JPH05266491A - Optical recording medium - Google Patents

Abstract

PURPOSE:To provide an optical recording medium capable of tracking and recording/reproducing/erasing to plural optical recording mediums whose track pitches are different each other by only one optical recording and reproducing device and with high interchangeability. CONSTITUTION:A standard track pitch area 22 and a user area 24 where the track pitches of a tracks 12, 14 are different each other are formed on the medium. The standard track pitch area 22 is formed by the track pitch common to each medium. By setting a sevo condition, etc., in the case of recording/ reproducing/erasing based on information recorded on the standard track pitch 22 in the user area 24, stable recording/reproducing/erasing are performed in the user area 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium used in an optical disk memory for recording / reproducing / erasing information by a laser beam, and more specifically to an optical recording medium for realizing a high density by narrowing a track pitch. The present invention relates to a recording medium.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 15, an optical recording medium used in an optical disk memory for recording / reproducing and erasing information by a laser beam is manufactured by injection molding and has a tracking groove 101 with a single track pitch. On the transparent substrate 100 such as polycarbonate provided with SiAlON, Al
Interference layer 102 of N, SiN, etc., recording layer 1 of GdTbFe, TbFeCo, etc.
04, SiAlON, AlN, a protective layer 106 such as SiN, and a reflective layer 108 such as Al are sequentially laminated.

In such an optical recording medium, information is recorded by irradiating the recording layer 104 with a laser beam and heating it to a Curie temperature or a compensation temperature or more and at the same time applying a magnetic field from the outside to invert the magnetization. It is done by In addition, reproduction is performed by utilizing the Kerr effect that when the recording layer 104 is irradiated with a linearly polarized laser beam, the rotation of the polarization plane of the reflected light is reversed depending on the direction of magnetization. The recording layer 1
Reference numeral 04 denotes a phase change recording material in addition to a magneto-optical recording material,
Perforated recording materials are also used.

Tracking is performed by a well-known push-pull method using the guide groove 101 provided on the substrate 100. The depth of the guide groove 101 is selected to be about 70 nm so that the push-pull signal necessary for tracking can be obtained with sufficient intensity. The track pitch is usually selected to be 1.6 μm.

[0005]

However, in the conventional optical recording medium, when the track pitch is narrowed in order to increase the recording density, the push-pull signal strength used for tracking decreases, and tracking becomes impossible. was there. The optical recording / reproducing apparatus is set with recording / reproducing / erasing conditions including servo conditions such as a tracking servo gain in accordance with a specific track pitch. Therefore, for example, when the push-pull signal strength is set larger than the set tracking servo gain, the tracking servo circuit oscillates when it is large, and when it is small, it becomes impossible to follow the movement of the track, and in any case tracking becomes impossible. .. Therefore, there is a problem in that the optical recording media having different track pitches cannot be recorded / reproduced / erased by the same optical recording / reproducing apparatus and compatibility cannot be achieved.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to form a plurality of optical recording media having different track pitches at a common track pitch. By providing a standard track pitch area having tracks, and in this standard track pitch area, by recording information necessary for reproducing, recording / reproducing, or recording / reproducing erasing in an area other than the standard track area, It is an object of the present invention to provide an optical recording medium having high compatibility that enables tracking and recording / reproducing / erasing with one optical recording / reproducing device even if the track pitch is different.

[0007]

In order to achieve this object, in an optical recording medium of the present invention, a standard track having a track formed at a common track pitch for a plurality of optical recording media having different track pitches. A pitch area is provided, and in this standard track pitch area, information necessary for reproducing, recording / reproducing, or recording / reproducing / erasing is recorded in an area other than the standard track area, that is, a user area. At this time, if the standard track pitch region is formed at a common radial position for a plurality of optical recording media, for example, at or near the innermost circumference, the track pitch is 1.6 μm, or 1.5 μm, or 1.4 μm. Good. Further, the standard track pitch region is preferably formed in a concentric shape.

[0008]

In the optical recording medium having the above structure, the information recorded in the standard track pitch area is first reproduced. At this time, since the standard track pitch area is formed with a common track pitch for a plurality of optical recording media having different track pitches, the servo condition and the reproducing condition are set in advance in the optical recording / reproducing apparatus. By setting it, it can be read from any optical recording medium. In the standard track pitch area, information necessary for reproduction, recording / reproduction, or recording / reproduction / erasure is recorded in advance in an area other than the standard track area, that is, in an area having a different track pitch depending on the optical recording medium. .. Therefore, by resetting the servo conditions such as the tracking servo gain and the recording / reproducing / erasing conditions based on the information read from the standard track pitch area, the area other than the standard track pitch area can be set.
Recording, reproduction and erasing can be performed.

