JP2001160221A - Optical pickup and recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup with which a tracking error sign of a good S-shape characteristic and a focus error signal may be obtained. SOLUTION: The optical pickup 50 has an objective lens 4 which condense and supplies the laser beam from a laser 2 to the tracks of an optical disk 80, a prism 8 to which the laser beam reflected by the optical disk 80 is supplied via the objective lens 4 and a photodetector 7. The ridge line 8Z with the track direction in the prism 8 to which the laser beam reflected by the optical disk 80 is supplied forms an angle of about 45 deg. and the laser beam passes above the ridge line 8Z, is bisected in the perpendicular direction of the ridge line 8Z and is supplied to the photodetector 7. The photodetector 7 has a first main photodetecting section which receives one of both laser beams and a second main photodetecting section which receives the other thereof. The first and second main photodetecting sections are bisected by a main bisecting line. The main bisecting line and the column direction where both laser beams line up are perpendicular.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup for irradiating an optical disk with laser light and a recording / reproducing apparatus.

[0002]

2. Description of the Related Art At present, various recording / reproducing apparatuses for recording and / or reproducing information using an optical disk have been commercialized. An optical pickup of a recording / reproducing apparatus using an optical disk has a laser and an optical system, and irradiates a focused laser beam to the optical disk.

[0003]

FIG. 1 is a schematic structural view showing an optical pickup to be compared with the present invention. The optical pickup 51 includes a semiconductor laser 2, a collimator lens 3, a beam splitter 1, and an objective lens 4.
, A condenser lens 6, a prism 28, and a photodetector 27.

The semiconductor laser 2 outputs linearly polarized laser light and supplies it to the collimator lens 3. The collimator lens 3 converts the laser light from the semiconductor laser 2 into parallel light and supplies the parallel light to the beam splitter 1. Beam splitter 1
Supplies the laser beam from the collimator lens 3 to the objective lens 4 through the laser beam. The objective lens 4 condenses the laser beam from the beam splitter 1 and supplies the laser beam to a track of the optical disc 80 on which lands and / or grooves are formed.

The objective lens 4 returns the laser beam reflected by the optical disk 80 to the beam splitter 1. The beam splitter 1 receives the laser beam from the objective lens 4, reflects the laser beam, and supplies the laser beam to the condenser lens 6. The condenser lens 6 condenses the laser light from the beam splitter 1 and supplies the laser light to the prism 28. Prism 28
Supplies the laser beam from the condenser lens 6 to the photodetector 27. The photodetector 27 receives the laser beam from the prism 28 at a light receiving section and generates an output signal.

FIGS. 2 and 3 show the relationship between the laser light (return laser light) reflected by the beam splitter 1 and supplied to the prism 28 and the ridge 28Z of the prism 28 in the optical pickup 51 of FIG. It is an explanatory view, wherein the outline of the zero-order diffracted light is indicated by a solid ring, and the outline of the ± first-order diffracted light is indicated by a dotted ring. The prism 28 is supplied with laser light in a solid line ring from the beam splitter 1,
The solid ring corresponds to the aperture of the objective lens 4.

[0007] The reflected laser light reflected by the tracks of the optical disk 80 having lands and / or grooves is zero.
Order diffracted light and ± 1st-order diffracted light generated by diffraction by lands and / or grooves. This 0th order diffracted light and ± 1
When the laser light including the second-order diffracted light passes through the prism 28 and is supplied to the photodetector 27, light interference occurs in a region where the 0th-order diffracted light and the ± 1st-order diffracted light overlap and a region where they do not overlap. By using a cylindrical lens instead of the prism 28 in the optical pickup 51 of FIG. 1, it is possible to generate the focus error signal FE by the astigmatism method. However, an offset occurs in the focus error signal FE due to interference of light based on the 0th-order diffracted light and the ± 1st-order diffracted light.

The arrangement of the prism 28 depends on the optical pickup 5
1 is one of the factors that determine the characteristics. The ridge 28Z of the prism 28 can be arranged in various ways.
The laser beam from the beam splitter 1 is split into two by Z and supplied to the photodetector 27. This photodetector 27
Has a light receiving section for receiving both laser lights generated by dividing the laser light into two by the prism 28. The focus error signal FE is obtained from each output signal of the light receiving section by the so-called Foucault method.
It is possible to obtain

As shown in FIG. 2, when the ridge 28Z of the prism 28 is arranged perpendicular to the track direction of the prism 28 to which the laser light reflected by the optical disk 80 is supplied,
Although the tracking error signal TE can be generated from the output signal of the light receiving portion of the photodetector 27, it is difficult to obtain a tracking error signal TE having good S-shaped characteristics.

As shown in FIG. 3, when the ridge 28Z of the prism 28 is arranged in parallel with the track direction of the prism 28 to which the laser light reflected by the optical disk 80 is supplied,
Although the focus error signal FE can be generated from the output signal of the light receiving unit of the photodetector 27, it is difficult to obtain a focus error signal FE having good S-shaped characteristics. The offset amount due to the light interference based on the above becomes large.

An object of the present invention is to provide a recording / reproducing apparatus capable of obtaining a tracking error signal and a focus error signal having good S-shaped characteristics, and an optical pickup usable in the recording / reproducing apparatus. .

[0012]

An optical pickup according to the present invention comprises: a laser for outputting a laser beam;
Alternatively, an objective lens for condensing and supplying laser light from the laser to a track of an optical disk on which a groove is formed, and the laser light reflected on the optical disk is supplied via the objective lens and supplied. A prism for splitting the laser light into two parts, and a photodetector to which both laser lights generated by the splitting by the prism are supplied, and a prism for supplying the laser light reflected by the optical disk; The track direction and the ridge line of the prism form an angle of about 45 degrees or about 135 degrees, and the laser light reflected by the optical disk passes over the ridge line of the prism and is divided into two in the vertical direction of the ridge line, A first detector that receives one of the two laser beams;
And a second main light receiving unit for receiving the other light receiving unit,
The first and second main light receiving sections are equally or substantially equally divided by a main dividing line, and a direction of the main dividing line and a column direction in which the two laser beams are arranged are perpendicular or Substantially vertical.

In the optical pickup according to the present invention, preferably, a collimator lens for converting the laser light from the laser into parallel light, the main laser light and the first and second auxiliary laser light from the collimators are preferably used. A diffraction grating that separates the light into light, and a beam splitter that supplies the laser light from the diffraction grating to the objective lens, wherein the objective lens irradiates a track of the optical disc with the main laser light. Irradiating one of the guide areas on both sides of the track with the first sub-laser light, irradiating the other guide area with the second sub-laser light, and reflecting the light on the optical disc. Returning the laser light to the beam splitter, the beam splitter supplies the laser light from the objective lens to the prism, and Vessel may further include a first to fourth sub light receiving portion, the prism, the supplied from the beam splitter main laser beam and the first and second
Are divided into two, and the main laser light is divided into two.
One of the two divided laser beams is supplied to the first main light receiving portion, and the other is supplied to the second main light receiving portion, so that the first sub laser beam is divided into two portions. One of the two laser beams is supplied to the first sub-light receiving unit and the other is supplied to the second sub-light receiving unit, and the two laser beams generated by dividing the second sub-laser beam into two Is supplied to the third sub-light receiving unit and the other is supplied to the fourth sub-light receiving unit.

In the optical pickup according to the present invention, it is more preferable that each of the first and second main light receiving portions is the main dividing line and a sub-dividing line perpendicular or substantially perpendicular to the main dividing line. Are divided into four equal parts or substantially four equal parts.

[0015] In the optical pickup according to the present invention, it is more preferable that the optical pickup further includes a Wollaston prism located between the beam splitter and the prism, and the Wollaston prism includes the main laser from the beam splitter. The light is split into a first main split laser beam and second and third main split laser beams sandwiching the first main split laser beam and supplied to the prism, and the first split beam from the beam splitter is output from the beam splitter. Is divided into a first sub-divided laser beam and second and third sub-divided laser beams sandwiching the first sub-divided laser beam, and is supplied to the prism. The second sub-laser light is supplied to a fourth
And the fifth and sixth sub-divided laser beams sandwiching the fourth sub-divided laser beam are supplied to the prism, and the photodetector is connected to the third to sixth main laser beams. The prism further includes a light receiving unit and fifth to twelfth sub-light receiving units, wherein the prism is configured to split one of the two laser lights generated by dividing the first main split laser light into two, and to output the first main split laser light to the first main split laser light. The second main light-receiving part is supplied to the second main light-receiving part while the other is supplied to the second main light-receiving part, and one of the two laser lights generated by dividing the second main laser light into two is supplied to the third main light-receiving part. While supplying the other to the fourth main light receiving section, and supplying one of the two laser lights generated by dividing the third main split laser light into two to the fifth main light receiving section. The other is supplied to the sixth main light receiving portion, and both laser beams generated by dividing the first sub-divided laser beam into two are provided. One of the laser beams is supplied to the first sub-light receiving portion, and the other is supplied to the second sub-light receiving portion, and the two sub-light beams generated by dividing the second sub-divided laser beam into two are separated. One of them is supplied to the fifth sub-light receiving unit and the other is supplied to the sixth sub-light receiving unit, and one of the two laser beams generated by dividing the third sub-divided laser beam into two. Is supplied to the seventh sub-light receiving portion and the other is supplied to the eighth sub-light receiving portion. Further, one of the two laser lights generated by dividing the fourth sub-divided laser light into two is The other is supplied to the third sub-light receiving section and the other is supplied to the fourth sub-light receiving section.
, And supplies one of the two laser lights generated by dividing the fifth sub-divided laser light into two, to the ninth sub-light receiving part, and supplies the other to the tenth sub-light receiving part. And supplies one of the two laser beams generated by dividing the sixth sub-divided laser beam into two, to the eleventh sub-light receiving portion and the other to the twelfth sub-light receiving portion. I do.

In the optical pickup according to the present invention, for example, the third main light receiving portion and the fourth main light receiving portion are connected, and the fifth main light receiving portion and the sixth main light receiving portion are connected. May be connected.

In the optical pickup according to the present invention, for example, the fifth sub-light receiving portion and the seventh sub-light receiving portion are connected, and the sixth sub-light receiving portion and the eighth sub-light receiving portion are connected. Are connected to each other, and the ninth sub-light receiving portion and the eleventh
And the tenth sub-light receiving unit and the twelfth sub-light receiving unit may be connected to each other.

