JP2001256657A - Optical pickup device and optical disk device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup device and an optical disk device which uses it, capable of correctly detecting reflected light by an optical disk of two laser beams, even when two semiconductor lasers are used. SOLUTION: The optical pickup device is provided with a first semiconductor laser, generating a laser beam of 650 nm wavelength and a second semiconductor laser, generating a laser beam of 780 nm wavelength, reflected light LB1 by a recording medium of the laser beam of 650 nm wavelength is detected by a first detecting part 811, divided into four parts of a first sensor 81 of a photodetector 8, reflected light by the recording medium of a main beam MLB2 generated from the laser beam of 780 nm wavelength is detected by a second detecting part 812 which is divided into either parts of the first sensor 81 of the photodetector 8, reflected light by the recording medium of a first sub-beam SLB21 generated from the laser beam of 780 nm wavelength is detected by a second sensor 82 of the photodetector 8, and a reflected light by the recording medium of a second sub-beam SLB22 generated from the laser beam of 780 nm wavelength is detected by a third sensor 83 of the photodetector 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical pickup device for recording and / or reproducing a signal on a recording medium using two laser beams having different optical axes, and an optical disk device using the same.

[0002]

2. Description of the Related Art An optical disk having a thickness of about 1.2 mm, such as a CD-ROM, from which information is read using a semiconductor laser is provided. In this type of optical disk, focus servo and tracking servo are performed on a pickup objective lens to irradiate a pit row on a signal recording surface with a laser beam to reproduce a signal.

A CD-R having the same recording density as a CD and capable of recording only once has been put to practical use, and a laser beam having a wavelength of 780 nm is used for recording and reproducing the signal. Further, recently, the recording density for recording a long moving image has been increasing. For example, the same diameter 1 as CD-ROM
DVD-ROMs that record 4.7 Gbytes of information on one side of a 2 cm optical disk are on the market. DVD
-The thickness of the ROM disk is about 0.6 mm.
Information can be recorded.

[0004] Further, it is rewritable and can be rewritten on one side.
A DVD-RAM having a recording capacity of 6 GBytes has also been put to practical use. Further, a magneto-optical recording medium is attracting attention as a rewritable, large storage capacity, and highly reliable recording medium, and has begun to be put into practical use as a computer memory or the like. Standardization of a 6.0 Gbyte magneto-optical recording medium (AS-MO (Advanced Store)).
aged Magneto Optical dis
k) standard), and is about to be put to practical use. Reproduction of signals from this magneto-optical recording medium is performed by irradiating a laser beam to transfer the magnetic domains of the recording layer of the magneto-optical recording medium to the reproducing layer and to detect the transferred magnetic domains only on the reproducing layer. An MSR (Magnetically) for forming a detection window and detecting a magnetic domain transferred from the formed detection window.
(Induced Super resolution) method. A laser beam having a wavelength of 650 nm is used for recording and / or reproducing signals on and from the magneto-optical recording medium.

[0005] In view of these circumstances, CD, C
It is assumed that a DR, a DVD-ROM, a DVD-RAM, and a magneto-optical recording medium coexist, and an optical pickup device capable of compatible reproduction of these optical discs and recording signals on a recordable optical disc is required. Currently CD
An optical pickup device capable of compatible reproduction of -R and DVD has been proposed.

[0006]

However, currently proposed CD-R / DVD compatible pickups are DVD-compatible pickups.
A semiconductor laser for generating a laser beam having a wavelength of 650 nm for reproducing a ROM and recording and / or reproducing on a DVD-RAM, and a semiconductor laser for generating a laser beam having a wavelength of 780 nm for recording and / or reproducing on a CD-R; To be included in one package, the optical axes of the two laser beams are deviated.

As a result, there has been a problem that it is difficult to accurately detect two laser beams reflected by the optical disk with one photodetector. That is, when two laser beams are detected by two photodetectors, the optical axis of one laser beam coincides with the center of one photodetector, but the position of the other photodetector changes with time. And the optical axis of the other laser beam deviates from the center of the other photodetector,
There arises a problem that laser light cannot be detected accurately.

Accordingly, the present invention solves such a problem, and an optical pickup device capable of accurately detecting the reflected light of two laser beams on an optical disk even when two semiconductor lasers are used, and an optical disk device using the same. The purpose is to provide.

[0009]

The invention according to claim 1 is an optical pickup device for recording and / or reproducing signals on a recording medium using a laser beam, comprising: a laser light source; a diffraction grating; And an optical pickup device including a photodetector. The laser light source selectively shifts a first laser light having a first wavelength and a second laser light having a second wavelength different from the first wavelength by shifting the optical axes of the two laser lights. Generate.

The diffraction grating generates a main beam, a first sub-beam, and a second sub-beam from the second laser light among the first and second laser lights generated from the laser light source. Further, the photodetector reflects reflected light of the first laser light from the recording medium and reflected light of the main beam, the first sub-beam, and the second sub-beam generated from the second laser light on the recording medium. And detect. And
The photodetector includes a first sensor, a second sensor, and a third sensor, wherein the first sensor is generated from the reflected light of the first laser light and the second laser light. Detecting a reflected light of the main beam, a second sensor detecting a reflected light of the first sub-beam, a third sensor disposed on an opposite side of the second sensor with respect to the first sensor, Detecting the reflected light of the second sub-beam;

Further, the first sensor includes a first detecting section and a second detecting section.
A first detector that detects reflected light of the first laser light, and a second detector that detects reflected light of the main beam generated from the second laser light. Then, the second detection unit sets the astigmatism such that the peak of the signal calculated by the astigmatism method becomes maximum even when the optical axis of the reflected light of the main beam generated from the second laser light is shifted. The four regions for calculating by the aberration method are divided into regions so as to be changeable.

In the optical pickup device according to the first aspect, the first laser light is used for a recording medium for reproducing a signal by using one laser light, and the first laser light is reflected by the recording medium. Light is detected by a first detector of a first sensor of the photodetector. The second laser light is used for a recording medium for recording or reproducing a signal using three laser lights, and is used to generate a main beam, a first sub-beam, and a second sub-beam generated from the second laser light. The reflected light from the recording medium is the second light from the first sensor of the photodetector.
Detection is performed by the detection unit, the second sensor of the photodetector, and the third sensor of the photodetector. Then, the reflected light of the main beam generated from the second laser light detected by the second detection unit on the recording medium is calculated by the astigmatism method while changing the area, and the signal having the maximum peak is detected. Is done.

Therefore, according to the first aspect of the present invention, even when the optical axis of the main beam generated from the second laser beam is deviated from the center of the second detection unit, focusing by the astigmatism method is performed. Error signal or DPP (Different
ial Push Pull) method can accurately generate a tracking error signal. According to a second aspect of the present invention, there is provided an optical disc device including the optical pickup device according to the first aspect, a first arithmetic circuit, and a second arithmetic circuit.

The first arithmetic circuit changes the four regions based on the optical signals input from the respective regions of the second detector of the photodetector, performs an arithmetic operation by the astigmatism method, and obtains an S at which the peak becomes maximum. Select and output a character curve. The second arithmetic circuit has an S-shaped curve having a maximum peak from the first arithmetic circuit,
A tracking error signal is generated by the DPP method from the optical signal detected by the third sensor and the optical signal detected by the third sensor.

In the optical disk apparatus according to the present invention, the first optical disk device comprises a photodetector.
The first arithmetic circuit performs an arithmetic operation using the optical signal detected by the second detection unit included in the sensor according to the astigmatism method, and selectively outputs the S-shaped curve having the maximum peak. Then, the S-shaped curve having the maximum peak is input to the second arithmetic circuit and used for calculating the tracking error signal by the DPP method together with the optical signals detected by the second sensor and the third sensor of the photodetector. The second arithmetic circuit generates a tracking error signal.

Therefore, according to the second aspect of the present invention, even when the optical axis of the main beam generated from the second laser beam is deviated from the center of the second detecting section, the first arithmetic circuit always operates. Since the S-shaped curve having the maximum peak is selected and output, and the S-shaped curve having the maximum peak is always input to the second arithmetic circuit, an accurate focus error signal by the astigmatism method can be obtained.
And an accurate tracking error signal by the DPP method can be generated.

According to a third aspect of the present invention, there is provided an optical pickup device for recording and / or reproducing a signal on a recording medium using a laser beam, comprising a laser light source, a diffraction grating, and a photodetector. An optical pickup device. The laser light source selectively shifts a first laser light having a first wavelength and a second laser light having a second wavelength different from the first wavelength by shifting the optical axes of the two laser lights. Generate.

The diffraction grating generates a main beam and first and second sub beams from the first and second laser beams generated by the laser light source. The photodetector includes a main beam generated from the first laser beam, a first sub-beam, and a reflected light of the second sub-beam on the recording medium; a main beam generated from the second laser beam; The first sub-beam and the reflected light of the second sub-beam on the recording medium are detected. The photodetector includes a first sensor, a second sensor, a third sensor, and a fourth sensor.
And a fifth sensor, wherein the first sensor is a reflected light of a main beam generated from the first laser light,
The second sensor detects reflected light of the main beam generated from the second laser light, the second sensor detects reflected light of the first sub-beam generated from the first laser light, and the third sensor detects the reflected light of the first sub-beam. The first sensor is disposed on the opposite side of the second sensor with respect to the first sensor, detects reflected light of the second sub-beam generated from the first laser light, and the fourth sensor is generated from the second laser light. Detecting a reflected light of the first sub-beam, wherein the fifth sensor is disposed on the opposite side of the third sensor with respect to the first sensor, and reflects the reflected light of the second sub-beam generated from the second laser light. Detect light.

Further, the first sensor includes a first detection unit and a second detection unit, and the first detection unit detects reflected light of the main beam generated from the first laser light, The detection unit detects reflected light of the main beam generated from the second laser light. Then, the second detection unit sets the peak of the signal calculated by the astigmatism method to be the maximum even when the optical axis of the reflected light of the main beam generated from the second laser light on the recording medium is shifted. In addition, four regions for performing calculations by the astigmatism method are divided so as to be changeable.

In the optical pickup device according to the third aspect, the first laser light is used for a recording medium for recording or reproducing a signal using three laser lights, and is generated from the first laser light. The reflected light of the main beam, the first sub-beam, and the second sub-beam on the recording medium is:
They are respectively detected by the first detection unit of the first sensor of the photodetector, the second sensor of the photodetector, and the third sensor of the photodetector. Further, the second laser light is also used for a recording medium for recording or reproducing a signal using three laser lights, and the main beam, the first sub-beam, and the second sub-beam generated from the second laser light are used. The reflected light from the recording medium is
Each is detected by the second detection unit of the first sensor of the photodetector, the fourth sensor of the photodetector, and the fifth sensor of the photodetector. Then, the reflected light of the main beam generated from the second laser light detected by the second detection unit on the recording medium is:
The signal is calculated by the astigmatism method while changing the area, and the signal having the maximum peak is detected.

