JP2002279659A - Optical disk drive - Google Patents

Abstract

(57) [Summary] In a conventional optical disc device, a main beam scans a land track and a groove track due to a difference in reflectivity between land / groove and a difference in physical groove structure shape. Scanning, the reflected light ratio of the main beam and the sub beam changes, and the normal DPP
In the system, there is a problem that a track offset is generated. An optical disc device according to the present invention includes a selection unit that selects one of a first tracking error signal calculation unit and a second tracking error signal calculation unit, and a tracking unit selected by the selection unit. Tracking control means for controlling the main beam to irradiate the land track or the groove track using an error signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical information recording medium.
The present invention relates to an optical disk device that performs tracking by irradiating a laser beam onto an (optical disk) and records and reproduces information.

[0002]

2. Description of the Related Art In recent years, the density of optical discs has been increasing, but as the track pitch of optical discs becomes narrower, it is necessary to perform tracking with high precision. In particular, in the case of a recording / reproducing type optical disc employing land / groove recording,
The presence of a track offset causes a problem of so-called cross-erase that deteriorates information recorded on an adjacent track when recording information, and it is required that the beam spot follow the track center with high accuracy during tracking.

On the other hand, in the configuration of a general optical head mounted on an optical disk device, when the objective lens shifts in the radial direction of the optical disk, that is, when the objective lens shifts, or when the disk is tilted, Since the position of the light spot on the photodetector (PD) that receives the reflected light shifts, an offset occurs in the push-pull signal that is a tracking error signal. As a result, the light beam spot scans a position shifted in the radial direction from the actual track center, causing deterioration of recording characteristics and the above-described cross erase problem.

In order to solve such a problem, a tracking signal detection method called a DPP (Differential Push Pull) method using a three-beam optical system has been proposed.

A conventional tracking signal detection method based on the DPP method will be described with reference to FIGS. In the land / groove recording, as shown in FIG. 9, the light spots S1 and S2 of two sub-beams among the three beams are shifted by a track pitch TP in the track cross direction with respect to the irradiation position of the main beam light spot S0. It is irradiated to the position offset only by.
Light spot S0 of main beam, light spot of two sub beams
The light reflected by S1 and S2 is divided into two photodetectors 201 around the tangential direction of the track shown in FIG.
Detected by 202 and 203. FIG. 11 is a diagram showing an arithmetic processing block of the tracking signal detection method by the DPP method. Photodetectors 201, 202, 203
Are output from the subtractors 301, 302, and 303, respectively.
And the difference signal (push-pull signal) PP0, P
P1 and PP2 are required.

The difference signals PP1 and PP2 corresponding to the light spots S1 and S2 of the sub-beams are supplied to the difference signal PP by the gain adjustment amplifier 304.
1. PP2 is multiplied by G1 so that PP2 has the same amplitude, and added by the adder 305 to obtain an added value (PP1 + G1 * PP2). This added value (PP1 + G1 * PP2) is
Thus, (PP1 + G1 * PP2) is multiplied by G2 so that the difference signal PP0 corresponding to the light spot S0 of the main beam has the same amplitude, and the tracking error signal TE is subtracted from the signal PP0 by the subtractor 307. can get. In this method, when the objective lens is shifted or the disc is tilted, the offset caused by the light spot shift on each photodetector that receives the reflected light occurs in the same phase, so that the offset component can be canceled by the above calculation. is there.

On the other hand, a general recording / reproducing type optical disc has embossed pit information aligned in the radial direction of the disc as shown in FIG. Is divided into zones, and emboss pit information is aligned in the radial direction of the disc in the zone. Generally, the emboss pit information is information such as a sector number, and data recording / reproduction is performed based on the emboss pit information. When the embossed pit information is aligned in the radial direction of such an optical disc, when the embossed pit information is adjacent to the recording data track, it is possible to avoid a problem that the servo characteristics and the recording characteristics are deteriorated due to crosstalk. However, on the other hand, since the position of the embossed pit information is fixed, there is a problem that the format efficiency is poor and the storage capacity cannot be obtained. In order to solve this problem, as shown in FIG. 13, in order to increase the storage capacity, for example, a structure of an optical disk represented by Japanese Patent Application Laid-Open No. 11-259868 has been proposed. In this case, the emboss pit information is not aligned in the radial direction of the disc, but is arranged at various places on the optical disc. Therefore, the emboss pit information exists at a position adjacent to the recording data area of the track. .

However, in land / groove recording, there are differences in the reflectance between lands / grooves and differences in the physical groove structure. Therefore, when the main beam scans the land track and when the groove track scans, the ratio of the reflected light amounts of the main beam and the sub beam changes, and in the normal DPP method, the track offset occurs conversely. There was a problem.

When the tracking control by the DPP method described above is performed on a recording / reproducing type optical disk in which the embossed pit information is not aligned in the radial direction of the disk, the embossed pit information is aligned in the radial direction of the disk. Therefore, when the main beam scans the recording track, the emboss pit information may appear in an adjacent track scanned by one of the sub-beams. In the DPP method, arithmetic processing is performed such that the track offset component is just canceled by adjusting the gain of the reflected light amount. If the irradiation position of the sub-beam spot is applied to the embossed pit information as described above, an average However, there is a problem that the reflected light amount changes and a track offset occurs.

As disclosed in Japanese Patent Application Laid-Open No. 10-3672, the center of the main beam is shifted by 1/4 track pitch.
2. Description of the Related Art There is known an optical disc apparatus that irradiates a book with a sub-beam and applies a predetermined gain to the output of the sub-beam to generate a tracking error signal.

However, since a tracking error signal is always generated by applying a predetermined gain, if there is a difference in the reflectance between the land and the groove and a difference in the shape of the physical groove structure, these effects are eliminated. In this case, it is necessary to adjust the gain in advance, but since there is no way to predict how much difference will occur, there is a problem that the effect cannot be substantially eliminated. Also,
Even if the above-mentioned emboss pit information is applied to an optical disc that is not aligned in the disc radial direction,
Similarly, it is necessary to adjust the gain in advance to eliminate these effects, but since there is no way to predict how much difference will be made, there is a problem that the actual effect cannot be eliminated. is there.

