JPH0944886A - Optical pickup and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup and a reproducing device capable of reproducing plural optical disks with different thickness using the same optical system. SOLUTION: Read light from a laser diode 11a is converted into a P polarization component and an S polarization component by a 1/2 wavelength plate 11c, and passes through a beam splitter 12 to be cast on an aberration correction plate 15. The P polarization component of the read lightpasses through the aberration correction plate 15 as it is to be converged on a recording surface of a first optical disk, and the S polarization component is converged on the recording surface of a second optical disk after the correction is performed by the aberration correction plate 15. The P polarization component, S polarization component of the read light reflected by the reflection surface of the optical disk are separated by the beam splitter 14a to be received respectively by photodetectors 14b, 14c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for being provided in a reproducing apparatus for reproducing information recorded on an optical recording medium such as an optical disk, and easily reproducing from an optical recording medium having a different thickness. Optical pickups that can

[0002]

2. Description of the Related Art Conventionally, an optical disk reproducing apparatus for reproducing information recorded on an optical disk is known. Such an optical disc reproducing apparatus, as shown in FIG. 7, for example, follows an optical pickup 100 that reproduces information recorded on the optical disc 99 and a recording track formed on the recording surface of the optical disc 99 to follow the optical pickup. A tracking control unit 117 that moves 100 and an optical pickup 100.
A focus adjustment unit 118 that adjusts the focus of the optical pickup 100 so that the reading light from the optical disc 99 is focused on the recording surface of the optical disc 99, and the optical pickup 100.
An information reproducing system 110 for reproducing the information recorded on the optical disc 99 from the reproduction output from

The pickup 100 has a light source 101 for generating reading light and a beam splitter 102 for transmitting the reading light from the light source 101 and for reflecting the reading light reflected on the recording surface of the optical disc 99.
The objective lens 103 for condensing the reading light on the recording surface of the optical disc 99 and the light receiving element 104 for receiving the reading light reflected by the recording surface of the optical disc 99 and outputting a pickup signal.

When the optical disc 99 is reproduced, the tracking control section 117 controls the position of the optical pickup 100 so that the reading light follows the recording track of the optical disc 99 to control the tracking. At the same time, the focus adjustment unit 118 moves the objective lens 103 of the optical pickup 100 up and down to adjust the focus so that the reading light is focused on the recording surface of the optical disc 99. Then, when the reading light from the optical pickup 100 is applied to the recording track with the tracking and focus adjusted in this way, the reading light is reflected with an intensity according to the recorded contents of the recording track. The optical pickup 100 receives the reflected light and outputs a reproduction output according to the intensity of the reflected light to the information reproducing system 1.
Supply to 10. In such a state, the information reproducing system 110 reproduces information such as audio, video, and file from the reproduction output supplied from the optical pickup 100 and supplies the information to an external device or the like.

By the way, in recent years, various optical discs of different formats have been proposed, but if a reproducing apparatus is prepared for each of these optical discs, a large installation space is required and power consumption increases. Also, in terms of the purchase cost of the playback device corresponding to each optical disc,
There is a demand for a reproducing apparatus capable of reproducing optical discs of a plurality of formats. However, since these optical discs are not only different in format but also different in physical size such as thickness of the optical disc, they are the same. It is difficult to reproduce with a reproducing device.

As shown in the cross sections of FIGS. 8A and 8B, these optical discs have a protective layer 99b made of transparent resin such as polycarbonate on the surface thereof in order to protect the recording surface 99a. Have These protective layers 99
Since b has a refractive index different from that of the surrounding space, the reading light condensed by the objective lens 103 of the optical pickup 100 is refracted and condensed when entering the protective layer 99b.
Therefore, the reading light that has entered the protective layer 99b is not focused at the focal position when it is focused in air, but is focused at different positions depending on the incident angle with respect to the protective layer 99b. It produces spherical aberration.

Therefore, in general, the shape of the objective lens 103 is corrected in consideration of the light condensing state in the protective layer 99b, and the reading light incident at each incident angle is recorded on the recording surface 9.
The light is focused on 9a. As a result, the reading light can be efficiently focused on the recording surface.

[0008]

However, since the light collecting state in the protective layer changes depending on the thickness of the protective layer, it is not possible to use the same optical system for the protective layers having different thicknesses. Can not. That is, in the case of reproducing optical discs having different thicknesses as described above, when an optical system optimized for the thickness of the protective layer of one optical disc is used, when reproducing the other optical disc, Since the thickness of the protective layer taken into consideration for the correction is different from the actual thickness of the protective layer, the reading light spreads due to the above-mentioned spherical aberration, and the reading light cannot be focused on the recording surface.

