JP2002150630A - Magneto-optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an MO disk which does not require a landing area dedicated to an MO disk, and is used in a system which loads and unloads a magnetic head dynamically so as to be usable all the areas of the MO disk for data recording. SOLUTION: The magneto-optical disk is provided with a substrate and a magneto-optical recording layer on the substrate. Furthermore, the magneto- optical disk is provided with an overcoat layer having a thickness of within the range of 25 nm to 200 microns on the recording layer. Data are recorded on the magneto-optical disk and read from the magneto-optical disk by using a laser beam made incident on the overcoat layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to the field of magneto-optical data recording disks. More particularly, it relates to the field of magneto-optical recording disks used for coating incident recording techniques.

[0002]

2. Description of the Related Art A typical magneto-optical (MO) disk drive records data by locally heating a portion of the disk. On MO disks or media,
A recording layer of magnetic material is included. As the heated portion of the medium is heated by the laser beam, its coercivity decreases. Therefore, the magnetic polarity in that portion can be reversed by the applied magnetic field. Such a disk
In a drive, data is read from a medium by illuminating a portion of the storage medium with a linearly polarized laser beam. The plane of polarization of the illumination beam is rotated by the Kerr rotation effect. The direction of rotation is determined by the magnetic polarity in the illuminated portion of the storage medium. When the disk is read, the polarization rotation is determined by the pair of photodetector and polarization beam splitter to generate the output data signal.
MO disk drive limitations include data access time and density at which data can be recorded.

FIG. 1 illustrates a conventional MO recording system 100, typically used with MO media having a diameter of 130 millimeters (mm). System 100 is an example of a “substrate incidence” recording system. In a substrate injection system, laser light is incident on a thick substrate, travels through the substrate, and is focused on a recording layer below the substrate. System 1
00 includes an objective lens 102 for focusing a parallel beam of light onto a disk 116. Disk 116
It is an example of a typical double-sided MO disk. MO disk 116 includes substrates 104 and 114 that form outer layers on opposing sides of disk 116. Substrates 104 and 114 are made of a material such as plastic or polycarbonate and have a thickness of about 1.2 mm. Substrate 104
There is a recording layer 106 below and a recording layer 112 below the substrate 114. The recording layers 106 and 112 are Tb-
It can be made of any one of several well-known materials, such as rare earth transition metal alloys such as Fe-Co. The laser light beam passing through the objective lens 102 penetrates the substrate 104 as shown, and is incident on a focal point on the surface of the recording layer 106.

[0004] System 100 has several disadvantages. One of the drawbacks of the system 100 is that it is necessary to apply energy to the recording layer to erase the data before writing new data. This is because a large fixed magnetic coil (not shown) having a large inductance is arranged on the opposite side of the disk 116 from the objective lens 102 to support the writing process. This coil is held relatively far from the media surface and has a relatively large inductance so that the magnetic field cannot be reversed with high frequency. Therefore, it is necessary to erase data before writing new data. The need to erase before writing slows down the process of writing data to disk 116.

Another disadvantage of system 100 is that disk 1
16 is relatively low in data density.
Another disadvantage of system 100 is that only one side of disk 116 can be accessed at a time. This is because a relatively large coil occupies space on the disk opposite the objective lens. Therefore, this space cannot be used for other lenses and actuators. In order to access the other side of disk 116, disk 116 must be removed from system 100, flipped over, and reinserted. However, the disk 116 has the substrates 104 and 114
Is relatively thick, the disk 116 can be handled without causing a risk of data loss or data reading difficulties due to contamination, and the like, so that data security is good. However, this thickness of the substrates 104 and 114 is a problem. Because of this added thickness of the substrate material, uneven heating and cooling characteristics of the outer radius cause uneven solidification during the molding process. Therefore, light passing through the substrate at the outer radius and the inner radius is distorted, and birefringence occurs. Therefore, the edge of the disk is not suitable for data recording, and the data recording capacity of the disk is reduced. More typically, a thick substrate will cause some light distortion across the disk.