[0012]

As described above, in the conventional optical disk device, land / groove recording is performed.
Due to the difference in the reflectance between the land and the groove and the difference in the shape of the physical groove structure, when the main beam scans the land track and when the groove track scans, the reflected light amount ratio of the main beam and the sub beam. And the normal DPP method has a problem that a track offset is generated on the contrary.

In a conventional optical disk apparatus, a recording / reproducing type optical disk in which embossed pit information is not aligned in the radial direction of the disk has a DPP.
When performing tracking control by the method, the embossed pit information is not aligned in the radial direction of the disk, so when the main beam scans the recording track, the sub-beam on one side scans the adjacent track. May appear embossed pit information. And
In the DPP method, since the calculation processing is performed so that the track offset component is just canceled by adjusting the gain of the reflected light amount, the average reflected light amount due to the irradiation position of the sub-beam spot on the embossed pit information , There is a problem that a track offset occurs on the contrary.

As disclosed in Japanese Patent Application Laid-Open No. 10-3672, the center of the main beam is shifted by 1/4 track pitch.
2. Description of the Related Art There is known an optical disc device that irradiates a book with a sub-beam and multiplies the output of the sub-beam by a predetermined coefficient to generate a tracking error signal.

However, since a predetermined gain is always applied, there is a problem that it is not possible to cope with a difference in reflectance between land and groove or a difference in reflectance due to the presence or absence of embossed pit information.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and in a case where tracking control is applied to an optical disk having a difference in reflectance between lands / grooves and a difference due to a physical groove structure, a track offset due to an objective lens shift. It is an object of the present invention to provide an optical disk device that does not cause the problem.

Further, when tracking control is performed on a recording / reproducing type optical disc in which the embossed pit information is not aligned in the radial direction of the disc, there is an objective lens shift and the embossed pit information is not included in the adjacent track. An object of the present invention is to provide an optical disk device in which a track offset does not occur even when it appears.

[0018]

In order to solve the above-mentioned problems, in an optical disk device of the present invention, land tracks and groove tracks are formed, and an optical disk on which information can be recorded on these tracks is used. An optical disc device for performing recording or reproduction of information by irradiating a main beam, wherein the main beam is irradiated on the land track, and adjacent to both sides of the land track irradiated by the main beam. Irradiating the groove track with a first sub-beam and a second sub-beam, respectively, or in a state where the main beam is irradiated on the groove track, adjacent to both sides of the groove track being irradiated with the main beam. A main beam and a sub-beam irradiating means for irradiating the first and second sub-beams to the land track, respectively, and the main beam. A first light receiving means for receiving reflected light of the main beam from the optical disk, out of the main beam and the sub beam by the sub beam irradiating means;
Second and third light receiving means for respectively receiving reflected light of the sub-beam and the second sub-beam by the optical disc;
A first tracking error signal calculating means for obtaining a first tracking error signal from the first light receiving means and the second light receiving means, the first light receiving means and the third
A second tracking error signal calculating means for obtaining a second tracking error signal from the light receiving means;
A selecting means for selecting which of the tracking error signal calculating means or the second tracking error signal calculating means is to be used, and using the tracking error signal on the side selected by the selecting means, the main beam And a tracking control means for controlling the irradiation of the track or the groove track.

For this reason, the switching does not cause a track offset even if there is a difference in the reflectance between the land and the groove and a difference in the physical groove structure.

Further, land tracks and groove tracks are formed, information can be recorded on these tracks, and emboss pit information shared by a pair of land tracks and groove tracks is provided. The embossed pit information shared with another set of land tracks and groove tracks is recorded or reproduced by irradiating a main beam on an optical disc arranged at a different position in the radial direction of the disc. An optical disc device, wherein the main beam is irradiated on the land track, and a first sub beam and a second sub beam are formed on groove tracks adjacent to both sides of the land track irradiated by the main beam. Respectively, or the main beam is irradiated on the groove track. A main beam and a sub-beam irradiating means for irradiating a land track adjacent to both sides of the groove track irradiated with the main beam with a first sub-beam and a second sub-beam, respectively; A first light receiving unit that receives a reflected light of the main beam from the optical disk among the main beam and the sub beam by the sub beam irradiation unit; and a reflection of the first sub beam and the second sub beam by the optical disk. The light receiving each
Second and third light receiving means, first tracking error signal calculating means for obtaining a first tracking error signal from the first light receiving means and the second light receiving means, the first light receiving means, A second tracking error signal calculating unit for obtaining a second tracking error signal from the third light receiving unit; and either the first tracking error signal calculating unit or the second tracking error signal calculating unit. Selecting means for selecting whether or not, using a tracking error signal on the side selected by the selecting means, comprising a tracking control means for controlling the main beam to be irradiated to the land track or the groove track, When the main beam irradiates the land track or the groove track, the main beam is illuminated. The tracking error signal calculation means for obtaining the tracking error signal based on the reflected light of the sub-beam irradiating the track sharing the track with the embossed pit information. It is characterized by.

As a result, no track offset occurs.

In the optical disk, the emboss pit information may be arranged between the groove track and the land track, and the emboss pit information may cause the groove track to protrude toward the land track. It is characterized by comprising.

Further, the first light receiving means and the second, second
The third light receiving means is a light receiving element divided into two in the track tangential direction of the land track or the groove track, and the first tracking error signal calculating means is a difference signal of the output by the first light receiving means. A first subtraction means for generating a difference signal of the output from the second light receiving means, and a first subtraction means for adjusting the gain of the amplitude of the difference signal by the second subtraction means. Gain adjustment means, a difference signal by the first subtraction means,
Subtraction means for subtracting the difference signal from the first gain adjustment means, and the second tracking error signal calculation means comprises a first subtraction for generating a difference signal of the output from the first light reception means. Means, a third subtraction means for generating a difference signal of the output by the third light receiving means, a second gain adjustment means for adjusting the gain of the amplitude of the difference signal by the third subtraction means, It is characterized by comprising subtraction means for subtracting the difference signal by the first subtraction means and the difference signal by the second gain adjustment means.

