JPH0944885A - 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 different in thickness using the same optical system. SOLUTION: When a first optical disk is reproduced, read light from a first laser diode 11a passes through a beam splitter 11d, and is made incident on an object lens 13 through a diffraction grating 11e and the beam splitter 12 to be converged on the recording surface 1a of the first optical disk. When a second optical disk is reproduced, the read light from a second laser diode 11b is reflected by the reflection surface of the beam splitter 11d after the correction is performed by an aberration correction plate 11c to be converged on the recording surface of the second optical disk. The read light reflected by the recording surface is reflected by the beam splitter 12 to be made incident on a photodetector 14.

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. 9, for example, follows an optical pickup 100 for reproducing 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. 10A and 10B, these optical discs have a protective layer 99b made of transparent resin such as polycarbonate for protecting the recording surface 99a. Have These protective layers 9
Since 9b 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 incident on the protective layer 99b is
It is not focused at the focal position when it is focused in the air,
The light is condensed at different positions depending on the incident angle with respect to the protective layer 99b, and so-called spherical aberration occurs.

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.
An optical pickup which irradiates the recording surface of the optical recording medium with the reading light, receives the reading light reflected by the recording surface, and outputs a pickup signal. An optical system for converging the irradiation light on the recording surface of the first optical recording medium and an optical system inserted into the optical path of the optical system so that the reading light from the light source is condensed on the recording surface of the second optical recording medium. In this way, an optical system correcting means for correcting the optical system is provided.

The optical pickup according to the present invention comprises:
The light source has first and second light emitting parts corresponding to the first and second optical recording media, and a combining means for combining the read light from the first and second light emitting parts. The system correcting means is provided between the second light emitting unit and the combining means.

The reproducing apparatus according to the present invention is a reproducing apparatus for reproducing information recorded on at least two types of first and second optical recording media having different thicknesses, and is a light source for generating reading light. And an optical system for converging the irradiation light from the light source on the recording surface of the first optical recording medium, and the reading light from the light source which is inserted in the optical path of the optical system for recording on the second optical recording medium. The optical pickup has an optical system correcting means for correcting the optical system so that the light is condensed on the surface, and an information reproducing means for reproducing information from a pickup signal from the pickup.

Further, in the reproducing apparatus according to the present invention, the light source of the optical pickup is the first and second light emitting portions corresponding to the first and second optical recording media, and the first and second light emitting portions. And a light emission control unit for driving one of the first and second light emitting units according to the optical recording medium to be reproduced.

[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 a light receiving element 14 that receives the reading light reflected by the beam splitter 12 and incident through the beam splitter 12.

Further, the light source section 11 is, as shown in FIG.
First and second laser diodes 11a and 11b that generate read light, an aberration correction plate 11c that faces the emission surface of the second laser diode 11b, and read light from the first laser diode 11a. And a diffraction grating 11e that diffracts the reading light incident through the beam splitter 11d. The beam splitter 11d transmits the reading light from the second laser diode 11b and reflects the reading light.

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. The reading light transmitted through the beam splitter 12 is focused on the recording surface of the optical disc 1 by the objective lens 13. 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. Beam splitter 12
Reflects the incident reflected light, changes the traveling direction, and makes it enter the light receiving element 14.

The light receiving element 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 obtains a tracking error signal, a focus error signal and a data reproduction signal,
These are supplied to the tracking control unit 20, the focus control unit 30, and the data reproducing unit 43, respectively.

Specifically, the diffraction grating 11e 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 the light receiving element 14 is provided with
It is divided according to the minus primary 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 disc 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 disk, 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.

By the way, when the reading light is irradiated to the second optical disk by using the objective lens 13 optimized for the first optical disk as described above, the incident reading light is incident as in the case of the first optical disk. Are refracted and condensed at the boundary of the protective layer 1e.

However, since the thickness of the protective layer 1e of the second optical disk is different from the thickness of the protective layer 1b of the first optical disk, 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 system controller 50 drives the first laser diode 11a to generate the reading light when reproducing the first optical disc, and when reproducing the second optical disc, the system controller 50 causes the emission surface to face as described above. Then, the reading light is generated by the second laser diode 11b provided with the aberration correction plate 11c.