In the optical pickup according to the present invention, for example, the first sub-light receiving portion, the fifth sub-light receiving portion, and the seventh sub-light receiving portion are connected, and the second sub-light receiving portion is connected to the first sub-light receiving portion. And the sixth sub-light receiving unit and the eighth sub-light receiving unit are connected, and the third sub-light receiving unit, the ninth sub-light receiving unit, and the eleventh sub-light receiving unit are connected. The fourth sub-light receiving unit, the tenth sub-light receiving unit, and the twelfth sub-light receiving unit may be connected to each other.

In the optical pickup according to the present invention, for example, the first and second main light receiving portions have the same shape, and the first, second, third and fourth sub light receiving portions have the same shape. It may be configured to have the same shape.

In the optical pickup according to the present invention, for example, the optical disk is an optical disk having a land-groove structure in which the lands and the grooves are formed, and a track of the optical disk is one of the lands and the grooves; The guide region may be configured to be the other of the land and the groove.

In the optical pickup according to the present invention, preferably, a focus error signal corresponding to an output signal of the photodetector is supplied, and the objective lens is moved from the recording surface of the optical disk based on the focus error signal. A first actuator for moving in a vertical focus direction, a tracking error signal corresponding to an output signal of the photodetector being supplied, and a first actuator for moving the objective lens in a radial direction of the optical disc based on the tracking error signal. And two actuators.

According to the present invention, there is provided a recording / reproducing apparatus comprising: a laser for outputting a laser beam; and an objective lens for condensing and supplying the laser beam from the laser beam to a track of an optical disc having lands and / or grooves formed thereon. And a prism that supplies the laser light reflected by the optical disk via the objective lens, and divides the supplied laser light into two, and a light to which both laser lights generated by the division by the prism are supplied. A detector, a generation circuit that generates a reproduction signal, a focus error signal, and a tracking error signal based on an output signal of the photodetector; a detection circuit that detects recording information of the optical disc based on the reproduction signal; A first moving the objective lens in a focus direction perpendicular to a recording surface of the optical disc based on a focus error signal; Includes a actuator and a second actuator for moving the objective lens based on the tracking error signal in the radial direction of the optical disc,
The track direction of the prism to which the laser light reflected by the optical disc is supplied and the ridge line of the prism form an angle of about 45 degrees or about 135 degrees, and the laser light reflected by the optical disc is reflected by the prism. The laser light passes through the ridge line and is divided into two in the vertical direction of the ridge line, and the photodetector has a first main light receiving unit that receives one of the two laser beams and a second main light receiving unit that receives the other of the two laser lights. Wherein the first and second main light receiving sections are divided into two equal parts or substantially two equal parts by a main dividing line, and the direction of the main dividing line and the column direction in which the two laser beams are arranged Is vertical or substantially vertical, and the generation circuit generates ｛(a1-b1)
The focus error signal is generated based on a value of (a2-b2), and the tracking error signal is generated based on a value of ((a1 + b1)-(a2 + b2)). Here, a1 is an output signal of a divided area on the side of the second main light receiving unit in both divided areas into which the first main light receiving unit is divided, and b1 is a divided signal of the first main light receiving unit. B2 is an output signal of a divided area on the side opposite to the second main light receiving section side of the divided areas, and b2 is the first signal of the divided areas where the second main light receiving section is divided. A2 is an output signal of a divided region on the main light receiving portion side, and a2 is an output signal of a divided region on the opposite side to the first main light receiving portion side of both divided regions into which the second main light receiving portion is divided. is there.

In the recording / reproducing apparatus according to the present invention, preferably, a collimator lens for converting the laser light from the laser into parallel light, and the laser light from the collimators are used as the main laser light and the first and second sub-lights. A diffraction grating that separates the laser light into light; and a beam splitter that supplies the laser light from the diffraction grating to the objective lens. The objective lens irradiates a track of the optical disk with the main laser light. And irradiating one of the guide areas on both sides of the track with the first sub-laser light, irradiating the other guide area with the second sub-laser light, Returning the reflected laser light to the beam splitter, the beam splitter supplies the laser light from the objective lens to the prism, and Further it has a first to fourth sub light receiving portion, the prism, the supplied from the beam splitter main laser beam and the first and second
Are divided into two, and the main laser light is divided into two.
One of the two divided laser beams is supplied to the first main light receiving portion, and the other is supplied to the second main light receiving portion, so that the first sub laser beam is divided into two portions. One of the two laser beams is supplied to the first sub-light receiving unit and the other is supplied to the second sub-light receiving unit, and the two laser beams generated by dividing the second sub-laser beam into two Is supplied to the third sub-light receiving unit, and the other is supplied to the fourth sub-light receiving unit.
1)-(a2 + b2) -γ (E1 + F1-E2-F)
2) The tracking error signal is generated based on the value of｝. Here, E1 is an output signal of the first sub-light receiving unit, E2 is an output signal of the second sub-light receiving unit, and F1
Is an output signal of the third sub-light receiving unit, F2 is an output signal of the fourth sub-light receiving unit, and γ is a constant.

In the recording / reproducing apparatus according to the present invention, it is more preferable that each of the first and second main light receiving sections is provided with the main division line and a sub-division perpendicular or substantially perpendicular to the main division line. The generation circuit divides the discrimination signal indicating that the track is either the land or the groove into ｛(A1 + B1-C
1-D1)-(A2 + B2-C2-D2)}. However, D1 is 4 when the first main light receiving section is 4
Of the divided areas, the second main light receiving unit side 2
A1 is an output signal of the divided region on the side of the second sub-light receiving unit in one divided region, and A1 is the output signal of the side of the second sub-light receiving unit in the two divided regions on the side of the second main light receiving unit. And B1 is a divisional area located in the diagonal direction of the divisional area that generates the output signal D1 among the divisional areas into which the first main light receiving unit is divided into four. C1 is an output signal of a divided area which is located in a diagonal direction of a divided area in which the first main light receiving portion is divided into four and which generates the output signal A1. . B2 is a divided area on the side of the third sub-light-receiving section among two divided areas on the side of the first main light-receiving section among the divided areas obtained by dividing the second main light-receiving section into four. Output signal
C2 is an output signal of a divided area of the two divided areas on the first main light receiving section side opposite to the third sub-light receiving section side, and D2 is an output signal of the second main light receiving section. Is an output signal of a divided area which is located in a diagonal direction of the divided area for generating the output signal B2 among the divided areas divided into four, and A2
Is an output signal of a divided area located in a diagonal direction of the divided area for generating the output signal C2 among the divided areas obtained by dividing the second main light receiving portion into four.

In the recording / reproducing apparatus according to the present invention, it is more preferable that the recording / reproducing apparatus further includes a Wollaston prism located between the beam splitter and the prism, and the Wollaston prism is configured to receive the main beam from the beam splitter. The laser beam is split into a first main split laser beam and second and third main split laser beams sandwiching the first main split laser beam, and is supplied to the prism. One sub-laser beam is divided into a first sub-divided laser beam and second and third sub-divided laser beams sandwiching the first sub-divided laser beam and supplied to the prism. The second sub-laser light is divided into a fourth sub-divided laser beam and a fifth sub-laser beam sandwiching the fourth sub-divided laser beam.
And the laser beam is divided into a sixth sub-divided laser beam and supplied to the prism, the photodetector further includes third to sixth main light receiving units and fifth to twelfth sub light receiving units, The prism supplies one of the two laser lights generated by dividing the first main divided laser light into two to the first main light receiving unit and supplies the other to the second main light receiving unit. Supplying one of the two laser beams generated by splitting the second main split laser beam into two to the third main light receiving portion and the other to the fourth main light receiving portion; One of the two laser beams generated by dividing the three main split laser beams into two is supplied to the fifth main light receiving unit, and the other is supplied to the sixth main light receiving unit. When one of the two laser beams generated by dividing the sub-divided laser beam into two is supplied to the first sub-light receiving portion, The other is supplied to the second sub-light receiving unit, and one of the two laser beams generated by dividing the second sub-divided laser light into two is supplied to the fifth sub-light receiving unit and the other is supplied to the fifth sub-light receiving unit. The laser beam is supplied to a sixth sub-light receiving unit, and one of the two laser beams generated by dividing the third sub-divided laser beam into two is supplied to the seventh sub-light receiving unit and the other is supplied to the eighth sub-light receiving unit. The laser beam is supplied to a sub-light receiving unit, and one of the two laser beams generated by dividing the fourth sub-divided laser beam into two is supplied to the third sub-light receiving unit and the other is supplied to the fourth sub-light receiving unit.
, And supplies one of the two laser lights generated by dividing the fifth sub-divided laser light into two, to the ninth sub-light receiving part, and supplies the other to the tenth sub-light receiving part. And supplies one of the two laser beams generated by dividing the sixth sub-divided laser beam into two, to the eleventh sub-light receiving portion and the other to the twelfth sub-light receiving portion. I do.

In the recording / reproducing apparatus according to the present invention, for example,
The third main light receiving unit and the fourth main light receiving unit may be connected to each other, and the fifth main light receiving unit and the sixth main light receiving unit may be connected to each other.

In the recording / reproducing apparatus according to the present invention, for example,
The fifth sub-light receiving portion is connected to the seventh sub-light receiving portion, the sixth sub-light receiving portion is connected to the eighth sub-light receiving portion, and the ninth sub-light receiving portion is connected to the fifth sub-light receiving portion. A portion may be connected to the eleventh sub light receiving portion, and the tenth sub light receiving portion and the twelfth sub light receiving portion may be connected.

In the recording / reproducing apparatus according to the present invention, for example,
The first sub-light receiving unit, the fifth sub-light receiving unit, and the seventh sub-light receiving unit are connected, and the second sub-light receiving unit, the sixth sub-light receiving unit, and the eighth The third sub-light receiving unit is connected to the third sub-light receiving unit, the ninth sub-light receiving unit is connected to the eleventh sub-light receiving unit, and the fourth sub-light receiving unit is connected to the fourth sub-light receiving unit. The tenth sub-light receiving unit and the twelfth sub-light receiving unit may be connected to each other.

In the recording / reproducing apparatus according to the present invention, for example,
The first and second main light receiving sections have the same shape,
The first, second, third, and fourth sub-light receiving units may have the same shape.

In the recording / reproducing apparatus according to the present invention, for example,
The optical disk is an optical disk having a land-groove structure in which the lands and the grooves are formed, a track of the optical disk is one of the lands and the grooves, and the guide area is the other of the lands and the grooves. May be adopted.

