CN1831974A - Optical pick-up apparatus and optical disk apparatus incorporating the optical pick-up apparatus - Google Patents

Abstract

An exemplary optical pickup device of the present invention includes: a first light source for emitting a light beam of a first wavelength; a second light source for emitting a light beam of a second wavelength, the second wavelength being greater than the first wavelength; a third light source, For emitting a light beam of a third wavelength, the third wavelength is greater than the second wavelength; the first dichroic element is used for transmitting the light beam of the first wavelength and reflecting the light beam of the second wavelength; the second dichroic element is used for Reflecting the light beams of the first and second wavelengths and transmitting the light beams of the third wavelength; A light beam of three wavelengths and having been transmitted through a second wavelength, and used to project the beam onto the disk.

Description

Optical pickup device and optical disc device having such optical pickup device

This application is based on and claims priority from Japanese Patent Application 2004-381932 filed on December 28, 2004 and Japanese Patent Application 2005-256817 filed on September 5, 2005, the entire contents of which are incorporated by reference here.

technical field

The present invention relates to an optical pickup device including an optical system compatible with CD, DVD, and HD-DVD simultaneously, and an optical disc device having such an optical pickup device.

Background technique

For example, Non-Patent Document 1 - "Pick-up arrangement (pickup device)" by Kiyono Ikenaka (Microoptics Study Group Journal (Microoptics Study Group Journal) Vol. 22 No. 3 No. 25-29, September 2004 Published) in Chapter 5 describes an optical device compatible with HD-DVD, DVD, CD at the same time.

According to the optical pickup device described in this reference, the polarizing beam splitter or half mirror for splitting the light beam in the optical transmission/receiving system is arranged just after the DVD LD (laser diode) and comes from the polarizing beam splitter or half mirror The beam from the HD-DVD LD is combined with the beam from the HD-DVD LD. Also, the light beam from the HD-DVD LD is not reflected and focused on a disc.

However, according to the optical pickup device described in this reference, the polarizing beam splitter or the half mirror for splitting the light beam in the light transmission/receiving system is provided and when the half mirror is used, the efficiency of the optical system will be reduced. reduce. For polarizing optical systems employing polarizing beam splitters, the optical combining means for combining one beam with the beam from the DVD LD adds to the complexity in the specification of polarization and wavelength and is therefore considered to be a de facto problem for practice. impossible. Also, in the above structure, the entire optical system is long and cannot be accommodated in a compact optical pickup device.

Contents of the invention

As described above, there is a problem that conventional optical pickups compatible with HD-DVD, DVD, and CD increase the complexity of optical element specifications and cannot be accommodated in compact optical pickups.

The present invention is made in consideration of the problems existing in the above-mentioned conventional optical pickup devices compatible with HD-DVD, DVD, and CD at the same time, and the object of the present invention is to provide a high-performance optical component that does not increase the complexity of the specifications. And an optical pickup device capable of being accommodated in a compact optical pickup device, and an optical disc device having such an optical pickup device are provided.

According to one aspect of the present invention, an optical pickup device is provided, which includes: a first light source for emitting a light beam of a first wavelength; a second light source for emitting a light beam of a second wavelength, and the second wavelength is greater than The first wavelength; the third light source, used to emit a beam of a third wavelength, the third wavelength is greater than the second wavelength; the first dichroic element, used to transmit the beam of the first wavelength and reflect the beam of the second wavelength; A second dichroic element for reflecting light beams of the first and second wavelengths and transmitting a light beam of a third wavelength; The light beam of the dichroic element and the light beam having the third wavelength and having been transmitted through the second wavelength are used to project the light beam onto the disc.

According to an example of the present invention, it is possible to provide an optical pickup device which never increases the complexity of the specifications of high-performance optical elements and which can be accommodated in a complicated and compact optical pickup device, and also provides an optical pickup device having such an optical pickup device. Pick up the optical disc unit of the unit.