Thus, when reproducing the first optical disk, the read light from the first laser diode 11a passes through the beam splitter 11d and the diffraction grating 1
1e, incident on the objective lens 13 via the beam splitter 12. Then, as described above, the objective lens 13 is the first
Since it is optimized for the optical disc, the light incident on the objective lens 13 is well focused on the recording surface 1a of the first optical disc as shown in FIG. 3 (A).

Further, when reproducing the second optical disk, the read light from the second laser diode 11b passes through the aberration correction plate 11c and the beam splitter 11d.
Is reflected by the reflection surface of the beam splitter 11d, and then enters the lens 13 via the diffraction grating 11e and the beam splitter 12.

Here, the shape of the aberration correction plate 11c is
The objective lens 13 is composed of a concave lens or the like so as to correct the spherical aberration that occurs when the reading light is focused on the second optical disk. Therefore, the reading light from the second laser diode 11b is corrected in the direction in which the spherical aberration at the time of focusing of the objective lens 13 is canceled.

The reading light thus corrected is
When incident on the objective lens 13, as shown in FIG. 3B, the light is favorably focused on the recording surface 1d of the second optical disc. As a result, in this optical disc reproducing apparatus, since it is possible to reproduce plural optical discs having different thicknesses by using the same optical system, it is possible to reduce the number of parts and to reduce the size and weight of the apparatus. Can be easy.

By the way, in the above description, the two laser diodes 11a and 11b are provided, and the reading light from these laser diodes 11a and 11b is applied to the diffraction grating 11.
A beam splitter 11d that guides the beam to the beam splitter 12 via e is provided, and the light read from one of the laser diodes 11b is corrected to correct the aspherical aberration of the objective lens 13, thereby reproducing a plurality of optical discs having different thicknesses. However, the light source unit 11 may be configured as one package.

In this case, as shown in FIG. 4, the light source unit 11 includes a laser light source 15 having two laser oscillating units 15a and 15b, and a first reflecting surface for transmitting the reading light from the laser oscillating unit 15a. 16a and an optical block 16 including a second reflecting surface 16b that reflects the reading light incident through the above-described aberration correction plate 11c.

Then, the above system controller 50
Drives the laser oscillator 15a when reproducing the first optical disk. The reading light from the laser oscillator 15a passes through the first reflecting surface 16a, passes through the diffraction grating 11e and the beam splitter 12, and then the objective lens 1
3 and is focused by the objective lens 13 on the recording surface 1a of the first optical disc.

Further, the system controller 50 is the second
When reproducing the optical disc, the laser oscillator 15b is driven. The reading light from the laser oscillator 15b is corrected by the aberration correction plate 11c as described above, and then reflected by the second reflecting surface 16b and the first reflecting surface 16a.
The objective lens 13 is irradiated with the light through the diffraction grating 11e and the beam splitter 12, and is focused on the recording surface 1d of the second optical disc by the objective lens 13.

Therefore, when the light source unit 11 is constructed as one package in this way, the same optical system can be corrected to reproduce a plurality of optical discs, and at the same time, a component constituting an optical pickup. The points can be reduced. Further, in this case, the optical block 16 corresponding to the beam splitter 11d is connected to the laser oscillator 15
Since the optical block 16 can be provided immediately before a and 15b, the optical block 16 can be downsized and reduced in weight, and the optical pickup can be easily reduced in size and weight.

Further, when packaging the light source unit 11, it becomes easy to adjust the optical axes of the respective constituent elements in advance, and compared with the case where the respective laser diodes and the beam splitter are separately configured. It is possible to easily adjust the optical axis when assembling the device.

Since such a light source unit 11 is packaged, there is no need to change the design of the optical system,
It can be replaced with a light source of an optical pickup of a conventional optical disc reproducing apparatus for reproducing a single optical disc. Accordingly, it is possible to configure a reproducing device capable of reproducing a plurality of optical disks having different thicknesses by simply changing the light source.

