JPH10312573A - Optical pickup and reproducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect desired information by shielding the part of a first laser beam reflected from the surface of an optical disc passing through a region separated by a specified distance radially from the center of an objective lens thereby shielding the part of the reflected light having adverse effect on a reproduced signal or a focus error signal. SOLUTION: The 0 order diffracted light L1A and the 1 order diffracted lights L1B, L1C of a laser beam L1 are reflected from the reflective surface of a CD 14B and the first through third reflected lights L2A-L2C enter into an objective lens 24. A lens holder 30 is provided with an annular light shielding part shielding the light for a partial region on one side of the objective lens 24 facing a DVD 14A or the CD 14B. According to the arrangement, such part of the first reflected light L2A entering into the objective lens 24 as having a worst effect on a reproduced signal is shielded by the light shielding part of the lens holder 30 and the remaining unshielded first through third reflected lights enter into a multilens 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Table of Contents] The present invention will be described in the following order.

BACKGROUND OF THE INVENTION Problems to be Solved by the Invention (FIGS. 14 to 16) Means for Solving the Problems (FIGS. 1 to 13) Embodiments of the Invention (1) First Embodiment Embodiment (1-1) Configuration of Reproducing Apparatus (FIG. 1) (1-2) Configuration of Optical Pickup According to First Embodiment (FIGS. 1 to 7) (1-3) Operation and Operation of First Embodiment Effects (FIGS. 1 to 7) (2) Second Embodiment (FIGS. 8 and 9) (3) Third Embodiment (FIGS. 1, 10 to 13) (3-1) Third Embodiment Configuration of Optical Pickup According to Embodiment (FIGS. 10 to 13) (3-2) Operation and Effect of Third Embodiment (FIGS. 10 to 13) (4) Other Embodiments Effects of the Invention

[0003]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup and a reproducing apparatus, for example, a DVD (Digital Video Disc).
/ CD (Compact Disc) compatible optical pickup and reproducing apparatus.

[0004]

2. Description of the Related Art In recent years, as a next-generation recording medium, DV
D is attracting expectations.

In a DVD, the shortest pit length is 0.4
[Μm] and the track pitch is standardized to about 0.74 [μm], so that the same
B]. Therefore, in order to reproduce recorded data from such a DVD, a high resolution (that is, light-collecting ability) is required as an optical pickup.

In this case, the spot diameter of the optical spot formed by the optical pickup on the disk surface is proportional to λ / NA, where NA is the aperture ratio of the objective lens and λ is the wavelength of the laser beam.

Therefore, in the optical pickup for DVD, a semiconductor laser having a wavelength of 780 [nm] and an objective lens having an NA of 0.45 are used in the optical pickup for CD, whereas the wavelength is 635 [nm]. Alternatively, a semiconductor laser of 650 [nm] and an objective lens of NA 0.6 are used, and thus an optical spot having a diameter of about 0.9 [μm] is formed on the reflection surface of the DVD by the combination of the semiconductor laser and the objective lens. In addition, it is possible to reproduce recorded data from a DVD satisfactorily.

[0008]

By the way, in recent years, DV
Many companies are developing optical pickups compatible with D / CD.

However, the objective lens of the optical pickup is usually designed so that light can be condensed at one point only through a disk substrate having a predetermined refractive index and a predetermined thickness. If different from
As shown in FIGS. 14A and 14B, the light passing through the center of the objective lens 1 and the light passing through the periphery thereof are shifted from the light-collecting point due to the spherical aberration, so that the light does not converge at one point. There is a problem that the shifted light adversely affects the reproduced signal. For this reason, for example, DV
If you try to play a CD using the objective lens for D,
There was a problem that a good reproduction signal could not be obtained.

In order to solve such a problem, recently, FIG.
As shown in FIG. 5, it has been proposed to form an annular groove 2B on one side 2A of the objective lens 2 designed for DVD.

In practice, in the optical pickup using such an objective lens 2, it is of course necessary to read C when reading a DVD.
In the reproduction of D, light having a deviated condensing point (light passing through the peripheral portion of the objective lens), which adversely affects the reproduction signal, of the reflected light from the optical disk is shielded (scattered) by the groove 2B of the objective lens 2. Therefore, it is possible to obtain a good reproduction signal to some extent, and there is an advantage that an optical pickup can be easily constructed.

However, in the optical pickup using the objective lens 2 having such a configuration, it is not possible to completely shut out all of the light whose focal point has shifted during reproduction of a CD, and the focal point cannot be completely shut out. FIGS. 16A and 16B show the focus servo signal due to the influence of light.
There was a problem that the disturbance occurred as in the part surrounded by a circle. Note that FIG. 16A is based on a calculation result, and FIG. 16B is based on an experimental result.

Further, in the optical pickup using the objective lens 1 having such a configuration, it is necessary to form an annular groove having a predetermined diameter and a predetermined width at a predetermined position with respect to the objective lens itself. There was.

