JPH09147408A - Light head - Google Patents

Abstract

(57) Abstract: An optical head capable of high density reproduction even with a long wavelength laser is provided. SOLUTION: Three light beams are emitted from an emitting means composed of a laser 10 and a polarization hologram 11. The track T1 on the magneto-optical disk 1 is irradiated with P-polarized S _P , and the adjacent tracks T2 and T3 are irradiated with S-polarized S _S1 and S _S2 . The analyzer 14 has an azimuth angle set to 45 degrees with respect to the y-axis, and is divided into mutually orthogonal components U and V.
Incident on. The output of the photodetector 15 is received by the differential amplifier 16. As a result, the information of adjacent tracks is differentially subtracted from the main reflected light, so that crosstalk can be removed and a low-cost semiconductor laser can be used without increasing the NA.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for carrying out optical information recording and reproducing using an external storage device of an electronic computer and an optical disk used for recording and reproducing device of music and video signals and other information. The present invention relates to an optical head used in the above device.

[0002]

2. Description of the Related Art Conventionally, as an optical head, a read-only type optical head used for a compact disk or the like and a recording / reproducing type head used for a magneto-optical disk or the like have been generally used.

In recent years, optical discs are required to have a larger capacity and a smaller size in response to a demand for long-time moving image reproduction intended to replace a video tape and an increase in the scale of computer data. As a result, high density recording is an important technology. It has been closed up.

As means for high-density recording and reproduction, firstly, a method of narrowing the width of the recording track to increase the track density, and secondly, a method of increasing the modulation speed to increase the recording mark density to increase the linear density. Third, there is a method of performing multi-layer recording.

Considering an optical disk as the first method, that is, increasing the track density, the width of the recording track, to be precise, the diameter of the laser beam is λ at the laser wavelength,
When NA is the numerical aperture for irradiating laser light, it is almost determined by λ / NA. For example, the diameter of the Airy disk is 1.
22 × λ / NA. Therefore, in order to increase the track density, it is conceivable to shorten the wavelength or increase the NA. However, it is not good systematically to increase the NA unnecessarily. This is because the allowable amount of defocus decreases with the square of NA, and the disc tilt is 3
This is because the permissible amount decreases with the fourth power with respect to the square and the disc substrate thickness unevenness.

Therefore, in order to realize a high track density, shortening the wavelength of the laser light is the most desirable and appropriate means.
For example, in a read-only medium that takes the same steps as a compact disc or the like, a narrow track disc itself can be relatively easily manufactured if an original plate is made with a short wavelength using an ultraviolet laser or an argon laser.

Further, the second method, a disk having an increased linear density, can be easily manufactured by the above method.

[0008]

However, it is difficult to manufacture a semiconductor laser having a short wavelength, which should be used in the apparatus for reproducing information on the high-density recording disk, and it cannot be realized immediately. If a high-density disc is reproduced normally by using a generally available infrared to red long-wavelength semiconductor laser, the light spot formed is larger than the recording mark, and the light spot from the surrounding recording marks becomes larger. Crosstalk cannot be ignored.

FIG. 11 shows a state in which a high density disc is reproduced by a conventional semiconductor laser. S is a light spot by a laser beam, and P51 to P56 are recording marks recorded on the optical disk in a convex shape with respect to the surroundings. now,
The light spot S mainly irradiates the recording mark P51 to reproduce information, but the size of the light spot S depends on the recording mark P51.
Greater than 51. As shown in the figure, in this state, the light spot S also irradiates a part of the recording marks P52 to P56, and the reflected light includes crosstalk noise due to the influence of these surrounding recording marks P52 to P56.

Therefore, according to the conventional method, it is very difficult to reproduce the high density recording information by using the existing semiconductor laser,
Reliability decreases.

The present invention has been made to solve the above problems, and an object of the present invention is to reduce the cost for reproducing high-density recorded information by using a conventional long-wavelength semiconductor laser. And to provide a highly reliable optical head.

[0012]

In order to solve the above problems, an optical head of the present invention is an optical head for reproducing at least information while scanning a recording medium, and irradiates a recording spot on the recording medium with a main light spot. Then, the main reflected light is obtained, and a sub-light spot is irradiated to the adjacent area adjacent to the recording mark to obtain the sub-reflected light that can be electromagnetically separated from the main reflected light. It is configured by performing calculations.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is an optical head for reproducing at least information while scanning a recording medium, irradiating a main light spot on a recording mark of the recording medium to obtain main reflected light,
By irradiating a sub-light spot to a region near the recording mark to obtain sub-reflected light that is electromagnetically separable from the main reflected light, the main reflected light or an electric signal corresponding to the main reflected light is obtained. By using an optical head that reduces the component of the neighboring region by utilizing the sub-reflected light, the crosstalk component of the neighboring region in the main reflected light can be reduced by utilizing the sub-reflected light.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) An optical head according to Embodiment 1 of the present invention will be described with reference to FIGS. The right-handed rectangular coordinate system is defined as shown in each figure.

FIG. 1A shows the structure of the optical head according to this embodiment. In FIG. 1A, 1 is a magneto-optical disk. The magneto-optical disk 1 has a substantially spiral recording track centering on a rotation center (not shown), and the recording track may be substantially parallel to the y-axis direction in the region discussed in the present embodiment. . The magneto-optical disk 1 is rotated about the z axis by a spindle motor (not shown) fixed at the center of rotation.

Reference numeral 10 is a semiconductor laser which generates linearly polarized light. The optical axis of the semiconductor laser 10 is parallel to the z axis, and z
The laser light L is emitted in the positive direction of the axis. The plane of polarization is rotated by 45 degrees with respect to the x axis, and both the x axis and the y axis have a polarization component.

Reference numeral 11 denotes a hologram type polarization separation element, which will be referred to as a polarization hologram hereinafter. Polarization hologram 11
Is made of, for example, a LiNbO ₃ crystal as a basic material and utilizes the anisotropy of refractive index to diffract into polarized light components which are orthogonal to each other depending on the polarization direction of incident light.

The hologram groove is provided in parallel with the y-axis direction, that is, in the direction parallel to the recording track of the magneto-optical disk 1, and most of the polarization components in the y-direction of the laser light L incident from the lower end of the z-axis. Is linearly transmitted, and the polarized component in the x direction is diffracted and transmitted as ± 1st order diffracted light in a direction symmetrical to the z axis and parallel to the xz plane. It should be noted that although odd-order components such as third-order and fifth-order are generated, they are designed to be sufficiently negligible for the first-order light.

That is, the polarization hologram 11 forms a main light beam, which is a 0th-order light having a plane of polarization in the y-direction parallel to the z-axis, with respect to the incident light, and a predetermined angle in the xz-plane with respect to the z-axis. A total of three light beams are generated, which are ± first-order light beams having polarization planes in the x direction. The semiconductor laser 10 and the polarization hologram 11 constitute a radiation means.

Reference numeral 12 is a beam splitter as a light beam splitting means, which splits the light beam by transmission and reflection. 1
Reference numeral 3 denotes an objective lens, which has a function of converging incident light as a light spot on the magneto-optical disk 1, and is connected to a mechanism (not shown) that follows surface wobbling of the magneto-optical disk 1 and eccentricity of a recording track. ing. Reference numeral 14 denotes an analyzer as a light detecting means, which divides incident light into two components, U and V, which are orthogonal to each other, refracts each component at a predetermined angle and transmits the components. The azimuth angle of the analyzer 14 is inclined 45 degrees in the y-axis direction. Reference numeral 15 denotes a photodetector as a photodetector, which is a region 15
It is divided into a and 15b, and the amount of light received in each area is converted into an electric current. Reference numeral 16 is a differential amplifier as a differential detection means, which amplifies an input potential difference and outputs it.

The arrangement of each constituent element is as follows:
1, the beam splitter 12, and the objective lens 13 are arranged with their optical axes parallel to each other in the z-axis direction, the reflected light from the magneto-optical disk 1 returns to the beam splitter 12, and the light reflected in the x-axis direction is passed to the analyzer 14. U of incident light, which is transmitted through the analyzer 14,
The V components are arranged so as to enter the light receiving regions 15a and 15b of the photodetector 15, respectively. In addition, the differential amplifier 16
Is connected to the outputs of the light receiving regions 15a and 15b.