Description of drawings

Fig. 1 shows the exemplary construction of an embodiment of the optical pick-up device according to the present invention;

2 is an explanatory diagram showing how a light beam is incident on and reflected by a second dichroic element of an embodiment of the present invention;

Fig. 3 is an explanatory view showing how a light beam is incident on and reflected by the first dichroic element of the embodiment of the present invention.

Detailed ways

Embodiments of the present invention will be explained below with reference to the drawings. FIG. 1 is an exemplary configuration of one embodiment of an optical pickup device according to the present invention. The optical disc device is provided with an optical pickup for focusing laser beams from laser diodes 11a, 11b, 11c on the surface of a disc 15 as a recording medium to record and reproduce information. The optical pick-up device includes: laser diodes 11a, 11b, 11c as light sources, which emit light beams of three different wavelengths; a dichroic film reflecting the beam from the laser diode 11b; a polarizing beam splitter 13 for transmitting the beam leaving the first dichroic element 12; and a second dichroic element 14, such as a dichroic mirror, which includes A dichroic film that passes the beam of the polarizing beam splitter 13 and transmits the beam from the laser diode 11c. A dielectric stack of dichroic films is used as a dichroic film.

The optical pick-up device also includes: a launching mirror (launching mirror) 16, which is used to reflect the light beam reflected by the second dichroic element 14 and passing therethrough to the disc 15 and reflect the light beam reflected by the disc 15 to the second dichroic element again. element 14; and a first optical detector 17a for receiving the reflection from the polarizing beam splitter 13 after the light beam from the disc 15 is reflected by the transmitting mirror 16, reaches the second dichroic element 14 and is reflected by the second dichroic element 14 Beam. The optical pick-up device also includes: a combined lens 18b between the laser diode 11b and the first dichroic element 12; A combination lens 18c; a collimating lens 20 between the second dichroic element 14 and the emitting mirror 16; and an optical element 21 and an objective lens 22 between the emitting mirror 16 and the disc 15, wherein the optical element 21 includes a polarizing Elements such as 1/4 wave plates or polarization holograms, as well as wavelength selective and numerical aperture limiting elements.

In an optical pickup capable of detecting beams of three wavelengths for HD-DVD/DVD/CD read/write operations (i.e. compatible with HD-DVD, DVD, CD simultaneously), three laser diodes 11a, 11b, 11c The emitted light beam must be directed to an objective lens 22 . In this case, it is required to keep the amount of wavefront aberration intentionally low and the utilization efficiency of the light beam intentionally high. Also, in the slim type optical pickup, it is required to reduce the size of the entire optical system as much as possible. In this embodiment of the invention, these requirements are met as follows. This embodiment will be explained with reference to FIG. 1 showing the configuration of an elongated type optical pickup device.

A laser diode 11a as a first light source emits a light beam in a wavelength range of 405 nm for HD-DVD. The beam emitted by this laser diode is transmitted through the first dichroic element 12 and the polarizing beam splitter 13 .

Generally, when an optical element made of glass is used, the amount of wavefront aberration is reduced in the case of a light beam transmitted through a glass optical element compared to the case of a light beam reflected from a glass optical element and thus the optical system allows the light beam Transmitted through the first dichroic element 12 and the polarizing beam splitter 13 is used to extract from the three optical systems (ie HD-DVD, DVD, CD optical systems) for the requirement of keeping the wavefront aberration very low Selected HD-DVD optical system.

The light beam after passing through the polarizing beam splitter 13 is then reflected by the second dichroic element 14 . In order to accommodate the entire optical system in a slim type optical pickup, the HD-DVD optical system having a larger optical magnification than a compact disc (CD) optical system uses reflected light of the second dichroic element 14 .

As shown in Figure 2, in order to minimize the chance of high aberrations occurring at the position of the CD optical system and to take into account the refractive properties of the dichroic film, the second dichroic element 14 is wedge-shaped and the light beam is normal to the reflective surface 21 The incident angle θ21 is preferably set to not more than 40 degrees. In this case, then, the outgoing angle θ22 of the light beam with respect to the normal direction of the reflecting surface is also set to be not greater than 40 degrees.