Further, the first gain adjusting means and the second gain adjusting means have gains G1 and G2 given to the amplitude of the difference signal by the second subtracting means by the first gain adjusting means. G2 is the gain given to the amplitude of the difference signal by the third subtraction means, and R is the total reflected light amount when the main beam irradiates the groove track.
1, the total reflected light amount when the main beam irradiates the land track is R3, the total reflected light amount when the first sub-beam irradiates the land track is R2, and the second sub-beam is the groove track. When the total amount of reflected light upon irradiation is R4, the gain is adjusted so as to satisfy the following relationships: G1 = R1 / R2 and G2 = R3 / R4.

Therefore, under the above conditions, the track offset can be minimized.

Also, land tracks and groove tracks are formed, information can be recorded on these tracks, and emboss pit information shared by a set of land tracks and groove tracks is provided. The embossed pit information shared with another set of land tracks and groove tracks is recorded or reproduced by irradiating a main beam on an optical disc arranged at a different position in the radial direction of the disc. An optical disc device, wherein the main beam is irradiated on the land track, and a first sub beam and a second sub beam are formed on groove tracks adjacent to both sides of the land track irradiated by the main beam. Respectively, or the main beam is irradiated on the groove track. A main beam and a sub-beam irradiating means for irradiating a land track adjacent to both sides of the groove track irradiated with the main beam with a first sub-beam and a second sub-beam, respectively; A first light receiving unit that receives a reflected light of the main beam from the optical disk among the main beam and the sub beam by the sub beam irradiation unit; and a reflection of the first sub beam and the second sub beam by the optical disk. The light receiving each
Second and third light receiving means, first tracking error signal calculating means for obtaining a first tracking error signal from the first light receiving means and the second light receiving means, the first light receiving means, A second tracking error signal calculating unit for obtaining a second tracking error signal from the third light receiving unit; and either the first tracking error signal calculating unit or the second tracking error signal calculating unit. Selecting means for selecting whether or not, using a tracking error signal on the side selected by the selecting means, comprising a tracking control means for controlling the main beam to be irradiated to the land track or the groove track, The selecting means irradiates the main beam with emboss pit information of the land track or the groove track. In this case, the tracking error signal calculating means for obtaining the tracking error signal is selected based on the reflected light of the sub beam irradiating the emboss pit information similarly to the main beam. .

Therefore, no track offset occurs.

Further, in the optical disk, the emboss pit information may be arranged between the groove track and the land track, and the emboss pit information may cause the groove track to protrude toward the land track. It is characterized by comprising.

The first light receiving means and the second and second light receiving means
The third light receiving means is a light receiving element divided into two in the track tangential direction of the land track or the groove track, and the first tracking error signal calculating means is a difference signal of the output by the first light receiving means. A first subtraction means for generating a difference signal of the output from the second light receiving means, and a first subtraction means for adjusting the gain of the amplitude of the difference signal by the second subtraction means. Gain adjustment means, a difference signal by the first subtraction means,
Subtraction means for subtracting the difference signal from the first gain adjustment means, and the second tracking error signal calculation means comprises a first subtraction for generating a difference signal of the output from the first light reception means. Means, a third subtraction means for generating a difference signal of the output by the third light receiving means, a second gain adjustment means for adjusting the gain of the amplitude of the difference signal by the third subtraction means, It is characterized by comprising subtraction means for subtracting the difference signal by the first subtraction means and the difference signal by the second gain adjustment means.

An optical disc apparatus in which a land track and a groove track are formed and information is recorded on or reproduced from these tracks by irradiating a main beam with the main beam. In the state where the main beam is applied to the land track, the first sub beam and the second sub beam are applied to groove tracks adjacent to both sides of the land track to which the main beam is applied, or A main beam irradiating a first sub-beam and a second sub-beam to land tracks adjacent to both sides of the groove track irradiated with the main beam in a state where the main beam is irradiated to the groove track. Beam and sub-beam irradiation means, and the main beam and the sub-beams of the main beam and sub-beam irradiation means. A first light receiving means divided into two in the track tangential direction of the land track or the groove track, and the first sub beam and the second sub beam are reflected by the optical disc. A first light receiving means for receiving the reflected light and generating a difference signal between an output of the second light receiving means and a third light receiving means divided into two in a track tangential direction of the land track or the groove track, and a first light receiving means; Subtraction means;
A second subtraction unit that generates a difference signal of the output by the second light receiving unit; a third subtraction unit that generates a difference signal of the output by the third light receiving unit; the second subtraction unit; and Gain adjustment means for adjusting the gain of the amplitude of the difference signal by the third subtraction means, addition means for adding the difference signal gain-adjusted by the gain adjustment means, and difference signal output by the first light receiving means A fourth subtracting means for subtracting an addition signal from said adding means, and a tracking for controlling the main beam so as to irradiate the land track or the groove track by using an output of the fourth subtracting means. Controlling means for changing a gain adjustment amount by the gain adjusting means depending on whether the track irradiated with the main beam is the land track or the groove track. And characterized in that.

Further, the gain adjusting means is a gain which gives the gain given to the amplitude of the difference signal by the second subtracting means to G2 and the gain given to the amplitude of the difference signal by the third subtracting means is G2.
3. The total reflected light amount when the main beam irradiates the groove track is R1, the total reflected light amount when the first sub beam irradiates the land track is R2, and the second sub beam is the land track. The total reflected light amount when irradiating is R3, the total reflected light amount when the main beam irradiates the land track is R4, and the total reflected light amount when the first sub beam irradiates the groove track is R5. G2 = R1 / (2 * R2) and G3 = R1 when the total reflected light amount when the sub beam of 2 irradiates the groove track is R6 and the main beam is irradiating the groove track. When the main beam irradiates the land track, the gain satisfies the relationship of G2 = R4 / (2 * R5) and G3 = R4 / (2 * R6). Is adjusted.

Therefore, under the above conditions, the track offset can be minimized.