Therefore, it is possible to correct the objective lens 103 with respect to the average thickness of the protective layer 99b of a plurality of optical disks. In this case, the wavefront aberration for each optical disk is completely eliminated. Since it cannot be eliminated, deterioration of the read output on the recording surface is inevitable.

Therefore, conventionally, it was not possible to reproduce an optical disk having a different protective layer thickness using the same optical system.

Further, by providing a plurality of pickups optimized for each optical disc and reproducing each disc by each pickup, it is possible to reproduce a plurality of discs without deterioration of reproduction output. it can. However, in this case, since it is necessary to provide a plurality of pickups, it is difficult to reduce the size of the reproducing apparatus, and the number of parts increases, so that the cost of the reproducing apparatus increases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical pickup capable of reproducing a plurality of optical disks without deterioration of reproduction output.

Another object of the present invention is to provide a reproducing apparatus capable of reproducing a plurality of optical disks without deterioration of reproduction output.

[0014]

An optical pickup according to the present invention is provided with at least two types of first and second different thicknesses.
Is an optical pickup which irradiates the recording surface of the optical recording medium with the reading light, receives the reading light reflected on the recording surface, and outputs a pickup signal, the reading light having a first or second polarization component. Is inserted between the light source section and the optical recording medium, and an optical system for converging light emitted from the light source section onto the recording surface of the first optical recording medium.
The optical system is not corrected for the reading light of the first polarization component, and the reading light of the second polarization component of the reading light of the second polarization component of the second optical recording medium is not corrected. And an optical system correcting means for correcting the optical system so that the light is focused on the recording surface.

Further, the optical pickup according to the present invention comprises a polarization component separation means for separating the reading light reflected on the recording surface of the optical recording medium into a first polarization component and a second polarization component, and the polarization component separation. A first light receiving means for receiving a first polarization component of the reading light separated by the means and outputting a light reception output; and a second light receiving component for the reading light separated by the polarization component separating means. And a second light receiving means for outputting a light receiving output.

The reproducing apparatus according to the present invention is a reproducing apparatus for reproducing information recorded on at least two kinds of first and second optical recording media having different thicknesses, and the first or second polarization component. A light source unit for generating reading light having an optical system, an optical system for converging light emitted from the light source unit on a recording surface of the first optical recording medium, and a light source unit inserted between the light source unit and the optical recording medium. No correction is made to the optical system for the reading light of the first polarization component, and for the reading light of the second polarization component,
An optical pickup having an optical system correcting means for correcting the optical system so that the reading light of the second polarized component is condensed on the recording surface of the second optical recording medium, and a pickup signal from the pickup. And information reproducing means for reproducing information from the.

Further, in the reproducing apparatus according to the present invention, the optical pickup includes polarization component separating means for separating the reading light reflected by the recording surface of the optical recording medium into the first polarization component and the second polarization component. A first light receiving means for receiving a first polarized light component of the reading light separated by the polarized light component separating means and outputting a light reception output; and a second polarized light component of the reading light separated by the polarized light component separating means. Second light receiving means for receiving light and outputting a light reception output. Further, in this reproducing apparatus, the information reproducing means has an output selecting means for outputting the light reception output of the first light receiving means or the second light receiving means as a pickup signal according to the type of the optical recording medium to be reproduced. And

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A case where the optical pickup and the reproducing apparatus according to the present invention are applied to an optical disk reproducing apparatus for reproducing an optical disk will be described below. The optical pickup of the present invention is used as the optical pickup of this optical disc reproducing apparatus.

As shown in FIG. 1, this optical disk reproducing apparatus includes an optical pickup 10 for reproducing information recorded on the optical disk 1, a tracking control system 20 for controlling tracking, and a focus adjusting system for adjusting focus. 30, a data reproduction system 40 for reproducing data from the reproduction output of the optical pickup 10, a system controller 50 for controlling the entire apparatus, and a rotation control system for controlling the rotation of the optical disc 1.

The data reproduction system 40 has an amplifier 41 for amplifying the pickup signal from the optical pickup 10.
And a matrix circuit 42 for obtaining a tracking error signal (TE), a focus error signal (FE), and a data reproduction signal (RF) from a pickup signal supplied from the amplifier 41, and data from the data reproduction signal from the matrix circuit 42. The data reproducing section 43 for reproducing the data and the output control section 44 for controlling the output of the data reproduced by the data reproducing section 43.

