JP2003303423A - Optical information recording medium and optical information reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reproduction-only optical information recording medium wherein even when recorded information is directly read as a recording signal, the recording of the read signal on the other disk is inhibited, and its reproducing method. <P>SOLUTION: A pit having two kinds of depths D1, D2 is formed on a substrate and, when the wavelength of light to reproduce the pit is λ, and the refractive index of an optical disk substrate is n, 3λ<16n<D1<5λ/16n and λ/16n<D2<3λ/16n are satisfied. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium capable of preventing illegal copying of digital signals, and an optical information reproducing method for reproducing information recorded on the optical information recording medium.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 2001-76347 discloses that two kinds of pits are defined to have a depth such that both an RF signal and a PushPull signal can be detected. However, Japanese Patent Laid-Open No. 2001-7634
In JP-A-7, one pit is defined to have a depth at which only an RF signal can be detected, and the other pit is PushP.
There is no disclosure of defining the depth at which only the ull signal can be detected.

[0003]

When music, images, characters, etc. are represented as digital information signals, the information is copied (copied) in comparison with the case where they are represented as analog information signals due to the characteristics of information transmission. Sometimes there is no deterioration of information. For this reason, it is currently a big copyright issue.
There is a demand for prohibiting or restricting copying (hereinafter, referred to as digital copying) of a digital information signal as it is in the form of the digital information signal. To give an example of the means to realize it, serial copy / copy copy used in mini discs (hereinafter referred to as MD)
There is a management system (hereinafter referred to as SCMS).

In the SCMS, a protect code regarding whether copying is possible is recorded in a part of the digital signal recorded in the MD, and when the MD device makes a copy,
It is a system that attempts to prevent digital copying more than once by referring to a protect code.
That is, if the protect code is written in the data of the TOC area of the MD and the protect code is not protected, the MD can be copied, and when the copy is made, the TOC area of the MD of the copy destination is protected. The protect code of is written. Protect
If the code is protected, it cannot be copied. In this way, more than one digital copy is prevented.

However, in the system such as the above-mentioned SCMS, information (for example, TOC) recorded on the disk is
A protect code is written in the area data), and the device determines whether copying is possible by referring to this protect code, but the data is recorded in a data area different from the TOC area described above. If the recorded information is directly read as a recording signal and recorded on another disc, the protect code will be copied regardless of the content of the protect code, and the copy will be repeated as many times as necessary. Therefore, it is impossible to prevent illegal copying due to copyright.

In the present invention, even if the recorded information is directly read as a recording signal, it is impossible to record the read signal on another disc, and a read-only optical information recording medium and a reproducing method thereof. The purpose is to provide.

[0007]

The invention according to claim 1 is
When pits having two kinds of depths D1 and D2 are formed on the substrate and the wavelength of the light for reproducing the pits is λ and the refractive index of the optical disc substrate is n, 3λ / 16n <D1 <5λ /
The most main feature is an optical information recording medium configured to satisfy 16n and λ / 16n <D2 <3λ / 16n.

According to a second aspect of the present invention, pits having two kinds of depths D1 and D2 are formed on the substrate. When the wavelength of light for reproducing the pits is λ and the refractive index of the optical disc substrate is n, An optical information recording medium configured so as to satisfy D1≈λ / 4n and D2≈λ / 8n is the most main feature.

According to a third aspect of the present invention, pits having two kinds of depths D1 and D2 are formed on the substrate. When the wavelength of light for reproducing the pits is λ and the refractive index of the optical disc substrate is n, 3λ / 16n <D1 <5λ / 16n and 5λ /
An optical information recording medium configured to satisfy 16n <D2 <7λ / 16n is the most main feature.

According to a fourth aspect of the present invention, pits having two kinds of depths D1 and D2 are formed on the substrate. When the wavelength of light for reproducing the pits is λ and the refractive index of the optical disc substrate is n, An optical information recording medium configured to satisfy D1≈λ / 4n and D2≈3λ / 8n is the most main feature.

According to a fifth aspect of the present invention, in the optical information recording medium according to any one of the first to fourth aspects, the pits having the depths D1 and D2 are formed in a concentric circle or spiral shape, and the pits having the depths D1 and D2 are formed. The main feature is an optical information recording medium in which pits are formed on the same track.