Here, the standard track pitch region has a track pitch of 1.6 μm at a radial position common to a plurality of optical recording media, for example, at or near the innermost circumference, or
If it is formed with 1.5 μm or 1.4 μm, it will be the position corresponding to the control track where the reproduction is first performed in the conventional optical recording medium.Therefore, it is necessary to detect the position where the standard track pitch area is formed and detect it. It becomes easy to reproduce the information recorded in the. Further, when the standard track pitch area is formed concentrically, even if the reproduction is continuously performed, the area other than the standard track pitch area is not reproduced, and the malfunction can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

An optical recording medium 10 to which the present invention is preferably applied.
As shown in the top view of FIG. 1, a standard track pitch region 22 and a user region 24 in which the track pitches of the tracks 12 and 14 are different from each other are formed. The standard track pitch region 22 is formed, for example, at a track pitch of 1.6 μm on the innermost peripheral side among the plurality of tracks 12 and 14 provided on the optical recording medium 10. User area 24
The track pitch is narrower than the standard track pitch region 22 and is, for example, 1.0 μm.

As shown in FIG. 2, such an optical recording medium 10 has, for example, a guide layer 32 and an interference layer 3 on a substrate 30.
4, the recording layer 36 and the protective layer 38 are laminated, and a part of the guide layer 32 is provided in the standard track pitch area 22 and the user area 24, for example, as shown in FIG. It has been removed on the pitch.

That is, in the standard track pitch area 22, the portion removed along the track 12 in a predetermined pattern forms a mark 40 indicating information necessary for recording / reproducing / erasing the user area 24. There is. On the other hand, the user area 24 is, for example, divided into several sectors 42 in the circumferential direction, and the index portion 44 at the start portion of the sector 42 has a sector mark or the like due to the removed portion of the guide layer 32 along the track 14. A mark 45 for generating a preformat signal is formed. Also,
In the remaining data area 46, a recording area 47 is formed in which the guide layer 32 is continuously removed along the track 14 by a predetermined length. Data is recorded on the recording layer 36 through the recording area 47. The thickness of the interference layer 34 is selected to be approximately λ / (8n ′) or λ / (6n ′) so that a push-pull signal and a preformatted signal can be obtained. Note that n ′ is the refractive index of the interference layer 34.

A resin such as acrylic or polycarbonate, or glass is used for the transparent substrate 30. The guide layer 32 is made of a metal such as Ta, Cr, or Al, and the recording layer 36 is made of a magneto-optical recording medium, for example, a rare earth transition metal amorphous alloy such as TbFeCo, TbFe, GdTbFe, or an extremely thin film of Pt and Co. A multi-layered superlattice thin film is used. Further, for the interference layer 34 and the protective layer 38, glass, transparent oxide such as SiO2, AlN, SiN, or nitride is used. The protective layer 38 functions to protect the recording layer 36 from oxidation and the like.

In general, as the track pitch becomes narrower, the push-pull signal strength used for tracking decreases. Therefore, in order to perform stable tracking, it is necessary to increase the tracking servo gain and correct the decrease in push-pull signal strength. Further, the movement amount when jumping to the adjacent track may be smaller as the track pitch is narrower, so that the track jump pulse intensity also needs to be reduced. Information such as the track pitch or tracking servo gain, push-pull signal strength, and jump pulse strength is recorded in the standard track pitch area 22 in advance, and the servo conditions for recording / reproducing erasing in the user area 24 are recorded. By setting, etc. based on the information recorded in the standard track pitch area 22, stable recording / reproducing / erasing can be performed in the user area 24.

Next, the procedure for recording / reproducing / erasing the optical recording medium 10 of this embodiment by the optical recording / reproducing apparatus will be described with reference to FIG.