Therefore, according to the third aspect of the present invention, even if the optical axis of the main beam generated from the second laser beam is deviated from the center of the second detector, focusing by the astigmatism method is possible. An error signal and a tracking error signal by the DPP method can be accurately generated. According to a fourth aspect of the present invention, there is provided an optical pickup device according to the third aspect, wherein:
An optical disc device includes an arithmetic circuit, a second arithmetic circuit, and a third arithmetic circuit.

The first arithmetic circuit changes the four areas based on the optical signals input from the respective areas of the second detection section of the photodetector and performs an arithmetic operation by the astigmatism method, and the peak at which S becomes the maximum is obtained. Select and output a character curve. Further, the second arithmetic circuit generates a tracking error signal by a DPP method from the optical signal detected by the first detection unit, the optical signal detected by the second sensor, and the optical signal detected by the third sensor. I do.

The third arithmetic circuit calculates the S-shaped curve having the maximum peak from the first arithmetic circuit, the optical signal detected by the fourth sensor, and the D signal from the optical signal detected by the fifth sensor.
A tracking error signal is generated by the PP method. In the optical disc device according to the fourth aspect, the first arithmetic circuit uses the optical signal detected by the second detection unit included in the first sensor constituting the photodetector of the optical pickup device, and the first arithmetic circuit uses astigmatism. Is calculated by the method of
Select and output a character curve. Then, the S-shaped curve having the maximum peak is input to the third arithmetic circuit, and the fourth curve of the photodetector is obtained.
The third arithmetic circuit generates a tracking error signal together with the optical signal detected by the third sensor and the fifth sensor for calculating a tracking error signal by the DPP method. The second arithmetic circuit includes an optical signal detected by the first detector of the first sensor of the photodetector, an optical signal detected by the second sensor, and an optical signal detected by the third sensor. Is used to generate a tracking error signal by the DPP method.

Therefore, according to the fourth aspect of the present invention, even when the optical axis of the main beam generated from the second laser beam is deviated from the center of the second detector, the first arithmetic circuit always operates. The S-curve with the maximum peak is selected and output, and the S-curve with the maximum peak is always input to the third arithmetic circuit.
And an accurate tracking error signal by the DPP method can be generated. As a result, it is possible to accurately access two recording media on which focus servo is performed by the astigmatism method and tracking servo is performed by the DPP method.

According to a fifth aspect of the present invention, there is provided an optical pickup device for recording and / or reproducing a signal on a recording medium using a laser beam, comprising: a laser light source; a polarization plane rotating element; An optical pickup device including a grating and a photodetector. The laser light source selectively shifts a first laser light having a first wavelength and a second laser light having a second wavelength different from the first wavelength by shifting the optical axes of the two laser lights. Generate.

The polarization plane rotation element selectively rotates the polarization plane of the first laser light generated from the laser light source and transmits the first laser light, and transmits the second laser light generated from the laser light source as it is. . The polarization-selective diffraction grating generates a main beam and first and second sub-beams from the second laser light transmitted through the polarization plane rotation element, and generates the first laser light transmitted through the polarization plane rotation element. From the first laser beam and the first and second beams according to the polarization plane of
And a sub-beam of

[0027] The photodetector is a device for reflecting the first laser beam reflected by the recording medium and the main beam, the first subbeam, and the second subbeam generated from the first laser beam. And the reflected light of the main beam, the first sub-beam, and the second sub-beam generated from the second laser light on the recording medium. The photodetector includes a first sensor, a second sensor, a third sensor, a fourth sensor, and a fifth sensor, and
Sensor detects reflected light of the first laser light, reflected light of the main beam generated from the first laser light, and reflected light of the main beam generated from the second laser light. Sensor detects reflected light of a first sub-beam generated from the first laser light, a third sensor is disposed on the opposite side of the second sensor with respect to the first sensor, and a first laser The fourth sensor detects reflected light of the second sub-beam generated from the light, and the fourth sensor detects the first light generated from the second laser light.
The fifth sensor is disposed on the opposite side of the fourth sensor with respect to the first sensor,
The reflected light of the second sub-beam generated from the laser light is detected.

Further, the first sensor includes a first detection unit and a second detection unit.
A first detector that detects reflected light of the first laser light and a reflected light of a main beam generated from the first laser light; and a second detector that detects the second laser light. The reflected light of the main beam generated from is detected. Then, the second detection unit sets the astigmatism such that the peak of the signal calculated by the astigmatism method becomes maximum even when the optical axis of the reflected light of the main beam generated from the second laser light is shifted. The four regions for calculating by the aberration method are divided into regions so as to be changeable.

In the optical pickup device described in claim 5, the first laser beam is a recording medium for recording or reproducing a signal by using one laser beam, and the recording or reproducing signal is performed by using three laser beams. The main beam generated from the first laser beam, which is used for a recording medium to be reproduced, and in which the first laser beam reflected by the recording medium is detected by a first detection unit of a first sensor of a photodetector. , The first sub-beam, and the second sub-beam reflected by the recording medium are respectively the first detector of the first sensor of the photodetector, the second sensor of the photodetector, and the second detector of the photodetector. 3 are detected by the sensors.
The second laser light is used for a recording medium for recording or reproducing a signal using three laser lights, and is used to generate a main beam, a first sub-beam, and a second sub-beam generated from the second laser light. The reflected light from the recording medium is detected by the second detector of the first sensor of the photodetector, the fourth sensor of the photodetector, and the fifth sensor of the photodetector, respectively.
Then, the reflected light of the main beam generated from the second laser light detected by the second detection unit on the recording medium is calculated by the astigmatism method while changing the area, and the signal having the maximum peak is detected. Is done.

Therefore, according to the fifth aspect of the present invention, even when the optical axis of the main beam generated from the second laser beam is deviated from the center of the second detection unit, focusing by the astigmatism method is performed. An error signal and a tracking error signal by the DPP method can be accurately generated. Further, a DPD (Differential Phase) is formed using the first laser beam.
e Detection) tracking error signal and a DPP tracking error signal can be generated.

According to a sixth aspect of the present invention, there is provided an optical pickup device including the optical pickup device according to the fifth aspect, a first arithmetic circuit, a second arithmetic circuit, a third arithmetic circuit, and a fourth arithmetic circuit. It is. The first arithmetic circuit changes the four regions based on the optical signals input from the respective regions of the second detector of the photodetector, performs an arithmetic operation by the astigmatism method, and calculates an S-shaped curve having a maximum peak. Select output.

Further, the second arithmetic circuit generates a tracking error signal from the optical signal detected by the first detector by the DPD method. The third arithmetic circuit generates a tracking error signal from the optical signal detected by the first detection unit, the optical signal detected by the second sensor, and the optical signal detected by the third sensor by a DPP method. I do.

Further, the fourth arithmetic circuit calculates the SPP curve from the first arithmetic circuit at which the peak is maximum, the optical signal detected by the fourth sensor, and the DPP from the optical signal detected by the fifth sensor. A tracking error signal is generated by the method. In the optical disk device described in claim 6,
A first signal is detected using an optical signal detected by a second detector included in a first sensor included in a photodetector of the optical pickup device.
The arithmetic circuit performs an arithmetic operation by the astigmatism method, and selectively outputs an S-shaped curve having a maximum peak. Then, the S-shaped curve having the maximum peak is input to the fourth arithmetic circuit, and is used for calculating the tracking error signal by the DPP method together with the optical signals detected by the fourth sensor and the fifth sensor of the photodetector. The fourth arithmetic circuit generates a tracking error signal. The second arithmetic circuit uses the optical signal detected by the first detection unit of the first sensor of the photodetector to generate a DPD signal.
A tracking error signal is generated by the method. The third arithmetic circuit includes an optical signal detected by the first detection unit of the first sensor of the photodetector, an optical signal detected by the second sensor,
And DPP using the optical signal detected by the third sensor
A tracking error signal is generated by the method.

Therefore, according to the invention described in claim 6, even when the optical axis of the main beam generated from the second laser light is deviated from the center of the second detection section, the first arithmetic circuit always operates. The S-shaped curve having the largest peak is selected and output, and the S-shaped curve having the largest peak is always input to the fourth arithmetic circuit.
And an accurate tracking error signal by the DPP method can be generated. As a result, two recording media that perform focus servo by the astigmatism method and perform tracking servo by the DPP method and a recording medium that performs focus servo by the astigmatism method and perform the tracking servo by the DPD method are accurately accessed. it can.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, an optical pickup device 10 according to the present invention includes a laser light source 1, a polarization-selective diffraction grating 2, a collimator lens 3, a half mirror 4,
An objective lens 5, a condenser lens 7, and a photodetector 8 are provided.

The laser light source 1 includes a first semiconductor laser 1A
And the second semiconductor laser 1B, the first semiconductor laser 1A generates a laser beam having a wavelength of 650 nm (allowable error ± 15 nm, the same applies hereinafter), and the second semiconductor laser 1B generates a laser beam having a wavelength of 780 nm (allowable error ± 15 nm, the same applies hereinafter). Then, the first semiconductor laser 1A
And the second semiconductor laser 1B are shifted from the recording medium 6 or 66 in the tangential direction by 100 to 200 μm. Therefore, the laser light source 1 is a light source that can selectively generate laser light having a wavelength of 650 nm and laser light having a wavelength of 780 nm by shifting its optical axis.

The polarization-selective diffraction grating 2 diffracts the laser beam according to the plane of polarization of the laser beam to generate a main beam, a first sub-beam, and a second sub-beam.
Wavelength 650 nm generated from the first semiconductor laser 1A
The second semiconductor laser 1B
The main beam, the first and second sub-beams are generated by diffracting the laser beam having a wavelength of 780 nm generated from.
The collimator lens 3 converts the laser light into parallel light. The half mirror 4 transmits the laser beam from the collimator lens 3 as it is and guides it to the objective lens 5, and the recording medium 6 or 66
The half of the laser beam reflected by the signal recording surface 6a or 66a is reflected toward the photodetector 8.

The objective lens 5 focuses and irradiates a laser beam having a wavelength of 650 nm on a signal recording surface 6a of an optical recording medium 6 having a substrate thickness of 0.6 mm, and irradiates a laser beam having a wavelength of 780 nm with a substrate thickness of 1.2.
The signal recording surface 66a of the optical recording medium 66 is condensed and irradiated. That is, the objective lens 5 is designed to be able to collectively irradiate the optical recording medium 6 having a substrate thickness of 0.6 mm and the optical recording medium 66 having a substrate thickness of 1.2 mm. Such an objective lens is disclosed in, for example, JP-A-10-143905. The condensing lens 7 condenses the laser light reflected by the half mirror 4. The light detector 8 detects a laser beam.