The polarization hologram 11 has an x direction of incident light and ay direction.
When the polarization component in the azimuth direction is 1: 1, the transmittance of the 0th-order rectilinear light which is a component parallel to the y-axis is 0.8, and the transmittance of ± 1st-order diffracted light which is a component parallel to the x-axis is 0. It is 08. The beam splitter 12 has a light transmittance of 0.7 and a reflectance of 0.3, and the magneto-optical disk 1 has a reflectance of about 0.2.

The operation of the optical head having the above structure will be described below. For the sake of convenience, the polarization components parallel to the x and y axes with reference to the reflection surface of the beam splitter 12 are referred to as S polarization and P polarization, respectively.

Since the plane of polarization of the light emitted from the semiconductor laser 10 is tilted about the x-axis by 45 degrees about the z-axis, the polarization hologram 11 has a P-polarized component: S-polarized component = 1: 1 light beam. Incident.

The light quantity ratio of the main beam, which is the 0th-order transmitted light of the P-polarized component, which is the output of the polarization hologram 11, and the sub-beam, which is the ± first-order diffracted light of the S-polarized component, is 1 as described in the configuration.
0: 1. Therefore, when the main beam is referred to as L _P and the sub-beams are referred to as L _S1 and L _S2 , respectively, the light amount ratios are L _P : L _S1 : L _S2 =
It becomes 10: 1: 1.

L _P , L _S1 , and L _S2 are beam splitters 12, respectively.
Is partially transmitted and enters the objective lens 13. FIG. 1 (b)
FIG. 3 is a diagram showing a relationship between a recording track on the magneto-optical disk 1 and a light spot. In the figure, A is the traveling direction of the magneto-optical disk 1. As shown in FIG. 1B, these are the main light spots on the recording tracks of the magneto-optical disk 1 and are the first light spots.
S _P, S _S1 a second light spot sub optical spots, to form the S _S2 is a third light spot in the sub optical spot is a light spot. S _P , S _S1 and S _S2 are respectively formed on the first, second and third recording tracks T1, T2 and T3 which are adjacent to each other, and the light quantity ratio thereof is substantially equal to the ratio of L _P , L _S1 and L _S2 , It is 10: 1: 1.

Now, let us consider a case where the recording mark B11 on the first recording track T1 is reproduced by the first light spot S _P which is the main light spot. Since the first light spot S _P scans not only the recording mark B11 but also the recording marks B21 and B22 of the second recording track T2 and the recording mark B31 of the third recording track T3 which are adjacent to each other, the reflection For light, B21, B22, B3 of these adjacent tracks
It also includes the information of 1.

In magneto-optical recording, the Kerr effect causes the polarization plane of reflected light to the polarization plane of incident light to be modulated by magnetization. Therefore, the main reflected light which is the reflected light of the first light spot S _P is also modulated by the surrounding recording marks.

The main reflected light that is the reflected light of the first light spot S _P due to the recording mark B11 is referred to as R _M , and the other components in the main reflected light due to the adjacent tracks are referred to as R _C as the crosstalk component. . The light intensity ratio of R _M and R _C dynamically changes depending on the recording mark, but it is assumed that R _M :
R _C = 8: 2.

The second and third light spots which are the sub-light spots.
To S_S1, S_S2Think about S _S1Is the second recording tiger
Mainly irradiate the recording marks B21 and B22 on the monitor T2
Then S_S2Is a recording mark B3 on the third recording track T3
1 is mainly irradiated. Therefore, S_S1, S_S2by
R is the sub-reflected light that is the reflected light_S1, R_S2Then, R_S1, R
_S2Is mainly information of B21, B22, B31, that is,
It has information on the crosstalk component of.

[0031] When substantially constant regardless of the reflectance of the magneto-optical disc 1 in the polarization _{direction, (L P: R M +} R C) = (L S1: R
_{Since S1} ) = (L _S2 : R _S2 ), L _P : L _S1 : L _S2 =
Considering 10: 1: 1, (10: 8 + 2) = (1: R
_S1 ) = (1: R _S2 ) = (1: 1). Therefore,
R _M : R _C : R _S1 : R _S2 = 8: 2: 1: 1. When the sum R _S1 + R _S2 of the secondary reflected light is R _S , R _M : R _C : R _S = 4:
When the ratio is 1: 1, the crosstalk component R _C of the main reflected light and the amount of the sub-reflected light R _S are almost the same.

The main reflected light and the sub reflected light are the objective lens 1
After passing through 3 again, a part of the beam is reflected by the beam splitter 12 and is incident on the analyzer 14. The reflected light incident on the analyzer 14 is redefined as R _M , R _C , and R _S , which are the same as above,
The ratio of the amount of light is constant.

Now, it is assumed that the recording mark B11 is in a magnetized state showing information 0. Consider the component R _M0 by the recording mark B11 indicating the information 0 of the main reflected light. The main beam incident light L _P had only P-polarized components, but the polarization plane of R _M0 was rotated by a predetermined angle θ with respect to the P-axis due to the Kerr effect.

This state is shown in FIG. In FIG. 2, the vertical axis is the P polarization axis and the horizontal axis is the S polarization axis. The size of the arrow schematically indicates the amplitude of light. It is assumed that the axes orthogonal to each other of the analyzer 14 are U and V axes, and that the U axis is tilted 45 degrees counterclockwise with respect to the P axis in FIG. The car rotation based on the information 0 is assumed to be θ in the clockwise direction. The _amounts of light output from the analyzer 14 to the light receiving regions 15a and 15b by R _M0 are components for the U and V axes, and are R _M0U and R _M0V , respectively, as shown in the figure.

Next, in FIG. 3A, the crosstalk component R _C
think about. Now, the second and third tracks T2 and T3
When the recording marks B21, B22, B31 of No. 1 are all information 0, the crosstalk component R _C0 due to the information 0 is also the component of which the polarization plane is rotated by θ in the direction of the information 0, that is, clockwise in FIG. 3A. Becomes The main beam incident light L _P is P
Since it is only the polarization component, the polarization plane of R _C0 is rotated clockwise from the P axis by θ. The _{amounts of} light output from the analyzer 14 to the light receiving regions 15a and 15b by R _C0 are R _C0U and R _C0V , respectively, as shown in the figure.

Further, in FIG. 3B, the sub-reflected light R_Sabout
Think. B21, B22, and B31 are all information 0
Therefore, sub-reflected light R due to information 0_S0Is still the direction of information 0,
That is, in FIG. 3B, the polarization plane is rotated clockwise by θ.
It will be a minute. Secondary beam incident light L _S1, L_S2Is only S-polarized component
Because it was R_S0Is the plane of polarization clockwise from the S-axis by θ
Is spinning. R_S0Causes the analyzer 14 to receive the light receiving area 15
The amount of light output to a and 15b is R as shown in the figure.
_S0U, R_S0VIt is.

Therefore, the amount of light received by the light receiving region 15a is R
_M0U + R _C0U + R _S0U , and similarly, the amount of light received by the light receiving region 15b is R _M0V + R _C0V + R _S0V . Differential amplifier 1
The output of 6 is G × (R _M0U +
R _C0U + R _S0U −R _M0V −R _C0V −R _S0V ).

However, since the crosstalk component R _C and the sub-reflected light R _S have almost the same amplitude as described above, |
Since R _C0 | = | R _S0 | and they are orthogonal to each other, R _C0U = R _S0V , R _C0V = R _S0U , and the output of the differential amplifier 16 is G × (R _{M0 U} − R _M0V ).

That is, the influence R _C0 due to the case where the crosstalk component is information 0 does not appear in the output of the differential amplifier 16, and
Only the signal component of the track. This result is similarly established when the crosstalk component is the information 1 and also when the information 0 and the information 1 are mixed in the crosstalk component.

As described above, according to the present embodiment, as the main light spot P on the first track of the magneto-optical disk.
Polarized light is made incident, and S-polarized light which is orthogonal to the main light spot as a sub light spot is made incident on the adjacent second and third tracks,
The crosstalk component from the second and third tracks of the reflected light of the main light spot and the reflected light amount of the sub light spot are made substantially equal,
By making the azimuth angle of the analyzer 45 degrees to obtain the differential between them, the crosstalk component between recording tracks can be removed.

