KR20030044315A - Method for high density optical recording, apparatus thereof - Google Patents

Abstract

PURPOSE: A high-density optical recording/reproducing method and system are provided to reproduce information from a disk with high recording density or record information in the disk and to effectively protect the surface of the disk. CONSTITUTION: An optical recording/reproducing method includes a step of preparing a contact face recording disk(10) whose recording layer(12) is formed being inclined to the contact face of the focus lens(20) on the basis of the center of the disk, and a step of inputting light irradiated from a light transmission and receiving unit to the recording layer of the contact face recording disk through the focus lens to record or reproduce information.

Description

High-density optical recording and reproducing method, the device {METHOD FOR HIGH DENSITY OPTICAL RECORDING, APPARATUS THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording and reproducing method and apparatus, and more particularly, to an optical recording and reproducing method and apparatus designed to modify a layered structure of a disc as a recording medium for high density recording and reproduction, and to be suitable for the structure.

In light of the trend of large-capacity information, new optical recording and reproducing methods are required to overcome the limitations of existing optical recording and reproducing methods.

An optical recording medium or a magneto-optical recording medium must have a small bit (or recording mark) size and a narrow track width to have a high density recording capacity. However, the limitation due to the difference in the layer structure of the recording medium including the protective layer, the recording layer, and the reflective layer and the condensing method, the diffraction of the spot size of the light condensed on the recording medium to form bits in the recording film of the recording medium. Due to limitations such as limitations, studies on optical recording and reproducing methods are actively being conducted to overcome such limitations.

The structure of a conventional far field optical recording and reproducing method is as shown in FIG. That is, the light irradiated from the transmitting / receiving part is focused using a focusing lens 1 having a numerical aperture (NA: Numerical Aperture) of about 0.5 to 0.6, and the focused light first passes through the substrate 2 and then the recording layer It takes the way to reach (3).

Thus, the reason why light is transmitted through the thick substrate 2 and reaches the recording layer 3 is because a protective layer made of a thick substrate is formed on the outer layer of the recording layer, whereby fingerprints, dust and other contaminants are formed. This is to prevent the recording layer from being damaged.

The recording density of the disc is determined by the size of the focused light, and the size of the light is determined by the wavelength? Of the light source and the numerical aperture NA of the lens used, in consideration of diffraction.

However, when the optical recording and reproducing of the signal using the disk of the above structure is taken, as shown in FIG. 1, the light reaches the recording layer 3 through the thick substrate 2. However, there is a limitation that a lens having a high refractive index, that is, a numerical value having a high numerical aperture cannot be used.

In addition, in order for the focus of the light focused through the focusing lens 1 to be formed in the recording layer 3, it is required to keep the focusing lens 1 and the recording layer 3 at a constant distance. ) Is difficult to take a smooth structure, so the focusing lens 1 cannot take a method of recording and reproducing a signal in contact with the surface of the substrate 2, that is, the surface of the disk. There is a need for a certain interval between them, which is another limitation in that a lens having a high numerical aperture cannot be used.

In order to solve the problem of the far field optical recording and reproducing method, an optical recording and reproducing method using a near field has recently been proposed as a method for increasing the recording density in a region where light diffraction does not occur. .

The principle of near field optical recording and reproducing is as follows. Light entering the lens at an angle greater than or equal to the critical angle is totally reflected when traveling from a dense refractive index to a small one. At this time, due to total reflection of light, light of very small intensity exists on the surface of the lens, which is called an evanescent wave or dissipation wave. Using this Evernet wave, the absolute limit of the resolution due to the diffraction phenomenon of light in the far-field can be achieved. The near field optical recording and reproducing optical system totally reflects the light in the lens to generate an Evernet wave on the surface of the lens, and records and plays back by coupling the Evernet wave and the recording medium.

2 is a configuration diagram briefly showing the configuration of a conventional near field optical recording and reproducing method.

