JP2001184706A - Optical pickup device and optical disk device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup device which is capable of recording and/or reproducing signals to and/or from an optical recording medium by eliminating the optical axis misalignment of two laser beams even when two semiconductor lasers are used and an optical disk device using the same. SOLUTION: The optical pickup device 10 has a laser beam source 1, a selective diffraction grating 2, a collimator lens 3, a half mirror 4, an objective lens 5, a condenser lens 7 and a photodetector 9. The laser beam source 1 includes the first semiconductor laser 1A, the second semiconductor laser 1B and an optical element 1C. The optical element 1C aligns the optical axis of the laser beam of 635 nm in wavelength emitted from the first semiconductor laser 1A and the optical axis of the laser beam of 780 nm in wavelength emitted from the second semiconductor laser 1B. The signals are recorded and/or reproduced to and from the optical recording medium 6 of 0.6 mm in substrate thickness and the optical recording medium 60 of 1.2 mm in substrate thickness by using the optical pickup device 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical pickup device capable of recording and / or reproducing signals on and from a plurality of optical disks using two laser beams having different wavelengths, 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 12 as the CD-ROM
A DVD that records 4.7 Gbytes of information on one side of an optical disk of cm is marketed. The thickness of a DVD disk is about 0.6 mm, and by bonding both sides thereof, information of 9.4 Gbytes can be recorded by one sheet.

Further, a magneto-optical recording medium has attracted 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 and the like. Is 6.0 Gb
Standardization of magneto-optical recording media of YTES has been promoted (AS-
MO (Advanced Storage Magn)
eto optical disk standard), and is being 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 reproduce only the transferred magnetic domains in the reproducing layer. M that forms a detection window and detects magnetic domains transferred from the formed detection window
SR (Magnetically Induced S)
The method is performed by an upper resolution method. A laser beam having a wavelength of 600 to 700 nm is used for recording and / or reproducing signals on the magneto-optical recording medium.

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

[0006]

However, currently proposed CD-R / DVD compatible pickups are DVD-compatible pickups.
In order to include in a single package a semiconductor laser that generates a laser beam having a wavelength of 635 nm for reproduction and a semiconductor laser that generates a laser beam for recording and reproducing a CD-R with a wavelength of 780 nm, two laser light beams are included. Off axis.

As a result, there has been a problem that it is difficult to detect two laser beams with one photodetector. It is also conceivable to provide two photodetectors corresponding to the two laser beams. However, in this case, the number of components increases, and there is a problem that the cost reduction and compactness of the optical pickup device are hindered. Therefore, the present invention solves such a problem, and an optical pickup device capable of recording and / or reproducing a signal on an optical recording medium by eliminating the optical axis shift of two laser beams even when two semiconductor lasers are used, and an optical pickup device therefor. It is an object of the present invention to provide an optical disc device using the same.

[0008]

The invention according to claim 1 is an optical pickup device for recording and / or reproducing a signal on a recording medium by using a laser beam, wherein the first semiconductor laser and the first semiconductor laser are provided. , An optical pickup device having a laser light source including a second semiconductor laser and an optical element. The first semiconductor laser generates a first laser beam having a first wavelength.

Further, the second semiconductor laser generates a second laser beam having a second wavelength different from the first wavelength. The optical element transmits the first laser light generated by the first semiconductor laser as it is, and transmits the second laser light generated by the second semiconductor laser to the optical axis of the first laser light. The light is transmitted substantially coincident with the optical axis of.

In the optical pickup device according to the first aspect, the first laser light generated from the first semiconductor laser and the second laser light generated from the second semiconductor laser are separated by an optical element. A laser light source whose optical axis is substantially aligned is emitted. Therefore, according to the first aspect of the invention, the reflected light of the first and second laser beams on the optical recording medium can be detected by one photodetector. Further, since an optical element for matching the optical axes of the two laser beams is included in the laser light source, there is no problem in downsizing the optical pickup device.

According to a second aspect of the present invention, there is provided an optical pickup device for recording and / or reproducing a signal on a recording medium by using a laser beam, comprising: a first semiconductor laser; a second semiconductor laser; An optical pickup device having a laser light source including an optical element. The first semiconductor laser generates a first laser beam having a first wavelength.

Further, the second semiconductor laser generates a second laser beam having a second wavelength different from the first wavelength. The optical element transmits the first laser light generated by the first semiconductor laser as it is, reflects the second laser light generated by the second semiconductor laser, and shifts the optical axis of the first laser light to the first laser light. Is transmitted substantially in accordance with the optical axis of the laser light.

In the optical pickup device according to the second aspect, the first laser light generated from the first semiconductor laser passes through the optical element as it is, and the second laser light generated from the second semiconductor laser. The laser light is reflected by the optical element and emitted from the laser light source while being substantially coincident with the optical axis of the first laser light. Therefore, according to the second aspect of the present invention, the optical axes of the two laser beams can be easily matched by using the optical component that selectively reflects the laser beams.

According to a third aspect of the present invention, in the optical pickup device according to the second aspect, the optical element comprises:
A first and a second surface transmitting the first laser light, a third surface transmitting the second laser light, and a third surface transmitting the first laser light and reflecting the second laser light. 4 is an optical pickup device including a fourth surface and a fifth surface that transmits the first and second laser beams.

In the optical pickup device according to the third aspect, the first laser beam passes through the first, second, fourth, and fifth surfaces, passes through the optical element, and passes through the second laser beam. Light passes through the third surface, is reflected by the fourth surface, passes through the fifth surface, and passes through the optical element. Then, when the second laser light is reflected by the fourth surface, its optical axis is made to coincide with the optical axis of the first laser light.

Therefore, according to the third aspect of the present invention, the optical axes of the two laser lights can be easily matched by using an optical component including one surface for selectively transmitting and reflecting the laser light. Let me do. Further, by making the directions in which the first and second laser beams enter the optical element differ by 90 degrees, it is possible to match the optical axis of the first laser beam by one reflection of the second laser beam. .