In this configuration, the light quantity ratio of the main reflected light signal component, the crosstalk component, and the sub reflected light is 4: 1: 1.
However, the ratio is not particularly limited, and there is no problem as long as the crosstalk component and the sub-reflected light have substantially the same light amount. For example, the magnitudes of the components of S-polarized light and P-polarized light can be finely adjusted by the rotation angle of the semiconductor laser 10, and the effect of crosstalk removal can be optimally adjusted.

Although the planes of polarization of the main light spot and the sub light spot are orthogonal to the P polarized light and the S polarized light, it is not necessary to use the P polarized light as the main light spot, and it is not particularly important to make them orthogonal. The configuration is possible by changing the analyzer for other polarizations and mutual angles for the purpose of independently detecting the polarization planes.

Further, the main reflected light and the sub-reflected light may be electromagnetically separated irrespective of the polarization plane, and can be constructed in principle by changing the modulation frequency, for example.

Further, although the semiconductor laser 10 and the polarization hologram 11 are used as the radiating means for generating the three light beams, this may be realized by using another configuration, for example, a multiple emission source laser.

(Second Embodiment) An optical head according to a second embodiment of the present invention will be described below with reference to FIG. 4A is a view of the optical head according to the present embodiment as viewed from the positive direction of the y-axis, and FIG. 4B is a view of the same as viewed from the negative direction of the x-axis. The right-handed rectangular coordinate system is defined as shown in each figure.

In FIGS. 4A and 4B, the magneto-optical disk 1 and the semiconductor laser 10 as each component, the beam splitter 12, the objective lens 13, the analyzer 14, the photodetector 15, the differential amplifier 16 are shown. Is the same as that of the first embodiment including the arrangement.

The polarization hologram 11 is the same component as in the first embodiment, but the arrangement is different. That is, they are arranged in the direction rotated by 90 degrees around the z axis with respect to the first embodiment. That is, the groove of the hologram is arranged in a direction substantially perpendicular to the recording track of the magneto-optical disk 1.

The operation of the optical head configured as described above will be described below with reference to the drawings.

In the present embodiment, since the groove of the polarization hologram 11 is arranged in the direction substantially orthogonal to the recording track, the main light spot and the sub light spot are arranged on the same track. FIG. 4C is a diagram showing the relationship between the recording track and the light spot on the magneto-optical disk 1. In the figure, A is the traveling direction of the magneto-optical disk 1. No. 1 which is the main light spot
Centered on the optical spot S _S , the second optical spot S _{P1 which} is a sub optical spot precedes S _{S in the} traveling direction A, and the third optical spot S _P2 which is a sub optical spot is more than S _S. It is placed behind.

Taking the reflecting surface of the beam splitter 12 as a reference, the plane of polarization is rotated by 90 degrees from that of the first embodiment, the main light spot S _S becomes S-polarized light, and the sub-light spots S _P1 and S _{P2 become} P-polarized light. And are orthogonal to each other.

Now, consider the case where the recording mark B42 is reproduced by the first light spot S _S which is the main light spot. First
The main reflected light from the light spot S _S of
Not only the information of the preceding recording mark B43 and the information of the succeeding recording mark B41 is also included. That is, the crosstalk components from the recording marks before and after are included.

However, the second and third light spots S _P1 and S _P2 , which are sub-light spots, are mainly recorded marks 43 respectively.
And the information of the recording mark 41 is detected. The light amounts of these sub-light spots are substantially the same as the crosstalk component because they have the same configuration as in the first embodiment. Therefore,
Although detailed operation is omitted, the crosstalk component in the track can be removed by the same operation as in the first embodiment.

As described above, according to the present embodiment, the S-polarized light as the main light spot and the P-polarized light perpendicular to the main light spot as the sub-light spot are made incident on the magneto-optical disk, and the P-polarized light is recorded in the same track. Sub-light spots are arranged before and after the main light spot, the crosstalk component of the reflected light and the reflected light amount of the sub-light spot are made substantially equal, and the azimuth angle of the analyzer is rotated by 45 degrees to obtain the differential between them. As a result, the crosstalk component before and after the recording mark on the same track can be removed. The present embodiment is particularly effective for reproducing a high linear density magneto-optical disk.

(Third Embodiment) An optical head according to a third embodiment of the present invention will be described below with reference to FIG. FIG. 5A is a diagram viewed from the positive direction of the y-axis of the optical head according to the present embodiment, and FIG. 5B is a diagram similarly viewed from the negative direction of the x-axis. The right-handed rectangular coordinate system is defined as shown in each figure.

In FIGS. 5A and 5B, the magneto-optical disk 1 and the semiconductor laser 10 as each component, the beam splitter 12, the objective lens 13, the analyzer 14, the photodetector 15, the differential amplifier 16 are shown. Is the same as that of the first embodiment including the arrangement.

Reference numeral 17 is a polarization hologram on which lattice-shaped projections parallel to the xy directions are formed. Polarization hologram 17
In the light incident from the lower end of the z-axis, most of the polarization component in the y-direction is transmitted straight, and the polarization component in the x-direction is defined as ± first-order diffracted light in a direction parallel to the xz-plane and the yz-plane symmetrically to the z-axis. It is formed so as to diffract and transmit.

The polarization hologram 17 has the x-direction and y-direction of the incident light.
When the direction polarization component is 1: 1, the transmittance of the 0th-order straight light, which is a component parallel to the y-axis, is 0.8, and the transmittance of the ± 1st-order diffracted light, which is a component parallel to the x-axis, is each light beam. Are set to 0.08 each.

That is, the polarization hologram 17 has a main light beam as a first outgoing light which is a 0th order light having a polarization plane in the y direction parallel to the z axis with respect to the incident light, and xz with respect to the z axis.
Two secondary light beams as second and third outgoing lights that are ± first-order lights having a predetermined angle in the plane and a polarization plane in the x direction, and a predetermined angle in the yz plane with respect to the z axis. And a sub-beam 2 as the 4th and 5th outgoing lights which are ± first-order lights having a polarization plane in the x direction and a total of 5 light beams are generated.

The ratio of the amount of emitted light depends on the above-mentioned transmittance.
The main light beam as the outgoing light of 1 is L _P, 2nd to 5th output
L is the secondary light beam as the incident light_S1, L_S2, L_S3, L_S4Toss
Then L_P: L_S1: L_S2: L_S3: L_S4= 10: 1: 1:
It becomes 1: 1. Semiconductor laser 10 and polarization hologram 17
The radiation means is constituted by.

The operation of the optical head having the above structure will be described below. For the sake of convenience, the polarization components parallel to the x and y axes with reference to the reflection surface of the beam splitter 12 are referred to as S polarization and P polarization, respectively. Therefore, the main light beam from the polarization hologram 17 is P-polarized and the sub-light beam is S-polarized.

FIG. 5C shows the light spot on the magneto-optical disk 1 formed according to this embodiment. In the figure, A is the traveling direction of the magneto-optical disk 1. A P-polarized main light spot S _P as a first light spot by the main light beam is formed on the first recording track T1, and the second to fifth light spots by the sub light beam are formed at four positions around the main light spot S _P. S-polarized sub-light spots S _S1 , S _S2 , S _S3 , and S _S4 are formed.

The sub-light spots S _S1 and S _S2 are respectively the second and third recording tracks T adjacent to the first recording track T1.
Sub-light spots S _S3 and S _S4 are formed on T2 and T3, respectively, in the vicinity of the front and rear of the main light spot S _P.

Now, let us consider a case where the recording mark B52 on the first recording track T1 is reproduced by the main light spot S _P.
The main light spot S _P includes not only the recording mark B52 but also the preceding recording mark B53, the succeeding recording mark B51, and the recording mark B6 of the adjacent second recording track T2.
1, B62 and the recording mark B of the third recording track T3
Since a part such as 71 is also scanned, the reflected light also includes the information of the surrounding recording marks.

