JPH08306095A - Recording and reproducing device and method - Google Patents

Abstract

PURPOSE: To provide a device and a method for recording and reproducing which allow a high density of recording exceeding the limit of conventional optical recording density by utilizing the high resolution given by the scanning type probe microscope technique. CONSTITUTION: The recording medium formed on a substrate 21 is constituted by a first recording layer, magnetic recording layer 22, which opposes a probe 6 and a second recording layer, electrostatic capacity type recording layer 23, which is situated beneath the first recording layer. The second recording layer 23 records and reproduces information irrespective of the first recording layer 22 using a recording and reproducing principle different from that of the first recording layer 22 to conduct tracking control of the probe 6 based on the servo signals reproduced independent of the data signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high density recording / reproducing apparatus and a recording / reproducing method including a probe recording system to which a scanning probe microscope technique is applied.

[0002]

2. Description of the Related Art An optical recording / reproducing apparatus is excellent in durability and reliability because recording / reproducing can be performed at a relatively high density and recording / reproducing can be performed in a non-contact manner. . However, in such a conventional optical recording / reproducing, there is a physical limit that the spot size for converging light cannot be less than a fraction of the wavelength of light,
There is a limit to high density.

On the other hand, the scanning probe microscope technique, in which the probe is traced to the sample at a distance of atomic order or nanometer unit, is a technique for observing a fine region far exceeding the above-mentioned light spot size. Not only the technology but also the possibility as a technology for processing or manipulating the sample surface with resolution of atomic or molecular order, and a technology for recording / reproducing information in nanometer unit on the sample surface are attracting attention.

Here, an atomic force microscope (AF) which is one of the deep scanning probe microscopes (SPM) related to the present invention.
The principle of M) is briefly described as follows. In general, forces such as Van der Waals force and Coulomb force act between material surfaces. The AFM detects the local force that acts when a probe provided on a minute cantilever approaches the sample surface as the deflection of the cantilever, and the distance between the probe and the sample is kept so as to keep this force constant. The sample is scanned along the surface of the sample while controlling, and this control amount is imaged as a sample surface image.

Although this SPM is being established as a technique for observing a specific minute region on the sample surface with high resolution, in order to apply this to the recording / reproducing technique, the probe can be operated at high speed over a wide sample surface. Moreover, a technology for highly accurate positioning control is required.

As a needle positioning method in a recording / reproducing system using a needle, a guide groove for the needle is provided on the surface of the disk like a pure mechanical disk phonograph, and the needle is gently guided in the guide groove as the disk rotates. There is something that can be traced mechanically. This trace method has also been adopted as a video disk recording method in which a recording signal of unevenness recorded in a V groove is detected as a difference in electrostatic capacitance between a recording medium and an electrode attached to a reproducing needle. Further, one of the tracing methods of electrostatic video discs using a needle is that there is no guide groove on the disc, and a pilot signal is recorded separately from the recording signal for the signal, thereby performing tracking control.

As an example of high-density recording and reproduction with the probe using the AFM, a bullet (RC Barret)
t) et al. are Ultra Microscopy (Ultrami)
42) (44) (1992) 262-2
67, a dielectric film on a conductor or semiconductor substrate (specifically, a nitride film (nit) on a silicon substrate.
Ride) and an oxide film (oxide) NOS
(Structure) as a recording medium, a voltage is applied to the conductor probe of the AFM cantilever to record charge dots on the interface, and a change in the capacitance of the NOS structure due to this is detected and reproduced. . Furthermore, in this paper, an idea is to use a grating on the surface of a dielectric film (nitride film) to read information by detecting the capacitance with a probe, and to use the surface irregularity information obtained by AFM for tracking. Is stated.

Further, in a hard disk drive which is a magnetic recording / reproducing apparatus, a servo surface servo method in which one surface of the disk is a recording surface dedicated to a servo signal and a data surface servo method in which a servo signal is arranged on a part of a data surface are used. Has been done.

[0009]

However, in applying the SPM to the recording / reproducing apparatus, the method described in the above-mentioned conventional example is not sufficient for controlling the position of the probe at high speed and with high accuracy over a wide sample surface. Is.

The term "probe" as used herein refers to the side surfaces of various probes (insulators, semiconductors, conductors, magnetic substances, etc.) in a scanning probe microscope, and the needles of insulators used in electrostatic capacity type video disks. Information is recorded and / or reproduced on a minute portion of the medium by approaching or approaching the surface of a recording medium such as a magnetic head having a part of an electrode, a magnetic head used for magnetic recording, for example, a single-pole magnetic head used for perpendicular magnetic recording. It is a generic term for things that do.