FIG. 4 is a block diagram showing the main part of the optical recording / reproducing apparatus. The optical recording medium 10 is irradiated with laser light,
An optical head 50 for recording / reproducing and erasing, an optical head control circuit 52 for controlling the optical head 50, a reproducing circuit 54 for reproducing a signal recorded in the optical recording medium 10, and a central processing circuit 56 for controlling each circuit. Is equipped with. With such a configuration, recording / reproducing / erasing is performed on the optical recording medium 10 according to the procedure shown in the flowchart of FIG. That is, at the start of control, first, the optical head 50 is moved to the standard track pitch area 22 of the optical recording medium 10. Next, servo such as tracking is performed by the optical head control circuit 52 using standard servo conditions stored or set in the optical recording / reproducing apparatus in advance. Here, in the optical recording medium 10 in which the track pitches of the user area 24 are different from each other, the track pitches of the standard track pitch area 22 are common, so the standard servo conditions are also common, and servo can be applied under the same conditions. .. In this state, the reproducing circuit 54 reads the servo conditions and the like in the user area 24 recorded in the standard track pitch area 22.

Here, the tracking servo is once turned off,
The optical head 50 is moved to the user area 24. In this user area 24, the tracking servo gain of the optical head control circuit 52 is calculated using the servo condition in the user area 24 read from the standard track pitch area 22,
Set the track jump pulse strength, etc., and then apply servo again. At this time, the optimum servo can be applied under the condition according to the track pitch of the user area 24.
Recording, reproduction and erasing can be performed under stable conditions. That is, in the same optical recording / reproducing apparatus, the user area 24
It is possible to perform recording / reproducing / erasing on / from the optical recording media 10 having different track pitches.

Although one embodiment of the present invention has been described in detail above with reference to FIGS. 1 to 5, the present invention can be implemented in other modes.

For example, the material of each layer is not particularly limited, and as the material of the substrate 30, other than glass, acrylic resin, polycarbonate resin, amorphous polyolefin resin or the like may be used.

Further, the recording layer 36 is not only a rare earth transition metal alloy other than TbFeCo, a multilayer film of PtCo or PdCo, an oxide magnetic material such as rare earth iron garnet and a magneto-optical material combining these, but also TeO _x , GeSbTe, etc. The phase change material, organic material such as pigment, and the like can be used.

The film thicknesses of the recording layer 36, the protective layer 38 and the guide layer 32 are not particularly limited. For example,
When the guide layer 32 is thin, the irregularities generated in the recording layer 36 are also small, so that the effect of suppressing deterioration from the step portion of the recording layer 36 is increased.

Further, the recording layer 36 is thinned as shown in FIG.
A reflective layer 60 made of a metal such as Al, Au, or Cu may be provided on the protective layer 38. That is, the light incident from the substrate 30 side is transmitted through the recording layer 36, is then reflected by the reflective layer 60, and is transmitted through the recording layer 36 again. As a result, not only the car effect but also the Faraday effect is added, so the reproduction C / N
Becomes higher. Further, as shown in the figure, the guide layer 32 and the substrate 3
An enhancement layer 62 may be provided between 0. The enhancement layer 62 is made of, for example, a material having the same refractive index as that of the interference layer 34, and by setting the sum of the film thicknesses of the enhancement layer 62 and the interference layer 34 to λ / (4n ′), a larger Kerr effect enhancement can be obtained. Occurs and the reproduction C / N becomes high. However,
Let λ be the wavelength of the laser light and n ′ be the refractive index of the interference layer 34 and the enhancement layer 62. At this time, it is preferable that the refractive indices of the interference layer 34 and the enhancement layer 62 are higher than the refractive index of the substrate 30, because the Kerr effect enhancement is large. The refractive indices of the interference layer 34 and the enhancement layer 62 do not necessarily have to be equal.

The material of the interference layer 34 is not particularly limited, and may be a multi-layer film using a plurality of materials. The thickness of the interference layer 34 is not particularly limited, and may be any value as long as the push-pull signal and the preformat signal used for tracking can be obtained with practically sufficient strength.

Further, as shown in FIG. 7, a translucent recording material 6 such as an organic dye or magnetic garnet is used instead of the interference layer 34.
6 may be used, and the reflective layer 68 may be provided thereon.

Further, as shown in FIG. 8, the interference layer 69 may be formed by spin coating or the like to make its surface flat. At this time, the recording layer 36 and the protective layer 38 also become flat.
That is, since the recording layer 36 does not have a step portion that causes noise or a defect, reliability is improved.

The pattern for removing the guide layer 32 is not particularly limited. For example, it may be removed in a continuous strip shape. The signal recorded in the standard track pitch area 22 is not the removal pattern of the guide layer 32 but the recording layer 36.
May be recorded in. Further, the preformatted signal may also be recorded in the recording layer 36 instead of the removal pattern of the guide layer 32. Although the width of the mark 45 indicating the preformat and the width of the recording area 47 are equal to each other in FIG. 3, the width is not limited to this. For example, the width of the mark 45 is larger than the width of the recording area 47. May be smaller. This results in greater diffraction and greater preformatted signal strength.

Further, as shown in FIG. 9, spiral or concentric guide layers 70 and 71 having different track pitches are formed in the standard track pitch region 22 and the user region 24, and marks 72 and 73 are formed therebetween. Good. Further, only the user area 24 may have the structure shown in FIG. 9, and the standard track pitch area 22 may have the structure shown in FIG.

As an optical recording medium, an interference layer 77 is formed on a substrate 76 having a guide groove 75 as shown in FIG.
Even if the recording layer 78 and the protective layer 79 are stacked, the user area 2 is exactly the same in the same optical recording / reproducing apparatus.
Even if the track pitches of 4 are different, the recording / reproducing erasure can be performed. In this case, since the guide groove 75 is used instead of the guide layer 32, crosstalk increases, and the track pitch cannot be narrower than that using the guide layer 32.

The shape and the like of the guide groove 75 of the guide grooved substrate 76 is not particularly limited, and as shown in FIG.
The groove 80 may be formed and the pit 81 may be provided therebetween. In addition, the standard track pitch area 22 is composed of only the pits 81,
The user area 24 may be composed of the V groove 80 and the pit 81.

Further, the width of the recording area 47 and the track pitch are not particularly limited. For example, the track pitch and the width of the recording area 47 may be narrowed toward the outer circumference. This further increases the recording capacity.

The position where the standard track pitch region 22 is formed does not have to be the innermost circumference of the optical recording medium 10 and is not particularly limited. For example, as shown in FIG. 12, the standard track pitch region 22 may be formed on the outermost periphery of the optical recording medium 10. Accordingly, by detecting the diameter of the optical recording medium 10, the optical head can be relatively easily moved to the standard track pitch region 22.

Further, as shown in FIG. 13, the standard track pitch region 22 may be provided at a predetermined position. Usually, the recordable / reproducible area differs depending on the diameter of the optical recording medium, and the positions of the outermost circumference and the innermost circumference of the area where the track is provided also differ. However, by providing the standard track pitch region 22 at a predetermined position, the optical head can be always moved to the standard track pitch region 22 regardless of the diameter of the optical recording medium.
It is possible to prevent the recording / reproduction / erasure of the optical recording medium from becoming impossible due to the inability to detect the standard track pitch region 22.

The number of standard track pitch regions 22 is not particularly limited, and a plurality of standard track pitch regions 22 may be provided as shown in FIG. For example, the standard track region 22 may be provided in all of the portions corresponding to the innermost position that differs depending on the diameter of the optical recording medium. As a result, recording / reproduction / erasing can be performed on optical recording media having different diameters by the same optical recording / reproducing device. Further, even when the track pitch of the user area 24 changes within one optical recording medium, by providing the standard track pitch area 22 at the boundary, it is possible to prevent a servo error from occurring.

The information recorded in the standard track pitch area 22 is not particularly limited. For example, part or all of the track pitch, tracking servo gain, jump pulse, or the size of the brake pulse that stops the movement of the objective lens during the track jump may be directly recorded, or they may be coded and recorded. You may.

Further, the track pitch of the standard track pitch region 22 is not particularly limited, but if it is equal to the currently commercially available optical recording medium, that is, 1.6 μm, it is compatible with the commercially available optical recording medium. Easy to take. Also, since a relatively large track pitch can realize stable tracking, 1.5, other than 1.6 μm,
1.4 μm is preferable. In addition, the standard track pitch area 22
The track pitch of 1 does not necessarily have to be common to each optical recording medium. For example, if the difference is small, such as 1.6 μm and 1.5 μm, there will be no major problems in tracking, etc.
It can be used as a standard track pitch area.

The width of the standard track pitch area 22 is not particularly limited as long as it has a capacity for recording necessary information. It should be noted that the standard track pitch area can be more reliably reproduced by setting the fluctuation in the radial direction of the track position allowed when the optical recording medium is eccentric and the degree of identification or a width wider than that.

