JP2000251281A - Optical recording / reproducing apparatus and optical recording / reproducing method - Google Patents

Abstract

(57) [Summary] [Problem] To surely perform focus control on an optical recording medium of a land-groove recording method. A laser beam emitted from a laser oscillator is split into a main beam and an auxiliary beam by a diffraction grating. These laser beams are reflected by the optical disc 2 and return light is incident on the photodetector 20 via the cylindrical lens 19. A focus error signal is generated from the return light of the main beam and the auxiliary beam incident on the photodetector 20. Recording and reproduction are performed while performing focus control of the main beam based on the focus error signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording / reproducing apparatus and an optical recording / reproducing method for recording and / or reproducing a recording signal on an optical recording medium of a so-called land / groove recording system.

[0002]

2. Description of the Related Art An optical recording medium is a recording medium on which a recording signal is recorded and / or reproduced (hereinafter, referred to as recording / reproducing) by being irradiated with a laser beam of a predetermined wavelength by an optical recording / reproducing apparatus. is there. The optical recording medium includes, for example, a magneto-optical disk and a phase-change optical disk capable of recording and reproducing a recording signal, and a reproduction-only optical disk having a concavo-convex pattern formed according to the recording signal.

[0003] The optical recording / reproducing apparatus has a mechanism for controlling the focus of a laser beam applied to a signal recording surface in order to perform accurate recording / reproducing on a recording track of an optical recording medium. In such a focus control mechanism, for example, an astigmatism method is used as a focus detection method.

In the optical recording / reproducing apparatus, when performing focus control using the astigmatism method, a cylindrical lens is disposed on an optical path of return light which is reflected by a laser beam on a signal recording surface and returns. In addition to intentionally generating large astigmatism,
The return light is configured to be incident on the photodetector.
Then, a focus error signal is generated using the signal output from the photodetector, and the laser light irradiation is controlled based on the focus error signal so that the laser light is focused on the signal recording surface of the optical recording medium. I do.

The photodetector is, for example, as shown in FIG.
The detection pattern is divided into four regions P, Q, R, and S. The photodetector is provided in the optical recording / reproducing apparatus such that when the laser beam is focused on the recording track, the light spot 100 of the return light is projected in a circular shape at the center of the detection pattern. Further, the photodetector is configured to output a signal such as an electric signal in accordance with an area on which the light spot 100 is projected for each of the four divided areas.

At this time, the signal output FE _{C of the} focus error signal is output.
The area of the light detector P, Q, R, S _P, respectively a signal output of the S, S _Q, S _R, when the S _S, is given as shown below (Equation 1).

[0007]

(Equation 1)

On the other hand, in recent years, it has been desired to increase the recording density of the optical recording medium so as to increase the recording density. Therefore, in an optical recording medium,
As shown in FIG. 7, a land 110a and a groove 110b having a physical uneven shape along a recording track are formed on a substrate 110, and the signal recording layer 111 is positioned at both positions of the land 110a and the groove 110b. A so-called land-groove recording method for recording a recording mark 112 corresponding to a recording signal has been proposed.

An optical recording medium on which recording and reproduction are performed by the land-groove recording method is generally formed such that the width between the land 110a and the groove 110b is substantially equal. The groove 110b is formed so that the depth of the groove 110b is λ / 8 to λ / 4 with respect to the wavelength λ of the laser beam used for recording and reproduction.

The land / groove recording method uses a land 110
a, a recording mark 112 recorded on the
Can significantly reduce signal interference (crosstalk) with the recording mark 112 recorded on the recording medium. The land-groove recording method can improve the recording density as compared with a so-called groove recording method in which the recording mark 112 is recorded only on the groove 110b, for example.

[0011]

In the land-groove recording type optical recording medium, the depth of the groove 110b is sufficiently smaller than the wavelength of the laser beam.
It can be considered that the focal positions at the land 110a and the groove 110b are the same. Therefore, the optical recording / reproducing apparatus, when performing focus control on such an optical recording medium, uses the land 110a and the groove 110b.
It is desirable that the focus error signals obtained in the steps (1) and (2) match.