According to a fourth aspect of the present invention, in the optical pickup device according to the second aspect, the optical element comprises:
A first and a second surface transmitting the first laser light, a third surface transmitting the second laser light, a fourth surface reflecting the second laser light, and a first laser An optical pickup device including a fifth surface that transmits light and reflects a second laser light, and a sixth surface that transmits the first and second laser lights.

In the optical pickup device described in claim 4, the first laser beam passes through the first, second, fifth, and sixth surfaces, passes through the optical element, and passes through the second laser beam. Light passes through the third surface, is reflected by the fourth and fifth surfaces, passes through the sixth surface, and passes through the optical element. Then, when the second laser light is reflected by the fifth surface, its optical axis is made to coincide with the first laser light.

Therefore, according to the fourth aspect of the present invention, the optical axes of the two laser beams can be easily matched by using an optical component including one surface for selectively transmitting and reflecting the laser beam. Let me do. Further, even when the first and second laser beams are made to enter the optical element from the same direction, the optical axis of the first laser beam can be made coincident with the reflection of the second laser beam twice.

According to a fifth aspect of the present invention, in the optical pickup device according to the second aspect, the first semiconductor laser and the second semiconductor laser are arranged such that the emission surfaces of the laser light are in the same plane. And the laser light source comprises first and second
Further comprising a pedestal on which the semiconductor laser and the optical element are mounted, wherein the pedestal maintains a constant distance between the emission surfaces of the first and second semiconductor lasers and the optical element, and has a cutout for installing the optical element. An optical pickup device having:

In the optical pickup device according to the fifth aspect, the first and second semiconductor lasers are installed on the pedestal at the time of assembly so that the emission surfaces thereof are in the same plane, and the optical element is provided on the pedestal. It is installed in the cutout. Therefore, according to the invention described in claim 5, the first
In addition, the distance between the emission surface of the second semiconductor laser and the optical element can be kept constant, and the optical axes of the two laser beams can be accurately matched. Further, even if the size of the optical element is reduced, the optical element can be accurately set.

According to a sixth aspect of the present invention, a signal is transmitted to a first recording medium having a first substrate thickness and a second recording medium having a second substrate thickness larger than the first substrate thickness. An optical pickup device for performing recording and / or reproduction, which is an optical pickup device including a laser light source, an objective lens, and a wavelength-selective optical element. The laser light source includes a first semiconductor laser, a second semiconductor laser, and an optical element, wherein the first semiconductor laser generates a first laser light having a first wavelength, and a second semiconductor laser. Generates a second laser beam having a second wavelength different from the first wavelength,
The optical element includes a first semiconductor laser generated by the first semiconductor laser.
And the second laser light generated by the second semiconductor laser is transmitted with its optical axis substantially coincident with the optical axis of the first laser light.

Also, the objective lens is designed to be compatible with the first substrate thickness of the first recording medium, and emits the first and second laser beams respectively to the first recording medium and the second recording medium. The medium is focused and irradiated. The wavelength-selective optical element is provided between the objective lens and the laser light source, transmits the first laser light as it is, guides the first laser light to the objective lens, and bends the second laser light outward from the optical axis. Only the predetermined inner peripheral portion is guided to the objective lens.

In the optical pickup device according to the sixth aspect, the first laser light generated from the first semiconductor laser passes through the optical element as it is and is emitted from the laser light source, and the wavelength selective optical element is also used. The light is transmitted as it is, enters the objective lens, and is condensed and irradiated on the first recording medium. on the other hand,
The second laser light generated from the second semiconductor laser is made to coincide with the optical axis of the first laser light by the optical element, emitted from the laser light source, and bent outward from the optical axis by the wavelength-selective optical element. Then, only the inner peripheral portion is incident on the objective lens, and is condensed and irradiated on the second recording medium.

Therefore, according to the invention described in claim 6, signals are recorded on a plurality of recording media having different substrate thicknesses and / or
Alternatively, even when two semiconductor lasers are used for reproduction, the optical axes of the two laser beams can be easily matched. Further, even if the objective lens is designed for a recording medium having a thin substrate, the laser beam can be focused and irradiated onto the recording medium having a large substrate without aberration using the objective lens.

According to a seventh aspect of the present invention, there is provided an optical pickup device according to any one of the first to sixth aspects, and selectively driving the first and second semiconductor lasers included in the laser light source. An optical disk device including a laser drive circuit. According to a seventh aspect of the present invention, in the optical disk device, the first semiconductor laser and the second semiconductor laser included in the optical pickup device according to any one of the first to sixth aspects are a laser driving circuit. To perform signal recording and / or reproduction on the optical recording medium.

Therefore, according to the invention described in claim 7, it is possible to record and / or reproduce a signal on the optical recording medium in a state where the optical axes of the two laser beams are not shifted.

[0028]

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

The laser light source 1 includes a first semiconductor laser 1A
And a second semiconductor laser 1B and an optical element 1C. The first semiconductor laser 1A has a wavelength of 635 nm.
(Permissible error ± 15 nm), and the second semiconductor laser 1B generates a laser beam having a wavelength of 780 nm (permissible error ± 15n).
m) is generated. The optical element 1C has a wavelength 63 emitted from the first semiconductor laser 1A as described later.
The optical axis of the 5 nm laser light is made to coincide with the optical axis of the 780 nm laser light emitted from the second semiconductor laser 1B. Therefore, the laser light source 1 selectively drives the laser light having a wavelength of 635 nm and the laser light having a wavelength of 780 nm by the laser driving circuit 20, and emits the two laser lights while making their optical axes coincide.

The selective diffraction grating 2 transmits the laser beam having a wavelength of 635 nm as it is, diffracts the laser beam having a wavelength of 780 nm, and emits a main beam and two sub beams.
In this case, the selective diffraction grating 2 may diffract only the laser light having a wavelength of 780 nm based on the difference in the wavelength of the laser light, and may diffract the laser light having a wavelength of 780 n based on the difference in the polarization plane of the laser light.
m may be diffracted. When diffracting only a laser beam having a wavelength of 780 nm based on the polarization plane of the laser beam, the polarization plane of the laser beam having a wavelength of 780 nm and the wavelength 635 are used.
The first semiconductor laser 1A and the second semiconductor laser 1B are installed so that the polarization plane of the laser light of nm is different.

The collimator lens 3 converts the laser light having a wavelength of 780 nm and the laser light having a wavelength of 635 nm into parallel light. The half mirror 4 transmits the laser light with a wavelength of 635 nm and the laser light with a wavelength of 780 nm from the collimator lens 3 and halves the reflected light of the two laser lights on the signal recording surface 6 a or 60 a of the optical recording medium 6 or 60. Is reflected in the direction of the photodetector 8.

The objective lens 5 transmits a laser beam having a wavelength of 635 nm to a signal recording surface 6a of an optical recording medium 6 having a substrate thickness of 0.6 mm.
780nm wavelength laser light with a substrate thickness of 1.2m
The light is condensed and irradiated on the signal recording surface 60a of the optical recording medium 60 of m. 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 60 having a substrate thickness of 1.2 mm. Such an objective lens is disclosed in, for example, JP-A-10-143905. Therefore, if such an objective lens is used, the laser beam having a wavelength of 635 nm is focused on the signal recording surface 6a of the optical recording medium 6 having a substrate thickness of 0.6 mm without selectively shielding the outer peripheral portion of the laser beam. Then, a laser beam having a wavelength of 780 nm is applied to the signal recording surface 6 of the optical recording medium 60 having a substrate thickness of 1.2 mm.
0a can be focused and irradiated.

The condensing lens 7 condenses the laser light reflected by the half mirror 4, and the photodetector 8 detects the laser light condensed by the condensing lens 7. Laser drive circuit 20
Selectively drives the first semiconductor laser 1A and the second semiconductor laser 1B included in the laser light source 1. The optical pickup device 10 has the selective diffraction grating 2 because
The focus servo of the objective lens 5 when recording or reproducing a signal on or from a CD or CD-R, which is an optical recording medium having a substrate thickness of 1.2 mm, irradiates the CD and CD-R with three beams. A so-called DPP (Differential) that detects a reflected light and generates a focus error signal.
The focus servo of the objective lens 5 when reproducing a signal from a DVD which is an optical recording medium having a substrate thickness of 0.6 mm using the Push Pull) method irradiates the DVD with one beam and detects the reflected light of the one beam. This is because a so-called astigmatism method is used to generate a focus error signal.

The operation of the optical pickup device 10 will be described. Wavelength 635 emitted from laser light source 1
The laser light of nm passes through the selective diffraction grating 2 as it is, is converted into parallel light by the collimator lens 3, passes through the half mirror 4, and enters the objective lens 5. Then, the light is condensed by the objective lens 5 and is condensed and irradiated on the signal recording surface 6a of the optical recording medium 6. Wavelength 63 reflected by signal recording surface 6a
The 5 nm laser light returns to the half mirror 4 via the objective lens 5, is half-reflected by the half mirror 4, is collected by the condenser lens 7, and is detected by the photodetector 8.

The wavelength 7 emitted from the laser light source 1
The 80 nm laser light is diffracted into a main beam and two sub-beams by the selective diffraction grating 2, converted into parallel light by the collimator lens 3, and then passes through the half mirror 4 to enter the objective lens 5. Then, the light is condensed by the objective lens 5 and is condensed and irradiated on the signal recording surface 60a of the optical recording medium 60. The laser light having a wavelength of 780 nm reflected by the signal recording surface 60a returns to the half mirror 4 via the objective lens 5, is half-reflected by the half mirror 4, is condensed by the condenser lens 7, and is condensed by the photodetector 8. Is detected.

The details of the laser light source 1 will be described with reference to FIGS. Referring to FIG. 2, laser light source 1
Includes a pedestal 1D, a first semiconductor laser 1A, and a second
The semiconductor laser 1B and the optical element 1C are installed on a base 1D. The first semiconductor laser 1A has a wavelength of 635 n
m laser beam LB1 is installed so as to go straight and pass through the optical element 1C, and the second semiconductor laser 1B is arranged in the radial direction or the track direction of the optical recording medium 6 or 60 with respect to the first semiconductor laser 1A. It is located at a shifted position. First
The distance between the semiconductor laser 1A and the second semiconductor laser 1B is 100 to 300 μm. Then, the laser light LB having a wavelength of 780 nm emitted from the second semiconductor laser 1B
2 is an optical element having a wavelength of 635 after entering the optical element 1C.
The optical element 1C is aligned with the optical axis of the laser beam LB1 of nm.
Is emitted.

FIG. 3 is a plan view of the laser light source 1 in FIG. 2 as viewed from above. The optical element 1C has a first surface 1C
1, a second surface 1C2, a third surface 1C3, a fourth surface 1C4, a fifth surface 1C5, and a sixth surface 1C6. The emission point SPA of the laser light of the first semiconductor laser 1A and the emission point SPB of the laser light of the second semiconductor laser 1B are on the same line 21 (three-dimensionally on the same plane. 2), the first semiconductor laser 1A and the second semiconductor laser 1B are set on the base 1D. Wavelength 635 emitted from first semiconductor laser 1A
The laser beam LB1 of nm enters the optical element 1C from the first surface 1C1, passes through the second surface 1C2, the third surface 1C3, and the fourth surface 1C4, and exits the optical element 1C.
On the other hand, the wavelength 780n emitted from the second semiconductor laser 1B
m of the optical element 1 from the fifth surface 1C5.
C, the light is reflected by the sixth surface 1C6 and the third surface 1C3, passes through the fourth surface 1C4, and exits the optical element 1C. Then, when reflected by the third surface 1C3, the wavelength 635
The optical axis can be matched with the laser beam LB1 of nm. Therefore, the third surface 1C3 is provided with a laser beam LB having a wavelength of 635 nm.
1 and has a function of reflecting a laser beam LB2 having a wavelength of 780 nm.

In the laser light source 1, the distance between the emission point SPA of the laser light of the first semiconductor laser A and the incident surface 1C1 of the optical element 1C, and the emission point SPB of the laser light of the second semiconductor laser 1B and the optical point It is necessary to keep the distance to the incident surface 1C5 of the element 6 constant. Therefore, as shown in FIG. 4, the pedestal 1 </ b> D of the laser light source 1 preferably has a notch 22. The notch 22 is formed parallel to the emission surface of the first semiconductor laser 1A and the emission surface of the second semiconductor laser 1B. Thereby, the optical element 1C can be easily installed on the pedestal 1D, and the emission point SPA of the laser light of the first semiconductor laser A and the incident surface 1 of the optical element 1C.
The distance to C1 and the distance between the emission point SPB of the laser light of the second semiconductor laser 1B and the incident surface 1C5 of the optical element 1C can be kept constant.

Referring to FIG. 5, optical pickup device 10
The operation in the case of reproducing a signal from the optical recording medium 6 having a substrate thickness of 0.6 mm using FIG. Laser drive circuit 2
0, the first semiconductor laser 1A in the laser light source 1 is selectively driven, and a wavelength of 635 n
m laser light is emitted. Emitted wavelength 635nm
As described above, the laser beam passes through the optical element 1C as it is, passes through the selective diffraction grating 2 as it is, is converted into parallel light by the collimator lens 3, and then passes through the half mirror 4 to the objective lens 5. Incident. The laser beam having a wavelength of 635 nm incident on the objective lens 5 is condensed by the objective lens 5 and is condensed and irradiated on the signal recording surface 6a of the optical recording medium 6. The laser light having a wavelength of 635 nm reflected by the signal recording surface 6a returns to the half mirror 4 via the objective lens 5, and is half reflected by the half mirror 4. Half mirror 4
The laser light having a wavelength of 635 nm reflected by the
And is detected by the photodetector 8. Thereby, a signal is reproduced from the optical recording medium 6.

Referring to FIG. 6, optical pickup device 10
The operation of recording and / or reproducing a signal on / from the optical recording medium 60 having a substrate thickness of 1.2 mm will be described with reference to FIG. First, an operation of recording a signal will be described. Laser drive circuit 20
, The second semiconductor laser 1B included in the laser light source 1
Is selectively driven. In this case, the second semiconductor laser 1B
Are driven based on a drive signal modulated by a recording signal. Wavelength 780n emitted from the second semiconductor laser 1B
As described above, the laser light of m is emitted from the laser light source 1 after the optical axis is made to coincide with the laser light of 635 nm in wavelength by the optical element 1C. Then, the light is diffracted into a main beam and two sub-beams by the selective diffraction grating 2, converted into parallel light by the collimator lens 3, transmitted through the half mirror 4, and enters the objective lens 5. The laser light having a wavelength of 780 nm incident on the objective lens 5 is condensed by the objective lens 5 and is condensed and irradiated on the signal recording surface 60a of the optical recording medium 60. Thus, a signal is recorded on the optical recording medium 60.

Next, the operation of reproducing a signal from the optical recording medium 60 will be described. The second semiconductor laser 1B is selectively driven by the laser drive circuit 20, and the optical recording medium 60
The operation until the signal recording surface 60a is focused and irradiated is the same as the case of the recording operation. The laser light having a wavelength of 780 nm reflected by the signal recording surface 60a returns to the half mirror 4 via the objective lens 5, and is half reflected by the half mirror 4. The laser light having a wavelength of 780 nm reflected by the half mirror 4 is condensed by the condenser lens 7 and detected by the photodetector 8. Thus, a signal is reproduced from the optical recording medium 60.

The laser light source used in the optical pickup device 10 is not limited to the laser light source 1 shown in FIGS. 2, 3, and 4, but may be a laser light source 30 shown in FIG. Laser light source 3
0 includes a first semiconductor laser 1A, a second semiconductor laser 1B, an optical element 30C, and a pedestal 1D. In the laser light source 30, the first semiconductor laser 1A and the second semiconductor laser 1B are arranged such that their respective emission surfaces are in different planes, and the wavelength of the 635 nm wavelength emitted from the first semiconductor laser 1A is The laser beam LB1 and the laser beam LB2 having a wavelength of 780 nm emitted from the second semiconductor laser 1B enter the optical element 30C from different directions.

Referring to FIG. 8, first semiconductor laser 1A
The emission point SPA of the laser light is located on the line 24, and the emission point SPB of the laser light of the second semiconductor laser 1B is located on the line 25. The line 24 and the line 25 make a right angle.
Therefore, in the laser light source 30, the first semiconductor laser 1A and the second semiconductor laser 1B are arranged such that the emission surfaces thereof form a right angle. The optical element 30C includes a first surface 30C1, a second surface 30C2, and a third surface 30C3.
And a fourth surface 30C4 and a fifth surface 30C5. Wavelength 635 nm emitted from the first semiconductor laser 1A
Of the optical element 3 from the first surface 30C1.
0C, the second surface 30C2, the third surface 30C3,
Then, the light passes through the fourth surface 30C4 and exits from the optical element 30C. On the other hand, the laser light having a wavelength of 780 nm emitted from the second semiconductor laser 1B enters the optical element 30C from the fifth surface 30C5, is reflected by the third surface 30C3, and
And exits the optical element 30C through the surface 30C4. Then, the laser light LB2 having a wavelength of 780 nm is applied to the third surface 3
When reflected at 0C3, the laser light L having a wavelength of 635 nm
The optical axis can be matched with B1. Therefore, the third surface 30C
3 transmits a laser beam LB1 having a wavelength of 635 nm and a wavelength of 7
It has a function of reflecting the laser beam LB2 of 80 nm.

Referring to FIG. 9, pedestal 1D preferably has a notch 23. Optical element 3 in notch 23
By setting 0C, the distance between the first semiconductor laser 1A and the optical element 30C can be kept constant, and the distance between the second semiconductor laser 1B and the optical element 30C can be kept constant. An optical disk device 100 using the optical pickup device 10 will be described with reference to FIG. The optical disc device 100 includes an optical pickup device 10, a reproduction signal amplification circuit 11, a servo circuit 12, a servo mechanism 13,
A spindle motor 14, a waveform equalizing circuit 15, an A / D
A conversion circuit 16, a decoding circuit 17, an encoder 18,
A modulation circuit 19 and a laser driving circuit 20 are provided.

As described above, the optical pickup device 10 receives the laser light from the first semiconductor laser 1A and the second semiconductor laser 1A.
The optical recording medium 6 or 60 is irradiated with the laser light from the semiconductor laser 1B of the above with the optical axes thereof substantially coincident with each other, and the reflected light is detected. The reproduction signal amplification circuit 11 amplifies the focus error signal, the tracking error signal, and the reproduction signal detected by the optical pickup device 10 to predetermined levels, outputs the focus error signal and the tracking error signal to the servo circuit 12, and reproduces the signal. The signal is output to the waveform equalization circuit 15.

The servo circuit 12 performs a servo mechanism 13 so as to perform focus servo and tracking servo of the objective lens 5 of the optical pickup device 10 based on the input focus error signal and tracking error signal.
And the spindle motor 14 is rotated at a predetermined rotation speed. The servo mechanism 13 performs focus servo and tracking servo of the objective lens 5 in the optical pickup device 10 based on control from the servo circuit 12. The spindle motor 14 is connected to the optical recording medium 6 or 60
Is rotated at a predetermined rotation speed.

The waveform equalizing circuit 15 includes the reproduced signal amplifying circuit 1
Waveform equalization is performed so that the level on the high frequency side of the reproduction signal input from 1 is almost equal to the level on the low frequency side. A / D conversion circuit 1
6 converts the reproduction signal input from the waveform equalization circuit 15 into a digital signal. The decoding circuit 17 decodes the input digital signal and outputs it as reproduction data. The encoder 18 encodes the recording data. Modulation circuit 19
Modulates the encoded recording signal into a predetermined format. The laser drive circuit 20 drives the second semiconductor laser 1B in the optical pickup device 10 based on the recording signal input from the modulation circuit 10 when recording a signal. When reproducing a signal, the laser drive circuit 20 operates the first and second semiconductor lasers 1 in the optical pickup device 10.
A and 1B are driven so as to emit laser light of a predetermined intensity.

When the optical recording medium 6 having a substrate thickness of 0.6 mm is mounted on the optical disk device 100, the optical recording medium 6 is rotated at a predetermined rotation speed by a spindle motor 14 and mounted by a recording medium discriminating circuit (not shown). The determined optical recording medium is determined to be an optical recording medium having a substrate thickness of 0.6 mm, and a control circuit (not shown) drives the first semiconductor laser 1A of the optical pickup device 10 based on the determination result. A control signal is output to drive circuit 20.

Then, the laser drive circuit 20 drives the first semiconductor laser 1A in the optical pickup device 10, the first semiconductor laser 1A generates a laser beam having a wavelength of 635 nm, and the optical pickup device 10 As described above, the optical recording medium 6 is irradiated with the laser light having the wavelength of 635 nm, and the reflected light is detected. When the focus error signal and the tracking error signal are detected by the optical pickup device 10, the focus servo and the tracking servo of the objective lens 5 in the optical pickup device 10 are turned on as described above. Thereafter, the optical pickup device 10 detects a reproduction signal by detecting a change in reflected light intensity based on a pit formed on the optical recording medium 6. The detected reproduction signal is supplied to the reproduction signal amplification circuit 1
1, via the waveform equalization circuit 15, the A / D conversion circuit 16, and the decoding circuit 17, are output as reproduction data as described above.

Next, an optical recording medium 60 having a substrate thickness of 1.2 mm
Is mounted on the optical disc device 100, the optical recording medium 6
0 is rotated at a predetermined number of revolutions by the spindle motor 14, and the mounted optical recording medium is determined to be an optical recording medium having a substrate thickness of 1.2 mm by a recording medium determination circuit (not shown), and based on the determination result. Optical pickup device 1
A control signal is output from the control circuit (not shown) to the laser drive circuit 20 so as to drive the second semiconductor laser 1B.

Then, the laser driving circuit 20 drives the second semiconductor laser 1B in the optical pickup device 10, the second semiconductor laser 1B generates laser light having a wavelength of 780 nm, and the optical pickup device 10 As described above, the optical recording medium 60 is irradiated with the laser light having the wavelength of 780 nm, and the reflected light is detected. Subsequent operation is 0.6m
Since this is the same as the case where the optical recording medium 6 having the thickness of m is mounted, the description thereof is omitted.

Further, an optical recording medium 60 having a substrate thickness of 1.2 mm
The case where a signal is recorded on the substrate will be described.
The operation until the 2 mm optical recording medium 60 is mounted and 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. afterwards,
The recording data is encoded by an encoder 18 and modulated by a modulation circuit 19 in a predetermined manner.
Input to 0. In addition, since a control signal is input from a control circuit (not shown) to the laser drive circuit 20 so as to drive the second semiconductor laser 1B in the optical pickup device 10, the laser drive circuit 20 operates based on the recording signal. Second semiconductor laser 1B so that the laser beam intensity changes
Drive. Thus, the optical pickup device 10 irradiates the optical recording medium 60 with a laser beam having a wavelength of 780 nm, the intensity of which changes based on the recording signal, and the signal is transmitted to the optical recording medium 60.
Is irradiated.

Referring to FIG. 11, another optical pickup device according to the present invention will be described. The optical pickup device 40 is obtained by adding a wavelength-selective optical element 600 to the optical pickup device 10 shown in FIG. 1 and using an objective lens 50 instead of the objective lens 5. Objective lens 50
Is a wavelength of 635 nm on the optical recording medium 6 having a substrate thickness of 0.6 mm.
Is an objective lens designed to be able to collect and irradiate a laser beam of a wavelength of 780 nm.
m is a lens that generates aberration when irradiated on the optical recording medium of m. That is, the objective lens 50 is a lens that causes aberration when irradiating the optical recording medium having a substrate thickness different from the substrate thickness used for the design with laser light. In addition,
The numerical aperture of the objective lens 50 is 0.6 (allowable error ± 0.0
5).

Therefore, in the optical pickup device 40, the wavelength-selective optical element 600 is used to remove the aberration generated when the laser beam having a wavelength of 780 nm is focused and irradiated on the optical recording medium 60 having a substrate thickness of 1.2 mm. Used. As described later, the wavelength-selective optical element 600 transmits a laser beam having a wavelength of 635 nm while maintaining its incident intensity and enters the objective lens 50, and transmits a laser beam having a wavelength of 780 nm while maintaining the incident intensity. The laser beam is diffracted into a laser beam in a desired direction and enters only the predetermined inner peripheral portion into the objective lens 50.

When recording a signal on a CD-R, as will be described later, the optical pickup device 40 can reduce the power of the laser light having a wavelength of 780 nm emitted from the second semiconductor laser 1B without substantially reducing the power of the CD. The signal recording surface 60a of -R is condensed and irradiated to record a signal. 12 and 13, the wavelength-selective optical element 60
0 will be described in detail. Referring to FIG. 12, a wavelength-selective optical element 600 includes a first material 602 formed on a surface of a light-transmitting substrate 601 such as glass, and the first material 60.
2 is a structure in which a second material 603 is formed so as to cover the second material 603. The first material 602 is formed at a predetermined interval substantially concentrically with respect to the optical axis L0, and is formed of, for example, a hologram. Therefore, the first material 602 has a wavelength of 635 n
It has the same refractive index of 2.3 for the laser light of m and the laser light of the wavelength of 780 nm. On the other hand, the second material 603
Is made of, for example, silicon nitride (SiN), has a refractive index of 2.3 with respect to a laser beam having a wavelength of 635 nm, and has a refractive index of 1.3 with respect to a laser beam having a wavelength of 780 nm.
It has a refractive index of 8.

Referring to FIG. 13A, a cross-sectional structure of the wavelength-selective optical element 600 on an arbitrary plane including the optical axis L0 will be described. A first material 602 having a right-angled triangle shape is provided on the surface of a light-transmitting substrate 601 at predetermined intervals with an optical axis L0.
Are formed symmetrically with respect to. The height of the first material 602 is 0.337 μm, and the interval is 29 at the innermost periphery.
6.43 μm, and 31.256 μm at the outermost periphery, and the distance gradually decreases from the inner periphery toward the outer periphery. The second material 603 is formed of a light-transmitting substrate 601.
And is formed so as to cover the first material 602.

FIG. 13B shows a wavelength-selective optical element 6.
00 is a plan view of the structure of FIG. The first material 602 is formed substantially concentrically on the surface of the light-transmitting substrate 601. Also, it is clear that the interval between the concentric circles is narrower toward the outer periphery. The optical characteristics of the optical element 600 will be described with reference to FIG. With reference to FIG.
Since the first material 602 has a refractive index of 2.3 and the second material 603 also has a refractive index of 2.3 with respect to the laser light of nm, the laser light LB1 having a wavelength of 635 nm incident on the optical element 600 is used. Is transmitted as the laser beam LB1 without being diffracted by the wavelength-selective optical element 600. As a result, the power of the laser light having a wavelength of 635 nm does not decrease even if it passes through the wavelength-selective optical element 600.

On the other hand, referring to FIG.
For 80 nm laser light, the first material 602 has a refractive index of 2.3, the second material 603 has a refractive index of 1.8, and the first material 602 is a second material. The optical element 60 has a gentle slope 604 at the interface with the optical element 60.
The laser light LB2 having a wavelength of 780 nm incident on the first material 602 from the first material 602 through the inclined surface 604.
At the time of incidence on light 03, it is diffracted from the optical axis to the outer peripheral side, and transmits through the wavelength-selective optical element 600 as diffracted light LB3.

In the case where the first material 602 is the material 700 having a step shape at the interface with the second material 603, the wavelength 78
The laser beam LB2 of 0 nm is transmitted from the first material 700 to the second
0th order light LB20 and +1 when entering the material 603
The light is diffracted into the next order light LB21 and the minus first order light LB22. Therefore, these three diffracted lights LB20, LB21, LB2
When one of the two diffracted lights is used, the power of the laser light is reduced. However, in the wavelength-selective optical element 600 of the present application, the first material 602 has a gentle slope 60.
4, the laser beam LB2 having a wavelength of 780 nm
For example, almost 100% is diffracted by the primary light LB3. Therefore, there is almost no decrease in power due to the laser beam LB2 passing through the wavelength selective optical element 600.

Referring to FIG. 15, wavelength-selective optical element 6
The laser beam LB2 having a wavelength of 780 nm incident on 00 is diffracted in a desired direction by the wavelength-selective optical element 600 and passes through the wavelength-selective optical element 600 as diffracted light LB3.
Out of the diffracted light LB3 that has passed through the wavelength-selective optical element 600, the outer peripheral portion LB3EX does not enter the objective lens 50, and only a predetermined inner peripheral portion LB3IN enters the objective lens 50. Therefore, the wavelength-selective optical element 600 has a wavelength of 780.
The laser beam LB2 of nm is diffracted into diffracted light LB3 in a desired direction, and only a predetermined inner peripheral portion LB3IN is incident on the objective lens 50. Further, since the distance between the first materials 602 of the wavelength-selective optical element 600 gradually decreases from the inner peripheral portion toward the outer peripheral portion, the diffraction angle differs between the inner peripheral portion and the outer peripheral portion. The wavelength-selective optical element 600 has the same function as diffracting laser light using a lens.

Referring to FIG. 16, optical pickup device 4
An operation when reproducing a DVD having a substrate thickness of 0.6 mm using 0 will be described. When playing a DVD, the first semiconductor laser 1A of the laser light source 1 is selectively driven. The laser light having a wavelength of 635 nm emitted from the laser light source 1 passes through the selective diffraction grating 2 as it is, is made parallel by the collimator lens 3, passes through the half mirror 4, and enters the wavelength selective optical element 600. In this case, since the laser light passes through the half mirror 4 with a transmittance of about 98%, there is almost no reduction in power due to passing through the half mirror 4.

The laser beam that has entered the wavelength-selective optical element 600 passes through the same while maintaining the incident intensity, and enters the objective lens 50. The laser light incident on the objective lens 50 is condensed by the objective lens 50 and is irradiated on the signal recording surface 6a of the DVD 6. The reflected light reflected by the signal recording surface 6a is reflected by the objective lens 50 and the wavelength-selective optical element 6
Returning to the half mirror 4 via 00, the half mirror 4
Is reflected halfway and enters the condenser lens 7. Then, the light is condensed by the condensing lens 7, condensed and irradiated on the light detector 8, and detected by the light detector 8.

Referring to FIG. 17, optical pickup device 4
The operation when recording and / or reproducing signals on a CD-R having a substrate thickness of 1.2 mm using 0 will be described. C
When recording and / or reproducing signals on the DR, the second semiconductor laser 1B of the laser light source 1 is selectively driven. First, a signal recording operation will be described. CD-R
When a signal is recorded on the second semiconductor laser 1B, a laser beam having an intensity of 70 mW is emitted from the second semiconductor laser 1B. The laser light having a wavelength of 780 nm emitted from the laser light source 1 is diffracted into a main beam and two sub-beams by a selective diffraction grating 2, converted into parallel light by a collimator lens 3, transmitted through a half mirror 4, and passed through a wavelength selective optics. Light enters the element 600. Also in this case, since the laser light passes through the half mirror 4 with a transmittance of about 98%, there is almost no reduction in power due to passing through the half mirror 4.

The laser beam incident on the wavelength-selective optical element 600 is diffracted while maintaining its incident intensity, and only a predetermined inner peripheral portion enters the objective lens 50. Objective lens 50
Is incident on the objective lens 50 and is focused on the CD.
-Irradiated on the signal recording surface 60a of R60. When recording a signal, since the laser beam is modulated by the recording signal, the signal is recorded by irradiating the modulated laser beam having a wavelength of 780 nm to the signal recording surface 60a.

The second semiconductor laser 1B having an intensity of 70 mW
The laser light having a wavelength of 780 nm emitted by the laser beam is reduced in intensity by about 2% by the half mirror 4 and enters the wavelength-selective optical element 600. Then, the light passes through the wavelength-selective optical element 600 while being diffracted while maintaining the intensity, and only a predetermined inner peripheral portion enters the objective lens 50. In this case, the predetermined inner peripheral portion is such that the effective numerical aperture of the objective lens 50 having a numerical aperture of 0.6 is 0.50.
This is an area within the range of 0.53. When the effective luminous flux of the laser light having a wavelength of 780 nm is 4.46 mm, the diameter of the predetermined inner peripheral portion where the effective numerical aperture of the objective lens 50 is in the range of 0.50 to 0.53 is 3.2 to 3 0.4 mm. Therefore, the intensity of the laser light incident on the objective lens 50 is 70 mW × 0.98 × (diameter of the inner peripheral portion to be effectively used / effective light flux of the laser light) = 49 to 52 mW. As a result, with the use of the optical pickup device 40, the signal recording surface 60a of the CD-R can be irradiated with laser light having a wavelength of 780 nm without substantially lowering the intensity immediately after the emission of the second semiconductor laser 1B. Records can be made.

Next, the operation of signal reproduction will be described.
When reproducing a signal from the CD-R, a laser beam having an intensity of 12 mW is emitted from the second semiconductor laser 1B. As described above, the laser light having a wavelength of 780 nm emitted from the laser light source 1 hardly decreases its intensity.
The signal is irradiated onto the signal recording surface 60a of the CD-R 60. Then, the reflected light reflected on the signal recording surface 60a is guided to the photodetector 8 in the same manner as described with reference to FIG. 16, and the signal is reproduced.

The laser light source 30 may be used for the optical pickup device 40. An optical disk device using the optical pickup device 40 is an optical disk device 10 shown in FIG.
0 optical pickup device 10 and optical pickup device 40
Other configurations and operations are shown in FIG.
It is the same as the description. Therefore, the optical pickup device 40
Substrate thickness of 0.6 mm
A signal can be recorded and / or reproduced on and from an optical recording medium having a substrate thickness of 1.2 mm.

In the above description, when the first semiconductor laser 1A included in the optical pickup devices 10 and 40 is used, it is described that only signal reproduction is performed. However, when the optical pickup device 40 is used, recording is performed. A signal can be recorded and / or reproduced on a magneto-optical recording medium which is a possible optical disk. In that case, a signal can be recorded while maintaining the intensity immediately after the light is emitted from the first semiconductor laser 1A.

As described above, by using the optical pickup devices 10 and 40, the optical axes of the two laser beams are made substantially coincident with each other so that the optical recording medium having the substrate thickness of 0.6 mm and the optical recording medium having the substrate thickness of 1.2 mm are used. Recording a signal on an optical recording medium and / or
Or playback can be performed.

[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 perspective view of the laser light source of FIG.

FIG. 3 is a top plan view of the laser light source of FIG. 2;

FIG. 4 is a preferred example of a pedestal shown in FIG. 2;

FIG. 5 is a diagram illustrating an operation of reproducing a signal from an optical recording medium having a substrate thickness of 0.6 mm using the optical pickup device shown in FIG.

FIG. 6 is a diagram illustrating an operation of recording a signal on and / or reproducing a signal from an optical recording medium having a substrate thickness of 1.2 mm using the optical pickup device shown in FIG.

FIG. 7 is a perspective view of another laser light source used in the optical pickup device shown in FIG.

8 is a top plan view of the laser light source of FIG.

FIG. 9 is a preferred example of the pedestal shown in FIG. 8;

10 is a configuration diagram of an optical disc device using the optical pickup device shown in FIG.

FIG. 11 is a diagram showing another configuration of the optical pickup device according to the present invention.

FIG. 12 is a perspective view of the wavelength-selective optical element of FIG.

13 is a sectional view and a plan view of the wavelength-selective optical element of FIG.

FIG. 14 is a diagram illustrating optical characteristics of the wavelength-selective optical element in FIG.

FIG. 15 is a diagram illustrating a path of a laser beam having a wavelength of 780 nm from a wavelength-selective optical element to an objective lens.

16 is a diagram illustrating a recording or reproducing operation of an optical disk having a substrate thickness of 0.6 mm using the optical pickup device shown in FIG.

17 is a diagram illustrating a recording or reproducing operation of an optical disc having a substrate thickness of 1.2 mm using the optical pickup device shown in FIG.

[Explanation of symbols]

Reference Signs List 1 laser light source, 1A first semiconductor laser, 1B second semiconductor laser, 1C optical element, 1D pedestal, 1C
1 1st surface, 1C2 2nd surface, 1C3 3rd surface,
1C4 fourth surface, 1C5 fifth surface, 1C6 sixth surface, 2 selective diffraction grating, 3 collimator lens, 4
Half mirror, 5 Objective lens, 6 optical recording medium, 6
a signal recording surface, 7 condenser lens, 8 photodetector, 10
Optical pickup device, 11 Reproduction signal amplification circuit, 12
Servo circuit, 13 servo mechanism, 14 spindle motor, 15 waveform equalization circuit, 16 A / D conversion circuit, 1
7 decoding circuit, 18 encoder, 19 modulation circuit, 2
0 laser drive circuit, 21 lines, 22, 23 notch, 2
4, 25 lines, 30 laser light source, 30C optical element,
30C1 first surface, 30C2 second surface, 30C3
3rd surface, 30C4 4th surface, 30C5 5th surface, 40 optical pickup device, 50 objective lens, 60
Optical recording medium, 60a signal recording surface, 100 optical disk device, 600 wavelength-selective optical element

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 11/105 551 G11B 11/105 551C 556 556B (72) Inventor Yoichi Tsuchiya 2 Keihanhondori, Moriguchi-shi, Osaka 5-5-5 Sanyo Electric Co., Ltd. F term (reference) 2H049 CA01 CA05 CA15 CA20 5D075 AA03 CD07 CD16 CE03 5D118 AA26 BA01 BB01 BB03 CD02 CG02 CG04 CG24 DA35 5D119 AA41 BA01 EC47 FA05 FA08

Claims (7)

[Claims] 1. An optical pickup device that records and / or reproduces a signal on a recording medium using a laser beam, comprising: a first semiconductor laser that generates a first laser beam having a first wavelength; A second semiconductor laser that generates a second laser light having a second wavelength different from the first wavelength, and a first laser light generated by the first semiconductor laser that is transmitted as it is; An optical pickup device having a laser light source including: an optical element that transmits the second laser light generated by the second semiconductor laser with its optical axis substantially coincident with the optical axis of the first laser light. . 2. An optical pickup device for recording and / or reproducing a signal on a recording medium using a laser beam, wherein the first semiconductor laser generates a first laser beam having a first wavelength; A second semiconductor laser that generates a second laser light having a second wavelength different from the first wavelength, and a first laser light generated by the first semiconductor laser that is transmitted as it is; An optical element that reflects the second laser light generated by the second semiconductor laser and transmits the light by substantially aligning the optical axis with the optical axis of the first laser light. Optical pickup device. 3. The optical element includes first and second surfaces that transmit the first laser light, a third surface that transmits the second laser light, and the first laser light. The optical pickup device according to claim 2, further comprising: a fourth surface that transmits light and reflects the second laser light; and a fifth surface that transmits the first and second laser lights. 4. An optical element comprising: a first and a second surface transmitting the first laser light; a third surface transmitting the second laser light; and the second laser light. A fourth surface that reflects the first laser light, a fifth surface that transmits the first laser light and reflects the second laser light, and a sixth surface that transmits the first and second laser light. The optical pickup device according to claim 2, comprising: 5. The first semiconductor laser and the second semiconductor laser have emission surfaces of laser light in the same plane, and the laser light source includes the first and second semiconductor lasers. And a pedestal on which the optical element is mounted. The pedestal holds a distance between the emission surfaces of the first and second semiconductor lasers and the optical element at a constant level, and mounts the optical element. The optical pickup device according to claim 2, further comprising a notch. 6. A signal is recorded and / or reproduced on a first recording medium having a first substrate thickness and a second recording medium having a second substrate thickness larger than the first substrate thickness. An optical pickup device, comprising: a first semiconductor laser that generates a first laser light having a first wavelength; and a second semiconductor laser that generates a second laser light having a second wavelength different from the first wavelength. Two semiconductor lasers,
The first laser light generated by the first semiconductor laser is transmitted as it is, and the second laser light generated by the second semiconductor laser is moved along the optical axis of the first laser light. A laser light source that includes an optical element that transmits substantially coincident with the optical axis; and a laser light source that is designed to be compatible with the first substrate thickness of the first recording medium and that transmits the first and second laser lights. An objective lens for converging and irradiating the first recording medium and the second recording medium, respectively; and an objective lens provided between the objective lens and the laser light source to transmit the first laser light as it is. A wavelength-selective optical element for guiding the second laser beam to an outer peripheral side from an optical axis to guide only a predetermined inner peripheral portion to the objective lens. 7. An optical pickup device according to claim 1, further comprising: a laser drive circuit that selectively drives the first and second semiconductor lasers included in the laser light source. Optical disk device.