However, the sub-light spot S_S1Is mainly recorded
The information of marks B61 and B62 is S _S2Is also B71
Again S_S3, S_S4Detects the information of B53 and B51 respectively
doing. Main light spot S_POf the main reflected light which is the reflected light of
R by the recording mark B52_MAnd next to everything else
Crosstalk component of main reflected light by contact recording mark
R as minutes_CCall. R_MAnd R_CThe light intensity ratio of
It changes more dynamically, but as a hypothesis R_M: R_C=
It is 6: 4.

The ratio of the amount of emitted light is determined by the above-mentioned polarization hologram 1.
7 When _{setting, L P: L S1 + L} S 2 + L S3 + L S4 = 1
Since it is 0: 4, assuming that the reflectance of the magneto-optical disk 1 is substantially constant regardless of the polarization direction, the sum of the reflected light amounts of S _{S1 to} S _S4 is R _S , and R _M + R _C : R _S = 10: It is 4. Therefore, R _M : R _C : R _S = 6: 4: 4.

That is, the light amounts of the crosstalk component R _C of the main reflected light and the sub reflected light R _S are almost the same. This results in the same result as in the first embodiment, and the detailed operation is omitted, but the crosstalk component R _C in the main reflected light can be removed by using R _S by the same operation as in the first embodiment.

As described above, according to the present embodiment, as the main light spot P on the first track of the magneto-optical disk.
Polarized light is made incident, and S-polarized light which is orthogonal to the main light spot as a sub light spot is made incident on the adjacent second and third tracks,
Further, by arranging a sub light spot before and after the main light spot in the first track, the crosstalk component of the surrounding recording mark contained in the reflected light of the main light spot and the reflected light amount of the sub light spot are made substantially equal, In addition to the effect of the first embodiment that the crosstalk component between the recording tracks can be removed by adopting the configuration in which the azimuth angle of the analyzer is rotated by 45 degrees and the differential between them is taken, in addition to the effect in the same track, Further, it is possible to combine the effect of the second embodiment that the crosstalk component before and after the recording mark can be removed. This embodiment is particularly effective for reproducing a magneto-optical disk having a high track density and a high linear density.

(Fourth Embodiment) An optical head according to a fourth embodiment of the present invention will be described below with reference to FIG. The right-handed rectangular coordinate system is defined as shown in each figure.

FIG. 6A shows an optical head according to this embodiment. The semiconductor laser 10, the polarization hologram 11, the beam splitter 12, and the objective lens 1, which are the respective components.
3, the photodetector 15 and the differential amplifier 16 are the same as those in the first embodiment including the arrangement.

Similar to the first embodiment, the beam splitter 1
Polarization components parallel to the x and y axes with reference to the second reflection surface are referred to as S-polarized light and P-polarized light, respectively.

Reference numeral 18 is an analyzer, which has the same structure as the analyzer 14 of the first embodiment, but is different in arrangement. That is, the incident light is divided into two components, U and V, which are orthogonal to each other, and each component is refracted at a predetermined angle to be transmitted, but the azimuth angle of the analyzer is arranged parallel to the x and y axis directions. In this case, the U axis is the P polarization direction and the V axis is the S polarization direction.

Reference numeral 2 denotes an optical disc which uses a change in the amount of reflected light as an information code, for example, a compact recording medium having a high density recording. Here, it is simply described as a reflection information disc. The reflection information disk 2 has a recording track in a substantially spiral shape around a rotation center (not shown) like the magneto-optical disk 1 of the first embodiment, and the recording track is in the area discussed in the present embodiment. May be substantially parallel to the y-axis direction. The reflection information disk 2 is rotated about the z-axis by a spindle motor (not shown) fixed at the center of rotation.

The operation of the optical head configured as described above will be described below with reference to the drawings.

FIG. 6B is a diagram showing the relationship between the recording tracks on the reflection information disc 2 and the light spots. FIG.
As shown in (b), the P-polarized main light spot is the first light spot S _P and the S-polarized sub-light spot is the second light spot S on the recording track of the reflection information disc 2. _S1 and the third light spot S _S2 are formed. S _P , S _S1 , and S _S2 are respectively adjacent to the first, second, and third
Are formed on the recording tracks T1, T2, and T3, and the light quantity ratio thereof is substantially equal to the ratio of L _P , L _S1 , and L _S2 as in the first embodiment, and is 10: 1: 1.

Now, consider a case where the recording mark P11 on the first recording track T1 is reproduced by the first light spot S _P which is the main light spot. Since the first light spot S _P scans not only the recording mark P11 but also the recording marks P21, P22 of the second recording track T2 and the recording mark P31 of the third recording track T3 which are adjacent to each other, the reflection For light, P21, P22, P3 of these adjacent tracks
It also includes the information of 1. They appear as noise due to changes in the amount of reflected light.

The main reflected light that is the reflected light of the first light spot S _P due to the recording mark P11 is referred to as R _M , and the other components in the main reflected light due to the adjacent tracks are referred to as R _C as the crosstalk component. . The light intensity ratio of R _M and R _C dynamically changes depending on the recording mark, but it is assumed that R _M :
R _C = 8: 2.

The second and third light spots which are the sub-light spots.
To S_S1, S_S2Think about S _S1Is the second recording tiger
Mainly irradiate the recording marks P21 and P22 on the monitor T2
Then S_S2Is the recording mark P3 on the third recording track T3
1 is mainly irradiated. Therefore, S_S1, S_S2by
R is the sub-reflected light that is the reflected light_S1, R_S2Then, R_S1, R
_S2Is mainly information of P21, P22, P31, that is, the above
It has information on the crosstalk component of.

[0078] When substantially constant regardless of the reflectivity of the reflective information disc 2 to the polarization _{direction, (L P: R M +} R C) = (L S1:
Since R _S1 ) = (L _S2 : R _S2 ), L _P : L _S1 : L _S2
= 10: 1: 1, (10: 8 + 2) = (1:
R _S1 ) = (1: R _S2 ) = (1: 1). Therefore, R
_M : _RC : _RS1 : _RS2 = 8: 2: 1: 1. When the sum R _S1 + R _S2 of the secondary reflected light is R _S , R _M : R _C : R _S = 4:
When the ratio is 1: 1, the crosstalk component R _C of the main reflected light and the amount of the sub-reflected light R _S are almost the same.

The main reflected light and the sub reflected light are the objective lens 1
After passing through 3 again, a part of the beam is reflected by the beam splitter 12 and is incident on the analyzer 18. The reflected light incident on the analyzer 18 is redefined as R _M , R _C , and R _S , which are the same as above.
The ratio of the amount of light is constant.

Consider the polarization planes and amplitudes of the reflected lights R _M , R _C , and R _S. As in the first embodiment, L _P is P-polarized light and L _P is
_S1 and L _S2 are S-polarized. Since the reflection information disk 2 does not modulate the plane of polarization by reflection, R _M and R _C are P polarized light because of L _P , and R _S is _S polarized light because of L _S1 and L _S2 .

FIG. 7 shows the polarization planes and amplitudes of the reflected lights R _M , R _C , and R _S. In FIG. 7, the vertical axis is the P polarization axis and the horizontal axis is the S polarization axis. The size of the arrow schematically indicates the amplitude of light. The mutually orthogonal axes of the analyzer 18 are defined as U and V axes. As described in the configuration, the U axis and the V axis of the analyzer 18 coincide with the P polarization axis and the S polarization axis, respectively.

As shown in FIG. 7, R _M and R _C appear only on the U-axis and R _S appears only on the V-axis, and these light quantities are output to the light receiving regions 15 a and 15 b of the photodetector 15, respectively.

Therefore, the amount of light received by the light receiving region 15a is R
_M + R _C , and similarly the amount of light received by the light receiving region 15b is R
_S. The output of the differential amplifier 16 has its amplification coefficient G
As G × (R _M + R _C −R _S ).

However, since the crosstalk component R _C and the sub-reflected light R _S have almost the same amplitude as described above, R
_C = R _S , so that the output of the differential amplifier 16 is G × R _M
Becomes That is, the influence R _C due to the crosstalk component does not appear in the output of the differential amplifier 16, but only the signal component of the first track T1.

