JP3291444B2 - Optical pickup device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reproducing apparatus for a plurality of types of optical disks having different substrate thicknesses and recording densities.

[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. Recently, the recording density for recording a long moving image has been increasing.

[0003] For example, the same 12 cm diameter as a CD-ROM
A DVD standard for recording 4.7 Gbyte information on one side of an optical disc has been proposed. The thickness of a DVD disk is about 0.6 mm, and 9.4 Gbyte information can be recorded on a single disc by bonding both sides. There is also a CD-R as a recordable optical disc having the same diameter, substrate thickness and recording density as a CD.

[0004] Since it is conceivable that these three types of optical disks coexist, a device capable of compatible reproduction of three types of optical disks is required. DVD, CD, and CD-R have different thicknesses of disk substrates, and cannot be reproduced by one optical pickup. Japanese Patent Application Laid-Open No. 5-303766 discloses that a high-density optical disk having a thin substrate having a thickness of 0.6 mm and a standard-density optical disk having a standard-thick substrate having a thickness of 1.2 mm are combined into one. An apparatus has been proposed that enables reproduction by an optical pickup.

This technique uses an objective lens having a numerical aperture of 0.6 designed to reproduce a high-density disc with a short-wavelength laser beam, and corrects aberrations when reproducing a standard-thickness standard-density optical disc. This is an apparatus in which an aperture for reducing the effective numerical aperture by shielding the outer peripheral side of the laser beam from light is added to the light source side of the objective lens. As a method of changing the effective numerical aperture of an objective lens for condensing a laser beam by selectively shielding the outer peripheral portion of a laser beam emitted from a semiconductor laser, the applicant has disclosed in Japanese Patent Application No. 8-84307. We propose a method that combines a liquid crystal that selectively rotates the plane of polarization of a laser beam and a polarization filter that transmits only a laser beam that is polarized in a specific direction, and discloses a technology that enables compatible playback of optical disks with different substrate thicknesses using this method. are doing.

[0006]

Problems to be Solved by the Invention Japanese Patent Application No. 8-84307
In the method disclosed in US Pat.
Compatible playback is possible, but the substrate thickness is 1.2mm
DR cannot be reproduced with a laser beam having a wavelength of 635 nm. Further, since the signal is recorded as a pit row, it is necessary to change the beam diameter applied to the signal recording surface in accordance with the size of the pit. DVDs cannot be compatiblely reproduced with a laser beam having a wavelength of 635 nm.

Therefore, the present invention solves such a problem, and performs compatible reproduction between a DVD having a substrate thickness of 0.6 mm and a CD or CD-R having a substrate thickness of 1.2 mm, and a DVD and a high density D.
An object of the present invention is to provide an optical pickup device capable of reproducing data compatible with VD.

[0008]

According to the present invention, there is provided a first optical disk having a transparent substrate having a first thickness, and a transparent optical disk having a second thickness different from the first thickness. What is claimed is: 1. An optical pickup device for performing recording and / or reproduction on a second optical disk having a substrate, comprising: an objective lens provided to face an optical disk on which recording and / or reproduction is to be performed; Numerical aperture changing means for changing the numerical aperture of the objective lens according to the thickness of the transparent substrate of the optical disc on which the optical disk is to be subjected;
A first semiconductor laser that generates the first laser light, a second semiconductor laser that generates the second laser light, the first laser light, and the second laser light from the signal recording surface of the optical disk. Light detecting means for detecting reflected light of the first semiconductor laser, and diffracting the first laser light generated by the first semiconductor laser in a first direction, and the second laser light generated by the second semiconductor laser. The laser light is diffracted in a second direction different from the first direction, and the first laser light and the reflected light of the second laser light from the signal recording surface of the optical disk are sent to the light detecting means. An optical means including a guiding hologram, and furthermore, a distance between the first semiconductor laser and the second semiconductor laser is Z ₀ ,
The distance between the first semiconductor laser and the light detecting means is Z
₁ , the distance between the second semiconductor laser and the light detecting means is Z ₂ , the distance between the first semiconductor laser and the hologram is L, the pitch of the hologram is p, the wavelength of the first laser light the lambda _1, the wavelength of the second laser beam when the _{λ 2, Z 1 = Lλ 1} / (p 2 -λ 1 2) 1/2, Z 2 = Lλ 2 / (p 2 -λ 2 ² )
^1/2, and having a Z ₀ = Z ₂ -Z ₁ the relationship.

The present invention also relates to a recording and / or reproducing apparatus for a first optical disk having a transparent substrate having a first thickness and a second optical disk having a transparent substrate having a second thickness different from the first thickness. An optical pickup device for performing recording and / or reproduction, comprising: an objective lens provided to face an optical disk on which recording and / or reproduction is to be performed; and a thickness of a transparent substrate of the optical disk on which recording and / or reproduction is to be performed. Numerical aperture changing means for changing the numerical aperture of the objective lens according to the following; a first semiconductor laser for generating a first laser beam; a second semiconductor laser for generating a second laser beam; An optical unit including: a first laser beam; and a light detecting unit that detects a reflected beam of the second laser beam from the signal recording surface of the optical disc; and the first laser beam from the optical unit. Diffracting in a first direction, diffracting the second laser light in a second direction different from the first direction, guiding the diffracted laser light to the objective lens, And a hologram for guiding the reflected light of the second laser light from the signal recording surface of the optical disk to the optical means, and furthermore, the distance between the first semiconductor laser and the second semiconductor laser is Z _0. The distance between the first semiconductor laser and the light detecting means is Z ₁ , the distance between the second semiconductor laser and the light detecting means is Z ₂ , and the distance between the first semiconductor laser and the hologram is L, and the pitch of the hologram p, a wavelength of the first laser beam lambda _1, the wavelength of the second laser beam when the _{λ 2, Z 1 = Lλ 1} / (p 2 -λ 1 2 ^{_{) 1/2, Z 2 = Lλ 2}} / (p 2 -λ 2 2)
^1/2, and having a Z ₀ = Z ₂ -Z ₁ the relationship.

Further, according to the present invention, there is provided a first optical disk having a transparent substrate of a first thickness, and a recording and / or recording of a second optical disk having a transparent substrate of a second thickness different from the first thickness. An optical pickup device for performing recording and / or reproduction, comprising: an objective lens provided to face an optical disk on which recording and / or reproduction is to be performed; and a thickness of a transparent substrate of the optical disk on which recording and / or reproduction is to be performed. Numerical aperture changing means for changing the numerical aperture of the objective lens according to the following; a first semiconductor laser for generating a first laser beam; a second semiconductor laser for generating a second laser beam; Light detection means for detecting reflected light of the first laser light and the second laser light from the signal recording surface of the optical disc; and the first laser generated by the first semiconductor laser Was diffracted in a first direction, the second
Diffracting the second laser light generated by the semiconductor laser in a second direction different from the first direction, and recording the first laser light and the second laser light on the optical disc. An optical unit including a hologram for guiding reflected light from a surface to the light detecting unit; a first laser beam and the second laser beam from the optical unit; And a distance between the first semiconductor laser and the second semiconductor laser is Z ₀ , and a distance between the first semiconductor laser and the second semiconductor laser is Z ₀ .
The distance between the semiconductor laser and the light detecting means is Z ₁ , the distance between the second semiconductor laser and the light detecting means is Z ₂ ,
When the distance between the first semiconductor laser and the hologram is L, the pitch of the hologram is p, the wavelength of the first laser light is λ ₁ , and the wavelength of the second laser light is λ ₂ , Z ₁ = Lλ ₁ / (p ² −λ ₁ ² ) ^1/2 , Z ₂ = Lλ ₂ / (p ² −λ ₂ ² )
^1/2, and having a Z ₀ = Z ₂ -Z ₁ the relationship.