The details of the polarization selective diffraction grating 2 will be described with reference to FIGS. Referring to FIG. 2, the polarization-selective diffraction grating 2 has a stripe-shaped grating 21 at a predetermined interval,
The laser beam LBH formed at a predetermined height and having the polarization plane 22 in the same direction as the direction in which the grating 21 is formed is not diffracted, but is transmitted as it is as the laser beam LBH. FIG.
, The polarization-selective diffraction grating 2 has a laser beam LBS having a polarization plane 23 orthogonal to the direction in which the grating 21 is formed.
And the main beam MLBS and the first sub beam S
An LBS1 and a second sub-beam SLBS2 are generated and transmitted. Therefore, in the optical pickup device 10, the first semiconductor laser 1A is arranged so that the polarization plane of the laser light having a wavelength of 650 nm coincides with the direction in which the grating 21 is formed, and the second semiconductor laser 1B has a wavelength of 780n.
The polarization plane of the m laser light is arranged to be orthogonal to the direction in which the grating 21 is formed. Accordingly, the polarization-selective diffraction grating 2 can transmit the laser light having the wavelength of 650 nm as it is, and diffract the laser light having the wavelength of 780 nm into the main beam, the first sub-beam, and the second sub-beam and transmit the laser light.

The details of the photodetector 8 will be described with reference to FIGS. The light detector 8 includes a first sensor 81, a second sensor 82, and a third sensor 83. First
The sensor 81 includes a first detection unit 811 and a second detection unit 812.
And The first sensor 81, the second sensor 82, and the third sensor 83 are arranged in the radial direction DR1 of the recording medium 6 or 66, and the second sensor 82 and the third sensor 83 are connected to the first sensor 81. Are arranged symmetrically with respect to. Further, the first detection unit 811 and the second detection unit 812 of the first sensor 81 are arranged in the tangential direction DR2 of the recording medium 6 or 66.

The first detector 811 of the first sensor 81 has a
The area is divided into a region 8111, a b region 8112, a c region 8113, and a d region 8114.
2 denotes an A region 8121, a B region 8122, and a C region 812
3, D region 8124, E region 8125, F region 812
6, the G area 8127, and the H area 8128. The second sensor 82 has a J region 821,
And the K area 822, and the J area 821 and the K area 822 are arranged in the radial direction of the recording medium 6 or 66. Further, the third sensor 83 has the M area 8
31 and an N area 832
And the N region 832 are arranged in the radial direction of the recording medium 6 or 66.

The first detecting section 811 is the first semiconductor laser 1
A laser beam LB1 having a wavelength of 650 nm generated from A and reflected by the signal recording surface 6a of the recording medium 6 is detected. The second detector 812 detects the main beam MLB2 generated from the second semiconductor laser 1B, diffracted by the polarization-selective diffraction grating 2, and further reflected by the signal recording surface 66a of the recording medium 66. The second sensor 82 detects the first sub-beam SLB21 generated from the second semiconductor laser 1B, diffracted by the polarization-selective diffraction grating 2, and further reflected by the signal recording surface 66a of the recording medium 66. The sensor 83 detects the second sub-beam SLB22 generated from the second semiconductor laser 1B, diffracted by the polarization selective diffraction grating 2, and further reflected on the signal recording surface 66a of the recording medium 66.

Referring to FIG. 5, the second detection unit 812
The region 8121, the B region 8122, the C region 8123, the D region 8124, the E region 8125, the F region 8126, the G region 8127, and the H region 8128 are divided into eight, which are divided into the first semiconductor laser 1A and the Even if the distance from the second semiconductor laser 1B deviates from the design value, the wavelength 78
Main beam MLB2 generated from 0 nm laser light
Is to be accurately detected. Originally, main beam ML
Although the optical axis of B2 coincides with the center 814 of the second detector 812, if the distance between the first semiconductor laser 1A and the second semiconductor laser 1B deviates from the design value, the first semiconductor laser 1A Light LB of wavelength 650 nm generated from
Since the optical axis adjustment is performed so that the optical axis of the first detection unit 811 coincides with the center of the first detection unit 811, the optical axis of the main beam MLB 2 generated from the laser light having the wavelength of 780 nm is adjusted to the second detection unit 811.
The optical axis of the main beam MLB2 is deviated from the center 814 of the twelve points 12 and coincides with the points 813 and 815 on the second detecting unit 812, and is irradiated to the second detecting unit 812. Therefore, in the present application, the optical axis of the main beam MLB2 is
Is calculated by the astigmatism method when the optical axis of the main beam MLB2 coincides with the points 813, 814, and 815 in order to accurately perform the calculation by the astigmatism method even when the center 814 deviates from the center 814. , The signal with the highest peak is selected.

That is, each of the A region 8121 and the B region 812
2, C region 8123, D region 8124, E region 812
5, F region 8126, G region 8127, and H region 8
The light intensity detected at 128 is [IA],
[IB], [IC], [ID], [IE], [IF],
Assuming that [IG] and [IH], when the optical axis of the main beam MLB2 coincides with the point 813, the calculation by the astigmatism method is [IA + IF + IG + IH]-[IB + IC + ID + IE] (1) When the optical axis of the beam MLB2 coincides with the point 814, the calculation by the astigmatism method is as follows: [IA + IB + IG + IH]-[IC + ID + IE + IF] (2), and the optical axis of the main beam MLB2 coincides with the point 815. In this case, the calculation by the astigmatism method is as follows: [IA + IB + IC + IH] − [ID + IE + IF + IG] (3)

Therefore, the above equations (1), (2), and (3) are operated to select a signal having the maximum peak. As a result, the optical axis of the main beam MLB2 is shifted to the second detector 812.
Can be accurately calculated by the astigmatism method even when the position deviates from the center 814 of. Referring to FIG. 6, laser light having a wavelength of 780 nm generated from second semiconductor laser 1B is converted into main beam MLB by polarization selective diffraction grating 2.
2. A recording medium 66 diffracted by the first sub-beam SLB21 and the second sub-beam SLB22 and having a substrate thickness of 1.2 mm, for example, a signal recording surface 6 of a CD-R or CD.
6a. In this case, the main beam MLB2 is applied to the center of the pit array 11 formed on the signal recording surface 66a, and the first sub-beam SLB21 is partially applied to the pit array 11 and is applied to the pit array 11 so as to be shifted to one side. Then, the second sub-beam SLB22 is partially applied to the pit row 11, and is irradiated while being shifted from the pit row 11 to the other side. When the recording medium 66 is a CD, a focus error signal by the astigmatism method and a reproduction signal are generated from the reflected light of the main beam MLB2, and tracking is performed from the reflected light of the first sub beam SLB21 and the second sub beam SLB22. Generate an error signal. When the recording medium 66 is a CD-R, a focus error signal is generated from the reflected light of the main beam MLB2 by the astigmatism method, and the main beam MLB2 and the first sub beam SLB2 are generated.
From the reflected light of the first and second sub-beams SLB22.
PP (Differential Push Pull)
A tracking error signal is generated by the method.

Referring to FIG. 7, first semiconductor laser 1A
Is emitted to a recording medium 6 having a substrate thickness of 0.6 mm, for example, a signal recording surface 6a of a DVD-ROM. Then, the laser beam LB1 having a wavelength of 650 nm is applied to the center of the pit row 12 formed on the signal recording surface 6a. Laser light L with a wavelength of 650 nm
From the reflected light of B1, a focus error signal by the astigmatism method, DPD (Differential Phase D)
tracking error signal by the
And reproduce the reproduction signal.

Referring again to FIG. 1, the laser light having a wavelength of 650 nm generated from the laser light source 1 passes through the polarization-selective diffraction grating 2 as it is, is converted into parallel light by a collimator lens 3, and passes through a half mirror 4. Incident on the objective lens 5. Then, the light is condensed by the objective lens 5 and is irradiated as a spot SP1 on the signal recording surface 6a of the recording medium 6. The laser light having a wavelength of 650 nm reflected by the signal recording surface 6a returns to the half mirror 4 via the objective lens 5, and half of the laser light is reflected by the half mirror 4 in the direction of the photodetector 8 and condensed by the condenser lens 7. You. Then, the first sensor 8 of the photodetector 8
1 is detected by the first detection unit 811.

The wavelength 7 generated from the laser light source 1
The 80 nm laser light is diffracted by the polarization-selective diffraction grating 2 into a main beam MLB2, a first sub-beam SLB21, and a second sub-beam SLB22. 5 is incident. Then, the light is condensed by the objective lens 5 and is irradiated as a spot SP2 on the signal recording surface 66a of the recording medium 66. Wavelength 7 reflected on signal recording surface 66a
The 80 nm laser light returns to the half mirror 4 via the objective lens 5, and half of the laser light is reflected by the half mirror 4 in the direction of the photodetector 8 and collected by the condenser lens 7. Then, the main beam MLB2 is detected by the second detector 812 of the first sensor 81 of the photodetector 8, and the first sub-beam SLB
21 is detected by the second sensor 82 of the photodetector 8,
Is the third sensor 8 of the photodetector 8
3 is detected.

Referring to FIG. 8, optical pickup device 10
Is used as a recording medium 6 having a substrate thickness of 0.6 mm.
The operation of reproducing a signal from the ROM will be described. DVD-R
When reproducing a signal from the OM, the first semiconductor laser 1A of the laser light source 1 is selectively driven by the laser driving circuit 250. Wavelength 650 emitted from first semiconductor laser 1A
The laser beam of nm passes through the polarization selective circuit grating 2 as it is, is converted into parallel light by the collimator lens 3, and enters the objective lens 5 via the half mirror 4. The light is condensed by the objective lens 5 and is recorded on the signal recording surface 6a of the DVD-ROM 6.
Is irradiated as a spot SP1. The laser light having a wavelength of 650 nm reflected by the signal recording surface 6a returns to the half mirror 4 via the objective lens 5, and half of the laser light is reflected by the half mirror 4 in the direction of the photodetector 8 and collected by the condenser lens 7. . Then, the signal is detected by the first detector 811 of the first sensor 81 of the photodetector 8, and the signal is reproduced.

Referring to FIG. 9, optical pickup device 10
The operation of reproducing a signal from a CD, which is a recording medium 66 having a substrate thickness of 1.2 mm, and recording and / or reproducing a signal on / from a CD-R will be described. First, CD or CD
The operation of reproducing a signal from -R will be described. CD,
Alternatively, when a signal is reproduced from the CD-R, the second semiconductor laser 1B of the laser light source 1 is selectively driven by the laser driving circuit 250. The laser light having a wavelength of 780 nm emitted from the second semiconductor laser 1B is
, The main beam MLB2 and the first sub beam SLB2
The light is diffracted into the first and second sub-beams SLB 22, is converted into parallel light by the collimator lens 3, and enters the objective lens 5 via the half mirror 4. Then, the light is condensed by the objective lens 5 and is recorded on the signal recording surface 66a of the CD or CD-R 66.
Is irradiated as a spot SP2. Signal recording surface 66a
The laser light having a wavelength of 780 nm reflected by the objective lens 5
, Half of the light is reflected by the half mirror 4 toward the photodetector 8 and condensed by the condenser lens 7. Then, the main beam MLB2 is detected by the second detector 812 of the first sensor 81 of the photodetector 8, and
Of the second sensor 8 of the photodetector 8
2, the second sub-beam SLB22 is detected by the third sensor 83 of the photodetector 8, and the CD or CD-
The signal is reproduced from R.

Next, the operation of recording a signal on a CD-R will be described. When recording a signal on a CD-R, the second semiconductor laser 1B of the laser light source 1
The intensity of the laser beam having a wavelength of 780 nm is selectively driven by 50 and modulated by the recording signal. The laser beam having a wavelength of 780 nm, the intensity of which has been modulated by the recording signal and emitted from the second semiconductor laser 1B, is diffracted by the polarization selective diffraction grating 2 into a main beam MLB2, a first sub beam SLB21, and a second sub beam SLB22. The light is collimated by the collimator lens 3 and enters the objective lens 5 via the half mirror 4. Then, the light is condensed by the objective lens 5 and is spot SP2 on the signal recording surface 66a of the CD-R 66.
Irradiated as As a result, pits are formed on the signal recording surface 66a, and the signal is recorded.

Referring to FIG. 10, second semiconductor laser 1
The position of B deviates from the design value, and the optical axis of the main beam MLB2 generated from the laser beam with a wavelength of 780 nm is the center 814 of the second sensor 812 of the first sensor 81 of the photodetector 8.
A description will be given of the second arithmetic circuit 120 that performs an arithmetic operation by the astigmatism method even in the case of deviation from the above, and selects and outputs a signal having a maximum peak. The second arithmetic circuit 120 includes a circuit 120
0, a circuit 1210, a circuit 1220, a maximum peak detection circuit 1230, an S-shaped curve output circuit 1240, and a switch 1245.

The circuit 1200 includes an adder 1201, an adder 1202, and a subtractor 1203. The circuit 1210 includes an adder 1211, an adder 1212, and a subtractor 1213. The circuit 1220 includes an adder 1221, an adder 1222, and a subtractor 1223. Circuit 1200 is a circuit for calculating the focus error signal FE ₁₃ by astigmatism method in the case of 4 dividing the second detection unit 812 about the point 13, i.e., the (1)
This is a circuit that performs the operation of the expression, and the adder 1201 has a function of [IA
+ IF + IG + IH], the adder 1202 performs [IB + IC + D + IE], and the subtractor 120
3 is [IA + IF + IG + IH]-[IB + IC + I
Performs the operation of the D + IE], a maximum peak detecting circuit 1230 as FE _13, and outputs to the terminal 1241.

The circuit 1210 includes a second detector 812
Circuitry for calculating a focus error signal FE ₁₄ by the astigmatism method when divided into four around the point 14, i.e.,
This is a circuit for performing the operation of the above equation (2).
Performs the operation of [IA + IB + IG + IH], the adder 1212 performs the operation of [IC + ID + IE + IF],
The subtractor 1213 calculates [IA + IB + IG + IH]-[I
Performs the operation of C + ID + IE + IF] , a maximum peak detecting circuit 1230 as FE _14, and outputs to the terminal 1242.

The circuit 1220 includes a second detection unit 812
Circuitry for calculating a focus error signal FE ₁₅ by 4 divided astigmatism method when the centering point 15, i.e.,
This is a circuit for performing the operation of the above equation (3).
Performs an operation of [IA + IB + IC + IH], an adder 1222 performs an operation of [ID + IE + IF + IG],
The subtractor 1223 calculates [IA + IB + IC + IH]-[I
D + IE + performs the operation of the IF + IG], a maximum peak detecting circuit 1230 as FE _15, and outputs to the terminal 1243.

Then, the maximum peak detection circuit 1230
Selects the focus error signal having the maximum peak from the input FE ₁₃ , FE ₁₄ , and FE ₁₅ , and outputs the result to the S-curve output circuit 1240. When the optical axis of the main beam MLB2 coincides with the position of the point 13 of the second detection unit 812 and is emitted to the second detection unit 812, FE
₁₃ , the peak becomes smaller in the order of FE ₁₄ and FE ₁₅ . That is,
S-shaped curve shown in FIG. 11 (a) becomes FE _13, FIG. 1
S-shaped curve shown in 1 (b) is a FE _14, S-shaped curve shown in FIG. 11 (c) it is FE _15. Therefore, the maximum peak detection circuit 1230 outputs the focus error signal FE
₁₃ is selected and the result is output to the S-shaped curve output circuit 1240. Then, the S-shaped curve output circuit 1240
Connects the switch 1245 to the terminal 1241, and outputs a focus error signal FE ₁₃ from the terminal 1246.

By the above operation, the focus error signal (S-curve) having the maximum peak is output from the second arithmetic circuit 120 using the intensity of the main beam MLB2 detected by the second detector 812. The focus error signal obtained by the astigmatism method is used for focus servo to a CD or CD-R as a recording medium with a substrate thickness of 1.2 mm and a DVD-ROM as a recording medium with a substrate thickness of 0.6 mm.

Referring to FIG. 12, first operation circuit 110 for generating a tracking error signal by the DPP method will be described. The first arithmetic circuit 110 includes a subtractor 1101,
Subtractor 1102, adder 1103, multiplication circuit 1104
And a subtractor 1105. Since it is the CD-R that performs the tracking servo using the tracking error signal by the DPP method, the main beam MLB2 obtained by diffracting the laser light having a wavelength of 780 nm emitted from the second semiconductor laser 1B, Sub beam SLB21,
And the reflected light of the second sub-beam SLB22 at the CD-R is converted to a second detection unit 812 and a second sensor 8 respectively.
2. A tracking error signal detected by the third sensor 83 and generated by the DPP method is generated. Therefore, the subtractor 1101
Are the light intensity [IJ] detected in the J region 821 of the second sensor 82 and the light intensity [IJ] detected in the K region 822.
K] is input, and the calculation of [IJ-IK] is performed.
The subtractor 1102 has an M area 8 of the third sensor 83.
The light intensity [IM] detected at 31 and the light intensity [IN] detected at the N region 832 are input, and [IM-IN]
Is performed. Then, [IJ-
IK] + [IM-IN] is calculated, and the multiplication circuit 11
The value is multiplied by k at 04 and input to the (-) terminal of the subtractor 1105. On the other hand, the (+) terminal of the subtractor 1105 has [IA +
IB + IC + ID]-[IE + IF + IG + IH] is input. Then, the subtractor 1105 calculates [IA + IB + I
C + ID]-[IE + IF + IG + IH] -k [[IJ
−IK] + [IM-IN]] is performed, and a terminal 110 is provided as a tracking error signal TR1 by the DPP method.
7 is output.

Referring to FIG. 13, the third arithmetic circuit 130 for generating a tracking error signal by the three-beam method will be described. The third arithmetic circuit 130 includes an adder 130
1, an adder 1302 and a subtractor 1303.
Since it is the CD that performs tracking servo by the three-beam method, the first sub-beam SLB21 and the second sub-beam SLB22 obtained by diffracting the laser light having a wavelength of 780 nm emitted from the second semiconductor laser 1B are obtained. The reflected light from the CD is sent to the second sensor 82 and the third sensor, respectively.
, And generates a tracking error signal by the three-beam method. Therefore, the adder 1301 has the light intensity [I] detected in the J region 821 of the second sensor 82.
J] and the light intensity [IK] detected in the K region 822 are input, and [IJ + IK] is calculated. Further, the light intensity [IM] detected in the M region 831 of the third sensor 83 and the light intensity [IN] detected in the N region 832 of the third sensor 83 are input to the adder 1302, and the calculation of [IM + IN] is performed. Done. Then, [IJ + IK] −
The calculation of [IM + IN] is performed, and is output from the terminal 1304 as a tracking error signal TR2 by the three-beam method.

Referring to FIG. 14, a fourth operation circuit 140 for generating a tracking error signal by the DPD method will be described. The fourth arithmetic circuit 140 includes an adder 1401
, Adder 1402, comparator 1403, comparator 1404, time difference detection circuit 1405, LP
F1406. Since the DVD-ROM performs tracking servo by the DPD method, the first sensor 81 detects the reflected light of the laser light having a wavelength of 650 nm generated by the first semiconductor laser 1A on the DVD-ROM by the first sensor 81. The tracking error signal is detected by the unit 811 and generated by the DPD method. Therefore, the light intensity [Ia] detected in the a region 8111 of the first detection unit is added to the adder 1401.
And the light intensity [Id] detected in the d region 8114 are input, and [Ia + Id] is calculated. Further, the light intensity [Ib] detected in the b region 8112 and the light intensity [Ic] detected in the c region 8113 of the first detector 811 are input to the adder 1402, and the calculation of [Ib + Ic] is performed. Will be That is, the adder 1401 outputs a signal shown in FIG. 15A, and the adder 1402 outputs a signal shown in FIG. The signal (a) is input to the comparator 1403 and is compared by the comparator 1403 to output the signal (c). Further, the signal (b) is input to the comparator 1404, and is compared by the comparator 1404 to output the signal (d). Then, the signal (c) and the signal (d) are input to the time difference detection circuit 1405, and the time difference detection circuit 1405 detects the phase difference between the signal (c) and the signal (d), and outputs the signal (e).
Is output from the time difference detection circuit 1405. Then, the signal (e) is input to the LPF 1406, and the LPF 1406
And the signal (f) is output as the tracking error signal TR3 by the DPD method.

Referring to FIG. 16, the fifth arithmetic circuit 150 for generating a reproduction signal of a CD or CD-R will be described. The fifth arithmetic circuit 150 includes an adder 1501 and an adder 150
2 and an adder 1503. The adder 1501
Wavelength 780 nm emitted from the second semiconductor laser 1B
The reflected light of the main beam MLB2 at the CD or CD-R obtained by diffracting the laser light of
Light intensity [IA] detected in region 8121, B region 812
The light intensity [IB] detected in step 2, the light intensity [IC] detected in the C region 8123, and the light intensity [ID] detected in the D region 8124 are input, and [IA + IB + IC + ID]
Is calculated. Further, the adder 1502 is a CD or a CD of the main beam MLB2 obtained by diffracting the laser light having a wavelength of 780 nm emitted from the second semiconductor laser 1B.
The light intensity [IE] detected in the E region 8125 of the second detector 812, the light intensity [IF] detected in the F region 8126, and the light intensity [I] detected in the G region 8127 of the second detector 812.
G], and the light intensity [IH] detected in the H region 8128
To calculate [IE + IF + IG + IH].
Then, the adder 1503 outputs the output [I
A + IB + IC + ID] and the output of the adder 1502 [IE
+ IF + IG + IH] and the reproduced signal RF1 =
[IA + IB + IC + ID] + [IE + IF + IG + I
H] is output.

Referring to FIG. 17, a sixth arithmetic circuit 160 for generating a DVD-ROM reproduction signal will be described. The sixth arithmetic circuit 160 includes an adder 1601 and an adder 160
2 and an adder 1603. The adder 1601
Wavelength 650 nm emitted from the first semiconductor laser 1A
The reflected light of the laser light from the DVD-ROM is detected by the first detection unit 8.
11, the light intensity [Ia] detected in the a region 8111 and the light intensity [Ib] detected in the b region 8112 are input to calculate [Ia + Ib]. Also, an adder 1602
Is the wavelength 650 emitted from the first semiconductor laser 1A.
The light intensity [Ic] detected by the c-region 8113 of the first detector 811 as the reflected light of the laser light of nm in the DVD-ROM,
Then, the light intensity [Id] detected in the d region 8114 is input, and [Ic + Id] is calculated. And the adder 16
03 adds the output [Ia + Ib] of the adder 1601 and the output [Ic + Id] of the adder 1602 to obtain a reproduced signal R
F2 = [Ia + Ib] + [Ic + Id] is output.

Referring to FIG. 18, first arithmetic circuit 110 and second arithmetic circuit 120 are connected and have a wavelength of 780n.
The second arithmetic circuit 120 calculates a focus error signal by the astigmatism method that has a maximum peak even when the optical axis of the main beam MLB2 generated from the m laser light is shifted from the center 814 of the second detection unit 812. And the result to terminal 12
The signal is output from 46 and used for the focus servo of the recording medium 6 or 66. Accordingly, even when the optical axis of the main beam MLB2 generated from the laser light having the wavelength of 780 nm is shifted from the center 814 of the second detection unit 812, the tracking error signal TR1 by the DPP method can be accurately generated.
The generated tracking error signal TR1 is used for CD-R tracking servo.

Referring to FIG. 19, optical pickup device 1
The optical disk device 100 using 0 will be described. The optical disk device 100 includes an optical pickup device 10, a first arithmetic circuit 110, a second arithmetic circuit 120, a third arithmetic circuit 130, a fourth arithmetic circuit 140, and a fifth arithmetic circuit 1.
50, a sixth arithmetic circuit 160, and a reproduced signal amplifying circuit 17
0, servo circuit 180, servo mechanism 190, spindle motor 200, decoding processing circuit 210, control circuit 220, modulation circuit 230, drive signal generation circuit 24
0 and a laser drive circuit 250.

The optical pickup device 10 irradiates the recording medium 6 or 66 with the laser light having the wavelength of 650 nm or the laser light having the wavelength of 780 as described above, and detects the reflected light with the photodetector 8. The first arithmetic circuit 110 generates the tracking error signal T by the DPP method as described above.
R1 is generated and output to the reproduction signal amplification circuit 170. The second arithmetic circuit 120 generates the focus error signal FE by the astigmatism method as described above, and outputs the focus error signal FE to the reproduction signal amplifier circuit 170. The third arithmetic circuit 130 generates the tracking error signal TR2 by the three-beam method as described above, and outputs it to the reproduction signal amplifier circuit 170.
The fourth arithmetic circuit 140 generates the tracking error signal TR3 by the DPD method as described above, and outputs it to the reproduction signal amplifier circuit 170. The fifth arithmetic circuit 150 generates the reproduction signal RF1 as described above, and outputs the signal to the reproduction signal amplifier circuit 170. The sixth arithmetic circuit 160 generates the reproduction signal RF2 as described above, and outputs the reproduction signal RF2 to the reproduction signal amplifier circuit 170.

The reproduction signal amplifier 170 receives the focus error signal FE and the tracking error signal TR.
1, TR2, TR3, and the reproduction signals RF1, RF2 are amplified to predetermined levels, and a focus error signal FE,
The tracking error signals TR1, TR2, and TR3 are output to the servo circuit 180, and the reproduction signals RF1 and RF2 are output to the decoding processing circuit 210.

The servo circuit 180 receives the focus error signal FE and the tracking error signal TR.
1, an optical pickup device 1 based on TR2 and TR3
The servo mechanism 190 is controlled so as to perform focus servo and tracking servo of the objective lens 5 during zero. In addition, the servo circuit 180 includes the spindle motor 20
0 is controlled to rotate at a predetermined rotation speed.

The servo mechanism 190 performs focus servo and tracking servo of the objective lens 5 in the optical pickup device 10 based on the control from the servo circuit 180. Further, the spindle motor 200 rotates the optical recording medium 6 or 66 at a predetermined rotation speed. The decoding processing circuit 210 decodes the reproduction signals RF1 and RF2 and outputs the decoded signals to an external output device as reproduction data. Control circuit 220
Controls the drive signal generation circuit 240. Modulation circuit 23
When a signal is recorded on a CD-R, 0 modulates the recording data in a predetermined format and outputs the modulated data to the drive signal generation circuit 240. When reproducing a signal from a CD-R based on the control from the control circuit 220, the drive signal generation circuit 240
A drive signal for generating a laser beam having an intensity of 0.7 mW is generated and output to the laser drive circuit 250. When recording a signal on a CD-R, the modulation circuit 230
A drive signal for modulating the intensity of the laser beam is generated based on the recording signal input from the controller, and is output to the laser drive circuit 250. The laser drive circuit 250 includes the drive signal generation circuit 24
The second semiconductor laser 1B in the optical pickup device 10 is selectively driven based on the drive signal from 0. The optical pickup device 10 irradiates the CD-R with laser light having a predetermined intensity.

DVD-R in Optical Disk Device 100
The reproduction operation from the OM 6 will be described. When the DVD-ROM 6 is mounted on the optical disk device 100, the control circuit 220 controls the servo circuit 180 to rotate the spindle motor 200 at a predetermined rotation speed, and the servo circuit 1
80 rotates the spindle motor 200 at a predetermined rotation speed. Further, the control circuit 220 controls the drive signal generation circuit 240 so as to generate a drive signal for generating a laser beam having a predetermined intensity and a wavelength of 650 nm, and the drive signal generation circuit 240 generates a drive signal. , To the laser drive circuit 250. The laser drive circuit 250 selectively drives the first semiconductor laser 1A in the optical pickup device 10 based on the drive signal from the drive signal generation circuit 240. To the DVD-RAM 6, and the reflected light is detected by the first detector 811 of the photodetector 7.
The light intensity detected by the first detector 811 is equal to the second arithmetic circuit 1
20 and the fourth arithmetic circuit 140, and the second arithmetic circuit 120 outputs the focus error signal FE as described above.
Is calculated, and the fourth arithmetic circuit 140 calculates the tracking error signal TR3 by the DPD method. Then, the focus error signal FE and the tracking error signal TR3
Means that the servo circuit 18
Input to 0. Then, focus servo and tracking servo of the objective lens 5 in the optical pickup device 10 are performed based on the focus error signal FE and the tracking error signal TR3.

After that, the laser light having a wavelength of 650 nm
The data is moved to the data area of the D-RAM 6 and the pit row 1
2 is detected by the first detector 811 of the photodetector 8 and the detected laser light intensity is changed to the sixth intensity.
Input to the arithmetic circuit 160. Then, the sixth arithmetic circuit 16
0, the reproduction signal RF2 is calculated as described above, and is input to the decoding processing circuit 210 via the reproduction signal amplifier circuit 170. The decoding processing described above is performed by the decoding processing circuit 210 and output to an external output device (not shown) as reproduction data. Thus, the reproduction operation from the DVD-RAM 6 ends.

Next, the CD in the optical disk device 100
The reproducing operation from step 66 will be described. When the CD 66 is mounted on the optical disk device 100, the control circuit 220 controls the servo circuit 180 to rotate the spindle motor 200 at a predetermined rotation speed, and the servo circuit 180 rotates the spindle motor 200 at a predetermined rotation speed. . Also,
The control circuit 220 has a wavelength of 780 nm having a predetermined intensity.
The drive signal generation circuit 240 is controlled so as to generate a drive signal for generating the laser light, and the drive signal generation circuit 2
40 generates a drive signal and outputs it to the laser drive circuit 250. The laser drive circuit 250 includes the drive signal generation circuit 2
Optical pickup device 10 based on the drive signal from
The second semiconductor laser 1B inside is selectively driven, and the optical pickup device 10 outputs a main beam MLB having a predetermined intensity.
2 and first and second sub-beams SLB21, SLB2
2 is irradiated to the CD 66, and the reflected light is emitted to the second detector 812 of the photodetector 8, the second sensor 82,
And the third sensor 83. Second detector 811
The intensity of the main beam MLB2 detected at is input to the second arithmetic circuit 120, and the second arithmetic circuit 120 calculates the focus error signal FE as described above. Also, the first sub-beam S detected by the second sensor 82
The intensity of the LB21 and the intensity of the second sub-beam SLB22 detected by the third sensor 83 are input to the third arithmetic circuit 130, and the third arithmetic circuit 130 generates the tracking error signal TR2 by the three-beam method as described above. Is calculated. Then, the focus error signal FE and the tracking error signal TR2 are input to the servo circuit 180 via the reproduction signal amplifier circuit 170. Then, focus servo and tracking servo of the objective lens 5 in the optical pickup device 100 are performed based on the focus error signal FE and the tracking error signal TR2.

Thereafter, the laser beam is moved to the data area of the CD 66, and the main beam M based on the pit row 11 is moved.
A change in the intensity of LB2 is detected by the second detector 812 of the photodetector 8, and the detected intensity of the laser light is calculated by the fifth arithmetic circuit 15
Enter 0. The reproduced signal RF1 is calculated by the fifth arithmetic circuit 150 as described above, and is input to the decoding processing circuit 210 via the reproduced signal amplifier circuit 170. The decoding processing described above is performed by the decoding processing circuit 210 and output to an external output device (not shown) as reproduction data. Thus, the reproduction operation from the CD 66 ends.

Next, the reproduction operation from the CD-R 66 in the optical disk device 100 will be described.
When the CD-R 66 is mounted on the optical disc device 100,
The control circuit 220 controls the servo circuit 180 to rotate the spindle motor 200 at a predetermined rotation speed, and the servo circuit 180 rotates the spindle motor 200 at a predetermined rotation speed. Further, the control circuit 220 controls the drive signal generation circuit 240 so as to generate a drive signal for generating laser light having a predetermined intensity and a wavelength of 780 nm,
The drive signal generation circuit 240 generates a drive signal and outputs it to the laser drive circuit 250. The laser driving circuit 250
The second semiconductor laser 1B in the optical pickup device 10 is selectively driven based on a drive signal from the drive signal generation circuit 240, and the optical pickup device 10 has a main beam MLB2 having a predetermined intensity and first and second sub-beams. S
The laser beam composed of LB21 and SLB22 is converted to CD-R6
6 and the reflected light is applied to the second detector 81 of the photodetector 8.
2. Detection is performed by the second sensor 82 and the third sensor 83. Main beam ML detected by second detector 812
The intensity of B2 is input to the second arithmetic circuit 120, and the second arithmetic circuit 120 calculates the focus error signal FE as described above. Then, the intensity of the main beam MLB2 detected by the second detection unit 812 and the second sensor 82
And the intensity of the first sub-beam SLB21 detected by the third sensor 83 and the second sub-beam SLB2 detected by the third sensor 83
2 is input to the first arithmetic circuit 110, and the first arithmetic circuit 110 calculates the tracking error signal TR1 by the DPP method as described above. Then, the focus error signal FE and the tracking error signal TR1 are supplied to the servo circuit 180 via the reproduction signal amplifier 170.
Is input to Then, focus servo and tracking servo of the objective lens 5 in the optical pickup device 100 are performed based on the focus error signal FE and the tracking error signal TR1.

After that, the laser beam is moved to the data area of the CD-R 66, and the intensity change of the main beam MLB 2 based on the pit row 11 is detected by the second detector 812 of the photodetector 8.
The intensity of the detected laser beam is input to the fifth arithmetic circuit 150. The reproduced signal RF1 is calculated by the fifth arithmetic circuit 150 as described above, and is input to the decoding processing circuit 210 via the reproduced signal amplifier circuit 170.
The decoding processing described above is performed by the decoding processing circuit 210 and output to an external output device (not shown) as reproduction data.
Thus, the reproduction operation from the CD-R 66 ends.

Next, the operation of recording a signal on the CD-R 66 in the optical disc apparatus 100 will be described. Second semiconductor laser 1 in optical pickup device 10
The operation from when B is selectively driven until the focus servo and the tracking servo of the objective lens 5 are turned on is the same as the case of the reproducing operation. After that, the modulation circuit 230 modulates the recording data into a predetermined format, and
0 generates a drive signal for generating a laser beam having a wavelength of 780 nm whose intensity changes based on the input recording signal, and outputs the drive signal to the laser drive circuit 250. Then, in the laser drive circuit 250, the second semiconductor laser 1B in the optical pickup device 10 is selectively driven based on the drive signal from the drive signal generation circuit 240, and recording is performed through the operation described with reference to FIG. A laser beam having a wavelength of 780 nm having an intensity modulated based on the signal is applied to the signal recording surface 66a of the CD-R 66, and a signal is recorded on the CD-R 66. Thus, the recording operation on the CD-R 66 ends.

The optical pickup device according to the present invention is shown in FIG.
The optical pickup device 20 shown in FIG. 20 is not limited to the optical pickup device 10 shown in FIG. The optical pickup device 20 replaces the polarization-selective diffraction grating 2 of the optical pickup device 10 shown in FIG.
Is replaced by a photodetector 88, and the other configuration is the same as that of the optical pickup device 10. The diffraction grating 22
The main beam and the first sub-beam are obtained by diffracting a laser beam having a wavelength of 650 nm emitted from the first semiconductor laser 1A included in the laser light source 1 and a laser beam having a wavelength of 780 nm emitted from the second semiconductor laser 1B. And a second sub-beam.

Referring to FIG. 21, the planar structure of photodetector 88 is obtained by adding a fourth sensor 84 and a fifth sensor 85 to the planar structure of photodetector 8 shown in FIG. First
Sensor 81, fourth sensor 84, fifth sensor 85
Are arranged in the radial direction DR1 of the recording medium 6 or 66, and the fourth sensor 84 and the fifth sensor 85 are arranged at symmetric positions with respect to the first sensor 81.

The fourth sensor 84 is divided into a j region 841 and a k region 842, and the j region 841 and the k region 842 are arranged in the radial direction of the recording medium 6 or 66. Further, the fifth sensor 85 has an m region 85
1 and an n region 852, and the m region 851 and the n region 852 are arranged in the radial direction of the recording medium 6 or 66.

The first detecting section 811 is the first semiconductor laser 1
A, the main beam ML is diffracted by the diffraction grating 22 and further reflected by the signal recording surface 6a of the recording medium 6.
Upon detecting B1, the fourth sensor 84 detects a first sub-beam SLB11 generated from the first semiconductor laser 1A, diffracted by the diffraction grating 22, and further reflected by the signal recording surface 6a of the recording medium 6. , The fifth sensor 85 is generated from the first semiconductor laser 1A, is diffracted by the diffraction grating 22,
Furthermore, the 22nd light reflected on the signal recording surface 6a of the recording medium 6
The sub beam SLB12 is detected.

In the optical pickup device 20, the first
When the distance between the semiconductor laser 1A and the second semiconductor laser 1B deviates from the design value, the second semiconductor laser 1B
The laser beam having a wavelength of 780 nm generated from the above can be detected to obtain a focus error signal by the astigmatism method in which the peak is maximized. Also, the optical pickup device 20
In the above, the laser light having a wavelength of 650 nm generated from the first semiconductor laser 1A is
Sub beam SLB11 and second sub beam SL
A signal is recorded or reproduced by diffracting the light into B12, and an example of the target optical disk is a DVD-RAM. Focus servo in a DVD-RAM is performed using a focus error signal by an astigmatism method.
Therefore, the reflected light of the main beam MLB1 from the DVD-RAM is detected by the first detection unit 811 of the photodetector 88, and the focus error signal by the astigmatism method is calculated by the second calculation circuit 120 shown in FIG. Is done.

The tracking servo in the DVD-RAM is performed using a tracking error signal by the DPP method. Therefore, the reflected light of the first sub-beam SLB11 on the DVD-RAM is detected by the fourth sensor 84 of the photodetector 88, and the DVD of the second sub-beam SLB12 is detected.
A fifth sensor 85 of the photodetector 88 for reflecting the reflected light from the RAM;
And the tracking error signal by the DPP method is calculated by the first calculation circuit 110 shown in FIG.

The optical disks targeted by the optical pickup device 20 are CDs, CD-Rs, and DVD-RAMs. Referring to FIG. 22, a DVD-RAM which is a recording medium 6 having a substrate thickness of 0.6 mm using an optical pickup device 20
The operation of reproducing a signal from a. When reproducing a signal from the DVD-RAM, the first semiconductor laser 1A of the laser light source 1 is selectively driven by the laser driving circuit 250. 650 nm wavelength emitted from the first semiconductor laser 1A
The laser light of the main beam MLB1,
The light is diffracted into the first sub-beam SLB11 and the second sub-beam SLB12, is converted into parallel light by the collimator lens 3, and enters the objective lens 5 via the half mirror 4. Then, the light is condensed by the objective lens 5 and the DVD-RAM
6 is irradiated as a spot SP1 on the signal recording surface 6a. The laser light having a wavelength of 650 nm reflected by the signal recording surface 6a returns to the half mirror 4 via the objective lens 5, and half of the laser light is reflected by the half mirror 4 in the direction of the photodetector 88.
The light is condensed by the condenser lens 7. The main beam MLB1 is detected by the first detector 811 of the first sensor 81 of the photodetector 88, the first sub-beam SLB11 is detected by the fourth sensor 84 of the photodetector 88, and the second sub-beam SLB
12 is detected by the fifth sensor 85 of the photodetector 88, and D
The signal is reproduced from the VD-RAM.

Next, the operation of recording a signal on the DVD-RAM will be described. When recording a signal on the DVD-RAM, the first semiconductor laser 1A of the laser light source 1 is selectively driven by the laser driving circuit 250, and the wavelength is 650 nm.
Is modulated by the recording signal. The first semiconductor laser 1A whose intensity is modulated by a recording signal.
Is emitted from the diffraction grating 22 at a wavelength of 650 nm.
, The main beam MLB1 and the first sub beam SLB1
The light is diffracted into the first and second sub-beams SLB 12, converted into parallel light by the collimator lens 3, and enters the objective lens 5 via the half mirror 4. Then, the light is condensed by the objective lens 5 and irradiated as a spot SP1 on the signal recording surface 6a of the DVD-RAM 6. Thereby, the signal recording surface 6a
A pit is formed and a signal is recorded.

Referring to FIG. 23, optical pickup device 2
0, a CD as a recording medium 66 having a substrate thickness of 1.2 mm
The operation of reproducing a signal from and reproducing a signal from / to a CD-R will be described. First, CD or C
The operation of reproducing a signal from DR will be described. C
When a signal is reproduced from D or CD-R, the second semiconductor laser 1B of the laser light source 1
0 is selectively driven. The laser light having a wavelength of 780 nm emitted from the second semiconductor laser 1B is diffracted by the diffraction grating 22 into the main beam MLB2, the first sub-beam SLB21, and the second sub-beam SLB22, is converted into parallel light by the collimator lens 3, and is converted into half light. The light enters the objective lens 5 via the mirror 4. Then, the light is condensed by the objective lens 5 and irradiated as a spot SP2 on the signal recording surface 66a of the CD or CD-R 66. The laser beam having a wavelength of 780 nm reflected by the signal recording surface 66a returns to the half mirror 4 via the objective lens 5, and half of the laser light is reflected by the half mirror 4 in the direction of the photodetector 88 and collected by the condenser lens 7. You. Then, the main beam MLB2 is detected by the second detector 812 of the first sensor 81 of the photodetector 88, and the first sub-beam SLB21 is detected by the second sensor 82 of the photodetector 8.
And the second sub-beam SLB22 is detected by the photodetector 8
8 is detected by the third sensor 83, and the CD or CD-
The signal is reproduced from R.

Next, the operation of recording a signal on a CD-R will be described. When recording a signal on a CD-R, the second semiconductor laser 1B of the laser light source 1
The intensity of the laser beam having a wavelength of 780 nm is selectively driven by 50 and modulated by the recording signal. The laser beam having a wavelength of 780 nm, the intensity of which is modulated by the recording signal and emitted from the second semiconductor laser 1B, is converted by the diffraction grating 22 into the main beam MLB2, the first sub-beam SLB21, and the second
Is diffracted into the sub-beam SLB 22, is converted into parallel light by the collimator lens 3, and enters the objective lens 5 via the half mirror 4. Then, the light is condensed by the objective lens 5 and
The signal is irradiated onto the signal recording surface 66a of -R66 as a spot SP2. As a result, pits are formed on the signal recording surface 66a, and the signal is recorded.

Referring to FIG. 24, optical pickup device 2
An optical disk device 300 using 0 will be described. The optical disk device 300 is an optical disk device 1 shown in FIG.
00 optical pickup device 10 and optical pickup device 2
The other configuration is the same as that of the optical disk device 100. Therefore, the operation of reproducing a signal from a CD or a CD-R and recording the signal on the CD-R is the same as that described with reference to FIG. In addition, a signal is recorded on a DVD-RAM,
The operation of reproducing a signal from a DVD-RAM is basically the same as the operation of recording a signal on a CD-R and reproducing the signal from the CD-R.

The optical pickup device according to the present invention may be the optical pickup device 30 shown in FIG. The optical pickup device 30 is obtained by adding the polarization plane rotating element 9 to the optical pickup device 10 shown in FIG.
Referring to FIG. 26, polarization plane rotating element 9 is a TN type liquid crystal 9.
1 is a transparent electrode 93 formed on a glass 92 and a glass 94
Are sandwiched between the transparent electrodes 95 formed in
The transparent electrode 93 and the transparent electrode 95 are in contact with the TN type liquid crystal 91. The TN liquid crystal 91 is twisted 90 degrees between the transparent electrode 93 and the transparent electrode 95. Therefore, when no voltage is applied between the transparent electrode 93 and the transparent electrode 95, the polarization plane rotating element 9 rotates the polarization plane of the laser beam by 90 degrees, and applies a voltage between the transparent electrode 93 and the transparent electrode 95. When applied, the laser beam is transmitted as it is without rotating the plane of polarization of the laser beam.

Referring again to FIG. 25, in the optical pickup device 30, the first semiconductor laser 1A is selectively driven to use a laser beam having a wavelength of 650 nm and a substrate thickness of 0.6.
When recording or reproducing a signal on or from a recording medium having a thickness of 1 mm, the polarization plane of the laser beam having a wavelength of 650 nm is selectively rotated by the polarization plane rotation element 9 and the main beam and the first beam are selectively generated by the polarization selective diffraction grating 2. Diffracts into a sub-beam and a second sub-beam. When the second semiconductor laser 1B is selectively driven to record or reproduce a signal on or from a recording medium having a substrate thickness of 1.2 mm using a laser beam having a wavelength of 780 nm, the polarization plane rotation element 9 generates a laser beam having a wavelength of 780 nm. The light is transmitted as it is without rotating the plane of polarization, and is diffracted by the polarization selective diffraction grating 2 into a main beam, a first sub beam, and a second sub beam.

Therefore, the optical pickup device 30 can be used for recording or reproducing signals using three beams, such as CDs and CD-ROMs.
R and DVD-RAM, and a DVD-ROM for recording or reproducing a signal using one beam. ON / OF of voltage to TN type liquid crystal 91 of polarization plane rotation element 9
F is performed by the liquid crystal drive circuit 260. Referring to FIG. 27, when reproducing a signal from a DVD-ROM using optical pickup device 30, a voltage is applied from liquid crystal drive circuit 260 to TN type liquid crystal 91 of polarization plane rotation element 9. Therefore, the wavelength 650n emitted from the first semiconductor laser 1A
The laser beam of m enters the polarization selective diffraction grating 2 without being able to rotate the polarization plane by 90 degrees by the polarization plane rotation element 9. Then, the light passes through the polarization selective diffraction grating 2 as it is, is converted into parallel light by the collimator lens 3, and enters the objective lens 5 via the half mirror 4. Then, the light is condensed by the objective lens 5 and is spot SP on the signal recording surface 6a of the DVD-ROM 6.
Irradiated as 1. The laser light having a wavelength of 650 nm reflected by the signal recording surface 6a returns to the half mirror 4 via the objective lens 5, and half of the laser light is reflected by the half mirror 4 to the photodetector 88.
, Is collected by the condenser lens 7, and detected by the first detector 811 of the first sensor 81 of the photodetector 88.

Also, using the optical pickup device 30,
When reproducing a signal from the VD-RAM, no voltage is applied from the liquid crystal driving circuit 260 to the TN type liquid crystal 91 of the polarization plane rotation element 9. Accordingly, the laser light having a wavelength of 650 nm emitted from the first semiconductor laser 1A has its polarization plane rotated by 90 degrees by the polarization plane rotation element 9 and enters the polarization selective diffraction grating 2. Then, the light is diffracted by the polarization-selective diffraction grating 2 into the main beam MLB1, the first sub-beam SLB11, and the second sub-beam SLB12.
Is converted into parallel light by the objective lens 5 via the half mirror 4.
Incident on. Then, the light is condensed by the objective lens 5 and the DVD
-Irradiated as a spot SP1 on the signal recording surface 6a of the RAM 6. Wavelength 650 nm reflected on signal recording surface 6a
Is returned to the half mirror 4 via the objective lens 5, half of the laser light is reflected by the half mirror 4 in the direction of the photodetector 88, is collected by the condenser lens 7, and
1 is the first detection unit 81 of the first sensor 81 of the photodetector 88
1, the first sub beam SLB11 is detected by the fourth sensor 84, and the second sub beam SLB12 is detected by the fifth sensor 85.

Further, using the optical pickup device 30,
When recording signals in the VD-RAM, the liquid crystal driving circuit 2
From 60, no voltage is applied to the TN type liquid crystal 91 of the polarization plane rotation element 9. Accordingly, the laser light having a wavelength of 650 nm emitted from the first semiconductor laser 1A has its polarization plane rotated by 90 degrees by the polarization plane rotation element 9 and enters the polarization selective diffraction grating 2. Then, the main beam M is polarized by the polarization selective diffraction grating 2.
The light is diffracted into LB1, first sub-beam SLB11, and second sub-beam SLB12, is converted into parallel light by collimator lens 3, and is incident on objective lens 5 via half mirror 4. The light is condensed by the objective lens 5 and the DVD-
The signal is irradiated onto the signal recording surface 6a of the RAM 6 as a spot SP1. A pit is formed on the signal recording surface 6a to record a signal.

Referring to FIG. 28, optical pickup device 3
When reproducing a signal from a CD using 0, no voltage is applied from the liquid crystal drive circuit 260 to the TN liquid crystal 91 of the polarization plane rotation element 9. Accordingly, the laser light having a wavelength of 780 nm emitted from the second semiconductor laser 1B has its polarization plane rotated by 90 degrees by the polarization plane rotation element 9 and enters the polarization selective diffraction grating 2. Then, the main beam MLB2, the first sub beam SLB21, and the second beam
Is diffracted into the sub-beam SLB 22, is converted into parallel light by the collimator lens 3, and enters the objective lens 5 via the half mirror 4. Then, the light is condensed by the objective lens 5 and
The signal recording surface 66a is irradiated as a spot SP2. The laser beam having a wavelength of 780 nm reflected by the signal recording surface 66a returns to the half mirror 4 via the objective lens 5, and half of the laser light is reflected by the half mirror 4 in the direction of the photodetector 88 and collected by the condenser lens 7. Main beam MLB2
Is the second detector 812 of the first sensor 81 of the photodetector 88
, The first sub-beam SLB21 is detected by the second sensor 82, and the second sub-beam SLB22 is detected by the third
Is detected by the sensor 83.

Further, using the optical pickup device 30,
When reproducing a signal from the DR, the liquid crystal driving circuit 260
No voltage is applied to the TN type liquid crystal 91 of the polarization plane rotation element 9 from. Accordingly, the laser light having a wavelength of 780 nm emitted from the second semiconductor laser 1B has its polarization plane rotated by 90 degrees by the polarization plane rotation element 9 and enters the polarization selective diffraction grating 2. Then, the polarization-selective diffraction grating 2 uses the main beam ML.
The light is diffracted by B2, the first sub-beam SLB21, and the second sub-beam SLB22, is converted into parallel light by the collimator lens 3, and is incident on the objective lens 5 via the half mirror 4. Then, the light is condensed by the objective lens 5 and the CD-R 6
6 is irradiated as a spot SP2 on the signal recording surface 66a. The laser beam having a wavelength of 780 nm reflected by the signal recording surface 66a returns to the half mirror 4 via the objective lens 5, and half of the laser light is reflected by the half mirror 4 in the direction of the photodetector 88 and collected by the condenser lens 7. Main beam MLB2
Is the second detector 812 of the first sensor 81 of the photodetector 88
, The first sub-beam SLB21 is detected by the second sensor 82, and the second sub-beam SLB22 is detected by the third
Is detected by the sensor 83.

Further, using the optical pickup device 30, C
When a signal is recorded in DR, no voltage is applied from the liquid crystal driving circuit 260 to the TN liquid crystal 91 of the polarization plane rotation element 9. Therefore, the laser light having a wavelength of 780 nm emitted from the second semiconductor laser 1B has its polarization plane 9
The light is rotated by 0 degrees and is incident on the polarization selective diffraction grating 2.
Then, the main beam MLB is polarized by the polarization selective diffraction grating 2.
2, diffracted into a first sub-beam SLB21 and a second sub-beam SLB22, converted into parallel light by a collimator lens 3, and incident on an objective lens 5 via a half mirror 4. Then, the light is condensed by the objective lens 5 and the CD-R 66
Is irradiated as a spot SP2 on the signal recording surface 66a. A pit is formed on the signal recording surface 66a to record a signal.

Referring to FIG. 29, optical pickup device 3
An optical disk device 400 using 0 will be described. The optical disk device 400 is an optical disk device 1 shown in FIG.
00 optical pickup device 10 and the optical pickup device 3
A liquid crystal drive circuit 260 is added instead of 0,
Other configurations are the same as those of the optical disc device 100. In this case, the control circuit 220 controls the liquid crystal drive circuit 260 so as to apply a voltage to the polarization plane rotating element 9 of the optical pickup device 30 or not to apply the voltage depending on the type of the recording medium mounted.

In the optical disk device 400, CD, C
The operation of reproducing a signal from the DR and DVD-ROM and recording the signal on the CD-R is the same as that described with reference to FIG. Also,
The operation of recording a signal on the DVD-RAM and reproducing the signal from the DVD-RAM is also performed by recording the signal on the CD-R,
The operation is basically the same as the operation of reproducing a signal from R. As described above, the optical pickup devices 10, 20, 30
When the distance between the first semiconductor laser 1A that emits a laser beam with a wavelength of 650 nm and the second semiconductor laser 1B that emits a laser beam with a wavelength of 780 nm deviates from a design value, the laser beam with a wavelength of 780 nm is used. And a focus error signal by the astigmatism method and a tracking error signal by the DPP method can be accurately generated.

The optical pickup devices 10, 20, 3
At 0, the objective lens 5 focuses and irradiates a laser beam having a wavelength of 650 nm on a recording medium having a substrate thickness of 0.6 mm,
When using an objective lens designed to be able to collectively irradiate a laser beam of 80 nm on a recording medium having a substrate thickness of 0.6 mm, which has been described as being able to collectively irradiate a laser beam having a substrate thickness of 1.2 mm, The difference in focusing laser light on a recording medium having a substrate thickness of 1.2 mm may be achieved by adopting a configuration in which a predetermined outer peripheral portion of the laser light is shielded. As a result, the substrate thickness is reduced to 0.
The laser beam can be focused and irradiated on the 6 mm recording medium and the 1.2 mm substrate thickness recording medium without aberration.

The optical pickup devices 10, 20, 3
Although the second detector 812 of the first sensor 81 of the photodetector 8 of 0 or 88 has been described as being divided into eight, the present invention is not limited to this.
It goes without saying that it may be divided into more parts. By dividing the laser beam into a larger number, a focus error signal by the astigmatism method can be obtained more accurately even when the optical axis of the laser beam having a wavelength of 780 nm is slightly shifted.

Further, in the above description, a case where two laser beams having different wavelengths are used has been described. However, the present invention is not limited to this, and a laser beam having a wavelength of 400 nm and a wavelength of 65 nm are used.
The present invention is also applicable to a case where laser light of 0 nm and laser light of a wavelength of 780 nm are used.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical pickup device according to the present invention.

FIG. 2 is a diagram illustrating a function of a polarization selective diffraction grating of the optical pickup device of FIG.

FIG. 3 is a diagram illustrating a function of a polarization selective diffraction grating of the optical pickup device of FIG.

FIG. 4 is a plan view of a photodetector of the optical pickup device of FIG. 1;

FIG. 5 is a diagram for explaining that a focus error signal can be accurately calculated by the astigmatism method even when the optical axis of the laser beam is deviated from the center of the detector.

FIG. 6 is a plan view of a CD and a CD-R.

FIG. 7 is a plan view of a DVD-ROM.

FIG. 8 shows a case where the substrate thickness is reduced by using the optical pickup device of FIG.
FIG. 3 is a diagram illustrating an operation of recording or reproducing a signal on a 6 mm recording medium.

9 shows a substrate thickness of 1. using the optical pickup device of FIG.
FIG. 3 is a diagram illustrating an operation of recording or reproducing a signal on a 2 mm recording medium.

FIG. 10 is a configuration diagram of an arithmetic circuit that can accurately calculate a focus error signal by the astigmatism method even when the optical axis of the laser light is shifted from the center of the detector.

FIG. 11 is a diagram showing a focus error signal calculated by the astigmatism method.

FIG. 12 is a configuration diagram of an arithmetic circuit that calculates a tracking error signal by the DPP method.

FIG. 13 is a configuration diagram of an arithmetic circuit that calculates a tracking error signal by a three-beam method.

FIG. 14 is a configuration diagram of an arithmetic circuit that calculates a tracking error signal by the DPD method.

FIG. 15 is a signal illustrating a process of calculating a tracking error signal by the DPD method.

FIG. 16 is a configuration diagram of an arithmetic circuit that calculates a reproduced signal.

FIG. 17 is a configuration diagram of an arithmetic circuit that calculates a reproduced signal.

FIG. 18 is a diagram illustrating a relationship between a first arithmetic circuit and a second arithmetic circuit.

FIG. 19 is a configuration diagram of an optical disk device according to the present invention.

FIG. 20 is another configuration diagram of the optical pickup device according to the present invention.

21 is a plan view of a photodetector of the optical pickup device of FIG.

22 is a diagram illustrating an operation of recording or reproducing a signal on or from a recording medium having a substrate thickness of 0.6 mm using the optical pickup device of FIG.

23 is a diagram illustrating an operation of recording or reproducing a signal on or from a recording medium having a substrate thickness of 1.2 mm using the optical pickup device of FIG.

FIG. 24 is another configuration diagram of the optical disc device according to the present invention.

FIG. 25 is still another configuration diagram of the optical pickup device according to the present invention.

FIG. 26 is a sectional structural view of the polarization plane rotator of FIG. 25;

FIG. 27 is a diagram illustrating an operation of recording or reproducing a signal on or from a recording medium having a substrate thickness of 0.6 mm using the optical pickup device of FIG.

28 is a diagram illustrating an operation of recording or reproducing a signal on or from a recording medium having a substrate thickness of 1.2 mm using the optical pickup device of FIG.

FIG. 29 is a diagram showing still another configuration of the optical disc device according to the present invention.

[Explanation of symbols]

1 laser light source, 1A first semiconductor laser, 1B
A second semiconductor laser, two polarization-selective diffraction gratings,
Reference Signs List 3 collimator lens, 4 half mirror, 5 objective lens, 6, 66 recording medium, 6a, 66a signal recording surface, 7 condenser lens, 8, 88 photodetector, 1
0, 20, 30 Optical pickup device, 11, 12
Pit row, 21 lattice, 22, 23 polarization plane, 81
First sensor, 82 second sensor, 83 third sensor
Sensor, 84 fourth sensor, 85 fifth sensor, 100, 300, 400 optical disk device, 11
0 1st arithmetic circuit, 120 2nd arithmetic circuit, 130
Third arithmetic circuit, 140 fourth arithmetic circuit, 150 fifth arithmetic circuit, 160 sixth arithmetic circuit, 170 reproduced signal amplification circuit, 180 servo circuit, 190 servo mechanism, 200 spindle motor, 210 decoding processing circuit, 220 control circuit, 230 modulation circuit, 24
0 drive signal generation circuit, 250 laser drive circuit, 2
60 liquid crystal drive circuit, 1200, 1210, 1220
Circuit, 1230 maximum peak detection circuit, 1240
S-shaped curve output circuit, 1106, 1107, 124
1, 1242, 1243, 1246, 1304 terminals,
1245 switch, 1201, 1202, 121
1, 1212, 1221, 1222, 1301, 130
2, 1401, 1402, 1501, 1502, 150
3, 1601, 1602, 1603 Adder, 110
1, 1102, 1105, 1203, 1213, 122
3, 1303 subtractor, 1104 multiplication circuit, 811
A first detector, 812 a second detector, 821, 822,
831, 832, 841, 842, 851, 852, 8
111, 8112, 8113, 8114, 8121, 8
122, 8123, 8124, 8125, 8126, 8
127, 8128 area, 1403, 1404 comparator, 1405 time difference detection circuit, 1406 LP
F

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Seiji Kajiyama 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in SANYO Electric Co., Ltd. 5D118 AA13 BA01 CA11 CA13 CA23 CA24 CB05 CC12 CD02 CD03 CF08 CF15 CF16 CG05 CG07 CG14 CG24 CG27 CG33 CG44 DA42 5D119 AA04 AA41 BA01 CA13 EA02 EA03 FA08 FA13

Claims (6)

[Claims] 1. An optical pickup device for recording and / or reproducing a signal on a recording medium using a laser beam, comprising: a first laser beam having a first wavelength; and a second laser beam having a second wavelength different from the first wavelength. A laser light source that selectively generates a second laser beam having a wavelength of 2 laser light by shifting the optical axis of the two laser beams, and among the first and second laser beams generated from the laser light source, A main beam from the second laser light,
A diffraction grating for generating a first sub-beam and a second sub-beam; a reflected light of the first laser light on the recording medium; a main beam generated from the second laser light; a first sub-beam And a photodetector for detecting a reflected light of the second sub-beam on the recording medium, wherein the photodetector comprises: A first sensor for detecting the generated reflected light of the main beam; a second sensor for detecting the reflected light of the first sub-beam; and a second sensor for the first sensor. A third sensor that is arranged on the opposite side of the sensor and detects the reflected light of the second sub-beam, wherein the first sensor detects the reflected light of the first laser light. A detection unit, the second laser light A second detector for detecting the reflected light of the generated main beam, wherein the second detector detects a peak of a signal calculated by an astigmatism method even when the optical axis of the reflected light is shifted. An optical pickup device in which four areas for performing an operation by the astigmatism method are divided so as to be maximal, so that the area can be changed. 2. The optical pickup device according to claim 1, wherein four regions are changed based on an optical signal input from each region of the second detection unit of the photodetector to perform an operation by an astigmatism method. A first arithmetic circuit for selectively outputting an S-shaped curve having a maximum peak; an S-shaped curve having a maximum peak from the first arithmetic circuit; an optical signal detected by the second sensor; An optical disc device comprising: a second arithmetic circuit that generates a tracking error signal from the optical signal detected by the third sensor by a DPP method. 3. An optical pickup device for recording and / or reproducing a signal on a recording medium using a laser beam, wherein the first laser beam has a first wavelength and a second laser beam different from the first wavelength. A laser light source for selectively generating a second laser beam having a wavelength of 2 by shifting the optical axes of the two laser beams; and a main beam from the first and second laser beams generated by the laser light source. A diffraction grating for generating the first and second sub-beams; a main beam generated from the first laser light;
And the reflected light of the main beam, the first sub-beam, and the second sub-beam generated from the second laser beam on the recording medium. A photodetector that detects the reflected light of the main beam generated from the first laser light, and the reflected light of the main beam generated from the second laser light. A first sensor that detects reflected light; a second sensor that detects the reflected light of the first sub-beam generated from the first laser light; and a second sensor that detects the reflected light. The second laser generated from the first laser light,
A third sensor that detects the reflected light of the sub-beam, a fourth sensor that detects the reflected light of the first sub-beam generated from the second laser light, The second sensor generated from the second laser light and disposed on the opposite side of the third sensor.
And a fifth sensor for detecting the reflected light of the sub-beam, wherein the first sensor detects the reflected light of the main beam generated from the first laser light, A second detector for detecting the reflected light of the main beam generated from the second laser light, wherein the second detector has astigmatism even when the optical axis of the reflected light is shifted. An optical pickup device in which four regions for performing calculation by the astigmatism method are divided so that the peak of a signal calculated by the method becomes maximum. 4. The optical pickup device according to claim 3, wherein four regions are changed based on an optical signal input from each region of the second detection unit of the photodetector to perform an operation by an astigmatism method. A first arithmetic circuit for selectively outputting an S-shaped curve having a maximum peak, an optical signal detected by the first detection unit, an optical signal detected by the second sensor, and the third sensor A second arithmetic circuit that generates a tracking error signal from the optical signal detected by the DPP method, an S-shaped curve having a maximum peak from the first arithmetic circuit, an optical signal detected by the fourth sensor, An optical disk device comprising: a third arithmetic circuit that generates a tracking error signal by a DPP method from the optical signal detected by the fifth sensor. 5. An optical pickup device for recording and / or reproducing a signal on a recording medium using a laser beam, comprising: a first laser beam having a first wavelength; and a second laser beam having a second wavelength different from the first wavelength. A laser light source for selectively generating a second laser light having a wavelength of 2 laser light by shifting the optical axes of the two laser lights, and selectively selecting a polarization plane of the first laser light generated from the laser light source. A polarization plane rotating element that transmits the second laser light generated from the laser light source as it is, and transmits a main beam from the second laser light transmitted through the polarization plane rotating element. And a second sub-beam, and a main beam and first and second sub-beams from the first laser light according to the polarization plane of the first laser light transmitted through the polarization plane rotation element. Generate A polarization-selective diffraction grating; reflected light of the first laser beam on the recording medium; and a main beam, a first sub-beam, and a second sub-beam generated from the first laser beam on the recording medium. And a photodetector for detecting the reflected light of the main beam, the first sub-beam, and the second sub-beam generated from the second laser light on the recording medium. The detector includes the reflected light of the first laser light, the reflected light of the main beam generated from the first laser light, and the reflected light of the main beam generated from the second laser light. A first sensor that detects reflected light; a second sensor that detects the reflected light of the first sub-beam generated from the first laser light; and a second sensor that detects the reflected light. Opposite side of sensor 2 Disposed, the second generated from the first laser beam
A third sensor that detects the reflected light of the sub-beam, a fourth sensor that detects the reflected light of the first sub-beam generated from the second laser light, And the second laser beam generated from the second laser beam is disposed on the opposite side of the fourth sensor.
A fifth sensor that detects the reflected light of the sub-beam of the first laser light, wherein the first sensor is configured to detect the reflected light of the first laser light and the main beam generated from the first laser light. A first detection unit that detects the reflected light; and a second detection unit that detects the reflected light of the main beam generated from the second laser light. Light that is divided into four areas for performing calculations by the astigmatism method so that the peak of the signal calculated by the astigmatism method is maximized even when the optical axis of the light is shifted. Pickup device. 6. An optical pickup device according to claim 5, wherein four regions are changed based on an optical signal input from each region of the second detection unit of the photodetector to perform an operation by an astigmatism method. A first arithmetic circuit for selecting and outputting an S-shaped curve having a maximum peak; a second arithmetic circuit for generating a tracking error signal by a DPD method from an optical signal detected by the first detection unit; A third arithmetic circuit that generates a tracking error signal by a DPP method from an optical signal detected by a detection unit, an optical signal detected by the second sensor, and an optical signal detected by the third sensor; A tracking error signal is obtained by a DPP method from an S-shaped curve having a maximum peak from the first arithmetic circuit, an optical signal detected by the fourth sensor, and an optical signal detected by the fifth sensor. Optical disk apparatus and a fourth operation circuit formed.