In the recording / reproducing apparatus according to the present invention, preferably, the optical disk is a phase-change type optical disk or a compact disk, and the generation circuit is configured to output each of the output signals of the first and second main light receiving sections. The reproduction signal is generated based on the sum of

In the recording / reproducing apparatus according to the present invention, preferably, the optical disk is a magneto-optical disk, and the generation circuit is configured to calculate a sum of output signals of the third and fourth main light receiving units, The reproduction signal is generated based on a difference between the output signals of the fifth and sixth main light receiving units and the sum of the output signals.

[0033]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 4 is a schematic configuration diagram showing a first embodiment of the optical pickup according to the present invention.

The optical pickup 50 includes a semiconductor laser 2, a collimator lens 3, a beam splitter 1,
Objective lens 4, condensing lens 6, prism 8, photodetector 7, lens holder 4H, focusing actuator 4F as a first actuator, and tracking actuator 4 as a second actuator
It has T.

The objective lens 4 is held by a lens holder 4H. The focusing actuator 4F is
Based on the drive signal Sfe, the lens holder 4H is moved in a focus direction perpendicular to the recording surface of the optical disc 80, and as a result, the objective lens 4 is moved in the focus direction.
The tracking actuator 4T moves the lens holder 4H in the radial direction of the optical disk 80 based on the drive signal Ste, and as a result, moves the objective lens 2 to the optical disk 80.
In the radial direction.

The semiconductor laser 2 outputs a linearly polarized laser beam based on the drive signal SL and supplies it to the collimator lens 3. The collimator lens 3 converts the laser light from the semiconductor laser 2 into parallel light and supplies the parallel light to the beam splitter 1. The beam splitter 1 passes the laser beam from the collimator lens 3 and supplies it to the objective lens 4. The objective lens 4 condenses the laser beam from the beam splitter 1 and supplies the laser beam to a track of the optical disc 80 on which lands and / or grooves are formed. The optical disk 80 is composed of, for example, a compact disk (CD), a digital video disk (DVD), a phase change optical disk (PD), and the like.

The objective lens 4 returns the laser beam reflected by the optical disk 80 to the beam splitter 1. The beam splitter 1 receives the laser beam from the objective lens 4, reflects the laser beam, and supplies the laser beam to the condenser lens 6. The condenser lens 6 condenses the laser light from the beam splitter 1 and supplies the laser light to the prism 8. Prism 8
The laser beam from the condenser lens 6 passes through and is supplied to the photodetector 7. The photodetector 7 receives the laser beam from the prism 8 at a light receiving section and generates an output signal.

FIG. 5 is an explanatory diagram showing how the prism 8 splits the laser light from the condenser lens 6 in the optical pickup 50 of FIG. The laser light from the condenser lens 6 passes on the ridge 8M of the prism 8, is divided into two in the vertical direction of the ridge 8M, and is supplied to the photodetector 7.

FIG. 6 shows a laser beam (return laser beam) reflected by the beam splitter 1 and supplied to the prism 8 in the optical pickup 50 of FIG.
FIG. 4 is an explanatory diagram showing the relationship with Z, where the outline of the 0th-order diffracted light is indicated by a solid ring and the outline of the ± 1st-order diffracted light is indicated by a dotted ring. The prism 8 is supplied with laser light in a solid line ring from the beam splitter 1, and the solid line ring corresponds to the radius or the aperture of the objective lens 4. The ridge line 8Z of the prism 8 makes an angle of about 45 degrees or about 135 degrees with the track direction of the prism 8 to which the laser light reflected by the optical disk 80 is supplied.

FIG. 7 is a schematic configuration diagram showing a light receiving section of the photodetector 7 of the optical pickup 50 of FIG. The photodetector 7 includes a first main light receiving unit 101 and a second main light receiving unit 1.
02. The first main light receiving unit 101 includes a prism 8
The second main light receiving unit 102 receives one of the two laser lights generated by dividing the laser light into two, and receives the other of the two laser lights. First and second main light receiving sections 10 of FIG.
Reference numerals 1 and 102 have the same shape, and beam spots 101Bm and 102Bm are formed by the supplied laser light.

The first main light receiving portion 101 is provided with a main dividing line 101
M is divided into two equal parts or substantially two equal parts.
The second main light receiving portion 102 is divided into two equal parts or substantially two equal parts by a main dividing line 102M. Main parting line 10
1M, 102M and first and second main light receiving sections 10
The column direction in which 1,102 are lined up is vertical or substantially vertical.

Of the two divided areas Ra1 and Rb1 obtained by dividing the first main light receiving section 101, the divided area Ra1 on the side of the second main light receiving section 102 generates an output signal a1. Of the divided regions Ra1 and Rb1 obtained by dividing the first main light receiving unit 101, the divided region R on the side opposite to the second main light receiving unit 102 side
b1 generates an output signal b1.

Of the divided areas Ra2 and Rb2 obtained by dividing the second main light receiving section 102, the divided area Rb2 on the first main light receiving section 101 side generates an output signal b2. Of the divided regions Ra2 and Rb2 obtained by dividing the second main light receiving unit 102, the divided region R on the opposite side to the first main light receiving unit 101 side
a2 generates an output signal a2.

FIG. 8 is an explanatory diagram showing the relationship between the shape of the beam spot formed on the first and second light receiving sections and the distance between the objective lens 4 and the optical disk 80. FIG.
(A) shows a case where the objective lens 4 is too close to the optical disc 80, and shows a semicircular beam spot 101Bm.
Is formed in the divided area Ra1, and the semicircular beam spot 102Bm is formed in the divided area Rb2.

In FIG. 8B, the distance between the objective lens 4 and the optical disk 80 is the focusing distance, and the laser light from the objective lens 4 is focused on the recording surface (signal surface) of the optical disk 80. And a circular or substantially circular beam spot 101Bm is formed in the center of the first main light receiving portion 101, and a circular or substantially circular beam spot 102Bm is formed.
Bm is formed at the center of the second main light receiving unit 102.

FIG. 8C shows a case where the objective lens 4 is too far from the optical disc 80, in which a semicircular beam spot 101Bm is formed in the divided area Rb1, and a semicircular beam spot 102Bm is formed in the divided area Rb1. Ra2 is formed.

FIG. 9 is a characteristic diagram showing characteristics of the focus error signal FE 'obtained from the output signals of the first and second main light receiving sections. In the horizontal axis of this characteristic diagram, the objective lens 4
The distance between the focal point formed by the laser beam from the optical disk and the recording surface of the optical disk 80 is defined as the defocus amount. Further, the focus error signal FE ′ = a1−b1. Optical disk 8
0 indicates an optical disk having a land-groove structure in which the land width and the groove width are almost the same.

In the characteristic diagram of FIG. 9, the focus error signal FE 'has a good S-shaped characteristic on the mirror surface of the optical disk 80. When the focal point of the laser beam from the objective lens 4 is located on the groove (G) or the land (L), the focus error signal FE ′ has a slightly distorted S-shaped characteristic. The boundary between the groove and the land includes a boundary where the groove is on one side and the land is on the other side (GL boundary), and a boundary where the land is on one side and the groove is on the other side (LG boundary). . When the focal point of the laser beam is located on the GL boundary or the LG boundary, the focus error signal FE ′ has a considerably distorted S-shaped characteristic.

FIG. 10 is a characteristic diagram showing characteristics of the focus error signal FE obtained from the output signals of the first and second main light receiving sections. In the horizontal axis of this characteristic diagram, the objective lens 4
The distance between the focal point formed by the laser beam from the optical disk and the recording surface of the optical disk 80 is defined as the defocus amount. Further, the focus error signal FE is set to be a1−b1−a2 + b2. The optical disk 80 has a land-groove structure in which the land width and the groove width are almost the same.

In the characteristic diagram of FIG. 10, when the focal point of the laser beam from the objective lens 4 is located on the groove (G) or the land (L), the focus error signal FE becomes
It has good S-shaped characteristics. Further, the focal point of the laser beam is GL
When located on the boundary or the LG boundary, the focus error signal FE has a good S-shaped characteristic.

FIG. 11 is a characteristic diagram showing characteristics of the tracking error signal TE obtained from the output signals of the first and second main light receiving sections. This characteristic diagram shows the characteristic of the tracking error signal TE when the focal point of the laser light is positioned on the recording surface of the optical disk 80 and the focal point of the laser light crosses the track. On the horizontal axis of this characteristic diagram, the case where the focal point is located on the groove is represented as 0 and 1, and
The case where the focal point is located on the land is represented as 0.5, and the deviation of the focal point from the groove is defined as the detrack amount.

In the characteristic diagram of FIG. 11, the solid line indicates the characteristic of the tracking error signal TE. The characteristic of the tracking error signal TE ′ generated by the push-pull method using the two-segment photodetector by removing the prism 8 from the optical pickup 50 is indicated by a dotted line. The solid tracking error signal TE has a smaller amplitude than the dotted characteristic curve, but has good S-shaped characteristics.

FIG. 12 shows the optical pickup 50 shown in FIG.
1 is a schematic block diagram illustrating an embodiment of a recording / reproducing device having a suffix (a). The recording / reproducing device 90 includes a motor 3
0, a motor drive circuit 35, a phase compensation circuit 40, an amplifier circuit 42, an optical pickup 50, an amplifier circuit (head amplifier) 52, a laser drive circuit 55, and a generation circuit 6.
0, an information detection circuit (detection circuit) 65, and a control circuit 70
And The recording / reproducing device 90 is an optical disk 80
Play the recorded information recorded in the.

The control circuit 70 is a controller that controls the entire recording / reproducing device 90, and is constituted by, for example, a microcomputer. This control circuit 7
0 controls the motor 30, the motor drive circuit 35, the laser drive circuit 55, the optical pickup 50, the phase compensation circuit 40, the generation circuit 60, the information detection circuit 65, and the like.

The optical pickup 50 irradiates a laser beam LB to a reproduction position of the optical disk 80 during reproduction. The laser drive circuit 55 generates a drive signal SL under the control of the control circuit 70, drives the semiconductor laser 2 in the optical pickup 50 with the drive signal SL, and causes the semiconductor laser 2 to output a laser beam LB.

The motor 30 is constituted by, for example, a spindle motor, and rotates the optical disk 80 at a predetermined rotation speed. The motor 30 rotates the optical disk 80 so that the linear velocity becomes constant, for example.