[0011] The present invention also relates to a first optical disk having a transparent substrate of a first thickness and a recording and / or reproducing method of a second optical disk having a transparent substrate of a second thickness different from the first thickness. An optical pickup device for performing recording and / or reproduction, comprising: an objective lens provided to face an optical disk on which recording and / or reproduction is to be performed; and a thickness of a transparent substrate of the optical disk on which recording and / or reproduction is to be performed. Numerical aperture changing means for changing the numerical aperture of the objective lens according to the following; a first semiconductor laser for generating a first laser beam; a second semiconductor laser for generating a second laser beam; Optical means including light detection means for detecting reflected light of the first laser light and the second laser light from the signal recording surface of the optical disc; and the first laser light generated by the laser light generation means. A collimator lens that receives light and the second laser light and guides the received light to the objective lens; and a collimator lens provided immediately before or immediately after the collimator lens, diffracts the first laser light in a first direction. And diffracts the second laser light in a second direction different from the first direction, and reflects the first laser light and the second laser light from the signal recording surface of the optical disc. And a hologram that guides the distance between the first semiconductor laser and the second semiconductor laser to Z ₀ , and the distance between the first semiconductor laser and the light detection unit to Z _1. The distance between the second semiconductor laser and the light detecting means is Z ₂ , the distance between the first semiconductor laser and the hologram is L, the pitch of the hologram is p, and the wavelength of the first laser light is λ ₁ When the wavelength of the second laser beam is λ ₂ , Z ₁ = Lλ ₁ / (p ² −λ ₁ ² ) ^1/2 , Z ₂ = Lλ ₂ / (p ² −λ ₂ ² )
^1/2, and having a Z ₀ = Z ₂ -Z ₁ the relationship.

Further, in the optical pickup device of the present invention, the wavelength λ ₁ of the first laser light is 620 to 660 n
m, and the wavelength λ ₂ of the second laser beam is 76
The distance Z ₀ between the first semiconductor laser and the second semiconductor laser is 0.1 to 0.1 nm.
In the range of 5 mm, the distance Z ₁ between the first semiconductor laser and the light detecting means is a range of 0.50～2.2Mm, pitch p of the hologram is in the range of 1.5~35μm The distance L between the first semiconductor laser and the hologram is in the range of 3 to 25 mm.

In the optical pickup device according to the present invention, the wavelength λ ₁ of the first laser light is 350 to 550 n.
m, and the wavelength λ ₂ of the second laser beam is 62
0 to 660 nm, and the distance Z ₀ between the first semiconductor laser and the second semiconductor laser is 0.1 to 0.5.
mm in the range of the distance Z ₁ between the first semiconductor laser and the light detecting means is in the range of 0.3 to 1.5 mm,
The hologram pitch p is in the range of 3 to 12 μm, and the distance L between the first semiconductor laser and the hologram is in the range of 3 to 15 mm.

In the optical pickup device of the present invention, the wavelength λ ₁ of the first laser light is 350 to 550 n.
m, and the wavelength λ ₂ of the second laser beam is 76
The distance Z ₀ between the first semiconductor laser and the second semiconductor laser is 0.1 to 0.5 nm.
mm in the range of the distance Z ₁ between the first semiconductor laser and the light detecting means is in the range of 0.2 to 1.0 mm,
The hologram pitch p is in the range of 5 to 12 μm, and the distance L between the first semiconductor laser and the hologram is in the range of 2 to 15 mm.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment A first embodiment of the present invention will be described with reference to the drawings. FIG. 18 shows CDs and CDs to be compatible with the present invention.
-R and rating values of DVD and playback conditions are shown. The CD substrate thickness is 1.2 (allowable error ± 0.1) mm, the shortest pit length is 0.83 (allowable range: 0.80 to 0.90) μm, and the track pitch is 1.6 (allowable error ± 0). .1) μm, and the reflectivity is 60 to 70 for a laser beam having a wavelength of 780 nm.
% Or more. The spot diameter of the laser beam during reproduction is 1.5 (allowable error ± 0.1) μm, the numerical aperture of the objective lens is 0.45 (allowable error ± 0.05), and the reproducing laser beam wavelength is 780 (allowable error). Range: 760-800) nm. The substrate thickness of CD-R is 1.2 (tolerance ± 0.1) m
m, the shortest pit length is 0.83 (allowable range: 0.80 to 0.8)
90) μm, track pitch 1.6 (tolerance ± 0.5)
1) The reflectivity to a laser beam having a wavelength of 780 nm and a wavelength of 780 nm is 60 to 70% or more, the spot diameter of the laser beam during reproduction is 1.5 (tolerance ± 0.1) μm, and the numerical aperture of the objective lens is 0. .45 (allowable error ± 0.05), reproduction laser beam wavelength is 780 (allowable range: 760-800) n
m. On the other hand, the DVD substrate thickness is 0.6 (tolerance ±
0.05) mm, the shortest pit length is 0.40 (permissible error ±
0.1) μm, track pitch 0.74 (tolerance ±
0.01) μm and a reflectivity to a laser beam having a wavelength of 635 nm is 40% or more (in the case of a single signal recording surface) or 15 to 40% (in the case of two signal recording surfaces);
The spot diameter of the laser beam during reproduction is 0.9 (allowable error ± 0.5) μm, the numerical aperture of the objective lens is 0.6 (allowable error ± 0.05), and the read laser beam wavelength is 635 (allowable range: 620-660) nm.

FIG. 1 shows a configuration of an optical pickup 10 for performing compatible reproduction between a CD, a CD-R and a DVD. Optical means 1
Wavelength 635 emitted from semiconductor lasers 1a and 1b inside
(Allowable range: 620 to 660) nm or wavelength 780
The laser beam of (permissible range: 760 to 800) nm is selectively diffracted by the hologram 1 d provided on the surface of the optical unit 1, selectively shielded by the numerical aperture changing unit 4, and enters the objective lens 5. The laser beam condensed by the objective lens 5 is applied to the signal recording surface 7a (or 77a) of the optical disk through the translucent polycarbonate substrate 7 (or 77). The signal recording surface 7a (or 77)
The laser beam reflected in a) is applied to the substrate 7 (or 7).
7) Returning via the objective lens 5 and the numerical aperture changing means 4 and detected by the photodetector 1c installed in the optical means 1 via the hologram 1d. The objective lens 5 is designed for an optical disk having a substrate thickness of 0.6 mm, and has a numerical aperture of 0.6 (allowable error ± 0.05).

In the present invention, the optical means 1 comprises a semiconductor laser 1a for emitting a laser beam having a wavelength of 780 nm,
Semiconductor laser 1 that emits a laser beam with a wavelength of 635 nm
b, a photodetector 1c and a hologram 1d for diffracting only a laser beam having a wavelength of 780 nm without diffracting a laser beam having a wavelength of 635 nm are provided. When a CD or CD-R is reproduced, the semiconductor laser 1a is used. Is selectively driven,
When a DVD is reproduced, the semiconductor laser 1b is selectively driven. That is, the optical unit 1 selectively drives a laser beam having a wavelength of 635 nm and a laser beam having a wavelength of 780 nm, diffracts only the laser beam having a wavelength of 780 nm to be incident on the objective lens 4, and has a wavelength of 635n.
It has a function of condensing the reflected light of the laser beam of m and the laser beam of 780 nm wavelength on the signal recording surface of the optical disc on the photodetector 1c.

The numerical aperture changing means 4 includes an outer peripheral portion 4a.
And an inner peripheral portion 4b.
Although the laser beam of 35 nm and the laser beam of 780 nm are transmitted as they are, the outer peripheral portion 4a has a wavelength of 78 nm.
It has a function of blocking only a laser beam of 0 nm. The diameter of the inner peripheral portion 4b is such that the effective numerical aperture of the laser beam having a wavelength of 780 nm in the objective lens 5 is 0.45.
(Allowable error ± 0.05). Further, since the numerical aperture changing means 4 and the objective lens 5 are fixed to the actuator 6, the numerical aperture changing means 4 moves in conjunction with the objective lens 5 at the time of focus pull-in or tracking servo. As a result, the numerical aperture changing means 4
There is no displacement between the laser beam and the objective lens 5, and the outer peripheral portion of the laser beam having a wavelength of 780 nm can be reliably shielded.

