JP2000215490A - Photodetector and optical pickup and optical disk device using the detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make constitution small and simple and also correctly record and reproduce information on various kinds of optical disks. SOLUTION: A photodetector has a plurality of divided light receiving sections 22, 23, 24 and 25 to receive returned light beams that are separated by an optical separating means 31, from the surface of the disk, when light beams from a light source illuminate the signal recording surface of an optial disk. Relative to the returned light beams, more than three sections of the sections 22 to 25 are arranged in the radial direction of the disk and are bisected by a center line along the radial direction. The returned light beams are separated approximately every one quater circle by the means 31. Two one quater circle returned light beams L1 and L2, which are mutually aligned in diagonal line directions, are made incident on the section 22 or the section 23. The other two one quater circle returned light beams L3 and L4 are made incident on the sections 23 and 24 or the sections 24 and 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for irradiating a signal recording surface of an optical disk (hereinafter, referred to as an "optical disk") such as an optical disk, a magneto-optical disk, and a phase change type disk with return light. The present invention relates to an optical pickup and an optical disk device for detecting, and a photodetector used for the optical pickup and the optical disk device.

[0002]

2. Description of the Related Art Conventionally, an optical pickup for reproducing an optical disk is constructed, for example, as shown in FIG. In FIG. 6, an optical pickup 1 includes a light emitting / receiving element 2, a grating 3, and an objective lens 4.

Here, the objective lens 4 is a convex lens, and forms an image of a light beam from the light emitting / receiving element 2 on a desired track on a signal recording surface of the optical disk D that is driven to rotate. Further, the objective lens 4 is supported by a biaxial actuator (not shown) so as to be movable in a biaxial direction, that is, a focus direction and a tracking direction. The light-receiving / emitting element 2 has a known configuration, and includes a light-emitting element and a light-receiving element sealed in a semiconductor package as an integrated optical block, for example, as shown in FIG. In FIG. 7, in the light emitting / receiving element 2, a second semiconductor substrate 2b is mounted on a first semiconductor substrate 2a, and a semiconductor laser element 2c is mounted on the second semiconductor substrate 2b.

On the first semiconductor substrate 2a in front of the semiconductor laser element 2c, a trapezoidal prism 2d having an inclined surface (optical path branch surface) is provided on the semiconductor laser element 2c side. A semi-transmissive film (not shown) as a beam splitter is formed on the branch surface 2e. The prism 2d has a total reflection film (not shown) formed on its upper surface, and a semi-transmissive film (not shown) formed on its lower surface. The prism 2d reflects the light beam emitted from the semiconductor laser element 2c upward by the optical path branch surface, and emits the light beam to the outside. As shown in FIG. 5, the light beam emitted from the light emitting / receiving element 2 is transmitted through the grating 3 to the main beam and the ± 1 beam.
Is split into two side beams composed of the next-order diffracted light, and is incident on the objective lens 4.
(For example, a CD).

[0005] The return light beam reflected by the optical disk D passes through the objective lens 4 to the prism 2 of the light emitting / receiving element 2.
d, and is sequentially reflected by the bottom surface and the top surface of the prism 2d, so that it is emitted below the prism 2d at two places on the bottom surface of the prism 2d.
As shown in FIG. 8, on the upper surface of the first semiconductor substrate 2a, the photodetectors 2f and 2 are located at positions where the main beams emitted from two places on the bottom surface of the prism 2d are received.
g is formed, and photodetectors 2h and 2i are formed at positions where the side beams are received, respectively.

Here, of the photodetectors 2f and 2g, as shown in FIG. 8, the photodetector 2f has three divided lines extending in the vertical direction near the center thereof and a center line in the horizontal direction. , Eight light receiving parts a, b, c, d, i, j,
The photodetector 2g is divided into three light receiving parts e, f, and g by two division lines extending in the vertical direction near the center thereof while being divided into k and l.
The photodetectors 2h and 2i are respectively provided with light receiving sections m and n.
It has. Each of the light receiving sections a, b, c, d, e,
f, g, i, j, k, l, m, n detection signals Sa,
Sb, Sc, Sd, Se, Sf, Sg, Si, Sj, S
Based on k, S1, Sm, and Sn, the reproduction signal RF, the focus error signal FE, and the tracking error signal TE
Is detected. Here, the focus error signal FE is detected by a so-called D-3DF method, and the tracking error signal TE has a wavelength of 78, for example.
The light of 0 nm is detected by the so-called three spot method, and the light of 650 nm, for example, is detected by the so-called phase difference method (DPD method).