Therefore, if these problems can be solved, it is considered that a DVD / CD compatible optical pickup having a high focus accuracy and a simple structure which can be easily manufactured can be realized.

The present invention has been made in view of the above points, and an object of the present invention is to propose an optical pickup and a reproducing apparatus having a simple configuration capable of coping with a plurality of types of optical discs.

[0016]

According to the present invention, there is provided an optical pickup, comprising: a high-density optical disk for focusing a first laser beam on a reflection surface of the optical disk to be reproduced; A portion of the reflected light of the objective lens formed so as to correspond to the reflection surface of the optical disk of the first laser beam that passes through a region that is a predetermined distance in the radial direction of the objective lens from the center of the objective lens is shielded. And a light blocking means.

As a result, of the reflected light of the first laser beam on the optical disk on which information is recorded at a normal density,
A portion that adversely affects the reproduction signal and the focus error signal can be shielded by the light shielding unit. Therefore, the information can be detected not only from a high-density optical disk but also from an optical disk on which information is recorded at a normal density.

Further, in the present invention, in the reproducing apparatus, an objective lens formed corresponding to the high-density optical disk for focusing the first laser beam on the reflection surface of the optical disk to be reproduced, and An optical pickup having a light shielding means for shielding a portion of the reflected light of the one laser beam from the reflection surface of the optical disk that passes through a region that is at a predetermined distance from the center of the objective lens in a radial direction of the objective lens is provided. I made it.

As a result, of the reflected light of the first laser beam on the optical disk on which information is recorded at a normal density,
A portion that adversely affects the reproduction signal and the focus error signal can be shielded by the light shielding unit. Therefore, the information can be reproduced not only from a high-density optical disc but also from an optical disc on which information is recorded at a normal density.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment (1-1) Configuration of Reproducing Apparatus In FIG. 1, reference numeral 10 denotes a reproducing apparatus to which the present invention is applied as a whole so that recorded data can be reproduced from DVDs and CDs. It has been done.

That is, in the case of this reproducing apparatus, during operation, the rotation control system 12 is controlled under the control of the drive controller 11.
, The motor 13 is driven, and the optical disk 14 (DVD or CD) to be reproduced set in a predetermined state is rotated.

At the same time, the optical pickup 15 is driven to irradiate the optical disk 14 with the laser beam L1, and a light receiving signal S10, which is an electric signal based on the reflected light of the laser beam L1 on the optical disk 14, is received by the optical pickup 15. Which is generated in the signal processing system 1
6 is sent.

The signal processing system 16 demodulates the data detected based on the supplied light receiving signal S10, and converts the obtained reproduction signal S11 via a drive controller 11 to a speaker (not shown) and an external output terminal (not shown). (Not shown)
On the other hand, a servo signal S12 such as a focus error signal and a tracking error signal is generated based on the light receiving signal S10, and is transmitted to the pickup control system 17.

The pickup control system 17 controls the focus and tracking of the optical pickup 15 based on the supplied servo signal S12.
Is generated and transmitted to a corresponding driving mechanism (for example, a tracking coil or a focusing coil) in the optical pickup 15 to control the tracking and the focus of the optical pickup 15.

The drive controller 11 can control the drive of the coarse motor 19 through the coarse motor control system 18. Thus, if necessary, the optical pickup 15 can be moved in the radial direction of the optical disk 14 to be reproduced. It can be moved to.

(1-2) Configuration of Optical Pickup According to First Embodiment In the case of this reproducing apparatus 10, the optical pickup 15 is configured as shown in FIG.

In this case, in this optical pickup 15, D
In the VD reproduction mode, the laser beam L1 having a wavelength of 635 [nm] emitted from the laser diode 20 is diffracted by the grating 21 and the obtained laser beam L1
The first-order diffracted light L1A and the ± 1st-order diffracted lights L1B and L1C are respectively transmitted through a beam splitter 22 to a collimator lens 2.
3

The 0th-order diffracted light L1A and ± 1st-order diffracted light L1 of the laser beam L1 incident on the collimator lens 23
B and L1C are converted into parallel light by the collimator lens 23,
As shown in FIG. 3, light is condensed on the reflecting surface of the track TR in a state of being inclined with respect to the track TR.

The 0th-order diffracted light L1A and ± 1st-order diffracted lights L1B and L1C of the laser beam L1 are DVD
The first light reflected on the reflecting surface of 14A and thus obtained
To the third reflected light L2A to L2C are incident on the multi-lens 25 via the objective lens 24, the collimator lens 23 and the beam splitter 22 sequentially.

Further, the first to third reflected lights L2A to L2A
After the astigmatism is given by the multi-lens 25, the L2C is divided into four main light receiving portions 26A or the first or second sub light receiving portions 26B of the photodetector 26 having the light receiving surface as shown in FIG. 26C respectively.

Thus, in the optical pickup 15, in the DVD reproducing mode, data recorded on the DVD 14A can be reproduced based on the light receiving signal S10A (FIG. 1) output from the main light receiving section 26A of the photodetector 26. Based on the light receiving signal S10A, tracking control by the heterodyne method and focus control by the astigmatism method can be performed.

