JPH08212550A - Phase transition type optical recording medium and optical information recording and reproducing device - Google Patents

Abstract

PURPOSE: To stabilize a tracking and to reduce the error at the time of recording/reproducing information as to a phase transition type optical recording medium capable of repeating recordings and which has a low reflectivity. CONSTITUTION: This device is set so as to satisfy either one of or all of next conditions with respect to track groove characteristics. 1) the push-pull value after a recording is within the range of 0.08 to 0.16. 2) the push-pull ratio before and after the recording is within the range of 0.6 to 1, 2. 3) the radial contrast value before the recording is >=0.1. 4) the radial contrast value after the recording is >=0.2, 5) the radial contrast ratio before and after the recording is >=0.3. Thus, the tracking is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in the field of optical memory-related equipment and the like, in which an optical information recording medium is condensed and irradiated with a light beam to cause a phase change in a recording layer material. The present invention relates to a phase change type optical recording medium and an optical information recording / reproducing apparatus capable of recording / reproducing information and rewriting.

[0002]

2. Description of the Related Art As one of optical memory media capable of recording, reproducing and erasing information by irradiating electromagnetic waves, especially laser beams, a transition between a crystalline phase and an amorphous phase or a transition between a crystalline phase is used. The so-called phase change type optical recording medium is well known. According to this phase change type optical recording medium, a single beam overwrite value, which is difficult particularly in a magneto-optical disk memory, is possible, and the optical system on the drive side is simpler. R & D is becoming more active.

As a typical example of such a phase change type optical recording medium, there is a so-called chalcogen alloy material as shown in US Pat. No. 3,530,441. Further, according to Japanese Patent Laid-Open No. 62-73438, Ge-Te is used to improve the recording / erasing repetition performance.
The composition such as -Se-Sb is specified.

By the way, a commercially available optical disc which can be recorded only once and cannot be rewritten (so-called write-once compact disc = WO / CD) is commercially available.
As for the standard of the track groove of the CD system, the push-pull value after recording PPA: 0.04 to 0.09 the push-pull ratio before and after recording NPPR: 0.6 to 1.2 radial contrast before recording RCb> 0 .05 radial contrast after recording RCa> 0.2. Even in the phase change type optical recording medium, it is necessary to form track grooves in the medium in advance, and it is conceivable to apply such a standard as a standard of such a track groove.

[0005]

However, according to such a conventional CD-based track groove standard, in an optical information recording / reproducing apparatus capable of recording / erasing / reproducing a CD system, a push-pull value and a radial contrast are obtained. Both may be small, but when both are small, in a phase change optical recording medium having a low reflectance, tracking is unstable and tracking error easily occurs, so that an error is likely to occur during recording / reproduction. . In particular, it is remarkable in an optical information recording / reproducing apparatus that uses a push-pull method for tracking servo. Further, as will be described later in detail, according to the conventional CD-based track groove standard, the track groove is formed as a narrow groove having a groove depth of 40 nm and a groove width of about 0.25 to 0.4 μm. The stamper having such a groove depth and groove width is very difficult to make, and even if it can be made, the cost becomes high.

For this reason, it is awaited to provide the track groove characteristics suitable for the phase change type optical recording medium capable of recording many times.

[0007]

According to the first aspect of the present invention,
Push-pull value after recording track groove characteristics is 0.08-
It is a phase-change optical recording medium set to fall within the range of 0.16.

According to a second aspect of the present invention, there is provided a phase change type optical recording medium in which the push-pull ratio of the track groove characteristics before and after recording is set within the range of 0.6 to 1.2.

According to a third aspect of the present invention, there is provided a phase change type optical recording medium in which the radial contrast value of the track groove characteristic before recording is set to 0.1 or more.

The invention according to claim 4 is a phase change type optical recording medium in which the radial contrast value after recording of the track groove characteristics is set to 0.2 or more.

According to a fifth aspect of the present invention, there is provided a phase change type optical recording medium in which the radial contrast ratio of the track groove characteristics before and after recording is set to 0.3 or more.

According to a sixth aspect of the present invention, with respect to track groove characteristics, the push-pull value after recording is 0.08 to 0.16.
The push-pull ratio before and after recording is 0.6-
It is set within the range of 1.2, the radial contrast value before recording is 0.1 or more, the radial contrast value after recording is 0.2 or more, and the radial contrast ratio before and after recording is 0.3 or more. It is a phase change type optical recording medium.