[0007]

However, in the photodetector having such a configuration, there is a problem that the shape of each light receiving portion of the photodetector is complicated and the cost is increased. On the other hand, the return light is separated from the optical axis by using the polarization hologram without using the prism 2d, and the return light is divided into four by a plurality of diffraction grating regions, and the divided quarter is divided. There is also known an optical pickup in which a return light beam of a circle is detected by a corresponding light receiving unit and a focus error signal is detected by a so-called Foucault method.

In this case, for example, when reproducing a high-density optical disk, a method of using a light having a wavelength of 650 nm to divide the main beam of the return light into, for example, a half circle and two quarter circles involves a phase difference method. , The characteristic of the detection signal (DPD signal) becomes insufficient.
You have to come up with a way to make use of all the return light of the circle. On the other hand, in combination with the D-3DF method for generating a focus error signal, division of the photodetector becomes very complicated. Furthermore, there is no one that can share a photodetector in correspondence with the three-spot method during CD reproduction.

In view of the above, the present invention provides a photodetector which is small in size and can be easily constructed, and which can correctly record and reproduce a plurality of types of optical discs having different wavelengths and intensities, for example. An object of the present invention is to provide an optical pickup and an optical disk device using the same.

[0010]

According to the first aspect of the present invention, a light beam from a light source is applied to a signal recording surface of an optical disk, and the light beam is separated from a signal recording surface of the optical disk separated by a light separating means. A photodetector having a plurality of light receiving portions divided so as to receive the return light beam, wherein each of the light receiving portions is arranged in three or more in the radial direction of the optical disc with respect to the return light beam, and The return light beam is divided into two by the center line in the radial direction, and the return light beam is separated by approximately 1/4 circle by the light separating means, and two return light beams of two 1/4 circles diagonal to each other are formed into one. This is achieved by a photodetector that is configured to be incident on the light receiving portion and configured so that the other two quarter-circle return light beams are respectively incident on other different light receiving portions.

According to the configuration of the first aspect, the light beam emitted from the light source is focused on the signal recording surface of the optical disk via the light focusing means, and the return light beam from the optical disk is again focused on the light focusing means. , The light is separated in the first direction by the light separating means, and the corresponding light receiving portion of the photodetector, that is, return light of a quarter circle opposed to each other is incident on one light receiving portion, and the other two Return light of 1/4 circle enters another different light receiving unit. Thereby, based on the detection signals from these light receiving sections, a focus error signal is detected by the Foucault method based on the detection signal of any one of the other light receiving sections, and the one Based on the detection signals from the light receiving unit and other different light receiving units, a reproduction signal of the optical disk is detected, and a tracking error signal is detected by the DPD method.

When reproducing another type of optical disk, light receiving portions are provided on both sides in the radial direction of the light receiving portion, so that the light beam emitted from the light source can be split by the light splitting means into the main beam and the two side beams. After being split into beams, the beam is focused on the signal recording surface of the optical disc via the light focusing means, and the return light beam from the optical disc is again separated in the first direction by the light separating means via the light focusing means. Then, the light enters the corresponding light receiving portion of the photodetector, that is, the one light receiving portion and another different light receiving portion and the light receiving portions on both sides. As a result, a focus error signal is detected by the three-spot method based on the detection signals from the light receiving sections on both sides based on the detection signals from these light receiving sections, and D
A tracking error signal is detected by the PD method.

In this case, even when the focus error signal is detected by the three-spot method, the tracking error signal is detected by the DPD method. Will be done by

Further, the light receiving portions on both sides are configured such that the center light receiving portion is simply divided into two along the center line, so that the interval therebetween is relatively narrow, and the entire photodetector is small. It is composed of

According to a second aspect of the present invention, there is provided a light source, a light focusing means for irradiating a light beam emitted from the light source so as to be focused on a signal recording surface of an optical disk, A light separating means disposed between the light receiving / emitting element and the light focusing means, and a plurality of light receiving portions divided so as to receive a return light beam from the signal recording surface of the optical disc separated by the light separating means. And a photodetector having
Each light receiving section of the photodetector is arranged in three or more in the radial direction of the optical disk with respect to the return light beam, and is divided into two by the center line in the radial direction, and the return light beam is separated by the light separating means. Two quarter-circle return light beams that are separated from each other by approximately 1/4 circle and that are diagonal to each other are incident on one light receiving unit, and the other two quarter-circle return light beams are respectively formed. This is achieved by an optical pickup configured to enter another different light receiving unit.