According to a sixth aspect of the present invention, in the optical information recording medium according to the fifth aspect, the pit having a depth D1 is composed of main information or main information and sub information necessary for reproducing the main information, and the depth D
The main feature of the optical information recording medium is that the second pit consists of sub information necessary for reproducing the main information.

According to a seventh aspect of the invention, in the optical information recording medium according to the sixth aspect, the sub information necessary for reproducing the main information forming the depth D2 is address information, error correction information and copy protection information. The main feature is an optical information recording medium including at least one of them.

According to an eighth aspect of the present invention, in the optical information recording medium according to the fifth aspect, the pit having the depth D1 is composed of main information and sub information necessary for reproducing the main information, and the main information and the sub information are modulated. The method is different, and there is a depth D2 between the main information and the sub information.
Pit array having a depth D2 between the main information and the sub information and a depth D in the main information from the sub information.
An optical information recording medium having two different pit arrangements is a main feature.

According to a ninth aspect of the present invention, in the optical information recording medium according to any one of the first to fourth aspects, the pits having the depths D1 and D2 are formed in a concentric circle or spiral shape, and the pits having the depth D1 are formed. The main feature of the optical information recording medium is a pit having a depth D2 formed between the formed tracks.

According to a tenth aspect of the present invention, in the optical information recording medium according to the ninth aspect, the pits of depth D1 are main information or main information and sub-information necessary for reproducing the main information, and pits of depth D2. The main feature is an optical information recording medium consisting of sub information necessary for reproducing the main information.

According to an eleventh aspect of the present invention, in the optical information recording medium of the tenth aspect, the sub information necessary for reproducing the main information forming the depth D2 is address information, error correction information and copy protection information. The main feature is an optical information recording medium including at least one of them.

According to a twelfth aspect of the present invention, in the optical information reproducing method of irradiating the optical information recording medium of the fifth aspect with a laser and detecting the reflected light thereof, the detector for detecting the reflected light is a laser traveling direction. Is divided into two, the output signals from the two-divided detector are A and B, the pit information of the depth D1 is detected by the RF signal (A + B) of the output signal, and the output signal Depth of TPP signal (A-B)
The most important feature is the optical information reproducing method for detecting the pit information of No. 2.

According to a thirteenth aspect of the present invention, in the optical information reproducing method of irradiating the optical information recording medium according to the eighth aspect with a laser and detecting the reflected light, a signal of a depth D2 is obtained by a signal from a pit having a depth D2. Judging whether the pit of depth D1 which is continuously reproduced to the pit is the main information or the sub information,
The most important feature is an optical information reproducing method for switching to demodulation corresponding to each information modulation method.

According to a fourteenth aspect of the present invention, in the optical information reproducing method of irradiating the optical information recording medium according to the ninth aspect with a laser and detecting the reflected light thereof, the detector for detecting the reflected light is a laser traveling direction. Is divided into two parts in a direction perpendicular to, and the output signals from the two-part detector are A and B, and the pit information of the depth D1 is detected by the RF signal (A + B) of the output signal. , The RPP signal (A-
The most important feature is the optical information reproducing method for detecting the pit information of depth D2 in B).

In the present invention, the optical information recording medium is composed of pits of two kinds of depths, and one pit depth is defined so that the signal cannot be recorded on the recording disk. That is, one pit is defined to have a depth that can detect only the RF signal, and the other pit is Pus.
The depth is defined so that only the hPull signal can be detected.
By the way, in reproducing an optical information recording medium having a recording layer of a phase change material or an organic dye material, a signal is reproduced by irradiating a laser on the recording layer and detecting a change in reflected light amount, that is, an RF signal. It is theoretically impossible to record the recording pits detected by the PushPull signal on the optical information recording medium having the recording layer of the phase change material or the organic dye material. Therefore, there is no recordable optical information recording medium for copying the read-only optical information recording medium having the pits detected by the PushPull signal as in the present invention.
Unauthorized copying can be fundamentally prevented.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 8 shows the relationship between the pit depth, the RF signal, and the PushPull signal. When the wavelength of the light for reproducing the pits is λ and the refractive index of the optical disk substrate is n, the RF signal amplitude has the maximum value when the pit depth is λ / 4n, and the PushPull signal amplitude has the pit depth of λ / Since the maximum value is taken at 8n, the vertical axis in FIG. 8 is standardized with each maximum value being 1. Pus
Since the polarity of the hPull signal is inverted at the pit depth λ / 4n as a boundary, in order to show that, λ / 4 is shown in FIG.
The value of the PushPull signal is made negative at a pit depth of n to λ / 2n.