According to the invention of claim 7, in the invention of claim 6, the track groove has a depth of 50 to 60 nm,
It is a phase change type optical recording medium having a groove width of 0.3 to 0.6 μm.

According to an eighth aspect of the invention, in the invention of the sixth aspect, the phase change type in which the main component material of the recording layer formed on the substrate contains at least Ag, In, Sb, Te. It is an optical recording medium.

A ninth aspect of the present invention is the phase change optical recording medium according to the sixth aspect, wherein the substrate material has a refractive index of 1.5 to 1.62.

The invention of claim 10 is the phase change type optical recording medium according to the invention of claim 6, wherein the reflectance of the medium itself is 35% or less.

According to an eleventh aspect of the present invention, tracking control is performed by a push-pull method by converging and irradiating a light beam onto an optical information recording medium, and information recording,
An optical information recording / reproducing apparatus for erasing or reproducing, wherein the phase change type optical recording medium according to any one of claims 1 to 10 is used as the optical information recording medium. is there.

[0018]

In the present invention, with respect to the track groove characteristics, the push-pull value after recording is within the range of 0.08 to 0.16, and the push-pull ratio before and after recording is within the range of 0.6 to 1.2. The radial contrast value is 0.1 or more, the radial contrast value after recording is 0.2 or more, and the radial contrast ratio before and after recording is 0.3 or more. By setting any or all of them so that tracking is stable. In addition, since the track deviation is less likely to occur, errors during recording / reproduction can be reduced.

Particularly, in the invention according to claim 6, since the track groove characteristics are set so as to satisfy all of these conditions, the tracking becomes more stable. Further, in the invention according to claim 7, the condition of the invention according to claim 6 is set by setting the depth of the track groove to 50 to 60 nm and the groove width to 0.3 to 0.6 μm. Easy to manufacture, easy to manufacture, and more stable in tracking. Further, claims 8, 9 and
In the invention described in 10, the main component material of the recording layer formed on the substrate is at least Ag, In, Sb, Te.
Or the substrate material has a refractive index of 1.5 to
Since the condition of the invention according to claim 6 is set to 1.62 or the reflectance of the medium itself is set to 35% or less,
Tracking becomes more stable before and after recording.

According to the invention of claim 11,
Since the phase change type optical recording medium set as described above with respect to the track groove characteristics is used as a medium, tracking control by the push-pull method can be stably performed, and recording / reproducing operation with few errors can be performed.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. First, the phase change type optical recording medium 1 used in this example
3 has a structure in which a lower protective layer 3, a recording layer 4, an upper protective layer 5, a heat dissipation layer 6 and a UV protective layer 7 are sequentially laminated on a substrate 2, as shown in FIG. Here, the substrate 2 is made of polycarbonate resin. The shape of the substrate 2 (therefore, the shape of the phase change optical recording medium 1) is, for example, a disk shape, but may be a card shape or a sheet shape. The upper and lower protective layers 3 and 5 are formed of, for example, ZnS, SiO ₂ , SiN _x, or the like. The recording layer 4 changes the optical constant upon irradiation with electromagnetic waves such as a laser beam, and is preferably a phase-change material, particularly preferably Ag, I as a layer constituent element.
Those containing n, Sb and Te are preferable. Therefore, the recording layer 4 is made of, for example, AgInSbTe, GeSbTe, or the like. The heat dissipation layer 6 is, for example, Al or Al.
It is made of alloy, Au, Ag, or the like. This heat dissipation layer 6 is not always necessary, but it is preferable to provide it in order to reduce the heat load on the disk (substrate 2) side by dissipating excess heat by the heat dissipation layer 6. The UV protection layer 7 is
It is made of UV curable resin.

Phase change type optical recording medium 1 usable in this embodiment
Is not limited to such a structure and material, but the above structure or material is preferable because recording / reproducing and overwrite characteristics are improved.

In such a phase change type optical recording medium 1, track grooves 8 as shown in FIG. 2 are formed in advance as pregrooves. Here, the groove characteristics of the track groove 8 are set as follows in this embodiment.

First, the standard is set so that the push-pull value after recording is within the range of 0.08 to 0.16 as shown in the range A in FIG. Range B in FIG. 1 indicates the conventional CD standard (0.04 to 0.09). When the push-pull amplitude is I1-I2 and the amplitude top level for 11T is I _top , the push-pull value after recording is PPA (after recording) = (I1-I2) / I _top (0.1 μ
m offset time).