Further, according to the present invention, there is provided a driving means for rotating an optical disc, and irradiating the rotating optical disc with light through a light focusing means, and a signal recording surface from the optical disc. Optical pickup for detecting return light from the optical pickup via the light focusing means, a biaxial actuator for supporting the light focusing means so as to be movable in two axial directions, and a reproduction signal based on a detection signal from the optical pickup. A signal processing circuit, based on a detection signal from the optical pickup, including a servo circuit for moving the light focusing means in two axial directions, the optical pickup, a light source, and a light beam emitted from the light source A light focusing means for irradiating the signal recording surface of the optical disc so as to be focused, a light separating means disposed between the light receiving and emitting element and the light focusing means, A photodetector having a plurality of light receiving portions divided so as to receive a return light beam from the signal recording surface of the optical disc separated by the step, wherein each light receiving portion of the photodetector is a return light beam. With respect to the beam, three or more are arranged in the radial direction of the optical disc, and are divided into two by the center line in the radial direction.
Two quarter-circle return light beams, which are separated from each other by approximately 1/4 circle by the light separating means and are diagonal to each other, are incident on one light receiving portion and return light beams of the other two quarter-circles are provided. The beam
This is attained by an optical disk device having a configuration in which the light is incident on other different light receiving units.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. still,
Since the embodiments described below are preferred specific examples of the present invention, various technically preferred limitations are added.
The scope of the present invention is not limited to these embodiments unless otherwise specified in the following description.

FIG. 1 shows the configuration of an optical disk device incorporating an optical pickup having one embodiment of a photodetector according to the present invention. In FIG. 1, an optical disk device 10 records a signal by irradiating a light beam onto a signal recording surface of a rotating optical disk 11 and a spindle motor 12 as a driving unit for driving the optical disk 11 to rotate.
An optical pickup 20 for reproducing a recording signal by a return light beam from the signal recording surface and a control unit 13 for controlling these are provided. Here, the control unit 13 includes an optical disk controller 14, a signal demodulator 15, and an error correction circuit 1.
6, interface 17, head access control unit 18
And a servo circuit 19.

The optical disk controller 14 controls the drive of the spindle motor 12 at a predetermined rotation speed. The signal demodulator 15 demodulates the recording signal from the optical pickup 20, corrects the error, and sends the signal to an external computer or the like via the interface 17. Thus, an external computer or the like can receive a signal recorded on the optical disk 11 as a reproduction signal.

The head access control unit 18 moves the optical pickup 20 to a predetermined recording track on the optical disk 11, for example, by a track jump or the like. At the moved predetermined position, the servo circuit 19 moves the objective lens held by the biaxial actuator of the optical pickup 20 in the focusing direction and the tracking direction.

FIG. 2 shows the structure of the optical pickup 20. In FIG. 2, the optical pickup 20
Includes a light receiving / emitting element 21, an objective lens 30 as a light focusing means, and a hologram element 31 as a light separating means.

The light emitting / receiving element 21 is formed by integrating two semiconductor laser elements as light sources and a photodetector as a photodetector. Here, the first semiconductor laser element is, for example, 650 for reproducing a high-density optical disk.
In addition to emitting light having a wavelength of nm, the second semiconductor laser device emits light having a wavelength of 780 nm for reproducing an optical disk such as a CD or a CD-R having a different reflectance.

The objective lens 30 is a convex lens and forms an image of a light beam from the light emitting / receiving element 21 on a desired track on a signal recording surface of the optical disk D1 or D2 that is driven to rotate. Further, the objective lens 30 is movably supported in a biaxial direction, that is, a tracking direction and a focus direction, by a biaxial actuator (not shown).