[0033]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram illustrating a configuration of a first optical disk device according to an embodiment of the present invention, and the operation thereof will be described. In FIG. 1, reference numeral 701 denotes an optical disk of a land / groove recording type, and an optical head 702 generates a main laser beam and two sub laser beams by using, for example, a diffraction grating from a semiconductor laser. As a result, as shown in FIG. 2, the sub beam spots S1 and S2 are shifted from the irradiation position of the main beam spot S0 by the track pitch (TP) in the radial direction of the disk. Is irradiated. Main beam light spot S0, two sub beam light spots
The light reflected by S1 and S2 is detected by photodetectors 704, 705, and 706 provided on the light receiving element portion 703 and divided into two around the tangential direction of the track. The photo detector 704 is for detecting the reflected light from the main beam spot S0, and the photo detector 705 is for detecting the sub beam spot S1 and the photo detector 7 respectively.
06 is for detecting the reflected light from the sub beam spot S2. Photodetectors 704, 705, 706
Are output to subtracters 708, 709, and 710, respectively, to output difference signals (push-pull signals) PP0 and PP0, respectively.
1, PP2 is required. Further, the divided outputs A and B of the photodetector 704 are input to an adder 707, and an RF signal (reproduction signal) is generated. The RF signal is determined by a header detection section 717 and a land / groove detection section 718 to determine whether the track irradiated by the main beam for recording and reproduction is a land track, a groove track, or a header section. The discrimination information indicating the track and the header is transferred to the controller 715.

As a method of determining whether the track irradiated by the main beam is a land track, a groove track, or a header portion, for example, when address information of an optical disk is used, the entire circumference of the optical disk is used. The optical disk device has a table indicating whether each sector number is a land track or a groove track by looking at a predetermined sector number, and it is first determined whether the sector number is a land track or a groove track. Next, in the case of an optical disc of a type having several header sections in one track, the discrimination as to whether the section is a header section or not is made in advance by the optical disc apparatus by determining the position of the header section in one track and the number of sectors per track. If a table is provided and the number of sectors in one track is counted and the position between the sectors is checked, it can be determined whether or not the position is the header portion.

As another method, the reflected light of the main light beam from the optical disk is checked, and if the reflected light has a drastic change in amplitude, it is determined that the pit of the header portion is formed in the header portion. A determination can be made. Naturally, in the optical disk device, the main beam is tracked by the controller 715 along the groove track or the land track, so that the controller 715 can obtain the discrimination information.

The gain adjustment amplifiers 711 and 712 are
As the fixed gains G1 and G2, the main beam spot S0 scans the groove track 801 (the sub beam spots S1 and S2 irradiate the land track).
Gain G1 (= total reflected light amount of main beam spot S0 / total reflected light amount of sub-beam spot S1)
(The total reflected light amount of the sub beam spot S1) and the main beam spot S0 scan the land track 802 (the sub beam spot S1).
Gain G2 (= total reflected light amount of main beam spot S0 / sub beam spot S2) corresponding to the ratio of total reflected light amount of main beam spot S0 and total reflected light amount of sub beam spot S2 when S1 and S2 irradiate groove tracks Are set in advance, and the difference signals PP1 and PP2 are used as the fixed gains G1 and G2.
In the gain adjustment amplifiers 711 and 712 having
G1 times (= G1 * PP1) and G2 times (= G2 * PP2). As a result, the difference signal PP0 and the difference signals PP1 and PP2 have the same level of amplitude. This signal is input to the input unit of the selector 713.
The selector 713 determines whether the main beam spot S0 is the groove track 8 based on the discrimination information from the controller 715.
01, the difference signal (G1 * PP1) of the gain-adjusted sub beam spot S1 is selected, and the main beam spot S0
Irradiates the land track 802, the difference signal (G2 * PP2) of the gain-adjusted sub-beam spot S2 is selected. The difference signal PP0 of the main beam spot S0 is calculated by the subtractor 714.
Subtracts the selected difference signal from the tracking error signal
Get TE. The tracking control circuit performs tracking control of the optical head 702 in accordance with the tracking error signal TE and a command such as track ON / OFF from the controller 715.

The tracking control and the focus control and the movement of the optical head 702 in the radial direction of the light 701 enable the reproduction of information from the optical disk 701.

In the optical disk device of the present invention, the conventional DPP
Similar to the principle of the method, the difference signal PP0 of the main beam spot S0 and the difference signal (G1 * PP1) of the sub beam after gain adjustment, or
By subtracting (G2 * PP2), the component of the track offset generated due to the objective lens shift and the tilt of the optical disk is canceled. In the case of land / groove recording, it is necessary to perform recording / reproduction on both land tracks and groove tracks, but there are differences in the reflectance between lands / grooves and differences in the physical groove structure. Therefore, when the main beam spot S0 scans a land track and when it scans a groove track, the ratio of the reflected light amounts of the main beam spot S0 and the sub beam spots S1 and S2 changes. However, in the optical disk device of the present invention, it is determined whether the scanning track of the main beam spot S0 is a land track or a groove track, and the sub beam spots S1 and S2 are determined based on the result. The above problem can be avoided by selecting and using one of the two difference signals.

Next, a description will be given of a case where recording / reproducing is performed using the optical disk apparatus of the present invention on a recording / reproducing optical disk having a land / groove structure in which the emboss pit information as shown in FIG. 3 is not aligned in the radial direction of the disk. I do. FIG. 3 illustrates a case where the main beam spot S0 and the sub beam spots S1 and S2 do not overlap the emboss pit information 901.

As shown in FIG. 3, the land track 903 adjacent to the groove track 902 shares the emboss pit information 901 and the reproduction beam spot (main beam spot S0) has a land track adjacent to the groove track 902. The emboss pit information 901 is arranged at the boundary between the groove track 902 and the land track 903 adjacent to the groove track 902 so that the emboss pit information 901 can be read regardless of which of the scans 903 is performed. Although the emboss pit information is shown in FIG. 3 as normal pits, other physical shapes may be used. Further, as shown in FIG. 3, the sub beam spots S1, S2
Is irradiated at a position shifted by a track pitch (TP) in the radial direction of the disc with respect to the irradiation position of the main beam spot S0.

On the other hand, land / emboss pit information not aligned in the radial direction of the disc
On a recording / reproducing optical disc having a groove structure, as shown in FIG. 4, when the main beam spot S0 scans a recording track, emboss pit information appears in an adjacent track where one side of the sub beam spot scans. Will be described. FIG. 4A shows the main beam spot S0.
FIG. 4B shows a case where the sub beam spot S2 irradiates the emboss pit information 1002 of the adjacent land track while irradiating the groove track 1003, and FIG. 4B shows that the main beam spot S0 irradiates the land track 1004. In this case, the sub beam spot S1 irradiates the emboss pit information 1005 of the adjacent groove track.

In the optical disk device of the present invention, when the main beam spot S0 scans a groove track (the sub beam spots S1 and S2 irradiate land tracks), the total reflected light amount of the main beam spot S0 and the sub beam spot S1 Gain G1 (= main beam spot S0) corresponding to the ratio of the total reflected light amount of
Total reflected light amount / total reflected light amount of sub beam spot S1) and total reflected light amount of main beam spot S0 when main beam spot S0 scans a land track (sub beam spots S1 and S2 irradiate groove track) And secondary beam spot
Gain G2 corresponding to the ratio of the total reflected light amount of S2 (= total reflected light amount of main beam spot S0 / total reflected light amount of sub-beam spot S2)
Are set in advance. This allows PP0 and PP1,
It has the same level of amplitude as PP2.

As shown in FIG. 4A, when the main beam spot S0 irradiates the groove track 1003, it irradiates the adjacent land track 1004 sharing the emboss pit information 1001. Select the difference signal (G1 * PP1) obtained from the sub beam spot S1, subtract the difference signal (G1 * PP1) from the difference signal PP0 of the main beam spot S0,
Obtain the tracking error signal TE.

As shown in FIG. 4B, when the main beam spot S0 irradiates the land track 1004, it irradiates the adjacent groove track 1003 sharing the emboss pit information 1001. The difference signal (G2 * PP2) obtained from the sub beam spot S2 is selected, and the difference signal (G2 * PP2) is subtracted from the difference signal PP0 of the main beam spot S0 to obtain a tracking error signal TE.

That is, since the emboss pit information area does not appear on the adjacent track on the side sharing the emboss pit information 1001, the difference signal from the sub beam spots S1 and S2 is provided in the optical disk apparatus of the present invention. By selecting, it is possible to avoid the occurrence of a track offset due to an average change in the amount of reflected light when the sub beam reproduces the emboss pit information area.

In other words, this utilizes the fact that the emboss pit information is not aligned in the radial direction of the disc. When one sub beam spot is irradiated on the emboss pit information, the other sub beam spot is Since the information is not irradiated, the sub beam spot is selected, and similarly, a difference signal from the main beam which is not affected by the emboss pit information is obtained as a tracking error signal TE. When an embossed pit information area is reproduced, occurrence of a track offset due to an average change in reflected light amount can be avoided.

In this embodiment, the emboss pit information is described as an example in the case where the emboss pit information exists as a pit on the land where the groove is divided. However, the emboss pit information having a structure where the groove is not divided as shown in FIG. In the case of 601,
The effects of the present invention can be obtained. Emboss pit information
As shown in FIG. 5, the structure of 601 is arranged in the middle between the groove track and the land track, and the emboss pit information has a shape that makes the groove track protrude toward the land track. Have been.

In FIG. 6, the main beam spot S0 scans the recording track on the recording / reproducing optical disk having the land / groove structure having the emboss pit information 601 having the structure shown in FIG. 5, as in FIG. The case where the emboss pit information appears in an adjacent track where one side beam spot scans while the sub beam spot is scanning will be described.

The optical disk has a land track 1103 adjacent to the groove track 1102 as shown in FIG.
Share the emboss pit information 1101, and the land track adjacent to the groove track 1102 so that the emboss pit information 1101 can be read when the reproduction beam spot scans both the groove track 1102 and the adjacent land track 1103. Emboss pit information 1101 is arranged at the boundary of 1103. The sub-beam spots S1 and S2 are irradiated at positions shifted by a track pitch (TP) in the radial direction of the disc with respect to the irradiation position of the main beam spot S0.

FIG. 6 (a) shows that when the main beam spot S0 irradiates the groove track 1102, the sub beam spot S2 changes the emboss pit information 11 of the adjacent land track.
FIG. 6B shows the case where the main beam spot S0 irradiates the land track 1103 and the sub beam spot S1 irradiates the emboss pit information 1105 of the adjacent groove track. Shows the case.

In the optical disk device of the present invention, when the main beam spot S0 scans a groove track (the sub beam spots S1 and S2 irradiate a land track), the total reflected light amount of the main beam spot S0 and the sub beam spot S1. Gain G1 (= main beam spot S0) corresponding to the ratio of the total reflected light amount of
Total reflected light amount / total reflected light amount of sub beam spot S1) and total reflected light amount of main beam spot S0 when main beam spot S0 scans a land track (sub beam spots S1 and S2 irradiate groove track) And secondary beam spot
Gain G2 corresponding to the ratio of the total reflected light amount of S2 (= total reflected light amount of main beam spot S0 / total reflected light amount of sub-beam spot S2)
Are set in advance. Due to the gains G1 and G2, PP0 and PP1 and PP2 have the same amplitude.

As shown in FIG. 6A, when the main beam spot S0 irradiates the groove track 1102, it irradiates the adjacent land track 1103 sharing the emboss pit information 1101. Select the difference signal (G1 * PP1) obtained from the sub beam spot S1, subtract the difference signal (G1 * PP1) from the difference signal PP0 of the main beam spot S0,
Obtain the tracking error signal TE.

When the main beam spot S0 irradiates the land track 1103 in FIG. 6B, the sub beam spot S2 irradiates the adjacent groove track 1102 sharing the emboss pit information 1101. The obtained difference signal (G2 * PP2) is selected, and the difference signal (G2 * PP2) is subtracted from the difference signal PP0 of the main beam spot S0 to obtain the tracking error signal TE.

That is, since the emboss pit information area does not appear on the adjacent track on the side sharing the emboss pit information 1101, the difference signal from the sub beam spots S1 and S2 in the optical disk apparatus of the present invention. Is selected, it is possible to avoid occurrence of a track offset due to an average change in the amount of reflected light when the sub beam reproduces the embossed pit information area.

Next, the case where the reproduction of the emboss pit information shown in FIG. 6 is performed by using the optical disk apparatus of the present invention will be described with reference to FIG.

Since the embossed pit information 1101 is located between the groove track and the land track which are not divided, the conventional embossed pit information is compared with the embossed pit information using the pits shown in FIGS. Method, DPP
On the other hand, there is an advantage that tracking by the method can be easily performed, but on the other hand, the signal amplitude is small and the track offset is weak. In order to reproduce the embossed pit information having such a structure, it is necessary to minimize the occurrence of track offset from the viewpoint of the reading rate.

FIG. 7 shows an emboss pit information area 1201.
FIG. 4 is an enlarged view showing a beam spot position on an optical disc when a main beam spot S0 reproduces the data. The emboss pit information area 1201 corresponds to, for example, an enlarged portion of the emboss pit information 1101 in FIG.

Normally, the distance between the main beam spot S0 and the sub beam spots S1, S2 in the beam spot moving direction is
Since the main beam spot S0 irradiates the embossed pit information area 1201 while scanning the groove track 1202, as shown in FIG. 7A, since it is shorter than the physical length of the embossed pit information area 1201, Secondary beam spot S1
Illuminates the emboss pit information area 1201 on the adjacent land track 1203, and the sub beam spot S2 illuminates the normal recording / reproducing area on the adjacent land track 1204. As shown in FIG. 7B, when the main beam spot S0 irradiates the emboss pit information area 1201 while scanning the land track 1203, the sub beam spot S2 The pit information area 1201 is irradiated, and the sub beam spot S1 irradiates a normal recording / reproducing area on the adjacent groove track 1205.

In the optical disc device of the present invention, when the main beam spot S0 irradiates the emboss pit information area 1201 on the groove track 1202, the main beam spot S0 on the adjacent land track 1203 on the side sharing the emboss pit information 1201. Select the difference signal (G1 * PP1) obtained from the sub beam spot S1 irradiating the main beam spot S0
The difference signal (G1 * PP1) is subtracted from the difference signal PP0 to obtain a tracking error signal.

When the main beam spot S0 irradiates the emboss pit information area 1201 on the land track 1203, it irradiates the adjacent groove track 1202 on the side sharing the emboss pit information 1201. Difference signal obtained from sub-beam spot S2 (G2 * PP2)
And the difference signal from the difference signal PP0 of the main beam spot S0
(G2 * PP2) is subtracted to obtain a tracking error signal TE.

The emboss pit information area 1201 is
Since recording is performed using pits, which are not normal recording marks, the average reflectance is different from that of a normal recording / reproducing area on a land / groove. Therefore, the main beam spot S0
Irradiates the embossed pit information area, the reflected light amount ratio of the main beam spot S0 and the sub beam spot on the side not sharing the embossed pit information area 1201 changes. Track offset occurs. On the other hand, in the optical disk device of the present invention, when the main beam spot S0 scans the emboss pit information area, the difference signal of the sub beam spot on the side scanning the same emboss pit information area on the adjacent track is selected. By subtracting, both the main beam and the sub-beam are affected by the emboss pit information, so that the change in the amount of reflected light becomes substantially the same, whereby the average reflection when the main beam irradiates the emboss pit information area It is possible to avoid the occurrence of a track offset due to a change in the amount of light.

FIG. 8 is a block diagram showing the configuration of a second optical disk device according to the embodiment of the present invention.
The operation will be described.

The same components including the optical head 702 have the same reference characters allotted, and description thereof will not be repeated.

FIG. 8 differs from FIG. 1 in that
Instead of the selector 713, variable gain adjustment amplifiers 1311, 131
2 is to eliminate the difference in the reflected light amount ratio between the main beam spot and the sub beam spot due to the land / groove difference.

Referring to FIG. 8, the signal generated by adder 707 is
Explaining from the RF signal (reproduction signal), the RF signal is input to the header detection unit 717 and the land / groove detection unit 718, and whether the track scanned by the main beam for recording and reproduction is a land track or a groove track, It is determined whether or not the header is being irradiated, and the determination information is sent to the controller 131.
Transfer to 5. The difference signals PP1 and PP2 are respectively supplied to variable gain adjustment amplifiers 1311 and 1312 whose gains are controlled by a controller 1315.
G2 multiplied difference signals (VG1 * PP1) and (VG2 * PP2) are input to the adder 1313, and the added signal PP3 (= (VG1 * PP1) + (VG2 * PP
2)) is generated.

Then, the controller 1315 sets the gain amounts VG1 and VG2 of the variable gain amplifiers 1311 and 1312 based on the discrimination information. The gain amounts VG1 and VG2 are determined by the total reflected light amount of the track scanned by the main beam spot S0. VG1 = R1 / 2 * R2, VG2 = R1 / corresponding to the ratio of R1 to the total reflected light amount R2, R3 of the track scanned by the sub beam spots S1, S2.
Set to satisfy 2 * R3. The subtractor 1314 subtracts the addition signal PP3 from the difference signal PP0 from the main beam, and the result becomes the tracking error signal TE. The tracking control circuit performs tracking control of the optical head 702 in accordance with the tracking error signal TE and a command such as track ON / OFF from the controller 1315.

According to the optical disk apparatus of this embodiment, the gain can be adjusted in accordance with the change in the reflected light amount ratio between the main beam spot and the sub beam spot due to the land / groove difference. In addition, it is possible to avoid occurrence of a track offset due to a change in the reflected light amount ratio between the sub beam spot and the sub beam spot.

[0068]

According to the optical disk apparatus of the present invention described above, when tracking control is applied to an optical disk having a difference in reflectance between lands / grooves and a difference due to a physical groove structure, an objective lens is required. It is possible to provide an optical disk device in which track offset due to shift does not occur.

When tracking control is performed on a recording / reproducing type optical disc in which the embossed pit information is not aligned in the radial direction of the disc, there is an objective lens shift and the embossed pit information is not included in the adjacent track. Even if it appears, it is possible to provide an optical disk device in which a track offset does not occur.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical disc device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing irradiation positions of a three-beam spot on a land / groove recording type optical disc in the optical disc apparatus of the present invention.

FIG. 3 is a diagram showing irradiation positions on a recording / reproducing optical disc having a land / groove structure in which emboss pit information of a three-beam spot is not aligned in the radial direction of the disc (main beam spot and sub beam spot) in the optical disc apparatus of the present invention. If the beam spot is not on the emboss pit information).

FIG. 4 is a diagram showing an irradiation position on a recording / reproducing optical disc having a land / groove structure in which emboss pit information of a three-beam spot is not aligned in the radial direction of the disc in the optical disc apparatus of the present invention (the sub-beam spot is embossed). If it is on the pit information).

FIG. 5 is a diagram showing a groove structure of an optical disc when embossed pit information whose grooves are not divided is not aligned in the radial direction of the disc.

FIG. 6 is an irradiation position on a recording / reproducing optical disc having a land / groove structure in which emboss pit information (structure in which a groove is not divided) of three beam spots is not aligned in the radial direction of the disc in the optical disc apparatus of the present invention. (In the case where the sub beam spot is on the emboss pit information).

FIG. 7 is a diagram showing irradiation positions of three beam spots on the optical disc in the optical disc apparatus of the present invention (when a main beam spot and a sub beam spot are on emboss pit information).

FIG. 8 is a block diagram of an optical disc device according to a second embodiment of the present invention.

FIG. 9 is a diagram showing irradiation positions on the optical disk of three beam spots in the DPP method.

FIG. 10 is a diagram illustrating a structure of a divided photodetector that receives reflected light of a three-beam spot in the DPP method.

FIG. 11 is a processing block diagram of TE signal generation of the DPP method.

FIG. 12 is a diagram showing a structure of an optical disc of a type in which emboss pit information is aligned in a radial direction of the disc.

FIG. 13 is a diagram showing a groove structure of an optical disk when emboss pit information arranged in a divided groove is not aligned in the radial direction of the disk.

[Explanation of symbols]

701 Optical disk 702 Optical head 703 Photodetector 704 Photodetector (main beam spot S
(Receives 0 reflected light) 705 Photodetector divided into two (sub-beam spot S
1 Receives the reflected light) 706 Photodetector split into two (sub-beam spot S
707, 1313 Adder 708, 709, 710, 714, 1314 Subtractor 711, 712 Gain adjustment amplifier 713 Selector 715, 1315 Controller 716 Tracking control unit 717 Header detection unit 718 Land / groove detection unit 801, 902, 1003, 1102, 1202, 1205 Groove track 802, 903, 1004, 1203, 1204 Land track 601, 901, 1001, 1002, 1005, 1101, 1103 Emboss pit information 1201 Emboss pit information area 1311, 1312 Variable gain Adjustment amplifier

Claims (10)

[Claims] 1. An optical disc apparatus for recording or reproducing information on an optical disc on which land tracks and groove tracks are formed and on which information can be recorded on these tracks, by irradiating a main beam, In the state where the main beam is applied to the land track, the first sub beam and the second sub beam are applied to groove tracks adjacent to both sides of the land track to which the main beam is applied, or A main beam irradiating a first sub-beam and a second sub-beam to land tracks adjacent to both sides of the groove track irradiated with the main beam in a state where the main beam is irradiated to the groove track. A main beam and a sub-beam irradiating unit; and a main beam and a sub-beam of the main beam and the sub-beam irradiating unit. First light receiving means for receiving light reflected by the optical disc; second and third light receiving means for receiving light reflected by the optical disc of the first sub-beam and the second sub-beam, respectively; A first tracking error signal calculating unit for obtaining a first tracking error signal from the light receiving unit and the second light receiving unit; and a second tracking error from the first light receiving unit and the third light receiving unit. A second tracking error signal calculating means for obtaining a signal; a selecting means for selecting whether to use the first tracking error signal calculating means or the second tracking error signal calculating means; and Using the tracking error signal on the selected side, control is performed so that the main beam is irradiated on the land track or the groove track. An optical disk device comprising: 2. A land track and a groove track are formed, information can be recorded on these tracks, and emboss pit information shared by a set of land track and groove track is provided. The embossed pit information shared by another set of land tracks and groove tracks is different from the embossed pit information for the optical disc arranged at a different position in the radial direction of the disc.
An optical disk device for recording or reproducing the information by irradiating a main beam, wherein the main beam is irradiated on the land track, and adjacent to both sides of the land track irradiated by the main beam. Irradiating the groove track with a first sub-beam and a second sub-beam, respectively, or in a state where the main beam is irradiated on the groove track, on both sides of the groove track being irradiated by the main beam. A main beam and a sub-beam irradiating means for irradiating an adjacent land track with a first sub-beam and a second sub-beam, respectively, of the main beam and the sub-beams by the main beam and the sub-beam irradiating means, First light receiving means for receiving light reflected by the optical disc; and reflection of the first sub-beam and the second sub-beam by the optical disc. Second and third light receiving means for respectively receiving light; first tracking error signal calculating means for obtaining a first tracking error signal from the first light receiving means and the second light receiving means; A second tracking error signal calculating unit for obtaining a second tracking error signal from the first light receiving unit and the third light receiving unit; and the first tracking error signal calculating unit or the second tracking error signal. Selecting means for selecting which of the calculating means to use, and tracking for controlling the main beam to be applied to the land track or the groove track using a tracking error signal on the side selected by the selecting means. Control means, wherein the selection means, the main beam, the land track or the groove track When irradiating, the tracking error signal calculation on the side that obtains the tracking error signal based on the reflected light of the sub-beam irradiating the track irradiating the track on which the main beam is illuminated and the track sharing the emboss pit information An optical disk device characterized in that a means is selected. 3. The optical disk, wherein the embossed pit information is arranged between the groove track and the land track, and the embossed pit information causes the groove track to protrude toward the land track. 3. The optical disk device according to claim 2, wherein: 4. The first light receiving means and the second and third light receiving means are light receiving elements divided into two in a track tangential direction of the land track or the groove track, and the first tracking means. Error signal calculating means, a first subtraction means for generating a difference signal of the output of the first light receiving means, a second subtraction means of generating a difference signal of the output of the second light receiving means, A first gain adjustment unit that adjusts the gain of the amplitude of the difference signal by the second subtraction unit; and a subtraction unit that subtracts the difference signal by the first subtraction unit from the difference signal by the first gain adjustment unit. Wherein the second tracking error signal calculating means generates a difference signal of an output by the first light receiving means, and a difference signal of an output by the third light receiving means Third Subtraction means, second gain adjustment means for adjusting the gain of the amplitude of the difference signal by the third subtraction means, difference signal by the first subtraction means, and difference signal by the second gain adjustment means 3. An optical disk device according to claim 1, further comprising a subtraction means for subtracting the following. 5. The first gain adjusting means and the second gain adjusting means, wherein the first gain adjusting means has a gain G1 applied to an amplitude of a difference signal by the second subtracting means, and the second gain adjusting means has a second gain. G2, the gain given to the amplitude of the difference signal by the third subtraction means by the gain adjustment means, the total reflected light amount when the main beam irradiates the groove track, and the main beam irradiates the land track. When the total reflected light amount is R3, the first
G1 = R1 / R2 and G2 = R3, where R2 is the total reflected light amount when the sub-beam irradiates the land track and R4 is the total reflected light amount when the second sub-beam irradiates the groove track. 5. The optical disk device according to claim 4, wherein a gain adjustment satisfying a relationship of / R4 is performed. 6. A land track and a groove track are formed, information can be recorded on these tracks, and emboss pit information shared by a set of land track and groove track is provided. The embossed pit information shared by another set of land tracks and groove tracks is different from the embossed pit information for the optical disc arranged at a different position in the radial direction of the disc.
An optical disk device for recording or reproducing the information by irradiating a main beam, wherein the main beam is irradiated on the land track, and adjacent to both sides of the land track irradiated by the main beam. Irradiating the groove track with a first sub-beam and a second sub-beam, respectively, or in a state where the main beam is irradiated on the groove track, on both sides of the groove track being irradiated by the main beam. A main beam and a sub-beam irradiating means for irradiating an adjacent land track with a first sub-beam and a second sub-beam, respectively; First light receiving means for receiving light reflected by the optical disc; reflection of the first sub-beam and the second sub-beam by the optical disc; Second and third light receiving means for respectively receiving light; first tracking error signal calculating means for obtaining a first tracking error signal from the first light receiving means and the second light receiving means; A second tracking error signal calculating unit for obtaining a second tracking error signal from the first light receiving unit and the third light receiving unit; and the first tracking error signal calculating unit or the second tracking error signal. Selecting means for selecting which of the calculating means to use, and tracking for controlling the main beam to be applied to the land track or the groove track using a tracking error signal on the side selected by the selecting means. Control means, and wherein the selection means is arranged so that the main beam is transmitted to the land track or the groove track. When irradiating the emboss pit information, it is configured to select the tracking error signal calculation means for obtaining the tracking error signal based on the reflected light of the sub-beam irradiating the emboss pit information similarly to the main beam. An optical disc device characterized by the above-mentioned. 7. The optical disk, wherein the emboss pit information is arranged between the groove track and the land track, and the emboss pit information causes the groove track to protrude toward the land track. 7. The optical disk device according to claim 6, wherein: 8. The first light receiving means and the second and third light receiving means are light receiving elements divided into two in a track tangential direction of the land track or the groove track, and the first tracking means. Error signal calculating means, a first subtraction means for generating a difference signal of the output of the first light receiving means, a second subtraction means of generating a difference signal of the output of the second light receiving means, A first gain adjustment unit that adjusts the gain of the amplitude of the difference signal by the second subtraction unit; and a subtraction unit that subtracts the difference signal by the first subtraction unit from the difference signal by the first gain adjustment unit. Wherein the second tracking error signal calculating means generates a difference signal of an output by the first light receiving means, and a difference signal of an output by the third light receiving means Third Subtraction means, second gain adjustment means for adjusting the gain of the amplitude of the difference signal by the third subtraction means, difference signal by the first subtraction means, and difference signal by the second gain adjustment means 8. The optical disk device according to claim 6, further comprising a subtraction means for subtracting the following. 9. An optical disc apparatus for recording and reproducing information on an optical disc on which land tracks and groove tracks are formed and on which information can be recorded on these tracks by irradiating a main beam, In the state where the main beam is applied to the land track, the first sub beam and the second sub beam are applied to groove tracks adjacent to both sides of the land track to which the main beam is applied, or A main beam irradiating a first sub-beam and a second sub-beam to land tracks adjacent to both sides of the groove track irradiated with the main beam in a state where the main beam is irradiated to the groove track. A main beam and a sub-beam irradiated by the main beam and the sub-beam irradiating unit; A first light receiving unit that receives light reflected by the optical disc and is divided into two in a track tangential direction of the land track or the groove track; and light reflected by the optical disc of the first sub-beam and the second sub-beam. Respectively in the track tangent direction of the land track or the groove track.
A second divided second and third light receiving means, a first subtraction means for generating a difference signal of the output from the first light receiving means, and a second subtraction means for generating a difference signal of the output from the second light receiving means A second subtraction unit, a third subtraction unit that generates a difference signal of an output by the third light receiving unit, and a gain of an amplitude of the difference signal by the second subtraction unit and the third subtraction unit. Gain adjustment means for performing, addition means for adding the difference signal gain-adjusted by the gain adjustment means, and fourth subtraction for subtracting the addition signal by the addition means from the difference signal output from the first light receiving means. Means, and tracking control means for controlling the main beam to irradiate the land track or the groove track by using the output of the fourth subtraction means, and adjusting the gain by the gain adjusting means. An optical disk device, wherein the amount is changed depending on whether the track irradiated with the main beam is the land track or the groove track. 10. The gain adjusting means, wherein G2 is a gain given to the amplitude of the difference signal by the second subtracting means, G3 is a gain given to the amplitude of the difference signal by the third subtracting means, and the main beam is The total reflected light amount when irradiating the groove track is R1, the total reflected light amount when the first sub-beam irradiates the land track is R2, and the total reflected light amount when the second sub-beam irradiates the land track To
R3, the total reflected light amount when the main beam irradiates the land track is R4, the total reflected light amount when the first sub-beam irradiates the groove track is R5, and the second sub-beam is the groove track. If the total reflected light amount at the time of irradiation is R6, and the main beam is irradiated on the groove track, the relationship of G2 = R1 / (2 * R2) and G3 = R1 / (2 * R3) When the main beam is irradiated on the land track, the gain is adjusted so as to satisfy the relationship of G2 = R4 / (2 * R5) and G3 = R4 / (2 * R6). 10. The optical disk device according to claim 9, wherein: