JPH09180214A - Optical head device in optical disk device and detecting method for track wobbling signals using the head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical head device of optical disk device, in which errors in reading wobbling signals are small, and a detection method of track wobbling signals using the head device by arranging an optical detecting element, which is located in the outer most peripheral, at the position where no zero-order light of the reflection optical beam is received. SOLUTION: An optical detector 34 consists of photodetectors 35 and 36 provided on a semiconductor substrate 37. Each of the photodetectors 35 and 36 separately has four strip-like photodetecting elements, respectively. Moreover, a semiconductor laser element 31 and a prism 33 are provided on the substrate 37. The substrate 37 is fixed to the case reference surface of an optical head device 30 so that the extending directions of the separation sections of each element of the photodetectors 35 and 36 are placed to a prescribed angle between 0 to 90 degrees with respect to the direction which corresponds to the recording track (the wobbling group) of an optical disk 1. Thus, zero-order light beam spots are projected on the region of each photodetector and wobbling signals are accurately detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an optical disc having a wobbling groove formed therein, makes a light beam incident on the optical disc, guides a reflected light beam from the optical disc to a light receiving section, and outputs an optical disc from the optical signal from the light receiving section. The present invention relates to an optical head device in an optical disc device for controlling a rotation speed and obtaining a track wobble signal capable of accurately reading information signals such as music information and address information, and a method for detecting a track wobble signal using the same. is there.

[0002]

2. Description of the Related Art First, a conventional optical head device will be described with reference to FIGS. FIG. 5 is a partial cross-sectional perspective view of a mini disk which is a currently used magneto-optical disk, FIG. 6 is a side view schematically showing an optical head device used in the mini disk device, and FIG. FIG. 7 is a plan view of a light receiving portion mounted on the optical head device shown in FIG.
FIG. 8 is a signal processing block diagram for obtaining a tracking control signal and a track wobble signal from the detection signals detected by the optical head device shown in FIGS. 6 and 7.
9 shows the state of the spot of the reflected light beam from the optical disk, FIG. 9A shows the state before passing through the objective lens, and FIG. 9B shows the state after passing through the objective lens. It is a top view.

FIG. 5 shows a mini disk (MD) 1 as an optical disk. On the surface of this mini disc 1,
The dielectric film 3 is formed on the surface of the PC substrate 2, and the magnetic film 4 is formed on the surface thereof.
However, the dielectric film 5 is formed on the surface, and the reflection film 6 is formed on the surface.
, And a protective film 7 is further laminated on the surface to form a recording surface. And on the surface of the mini disc 1,
For example, a width of 1.1 μm, a pitch of 1.6 μm and a frequency of 20
A wobbling groove having a KHz sine wave is spirally formed as a recording track T, and an information signal is recorded along the recording track T.

A CD device for reproducing recorded information from a magneto-optical disc such as a mini disc as such an optical disc or an optical disc such as a CD (hereinafter, the magneto-optical disc and the optical disc are collectively referred to as "optical disc") 1. In an optical disc device such as an MD device, FIG.
The optical head device 10 for reading the information recorded on the optical disc 1 by making the laser light beam incident on the optical disc 1 as shown in FIG. This optical head device 1
0 generates a laser light beam, which is formed on the optical disc 1 and has the extremely narrow recording track T as described above.
It is required that the light beam be incident on the recording track T accurately in a focused state, and that the reflected laser light beam from the recording track T of the optical disk 1 be accurately guided to the photodetector 14, and thus the semiconductor is used. The laser element 11, the objective lens 12 facing the optical disk 1, other lenses, various optical elements such as the mirror or prism 13, the photodetector 14 are precisely arranged, and all of them are
Focus control for supporting and configuring the objective lens 12 so that it can be displaced in the direction along the optical axis and in the direction orthogonal thereto, and for making the laser light beam incident on the recording track T formed on the optical disc 1 in an appropriate focused state. And tracking control for causing the laser light beam to accurately follow the recording track T formed on the optical disc 1, and track wobble for accurately controlling the rotation of the optical disc 1 to obtain an accurate information signal and address information. It is equipped with the function of obtaining signals.