Further, by forming the standard track pitch area 22 concentrically and recording the same contents on each track, it is sufficient that only one of the tracks formed in the standard track pitch area 22 can be reproduced. ,Also,
Since the track jump is not necessary in the standard track pitch area 22, the structure of the optical recording / reproducing apparatus is simplified.
Further, even when the reproduction is continuously performed, the area other than the standard track pitch area is not reproduced, and the malfunction can be prevented.

Further, the standard track pitch region 22 and the user region 24 do not have to be formed continuously, and a buffer region where no track is formed may be provided between them.

The optical recording medium used in the optical recording system of the present invention does not have to be disk-shaped, and its shape is not particularly limited. For example, it may be card-shaped.

[0041]

As is clear from the above description,
The optical recording medium of the present invention is provided with a standard track pitch area having tracks formed with a common track pitch for a plurality of optical recording media having different track pitches, and the standard track pitch area is provided in the standard track pitch area. Information necessary for performing recording / reproducing / erasing is recorded in an area other than the pitch area, that is, in the user area. Therefore, in the same optical recording / reproducing apparatus, it is possible to perform recording / reproducing / erasing with respect to optical recording media having different track pitches in user areas, and it is possible to easily maintain compatibility in optical recording media having different track pitches. You can

[Brief description of drawings]

FIG. 1 is a plan view of an essential part showing an embodiment of an optical recording medium of the present invention.

FIG. 2 is a cross-sectional view of essential parts for explaining the configuration of the optical recording medium of the present invention.

FIG. 3 is a main part plan view showing a pattern formed on a guide layer in the optical recording medium of the present invention.

FIG. 4 is a block diagram showing a main part of an optical recording / reproducing apparatus for performing recording / reproducing / erasing on / from the optical recording medium of the present invention.

FIG. 5 is a flowchart showing a procedure for performing recording / reproducing / erasing on / from the optical recording medium of the present invention.

FIG. 6 is a cross-sectional view of essential parts showing another embodiment of the optical recording medium of the present invention.

FIG. 7 is a cross-sectional view of essential parts showing another embodiment of the optical recording medium of the present invention.

FIG. 8 is a cross-sectional view of essential parts showing another embodiment of the optical recording medium of the present invention.

FIG. 9 is a main part plan view showing another embodiment of the guide layer removal pattern in the optical recording medium of the present invention.

FIG. 10 is a cross-sectional view of essential parts showing another embodiment of the optical recording medium of the present invention.

FIG. 11 is a cross-sectional view of essential parts showing another embodiment of the optical recording medium of the present invention.

FIG. 12 is a main part plan view showing another embodiment of the optical recording medium of the present invention.

FIG. 13 is a main part plan view showing another embodiment of the optical recording medium of the present invention.

FIG. 14 is a main part plan view showing another embodiment of the optical recording medium of the present invention.

FIG. 15 is a cross-sectional view of an essential part showing an optical recording medium using a conventional substrate.

[Explanation of symbols]

 10 optical recording medium 12 tracks 14 tracks 22 standard track pitch area

Claims (7)

[Claims] 1. An optical recording medium having a plurality of tracks and reproducing, recording / reproducing, or recording / reproducing erasing information along the tracks, wherein the tracks are formed at a plurality of track pitches. Characteristic optical recording medium. 2. The optical recording medium according to claim 1,
An optical recording medium having a standard track pitch region having the tracks formed at a common track pitch for a plurality of optical recording media. 3. The optical recording medium according to claim 2,
An optical recording medium, wherein the standard track pitch region is formed in a concentric shape. 4. The optical recording medium according to claim 2,
An optical recording medium, wherein the standard track pitch region is formed at a common radial position for the plurality of optical recording media. 5. The optical recording medium according to claim 2, wherein
An optical recording medium, wherein the standard track pitch region is formed at or near the innermost circumference. 6. The optical recording medium according to claim 2,
The track pitch of the standard track pitch area is 1.6μ
An optical recording medium characterized by having a size of m, 1.5 μm, or 1.4 μm. 7. The optical recording medium according to claim 2, wherein
An optical recording medium, wherein information necessary for reproducing, recording / reproducing, or recording / reproducing erasing is recorded in the standard track pitch area in an area other than the standard track area.