As described in the conventional example, there is an idea that a grating is provided on the surface of the recording medium and this unevenness information obtained by the AFM is used for tracking.
No specific method for obtaining the error signal including the direction to be controlled is disclosed. Also, in the case of forming irregularities that become tracking signals in advance on the recording medium, after manufacturing this medium, mount the movement mechanism of the probe and the recording medium, or mount the exchangeable recording medium on the device that assembled this movement mechanism. Therefore, there is a drawback that a large error occurs between the tracking signal train and the movement trajectory of the probe.

On the other hand, in the hard disk drive of the magnetic recording / reproducing apparatus, since the servo signal is recorded after the disk drive is assembled, the above-mentioned error is greatly reduced, but the servo surface servo adopted in the hard disk drive. In order to apply the method to the ultra-high-density recording / reproducing apparatus aimed at by the present invention, the magnetic head for recording / reproducing a servo signal and the magnetic head for recording / reproducing a data signal are widely separated from each other. During this time, the mechanism portion is largely deviated due to thermal expansion, and tracking by this method is practically impossible.

Further, as in the data surface servo system in a hard disk drive or the pilot signal system in an electrostatic video disk, there is a system in which a pilot signal is recorded on the data surface separately from the data signal and tracking control is performed by this. However, this method has a drawback that the recording density and the recording / reproducing speed are reduced by this amount because an extra pilot signal is recorded.

As one type of data surface servo system in a hard disk, there is an embedded servo system in which a recording layer is divided into two magnetic recording layers and a data signal and a servo signal are frequency-separated and recorded. In this case as well, the data recording density is compressed due to frequency separation, and since the two recording layers are magnetic recording layers of the same recording / reproducing principle, if the S / N of the servo signal decreases due to repeated recording / reproducing There was a drawback that servo control became impossible.

In view of these problems of the conventional recording / reproducing apparatus, it is an object of the present invention to solve these problems and provide a recording / reproducing apparatus and a recording / reproducing method capable of high density recording.

[0016]

A recording / reproducing apparatus of the present invention positions a recording / reproducing or recording / reproducing separated type probe with respect to a recording medium, and the probe is relatively close to a recording surface of the recording medium. An apparatus for recording or reproducing information on this recording medium by bringing it into contact with the recording medium, comprising: a first recording layer facing the probe; and a second recording layer located below the first recording layer. Then, information is recorded / reproduced on / from the first recording layer by the probe and information is recorded / reproduced on / from the second recording layer independently of the first recording layer by a recording / reproducing principle different from that of the first recording layer. , Tracking control of the probe is performed by moving the probe in a direction orthogonal to the direction of the recorded information sequence of the data signal recorded in the recording layer based on a servo signal reproduced independently of the data signal. It is provided with a control means that.

Further, in the recording / reproducing apparatus of the present invention, information is magnetically recorded by causing a coil current to flow through a probe whose first recording layer is a magnetic probe type, a single magnetic pole type or an inductance type magnetic head for excitation. A magnetic recording layer for reproducing information by the magnetic head or a magnetic resistance type magnetic head or a magnetic impedance type magnetic head, wherein the second recording layer has a capacitance by applying a voltage to a probe made of a conductor or a semiconductor electrode needle. This is a capacitance type recording layer for recording information by causing a change and detecting the capacitance change by the probe to reproduce the information.

Further, in the recording / reproducing apparatus of the present invention, by applying a voltage to a probe whose recording layer is composed of a conductor or a semiconductor electrode needle, a capacitance change is caused to record information, and the capacitance is recorded by the probe. A capacitance type recording layer that detects a change and reproduces information, and a second recording layer is excited by applying a coil current to a probe formed of a magnetic probe type, single magnetic pole type or inductance type magnetic head. A magnetic recording layer for magnetically recording information and reproducing the information by the magnetic head or the magnetic resistance type or magnetic impedance type magnetic head.

Further, in the recording / reproducing apparatus of the present invention, information is recorded by causing a capacitance change by applying a voltage to a probe whose first recording layer is a conductor or a semiconductor electrode needle, and by the probe, An electrostatic capacitance type recording layer that reproduces information by detecting a change in electrostatic capacitance, and a second recording layer is excited by applying a coil current to a probe formed of a magnetic probe type, single magnetic pole type or inductance type magnetic head. Or a magneto-optical recording layer for magnetically recording information by condensing and heating with light while applying a bias magnetic field and reproducing the information by Kerr effect or Faraday effect of magneto-optical recording.

