JP2001143260A - Information recording and reproducing method and disk used for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To settle a loading method which stably floats an optical head in proximity field recording using the optical head on which an SIL(solid immersion lens) is mounted. SOLUTION: A disk 2 provided with an area 1 for floating is used, and the optical head on which the SIL is mounted is moved to an objective place in a recording and reproducing area 3 to perform recording and reproducing after being floated in the area 1 for floating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which analog codes such as video and audio are FM-modulated by a recording beam such as a laser beam, data of an electronic computer, and the like.
The present invention relates to an information recording / reproducing method capable of recording / reproducing digital information such as a facsimile signal and a digital audio signal in real time.
The present invention relates to a loading method in an information recording / reproducing apparatus using mmersion lenses.

[0002]

2. Description of the Related Art In recent years, with the increase in the capacity of information, the development of high-density recording technology using optical recording has been actively performed. In optical recording, the limit is said to be a recording bit diameter of about 500 nm due to light diffraction. This diffraction limit is proportional to the wavelength of the light and inversely proportional to the figure of merit (NA) of the lens. For this reason, one direction of the high density is to shorten the wavelength of light and to increase the NA of the aperture lens.

As another method, there is a method utilizing an optical phenomenon which does not depend on the diffraction limit. Recently, in particular,
As a method for propelling these, attention has been paid to a near field in light. For example, as in US Pat. No. 5,121,256, an increase in NA is realized by using SIL, and a smaller spot diameter than that obtained by using an ordinary optical lens is obtained.

[0004] The principle of the prior art will be described below. First, the SIL is manufactured by polishing a spherical lens made of a transparent substance having a large refractive index n into, for example, a hemispherical surface. Next, the focus of the laser beam focused by the focusing lens is adjusted to this polished surface. The speed of the laser light entering the SIL is reduced by the refractive index, and the wavelength is reduced to 1 / n. That is,
The diffraction limit in the SIL is reduced to 1 / n of the normal value. From a different viewpoint, it can be said that the NA of the objective lens can be increased n times.

[0005] At this time, even if the NA is increased inside the SIL, if the laser beam passes through the SIL and enters the air, it returns to the original beam spot diameter again. However, when the distance between the polished surface, which is the bottom surface of the SIL, and the sample (eg, on the recording film of the disk) is close to λ / 4 or less with respect to the wavelength λ of the incident light (near field), the wavelength becomes Since the light is propagated to the sample as 1 / n, the resolution can be increased by n times. That is, a normal 1 / n diffraction limit is obtained.

[0006]

As described above, high-density recording can be performed by using the SIL. However, since the distance between the optical head on which the SIL is mounted and the disk surface is extremely small, the optical head cannot be mounted on the disk. When setting (loading) the optical head, the optical head and the disk may come into contact (crash). This is likely to occur when the disk surface is soft or when the disk surface has large irregularities (for example, maximum height: Rmax).

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to realize an SI for achieving higher density recording more stably.
An object of the present invention is to provide a method of loading an optical head equipped with an L.

[0008]

SUMMARY OF THE INVENTION The present invention provides a loading method by which an SIL-mounted optical head can be stably levitated on the surface of a recording medium. The optical head crashes mainly when the optical head is set (loaded) on a disk. If the surface of the disk is soft, the surface of the disk is pressed and dented when the optical head approaches the disk. As a result, the flying of the optical head becomes unstable, causing a crash. Also,
The surface roughness (especially Rmax) of the disk surface also causes a crash at the time of flying. Therefore, in the present invention, at least one of the following two loading methods is used.

(1) Using a disk provided with a dedicated area for flying, first, loading is performed in the area for flying, and after the optical head stably floats, the optical head is moved to a target place. Perform recording or playback.

(2) In the case of CAV (constant angular velocity), the rotation speed of the disk during loading is once higher than the rotation speed during normal recording or reproduction, and after the optical head stably floats, the recording or reproduction is stopped. Recording or reproduction is performed by returning to the rotation speed of. In the case of CLV (constant linear velocity), the linear velocity of the disk at the time of loading is once higher than the linear velocity at the time of recording or reproduction, and after the optical head stably flies, the linear velocity at the time of recording or reproduction is increased. To perform recording or playback.

In the present invention, the above (1) and (2) may be combined in some cases. For example, if there is a large difference in film thickness between the flying area and the recording / reproducing area, loading is performed in the flying area, and after the optical head stably flies, the rotation during recording / reproducing. After increasing the flying height at a speed higher than the number and overcoming the step of the film thickness, the number of revolutions may be returned to the number of revolutions at the time of recording / reproduction, and recording or reproduction may be performed at a target place.

The floating area and the recording / reproducing area are preferably on the same substrate, but may be provided on separate substrates. Further, it is preferable that the area for floating is a surface state where a film such as a recording film is not formed, for example, a glass substrate.

The SIL loading method according to the present invention is effective not only in an information recording / reproducing apparatus but also in an original disc cutting apparatus. In particular, since the resist is soft, the effect is large.

Further, by forming a super-resolution film on the SIL, it is possible to further increase the density as compared with the prior art. Here, the super-resolution film refers to a thin film in which, when an incident beam passes through the super-resolution film and exits, the beam spot diameter of the emitted beam is smaller than the spot diameter of the incident beam. . In addition, the super-resolution film is often formed on a plane portion (for example, a polished surface) of the SIL.

As the super-resolution film of the present invention, a photochromic material is mainly used, and multiphoton absorption, photobleachability (photobleachability), absorption saturation and the like are utilized. Since the transmittance of the central portion of the irradiation beam in the super-resolution film is high, the beam is transmitted only in this region. As a result, the beam spot diameter is apparently smaller (super-resolution effect). Alternatively, the same effect can be obtained by using a film in which a hole (such as a pinhole) smaller than the beam diameter is formed in the vicinity of the center position of the incident beam in advance.