In the embodiment according to claim 1, 3λ / 1
6n <D1 <5λ / 16n and λ / 16n <D2 <3λ
/ 16n. From Figure 8, the pit of depth D1 is R
The F signal is large, the absolute value of the PushPull signal is small, and the pit at the depth D2 has a small RF signal and PushP.
It can be seen that the absolute value of the ull signal becomes large.

The aspect according to claim 2 defines a range more preferable than the pit depth range of the aspect according to claim 1. That is, D1≈λ / 4n and D2≈λ /
8n. It can be seen from FIG. 8 that the pit having the depth D1 has the maximum RF signal and the absolute value of the PushPull signal has the minimum, and the pit having the depth D2 has the maximum absolute value of the PushPull signal.

In the embodiment according to claim 3, 3λ / 1
6n <D1 <5λ / 16n and 5λ / 16n <D2 <7
λ / 16n. From FIG. 8, the pit of depth D1 has a large RF signal and the absolute value of the PushPull signal becomes small, and the pit of depth D2 has a small RF signal and is Push.
It can be seen that the absolute value of the Pull signal increases.

In the form according to claim 4, a range more preferable than the pit depth range of the form according to claim 3 is defined. That is, D1≈λ / 4n and D2≈3λ
/ 8n. From Figure 8, the pit with depth D1 is RF.
It can be seen that the signal has the maximum value and the absolute value of the PushPull signal becomes the minimum, and the pit at the depth D2 has the maximum absolute value of the PushPull signal.

The PushPull signal detected by the pit having the depth D2 differs depending on the positional relationship with the pit having the depth D1.

In the embodiment according to claim 5, the depth D1
Since the pit of D2 and the pit of D2 are on the same track, the pit of depth D2 is Tangent Push Pull
(Hereinafter TPP) signal is detected.

According to the fifth aspect of the invention, the track center is easily tracked because it is composed of one track, and it is easy to prevent the increase of the jitter of the RF signal due to the tracking deviation.

In the embodiment according to claim 9, the depth D1
Since there is a pit of depth D2 between the pit tracks of
Radial Push Pull is the pit at depth D2.
(Hereinafter, RPP) signal is detected.

According to the ninth aspect, it is difficult to detect the RF signal from the pit having the depth D2. Also, in terms of recording capacity, the depth D is larger than that of the embodiment according to claim 5.
It is advantageous that the two pits are formed between the tracks of the pits having the depth D1.

A twelfth aspect is a reproducing method of the optical information recording medium according to the fifth aspect.

FIG. 1 shows the arrangement of detectors, and FIG. 2 shows detection signals. As shown in FIG. 1, since the detector 1 is divided into two light receiving elements 2a and 2b in the circumferential direction, when the center of the pit having the depth D2 is tracked, the TPP signal is detected at the edge of the pit. . The polarity of the TPP signal is inverted at the entrance and exit of the pit. Further, the polarity of the TPP signal is inverted between the form according to claims 1 and 2 and the form according to claims 3 and 4. The TPP signal in FIG. 2 shows an example thereof.

RF signal binarization and TP shown in FIG.
The P signal binarized signal is a signal processed by a circuit as shown in FIGS. The binarization of the RF signal is a signal processed by the equivalent circuit 4 and the binarization circuit 5 of FIGS.
The TPP signal binarization is a signal obtained by combining the signals processed by COMP + 6 and COMP-7. More specifically, COMP + 6 detects the positive part of the TPP signal and
Binarization is performed by COMP-7 by detecting the negative part of the TPP signal in COMP-7. Then, the signal obtained by synthesizing the signal obtained by inverting the polarity of the signal processed by COMP-7 and the signal processed by COMP + 6 becomes the signal for binarizing the TPP signal in FIG.

According to the sixth and seventh aspects, the pit having the depth D1 is the main information, and the pit having the depth D2 is the sub information. Particularly, in the form according to claim 7, the sub information is made up of one of address information, error correction information and copy protection information. As shown in FIG. 5, sub information can be obtained by finally demodulating the TPP signal in the sub information demodulation circuit 8. The sub information is processed by the control DSP (digital signal processor) 9, the error correction information and the copy protection information control the main information demodulation circuit 10, and the address information controls the servo circuit 11. Even if the sub information is copied to the recording optical information recording medium, the recorded signal is detected by the RF signal, so that the recording optical information recording medium cannot be controlled and the main information is also reproduced. I can't.