A polarizing beam splitter film (hereinafter referred to as a PBS film) that reflects the S-polarized light component of the incident read light and transmits the P-polarized light component of the read light on the reflecting surface of the beam splitter 11d. The polarized beam splitter described above may be used.

In this case, the laser diodes 11a, 1
1b are arranged so as to generate only P-polarized components,
As shown in FIG. 5, P immediately before the laser diode 11b.
A half-wave plate 11f that polarizes the reading light of the polarization component into the S-polarization component is provided. Alternatively, without providing the half-wave plate 11f, the laser diode 11a is arranged so as to generate only the P polarization component, and the laser diode 11b is arranged so as to generate only the S polarization component.

As a result, the read light of the P-polarized component from the laser diode 11a is emitted from the beam splitter 11d.
Of the laser diode 1 through the beam splitter 12 through the PBS film on the reflection surface of the laser diode 1.
The readout light of the S-polarized component from 1b is reflected by the PBS film on the reflecting surface of the beam splitter 11d and is irradiated onto the objective lens 13 via the beam splitter 12.

Therefore, S from the laser diode 11b
A correction for compensating for aberration such as spherical aberration of the objective lens 13 can be applied only to the reading light of the polarization component, and a plurality of discs having different thicknesses can be reproduced by the same optical system as in the above case. .

The PBS film on the reflecting surface of the beam splitter 11d transmits almost 100% of the P-polarized component light and reflects almost 100% of the S-polarized component light, and thus the first laser diode 11a. It is possible to improve the transmittance of the reading light from and the reflectance of the reading light from the second laser diode 11a to almost 100%. Therefore, the utilization efficiency of the reading light from the laser diodes 11a and 11b can be improved, and the required output of the laser light can be reduced. This can reduce power consumption.

Further, such a light source unit 11 can be constructed as one package as in the case shown in FIG. In this case, as shown in FIG. 6, the light source unit 11 includes a laser light source 15 including two laser oscillation units 15a and 15b, and a half-wave plate provided on the laser oscillation unit 15b side of the aberration correction plate 11c. 11f and P mentioned above
A first reflecting surface 17a made of a BS film or the like for transmitting the reading light from the laser oscillating unit 15a and a second reflecting surface for reflecting the reading light incident through the aberration correction plate 11c.
And an optical block 17 including a reflection surface 17b of the laser. The laser oscillators 15a and 15b are arranged so as to generate the reading light of the P-polarized component.

The above system controller 50
Drives the laser oscillator 15a when reproducing the first optical disk. The read light of the P-polarized component from the laser oscillation unit 15a passes through the first reflecting surface 16a, is irradiated onto the objective lens 13 via the diffraction grating 11e and the beam splitter 12, and is then reflected by the objective lens 13 It is focused on the recording surface of the first optical disc 1a.

Further, the system controller 50 is
When reproducing the second optical disc, the laser oscillator 15
Drive b. The read light of the P-polarized component from the laser oscillator 15b is converted into the S-polarized component by the ½ wavelength plate, corrected by the aberration correction plate 11c, and then the second reflection surface 1
It is reflected by 7b, further reflected by the first reflecting surface 17a, and is irradiated onto the objective lens 13 through the diffraction grating 11e and the beam splitter 12. The objective lens 13 causes the recording surface of the first optical disc 1a to be irradiated. Collected.

Therefore, when the light source unit 11 is configured as one package in this way, the same optical system is corrected to reproduce a plurality of optical disks, as in the case shown in FIG. 4 described above. In addition, it is possible to reduce the number of parts constituting the optical pickup. This facilitates downsizing and weight reduction of the optical pickup.

Since the light source unit 11 is packaged as in the case shown in FIG. 4, the optical pickup unit of the optical disc reproducing apparatus for reproducing a conventional single optical disc is used. It can be replaced with a light source. Accordingly, it is possible to configure a reproducing device capable of reproducing a plurality of optical disks having different thicknesses by simply changing the light source.

