JP3123841B2 - Optical disk recording and playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording / reproducing apparatus for performing high-speed reading.

In recent years, as the amount of information handled by computers has increased, large-capacity memories have become necessary, and read-only or rewritable optical disks have been used as recording media. When accessing such an optical disc, high-speed reading is required. Therefore, in high-speed reading, it is necessary to replace the medium with another device and to maintain the recording density.

[0003]

2. Description of the Related Art Conventionally, there has been an optical disk recording / reproducing device as an external storage device of a computer or the like, and a magneto-optical disk is used as a recording medium thereof.

FIG. 4 is a diagram showing a medium configuration of a magneto-optical disk. In FIG. 4, the magneto-optical disk 11 has a recording layer 13 formed on a substrate 12, and a pre-groove 14 which is a track guide groove for a light spot to follow a predetermined track has a track pitch. It is formed beforehand at 1.6 μm. Land portions 15 are formed between adjacent pregrooves 14. The land 15 is irradiated with a minute spot collected by the objective lens. An ID signal such as a track number or a sector number is previously formed at a predetermined position of the land portion 15 in the form of unevenness as shown by 16 in FIG.

The recording information (user data) is recorded on the recording layer 13 of the land 15 following the ID signal recording pit 16 by the mark length recording method, for example, as the direction of the magnetization of the magnetic film instead of the unevenness, as indicated by 17. It is recorded by a light beam. During both recording and reproduction, the light beam is incident from the back surface of the substrate 12 and is focused on the recording layer 13 so as to be focused.

[0006] The reproduction of such a magneto-optical disk 11 is 1
High-speed reading is demanded because access is performed by tracks and an access time is required. As a method of performing high-speed reading, increasing the number of rotations of a disk and setting a high clock frequency during data reproduction are performed.

Further, as another method, the track interval is narrowed (the pre-groove is narrowed) without changing the spot diameter of the light beam, and two tracks are read out with one spot light beam, or the track interval is changed. By increasing the spot of the light beam to two tracks without causing the
In recent years, reading a track portion at twice the speed by irradiating a light beam at a time has been performed in recent years.

[0008]

However, increasing the number of rotations of the disk at the time of high-speed reading requires high-precision servo, and increasing the clock frequency with high density requires shortening the optical wavelength. However, there is a problem that it is difficult with a semiconductor laser.

The method of narrowing the track interval of the magneto-optical disk can be used for a device other than a device capable of reading and reproducing data of two tracks or a device capable of performing tracking servo even with a narrow pre-groove. There is a problem that compatibility is lost.

Further, increasing the spot of the light beam to two tracks must be performed with a light beam having a large spot in data recording, and the linear density (the amount of data recordable in the data portion of the track) is reduced. Then I
There is a problem that reading cannot be performed on an SO standard disk.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an optical disk recording / reproducing apparatus which is medium replaceable and can easily perform high-speed reading while maintaining the disk rotation speed and the recording density. I do.

[0012]

The object of the present invention is to irradiate a light beam on a track of an optical disk to record data,
In an optical disc recording / reproducing apparatus for reading recorded data, information including a tracking servo mark, a track identification mark, and predetermined clock data is recorded on the optical disc in advance, and when recording data on the optical disc, First irradiating means for irradiating a first light beam having a Gaussian distribution corresponding to one track width of the optical disc, and a width of two tracks with respect to a tangential direction of the optical disc during reproduction; Second irradiating means for irradiating a second light beam having the same width as the first light beam in a linear direction, and one track from reflected light from two tracks of the optical disk by the second light beam The problem is solved by having a configuration having a processing unit for reproducing data for each of them.

[0013]

As described above, the first light beam from the first irradiation means is used for recording, and the second light beam from the second irradiation means is used for reproduction. The first light beam has a Gaussian distribution corresponding to one track width, and the second light beam has a width of 2 with respect to the normal direction of the optical disk.
The beam corresponds to the width of the track and has the same width as the first light beam in the tangential direction.

That is, since the recording and reproduction of data recorded on one track is performed by irradiating the first and second light beams corresponding to the width of one track, the conventional high-density recording can be maintained. The optical disk of the medium is the same as that used in general, and can maintain compatibility with other devices. Further, at the time of reading, two tracks are read at a time, and data is separated for each track, thereby enabling high-speed reading.

[0015]

FIG. 1 is a block diagram showing an embodiment of the present invention.
In FIG. 1, an optical disk recording / reproducing device 21 irradiates an optical disk (magneto-optical disk) 22 with a light beam (laser beams 24a, 24b) via an objective lens.

A first light source 25 composed of a semiconductor laser
The light beam (laser beam) radiated from the laser beam enters a beam splitter 27 formed by a prism as a first light beam 24a via a first beam shaper 26. The first light source 25 and the first beam shaper 26 constitute a first irradiation unit.

On the other hand, a light beam (laser beam) emitted from a second light source 28 composed of a similar semiconductor laser
Enters the beam splitter 27 as a second light beam 24b via the second beam shaper 29 and the aperture 30. The second light source 28 and the second beam shaper 2
9 and the aperture 30 constitute a second irradiation unit.

First and second light beams 24a, 24b
The objective lens 2 is made to have the same optical path by a beam splitter 27, and a polarizer 31 as a polarizing means, a beam splitter 32 formed by a prism, and a reflection mirror 33.
3 is incident.

At the time of reproduction, reflected light from the optical disk 22 is:
Objective lens 23, reflection mirror 33, beam splitter 3
2 to the processing means. In the processing means, the light beam from the beam splitter 32 is split by a beam splitter 34 formed by a prism, and one of the light beams is received by a servo light receiving unit 36 via a lens 35. Tracking servo for moving the objective lens 23 and the reflection mirror 33 is performed based on the light receiving state of the light receiving section (photodetector) 36.

The other is split by a beam splitter 38 formed by a prism via a wavelength plate 37 and received by light receiving units (photodetectors) 40 and 42 for data via lenses 39 and 41, respectively.

The signals from the light receiving sections 40 and 42 are input to a subtractor 43 and an adder 44, respectively, and the data signals for two tracks of high frequency (RF) output from the subtractor 43 are input to a signal separating section 45. At the same time, the clock signal (CLK) output from the adder 44 is input to the clock unit 46 and separated into clocks for each track.

The signal separating section 45 separates the data signal for each track on the basis of the clock for each track from the clock section 46, and stores the data signals in the memories 47a and 47b of the memory section.

FIG. 2 is a diagram for explaining a recording format of the optical disk of FIG. As shown in FIG. 4, the optical disk (magneto-optical disk) 22 shown in FIG. 2 has tracks 22a, which are lands, and track guide grooves 22b, which are pre-grooves, formed alternately on the recording layer. Here, the tracks 22a ₁ , 22
The a ₂ will be described as an example.

As shown in FIG. 2, each track 22a ₁ ,
22a ₂ is divided into an information area 51 and a data area 52, and a signal as information is recorded in the information area 51 in advance, and predetermined data is recorded in the data area 51 at the time of recording. .

The information area section 51 includes a predetermined number of clock areas 51a, address areas 51b, and the like.
Adjacent tracks 22a in 1a _1, 22a ₂ at a predetermined frequency with different half clock phase clock data 5
3 is recorded. The data recorded in the data area 52 is also recorded with a phase difference of a half clock between the adjacent tracks 22a ₁ and 22a ₁ according to the clock data.

In the information area 51, a predetermined number of tracking servo sample marks 54 are formed at the boundary between the track 22a and the groove 22b so as to cross each other.

Such a magneto-optical disk 22 has, for example, a track 22a and a groove 22b formed on a 3-inch GGG (gadolinium gallium garnet) substrate, and a mark of predetermined information formed thereon, thereby forming a Ce-substituted garnet. It is formed by sputtering and depositing Al (aluminum) thereon as a reflective film. The sputtering was performed using garnet (Ce ₂ DyG
a _0.8 Fe _4.2 O ₁₂ ), sputtering gas Ar, gas pressure 1.
The film thickness is 0.2 μm at 5 Pa, power 200 W. The degree of vacuum before vapor deposition is 4 × 10 ⁻⁴ Pa.

Such a magneto-optical disk 22 has a recording power of 8 mW, an external magnetic field of 350 Oe, and a read power of 1 mW.
Recording and reproduction are performed.

FIG. 3 is a diagram for explaining the laser beam shown in FIG. FIG. 3A shows the first light beam 2.
4A shows the shape of the second light beam 24b. FIG. 3B shows the shape of the second light beam 24b.

As shown in FIG. 3A, the first type shown in FIG.
The semiconductor laser having a wavelength of 780 mm emitted from the light source 25 becomes a first light beam 24a of a perfect circle by the first beam shaper 26, and is emitted at the time of recording. The first light beam 24a is a beam having a diffraction-limited Gaussian distribution corresponding to one track width, and its shape and size are the same as those conventionally used.

On the other hand, as shown in FIG. 3B, a semiconductor laser having a wavelength of 780 mm emitted from the second light source shown in FIG. Beam shaping is performed by setting the effective light flux of the objective lens 23 to 3 mm.
In this case, the beam is set to 3 mm so as to be diffraction-limited in the tangential direction of the optical disk 22 as in the case of the first light beam 24a, and is set to 2 mm so that the beam width becomes two tracks in the normal direction. It is performed to be a beam. This is made elliptical (or rectangular) by the aperture 30.
Then, when the second light beam 24b is incident on the objective lens 23, a beam of 2.6 μm is obtained on the optical disk 22.

Next, the above-described optical disk recording / reproducing device 21
Will be described.

First, recording will be described. With respect to the rotating optical disk 22, the polarization directions of the two semiconductor lasers (first and second light sources) are matched with the polarization directions of the beam splitter 27, and the first light source 25 and the first beam shaper 26 perform the second polarization. One light beam 24a (FIG. 3A)
Is incident on the polarizer 31 via the beam splitter 27. The polarizer 31 is formed of, for example, a ferroelectric substance (for example, ammonium biphosphate (ADP)), and rotates the polarization plane (S or P) of the first light beam 24a to align the polarization plane with the beam splitter 32. This is performed during recording or reproduction.

For example, when the polarization is rotated at the time of recording, the power of the first light beam 24a is increased and made incident on the polarizer 31.
The optical disc 22 is rotated by an angle of .degree. To be incident on the beam splitter 32, and has a recording power of 8 mW on the surface of the optical disk 22, for example.

In this case, as described with reference to FIG. 2, the recording of data is performed by changing the phase by a half clock from that of an adjacent track. The tracking is performed by a normal push-pull method using the light receiving unit 36 and the groove 22b.

Next, the reproduction operation will be described. Second light source 28, second beam shaper 29, and aperture 30
The second light beam (see FIG.
(B)) 24 b is incident on the polarizer 31 via the beam splitter 27. The polarizer 31 allows the second light beam 24b to pass without applying a voltage to the beam splitter 32.
At a read power of 3 mW on the surface of the optical disk 22, for example. If the laser power is sufficient, the beam splitter 27 may be depolarized and the polarizer 31 may be omitted.

In this case, tracking is performed by normal sample servo using sample marks 54 recorded in advance using the light receiving section 36.
₁ , 22a _{2 is} the center servo.

The second light beam 24b is applied to the optical disk 2
Irradiation is performed on two tracks 22 ₁ and 22a _{2 on 2} , and data (reflected light) for two tracks is input (received) to the light receiving units 40 and 41 via the beam splitters 32, 34 and 38.

The outputs of the light receiving sections 40 and 41 are input to a subtractor 43, where data for two tracks of a track identification mark 55 and a data area section 52 are extracted and input to a signal separation section 45. You. The outputs of the light receiving units 40 and 41 are input to the adder 44 and added, and the clock CL
It is input to the clock unit 46 as K.

In the clock section 46, each track 22
Clocks having different phases by a half clock corresponding to a ₁ and 22a ₂ are extracted and sent to the signal separation unit 45, respectively. The signal separating unit 45, the tracks to be synchronized from the data of two tracks, for example, the data the tracks 22a ₁ which is synchronized with the frequency of the recorded tracks 22a ₁ clock, the frequency of the clock that is recorded in the track 22a ₂ 22
a Separate the data of ₂ . And each track 22
a ₁ and 22a ₂ are stored in the memories 47a and 47a, respectively.
b, and sends data to the main unit at the same time when one round of reading is completed.

As described above, recording on the optical disk 22 is performed as follows.
Since high-density recording is performed in a normal format by the first light beam 24a, compatibility with other devices of the optical disc can be maintained, and reproduction can be performed for every two tracks. The reading can be performed twice as fast as before without increasing the number or reducing the recording density.

In the above embodiment, the case where the first and second light sources are semiconductor lasers has been described. However, in order to further increase the density, a short-wavelength laser (eg, N
The same effect can be obtained by using d: YVO ₄ , Nd: YAG, SHG (second harmonic generation element).

[0043]

As described above, according to the present invention, recording is performed with the first light beam having a normal beam width, the width is two tracks with respect to the normal direction of the optical disk, and the width is tangential. On the other hand, by performing reproduction with the second light beam having the same width as the first light beam, the medium can be exchanged with another apparatus, and high-speed reading can be easily performed while maintaining the disk rotation speed and recording density. Is what you can do.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram for explaining a recording format of the optical disc of FIG. 1;

FIG. 3 is a diagram for explaining the laser beam of FIG. 1;

FIG. 4 is a diagram showing a medium configuration of a magneto-optical disk.

[Explanation of symbols]

 Reference Signs List 21 optical disk recording / reproducing device 22 optical disk 23 objective lens 24a first light beam 24b second light beam 25 first light source 26 second light source 27, 32, 34, 38 beam splitter 28 second light source 29 second Beam shaper 30 aperture 31 polarizer 45 signal separation unit 46 clock unit 47a, 47b memory

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-302933 (JP, A) JP-A-4-123331 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/00-7/013 G11B 7/12-7/22 G11B 7/28-7/30

Claims (6)

(57) [Claims] A track (22) on an optical disc (22).
a) irradiating a light beam (24a, 24b) on the optical disk to record data and read out the recorded data; Information including an identification mark (55) and predetermined clock data (53) is recorded. When data is recorded on the optical disc (22), a Gaussian distribution corresponding to one track width of the optical disc (22) is recorded. A first irradiating means (25, 26) for irradiating a first light beam (24a); and a second irradiating means with respect to a normal direction of the optical disc (22) during reproduction.
A second track having the same width as the first light beam (24a) in the tangential direction of the optical disc (22);
The second irradiation means (28) for irradiating the light beam (22b)
30) and the optical disk (2) by the second light beam (24b).
Processing means (34-47a, 47b) for reproducing data for each track from the reflected light from the two tracks of 2)
An optical disk recording / reproducing apparatus, comprising: 2. The first and second light beams (24a, 24a,
24b), the first and second light beams (24
2. The optical disk recording / reproducing apparatus according to claim 1, further comprising a polarizing means (31) for rotating a polarization plane with respect to a, 24b). 3. The tracking servo mark (5)
4) to the track (22a) of the optical disc (22).
3. The optical disk recording / reproducing apparatus according to claim 1, wherein a predetermined number is formed on both sides of a boundary between the track and a track guide groove (22b) formed between the tracks (22a). 4. The clock data (53) prerecorded on the optical disk (22) and the data recorded upon recording are recorded on the adjacent track (22a) and the clock data (53) recorded upon recording. 4. The optical disk recording / reproducing apparatus according to claim 1, wherein the data is recorded with a phase difference of a half clock. 5. The optical disc according to claim 1, wherein the track identification mark (55) prerecorded on the optical disc (22) is a code for identifying an adjacent track (22a). Recording and playback device. 6. The processing means reads data of the two tracks and separates the data for each track (22a) based on the clock data (53) recorded on the read track. 6. The optical disk recording / reproducing apparatus according to claim 1, further comprising: a signal separating section (45) for performing the recording and a memory section (47a, 47b) for storing the data for each of the tracks (22a).