As described above, according to the present embodiment, the P-polarized light is incident as the main light spot on the first track of the optical disc having the change of the reflected light amount as the information code, and the adjacent second and third optical discs are incident. The S-polarized light orthogonal to the main light spot is made incident on the track as the sub light spot, and the crosstalk component and the reflected light amount of the sub light spot from the second and third tracks of the main light spot are made substantially equal to each other. The crosstalk component between the recording tracks can be removed by adopting a configuration in which the azimuth angle of is matched with the polarization plane of the main light spot and the difference is obtained.

(Fifth Embodiment) An optical head according to a fifth embodiment of the present invention will be described below with reference to FIG. The right-handed rectangular coordinate system is defined as shown in the figure.

In FIG. 8, a semiconductor laser 10, a polarization hologram 11, a beam splitter 12 as a light beam separating means,
The objective lens 13 is the same as that of the first embodiment including the arrangement. The analyzer 14 as the first light detecting means, the photodetector 15 as the first light detecting means, and the differential amplifier 16 as the first differential detecting means are the same as those in the first embodiment except for the arrangement. Is. Reference numeral 19 is an analyzer as a second analyzer.
Reference numeral 0 is a photodetector as the second photodetection means, and 21 is a differential amplifier as the second differential detection means, which are the same as the analyzer 14, the photodetector 15, and the differential amplifier 16, respectively.

Reference numeral 3 denotes an optical disc, which is a disc using a magneto-optical recording medium having a change in magnetization as an information code as a first type recording medium or a disc having a reflectance change as an information code as a second type recording medium. Indicates either. Here, the former is simply called a magneto-optical disk and the latter is called a reflective information disk.

Reference numeral 24 is a half mirror as a second light beam separating means for splitting the input light quantity in a transmitting / reflecting direction into approximately 1: 1. Reference numeral 22 denotes a type determination unit that determines the type of the optical disc 3. Although not shown here, the type determination unit 22 determines the type from the type information from the cartridge including the optical disc 3 or the information from the management information area of the optical disc 3 and the like. Is output.

Reference numeral 23 is a signal selecting section which selects the signals inputted to the signal inputs 23a and 23b according to the information of the control input 23c and outputs them to the output 23d. That is, when a signal corresponding to the magneto-optical disk is input to the control input 23c, the output 2
The signal input to the signal input 23a is output to 3d,
When a signal corresponding to the reflection information disc is input to the control input 23c, the signal input to the signal input 23b is output to the output 23d.

The light reflected from the beam splitter 12 is input to the half mirror 24, and the light transmitted through the half mirror 24 is input to the analyzer 14 as a first detection light beam. Similar to the first embodiment, the analyzer 14 is fixed so that the azimuth angle is inclined by 45 degrees with respect to the y-axis. The output light of the analyzer 14 is the photodetector 15 as in the first embodiment.
To the differential amplifier 16, and the output of each region of the photodetector 15 is input to the differential amplifier 16.
3 is input to the signal input 23a.

Analyzer 14, photodetector 15, differential amplifier 1
6 constitutes the first detection system 101. This is the same as the detection system for the magneto-optical disk used in the first embodiment.

The light reflected by the half mirror 24 is arranged so as to be input to the analyzer 19 as a second detection light beam.
As in the fourth embodiment, the azimuth angle of the analyzer 19 is fixed in parallel to the y direction. The output light of the analyzer 19 is input to the photodetector 20, the output of each region of the photodetector 20 is input to the differential amplifier 21, and the output of the differential amplifier 21 is input to the signal input 23b of the signal selection unit 23. To be done.

Analyzer 19, photodetector 20, differential amplifier 2
1 constitutes the second detection system 102. This is the same as the detection system for the reflection information disc used in the fourth embodiment.

The operation of the optical head configured as described above will be described below with reference to the drawings.

First, when the optical disc 3 is a magneto-optical disc, the light spots formed on the optical disc 3 are the same as those in FIG. 1B in the first embodiment, and their main reflected light and sub-reflected light are obtained. Passes through the half mirror 24 and
It is input to the detection system 101. Since the first detection system 101 is the same as the detection system for the magneto-optical disk in the first embodiment, the reproduction in which the crosstalk component is removed from the signal input 23a of the signal selection unit 23 according to the operation of the first embodiment. A signal is input.

On the other hand, a signal corresponding to the magneto-optical disk is input from the type determination unit 22 to the control input 23c of the signal selection unit 23 as a determination result, and the signal selection unit 23 outputs the signal input 2
The signal of 3a is output to the output 23d.

As a result, the reproduction signal of the magneto-optical disk from which the crosstalk component has been removed is obtained at the output 23d.

Next, when the optical disc 3 is a reflection information disc, the light spots formed on the optical disc 3 are the same as those in FIG. 6B in the fourth embodiment, and their main reflected light and sub-reflected light are reflected. The light is reflected by the half mirror 24,
It is input to the second detection system 102. Since the second detection system 102 is the same as the detection system for the reflection information disc in the fourth embodiment, the reproduction in which the crosstalk component is removed from the signal input 23b of the signal selection unit 23 according to the operation of the fourth embodiment. A signal is input.

On the other hand, a signal corresponding to the reflection information disc is input from the type determination unit 22 to the control input 23c of the signal selection unit 23 as a determination result, and the signal selection unit 23 outputs the signal of the signal input 23b to the output 23d. .

As a result, the reproduction signal of the reflection information disc from which the crosstalk component is removed is obtained at the output 23d.

Therefore, according to the present embodiment, it is possible to obtain a reproduction signal from which the crosstalk component is removed regardless of whether the optical disc 3 is a magneto-optical disc or a reflection information disc.

As described above, according to the present embodiment, the first detection system for detecting the reproduction signal of the magneto-optical disk and the second detection system for detecting the reproduction signal of the reflection information disk are provided, and the first detection system is provided. Each of the second detection systems is composed of an analyzer that removes crosstalk components, a photodetector, and a differential amplifier, and a half mirror that outputs the reflected light from the optical disk to each detection system is provided. Even if the optical disc is a magneto-optical disc, a reproduction signal from which the crosstalk component of the magneto-optical disc is removed is obtained from the system and a reproduction signal from which the crosstalk component of the reflection information disc is removed is obtained from the second detection system. It is possible to realize an optical head that has the effects of both the first and fourth embodiments that the reflective information disc can be reproduced in any case and the crosstalk component can be removed. Can.

In this embodiment, the number of sub-light spots is set to two, and crosstalk removal from adjacent tracks is intended. However, depending on the target optical disc,
The present embodiment can be applied to the configuration intended to remove front and rear crosstalk on the same track as described in the second embodiment. Furthermore, the present embodiment can be applied to the configuration in which a total of four sub-light spots are provided to the front and rear and adjacent tracks described in the third embodiment. In either case, the polarization hologram 11 is simply changed to the intended specifications.

(Sixth Embodiment) An optical head according to a sixth embodiment of the present invention will be described below with reference to FIG. The right-handed rectangular coordinate system is defined as shown in the figure.

In FIG. 9, a semiconductor laser 10, a polarization hologram 11, a beam splitter 12 as a light beam separating means,
The objective lens 13 is the same as that of the first embodiment including the arrangement. The type determination unit 22, the signal selection unit 23, the first detection system 101, and the second detection system 102 are the same as those in the fifth embodiment. Therefore, the analyzer 14, which is the component thereof, as the first light detecting means, the photodetector 15 as the first light detecting means,
The differential amplifier 16 as the first differential detection means, the analyzer 19 as the second light detection means, the photodetector 20 as the second light detection means, and the differential amplifier 21 as the second differential detection means are also implemented. The same as Form 5.

Reference numeral 3 denotes the optical disk described in the fifth embodiment, which is either a magneto-optical disk or a reflection information disk.

27 is a motor drive control unit, 26 is a motor,
25 is a mirror. The motor drive control unit 27 changes the rotation angle of the motor 26 according to the signal from the type determination unit 22. The mirror 25 is connected to the rotating shaft of a motor 26, and the angle around the y axis can be changed by the motor 26.