In the above description, the aberration correction plate 11c is used.
Was used to correct the spherical aberration caused by the thickness of the protective layer of the optical disc to be reproduced. However, since this spherical aberration is proportional to the fourth power of the numerical aperture (NA) of the objective lens 13, the optical disc to be reproduced is The spherical aberration can be reduced by changing the numerical aperture of the optical system according to the above.

That is, in this case, as shown in FIG. 7, immediately before the laser diode 11b, instead of the aberration correction plate 11c shown in FIG.
An aperture plate 11g for limiting the emission angle of the reading light from b is provided. As a result, the emission angle of the reading light from the laser diode 11b is limited, and the numerical aperture of the objective lens 13 equivalently decreases. Therefore, the spherical aberration at the time of reproducing the second optical disk is reduced, and the reading light is not
The light can be satisfactorily focused on the recording surface 1d of the optical disc.

Further, in the above description, the light source section 11 is used.
In addition, a plurality of laser diodes 11a and 11b corresponding to each optical disc to be reproduced or a laser oscillator 15
Although the case where a and 15b are provided has been described, as shown in FIG. 8, if the above-mentioned aberration correction plate 11c is taken in and out of the optical path according to the optical disc to be reproduced, even if only one laser diode is provided. Good.

In this case, the above system controller 5
0 selects the laser diode to be driven according to the optical disc to be reproduced as described above, and controls the correction plate driving unit 11h according to the optical disc to be reproduced to move the aberration correction plate 11c in and out of the optical path.

Therefore, in this case, the number of laser diodes can be reduced and the beam splitter 12 can be omitted. As a result, the number of parts of the optical pickup 10 can be reduced, and the weight and size can be easily reduced.

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 unit 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.

[0066]

According to the present invention, the reading light from the light source is focused on the recording surface of the first optical recording medium by the optical system, and the reading light is read by the optical system corrected by the optical system correcting means. By condensing on the recording surface of the second optical recording medium, it is possible to correct the same optical system and condense the reading light on the recording surfaces of a plurality of optical discs having different thicknesses. Therefore, it is possible to reproduce a plurality of optical discs 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 diagram showing another configuration of a light source unit that constitutes the optical pickup.

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

FIG. 6 is a diagram showing another configuration of a light source section that constitutes the optical pickup.

FIG. 7 is a conceptual diagram showing another configuration of the optical pickup that constitutes the optical disc reproducing apparatus.

FIG. 8 is a conceptual diagram showing another configuration of the optical pickup that constitutes the optical disc reproducing apparatus.

FIG. 9 is a block diagram showing a configuration of a conventional optical disc reproducing apparatus.

FIG. 10 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 12 Beam splitter 13 Objective lens 14 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 for generating reading light, an optical system for converging light emitted from the light source on a recording surface of the first optical recording medium, and an optical system inserted in an optical path of the optical system, So that the reading light from the light source is focused on the recording surface of the second optical recording medium,
An optical pickup comprising: an optical system correcting unit that corrects the optical system. 2. The synthesizing means for synthesizing the first and second light emitting portions corresponding to the first and second optical recording media, and the reading light from the first and second light emitting portions, by the light source. 2. The optical pickup according to claim 1, wherein the optical system correcting means is provided between the second light emitting section and the combining means. 3. A reproducing apparatus for reproducing information recorded on at least two types of first and second optical recording media having different thicknesses, the light source generating a reading light, and the irradiation light from the light source. An optical system for condensing the light on the recording surface of the first optical recording medium,
Inserted in the optical path of the optical system, so that the reading light from the light source is condensed on the recording surface of the second optical recording medium,
A reproducing apparatus comprising: an optical pickup having an optical system correcting means for correcting the optical system; and an information reproducing means for reproducing information from a pickup signal from the pickup. 4. The light source of the optical pickup is the first light source.
And a first and a second light emitting portion corresponding to the second optical recording medium, and a synthesizing means for synthesizing the reading light from the first and the second light emitting portion, depending on the optical recording medium to be reproduced. 4. The reproducing apparatus according to claim 3, further comprising a light emission control unit that drives one of the first and second light emitting units.