However, in the optical recording / reproducing apparatus, when performing the focus control using the above-mentioned astigmatism method on the optical recording medium on which the recording / reproducing is performed by the land / groove recording method, the optical recording / reproducing apparatus occurs in the groove 110b. The land 110a and the groove 110b are affected by the strong diffracted light.
However, there is a problem that the focus error signals obtained by the above methods are different from each other. Specifically, for example,
As shown in FIG. 8, the focus error signal obtained from the land 110a did not match the focus error signal obtained from the groove 110b.

Therefore, in the conventional optical recording / reproducing apparatus, when performing the focus control of the laser beam on the optical recording medium of the land / groove recording method, the target value of the focus error signal is independently set between the land 110a and the groove 110b. There is a problem that it is necessary to set or provide a separate control circuit, and the circuit configuration becomes complicated.

In the conventional optical recording / reproducing apparatus, when performing recording / reproducing on an optical recording medium of the land / groove recording system, when a recording track to be irradiated with a laser beam is moved, a land 110a and a groove 110b are used. Since the focus error signal fluctuates, it is difficult to discriminate between the land 110a and the groove 110b and perform stable focus control.

Accordingly, the present invention provides an optical recording / reproducing apparatus and an optical recording / reproducing method which can easily and reliably perform stable focus control even when performing recording / reproducing on an optical recording medium of a land-groove recording system. The purpose is to provide.

[0016]

An optical recording / reproducing apparatus according to the present invention has a signal recording layer on a substrate on which lands and grooves are formed along recording tracks, and a recording signal is recorded on both of the lands and grooves. Is an optical recording / reproducing apparatus that performs recording and / or reproduction of a recording signal on an optical recording medium on which recording is performed. A beam irradiation unit;
A focus error signal generating means. Beam irradiation means
The signal recording layer is irradiated with a main beam for recording and / or reproducing a recording signal and two auxiliary beams. The focus error signal generating means is configured to output, among the two auxiliary beams,
A focus error signal for at least one auxiliary beam is generated. The beam irradiation means irradiates the two auxiliary beams at intervals of an odd multiple of the track pitch with the main beam interposed therebetween, and adjusts the focus position of the main beam based on the focus error signal for recording and recording. And / or perform playback.

In the optical recording / reproducing apparatus configured as described above, the output of the focus error signal of the auxiliary beam matches even when the main beam is applied to either the land or the groove. , And reliable focus control can be performed.

The optical recording / reproducing apparatus according to the present invention has a signal recording layer on a substrate on which lands and grooves are formed along recording tracks, and records recording signals on both of the lands and grooves. An optical recording / reproducing apparatus for recording and / or reproducing a recording signal on / from an optical recording medium. Further, it includes a beam irradiation unit and an irradiation position determination unit. The beam irradiation means irradiates the signal recording layer with a main beam for recording and / or reproducing a recording signal and at least one auxiliary beam. The irradiation position determination means determines whether the irradiation position of the main beam is a land or a groove from the phase difference between the push-pull signals of the main beam and the auxiliary beam. The beam irradiating unit irradiates the auxiliary beam to the boundary between the land and the groove, and performs recording and / or reproduction with the main beam based on the determination result of the irradiation position determining unit.

In the optical recording / reproducing apparatus configured as described above, the irradiation position judging means only compares the phase difference between the push-pull signal of the main beam and the push-pull signal of the auxiliary beam, and the irradiation position of the main beam is determined. A land or a groove can be easily and reliably determined.

Further, the optical recording / reproducing method according to the present invention comprises:
A recording signal is recorded and / or recorded on an optical recording medium having a signal recording layer on a substrate on which lands and grooves are formed along recording tracks, and recording signals on both the lands and grooves. This is an optical recording / reproducing method for performing reproduction. Then, a main beam for recording and / or reproducing a recording signal is applied to the signal recording layer, and two auxiliary beams are applied to the signal recording layer at intervals of an odd multiple of the track pitch with the main beam interposed therebetween. Irradiate for. In addition, recording and / or recording is performed while adjusting the focal position of the main beam based on a focus error signal generated from at least one of the two auxiliary beams.
Or perform reproduction.

According to such an optical recording / reproducing method, the output of the focus error signal of the auxiliary beam coincides with the land and the groove even when the main beam is irradiated on the land and the groove. The same focus control method can be applied to this.

In the optical recording / reproducing method according to the present invention, a signal recording layer is provided on a substrate having lands and grooves formed along recording tracks, and recording signals are recorded on both of the lands and grooves. This is an optical recording / reproducing method for recording and / or reproducing a recording signal on an optical recording medium. Then, a main beam for recording and / or reproducing a recording signal is applied to the signal recording layer, and an auxiliary beam is applied to the signal recording layer at a boundary between a land and a groove. Further, based on the result of determining whether the irradiation position of the main beam is a land or a groove from the phase difference of the push-pull signal between the main beam and the auxiliary beam, while adjusting the focal position of the main beam. Perform recording and / or playback.

According to such an optical recording / reproducing method, the irradiation position of the main beam is either a land or a groove only by comparing the phase difference between the push-pull signal of the main beam and the push-pull signal of the auxiliary beam. Can be easily and reliably determined.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings. Hereinafter, an optical disc apparatus 1 as shown in FIG. 1 will be described as an optical recording / reproducing apparatus to which the present invention is applied. The optical disk device 1 is a device that records and reproduces a recording signal on an optical disk 2. Therefore, first, the optical disc 2 will be described.

In the following, as the optical disk 2, a so-called phase-change type optical disk in which a signal recording layer is formed of a phase-change material and recording signals can be rewritten will be described as an example. The present invention is not limited to an optical recording / reproducing apparatus that performs recording / reproducing on a variable optical disc. The optical disc used for the optical recording / reproducing apparatus according to the present invention is, for example, a laser beam which is irradiated on a signal recording layer and a magnetic field is applied to write a magnetic domain, and the magnetic domain is read using a magneto-optical effect. It may be a magnetic disk. Alternatively, a read-only optical disk having pits corresponding to a recording signal as a change in physical shape in the signal recording layer may be used.

As shown in FIG. 2, the optical disc 2 has a signal recording layer 4 and a protective film 5 sequentially laminated on a transparent substrate 3. The optical disk 2 is irradiated with laser light from the side of the main surface 3 a facing the outside of the transparent substrate 3 by the optical disk device 1, and recording / reproduction of a recording signal to / from the signal recording layer 4 is performed. The optical disk 2 is housed in, for example, a disk cartridge (not shown) and is used detachably with respect to the optical disk device 1. However, the optical disk 2 is used integrally with the optical disk device 1 and is not detachable. You may.

The transparent substrate 3 is made of a hard material having a light-transmitting property with respect to laser light, and is formed in a substantially disk shape as a whole. As a material for forming the transparent substrate 3, for example, various resin materials such as a polycarbonate resin, an acrylic resin, a polyolefin resin, and an epoxy resin, and a glass material such as a quartz glass are used. Further, on the transparent substrate 3, groove-shaped grooves 3b are formed in the circumferential direction parallel to each other along the recording track. A region between the adjacent grooves 3b is a land 3c.

The optical disk 2 is configured to record and reproduce recording signals on the signal recording layer 4 along the grooves 3b and the lands 3c. Also, the optical disc 2
The groove 3b and the land 3c are configured to have substantially the same width, the width indicated by the arrow T _p 2 is the track pitch.

The signal recording layer 4 is made of, for example, In-Sb-T
A thin film is formed on the transparent substrate 3 using a phase change material such as an e-based compound or a Ge-Sb-Te-based compound. The optical disc 2 is irradiated with laser light of a predetermined intensity toward the signal recording layer 4 so that the signal recording layer 4
It is configured to cause a phase change between a crystal and an amorphous. In the following description, a part where the phase change has occurred is referred to as a recording mark. The recording signal is recorded on the optical disc 2 by forming a recording mark on a recording track of the signal recording layer 4 according to the recording signal.

The protective film 5 is formed in a thin film on the signal recording layer 4 by, for example, curing an ultraviolet curable resin applied by a spin coater or the like. Since the optical disk 2 includes the protective film 5, it is possible to prevent the signal recording layer 4 from being deteriorated due to oxidation or the like. Further, it is possible to prevent the signal recording layer 4 from being damaged.