The motor drive control unit 27 includes a type determination unit 22.
When the signal corresponding to the magneto-optical disk is received from the motor 26, the motor 26 is driven and controlled so that the mirror 25 comes to the position of 25a. Drive is controlled so that is at the position of 25b. In FIG. 9, the mirror 25 is 2
The solid line indicates the position of 5a, and the broken line indicates the position of 25b.

The mirror 25 and the motor 26 constitute an optical path changing means, and when the mirror 25 reaches the position of 25a, the reflected light from the beam splitter 12 goes straight in the positive direction of the x-axis and becomes the first detected light flux. 1 Input to the detection system 101. Further, when the mirror 25 reaches the position of 25b, the reflected light from the beam splitter 12 is reflected by the mirror 25 in the negative direction of the z axis and is input to the second detection system 102 as the second detection light beam.

The operation of the optical head configured as described above will be described below with reference to the drawings.

First, when the optical disk 3 is a magneto-optical disk, the light spots formed on the optical disk 3 are the same as those in FIG. 1B in the first embodiment, and their main reflected light and sub-reflected light are obtained. Part of the beam splitter 12
Is reflected by

On the other hand, a signal corresponding to the magneto-optical disk is output from the type determination unit 22 as the determination result to the motor drive control unit 2
7 is output. The motor drive controller 27 rotates the motor 26 so that the mirror 25 is located at the position 25a. As a result, the reflected light from the beam splitter 12 goes straight in the positive direction of the x-axis and is input to the first detection system 101. Since the first detection system 101 is the same as the detection system for the magneto-optical disk in the first embodiment, according to the operation of the first embodiment, the reproduction in which the crosstalk component is removed from the signal input 23a of the signal selection unit 23 is performed. A signal is input.

Further, the signal from the type determining section 22 is input to the control input 23c of the signal selecting section 23, and the signal selecting section 23 receives the signal.
Outputs the signal of the signal input 23a to the output 23d. Therefore, the reproduction signal of the magneto-optical disk from which the crosstalk component is removed is obtained at the output 23d.

Next, when the optical disc 3 is a reflection information disc, the light spots formed on the optical disc 3 are the same as those in FIG. 6B in the fourth embodiment, and their main reflected light and sub-reflected light are reflected. Part of the light is a beam splitter 1
It is reflected at 2.

On the other hand, the type determination section 22 outputs a signal corresponding to the reflection information disk to the motor drive control section 27 as the determination result. The motor drive controller has two mirrors 25.
The motor 26 is rotated so as to come to the position of 5b. As a result, the reflected light from the beam splitter 12 is reflected in the negative direction of the z axis and is input to the second detection system 102. Since the second detection system 102 is the same as the detection system for the reflection information disc in the fourth embodiment, the reproduction in which the crosstalk component is removed from the signal input 23b of the signal selection unit 23 according to the operation of the fourth embodiment. A signal is input.

The signal from the type determining section 22 is input to the control input 23c of the signal selecting section 23, and the signal selecting section 23 receives the signal.
Outputs the signal of the signal input 23b to the output 23d. Therefore, at the output 23d, the reproduction signal of the reflection information disc from which the crosstalk component is removed can be obtained.

Therefore, according to the present embodiment, it is possible to obtain a reproduction signal from which the crosstalk component is removed regardless of whether the optical disc 3 is a magneto-optical disc or a reflection information disc.

This embodiment has the same effect as that of the fifth embodiment, but the half mirror 24 used in the fifth embodiment.
Since the mirror 25 is used instead of the first detection system 101,
Alternatively, the amount of light input to the second detection system 102 is almost 100.
%, Which has the effect of further improving the S / N ratio of the reproduced signal.

In the present embodiment, the mechanism using the motor as the means for rotating the mirror 25 has been taken as an example, but it is not necessary to be particular about this mechanism. Since the turning angle may be binary, for example, a simpler mechanism using a spring and an electromagnetic plunger can be considered.

As described above, according to this embodiment, the first detection system for detecting the reproduction signal of the magneto-optical disc and the second detection system for detecting the reproduction signal of the reflection information disc are provided, and the first detection system is provided. Each of the second detection systems is composed of an analyzer for removing crosstalk components, a photodetector and a differential amplifier, and a mirror and a mirror as an optical path changing means for selectively outputting the reflected light from the optical disk to each detection system. By providing the rotating mechanism, a reproduction signal from the magneto-optical disk of the magneto-optical disk can be obtained from the first detection system and a crosstalk component of the reflection information disk can be removed from the second detection system. In addition to the effect of the fifth embodiment that the reflective information disc can be reproduced in any case and the crosstalk component can be removed, the amount of reflected light used as a signal is further increased to reproduce the information. It can be issue of S / N for superior optical head of improving.

(Embodiment 7) An optical head according to Embodiment 7 of the present invention will be described below with reference to FIG. The right-handed rectangular coordinate system is defined as shown in the figure.

In FIG. 10, the semiconductor laser 10, the polarization hologram 11, the beam splitter 12, the objective lens 13, the photodetector 15, and the differential amplifier 16 are the same as those in the first embodiment including the arrangement. The type determination unit 22 is the same as that in the fifth embodiment.

The analyzer 14 as the light detecting means is the same as that of the first embodiment, except that it is supported rotatably around the x axis. A second gear 28 is provided around the analyzer 14.

Reference numeral 3 denotes the optical disk described in the fifth embodiment, which is either a magneto-optical disk or a reflection information disk.

31 is a motor drive controller, 30 is a motor,
Reference numeral 29 is a first gear connected to the shaft of the motor 30. The motor drive control unit 31 rotates the first gear 29 connected to the motor 30 in response to the signal from the type determination unit 22. The first gear 29 is engaged with the second gear 28. Therefore, the motor drive control unit 31 drives the motor 30 according to the signal from the type determination unit 22 to change the rotation angle of the analyzer 14 around the x-axis via the first gear 29 and the second gear 28.

The motor drive control section 31 includes a type determination section 22.
When a signal corresponding to the magneto-optical disk is received from the motor 30, the motor 30 is driven and controlled so that the azimuth angle of the analyzer 14 becomes 45 degrees which is the first rotation state with respect to the y axis, and the type determination unit 2
When the signal corresponding to the reflection information disc is received from 2, the motor 30 is drive-controlled so that the azimuth angle of the analyzer 14 becomes parallel to the y axis in the second rotation state.

When the analyzer 14 is in the first rotation state, the detection system of this embodiment is the same as the detection system for the magneto-optical disk in the first embodiment, and in the second rotation state,
This is the same as the detection system for the reflective information disc in the fourth embodiment.

The operation of the optical head configured as described above will be described below with reference to the drawings.

First, when the optical disc 3 is a magneto-optical disc, the light spots formed on the optical disc 3 are the same as those in FIG. 1B in the first embodiment, and their main reflected light and sub-reflected light are obtained. Part of the beam splitter 12
Is reflected by

On the other hand, a signal corresponding to the magneto-optical disk is output from the type determination unit 22 as a determination result to the motor drive control unit 3
It is output to 1. The motor drive control unit 31 drives and controls the motor 30 to rotate the analyzer 14 via the first gear 29 and the second gear 28 so that the analyzer 14 is in the first rotation state.

As a result, the detection system composed of the analyzer 14, the photodetector 15, and the differential amplifier 16 becomes the same as the detection system for the magneto-optical disk in the first embodiment, and therefore the operation of the first embodiment is performed. At the output of the differential amplifier 16, a reproduction signal of the magneto-optical disk from which the crosstalk component is removed can be obtained.

Next, when the optical disc 3 is a reflection information disc, the light spots formed on the optical disc 3 are the same as those in FIG. 6B in the fourth embodiment, and their main reflected light and sub-reflected light are reflected. Part of the light is a beam splitter 1
It is reflected at 2.

On the other hand, a signal corresponding to the magneto-optical disk is output from the type determination unit 22 as a determination result to the motor drive control unit 3
It is output to 1. The motor drive control unit 31 drives and controls the motor 30 to rotate the analyzer 14 via the first gear 29 and the second gear 28 so that the analyzer 14 is in the second rotation state.