The focus control performed in the optical head device 10 is based on a detection signal obtained by detecting the reflected laser light beam from the recording track T of the optical disc 1 by the photodetector 14 and recording track T in the optical disc 1. A focus error signal that changes according to the focusing state of the laser light beam incident on the laser beam is formed, and, for example, the objective lens 12 is generated according to the focus error signal.
Is performed along the optical axis direction, and the tracking control is based on a detection signal obtained by detecting the reflected laser light beam from the recording track T of the optical disc 1 by the photodetector 14. A tracking error signal having a change according to the follow-up state of the laser light beam incident on the recording track T on the optical disc 1 with respect to the recording track T is formed. According to the tracking error signal, for example, the optical axis direction of the objective lens 12 is changed. It is performed by displacing in the direction orthogonal to the recording track T. Furthermore, a track wobble signal for controlling the number of revolutions of the optical disc 1 is also formed based on a detection signal obtained by detecting the reflected laser light beam from the recording track T of the optical disc 1 by the photodetector 14, and this track wobble signal The frequency of the spindle motor for rotating the optical disk is controlled based on the above.

In the photodetector 14, for example, as shown in FIGS. 6 to 9, two light receiving portions 15 and 16 are arrayed and formed inside a semiconductor substrate 17, and the semiconductor substrate 17 is also formed. The semiconductor laser element 11 is arranged on the surface,
Although not shown, the surface on which the semiconductor laser device 11 is arranged is covered with a protective film, and the prism 13 is arranged on the protective film at a position corresponding to the light receiving portions 15 and 16 to form an integrated structure. Has been converted. The prism 1
3, the surface facing the semiconductor laser element 11 is a light semi-transmissive reflective surface 13A that is inclined with respect to the surface of the semiconductor substrate 17 on which the semiconductor laser element 11 is arranged.

In the photodetector 14 having such a configuration, the laser light beam emitted from the semiconductor laser element 11 is reflected by the light semi-transmissive reflecting surface 13A of the prism 13 through various optical devices (not shown), and the objective is obtained. It enters the recording track T of the optical disc 1 through the lens 12. And optical disc 1
The reflected laser light beam from the recording track T passes through the objective lens 12 and the light semi-transmissive reflection surface 13A of the prism 13 and enters the prism 13. A part of the reflected laser light beam that has entered the prism 13 reaches the light receiving portion 15, and another part of the reflected laser light beam reaches the light receiving portion 16 after being reflected inside the prism 13. At that time, the reflected laser light beam is formed in the prism 13, and is received from the light receiving unit 15 to the light receiving unit 1.
It is set so as to have a focal point on the optical path reaching 6. Therefore, the reflected laser light beam from the recording track T of the optical disc 1 is incident on each of the light receiving portions 15 and 16.

The light receiving portion 1 provided on the semiconductor substrate 17
Each of 5 and 16 is composed of two photodetecting elements. That is, the light receiving section 15 is composed of two strip-shaped photodetection elements Da and Db which are separated by the separating section E and are arranged side by side in the same plane, and the light receiving section 16 is
2 separated in the same plane by the separation part E and arranged in parallel
It is composed of individual strip-shaped photodetectors Dc and Dd.

The light receiving portions 15 and 16 are formed, and the semiconductor laser element 11 and the prism 13 are formed.
In the semiconductor substrate 17 provided with, the direction in which the respective separating portions E of the light receiving portions 15 and 16 extend on the reference surface of the case of the optical head device 10 generally corresponds to the recording track T direction of the optical disc 1 ( It is fixed at a predetermined angle θ between 0 and 90 degrees with respect to the direction indicated by the arrow X). In the case of the example shown in FIG. 7, θ = 0.
Therefore, the respective photodetecting elements Da and Db and the photodetecting elements Dc and Dd which form the respective light receiving portions 15 and 16 are angled with respect to the direction corresponding to the recording track T direction in the optical disc 1 indicated by the arrow X. It extends by θ.