The optical means 1 is provided with the semiconductor lasers 1a and 1b and the photodetector 1c. The positional relationship between them will be described. The hologram used in the present invention selectively diffracts the laser beam according to the difference in the wavelength of the laser beam emitted from the semiconductor laser, makes the laser beam incident on the objective lens 5, and makes the signal recording surface 7a
(Or 77a) is condensed in a direction different from the direction of the semiconductor laser that has emitted the laser beam. Referring to FIG. 2, a semiconductor laser SL that emits a laser beam and a photodetector D that detects reflected light
A method for determining the positional relationship between the two will be described. The semiconductor laser SL and the photodetector D are installed on the same plane,
The distance between the semiconductor laser SL and the hologram H is L, the pitch of the fine uneven structure provided on the hologram H is p, the angle between the traveling direction of the reflected light changed by the hologram H and the normal direction is θ, and the laser is The wavelength of the beam is λ, and the distance between the semiconductor laser SL and the photodetector D is Z.

In this case, sin θ = λ / p (1) Z = Ltan θ (2) holds. From the above equations (1) and (2), Z = Lλ / (p ² −λ ² ) ^1/2 (3) holds. Therefore, as the wavelength of the laser beam becomes longer, the angle θ at which the reflected light can change its traveling direction by the hologram H
Becomes larger. As a result, the distance Z between the semiconductor laser SL and the photodetector D increases. This means that if semiconductor lasers emitting laser beams having different wavelengths are installed at the same position, the positions where the reflected light is detected will be different. That is, if the reflected light of the laser beam having the wavelength of 635 nm is detected by the photodetector D, the reflected light of the laser beam having the wavelength of 780 nm can be detected at a position shifted from the photodetector D in the opposite direction to the semiconductor laser SL. become. Therefore, in the present invention, the deviation of the detection position of the reflected light generated due to the difference in the wavelength of the laser beam is absorbed by making the installation position of the semiconductor laser different, and even if the wavelength is different, the reflected light of the laser beam is absorbed. Is characterized in that two semiconductor lasers and a photodetector are installed so that can be detected at the same position. Further, since the distance Z between the semiconductor laser SL and the photodetector D changes depending on the distance L between the semiconductor laser SL and the hologram H, the hologram 1d and the semiconductor laser 1 according to the present invention are referred to FIG.
The detailed positional relationship between a, 1b and the photodetector 1c will be described. The distance between the semiconductor laser 1b that emits a laser beam having a wavelength of 635 nm and the photodetector 1c is Z ₁ , and the wavelength is 78.
Z _2> Z ₁ and comprising as a semiconductor laser 1a the distance between the semiconductor laser 1a and the light detector 1c for emitting a laser beam of 0nm as Z _2, 1b, installing a light detector 1c. The pitch p of the uneven structure of the hologram 1d and the semiconductor laser 1
a, 1b, the distance between the photodetector 1c and the hologram 1d, that is, the result of calculating Z ₁ , Z ₂ , Z ₂ -Z ₁ using the distance L between the light emitting point of the laser beam and the hologram as a parameter.
As shown in FIG. The hologram pitch p is 1.5 to 35 μm
, And Z ₂ -Z ₁ is 0.1-0.5 m when the distance L between the laser beam emission point and the hologram is 3-25 mm.
m. The distance between the semiconductor laser 1b and the photodetector 1c is in the range of 0.5 to 2.2 mm.
Therefore, in the present invention, the distance between the semiconductor laser 1a and the semiconductor laser 1b is set within the range of 0.1 to 0.5 mm, and the laser beam having the wavelength of 635 nm and the wavelength of 780 nm are set.
The reflected light of the nm laser beam from the signal recording surface of the optical disk is detected at the same position of the photodetector 1c. In this case, the photodetector 1c is positioned so that the semiconductor laser 1a is positioned in the outer peripheral direction of the optical disk with the semiconductor laser 1b as a center.
Are located in the inner circumferential direction of the optical disk.

The semiconductor laser 1a and the semiconductor laser 1
Although the installation position is different from b in the range of 0.1 to 0.5 mm,
The shift in this range does not appear as deterioration of the reproduction characteristics due to the shift of the optical axis of the laser beam applied to the optical disk. Further, the direction of the installation position of the semiconductor laser 1a and the semiconductor laser 1b is not limited to the radial direction of the optical disk, but may be the circumferential direction.

Referring to FIG. 5, the semiconductor laser 1a,
The mounting of the photodetector 1b and the photodetector 1c will be described.
FIG. 5 shows a view from the numerical aperture changing means 4 side. The optical means 1 has three cuts k1, k2, and k3, and the light emitting points A and B of the semiconductor lasers 1a and 1b, respectively.
Are mounted so as to be arranged in a horizontal direction on a line connecting the cuts k2 to k3. The optical means 1 on which the two semiconductor lasers 1a and 1b are mounted is installed so that the direction of the cuts k2-k3 coincides with the radial direction of the optical disk, that is, the tracking direction. Further, the semiconductor lasers 1a, 1
b may be created independently, and the element may be mounted on one substrate, or two elements may be created by growing crystals on one substrate.

A specific example of the numerical aperture changing means 4 will be described with reference to FIG. Numerical aperture changing means 4 shown in FIG.
4 is a laser beam having a wavelength of 635 nm in the outer peripheral portion 44a,
It has the function of diffusing only the laser beam having a wavelength of 780 nm to the outside of the optical axis without being incident on the objective lens 5 and transmitting the laser beam having a wavelength of 635 nm.
And the laser beam having a wavelength of 780 nm are transmitted as they are. With reference to FIG.
The 35 nm laser beam 50 is not affected at all by the numerical aperture changing means 44 and is transmitted as it is. On the other hand, FIG.
Referring to (b), a laser beam 51 having a wavelength of 780 nm
In the numerical aperture changing means 44, the laser beam incident on the inner peripheral portion 44b is transmitted as it is, but the outer peripheral portion 44a
Is greatly diffracted outside the optical axis. As a result, the laser beam 52 is transmitted substantially only at the inner periphery.

Another specific example of the numerical aperture changing means 4 will be described with reference to FIG. The numerical aperture changing means 45 shown in FIG. 7 is provided with a polarizing film that transmits only a laser beam polarized in a direction perpendicular to the paper surface on the outer peripheral portion 45a,
Nothing is provided on the inner peripheral portion 45b. as a result,
A laser beam having a wavelength of 635 nm, which is polarized in a direction perpendicular to the plane of the paper, entirely passes through the numerical aperture changing unit 45, whereas a laser beam having a wavelength of 780 nm, which is polarized in a direction parallel to the plane of the paper, has only the outer peripheral part having the numerical aperture changing unit 45. , And only the inner peripheral portion is transmitted.

Still another example of the numerical aperture changing means 4 will be described with reference to FIG. The numerical aperture changing means 46 shown in FIG. 8 is provided with a polarizing glass which absorbs only a laser beam having a wavelength of 780 nm on an outer peripheral portion 46a, and an inner peripheral portion 46b is a normal glass provided with no polarizing glass. as a result,
The laser beam having a wavelength of 635 nm is entirely transmitted through the numerical aperture changing unit 46, but the laser beam having a wavelength of 780 nm is shielded only by the outer peripheral part by the numerical aperture changing unit 46 and is transmitted only by the inner peripheral part.

Referring to FIG. 9, the operation of reproducing a DVD which is an optical disk having a substrate thickness of 0.6 mm will be described. DV
When D is reproduced, a semiconductor laser 1a that emits a laser beam having a wavelength of 635 nm in the optical unit 1 is selectively driven by a laser driving circuit 18 in an optical reproducing apparatus described later. As a result, the laser beam having a wavelength of 635 nm passes through the hologram 1d and the numerical aperture changing means 4 as it is, is condensed by the objective lens 5, and irradiates the signal recording surface 7a through the substrate 7 of the optical disk. The spot diameter of the laser beam applied to the signal recording surface 7a is 0.9 (allowable error ± 0.1) μm. Subsequent operations are the same as those described with reference to FIG.

Referring to FIG. 10, the operation of reproducing a CD or CD-R as an optical disk having a substrate thickness of 1.2 mm will be described. When a CD or CD-R is reproduced, the laser driving circuit 18 selectively drives the semiconductor laser 1b in the optical means 1 which emits a laser beam having a wavelength of 780 nm. As a result, the laser beam having a wavelength of 780 nm is diffracted by the hologram 1d, only the outer peripheral portion is shielded by the numerical aperture changing means 4, and the inner peripheral portion is incident on the objective lens 5. The laser beam that has entered the objective lens 5 is condensed and passes through the substrate 77 of the optical disk and irradiates the signal recording surface 77a. The spot diameter of the laser beam applied to the signal recording surface 77a is 1.5 (allowable error ± 0.1) μm.
Subsequent operations are the same as those described with reference to FIG.