Further, in the recording / reproducing apparatus of the present invention, by applying a voltage to a probe whose first recording layer is a conductor or a semiconductor electrode needle, a change in conductivity is caused to record information, and the probe is used for conducting. The recording layer is a conductive control type recording layer that reproduces information by detecting a change in the recording property, and the second recording layer is a magnetic recording layer or a magneto-optical recording layer.

Further, it is preferable that the probe for reproducing the data signal recorded on the first recording layer and the probe for reproducing the servo signal recorded on the second recording layer are constituted by the same probe. It is preferable that a probe for recording a data signal on the first recording layer and a probe for recording a servo signal on the second recording layer are arranged close to each other to have an integrated structure, and further, the surface of the first recording layer is lubricated. It is preferable to provide layers.

Further, when the magnetic recording layer is formed on the capacitance type recording layer, the magnetic recording layer comprises a metal oxide magnetic material such as barium ferrite or a metal magnetic material dispersed in an insulating matrix. Preferably.

Further, the magnetic recording layer of the present invention is a perpendicular magnetic recording film, and it is preferable to provide a magnetic flux returning soft magnetic layer in this magnetic recording layer or below the second recording layer.
Further, the capacitance type recording layer of the present invention is preferably a dielectric layer formed on a semiconductor via an oxide film or a ferroelectric layer formed on the semiconductor.

[0024]

In the recording / reproducing apparatus of the present invention, the recording medium is composed of the first recording layer facing the probe and the second recording layer located below this recording layer. The second recording layer has the first recording layer. Since the information is recorded and reproduced independently of the first recording layer by the recording and reproduction principle different from that of the recording layer, the servo signal and the data signal are recorded and reproduced independently. Based on the servo signal reproduced independently of the data signal, the probe can be moved in a direction orthogonal to the direction of the recorded information sequence of the data signal to perform tracking control.

Since the servo signal can be directly recorded / reproduced on / from the recording medium, this servo signal can be recorded after assembling the motion mechanism of the probe and the recording medium, and the error between the motion locus of the probe and the servo signal train can be eliminated. It can be extremely small. Furthermore, since servo signals and data signals can be recorded and reproduced independently, the probe for servo signal recording and the probe for data signal recording can be the same probe,
They can be placed very close to each other without any misalignment between them due to thermal expansion. Further, since the servo signal and the data signal can be independently recorded / reproduced by different recording / reproduction principles, the S / N of the servo signal reproduction does not decrease with the repeated recording / reproduction of the data signal.

Further, in the recording / reproducing apparatus of the present invention, the first recording layer is a magnetic recording layer and the second recording layer is a capacitance type recording layer. That is, information is magnetically recorded on the first recording layer by causing a coil current to flow through a probe composed of a magnetic probe type, a single magnetic pole type or an inductance type magnetic head to excite the information, and the magnetic head, the magnetic resistance type or the magnetic impedance is recorded. The information is reproduced by the magnetic head of the mold. Magnetic recording allows information to be recorded / reproduced at high speed, is suitable for repeated recording / reproduction, and is excellent in storing this information for a long period of time. In the second recording layer, information is recorded by causing a capacitance change by applying a voltage to a probe made of a conductor or a semiconductor electrode needle, and the probe detects the capacitance change to reproduce the information. . In the electrostatic capacity type recording, since recording and reproduction can be performed even if there is a space between the probe and the recording layer, this recording layer can be arranged below the magnetic recording layer. Since there is a space loss in recording and reproducing in both magnetic recording and electrostatic capacity type recording, a data signal is recorded in the first recording layer facing the probe and a band lower than the data signal is recorded in the second recording layer below the first recording layer. It is preferable to record the servo signal which requires the signal of.