On the other hand, in the optical pickup 15, the 0th-order diffracted light L1A and the ± 1st-order diffracted lights L1B and L1C of the laser beam L1 emitted from the laser diode 20 are used as the objectives in the CD reproduction mode and the DVD reproduction mode, respectively. The light enters the lens 24.

At this time, the objective lens 24 has been moved to a position separated from the CD 14B by a predetermined distance according to the CD reproduction mode by a drive mechanism (not shown), and the 0th-order diffracted light L1A and ± 1st-order diffracted light of the incident laser beam L1. L1
B and L1C are condensed while being obliquely inclined with respect to the track TR as described above with reference to FIG.

The zero-order diffracted light L1 of the laser beam L1
A, the ± 1st-order diffracted lights L1B and L1C are reflected on the reflecting surface of the CD 14B, and the first to third reflected lights L2A to L2C thus obtained are incident on the objective lens 24.

At this time, as shown in FIG. 4, the lens holder 30 holding the objective lens 24 has an annular light-shielding portion so as to shield a part of the objective lens 24 on one side 24A facing the DVD 14A or CD 14B. 30A, the portion of the first reflected light L2A incident on the objective lens 24 that most adversely affects the reproduced signal (corresponding to the received light signal S10A) is the lens holder 30.
The light is shielded by the light shielding unit 30A.

The light shielding portion 30 of the lens holder 30
A, the remaining first to third reflected light L not blocked by A
2A to 2C sequentially enter the multi-lens 25 via the collimator lens 23 and the beam splitter 22, and after the astigmatism is given by the multi-lens 25, the main light receiving section 26A of the photodetector 26 or the first or second , Respectively.

As a result, in the optical pickup 15, the CD1 is output based on the light receiving signal S10A (FIG. 1) output from the main light receiving section 26A of the photodetector 26.
The reproduction of the data recorded on the 4B and the focus control by the astigmatism method can be performed.
The tracking control by the three beam method can be performed based on the light receiving signals S10B and S10C (FIG. 1) output from the first and second sub light receiving units 26B and 26C.

In addition to the above configuration, the optical pickup 15
In the case of, the light-shielding portion 30A of the lens holder 30 has an inner diameter r _{IN1 of} about 0.55 to 0.65, where the radius r of the objective lens 24 is 1.
Is selected, and the width W ₁ is equal to the radius r of the objective lens 24.
About 0.05 to 0.15.

Thus, in the optical pickup 15, in the CD reproduction mode, when the 0th-order diffracted light L1A of the laser beam L1 reflected on the reflection surface of the CD 14B (that is, the first reflected light L2A) passes through the objective lens 24, A portion of the first reflected light L2A that greatly affects the focus error signal can be shielded by the light shielding portion 30A of the lens holder 30.

In practice, the light shielding portion 30A of the lens holder 30
By changing the inner diameter r _IN1 and width W ₁ of, when it tries to calculate the value of Jitsuta occurring Fuo scum error signal in case of reproducing the CD14B with a laser beam L1 having a wavelength 635 [nm], 6 and An operation result as shown in FIG. 7 was obtained. Accordance connexion As is clear from FIGS. 6 and 7, it can be most reduced Jitsuta of Yotsute Fuo Kas error signal to select the inner diameter r _IN1 and width W ₁ of the lens holder 30 as described above Was confirmed.

Further, in the case of the optical pickup 15, the size of the main light receiving portion 26A of the photodetector 26 is
In the DVD reproduction mode, the laser beam L1 reflected by the reflection surface of the DVD 14A and transmitted through the objective lens 24 has a zero value.
Almost all of the second-order diffracted light L1A (that is, the first reflected light L2A) can be received, and the 0th-order diffracted light L1A of the laser beam L1 is reflected on the reflection surface of the CD 14B in the CD reproduction mode. , Objective lens 2
The size of the lens holder 30 is set to such a size that it can receive only a portion that is transmitted inside the region shielded by the light shielding portion 30A of the lens holder 30.

As a result, in this optical pickup 15,
When the main light receiving portion 26A of the photodetector 26 has a portion (ie, the objective lens 24) of the first reflected light L2A that adversely affects the focus error signal in the CD reproduction mode.
(The portion passing outside the region shielded by the light shielding portion 30A of the lens holder 30) can be prevented from being received beforehand.

(1-3) Operation and Effect of First Embodiment In the above configuration, the reproducing apparatus 10 according to the present embodiment
In the optical pickup 15 of FIG.
In the D reproduction mode, the laser beam L1 emitted from the laser diode 20 is diffracted by the grating 21, and the zero-order diffracted light L of the laser beam L1 thus obtained is obtained.
The 1A and ± 1st-order diffracted lights L1B and L1C are incident on the reflection surface of the DVD 14A or CD 14B via the beam splitter 22, the collimator lens 23 and the objective lens 24 in order.