As a result, the detection system composed of the analyzer 14, the photodetector 15 and the differential amplifier 16 becomes the same as the detection system for the reflection information disc in the fourth embodiment,
According to the operation of the fourth embodiment, the reproduced signal of the reflection information disc from which the crosstalk component is removed can be obtained at the output of the differential amplifier 16.

Therefore, according to this embodiment, it is possible to obtain a reproduction signal from which the crosstalk component is removed regardless of whether the optical disc 3 is a magneto-optical disc or a reflection information disc.

As in the sixth embodiment, the present embodiment has an effect that the amount of light input to the detection system is almost 100% and the S / N ratio of the reproduced signal is further improved, but the rotation of the analyzer 14 is increased. Since it is realized by the above, it is not necessary to provide two detection systems.

In the present embodiment, the mechanism for rotating the analyzer 14 is exemplified by a mechanism including a motor and a gear, but it is not necessary to pay particular attention to this mechanism. Rotation angle is 2
Since the value is good, a simpler mechanism using a lever and an electromagnetic plunger is also conceivable.

As described above, according to the present embodiment, the detection system comprises the analyzer for removing the crosstalk component, the photodetector, and the differential amplifier, and the analyzer detects the reproduction signal of the magneto-optical disk. By providing the binary switching means for the rotating state and the second rotating state for detecting the reproduction signal of the reflection information disc, it is possible to reproduce whether the optical disc is a magneto-optical disc or a reflection information disc. In addition to the effect of the fifth embodiment that the crosstalk component can be removed and the effect of the sixth embodiment that the S / N of the reproduction signal is improved, only one detection system is required, and a significant cost reduction is realized. .

[0140]

As described above, the optical head of the present invention irradiates the recording mark of the recording medium with the main light spot to obtain the main reflected light, and irradiates the sub-light spot in the vicinity of the recording mark. By obtaining sub-reflected light that is electromagnetically separable from the main reflected light and performing calculations between the signals of the main reflected light and the sub-reflected light, the cross-talk component in the vicinity region in the main reflected light is converted into the sub-reflected light. Since it can be reduced by utilizing it, it can be constituted by an optical head using a relatively inexpensive long-wavelength semiconductor laser even when reproducing a recording medium having a high density recording, and the cost can be reduced, and the NA is increased. Since it is not necessary, it is possible to provide an optical head having various excellent features such as being extremely stable systematically with respect to changes in the substrate thickness and changes in inclination of the recording medium, and having high reliability.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration diagram and an operation of an optical head according to a first embodiment of the present invention.

FIG. 2 is a diagram showing signal detection of main reflected light of the same optical head.

FIG. 3 is a diagram showing crosstalk detection and signal detection by sub-reflected light of the same optical head.

FIG. 4 is a diagram showing a configuration diagram and an operation of an optical head according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration and an operation of an optical head according to a third embodiment of the present invention.

FIG. 6 is a diagram showing the configuration and operation of an optical head according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing signal detection of the optical head.

FIG. 8 is a configuration diagram of an optical head according to a fifth embodiment of the present invention.

FIG. 9 is a configuration diagram of an optical head according to a sixth embodiment of the present invention.

FIG. 10 is a configuration diagram of an optical head according to a seventh embodiment of the present invention.

FIG. 11 is a diagram showing a reproducing state by a conventional optical head.

[Explanation of symbols]

 1 Magneto-optical disc 2 Reflection information disc 3 Optical disc 10 Semiconductor laser 11 Polarization hologram 12 Beam splitter 13 Objective lens 14, 18, 19 Analyzer 15, 20 Photodetector 16, 21 Differential amplifier 17 Polarization hologram 22 Type determination part 23 Signal Selection unit 24 Half mirror 25 Mirror 26 Motor 27 Motor drive control unit 28 Second gear 29 First gear 30 Motor 31 Motor drive control unit 101 First detection system 102 Second detection system

Claims (17)