As shown in the drawing, the conventional near field optical recording and reproducing method injects the light emitted from the transmitting / receiving unit into the focusing lens 5 having a very high numerical aperture through the objective lens 4, thereby generating an Evernet wave generated at the focus. A signal is recorded or reproduced by the coupling of the recording layer 3 formed on the surface of the disc.

However, in such a near-field optical recording / reproducing method, a focusing lens having a very high numerical aperture must be used, and in order for the focus of the lens to be formed on the recording layer of the disc, a structure in which the recording layer is formed on the surface of the disc is provided. The distance between the focusing lens and the disk surface is limited to several tens of nm, which is less than the wavelength of light.

Therefore, the space in which the protective layer can be formed outside the recording layer of the disc is very limited.

On the other hand, the focusing lens 5 reciprocates at very close intervals of about several tens of nm on a disk rotating at high speed to scan the track of the disk. When the data is recorded on the disk, The focus of the laser light is formed, which raises the temperature of the disk surface in contact with the focusing lens.

According to the experimental results, in the case of a magneto-optical disk, the temperature of the recording layer is raised to about 200 to 250 ° C, and in the case of a phase change disk, it is known to rise to about 600 ° C.

At this time, the temperature of the surface of the optical disk formed by the dielectric layer and the protective layer covering and protecting the recording layer also rises to 60 to 300 ° C., thus causing the following problems on the contact surface of the focusing lens in contact with the surface.

In other words, foreign matter adhering to the material or other surface constituting the surface of the disk is transferred to the contact surface of the focusing lens from the surface of the disk and adheres to it, and then the contact surface of the focusing lens is coated by the heat generated by the above-described causes. will be.

Since the focusing lens moves around the entire area of the disk for reproduction or recording of the disk, contaminants adhering to the surface of the disk are continuously transferred to the contact surface of the focusing lens, which is coated on the contact surface of the focusing lens by heat, The transmittance of the focusing lens is reduced, and the use of the optical recording / reproducing apparatus can be made impossible when it is continued for a long time.

There are many contaminants that cause this problem, and representative examples include substrate materials, hub materials, cartridge materials, materials constituting the surface of an optical disk such as a lubricating layer or a protective layer, materials constituting a human fingerprint, and the like. Dust and the like.

As a result of analyzing these pollutants, mainly carbon and fluorine compounds were found, and other sodium and silicon compounds were also detected.

As described above, although the role of the protective layer for protecting the recording layer of the disk from heat is further emphasized in the near field optical recording and reproducing method, the space for forming the protective layer is limited as described above. come.

The present invention solves the above problems, and provides an optical recording and reproducing method and apparatus of a more advanced configuration, which can effectively reproduce or record information from a disk having a high recording density and effectively protect the surface of the disk. Its purpose is to provide.

1 and 2 schematically show a configuration of a conventional optical recording and reproducing method,

1 is a configuration diagram showing the configuration of the far field method

2 is a configuration diagram showing the configuration of the near-field method

3 to 6 schematically show the configuration of the optical recording and reproducing method according to the present invention.

3 is a configuration diagram showing a configuration of the first embodiment

4 is a configuration diagram showing the configuration of the second embodiment;

5 is a configuration diagram showing a configuration of the third embodiment

6 and 7 show the structure of the optical recording and reproducing apparatus according to the present invention.

6 is a plan view showing the structure of the entire optical recording and reproducing apparatus;

7 is a configuration diagram schematically showing a configuration of an optical system

** Description of the symbols for the main parts of the drawings **

10 contact surface recording disk 11 substrate

12: recording layer 13: protective layer

20: focusing lens 21: the first focusing lens

22: second focusing lens 30: slider

31: air pressure generating unit 32: magnetic coil

34: reflecting means 40: transmitting and receiving part

The present invention provides an optical recording and reproducing method for recording or reproducing information by irradiating and injecting light from a transmitting / receiving unit through a focusing lens onto a rotating disk in order to achieve the object as described above, wherein the recording layer has a thickness of the disk. Providing a contact surface recording type disc formed at the contact surface side with said focusing lens with respect to a center; Recording or reproducing information by injecting the light irradiated from the transmitting / receiving unit onto the recording layer of the contact surface recording disc through the focusing lens; A high density optical recording and reproducing method including the above is provided.