The 0th-order diffracted light L1A and ± 1st-order diffracted lights L1B and L1C of the laser beam L1 are
A or 1 to 1 reflected on the reflection surface of A or CD14B
The third reflected lights L2A to L2C are sequentially passed through the objective lens 24, the collimator lens 23, the beam splitter 22, and the multi-lens 25 to the main light receiving section 26A or the first or second sub light receiving section 26B, 26 of the photodetector 26.
Light is received by C.

In this case, in the optical pickup 15, the objective lens 24 is designed for DVD, and accordingly,
In the D reproduction mode, all of the 0th-order diffracted light L1A of the laser beam L1 passing through the objective lens 24 is condensed on one point on the reflection surface of the DVD 14A. In the first reflected light L2A, there is no portion where the focus point is shifted which adversely affects the focus servo signal.

Accordingly, in the optical pickup 15, although the amount of the first reflected light L2A passing through the objective lens 24 and entering the main light receiving portion 26A of the photodetector 26 is reduced by the light shielding portion 30A of the lens holder 30, the lens holder A good focus servo signal can be obtained without being affected by the light shielding portion 30A.

On the other hand, in the optical pickup 15, C
In the D reproduction mode, the 0th-order diffracted light L1A of the laser beam L1
Of these, the portion passing through the peripheral portion of the objective lens 24 shifts the light condensing point and condenses near the reflection surface of the CD 14B, so that the first-order diffraction light L1A is reflected on the reflection surface of the CD 14B. The light L2A has a portion that adversely affects the reproduction signal and the focus servo signal.

However, in the optical pickup 15, a main portion of the first reflected light L2A which adversely affects the reproduction signal and the focus error signal is shielded by the light shielding portion 30A of the lens holder 30, and the main detector 26 Since the size of the light receiving portion 26A is selected so as not to receive a portion of the first reflected light L2A which adversely affects the focus error signal in the CD reproduction mode, the light receiving portion 26A is also excellent in CD reproduction. A focus error signal can be obtained.

Further, in the case of the optical pickup 15, as described above, the light-shielding portion for shielding the main portion of the first reflected light L2A which has a bad influence on the reproduction signal and the focus error signal in the CD reproduction mode is provided. Lens holder 30
Thus, the light-shielding portion can be formed much more easily than, for example, a case where a light-shielding portion is provided by forming a groove in the objective lens 24.

According to the above configuration, the annular light-shielding portion 30A that covers a predetermined area on one side of the objective lens 24 is provided in the lens holder 30 of the DVD optical system, so that the first reflected light L2A The portion that adversely affects the reproduction signal and the focus error signal during CD reproduction can be shielded from light, and thus a DVD / CD compatible reproduction apparatus and optical pickup having a simple configuration can be realized.

(2) Second Embodiment FIG. 8 in which parts corresponding to those in FIG.
An optical pickup 40 according to a second embodiment applied to the reproducing apparatus 10 of the first embodiment is shown, and has the same configuration as the optical pickup 15 of the first embodiment except for the shape of a lens holder 41.

That is, in the case of the optical pickup 40,
As shown in FIG. 9, the lens holder 41 is provided with a pair of parallel light shielding portions 41A and 41B.

In this case, the light shielding portions 41A and 41B
Of the one surface 24A of the objective lens 24, the objective lens 2
Assuming that the radius r of 4 is 1 and is 0.
55 to 0.65 only it is formed positioned to cover the region away portion selection, also its width W ₂ are selected, each 0.5 about 1.5.

Thus, in the optical pickup 40, at the time of reproducing a CD, the 0th-order diffracted light L of the laser beam L1 is reproduced.
A part of the first reflected light L2 reflected by the reflection surface of the CD 14B, which has the most adverse effect on the reproduction signal and the focus error signal, is shielded near the center of the light shielding part 41 of the lens holder 41. Thus, the disturbance of the focus error signal can be reduced.

According to the above configuration, the lens holder 41 of the DVD optical system is provided with the pair of parallel light-shielding portions 41A and 41B that cover a predetermined position on the one surface 24A of the objective lens 24. Of the reflected light L2A of
Part of the range that adversely affects the reproduction signal and the focus error signal during D reproduction can be shielded, and thus a DVD / CD compatible reproduction apparatus and optical pickup having a simple configuration can be realized.

(3) Third Embodiment (3-1) Configuration of Optical Pickup According to Third Embodiment FIG. 10 in which parts corresponding to those in FIG. 12 shows an optical pickup 50 according to a third embodiment applied to DVDs, CDs, and CDs.
Recorded data can be reproduced from a DR (Compact Disc Recordable).

That is, in the case of this optical pickup 50,
A first laser diode 51 that emits a first laser beam L10 having a wavelength of 635 [nm], and a second laser diode 51 having a wavelength of 780 [nm].
And a second laser diode 52 that emits the laser beam L11.

In the DVD playback mode, the first laser diode 51 is driven, and the first laser beam L10 emitted from the first laser diode 51 is incident on the beam splitter 53.

At this time, the beam splitter 53
A laser beam having a wavelength of 635 [nm] is split into a predetermined branching ratio (eg,
50:50), the first laser beam L10 reflected by the beam splitter 53 is used as a reproduction target through the collimator lens 23 and the objective lens 24 in order. DVD14A
Incident on the reflection surface.

The D of the first laser beam L10
The first reflected light L12, which is light reflected on the reflection surface of the VD 14A, is incident on the half mirror 54 via the objective lens 24, the collimator lens 23, and the beam splitter 53 sequentially, and the half mirror 54 gives astigmatism. After that, the main light receiving section 26A of the photodetector 26 is
(FIG. 4).

Thus, in the optical pickup 50, in the DVD reproduction mode, the reproduction of the data recorded on the DVD 14A based on the light receiving signal S10A (FIG. 1) output from the main light receiving section 26A of the photodetector 26 and the heterodyne method. And tracking control by the astigmatism method.

On the other hand, in the optical pickup 50, the second laser diode 52 is driven in the CD reproduction mode and the CD-R reproduction mode. The second laser beam L1 emitted from the second laser diode 52
1 is incident on the grating 55, and the 0th-order diffracted light L11A and ± of the second laser beam L11 thus obtained are
The first-order diffracted lights L11B and L11C are incident on the reflection surface of the CD 14B or CD-R 14C to be reproduced via the half mirror 54, the beam splitter 53, the collimator lens 23, and the objective lens 24, respectively.

The 0th-order diffracted light L11A and ± 1st-order diffracted lights L11B and L11 of these second laser beams L11
C is reflected on the reflecting surface of CD14B or CD-R14C, and the thus obtained second to fourth reflected lights L13A to L13A.
L13C enters the objective lens 24, respectively.

At this time, as shown in FIG. 11, the objective lens 24 is held in the lens holder 56 for holding the objective lens 24.
An annular light-shielding portion 56A is provided so as to shield a partial area of the one surface 24A facing the DVD 14A, CD 14B or CD-R 14C from the first reflected light L13A incident on the objective lens 24. The part that has the most adverse effect on the signal is the light shielding part 5 of the lens holder 56.
The light can be shielded by 6A.

The light shielding portion 56 of the lens holder 56
A, the remaining first to third reflected light L not blocked by A
13A to 13C enter the half mirror 54 via the collimator lens 23 and the beam splitter 53 in order,
After astigmatism is given by the half mirror 54, the main light receiving portion 26A (FIG. 4) of the photodetector 26 or the first or second sub light receiving portion 26B, 26C
Respectively.

Thus, in the optical pickup 50, in the CD reproduction mode and the CD-R reproduction mode, the CD 14B or the CD-R 14C based on the light receiving signal S10A (FIG. 1) output from the main light receiving section 26A of the photodetector 26. Of the data recorded in the photodetector and focus control by the astigmatism method, while the first and second sub-light receiving units 26B and 26C of the photodetector 26 can be used.
The tracking control by the three-beam method can be performed based on the light receiving signals S10B and S10C (FIG. 1) output from.

In addition to the above configuration, the optical pickup 50
In this case, the light-shielding portion 56A of the lens holder 56 has an inner diameter r _{IN3 of} about 0.55 to 0.65, where the radius r of the objective lens 24 is 1.
Is selected, and the width W ₃ is equal to the radius r of the objective lens 24.
Is selected to be about 0.1 to 0.2.

As a result, in the optical pickup 50, in the CD reproduction mode and the CD-R reproduction mode,
When the 0th-order diffracted light L11A (that is, the second reflected light L13A) of the second laser beam L11 reflected on the reflection surface of the D14B or the CD-R14C passes through the objective lens 24, the focus of the second reflected light L13A The portion that greatly affects the error signal can be shielded from light by the light shielding portion 56A of the lens holder 56.

In practice, the light shielding portion 56A of the lens holder 56
The values of jitter generated in the focus error signal when a CD was reproduced using a laser beam having a wavelength of 780 [nm] were calculated by changing the inner diameter r _IN3 and the width W ₃ of FIG. An operation result as shown in FIG. 13 was obtained. Therefore, as is clear from FIGS. 12 and 13, the jitter of the focus error signal can be reduced most by selecting the inner diameter r _IN3 and the width W ₃ of the lens holder 56 as described above. Was confirmed.

(3-2) Operation and Effect of Third Embodiment In the above configuration, in the optical pickup 50 according to the present embodiment, the wavelength 635 emitted from the first laser diode 51 in the DVD reproduction mode is used. nm] through the beam splitter 53, the collimator lens 23, and the objective lens 24 in that order.
4A, while the first laser beam L10 is reflected on the reflection surface of the DVD 14A, the first reflection light L12 is reflected by the objective lens 24, the collimator lens 23, the beam splitter 53, and the half mirror 54. The light is sequentially received by the main light receiving section 26A of the photodetector 26.

