a floppy disk drive, which is formed by aluminum die casting, sheet metal pressing, or the like.

Reference numeral 2 denotes a holder, which cooperates with an eject lever 3 to take in and out the magnetic recording medium 4 shown in FIG.

Reference numeral 5 denotes a stepping motor.
A lead screw 7 for driving the head carriage 6 is connected to the head carriage 6.
Is moved in the track direction of the magnetic recording medium 4 so that the magnetic head 8 provided on the head carriage 6 can be positioned at a predetermined track of the magnetic recording medium 4.

As shown in FIG. 2, the head carriage 6 has an arm whose base end is pivotally connected to the head carriage 6 by a pin 10 and whose distal end is urged toward the head carriage 6 by urging means 11 such as a spring. A magnetic recording medium 4 is sandwiched between both ends of the arm 12 and the head carriage 6 to record information on the magnetic recording medium 4 or to transfer the recorded information. A pair of magnetic heads 8 for reproduction are mounted so as to face each other.

In FIG. 2, reference numeral 14 denotes a spindle motor for driving the magnetic recording medium 4 to rotate.
A chuck 15 for chucking a central portion of the device is mounted.

The magnetic head 8 is, as shown in FIG.
The substrate 8a of the magnetic head 8 attached to the arm 12 side is a gimbal spring.

A slider 16 that contacts the magnetic recording medium 4 is provided on the substrate 8a.

The slider 16 is made of a non-magnetic material such as potassium titanate-based ceramic, and has a groove 16b formed on a contact surface 16a with the magnetic recording medium 4 and a groove formed in the slider 16. A core 17 made of a soft magnetic material is provided in parallel with 16b.

The core 17 is made of, for example, Mn-Zn ferrite whose hardness and coefficient of thermal expansion are close to those of the slider 16, and as shown in FIG.
R / W for recording information on the magnetic recording medium 4 and reproducing the recorded information in a direction orthogonal to the rotation direction a of
A gap 17a and an erase gap 17b for erasing (trim erasing) both sides of the recording track are formed.
When a Ni—Zn ferrite is used for the core, a barium titanate ceramic slider is suitable.

FIG. 5 is a sectional view of the core 17 forming the R / W gap 17a and the erase gap 17b.
An R / W gap 17a is formed between c and a C-shaped core 17d provided so as to face the I-shaped core 17c.

An I-shaped core 17g provided back to back with an I-shaped core 17c and a separator 17f interposed therebetween, and a C-shaped core 1 provided to face the I-shaped core 17g.
The erase gap 17b is formed during 7h.

R / W gap 17a and erase gap 1
Each of the C-shaped cores 17d and 17h forming
Coils 19 and 20 for magnetizing the shaped cores 17d and 17h are provided, and a back bar 17i constituting a magnetic circuit is provided on the opposite side of the R / W gap 17a and the erase gap 17b.

The separator 17f separates the magnetic circuit of the R / W gap 17a from the magnetic circuit of the erase gap 17b, but need not be provided.

In FIG. 3, reference numeral 21 denotes a flexible cable for connecting the magnetic head 8 to a circuit (not shown) in the floppy disk drive.

On the other hand, the surface roughness of the surface of the magnetic head 8 which contacts the core 17 and the slider 16 with the magnetic recording medium 4 is set as follows.

The magnetic recording medium 4 is mounted on the floppy disk drive.
Is inserted to record information on the magnetic recording medium 4 or reproduce the recorded information, the magnetic recording medium 4 is held at a position of a radius Rn by the magnetic head 8 as shown in FIG. It is rotated by the spindle motor 14, and the pinching load at this time is normally pressed by the urging means 11 to about 10 to 25 gf.

Assuming that the sandwiching load is F and the friction coefficient (maximum friction coefficient or static friction coefficient) of the contact surface between the magnetic head 8 and the magnetic recording medium 4 is μs, the starting required for starting the magnetic recording medium 4 is performed. The torque Ts is obtained by Ts = 2 × μs × F × Rn.

When the magnetic recording medium 4 is started, the largest starting torque is required when the magnetic head 8 is in contact with the outermost periphery (usually called a track φ) of the magnetic recording medium 4, and 3.5. In the case of the inch-type magnetic recording medium 4, the starting torque is about 100 to 120 gf-cm. Therefore, the spindle motor 14 that drives the magnetic recording medium 4 is designed to obtain a starting torque that can overcome this starting torque. .

The spindle motor 14 is usually a brushless DD (direct drive) motor.
The torque generated by this motor is substantially proportional to the input current. However, when the use environment of the floppy disk device is high temperature and high humidity, the magnetic head 8 is attracted to the magnetic recording medium 4 and the starting torque is 250 gf- cm, it is necessary to consider this point.

On the other hand, the load F at which the magnetic head 8 clamps the magnetic recording medium 4 depends on the vibration resistance of the floppy disk drive and
Although it is set to be optimal including the compliance between the magnetic head 8 and the magnetic recording medium 4, in order to reduce the starting torque for starting the magnetic recording medium 4, the magnetic head 8 and the magnetic recording medium 4 must Needs to be reduced.

FIG. 6 shows the surface roughness nmRa of the surface of the slider 16 of the magnetic head 8 and the track φ with which the magnetic head 8 contacts.
Shows the relationship of the starting torque in the slider 16
It can be seen that the surface roughness shows a substantially constant low value in the range of approximately 5 nmRa to approximately 50 nmRa.

FIG. 5 also shows the relationship between the surface roughness of the slider 16 and the number of passes in which wear occurs.
From per nmRa it can be seen that the generation of wear occurs with a smaller number of passes.

Although this varies slightly depending on the magnetic recording medium 4, if the life is sufficient at about 10 million passes, the surface roughness of the surface of the slider 16 is optimally 5 to 50 nmRa.

Further, the material of the slider 16 includes a core 17
By using a material whose coefficient of thermal expansion is similar to that of the above, a step is not generated between the core 17 and the slider 16 due to a temperature cycle or the like, and at the same time, the influence of heat generation during surface processing can be reduced. improves.

Therefore, in the embodiment of the present invention, in order to make the surface roughness of the slider 16 in the range of 5 to 50 nmRa, the slider 16 is used for the abrasive grain size and the type of abrasive grains for polishing the surface of the slider 16 and for lapping. Lap machine hardness, peripheral speed,
The surface of the slider 16 was polished while changing the pressing force and the like and simultaneously measuring the surface roughness, and optimization was performed so that a surface roughness of 5 to 50 nm Ra was obtained.

As a result, a desired surface roughness can be obtained by using a chromic acid or diamond abrasive having an abrasive particle diameter of approximately 5 to 10 μm Ra.

The abrasive grain size of about 5 to 10 μm Ra may be appropriately selected in relation to a desired surface roughness. In the embodiment, a diamond powder having a grain size of 2 to 5 μm Ra and a 4 to 8 μm Ra weights 1: 3. Slider 16 having a surface roughness of about 4 to 5 nm Ra
Was obtained stably.

When the surface of the slider 16 is wrapped by using a lapping liquid, good characteristics can be obtained without generating heat during processing, generating a damaged layer or the like, and having no influence of thermal stress on the core 17. Slider 16 was obtained.

The method of processing the surface of the slider 16 is not limited to these, and a physical processing method such as sputtering or a chemical processing method using chemicals may be used.

The surface roughness of the slider 16 of the magnetic head 8 has been described above.
It is set as follows.

Now, a spacing loss Ls due to a gap generated between the magnetic head 8 in contact with the magnetic recording medium 4 and the magnetic recording medium 4 is given by a recording wavelength λ and a gap d. And the surface roughness of the core 17 is 3 nmRa and 10 nmR
In the case of “a”, the recording wavelength λ ≒ 3 μm is about 1.5%, so that the effect of the spacing loss is small.

Therefore, the surface roughness of the core 17 is reduced
10 nm Ra or less, which is smoother than the surface roughness of the surface.

The core 17 of the magnetic head 8 attached to the normal arm 12 is equivalent to the core 17 of the magnetic head 8 on the head carriage 6 by eight tracks (3.5 in the radial direction of the magnetic recording medium 4). For an inch-type magnetic recording medium, 0.
1875 × 8 = 0.75 mm).

Since the floppy disk drive is used in CAV (constant angular rotation), the magnetic head 8 located on the inner peripheral side is set in advance so that the recording wavelength λ is shorter. For this reason, in order to reduce the resolution ability of the magnetic head 8 located on the inner peripheral side and to reduce the influence of the spacing loss, the core 17 of the magnetic head 8 on the inner peripheral side is reduced.
The surface roughness is made smoother than the surface roughness of the core 17 of the magnetic head 8 on the outer peripheral side to prevent the characteristics from deteriorating.

As described above, the slider 16 of the magnetic head 8
By setting the surface roughness of the core 17 and the surface roughness of the core 17, the contact friction with the magnetic recording medium 4 can be greatly reduced, so that the magnet used in the conventional spindle motor is changed from a neodymium iron-based magnet to a ferrite-based magnet. As a result, the spindle motor 14 can be reduced in price, and even when the floppy disk device is used in a high-temperature, high-humidity environment, the magnetic recording medium 4 and the magnetic head 8 are almost completely attracted. lost.

[0051]

As described in detail above, the present invention is directed to a magnetic recording medium for recording information on the magnetic recording medium and reproducing the information recorded on the magnetic recording medium by abutting on both side surfaces of the magnetic recording medium. The surface roughness of the surface where the core of the head contacts the magnetic recording medium is 10 nm Ra or less, and the surface roughness of the surface where the slider contacts the magnetic recording medium is 5 to 50 n.
By setting the range of mRa, the starting torque at the time of starting the magnetic recording medium can be reduced, so that the power consumption at the time of starting can be reduced.
Even when the use environment is high temperature and high humidity, the magnetic head does not stick to the magnetic recording medium, so that the magnetic recording medium cannot be rotated by the spindle motor or it takes much time to start. Therefore, it is possible to solve the problem that the rising characteristic in the standby mode is deteriorated.

Since the difference between the coefficient of kinetic friction and the coefficient of static friction is small, unnecessary vibration does not occur in the magnetic head or the arm on which the magnetic head is mounted at the time of startup. No errors, which increases reliability,
Since an inexpensive motor using a ferrite magnet can be used for the spindle motor, the cost of the floppy disk device can be reduced.

Further, the surface roughness of the core of the magnetic head disposed on the inner peripheral side of the magnetic recording medium is made smoother than the surface roughness of the core of the magnetic head disposed on the outer peripheral side. Even if the recording wavelength of the recording head provided on the inner peripheral side of the magnetic recording medium is set to be short, the resolution is reduced and the influence of spacing loss is small, so that a highly reliable floppy disk A device is obtained.

[Brief description of the drawings]

FIG. 1 is an overall plan view of a floppy disk drive according to an embodiment of the present invention.

FIG. 2 is a sectional view of the vicinity of a head carriage of the floppy disk drive according to the embodiment of the present invention;

FIG. 3 is an enlarged perspective view of a magnetic head of the floppy disk drive according to the embodiment of the present invention;

FIG. 4 is an enlarged view of the inside of an A circle in FIG. 3;

FIG. 5 is a sectional view taken along the line BB of FIG. 4;

FIG. 6 is a diagram showing the relationship between the surface roughness of a slider constituting a magnetic head, the starting torque, and the number of wear generation passes.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base plate 2 Holder 3 Eject lever 4 Magnetic recording medium 5 Step motor 5a Rotating shaft 6 Head carriage 7 Lead screw 8 Magnetic head 8a Substrate 10 Pin 11 Energizing means 12 Arm 14 Spindle motor 14a Rotating shaft 15 Chuck 16 Slider 16a Contact surface 16b Groove 17 Core 17a R / W gap 17b Erasure gap 17c I-type core 17d C-type core 17f Separator 17g I-type core 17h C-type core 17i Back bar 19,20 Coil 21 Flexible cable

Claims (2)

[Claims] 1. A magnetic head comprising: a plurality of magnetic heads each having a core made of a soft magnetic material and a slider provided around the core and made of a non-magnetic material, the magnetic head being in contact with both side surfaces of a magnetic recording medium; A floppy disk drive for recording information on a magnetic recording medium by a head and reproducing the information recorded on the magnetic recording medium, wherein a surface roughness of a surface where the core contacts the magnetic recording medium is set to 10 nm Ra or less. ,
Further, a surface roughness of a surface of the slider in contact with the magnetic recording medium is in a range of 5 to 50 nmRa. 2. The floppy disk according to claim 1, wherein the surface roughness of the core of the magnetic head disposed on the inner peripheral side of the magnetic recording medium is smoother than the surface roughness of the core of the magnetic head disposed on the outer peripheral side. Disk device.