[0016]

(Embodiment 1) In this embodiment, a disk 2 having an area 1 for floating an optical head as shown in FIG. 1 is used. Here, the recording / reproducing area 3 has a diameter of 12
ZnS-SiO ₂ on a 0 mm, 0.6 mm thick glass substrate
GeSbTe-based recording film and Al-T sandwiched between protective films
An i-reflection film and the like are formed. First, area 1 for ascent
Move the optical head to the desired rotation speed (1500 rpm)
When it comes to loading.

Since the glass substrate on which the recording film and the like are not formed is left in the floating region 1, the floating can be performed stably. After flying, the optical head is moved to a target location on the recording / reproducing area 3 to perform recording / reproducing. If the recording film or the like crashes at the boundary between the flying area 1 and the recording / reproducing area 3 due to the thickness of the recording film or the like, after loading in the flying area 1, the rotation speed or linear velocity of the disk After raising the height to a level higher than the normal flying height, the level difference may be overcome.

A disk (a glass substrate having a diameter of 120 mm and a thickness of 0.6 mm) having no area for floating is used. In the case of CAV (constant angular velocity), a normal rotation speed used for recording and reproduction is used. Faster than 3000rpm
By rotating the disk in step m) and loading the optical head with the flying height increased, the disk was less affected by the state of the irregularities on the disk surface, so that the disk could fly stably.

After floating, the number of revolutions during recording and reproduction (1500 r)
pm), and recording / reproducing was performed at the target place. CL
In the case of V (constant linear velocity), the disk is rotated at a linear velocity higher than the normal linear velocity used for recording / reproducing, and the optical head is loaded with the flying distance increased, so that the irregularities on the disk surface are reduced. Since it is less affected by the state, it is possible to stably float. After ascending,
The recording / reproducing may be performed at the target location by returning to the linear velocity at the time of recording / reproducing.

(Embodiment 2) FIG. 2 shows an outline of a recording / reproducing system in this embodiment. A laser beam 7 emitted from a semiconductor laser (wavelength 410 nm) is incident on a floating optical head 6 in which the SIL 4 and the aperture lens 5 are integrated. The laser beam 7 is focused on the polished surface 8 of the SIL.

Further, a super-resolution film 9 is formed on the polished surface (plane portion) 8 of the SIL. The distance between the optical head 6 and the disk 2 is approaching about 50 nm (near-field region). This distance is controlled by the shape of the flying head 6 and the number of revolutions of the disk 2, and is kept substantially constant.

The recording / reproducing apparatus used in the present invention is equipped with a laser, means for focusing a beam emitted from the laser on a super-resolution film formed on the SIL by means of a focusing lens, loading means for stably floating, It has at least means for controlling the distance between the super-resolution film surface of the SIL and the disk and means for rotating the disk.

Here, even when the super-resolution film 9 is not formed on the bottom surface of the SIL, the effect of the present invention can be obtained. Further, the loading method used in the present invention can be applied to a cutting device for producing a master. In this case, it is preferable to use a disk which is larger than the size of the disk actually used for recording and reproduction by an area for floating.

[0024]

According to the present invention, a crash can be prevented in loading an optical head mounted with an SIL, and stable loading can be achieved.

[Brief description of the drawings]

FIG. 1 is a plan view of a disk used in an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a recording / reproducing optical system according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Area for floating, 2 ... Disk, 3 ... Recording / reproducing area, 4 ... SIL, 5 ... Focusing lens, 6 ... Floating head, 7 ... Laser beam, 8 ... Polished surface of SIL, 9 ... Super resolution film.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideki Saga 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo F-term in Central Research Laboratory, Hitachi, Ltd. 5D090 AA01 HH01 HH03 LL04

Claims (7)

[Claims] In a method for recording and reproducing information using a solid immersion lens (SIL), a disk provided with a dedicated area for floating an optical head mounted with an SIL is used, and light is emitted in the floating area. An information recording / reproducing method, wherein the recording / reproducing is performed by moving the optical head to a target position in the recording / reproducing area after the optical head is stably levitated (loaded) and levitated. 2. The information recording / reproducing method according to claim 1, wherein when the disk is rotating at a constant angular velocity (CAV), the number of rotations when the optical head is in the floating area is equal to the recording / reproducing area. A method for recording and reproducing information, wherein the number of rotations is higher than the rotation speed when an optical head is provided. 3. The information recording / reproducing method according to claim 1, wherein, when the disk is rotating at a constant linear velocity (CLV), the linear velocity when the optical head is in an area for floating is:
An information recording / reproducing method characterized by being larger than a linear velocity when an optical head is in a recording / reproducing area. 4. In an information recording / reproducing method for recording / reproducing information using SIL, when a disk is rotated by CAV, loading is performed at a higher rotational speed of the disk than at the time of recording / reproducing. A method for recording and reproducing information, wherein the recording and reproduction are performed after returning to the rotation speed at the time of recording and reproduction after stably floating. 5. An information recording / reproducing method for recording / reproducing information by using an SIL, wherein when the disk is rotating at CLV, the linear velocity of the disk is set to be higher than at the time of recording / reproducing, and the optical head is loaded. After a stable surface,
An information recording / reproducing method, wherein recording or reproduction is performed after returning to a linear velocity at the time of recording / reproduction. 6. A disk used in a method for recording and reproducing information using an SIL, wherein a dedicated area for floating an optical head mounted with the SIL is provided. 7. The disk according to claim 6, wherein a dedicated area for floating is left on the substrate surface.