In this case, the inner peripheral portion of the laser beam, whose outer peripheral portion is shielded by the numerical aperture changing means 4, is diffracted outward even after the light is shielded by the effect of the diffraction by the hologram 1d, so that the objective lens 5 receives the laser beam. As a result of being incident and condensed by the objective lens 5, the occurrence of aberration in an optical disk having a substrate thickness of 1.2 mm is suppressed. Further, the optical pickup according to the present invention is not limited to the one shown in FIG. 1, but may be one shown in FIG. That is, in the configuration shown in FIG. 1, the semiconductor lasers 1a and 1b, the photodetector 1c, and the hologram 1d are arranged in one optical unit 1, but the present invention is not limited to this.
As shown in FIG. 1, the optical pickup 20 may have a configuration in which the hologram 2 is separated from the optical unit 1. In this case, the distance between the semiconductor lasers 1a and 1b and the hologram 2 in the optical means 1, the distance between the semiconductor laser 1a and the semiconductor laser 1b, the distance between the semiconductor laser 1b and the photodetector 1c, and the pitch of the hologram 2 are shown in FIG. Is the same as that shown in FIG. The components other than the optical unit 1 and the hologram 2 are the same as those in FIG.

The optical pickup according to the present invention comprises:
Further, it may have the configuration shown in FIG. FIG.
An optical pickup 40 shown in FIG. 1 has a configuration in which a collimator lens 3 is inserted between the optical unit 1 and the numerical aperture changing unit 4 of the optical pickup 10 shown in FIG. Optical means 1
The distance between the semiconductor lasers 1a and 1b and the hologram 1d, the distance between the semiconductor laser 1a and the semiconductor laser 1b, the distance between the semiconductor laser 1b and the photodetector 1c, the hologram 1
The pitch of d is the same as that shown in FIG. The other parts are the same as those of the optical pickup 10, and the other description will be omitted.

The optical pickup according to the present invention comprises:
Further, the configuration shown in FIGS. 13 to 16 may be employed. The optical pickup shown in FIGS. 13 to 16 has a configuration in which the hologram 2 is separated from the optical unit 1 in the optical pickup 10 of FIG. 1 and a collimator lens 3 is added. Also in this case, the semiconductor laser 1 in the optical means 1
The distance between a, 1b and hologram 2, the distance between semiconductor laser 1a and semiconductor laser 1b, the distance between semiconductor laser 1b and photodetector 1c, and the pitch of hologram 2 are the same as those shown in FIG. The hologram 2 may be located in front of the collimator lens 3 as shown in FIG.
4, it may be located immediately after the collimator lens 3. Further, the hologram 2 may be integrated with the collimator lens 3, and in this case, the hologram 2 may be provided on the front and rear surfaces of the collimator lens 3 as shown in FIGS. Good. With reference to FIG. 17, a reproducing apparatus for compatible reproduction of a DVD having a substrate thickness of 0.6 mm and a CD or CD-R having a substrate thickness of 1.2 mm will be described. The objective lens 5 in the optical pickup 10 is controlled by the servo mechanism 13 so that a signal to be reproduced is focused on a track formed as a pit row, and the laser beam is collected by the objective lens 5. The light is emitted and irradiates the signal recording surface 7a (or 77a) through the substrate 7 (or 77) of the optical disk. The laser beam reflected by the signal recording surface 7a (or 77a) is detected by the photodetector 1c and detected as a reproduction signal.
The reproduced signal detected by the photodetector 1c is a preamplifier 1
The signal is sent to a discrimination circuit 14, an RF demodulation circuit 16 and a servo circuit 12 after a predetermined amplification. The servo circuit 12 controls the servo mechanism 13 based on the sent tracking error signal. Also, the discriminating circuit 1
Reference numeral 4 denotes a command circuit 15 for identifying the type of the optical disc mounted on the reproducing apparatus based on the transmitted signal and for discriminating the identification result.
Send to The command circuit 15 switches the semiconductor laser in the optical means 1 so as to be compatible with the identified optical disk.
9 is commanded. Further, the command circuit 15 switches the characteristic switching circuit 17 based on the received identification result in order to switch to a demodulation circuit suitable for reproducing the identified optical disk.
Also issue a command. The control circuit 19 includes the command circuit 1
The characteristic switching circuit 17 switches the semiconductor laser via a laser driving circuit 18 based on a command from the RF demodulation circuit 16 based on a command from the command circuit 15.
Switch. Thereby, reproduction suitable for the optical disk mounted on the reproduction device is performed. Second Embodiment In the first embodiment, a DVD, which is an optical disk having a substrate thickness of 0.6 mm, is formed by using an optical unit 1 for selectively generating a laser beam having a wavelength of 635 nm and a laser beam having a wavelength of 780 nm. Although the optical pickup device capable of reproducing compatible with CDs and CD-Rs, which are optical disks having a substrate thickness of 1.2 mm, has been described, the second embodiment has a wavelength of 4 mm.
DVD using optical means for selectively generating a laser beam of 80 (allowable range: 350 to 550) nm and a laser beam of wavelength 635 (allowable range: 620 to 660) nm
1 shows an optical pickup device that performs compatible reproduction between a DVD and a high-density DVD.

Referring to FIG. 19, D which is the object of the present invention
The rated values and the reproduction conditions of the VD and the high-density DVD will be described. D
The substrate thickness of VD is 0.6 (tolerance ± 0.05) mm, the shortest pit length is 0.40 (tolerance ± 0.1) μm, and the track pitch is 0.74 (tolerance ± 0.01) μm. , Wavelength 63
The reflectivity for a laser beam of 5 nm is 40% or more (in the case of a single signal recording surface) or 15 to 40% (in the case of two signal recording surfaces), and the spot diameter of the laser beam during reproduction is 0.9. (Allowable error ± 0.5) μm, the numerical aperture of the objective lens is 0.6 (allowable error ± 0.05), and the reproduction laser beam wavelength is 635 (allowable error ± 15) nm. On the other hand, the substrate thickness of the high-density DVD is 0.3 (tolerance ± 0.0
5) mm, shortest pit length 0.30 (tolerance ± 0.1)
μm, track pitch 0.56 (tolerance ± 0.01)
μm, the reflectance to a laser beam having a wavelength of 480 nm is 40% or more (in the case of a single signal recording surface) or 15 to
40% (when there are two signal recording surfaces), and the spot diameter of the laser beam during reproduction is 0.7 (allowable error ± 0.5) μ.
m, the numerical aperture of the objective lens is 0.65 (tolerance ± 0.0
5) The reproduction laser beam wavelength is 480 (permissible range: 35)
0-550) nm.

FIG. 20 shows the configuration of an optical pickup 201 for performing compatible reproduction between a DVD and a high-density DVD. A laser beam having a wavelength of 480 (allowable range: 350 to 550) nm or a wavelength of 635 (allowable error ± 15) nm emitted from the semiconductor lasers 1e and 1b in the optical means 202 is a hologram 1g provided on the surface of the optical means 202. Are selectively diffracted, and are selectively shielded from light by the numerical aperture changing means 203 and enter the objective lens 204. The laser beam condensed by the objective lens 204 is applied to the signal recording surface 205a (or 206a) of the optical disk through the translucent polycarbonate substrate 205 (or 206). The laser beam reflected by the signal recording surface 205a (or 206a) returns via the substrate 205 (or 206), the objective lens 204, and the numerical aperture changing unit 203, and passes through the hologram 1g to the optical unit 202. It is detected by the photodetector 1c installed inside. The objective lens 204 is designed for an optical disk having a substrate thickness of 0.3 mm, and has a numerical aperture of 0.65 (allowable error ± 0.05).