Further, in the recording / reproducing apparatus of the present invention, the first recording layer is a capacitance type recording layer and the second recording layer is a magnetic recording layer. That is, in the first recording layer, information is recorded by causing a capacitance change by applying a voltage to a probe formed of a conductor or a semiconductor electrode needle, and the probe detects the capacitance change to reproduce the information. To do. Capacitance type recording can record / reproduce information at high speed, and the repeated recording / reproduction and storage life, which have been problems in the past, have been improved by the progress of medium technology and can be put to practical use. Information is magnetically recorded on the second recording layer by causing a coil current to flow through a probe composed of a magnetic probe type, a single magnetic pole type or an inductance type magnetic head for magnetic recording, and the magnetic head, the magnetic resistance type or the magnetic impedance type is recorded. The information is reproduced by the magnetic head of. Since this magnetic recording can be recorded and reproduced even if there is a space between the probe and the recording layer,
This recording layer can be disposed below the capacitance type recording layer. Since there is space loss in recording / reproducing both electrostatic capacity type recording and magnetic recording, the first type facing the probe
It is preferable that a data signal is recorded on the recording layer of No. 2 and a servo signal that requires a signal of a band lower than the data signal is recorded on the second recording layer thereunder.

Further, in the recording / reproducing apparatus of the present invention, the first recording layer is a capacitance type recording layer and the second recording layer is a magneto-optical recording layer. That is, in the first recording layer, information is recorded by causing a capacitance change by applying a voltage to a probe formed of a conductor or a semiconductor electrode needle, and the probe detects the capacitance change to reproduce the information. To do. Second
In the recording layer, information is magnetically recorded by applying a coil current to a probe composed of a magnetic probe type, a single magnetic pole type or an inductance type magnetic head to excite it, or concentrating and heating with light while applying a bias magnetic field. Information is reproduced by the Kerr effect or Faraday effect of the magneto-optical recording layer. The operation is similar to that described above.

Further, in the recording / reproducing apparatus of the present invention, the first recording layer is a conductivity control type recording layer, and the second recording layer is a magnetic recording layer or a magneto-optical recording layer. In other words, the first recording layer records information by applying a voltage to a probe made of a conductor or a semiconductor electrode needle to change the conductivity, and the probe detects the change in the conductivity to reproduce the information. The conductivity control type recording is 10n as described later.
Information can be recorded / reproduced in a minute area of the order of m, and ultra-high density recording / reproduction is possible. The second recording layer is a magnetic recording layer or a magneto-optical recording layer. The operation is similar to that described above.

Further, in the recording / reproducing apparatus of the present invention, the probe for reproducing the data signal recorded in the first recording layer and the probe for reproducing the servo signal recorded in the second recording layer are the same probe. With the preferable configuration, a deviation due to thermal expansion between the two probes does not occur in principle during reproduction, so that highly accurate tracking control can be performed.

Further, in the recording / reproducing apparatus of the present invention, a probe for recording a data signal on the first recording layer and a probe for recording a servo signal on the second recording layer are arranged in close proximity to each other and are preferably integrated. By setting the above, it is possible to minimize the deviation due to thermal expansion between both probes during recording, and it is possible to reduce the position error of the servo signal with respect to the data signal. Accordingly, highly accurate tracking control can be performed during reproduction.

Further, the recording / reproducing apparatus of the present invention has a preferable structure in which the lubricating layer is provided on the surface of the first recording layer, thereby suppressing the progress of wear of the probe which moves close to or in contact with the surface of the recording medium and moves relatively. it can.

Further, in the recording / reproducing apparatus of the present invention, when the first recording layer is a magnetic recording layer and the second recording layer is a capacitance type recording layer, this magnetic recording layer is made of barium ferrite or the like. Information can be efficiently recorded / reproduced on / from the second recording layer by adopting a preferable structure composed of a metal oxide magnetic material or a metal magnetic material dispersed in an insulating matrix.

Further, in the recording / reproducing apparatus of the present invention, the magnetic recording layer is a perpendicular magnetic recording film, and a soft magnetic layer for magnetic flux return is provided in the magnetic recording layer or below the second recording layer. High-density recording / reproducing can be performed on the magnetic recording layer, and information can be efficiently recorded / reproducing on the magnetic recording layer.

Further, in the recording / reproducing apparatus of the present invention, the capacitance type recording layer is preferably composed of a dielectric layer formed on a semiconductor via an oxide film or a ferroelectric layer formed on the semiconductor. High-density recording and reproduction can be performed on the electrostatic capacity type recording layer.

[0036]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 shows a perspective view of a recording / reproducing apparatus when the present invention is applied to a rotary disk type recording / reproducing apparatus as an embodiment of the present invention. The configuration will be described below together with the operation.

While rotating the recording medium disk 1 in the direction of arrow 2, the holder 3 of the probe is positioned by the linear slide 5 in the radial direction 4 of the disk. The probe 6 at the tip of the probe holder 3 is brought close to or in contact with this recording surface to perform recording or reproduction on this recording medium. Tracking control of the probe 6 is performed by moving the probe 6 in the direction 8 orthogonal to the direction 7 of the recorded information sequence to be recorded.

As a method for keeping the force acting between the probe and the recording medium substantially constant, an example in which an optical lever method used in an atomic force microscope (AFM) is applied is shown here. The light reflecting surface 9 of the holder 3 of the probe is irradiated with the laser beam from the laser diode 10, and the reflected light is received by the two-split photodetector 11. The probe holder 3 is constructed so as to bend due to the force acting between the probe and the recording surface,
The photodetector 11 can detect the change in the amount of received light according to this deflection, and thus the force acting on both can be detected.
According to this detection force, the probe is moved by the triaxial piezoelectric actuator 12 along the radial direction 13 of the recording surface so that this force becomes constant. This control is equivalent to focusing control in optical recording, and it is not always necessary to follow minute irregularities on the recording surface, and the response frequency is limited so as to follow surface wobbling due to rotation of the disk.

Further, the recording medium disc is as shown in FIG.
As shown in FIG. 2A, FIG. 3A, or FIG. 4A, the first recording layer (FIG.
2, FIG. 2 (a) 23, FIG. 3 (a) 23, FIG. 4 (a) 3
5) and the second recording layer (FIG. 1 (a) 23, FIG. 2 (a) 22, FIG. 3 (a) 31, FIG.
(A) has a two-layer structure composed of 22 or 31),
Information is recorded and reproduced by the probe 6 on the first recording layer,
Information is recorded / reproduced on the second recording layer independently of the first recording layer by a recording / reproducing principle different from that of the first recording layer. Based on the servo signal reproduced independently of the data signal from both of these recording layers, the probe 6 is moved in the direction 8 orthogonal to the direction 7 of the recorded information sequence of the data signal recorded in the recording layer, and the slide 5 or triaxial By moving the piezoelectric actuator 12, the feedback control is performed so that the probe 6 traces the recorded information sequence.

Since the servo signal can be directly recorded / reproduced on / from the recording medium, this servo signal can be recorded after the disk drive described in FIG. 5 is assembled, and the error between the motion locus of the probe 6 and the servo signal sequence 7 can be recorded. Can be extremely reduced. Box 1 for the whole device if necessary
Cover with 4 and shut off from the outside atmosphere through a filter, or contain in dry gas or reduced pressure gas.

FIG. 1 shows an example of the structure of the recording medium of the present invention, in which the first recording layer is a magnetic recording layer 22 and the second recording layer is a capacitance type recording layer 23. These recording layers are formed on the substrate 21, and the lubricating layer 24 is formed on the outermost layer of the recording layers. Information is magnetically recorded on the first recording layer 22 by causing a coil current to flow through a probe formed of a magnetic probe type, a single magnetic pole type or an inductance type magnetic head to excite the magnetic recording medium, the magnetic resistance type or the magnetic impedance type. The information is reproduced by the magnetic head of the mold. Magnetic recording can record and reproduce information at high speed, is suitable for repeated recording and reproduction, and is excellent for storing this information for a long time, and is suitable for recording data signals. Information is recorded on the second recording layer 23 by applying a voltage to a probe made of a conductor or a semiconductor electrode needle to change the capacitance, and the probe detects the change in the capacitance to reproduce the information. To do. Capacitance type recording can record and reproduce even if there is a space between the probe and the recording layer, and this recording layer is arranged below the magnetic recording layer to record and reproduce the servo signal which requires only a low band signal.

The magnetic recording / reproducing can be independently performed regardless of the voltage application in the electrostatic capacity type recording or the presence or absence of the electrostatic capacity recording layer. The electrostatic capacity type recording / reproducing can also be configured as described above since the recording / reproducing can be performed independently without relatively affecting the magnetic field application in magnetic recording or the presence or absence of the magnetic recording layer. Further, since the servo signal and the data signal can be independently recorded / reproduced by different recording / reproduction principles, the S / N of the servo signal reproduction does not decrease with the repeated recording / reproduction of the data signal.

FIGS. 1B and 1C show two different embodiments of the recording medium having the structure of FIG.
FIG. 2B shows a magnetic recording layer, which is the first recording layer, in addition to two.
The magnetic recording layer 22 has a layered structure including a perpendicular magnetic recording film 25 and a magnetic flux returning soft magnetic layer 26.
With such a configuration, high density recording / reproducing can be performed on the magnetic recording layer, and information can be efficiently recorded / reproducing on the magnetic recording layer. By using a metal oxide magnetic material such as barium ferrite or a metal magnetic material dispersed in an insulating matrix as the perpendicular magnetic recording layer 25, information can be efficiently recorded / reproduced on / from the second recording layer. . As the magnetic flux returning soft magnetic layer 26, a metal oxide soft magnetic material or a metal soft magnetic material dispersed in an insulating matrix is suitable.

The capacitance type recording layer 23 is, for example, on a p-type or n-type silicon substrate 21 which is a semiconductor material,
Silicon nitride film 28 through thin silicon oxide film 27
When a voltage is applied to the probe 6, electrons directly under the probe of the silicon substrate 21 are made to pass (tunnel) through the silicon oxide film (tunnel oxide film) 27 by applying a voltage to the probe 6, and the oxide film interface of the silicon nitride film 28 is formed. Information is recorded by trapping in the. An electron vacancy layer is formed on the silicon substrate immediately below where the electrons are trapped, and a change in the capacitance due to the hole layer can be detected by the probe 6.

In FIG. 6C, the magnetic recording layer which is the first recording layer is the perpendicular recording film 22, and the magnetic flux returning soft magnetic layer 26 is the second recording layer 23 which is the capacitance type recording. It is configured in the lower layer 26 of the layer. With such a structure, the perpendicular magnetic recording of the first layer can be performed efficiently with high density, and the capacitance type recording of the second layer can reduce the film thickness of the first layer, resulting in space loss. It is possible to reduce the influence and stably record and reproduce.

FIG. 2 shows another example of the structure of the recording medium of the present invention, in which the first recording layer is the capacitance type recording layer 23 and the second recording layer is the magnetic recording layer 22. Is.

In FIG. 2B, each layer has a structure similar to that of FIG. 1B, and therefore detailed description thereof is omitted. FIG.
The difference from (b) is that the p-type or n-type silicon layer 29, which is the semiconductor layer of the capacitance type recording layer 23, is a thin film forming layer. In this case, the substrate 21 does not have to be a silicon substrate, but a glass substrate, a graphite substrate, or the like can be used, and there is an advantage that an optimal substrate can be selected. The configuration of FIG. 2 is a configuration in which the first recording layer and the second recording layer are replaced with the configuration of FIG. As described above in the description of the operation of the present invention, the structure of this recording medium may be a practical structure.

FIG. 3 shows another example of the structure of the recording medium of the present invention. The first recording layer is the electrostatic capacity type recording layer 23, and the second recording layer is the second type.
This is a case where the recording layer of is the magneto-optical recording layer 31.

FIG. 3B shows the specific structure of each layer, and the structure of the capacitance type recording layer of the first recording layer is the same as the structure shown in FIG. As the magneto-optical recording layer 31 of the second recording layer, for example, TbFeCo or NdFeCo having a large Kerr effect or Faraday effect, an artificial lattice film in which Co and Pt are alternately laminated is used.

In order to record information on the magneto-optical recording layer of the second recording layer, while collecting and heating with light, a coil current is applied to a probe formed of a magnetic probe type, single magnetic pole type or inductance type magnetic head. Information is magnetically recorded by flowing and exciting or by converging and heating with light while applying a bias magnetic field. The reproduction is performed by detecting the Kerr effect or Faraday effect of the magneto-optical recording layer.

The recording bit of the magneto-optical recording layer has a limit to miniaturization due to the diffraction limit of light.
D. Terris) et al. Applied Physics Letter (App
L.Phys.Lett.) vol.65 (4) .25 (1994) p.388 describes a miniaturization method using a solid immersion lens. FIG.
As shown in (b), the recording / reproducing light beam 34 is focused on the recording layer 31 through the collimator lens 33 and the solid immersion lens 32. The focused spot size is represented by (spot diameter) = λ / 2n, where λ is the wavelength of light and n is the refractive index of the medium between the objective lens and the focused spot. Air layer (refractive index n = 1) in front of the objective lens
In comparison with the normal case through the solid immersion lens serving as the objective lens and the first recording layer serving as the medium between the converging spot, the refractive index can be increased to about 1.5 to 2, Therefore, the spot diameter can be reduced.

Optical recording of such a second layer (magneto-optical recording)
By miniaturizing the recording bits, the minute recording of the servo signal corresponding to the size of the recording bits of the data signal to be recorded in the first layer can be performed.

FIG. 4 shows another example of the structure of the recording medium of the present invention. The first recording layer is the conductivity control type recording layer 35, and the second recording layer is the magnetic recording layer 22 or the magneto-optical recording layer. This is the case of setting 31. That is, the first recording layer records information by applying a voltage to a probe made of a conductor or a semiconductor electrode needle to cause a change in conductivity, and the probe detects the change in conductivity to reproduce the information. Conductivity control type recording is, for example, amorphous GeSbTe.
It is composed of layers, and by applying a voltage with a probe, information can be recorded / reproduced in a minute region of the order of 10 nm, and recording / reproduction with an extremely high density can be performed. The second recording layer is a magnetic recording layer or a magneto-optical recording layer. The operation of the second layer is the same as described above.

In the case of the medium structure shown in FIG. 1 or 2, a probe made of a metal magnetic material or a probe having electrodes formed on magnetic needles is used as a probe, and a data signal recorded in the first recording layer is recorded. By using the same probe as the probe for reproducing and the probe for reproducing the servo signal recorded on the second recording layer, it is possible to prevent a deviation due to thermal expansion between both probes at the time of reproducing, and highly accurate tracking control. Can be applied.

FIG. 6 shows the data signal 41 recorded by the probe 43 and the servo signal 42 recorded by the two probes 44 arranged on both sides of the probe 43. The servo signal 42 is recorded in different patterns to the left and right with respect to the center line of the data signal sequence, and an error signal including discrimination in the tracking error direction can be obtained during reproduction.

As shown in FIG. 7, a probe 45 for recording a data signal on the first recording layer and a probe 46, 47 for recording a servo signal on the second recording layer are arranged close to each other and integrated. By setting the above, it is possible to minimize the deviation due to thermal expansion between both probes at the time of recording, and it is possible to reduce the positional error of the servo signal 42 with respect to the data signal 41. Accordingly, highly accurate tracking control can be performed during reproduction.

Here, the recording of the servo signal may be performed simultaneously with the recording of the data signal, or only the servo signal is recorded in advance and the formatting is performed, and then the data signal is recorded while reproducing the servo signal. Good.

Although specific examples of the recording method applied to the first recording layer and the second recording layer of the present invention have been described with reference to claims 3 to 6, optical recording not particularly mentioned above. The present invention is also effective in combination with a system or a recording system in which surface irregularities are formed thermomechanically.

In all of the above-mentioned examples, a lubricating layer is provided on the outermost surface of the recording layer, which is necessary for recording and reproducing by bringing the probe close to or in contact with the recording medium. However, on the other hand, it is desirable to minimize the film thickness of this layer in order to avoid the space loss that hinders the recording of ultra-high density. For example, a surface-modified ultrathin film such as a water-repellent monomolecular film covalently bonded to the surface of the recording medium is desirable.

[0060]

As described above, the present invention provides a recording / reproducing apparatus and a recording / reproducing servo system which breaks the limit of the recording density of the conventional optical system and enables the super-high density mass information recording. It has a great industrial value.

[Brief description of drawings]

1A to 1C are cross-sectional views of a recording medium in an embodiment of the present invention.

2A and 2B are cross-sectional views of a recording medium according to another embodiment of the present invention.

3A and 3B are cross-sectional views of a recording medium in another embodiment of the present invention.

4A and 4B are cross-sectional views of a recording medium according to another embodiment of the present invention.

FIG. 5 is a perspective view of a recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 6 is a plan view showing the arrangement of data signals and servo signals in one embodiment of the present invention.

FIG. 7 is a perspective view of an integrated probe showing an embodiment of the present invention.

[Explanation of symbols]

 1 recording medium disc 2a recording surface 2 recording medium disc rotation direction 3 probe holder 4 recording medium disc radial direction 5 linear slide 6 probe 7 recording information sequence direction 8 direction orthogonal to recording information sequence 9 light reflection Surface 10 Laser diode 11 Two-division photodetector 12 Triaxial piezoelectric actuator 13 Radial direction of recording surface 14 Box 21 Substrate 22 Magnetic recording layer 23 Capacitive recording layer 24 Lubricating layer 31 Magneto-optical recording layer 35 Conductivity control type recording Layer 41 Data signal 42 Servo signal 43-47 Probe

Front page continued (72) Inventor Shinichi Mizuguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Akio Murata 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Shoro Kuroe 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (12)

[Claims] 1. A recording / playback combined or recording / playback separation type probe is positioned with respect to a recording medium, and the probe is brought relatively close to or in contact with the recording surface of the recording medium to record information on the recording medium. A recording / reproducing apparatus for reproducing, wherein the recording medium comprises a first recording layer facing the probe, and a second recording layer located below the first recording layer. Information is recorded and reproduced by the probe, and information is recorded and reproduced on the second recording layer independently of the first recording layer by a recording and reproduction principle different from that of the first recording layer. Performs tracking control of the probe by moving the probe in the direction orthogonal to the direction of the recorded information sequence of the data signal recorded in the recording layer based on the servo signal reproduced independently. Recording reproducing apparatus characterized in that a control means. 2. A recording / reproducing or recording / reproducing separated type probe is positioned with respect to a recording medium, and the probe is brought relatively close to or in contact with the recording surface of the recording medium to record or reproduce information on the recording medium. The recording medium records and reproduces information on the first recording layer facing the probe with the probe, and the second recording layer located below the first recording layer has the above-mentioned information. Information is recorded / reproduced independently of the first recording layer by a recording / reproducing principle different from that of the first recording layer, and the probe is recorded in the recording layer based on a servo signal reproduced independently of the data signal. A recording / reproducing method, wherein tracking control of the probe is performed by moving the probe in a direction orthogonal to the direction of the recorded information sequence of the data signal. 3. A first recording layer magnetically records information by causing a coil current to flow through a probe formed of a magnetic probe type, single magnetic pole type or inductance type magnetic head to excite the information, thereby magnetically recording the information. Recording layer for reproducing information by a magnetic head of a magnetic type or a magnetic impedance type, and the second recording layer changes the electrostatic capacity by applying a voltage to a probe made of a conductor or a semiconductor electrode needle. 2. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing apparatus is an electrostatic capacity type recording layer for recording information, reproducing the information by detecting the electrostatic capacity change by the probe. 4. The first recording layer records voltage by applying a voltage to a probe having a conductor or a semiconductor electrode needle to record information, and the probe detects the capacitance change. Information is magnetically recorded by applying a coil current to a probe, which is a capacitance type recording layer for reproducing information and whose second recording layer is a magnetic probe type, a single magnetic pole type or an inductance type magnetic head, for excitation. ,
The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing apparatus is a magnetic recording layer for reproducing information by the magnetic head or a magnetic resistance type or magnetic impedance type magnetic head. 5. A voltage is applied to a probe whose first recording layer is a conductor or a semiconductor electrode needle to cause a capacitance change, thereby recording information, and detecting the capacitance change by the probe. This is a capacitance type recording layer for reproducing information, and while the second recording layer is focused and heated by light, a coil current is passed through a probe composed of a magnetic probe type, single magnetic pole type or inductance type magnetic head for excitation. 2. A magneto-optical recording layer for magnetically recording information by condensing and heating with light while applying a bias magnetic field, and reproducing information by the Kerr effect or Faraday effect. Recording / playback device. 6. The information is recorded by causing a change in conductivity by applying a voltage to a probe whose first recording layer is a conductor or a semiconductor electrode needle, and the change in conductivity is detected by the probe to record information. 2. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing apparatus is a conductive control type recording layer for reproducing the data, and the second recording layer is a magnetic recording layer or a magneto-optical recording layer. 7. A probe for reproducing a data signal recorded on a first recording layer and a probe for reproducing a servo signal recorded on a second recording layer are constituted by the same probe. 1. The recording / reproducing apparatus according to 1. 8. An integrated structure in which a probe for recording a data signal on the first recording layer and a probe for recording a servo signal on the second recording layer are arranged close to each other. Recording and reproducing device. 9. The recording / reproducing apparatus according to claim 1, wherein a lubricating layer is provided on the surface of the first recording layer. 10. The recording / reproducing apparatus according to claim 3, wherein the magnetic recording layer is made of a metal oxide magnetic material such as barium ferrite or a metal magnetic material dispersed in an insulating matrix. 11. The magnetic recording layer is a perpendicular magnetic recording film, and a soft magnetic layer for magnetic flux return is provided in the magnetic recording layer or below the second recording layer. The recording / reproducing apparatus according to any one of claims. 12. The capacitance type recording layer comprises a dielectric layer formed on a semiconductor via an oxide film or a ferroelectric layer formed on a semiconductor. The recording / reproducing apparatus as described in.