JPH07311974A - Optical disc unit - Google Patents

Abstract

PURPOSE:To provide an optical disc unit for reproducing the recorded information of two systems simultaneously from adjacent tracks using a two beam system in which a correct reproduction signal is obtained from a high density recording optical disc by removing the crosstalk component produced between the tracks. CONSTITUTION:An output signal S1 from an optical detector 3 relating to a light spot B1 on the preceding irradiation side is delay through a delay circuit 5 by a time L/V (L; the interval between light spots B1 and B2 in the line speed direction of a disc, V; line speed of disc). Crosstalk component is then removed from a delayed signal S1' and an output signal S2 of an optical detector 4 relating to the light spot B2 on the following irradiation side using attenuators 6, 7 having an attenuation rate (a) (corresponding to the relative crosstalk ratio between adjacent tracks 1 and 2) and differential amplifiers 8, 9 thus obtaining reproduction signals RF1, RF2. The interval of each light spot B1, B2 in the direction perpendicular to the line speed direction is set shorter than the track pitch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk such as a magneto-optical disk or a phase change disk, which records two systems of information on adjacent tracks by a two-beam method and simultaneously reproduces each recorded information. The present invention relates to an improvement for removing and suppressing crosstalk between tracks in an apparatus, a measure for reducing the influence of return light noise in a recording mode, and the like.

[0002]

2. Description of the Related Art CD (Compact Disc), which is an optical disc exclusively for audio reproduction, has become widespread, and recently, MD (Mini Di disc) which is a magneto-optical disc capable of recording / reproducing.
Sc) and phase change (PC :: Phase Change) disks are in the limelight, and various disk devices have been developed.

First, in a CD, all the recorded information is recorded on a track in the form of pits formed as irregularities on the reflection surface, and the laser beam emitted from the laser beam emitting section is passed through an optical system. The reflected light is received by a photodetector and the output signal photoelectrically converted by the photodetector is demodulated to read and reproduce recorded information on the disc. Also, during reproduction, tracking of the focused spot, control information of the linear velocity of the disk, detection of time / address information, etc. are required. However, such control information is also detected using the pits described above. In terms of operation, the 3-beam method and the 1-beam push-pull method are adopted.

On the other hand, MD and CD-MO (Magneto-Optical)
Although a PC disc and the like are recordable / reproducible optical discs, irradiating a focused spot onto a track of the disc in each recording / reproducing mode is the same as in the case of a CD. That is, in the recording mode, recording is performed by changing the polarization axis and the refractive index of the recording area by the magnetic field modulation method for the area of the focused spot in the MD and by the light intensity modulation method in the CD-MO or PC disk. In the reproducing mode, the reflected light obtained from the focused spot on the track is photoelectrically converted to obtain a reproduced signal, as in the case of the CD.

However, in a recordable disc such as an MD, the recorded information may not exist in the track or the recorded information may be erased. Therefore, in order to obtain various control information at the time of recording, the surface of the disc is previously recorded. On the other hand, grooves (guide grooves) are often formed in a meandering manner, and grooves and lands are alternately arranged along the circumferential direction of the disc, and the side walls between the grooves and lands are wobbled at a constant cycle. ing. Then, for example, in recording / reproducing an MD, the one-beam push-pull method is used to detect a wobbling (WobC) signal or an address (ADD) signal necessary for spindle control and address detection, and a 1-beam push-pull method is used to detect a tracking error (TE) signal. The three-beam method is used for detection, the astigmatism method is used for detection of the focus error (FE) signal, and the three-beam Wustlan prism method is used for detection of the reproduction signal. The groove is detected while detecting various servo control signals. Magneto-optical recording and reproduction will be performed.

By the way, as a deformable disk for wobbling, as shown in FIG.
1a only is meandering, and the average value of the width of the groove 1 is set to be equal to the average value of the width of the land 2 between the grooves 1 '' has been proposed. JP-A-5-314538). According to this optical disk, due to the above-mentioned characteristics, the focused spot B01 as shown in FIG.
Alternatively, when B02 is irradiated, a strong tracking signal is obtained, and accurate tracking / spindle control can be performed.

On the other hand, as a recent attempt for high-density recording on optical disks, land / groove recording, that is, a method of recording on both lands and grooves has been proposed (Ohno et al .: “Land & Phase in Phase Change Optical Disks”). Examination of groove recording ", '93 Spring Applied Physics Society, Proceedings 29a-B-9), as a suggestion of the possibility of high-density recording without shortening the wavelength of the light source and improving the NA (Numerical Aperture) of the objective lens. As noted, the one-sided wobbling type optical disc (FIG. 6) according to the above-mentioned proposal has a more advantageous structure for performing the land-and-groove recording. That is, in the optical disk of the one-sided wobbling method, a stronger TE signal can be obtained as compared with the case where both-sided wobbling is performed as in the MD, and at the same time, one light spot strikes the two meandering side walls. Since it does not exist, highly accurate land and groove recording can be performed by accurate tracking control and address information detection based on the above characteristics.