In the present invention, the optical means 202 is a semiconductor laser 1 that emits a laser beam having a wavelength of 635 nm.
b, a semiconductor laser 1e that emits a laser beam with a wavelength of 480 nm, a photodetector 1c, and a hologram 1g that diffracts only the laser beam with a wavelength of 635 nm without diffracting the laser beam with a wavelength of 480 nm are arranged, and a DVD is reproduced. In this case, the semiconductor laser 1b is selectively driven, and when a high-density DVD is reproduced, the semiconductor laser 1e is selectively driven. That is, the optical means 202 has a wavelength of 480n.
The laser beam having a wavelength of 635 nm and the laser beam having a wavelength of 635 nm are selectively driven, and only the laser beam having a wavelength of 635 nm is diffracted and incident on the objective lens 204. It has a function of condensing the light reflected on the signal recording surface to the photodetector 1c.

The numerical aperture changing means 203 is divided into an outer peripheral portion 203a and an inner peripheral portion 203b. The inner peripheral portion 203b transmits a laser beam having a wavelength of 480 nm and a laser beam having a wavelength of 635 nm as it is. The outer peripheral portion 203a has a function of blocking only a laser beam having a wavelength of 635 nm. The diameter of the inner peripheral portion 203b is a diameter of the objective lens 204 of a laser beam having a wavelength of 635 nm.
Is the diameter at which the effective numerical aperture at is 0.60 (allowable error ± 0.05). Further, since the numerical aperture changing means 203 and the objective lens 204 are fixed to the actuator 6, the numerical aperture changing means 203 moves in conjunction with the objective lens 204 at the time of focusing and tracking servo. As a result, there is no displacement between the numerical aperture changing means 203 and the objective lens 204, and the outer periphery of the laser beam having a wavelength of 635 nm can be reliably shielded.

In the optical means 202, the semiconductor lasers 1b and 1e and the photodetector 1c are provided. The method for determining the positional relationship between them is as described in the first embodiment. This method is the same as the method described with reference to FIGS. The distance between the semiconductor laser 1e that emits a laser beam having a wavelength of 480 nm and the photodetector 1c is Z ₁ , and the wavelength is 635.
nm of Z ₂ the distance between the semiconductor laser 1b and the photodetector 1c as Z ₂ for emitting a laser beam> Z ₁ and comprising as a semiconductor laser 1e, 1b, installing a light detector 1c. The pitch p of the uneven structure of the hologram 1g and the semiconductor laser 1e,
1b, the distance between the photodetector 1c and the hologram 1g, ie,
FIG. 21 shows the result of calculating Z ₁ , Z ₂ , and Z ₂ -Z ₁ using the distance L between the light emitting point of the laser beam and the hologram as a parameter.
Shown in The hologram pitch p is in the range of 3 to 12 μm, and the distance L between the laser beam emission point and the hologram is 3
Z ₂ -Z ₁ is in the range of 0.1 to 0.5 mm in the range of ₁₅ mm. The distance between the semiconductor laser 1e and the photodetector 1c is in the range of 0.289 to 1.45 mm.
Therefore, in the present invention, the distance between the semiconductor laser 1e and the semiconductor laser 1b is set within the range of 0.1 to 0.5 mm, and the laser beam having the wavelength of 480 nm and the wavelength of 635 nm are set.
The reflected light of the nm laser beam from the signal recording surface of the optical disk is detected at the same position of the photodetector 1c. In this case, the photodetector 1c is set so that the semiconductor laser 1b is positioned in the outer peripheral direction of the optical disk with the semiconductor laser 1e as the center.
Are located in the inner circumferential direction of the optical disk.

The semiconductor laser 1b and the semiconductor laser 1
Although the installation position is different from e in the range of 0.1 to 0.5 mm,
The shift in this range does not appear as deterioration of the reproduction characteristics due to the shift of the optical axis of the laser beam applied to the optical disk. Further, the direction of the installation position of the semiconductor laser 1b and the semiconductor laser 1e is not limited to the radial direction of the optical disk, but may be the circumferential direction.

Further, the semiconductor lasers 1b, 1e
The mount of the photodetector 1c is the same as the mount shown in FIG. 5 in the first embodiment. Also,
Further, as a specific example of the numerical aperture changing means 203, the specific examples shown in FIGS. 6, 7, and 8 in the first embodiment are also applied to the numerical aperture changing means 203 of the second embodiment. Can be used.

A DVD having a substrate thickness of 0.6 mm and a substrate thickness of 0.3 m
The reproduction operation for the m high-density DVD is the same as the operation described with reference to FIGS. 9 and 10 in the first embodiment. Further, the optical pickup device according to the second embodiment is not limited to the configuration of the optical pickup 201, and may be one shown in FIG. That is, in the configuration shown in FIG. 20, the semiconductor lasers 1b and 1e, the photodetector 1c, and the hologram 1g are arranged in one optical unit 202. However, the present invention is not limited to this. The optical pickup 221 may have a configuration separated from the means 202. In this case, the semiconductor laser 1 in the optical unit 202
b, 1e and distance between hologram 207, semiconductor laser 1
The distance between b and the semiconductor laser 1e, the distance between the semiconductor laser 1e and the photodetector 1c, and the pitch of the hologram 207 are shown in FIG.
1 is the same as that shown in FIG. In addition, components other than the optical unit 202 and the hologram 207 are the same as those in FIG.

The optical pickup according to the second embodiment may further have the configuration shown in FIG. The optical pickup 231 shown in FIG. 23 has a configuration in which a collimator lens 208 is inserted between the optical unit 202 and the numerical aperture changing unit 203 of the optical pickup 201 shown in FIG. Distance between the semiconductor lasers 1b and 1e in the optical means 202 and the hologram 1g;
The distance between b and the semiconductor laser 1e, the distance between the semiconductor laser 1e and the photodetector 1c, and the pitch of the hologram 1g are shown in FIG.
Is the same as that shown in FIG. The other parts are the same as those of the optical pickup 201, and the other description is omitted.

The optical pickup according to the present invention comprises:
Further, the configuration shown in FIGS. 24 to 27 may be used. The optical pickup shown in FIGS. 24 to 27 has a configuration in which the hologram 207 is separated from the optical unit 202 in the optical pickup 201 of FIG. 20, and a collimator lens 208 is added. Also in this case, the optical means 202
The distance between the semiconductor lasers 1b and 1e and the hologram 207, the distance between the semiconductor laser 1b and the semiconductor laser 1e, the distance between the semiconductor laser 1e and the photodetector 1c, the hologram 2
The pitch of 07 is the same as that shown in FIG. Further, the hologram 207 may be located before the collimator lens 208 as shown in FIG. 24, or may be located immediately after the collimator lens 208 as shown in FIG. Further, the hologram 207 is a collimator lens 208.
26 and 27, the hologram 207 may be provided on the front and rear surfaces of the collimator lens 208 as shown in FIGS.

A DVD having a substrate thickness of 0.6 mm and a DVD having a substrate thickness of 0.6 mm
The same playback device as the device shown in FIG. 17 in the first embodiment can be used as a playback device for compatible playback of a 3 mm high-density DVD. Third Embodiment In the third embodiment, a CD or a CD-R, which is an optical disk having a substrate thickness of 1.2 (tolerance ± 0.1) mm, and a substrate thickness of 0.3 (tolerance ± 0). A description will be given of compatible playback with a high-density DVD, which is a .05) mm optical disc.