In this way, the influence of high aberration occurring at the position of the CD optical system can be suppressed and the light beam of the first wavelength can be reflected by the second dichroic element 14 with high reflectivity. The light beam reflected by the second dichroic element 14 is then transmitted through the collimating lens 20 and reflected by the emitting mirror 16 . The linearly polarized beam reflected by the transmitting mirror 16 is converted into a circularly polarized beam by the 1/4 wave plate of the optical element 21 and the circularly polarized beam is transmitted through the objective lens 22, the numerical aperture of which is limited by the wavelength selection and the numerical aperture The elements are suitably controlled so as to vary according to wavelength. The light beam reflected from disc 15 then follows a forward path. That is, the light beam reflected from the disc is transmitted through the objective lens 22 and the optical element 21, reflected by the emission mirror 16, transmitted through the collimating lens 20, and reflected by the second dichroic element 14 to the polarizing beam splitter 13, while the polarized beam The beam splitter 13 in turn reflects the light beam to the first optical detector 17a. The numerical aperture limiting element limits the numerical aperture of the objective lens 22 so as to reduce the numerical aperture of the objective lens 22 as the wavelength of the light beam becomes longer.

Also, a laser diode 11b as a second light source emits a light beam having a wavelength range of 655 nm for DVD. The light beam emitted from this diode passes through the combination lens 18b and is first reflected by the first dichroic element 12 .

As shown in FIG. 3 , in order to minimize the chance of wavefront aberration when the light beam emitted by the first light source is transmitted and take into account the refraction properties of the dichroic film, the first dichroic element 12 is wedge-shaped and the light beam is opposite to the reflective surface The incident angle θ31 and the reflection angle θ32 of the normal direction are preferably set to not more than 40 degrees. Thus, the influence of wavefront aberration occurring when the light beam of the first wavelength is transmitted can be suppressed, and the light beam of the second wavelength can be reflected with a high reflectivity.

Then, the light beam reflected by the first dichroic element 12 travels substantially along the same path as the light beam emitted by the above-mentioned HD-DVD laser diode 11a. That is to say, the light beam reflected by the first dichroic element is transmitted through the polarizing beam splitter 13, reflected by the second dichroic element 14, transmitted through the collimator lens 20, reflected by the emitting mirror 16, and passed through the optical element 21 and the objective lens 22, and radiate onto disk 15. The light beam reflected from the disc 15 passes through the objective lens 22, the optical element 21 again, is reflected by the transmitting mirror 16, passes through the collimating lens 20, is reflected by the second dichroic element 14, is reflected by the polarizing beam splitter 13, and enters the first Optical detector 17a.

The first optical detector 17a is used to detect optical signals reflected from the disk and to generate radio frequency signals, focus signals, tracking signals, etc. when the disk 15 is accessed for recording data and played back to reproduce the original The optical signal from the disc that receives the beam from the HD-DVD and DVD laser diodes.

Also, the 1/4 wave plate as the light polarizing element of the optical element 21 may be replaced by a polarization hologram having an operating wavelength range including the first and second wavelengths.

A laser diode 11c serving as a third light source, a second optical detector 17b and a spectroscopic device 19 are integrated into a combined spectroscopic device and laser unit. The laser diode 11c emits a light beam having a wavelength range of 785 nm for CD. The beam passes through the beam splitting device 19 for splitting the beam when the beam reflected from the disk 15 passes therethrough to split a part of the energy of the beam and passes through the combining lens 18c, and then transmits through the second dichroic element 14. Leads to the second optical detector 17b.

The light beam transmitted through the second dichroic element 14 passes through the collimating lens 20 and hits the transmitting mirror 16, and passes through the optical element 21, the objective lens 22, and reaches the disc 15 (in this example an optical disc). The light beam reflected from disc 15 follows a forward path. That is, since, for example, a combined spectroscopic device and laser unit is used as shown in FIG. 1, the reflected light beam is diffracted in this unit and enters the second optical detector 17b near the laser diode 11c. The second optical detector 17b detects optical signals reflected from the disc 15 and is used to generate radio frequency signals, focus signals, tracking signals, etc. when the disc 15 receiving light beams from the CD diode is accessed for recording data and playing to reproduce original signals.

Remember, as explained in connection with the optical path of the beam from the first light source, the linearly polarized beam is converted into a circularly polarized beam by the 1/4 wave plate (which is the light polarizing element of the optical element 21) and the circularly polarized beam is transmitted through the objective lens 22 , and reach the disk 15, the numerical aperture of the objective lens is suitably controlled by a wavelength-selective numerical aperture limiting element so as to vary according to the wavelength. Therefore, it goes without saying that the light beams from the second light source and the third light source travel to the disc through the same optical path as the light beam from the first light source. A light polarizing element, such as a quarter-wave plate, polarizes each light beam at the first, second, and third wavelengths.

In this embodiment, since the combination lens 18b is interposed between the laser diode 11b and the first dichroic element 12, the magnification of the optical system that can transmit the light beam of the second wavelength in the forward direction is the same as that of the optical system that can transmit the light beam in the forward direction. The magnification of the optical system for the first wavelength light beam is different. Also, since the combined lens 18c is interposed between the laser diode 11c and the second dichroic element 14, the magnification of the optical system capable of transmitting the light beam of the third wavelength in the forward direction can be changed. Furthermore, it can be presumed that the combined lens 18 a is also interposed between the laser diode 11 a and the first dichroic element 12 . In this case, similar to the case where the combination lens 18b is interposed between the laser diode 11b and the first dichroic element 12, the magnification of the optical system capable of transmitting the light beam of the first wavelength in the forward direction is the same as that in the forward direction. The magnification of the optical system that transmits the light beam of the second wavelength is different.

According to the foregoing embodiments of the present invention, it is possible to provide an enhanced compact optical pickup device capable of generating a beam spot for recording and reproducing information into and from a recording medium from a laser beam emitted from a laser diode, and It is possible to detect light beams of three wavelengths for HD-DVD/DVD/CD read/write operations, and it is also possible to provide an optical disc device equipped with such an optical pickup device.

More specifically, when the light beams emitted from the three laser diodes 11a, 11b, and 11c are directed to one objective lens 22, it is critical to keep the wavefront aberration deliberately low and to keep the utilization efficiency of light energy deliberately low. high ground. Then, in the above-mentioned embodiment, the HD-DVD optical system is constituted by the optical system that allows the light beam to transmit through the first dichroic element 12 and the polarizing beam splitter 13 and thus the wavefront aberration becomes small and the light energy Utilization can be intentionally kept high.

Also, in the slim type optical pickup, the entire optical system is required to be small in size so that the pickup can accommodate the optical system. According to the above-described embodiment, the light beam reflected by the second dichroic element 14 is used in the HD-DVD optical system with a large optical magnification. Therefore, the size of the entire optical system can be reduced compared with that of a compact disc (CD).

Furthermore, according to the above-described embodiment, the first optical detector 17a for detecting the optical signal reflected from the disc 15 is also used to detect the optical signal emitted from the disc (which reflects the laser beams from the HD-DVD laser source and the DVD laser source). signal, and thus the number of optical detectors can be reduced to two. That is, only the above-mentioned first optical detector 17a and second optical detector 17b for detecting the light beam from the CD laser source are incorporated into a system for HD-DVD/DVD/CD read/write operations. An optical pickup device for detection of beams of three wavelengths.

The optical pickup device described above can be applied to an optical disc device capable of generating a beam spot for recording and reproducing information to and from a recording medium from a laser beam emitted from a laser diode.

Claims (15)

1. optic pick-up, it comprises:

First light source is used to launch the light beam of first wavelength;

Secondary light source is used to launch the light beam of second wavelength, and described second wavelength is greater than first wavelength;

The 3rd light source is used to launch the light beam of three-wavelength, and described three-wavelength is greater than second wavelength;

First recombination dichroic elements is used for transmission and crosses the light beam of first wavelength and the light beam of reflection second wavelength;

Second recombination dichroic elements is used to reflect the light beam of first and second wavelength and the light beam that three-wavelength is crossed in transmission;

Object lens are used for transmission and cross and have first and second wavelength and entered and left the light beam of first and second recombination dichroic elements and had three-wavelength and the light beam of second wavelength is crossed in transmission, and are used for light beam is projected disk.