The optical pickup 10 transmits the reading light from the light source section 11 for generating the reading light and reflects the reading light reflected by the recording surface 1a of the optical disc 1 as well. Beam splitter 12 for changing the traveling direction by
The objective lens 13 for condensing the reading light incident on the recording surface of the optical disc 1, and the recording surface 1a of the optical disc 1.
And the optical pickup 1 for receiving the reading light reflected by the beam splitter 12 and incident through the beam splitter 12.
And an aberration correction plate 15 for correcting the optical system of 0.

As shown in FIG. 2, the light source unit 11 is irradiated with a laser diode 11a for generating reading light, a diffraction grating 11b for diffracting the reading light from the laser diode 11a, and the diffraction grating. The ratio of the P-polarized component and the S-polarized component of the reading light is 1: 1
The wave plate 11c is provided.

Further, as shown in FIG. 2, the light receiving section 14 includes a polarization beam splitter 14a for decomposing the reading light reflected by the recording surface of the optical disk which is incident through the beam splitter 12 into respective polarization components. , And light receiving elements 14b and 14c for receiving the respective polarized components separated by the polarization beam splitter 14a.

In the optical disc reproducing apparatus having the above-mentioned structure, when the reproduction of the optical disc is started, the rotation control system rotationally drives the optical disc 1 under the control of the system controller 50 or the like.

The light source unit 11 generates reading light and irradiates the beam splitter 12 with the reading light. This reading light is applied to the objective lens 13 via the beam splitter 12 and the aberration correction plate 15, and the objective lens 13 causes the optical disc 1 to be read.
Is focused on the recording surface of. Then, the reflected light reflected by the recording surface enters the beam splitter 12 along a path opposite to that at the time of focusing. The beam splitter 12 reflects the incident reflected light, changes its traveling direction, and makes it enter the light receiving unit 14.

The light receiving section 14 supplies a pickup signal corresponding to the intensity of the incident reflected light to the matrix circuit 42 via the amplifier 41. The matrix circuit 42 obtains a tracking error signal, a focus error signal, and a data reproduction signal from the pickup signal, and outputs the tracking error signal, the focus error signal, and the data reproduction signal, respectively, to the tracking control unit 20 and the focus control unit 3.
0, and supplied to the data reproducing unit 43.

Specifically, the diffraction grating 11b as described above is used.
The reading light that has passed through is diffracted in the radial direction of the optical disc 1, that is, in the width direction of the recording track on the recording surface into 0th-order light, plus 1st-order light, minus 1st-order light, etc. The light is focused on the first recording surface. That is, the plus first-order light and the minus first-order light are 0
It is condensed at a position apart from the next light by a predetermined length in the width direction of the recording track.

When the 0th order light is accurately scanning the recording track, the plus 1st order light and the minus 1st order light are symmetrically applied to the recording track, and their intensities are equal to each other. On the other hand, when the 0th-order light is scanning a position away from the recording track, the intensities of the plus primary light and the minus primary light differ depending on the distance from the recording track.

Therefore, in this optical pickup 10,
To obtain the intensities of plus primary light and minus primary light,
The light receiving surface of each of the light receiving elements 14b and 14c is divided in correspondence with 0th order light, plus 1st order light, and minus 1st order light. The matrix circuit 42 detects the level of the pickup signal from each light receiving surface, and detects the tracking error from the difference between the pickup signals of the plus primary light and the minus primary light.

Then, the tracking controller 20 drives the optical pickup 10 based on the tracking error signal supplied from the matrix circuit 42 to control the tracking. As a result, the light source section 11 to the light receiving element 14 are integrally moved while maintaining their relative positional relationships. As a result, the reading light focused by the objective lens 13 scans the recording track formed on the recording surface of the optical disc 1.

On the other hand, the focus control section 30 drives the objective lens 13 of the optical pickup 10 up and down with respect to the optical disk 1 based on the focus error signal supplied from the matrix circuit 42 to adjust the focus. As a result, even if the height of the recording surface of the optical disk 1 varies due to the tilt of the optical disk, the reading light can be kept focused on the recording surface.