The hologram element 31 includes the light receiving / emitting element 2
The light-emitting / receiving element 21 has two surfaces perpendicular to the optical axis of the light beam from the light-emitting / receiving element 21.
A diffraction grating 32 is formed as a second diffraction grating region on the optical axis of the light beam from the light emitting / receiving element 21. Further, the hologram element 31 has a hologram 33 formed on the optical axis of the light beam from the light emitting element 21 on the first surface (the upper surface in FIG. 3) on the optical disk side.

The hologram 33 is formed as a transmission-type hologram that allows the light beam from the light emitting and receiving element 21 to pass through as it is, and diffracts the return light from the optical disk D as described later. (Described later). Here, as shown in FIG. 2, in the present embodiment, the hologram 33 is divided into two in the inner and outer directions (radial direction) of the optical disc D to form each semicircle.
It is divided into at least two parts in a direction parallel to the tangential direction to form two quarter-circular regions.

For this reason, as shown in FIG. 2, the hologram 33 is divided into a diffraction grating region in a direction parallel to the tangential direction of the optical disk D and in a radial direction of the optical disk D, so that the hologram portion divided into four is formed. The hologram portion is a hologram surface in which the pitch of the unevenness gradually changes. As a result, the hologram 33 has four hologram portions as diffraction grating regions, that is, four １ ／ circular hologram portions 33.
a, 33b, 33c, and 33d, and the hologram sections 33a, 33b, 33c, and 33d have discontinuous spatial frequencies. Further, of the hologram parts 33a, 33b, 33c and 33d, a pair of hologram parts in a diagonal direction,
a and 33c are configured to have the same spatial frequency so as to separate the return light of 1/4 circle at the same separation angle.

Here, the light emitting / receiving element 21 will be described in detail. As shown in FIGS. 3 and 4, the light receiving / emitting element 21 includes a second semiconductor substrate 2 on a first semiconductor substrate 21a.
1b is mounted, and two semiconductor laser elements 21c and 21d as light source units are mounted side by side on the second semiconductor substrate 21b. First semiconductor substrate 2 in front of semiconductor laser elements 21c and 21d (inside in the radial direction of optical disc)
A mirror 21e having an inclined surface (optical path branch surface) on the side of the semiconductor laser element is provided on 1a. Mirror 2
1e reflects the light beams emitted from the semiconductor laser elements 21c and 21d upward and emits the light beams to the outside. The mirror 2 is provided on the semiconductor substrate 21a.
1e, that is, the radial direction of the optical disk D1 or D2, and the center of the optical disk D1 or D2 in the radial direction, that is, the main beam split by the diffraction grating 32 of the hologram element 31 should be incident. Light receiving sections 22, 23, 24, 25 are formed. That is, the divided light receiving units 22, 23, 24, and 25 are provided along the radial direction. In addition, these light receiving sections 23,
On both sides of 24, 25, that is, inside and outside, light receiving portions 26, 27 to which the side beams split by the diffraction grating 32 of the hologram element 31 are incident are formed.
The light receiving units 22 to 27 constitute a plurality of divided light receiving units of the photodetector 28, respectively.

As shown in FIG. 3, the light receiving portions 22 to 25 are arranged in a row in the horizontal direction, and are divided into two parts by a center line in the radial direction. As a result, the light receiving units 22 to 25 are respectively arranged above and below the light receiving units A and B, the light receiving units C and D, the light receiving units E and F, and the light receiving units G and H, respectively.
The light receiving sections 26 and 27 constitute light receiving sections I and J, respectively. Thus, the main beam of the return light of the light beam having the wavelength of 650 nm from the first semiconductor laser element 21c is separated into the light beams L1, L2, L3, and L4 by the hologram parts 33a, 33b, 33c, and 33d of the hologram element 31, respectively.・ It is divided.

Of these, the light beams L1 and L3 are
2, the light beam L2 is applied to the light receiving section 24, and the light beam L
4 enters the light receiving unit 23. Similarly, the main beam of the return light of the light beam having the wavelength of 650 nm from the second semiconductor laser element 21d is separated and divided by the hologram parts 33a, 33b, 33c, 33d of the hologram element 31, and shown in FIG. As described above, the light enters the light receiving units 23, 24, and 25. This is because the diffraction angle of each of the hologram portions 33a, 33b, 33c, and 33d of the hologram 33 increases with respect to light having a longer wavelength. The signals from the light receiving sections A, B, C, D, R, F, G, H, I, and J of the light receiving sections 22 to 27 are respectively amplified by amplifiers (not shown) to generate detection signals Sa, Sb, Sc, Sd, Se, Sf, Sg, S
h, Si, and Sj.