On the photo-detecting elements Da and Db of the light-receiving section 15 and the photo-detecting element D of the light-receiving section 16 arranged in this way.
A beam spot Sa of the 0th-order light as shown by a chain line in FIG. 7 and both sides thereof are formed on c and Dd by the reflected laser light beam from the recording track T of the optical disc 1 which has passed through the objective lens 12. 2 of the primary light
The beam spots Sb and Sc are projected.

That is, as shown in FIG.
The beam spots Sa, Sb, Sc before being reflected by and incident on the objective lens 12 are in the state of FIG. A, the central beam spot Sa is the 0th order diffracted light, and the left and right beam spots Sb, Sc are 1 It is the next diffracted light. When these beam spots Sa, Sb, Sc pass through the objective lens 12, the pupils of the objective lens 12 cause the beam spots Sa, Sb, Sc to become as shown in FIG. It can be seen that the 0th order light and the 1st order overlap in the left and right 1st order diffracted light regions in the beam spot.

Then, the detection output signals Va and Vb corresponding to the beam spots Sa, Sb, and Sc are obtained from the photodetection elements Da and Db of the light receiving section 15, and the photodetection elements Dc and Dd of the light receiving section 16 are obtained. Output detection signals Vc and Vd corresponding to the beam spots Sa, Sb, and Sc, respectively, and these detection output signals are supplied to the servo signal through a flexible wiring connection board (not shown) as shown in FIG. Matrix amplifiers 21, 22 and 2
3 is derived.

A wobbling groove having a depth of λ / 8 of the wavelength λ of the laser light beam L incident thereon is formed on the recording track T of the optical disc 1 facing the optical head device 10 as described above. Therefore, the objective lens 1
The laser light beam L incident on the recording track T of the optical disc 1 through 2 is diffracted by the wobbling groove and reflected. Therefore, it returns from the recording track T through the objective lens 12, is guided to the light receiving portions 15 and 16, and
On the photodetectors Da and Db and on the photodetectors Dc and Dd
The reflected laser light beams that form the beam spots Sa, Sb, and Sc on the upper side correspond to the positional relationship between the wobbling groove that forms the recording track T and the beam spot of the laser light beam L that irradiates them.
Make a diffraction pattern on B, and such a diffraction pattern is
With respect to each of the photodetector elements Da and Db forming the light-receiving section 15 and the photodetector elements Dc and Dd forming the light-receiving section 16, a recording track is formed in a direction corresponding to the recording track direction shown by an arrow X in FIG. It moves at a speed according to the moving speed of the recording track T with respect to the laser light beam L for irradiating T.

The optical disc 1 is, for example, 400 to 900.
Accurately rotating at a predetermined number of rotations within the range of rpm,
When the laser light beam L accurately irradiates the wobbling groove on the optical disc 1, as shown in FIG. 7, the beam spots Sa, Sb, and Sc are detected by the photodetectors Da, Db, Dc, and Dd. It is projected with a diffraction pattern in which the above light quantity distribution is symmetrical. That is, the state shown in FIG. 7 shows the case where the tracking state is proper. However, when the laser light beam L with respect to the wobbling groove is deviated in the direction transverse to the recording track direction on the optical disc 1 for some reason, the photodetectors Da, Db, D of the beam spots Sa, Sb, Sc are generated.
The light quantity distributions on c and Dd are projected with an asymmetrical diffraction pattern.