The motor drive circuit 35 supplies drive power to the motor 30 to drive the motor 30. The motor drive circuit 35 may perform rotation control of the motor 30 by PWM (Pulse Width Modulation) control, and may perform PLL (Ph
Rotation control may be performed by ase Locked Loop) control.

The amplifying circuit 52 includes output signals a1, a2, b of each light receiving section of the photodetector 7 included in the optical pickup 50.
1 and b2 are amplified and supplied to the generation circuit 60.

The generation circuit 60 generates a signal based on the amplified output signals a1, a2, b1, and b2 from the amplification circuit 52.
A reproduction signal RF, a focus error signal FE, and a tracking error signal TE are generated. Further, if necessary, a discrimination signal LG to be described later is generated, and the discrimination signal LG is output to the phase compensation circuit 4
0, the information is supplied to the information detection circuit 65, the control circuit 70, and the like. The generation circuit 60 outputs, for example, the sum (a1 + a2 + b1 + b) of the output signals a1, a2, b1, and b2 from the amplification circuit 52.
The reproduction signal RF is generated based on 2).

The phase compensation circuit 40 generates a compensation signal by compensating (phase compensation and / or frequency compensation) the focus error signal FE and the tracking error signal TE, and supplies the compensation signal to the amplifier circuit 42.

The amplification circuit 42 has a focus error signal FE.
Is supplied to the focusing actuator 4F in the optical pickup 50. The focusing actuator 4F moves the objective lens 4 in the focus direction based on the drive signal Sfe (ie, a signal amplified by compensating the focus error signal FE). Further, the amplifier circuit 42 supplies the drive signal Ste obtained by amplifying the compensation signal of the tracking error signal TE to the tracking actuator 4T in the optical pickup 50. The tracking actuator 4T moves the objective lens 4 in the disk radial direction based on the drive signal Ste (that is, a signal amplified by compensating for the tracking error signal TE).

The information detection circuit 65 is supplied with the reproduction signal RF from the generation circuit 60, demodulates the reproduction signal RF, reproduces the recorded information on the optical disk 80, and outputs the reproduced recorded information as the output signal So. . Recording / reproducing device 90
Generates the focus error signal FE and the tracking error signal TE having good S-shaped characteristics from the output signal of the optical pickup 50 and controls the position of the objective lens 4 in the optical pickup 50, so that the reliability of the reproduced information is improved. It is possible.

In the recording / reproducing apparatus 90 shown in FIG. 12, an optical pickup 50 'shown in FIG.
May be used. The optical pickup 50 ′ has a diffraction grating 9 disposed between the beam splitter 1 and the collimator lens 3 with respect to the optical pickup 50 of FIG. This is a configuration using a photodetector 7 'for receiving the second sub-laser light.

In the optical pickup 50 ′ shown in FIG. 13, the collimator lens 3 converts the laser beam from the semiconductor laser 2 into parallel light and supplies it to the diffraction grating 9. The diffraction grating 9 separates the laser beam from the collimators 3 into a main laser beam and first and second sub-laser beams and supplies the laser beam to the beam splitter 1. The beam splitter 1 supplies the laser light from the diffraction grating 9 to the objective lens 4.

The objective lens 4 irradiates a track of the optical disk 80 with a main laser beam, irradiates one of the guide areas on both sides of the track with a first sub-laser light, and irradiates the other with the first sub-laser light. The guide region is irradiated with the second sub-laser light. Further, the laser beam reflected by the optical disk 80 is returned to the beam splitter 1. For example, a land is a track, and grooves on both sides (or both sides) of the land are guide areas. Alternatively, the groove is a track, and lands on both sides (or both sides) of the groove are guide areas. The beam splitter 1 supplies the laser beam from the objective lens 4 to the prism 8 via the condenser lens 6.

FIG. 14 shows the optical pickup 50 'of FIG.
FIG. 4 is a schematic configuration diagram illustrating a light receiving unit included in the photodetector 7 ′ of FIG. The photodetector 7 'has first and second main light receiving portions 111 and 112 having the same shape, and first to fourth sub light receiving portions 121 to 124 having the same shape.

The prism 8 of the optical pickup 50 ′ divides the main laser beam and the first and second sub-laser beams supplied from the condenser lens 6 into two.
The prism 8 supplies one of the two laser beams generated by dividing the main laser beam into two, to the first main light receiving unit 111, and supplies the other to the second main light receiving unit 112. In addition, one of the two laser beams generated by dividing the first sub-laser beam into two is supplied to the first sub-light receiving unit 121 and the other is supplied to the second sub-light receiving unit 122. Further, one of the two laser beams generated by dividing the second sub-laser beam into two is supplied to the third sub-light receiving unit 123 and the other is supplied to the fourth sub-light receiving unit 124.

The first main light receiving section 111 has a main dividing line 111
M is divided into two equal parts or substantially two equal parts.
The second main light receiving portion 112 is divided into two equal parts or substantially two equal parts by a main dividing line 112M. Main dividing line 11
1M, 112M directions and first and second main light receiving sections 11
The column direction in which 1,112 are arranged is vertical or substantially vertical.

Of the divided areas Ra1 and Rb1 obtained by dividing the first main light receiving section 111, the divided area Ra1 on the side of the second main light receiving section 112 generates an output signal a1. Of the divided regions Ra1 and Rb1 obtained by dividing the first main light receiving unit 111, the divided region R on the side opposite to the second main light receiving unit 112 side
b1 generates an output signal b1.

Of the divided areas Ra2 and Rb2 obtained by dividing the second main light receiving section 112, the divided area Rb2 on the first main light receiving section 111 side generates an output signal b2. Of the divided regions Ra2 and Rb2 obtained by dividing the second main light receiving portion 112, the divided region R on the side opposite to the first main light receiving portion 111 side
a2 generates an output signal a2.

The first sub light receiving section 121 generates an output signal E1. The second sub light receiving section 122 generates an output signal E2. The third sub-light receiving unit 123 generates an output signal F1. The fourth sub light receiving section 124 generates an output signal F2.

In the recording / reproducing apparatus 90 having the optical pickup 50 ', the main light receiving section 11 of the optical pickup 50'
1, 112, output signals a1, a2, b1, b2 and output signals E1, E2, F1, F2 of the sub-light receiving units 121 to 124.
Is supplied to the amplifier circuit 52. The amplification circuit 52 amplifies the signals a1, a2, b1, b2, E1, E2, F1, and F2 and supplies the signals to the generation circuit 60. The generation circuit 60 generates a focus error signal F based on a signal from the amplification circuit 52.
E, a tracking error signal TE, a reproduction signal RF and the like are generated. This tracking error signal TE is expressed as TE = a1 +
b1- (a2 + b2)-[gamma] (E1 + F1-E2-F2)
And Here, γ is a constant for correcting the light amount difference between the main laser light and the sub-laser light, and correcting the gain difference between the main light-receiving part and the sub-light-receiving part, and is a correction coefficient.

FIG. 15 is a schematic configuration diagram showing a modification of the light receiving section shown in FIG. The light receiving unit shown in FIG. 15 has a configuration similar to the light receiving unit shown in FIG. 14, and has a configuration in which the first and second main light receiving units 111 and 112 are divided into four. In the light receiving unit of FIG. 15, the same components as those of the light receiving unit of FIG. 14 are denoted by the same reference numerals, and the description of the same components will be appropriately omitted. In this case, the photodetector 7 'includes first and second main light receiving sections 111' and 112 'having the same shape.
And first to fourth sub-light receiving units 121 to 124 having the same shape.

The prism 8 of the optical pickup 50 'divides the main laser beam and the first and second sub-laser beams supplied from the condenser lens 6 into two.
The prism 8 supplies one of the two laser beams generated by dividing the main laser beam into two, to the first main light receiving portion 111 ', and supplies the other to the second main light receiving portion 112'.

The first main light receiving section 111 ′ is
1M and a sub-dividing line 111S perpendicular to the main dividing line 111M.
Divides into four equal parts or substantially four equal parts. The second main light receiving portion 112 'is divided into four equal parts or substantially four equal parts by a main dividing line 112M and a sub dividing line 112S perpendicular to the main dividing line 112M. The direction of the main dividing lines 111M and 112M and the column direction in which the first and second main light receiving portions 111 'and 112' are arranged are perpendicular or substantially perpendicular.

Of the divided areas RA1 to RD1 into which the first main light receiving portion 111 'is divided into four, the second main light receiving portion 112'
The divided region RD1 on the side of the second sub-light receiving unit 122 in the two divided regions RA1 and RD1 on the side generates the output signal D1. Two divided regions R on the second main light receiving portion 112 'side
A divided area RA1 of A1, RD1 on the opposite side to the second sub-light receiving section 122 generates an output signal A1. The first main light receiving portion 111 'is divided into four divided areas RA1 to RD.
1, the divided region RD1 for generating the output signal D1
The divided area RB1 located in the diagonal direction of the output signal B1
Generate Of the divided areas RA1 to RD1 in which the first main light receiving unit 111 'is divided into four, the divided area RC located diagonally to the divided area RA1 that generates the output signal A1.
1 generates the output signal C1.

Of the divided areas RA2 to RD2 obtained by dividing the second main light receiving portion 112 'into four, the first main light receiving portion 111'
The divided area RB2 on the third sub-light receiving unit 123 side in the two divided areas RB2 and RC2 on the side generates an output signal B2. Two divided regions R on the first main light receiving portion 111 'side
The divided area RC2 of the side B2, RC2 opposite to the side of the third sub-light receiving section 123 generates the output signal C2. The divided areas RA2 to RD in which the second main light receiving section 112 'is divided into four
2, the divided area RB2 that generates the output signal B2
Are divided in the diagonal direction of the output signal D2
Generate Of the divided areas RA2 to RD2 in which the second main light receiving portion 112 'is divided into four, the divided area RA located diagonally to the divided area RC2 that generates the output signal C2.
2 generates an output signal A2.

The divided area RA of the first main light receiving portion 111 '
1 and RD1 are obtained by dividing the divided area Ra1 in FIG.
It can be obtained by dividing into two by 1S. First main light receiving section 1
The divided region RB1 and RC1 of 11 ′ can be obtained by dividing the divided region Rb1 of FIG. 14 into two by the sub-partition line 111S. The divided areas RA2 and RD2 of the second main light receiving section 112 '
Can be obtained by dividing the divided area Ra2 in FIG. 14 into two parts by the sub-partition line 112S. The divided areas RB2 and RC2 of the second main light receiving portion 112 'can be obtained by dividing the divided area Rb2 of FIG. 14 by the sub-divided line 112S. Therefore, a1 = A1 + D1, a2 = A2 + D2, b1 = B
1 + C1, b2 = B2 + C2.