On the basis of the detection signals Sa to Si obtained in this manner, a signal processing circuit (not shown) uses a first semiconductor laser device in the case of a first type of optical disk (ie, a high-density recording optical disk). Based on the light beam from 21c, the reproduced signal RF1 is

(Equation 1) As a result, the focus error signal FE1 is

(Equation 2) And the tracking error signal TE1 becomes a so-called D
By the PD method,

(Equation 3) Generated by

The second type of optical disk (ie, C
In the case of D), based on the light beam from the second semiconductor laser element 21d, the reproduction signal RF2 is

(Equation 4) And the focus error signal FE2 is obtained by the so-called Foucault method,

(Equation 5) And the tracking error signal TE2 is calculated by the so-called three spot method.

(Equation 6) Generated by

The light receiving sections 22 to 27 and the optical pickup 20 according to the present embodiment are configured as described above, and the case where the high-density optical disc D1 is reproduced first will be described. In this case, the semiconductor laser element 21c of the light receiving / emitting element 21 emits light.

As a result, 650 from the light emitting / receiving element 21 can be obtained.
The light beam having a wavelength of nm is divided into a main beam and two side beams by the diffraction grating 32 of the hologram element 31, then passes through the hologram 33, and passes through the objective lens 30.
Thus, the light is focused on the signal recording surface of the optical disc D1. The return light from the optical disk D1 again enters the hologram 33 via the objective lens 30. Here, the return light is transmitted to each of the hologram parts 33a, 33b,
Return light of the main beam is diffracted by 33c and 33d, respectively, and enters the light receiving units 22, 23, and 24 of the photodetector, and return light of the side beam enters the light receiving units 26 and 27 of the photodetector. I do. Thereby, the light receiving unit 22,
Based on the detection signals from 23 and 24, the above equations 1 to 3
As a result, the reproduction signal RF1, the focus error signal FE1, and the tracking error signal T
E1 is generated, and the recorded signal on the optical disk D1 is correctly reproduced.

Next, when reproducing an optical disk D2 such as a CD or CD-R, the semiconductor laser element 21d of the light emitting / receiving element 21 emits light. As a result, the light beam having a wavelength of 780 nm from the light emitting / receiving element 21 is split into a main beam and two side beams by the diffraction grating 32 of the hologram element 31, and then the hologram 33
And is focused by the objective lens 30 on the signal recording surface of the optical disc D2. The return light from the optical disc D2 again enters the hologram 33 via the objective lens 30. Here, the return light is diffracted by each of the hologram parts 33a, 33b, 33c, 33d of the hologram 33, and the return light of the main beam enters the light receiving parts 23, 24, 25 of the photodetector. The return light of the side beam enters the light receiving units 26 and 27 of the photodetector. Accordingly, based on the detection signals from the light receiving units 22, 23, and 24, the optical disc D2
Reproduction signal RF2, focus error signal FE2
Then, the tracking error signal TE2 is generated, and the recording signal on the optical disk D2 is correctly reproduced.

In this case, two types of optical discs D1, D2
Return light from the hologram 33, when diffracted by the hologram 33, has a different diffraction angle based on the difference in frequency and enters the photodetector. In the case of the optical disc D1,
Of the light receiving sections 22, 23, 24, and 25 of the photodetector, return light is incident on the light receiving sections 22, 23, and 24 of the first combination, and in the case of the optical disc D2, light receiving of the second combination is performed. Return light is incident on the sections 23, 24, and 25. Therefore, the light receiving / emitting element 21 is a part of the light receiving units 22, 23, 24, 25, that is, the light receiving units 23, 2 for detecting the return light with respect to the different types of optical disks D1, D2.
4 are used in common, and a part of the light receiving unit 22 is different.
Or 25 will be used additionally.