FIG. 1 shows the dependence of the push-pull value after recording on the groove width and groove depth. According to FIG. 1, in the case of the conventional CD standard, the groove depth is 40n.
When the track width is m, the track width must be formed as a narrow track groove so that the groove width is in the range of 0.25 to 0.4 μm, and it is very difficult to make a stamper suitable for this. Further, since the push-pull value is small, tracking is likely to be missed in an optical information recording / reproducing apparatus using a push-pull tracking servo. On the other hand, according to the push-pull value standard of this embodiment, the groove depth of the track groove 8 is 50 to 50.
It is sufficient that the groove width is 60 nm and the groove width is in the range of 0.3 to 0.55 μm, and a stamper suitable for this can be sufficiently manufactured. Further, in the case of the phase change type optical recording medium 1 produced within the range of such a standard, it is larger than the conventional push-pull value in the evaluation by the wavelength λ = 780 nm and the numerical aperture NA = 0.47 of the objective lens. Therefore, the tracking is stable, and the track is less likely to be lost. Therefore, when used in an optical information recording / reproducing apparatus that performs push-pull type tracking control, errors in recording / reproducing are reduced.

Secondly, the push-pull ratio before and after recording, that is, the normalized push-pull NPPR is set to fall within the range of 0.08 to 0.16 as shown in the range A in FIG. ing. Range b in FIG. 4 is a conventional CD
The standard (0.5 to 1.0) is shown. Before recording, (I1
-I2) / Ig and (I1-I2) / Iga after recording, the push-pull ratio NPPR is NPPR = {(I1-I2) / Ig} / {(I1-I
2) / Iga}.

FIG. 4 shows the dependence of the push-pull ratio NPPR on the groove width and groove depth before and after recording. According to FIG. 4, according to the conventional CD standard, the track groove has a groove depth of 40 to 60 nm and a groove width of 0.3 to
Push-pull ratio NP even if changed in the range of 0.6 μm
PR is concentrated on values near the upper limit of the conventional CD standard. This is because if the NPPR is small, the push-pull after recording is small, and in this case, tracking is likely to be lost in the push-pull type optical information recording / reproducing apparatus. On the other hand, according to the standard of the push-pull ratio NPPR of this embodiment, the track groove 8 may have a groove depth of 40 to 60 nm and a groove width of 0.3 to 0.6 μm. A stamper that conforms to can be created sufficiently. Further, in the case of the phase change type optical recording medium 1 created within such a standard range, the wavelength λ = 780 nm, the numerical aperture NA of the objective lens =
In the evaluation according to 0.47, since it is larger than the conventional push-pull ratio, the tracking is stable and the track deviation is unlikely to occur. Therefore, when used in the optical information recording / reproducing apparatus, errors in recording / reproducing are reduced.

Thirdly, the standard is set so that the radial contrast value RCb before recording is 0.1 or more as shown by an arrow A in FIG. Arrow B in FIG. 5 indicates the conventional CD standard (0.05 or more). When the land level is I _l and the groove level is I _g , the radial contrast value RCb before recording is calculated as RCb (before recording) = 2 * (I _l −I _g ) / (I _l + I _g ). It is a thing.

FIG. 5 shows the dependence of the radial contrast value RCb before recording on the groove width and the groove depth. According to FIG. 5, in the case of the conventional CD standard,
Since the radial contrast value RCb is small, tracking is likely to be lost when used in a push-pull type optical information recording / reproducing apparatus. On the other hand, according to the standard of the radial contrast value RCb before recording in the present embodiment, the groove depth of the track groove 8 may be in the range of 50 to 60 nm and the groove width may be in the range of 0.3 to 0.55 μm. , It is possible to make a stamper suitable for this. Further, in the case of the phase change type optical recording medium 1 created within such a standard range, the wavelength λ = 780 nm, the numerical aperture NA of the objective lens =
In the evaluation according to 0.47, since it is larger than the conventional radial contrast value RCb before recording, tracking is stable and track deviation is unlikely to occur. Therefore, when used in the optical information recording / reproducing apparatus, errors in recording / reproducing are reduced.

Fourthly, the standard is set so that the radial contrast value RCa after recording is 0.2 or more as shown by an arrow A in FIG. The radial contrast value RCa after recording is calculated as RCa (after recording) = 2 * (I ₁ −I _g ) / (I ₁ + I _g ).

FIG. 6 shows the dependence of the radial contrast value RCa after recording on the groove width and the groove depth. According to FIG. 6, according to the standard of the radial contrast value RCa after recording in this embodiment, if the groove depth of the track groove 8 is 50 to 60 nm and the groove width is 0.3 to 0.55 μm. Well, a stamper suitable for this can be created sufficiently. Further, in the case of the phase change type optical recording medium 1 produced within such a standard range, the wavelength λ = 780 n
In the evaluation with m and the numerical aperture NA of the objective lens = 0.47, the tracking is stable and the track deviation is unlikely to occur. Therefore, when used in an optical information recording / reproducing apparatus, recording / recording
Errors in playback are reduced.

Fifth, the standard is set such that the radial contrast ratio (RCb / RCa) before and after recording is 0.3 or more as shown by an arrow A in FIG. Here, FIG. 7 shows the radial contrast value RC before and after recording.
It shows the dependence of b on the groove width and groove depth. According to FIG. 7, according to the standard of the radial contrast ratio before and after recording in the present embodiment, the groove depth of the track groove 8 is 50 to 60.
nm, and the groove width may be within the range of 0.3 to 0.55 μm, and a stamper suitable for this can be sufficiently manufactured. Further, in the case of the phase-change type optical recording medium 1 produced within the range of such a standard, the radial contrast ratio before and after recording is large in the evaluation with the wavelength λ = 780 nm and the numerical aperture NA = 0.47 of the objective lens. Since the amplitude change before and after recording is small, tracking is stable before and after recording, and track deviation is unlikely to occur. Therefore, when used in the optical information recording / reproducing apparatus, errors in recording / reproducing are reduced.

In the above description, the first to fifth standards for the groove characteristics have been individually described. However, if all of the first to fifth groove characteristic standards are combined or appropriately combined,
It can be easily understood that the tracking is more stable. That is, sixthly, regarding the track groove characteristics, the push-pull value PPA after recording is in the range of 0.08 to 0.16, and the push-pull ratio NPPR before and after recording is 0.
Within the range of 6 to 1.2, the radial contrast value PCb before recording is 0.1 or more, the radial contrast value PCa after recording is 0.2 or more, and the radial contrast ratio (PCb / PCa) before and after recording is If it is set to 0.3 or more, better tracking characteristics can be obtained.

Seventh, when the groove characteristics of the standard described as the sixth are given, the groove depth of the track groove 8 is set to 50 to 6.
It is preferable to satisfy the condition that the groove width is within the range of 0 nm and 0.3 to 0.6 μm. That is, the track groove 8 has a groove depth of 50 to 60 nm and a groove width of 0.3 to 0.6.
With respect to the track groove characteristics, the push-pull value PPA after recording is in the range of 0.08 to 0.16, and the push-pull ratio NPPR before and after recording is 0.6 to 1.
Within the range of 2, the radial contrast value P before recording
Cb is 0.1 or more, the radial contrast value PCa after recording is 0.2 or more, and the radial contrast ratio (PCb / PCa) before and after recording is 0.3 or more. Is easy to manufacture, is easy to manufacture, and has better tracking characteristics.

Eighth, in giving the groove characteristic of the standard described as the sixth, as described in FIG. 3, the recording layer 4 is formed.
At least Ag, In, Sb, Te
Should be included. That is, the main component material of the recording layer 4 contains at least Ag, In, Sb, and Te, and the track groove characteristics are such that the push-pull value PPA after recording is in the range of 0.08 to 0.16. The push-pull ratio NPPR before and after recording is in the range of 0.6 to 1.2, and the radial contrast value PCb before recording is 0.
1 or more, the radial contrast value PCa after recording
Is 0.2 or more, and by setting the radial contrast ratio (PCb / PCa) before and after recording to be 0.3 or more, good tracking characteristics can be obtained before and after recording. In particular, such a recording layer 4 has a higher sensitivity than that of a GeSbTe system and has good groove characteristics after recording, so that the error is further reduced.

Ninth, when the groove characteristic of the standard described as the sixth is provided, the refractive index of the substrate 2 is 1.5 to 1.6.
It is preferable to satisfy the condition of being within the range of 2. The thickness of the substrate 2 is 1.2 mm. That is, after setting the refractive index of the substrate 2 within the range of 1.5 to 1.62,
Regarding track groove characteristics, push-pull value PP after recording
A is in the range of 0.08 to 0.16, the push-pull ratio NPPR before and after recording is in the range of 0.6 to 1.2, the radial contrast value PCb before recording is 0.1 or more, and after recording By setting the radial contrast value PCa of No. 2 to be 0.2 or more and the radial contrast ratio (PCb / PCa) before and after recording to be 0.3 or more, better tracking characteristics can be obtained before and after recording. . Further, if the refractive index of the substrate 3 is within the above range, even if the thickness of the substrate 2 is 1.2 mm, the laser beam is focused on the recording layer 4 by the evaluation system by the optical information recording / reproducing apparatus. However, if the refractive index of the substrate 2 is out of the above range, the laser beam is not focused on the recording layer 4 and tracking cannot be performed.

Tenth, it is preferable to satisfy the condition that the reflectance of the phase-change optical recording medium 1 itself is 35% or less when the groove characteristic of the standard described as the sixth is provided. That is, the reflectance of the phase change optical recording medium 1 itself is 35%.
Regarding the track groove characteristics, the push-pull value PPA after recording is in the range of 0.08 to 0.16, and the push-pull ratio NPPR before and after recording is 0.6 to 1.
Within the range of 2, the radial contrast value P before recording
Cb is 0.1 or more, the radial contrast value PCa after recording is 0.2 or more, and the radial contrast ratio (PCb / PCa) before and after recording is set to 0.3 or more, so that before and after recording. A better tracking characteristic can be obtained.

Here, as a more specific structural example of the phase-change optical recording medium 1, a polycarbonate resin having a refractive index of 1.58 is used for the substrate 2, and ZnS, Si is provided on the substrate 2.
A lower protective layer 3 made of O ₂ is formed to a thickness of 200 nm, a recording layer 4 made of AgInSbTe is formed to a thickness of 20 nm on the lower protective layer 3, and ZnS and S are further formed on the recording layer 4.
An upper protective layer 5 made of iO ₂ is formed to a thickness of 25 nm, a heat dissipation layer 6 made of an Al alloy of Al-Ti (1 wt%) is formed to a thickness of 100 nm on the upper protective layer 5, and a UV protective film is formed on the uppermost layer. Formed 7.

In the structure of the phase change type optical recording medium 1 as described above, various measured values when the standard conditions are changed by making the first to ninth conditions described above correspond to the samples 1 to 9 respectively. It shows in Table 1. In addition, these samples 1-1
The phase-change optical recording medium 1 used for No. 0 is a disk having a diameter of 120 nm, and various measured values are measured at the inner circumference (r23
m), the average value of the measured values at the middle circumference (r40 mm) and the outer circumference (r58 mm). In addition, the comparative sample 1 is
An example in which the recording layer is formed of AgInSbTe system in the phase change type optical recording medium according to the conventional CD standard having groove characteristics, and Comparative Sample 2 is the phase change type optical recording medium 1 of Sample 8 in which the recording layer is formed of GeSbTe system. Examples, comparative sample 3 is an example in which impurities are added to the substrate in the phase change optical recording medium 1 of sample 8 so that the refractive index is 1.8, and comparative sample 4 is the phase change optical recording medium of comparative sample 1. In the above, an example in which the upper protective layer forming a part of the layer structure is omitted and the reflectance of the medium itself is 41% is shown. In addition, the optical information recording / reproducing apparatus used for the measurement and evaluation is
This is a normal CD-based recordable / erasable drive device, which is roughly composed of an optical pickup, a signal processing system, and a pickup control system. Tracking is performed in the pickup control system by the push-pull method. A servo system is included, the wavelength of the laser beam used in this drive device is λ = 780 nm, the numerical aperture of the objective lens is NA = 0.47, and the linear velocity of the phase-change optical recording medium is 2.4 m / s. The recording power of the laser beam to be irradiated was set to a multi-pulse with a peak power of 12 mW and a bottom power of 5 mW in the case of 3T as shown in FIG.

[0040]

[Table 1]

According to the results shown in Table 1, in the case of the comparative sample example according to the conventional CD standard, the tracking error occurred, but in the case of the sample example according to the standard set in this embodiment, It can be seen that the tracking error does not occur.