FIG. 28 shows CDs and CD-Rs which are compatible reproduction targets of the optical pickup device according to the third embodiment.
And the rated values and reproduction conditions of the high-density DVD. The CD substrate thickness is 1.2 (allowable error ± 0.1) mm, the shortest pit length is 0.83 (allowable range: 0.80 to 0.90) μm, and the track pitch is 1.6 (allowable error ± 0). .1) μm, and the reflectance is 70% or more for a laser beam having a wavelength of 780 nm. The spot diameter of the laser beam during reproduction is 1.5 (allowable error ± 0.1) μm, the numerical aperture of the objective lens is 0.45 (allowable error ± 0.05), and the reproducing laser beam wavelength is 780 (allowable error). Range: 760-800) nm. C
The substrate thickness of the DR is 1.2 (allowable error ± 0.1) mm, and the shortest pit length is 0.83 (allowable range: 0.80 to 0.90) μ.
m, track pitch is 1.6 (tolerance ± 0.1) μm,
The reflectance for a laser beam having a wavelength of 780 nm is 60 to
70% or more, the spot diameter of the laser beam during reproduction is 1.5 (tolerance ± 0.1) μm, the numerical aperture of the objective lens is 0.45 (tolerance ± 0.05), and the reproduction laser beam wavelength Is 780 (allowable range: 760 to 800) nm.
On the other hand, the substrate thickness of the high-density DVD is 0.3 (tolerance ± 0.0
5) mm, shortest pit length 0.30 (tolerance ± 0.1)
μm, track pitch 0.56 (tolerance ± 0.01)
μm, the reflectance to a laser beam having a wavelength of 480 nm is 40% or more (in the case of a single signal recording surface) or 15 to
40% (when there are two signal recording surfaces), and the spot diameter of the laser beam at the time of reproduction is 0.9 (allowable error ± 0.5) μ.
m, the numerical aperture of the objective lens is 0.6 (tolerance ± 0.0
5) The reproduction laser beam wavelength is 480 (permissible range: 35)
0-550) nm.

FIG. 29 shows the configuration of an optical pickup 291 for performing compatible reproduction between a CD or CD-R and a high-density DVD.
A laser beam having a wavelength of 480 (allowable range: 350 to 550) nm or a wavelength of 635 (allowable range: 620 to 660) nm emitted from the semiconductor lasers 1e and 1a in the optical means 292 is provided on the surface of the optical means 292. The light is selectively diffracted by the hologram 1 h, selectively shielded by the numerical aperture changing means 293, and enters the objective lens 294. The laser beam condensed by the objective lens 294 passes through a transparent polycarbonate substrate 295 (or 296) and passes through a signal recording surface 295a (or 296a) of the optical disk.
Is irradiated. The signal recording surface 295a (or 296)
The laser beam reflected in a) returns through the substrate 295 (or 296), the objective lens 294, and the numerical aperture changing unit 293, and detects the light detected in the optical unit 292 via the hologram 1h. Is detected by the detector 1c. The objective lens 294 is designed for an optical disk having a substrate thickness of 0.6 mm, and has a numerical aperture of 0.60 (allowable error ± 0.05).

In the present invention, the optical means 292 is a semiconductor laser 1 that emits a laser beam having a wavelength of 780 nm.
a, a semiconductor laser 1e that emits a laser beam with a wavelength of 480 nm, a photodetector 1c, and a hologram 1h that diffracts only a laser beam with a wavelength of 780 nm without diffracting a laser beam with a wavelength of 480 nm are provided. Is reproduced, the semiconductor laser 1a is selectively driven, and when a high-density DVD is reproduced, the semiconductor laser 1e is selectively driven. That is, the optical unit 292 selectively drives a laser beam having a wavelength of 480 nm and a laser beam having a wavelength of 780 nm, and diffracts only the laser beam having a wavelength of 780 nm to be incident on the objective lens 294. 780
It has a function of condensing the reflected light of the laser beam of nm on the signal recording surface of the optical disc on the photodetector 1c.

The numerical aperture changing means 293 is divided into an outer peripheral portion 293a and an inner peripheral portion 293b. The inner peripheral portion 293b transmits a laser beam having a wavelength of 480 nm and a laser beam having a wavelength of 780 nm as it is. The outer peripheral portion 293a has a function of blocking only a laser beam having a wavelength of 780 nm. The diameter of the inner peripheral portion 293b is a laser beam having a wavelength of 780 nm.
Is the diameter at which the effective numerical aperture is 0.45 (allowable error ± 0.05). Since the numerical aperture changing means 293 and the objective lens 294 are fixed to the actuator 6, the numerical aperture changing means 293 moves in conjunction with the objective lens 294 at the time of focus pull-in and tracking servo. As a result, there is no displacement between the numerical aperture changing means 293 and the objective lens 294, and the outer peripheral portion of the laser beam having a wavelength of 780 nm can be reliably shielded.

In the optical means 292, the semiconductor lasers 1a and 1e and the photodetector 1c are provided. The method for determining the positional relationship between them is as described in the first embodiment. This method is the same as the method described with reference to FIGS. The distance between the semiconductor laser 1e that emits a laser beam having a wavelength of 480 nm and the photodetector 1c is Z ₁ , and the wavelength is 780.
nm of Z ₂ the distance between the semiconductor laser 1a and the light detector 1c as Z ₂ for emitting a laser beam> Z ₁ and comprising as a semiconductor laser 1e, 1a, installing a light detector 1c. The pitch p of the uneven structure of the hologram 1h and the semiconductor laser 1e,
1a, the distance between the photodetector 1c and the hologram 1h, ie,
FIG. 30 shows the results of calculating Z ₁ , Z ₂ , and Z ₂ -Z ₁ using the distance L between the laser beam emission point and the hologram as a parameter.
Shown in The hologram pitch p is in the range of 5 to 12 μm, and the distance L between the laser beam emission point and the hologram is 2
Z ₂ -Z ₁ is in the range of 0.1 to 0.5 mm in the range of ₁₅ mm. Further, the distance between the semiconductor laser 1e and the photodetector 1c is in the range of 0.193 to 0.772 mm. Therefore, in the present invention, the distance between the semiconductor laser 1e and the semiconductor laser 1a is set within a range of 0.1 to 0.5 mm, and the laser beam having a wavelength of 480 nm and the wavelength of 7
The reflected light of the 80 nm laser beam from the signal recording surface of the optical disk is detected at the same position of the photodetector 1c. In this case, the semiconductor laser 1e is centered on the semiconductor laser 1e.
The photodetector 1c is arranged so that a is located in the outer peripheral direction of the optical disk, and the photodetector 1c is located in the inner peripheral direction of the optical disk.

The semiconductor laser 1a and the semiconductor laser 1
Although the installation position is different from e in the range of 0.1 to 0.5 mm,
The shift in this range does not appear as deterioration of the reproduction characteristics due to the shift of the optical axis of the laser beam applied to the optical disk. Further, the direction of the installation position of the semiconductor laser 1a and the semiconductor laser 1e is not limited to the radial direction of the optical disk, but may be the circumferential direction.

Further, the semiconductor lasers 1a, 1e
The mount of the photodetector 1c is the same as the mount shown in FIG. 5 in the first embodiment. Also,
Further, as specific examples of the numerical aperture changing means 293, the specific examples shown in FIGS. 6, 7, and 8 in the first embodiment are also applied to the numerical aperture changing means 293 of the third embodiment. Can be used.

The reproduction operation of a CD or CD-R having a substrate thickness of 1.2 mm and a high-density DVD having a substrate thickness of 0.3 mm is the same as the operation described with reference to FIGS. . Further, the optical pickup device according to the third embodiment is not limited to the configuration of the optical pickup 291 and may be the one shown in FIG. That is, in the configuration shown in FIG. 29, the semiconductor lasers 1a and 1e, the photodetector 1c, and the hologram 1h are arranged in one optical unit 292. However, the present invention is not limited to this, and as shown in FIG.
7 is an optical pickup 3 having a configuration separated from the optical means 292
It may be 11. In this case, the distance between the semiconductor lasers 1a and 1e and the hologram 297 in the optical means 292, the distance between the semiconductor laser 1a and the semiconductor laser 1e, the distance between the semiconductor laser 1e and the photodetector 1c, and the pitch of the hologram 297 are as shown in FIG. Is the same as that shown in FIG. Components other than the optical unit 292 and the hologram 297 are the same as those in FIG.
Therefore, the description of the function is also omitted.

The optical pickup according to the third embodiment may further have the configuration shown in FIG. The optical pickup 321 shown in FIG. 32 has a configuration in which a collimator lens 298 is inserted between the optical unit 292 and the numerical aperture changing unit 293 of the optical pickup 291 shown in FIG. Distance between semiconductor lasers 1a and 1e in optical means 292 and hologram 1h;
The distance between a and the semiconductor laser 1e, the distance between the semiconductor laser 1e and the photodetector 1c, and the pitch of the hologram 1h are shown in FIG.
Is the same as that shown in FIG. The other parts are the same as those of the optical pickup 291, and the other description is omitted.