Also, in the case where the optical information recording medium is composed of pits having the depth D2, illegal copying can be prevented. However, the recording density of the pits of the depth D1 at which the RF signal becomes maximum as in the conventional case can be made larger than that of the pits of the depth D2. Therefore, when considering a large-capacity optical information recording medium, it is better to use the pits having the depth D1 as the main information and the pits having the depth D2 as the sub-information as in the embodiments according to claims 6 and 7.

According to the eighth and thirteenth aspects, both the main information and the sub information are formed by pits having the depth D1. In the recent optical information recording media, it is required to increase the capacity of not only the main information but also the sub information. Therefore, the pits that can be detected by the RF signal are more advantageous in terms of capacity. At this time, in order to prevent illegal copying, the modulation method of the main information and the sub information is changed, and when the laser reproduces the information, the depth is used as a signal for identifying whether the information is the main information or the sub information. Use the pit of D2. Two kinds of pit arrangement of the depth D2 are sufficient. That is, it is sufficient to identify two types of information that is continuous with the depth D2, that is, main information or sub information.

As shown in FIG. 6, the switching circuit 1 is operated after the TPP signal is detected from the pit having the depth D2 and binarized.
2 is signaled. In the switching circuit 12, the RF signal continuously reproduced from the TPP signal is sent to the main information demodulation circuit 10 when it is the main information and to the sub information demodulation circuit 8 when it is the sub information. If it is copied illegally, the TPP signal is not detected and the method of demodulating the RF signal is unknown, so it is impossible to reproduce.

A fourteenth aspect is a reproducing method of the optical information recording medium according to the ninth aspect. FIG. 3 shows the arrangement of detectors, and FIG. 4 shows the detection signal. Detector 1 as shown in FIG.
Since the light receiving elements 3a and 3b are divided into two in a direction different from the above by 90 ° in the circumferential direction, the RPP signal is detected when the pit having the depth D2 is in the spot of the laser. The actual tracking is performed by tracking the center of the pit of depth D1 when only the pit of depth D1 is used.
When there are pits of 1 and D2, tracking is performed from the center of the pit of depth D1 to the pit of depth D2. When the form according to claims 1 and 2 and claims 3 and 4
In the case of the above form, the polarity of the RPP signal is inverted. The RPP signal in FIG. 4 shows an example thereof.

RF signal binarization and RP shown in FIG.
The P signal binarized signal is a signal processed by a circuit as shown in FIG. The RF signal binarization and the RPP signal binarization are signals processed by the equivalent circuit 4 and the binarization circuit 5 in FIG.

According to the tenth and eleventh aspects,
The pit having the depth D1 is used as the main information, and the pit having the depth D2 is used as the sub information. Particularly, in the embodiment according to claim 11, the sub information is made up of one of address information, error correction information and copy protection information. As shown in FIG. 7, sub information can be obtained by finally demodulating the RPP signal in the sub information demodulation circuit 10. Sub information is a control DSP (digital signal processor)
9, the error correction information and the copy protection information control the main information demodulation circuit 10, and the address information controls the servo circuit 11. Even if the sub information is copied to the recording optical information recording medium, the recorded signal is detected by the RF signal, so that the recording optical information recording medium cannot be controlled and the main information is also reproduced. I can't.

Even when the optical information recording medium is composed of pits having the depth D2, illegal copying can be prevented. However, the recording density of the pits of the depth D1 at which the RF signal becomes maximum as in the conventional case can be made larger than that of the pits of the depth D2. Therefore, when a large-capacity optical information recording medium is considered, the depth D1 is the same as in the embodiments according to claims 10 and 11.
It is better to use the pit of No. 2 as the main information and the pit of depth D2 as the sub information.

[0043]

EXAMPLES The present invention will now be described in more detail with reference to examples.

Example 1 A laser having a wavelength of 650 nm and N
An optical disc made of PC (polycarbonate) reproduced by a pickup having an objective lens of A = 0.6 will be described. Since the refractive index n of the PC is about 1.51, the pit 1 with a depth of 81 to 135 nm is formed on the PC.
And pits 2 of 27 to 81 nm are formed on the same track with a track pitch of 0.74 μm. Preferably about 1 depth
Pits of 08 nm and about 54 nm are good. Further, the forms according to claims 3 and 4 may be adopted. The detector 1 is composed of four light receiving elements a, b, c, and d in the circumferential direction. Pit 1
And DPD (D
differential Phase Detecti
on) method is used. When the servo control is performed so that the DPD signal becomes zero, the laser irradiates the center of the pit. DP
Since the D signal does not depend on the pit depth, pit 1
And tracking of pit 2 is possible. RF signal is used to detect pit 1 and T is used to detect pit 2.
Use the PP signal. Each signal is obtained by processing the signals from the four-division detector as follows. DPD = (a + d)-(b + c) RF = (a + b + c + d) TPP = (b + d)-(a + c)

Since the signal of pit 2 is detected by the TPP signal, it is not copied. Therefore, if a signal required for reproduction such as address information, error correction information, and copy protection information is formed in the pit 2, illegal copying can be prevented.

[Embodiment 2] A laser having a wavelength of 650 nm and N
An optical disc made of PC (polycarbonate) reproduced by a pickup having an objective lens of A = 0.6 will be described. Since the refractive index n of the PC is about 1.51, the pit 1 with a depth of 81 to 135 nm is formed on the PC.
And pits 2 of 27 to 81 nm are formed on the same track with a track pitch of 0.74 μm. Preferably about 1 depth
Pits of 08 nm and about 54 nm are good. Further, the forms according to claims 3 and 4 may be adopted. The detector 1 is 4 as shown in FIG.
It is divided. In order to track pit 1 and pit 2, DPD (Differential P
The Hase Detection method is used. When the servo control is performed so that the DPD signal becomes zero, the laser irradiates the center of the pit. Since the DPD signal does not depend on the pit depth, it is possible to track pit 1 and pit 2. Use RF signal to detect pit 1,
Use the TPP signal to detect pit 2. Each signal is obtained by processing the signal from the four-divided detector 1 as follows. DPD = (a + d)-(b + c) RF = (a + b + c + d) TPP = (b + d)-(a + c)

At this time, the main information is recorded in the pit 1 by 8/16 modulation, and the sub information is recorded by EFM modulation. A signal for switching the modulation method is recorded in the pit 2. Since the signal of pit 2 is detected by the TPP signal, it is not copied. Therefore, in the case of illegal copying, since there is no information on the demodulation method after binarizing the RF signal of the pit 1, it cannot be reproduced and illegal copying can be prevented.

[Embodiment 3] A laser having a wavelength of 650 nm and N
An optical disc made of PC (polycarbonate) reproduced by a pickup having an objective lens of A = 0.6 will be described. Since the refractive index n of the PC is about 1.51, the pit 1 with a depth of 81 to 135 nm is formed on the PC.
Are formed with a track pitch of 0.74 μm, and pits 2 of 27 to 81 nm are formed between the tracks of pits 1. Pits having a depth of about 108 nm and about 54 nm are preferable.
Further, the forms according to claims 3 and 4 may be adopted. The detector 1 is divided into four as shown in FIG. From the wavelength and NA, the Airy diameter of the laser spot is 0.61 × 650 nm / 0.6
˜660 nm. Therefore, the pit 2 between the tracks of the pit 1 can be sufficiently detected. In order to track pit 1, DPD (Differentialial)
The Phase Detection) method is used. DP
When the servo control is performed so that the D signal becomes zero, the laser irradiates the center of the pit 1. Since the DPD signal is a signal that does not depend on the pit depth, it is possible to track pit 1. The RF signal is used to detect pit 1 and the RPP signal is used to detect pit 2. Each signal is obtained by processing the signal from the four-divided detector 1 as follows. DPD = (a + d)-(b + c) RF = (a + b + c + d) RPP = (a + b)-(c + d)

Since the signal of pit 2 is detected by the RPP signal, it is not copied. Therefore, if a signal required for reproduction such as address information, error correction information, and copy protection information is formed in the pit 2, illegal copying can be prevented.