On the other hand, in the optical pickup 50, in the CD reproducing mode and the CD-R reproducing mode, the second laser beam L11 having a wavelength of 780 [nm] emitted from the second laser diode 52 is diffracted by the grating 55. 0th order diffracted light L11A, ± 1st order diffracted light L11
B and L11C are respectively a half mirror 54, a beam splitter 53, a collimator lens 23, and an objective lens 24.
Sequentially enter the reflection surface of the CD 14B or CD-R.

Then, the second laser beam L11
The second to fourth reflected lights L13A to L13C, which are the reflected lights of the ± 1st-order diffracted lights L11A, ± 11th-order diffracted lights L11B and L11C on the reflection surface of CD14B or CD-R, are converted into an objective lens 2
4. The light is received by the main light receiving portion 26A or the first or second sub light receiving portion 26B, 26C of the photodiode 26 via the collimator lens 23, the beam splitter 53, and the half mirror 54 sequentially.

In this case, in the optical pickup 50, as in the first embodiment, the objective lens 24 is designed in an optimal state for a DVD, so that the influence of the light shielding portion 56A (FIG. 11) of the lens holder 56 is obtained. A good focus servo signal can be obtained with almost no reception.

In the optical pickup 50, in the CD reproduction mode and the CD-R reproduction mode, the main part of the 0th-order diffracted light L11A of the second laser beam L11 which adversely affects the focus servo signal is a lens holder. 5
6, the size of the main light receiving portion 26A of the photodetector 26 adversely affects the reproduction signal and the focus error signal of the second reflected light L13A in the CD reproduction mode and the CD-R reproduction mode. Therefore, a good focus error signal can be obtained even during CD reproduction and CD-R reproduction.

Further, in the case of the optical pickup 50, as described above, there is a major adverse effect on the reproduction signal and the focus error signal of the second reflected light L13A in the CD reproduction mode and the CD-R reproduction mode. Since the light-shielding portion 56A that shields a portion is provided in the lens holder 56, the light-shielding portion can be formed much more easily than a case where the light-shielding portion is provided by forming a groove in the objective lens 24, for example. it can.

According to the above configuration, the first laser diode 51 for emitting the first laser beam L10 having a wavelength of 635 [nm] and the second laser beam L1 having a wavelength of 780 [nm] are used.
1, a lens holder 5 having a second laser diode 52 for emitting light, a DVD objective lens 24, and an annular light-shielding portion 56A covering a predetermined area on one surface of the objective lens 24.
In the DVD reproduction mode, the first laser diode 51 is driven to reproduce the recorded data from the DVD 14A, while in the CD reproduction mode and CD-R reproduction, the second laser diode 52 is driven to drive the CD 14B or By reproducing data from the CD-R 14C, data can be reproduced from the DVD 14A, the CD 14B and the CD-R 14C, and the data can be reproduced from the CD 14B and the CD-R.
At the time of reproduction of 14C, a portion of the second reflected light L13A that has the least adverse effect on the reproduction signal and the focus error signal can be shielded, and thus the D of the simple configuration
A VD, CD, and CD-R compatible playback device and optical pickup can be realized.

(4) Other Embodiments In the first embodiment, the lens holder 3
The case where the inner diameter r _IN1 of the light shielding part 30A of 0 is selected to be about 0.55 to 0.65 with the radius r of the objective lens 24 being _1, and the width W1 of the light shielding part 30A is selected to be about 0.05 to 0.15 However, the present invention is not limited to this, and the inner diameter r _IN1 and the width W ₁ of the light-shielding portion 30A of the lens holder 30 are not limited _thereto.
May be selected in addition to this. However, by doing so, the light shielding portion 30A of the lens holder 30 is formed.
It is considered that the light-shielding effect due to is slightly deteriorated.

In the above-described second embodiment,
A pair of linear light shielding portions 41A and 41 are provided on the lens holder 41.
Although the case where B is provided in parallel has been described, the present invention is not limited to this, and the light shielding portions 41A and 41B may be formed in shapes other than linear, or the width of the light shielding portions 41A and 41B may be partially changed. The light-shielding portions 41A and 41B may be provided without being parallel, or one or three or more light-shielding portions may be provided.
If the portion of the reflected light L2A on the reflection surface of the CD 14B of 1A that can pass through a predetermined area that is separated from the center of the objective lens 24 by a predetermined distance in the radial direction of the objective lens 24 can be shielded, the lens holder 41 Various other shapes and forms can be applied to the shapes and forms of the light-shielding portions 41A and 41B formed in the above.

Similarly, in the third embodiment described above,
Although the case where the light shielding portion 56A of the lens holder 56 is formed in an annular shape has been described, the present invention is not limited to this.
In short, in the CD reproduction mode and the CD-R reproduction mode, the objective lens 24 of the reflected light L13A of the laser beam L11A on the reflection surface of the CD14B or CD-R14C.
The shape and form of the light-shielding portion formed on the lens holder 56 can be various other shapes as long as it can shield a portion that transmits through a predetermined region that is a predetermined distance away from the center of the objective lens 24 in the radial direction. Shapes and forms can be applied.

Further, in the above-described second embodiment,
The light-shielding portions 41A and 41B of the lens holder 41 are set at 0.55 to 0.65 from the center of the objective lens 24 with the radius r of the objective lens 24 being 1 on one surface 24A of the objective lens 24.
And forming by selecting the position to cover the distant area portion only, it has dealt with the case of selecting the width W ₂ each 0.5 about 1.5, the present invention is not limited to this, the objective lens formed by selecting the position to cover the region portion of 0.55 to 0.65 than the center of 24, or may be selected width W ₂ to each non 0.5-1.5.

Further, in the third embodiment described above,
The light-shielding portion 56A of the lens holder 56 is selected to have an inner diameter r _IN3 of about 0.55 to 0.65, where the radius r of the objective lens 24 is 1, and the width W ₃ is set to 0.
Although the case of selecting about 1 to 0.2 has been described, the present invention is not limited to this, and the inner diameter r _IN3 and the width W ₃ of the light shielding portion 56A of the lens holder 56 may be selected other than this. . However, it is conceivable that the light-shielding effect of the light-shielding portion 56A of the lens holder 56 is somewhat deteriorated by doing so.

Further, in the first and second embodiments described above, the present invention relates to an optical pickup 1 compatible with DVD / CD.
In the third embodiment, the present invention is applied to the DVD, CD and CD-R compatible optical pickup 50 and the reproducing apparatus 1. The present invention is not limited to this, and the point is that an optical pickup and a reproducing apparatus for detecting or reproducing information from a high-density optical disk and an optical disk on which information is recorded at a lower density than the high-density optical disk. Can be widely applied.

Further, in the above-described first to third embodiments, in the CD reproduction mode (and the CD-R reproduction mode), the reflection of the laser beams L1A and L11A on the reflection surface of the CD14B (or CD-R14C). Light L2A, L
13A, the light-shielding means that shields a portion that passes through a predetermined area that is separated from the center of the objective lens 24 by a predetermined distance in the radial direction of the objective lens 24 is used as the lens holders 30, 41, and 56.
(Light shielding portions 30A, 41A, 41B, 56A) has been described, but the present invention is not limited to this, and may be provided separately from the lens holder that holds the objective lens 24.

Further, in the above-described second embodiment, a light-shielding portion for shielding a portion of the 0-order diffracted light L2A of the laser beam L1 reflected on the reflection surface of the CD 14B, which adversely affects the focus error signal, is provided by the lens holder. However, the present invention is not limited to this, and a band-shaped groove as shown in FIG.
4 may be formed.

Further, in the first to third embodiments, the zero-order diffracted light L2 of the laser beams L1 and L11A reflected on the reflection surface of the CD 14B or CD-R 14C is used.
A and L13A have been described in which the light-shielding portion that shields a portion that adversely affects the reproduction signal and the focus error signal is provided on one side 24A of the objective lens 24 facing the DVD 14A or the like. The invention is not limited to this, and the light-shielding portion may be provided on the surface of the objective lens 24 on the side not facing the DVD 14A or the like.

[0087]

As described above, according to the present invention, in an optical pickup, a first laser beam is formed corresponding to a high-density optical disk which is focused on a reflection surface of the optical disk to be reproduced. And a light shielding means for shielding a portion of the reflected light of the first laser beam from the reflecting surface of the optical disk that passes through a region that is separated from the center of the objective lens by a predetermined distance in the radial direction of the objective lens. By providing the optical disk, the information can be detected not only from the high-density optical disk but also from the optical disk on which the information is recorded at the normal density, and thus a simple configuration capable of coping with a plurality of types of optical disks. Optical pickup can be realized.

Further, according to the present invention, in the reproducing apparatus,
An objective lens formed so as to correspond to a high-density optical disk for converging a first laser beam on the reflection surface of the optical disk to be reproduced, and reflected light of the first laser beam on the reflection surface of the optical disk Of these, an optical pickup having a light-shielding means for shielding a portion transmitting a predetermined distance in the radial direction of the objective lens from the center of the objective lens is provided, so that not only a high-density optical disk, The information can also be detected from an optical disk on which information is recorded at a normal density, and thus a reproducing apparatus having a simple configuration capable of dealing with a plurality of types of optical disks can be realized.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram illustrating a configuration of an optical pickup according to a first embodiment.

FIG. 3 shows a laser beam 0 on a reflection surface of an optical disk;
FIG. 4 is a schematic diagram illustrating a positional relationship between light spots of the first-order diffracted light and ± first-order diffracted light.

FIG. 4 is a schematic diagram illustrating a configuration of a photodiode.

5A and 5B are a side view and a top view illustrating a configuration of the lens holder according to the first embodiment.

FIG. 6 is a schematic diagram illustrating a relationship between an inner diameter of a light shielding unit and jitter generated in a focus error signal.

FIG. 7 is a schematic diagram illustrating a relationship between a light shielding portion width and a jitter generated in a focus error signal.

FIG. 8 is a schematic diagram illustrating a configuration of an optical pickup according to a second embodiment.

FIG. 9 is a side view and a top view showing a configuration of a lens holder in a second embodiment.

FIG. 10 is a schematic diagram illustrating a configuration of an optical pickup according to a third embodiment.

FIGS. 11A and 11B are a side view and a top view illustrating a configuration of a lens holder according to a third embodiment.

FIG. 12 is a schematic diagram illustrating a relationship between an inner diameter of a light shielding unit and jitter generated in a focus error signal.

FIG. 13 is a schematic diagram illustrating a relationship between a light-shielding portion width and jitter generated in a focus error signal.

FIG. 14 is a side view for explaining a difference in light-collecting state due to a difference in disk thickness.

FIG. 15 is a side view and a top view showing a conventional DVD / CD compatible objective lens.

FIG. 16 is a characteristic curve diagram for explaining the disturbance generated in the focus servo signal in the optical pickup using the objective lens of FIG.

[Explanation of symbols]

1 ... reproducing device, 14A ... DVD, 14B ... CD,
14C ... CD-R, 15, 41, 50 ... Optical pickup, 20, 51, 52 ... Laser diode, 24 ...
... Objective lens, 26 ... Photodetector, 26A ...
Main light receiving section, 30, 41, 56 ... lens holder, 3
0A, 41A, 41B, 56A...

Claims (10)

[Claims] An optical disk for irradiating a laser beam on an optical disk and detecting information recorded on the optical disk based on the reflected light of the laser beam on a reflection surface of the optical disk. A first light source for emitting the first laser beam having a wavelength corresponding to the first light source, and condensing the first laser beam emitted from the first light source on a reflection surface of the optical disk to be reproduced; An objective lens formed corresponding to the high-density optical disk; and a predetermined distance in the radial direction of the objective lens from a center of the objective lens, of the reflected light of the first laser beam on the optical disk. An optical pickup, comprising: a light-shielding unit that shields a portion that transmits a region. 2. The optical pickup according to claim 1, wherein said light shielding means is provided on a lens holder for holding said objective lens. 3. A light receiving means for receiving the reflected light of the first laser beam on the optical disk and outputting an electric signal based on the received reflected light, wherein the light receiving means receives the reflected light. A light receiving unit that can receive substantially all of the reflected light of the first laser beam on the high-density optical disk, and the information on the optical disk on which the information is recorded at a lower density than the high-density optical disk. The reflected light of the first laser beam is formed to have such a size that it can receive only a portion of the reflected light that has passed through the inside of the region that is separated from the center of the objective lens by a predetermined distance in the radial direction of the objective lens. The optical pickup according to claim 1, wherein: 4. The light-shielding means has a band-like shape that shields a part of the reflected light that passes through the area at a predetermined distance from the center of the objective lens in the radial direction of the objective lens. 2. An optical pickup according to claim 1, wherein: 5. A second laser beam having a wavelength lower than that of the high-density optical disc and having a wavelength corresponding to the optical disc on which the information has been recorded, irradiating the optical disc via the objective lens. 2. The optical pickup according to claim 1, further comprising a light source. 6. An optical disk is irradiated with a first laser beam of a predetermined wavelength, and information recorded on the optical disk is reproduced based on the reflected light of the first laser beam on the reflecting surface of the optical disk. In a reproducing apparatus, a first light source that emits a first laser beam having a wavelength corresponding to a high-density optical disc, and the first laser beam emitted from the first light source are used for reproducing the optical disc to be reproduced. An objective lens formed corresponding to the high-density optical disk condensed on a reflecting surface; and, of the reflected light of the first laser beam on the optical disk, an objective lens of the objective lens from a center of the objective lens. A reproducing apparatus comprising: an optical pickup having light-shielding means for shielding a portion that transmits a region that is separated by a predetermined distance in a radial direction. 7. A reproducing apparatus according to claim 6, wherein said light shielding means of said optical pickup is provided on a lens holder for holding said objective lens. 8. The optical pickup includes light receiving means for receiving the reflected light of the first laser beam on the optical disk and outputting an electric signal based on the received reflected light, wherein the light receiving means comprises: The light receiving unit for receiving the reflected light can receive substantially all of the reflected light of the first laser beam on the high-density optical disk, and the information is recorded at a lower density than the high-density optical disk. The reflected light of the first laser beam on the optical disk is large enough to receive only a portion that has passed through the inside of the area at a predetermined distance in the radial direction of the objective lens from the center of the objective lens. The reproducing apparatus according to claim 6, wherein the reproducing apparatus is formed. 9. The light-blocking means of the optical pickup has a band-like shape for shielding a part of the reflected light transmitted through the area at a predetermined distance in the radial direction of the objective lens from the center of the objective lens. 7. The reproducing apparatus according to claim 6, wherein: 10. An optical pickup, comprising: a second laser beam having a wavelength corresponding to the optical disk on which the information is recorded at a density lower than that of the high-density optical disk; 7. The reproducing apparatus according to claim 6, further comprising a second light source for irradiating.