The optical pickup according to the present invention comprises:
Furthermore, the configuration shown in FIGS. 33 to 36 may be used. The optical pickup shown in FIGS. 33 to 36 has a configuration in which the hologram 297 is separated from the optical means 292 in the optical pickup 291 of FIG. 29, and a collimator lens 298 is added. Also in this case, the optical means 292
The distance between the semiconductor lasers 1a and 1e and the hologram 297, the distance between the semiconductor laser 1a and the semiconductor laser 1e, the distance between the semiconductor laser 1e and the photodetector 1c, the hologram 2
The pitch of 97 is the same as that shown in FIG. The hologram 297 may be located before the collimator lens 298 as shown in FIG. 33, or may be located immediately after the collimator lens 298 as shown in FIG. Further, the hologram 297 further includes a collimator lens 298.
The hologram 297 may be provided on the front and rear surfaces of the collimator lens 298 as shown in FIGS.

A reproducing apparatus for compatible reproduction of a CD or CD-R having a substrate thickness of 1.2 mm and a high-density DVD having a substrate thickness of 0.3 mm is the apparatus shown in FIG. 17 in the first embodiment. The same playback device can be used. In the first to third embodiments, reproduction from an optical disk has been described. However, the present invention is not limited to this, and recording on an optical disk can be performed using each of the optical pickup devices described above.

Further, in the first to third embodiments, the wavelength of the laser beam generated from the optical means is 635 nm and 780 nm, and 480 nm and 635 nm
Although m and the combination of 480 nm and 780 nm have been described, it is needless to say that the present invention is not limited to this, and may be a combination of laser beams having other wavelengths.

[0054]

According to the present invention, the light source has a wavelength of 635n.
Since two semiconductor lasers having different wavelengths of 780 nm and 780 nm are used, the optical disk DV having a substrate thickness of 0.6 mm is used.
Compatible reproduction between D and CD-R, which is an optical disk having a substrate thickness of 1.2 mm, can be performed.

According to the present invention, the light source has a wavelength of 48.
Since two semiconductor lasers having different wavelengths of 0 nm and 635 nm are used, it is possible to perform compatible reproduction between a high-density DVD which is an optical disk having a substrate thickness of 0.3 mm and a DVD which is an optical disk having a substrate thickness of 0.6 mm. According to the invention, the light source has a wavelength of 480 nm and a wavelength of 780 nm.
Are used, it is possible to perform compatible reproduction between a high-density DVD, which is an optical disk having a substrate thickness of 0.3 mm, and a CD or CD-R, which is an optical disk having a substrate thickness of 1.2 mm.

According to the present invention, since the laser beam generating means, the light detecting means, and the optical means integrated with the hologram are used, it is not necessary to use a half mirror and a rising mirror to constitute an optical pickup. A compact optical pickup can be manufactured, which leads to low cost. Further, according to the present invention, it is possible to realize an optical pickup capable of reproducing a CD-R with substantially the same configuration as a conventional optical system.

According to the present invention, if the optical axis is adjusted with respect to a laser beam having a wavelength of 635 nm, the wavelength is 780 nm.
The optical axis can be adjusted with respect to the laser beam. Further, according to the present invention, if the optical axis is adjusted for a laser beam having a wavelength of 480 nm, the optical axis can be adjusted for a laser beam having a wavelength of 635 nm. According to the present invention, the wavelength 4
If the optical axis is adjusted for a laser beam of 80 nm, the optical axis can be adjusted for a laser beam of a wavelength of 780 nm.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an optical pickup according to a first embodiment.

FIG. 2 is a diagram illustrating a method of calculating a distance between a semiconductor laser, a hologram, and a photodetector according to the first to third embodiments.

FIG. 3 is a diagram illustrating a method for calculating a distance between two semiconductor lasers, a hologram, and a photodetector in the first to third embodiments.

FIG. 4 is a table showing a calculation result of a distance between two semiconductor lasers, a hologram, and a photodetector in the first embodiment.

FIG. 5 is a diagram illustrating a mount of a semiconductor laser and a photodetector according to the first to third embodiments.

FIG. 6 is a diagram illustrating a specific example of a numerical aperture changing unit according to the first to third embodiments.

FIG. 7 is a diagram showing another specific example of the numerical aperture changing means in the first to third embodiments.

FIG. 8 is a diagram showing another specific example of the numerical aperture changing unit in the first to third embodiments.

FIG. 9 is a diagram for explaining a reproducing operation of an optical disk having a substrate thickness of 0.6 mm according to the first embodiment.

FIG. 10 shows a substrate thickness of 1.2 mm in the first embodiment.
FIG. 4 is a diagram for explaining the reproduction operation of the optical disk of FIG.

FIG. 11 is a diagram illustrating another configuration of the optical pickup according to the first embodiment.

FIG. 12 is a diagram showing still another configuration of the optical pickup according to the first embodiment.

FIG. 13 is a diagram showing still another configuration of the optical pickup according to the first embodiment.

FIG. 14 is a diagram showing still another configuration of the optical pickup according to the first embodiment.

FIG. 15 is a diagram showing still another configuration of the optical pickup according to the first embodiment.

FIG. 16 is a diagram showing still another configuration of the optical pickup according to the first embodiment.

FIG. 17 is a diagram illustrating a playback device according to the first to third embodiments.

FIG. 18 is a table showing rated values and reproduction conditions of CD, CD-R, and DVD.

FIG. 19 is a table showing rated values and reproduction conditions of a DVD and a high-density DVD.

FIG. 20 is a diagram illustrating a configuration of an optical pickup according to a second embodiment.

FIG. 21 is a table showing a calculation result of a distance between two semiconductor lasers, a hologram, and a photodetector in the second embodiment.

FIG. 22 is a diagram illustrating another configuration of the optical pickup according to the second embodiment.

FIG. 23 is a diagram showing still another configuration of the optical pickup according to the second embodiment.

FIG. 24 is a diagram showing still another configuration of the optical pickup according to the second embodiment.

FIG. 25 is a diagram showing still another configuration of the optical pickup according to the second embodiment.

FIG. 26 is a diagram showing still another configuration of the optical pickup according to the second embodiment.

FIG. 27 is a diagram showing still another configuration of the optical pickup according to the second embodiment.

FIG. 28 is a table showing rated values and reproduction conditions of CD, CD-R, and high-density DVD.

FIG. 29 is a diagram illustrating a configuration of an optical pickup according to a third embodiment.

FIG. 30 is a table showing a calculation result of a distance between two semiconductor lasers, a hologram, and a photodetector in the third embodiment.

FIG. 31 is a diagram illustrating another configuration of the optical pickup according to the third embodiment.

FIG. 32 is a diagram showing still another configuration of the optical pickup according to the third embodiment.

FIG. 33 is a diagram showing still another configuration of the optical pickup according to the third embodiment.

FIG. 34 is a diagram illustrating still another configuration of the optical pickup according to the third embodiment.

FIG. 35 is a diagram showing still another configuration of the optical pickup according to the third embodiment.