Further, the data reproducing section 43 reproduces the data by subjecting the data reproduced signal from the matrix circuit 42 to processing such as demodulation and error correction, and outputs the reproduced data via the output control section 44. As a result, this optical disk reproducing apparatus reproduces data from the recording track formed on the recording surface of the optical disk 1.

By the way, this optical disk reproducing apparatus can reproduce optical disks of two different thicknesses, as shown in FIGS. 3 (A) and 3 (B).
As shown in FIG. 3A, the first optical disc has a thickness d1 of about 1.2 mm and a thickness t1 of transparent resin such as polycarbonate on the surface of the recording surface 1a on which data is recorded. The protective layer 1b is formed. Also, the second
The optical disc has a thickness d as shown in FIG.
2 is about 0.6 mm, recording surface 1d on which data is recorded
Thickness of t1 made of resin such as polycarbonate on the surface of
Protective layer 1e is formed. Further, protective layers 1c and 1c are formed on the back surfaces of the recording surfaces 1a and 1d of the above-mentioned two types of optical disks, respectively.

On the first optical disc, the objective lens 13
When the reading light focused by is incident on the protective layer 1b, the refractive index of the space outside the optical disc 1 is different from that of the protective layer 1b. Therefore, as shown in FIG. It is refracted and condensed. Therefore, an aberration such as a spherical aberration that is different from the focusing in the surrounding space occurs, and the beam spot diameter to be focused becomes large.

Therefore, in this optical pickup 10,
In consideration of the thickness of the protective layer 1b, the shape of the objective lens 13 is optimized so that aberrations such as spherical aberration are reduced to prevent the beam spot diameter from increasing due to spherical aberration.

When the second optical disc is irradiated with the reading light by using the objective lens 13 optimized for the first optical disc as described above, the incident reading light is protected as in the case of the first optical disc. The light is refracted and condensed at the boundary of the layer 1e.

However, since the thickness of the protective layer 1e of the second optical disc is different from the thickness of the protective layer 1b of the first optical disc, the distance that the focused reading light propagates in the protective layer is long. Then, an aberration different from that at the time of focusing in the protective layer 1b occurs, and the beam spot diameter increases.

Therefore, in this optical pickup 10,
The reading light is converted into a P-polarized component and an S-polarized component, the optical system is not corrected for the P-polarized component, and the S-polarized component for the S-polarized component is read by the second optical disc. The correction is performed so that the light is focused on the recording surface.

That is, the reading light from the laser diode 11a is converted into a P-polarized component and an S-polarized component by the half-wave plate 11c, passes through the beam splitter, and is applied to the aberration correction plate 15. The aberration correction plate 15 is composed of a polarization hologram, a birefringent crystal, or the like, and is corrected so that the P-polarized component of the reading light is directly transmitted and the S-polarized component of the reading light is condensed on the recording surface of the second optical disc. Give. Therefore, as shown in FIG. 3A, the P-polarized light component of the read light is the objective lens 13
Is condensed at a position corresponding to the recording surface of the first optical disc, and the S-polarized component of the read light is corrected by the aberration correction plate 15, so that as shown in FIG. It is condensed by the objective lens 13 at a position corresponding to the recording surface of the second optical disc.

Here, when reproducing the first optical disk, the P-polarized component of the reading light is condensed on the recording surface of the first optical disk and the P of the reading light reflected by the recording surface is reflected.
The polarized component is applied to the beam splitter 12 via the objective lens 13 and the correction plate 15, and then to the polarized beam splitter 14a. This polarization beam splitter 1
4a transmits the P-polarized component and reflects the S-polarized component. As a result, the P-polarized component of the reading light reflected by the recording surface of the optical disc is changed to the polarization beam splitter 1
The light passes through 4a and enters the light receiving element 14b. On the other hand, the S-polarized light component of the reading light is reflected on the recording surface and enters the light receiving element 14c like the P-polarized light component, but the S-polarized light component of the reading light is condensed at a position corresponding to the second optical disc. Therefore, when reflected by the recording surface of the first optical disk, the light is diverged and the strength is reduced.

When reproducing the second optical disc, the S-polarized component of the reading light is condensed on the recording surface of the second optical disc, and the S-polarized component of the reading light reflected by the recording surface is The beam splitter 12 is irradiated through the objective lens 13 and the correction plate 15, reflected by the polarization beam splitter 14a, and then incident on the light receiving element 14c. On the other hand, the P-polarized component of the reading light is reflected on the recording surface and enters the light receiving element 14b similarly to the S-polarized component, but the P-polarized component of the reading light is condensed at a position corresponding to the first optical disc. Therefore, when reflected by the recording surface of the second optical disc, the light is diverged and the intensity is reduced.

Then, the system controller 50
When reproducing the first optical disc, the light receiving element 14
The pickup signal of b is controlled so as to be supplied to the matrix circuit 42 via the head amplifier 41,
When reproducing the second optical disk, control is performed so that the pickup signal of the light receiving element 14c is supplied to the matrix circuit 42 via the head amplifier 41.

As a result, when reproducing the first optical disc, the output of the light receiving element 11b which receives the reflected light of the P-polarized component of the reading light focused on the recording surface of the first optical disc is used as the pickup signal. When reproducing the second optical disc, the light receiving element 11 for receiving the reflected light of the S-polarized component of the reading light focused on the recording surface of the second optical disc.
The output of c can be the pickup signal.

As a result, the optical pickup 10 has the same objective lens 13 depending on the optical disc to be reproduced.
Can be corrected, and the reading light can be well focused on the recording surfaces of the plurality of optical disks. Therefore, in this optical disk reproducing apparatus, it is possible to reproduce a plurality of optical disks having different protective layer thicknesses by one optical system without lowering the reliability.

Therefore, the number of parts can be reduced as compared with the case where a plurality of optical systems optimized for each optical disk are provided, and thus the size and weight of the device can be easily reduced. In addition, the cost of the device can be reduced by reducing the number of parts.

In the above description, the half-wave plate 11 is used.
The reading light was converted into the P-polarized component and the S-polarized component by c. However, by tilting the polarization axes of the aberration correction plate 15 and the polarization beam splitter 14a with respect to the polarization axis of the laser diode 11a by 45 °, It is possible to eliminate the need for the two-wave plate 11c.

In this case, as shown in FIG.
Instead of the aberration correction plate 15 and the polarization beam splitter 14a in the inside, an aberration correction plate 15a and a polarization beam splitter 14d whose polarization axis is inclined by 45 ° with respect to the polarization axis of the laser diode 11a are provided.

The light from the laser diode 11a is applied to the aberration correction plate 15a via the diffraction grating 11b and the beam splitter 12. Since the polarization axis of the aberration correction plate 15a is tilted by 45 ° with respect to the polarization axis of the laser diode 11a as described above, 50% of the P polarization component of the reading light and 50% of the S polarization component of the reading light are arranged. % (Hereinafter referred to as the first polarization component) is transmitted as it is, and
Correction is performed so that 50% of the remaining P-polarized component and 50% of the S-polarized component (hereinafter referred to as the second polarized component) are focused on the recording surface of the second optical disc.

Therefore, the first polarized light component is condensed at the position corresponding to the recording surface of the first optical disk, and the second polarized light component is condensed at the position corresponding to the recording surface of the second optical disk. It

The first and second polarization components of the reading light reflected by the reflection surface of the optical disc are applied to the polarization beam splitter 14d via the objective lens 13, the aberration correction plate 15a and the beam splitter 12. Since the polarization axis of the polarization beam splitter 14d is inclined by 45 ° with respect to the polarization axis of the laser diode 11a as described above, the polarization beam splitter 14d transmits the first polarization component and also transmits the second polarization component. To reflect.

Then, the first polarization component condensed at the position corresponding to the recording surface of the first optical disk is received by the light receiving element 14
The second polarized light component which is incident on b and is condensed at the position corresponding to the recording surface of the second optical disc is incident on the light receiving element 14c. Then, the system controller 50 supplies the output of the light receiving element 14b to the matrix circuit 42 when reproducing the first optical disk, and when reproducing the second optical disk, according to the type of the optical disk to be reproduced. Control is performed so that the output of the light receiving element 14c is supplied to the matrix circuit 42.

As a result, the optical pickup 10 has the same objective lens 13 depending on the optical disc to be reproduced.
Can be corrected, and the reading light can be well focused on the recording surfaces of the plurality of optical disks. Therefore, in this optical disk reproducing apparatus, it is possible to reproduce a plurality of optical disks having different protective layer thicknesses by one optical system without lowering the reliability.

In the above description, the light receiving section 14 is provided with the two light receiving elements 14b and 14c, but the light receiving section may have a plurality of light receiving sections.

In this case, as shown in FIG.
4, an optical block 16 for decomposing the reading light from the beam splitter 12 into the first and second polarization components.
And a light receiving element 17 having two light receiving surfaces 17a and 17b for receiving the first and second polarization components, respectively.

The optical block 16 transmits the first polarized component of the read light from the beam splitter 12 and guides it to the light receiving surface 17a, and at the same time, the first reflective surface 16a that reflects the second polarized component; And a second reflecting surface 16b that reflects the second polarized component reflected by the first reflecting surface 16a and guides it to the light receiving surface 17b. Further, the first reflecting surface 16a is arranged such that its polarization axis is inclined by 45 ° with respect to the polarization axis of the laser diode 11a, as in the above-mentioned polarization beam splitter 11d.

In such an optical pickup 10, as in the optical pickup 10 shown in FIG. 4 described above, the first polarization component is well focused on the recording surface of the first optical disc, and the aberration correction plate is used. Second corrected by 15a
The polarized light component of is favorably focused on the recording surface of the second optical disc. Then, the first and second polarization components of the read light are received by the light receiving surfaces 17a and 17b, respectively.

As a result, in the optical pickup 10, the same objective lens 13 is used depending on the optical disc to be reproduced.
Can be corrected, and the reading light can be well focused on the recording surfaces of the plurality of optical disks. Therefore, in this optical disk reproducing apparatus, it is possible to reproduce a plurality of optical disks having different protective layer thicknesses by one optical system without lowering the reliability.

Further, as described above, the optical pickup 10 has the optical block 16 for separating the first and second polarization components of the reading light and the light receiving element 17 having a plurality of light receiving surfaces. , Laser diode 1
The 1a, the diffraction grating 11b, the beam splitter 12, the optical block 16, the light receiving element 17, and the like can be configured as one package. By configuring these components as one package, assembly of the device, adjustment of the optical axis, etc. can be simplified.

The light-receiving element 17 having such a plurality of light-receiving surfaces is, as shown in FIG.
Can also be used in a configuration in which the reading light is converted into a P-polarized component and an S-polarized component by using.

In this case, as shown in FIG. 6, the light source unit 1
First, the above-mentioned 1/2 polarizing plate 11 for converting the light read from the laser diode 11a into a P-polarized component and an S-polarized component
c is provided so that the polarization axis of the aberration correction plate 15 coincides with the optical axis of the laser diode 11a. Then, similarly to the configuration shown in FIG. 5 described above, the light receiving section 14 is provided with an optical block 16 for separating the P-polarized component and the S-polarized component of the read light, and a light-receiving element 17 having a plurality of light-receiving surfaces 17a and 17b. Set up.

Here, the optical block 16 is provided with a first reflecting surface 16c that transmits the P-polarized component of the reading light and reflects the S-polarized component instead of the above-mentioned first reflecting surface 16a. There is.

The P-polarized component of the read light is the aberration correction plate 1
After passing through 5 as it is, it is condensed on the recording surface of the first optical disc by the objective lens 13. In addition, S of reading light
The polarization component is corrected by the aberration correction plate 15, and is focused on the recording surface of the second optical disc by the objective lens 13.

The P-polarized light component and the S-polarized light component of the reading light reflected on the recording surface are incident on the optical block 16 via the objective lens 13, the aberration correction plate 15 and the beam splitter 12, and the P-polarized light component and the S-polarized light component. It is separated into polarized components.
That is, the P-polarized component is transmitted through the first reflecting surface 11c and enters the light receiving surface 17a, and the S-polarized component is reflected by the first reflecting surface 17c and then reflected by the second reflecting surface 17b. And enters the light receiving surface 17b.

As a result, in this optical pickup 10, the same objective lens 13 is used depending on the optical disc to be reproduced.
Can be corrected, and the reading light can be well focused on the recording surfaces of the plurality of optical disks. Therefore, in this optical disk reproducing apparatus, it is possible to reproduce a plurality of optical disks having different protective layer thicknesses by one optical system without lowering the reliability.

In the above description, each has a thickness of 0.6.
Although the configuration for reproducing two types of optical discs of mm and 1.2 mm has been described, the types of optical discs to be reproduced are not limited to these two types, and the objective lens 13, which corresponds to the optical discs to be reproduced, Aberration correction plate 11
The shape of c can be changed appropriately.

Further, for example, the laser diodes 11a and 11b of the light source section 11 shown in FIG.
Alternatively, using a light source unit packaged as shown in FIG. 6,
The system controller 50 drives one of the four laser oscillating units according to the optical disc to be reproduced, so that four types of optical discs can be reproduced.

[0067]

According to the present invention, the reading light of the first polarized component is not corrected in the optical system, and the reading light of the second polarized component is corrected to the optical system by the optical system correcting means. By performing the correction, the reading light of the first polarized component is condensed on the recording surface of the first optical recording medium, and the reading light of the second polarized component is collected on the recording surface of the second optical recording medium. Can be focused on. This makes it possible to correct the same optical system and focus the reading light on the recording surfaces of a plurality of optical recording media having different thicknesses. Therefore, it is possible to reproduce a plurality of optical recording media having different thicknesses without lowering the reliability of reproducing the data.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical disc reproducing device to which an optical pickup and a reproducing device according to the present invention are applied.

FIG. 2 is a conceptual diagram showing a configuration of an optical pickup which constitutes the optical disc reproducing apparatus.

FIG. 3 is a cross-sectional view showing how reading light is condensed by the optical pickup.

FIG. 4 is a conceptual diagram showing another configuration of the optical pickup which constitutes the optical disc reproducing apparatus.

FIG. 5 is a conceptual diagram showing another configuration of the optical pickup that constitutes the optical disc reproducing apparatus.

FIG. 6 is a conceptual diagram showing another configuration of the optical pickup that constitutes the optical disc reproducing apparatus.

FIG. 7 is a block diagram showing a configuration of a conventional optical disc reproducing apparatus.

FIG. 8 is a cross-sectional view showing how reading light is condensed by an optical pickup that constitutes the conventional optical disc reproducing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 1a, 1d Recording surface 1b, 1c, 1e Protective layer 10 Optical pickup 11 Light source part 11a, 11b Laser diode 11c Aberration correction plate 11d Beam splitter 11e Diffraction grating 11f 1/2 wavelength plate 11g Aperture plate 11h Correction plate drive part 16 Optical block 17a, 17b Light receiving surface 12 Beam splitter 13 Objective lens 14, 17 Light receiving element 20 Tracking control system 30 Focus adjustment system 40 Data reproduction system 50 System controller

Claims (4)

[Claims] 1. A reading light is applied to the recording surfaces of at least two types of first and second optical recording media having different thicknesses, the reading light reflected by the recording surfaces is received, and a pickup signal is output. An optical pickup, which is a light source section for generating reading light having a first or second polarization component, and an optical system for condensing irradiation light from the light source section on a recording surface of the first optical recording medium. Is inserted between the light source section and the optical recording medium, the optical system does not correct the reading light of the first polarized component, and the reading light of the second polarized component is not corrected. And an optical system correcting means for correcting the optical system so that the reading light of the second polarization component is condensed on the recording surface of the second optical recording medium. . 2. A polarization component separation means for separating the first polarization component and the second polarization component of the reading light reflected by the recording surface of the optical recording medium, and the reading light separated by the polarization component separating means. First light receiving means for receiving a first polarized light component of the reading light and outputting a light receiving output, and a second light receiving means for receiving a second polarized light component of the reading light separated by the polarization component separating means and outputting a light receiving output. 2. The optical pickup according to claim 1, further comprising: 3. A reproducing apparatus for reproducing information recorded on at least two types of first and second optical recording media having different thicknesses, and generating read light having a first or second polarization component. A light source section, an optical system for converging light emitted from the light source section on the recording surface of the first optical recording medium, and the optical system inserted between the light source section and the optical recording medium. The reading light of the polarization component is not corrected in the optical system, and the reading light of the second polarization component is the reading light of the second optical recording medium with respect to the reading light of the second polarization component. A reproduction characterized by comprising an optical pickup having an optical system correction means for correcting the optical system so that the light is focused on the recording surface, and an information reproduction means for reproducing information from a pickup signal from the pickup. apparatus. 4. The optical pickup comprises a polarization component separation means for separating a first polarization component and a second polarization component of the reading light reflected by the recording surface of the optical recording medium, and the polarization component separation means. First light receiving means for receiving a first polarized component of the separated reading light and outputting a light reception output;
A second light receiving means for receiving a second polarization component of the reading light separated by the polarization component separating means and outputting a light reception output, wherein the information reproducing means is a type of an optical recording medium to be reproduced. 4. The reproducing apparatus according to claim 3, further comprising an output selecting unit that outputs a light receiving output of the first light receiving unit or the second light receiving unit as a pickup signal.