Therefore, the detection output signals Va and Vb detected by the photodetectors Da and Db and the photodetector Dc are detected.
, Dd detected detection output signals Vc and Vd,
When the servo matrix amplifier 21 shown in FIG. 8 performs addition and subtraction under a predetermined arithmetic expression, a focus control signal Ef for controlling the position of the objective lens 12 in the optical axis direction is obtained, and the focus control of the objective lens 12 is performed. When the servo matrix amplifier 22 performs addition and subtraction according to a predetermined calculation formula, the tracking control signal Et for controlling the position of the objective lens 12 in the direction transverse to the moving direction of the recording track T is obtained. By this tracking control signal Et, tracking control can be performed so that the objective lens 12 is always accurately traced on the recording track T, and further the servo matrix amplifier 23 [Equation 1]
The track wobble signal Ew for accurately rotating the optical disc 1 at a predetermined rotation speed so that accurate information signals such as music information and address information can be obtained by addition and subtraction by
Can be obtained.

[0016]

[Equation 1]

[0017]

However, the above-mentioned [Equation 1]
Objective lens 1 by the track wobble signal Ew obtained by the formula
The rotation control of the second recording track T (wobbling groove) is performed by the number of times (ATER, track wobble) in which the address information cannot be read as the light beam L deviates from the recording track T, as indicated by a black square in FIG. Error rate) is high. That is,
There is a problem that reading errors of the wobbling signal increase.

This is because the 0th-order light region is also used for detecting the track wobble signal Ew, so that, for example, even when the light beam L is correctly tracking on the recording track T (wobbling groove). The beam spots Sa, Sb, Sc are displaced from a predetermined position due to, for example, a disturbance such as an electric offset on the tracking control signal Et, that is, the 0th order light of the beam spot is used for detecting the tracking control signal Et. It is presumed that this is due to the fact that the area is also used.

SUMMARY OF THE INVENTION The present invention is intended to solve such a problem, and an object thereof is to obtain an optical head device in an optical disk device in which a reading error of a wobbling signal is small and a method of detecting a track wobble signal using the same. It is what

[0020]

Therefore, in the optical head device of the present invention, the light beam generator and the light beam from the light beam generator are made incident on the optical disc having the wobbling groove and the optical disc Lens means for receiving the light beam and a light receiving portion for guiding the reflected light beam from the optical disk received by the lens means, the light receiving portion being in the moving direction of the diffraction pattern formed by the reflected light beam. For 0
At least four lights which are separated and juxtaposed by at least three parallel separating portions extending in a direction having a predetermined angle between 90 degrees, and which are made incident with the reflected light beams to obtain detection outputs from the respective lights. The photo-detecting elements, which are composed of detection elements and are located on the outermost side of the photo-detecting elements, are arranged at positions where the 0th-order light of the reflected light beam is not received.

Further, the method of detecting a track wobble signal in the optical disk device of the present invention uses a plurality of, for example, two photodetectors of the photodetector in the optical head device, and the photodetectors are the lens means. A detection output signal of each of the photodetecting elements which are arranged at a predetermined interval in the direction of the reflected light beam which has passed through and is located on the outermost side opposite to each other of the photodetecting elements of each set. And a sum of detection output signals of the outermost photodetecting elements existing on the opposite sides of the photodetecting elements of the respective groups, which are different from the opposite sides, to obtain a track wobble signal. The above problems are solved by adopting the above.

Therefore, if the optical head device and the wobble signal detecting method using the same in the optical disk device of the present invention are adopted, the allowable value of the track deviation of the light beam generated by the disturbance at the time of reproducing the track wobble signal is currently set. Since it spreads compared with the system, it is possible to reduce the reading error of the wobbling signal.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical head device in an optical disk device of the present invention and a track wobble signal detecting method using the same will be described below with reference to FIGS. FIG. 1 is a side view schematically showing an optical head device according to an embodiment of the present invention, and FIG. 2 is a plan view of a light receiving portion mounted on the optical head device shown in FIG. FIG. 4 is a signal processing block diagram of the present invention for processing various signals detected by the optical head device shown in FIG. 1, and FIG. 4 shows a track wobble signal detection method of the present invention and a conventional track wobble signal detection method. 7 is a graph showing the relationship of ATER with respect to tracking deviation.

As shown in FIG. 1, the optical head device 30 of the present invention generates a laser light beam and forms it on the optical disc 1 as described above, like the existing optical head device 10. It is possible to make the laser beam incident on the extremely narrow recording track T in an appropriate focused state so as to accurately follow the recording track T, and further to accurately guide the reflected laser light beam from the recording track T of the optical disc 1 to the photodetector 34. Needless to say, the objective lens 3 facing the semiconductor laser element 31 and the optical disk 1 is required.
2. Various optical elements such as other lenses, mirrors or prisms 33, and photodetectors 34 are precisely arranged, and the whole of them can be displaced in the direction along the optical axis of the objective lens 32 and the direction orthogonal thereto. Focus control for making the laser light beam incident on the recording track T formed on the optical disc 1 in a proper focusing state, and accurately supporting the laser light beam on the recording track T formed on the optical disc 1. It is equipped with a tracking control for following and a function for obtaining a track wobble signal for accurately controlling the rotation of the optical disc 1 to obtain an accurate information signal and address information.

The photodetector 34 comprises a light receiving portion 35 and a light receiving portion 36 provided on a semiconductor substrate 37,
In the present invention, as shown in FIG.
Reference numerals 5 and 36 each include four photodetector elements. That is, the light receiving section 35 is composed of four strip-shaped photodetector elements Da, Db, Dc and Dd which are separated by the separating section E and arranged in parallel in the same plane, and the light receiving section 36 is , In the same plane, separated by the separation unit E,
Four strip-shaped photodetectors De, Df, Dg arranged in parallel
And Dh.

The light receiving portions 35 and 36 are formed, and the semiconductor laser device 31 and the prism 33 are formed.
In the semiconductor substrate 37 provided with, the direction in which the respective separation portions E of the light receiving portions 35 and 36 extend on the reference surface of the case of the optical head device 30 generally corresponds to the recording track T direction of the optical disc 1 ( It is fixed at a predetermined angle θ between 0 and 90 degrees with respect to the direction indicated by the arrow X). In the case of the example shown in FIG. 2, θ = 0.
Therefore, the respective photodetector elements Da, Db, Dc and Dd, and the photodetector elements De, Df, Dg and Dh which form the respective light receiving portions 35 and 36 are in the recording track T direction in the optical disc 1 indicated by the arrow X. With respect to the direction corresponding to.

Then, each of the photodetector elements Da, Db, D
c and Dd, and the respective photodetectors De, Df, Dg and D
The width and arrangement of h are such that the beam spot Sa of the 0th-order light shown in FIG. 9 remains in the region of the photodetection elements Db, Dc and Df, Dg, that is, the photodetection elements Da, Dd and photodetection. The elements De and Dh are set so as not to be projected.

Therefore, when the light beam L is accurately tracking on the recording track T, the optical disk 1 which has passed through the objective lens 32 on the light receiving section 35 and the light receiving section 36 arranged as described above. When the reflected laser light beam from the recording track T is projected, the beam spot Sb of the primary light thereof extends over the area of the photodetector elements Da and Db of the light receiving unit 35, as shown by the alternate long and short dash line in FIG. Then, the beam spot Sc of the primary light straddles the regions of the photodetectors Dc and Dd of the light receiver 35, and the beam spot Sb of the other primary light is the photodetector of the light receiver 36. The beam spot Sc extends over the regions De and Df, and the beam spot Sc extends over the regions of the photodetectors Dg and Dh, and at the same time, the beam spot S of zero-order light is emitted.
The light a is retained and irradiated only in the regions of the photodetectors Db and Dc of the light receiving unit 35 and the regions of the photodetectors Df and Dg of the light receiving unit 36.

Then, the reflected laser light beams are arranged as described above to the respective photodetector elements Da, Db, Dc, Dd, D.
When irradiated with e, Df, Dg, and Dh, the detection output signals V corresponding to the beam spots Sa, Sb, and Sc are emitted from the photodetector elements Da, Db, Dc, and Dd of the light receiving unit 35, respectively.
a, Vb, Vc, and Vd are obtained, and the detection output signals Ve, Vf, Vg, and Vg corresponding to the beam spots Sa, Sb, and Sc are obtained from the photodetector elements De, Df, Dg, and Dh of the light receiving unit 36, respectively. Vh is obtained, and these detection output signals are led to the servo matrix amplifiers 41, 42 and 43 through a flexible wiring connection board (not shown) as shown in FIG.

These detection output signals Va, Vb, Vc, V
Detection output signal V among d, Ve, Vf, Vg and Vh
The track wobble signal Ewa is obtained by adding and subtracting only a, Vd and the detection output signals Ve, Vh by the equation of [Equation 2] in the servo matrix amplifier 43 shown in FIG. It is possible to obtain accurate information signals and address information.

Of course, the servo matrix amplifier 41
The focus control signal Efa can be obtained by adding / subtracting under a predetermined arithmetic expression with, and the tracking control signal Eta can be obtained by adding / subtracting under a predetermined arithmetic expression by the servo matrix amplifier 42. it can.

[0032]

[Equation 2]

As described above, in the present embodiment, each light receiving portion 35
Of the photo-detecting elements Da, Db, Dc and Dd constituting the light-receiving part 36 and the photo-detecting elements De, Df, Dg and Dh constituting the light-receiving part 36, the photo-detecting elements D existing at the outermost sides.
Beam spot Sa of 0th-order light of a, Dd, De, and Dh
Not using the detection output signals Va, Vd, Ve and Vh, the sum (V of the detection output signals of the photodetecting elements existing on the outermost opposite sides of the photodetecting elements of each set of the light receiving unit).
a + Ve) and the sum (Vd + Vh) of the detection output signals of the outermost photodetecting elements existing on the opposite sides of the photodetecting elements of the respective groups, which are different from the opposite sides, and the track wobble signal is obtained. Ewa is detected.

The optical disc 1 is produced by the track wobble signal Ewa obtained by using the optical head device 30.
If the rotation control is performed, even if the light beam L deviates from the recording track T, as shown by the white square points in FIG.
A measurement result was obtained in which the number of occurrences (ATER, track wobble error rate) per unit time in a state where the information signal or the address information could not be accurately read was reduced. That is, the permissible value of the track deviation becomes wider, and the reading can be performed more accurately than the reading of the information signal and the address information in the existing optical disk device.

Although the reason why the occurrence of a track wobble signal reading error due to the track deviation is less than that in the existing technique has not been clarified yet, in the present invention, the reflected laser light beam reflected and returned from the optical disc 1 is returned. It is considered that the reason is that only the region of the first-order diffracted light is detected and used. In other words, in the current technology, the beam spot of the 0th-order light that is easily affected by the disturbance is used for detecting the track wobble signal, so that the 0th-order light has a large adverse effect when the track shift occurs. FIG. 4 shows that the influence of the 0th-order light is reduced because only the beam spot of the 1st-order light that is not easily affected by the disturbance is used to detect the track wobble signal of the invention. Inferred from experimental results. And it has not been clarified at present how the 0th-order light has an adverse effect.

[0036]

As described above, when the track wobble signal detecting method in the optical disk device of the present invention is adopted, the allowable value of the track deviation of the light beam with respect to the recording track of the optical disk at the time of reproducing the track wobble signal is the same as that of the current technology. Compared to the system, the reading error of the wobbling signal due to the track shift is reduced, and the optical head device can be made to follow the recording track almost always, and more accurate reproduction information signal and address information can be obtained. it can.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing an optical head device according to an embodiment of the present invention.

FIG. 2 is a plan view of a light receiving portion mounted on the optical head device shown in FIG.

3 is a signal processing block diagram of the present invention for processing various signals detected by the optical head device shown in FIG.

FIG. 4 is a graph showing a relationship of ATER with respect to tracking deviation by the track wobble signal detection method of the present invention and the track wobble signal detection method of the prior art.

FIG. 5 is a partial cross-sectional perspective view of a mini disk which is a currently used magneto-optical disk.

FIG. 6 is a side view schematically showing an optical head device used in a currently used mini disk device.

FIG. 7 is a plan view of a light receiving portion mounted on the optical head device shown in FIG.

8 is a signal processing block diagram of various signals detected by the optical head device shown in FIGS. 6 and 7. FIG.

9A and 9B show a spot state of a reflected light beam from an optical disk, FIG. 9A shows the state before passing through the objective lens, and FIG. 9B shows the state after passing through the objective lens. It is a top view.

[Explanation of symbols]

 T recording track (wobbling groove) Da photodetector Db photodetector Dc photodetector Dd photodetector De photodetector Df photodetector Dg photodetector Dh photodetector Efa focus control signal Eta tracking control signal Ewa track wobble Signal Sa Reflected laser light beam of 0th order light Sb Reflected laser light beam of 1st order light Sc Reflected laser light beam of 1st order light Va Detection output signal Vb Detection output signal Vc Detection output signal Vd Detection output signal Ve Detection output signal Vf Detection Output signal Vg Detection output signal Vh Detection output signal 1 Minidisk 30 Optical head device 31 of the present invention 31 Semiconductor laser element 32 Objective lens 33 Prism 34 Photodetector 35 Light receiving part 36 Light receiving part 37 Semiconductor substrate 41 Servo matrix amplifier 42 Servo・ Ma Tricks Amp 43 Servo Matrix Amp

Claims (3)

[Claims] 1. A light beam generator, a lens means for causing the light beam from the light beam generator to enter an optical disc having a wobbling groove, and a lens means for receiving the light beam from the optical disc, and a lens means for receiving the light beam. A light receiving unit for guiding the reflected light beam from the optical disc, the light receiving unit having a predetermined angle between 0 and 90 degrees with respect to the moving direction of the diffraction pattern formed by the reflected light beam. And at least four photodetection elements which are separated by juxtaposed parallel lines extending in the direction having the direction of separation and which are provided with the reflected light beam to obtain a detection output from each of the light detection elements. The optical detection element existing on the outermost side of the element is arranged at a position where the 0th order light of the reflected light beam is not received. Apparatus. 2. A plurality of the light receiving portions are arranged at a predetermined interval in a direction in which the reflected light beam passes through the lens means and is incident.
The optical head device described in 1. 3. A light beam generator, a lens means for causing the light beam from the light beam generator to be incident on an optical disk having a wobbling groove, and a lens means for receiving the light beam from the optical disk, and a lens means for receiving the light beam. A pair of light receiving portions for guiding the reflected light beam from the optical disc, the pair of light receiving portions having a predetermined interval in the direction in which the reflected light beam enters through the lens means. Are arranged, and each of the light receiving portions is set to 0 with respect to the moving direction of the diffraction pattern formed by the reflected light beam.
At least 4 parallel beams separated by at least three parallel separating portions extending in a direction having a predetermined angle of about 90 degrees and having the reflected light beams incident thereon to obtain detection outputs from each of them. The photodetecting element, which is composed of a photodetecting element and exists on the outermost side of the photodetecting element, uses an optical head device arranged at a position where the 0th order light of the reflected light beam is not received. The sum of the detection output signals of the respective outermost photodetecting elements on the opposite sides of the detecting elements and the different light on the other outer sides of the other opposite sides of the photodetecting elements of each set. A method for detecting a track wobble signal in an optical disk device, wherein a track wobble signal is obtained by calculating a difference from a sum of detection output signals of a detection element.