Further, the side beam is incident on the light receiving portions 26 and 27 on both sides.
Each of the light receiving portions 22 to 25 at the center is configured to have a relatively narrow width since it is only divided into two by the center line in the radial direction. Accordingly, the intervals between the light receiving sections 26 and 27 on both sides are also relatively narrow, and the entire photodetector is compact. This eliminates the need to provide a dedicated photodetector for detecting return light from different types of optical discs D1 and D2.
In both the PD method and the three-spot method, the return light can be detected by the same one photodetector in any of the optical discs D1 and D2, so that the chip area of the photodetector is reduced. The light emitting element 21 is configured to be small, light and at low cost. Thus, the optical pickup 20
The optical disk device 10 is also made compact,
The cost will be reduced.

In the above embodiment, the optical disk D1
In the case of the optical disk D2, the tracking error signal is detected by the DPD method, and in the case of the optical disk D2, the tracking error signal is detected by the three-spot method. The tracking error signal may be detected by a method. Also, conversely,
Also in the case of the optical disk D2, the tracking error signal may be detected by the DPD method. In this case, the diffraction grating 32 for dividing the light beams from the semiconductor laser elements 21c and 21d into a main beam and two side beams becomes unnecessary, and the cost is reduced.

In the above embodiment, the optical disk D1
In the case of, the return light is transmitted to the light receiving sections 22, 23, 24, 2
6, 27, and in the case of the optical disc D2, it is detected by the light receiving sections 23, 24, 25, 26, 27. However, the present invention is not limited to this. The return light may be detected by all the light receiving units, and in the case of the other optical disk, the return light may be detected by some of the light receiving units. Conversely, the return light may be detected by the light receiving units 22, 23, 24, 26, 27 both in the case of the optical disk D1 and in the case of the optical disk D2.

Further, in the above-described embodiment, one semiconductor laser element 21c of the light receiving / emitting element 21 emits a light beam having a wavelength of, for example, 650 nm, and the other semiconductor laser element 21d emits a light beam having a wavelength of, for example, 780 nm. It is configured to emit a beam, but is not limited to this.
For example, both semiconductor laser elements 21c and 21d may be configured to emit light beams having the same wavelength and different intensities. For example, in the optical pickup 20, one semiconductor laser element 21c has a wavelength of 780 nm and emits high-efficiency and high-output light for writing, and the other semiconductor laser element 21d has a wavelength of 780 nm and has a wavelength of 780 nm for reading. May be configured to emit light of low output and low noise.

In this case, for example, at the time of recording and reproduction of a magneto-optical disk, the semiconductor laser device 2 for emitting a light beam
By switching between 1c and 21d, it is possible to use a light beam having an optimum intensity, and since the semiconductor laser elements 21c and 21d are designed to be read-only and write-only, respectively, they have excellent performance and As a result, a low-cost light emitting / receiving element 21 is obtained, and noise during reproduction is reduced. In addition, if the tracking error signal is detected by the DPD method during recording and the tracking error signal is detected by the three-spot method during reproduction, the signal can be recorded / reproduced on / from the groove-shaped optical disk. Tracking can be performed reliably.

Further, in the above embodiment, the case of reproducing a CD and a high-density optical disk as the optical disk has been described. However, the present invention is not limited to this, and the present invention is applicable to the case of recording or reproducing another type of optical disk. Clearly applicable.

[0042]

As described above, according to the present invention, 3
Even when the focus error signal is detected by the spot method, the tracking error signal is detected by the DPD method, and so-called high-density recording optical disk and compact disk are reproduced by one photodetector. In addition, the light receiving portions on both sides are configured such that the center light receiving portion is simply divided into two along the center line, so that the interval therebetween is relatively narrow, and the entire photodetector is configured to be small. You. Thus, according to the present invention, a photodetector which can be configured in a small size and can be easily configured, for example, so that recording and reproduction of a plurality of types of optical discs having different wavelengths, intensities, and the like are correctly performed, An optical pickup and an optical disk device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical disk device incorporating an optical pickup provided with a photodetector according to an embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a configuration of an optical pickup in the optical disk device of FIG.

FIG. 3 is a schematic plan view of a light emitting and receiving element in the optical pickup of FIG. 2;

FIG. 4 is a schematic sectional view of a light emitting unit in the light emitting and receiving element of FIG. 3;

FIG. 5 is a plan view showing the optical disc D2 in the light emitting and receiving element of FIG. 3 during reproduction.

FIG. 6 is a schematic side view showing an example of a conventional optical pickup.