The protective film 5 may be formed by containing various lubricants, or by applying various lubricants to the main surface 5a facing outward. Accordingly, when the optical disk 2 is, for example, a magneto-optical disk, and the recording magnetic head provided in the optical disk device 1 is slid over the main surface 5a of the protective film 5, the recording magnetic Wear and heat generation of the head and the protective film 5 can be prevented.

The optical disc 2 may have a structure in which a dielectric layer formed in the form of a thin film is provided on both main surfaces of the signal recording layer 4. Thereby, the durability of the signal recording layer 4 can be improved, and peeling of the signal recording layer 4 from the transparent substrate 3 can be prevented. The dielectric layer is made of, for example, Si ₃ N ₄ , SiN, AlN, Al ₂ O ₃ , AlSiN
O, HfO ₂ , ZnS, ZrO ₂ , Y ₂ O ₃ , MgO, Si
It may be formed into a thin film by using a material such as O ₂ , MgF ₂ or LiF by a thin film forming technique such as various sputtering methods. However, as a material for forming the dielectric layer, a material that has a light-transmitting property with respect to a laser beam incident to perform recording / reproduction of a recording signal, does not transmit oxygen and water molecules, and does not contain oxygen. It is preferable to use SiN, Si ₃ N ₄
Alternatively, it is desirable to use AlN or the like.

Further, the optical disc 2 may have a configuration in which a light reflection layer is provided on the signal recording layer 4 on the side opposite to the side on which the laser beam is incident. Thereby, the optical disc 2 reflects the laser light transmitted through the signal recording layer 4 and makes the laser light incident again on the signal recording layer 4, thereby improving the utilization efficiency of the laser light and efficiently performing recording and reproduction. Further, heat can be prevented from being stored in the signal recording layer 4. As a material for forming the light reflecting layer, it is preferable to use a nonmagnetic metal element or a compound thereof which is a thermally good conductor singly or in combination, and for example, may be formed of Au, Al or the like.

The optical disk device 1 is a device for recording and reproducing recording signals on the optical disk 2 configured as described above. As shown in FIG. 1, the optical disc apparatus 1 includes an optical head 10, a focus error signal generation unit 11, an irradiation position determination unit 12, and a rotation driving unit (not shown) for driving the optical disc 2 to rotate. And a focus position adjusting unit (not shown) for adjusting the focus position of the laser light emitted from the optical head 10.

When recording a recording signal on the optical disk 2, the optical disk device 1 drives the optical disk 2 to rotate by a rotation drive unit, and
A laser beam having a predetermined intensity is made incident from the optical head 10 toward the signal recording layer 4 of the optical disk, and a recording mark corresponding to the recording signal is formed along the recording track. In addition, when reproducing the recording signal recorded on the optical disk 2, the optical disk device 1 drives the optical disk 2 to rotate by the rotation driving unit, and also records the laser light of lower intensity from the optical head 10 than at the time of recording. The recording signal corresponding to the recording mark is reproduced by detecting the return light reflected by the signal recording layer 4 by making the light incident on the layer 4 and utilizing the difference in the reflectance at the portion where the recording mark is formed. I do.

In the optical disk device 1, the optical head 10 is movable in the radial direction of the optical disk 2,
It is configured such that recording and reproduction can be performed at an arbitrary position on a recording track.

The optical head 10 includes a laser oscillator 13 for oscillating laser light of a predetermined wavelength, a collimator lens 14
, A diffraction grating 15, a beam splitter 16, an objective lens 17, a condenser lens 18, a cylindrical lens 19, and a photodetector 20.

The collimator lens 14 and the diffraction grating 15
, The beam splitter 16 and the objective lens 17 are sequentially arranged on the optical path of the laser light emitted from the laser oscillator 13.

When the laser light is emitted from the laser oscillator 13 and enters the diffraction grating 15 via the collimator lens 14, the diffraction grating 15 compares the zero-order light having a large amount of light with the zero-order light. The light is branched into ± primary lights having a small amount of light. In the following description, the 0th-order light is referred to as a main beam, and the + 1st-order light and the -1st-order light are referred to as a first auxiliary beam and a second auxiliary beam, respectively. Since the deviation of the optical axis between the main beam and the two auxiliary beams is very small, these optical paths are shown as the same in FIG.

The main beam and the two auxiliary beams enter the signal recording layer 4 of the optical disk 2 via the beam splitter 16 and the objective lens 17 and are adjusted so as to be focused on the signal recording layer 4. Have been. The two auxiliary beams are incident on the signal recording layer 4 at an interval of an odd multiple of the track pitch with the main beam interposed therebetween.

That is, in the optical disk 2, FIG.
As shown in FIG. 2, a main beam, a first auxiliary beam, and a second auxiliary beam are incident on the signal recording layer 4, and the main spot 21, the first auxiliary spot 22, and the second The auxiliary spot 23 is irradiated on the signal recording layer 4. In FIG. 3, the transparent substrate 3 of the optical disk 2 is omitted.

In FIG. 3, the main spot 21 is irradiated to the position of the land 3c, and the first spot 21 and the second spot 22 are respectively applied to both edges of the land 3c irradiated with the main spot 21. Shows a case in which is irradiated. In this case, the first auxiliary beam 21 and the second auxiliary beam 22 are irradiated with the main beam 20 interposed therebetween at the same interval as the track pitch. The interval between irradiation with the auxiliary beam 22 may be an odd multiple of the track pitch. However, it is desirable that the first spot 21 and the second spot 22 are irradiated on both edges of the recording track irradiated by the main spot 21. Thereby, in the optical disc device 1, the followability of the main spot 21 to the recording track to be recorded / reproduced becomes better.

The main beam and the two auxiliary beams are respectively reflected by the signal recording layer 4 and return light returning through the incident optical path. When the return light passes through the objective lens 17 and is incident on the beam splitter 16, it is reflected in a direction of 90 ° with respect to the incident direction, and is returned to the condenser lens 18 and the cylindrical lens 1.
9 and is incident on the photodetector 20. That is, the condenser lens 18, the cylindrical lens 19, and the photodetector 20 are disposed downstream of the beam splitter 16 on the optical path of the return light.

As shown in FIG. 3, the photodetector 20 is provided with photodetectors 20a, 20b, and 20c for the main beam, the first auxiliary beam, and the second auxiliary beam, respectively. Each of the light detection units 20a, 20b, and 20c has a detection pattern divided into four regions.
That is, the photodetectors 20a, 20b, and 20c are each divided into four areas: areas A, B, C, and D; areas E, F, G, and H; and areas I, J, K, and L. Further, when the main beam and the two auxiliary beams are focused on the recording track, the light detectors 20 detect the light spots 25a, 25b, and 25c of the return light, respectively.
The optical disc device 1 is arranged so that the center of the detection patterns b and 20c is projected at the position of the circle of least confusion.

The photodetector 20 includes a photodetector 20a,
The dividing lines 20b and 20c are arranged such that the direction of the dividing line forms an angle of 45 ° with the generatrix direction of the cylindrical lens 19. Thereby, in the optical disc device 1, when the main beam and the two auxiliary beams are out of focus (hereinafter, referred to as defocus) with respect to the recording track,
Each light spot 25a, 25b, 25c changes into an elliptical shape according to the defocus amount.

Further, the photodetector 20 includes a photodetector 20
Each of a, 20b, and 20c outputs an electric signal according to the area on which the light spots 25a, 25b, and 25c are projected for each of the four divided areas. This output signal is input to the focus error signal generator 11 and the irradiation position determiner 12.

In the focus error signal generator 11, the photodetector 2
A focus error signal is generated based on the output signal input from 0. The focus error signal generation unit 11 is constituted by, for example, various electric circuits and signal processing means such as a microprocessor. The focus error signal generation unit 11 performs various operations on an output signal input from the photodetector 20 to thereby obtain a focus error signal. Generate a signal. Specifically, the light detection units 20a, 20b, 2
0c, four regions A, B, C, D, E, F,
G, H, I, J, K, L signal outputs are S _A ,
_{S B, S C, S D} , S E, S F, S G, S H, S I, S J, S K,
Let S _L be the signal outputs FE ₀ , FE ₁ , F of the focus error signals of the main beam, the first auxiliary beam and the second auxiliary beam.
E ₂ can each be obtained as shown below.

[0048]

(Equation 2)

The signal output FE ₀ of the focus error signal of the main beam
Is an output equivalent to (Equation 1) shown in the above-described conventional optical recording / reproducing apparatus, and fluctuates depending on whether the recording track irradiated by the main spot 21 is the groove 3b or the land 3c. On the other hand, the signal outputs FE ₁ and FE ₂ of the focus error signals of the first auxiliary beam and the second auxiliary beam are shown in FIG.
As shown in (1), the output becomes 0 when the defocus amount is 0, regardless of the recording track irradiated by the main spot 21, and each output becomes substantially the same. This is because the first auxiliary spot 22 and the second auxiliary spot 23 are used when the recording track irradiated by the main spot 21 is either the groove 3b or the land 3c.
This is because the light is radiated to the boundary portion between.

The signal outputs FE ₁ and FE ₂ of the focus error signals of the first auxiliary beam and the second auxiliary beam are moved by moving the optical head 10 in the radial direction of the optical disk 2 (seek operation) or the like. When the main beam and the two auxiliary beams traverse the groove 3b and the land 3c of the optical disk 2, as shown in FIG. 5, a sinusoidal variation having an extreme value at the center of the groove 3b and the land 3c is shown. Further, the signal outputs FE ₁ and FE ₂ of the focus error signal have the phase of fluctuation of 18 because the first auxiliary spot 22 and the second auxiliary spot 23 are separated by the same interval as the track pitch.
The phase is shifted by 0 ° and the phases are reversed.

Therefore, the signal amount of the focus error signal FE obtained by synthesizing the signal outputs FE ₁ and FE ₂ of the focus error signal as shown below is doubled, and the optical head 1
The fluctuation at the time of the seek operation of 0 can be offset and reduced.

[0052]

(Equation 3)

However, the signal outputs FE ₁ ,
When the sum of FE _2, as shown below, AGC normalizing the respective signal by the total amount (Auto Gain Contro
It is desirable to sum after l). Thereby, the first auxiliary spot 22 and the second auxiliary spot 23
Can be reduced.

[0054]

(Equation 4)

The optical disc apparatus 1 performs the following operation based on the focus error signal FE _AGC output from the focus error signal generator 11.
The amount of defocus of the main spot 21 from the recording track is determined, and recording and reproduction of a recording signal is performed while the focal position adjusting unit adjusts the focal position of the laser light emitted from the optical head 10 to the optical disc 2.

In the optical disk device 1, the groove 3
Regardless of which recording track is recorded on the recording track b or the land 3c, the focus error signal FE _AGC has substantially the same output, so that recording and reproduction can be performed while performing stable and reliable focus control. it can. Also, in the optical disk device 1, the same focus error signal FE _AGC
Focus control based on
There is no need to prepare separate output signals or signal circuits for recording and reproducing on the recording tracks of the groove 3b and the land 3c, and it is possible to perform reliable focus control without requiring a complicated circuit configuration.

In the optical disk device 1, the focal position adjusting unit 11 is configured by combining a coil and a magnet, for example, like the focal position adjusting means provided in a conventional optical recording / reproducing apparatus. The position of the optical head 10 may be adjusted by an appropriate force. The present invention does not relate to the configuration of the focal position adjusting unit 11, but may be configured using the same focal position adjusting means as the conventional one.

In the irradiation position judging section 12, based on the output signal input from the photodetector 20, the position of the main spot 21 irradiated on the signal recording layer 4 of the optical disk 2 is the groove 3b or the land 3c. It is determined whether there is. The irradiation position determination unit 12 includes, for example, various electric circuits and signal processing means such as a microprocessor, and performs determination by performing various calculations on an output signal input from the photodetector 20. . More specifically, first, push-pull signals PP ₀ , PP ₁ , and PP ₂ of the main beam, the first auxiliary beam, and the second auxiliary beam are generated by an operation represented by the following equation.

[0059]

(Equation 5)

These push-pull signals PP ₀ , PP ₁ , P
P ₂ fluctuates when the optical head 10 performs a seek operation, similarly to the focus error signals shown in (Equation 2) to (Equation 4). The irradiation position determination unit 12 compares the phase change between the push-pull signal PP ₀ of the main beam and one of the push-pull signals PP ₁ and PP ₂ of the two auxiliary beams to determine the phase change. Determine whether it is ahead or late. Thereby, in the optical disk device 1, the main spot 21
Can be determined whether the position is the groove 3b or the land 3a.

The optical disk device 1 can record and reproduce data on and from the optical disk 2 of the land-groove recording system.
As described above, the position of the main spot 21 is determined only by comparing the phase difference of the fluctuations of the two push-pull signals.
It is possible to easily and reliably determine whether it is b or the land 3c. Therefore, the optical disk device 1
There is no case where recording and reproduction are performed on an incorrect recording track.

In the above description, (Equation 6)
The defocus amount is determined on the basis of the focus error signal FE _AGC shown in (5). For example, the focus error signal FE shown in (Formula 5) or the focus shown in (Formula 3) and (Formula 4) The defocus amount may be determined based on _{one of} the error signals FE ₁ and FE ₂ . As a result, the optical disc apparatus 1 outputs substantially the same focus error signal for determination, regardless of which recording track is recorded on the groove 3b or the land 3c. However, by using the focus error signal FE or the focus error signal FE _AGC shown in (Equation 5) and (Equation 6), the fluctuation of the focus error signal is reduced even during the seek operation of the optical head 10 as described above. can do.

The optical disk 2 used for the optical disk device 1 may be an optical recording medium of a land-groove recording system, and is not limited to the above-described configuration.
The optical disc 2 includes, for example, a groove 3b and a land 3c.
However, a minute variation may be provided in the radial direction, and a so-called pre-groove may be formed. Further, the optical disk 2 may be a so-called near-field recording type optical disk in which a laser beam for recording / reproducing is incident from the protective film 5 side instead of the transparent substrate 3 side. Also,
The optical disc 2 may be a so-called multilayer recording type optical disc provided with a plurality of signal recording layers 4 or a so-called double-sided reading type optical disc in which protective films 5 of two optical discs 2 are bonded together. You may.

[0064]

As described above, in the optical recording / reproducing apparatus according to the present invention, the output of the focus error signal of the auxiliary beam coincides even when the main beam is applied to either the land or the groove. Furthermore, simple and reliable focus control can be performed without requiring a complicated circuit configuration. Further, by simply comparing the phase difference between the push-pull signal of the main beam and the push-pull signal of the auxiliary beam, it is possible to easily and reliably determine whether the irradiation position of the main beam is a land or a groove. . Therefore, the optical recording / reproducing apparatus according to the present invention can easily perform stable and reliable recording / reproducing even on an optical recording medium of the land / groove recording system.

Further, according to the optical recording / reproducing method of the present invention, the output of the focus error signal of the auxiliary beam coincides with the land even when the land is irradiated with the main beam. The same focus control method can be applied to the groove. Further, by simply comparing the phase difference between the push-pull signal of the main beam and the push-pull signal of the auxiliary beam, it is possible to easily and reliably determine whether the irradiation position of the main beam is a land or a groove. . Therefore, according to the optical recording / reproducing method of the present invention, stable and reliable recording / reproducing can be performed even on an optical recording medium of the land / groove recording system.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an optical disk device according to the present invention.

FIG. 2 is an enlarged sectional view showing an optical disk used for the optical disk device.

FIG. 3 is a schematic diagram for explaining light spots irradiated on an optical disk by the optical disk device and a light detection unit of a light detector corresponding to each light spot.

FIG. 4 is a focus error signal F in the optical disc device.
FIG. 4 is a diagram showing a variation of E ₁ and FE ₂ with respect to a defocus amount.

FIG. 5 shows a focus error signal F in the optical disc apparatus.
It is a diagram showing a variation with respect to the irradiation position of the auxiliary beams E _1, FE _2.

FIG. 6 is a diagram showing a detection pattern of a photodetector provided in a conventional optical recording / reproducing apparatus.