In an optical disk such as a compact disk (CD) or a phase-change optical disk that uses a change in the amount of light as a signal, a reproduced signal RF is expressed as RF = A1 + B1 + C1 +
It can be obtained from D1 + A2 + B2 + C2 + D2.

First and second main light receiving sections 111 ′ and 11 ′
By dividing 2 ′ into four, the discrimination signal LG indicating whether the focal point of the laser beam from the objective lens 4 is located on the land of the optical disc 80 or on the groove is LG = A1 + B1
-C1-D1- (A2 + B2-C2-D2).

FIG. 16 is a characteristic diagram showing the characteristics of the discrimination signal LG obtained from the output signals of the first and second main light receiving sections divided into four parts. This characteristic diagram shows the characteristics of the tracking error signal and the discrimination signal LG when the focus of the laser light is positioned on the signal surface of the optical disk 80 and the focus of the laser light crosses the track. On the horizontal axis of this characteristic diagram, the case where the focus is located on the groove is represented as 0 and 1, and the case where the focus is located on the land is 0.5.
And the deviation of the focus from the groove is defined as the detrack amount.

In the characteristic diagram of FIG. 16, the determination signal LG
Is a signal whose phase is shifted by 90 degrees from the tracking error signal. This discrimination signal LG can be used when discriminating whether the laser beam is located on the land or on the groove at the time of seeking or the like.

FIG. 17 is a schematic configuration diagram showing a second embodiment of the optical pickup according to the present invention. The optical pickup 150 includes a semiconductor laser 2, a collimator lens 3, a diffraction grating 9, a beam splitter 1, an objective lens 4, a Wollaston prism 11, a condenser lens 6, a prism 8, a photo detector 17, a lens holder 4H, and a focusing actuator serving as a first actuator.
It has an actuator 4F and a tracking actuator 4T as a second actuator. FIG.
In the optical pickup 150 of No. 7, the same components as those of the optical pickup 50 of FIG. 4 are denoted by the same reference numerals, and the description of the same components will be appropriately omitted.

The semiconductor laser 2 outputs a linearly polarized laser beam based on the drive signal SL and supplies it to the collimator lens 3. The collimator lens 3 converts the laser light from the semiconductor laser 2 into parallel light and supplies the parallel light to the diffraction grating 9. The diffraction grating 9 separates the laser beam from the collimators 3 into a main laser beam and first and second sub-laser beams and supplies the laser beam to the beam splitter 1. The beam splitter 1 supplies the laser light from the diffraction grating 9 to the objective lens 4.

The objective lens 4 irradiates a track of the optical disk 81 with a main laser beam, irradiates one of the guide areas on both sides of the track with a first sub-laser light, and irradiates the other with the first sub-laser light. The guide region is irradiated with the second sub-laser light. Further, the laser beam reflected by the optical disk 81 is returned to the beam splitter 1. Optical disk 81
Is a magneto-optical disk, for example. Beam splitter 1
Supplies the laser light from the objective lens 4 to the Wollaston prism 11.

The Wollaston prism (WP) 11 converts the main laser beam from the beam splitter 1 into a first main split laser beam and second and third main split laser beams sandwiching the first main split laser beam. And the light is supplied to the prism 8 via the condenser lens 6. Further, the first sub-laser light from the beam splitter 1 is divided into a first sub-divided laser light and second and third sub-divided laser lights sandwiching the first sub-divided laser light, and are condensed. The light is supplied to the prism 8 via the lens 6. Further, the second sub-laser light from the beam splitter 1 is split into a fourth sub-divided laser light and fifth and sixth sub-divided laser lights sandwiching the fourth sub-divided laser light, and are condensed. The light is supplied to the prism 8 via the lens 6.

The prism 8 allows the laser light from the condenser lens 6 to pass therethrough and divides the laser light into two, and supplies the laser light to the photodetector 17. The photodetector 17 receives the laser beam from the prism 8 at a light receiving unit and generates an output signal.

FIG. 18 is an explanatory diagram showing how the Wollaston prism 11 divides the laser beam from the beam splitter 1 into three. The laser light from the beam splitter 1 has a main laser light generated by the diffraction grating 9 and first and second sub-laser lights sandwiching the main laser light. The Wollaston prism 11 couples the main laser beam with the first and second
Is supplied to the condenser lens 6 after being divided into three.

FIG. 19 shows the optical pickup 150 of FIG.
FIG. 3 is a schematic configuration diagram illustrating a light receiving unit included in the photodetector 17 of FIG. The photodetector 17 includes first to sixth main light receiving units 211 to
216 and first to twelfth sub-light receiving units 221 to 232. Main light receiving units 211 to 216 and sub light receiving unit 221
To 232, laser beam spots are formed, and a total of 18 beam spots are formed.

The prism 8 converts the first main split laser beam into two beams.
One of the split laser beams is supplied to the first main light receiving unit 211 and the other is supplied to the second main light receiving unit 21.
Feed to 2. Further, one of the two laser beams generated by dividing the second main divided laser beam into two is supplied to the third main light receiving section 2.
13 and the other to the fourth main light receiving section 214. Further, one of the two laser beams generated by dividing the third main split laser beam into two is supplied to the fifth main light receiving portion 215 and the other is supplied to the sixth main light receiving portion 216.

The prism 8 converts the first sub-divided laser beam into two beams.
One of the two divided laser beams is supplied to the first sub-light receiving unit 221 and the other is supplied to the second sub-light receiving unit 22.
Feed to 2. Further, one of the two laser beams generated by dividing the second sub-divided laser beam into two is input to the fifth sub-light receiving unit 2.
25, and the other is supplied to the sixth sub-light receiving unit 226. In addition, one of the two laser beams generated by dividing the third sub-divided laser beam into two is supplied to the seventh sub-light receiving unit 227 and the other is supplied to the eighth sub-light receiving unit 228.

The prism 8 converts the fourth sub-divided laser beam into two beams.
One of the split laser beams is supplied to the third sub-light receiving unit 223 and the other is supplied to the fourth sub-light receiving unit 22.
4 Further, one of the two laser beams generated by dividing the fifth sub-divided laser beam into two is used as the ninth sub-light receiving unit 2.
29 and the other is supplied to the tenth sub-light receiving section 230. Further, one of the two laser beams generated by dividing the sixth sub-divided laser beam into two is used as an eleventh sub-light receiving portion 23.
1 and the other is supplied to the twelfth sub-light receiving section 232.

Among the light receiving sections shown in FIG. 19, the first and second main light receiving sections 211 and 212 and the first to fourth sub light receiving sections 2
21 to 224 have a configuration similar to the light receiving section shown in FIG. Main light receiving units 211 and 212 and sub light receiving units 221-222
Reference numeral 4 corresponds to the main light receiving units 111 'and 112' and the sub light receiving units 121 to 124 in FIG. 15, respectively, and a description thereof will be omitted.

FIG. 20 shows the optical pickup 1 shown in FIG.
FIG. 1 is a schematic block diagram showing an embodiment of a recording / reproducing apparatus having 50. The recording / reproducing apparatus 190 includes a modulation circuit 10, a magnetic head 20, a magnetic head drive circuit 25, a motor 30, a motor drive circuit 35, a phase compensation circuit 40, an amplifier circuit 42, an optical pickup 150
, An amplification circuit (head amplifier) 152, a laser drive circuit 155, a generation circuit 160, an information detection circuit (detection circuit) 165, a control circuit 170, and a recording / reproduction switching circuit 175. The recording / reproducing device 190 records information on the rotating optical disk 81 or reproduces recorded information from the rotating optical disk 81.

The control circuit 170 is a controller that controls the entire recording / reproducing apparatus 190, and is constituted by, for example, a microcomputer. The control circuit 190 includes a motor drive circuit 35, a laser drive circuit 15
5, optical pickup 150, phase compensation circuit 40, generation circuit 160, information detection circuit 165, magnetic head drive circuit 2
5. Control the modulation circuit 10 and the like.

The optical pickup 150 irradiates a laser beam LB to a recording position of the optical disk 81 during recording, and irradiates a laser beam LB to a reproduction position of the optical disk 81 during reproduction. However, the power of the laser beam LB is larger during recording than during reproduction.

The modulation circuit 10 receives an input signal Sin indicating information to be recorded at the time of recording, and the input signal Sin
Is modulated by an EFM (Eight to Fourteen Modulation) modulation method or the like to generate an output signal S10, and the output signal S10 is supplied to the magnetic head drive circuit 25.

The magnetic head drive circuit 25 includes the modulation circuit 10
Is supplied to the magnetic head 20 based on the output signal S10.

The magnetic head 20 includes a magnetic head driving circuit 2
5 excites the core with the exciting current S25, generates a line of magnetic force MB corresponding to the input signal Si from the core, and applies a magnetic field corresponding to the input signal Si to the beam irradiation location of the optical disk 81.

The motor 30 is constituted by, for example, a spindle motor, and rotates the optical disk 81 at a predetermined rotation speed. The motor 30 rotates the optical disk 81 so that the linear velocity becomes constant, for example.

The motor drive circuit 35 supplies drive power to the motor 30 to drive the motor 30. The motor drive circuit 35 may perform rotation control of the motor 30 by PWM (Pulse Width Modulation) control, and may perform PLL (Ph
Rotation control may be performed by ase Locked Loop) control.

The laser driving circuit 155 includes a control circuit 170
, The semiconductor laser 4 in the optical pickup 150 is driven by the drive signal SL, and the semiconductor laser 4 outputs a laser beam LB. The laser drive circuit 155 outputs the laser beam L during recording.
The output power of B is made larger than that during reproduction.

The optical pickup 150 receives the laser beam L
B is supplied to the track of the optical disk 81 and the optical disk 8
One recording location or reproduction location is irradiated. At the time of recording, the temperature of the irradiated portion of the optical disk 81 becomes high enough to exceed the Curie point of the recording film, the irradiated portion is magnetized by the magnetic field applied from the magnetic head 20, and the input signal Sin is recorded.

The amplification circuit (head amplifier) 152 amplifies the output signal output from the light receiving portion of the photodetector 17 in the optical pickup 150 and supplies the output signal to the generation circuit 160.

The generation circuit 160 generates a reproduction signal RF (MO), a focus error signal FE, a tracking error signal TE, and a discrimination signal LG based on the signal from the amplification circuit 152. The generation circuit 160 outputs the determination signal LG to the phase compensation circuit 40, the information detection circuit 165, and the control circuit 17
0 and so on.

The phase compensation circuit 40 generates a compensation signal by compensating (phase compensation and / or frequency compensation) the focus error signal FE and the tracking error signal TE, and supplies this compensation signal to the amplifier circuit 42.

The amplification circuit 42 outputs the focus error signal FE
Is supplied to the focusing actuator 4F in the optical pickup 150. The focusing actuator 4F moves the objective lens 4 in the focus direction based on the drive signal Sfe (ie, a signal amplified by compensating the focus error signal FE). The amplifying circuit 42 supplies the drive signal Ste obtained by amplifying the compensation signal of the tracking error signal TE to the tracking actuator 4 in the optical pickup 150.
Supply to T. The tracking actuator 4T is
The objective lens 4 is moved in the disk radial direction based on the drive signal Ste (that is, a signal amplified by compensating the tracking error signal TE).

The information detection circuit 165 is supplied with the reproduction signal MO from the generation circuit 160, demodulates the reproduction signal MO, reproduces the recorded information on the optical disk 81, and outputs the reproduced recorded information as the output signal So. .

The recording / reproduction switching circuit 175 generates a switching signal for switching between recording and reproduction of the recording / reproducing device 190, and transmits this switching signal to the control circuit 170, the information detection circuit 16
5, the modulation circuit 10, the magnetic head drive circuit 25, and the like.

When the switching signal indicating the time of reproduction is supplied, the modulation circuit 10 outputs the output signal S10 to the magnetic head driving circuit 2.
Stop feeding to 5. When the switching signal indicating the reproduction time is supplied, the magnetic head drive circuit 25 stops supplying the exciting current S25 to the magnetic head 20. On the other hand, the information detection circuit 165 stops generating the output signal So when the switching signal indicating the recording time is supplied. Further, the control circuit 170 controls the laser output power of the optical pickup 150 according to the switching signal. The recording / reproducing device 190 generates a focus error signal FE and a tracking error signal TE having good S-shaped characteristics from the output signal of the optical pickup 150 and controls the position of the objective lens 4 in the optical pickup 150, so that the reliability of the reproduced information is improved. It is possible to increase the quality.

FIG. 21 is a schematic configuration diagram showing a first modification of the light receiving section shown in FIG. The light receiving section shown in FIG. 21 has a configuration similar to that of the light receiving section shown in FIG. 19, and third and fourth main light receiving sections 213 and 214 are connected to form a main light receiving section 2134, and fifth and sixth light receiving sections are formed. Main light receiving section 21
5, 216 are connected to form a main light receiving section 2156. In the light receiving unit of FIG. 21, the same components as those of the light receiving unit of FIG. 19 are denoted by the same reference numerals, and the description of the same components will be omitted as appropriate.

The first main light receiving section 211 is divided into four equal parts, and the four divided areas generate output signals A1 to D1.
The second main light receiving unit 212 is divided into four equal parts, and the four divided areas generate output signals A2 to D2. Main light receiving section 21
34 generates an output signal I. The main light receiving section 2156 is
Generate an output signal J.

The first sub light receiving section 221 generates an output signal E1. The second sub-light receiving section 222 generates an output signal E2. The third sub-light receiving unit 223 generates an output signal F1. The fourth sub-light receiving unit 224 generates an output signal F2.

Main light receiving sections 211, 212, 2134, 21
56 output signals A1 to D1, A2 to D2, I, J,
Output signals E1, E2, F of the sub-light receiving units 221 to 224
1 and F2 are supplied to the generation circuit 160 via the amplification circuit 152. Based on the signal from the amplifying circuit 152, the generating circuit 160 determines whether or not the reproduced signal RF (MO) including the focus error signal FE, the tracking error signal TE, the magneto-optical signal, and the pit is present, using the equation shown in FIG. A corresponding reproduction signal RF (Pit), a discrimination signal LG, and the like are generated.

FIG. 22 is a schematic configuration diagram showing a second modification of the light receiving section shown in FIG. The light receiving unit illustrated in FIG. 22 has a configuration similar to the light receiving unit illustrated in FIG.
The fifth to twelfth sub light receiving units 225 to 232 are used instead of the fourth sub light receiving units 221 to 224. In the light receiving unit of FIG. 22, the same components as those of the light receiving unit of FIG. 21 are denoted by the same reference numerals, and the description of the same components will be appropriately omitted.

The fifth sub light receiving section 225 generates an output signal E5. The sixth sub light receiving section 226 generates an output signal E6. The seventh sub-light receiving unit 227 generates an output signal E7. The eighth sub-light receiving unit 228 generates an output signal E8. The ninth sub-light receiving unit 229 generates an output signal F5. The tenth sub light receiving unit 230 generates an output signal F6. The eleventh sub light receiving unit 231 generates an output signal F7. The twelfth sub light receiving section 232 generates an output signal F8.

Main light receiving sections 211, 212, 2134, 21
56 output signals A1 to D1, A2 to D2, I, J,
Output signals E5 to E8 and F5 of the sub-light receiving units 225 to 232
To F8 are supplied to the generation circuit 160 via the amplification circuit 152. Based on the signal from the amplifying circuit 152, the generating circuit 160 determines the focus error signal FE, the tracking error signal TE, the reproduction signal RF (MO) composed of a magneto-optical signal, and the presence or absence of a pit using the equation shown in FIG. A corresponding reproduction signal RF (Pit), a discrimination signal LG, and the like are generated.

FIG. 23 shows the optical pickup 150 of FIG.
FIG. 9 is a schematic configuration diagram illustrating another example of a light receiving unit included in the photodetector 17 of FIG. The photodetector 17 includes first to sixth main light receiving units 311 to 316 and first to twelfth sub light receiving units 321 to 321.
332. Each of the main light receiving sections 311 to 316 and the sub light receiving sections 321 to 332 has a beam spot formed by laser light, and a total of 18 beam spots are formed.

The main light receiving sections 311 to 316 and the sub light receiving sections 321 to 332 in FIG.
1 to 216 and the sub-light receiving units 221 to 232, respectively, and a description thereof will be omitted as appropriate. In the light receiving unit of FIG. 23, the side beam separation direction and the Wollaston prism 1
1, the laser light is separated in the vertical and horizontal directions of the main light receiving portion and the sub light receiving portion. In contrast, FIG.
The light receiving unit 9 has a configuration in which the side beam separation direction and the laser beam separation direction by the Wollaston prism 11 are diagonal to the main light receiving unit and the sub light receiving unit.

FIG. 24 is a schematic configuration diagram showing a modification of the light receiving section shown in FIG. The light receiving unit illustrated in FIG. 24 has a configuration similar to the light receiving unit illustrated in FIG. 23, and the first, fifth, and seventh sub light receiving units 321, 325, and 327 are connected to form a sub light receiving unit 3257. The second, sixth, and eighth sub-light receiving units 322, 326, and 328 are connected to form a sub-light receiving unit 3268. Also, the third, ninth and first
The first sub-light receiving portion 323, 329, 331 is connected to form a sub-light receiving portion 3291, and the fourth, tenth, and twelfth sub-light receiving portions 324, 330, 332 are connected to the sub-light receiving portion 3291.
302.

The first main light receiving section 311 is divided into four equal parts, and the four divided areas generate output signals A1 to D1.
The second main light receiving unit 312 is divided into four equal parts, and the four divided areas generate output signals A2 to D2. The third main light receiving unit 313 generates an output signal I1. The fourth main light receiving section 314 generates an output signal I2. Fifth main light receiving section 3
15 generates an output signal J1. Sixth main light receiving section 31
6 generates an output signal J2.

The sub light receiving section 3257 generates an output signal E1. The sub light receiving unit 3268 generates an output signal E2.
The sub light receiving unit 3291 generates the output signal F1. The sub light receiving section 3302 generates the output signal F2.

Each output signal A1 of the main light receiving sections 311 to 316
D1, A2 to D2, I1, I2, J1, J2 and the output signals E1, E2, F1, F2 of the sub-light receiving units 3257, 3268, 3291, 3302 are supplied to the generation circuit 160 via the amplification circuit 152. Is done. Based on the signal from the amplification circuit 152, the generation circuit 160 determines whether or not there is a reproduction signal RF (MO) including a focus error signal FE, a tracking error signal TE, a magneto-optical signal, and a pit by using the equations shown in FIG. A corresponding reproduction signal RF (Pit), a discrimination signal LG, and the like are generated.

FIG. 25 is an explanatory view showing a modified example of the prism 8, and the above-described optical pickups 50, 50 ', 15
At 0, a prism 18 may be used instead of the prism 8. FIG. 25 shows how the prism 18 splits the laser light from the condenser lens 6. The laser light from the condenser lens 6 passes on the ridge 18M of the prism 18 and is divided into two in the vertical direction of the ridge 18M, and
7 is supplied.

In the recording / reproducing apparatuses 90 and 190, since the offset of the focus error signal FE between the land and the groove is small, it is not necessary to adjust the focus offset when switching the track from one of the land and the groove to the other. it can. Further, the tracking error signal T
When generating E, a differential push-pull method (DPP method) can be used. Further, by generating the discrimination signal LG, the focal position of the laser beam can be detected, and the seek can be performed at high speed. The above embodiment is an exemplification of the present invention, and the present invention is not limited to the above embodiment.

[0126]

As described above, in the present invention, the track direction in the prism to which the laser light reflected by the optical disk is supplied and the ridge line are approximately 45 degrees or approximately 135 degrees.
The two laser beams, which are formed at an angle of degree and pass through the ridge line of the prism and are divided into two in the vertical direction of the ridge line, are received by the first and second main light receiving portions of the photodetector. It is possible to obtain a tracking error signal and a focus error signal having an appropriate S-shaped characteristic from the output signal of the photodetector.
As described above, according to the present invention, it is possible to provide a recording / reproducing device capable of obtaining a tracking error signal and a focus error signal having good S-shaped characteristics, and an optical pickup usable in the recording / reproducing device. it can.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an optical pickup compared with the present invention.

FIG. 2 is a first explanatory diagram showing a relationship between laser light reflected by a beam splitter 1 and supplied to a prism 28 and a ridge 28Z of the prism 28 in the optical pickup 51 of FIG.

FIG. 3 is a second explanatory diagram showing a relationship between a laser beam reflected by the beam splitter 1 and supplied to the prism 28 and a ridgeline 28Z of the prism 28 in the optical pickup 51 of FIG.

FIG. 4 is a schematic configuration diagram showing a first embodiment of an optical pickup according to the present invention.

FIG. 5 is an explanatory diagram showing how a prism 8 divides laser light from a condenser lens 6;

6 is an explanatory diagram showing a relationship between a laser beam reflected by a beam splitter 1 and supplied to a prism 8 and a ridge line 8Z of the prism 8 in the optical pickup 50 of FIG.

FIG. 7 is a schematic configuration diagram showing a light receiving section included in the photodetector 7 of the optical pickup 50 of FIG.

FIG. 8 is an explanatory diagram showing the relationship between the shape of a beam spot formed on the first and second main light receiving portions and the distance between the objective lens 4 and the optical disk 80.

FIG. 9 is a characteristic diagram showing characteristics of a focus error signal FE ′ (= a1−b1) obtained from output signals of the first and second main light receiving units.

FIG. 10 shows a focus error signal FE (= a1-b1-a2 +) obtained from output signals of the first and second main light receiving units.
It is a characteristic view which shows the characteristic of b2).

FIG. 11 shows a tracking error signal TE (= a1 + b1-a2) obtained from output signals of the first and second main light receiving units.
It is a characteristic view which shows the characteristic of -b2).

FIG. 12 is a schematic block diagram showing an embodiment of a recording / reproducing apparatus having the optical pickup 50 shown in FIG.

FIG. 13 is a schematic configuration diagram showing a modified example of the optical pickup 50 included in the recording / reproducing device 90 of FIG.

FIG. 14 is a schematic configuration diagram illustrating a light receiving unit included in a photodetector 7 ′ of the optical pickup 50 ′ of FIG.

FIG. 15 is a schematic configuration diagram showing a modified example of the light receiving unit shown in FIG.

FIG. 16 is a characteristic diagram illustrating characteristics of a discrimination signal LG obtained from output signals of the first and second main light receiving units divided into four parts.

FIG. 17 is a schematic configuration diagram showing a second embodiment of the optical pickup according to the present invention.

FIG. 18 is an explanatory diagram showing how the Wollaston prism 11 divides the laser beam from the beam splitter 1 into three in the optical pickup 150 of FIG.

19 is a photodetector 1 of the optical pickup 150 shown in FIG.
FIG. 7 is a schematic configuration diagram illustrating a light receiving unit included in 7.

20 is a schematic block diagram showing an embodiment of a recording / reproducing apparatus having the optical pickup 150 shown in FIG.

21 is a schematic configuration diagram illustrating a first modification of the light receiving unit illustrated in FIG.

FIG. 22 is a schematic configuration diagram showing a second modified example of the light receiving section shown in FIG.

23 is a photodetector 1 of the optical pickup 150 shown in FIG.
FIG. 9 is a schematic configuration diagram illustrating another example of the light receiving unit included in 7.

24 is a schematic configuration diagram showing a modified example of the light receiving unit shown in FIG.

FIG. 25 is an explanatory view showing a modification of the prism 8;

[Explanation of symbols]

1. Beam splitter 2. Semiconductor laser (laser),
3 ... Collimator lens, 4 ... Objective lens, 4H ... Lens holder, 4F ... Focusing actuator (first
, 4T tracking actuator (second actuator), 8, 18, 28 ... prism, 8M, 18M, 28Z ... ridgeline, 6 ... condenser lens,
7, 7 ', 17 photodetector, 9 diffraction grating, 11 Wollaston prism, 30 motor, 35 motor drive circuit, 40 phase compensation circuit, 42 amplifier circuit, 50, 5
0 ', 51, 150 ... Optical pickup, 52, 152 ...
Amplifier circuits (head amplifiers), 55, 155 laser drive circuits, 60, 160 generation circuits, 65, 165 information detection circuits (detection circuits), 70, 170 control circuits, 80,
81 optical disk, 90, 190 recording / reproducing device, 10
1, 111, 111 ′, 211, 311... First main light receiving portion, 101Bm, 102Bm.
M, 102M, 111M, 112M ... main dividing line, 10
2, 112, 112 ′, 212, 312... Second main light receiving portion, 111S, 112S.
321, a first sub-light receiving section, 122, 222, 322, a second sub-light receiving section, 123, 223, 323, a third sub-light receiving section, 124, 224, 324, a fourth sub-light receiving section, 175
... Recording / reproducing switching circuit, 225,325 ... Fifth sub-light receiving unit, 226,326 ... Sixth sub-light receiving unit, 227,327
... Seventh sub-light receiving portion, 228, 328 ... Eighth sub-light receiving portion,
229, 329: ninth sub-light receiving portion, 230, 330 ... tenth sub-light receiving portion, 231, 331 ... eleventh sub-light receiving portion,
232, 332... Twelfth sub-light receiving section, 2134, 215
6. Main light receiving section, 3257, 3268, 3291, 330
2: Sub-light receiving section, FE: Focus error signal, G: Groove, L: Land, LG: Discrimination signal, RF: Reproduction signal, R
A1 to RD1, RA2 to RD2, Ra1, Ra2, Rb
1, Rb2: divided area, TE: tracking error signal.

Continued on the front page F term (reference)

Claims (21)

[Claims] A laser for outputting a laser beam; an objective lens for condensing and supplying a laser beam from the laser to a track of an optical disc on which lands and / or grooves are formed; A prism that supplies the laser light through the objective lens, divides the supplied laser light into two, and a photodetector to which both laser lights generated by the division by the prism are supplied; The track direction of the prism to which the laser light reflected by the optical disc is supplied and the ridge line of the prism form an angle of about 45 degrees or about 135 degrees, and the laser light reflected by the optical disc is reflected by the prism. A first main light receiving unit that passes over the ridge line and is divided into two in the vertical direction of the ridge line, and the photodetector receives one of the two laser beams. A second main light receiving portion for receiving the other light, wherein the first and second main light receiving portions are divided into two equal parts or substantially two equal parts by a main dividing line. An optical pickup in which a direction and a column direction in which the two laser beams are arranged are perpendicular or substantially perpendicular. 2. A collimator lens for converting a laser beam from the laser into parallel light, and a laser beam from the collimators and a first laser beam.
And a diffraction grating that separates the laser light from the diffraction grating into a second auxiliary laser light; and a beam splitter that supplies the laser light from the diffraction grating to the objective lens. A main laser beam is irradiated, one of the guide regions on both sides of the track is irradiated with the first sub laser beam, and the other guide region is irradiated with the second sub laser beam. Returning the laser light reflected by the optical disc to the beam splitter, the beam splitter supplying the laser light from the objective lens to the prism, and the photodetector comprising: The prism further includes a light receiving unit, and the prism splits the main laser light and the first and second sub-laser lights supplied from the beam splitter into two, respectively. Supplying one of the two laser beams generated by dividing the main laser beam into two, to the first main light receiving unit and the other to the second main light receiving unit; One of the two laser beams generated by dividing the laser beam into two is supplied to the first sub-light receiving portion, and the other is supplied to the second sub-light receiving portion. 2. The optical pickup according to claim 1, wherein one of the divided laser beams is supplied to the third sub-light receiving unit and the other is supplied to the fourth sub-light receiving unit. 3. Each of the first and second main light receiving sections includes:
3. The optical pickup according to claim 2, wherein the optical pickup is divided into four equal parts or substantially four equal parts by the main dividing line and a sub dividing line perpendicular or substantially perpendicular to the main dividing line. 4. A Wollaston prism located between the beam splitter and the prism, wherein the Wollaston prism converts the main laser light from the beam splitter into a first main split laser light. A second one sandwiching the first main split laser beam;
And a third main split laser beam is supplied to the prism, and the first sub laser beam from the beam splitter is
A first sub-divided laser beam and second and third sub-divided laser beams sandwiching the first sub-divided laser beam are supplied to the prism, and the second sub-laser from the beam splitter is supplied to the prism. the light,
A fourth sub-divided laser beam and fifth and sixth sub-divided laser beams sandwiching the fourth sub-divided laser beam are supplied to the prism and supplied to the prism. Main light receiving section and the fifth to twelfth
The prism further supplies one of the two laser lights generated by dividing the first main split laser light into two to the first main light receiving part and supplies the other to the first main light receiving part. The second main light receiving portion is supplied to the second main light receiving portion, and one of the two laser lights generated by dividing the second main split laser light into two is supplied to the third main light receiving portion and the other is supplied to the fourth main light receiving portion. And supplies one of the two laser lights generated by dividing the third main split laser beam into two, to the fifth main light receiving section, and the other to the sixth main light receiving section. And supplying one of the two laser beams generated by dividing the first sub-divided laser beam into two, and supplying the other to the second sub-light receiving unit. And one of the two laser lights generated by dividing the second sub-divided laser light into two is The fifth sub-light receiving portion is supplied to the sixth sub-light receiving portion while the other is supplied to the sixth sub-light receiving portion. And the other is supplied to the eighth sub-light receiving unit. Further, one of the two laser lights generated by dividing the fourth sub-divided laser light into two is supplied to the third light receiving unit. The other is supplied to the sub-light receiving unit and the other is supplied to the fourth sub-light receiving unit, and one of the two laser lights generated by dividing the fifth sub-divided laser light into two is supplied to the ninth sub-light receiving unit And the other is supplied to the tenth sub-light receiving unit, and one of the two laser beams generated by dividing the sixth sub-divided laser light into two is supplied to the eleventh sub-light receiving unit 3. The optical pickup according to claim 2, wherein the other is supplied to the twelfth sub-light receiving unit. 5. The third main light receiving section is connected to the fourth main light receiving section, and the fifth main light receiving section is connected to the sixth main light receiving section. 4. The optical pickup according to item 4. 6. The fifth sub-light receiving portion is connected to the seventh sub-light receiving portion, the sixth sub-light receiving portion is connected to the eighth sub-light receiving portion, and The optical pickup according to claim 4, wherein a ninth sub-light receiving unit and the eleventh sub-light receiving unit are connected, and the tenth sub-light receiving unit and the twelfth sub-light receiving unit are connected. 7. The first sub-light receiving unit, the fifth sub-light receiving unit, and the seventh sub-light receiving unit are connected, and the second sub-light receiving unit and the sixth sub-light receiving unit are connected. And the eighth sub-light receiving portion are connected to each other, and the third sub-light receiving portion, the ninth sub-light receiving portion, and the eleventh
And the fourth sub-light receiving unit, the tenth sub-light receiving unit, and the first
5. The optical pickup according to claim 4, wherein the second light receiving section is connected to the second light receiving section. 8. The light receiving device according to claim 2, wherein the first and second main light receiving portions have the same shape, and the first, second, third and fourth sub light receiving portions have the same shape. Optical pickup as described. 9. The optical disc according to claim 1, wherein the optical disc has a land-groove structure in which the land and the groove are formed, a track of the optical disc is one of the land and the groove, and the guide area includes the land and the groove. 3. The optical pickup according to claim 2, which is the other of the grooves. 10. A first apparatus for supplying a focus error signal corresponding to an output signal of the photodetector, and for moving the objective lens in a focus direction perpendicular to a recording surface of the optical disc based on the focus error signal. 2. An actuator, further comprising: a second actuator to which a tracking error signal corresponding to an output signal of the photodetector is supplied, and which moves the objective lens in a radial direction of the optical disc based on the tracking error signal. Optical pickup as described. 11. A laser for outputting a laser beam, an objective lens for condensing and supplying a laser beam from the laser to a track of an optical disc on which lands and / or grooves are formed, and a laser beam reflected by the optical disc. A prism that supplies the laser light through the objective lens, and divides the supplied laser light into two parts; a photodetector to which both laser lights generated by the division by the prism are supplied; A generation circuit that generates a reproduction signal, a focus error signal, and a tracking error signal based on an output signal of the optical disc; a detection circuit that detects recording information of the optical disc based on the reproduction signal; A first actuator for moving an objective lens in a focus direction perpendicular to a recording surface of the optical disc; A second actuator for moving the objective lens in a radial direction of the optical disc based on a racking error signal, and a track direction in the prism to which the laser light reflected by the optical disc is supplied and a ridge line of the prism Means an angle of about 45 degrees or about 135 degrees, the laser light reflected by the optical disk passes through the ridge of the prism, and is divided into two in the vertical direction of the ridge, and the photodetector is A first main light receiving portion for receiving one of the two laser beams and a second main light receiving portion for receiving the other, and the first and second main light receiving portions are divided into two by a main dividing line. The direction of the main division line and the column direction in which the two laser beams are arranged are vertical or substantially vertical, and the generation circuit is configured as follows: ｛(a1-b1) − ( 2-b2)}
Generating the focus error signal based on the value of
The tracking error signal is generated based on the value of {(a1 + b1)-(a2 + b2)} (where a1 is the second main light receiving portion of the two divided regions into which the first main light receiving portion is divided). B1 is an output signal of a divided region on the side opposite to the second main light receiving portion side of the divided regions obtained by dividing the first main light receiving portion; Is an output signal of a divided area on the side of the first main light receiving section of the divided areas obtained by dividing the second main light receiving section, and a2 is a divided signal obtained by dividing the second main light receiving section. (This is an output signal of a divided area of the area opposite to the first main light receiving unit side.) 12. A collimator lens for converting a laser beam from the laser into a parallel beam, and a laser beam from the collimators and a first laser beam.
And a diffraction grating that separates the laser light from the diffraction grating into a second auxiliary laser light; and a beam splitter that supplies the laser light from the diffraction grating to the objective lens. A main laser beam is irradiated, one of the guide regions on both sides of the track is irradiated with the first sub laser beam, and the other guide region is irradiated with the second sub laser beam. Returning the laser light reflected by the optical disc to the beam splitter, the beam splitter supplying the laser light from the objective lens to the prism, and the photodetector comprising: The prism further includes a light receiving unit, and the prism splits the main laser light and the first and second sub-laser lights supplied from the beam splitter into two, respectively. Supplying one of the two laser beams generated by dividing the main laser beam into two, to the first main light receiving unit and the other to the second main light receiving unit; One of the two laser beams generated by dividing the laser beam into two is supplied to the first sub-light receiving portion, and the other is supplied to the second sub-light receiving portion. One of the two laser beams generated by the division is supplied to the third sub-light receiving unit and the other is supplied to the fourth sub-light receiving unit, and the generation circuit generates ｛(a1 + b1) − (a2 + b2). −
The tracking error signal is generated based on the value of γ (E1 + F1-E2-F2)｝ (where E1 is an output signal of the first sub-light receiving unit, and E2 is a signal of the second sub-light receiving unit). 12. The recording / reproducing apparatus according to claim 11, wherein F1 is an output signal of the third sub-light receiving unit, F2 is an output signal of the fourth sub-light receiving unit, and γ is a constant. apparatus. 13. Each of said first and second main light receiving sections is divided into four equal parts or substantially four equal parts by said main dividing line and a sub dividing line perpendicular or substantially perpendicular to said main dividing line. The generation circuit outputs a discrimination signal indicating whether the track is the land or the groove, by the following formula: ｛(A1 + B1-C1-D
1)-(A2 + B2-C2-D2)} (where D1 is the second main light receiving unit side of the divided region into which the first main light receiving unit is divided into four). A1 is an output signal of the divided region on the side of the second sub-light receiving unit in the two divided regions, and A1 is the second sub-light receiving unit of the two divided regions on the side of the second main light receiving unit. B1 is an output signal of a divided region on the opposite side to the side, and B1 is located in a diagonal direction of a divided region for generating the output signal D1 among divided regions obtained by dividing the first main light receiving portion into four. C1 is an output signal of a divided region which is located in a diagonal direction of a divided region for generating the output signal A1 among divided regions obtained by dividing the first main light receiving portion into four. B2 is the first main light receiving unit side of the divided area obtained by dividing the second main light receiving unit into four. And C3 is an output signal of a divided area on the side of the third sub-light receiving unit in the two divided areas.
Is an output signal of a divided area of the two divided areas on the first main light receiving section side opposite to the third sub-light receiving section side, and D2 is an output signal of the second main light receiving section. Among the four divided regions, the output signal is a divided region that is located diagonally to the divided region that generates the output signal B2, and A2 is the divided region in which the second main light receiving unit is divided into four. 13. The recording / reproducing apparatus according to claim 12, wherein the output signal is an output signal of a divided area located in a diagonal direction of the divided area that generates the output signal C2. 14. A Wollaston prism located between the beam splitter and the prism, wherein the Wollaston prism converts the main laser light from the beam splitter into a first main split laser light. A second one sandwiching the first main split laser beam;
And a third main split laser beam is supplied to the prism, and the first sub laser beam from the beam splitter is
A first sub-divided laser beam and second and third sub-divided laser beams sandwiching the first sub-divided laser beam are supplied to the prism, and the second sub-laser from the beam splitter is supplied to the prism. the light,
A fourth sub-divided laser beam and fifth and sixth sub-divided laser beams sandwiching the fourth sub-divided laser beam are supplied to the prism and supplied to the prism. Main light receiving section and the fifth to twelfth
The prism further supplies one of the two laser lights generated by dividing the first main split laser light into two to the first main light receiving part and supplies the other to the first main light receiving part. The second main light receiving portion is supplied to the second main light receiving portion, and one of the two laser lights generated by dividing the second main split laser light into two is supplied to the third main light receiving portion and the other is supplied to the fourth main light receiving portion. And supplies one of the two laser lights generated by dividing the third main split laser beam into two, to the fifth main light receiving section, and the other to the sixth main light receiving section. And supplying one of the two laser beams generated by dividing the first sub-divided laser beam into two, and supplying the other to the second sub-light receiving unit. And one of the two laser lights generated by dividing the second sub-divided laser light into two is The fifth sub-light receiving portion is supplied to the sixth sub-light receiving portion while the other is supplied to the sixth sub-light receiving portion. And the other is supplied to the eighth sub-light receiving unit. Further, one of the two laser lights generated by dividing the fourth sub-divided laser light into two is supplied to the third light receiving unit. The other is supplied to the sub-light receiving unit and the other is supplied to the fourth sub-light receiving unit, and one of the two laser lights generated by dividing the fifth sub-divided laser light into two is supplied to the ninth sub-light receiving unit And the other is supplied to the tenth sub-light receiving unit, and one of the two laser beams generated by dividing the sixth sub-divided laser light into two is supplied to the eleventh sub-light receiving unit The other is supplied to the twelfth sub-light receiving unit together with the other.
The recording / reproducing apparatus as described in the above. 15. The third main light receiving section is connected to the fourth main light receiving section, and the fifth main light receiving section and the sixth main light receiving section are connected. 15. The recording / reproducing apparatus according to 14. 16. The fifth sub-light receiving portion is connected to the seventh sub-light receiving portion, the sixth sub-light receiving portion is connected to the eighth sub-light receiving portion, and The recording / reproducing apparatus according to claim 14, wherein a ninth sub-light receiving unit and the eleventh sub-light receiving unit are connected, and the tenth sub-light receiving unit and the twelfth sub-light receiving unit are connected. . 17. The first sub-light receiving unit, the fifth sub-light receiving unit, and the seventh sub-light receiving unit are connected, and the second sub-light receiving unit and the sixth sub-light receiving unit are connected. And the eighth sub-light receiving portion are connected to each other, and the third sub-light receiving portion, the ninth sub-light receiving portion, and the eleventh
And the fourth sub-light receiving unit, the tenth sub-light receiving unit, and the first
The recording / reproducing apparatus according to claim 14, wherein the two sub light receiving units are connected. 18. The light receiving device according to claim 12, wherein the first and second main light receiving portions have the same shape, and the first, second, third, and fourth sub light receiving portions have the same shape. The recording / reproducing apparatus as described in the above. 19. The optical disc of claim 1, wherein the land and the groove are formed on the optical disc, and the track of the optical disc is one of the land and the groove, and the guide area is the land and the groove. 13. The recording / reproducing apparatus according to claim 12, which is the other of the grooves. 20. The optical disk according to claim 1, wherein the optical disk is a phase-change optical disk or a compact disk, and the generation circuit generates the reproduction signal based on a sum of respective output signals of the first and second main light receiving units. Claim 1
2. The recording / reproducing apparatus according to 1. 21. The optical disk, wherein the optical disk is a magneto-optical disk, and wherein the generation circuit includes a sum of output signals of the third and fourth main light receiving units, and a sum of output signals of the fifth and sixth main light receiving units. The recording / reproducing apparatus according to claim 11, wherein the reproduction signal is generated based on a difference from a sum of output signals.