Another disadvantage of the system 100 is its tilt. The inclination means that the angle between the axis of the incident light and the recording layer surface of the medium deviates from 90 degrees. Since the incident light must pass through a relatively thick substrate before reaching the recording layer, the incident light is distorted by the occurrence of the tilt. This substantially limits the possibility of reducing the spot size of the incident light and consequently substantially limits the possibility of increasing the recording density of the MO disk. It is desirable to reduce the spot size because the smaller the spot size, the higher the numerical aperture (NA) of the system. N
There are several factors that determine the upper limit of A. One of the factors
One is inclined. Thus, in systems such as system 100, the slope limits the increase in NA and limits the recording capacity of the disc.

FIG. 2 shows another conventional MO recording system 20.
FIG. The parallel light beam 202 is the objective lens 2
04 and reaches the disk 216. Disk 21
6 includes a substrate 206 that is typically 0.6-1.2 mm thick. Further, the disk 216 includes the substrate 206 and the protective layer 2.
10, a recording layer 208 is included. In the system 200, the large fixed coil of the system 100 has been replaced by a relatively small coil in the floating magnetic recording head 214. The flying height 212 is maintained by an air bearing created below the flying magnetic recording head 214 as the disk 216 passes. To write on the disk 216, a combination of the magnetic field generated by the magnetic recording head 214 and the parallel light 202 passing through the objective lens 204 is used. The small coils of the magnetic recording head 214 have less inductance than the large fixed coils of the system 100. Due to the reduced inductance,
By switching the magnetic field, data on the disk 216 can be directly overwritten.

[0008] System 200 still suffers from the relatively low recording density. For example, system 2
Because 00 is a substrate injection system, thick substrate 216 causes system 200 to have the same slope as system 100. Further, since the disk 216 is not a double-sided disk but a single-sided disk, the overall recording capacity is small.

The system 200 also includes a disk 216
There is also a disadvantage that the light on one side of the disk 216 and the magnetic recording head 214 on the upper side (the lower side in the drawing) of the other side of the disk 216 must be mechanically coupled. Typically, this coupling is
2 to the magnetic recording head 2
This is achieved by a mechanical linkage that passes to. This mechanical linkage cannot be interfered by the movement of the objective lens 202 or the disk 216.

FIG. 3 is a diagram showing a conventional MO recording system 300. System 300 is an example of an “air-entry” design in which the lens is held very close to the media and the laser light is incident on a very thin protective layer 309 on recording layer 308 of disk 318. Other prior art air entry designs may not have a protective layer, in which case the surface of the recording layer is the disk surface. System 30
0 uses a floating magnetic recording head 316 and two objective lenses consisting of a lens 314 and a lens 312. In a prior art system similar to system 300,
Other lens designs are used, such as, for example, a single lens or a three objective lens design. Lens 314 is held extremely close to disk 318. Parallel light beam 3
02 passes through the lens 312 and the lens 314. The lens 312 and the lens 314 are integrated with the slider 304 and the magnetic recording head 316. System 30
A floating height 306 of 0 typically results in an MO disk 318
Shorter than the wavelength of the laser light used for reading from the disk and writing to the disk.

[0011] The disk 318 has an MO recording layer 308 on a substrate 310. In the system 300, the floating objective lens 314 is so close to the disk 318 that the need for a focus actuator is eliminated. As is well known, a focus actuator is a mechanism that adjusts the height of an objective lens on a disk during read and write operations. In the case of the system 300, the floating lens 31
2 and 314 heights and thus the floating objective 31
The focus of 2 and 314 is determined by the distance between recording layer 308 and floating objectives 312 and 314, as well as by the air bearing created between slider 304 and disk 318 when floating.

By keeping the spacing between the floating objectives 312 and 314 and the recording layer 308 shorter than the wavelength of the laser light used, the laser light is brought into the near field.
field) The focusing can be performed in the operation mode. As is well known, the near-field mode of operation uses the phenomenon of evanescent coupling, so that the objective lens must be kept very close to the recording layer. When recording is performed using evanescent coupling, the spot size can be reduced, so that the recording density can be increased and the data throughput can be improved.

System 300 has several disadvantages. For example, the very thin protective layer 309 surface or the surface of the lens 314 closest to the disk can become contaminated, resulting in permanent damage to the data or disk drive system.

Another disadvantage of the system 300 stems from the fact that the floating height must be tightly controlled in order to properly control the focus, since there is only one objective and no focus actuator. The variation in flying height and the thickness of the very thin protective layer 309 on the recording layer must be controlled within the tolerance of the focal depth of the floating lens. Generally, the tolerance between the floating height 306 and the thickness of the protective layer 309 is a percentage of the nominal thickness. Therefore, the nominal thickness of the very thin protective layer 309 must be reduced in order to reduce the tolerance. For example, the depth of focus tolerance is typically plus or minus 0.5 microns. A typical tolerance for adding a very thin protective layer 309 is 10 percent of the protective layer thickness. Therefore, the sum of the floating height 306 and the thickness of the very thin protective layer 309 must be very small so that the variation of the very thin protective layer 309 is less than 0.5 microns.

In the case of a near-field system such as the system 300, the floating height (the bottom surface of the floating lens 314 and the recording layer 308
Must be smaller than the wavelength of the laser light. The wavelength of the laser light is typically 70
0 nanometers. Therefore, the thickness of the protective layer on the recording layer 308 would be about 25 nanometers. This is extremely thin, and the data on the recording layer 308 is
It does not protect the removable disk application from manual handling or corrosion or contamination during the shelf life. Even if protected by a cartridge that covers disk 318, some contamination by atmospheric particles or humidity or corrosive gases is inevitable over time.

Another disadvantage of the system 300 is that the system needs to apply a lubricant to the surface of the magnetic media because the very low flying height can cause the media to contact the head. Is what can happen.
Lubricants are used to minimize friction at the contact points and to prevent the media from causing a "head crash". The use of lubricants is expensive, and the application of lubricants is an additional step in the manufacturing process. The presence of a lubricant is also a drawback because the presence of the lubricant makes it impossible to wipe the media in the drive mechanism to remove surface contaminants.

All conventional disk drives share similar drawbacks regarding accessing data on recording disks. Current disk drives, even those designed to access both sides of the media,
It is restricted so that only one side of the medium can be accessed at a time. Heretofore, both sides of a double-sided disc have never been simultaneously and separately accessible. One reason for this is that the read / write head mechanisms on either side of the disk are built to move together or not at all. Therefore, current disk drives have limited data access speeds. This drawback is also shared with earlier MO drives and drives that use other techniques, such as those used in computer hard disk drives.

There is a technique in which a plurality of disk drives appear on a client device as a single drive. Redundant independent drive array (RAID: Redundant
In arrays of independent drives, incoming data is split into multiple streams, which are written to multiple drives simultaneously. With RAID, throughput can be improved by splitting a single input data into streams and writing it partially to multiple drives simultaneously. With RAID, data redundancy can also be achieved by sending different copies of the same data to multiple drives simultaneously. Although the use of RAID can increase access speed, RAID is simply a matter of conventional disk storage.
Devices that contain duplicate drives and are expensive and complex because each has all of the limitations discussed above with respect to current disk drives.

[0019]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic disk having an overcoat layer having a thickness sufficient to handle the disk without risk of data loss.
O disk.

Another object of the present invention is that the thickness of the overcoat layer of the MO disk is not limited by the need to focus using the distance from the recording layer of the MO disk to the floating objective. An object of the present invention is to provide an MO disk that accesses data on the MO disk using a floating objective lens having a focus actuator.

It is another object of the present invention to provide an MO disk which operates in an MO drive and directly executes overwriting of data without performing initial erasure.

It is another object of the present invention to provide a MO head for use in a system for dynamically loading and unloading a magnetic head such that a contact start / stop event occurs and the MO disk does not need to be lubricated. Is to provide a disk.

It is another object of the present invention to use a magnetic head in a system for dynamically loading and unloading a magnetic head such that a dedicated landing area for the MO disk is not required and the entire area of the MO disk can be used for data recording. Is to provide an MO disk to be used.