FIG. 7 is an enlarged perspective view showing an optical disk used for a conventional optical recording / reproducing apparatus.

FIG. 8 is a diagram showing a variation of a focus error signal with respect to a defocus amount in a conventional optical recording / reproducing apparatus.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 optical disk device, 2 optical disk, 10 optical head, 11 focus error signal generation unit, 12 irradiation position determination unit, 13 laser oscillator, 15 diffraction grating, 16 beam splitter, 17 objective lens, 19 cylindrical lens, 2
0 Photodetector

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiichi Tsutsui 6-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F term (reference) 5D118 AA13 BB05 BF02 BF03 CC12 CD02 CF16

Claims (9)

[Claims] An optical recording medium having a signal recording layer on a substrate on which lands and grooves are formed along recording tracks, and recording signals on both of the lands and grooves. An optical recording / reproducing apparatus for performing recording and / or reproduction of a signal beam, comprising: a main beam for recording and / or reproduction of a recording signal; and beam irradiation means for irradiating the signal recording layer with two auxiliary beams; And a focus error signal generating means for generating a focus error signal of at least one of the two auxiliary beams, wherein the beam irradiating means has an odd multiple of a track pitch with the main beam interposed therebetween. Optical recording, wherein recording and / or reproducing are performed while irradiating two auxiliary beams and adjusting a focal position of the main beam based on the focal error signal. Playback device. 2. An optical recording / reproducing apparatus according to claim 1, wherein said focus error signal generating means generates a focus error signal by an astigmatism method. 3. The focus error signal generating means generates the focus error signals of the two auxiliary beams by an astigmatism method, and then combines the two focus error signals. 2. The optical recording / reproducing apparatus according to claim 1, wherein the focus position of the main beam is adjusted based on the focus error signal. 4. An optical recording medium having a signal recording layer on a substrate on which lands and grooves are formed along recording tracks, and recording signals on both the lands and the grooves. An optical recording / reproducing apparatus for performing recording and / or reproduction of a signal beam, comprising: a main beam for recording and / or reproduction of a recording signal; and a beam irradiation unit for irradiating the signal recording layer with at least one auxiliary beam. An irradiation position determination unit that determines whether the irradiation position of the main beam is a land or a groove from the phase difference of the push-pull signal between the main beam and the auxiliary beam, Irradiating the auxiliary beam to the boundary of the groove, and performing recording and / or reproduction with the main beam based on the determination result of the irradiation position determination means. An optical recording / reproducing apparatus characterized by the above-mentioned. 5. An optical recording medium having a signal recording layer on a substrate on which lands and grooves are formed along recording tracks, and recording signals on both the lands and grooves. An optical recording / reproducing method for performing recording and / or reproduction of an optical signal, comprising: irradiating a main beam for recording and / or reproducing a recording signal to the signal recording layer; Irradiating the signal recording layer with two auxiliary beams at double intervals, and adjusting a focal position of the main beam based on a focus error signal generated from at least one of the two auxiliary beams. An optical recording / reproducing method characterized by performing recording and / or reproducing while performing. 6. The optical recording / reproducing method according to claim 5, wherein the focus error signal is generated from at least one of the two auxiliary beams by an astigmatism method. 7. The optical recording / reproducing method according to claim 5, wherein said focus error signal is a signal obtained by combining two focus error signals respectively generated from said two auxiliary beams. 8. The optical recording / reproducing method according to claim 7, wherein the two focus error signals are respectively generated from the two auxiliary beams by an astigmatism method. 9. An optical recording medium having a signal recording layer on a substrate on which lands and grooves are formed along recording tracks, and recording signals on both the lands and grooves. An optical recording / reproducing method for recording and / or reproducing a signal, comprising: irradiating a main beam for recording and / or reproducing a recording signal onto the signal recording layer, and applying lands and grooves to the signal recording layer. Irradiating an auxiliary beam to the boundary of the main beam, based on the result of determining whether the irradiation position of the main beam is a land or a groove from the phase difference of the push-pull signal between the main beam and the auxiliary beam, An optical recording / reproducing method, wherein recording and / or reproducing is performed while adjusting a focal position of a beam.