[0042]

As described above, according to the present invention, with respect to the track groove characteristics, the push-pull value after recording is in the range of 0.08 to 0.16, and the push-pull ratio before and after recording is 0.6 to 1.2. Within the range, the radial contrast value before recording is 0.1 or more, the radial contrast value after recording is 0.2 or more, and the radial contrast ratio before and after recording is 0.3 or more. Therefore, tracking can be stabilized, and thus a phase change type optical recording medium in which track deviation is unlikely to occur is produced, and errors during recording / reproduction can be reduced.

In particular, according to the invention of claim 6, the track groove characteristics are set so as to satisfy all of these conditions, so that tracking can be made more stable.
According to the invention of claim 7, the condition of the invention of claim 6 is set by setting the depth of the track groove to 50 to 60 nm and the groove width to 0.3 to 0.6 μm. In addition to being easy and easy to manufacture, tracking can be made more stable. Further, according to the invention of claims 8, 9, and 10, the main component material of the recording layer formed on the substrate contains at least Ag, In, Sb, Te, or the refractive index of the substrate material. 1.5 to 1.62
Alternatively, the reflectance of the medium itself is set to 35% or less, and the condition of the invention of claim 6 is set. Therefore, tracking can be stabilized before and after recording.

According to the eleventh aspect of the present invention, since the phase change type optical recording medium having the track groove characteristics set as described above is used as the medium, the push-pull system does not cause tracking deviation. The tracking control can be stably performed, the recording / reproducing operation with few errors can be performed, and the phase-change optical recording medium capable of repetitive recording can be effectively used.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing the dependence of a push-pull value after recording on a groove width and a groove depth according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a track groove structure.

FIG. 3 is a cross-sectional view showing a layer structure of a phase change type optical recording medium.

FIG. 4 is a characteristic diagram showing dependence of a push-pull ratio on a groove width and a groove depth.

FIG. 5 is a characteristic diagram showing the dependence of the radial contrast value before recording on the groove width and groove depth.

FIG. 6 is a characteristic diagram showing the dependence of the radial contrast value after recording on the groove width and the groove depth.

FIG. 7 is a characteristic diagram showing the dependence of the radial contrast ratio before and after recording on the groove width and groove depth.

FIG. 8 is a time chart of a pulse method for explaining the recording power at the time of measurement.

[Explanation of symbols]

 1 phase change type optical recording medium 2 substrate 4 recording layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G11B 7/24 561 8721-5D

Claims (11)

[Claims] 1. A phase-change type optical recording medium characterized in that a push-pull value after recording of track groove characteristics is set within a range of 0.08 to 0.16. 2. A phase-change type optical recording medium characterized in that the push-pull ratio of track groove characteristics before and after recording is set within a range of 0.6 to 1.2. 3. A phase-change type optical recording medium, wherein the radial contrast value before recording of the track groove characteristics is set to 0.1 or more. 4. A phase-change type optical recording medium, characterized in that the radial contrast value after recording of the track groove characteristics is set to 0.2 or more. 5. A phase-change type optical recording medium, characterized in that the radial contrast ratio before and after recording of the track groove characteristics is set to 0.3 or more. 6. Regarding track groove characteristics, the push-pull value after recording is in the range of 0.08 to 0.16, and the push-pull ratio before and after recording is in the range of 0.6 to 1.2. Of the phase change type optical recording medium having a radial contrast value of 0.1 or more, a radial contrast value of 0.2 or more after recording, and a radial contrast ratio of 0.3 or more before and after recording. recoding media. 7. The phase-change optical recording medium according to claim 6, wherein the track groove has a depth of 50 to 60 nm and a groove width of 0.3 to 0.6 μm. 8. The phase change optical recording medium according to claim 6, wherein the main component material of the recording layer formed on the substrate contains at least Ag, In, Sb, and Te. 9. The phase change optical recording medium according to claim 6, wherein the substrate material has a refractive index of 1.5 to 1.62. 10. The phase change type optical recording medium according to claim 6, wherein the reflectance of the medium itself is 35% or less. 11. An optical information recording / reproducing apparatus adapted to perform tracking control by a push-pull method and perform recording, erasing or reproduction of information by converging and irradiating a light beam onto an optical information recording medium, wherein the optical information is recorded. An optical information recording / reproducing apparatus, wherein the phase change type optical recording medium according to any one of claims 1 to 10 is used as a recording medium.