[Claims] 1. An optical head, which scans a recording medium and reproduces at least information, irradiates a main light spot on a recording mark of the recording medium to obtain main reflected light, and a near region substantially adjacent to the recording mark. To obtain a sub-reflected light that is electromagnetically separable from the main-reflected light, and the main-reflected light or the component of the vicinity region in the electric signal corresponding to the main-reflected light is added to the sub-reflected light. An optical head that reduces the reflected light. 2. The sub-light spot irradiates the main light spot onto at least one of two left and right neighboring areas in the scanning direction or two front and back neighboring areas.
The described optical head. 3. The recording medium uses a change in magnetization as an information code,
The main light spot is linearly polarized, the sub light spot has a plane of polarization substantially perpendicular to the main light spot, and is not parallel or perpendicular to the main light spot in the main reflected light and the sub reflected light.
The optical head according to claim 1, wherein a difference between a polarization component and a second polarization component that is substantially perpendicular to the first polarization component is detected. 4. The recording medium uses a change in the amount of reflected light as an information code, the main light spot is linearly polarized, and the sub light spot has a polarization plane substantially perpendicular to the main light spot. The optical head according to claim 1, wherein a difference between a first polarization component substantially parallel or substantially perpendicular to the main light spot therein and a second polarization component substantially perpendicular to the first polarization component is detected. 5. A main light spot is linearly polarized, and a sub-light spot is polarized light substantially perpendicular to said main light spot, comprising an analyzing means for transmitting a first polarization component and a second polarization component which are substantially perpendicular to each other. The recording medium has a surface, and the information code of the recording medium changes the rotation angle around the optical axis direction of the light detecting means by a change in magnetization or the amount of reflected light, and transmits the main reflected light and the sub reflected light to the light detecting means. The optical head according to claim 1, wherein a difference between the first polarized light component and the second polarized light component is detected. 6. The main light spot is linearly polarized, the sub light spot has a plane of polarization substantially perpendicular to the main light spot, and is not parallel or perpendicular to the main light spot in the main reflected light and the sub reflected light. A first detection system that detects a difference between a first polarization component and a second polarization component that is substantially perpendicular to the first polarization component; and a first detection system that is parallel or perpendicular to the main light spots in the main reflected light and the sub reflected light. The optical head according to claim 1, further comprising a second detection system that detects a difference between a third polarization component and a fourth polarization component that is substantially perpendicular to the third polarization component. 7. A recording medium having a plurality of recording tracks that are substantially parallel to each other and using a change in magnetization as an information code,
Linearly polarized first emitted light and second and third emitted light having polarization planes substantially perpendicular to the first emitted light are provided on both sides of the first recording track and the first recording track, respectively. The adjacent second and third recording tracks are irradiated as first to third light spots arranged on a substantially straight line substantially perpendicular to the recording tracks, and the first emitted light in the reflected light thereof is emitted. An optical head for detecting a difference between a first polarization component having an azimuth angle that is at least not parallel or perpendicular to a plane of polarization and a second polarization component having an azimuth angle substantially perpendicular to the first polarization component. 8. A recording medium which has a recording track and uses a change in magnetization as an information code, and irradiates the recording track with a first emitted light which is a linearly polarized light to form a first light spot. The second and third emitted lights having polarization planes substantially perpendicular to the emitted light are radiated as second and third light spots before and after the vicinity of the first light spot of the recording track, and in the reflected light thereof. An optical head for detecting a difference between at least a first polarization component having an azimuth angle that is not parallel or perpendicular to the polarization plane of the first outgoing light and a second polarization component having an azimuth angle that is substantially perpendicular to the first polarization component. 9. A recording medium having a plurality of recording tracks that are substantially parallel to each other and using a change in magnetization as an information code,
The first emitted light, which is linearly polarized light, is applied to the first recording track as a first light spot, and the first and second recording tracks adjacent to both sides of the first recording track are provided with the first light spot.
As second and third light spots, the second and third emitted lights having polarization planes substantially perpendicular to the emitted light are arranged on a substantially straight line passing through the first light spot substantially perpendicular to the recording track. The fourth and fifth emitted lights having the polarization planes that are substantially perpendicular to the first emitted light are irradiated before and after the first light spot of the first recording track near the first light spot. A first polarized component having an azimuth angle that is radiated as a spot and has an azimuth angle that is at least not parallel or perpendicular to the polarization plane of the first emitted light in the reflected light and a second polarized light component that has an azimuth angle substantially perpendicular to the first polarized light component. An optical head that detects the difference between 10. The recording medium is a recording medium in which a change in the amount of reflected light is used as an information code, and a second polarized light which is substantially parallel to the polarization plane of the first emitted light in the reflected light and a second polarized light which is substantially perpendicular to the first polarized light component. The optical head according to claim 7, which detects a difference with a component. 11. A first emitted light that is linearly polarized light and is substantially perpendicular to the first emitted light, which is used for a recording medium that has a plurality of recording tracks that are substantially parallel to each other and uses a change in magnetization as an information code. Radiating means for generating second and third emitted light having a predetermined optical axis angle symmetrically with respect to the optical axis of the first emitted light by the light of the polarization plane, the first recording track and the first recording. The first, second, and third recording tracks, which are adjacent to both sides of the track, are made to condense the first, second, and third emitted lights, respectively, and are arranged on a substantially straight line substantially perpendicular to the recording track. Condensing means for irradiating as a third light spot and condensing reflected light thereof, first polarized light component and second polarized light component which are polarized light components substantially perpendicular to each other with at least a part of the reflected light as an input. The components are spatially separated and output, and the first polarized component is output as the first output. Light detecting means for making an azimuth angle at least not parallel or perpendicular to the plane of polarization of the emitted light, and light detection for receiving the first polarization component and the second polarization component in independent regions to generate the first signal and the second signal. Means, differential detection means for detecting a difference between the first signal and the second signal, and at least a part of the reflected light arranged on an optical path between the emitting means and the condensing means. An optical head comprising: a light beam separating means for outputting to a light means. 12. A first emitted light which is a linearly polarized light and a light having a plane of polarization substantially perpendicular to the first emitted light, which is used for a recording medium having a recording track and having a change in magnetization as an information code. Radiating means for generating second and third emitted light having a predetermined optical axis angle symmetrical to the optical axis of the first emitted light;
Emitted light as a first light spot on the recording track, and the second and third emitted light as second and third light spots before and after the vicinity of the first light spot on the recording track. Condensing means for irradiating and condensing the reflected light thereof, and spatially separating the first polarized component and the second polarized component which are polarized components substantially perpendicular to each other with at least a part of the reflected light as an input. And outputs the first polarized component to the first
Detecting means for making an azimuth angle which is at least not parallel or perpendicular to the plane of polarization of the emitted light, and the first polarization component and the second polarization component are received in independent regions to receive the first signal and the second signal.
A light detecting means for generating a signal, a differential detecting means for detecting a difference between the first signal and the second signal, a light detecting means arranged on an optical path between the emitting means and the condensing means, and An optical head comprising: a light beam separating means for outputting at least a part of the light to the light detecting means. 13. A linearly polarized first emitted light used in a recording medium having a plurality of recording tracks substantially parallel to each other and having a change in magnetization as an information code, and being substantially perpendicular to the first emitted light. Radiating means for generating second, third, fourth, and fifth emitted light having a predetermined optical axis angle symmetrically with respect to the optical axis of the first emitted light by the light of the polarization plane, and the first output. First light
Irradiating the recording track as a first light spot, and the second and third emitted lights are admitted to the second and third recording tracks adjacent to both sides of the first recording track substantially perpendicularly to the recording track. Irradiation as second and third light spots arranged on a substantially straight line passing through the first light spot, the fourth,
Converging means for irradiating the fifth emitted light as fourth and fifth light spots before and after the vicinity of the first light spot on the recording track and condensing the reflected light thereof, and at least the reflected light. A first polarized light component and a second polarized light component, which are polarized light components which are partially input and are substantially perpendicular to each other, are spatially separated and output, and the first polarized light component is at least parallel to the polarization plane of the first emitted light. Alternatively, a light detecting means having a non-vertical azimuth angle, a light detecting means for receiving the first polarized component and the second polarized component in independent regions to generate a first signal and a second signal, and the first signal And a second detecting means for detecting a difference between the second signal and the second signal, and a light beam separating unit arranged on an optical path between the emitting means and the condensing means and outputting at least a part of the reflected light to the detecting means. And an optical head. 14. A recording medium is a recording medium in which a change in the amount of reflected light is used as an information code, and the analyzing means receives a first polarized component which is a polarized component which receives at least a part of the reflected light and is substantially perpendicular to each other. 14. The second polarization component is spatially separated and outputted, and the first polarization component has an azimuth angle substantially parallel or substantially perpendicular to the polarization plane of the first outgoing light. The described optical head. 15. A recording medium of which the information code is represented by a change of magnetization is a first type recording medium, and a recording medium of which the change of the reflected light amount is a second type recording medium, and the recording medium is the first type recording medium or the first type recording medium. It is a two-type recording medium, and receives the output from the light beam separating means as input, the second light beam separating means for dividing and outputting the first detection light beam and the second detection light beam having substantially the same light quantity, and the first detection light beam as input. And a second detection system that receives the second detection light beam as an input, and the first detection system is a first polarization component and a second polarization component that are polarization components that are substantially perpendicular to each other. Are spatially separated and output, and the first polarization component is the azimuth angle which is at least not parallel or perpendicular to the polarization plane of the first emitted light, the first polarization component and the second Receives polarized components in independent regions to generate first and second signals The third polarized light is composed of a first light detection means and a first differential detection means for detecting a difference between the first signal and the second signal, and the second detection system is a third polarization which is a polarization component substantially perpendicular to each other. A second light detecting means for spatially separating the component and the fourth polarized light component and outputting the third polarized light component, and for making the third polarized light component have an azimuth angle substantially parallel or substantially perpendicular to the polarization plane of the first emitted light; Three
Second light detection means for receiving a polarization component and the fourth polarization component in independent regions to generate a third signal and a fourth signal, and a second difference for detecting a difference between the third signal and the fourth signal. 14. The optical head according to claim 11, further comprising a motion detecting means. 16. A recording medium of which the information code is represented by a change of magnetization is a first type recording medium, and a recording medium of which the amount of reflected light is represented is a second type recording medium, and the recording medium is the first type recording medium or the first type recording medium. It is a two-type recording medium, and at least a part of the reflected light from the light beam separating means is switched to the first detection optical path or the second detection optical path by a signal for determining the type of the first-type recording medium and the second-type recording medium. And output optical path changing means,
A first detection system provided in the first detection optical path; and a second detection system
A second detection system provided in a detection optical path, wherein the first detection system spatially separates and outputs a first polarization component and a second polarization component which are polarization components substantially perpendicular to each other, A first light detecting means for making the first polarized light component have an azimuth angle which is at least not parallel or perpendicular to the plane of polarization of the first emitted light, and receives the first polarized light component and the second polarized light component in independent regions The first photodetector means for generating one signal and the second signal, and the first differential detector means for detecting the difference between the first signal and the second signal, and the second detection system are mutually substantially The third polarization component and the fourth polarization component, which are vertical polarization components, are spatially separated and output, and the third polarization component has an azimuth angle substantially parallel or substantially perpendicular to the polarization plane of the first emitted light. The second light detecting means receives the third polarized light component and the fourth polarized light component in independent regions, and receives the third light And EP 2 for generating a fourth signal
14. A light detecting means and a second differential detecting means for detecting a difference between the third signal and the fourth signal.
The optical head according to any one of the above. 17. A recording medium of which the information code is represented by a change of magnetization is a first type recording medium, and a recording medium of which the amount of reflected light is represented is a second type recording medium, and the recording medium is the first type recording medium or the first type recording medium. The recording medium is a two-type recording medium, and the detection means is binary-rotated about an axis on which reflected light is incident in accordance with a signal for determining the type of the first-type recording medium and the second-type recording medium.
It has a rotation means for switching between a first rotation state corresponding to the seed recording medium and a second rotation state corresponding to the second type recording medium, and the first rotation state has a first polarization component of the first polarization state. An azimuth angle that is at least not parallel or perpendicular to the plane of polarization of the emitted light, and the second rotation state sets the first polarization component to an azimuth angle that is substantially parallel or substantially perpendicular to the plane of polarization of the first emitted light. The optical head according to any one of 11 to 13.