Therefore, the applicant of the present application detects the wobbling modulation signal by the two-beam method and obtains various control signals for the above-mentioned one-sided wobbling optical disk, and at the same time, information of two systems for the land and the groove is obtained. We are proposing an optical disk device that can record data and reproduce two systems of recorded information at the same time [January 28, 1995]
Patent application filed on the date (reference number: 406001022)].

The optical disk device according to the proposal is realized by the structure as shown in FIG. First, the focused spots B1 and B2 are independently irradiated to the areas including the wobbling portions of the groove 1 and the land 2 which are adjacent to each other via the wobbling side wall 1a, and the reflected light is directed in the linear velocity direction of the disc. Each photodetector divided into two in the direction parallel to
Detect with 4.

In the recording mode, recording information of two systems (magnetic field modulation method for magneto-optical disk, light intensity modulation method for PC disk, etc.) is performed by using each condensing spot B1, B2, and in reproduction mode. The divided output signals of the photodetectors 3 and 4 are added by the addition amplifiers 51 and 52 to reproduce signals (RF1, RF
2) is detected. In the recording mode and the reproducing mode, the differential signals of the divided output signals of the photodetectors 3 and 4 are obtained by the differential amplifiers 53 and 54, and the center of the pass band is the linear velocity V of the disc from the respective difference signals. The wobbling modulation signal is detected by each BPF 55, 56 set to the wobbling frequency determined by the wobbling cycle of the side wall 1a, and each wobbling modulation signal is input to each envelope (ENV) detection circuit 57, 58 to output the amplitude component of the wobbling modulation signal. And further input each amplitude signal to the differential amplifier 59 to obtain the difference signal of each amplitude signal,
The difference signal is used as a tracking error (TE) signal. Further, the output of the BPF 55 corresponding to the focused spot B1 which is previously irradiated in the direction of the linear velocity of the optical disc is delayed by the delay circuit 61 by the time τ (= L / V), and the other focused spot which is irradiated later. The output signal of the BPF 56 corresponding to B2 and the delayed signal are input to the summing amplifier 62,
The sum signal is used as a wobbling carrier (WobC) signal, and the sum signal is demodulated by the FM demodulator 63 and the signal decoded by the decoder 64 is an address (ADD).
Used as a signal.

[0011]

By the way, generally, in recording / reproducing for an optical disk, the problem of crosstalk occurring between adjacent tracks inevitably occurs. In particular, when recording is performed on both the groove and the land to achieve high density recording, the crosstalk component increases because the distance between the tracks decreases.
2 beams at the same time, as proposed by the applicant
The influence cannot be ignored when recording / reproducing the system.

On the other hand, as a prior art relating to the removal of crosstalk components, in a three-beam type optical disc reproducing apparatus, "a main information signal from a main track of a disc and both sub information signals from sub tracks on both sides thereof are reproduced at the same time. ,
An apparatus for storing these signals in a storage means and removing the crosstalk signal contained in the main information signal based on the stored contents "has been proposed (Japanese Patent Laid-Open No. 6-20283). The principle of crosstalk removal by the three-beam method can be applied to the land and groove recording described above, but three beams are required even if there is only one track to be reproduced.
It is unsuitable for a system in which two systems of recording / reproducing are simultaneously performed on a pair of adjacent grooves and lands. Further, there is a problem in processing speed because it involves software processing such as a data processor.

Therefore, according to the present invention, in an optical disc device which records information of two systems on adjacent tracks by the two-beam method and reproduces information of two systems of those tracks at the same time, the information is recorded between adjacent tracks. It was created for the purpose of providing an optical disc device capable of recording / reproducing information while removing or suppressing the crosstalk. The present invention also proposes a recording condition for avoiding the influence of return light noise when recording is performed by the two-beam method at the same time.