FIG. 36 is a diagram showing still another configuration of the optical pickup according to the third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical means 1a, 1b, 1e ... Semiconductor laser 1c ... Photodetector 1d, 1g, 1h, 2, 207, 297 ... Hologram 3, 208, 298 ... Collimator lens 4. ..Aperture changing means 5 ... Objective lens 6 ... Actuator 7, 77 ... Substrate 7a, 77a ... Signal recording surface 10 ... Optical pickup 11 ... Preamplifier 12 ... Servo circuit Reference Signs List 13 servo mechanism 14 discrimination circuit 15 command circuit 16 RF demodulation circuit 17 characteristic switching circuit 18 laser drive circuit 19 control circuit

Continued on the front page (72) Inventor Masato Yamada 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Yoichi Tsuchiya 2-5-5-1 Keihanhondori, Moriguchi-shi, Osaka Sanyo Inside Electric Co., Ltd. (72) Inventor Shuichi Ichiura 2-5-1-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-62-200543 (JP, A) JP-A-9-95 270145 (JP, A) JP-A-9-73017 (JP, A) JP-A-9-120568 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/135

Claims (7)

(57) [Claims] 1. Recording and / or reproduction of a first optical disk having a transparent substrate of a first thickness and a second optical disk having a transparent substrate of a second thickness different from the first thickness. An optical pickup device, comprising: an objective lens provided to face an optical disc on which the recording or / and / or reproduction is to be performed; A numerical aperture changing means for changing a numerical aperture of the objective lens; a first semiconductor laser for generating a first laser beam;
A second semiconductor laser that generates a laser beam of
Laser light, and the optical disk of the second laser light.
Light detecting means for detecting light reflected from the signal recording surface of the laser,
The first laser generated by the first semiconductor laser;
Laser light is diffracted in a first direction and the second semiconductor laser
The second laser light generated by the first laser
Diffracted in a second direction different from the first direction,
Laser light, and the optical disk of the second laser light.
A guide for guiding the reflected light from the signal recording surface of the
Optical means including a first semiconductor laser and a second semiconductor laser.
Z ₀ the distance between the over THE, the first semiconductor laser and the optical
The distance from the detection means is Z ₁ , the distance from the second semiconductor laser is
The distance from the light recording detecting means is Z ₂ , and the first semiconductor laser is
L and the hologram pitch
H, the wavelength of the first laser beam is λ ₁ ,
When the wavelength of the laser beam is λ ₂ , Z ₁ = Lλ ₁ / (p ² −λ ₁ ² ) ^1/2 , Z ₂ = Lλ ₂ / (p ² −λ ₂ ² )
An optical pickup device having a relationship of ^1/2 , Z ₀ = Z ₂ -Z ₁ . 2. Recording and / or reproduction of a first optical disk having a transparent substrate of a first thickness and a second optical disk having a transparent substrate of a second thickness different from the first thickness are performed. An optical pickup device, comprising: an objective lens provided to face an optical disc on which the recording or / and / or reproduction is to be performed; A numerical aperture changing means for changing a numerical aperture of the objective lens; a first semiconductor laser for generating a first laser beam;
A second semiconductor laser that generates a laser beam of
Laser light, and the optical disk of the second laser light.
Light detecting means for detecting reflected light from the signal recording surface of the
Optical means including: the first laser light from the optical means is diffracted in a first direction; the second laser light is diffracted in a second direction different from the first direction; and the laser beam guides on the objective lens, and a hologram for guiding the first laser beam, and the reflected light from the signal recording surface of the second of the optical disk of the laser light to the optical unit, further wherein A first semiconductor laser and the second semiconductor laser;
Z ₀ the distance between the over THE, the first semiconductor laser and the optical
The distance from the detection means is Z ₁ , the distance from the second semiconductor laser is
The distance from the light recording detecting means is Z ₂ , and the first semiconductor laser is
L and the hologram pitch
H, the wavelength of the first laser beam is λ ₁ ,
When the wavelength of the laser beam is λ ₂ , Z ₁ = Lλ ₁ / (p ² −λ ₁ ² ) ^1/2 , Z ₂ = Lλ ₂ / (p ² −λ ₂ ² )
An optical pickup device having a relationship of ^1/2 , Z ₀ = Z ₂ -Z ₁ . 3. Recording and / or reproduction of a first optical disk having a transparent substrate of a first thickness and a second optical disk having a transparent substrate of a second thickness different from the first thickness are performed. An optical pickup device, comprising: an objective lens provided to face an optical disc on which the recording or / and / or reproduction is to be performed; A numerical aperture changing means for changing a numerical aperture of the objective lens; a first semiconductor laser for generating a first laser beam;
A second semiconductor laser that generates a laser beam of
Laser light, and the optical disk of the second laser light.
Light detecting means for detecting light reflected from the signal recording surface of the laser,
The first laser generated by the first semiconductor laser;
Laser light is diffracted in a first direction and the second semiconductor laser
The second laser light generated by the first laser
Causes diffracted in a second direction that different from the direction, the first
Laser light, and the optical disk of the second laser light.
A guide for guiding the reflected light from the signal recording surface of the
And a collimator lens that receives the first laser light from the optical means, and the second laser light, and guides the received laser light to the objective lens . The first semiconductor laser and the second semiconductor laser
Z ₀ the distance between the over THE, the first semiconductor laser and the optical
The distance from the detection means is Z ₁ , the distance from the second semiconductor laser is
The distance from the light recording detecting means is Z ₂ , and the first semiconductor laser is
L and the hologram pitch
H, the wavelength of the first laser beam is λ ₁ ,
When the wavelength of the laser beam is λ ₂ , Z ₁ = Lλ ₁ / (p ² −λ ₁ ² ) ^1/2 , Z ₂ = Lλ ₂ / (p ² −λ ₂ ² )
An optical pickup device having a relationship of ^1/2 , Z ₀ = Z ₂ -Z ₁ . 4. Recording and / or reproduction of a first optical disk having a transparent substrate of a first thickness and a second optical disk having a transparent substrate of a second thickness different from the first thickness are performed. An optical pickup device, comprising: an objective lens provided to face an optical disk on which recording or / and reproduction is to be performed; and an objective lens according to a thickness of a transparent substrate of the optical disk on which recording or / and reproduction is to be performed. A numerical aperture changing means for changing a numerical aperture of the objective lens; a first semiconductor laser for generating a first laser beam;
A second semiconductor laser that generates a laser beam of
Laser light, and the optical disk of the second laser light.
Light detecting means for detecting reflected light from the signal recording surface of the
An optical unit including: a collimator lens that receives the first laser light and the second laser light from the laser light generation unit and guides the received light to the objective lens; And diffracting the first laser light in a first direction, diffracting the second laser light in a second direction different from the first direction, the first laser light, and A hologram for guiding reflected light of the second laser light from the signal recording surface of the optical disc to the optical means; and further comprising the first semiconductor laser and the second semiconductor laser.
Z ₀ the distance between the over THE, the first semiconductor laser and the optical
The distance from the detection means is Z ₁ , the distance from the second semiconductor laser is
The distance from the light recording detecting means is Z ₂ , and the first semiconductor laser is
L and the hologram pitch
H, the wavelength of the first laser beam is λ ₁ ,
When the wavelength of the laser beam is λ ₂ , Z ₁ = Lλ ₁ / (p ² −λ ₁ ² ) ^1/2 , Z ₂ = Lλ ₂ / (p ² −λ ₂ ² )
An optical pickup device having a relationship of ^1/2 , Z ₀ = Z ₂ -Z ₁ . 5. The wavelength λ ₁ of said first laser beam is 620
660 nm, and the wavelength of the second laser light.
λ ₂ is in the range of 760 to 800 nm,
The distance Z ₀ between the semiconductor laser and the second semiconductor laser is
0.1 to 0.5 mm, wherein the first semiconductor laser
Distance Z ₁ between THE and the light detecting means 0.50~2.2mm
And the pitch p of the hologram is 1.5-3.
5 μm, and the first semiconductor laser and the
That the distance L to the program is in the range of 3 to 25 mm
5. The optical pickup according to claim 1, wherein
apparatus. 6. The wavelength λ ₁ of said first laser beam is 350
550 nm, and the wavelength of the second laser light.
λ ₂ is in the range of 620 to 660 nm, and the first half
The distance Z ₀ between the conductor laser and the second semiconductor laser is 0.3.
The first semiconductor laser having a range of 1 to 0.5 mm;
The distance Z ₁ is range of 0.3~1.5mm and said light detecting means and
And the hologram pitch p is 3 to 12 μm.
The first semiconductor laser and the hologram
Is within a range of 3 to 15 mm.
5. The optical pickup device according to claim 1, wherein: 7. The wavelength λ ₁ of said first laser beam is 350
550 nm, and the wavelength of the second laser light.
λ ₂ is in the range of 760 to 800 nm, and the first half
The distance Z ₀ between the conductor laser and the second semiconductor laser is 0.3.
The first semiconductor laser having a range of 1 to 0.5 mm;
The distance Z ₁ is range of 0.2~1.0mm and said light detecting means and
And the pitch p of the hologram is 5 to 12 μm.
The first semiconductor laser and the hologram
To the distance L is characterized by a range of 2~15mm with
5. The optical pickup device according to claim 1, wherein: