JP3303508B2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for recording or reproducing data by irradiating a laser beam on an optical disk on which address information is recorded every predetermined track.

[0002]

2. Description of the Related Art In recent years, crosstalk between adjacent tracks has been reduced by selecting the optical depth of a guide groove for recording and reproduction as a high-density recording method using a phase-change type optical disk. ) And a groove portion (hereinafter, referred to as a “land portion”) has been proposed as a recording track (see the '93 IEICE Spring Conference C-478, etc.).

[0003]

As described above, when both the groove portion and the land portion are used as the recording tracks, as shown in FIG. It is conceivable to provide an address portion in which the address information is recorded, and to record the address information only in the radial position corresponding to the groove portion from the viewpoint of ease of preparation of the master and readability of the address information. In this case, the address information is formed by pits, and is formed in advance together with the groove when the optical disc is formed. In the figure, 20G
Reference numerals 20L and 20L denote groove portions and land portions constituting the recording portion, respectively, and 20P denotes pits as address information.

In this case, when recording and reproduction are performed by irradiating the groove portion 20G with a laser beam, the address information pit 20P can be irradiated with the laser beam, so that the address information can be reproduced. When recording / reproducing is performed by irradiating a laser beam, there is a disadvantage that the address information cannot be reproduced because the address information pits 20P cannot be irradiated by the laser beam.

Although it is conceivable to record address information only at a radial position corresponding to the land portion 20L, similarly, when recording and reproducing are performed by irradiating the groove portion 20G with a laser beam, the laser beam is used. There is a disadvantage that the address information cannot be reproduced because the address information pit 20P cannot be irradiated. A similar inconvenience generally occurs when recording or reproduction is performed by irradiating a laser beam onto an optical disc on which address information is recorded at predetermined tracks.

In view of the above, the present invention provides an optical disc apparatus which can always reproduce address information when recording or reproducing by irradiating a laser beam onto an optical disc on which address information is recorded every predetermined track. It is.

[0007]

An optical disk device according to the present invention has a recording portion and an address portion formed in a circumferential direction,
Grooves and inter-grooves are formed alternately in the radial direction of the recording portion, and both the grooves and the inter-grooves constitute recording tracks, and have the same radial position as the recording tracks of the grooves.
The same as the address track of the
An optical disc device for recording or reproducing by irradiating a laser beam onto an optical disc having address information recorded on one of address portions at a radial position, wherein a first recording track for recording or reproducing has a first recording track. A laser beam irradiating means for irradiating the second recording track radially with respect to the first recording track by an odd multiple of half the pitch of the groove, and irradiating the second recording track with the second laser beam; Same as the first recording track
When the address information is recorded in the address portion at the radial position, the reflected light of the first laser beam is processed to obtain the address information, and the same address as that of the first recording track is obtained .
When address information is not recorded in the address portion at the radial position, address information reproducing means for processing the reflected light of the second laser beam to obtain the address information is provided.

[0008] For example, Les Zabimu irradiation means by the laser beam from the diffraction grating from a single laser light source, the
A first laser beam and a second laser beam are obtained.

[0009]

According to the present invention, a laser beam is irradiated on a recording track on which address information is recorded in parallel with a recording track on which recording or reproduction is performed. Address information can be obtained by processing the reflected light of the recorded recording track.

For example, grooves and inter-grooves are alternately formed in the radial direction of the optical disk, and both the grooves and the inter-grooves constitute recording tracks, and address information is recorded at radial positions corresponding to the grooves. In the case of recording or reproducing in the groove,
The recording position of the address information can be irradiated with a laser beam, and the reflected light can be processed to obtain the address information. In addition, the laser beam irradiation means obtains a plurality of laser beams by a diffraction grating from a laser beam from a single laser light source, so that the laser beam irradiation means can be configured without the need for a plurality of laser light sources and can be realized at low cost. Become.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. This example is an example applied to a magneto-optical disk device. In the figure, reference numeral 1 denotes a spindle motor, and the magneto-optical disk 2 is rotationally driven by the motor 1.

The recording data WD supplied to the input terminal 3a is subjected to error correction encoding by an ECC encoder 4 and modulation (channel encoding) by a modulation circuit 5.
Is supplied to the magnetic head driver 6.
As a result, an external magnetic field corresponding to the recording data is generated from the magnetic head 7, and the recording data is magneto-optically recorded on the recording track of the magneto-optical disk 2 in cooperation with the laser beam from the optical head 8. Although the control line is omitted, the operation of the recording system described above is controlled by the system controller 9.

Here, the details of the structure of the magneto-optical disk 2 of this embodiment will be described. In the magneto-optical disk 2, a guide groove is formed, for example, in a spiral shape over the entire circumference, and both a groove portion (groove portion) and a land portion (inter-groove portion) are used as recording tracks. FIG. 2 shows a cross section of the magneto-optical disk 2, wherein 201 is a polycarbonate substrate, 202
Is a dielectric layer; 203 is a recording layer made of a magneto-optical material;
4 is a dielectric layer, 205 is a reflective film, 206 is a protective film, 20
7 is a molded guide groove. In this case, the guide groove 2
07 is the groove portion 20G, and the space between the guide grooves 207 is the land portion 20L. In this case, the depth of the groove portion 20G is set so that the amount of crosstalk from an adjacent track during reproduction of the groove portion 20G or the land portion 20L is minimized.

An address portion for recording address information such as a track number and a sector number is provided in the circumferential direction in addition to the recording portion, and only at a position in a radial direction (disc radial direction) corresponding to the groove portion 20G. The address information is recorded (see FIG. 8). In this case, the address information is formed by the pits 20P and is formed together with the groove 20G when the magneto-optical disk 2 is formed.

FIG. 3 shows an example of the configuration of the optical system of the optical head 8.
Is shown. Reference numeral 80 denotes a semiconductor laser.
The laser beam from the laser 80 is
G) 81. Then, the light is emitted from the diffraction grating 81.
0th order light (main beam) L ₀And ± 1st order light (sub beam
M) L₊₁, L_-1Are the beam splitter 82 and
Through the objective lens 83 and on the recording layer of the magneto-optical disk 2
Irradiated. In this case, the zero-order light L₀And ± 1st order light
L₊₁, L_-1On the recording layer of the magneto-optical disk 2
Central spot P₀And side spot P₊₁, P_-1age
To form an image. Central spot P₀And side spot P₊₁,
P_-1The radial distance between the optical axis and the
By adjusting the rotation of the grid 81, the guide groove 207 (glu
The pitch is set to be half of the pitch of the
You.

The spot P on the magneto-optical disk 2₀,
P₊₁, P_-1Light Lr reflected from₀, Lr ₊₁, Lr_-1Is
After passing through the objective lens 83, respectively, the beam splitter 8
2 reflected by Wollaston prism (polarization plane detection pre
The Wollaston prism 84
And the reflected light Lr₀, Lr₊₁, Lr_-1Each of three types
Separated into laser beams.

FIG. 4 shows a specific configuration example of the Wollaston prism 84. The prism 84 includes a first right-angle prism 84a and a second right-angle prism 8 made of quartz.
4b are joined. In this case, the prism 84
The optical axis Axb of b is set to be inclined by 45 ° with respect to the optical axis Axa of the prism 84a.

In such a configuration, since the quartz has two different refractive indices in relation to the polarization plane of the incident light, the prism 84a has a polarization plane Ppo inclined by 45 ° with respect to its optical axis Axa. When the linearly polarized light La having the optical axis Axa is incident on the prism 84a as shown in FIG.
Component Lb1 having a polarization plane perpendicular to the optical axis Ax
separated into a polarization component Lb2 having a polarization plane parallel to a,
Further, in the prism 84b, the polarization component Lb1 is changed to the optical axis Axb.
Polarization component Lc1 and polarization axis Ax having a polarization plane parallel to
b is separated into a polarization component Lc2 having a polarization plane perpendicular to the optical axis Ax.
polarization component Lc3 having a polarization plane parallel to b and optical axis A
The light is separated into a polarization component Lc4 having a polarization plane perpendicular to xb.

Here, the polarized light components Lc1 and Lc2 are obtained by separating the polarized light component Lb1 having a plane of polarization perpendicular to the optical axis Axa of the prism 84a from the linearly polarized light La. Is 1/4 of the above. On the other hand, the polarization components Lc3 and Lc4 are linearly polarized light Lc.
a, which is obtained by separating a polarization component Lb2 having a polarization plane parallel to the optical axis Axa of the prism 84a,
Each light amount is １ ／ of the linearly polarized light La. Then, the exit angles of the polarization components Lc2 and Lc3 from the prism 84b are equal. As a result, the three laser beams L
i, Lm, and Lj are obtained separately.

Returning to FIG. 3, reflected light Lr ₀ , Lr ₊₁ , L
r _-1 is the prism 8 of the Wollaston prism 84
4a, the polarization plane is set to be inclined by 45 ° with respect to the optical axis Axa when there is no rotation (Kerr rotation) of the polarization plane in the recording layer of the magneto-optical disk 2 (FIG. 4 (see the relationship between the polarization plane Ppo of the linearly polarized light La and the optical axis Axa). As a result, similarly to the linearly polarized light La described above, the three laser beams Li ₀ and L 3 are generated from the reflected light Lr _0.
m ₀ , Lj ₀ are obtained separately, and three laser beams Li ₊₁ , Lm ₊₁ , Lj ₊₁ are obtained separately from the reflected light Lr _{+ 1} , and three laser beams Li ₊₁ , Lm ₊₁ , Lj ₊₁ are obtained from the reflected light Lr ₋₁ . Laser beam Li ₋₁ , Lm
_-1 and Lj _-1 are obtained separately.

Here, the polarization plane of the reflected light Lr ₀ slightly rotates clockwise or counterclockwise according to the direction of magnetization of the recording film of the magneto-optical disk 2, and the laser beams Li ₀ , L
The magnitude of the light quantity j ₀ depends on the direction of magnetization of the recording film of the magneto-optical disk 2. Therefore, the laser beam Li
_The signals corresponding to the magneto-optically recorded data can be obtained by detecting the light amounts ₀ and Lj ₀ and taking the difference. Further, even if the polarization plane of the reflected light Lr ₀ rotates, the laser beam L
Since the light amount of m ₀ does not change, a signal corresponding to the data recorded in the pit can be obtained by detecting the light amount.

[0022] Incidentally, the plane of polarization of the reflected light Lr ₊₁ and Lr _-1 also slightly rotated clockwise or counterclockwise direction according to the magnetization direction of the recording film of the same the optical disk 2 and the reflected light Lr ₀ described above Therefore, the laser beams Li ₊₁ , Lm ₊₁ , Lj ₊₁ obtained by separating the reflected lights Lr ₊₁ and Lr _-1 are obtained.
The same can be said for the laser beams Li ₀ , Lm ₀ , and Lj ₀ with respect to Li ₋₁ , Lm ₋₁ , and Lj ₋₁ .

The nine laser beams Li ₀ , Lm ₀ , Lj ₀ , Li ₊₁ , L emitted from the Wollaston prism 84
Each of m ₊₁ , Lj ₊₁ , Li _-1 , Lm _-1 , and Lj _-1 is incident on a photodetector 86 composed of, for example, a photodiode via a cylindrical lens 85.

FIG. 6 shows the structure of the photodetector 86.
The photodetector 86 includes photodetectors a1 to a4 forming a four-segment detector and a photodetector b forming a two-segment detector.
1, b2, a photodetector c1, which constitutes a two-divided detector
c2, a light detection unit d and a light detection unit e. The laser beams Li ₀ , Lm ₀ , and Lj ₀ are applied to the light detection units d, a1 to a4, and e, respectively, and the laser beams Lm _{+ 1} are applied to the light detection units b1 and b2. , C2 are irradiated with the laser beam Lm _-1 .

Here, the light detectors a1 to a1 of the light detector 86
4, b1, b2, c1, c2, d, e output signals
Each S_a1~ S_a4, S_b1, S_b2, S_c1, S_c2, S_d, S_eWhen
Then S_d-S_eCalculation of the recorded data
The signal RFMO is obtained and (S _a1+ S_a3)-(S_a2+
S_a4) By the astigmatism method during recording and reproduction.
The focus error signal FE is obtained, and ｛(S_a1+ S_a2)-
(S_a3+ S_a4)｝-G ｛(S_b1+ S_c1)-(S_b2+
S_c2) Recording on the groove 20G by the calculation of｝
Tracking error signal by push-pull method during playback
The TEG is obtained, and the land portion 20 is calculated by the operation of -TEG.
Track by push-pull method during recording and reproduction for L
Thus, a switching error signal TEL is obtained.

[0026] In the case of recording and reproducing with respect to grooves 20G, center spot P ₀ described above, the side spots P _+1, P _-1 is in a positional relationship shown in FIG. 7A, the central spot P ₀ The signal ADG corresponding to the address information recorded in the address portion is obtained by the calculation of S _a1 + S _a2 + S _a3 + S _a4 because the pit at the address portion is scanned at the radial position corresponding to the groove portion 20G. . On the other hand, when recording / reproducing on the land portion 20L, the center spot P ₀ , the side spots P ₊₁ , P _-1
7B has a positional relationship as shown in FIG. 7B. Since the side spots P ₊₁ and P _-1 are located at radial positions corresponding to the groove portions 20G and scan the pits of the address portion, S
A signal ADL corresponding to the address information recorded in the address portion by the operation of _b1 + _Sb2 (or _Sc1 + _Sc2 )
Is obtained.

Returning to FIG. 1, signals ADG and ADL corresponding to the address signal obtained from the optical head 8 are supplied to the G-side and L-side fixed terminals of the changeover switch 10, respectively. The changeover of the changeover switch 10 is performed by the controller 9.
Are connected to the G side when recording / reproducing with respect to the groove portion 20G, and are connected to the L side when recording / reproducing with respect to the land portion 20L. A signal corresponding to the address information obtained from the changeover switch 10 is supplied to an address decoder 11, and address data AD obtained by the address decoder 11 is supplied to a controller 9.

The focus error signal FE obtained from the optical head 8 is supplied to the servo circuit 12. In addition, the tracking error signals TEG and TEL obtained from the optical head 8 are
And fixed terminals on the L and L sides. Changeover switch 1
The switching of 3 is controlled by the controller 9 and is connected to the G side when recording / reproducing with respect to the groove portion 20G.
When recording / reproducing with respect to the land portion 20L, it is connected to the L side. The tracking error signal output from the changeover switch 13 is supplied to the servo circuit 12.

The operation of the servo circuit 12 is controlled by the controller 9. The servo circuit 12 performs tracking servo and focus servo of the optical head 8, and also performs seek control based on the address data AD from the address decoder 11. Further, the rotation of the spindle motor 1 is controlled by the servo circuit 12.

The signal RF obtained from the optical head 8
The MO has its frequency characteristics compensated by the equalizer circuit 14, and
After the demodulation processing is performed by the demodulation circuit 15, the signal is supplied to the ECC decoder 16, where the error correction processing is performed. Then, the reproduced data R corrected by the ECC decoder 16 is read.
D is led out to the output terminal 17. Although the control line is omitted, the operation of the above-described reproduction system is controlled by the controller 9. The controller 9 is connected to a display 18 for displaying an operation mode, an operation state, and the like, and operation keys 19 for user operation.

As described above, according to the present embodiment, the groove portion 20
The recording and reproduction with respect to G can be obtained a signal ADG corresponding to the address information recorded in the address unit by processing the reflected light Lr ₀ from the central spot P _0,
On the other hand, at the time of recording / reproducing with respect to the land portion 20L, the reflected light Lr _{+ 1} (or Lr) from the side spot P _{+ 1} (or P- ₁ ).
r _-1 ), a signal ADL corresponding to the address information recorded in the address section can be obtained.
Therefore, the address data AD can always be obtained from the address decoder 11, and recording and reproduction can be favorably performed on both the groove portion 20G and the land portion 20L.

Further, according to the present embodiment, the zero-order light (main beam) L ₀ and the primary light (sub-beams) L ₊₁ , L ₋₁ formed by the diffraction grating 81 from the laser beam from the semiconductor laser 80.
Is efficiently used, so that it can be configured without the need for a plurality of laser light sources, and has the advantage that it can be realized at low cost.

In the above embodiment, the pits 20P as address information are recorded only at the radial positions corresponding to the groove portions 20G, but only at the radial positions corresponding to the land portions 20L. The present invention can be similarly applied to those in which pits 20P are recorded as address information. In this case, at the time of recording / reproducing with respect to the groove section 20, the reflected light Lr _{+ 1} (or Lr- ₁ ) from the side spot P _{+ 1} (or P _{- 1} ) is processed to correspond to the address information recorded in the address section. signal ADG could be obtained, the reflected light L from the center spot P ₀ at the time of recording and reproduction with respect to the land portion 20L
By processing r ₀ , a signal ADL corresponding to the address information recorded in the address section can be obtained, and address data can always be obtained.

In the above embodiment, the address information is recorded in the pit 20P in the address portion. However, the guide groove (groove portion) is meandered according to the address information as in a known mini disk. The present invention can be similarly applied to a device in which address information is recorded in advance. In this case, the address information can be reproduced from the tracking error signal obtained from the groove 20G.

Further, the present invention can be similarly applied to an optical disc on which address information is recorded every predetermined track and which performs recording or reproduction by irradiating a laser beam to the optical disc. In short, a recording track on which address information is recorded is irradiated with a laser beam in parallel with a recording track on which recording or reproduction is performed, and the reflected light from the recording track on which the address information is recorded is processed to obtain the address information. That is all you need to do.

Although the above embodiment is an example in which the present invention is applied to a magneto-optical disk drive, the present invention applies a laser beam to an optical disk in which address information is recorded every predetermined track, such as a phase-change optical disk drive. It is needless to say that the present invention can be similarly applied to an optical disk device that performs recording or reproduction.

[0037]

According to the present invention, an address at the same radial position as the first recording track for recording or reproducing is added.
When address information is recorded in the
Address information is obtained by processing the reflected light of the first laser beam applied to the recording track, and the same radial position as the first recording track for performing recording or reproduction
When no address information is recorded in the address part of
Address information obtained by processing reflected light of a second laser beam applied to a second recording track which is radially away from the first recording track by an odd multiple of half the pitch of the groove portion; Thus, address information can be obtained even if the recording track on which recording or reproduction is performed changes, and recording and reproduction can be performed satisfactorily on any of the recording tracks.

[0038]

In addition, by efficiently using the first and second laser beams formed by the diffraction grating from the laser beam from a single laser light source, the laser light source can be configured without requiring a plurality of laser light sources, It can be realized at low cost.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a main part of the magneto-optical disk of the embodiment.

FIG. 3 is a diagram showing a configuration of an optical system of the optical head.

FIG. 4 is a diagram illustrating a configuration example of a Wollaston prism.

FIG. 5 is a diagram illustrating a state of separation of light rays by a Wollaston prism.

FIG. 6 is a diagram showing a configuration of a photodetector of the optical head.

FIG. 7 is a diagram for explaining an operation of reproducing address information.

FIG. 8 is a diagram illustrating a relationship between a recording unit and an address unit.

[Explanation of symbols]

 2 Magneto-optical disk 7 Magnetic head 8 Optical head 9 System controller 11 Address decoder 12 Servo circuit 20G Groove section 20L Land section 20P Pit 80 Semiconductor laser 81 Diffraction grating 83 Objective lens 84 Wollaston prism 86 Photodetector 207 Guide groove

Claims (2)

(57) [Claims] 1. A recording section and an address section are formed in a circumferential direction.
Grooves and inter-grooves are alternately formed in the radial direction of the recording portion, and both the grooves and the inter-grooves constitute recording tracks, and the recording tracks of the grooves and
Address part of the same radial position or address of the same radial position and the recording track of the land part
An optical disc device for performing recording or reproduction by irradiating a laser beam on an optical disc on which address information is recorded on any one of the sections, wherein a first laser beam is applied to a first recording track for performing the recording or reproduction. A laser beam irradiating unit for irradiating a second laser beam on a second recording track radially away from the first recording track by an odd multiple of half the pitch of the groove, and 1 at the same radial position as the recording track
When address information is recorded in the dress portion , the reflected light of the first laser beam is processed to obtain address information, and the same radial position as the first recording track is obtained.
An optical disk device comprising: address information reproducing means for processing the reflected light of the second laser beam to obtain address information when address information is not recorded in the address portion of the device. 2. The apparatus according to claim 1, wherein the laser beam irradiation means obtains the first laser beam and the second laser beam from a laser beam from a single laser light source by a diffraction grating. An optical disk device as described in the above.