[0014]

According to a first aspect of the present invention, two converging spots are formed, and the respective converging spots are spaced apart from each other on a track adjacent to the optical disc at a constant interval in the linear velocity direction of the optical disc. It is possible to simultaneously reproduce the recorded information of each of the tracks by providing a light irradiating means for irradiating with each other and two light detecting means for independently detecting and photoelectrically converting the reflected light from each of the condensed spots. In the optical disc device, the output signal of the first light detecting means for detecting the reflected light of the focused spot which is irradiated in advance in the linear velocity direction of the optical disc is divided by the linear velocity of the optical disc by the interval between the focused spots. Delay means for giving an output of only the delay and outputting the output signal of the delay means with an attenuation ratio equivalent to the relative crosstalk ratio of the photodetection signal generated between the tracks. An attenuating means, a second attenuating means for attenuating the output signal of the second photodetecting means for detecting the reflected light of the converging spot which is irradiated later in the linear velocity direction of the optical disc, and the delay. First signal calculating means for obtaining a difference signal between the output signal of the means and the output signal of the second attenuating means, and second signal calculating means for obtaining a difference signal between the output signals of the first attenuating means and the second photodetecting means. According to the optical disc device, each difference signal obtained by the first and second signal calculation means is used as a reproduction signal of recorded information of each track.

According to a second aspect of the present invention, a light irradiating means which forms two converging spots and irradiates each converging spot on each adjacent track of the optical disc at a constant interval in the linear velocity direction of the optical disc. And an optical disc device capable of reproducing the recorded information of each of the tracks at the same time, which is provided with two photodetection means for independently detecting and photoelectrically converting the reflected light from each of the condensed spots. An interval between the respective focused spots in a direction orthogonal to the linear velocity direction is set smaller than a track pitch of the optical disc, and reproduction is performed under an arrangement condition in which the focused spots are brought closer to a track boundary side. The present invention relates to an optical disk device.

According to a third aspect of the present invention, a light irradiating means which comprises two condensing spots and irradiates each condensing spot on each adjacent track of the optical disk in the linear velocity direction of the optical disk at a constant interval. And two light detecting means for independently detecting and photoelectrically converting the reflected light from each of the condensed spots, and recording / reproducing two systems of record information for adjacent tracks of the optical disc. The present invention relates to an optical disc device capable of performing recording using only one focused spot in the recording mode.

A fourth aspect of the present invention is a condition for setting an interval of each converging spot according to the second aspect of the present invention, in which two systems of recording information are recorded on adjacent tracks of an optical disk under the recording condition of the third aspect. / In the optical disk device for reproducing, provided is a condensing spot displacement means for displacing each condensing spot so that one condensing spot is located in the central area of the track. The present invention relates to an optical disc device in which recording is performed only on the side of a focused spot located in the central area of a track.

According to a fifth aspect of the invention, in the optical disc device according to the third or fourth aspect of the invention, when recording is performed on an optical disc having lands and grooves or an optical disc having wobbling between tracks, The present invention relates to an optical disc device that obtains various control signals by using output signals of a photodetector corresponding to a focused spot on which no recording operation is performed.

[0019]

[Action]

Regarding the first invention; the present invention relates to a configuration for canceling crosstalk of a photodetection signal generated between tracks when reproducing information recorded in adjacent tracks of an optical disc by a two-beam method. Since each focused spot is irradiated at a position separated by a constant interval in the linear velocity direction of the optical disc, the photodetection means corresponding to the focused spot that is irradiated in advance has a rear position in the direction orthogonal to the linear velocity direction of the optical disc. The recording information at the position preceding the light detecting means corresponding to the focused spot for row irradiation is output as a signal. On the other hand, crosstalk between adjacent tracks is a phenomenon that occurs between regions at the same position in the direction orthogonal to the linear velocity direction of the optical disc.

The delay means plays a role of adjusting the timing so that the output signal of each light detecting means becomes a signal at the same position in the direction orthogonal to the linear velocity direction on the optical disk. Then, each signal adjusted as described above is attenuated by each attenuating means, and each signal calculating means obtains a difference signal from the other signal to obtain a reproduction signal of recorded information of each track. Since the attenuation ratio is set to be equal to the relative crosstalk ratio generated between tracks, each reproduction signal output from each signal calculation means has the crosstalk component removed.

Regarding the second aspect of the invention; in the case of reproducing the record information of the adjacent tracks of the optical disc by the two-beam method,
Generally, since the recording information is recorded at the center position of each track, each focused spot is irradiated so that its center is located at the center position of each track, and each focused spot in the direction orthogonal to the linear velocity direction of the optical disc. Is set to correspond to the track pitch. By the way, the first invention eliminates the crosstalk between the adjacent tracks irradiated with the two focused spots. Crosstalk from the tracks that are present also appears in the output signal of each photodetector.

Therefore, in the present invention, the interval between the respective focused spots in the direction orthogonal to the linear velocity direction of the optical disk is made small so that the crosstalk from the tracks adjacent to the outside and the inside can be suppressed as much as possible. . If each focused spot includes the central area of each track, it is possible to detect the recorded information by each photodetector even in that state, and the crosstalk that occurs between the adjacent tracks to be reproduced. Can be removed by applying the first aspect of the invention.

Regarding the third invention: The present invention relates to a case where not only reproduction but also recording is performed in the optical disc apparatus adopting the two-beam method as in the above-mentioned respective inventions. Generally, in the recording mode, the light output of the laser is increased because it is necessary to increase the irradiation intensity of the focused spot as compared with the case of the reproduction mode, but the return light to the emitting portion of the laser induces a jump in the spectrum mode, So-called return light noise occurs. In particular, when the two optical beams for recording are applied to the optical disk through the same optical system, it is difficult to prevent the return light noise, and as a result, stable servo control cannot be performed. Therefore, in the present invention, only one focused spot is used in the recording mode, and recording on each track is executed while reducing the influence of return light noise.

Regarding the fourth aspect of the invention: In the present invention, the interval between the respective focused spots in the direction orthogonal to the linear velocity direction of the optical disc is set to be small in consideration of the problem of crosstalk during reproduction as in the second aspect of the invention. The present invention relates to the case where only one converging spot is used for recording in consideration of the problem of return light noise during recording as in the third invention.

In the second aspect of the invention, the interval is made small in order to bring the focused spots to the track boundary side during reproduction, but the relative position of each focused spot to the track during reproduction is recorded. When applied as is,
The center of each focused spot is irradiated in a manner shifted from the center of the track, and when recording is performed using only one focused spot, the recording signal is inevitably located at a position shifted from the center of the track. It will be recorded. Therefore,
Focusing spot displacement means is provided, and in the recording mode, the focusing spot on the recording side is displaced so as to be positioned at the center of the track so that recording is performed in the central area of the track. The other focused spot can also be displaced at the same time, but since the focused spot is not used for recording, the above displacement does not cause any trouble.

Regarding the fifth aspect of the invention; like the third aspect of the invention, when only one focused spot is used for recording,
If the land and the groove are formed on the optical disk, the TE signal can be obtained from the other focused spot. Further, in the case of the fourth aspect of the invention, the other focused spot not used for recording is displaced toward the track boundary side, and various controls are performed on the disk in which wobbling is applied to the track boundary. It is a convenient location to get the signal. Therefore, in the present invention, by positively utilizing the converging spot that is not used for recording, and obtaining various servo control signals and address signals from the output signal of the photodetector corresponding to the converging spot, Enable recording while executing focus, tracking, spindle control, etc.

In each of the above inventions, the first to fourth aspects
In view of those principles, the invention can be applied regardless of whether lands and grooves are formed on the optical disk or whether wobbling is performed between tracks.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an optical disk device of the present invention will be described in detail below with reference to FIGS. Embodiment 1; This embodiment relates to an optical disk device corresponding to the above-mentioned first invention, and here, in the case of recording / reproducing information of two systems by a two-beam method on a groove and a land of an optical disk of one side wobbling. As a specific example,
FIG. 1 shows the positional relationship between the respective focused spots on the optical disc and the detection circuit for the reproduced signal. First, the optical disc is the same as that shown in FIGS. 6 and 7, and the same reference numerals as those in FIGS. 6 and 7 show the same elements in the optical disc of FIG. Detailed description is omitted. The numbers shown in parentheses for the groove 1 and the land 2 in FIG. 1 indicate the track numbers because the groove 1 and the land 2 are tracks. In addition, in this embodiment, as shown in FIG.
In the same manner as in the above case, the respective focused spots B1 and B2 are irradiated on the adjacent tracks at a constant interval L in the linear velocity direction of the optical disk.

The reproduction signal detection circuit is provided with a focused spot B1.
Output signal S1 of the photodetector 3 corresponding to the time τ (= L / V)
Delay circuit 5 for delaying only by and output signal S1 'of delay circuit 5
Attenuator 6 for attenuating light at an attenuation rate a, an attenuator 7 for attenuating the output signal S2 of the photodetector 4 corresponding to the focused spot B2 at an attenuation rate a, and output signals of the delay circuit 5 and the attenuator 7. A differential amplifier 8 for detecting a difference signal between (S1 'and aS2) and a photodetector 4
And a differential amplifier 9 for detecting a difference signal between the output signals (S2 and a · S1 ′) of the attenuator 6, and the difference signals output by the differential amplifiers 8 and 9 are collected respectively. The reproduced signals (RF1, RF2) of the recorded information detected at the spots B1, B2 are used. Here, the attenuation rate a of each attenuator 6 and 7 is determined by the adjacent groove 1 (N).
Is set to a value corresponding to the relative crosstalk ratio generated between the land and the land 2 (N).

In the above structure, each focused spot B1,
Although B2 is arranged at a constant interval L in the linear velocity direction of the optical disk, the output signal S1 of the photodetector 3 corresponding to the focused spot B1 previously irradiated on the optical disk is delayed by the delay circuit 5 for the time τ. Since the signals are delayed and output, the output signal S1 ′ of the delay circuit 5 and the output signal S2 of the photodetector 4 corresponding to the focused spot B2 that is irradiated to the optical disc in the following are the same in the linear velocity direction of the optical disc. This means that the recorded information of the groove 1 (N) and the land 2 (N) existing at the position is detected.

And, in that precondition, the photodetector
The output signal S1 of 3 corresponds to an addition signal of the signal component A related to the reflected light from the groove 1 (N) and the crosstalk components a and B related to the reflected light from the land 2 (N), and the photodetector 4 Output signal S
Assuming that 2 corresponds to the sum signal of the signal component B related to the reflected light from the land 2 (N) and the crosstalk component a · A related to the reflected light from the groove 1 (N), the above circuit configuration results. For example, the output signal RF1 of the differential amplifier 8 is (S1−a · S2) =
(A + a · B−a · B−a ² · A) = (1−a ² ) · A, and the output signal RF2 of the differential amplifier 9 is (S2−a · S1) = (B +
a · A−a · A−a ² · B) = (1−a ² ) · B. Now, for example, the above-mentioned relative crosstalk ratio, that is, each attenuator 6,7
If the attenuation rate of a is 0.1 (= 10%), each reproduced signal becomes RF1 = 0.99A, RF2 = 0.99B, and the signal level slightly decreases, but the groove 1 (N) And land 2 (N)
The signal is output as a signal from which the crosstalk component generated between the two is removed.

Therefore, even in the optical disc in which the information is recorded in the groove 1 and the land 2 to increase the recording density, the reproduction signals RF1 and RF2 from which the crosstalk between the adjacent tracks which are simultaneously reproduced are removed can be obtained. Accurate reproduction becomes possible. Although each of the reproduction signals RF1 and RF2 contains a wobbling modulation component, only the reproduction signal can be extracted by a high-pass filter as is normally done.

Embodiment 2; This embodiment corresponds to the above-mentioned second invention. In the above-described first embodiment, the crosstalk between the adjacent tracks that are simultaneously reproduced is removed, but it is only from the land 2 (N) side that the crosstalk is exerted when reproducing the information of the groove 1 (N). Not its groove
Crosstalk from the land 2 (N + 1) side existing outside 1 (N) must also be considered. In addition, the situation is land
The same applies to the reproduction of 2 (N) information, and groove 1 (N)
Not only from the side, but also from the groove 1 (N-1) side inside the land 2 (N) side must be considered. In the first embodiment, the removal of these crosstalks is not targeted, and the crosstalk components are actually included in the reproduction signals RF1 and RF2.

On the other hand, according to the first embodiment, it is possible to remove the crosstalk component between the adjacent tracks which are simultaneously reproduced. Therefore, in this embodiment, the side wall 1 on which wobbling is applied to the positions of the respective focused spots B1 and B2.
Displace in the direction of a (track boundary direction) and land 2 (N +
Crosstalk from the 1) side and the groove 1 (N-1) side is suppressed as much as possible.

The principle of the crosstalk suppression is shown in FIG. 2 for the reproduction signal RF1 and FIG. 3 for the reproduction signal RF2.
Will be described using. In FIG. 2, the focused spot B1
If the center of is at the center of the maximum width of groove 1 (N),
For the reproduction signal RF1, the crosstalk level C2 (N) from the land 2 (N) side and the crosstalk level C from the land 2 (N + 1) side
2 (N + 1) is included, but when the position of the focused spot B1 is offset displaced toward the side wall 1a by Δd, C2 (N) becomes large, but C2 (N + 1) becomes small. . Also, FIG.
In the case where the center of the focused spot B2 is at the center of the maximum width of the land 2 (N), the groove 1 is included in the reproduction signal RF2.
Crosstalk level C1 (N) and groove 1 (N-1) from the (N) side
Although the crosstalk level C1 (N-1) from the side is included, C1 (N) increases when the position of the focused spot B2 is offset displaced toward the side wall 1a by Δd, but C
1 (N-1) becomes smaller. Then, each focused spot B1, B2
Since C2 (N) and C1 (N) that have become large due to the offset displacement of C2 (N +) can be removed by the circuit according to the first embodiment, C2 (N +
1) and C1 (N-1) are suppressed to obtain a more accurate reproduction signal RF1,
RF2 will be obtained. In addition, since the irradiation areas of the focused spots B1 and B2 are largely applied to the wobbling side wall 1a due to the offset displacements described above, the wobbling modulation components included in the output signals of the photodetectors 3 and 4 are increased. This is convenient when various control signals are obtained based on the wobbling modulation signal as shown in FIG.

It should be noted that in the actual device, each of the above-mentioned focused spots B
In order to realize the offset displacement of 1 and B2, as shown in FIG. 4, the semiconductor laser unit of the semiconductor laser unit is set so that the interval between the respective focused spots B1 and B2 on the optical disc is narrower than the track pitch P0 by 2 · Δd. It is enough to set the position of each beam launcher.

Embodiment 3; This embodiment corresponds to the above-mentioned third invention, and recording is performed on the optical disc while forming the respective focused spots B1 and B2 under the same arrangement conditions as in the above-mentioned Embodiment 1. When to do. Focusing spots B1 and B of Example 1
If the arrangement condition of 2 is used, it is possible to simultaneously record information of two systems on the optical disc. However, regardless of whether the recording method for the optical disk is the magnetic field modulation method or the optical modulation method, it is necessary to increase the light output of the laser in the recording mode as compared with the reproduction mode to increase the irradiation intensity of the focused spot. In that case, return light noise is likely to occur because more reflected light from the focused spot returns to the laser emission part, but when there is no margin in the upper limit of the laser light output, high frequency superimposition reduces the return light noise. It is difficult to take a measure for removing the return light noise because the method described above cannot be applied, and as a result, various servo control signals cannot be stably obtained.

Therefore, in this embodiment, in the recording mode, recording is performed using only one of the converging spots, but the advantage of simultaneous recording of two systems is lost, but the converging spots not used for recording are reproduced. Stable recording conditions that are not affected by return light noise are secured as the irradiation intensity in the mode. Note that it is not necessary to use one of the focused spots fixedly, and the recording operation state may be selectively performed. For example,
In FIG. 1, recording is performed by a switching method in which only the focused spot B1 is recorded in the groove 1 (N) in the recording operation state, and then only the focused spot B2 is recorded in the recording operation state in the land 2 (N). It is also possible to go.

Embodiment 4; This embodiment corresponds to the above-mentioned fourth and fifth inventions. In the third embodiment, the return light noise is taken into consideration under the arrangement conditions of the respective focused spots B1 and B2 in the first embodiment, and only one of the focused spots is set as the recording operation state for recording. The same can be said under the arrangement conditions of the respective focused spots B1 and B2 in the second embodiment. Further, according to the interval setting condition of each condensing spot B1, B2 of the second embodiment, the interval of each condensing spot B1, B2 in the direction orthogonal to the linear velocity direction of the optical disc is made narrower than the track pitch. The irradiation areas of the respective focused spots B1 and B2 are protruded to the land 2 side and the groove 1 side in such a manner that they overlap each other by the offset displacement, and in the recording mode, the focused spots B1 and B1 are projected as shown in FIG.
The crosstalk area of the recording signal corresponding to B2 becomes large, and if the offset displacement amount of each condensing spot B1, B2 is made large, it becomes difficult to reproduce the signal accurately in the reproduction mode. That is, under the condition for setting the interval between the focused spots B1 and B2 in the second embodiment, also in that sense, the focused spots B1 and B2 are set.
It is not suitable for recording 2 lines using 2 simultaneously.

By the way, under the condition for setting the interval between the respective focused spots B1 and B2 of the second embodiment, which is more advantageous in removing the crosstalk in the reproduction mode, only one of the focused spots as in the third embodiment is selected. When recording is performed using this, the focused spot used for recording is displaced from the central region of the track under the condition of setting the interval between the focused spots B1 and B2 for the track in the reproduction mode. Therefore, in this embodiment, in the reproduction mode, the respective focused spots B1 and B2 for the tracks in the second embodiment.
Simultaneous reproduction of two systems from groove 1 and land 2 is performed under the interval setting condition of, but in the recording mode, the tracking servo operation point is set so that the focused spot in the recording operation state is located in the center area of the track to be recorded. Offset.

For example, referring to FIG. 4, a description will be given of the case where each of the focused spots B1 and B2 is selectively placed in the recording operation state. In the case of recording on the groove 1 (N), the focused spot B1 is indicated by a solid line. The focused spot B2 is set to the position indicated by, and the recording is performed using only the focused spot B1 in the state, and conversely, the recording to the land 2 (N) is performed. In this case, the focused spot B1 is set at the position indicated by the alternate long and two short dashes line, and the focused spot B2 is set at the position indicated by the solid line, and recording is performed using only the focused spot B2 in that state.

By the way, when the positions of the focused spots B1 and B2 with respect to the track are displaced as described above in the recording mode, the focused spot on the non-recording side is largely applied to the wobbling portion of the side wall 1a, and its reflection is caused. This is a convenient state for obtaining various control signals from light. That is,
For example, when recording is performed on the groove 1 (N) with the focused spot B1 at the position shown by the solid line in FIG. 4, the focused spot B2 on the non-recording side is at the position shown by the chain double-dashed line. It is convenient to detect the wobbling component of 1a.

Therefore, it is possible to obtain the focus / tracking / spindle control signal and the address signal from the output signal of the photodetector corresponding to the focused spot on the non-recording side. Recording can be performed while using the. For example, focused spot B1
When the recording side is on the recording side, the focused spot B in FIG.
Using the split output signal of the photodetector 4 corresponding to 2, the focus control signal from the average value of the added signal of each split output, the TE signal by the push-pull method by comparing the levels of both split outputs, the difference of each split output A signal is obtained, the wobbling modulation component of the difference signal is detected, the WobC signal is obtained, and the WobC signal is FM demodulated and decoded to obtain an ADD signal. Further, when the focused spot B2 is on the recording side, each control signal is obtained using the divided output signal of the photodetector 3 in the same manner as described above.

[0044]

The optical disk device of the present invention has the following effects due to the above configuration. According to the invention of claim 1, a light irradiating means which forms two converging spots, and irradiates each converging spot on each adjacent track of the optical disc at a constant interval in the linear velocity direction of the optical disc, In the optical disk device, which is provided with two light detecting means for independently detecting and photoelectrically converting the reflected light from each of the condensed spots, and capable of simultaneously reproducing the record information of each of the tracks, the information is simultaneously reproduced. Removes crosstalk components generated between each track,
The reproduced signal is detected with high accuracy. According to a second aspect of the present invention, in the optical disc apparatus of the two-beam system, the intervals between the focused spots are narrower than the track pitch in the direction orthogonal to the linear velocity direction of the optical disc, so that the tracks are simultaneously reproduced. The crosstalk from each track located outside and inside is suppressed. By applying the inventions of claims 1 and 2, even if high-density recording is performed like an optical disc in which information is recorded in both the groove and the land, the reproduced signal is accurately obtained without being affected by crosstalk. Can be detected.
According to the invention of claim 3, when information is recorded under the irradiation condition of each focused spot on the track of the disc in the invention of claim 1 or 2, only one focused spot is set to the recording operation state. By recording, the effect of return light noise is reduced, and high-precision recording is realized while ensuring stable servo control. Further, when the two focused spots are simultaneously brought into the recording operation state, the temperature rises and the semiconductor laser unit deteriorates to shorten the life. However, the present invention has an advantage that the problem can be solved.
According to a fourth aspect of the present invention, when recording is performed on adjacent tracks under the recording condition according to the third aspect of the invention under the condition for setting the interval of the focused spots according to the second aspect of the invention,
Recording can be performed by positioning the center of the focused spot in the recording operation state to the central region of the track, and the effect of claim 2 can be obtained in the reproduction mode, and the information can always be recorded at the proper position of the track in the recording mode. Realize an optical disk device. The invention of claim 5 relates to claim 3 and claim 4.
In the invention of (1), recording is performed using only one converging spot, but if the optical disc to be recorded has lands and grooves or wobbles between tracks, It becomes possible to detect various control signals by positively utilizing the focused spot of.

[Brief description of drawings]

FIG. 1 is a diagram showing a positional relationship between respective focused spots on an optical disc and a detection circuit of a reproduction signal in Example 1 of an optical disc of the present invention.

FIG. 2 is a graph showing a principle of crosstalk suppression [relationship between crosstalk generated in the groove 1 (N) and the lands 2 (N), 2 (N + 1) in FIG. 1] in Example 2;

FIG. 3 is a graph showing the principle of crosstalk suppression [relationship between crosstalk occurring in lands 2 (N) and grooves 1 (N), 1 (N-1) in FIG. 1] in Example 2;

FIG. 4 is a diagram showing a positional relationship between condensed light spots in Example 2 and Example 4;

FIG. 5 is a diagram showing a state of occurrence of a crosstalk area at the time of recording in Example 4.

FIG. 6 is a diagram showing the structure of a one-sided wobbling type optical disc and the position of a focused spot [(A) is an enlarged plan view of the disc, and (B) is a sectional view taken along the line XX of (A)].

FIG. 7 is a diagram showing the positional relationship of each converging spot on the optical disc in an optical disc device for a single-sided wobbling type optical disc, a detection circuit for TE signal, WobC signal, and ADD signal, and two systems of recording on a groove and a land. It is a figure which shows the detection circuit of the reproduction signal at the time of reproducing recording information.

[Explanation of symbols]

1,1 (N-1), 1 (N), 1 (N + 1) ... groove (track), 1a ... Wobbling side wall, 2,2 (N-1), 2 (N), 2 (N + 1) ... Land (track), 3, 4 ... Photodetector (3; First photodetecting means, 4; Second photodetecting means), 5,61 ... Delay circuit (delaying means), 6, 7 ... Attenuator (6; first attenuator, 7; second attenuator), 8,9,53,54,59 ...
Differential amplifier (8; first signal operation means, 9; second signal operation means), 51, 52, 62 ... Summing amplifier, 55, 56 ... BPF, 57, 58 ...
ENV circuit, 63 ... FM demodulator, 64 ... Decoder, B1, B2,
B01, B02 ... Focused spots (irradiated by light irradiation means), C1
(N), C1 (N-1), C2 (N), C2 (N + 1) ... Crosstalk level, L
... Each focused spot B1, in the linear velocity direction of the optical disc
B2 spacing, P0 ... track pitch, RF1, RF1 (N), R
F1 (N-1), RF2, RF2 (N), RF2 (N + 1) ... Playback signal, S1,
S2 ... Output signals of photodetectors 3 and 4, S1 '... Output signal of delay circuit 5, V ... Linear velocity of optical disk, .DELTA.d ... Focus spot B
1, B2 displacement amount.

Claims (5)

[Claims] 1. A light irradiating means for structuring two converging spots, and irradiating each converging spot on each adjacent track of the optical disc at a constant interval in the linear velocity direction of the optical disc. In an optical disk device that includes two light detection means for independently detecting reflected light from each focused spot and performing photoelectric conversion, and is capable of reproducing the recorded information of each track at the same time, regarding the linear velocity direction of the optical disk. Delay means for giving a delay to the output signal of the first light detecting means for detecting the reflected light of the converging spot that is previously irradiated and dividing the interval of each converging spot by the linear velocity of the optical disk and outputting the delayed signal. A first attenuating means for attenuating the output signal of the delay means with an attenuation ratio equal to the relative crosstalk ratio of the photodetection signal generated between the tracks, and the linear velocity of the optical disk. Second attenuating means for attenuating the output signal of the second light detecting means for detecting the reflected light of the converging spot irradiated subsequently in the degree direction, with the same attenuation ratio as the above.
First signal calculating means for obtaining a difference signal between the output signal of the delay means and the output signal of the second attenuating means, and second signal operation for obtaining a difference signal between the output signals of the first attenuating means and the second photodetecting means. And an optical disc apparatus, wherein each of the difference signals obtained by the first and second signal calculation means is used as a reproduction signal of recorded information of each track. 2. A light irradiating means for forming two converging spots and irradiating each converging spot on each adjacent track of the optical disc at a constant interval in the linear velocity direction of the optical disc, In an optical disk device that includes two light detection means for independently detecting and photoelectrically converting the reflected light from each converging spot and is capable of reproducing the recorded information of each track at the same time, in the linear velocity direction of the optical disk. An optical disk device characterized in that an interval between the respective focused spots in a direction orthogonal to each other is set smaller than a track pitch of the optical disc, and the focused spots are reproduced under an arrangement condition in which the focused spots are brought close to a track boundary side. 3. Light irradiating means for structuring two converging spots, and irradiating each converging spot on each adjacent track of the optical disc at a constant interval in the linear velocity direction of the optical disc, An optical disk device that includes two photodetectors that independently detect and photoelectrically convert the reflected light from each focused spot, and is capable of recording / reproducing two systems of record information for adjacent tracks of the optical disk. In the recording mode, the optical disk device is characterized in that recording is performed using only one focused spot. 4. An optical disk device for recording / reproducing two systems of record information for each adjacent track of an optical disk under the recording spot setting condition according to claim 2 under the recording condition according to claim 3. , Providing a condensing spot displacement means for displacing each condensing spot so that one condensing spot is located in the central region of the track,
In the recording mode, the optical disk device is configured to perform recording only on the side of the focused spot located in the central area of the track by the focused spot displacement means. 5. The optical disk device according to claim 3 or 4, wherein a recording operation is performed when recording is performed on an optical disk having lands and grooves or an optical disk having wobbling between tracks. An optical disc device which obtains various control signals by using output signals of a photodetector corresponding to a non-focused spot.