JPH04167267A - Disk device - Google Patents

Abstract

PURPOSE:To provide a high density, large-capacity and high-speed disk device by ensuring a contact state of head means with a flexible disk by a gimbal of a head by a liner, and specifying the contact position with servo information. CONSTITUTION:A flexible disk 1 held by a liner 3 is held by a double head system 9 of a gimbal/suspension structure symmetrical at both side surfaces, and a head is positioned by using servo information formed on the disk 1. Accordingly, even if the disk 1 is rotated at a high speed, the vicinity of a head gap is not floated, and it is always brought into contact with the disk 1, and hence even if the line density is enhanced, no spacing loss occurs. On the other hand, since the disk 1 is always brought into contact with the liner 3, even if the disk 1 is rotated at a high speed, the media is not damaged due to a dust removing effect at the liner 3, suspension loading, etc. Thus, it is possible to provide a high-density, large-capacity and high-speed disk device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a disk device in which disks can be replaced.

(Prior Art) As computer systems become smaller and more sophisticated, removable magnetic disk drives are increasingly required to have larger capacities, faster speeds, smaller sizes, lighter weights, and lower costs. A floppy disk device is a removable magnetic disk device! (FDD), removable hard disk device (removable HDD), and Bernoulli flexible disk device, but FDD is widely used because it is cheap and easy to use.

However, since the FDD has a small capacity and a slow rotational speed, the transfer speed is slow, and furthermore, since a stepping motor is used, the access speed is also slow. The main reason for the small capacity is that conventional FDDs are non-tracking servos, and cannot follow the expansion and contraction of temperature and humidity of flexible media, making it impossible to increase track density. However, recently, track densities have been increased by using tracking servos. Despite this, the reason why the track density is lower than that of HDDs is due to differences in magnetic head systems, which will be described later. The rotational speed of an FDD is usually 300 to 360 rpm, which is an order of magnitude slower than that of an HDD. This is because the head and the medium are used in contact with each other, so if the head is rotated at high speed, as in an HDD where the head is floated above the medium, the life of the medium will not last.

Initially, there were two types of double-sided FDD head systems. One is Herad suspension for HDD, I
This is an improved version of B M3330 type for FDD use.
It is described in detail in US Pat. No. 4,263,630.

FIG. 20 shows its structure. 200 is the head assembly, 201 is the gimbal plate, 202 is the Herad tip, 203 is the slider, 204 is the R/W gap 205
206 is a suspension, and 207 is a load spring. R/W gap 20
5 will be explained later in the case of HDD.

Since the head is used with the head floating, it is provided on the disk outflow side of the slider 203, but in the case of an FDD, the head is used by pressing down on the disk and making contact with it, so it is provided almost at the center of the slider 203.

This head system has the advantage of improving the durability of the medium because head touch can be achieved with a relatively small suspension load. However, the structure is complicated, large, and expensive. Furthermore, since the head chip 202 is supported by a stiff suspension 206, the posture during head load-off is unstable and adjustment is difficult. Also, depending on the drive posture, side 0
There were problems such as different offsets occurring between the side and the side 1 side. For this reason, this type of double-sided head system is not currently used.

The other one was proposed by Tanton.

One of the double-sided heads is fixed and the other has a gimbal structure. This content is described in detail in US P4151573. FIG. 21 is a schematic diagram of a recent double-sided head system for FDD using this. 211
a is a hard head plate 2 with a helad tip on side 1
12 to the carriage 210. On the other hand, the Herad chip 211b on the side 1 side is attached to a gimbal plate 213, and this gimbal plate is attached to the Herad arm 214. 2
A pivot 17 is formed integrally with the head arm and is in contact with the head chip 211b. 215 is a vertically movable suspension, 216 is a herad tip 211
This is a load spring that applies a load to b. Figure 22 is 211
FIG.

220 is a herad core with R/W gap 2 near the center.
21 and an erase gap 222 are formed. A head slider 223 is separated into two by a separation groove 224. Figure 23 shows floppy disk 1 at 211
8. The structure is such that the head 211a on the side 1 side is fixed, and the floppy disk 1 is held down by the head 211b.

Therefore, even if the floppy disk 1 is bent, the disk is pressed against the fixed head 211a, so no track offset occurs, and this double-sided head system does not cause track offset depending on how the device is placed. Thus, the problem of the double-sided head system shown in FIG. 20 was solved. Most of the FDD double-sided head systems currently in use use this structure. This head system has disk 1
The slider surface 225 with a gimbal structure on the side 1 side is strongly pressed against the fixed side O side slider surface 223 (usually with a head pressure of 20 g to 30 g), and the slider on both sides comes into contact with the medium, so that the head on both sides It is now possible to take a touch. Therefore, large friction occurs between the head and the medium, and a large torque is required from the spindle motor that rotates the disk. For this reason,
This is an unfavorable head system from the viewpoint of media durability.

Usually, FDD has a disk rotation speed of 300 to 360 rpm.
It is used in m. For faster transfer speed.

As the rotation of the disk increases, the head floats above the medium, making it impossible to touch the head. In particular, as shown in FIG. 22, in an FDD head, the bed gap is located near the center of the slider, so the head output that causes the head to fly even a little starts to decrease. This becomes more noticeable as the linear recording density increases. Therefore, if an attempt is made to obtain a head touch by applying a large load to the head, a problem arises in the durability of the medium. Furthermore, in order to rotate the disk at high speed under such conditions, a spindle motor with a very large torque is required, which causes problems such as space, cost, and power consumption. Further, the head system of an FDD is larger and has a larger mass than the head system of an HDD. For this reason, since the movable part of the head positioner is large and has a large mass, there is also the problem that it is difficult to increase the seek speed.

As mentioned above, the top magnetic head system of an FDD obtains head touch by pressing the medium with the head slider, and the head gap is located approximately at the center of the slider. In manufacturing such a bulk type magnetic head, it is difficult to accurately control the track width and gap length.

Therefore, even if the positioning error can be reduced by tracking servo, it is difficult to increase the track density due to the difference in track width between devices, and there is also the problem that large OWM noise is generated due to the difference in gap length.

On the other hand, although removable HDDs have the advantage of large capacity and high speed compared to FDDs, they have disadvantages such as expensive disk cartridges and the constant risk of head crashes due to dust, adsorption, impact, etc. be.

In addition, since the head is used by floating above the disk,
There is also the problem that spacing loss occurs and linear recording density cannot be increased.

The biggest problem with HDDs, not just removable HDDs, is head crash, which is an essential drawback of HDDs due to the hardness of the disk.

In particular, removable HDDs, compared to fixed HDDs,
Since much more dust is taken into the HDA (head disk assembly), the risk of head crash is correspondingly high.

FIG. 24 shows a head chip for an HDD that has been used recently, and the position of the head gap is different from that of an FDD head, and is provided at the outflow end of the disk. Additionally, the shape of the slider is also significantly different. (,) is a monolithic Herad chip 240a, and the head gap 241a is 3
It is installed in the center ABS of the book's ABS. (
b) is a composite head chip 240b in which a head core 245 is provided on one side 243b of the ABS, and a bed gap 241b is provided at the end on the disk outflow side. (C) is a thin film rad chip 240c, and the head is formed at the disk outflow end of the ABS, but only one of them is actually wired. The thin film head that can be manufactured using the thin film process is the smallest in size of the head chip. This is because by making the head chip smaller, a large number of Herad chips can be obtained from one wafer, and by making the head chip smaller, the head load can be reduced, which is advantageous for contact start-stop. Furthermore, since the head is light, it is less susceptible to external forces, so it is made smaller. Other items are determined based on ease of processing. FIG. 25 shows a recently used IBM3370 type head assembly 250. 251 is a Herad suspension and is used by bending a thin stainless steel plate. Reference numeral 252 is a load spring, and the spring force is comprehensively determined based on the size of the ABS, the number of revolutions of the disk, etc. in order to obtain the necessary flying height of the head. This spring force was about 15 g in the original monolithic head, but a very light 6.5 g is used in recent micro sliders of thin film heads. (b) The figure shows a Herad gimbal 255, in which a portion 258 is attached to the Herad chip 240, while a portion 256 is attached to the Herad suspension 251. 259 is a pivot that comes into contact with the tip of the suspension 251. Normally, the length of the suspension is 1 inch, but for thin film heads and the like, shorter lengths are used. Also, for the ABS surface and head mounting, the height to the board is usually 0.1 inch.

Smaller HDDs use even lower values. This type of head assembly is characterized by a simpler structure, smaller size, and higher suspension rigidity than the head assembly shown in FIG. 20.

FIG. 26 is a diagram showing the relationship between the hard disk 260 and the floating head chip 240. Hard disks usually have a magnetic layer and a lubricant layer formed on an aluminum substrate. A magnetic head is usually placed in contact with the surface of the disk. When the disk is rotated at high speed, it transitions from a contact state to a floating state. As can be seen from the figure, the flying height is large on the inflow side of the disk, and small on the outflow side of the disk, that is, the side where the head gap 241 is formed. Flying Hide Fh has an ABS shape,
In particular, it is mainly determined by the width of ABS and the number of revolutions per rotation of the head load.

For high-density recording, it is better to have the flying height as small as possible; however, if the flying height is reduced, it will come into contact with the disk surface, and if the surface area is increased, adhesion will occur at CC8, which does not provide media durability. Currently, in HDD, Fh is 0.1
5 to 0.2 voices are used. In this way, in a hard disk, the head flies with a very small flying height, so if even submicron-order dust gets between the disk and the ABS, it can cause a head crash.

The IB M3370 type head assembly shown in FIG. 25 sufficiently follows the surface runout of the hard disk.
However, it shows high rigidity, so in HDD,
With tracking servo, it is possible to easily obtain high track densities. However, with removable HDDs, head crashes due to dust are a more serious problem than with normal fixed HDDs. In the case of a removable HDD, it has a sealed structure to prevent dust from entering the cartridge, but since a shutter is opened and closed for head loading, it is difficult to prevent dust on the order of submicrons from entering.

In addition, since the drive is loaded with a cartridge with dust on it, the head disk assembly (HDA)
It is impossible to keep the inside as clean as a fixed HDD. Therefore, removable HDD is different from fixed HDD.
It is less reliable, and the flying height cannot be lowered due to dust problems.

There are many problems, including the inability to increase recording density.

The Bernoulli flexible disk device is a device that can rotate and replace disks at high speed. The basic structure is described in USP 4,419,704.

In this disk device, a flexible disk is rotated at high speed (15
00 to 2000 rpm), a micro air layer is formed by the airflow on the disk surface between the disk and the stabilizer plate, thereby preventing surface wobbling of the flexible disk. For high speed rotation, the head is installed on one side, opposite the stabilizer. The structure of the head is shown in FIG. 27. A head assembly 270 is circular and has a ring stabilizer 271 on the outer circumferential side that attracts the disk. There is a spherical Herad air bearing surface 272 inside thereof, and a slot 274 and a R/W gap 273 are provided in the center thereof. In an actual device, the head is installed so that it slightly protrudes from the disk. When the disk is rotated at high speed in this state, the ring stabilizer pulls the flexible disk toward the head, causing it to align with the head air bearing surface. Additionally, the slots provided on the head air bearing surface create negative pressure.
At a position where there is a R/W gap, a stable floating clearance of 0.1 to 0.2p can be obtained. This head system is basically single-sided, but recently, a pseudo-double-sided system has been achieved by using a cartridge that houses two flexible disks with a stabilizing plate in between.

In this way, the Bernoulli method disk device.

Since there is no contact between the head and the medium, the speed can be easily increased, but on the other hand, a flying gap is created between the head and the medium, so it has the disadvantage that the recording density cannot be increased in the same way as an HDD. Since a flexible disk is used, the HDD
Although it is resistant to head crashes like HDDs, if dust gets in, the medium can be easily damaged just like HDDs, so filtration like removable HDDs is required and it has the disadvantage of being expensive.

In addition, the head structure is more complicated than conventional FDD heads or HDD heads, making it more expensive.Furthermore, since there is a R/W gap in the center of the spherical slider, thin-film heads like HDD heads cannot be used. . This Bernoulli system is basically a single-sided head type, so if you create a pseudo-double-sided system, it will be necessary to store two discs in one cartridge, which has the disadvantage of making the disc cartridge expensive. .

(Problems to be Solved by the Invention) As described above, conventional removable magnetic disk devices, that is, floppy disks, have the disadvantages of small capacity and slow speed, while removable HDDs have the disadvantages of being expensive. In addition, Bernoulli-type devices have disadvantages such as poor disk cartridges, head crashes due to dust, and the inability to increase recording density.
In addition to the similar disadvantages of HDDs except for the problem of head crash, they also require a complicated and expensive head, and furthermore require two disks if double-sided printing is desired.

The present invention was made in view of the above problems, and
High density and large capacity comparable to HDD, at the same convenience and price.
The aim is to provide a high-speed disk device.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a disk device with replaceable disks, which includes at least a flexible disk sandwiched between liners, and a double-sided head system with a gimbal/suspension structure that is symmetrical on both sides of the flexible disk. This disk device has a tracking servo system that positions the head using servo information formed on the sandwiched disk.

(Function) The removable magnetic disk device of the present invention uses a double-sided head system with a flexible disk sandwiched between liners and a symmetrical gimbal/suspension structure as the basic structure of the head/medium type. Since it has a symmetrical gimbal/suspension, the double-sided head system follows the surface runout of the disk by moving the suspension in the Z direction and rotating the gimbal in two axes. As the rotational speed of the disk increases, the disk is stretched by centrifugal force, increasing its rigidity but decreasing its surface runout.

However, since the suspension load is sufficiently greater than the rigidity of the disc, the disc is approximately flattened near the ABS. Therefore, even if the disk rotates at high speed, the area near the head gap does not float and is always in contact with the disk, so even if the linear density is increased, no spacing loss occurs.As the suspension moves in two directions, the side Track offsets occur in opposite directions on the O side and side 1 side, but this is not a problem because the tracking servo system used to achieve high track density corrects the track position on each track according to servo information. do not have.

On the other hand, since the flexible disc is always in contact with the liner, any dirt that adheres to the disc is wiped away by the liner. Originally, flexible discs are resistant to dust because the disc is flexible, but the dust removal effect of the liner and the low suspension load, and the fact that the disc is in contact with the disc at a part of the outflow side of the disc instead of all of the ABS. Because of this, the media will not be damaged even if the disk is rotated at high speed.In addition, by sandwiching the disk between liners, large surface runout of the disk can be suppressed, so there is no need to use measures such as stabilizers. .

Therefore, according to the present invention, it is possible to achieve a removable magnetic disk device that is as fast and large-capacity as a hard disk, as simple and inexpensive as an FDD.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a diagram schematically showing a removable magnetic disk device according to an embodiment of the present invention.

1 is a flexible disk having a chucking hub 4, which is sandwiched between liners 3 and housed in a cartridge case 2. 5 is a spindle motor, 6 is a spindle shaft, and 7 is a hub pedestal, a part of which is embedded with a magnet. 9a is a magnetic head assembly on side 019b side 1; 10a and 10b are helad chips on side 0 and side 1, respectively; 11 is a magnetic head assembly 9
A protrusion for head unloading provided in b, 1
2 is a part of the helad unloading mechanism, 13 is a helad arm for attaching a magnetic helad assembly, 14 is a protrusion provided on the helad arm 13, and 1
5 is a head positioner, 16 is a carriage, and 17 is a read/write amplifier mounted on the carriage.

When a cartridge is not inserted into the device, the magnetic head assembly 9b on side 1 is moved by a portion 11 of the head unloading mechanism provided on the magnetic head assembly 9b by a portion 12 of a head unloading mechanism connected to a loading mechanism (not shown). is pulled upward through the protrusion. On the other hand, the side 0 magnetic head assembly 9a is
As will be described later, a part of it hits the protrusion 14 provided on the helad arm 13, so that the air bearing slider (ABS) surface provided on the head chip 10a is slightly closer to side 1 than the disk surface. It is set. The carriage 16 is pressed outward by the loading mechanism so that the magnetic head assembly 9 is located on the outermost side of the disk. When the six-cart cartridge 2 is loaded into the device, the cartridge 2 is moved downward from above the spindle shaft 6. be dropped to. At this time, a cartridge shutter (not shown) opens, and a window for loading the magnetic head opens. At the same time, the magnetic head assembly 9b is gently lowered onto the disk by the rad unload mechanism 12. When the spindle motor is rotated, the chucking hub is attracted to the magnet of the hub pedestal 7, and chucking of the disk is completed. disc 1
As will be described later, servo information for tracking is embedded in the servo information.

The signal read by the magnetic head is amplified by a read/write amplifier 17 and a 1-position signal reproducing circuit 18.

The 0 position signal sent to the data reproducing circuit 19 is A at 20.
/D converted and then taken into the MPU 21.

After the necessary calculations are done here, the control signal is 22 D/A
The signal is sent to the positioner 15 via the converter and current amplifier 23, and as a result, the magnetic head can be made to follow the target track. With tracking applied, the reproduced data is sent to the host system via the controller 25. On the other hand, the target track address and data to be written are sent from the host system to the controller, and after seeking by the MPU 21, predetermined data is sent to the read/write amplifier 17 via the data recording circuit 24, and the data is written to disk.

As mentioned in the conventional example, the rotational speed of the FDD is approximately 300 r.
If the rotation speed is forcibly increased, problems will arise in the durability of the medium. On the other hand, removable HDDs have a high rotational speed of 3,600 rpm, but have low reliability due to dust problems, and cannot increase the recording density because the flying hide cannot be lowered. We decided to construct a removable disk device using a flexible disk and an IBM 3370 type magnetic head as its basic structure.

Hereinafter, the present invention will be explained in detail without showing experimental results. The experiment used a 3.5-inch Ba ferrite floppy disk (base thickness 75 mm) and a thin-film magnetic head shown in Figure 24 (C) (adopting a micro slider with a head weight of 6.5 g) at a recording density of 42 kPCI. I went there. The discs come in regular disc cartridges. The disc is sandwiched between liners, and the lifter is pressed down to further enhance the dust removal effect. Side 1 is the head on the upper side of the disk, the gap position is at a radius of 23.5 mm, and side 0 is the head on the lower side of the disk.

The position of the gap is located 1.5 mm from side 1 to the outer periphery. In Figure 2, (a) is A B S llgo, 3
m+, (b) is an experimental result showing the relationship between the number of revolutions and the output of the rolling head when the ABS width is 0.4 mm. ABS width is 0
．． At 3-, the output increases linearly up to 2000 rpm.The rotation speed at which the output decreases by 1 dB is approximately 2600 rpm.In contrast, the ABS width is 0.4
When the power is on, the output increases linearly to about 170 rpm. It takes about 200O to reduce the output by 1dB.
It is rpm+. In this way, if the head weight is kept constant.

It can be seen that the narrower the ABS width, the more difficult it is to float.

In addition, the characteristics of side O and side 1 are different because side 1 works to receive gravity, side 1 works to apply gravity, and side O works to reduce gravity, so side 1 is harder to float. it is conceivable that. FIG. 3 shows the experimental results of a normal slider type composite head shown in FIG. 24(b) with a head load of 9.5 g. ABS width is 0.
381, and the recording density is 35 kPCI. The output increases linearly up to 2300 rpm, and the output increases by 1
The dB drop is approximately 300° rpm. Weight is the second
Since it is larger than the one in the figure, the change in characteristics between side 0 and side 1 is small. Therefore, it can be seen that the larger the head load is to some extent, the smaller the change in the flying characteristics due to the way the device is placed. On the other hand, the recording and playback characteristics are
It works well while the head is extending linearly, but as the output decreases, modulation occurs. this is,
When the head begins to float, the recording ability of the head decreases,
This is thought to be due to the fact that uniform magnetization is no longer possible, and the medium is not sufficiently held down by the ABS, resulting in differences in spacing.

The spacing loss due to levitation is approximately -54,6d/λ
The recording density is said to be 42kPC (dB).
In the case of I (λ=1.21m), the spacing loss is 1
The head flying height that becomes dB is approximately 0.02μs, 35k
For PCI it is 0.024. On the other hand, the average surface roughness Ra of the flexible disk is 0.00871111
11, there are many abnormal protrusions exceeding 0.02. Therefore, this flying height can be said to be a state in which the head is almost always in contact with the disk. In fact, when the contact status of the above head with the disk is measured using an AE sensor, a flying state cannot be obtained between 750 rpm and 4000 rpw+, and a signal indicating contact is always obtained. For this reason, this head system
Unlike when the head is used with the head completely floating above the disk, it is used with a part of the ABS always in contact with the disk.

Figure 4 shows the thin film head at a rotational speed of 150Or.
These are the experimental results when the head was fixed at pm and the head mounting position was changed. (a) has an ABS of 0.3, (b)
) is when the ABS is 0.4m+. In either case, the range in which the output decreases by 1 dB is ±0.5 degrees. Fifth
The figure similarly shows the experimental results for the MIG head. With this head, at 1500 rpm, ±
For installations of 0.5m or more, a margin can be obtained.If the rotation speed is increased to 300 rpm, the margin for installations will be ±
It drops to 0.4 kaku. On the other hand, in the case of FDDs and HDDs, the margin for head installation is said to be ±0.2 degrees.

On the other hand, experimental results show that there is a margin for mounting twice that amount or more. From the above experimental results, I
It has been found that a head/medium system using a flexible disk with a BM3370 type magnetic head and a liner is very compatible from the point of view of head touch. The data shown above has not been presented at an academic conference, and this is the first time it has been disclosed.

From the above experimental data, it has been found that by using a portion of the ABS in contact with the disk, a margin for good head touch and attachment can be obtained. At this time, the problem is the durability of the medium when used at high speed and in contact. Figure 6(a) shows the monolithic type head (normal type,
These are the head output and AE sensor output when running tests were conducted on approximately 21 million buses for a total of 26 days at 150 rpm with a head load of 15 g, ABS width of 0.58 mm, and the innermost circumference of the disk. . Figure 24(b) shows the output from a truck that has not been tested at the outer periphery of the radial position where the driving test was performed.The driving test was conducted in an office environment with the cartridge directly exposed indoors. However, even in a driving test of 21 million passes,
There are no scratches such as pass marks, and there is a partial drop in the way the head comes out, but this is because the lubricant that adhered to the head remains partially on the disk during start/stop2, and dirt has settled here. The head touch was poor in some areas, but the signal level was not particularly problematic. The above experiment is
After a much more severe test than the FDD driving test,
The driving life of the FDD is 3 million buses (300r).
pm). On the other hand, in the case of HDDs, when used in an indoor environment in contact with each other, there is a problem that pass marks are generated after 10,000 to 20,000 passes.

In this way, sandwich the flexible disc between the liners,
In addition to ensuring the dust removal effect and disk flutter, if a part of the ABS of the IBM M3370 type head is used in contact with the disk, even at high speed rotation, good head touch, installation with a margin, and conventional FD of
It was found that media durability exceeding D was obtained. In addition,
Since the head load of a thin film head with a microslider is less than half that of the monolithic head used in this experiment, it is thought that the media lifespan will be further increased.

By the way, the micro slider HDD shown in FIG.
To ensure stable media running, thin-film magnetic heads for
Pivot 2 from the ABS surface for the ABS spacing (distance between 242c and 243c, gap spacing of 1.5 m)
The distance to 59 is selected to be about 0.75 m+, which is about half the gap interval. This is to prevent the stability against radial rotation, that is, rolling, from decreasing during seek if the distance to the pivot is increased relative to the ABS interval. (not shown) has a cartridge thickness of approximately 3.4 m. Therefore, in order for the suspension arm 251 to come out from the cartridge case, the FDD
As in the case of , the distance from the ABS surface to the lower end of the suspension arm must be about 3 cm. Using the same concept as before, the ABS interval would be 6Iff111, which would not fit into the cartridge window.Furthermore, if a flexible disk is used, stability against rolling is required more than in the case of an HDD.

Therefore, the above idea would make the slider even larger, which is not realistic.

Therefore, in the present invention, the distance from the ABS to the pivot is made as short as possible to increase the rolling stability of the head. An example of the embodiment is shown in FIG.
In contrast to the conventional HDD magnetic head shown in the figure, the suspension 758 is prevented from touching the cartridge 2 by providing an offset by bending the 74a. The length of the bent portion is determined by the thickness of the cartridge, and in the case of the thin film head and 3.5 inch floppy disk, it is approximately 2.3 m++.

The width of 74a in (a) is wide because the width corresponding to the suspension is left as is, and it may be determined as appropriate depending on the required rigidity of this portion.

FIG. 8 shows another embodiment in which 80 blocks are used as the offset means. As for the block, it is best to use something that is rigid and lightweight, such as resin or ceramics.

FIG. 9 shows another embodiment in which the offset means is made of the same material as the suspension 81, generally a stainless steel plate, but this is bent. In this way, various offset means can be considered, but the point is that if you offset the suspension while keeping the distance between the ABS surface and the pivot short, the head suspension will hit the cartridge without affecting the rolling characteristics of the head. You can make it so that there is no such thing.

The present invention is characterized in that the disk can be replaced, as shown in the embodiment of FIG. For this reason, it is necessary to unload the magnetic head when replacing the disk. With conventional FDDs, when ejecting a disk, side 0
Since the head on the side is fixed, only the head on the side 1 side,
It is lifted in conjunction with the disc ejection mechanism.

When loading a disk, the side 1 head is loaded simultaneously with chucking or with a slight delay using an air damper. However, this method cannot be used when the head structure for HDD is basically adopted as in the present invention. In other words, in the present invention, both the heads on side O and side L touch the surface of the disk. By tracking at the same time, it is stable from low speed to high speed.

Good head contact is achieved, and the installation margin is larger than that of conventional FDDs. This is also because media durability is ensured. An example of replacing a disk using a magnetic head for an HDD is a removable HDD. When replacing a removable HDD, it is necessary to prevent dust from entering the cartridge as much as possible.

When there is no cartridge, the magnetic head is on side 0,
Both side 1 are spread out evenly. When the disk is loaded and chucking is completed, the disk is first rotated, and a fan linked to this rotation system causes the disk to rotate (HI).
Clean the inside of A (head disk assembly) at once, and then stop the rotation of the disk. Next, the head is gently lowered onto the disk using a solenoid or stepping motor at a speed that does not damage the disk, the head is loaded, and the disk is then rotated again.

In this method, since the heads on side 0 and side 1 are pushed open equally, a large space is required for head unloading, and it is difficult to make the drive thin like an FDD. In addition, since a driving force is required for head loading, the mechanism cannot be made as simple as an FDD.In the present invention, even though a magnetic head for an HDD is basically used, a mechanism as simple as an FDD is not possible. Load the head with /
I am making it possible to unload.

FIG. 9 shows the head on the side O side. 90 is a suspension, 91 is an offset means, 92 is an ABS surface,
93 is a plate for mounting the head, and 95 is a suspension stopper provided on the head arm.

90c shows the suspension without the suspension stopper projections 94. In this way, when there is no head on side 1, the head ABS surface 92c is at a much higher position than the position where the disk 1 should be. In other words, by bending this much, the ABS
A predetermined head load is applied when the surface coincides with the disk surface.6 In the present invention, by providing 94 protrusions, the ABS surface is positioned at side 1 compared to the ideal position of the disk. . This amount is determined in consideration of errors in head installation, surface contact of the disk, and prevention of damage to the medium by the edge of the head when loading a disk, but approximately 0.51 is desirable.

In (b), in order to perform this positioning accurately, the protrusion 94 is separated from the head arm as 96, and is fastened with a screw 97. The reason why the ABS surface of side O can be placed closer to side 1 than the ideal position of the disk is because the disk is flexible.

FIG. 10 shows the helad unloading mechanism on the side 1 side. The head suspension has a projection 11 for unloading, which is linked with a loading mechanism by an unloading plate 12 so that the head can be loaded/unloaded. FIG. 11 shows another embodiment. The suspension 110 does not have a protrusion or the like for unloading the head. Instead, the suspension 110 is loaded/unloaded by moving the suspension 110 up and down using an unloading means having a structure shown in H1.

As described above, by means of the present invention, loading/unloading of the head of a double-sided head system accompanying disk exchange can be realized with a simple mechanism similar to an FDD. In addition,
In the embodiment of the present invention, the head on the side O side is slightly inserted into the side 1 side during unloading, but it is also possible to move the head slightly into the side O side by interlocking with the loading mechanism. . i.e. side 0
By using the mechanism shown in Figures 10 or 11 for the head on the side, and above all, by widening the interval for unloading, the ABS surface is 0.5 times smaller than the disk surface.
It is sufficient to keep a distance of about 1 m+.

Next, FIG. 12, which shows the shape of the head slider, is a diagram showing the relationship between a conventional head having a symmetrical ABS surface and a disk. (a) The circumferential speed of the disk is slow <, ABS
120 shows the position where the head is in contact with the disk 1. Figure 120 shows the position where there is a helad gap. Figure (b) shows the state where the circumferential speed of the disk is increased, and the head is in contact with the disk 1.
In the case of a 6 flexible disk that is flying by h, this flying height is when viewed from the head output (gap position), and does not physically mean that the head is completely flying from the disk.

Figures (a) and (b) just show the relationship between the innermost circumference and the outermost circumference of the disk. In other words, the head is in contact with the disk at the innermost circumference.

At the outermost periphery, where the circumferential speed is faster, the head flies slightly. In normal CAV recording, the recording density decreases as the head approaches the outer periphery, so spacing loss due to floating does not pose a problem. However, ZB used to increase capacity
In R recording (zone pit recording), the recording density is almost the same on both the inner and outer circumferences. In this case, the signal output will be lower on the outer circumference side where floating occurs than on the inner circumference side.

Furthermore, when the disk is used with varying rotation speed, it is not preferable that the flying height differs depending on the circumferential speed.

FIG. 13 shows an example for solving the above problem.
a) The figure shows when the disk is rotated at low speed.

(,b) Figure shows when rotating at medium speed, (c) Figure shows when rotating at high speed.0 In a double-sided head system, the width of each opposing ABS surface is narrower when there is a head gap, and when there is no head gap. It is more widely formed.

When the disk is rotating at a low speed, the disk and ABS surface are in contact. As the speed increases, pressures 132, 133 are generated between the wide ABS surfaces, 130b and 131a, and the disk surface, as shown in the figure (b), and the disk is forced to move toward the narrow ABS surface, 130a, 131b surface. In other words, a spacing of Fh occurs between the ABS surface without a head gap and the disk surface, but
Almost no spacing occurs on the side where there is a bed gap, and the ABS surface and the disk surface are in contact. (C)
As the rotational speed is further increased as shown in the figure, the air pressure on the wide ABS surface further increases, and the spacing on this surface becomes even larger. However, since the ABS surface and the disk surface on the opposite side are pressed together by large air pressure, almost no spacing occurs even if the rotational speed increases. A
The BS width is determined by the number of rotations of the disc.

The narrower ABS width may be determined based on the head load, friction coefficient, media durability, etc., and then the wider ABS width may be determined to be approximately twice the narrower one.

As the rotation speed increases or the circumferential speed increases, the disk becomes distorted as shown in figure (c), but under normal use,
Fh is 0.2 to 0.3 groups at most, and the thickness of the medium is 75p.
, is negligible compared to the gap interval of 1.5 ms. The head gaps 120a and 120b are preferably formed outside the center of the ABS 130a and 131b, that is, on the opposite side of the ABS separation groove. By setting the width, the ABS surface with the head gap and the disk surface can be kept in almost contact state regardless of the circumferential speed of the disk. The method of the present invention does not forcibly increase the head load or narrow the ABS width.
Also, one side of the ABS is separated from the disk surface. This represents a great advantage for media durability.

Furthermore, since the coefficient of friction is also reduced, there is an advantage that the load torque of the spindle motor can be reduced.

Next, the track format of a specific disk will be explained.The present invention has a high density, large capacity, and
High-speed removable disk device, i.e., storage capacity of 100 MB or more after formatting a disk,
The company is aiming for a data transfer rate of 1.5 Mbytes/sec. The disk used is a 3.5 inch Ba ferrite floppy disk, the head is a thin film head, and the track density is 2000.
T P I, linear recording density 1*70-75 kB P L disc rotation speed is 1800 rpm. Unlike the bulk head of conventional FDDs, thin-film heads can accurately form track widths and gap lengths in the same way as in semiconductor processes. In addition, even if the inductance is the same number of coil turns, it is one order of magnitude smaller than that of a bulkhead, which causes problems such as unerased tracks, OWM noise (overwrite noise), and poor recording current rise caused by differences in track width and gap length. Occurring OWM is not a problem, so there is no need to use a pre-erase head, which is conventionally required for high-density recording.

Further, when a thin film head is used, a low-noise preamplifier can be used, and even if the signal level decreases, the system S/N ratio does not increase and deteriorate because of the narrow track. Therefore, it is possible to select a high-density recording medium by focusing on the medium S/N and resolution rather than the output.

When using a floppy disk, tracking servo control for primary track runout (worst ±10 IJM) and secondary track runout (worst ±10 IJM) caused by eccentricity associated with disk replacement, anisotropic expansion and contraction of temperature and humidity of the medium, etc. The tracking performance of the system is important in determining track density. If the track density is 20007 P, the track width is required to be approximately 1041, and the positioning accuracy is required to be approximately ±0.6. The actual positioning error includes the above-mentioned first-order component,
In addition to the next component, there is a random component. It also needs to be sufficiently strong against vibrations and shocks applied to the drive from the outside.

Track density is 2000T for PI class HDD.

A servo band of about 400 Hz is used.

However, in the present invention, due to the use of a flexible disk, there is a large second-order track runout, so in consideration of the tracking characteristics for this, 5407 is used as the servo band. At this time, the tracking error for the worst value of the first and second track runout is approximately 42 dB and 3
Because it can be taken in 0dB increments.

±0.08. , ±0.3p, which is below the permissible value of the tracking error. By the way, it is said that the sampling frequency of servo information is required to be about 7 of the servo band. For this reason, the conventional sector servo method, which embeds servo information in each sector, cannot obtain a sufficient sampling frequency.Therefore, we have developed a modified sector servo method, which embeds servo information in each data sector as well. I will use it.

FIG. 14 shows an example 140 of the disc format of the present invention.
The unformatted capacity per sector is 7.
76 bytes, format capacity is 512 bytes.

Each sector has a servo field a141, PL La1
42 (PLL signal for ID field demodulation),
ID field 143, PLL Lb 144 (PLL signal for data/ECC field a demodulation), data/ECC field a 145. WRG 146
(Write recovery gap), servo field b147. P L Lc14g (Data/ECC
signal for field demodulation), data/ECC field b149. One sector is divided into two by servo information, each having a length of 388 bytes from the edge detection position shown at 4141 and 147. Servo field 8141 is AGC15,1,E
RASE152.5YNC153, PO8a, ZONE
155, p.

Consists of sb. On the other hand, servo field b is ERAS
E157.5YNC153, PO8a154, ZONE
158, POS b156. ERASE15
2 is for detecting servo field a, and consists of 4 bytes of DC erase in which no data is recorded. On the other hand, ERASE 157 is for detecting servo field b and consists of 2-byte DC erase.

Although sector marks can be detected from the length of the ERASE section, an identification signal is provided in the ZONE section for greater reliability. The details of the servo field are shown in FIG. 15. The ZONE section consists of a sector signal, an index signal, and a data zone signal.
It is formed so that the sector signal is at H level, and the sector signal at Z ON E 157 is at L level. Sector marks can be detected accurately from these signals. PO8a
The position bits used for speed control, P, Q,
Periodic signals R, A, B, C, and D are formed. The details of how to use these signals are described in USP 4,631,606, so I will omit the details, but by using these signals, it is possible to directly detect up to 6 tracks/sample, and if periodicity is used, it is possible to detect up to 32 tracks, twice that. / sample can be detected with an acceptable speed error. This time, the track density is 20007 PI, so when 16 tracks/sample, the detection speed is 0.78 m/s.

This speed is a detection speed that allows an average seek time of about 25 m5. In addition, in FIG. 1 which is an example of the present invention,
Although it is not designed to use an external optical scale, position detection means such as an optical scale may be used in addition to disk servo information for reasons such as high speed seek, format efficiency, and stiffness against disturbance.
is a burst position signal and is used for single position tracking control. The purpose of using the burst signal is to improve the S/N of the position signal, which decreases due to higher track density, by increasing the number of position bits.

By the way, as mentioned above, the double-sided head system of the present invention has a symmetrical head suspension and is adapted to follow the deflection of the disk caused by the large surface runout of the disk or the way the disk is placed. Therefore, even if the track spacing between both heads is adjusted accurately when assembling the device, the track spacing between the two heads may be incorrect in actual use.
In the device according to the embodiment of the present invention, which has a track density of 2000T P I, where expansion and contraction due to the temperature and humidity of the disk is extremely large relative to the track width, it is conceivable that the track misalignment between both heads may extend to multiple tracks. .

Therefore, if the track misalignment between both heads is unknown,
RTZ (return to zero,
(initialization of track numbers), resulting in a problem of longer access time. However, in the present invention, the first
As shown in FIG. 5, it has a plurality of position signals having a maximum of 16 track periods. Therefore, if the positional deviation is less than ±8 tracks, it can be automatically corrected by using these position signals even if the head is switched. If the track deviation exceeds this range, the position bit is changed to 154 depending on the expected size of the deviation.
Another method is to add it to PO8a.
After loading the disk into the device, seek to an appropriate position, for example, near the center of the disk, switch heads, and read the track address on each side. Then, calculate the amount of track deviation from the difference and use this as the track offset during subsequent seeking.If the disk is unformatted, format it one side at a time, and then correct it using the same method. However, even if track misalignment is corrected using this method, partial track misalignment still occurs due to expansion and contraction of the disk due to temperature and humidity, and disk flexure.

Since this amount is at most several tracks, it does not pose a problem when a periodic servo pattern of as many as 16 tracks is used as in the present invention.

The embodiment of the present invention has a recording density 60 times higher than that of a conventional 2HD floppy disk. Therefore, defects in the medium and reduction in signal S/N become problems. Therefore, first, the ID field 143 is double-written with ID,
Furthermore, ID detection is ensured by using it together with the servo sector detection signal. On the other hand, the data field uses powerful error correction similar to optical discs. Optical discs that are already commercially available use a 5-interleave Reed-Solomon code in a 512-byte format.

However, since the track width of the embodiment of the present invention is eight times wider than that of an optical disk, it is expected that there will be considerably fewer defects than an optical disk. Therefore, we decided to use a 54-interleave Reed-Solomon code here. Figure 16 shows the data arrangement, 160 is data/F
This is data recorded in the CC field 145, and 16
1 indicates data recorded in the data/FCC field 149. R8 is a resync pattern, which is provided in units of 20 bytes, in order to prevent errors from propagating due to defects. USER is the user who saves the data in addition to the data.
It is prepared so that it can be used for purposes such as control data.

FIG. 17 is a diagram showing the positional relationship of zones when ZBR recording is used. In the present invention, since a thin film head of a micro slider is used, the innermost radius is 22 m on side 1, 23 m on side 0, and 17 m + stroke.
Therefore, the number of tracks is 1338.

Unformat capacity when not using ZBR recording is 1
32.9MB, capacity after formatting is 87.68
M bytes does not reach 100 M bytes.Therefore, as shown in the figure, in the present invention, the data track area is divided into four. 170 Dl, 171 D2, 172
D3 and D4 of 173 respectively indicate valid data zones.

The number of tracks in each data zone is 330, and the number of sectors is 64.76 and 88.100 from the innermost circumference, so the format capacity is 110 MB, which is the target of 10.
This means that it can be achieved with 0MB. Therefore, the increase in format capacity due to 4-division ZBR recording is approximately 25%.
It is possible to further increase the format capacity by increasing the number of zero divisions. However, the circuit becomes complicated.

Since the rate of increase in capacity is small, the actual limit is about 10 divisions. On the other hand, G1 of 174, G5 of 178 indicates the outer guard zone, G2 of 175, G5 of 176
G4 in 3.177 indicates an inner guard zone. The inner guard zone is provided for the combined use of ZBRE recording and the modified sector servo system, and each is allocated 6 tracks.

By providing this zone, there is ample time for clock switching between adjacent data zones during seek, so servo information can be captured accurately even when seeking at high speed. However, if there is a position detection means other than the disk, such as an optical scale, this is not necessary.

In the embodiments of the present invention, sector servo is basically used as an example.
But it can be adapted as well. In this case, in addition to the data R/W gap, a servo gap can be provided on the other side of the twin-body slider. Further, although the present invention describes a removable type in which the disk is replaced, it can be similarly applied to a case in which the disk is not replaced.

Furthermore, the present invention can be applied not only to magnetic recording but also to optical discs using flexible discs. however,
In the case of an optical disc using an objective lens, the allowable focus error is as much as ±1/ffi. Therefore, when designing a head slider/suspension, etc., it is sufficient to maintain the allowable focus error at the outermost periphery.According to the spirit of the present invention, there is no need for a focusing mechanism.
Optical pickups are very easy to configure. FIG. 18 shows an example of a pickup in which a semiconductor laser 181 is directly mounted on a Herad chip 180. By using the signal detection ability of the semiconductor laser itself, it is possible to read the signal without using a photodetector. Further, if a thin film process is used, it is possible to collectively form a semiconductor laser, a photodetector, an optical system for various signal pickups, etc. on a head chip. Therefore, it is also applicable to 9MO recording media. In addition, since optical discs can generally be used with a high flying height, for example, if a CD disc is stored in a liner cartridge and read by the optical pickup described above, an extremely simple pickup system can be created. It can also be easily used as a double-sided device.

As described above, the present invention is applicable to everything from magnetic disks to optical disks, and can be implemented with various modifications without departing from the gist of the present invention.

〔Effect of the invention〕

As described above based on the embodiments, according to the present invention, by using a double-sided head system whose basic structure is a flexible disk sandwiched between liners and an HDD head, it is possible to achieve higher density than a fixed HDD. Speeds comparable to HDDs can be easily achieved at low cost. Also, there is no risk of head crash like with removable HDDs,
Furthermore, the lifetime of the medium can be longer than that of a general FDD.

As described above, according to the present invention, it is possible to easily realize a removable magnetic disk device that is as fast and large-capacity as an HDD, and as simple and inexpensive as an FDD.

Its practical effects are extremely large.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the removable magnetic disk device of the present invention, FIGS. 2 to 6 are diagrams showing experimental data to demonstrate the gist of the present invention, and FIGS. 7 to 8 are diagrams showing both sides of the device. Figures 9 to 11 are diagrams for explaining an embodiment of the head system suspension and offset means; Figures 9 to 11 are diagrams to explain an embodiment of means associated with disk exchange in a double-sided head system; Figures 12 to 13; The figure is a diagram showing the relationship between the head slider and the flexible disk, No. 14.
15 shows an example of the servo pattern, FIG. 16 shows an example of the data/FCC field of the track format, and FIG. 17 shows an example of the track format of the disk. FIG. 3 is a diagram showing an example when ZBR recording is used. Figure 18 shows one implementation when adapting to optical pickup.
Figures 1 through 3 are diagrams showing a conventional magnetic head and a double-sided head system, and Figure H is a diagram showing a magnetic head of a disk device using the Bernoulli method. 1...Flexible disk 2...Disk cartridge 3...Liner 4...Chucking hub 5...Spindle motor 9...Magnetic head assembly 10...Head chip 15...Position 1 16
... Carriage agent Patent attorney Nori Chika Ken Yuma H. Rotation speed (tL) (Et!L) Rotation speed (b Figure 2 (Ichi yt) Figure 3 Article 10, 6 -0 .4 -0.2 0
0.2 0. lJ O,6 head installation C1 height (Q,) -0,6-0,4-0,20a2 0.4
tl, 6 head mounting height (b) Head mounting height t17 height Fig. 5 (/6oorpm, att5>,) (tsoorpm, 1rlL tg) Fig. 6 < a,) Fig. 7 Cb) 9th Fig. 11 Fig. 12 (0-n Fig. 13 Fig. 17 Fig. 18 Fig. 19 Fig. 20 Fig. 21 Fig. 22 (b) Fig. 24 (,,) Export 9 Fig. 2 Δ Fig. 2 Figure 26 v!J

Claims (1)

[Claims] A flexible disk on which servo information for positioning a head for recording information is recorded, a liner that sandwiches the flexible disk from both sides, and a liner that sandwiches the flexible disk between the liners symmetrically from both sides. head means including the head that records information by being brought into contact with the gimbal of the head means, the contact state of the head of the head means with the flexible disk by the gimbal is ensured by the liner, and the contact position is controlled by the servo. A disk device characterized by being defined by information.