It is another object of the present invention to provide a double-sided MO disk that allows simultaneous and separate access to both sides of the MO disk.

[0025]

SUMMARY OF THE INVENTION A magneto-optical (MO) disk and a method for accessing data recorded on the MO disk are described. The MO disk includes a substrate and a magneto-optical recording layer provided on the substrate.
In addition, MO disks have an overcoat layer applied over the recording layer, having a thickness between 25 nanometers and 200 microns.

[0026]

DETAILED DESCRIPTION OF THE INVENTION The present invention includes a magneto-optical (MO) disk drive and an MO disk. In one embodiment, the recording is performed using a far field technique with a single objective lens that focuses the collimated laser light. After passing through the objective lens, the parallel laser light passes through an opening in the floating magnetic head floating on the MO disk. Through conventional recording techniques using protected MO disks, an increase in data recording density is achieved. In one embodiment, the MO
The disc includes two opposing recording layers covered by an overcoat layer. In this embodiment, both the floating magnetic head and the objective lens are placed on each side of the MO disk to perform coating incident recording, where light is incident on the overcoat layer and focus is maintained by the focus actuator. And are started separately, so that both sides of the MO disk can be accessed simultaneously and completely separately.

FIG. 4 shows an MO according to an embodiment of the present invention.
1 shows a data recording and retrieval system 400. FIG.
In FIG. 4, similarly numbered elements except for "a" or "b" are identical or functionally equivalent.
For example, objective lens 414a is the same or functionally equivalent to objective lens 414b.

The objective lens 414a focuses the parallel laser light beam 402a. The flying height 406a of the magnetic recording head 418a on the disk 420 can be between 0.05 and 5.0 microns, depending on the particular embodiment. Since the magnetic recording heads 418a and 418b generate a magnetic field having a relatively low inductance, data can be directly overwritten by switching the magnetic field. Higher recording densities can be achieved by modulating the magnetic field generated by the magnetic recording heads 418a and 418b during the writing and reading processes.

The magnetic recording head 418a has an optical channel 416 which is an opening passing through the center of the magnetic recording head 418a.
a. The slider 404a is a magnetic recording head 418a.
When the disk 420 is rotating,
Allow the magnetic recording head 418a to float above the MO disk 420 on the air bearing. System 40
0 is the MO disk 420 using well-known far-field techniques.
Record the data above. In the far-field technique, the focal length (the distance from the objective lens to the focal position on the recording layer) is relatively long, so that the objective lens does not contact or come very close to the recording layer. Also, the objective lens may not be coupled to the slider.

In this embodiment, the MO disk 420 has spiral grooves in both recording layers. The spiral grooves on this opposing recording layer spiral in opposite directions so that the rotating disk can be accessed from both sides simultaneously. In another embodiment, a double-sided MO disk having concentric grooves is used. Spiral grooves are preferred when the recorded and accessed data is sequential. The concentric grooves are preferable when the data to be recorded and retrieved have a low sequentiality and a high randomness.

The MO disk 420 includes a central substrate 412. On both sides of the substrate 412, the recording layers 410a are respectively provided.
And 410b. In one embodiment, the recording layer 410
Is made of a rare earth transition metal alloy such as Tb-FeCo. The overcoat layer 408a forms one surface of the MO disk 420 and covers the recording layer 410a. The overcoat layer 408b forms both sides of the MO disk 420 and covers the recording layer 410b.

In one embodiment, MO disk 420 includes additional layers. For example, in one embodiment, each recording layer 410 includes multiple layers. Multiple recording layers are known in the art and will not be described in detail herein. In one embodiment, MO disk 420 includes a reflective layer and a dielectric layer, as is known in the art.

[0033] The thickness of the overcoat layer 408 is from about 25 nanometers to 200 microns. The thicker the overcoat layer 408, the more adverse contamination effects occur on the surface of the overcoat layer 408. Examples of contamination that typically interfere with the reading and writing processes include dust and fingerprints. The effect of particles on the surface of the overcoat layer 408 being on the focal point decreases as the focal depth increases. One consideration in selecting the thickness of the coating 408 is to reduce the strength of the magnetic field generated by the floating magnetic recording head 418. Above a certain thickness, the size of the coil must be increased, which increases the switching time of the magnetic field, which in turn degrades the performance of the disk drive.

[0034] The overcoat layer 408 can be made of a variety of materials depending on the design elements. For example, the coating material can be selected to enhance the optical properties or reduce the diameter of the light spot incidence on the media (known as a reduction in spot size).

In one embodiment, overcoat layer 408 includes multiple layers. For example, in one embodiment, overcoat layer 408 comprises a relatively thin silicon nitride layer as well as a relatively thick acrylic ultraviolet (UV) resin layer. The silicon nitride layer is applied by a sputtering process and typically has a thickness of about 50 nanometers. The overcoat layer is applied by a spin coating process and typically has a thickness of about 10 microns.
In another embodiment, the overcoat layer 408 comprises a thin layer (about 50 nanometers) of a dielectric material such as silicon nitride,
It can consist of a thick layer of transparent material such as polycarbonate applied by a bonding or laminating process.

In either case, the thickness of the coating 408 can be quite wide and limited to very small dimensions, as in the prior art where floating height must be used to focus. It has not been.

The overcoat layer 408 requires no lubricant because the use of the apparatus and method of the present invention virtually eliminates the possibility of contact between the media and the head.
Thus, in embodiments including a disk wiping mechanism, the magnetic head can be loaded after wiping the contaminants from the surface of the disk 420.

[0038] The coating 408 can have a bump height that is significantly greater than the bump heights of the prior art used in the air incidence technique. The uneven height is the maximum height of a portion protruding from the surface. For example, in one embodiment, the uneven height of the coating 408 can be from 0 to 5 microns. In the MO disk 420, since the floating height of the recording head 418 does not control the focal point, a larger uneven height is possible, and thus the floating height can be made relatively high. MO disk 420
Has the advantage of being simpler and less expensive to manufacture because the tolerances of the surface finish are less stringent.

In one embodiment, the magnetic recording head 418 is dynamically loaded so that no contact start / stop events occur during operation. Further, since the floating height of the magnetic recording head 418 is sufficiently large, accidental contact between the magnetic recording head 418 and the MO disk 420 hardly occurs. Therefore, no lubricant is required on the surface of the MO disk 420. Another advantage is that the entire recording layer 410 of the MO disk 420 is used for data recording because a dedicated landing position is not required for a contact start / stop event as in some MO disks found in the prior art. Is to be done. Since prior art methods rely on contact start and stop events, a portion of the disk must be reserved for the landing zone and cannot be used for recording. Therefore, the data density of the entire MO disk 420 can be higher than that of the conventional MO disk.

In one embodiment, the overcoat layer 408
Uses spin coating. In other embodiments, the overcoat layer 408 can utilize other methods, such as sputtering. Overcoat layer 408
Is thinner than a substrate of a prior art disk such as the disk shown in FIG. 1, so that no birefringence occurs in any part of the MO disk 420 when light passes through the overcoat layer 408. The coat layer 408 can be formed consistently. Birefringence is a limiting effect on NA. The advantage of eliminating birefringence is that the NA is higher, and consequently the recording density on the MO disk can be increased.

The overcoat layer 408 is formed as shown in FIG.
Much thicker than the disk layer used in air-incident recording (as shown in the prior art). Therefore, the MO disk 420 can better prevent handling and environmental contaminants than the MO disk used for air incident recording.

Although the overcoat layer 408 is thicker than the disk used for air incidence recording, the overcoat layer 408
Is much thinner than the substrate of the MO disk used for substrate incident recording. Thus, system 400 has the advantage of being significantly less inclined than, for example, system 100 or 200. Therefore, it is possible to use a lens with a high NA, resulting in an increase in recording capacity and an increase in possible throughput.

In this embodiment, the focus actuator controlling the objective lens 414a and the magnetic head 418a includes the objective lens 414b and the magnetic head 418b.
Is completely independent of the focus actuator controlling the Focus actuators are known in the art and are not shown for clarity. The system 400 reads and writes on each side of the MO disk 420 completely independently. For example, using each head assembly, the recording layer 410a
Can be read from the recording layer 410b at the same time as writing.

In the embodiment of FIG. 4, MO data recording and retrieval system 400 includes two magnetic heads 418 and two lenses 414 for separately accessing each side of MO disk 420. In other embodiments, the MO data recording and retrieval system may include only one magnetic head 418 and one lens 420.

FIG. 5 illustrates a slider / switch according to one embodiment.
Magnetic recording head suspension assembly 1000
FIG. Suspension assembly 1000
Suspension assembly such as the slider 404
And a magnetic head 418 for suspension. The magnetic recording head suspension assembly is not shown in FIG. 4 for clarity.
Before the read and write operations, rotate the disk,
The slider / magnetic recording head suspension assembly 1000 is then loaded by engaging, ie, loading, the slider / magnetic recording head suspension assembly 1000. The air bearing is the slider / magnetic recording head assembly 101
The slider surface will never come into contact with the disk surface because it is formed between the zero and the rotating disk. In another embodiment, the slider rests on the disk surface when the disk is not moving. In these embodiments, the slider rests on the disk surface until the disk reaches a constant rotational speed, at which time an air bearing is formed to separate the slider from the disk surface.

Further, the slider sweeps out floating particles on the surface of the MO disk that prevent or block light from passing to the recording layer.

A magnetic circuit resident on a floating slider can operate effectively by floating a few microns away from the recording layer and the medium surface. The ability of the slider to float over several microns above the media surface allows the media surface to be manufactured without strict tolerances for surface irregularities and flatness. For example, typical tolerances for the surface irregularities of the MO disk of the present invention are less than about 2 microns.

During read and write operations, laser light beam 1008 passes through objective lens 1006 and through optical channel 1013 in slider / magnetic recording head assembly 1010. In this embodiment, optical channel 1
013 is rectangular, but in other embodiments circular or irregular shapes are also possible. The optical channel 1013 is surrounded by a wire winding device 1012. Slider / magnetic recording head assembly 1010 and winding device 1
012 is the gimbal 1004 and the load beam 10
02 supported. The gimbal 1004 also includes an opening to allow light to pass through the gimbal 1004. The openings in the gimbal 1004 are rectangular in this embodiment, but can be circular or irregular in other embodiments.

FIG. 6 is a top view of a disk drive 700 according to one embodiment of the present invention. In this embodiment, disk drive 700 includes two optical pickup / front-end electronics assemblies 716a and 716b. In this embodiment,
The assembly 716 is moved back and forth on each side of the MO disk 710 by linear focus actuators. In other embodiments, other focus actuators may be used, for example, a rotary focus actuator.

The optical pickup / front-end electronics assembly 716a is located on one side of the MO disk 710 and the assembly 716b is
It is located on the opposite side of the O disk 710. Each assembly 716 is integrated with the optical device assembly. As is well known, an integrated optical device assembly includes:
One unit includes one focus actuator, one tracking actuator, one coarse actuator, optical components, and front end electronics. In the embodiment shown in FIG. 6, an integrated optical device is selected in part for ease of assembly. Extreme precision is required to align the optical components of the mechanism. Using integrated optics, the entire disk drive can be assembled after performing alignment on an assembly, such as assembly 716a, located on a separate station. This makes assembly quick and inexpensive.

In another embodiment, a separate optical device is used. The separated optical device includes a moving part and a fixed part. The moving part moves on the disk and includes an objective lens, a mirror, a fine movement actuator, a coarse movement actuator, and a focus actuator. The fixed part includes the laser diode, detector, optics, and front-end electronics.

In this embodiment, the focus actuator and the fine actuator are coupled to the coarse actuator. The coarse actuator makes a relatively large movement horizontally across the disk surface. The focus actuator moves in a direction perpendicular to the disk to focus the laser light. The fine movement actuator makes small horizontal movements or microsteps to keep the focused laser light on the tracks of the disk.

In this embodiment, the magnetic head is coupled to the coarse actuator by compliant and flexible means. In this embodiment, the magnetic head is separated from the focus actuator and the fine actuator. The objective lens is coupled to a focus actuator and a fine movement actuator. In an alternative embodiment, the magnetic head is coupled to both a focus actuator and a fine actuator, and then both are coupled to a coarse actuator.

The disk drive 700 includes a carriage coil 702, a return magnetic path assembly 704, and a magnet 706. The spindle motor 708 is
It engages with the MO disk 710 as described in detail below. In this embodiment, dimension 718 is about 210 m
m, dimension 714 is about 152 mm, 712 is about 130 mm
It is. In other embodiments of the disk drive 700, some of the building elements operate on different MO disks. For example, a disk drive embodying the present invention could be used with the MO disks described herein, but could also be used with forming elements such as 80 mm, 90 mm, or 120 mm in diameter.

The disk drive 700 is one embodiment that includes two optical pickup / front-end electronics assemblies. In other embodiments,
It has only one optical pickup / front-end electronics assembly that accesses one side of the MO disk 710. In this embodiment, only one side of the disk is read or written at a time.

FIG. 7 shows a side view 800 of the disk drive of FIG. Disk drive 700
Recorded partially by upper cover 802, lower cover 804, and printed circuit board (PCB) assembly 808. The objective lens 810 of the assembly 716a is shown. Assemblies 716a and 716b are identical or functionally equivalent. Magnetic head and suspension 818 is shown for assembly 716b. In this embodiment, the magnetic head is designed as a magnetic field modulation head. Magnetic field modulation techniques are known in the art. Coarse carriage coil 814 is shown for assembly 716b. Spindle motor 816 is shown engaged with disk 812. Reference numeral 806 identifies the spindle motor in the disconnected position. Spindle motor 708
Is disconnected when the disk 812 is inserted or removed. The spindle motor 708 is connected to the MO disk 71
0, then move upwards to
Engage with.

FIG. 8 is a diagram showing an end surface 900 of the disk drive 700. End view 900 associates one magnetic head / suspension assembly 902 and objective lens 904. In this embodiment, the magnetic head / suspension assembly 902 is mounted on the coarse actuator body and not on the focus actuator.

An upper cover 906, a lower cover 912, and a PCB assembly 908 are also shown. An optical pickup / front-end electronics assembly 916 is shown on either side of the MO disk 910. A carriage coil 914 is shown for one assembly 916. In this embodiment, dimension 9
24, that is, the thickness of the MO disk 910 is 0.6 to
2.4 mm. In this embodiment, dimension 918 is 5
mm, dimension 922 is 10 mm, dimension 920 is 41.3 m
m.

The illustrated embodiment shows a single disk drive.
Perform parallel or redundant data processing within the drive. The optical pickup / front-end electronics assembly 716 of FIG. 6 is operated by independent actuators, and the input data stream is split into two assemblies and read and / or read separately on either side of the MO disk 710. Or, writing is performed. Thus, the user chooses to use parallel access to increase throughput or reduce access time. Alternatively, the user may choose to redundantly access both sides of the MO disk 710 to make a backup copy of the data. Choosing the parallel access mode allows client devices executing the command queue to process more quickly because commands in the queue can be executed smoothly if they are not of the same type. For example,
A write operation can be performed on one side of the MO disk 710, while a read operation can be performed on the opposite side of the MO disk 710.

The illustrated embodiment increases the data density, accesses the two data recording surfaces simultaneously and separately,
Perform MO recording using far-field techniques with the ability to overwrite directly. Other embodiments include an optical pickup / front-end electronics assembly in one
Since only one is included, the two data recording surfaces are not accessed simultaneously and separately.

The specific embodiment of the present invention has been described. For example, the illustrated embodiment includes an MO disk of a particular forming element, and a disk drive integrated with the optics and linear actuator. However, one of ordinary skill in the art can make modifications and changes to the particular embodiment illustrated without departing from the spirit and scope of the invention as set forth in the appended claims.

[Brief description of the drawings]

FIG. 1 illustrates a prior art magneto-optical (MO) data recording and retrieval system.

FIG. 2 is a diagram showing a conventional MO data recording and retrieval system.