2. according to the optic pick-up of claim 1, also comprise: the numerical aperture limiting element, it is used for the numerical aperture corresponding to the wavelength restriction object lens of light beam.

3. according to the optic pick-up of claim 1, also comprise:

Polarizing beam splitter, it is between first recombination dichroic elements and second recombination dichroic elements;

First fluorescence detector is used for reception and is polarized the beam splitter beam reflected; With

The light polarization element is used for each light beam of polarization first, second and three-wavelength.

4. according to the optic pick-up of claim 3, also comprise:

Light-dividing device is used to cut apart by the 3rd light emitted and from the light beam of the three-wavelength of disk reflection; With

Second fluorescence detector is used to receive the light beam of cutting apart.

5. according to the optic pick-up of claim 1, also comprise: first compound lens, it is between first light source and first recombination dichroic elements.

6. according to the optic pick-up of claim 1, also comprise: second compound lens, it is between the secondary light source and first recombination dichroic elements.

7. according to the optic pick-up of claim 1, also comprise: the 3rd compound lens, it is between second recombination dichroic elements and the 3rd light source.

8. according to the optic pick-up of claim 1, wherein second recombination dichroic elements is a wedge shape.

9. according to the optic pick-up of claim 1, wherein second recombination dichroic elements is constructed to make the light beam of first and second wavelength to be not more than 40 degree with respect to the incident angle of the second recombination dichroic elements reflecting surface normal direction.

10. according to the optic pick-up of claim 1, wherein first recombination dichroic elements is constructed to make the light beam of second wavelength to be not more than 40 degree with respect to the incident angle of the first recombination dichroic elements reflecting surface normal direction.

11. according to the optic pick-up of claim 3, wherein polarizer is one of polarization holograms and 1/4 ripple plate.

12. an optic pick-up, it comprises:

First light source is used to launch the light beam of first wavelength;

Secondary light source is used to launch the light beam of second wavelength, and described second wavelength is greater than first wavelength;

The 3rd light source is used to launch the light beam of three-wavelength, and described three-wavelength is greater than second wavelength;

First recombination dichroic elements is used for transmission and crosses the light beam of first wavelength and the light beam of reflection second wavelength;

Polarizing beam splitter, its operating wavelength range comprises first and second wavelength;

Second recombination dichroic elements is used to reflect the light beam of first and second wavelength and the light beam that three-wavelength is crossed in transmission;

Collimation lens is used for transmission and crosses the light beam of being crossed second recombination dichroic elements by the second recombination dichroic elements beam reflected and transmission;

Object lens are used for transmission after passing collimation lens and have first, second and the light beam of three-wavelength, and are used for light beam is projected disk;

The light polarization element is used for each light beam of polarization first, second and three-wavelength, and the numerical aperture limiting element, is used for the numerical aperture corresponding to the wavelength restriction object lens of light beam;

First fluorescence detector, be used for receiving have first and second wavelength and after the disk reflection by first recombination dichroic elements and the second recombination dichroic elements beam reflected;

Light-dividing device is used to cut apart and has three-wavelength and cross the light beam of second recombination dichroic elements in transmission after disk reflection; With

Second fluorescence detector is used to receive the light beam of being cut apart by light-dividing device.

13. according to the optic pick-up of claim 12, wherein the 3rd light source, light-dividing device and second fluorescence detector are integrated into a unit.

14. an optical disc apparatus, the optic pick-up that it comprises according to claim 4 is used for producing from laser diode emitted laser bundle and is used to record information to recording medium and from the beam spot of recording medium reproducing information.

15. an optical disc apparatus, the optic pick-up that it comprises according to claim 12 is used for producing from laser diode emitted laser bundle and is used to record information to recording medium and from the beam spot of recording medium reproducing information.

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