FIG. 7 is an enlarged cross-sectional view showing a configuration of a light receiving / emitting element in the optical pickup of FIG.

FIG. 8 is a plan view of a photodetector in the light emitting and receiving element of FIG. 7;

[Explanation of symbols]

10 optical disk device, 11 optical disk, 1
2 ... Spindle motor, 13 ... Control unit, 14.
..Optical disk drive controller, 15 ... signal demodulator, 16 ... error correction circuit, 17 ... interface, 18 ... head access control unit, 19 ...
・ Servo circuit, 20 ・ ・ ・ Optical pickup, 21 ・ ・
. Light-receiving / emitting elements, 21c, 21d... Semiconductor laser elements (light sources), 22, 23, 24, 25, 26, 27,.
Light receiving unit, 28: photodetector, 30: objective lens,
31 ... light separating means, 32 ... diffraction grating, 33 ...
・ Hologram element, 33a, 33b, 33c, 33d
..Hologram section.

Claims (6)

[Claims] An optical beam from a light source is applied to a signal recording surface of an optical disk, and a plurality of light receiving sections divided so as to receive a return light beam from the signal recording surface of the optical disk separated by an optical separating means are provided. The photodetector, wherein each of the light receiving units, with respect to the return light beam, is arranged in three or more in the radial direction of the optical disk, and is divided into two by the radial center line, the return light beam,
Two quarter-circle return light beams, which are separated from each other by approximately 1/4 circle by the light separating means and are diagonal to each other, are incident on one light receiving portion and return light beams of the other two quarter-circles are provided. The beam
A photodetector characterized in that it is configured to be incident on different light receiving portions. 2. A light source, a light converging means for irradiating a light beam emitted from the light source so as to be focused on a signal recording surface of an optical disc, and disposed between the light receiving / emitting element and the light converging means. And a photodetector having a plurality of light receiving portions divided so as to receive a return light beam from a signal recording surface of the optical disc separated by the light separating means. Each light receiving section of the detector is arranged in three or more radial directions of the optical disk with respect to the return light beam, and is divided into two by the center line in the radial direction. Two quarter-circle return light beams that are separated by a quarter circle and are diagonal to each other are incident on one light receiving unit, and the other two quarter-circle return light beams are respectively transmitted to the other light-receiving units. It is configured to be incident on different light receiving parts The optical pickup, wherein the door. 3. The light separating means has at least two surfaces intersecting with an optical axis, and the first surface on the optical disk side transmits a returning light beam from the optical disk to the optical disk from the light source toward the optical disk. A diffraction grating region separated from the axis and guided to the photodetector, wherein the diffraction grating region of the light separating means is composed of four diffraction grating regions having different diffraction directions for each quarter circle. The optical pickup according to claim 2, wherein 4. A light source-side second surface of the light separating means,
The optical pickup according to claim 2, further comprising a second diffraction grating region that divides light from the light source into a main beam and a side beam. 5. The optical pickup according to claim 2, wherein light receiving portions on both sides for receiving a side beam are disposed on both sides in the radial direction of the light receiving portion. 6. A driving means for driving the optical disc to rotate, and a light irradiating the rotating optical disc through a light focusing means, and detecting a return light from the signal recording surface from the optical disc through the light focusing means. An optical pickup, a biaxial actuator for supporting the light focusing means so as to be movable in two axial directions, a signal processing circuit for generating a reproduction signal based on a detection signal from the optical pickup, and a detection signal from the optical pickup A servo circuit for moving the light focusing means in two axial directions, wherein the optical pickup irradiates a light source and a light beam emitted from the light source so as to be focused on a signal recording surface of the optical disc. A light focusing means, a light separating means provided between the light receiving / emitting element and the light focusing means, and a signal recording surface of an optical disc separated by the light separating means. And a photodetector having a plurality of light receiving portions divided so as to receive the return light beams, wherein each of the light receiving portions of the photodetector has three return light beams in the radial direction of the optical disc. The return light beam is divided into two by a center line in the radial direction, and the return light beam is separated by the light separating means at approximately every 1/4 circle, and the return light beams are returned by two 1/4 circles in a diagonal direction with respect to each other. An optical disk device, wherein a light beam is incident on one light receiving portion, and the other two quarter-circle return light beams are respectively incident on different light receiving portions.