JP3005648B2 - Optical disk recording method and optical disk 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 device, and more particularly to an optical disk recording method and an optical disk device for recording or reproducing a multi-track signal on an optical disk by a multi-beam optical head having a multi-beam emitting semiconductor laser.

[0002]

2. Description of the Related Art Conventionally, in order to realize a high transfer rate in an optical disk device, for example, two or four lines are used.
A multi-beam emission semiconductor laser that emits laser light from a plurality of light sources such as a tree (hereinafter, referred to as a multi-semiconductor laser)
There has been proposed a multi-beam recording system in which a plurality of light spots are formed on an optical disk by using a multi-beam optical head provided with the optical disk and recording and reproduction of a plurality of signal tracks are simultaneously performed. Conventionally, in the case of a multi-beam recording system of this type, for example, when the number of multis is four, that is, four beams, the width of the groove of the optical disk is 0.4 μm and the groove pitch is 1 as in a normal optical disk using one laser light source. Each of the grooves is irradiated with four beams to record and reproduce signals, and a tracking error is detected by a push-pull method for each groove (ie, track groove).

[0003]

In the above conventional method,
The tracking error detection by the push- pull method has a problem that the stability of the tracking servo is low because the tracking error detection is easily affected by the disc surface deflection due to the use of the diffraction effect at the time of reflection at the groove. Further, the and the influence of the diffraction effect in the groove as well occur in the recording reproducing signal because recording signals on the track groove, the question of low reliability of the recording and reproducing
There is also a title . Also, with respect to the optical disc itself, since the track grooves are dense, it is not easy to mold the disc.
Japanese Patent Application Laid-Open No. 4-82021, "Optical Recording / Reproducing Apparatus", published after the filing of the present application, discloses that one or two laser beams provided on an information recording medium are provided with any two of the four laser beams. It irradiates the edge of the guide part on the different side, detects the tracking error signal by the twin beam method from the reflected light, adjusts the tracking, and irradiates the remaining laser beam to the land to record and reproduce information. An apparatus of this kind is disclosed. However, this apparatus is configured such that the oblique angle formed by the four spots formed by the four laser beams irradiated on the optical disc with respect to the radial direction of the disc can be variably adjusted. Therefore, the width of the guide part or land part had a solid difference that was not within the range assumed at the time of design .
Fix the width of the optical disc or guide groove or flat part
There is no body difference, but there is apparent solid difference due to the influence of mounting posture etc.
When recording or reproducing an optical disk or the like , the irradiation spot of the laser beam may protrude from the target land portion, or only one of the laser beams in the center two rows may be applied to the edge of the guide portion. playable optical disk were those facing the problem that is limited constant.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional disadvantages, and enables stable tracking control irrespective of the type of optical disk, and also improves the reliability of signal recording and reproduction. An object of the present invention is to provide an optical disk recording method and an optical disk device that can perform the method.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a shaft capable of obliquely adjusting an optical disk having a flat portion formed between spiral guide grooves at an arbitrary angle with respect to the disk radial direction. Laser light is emitted from a plurality of light sources arranged on a line, and two central rows of laser light of the plurality of laser lights are irradiated on both sides of the guide groove so as to partially overlap the guide groove, and the reflected light is received. In this method, tracking control is performed by a twin beam method, and a laser beam of the same number as the number of the light sources applied to the flat portion forms a multitrack and records a signal.

[0006]

In the above configuration, in the tracking error detection performed by the twin beam method using two light spots formed on both sides of the guide groove, the diffraction effect in the groove is canceled out and the influence is small, and a stable tracking servo is performed. It can be performed.

Further, since recording and reproduction of a signal is performed on a flat portion of the disk surface, there is no problem due to the effect of the diffraction effect in the groove, and the reliability of recording and reproduction is high.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a configuration of a multi-beam optical head in an optical disk apparatus according to an embodiment of the present invention. Reference numeral 1 denotes a 6-beam emitting semiconductor laser (hereinafter abbreviated as 6-beam laser) for emitting laser light from six light sources, for example. Reference numeral 2 denotes a collimator lens for converting the diffused light emitted from the six-beam laser 1 into parallel light, and the six-beam laser 1 and the collimator lens 2 are integrated by a frame 3. By rotating the body 3, the rotation of the six-beam laser 1 can be adjusted. Reference numeral 4 denotes a polarization beam splitter, reference numeral 5 denotes an objective lens for forming a light spot by focusing parallel light on a signal surface of the optical disk 6, and reference numeral 7 denotes a device for rotating a polarization plane of transmitted light (linearly polarized light) by 45 °. / 2 wavelength plate, reference numeral 8 denotes a condenser lens, reference numeral 9 denotes a Wollaston prism for separating incident light into two light beams of ordinary light and extraordinary light, and reference numeral 10 denotes return light reflected on the disk surface. It is a photodetector. This photodetector has eleven elements A, B, C, D, F, G,
It has a total of 14 elements 11 of H, I, M, N and three elements J, K, L constituting a three-division optical sensor. That is, the multi-number M of the six-beam optical head
(6 in this case) and 2M + 2 (2 × 6 + 2 in this case)
= 14) elements. The three-division optical sensors J, K, and L are divided into three in order to detect a focusing error by a beam size method, as described later.

As shown in FIG. 4, the optical disk 6 used has a width of the guide groove 6a of 0.4 μm and a groove pitch of 8.4 μm. When the number M of the grooves is 6, the groove pitch is preferably about 20 times the groove width. As shown in FIGS. 3 and 4, the six light spots formed by the six-beam optical head are formed by combining two central light spots formed on both sides of the guide groove 6a so as to partially overlap the guide groove 6a. The six symmetrical pieces are formed on the flat portion 6b of the optical disk 6. That is, signal recording is performed on the flat surface 6b of the optical disk 6.

In the above-described six-beam optical head, laser beams emitted from the six laser light sources of the six-beam laser 1 are collimated by the collimator lens 4, transmitted through the polarization beam splitter 4, and transmitted by the objective lens 5. The light is condensed to form a light spot on the flat surface 6b of the optical disk 6 as shown in FIG. In other words, the center 2 which partially covers the guide groove 6a
6 light spots combining the two light spots into a flat surface 6b
Formed. The return light reflected from the optical disk surface and returned along the same path is reflected at right angles by the polarization beam splitter 4, passes through the half-wave plate 7, changes the polarization plane by 45 °, and is collected by the condenser lens 8. Lighted, Wollaston prism 9
As a result, each of the six light beams is separated into two light beams, an ordinary light and an extraordinary light, and becomes a total of 12 light beams.
Twelve focal points are formed on the photodetector 10 as shown in FIG. In this case, the focusing error signal is Fo, the tracking error signal is Tr, and the reproduced RF signals of the first to sixth channels are RF1, RF2, and RF, respectively.
Assuming that 3, RF4, RF5, and RF6, Fo = (J + L) -K
Tr = (C + (L + K + J))-(D + I)
RF1 = A-N
RF2 = BM
RF3 = C- (L + K + J)
RF4 = DI
RF5 = E−H
RF6 = FG
It is.

That is, the focus error detection is as follows.
The beam size method is performed by detecting the size of the beam irradiated to the three-division optical sensors J, K, and L. Further, the tracking error detection employs a twin beam method using two central light spots that partially overlap the guide groove 6a. Further, the detection of each reproduction RF signal is performed by taking the difference between the outputs of two elements (for example, elements A and N) that receive two light beams separated by the Wollaston prism 9 by ordinary light and extraordinary light. RF signals are used.
As described above, by constructing the differential detection optical system using the Wollaston prism, the reproduction R with less noise is achieved.
An F signal is obtained.

When six light spots are formed on the signal surface of the optical disk 6, they are arranged at an angle θ with respect to the guide groove 6a as shown in FIG.
, And six light spots must be accurately positioned on each signal track. For this purpose, the rotation of the six-beam laser 1 needs to be adjusted. As shown in FIG. 5, the rotation of the six-beam laser 1 is adjusted by a frame body integrally attached to the collimator lens 5 and the six-beam laser 1. 3 is rotated around the center of the collimator lens . For this reason,
For example, the width dimension of the guide groove or flat part was assumed at the time of design.
Optical discs or guides with individual differences not within the range
There is no individual difference in the width dimension of the groove or flat part, but the mounting posture etc.
Record or record optical discs that have apparently
In the case of reproduction, place the frame 3 at the center of the collimator lens.
Rotate around and adjust the rotation of 6 beam laser 1
The effect of the difference can be eliminated.

FIG. 6 shows the three-division optical sensors J, K, and L.
Instead, replace the central element K with K₁, K₂, K₃of
5-division optical sensor J, K divided into three elements₁,
K₂, K₃, L are shown. Illustration omitted
However, the size of the other 11 elements is
K₂Of the same size. In this case, Focusing
The error signal Fo is expressed as Fo = (J + L)-(K₁+ K₂+ K₃) To detect. In other words, focusing error detection
The beam size method in the case of the aforementioned three-segment optical sensor and
Exactly the same. The reproduction RF signal (RF) is RF = K₂  And That is, the output of the reproduced RF signal is
Mend K₂Only output. This small eleme
If the playback RF signal is detected by the
Since the light is received only at the center of the light spot,
Thus, signal-free signal reproduction is performed.

FIG. 7 shows an element arrangement of the photodetector 10 'when the focusing error is detected by the astigmatism method. In this case, the part for performing the focusing error detection is constituted by the four-division optical sensors J, K, L, and M. That is, 2M + 3 for the multi-number M (6 in this case)
(In this case, 2 × 6 + 3 = 15) elements are provided. The focusing error signal Fo is as follows: Fo = (J + L)-(K + M).

[0015]

According to the present invention, between spiral guide grooves,
With respect to the optical disk on which the flat part is formed,
Lined up on an axis that can be adjusted obliquely at an arbitrary angle to the direction
Laser light is emitted from a plurality of light sources, and
The two central rows of laser light are projected on both sides of the guide groove, respectively.
Irradiate the inner groove partially overlapping, receive the reflected light and
Perform tracking control by the in-beam method, and
The same number of laser beams as the number of
Since a track is formed to record a signal, an optical disc having a difference in the guide groove or the flat portion having a width dimension not within the range assumed at the time of design , or a guide groove or
Although there is no difference in the width of the flat part,
When recording or reproducing an optical disk or the like having an apparent solid difference, it is possible to cope with the oblique adjustment of the axis connecting the plurality of light sources at an arbitrary angle with respect to the disk radial direction. It does not protrude from the flat portion or that only one of the two rows of laser beams in the center can irradiate the edge of the guide groove, enabling free recording or reproduction according to the type of optical disc, and tracking. Since the error detection is performed by the twin beam method using two light spots formed on both sides of the guide structure of the optical disc, the diffraction effect in the groove is canceled and the influence is small, and stable tracking servo can be performed. And so on.

Further, since the recording and reproduction of the signal is performed on the flat portion of the disk surface, there is no problem of the effect of the diffraction effect in the groove, and the effect of improving the reliability of the recording and reproduction can be obtained.

Also, since the guide grooves of the optical disk itself are not closely spaced, the disk can be easily formed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a multi-beam optical head in an optical disc device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an element arrangement of the photodetector in FIG.

FIG. 3 is an explanatory diagram of a light spot irradiated on a disk surface by the multi-beam optical head of FIG. 1;

FIG. 4 is a diagram for elucidating a groove pitch dimension of an optical disc.

FIG. 5 is an explanatory view of integrally rotating a multi-beam emission semiconductor laser and a collimator lens.

FIG. 6 shows another embodiment of the photodetector, and is an arrangement diagram of some elements of the photodetector.

FIG. 7 shows still another embodiment of the photodetector, and is an element arrangement diagram of the photodetector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Multi-beam emission semiconductor laser 2 Collimator lens 3 Frame 6 Optical disk 6a Guide groove 6b Flat part 9 Wollaston prism 10 Photodetector A, B, C, D, E, F, G, H, I, J, K , L,
M, N, O elements K _{1, K} 2, _{K 3} elements

Claims (4)

(57) [Claims] 1. A laser beam is emitted from a plurality of light sources arranged on an axis that can be obliquely adjusted at an arbitrary angle with respect to a radial direction of a disc with respect to an optical disc having a flat portion formed between spiral guide grooves, The center two rows of laser beams of the plurality of laser beams are irradiated on both sides of the guide groove so as to partially overlap the guide grooves, and the reflected light is received to perform tracking control by the twin beam method, and the flat portion is formed. An optical disc recording method, wherein the same number of laser beams as the number of light sources applied to the optical disc form a multitrack and record signals. 2. An optical component having a photodetector having (2M + 2) elements for the number M of the light sources, and separating one beam into two in an optical path of return light toward the photodetector. 2. The optical disk recording method according to claim 1, wherein a recording signal is detected by a differential method using the two separated beams, and a focusing error is detected by a beam size detection method. 3. The optical disk recording according to claim 1, wherein a photodetector having (2M + 3) elements for the number M of the light sources is provided, and a focusing error is detected by an astigmatism method. Method. 4. An optical disk having a flat portion formed between spiral guide grooves, wherein a laser beam is emitted from a plurality of light sources arranged on an axis which can be obliquely adjusted at an arbitrary angle with respect to the disk radial direction. A beam emitting semiconductor laser, a collimator lens coupled to the multi-beam emitting semiconductor laser so as to be integrally rotatable, and a central two-row laser beam of the plurality of laser beams transmitted through the collimator lens, on both sides of the guide groove. And a tracking control unit that receives reflected light from the optical disk via the objective lens and performs tracking control by a twin beam method. Optical disk device.