Further, the focusing lens is preferably mounted on a slider which allows the track of the contact surface recording disk to be scanned while floating against the contact surface recording disk by air dynamic pressure.

Further, the depth of focus of the focusing lens is preferably located within the thickness of the recording layer of the contact surface recording type disk.

Further, it is preferable that the focusing lens has a higher flatness of the surface facing the contact surface recording type disk than the opposite side.

In addition, the focusing lens may be configured in plural to focus light as a layered structure.

Also, the optical recording and reproducing method according to the present invention comprises the steps of: forming a magnetic coil on the contact surface recording disk side facing surface of the slider; Reproducing or recording a signal on a recording layer of the contact surface recording disc by transmitting a signal to the magnetic coil; It is preferable to comprise.

On the other hand, the present invention is another means for achieving the object as described above, the transmission and reception portion for recording or reproducing information by irradiating and incident light, and the reciprocating rotation with respect to the surface of the disk mounted and rotated in the main body An installed swing arm, an actuator for providing a rotational driving force to the swing arm, a slider provided at an end of the swing arm, and a light converging part attached to the slider to focus light irradiated from the light transmitting and receiving part onto the disk. An optical recording and reproducing apparatus, comprising: the slider is provided to scan a track of the disk while floating against the disk by pneumatic pressure, wherein the disk has a recording layer with the slider about the center of the thickness thereof. And a contact surface recording type disc formed at the contact surface side with Comprising: a focusing lens, and presents a high-density optical recording and reproducing apparatus characterized in that by the incident light emitted from the transmitting light receiving record or reproduce information in the recording layer of the contact surface recordable disc.

Further, the focusing lens is preferably mounted so that its depth of focus is within the thickness of the recording layer of the contact surface recording disk.

Further, it is preferable that the focusing lens has a higher flatness of the surface facing the contact surface recording type disk than the opposite side.

In addition, the focusing lens may have a configuration in which a plurality of focusing lenses are mounted on the slider so that the optical axes coincide with each other.

In addition, the transmitting and receiving unit and the light irradiation unit for irradiating light; A beam splitter having an exploded surface for selectively reflecting the irradiated light; A collimating lens mounted to the light converging portion so as to coincide with the optical axis of the light reflected or transmitted by the beam splitter; Reflecting means mounted to reflect light transmitted through the collimating lens toward the light converging portion; Signal conversion means mounted on the opposite side of the light converging portion of the beam splitter; It is preferable to comprise.

The optical recording and reproducing apparatus according to the present invention further includes: a magnetic coil mounted on the contact surface recording disk side facing surface of the slider; Recording means for transmitting a signal to the magnetic coil; It is preferable to comprise.

Furthermore, it is effective that an air pressure generating portion is formed on the contact surface of the slider with the contact surface recording type disk.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

3 to 5 schematically show the structure of the optical recording / reproducing method according to the present invention, FIG. 3 is a block diagram showing the structure of the first embodiment, and FIG. 4 shows a structure of the second embodiment. 5 is a block diagram showing the configuration of the third embodiment.

As shown, the optical recording and reproducing method according to the present invention comprises the steps of: providing a contact surface recording type disc 10 in which the recording layer 12 is formed on the contact surface side with the focusing lens 20 with respect to the center of the disk thickness; Injecting light irradiated from a light-receiving unit (not shown) onto the recording layer of the contact surface recording type disk 10 through the focusing lens 20 to record or reproduce information; It is configured to include.

The recording density is determined by the size of the focused light, and the size of the light is determined by the wavelength? Of the light source and the numerical aperture NA of the lens used, in consideration of diffraction. According to the Rayleigh diffraction limit, the diameter D of the focused laser light is

D = 1.22 λ / NA

However, the practically available limit may be regarded as 0.61, which is a coefficient corresponding to a full width at half maximum of a laser light having a Gaussian intensity distribution. Therefore, in order to increase the recording density by reducing the mark size, the wavelength of the light may be reduced or the numerical aperture NA of the lens may be increased. In order to increase the numerical aperture of the lens, the focusing lens and the recording layer of the disk are approached.

That is, the present invention is a concept that combines the advantages of the conventional far field method and the near field method, by forming a recording layer on the surface of the disk and irradiating light through a focusing lens having a high numerical aperture to signal to a disk having a high recording density. The advantage of the near-field method of recording or reproducing the data, and the distance between the disk surface and the focusing lens at a predetermined distance, protects the focusing lens from heat and contamination and secures a space for forming an appropriate protective layer on the disk surface. It has all the advantages.

Therefore, the signal can be recorded or reproduced on a disk having a high recording density, and at the same time, the protective layer of the disk can be efficiently formed.

However, since the optical recording and reproducing method according to the present invention does not use the Everest wave as in the case of the near field method, it does not overcome the limitation of the resolution caused by the diffraction phenomenon of light as described above, and thus the near field method in terms of recording density. It has a somewhat less effective effect.

However, the problem that the focusing lens should be protected from heat and contamination can fundamentally solve the fatal problem of the near-field method, such as the absolute lack of space for forming a protective layer between the focusing lens and the recording layer of the disc. From the side, it can be seen that such defects can be sufficiently offset.

The focusing lens 20 is preferably mounted on a slider 30 which allows scanning of the tracks of the contact surface recording disk 10 while being lifted against the contact surface recording disk 10 by pneumatic pressure.

That is, according to the present invention, since the slider is driven, the slider is lifted by the air dynamic pressure of the rotating disk as in the near-field method, so that the focus is automatically performed. Therefore, a separate focus servo is not required. The driving speed is fast.

This is possible by taking a structure in which a protective layer 13 having a uniform structure is formed between the recording layer 12 and the focusing lens 20, instead of the substrate 11 having a non-uniform structure, unlike the conventional far field method. It will be lost.

Although the depth of focus of the focusing lens 20 may be slightly out of the thickness of the recording layer 12 of the contact surface recording type disk 10, the depth of focus may be located within the thickness of the recording layer 12 for recording or reproducing a clearer signal. It is desirable to.

As described above, according to the present invention, since the slider 30 floats due to the air dynamic pressure of the rotating disk, the focusing is automatically performed. It is desirable to take a flat structure. Therefore, it is advantageous that the converging lens 20 mounted on the disk side facing surface of the slider 30 has a higher flatness of the surface facing the contact surface recording disk 10 than the opposite side thereof.

Only one focusing lens 20 may be mounted as having a high numerical aperture, but as shown in FIG. 4, a plurality of focusing lenses 20 may be configured to focus light as a layered structure.

This uses a high numerical aperture expensive lens as the second focusing lens 22 facing the disk side facing surface, and the first focusing lens 21 having a relatively low importance uses a low numerical aperture low cost lens, It is significant in that manufacturing costs can be reduced as a whole.

On the other hand, the present invention can also be applied to the recording and reproducing method of the magneto-optic method that uses an optical method and an electromagnetic method as a method of recording or reproducing a signal of a disc.

As shown in Fig. 5, the method further comprises the steps of: forming a magnetic coil 32 on the opposing surface of the contact surface recording disk 10 side of the slider 30 in addition to the optical recording and reproducing method as described above; Reproducing or recording a signal on the recording layer 12 of the contact surface recording disc 10 by transmitting a signal to the magnetic coil 32; It is achieved by including.

That is, the present invention allows the gap between the slider 30 and the recording layer 12 of the disc to be narrowed, so that the magnetic coil 32 and the recording layer 12 of the disc are compared with the conventional magneto-optical recording and reproducing method. The distance between them is narrowed, so that the required amount of current required per unit recording can be reduced.

In addition, since a disk having a high recording density is used, a magnetic coil 32 having a smaller structure is applied, which enables recording by higher frequency, so that an effect of increasing the information transmission rate can be obtained.

Hereinafter, a high density optical recording and reproducing apparatus will be described in detail as an embodiment in which the optical recording and reproducing method according to the present invention is specifically implemented.

6 and 7 show the structure of the optical recording and reproducing apparatus according to the present invention, FIG. 6 is a plan view showing the structure of the entire optical recording and reproducing apparatus, and FIG. 7 is a schematic diagram showing the structure of the optical system. .

As shown in the drawing, the optical recording and reproducing apparatus according to the present invention includes a transmitter / receiver 40 for recording or reproducing information by irradiating and incident light, and a reciprocating rotation with respect to the surface of the disk mounted and rotated in the main body 50. A swing arm 51 provided as possible, an actuator 52 providing a rotational driving force to the swing arm 51, a slider 30 provided at an end of the swing arm 51, and a light receiver And a light converging portion for focusing the light irradiated from the 40 and incident on the disk.

Here, the slider 30 is provided so as to scan the track of the disk while floating against the disk by pneumatic pressure, the disk having the recording layer oriented to the contact surface side with the slider 30 about the center of the thickness thereof. The contact surface recording type disk 10 is formed, and the light converging portion includes a focusing lens 20 having a high numerical aperture, and is irradiated from the transmitting and receiving portion 40 to the recording layer 12 of the contact surface recording type disk 10. Light is incident to record or reproduce information.

The focusing lens 20 is mounted so that its depth of focus is located within the thickness of the recording layer of the contact surface recording disk 10, and the focusing lens 20 has the flatness of the surface facing the contact surface recording disk 10 opposite. It is characterized by higher than the side.

One focusing lens 20 may be mounted as one having a high numerical aperture, and a plurality of focusing lenses 20 may be mounted as one having a lower numerical aperture. When the plurality of focusing lenses 21 and 22 are mounted, a slider ( 30) is provided so that the optical axis coincides as a layered structure.

As shown in FIG. 7, the light-receiving unit 40 includes a light irradiation unit 41 for irradiating light; A beam splitter 44 having an exploded surface for selectively reflecting the irradiated light; A collimating lens 43 mounted to the light focusing side so as to coincide with the optical axis of the light that has reflected or transmitted the beam splitter 44; Reflecting means (34) mounted to reflect light transmitted through the collimating lens (43) toward the light focusing portion; Signal conversion means (42) mounted on the opposite side of the light focusing portion of the beam splitter (44); It is configured to include.

On the other hand, in the case of adopting the magneto-optical method, the magnetic coil 32 mounted on the opposing surface of the contact surface recording disk 10 side of the slider 30; Recording means (not shown) for transmitting a signal to the magnetic coil 32; It is configured to include.

The optical recording and reproducing apparatus according to the present invention adopts a driving method in which the slider 30 floats due to the air dynamic pressure generated by the rotation of the disk. Therefore, the optical recording and reproducing apparatus has a contact surface with the contact surface recording type disk 10 of the slider 30. It is preferable that the air pressure generating part 31 is formed.

The operation of the high density optical recording and reproducing apparatus according to the present invention will be described below.

The light irradiated from the light irradiating part 41 passes through the disassembled surface of the beam splitter 44, is converted into parallel light while passing through the collimating lens 43, and is reflected by the reflecting means 34 to reflect the slider 30. Will face.

The light condensed by the objective lens 21 and the opposing lens 22 formed under the slider 30 is reproduced or recorded by the recording layer 12 of the contact surface recording disk 10, and then the opposing lens ( 22) the light is collected while passing through the path of the objective lens 21 and the reflecting means 44.

This light is reflected on the disassembled surface of the beam splitter 44 and is incident on the signal converting means 42, thereby converting a signal recorded on the recording layer 12 of the contact surface recording disk 10 into an electrical signal.

In the case of the magneto-optical method, the optical reproducing or recording method is the same as above, and in the electromagnetic reproducing or recording method, a signal is transmitted to the magnetic coil 32 formed on the opposing surface of the contact surface recording disk 10 side of the slider 30. By the magnetic energy generated by the coil 32, a signal is reproduced or recorded on the recording layer 12 of the contact surface recording disk 10.

The present invention provides an optical recording and reproducing method and apparatus of a more advanced configuration which enables to reproduce or record information from a disk having a high recording density, and can effectively protect the surface of the disk.

Claims (13)

An optical recording and reproducing method for recording or reproducing information by irradiating and injecting light onto a rotating disk through a focusing lens from a transmitting / receiving unit, Providing a contact surface recording type disk in which a recording layer is formed on the contact surface side with the focusing lens with respect to the center of the disk thickness; Recording or reproducing information by injecting the light irradiated from the transmitting / receiving unit onto the recording layer of the contact surface recording disc through the focusing lens; High density optical recording and reproducing method comprising a. The method of claim 1, And the focusing lens is mounted to a slider which allows scanning of tracks of the contact surface recording disk while floating against the contact surface recording disk by air dynamic pressure. The method of claim 2, The focus depth of the focusing lens is located within the thickness of the recording layer of the contact surface recording type disk. The method of claim 3, And the flattening of the focusing lens toward the contact surface recording disk is higher than the opposite side. The method of claim 4, wherein And a plurality of converging lenses configured to focus light as a layered structure. The method according to any one of claims 1 to 5, Forming a magnetic coil on the contact surface recording disk side facing surface of the slider; Reproducing or recording a signal on a recording layer of the contact surface recording disc by transmitting a signal to the magnetic coil; High density optical recording and reproducing method comprising a. A transmitter / receiver for recording or reproducing information by irradiating and entering light, a swing arm mounted on the main body so as to be reciprocally rotated, an actuator providing rotational driving force to the swing arm, and the swing An optical recording and reproducing apparatus, comprising: a slider provided at an end of an arm; and a light converging section attached to the slider to focus light irradiated from the light transmitting and receiving section and to enter the disk. The slider is installed to scan the track of the disk while floating against the disk by pneumatic pressure, The disk is a contact surface recording type disk in which the recording layer is formed on the contact surface side with the slider about the center of the thickness thereof, And the light converging portion comprises a condenser lens having a high numerical aperture, and recording or reproducing information by injecting light irradiated from the light transmitting and receiving portion to a recording layer of the contact surface recording type disk. The method of claim 7, wherein And the focusing lens is mounted so that its depth of focus is within the thickness of the recording layer of the contact surface recording disk. The method of claim 8, And said converging lens has a flatness of the surface facing the contact surface recording type disk higher than that on the opposite side thereof. The method of claim 9, And a plurality of focusing lenses mounted on the slider so that the optical axes coincide with each other in a layered structure. The method according to any one of claims 7 to 10, The transmitter and receiver A light irradiation unit for irradiating light; A beam splitter having an exploded surface for selectively reflecting the irradiated light; A collimating lens mounted to the light converging portion so as to coincide with the optical axis of the light reflected or transmitted by the beam splitter; Reflecting means mounted to reflect light transmitted through the collimating lens toward the light converging portion; Signal conversion means mounted on the opposite side of the light converging portion of the beam splitter; High density optical recording and reproducing apparatus, characterized in that it comprises a. The method according to any one of claims 7 to 10, A magnetic coil mounted to the contact surface recording disk side opposing surface of the slider; Recording means for transmitting a signal to the magnetic coil; High density optical recording and reproducing apparatus configured to include. The method according to any one of claims 7 to 10, And an air pressure generating portion formed on the contact surface of the slider with the contact surface recording type disk.