FIG. 3 is a diagram showing a conventional MO data recording and retrieval system.

FIG. 4 is a diagram showing an MO data recording and retrieval system and an MO disk according to an embodiment of the present invention.

FIG. 5 illustrates a magnetic head suspension assembly according to one embodiment.

FIG. 6 is a top view of the MO drive according to one embodiment.

FIG. 7 is a partial side view of the MO drive of FIG. 6;

FIG. 8 is a partial end view of the MO drive of FIG. 6;

[Explanation of symbols]

 400 MO Data recording and retrieval system 402a Parallel laser light beam 402b Parallel laser light beam 404a Slider 404b Slider 406a Floating height 408a Overcoat layer 408b Overcoat layer 410a Recording layer 410b Recording layer 412 Central substrate 414a Objective lens 414b Objective lens 416a Light Channel 416b Optical channel 418a Magnetic recording head 418b Magnetic recording head 420 MO disk

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 11/105 501 G11B 11/105 501Z 536 536C 546 546F

Claims (15)

[Claims] 1. A substrate, a magneto-optical recording layer applied on the substrate, and a thickness of 25 nm to 20 nm applied on the recording layer.
An overcoat layer in the range of 0 microns, wherein data is recorded on the magneto-optical disk and read from the magneto-optical disk using laser light incident on the overcoat layer. 2. The magneto-optical disk according to claim 1, wherein the overcoat layer is dried so that the surface of the overcoat layer can be wiped. 3. The method of claim 1, wherein the overcoat layer is made of a material having a protective property and a thickness sufficient to allow manual handling of the magneto-optical disk without damaging data recorded on the magneto-optical disk. Item 2. A magneto-optical disk according to item 1. 4. The magneto-optical disk of claim 1, wherein the coating comprises silicon nitride applied by a sputtering process. 5. An overcoat layer comprising: a silicon nitride layer applied by sputtering over the recording layer; and an acrylic ultraviolet (U) layer applied over the silicon nitride layer by spin coating, the thicker than the silicon nitride layer.
2. The magneto-optical disk according to claim 1, further comprising V) a resin layer. 6. The magnet of claim 1, wherein the overcoat layer includes a first underlayer applied using a sputtering process, and a second underlayer adhered to the first underlayer and made of a transparent material. Optical disc. 7. The magnet according to claim 1, wherein the overcoat layer comprises a first underlayer applied using a sputtering process, and a second underlayer laminated to the first underlayer and made of a transparent material. Optical disc. 8. The magneto-optical disk according to claim 6, wherein the transparent material is polycarbonate. 9. The magneto-optical disk according to claim 7, wherein the transparent material is polycarbonate. 10. A disk having a plurality of protrusions on its surface,
2. The method of claim 1, wherein the maximum protrusion height above the surface is 2 microns.
2. The magneto-optical disk according to claim 1. 11. A magneto-optical disk for use in a magneto-optical drive having a floating magnetic head, comprising: a central substrate; a first magneto-optical recording layer applied on a first surface of the central substrate; A first overcoat layer applied over the one recording layer, wherein the first overcoat layer has a thickness in the range of 25 nanometers to 200 microns. 12. The method according to claim 1, wherein the second substrate has a second surface.
A second magneto-optical recording layer; and a second overcoat layer applied over the second recording layer, wherein the second overcoat layer has a thickness in the range of 25 nanometers to 200 microns. Claim 1 having
2. The magneto-optical disk according to 1. 13. Using a laser beam incident on each of the first overcoat layer and the second overcoat layer, information is recorded on and read from the first and second recording layers. 13. The magneto-optical disk according to claim 12, wherein the magneto-optical disk is used. 14. The first overcoat layer includes a groove that spirals in a first direction from the center of the magneto-optical disk, and the second overcoat layer includes a second groove from the center of the magneto-optical disk. 14. The magneto-optical disk according to claim 13, comprising a groove that spirals in the direction of. 15. The magneto-optical disk according to claim 13, wherein the first overcoat layer and the second overcoat layer include grooves that spiral in the same direction from the center of the magneto-optical disk.