[Embodiment 4] A laser having a wavelength of 405 nm and N
An optical disc made of PC (polycarbonate) reproduced by a pickup having an objective lens of A = 0.85 will be described. Since the refractive index n of PC is about 1.51, pits 1 with a depth of 50 to 84 nm are formed on the PC.
And pits 2 of 84 to 117 nm are formed on the same track with a track pitch of 0.3 μm. Preferably about 6 depth
Pits of 7 nm and about 101 nm are good. Although the depth of the pit 2 may be in the form according to claims 1 and 2,
According to the third and fourth aspects, it is easy to control the two kinds of pit depths by mastering. Detector 1
Is divided into four as shown in FIG. In order to track pit 1 and pit 2, DPD (Differ
The initial phase detection method is used. When the servo control is performed so that the DPD signal becomes zero, the laser irradiates the center of the pit. Since the DPD signal does not depend on the pit depth, pit 1 and pit 2
Can be tracked. The RF signal is used to detect pit 1 and the TPP signal is used to detect pit 2. Each signal is obtained by processing the signal from the four-divided detector 1 as follows. DPD = (a + d)-(b + c) RF = (a + b + c + d) TPP = (b + d)-(a + c)

Since the signal of pit 2 is detected by the TPP signal, it is not copied. Therefore, if a signal required for reproduction such as address information, error correction information, and copy protection information is formed in the pit 2, illegal copying can be prevented.

[Embodiment 5] A laser having a wavelength of 405 nm and N
An optical disc made of PC (polycarbonate) reproduced by a pickup having an objective lens of A = 0.85 will be described. Since the refractive index n of PC is about 1.51, pits 1 with a depth of 50 to 84 nm are formed on the PC.
Are formed with a track pitch of 0.3 μm, and pits 2 of 84 to 117 nm are formed between the tracks of pits 1. Pits having a depth of about 67 nm and about 101 nm are preferable.
Although the depth of the pit 2 can be set to the form according to claims 1 and 2, it is set to the form according to claims 3 and 4 in which control for forming two types of pit depths by mastering is easy. . The detector 1 is divided into four as shown in FIG. Airy diameter of laser spot is 0.61 × 4 from wavelength and NA
It becomes 05 nm / 0.85-290 nm. Therefore, the pit 2 between the tracks of the pit 1 can be sufficiently detected. In order to track pit 1, DPD (Di
different Phase Detectio
n) method is used. When the servo control is performed so that the DPD signal becomes zero, the laser irradiates the center of the pit 1. DP
Since the D signal does not depend on the pit depth, pit 1
Can be tracked. The RF signal is used to detect pit 1 and the RPP signal is used to detect pit 2. Each signal is obtained by processing the signal from the four-divided detector 1 as follows. DPD = (a + d)-(b + c) RF = (a + b + c + d) RPP = (a + b)-(c + d)

Since the signal of pit 2 is detected by the RPP signal, it is not copied. Therefore, if a signal required for reproduction such as address information, error correction information, and copy protection information is formed in the pit 2, illegal copying can be prevented.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the present invention.

[0055]

According to the present invention, the following effects can be obtained. According to the invention of claim 1, two kinds of depth D
1 and D2 pits are 3λ / 16n <D1 <5λ / 16n
Since λ / 16n <D2 <3λ / 16n,
The signal of the pit of depth D1 is large RF signal,
The absolute value of the Pull signal becomes small, the RF signal of the pit signal of depth D2 is small, and the absolute value of the PushPull signal becomes large.

According to the second aspect of the present invention, pits having two kinds of depths D1 and D2 are D1≈λ / 4n and D2≈λ /.
Since the depth of the pit signal is 8n, the RF signal is maximum in the pit signal of depth D1, and the absolute value of the PushPull signal is minimum, and the absolute value of the PushPull signal is maximum in the pit signal of depth D2.

According to the invention described in claim 3, pits of two kinds of depths D1 and D2 are formed with 3λ / 16n <D1 <5λ / 1.
Since 6n and 5λ / 16n <D2 <7λ / 16n, the pit signal of the depth D1 has a large RF signal and P
The absolute value of the pushPull signal becomes small, and the pit signal of depth D2 has a small RF signal and a large pushPul signal.

According to the invention described in claim 4, pits having two kinds of depths D1 and D2 are D1≈λ / 4n and D2≈3λ.
/ 8n, so the pit signal of depth D1 is RF
The signal has the maximum value, the absolute value of the PushPull signal becomes the minimum, and the pit signal of the depth D2 has the maximum absolute value of the PushPull signal.

According to the fifth aspect of the invention, since the two types of pits are on the same track, tracking can always be performed at the center of the two types of pits, and a stable RF signal and PushPull signal can be detected. .

According to the invention of claim 6, the recording density of the pits of the depth D1 is high, but the recording density of the pits of the depth D2 is low. If an optical information recording medium is formed only with pits of depth D2, illegal copying can be easily prevented, but the amount of information will be reduced. In the invention described in claim 7, the main information having a large amount of information is a pit having a depth D1, and a part of the sub information having a small amount of information is a pit having a depth D2. Compatibility is possible.

According to the invention described in claim 7, the sub information comprises any one of the address information, the error correction information and the copy protection information, and the sub information is necessary for reproducing the main information. Therefore, it is impossible to reproduce the main information by copying only the main information, and it is possible to prevent illegal copying.

According to the invention of claim 8, the recording density of the pits of the depth D1 is high, but the recording density of the pits of the depth D2 is low. If an optical information recording medium is formed only with pits of depth D2, illegal copying can be easily prevented, but the amount of information will be reduced. Instead of using the pits having a large recording density and the depth D1 for the main information and the sub information, the modulation method of the main information and the sub information is changed, and a signal of the depth D2 between the main information and the sub information is used as a signal notifying the switching of the modulation method. Form a pit. Since it is sufficient to recognize whether the continuous information is the main information or the sub information for the pits of the depth D2, two types of pit arrangements are sufficient, and there is no problem even if the recording density is small. In the invention described in claim 8, by forming two kinds of pits in this way, it is possible to achieve both the amount of information and the prevention of illegal copying.

According to the invention described in claim 9, since the tracks of the pit of the depth D1 and the pit of the depth D2 are different, the depth D
When tracking is performed on one pit, the influence of the RF signal from the pit having the depth D2 can be reduced.

According to the invention of claim 10, the depth D1
The recording density of the pits is high, but the recording density of the pits of depth D2 is low. If an optical information recording medium is formed only with pits of depth D2, illegal copying can be easily prevented, but the amount of information will be reduced. In the invention described in claim 10, the main information having a large amount of information is a pit having a depth D1 and a part of the sub information having a small amount of information is a pit having a depth D2. Compatibility is possible.

According to the eleventh aspect of the invention, the sub-information comprises any one of address information, error correction information and copy protection information, and these sub-information are necessary information for reproducing the main information. Therefore, it is impossible to reproduce the main information by copying only the main information, and it is possible to prevent illegal copying.

According to the twelfth aspect of the invention, the depth D1
Detects pits with RF signal and detects pits with depth D2 by TPP
Since it is detected by the signal, the pit with the depth D2 cannot be copied. In other words, the recording medium is basically R
The F signal can be recorded, but the TPP signal cannot be recorded. Therefore, since there is no recording medium for performing illegal copy, illegal copy can be prevented.

According to the invention of claim 13, the depth D2
It is judged whether the pit of depth D1 continuously reproduced from the pit of depth D2 is the main information or the sub information by the signal from the pit of, and the demodulation corresponding to the modulation method of each information is performed. Since the switching is performed, the optical information recording medium having no TPP signal corresponding to the pit of the depth D2 that has been illegally copied cannot be reproduced, and the illegal copy can be prevented.

According to the fourteenth aspect of the invention, the depth D1
The pits are detected by the RF signal and the pits of depth D2 are RPP
Since it is detected by the signal, the pit with the depth D2 cannot be copied. In other words, the recording medium is basically R
The F signal can be recorded, but the RPP signal cannot be recorded. Therefore, since there is no recording medium for performing illegal copy, illegal copy can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a detector used in a reproducing method of an optical information recording medium of the present invention.

FIG. 2 is a diagram showing an example of a detection signal by the detector of FIG.

FIG. 3 is a schematic view showing another example of the detector used in the reproducing method of the optical information recording medium of the present invention.

FIG. 4 is a diagram showing an example of a detection signal by the detector of FIG.

FIG. 5 is a block diagram showing an example of a signal circuit according to the present invention.

FIG. 6 is a block diagram showing another example of the signal circuit according to the present invention.

FIG. 7 is a block diagram showing still another example of the signal circuit according to the present invention.

FIG. 8 is a diagram showing a relationship between a pit depth, an RF signal, and a PushPull signal.

FIG. 9 is a schematic diagram showing another example of a detector.

[Explanation of symbols]

1 detector 2a, 2b Light receiving element 3a, 3b Light receiving element 4 Equalization circuit 5 Binarization circuit 6 COMP + 7 COMP- 8 Sub information demodulation circuit 9 Control DSP 10 Main information demodulation circuit 11 Servo circuit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 20/12 G11B 20/12

Claims (14)

[Claims] 1. A pit having two kinds of depths D1 and D2 is formed on a substrate, and the wavelength of light for reproducing the pit is λ,
3λ / 16n, where n is the refractive index of the optical disk substrate
<D1 <5λ / 16n and λ / 16n <D2 <3λ / 1
An optical information recording medium, which is configured to satisfy 6n. 2. A pit having two kinds of depths D1 and D2 is formed on a substrate, and the wavelength of light for reproducing the pit is λ,
When the refractive index of the optical disk substrate is n, D1≈λ / 4
An optical information recording medium, characterized in that n and D2≈λ / 8n are satisfied. 3. A pit having two kinds of depths D1 and D2 is formed on a substrate, and the wavelength of light for reproducing the pit is λ,
3λ / 16n, where n is the refractive index of the optical disk substrate
<D1 <5λ / 16n and 5λ / 16n <D2 <7λ /
An optical information recording medium, which is configured to satisfy 16n. 4. A pit having two kinds of depths D1 and D2 is formed on a substrate, and the wavelength of light for reproducing the pit is λ,
When the refractive index of the optical disk substrate is n, D1≈λ / 4
An optical information recording medium characterized in that it is configured to satisfy n and D2≈3λ / 8n. 5. The optical information recording medium according to claim 1, wherein the pits having the depths D1 and D2 are formed in a concentric circle or spiral, and the pits having the depths D1 and D2 are on the same track. An optical information recording medium characterized by being formed. 6. The optical information recording medium according to claim 5, wherein the pits having a depth D1 are main information or main information and sub information necessary for reproducing the main information, and the pits having a depth D2 are for reproducing the main information. An optical information recording medium comprising necessary sub-information. 7. The optical information recording medium according to claim 6, wherein the sub information required for reproducing the main information forming the depth D2 is at least one of address information, error correction information and copy protection information. An optical information recording medium characterized by the above. 8. The optical information recording medium according to claim 5, wherein the pit having the depth D1 is composed of main information and sub information necessary for reproducing the main information, and the main information and the sub information have different modulation methods, There is a pit of depth D2 between the information and the sub information, and the pit arrangement of depth D2 between the main information and the sub information is different from the pit arrangement of depth D2 in the main information from the sub information. A characteristic optical information recording medium. 9. The optical information recording medium according to claim 1, wherein the pits with depths D1 and D2 are formed in a concentric circle or spiral shape, and between the tracks in which the pits with depth D1 are formed. An optical information recording medium, characterized in that a pit having a depth D2 is formed at the depth. 10. The optical information recording medium according to claim 9,
An optical information recording medium characterized in that a pit having a depth D1 comprises main information or main information and sub-information necessary for reproducing the main information, and a pit having a depth D2 comprises sub-information necessary for reproducing the main information. . 11. The optical information recording medium according to claim 10, wherein the sub information required for reproducing the main information forming the depth D2 is at least one of address information, error correction information and copy protection information. An optical information recording medium characterized by the above. 12. The optical information reproducing method for irradiating a laser on the optical information recording medium according to claim 5 and detecting the reflected light thereof, wherein the detector for detecting the reflected light is divided into two in the traveling direction of the laser. The output signals from the two-divided detector are A and B, the RF signal (A + B) of the output signal detects pit information of depth D1, and the TPP signal (A- of the output signal is detected. An optical information reproducing method characterized in that the pit information of the depth D2 is detected in B). 13. An optical information reproducing method for irradiating a laser on the optical information recording medium according to claim 8 and detecting reflected light thereof, wherein the pit of depth D2 is continuously reproduced by a signal from the pit of depth D2. An optical information reproducing method, characterized in that it is determined whether a pit having a depth D1 to be formed is main information or sub-information, and the demodulation is switched to a demodulation corresponding to a modulation method of each information. 14. An optical information reproducing method for irradiating a laser on the optical information recording medium according to claim 9 to detect reflected light thereof, wherein a detector for detecting the reflected light is in a direction perpendicular to a traveling direction of the laser. The output signal from the two-divided detector is A and B, the pit information of the depth D1 is detected by the RF signal (A + B) of the output signal, and the RPP of the output signal is detected. An optical information reproducing method characterized by detecting pit information of a depth D2 by a signal (AB).