JP2013186929A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device suitable for an optical pickup device which also functions as a photodetector for receiving laser beams having different wavelength.SOLUTION: The device comprises :a photodetector to which return light of a first laser beam and a second laser beam reflected from each signal recording layer provided in each optical disk having a different standard is irradiated and which is provided with a light receiving part that also functions as a light receiving part of the first laser beam and the second light beam; and a diffraction optical element for adjusting an optical axis of the first laser beam by displacement operation in an optical axis direction and rotational displacement operation centered on the optical axis and guiding the first laser beam to the light receiving part. The device includes a holder 11 to which the diffraction optical element is fixed, and which is provided in a linearly displaceable and rotationally displaceable manner with respect to a housing 13 of an optical pickup device and is held in an adjustable state by elastic force of a plate spring 12 for pressing the holder 11 to the housing 13.

Description

  The present invention relates to an optical pickup device that performs a read operation of a signal recorded on an optical disc using a laser beam.

  2. Description of the Related Art Optical disk apparatuses that can perform a signal reading operation by irradiating a signal recording layer of an optical disk with laser light emitted from an optical pickup apparatus have become widespread.

  As an optical disk apparatus, an apparatus using an optical disk called a CD or a DVD is generally widespread. Recently, an optical disk with improved recording density, that is, an apparatus using a Blu-ray standard optical disk has been developed.

  For example, infrared light having a wavelength of 785 nm is used as a laser beam for reading a signal recorded on a CD standard optical disk, and a laser beam for performing a signal reading operation recorded on a DVD standard optical disk is used. For example, red light having a wavelength of 655 nm is used.

  Further, the thickness of the transparent protective layer provided between the signal recording layer and the surface of the optical disc in the CD standard optical disc is 1.2 mm, and is used to read out signals from the signal recording layer. The numerical aperture of the objective lens to be set is set to 0.47. The thickness of the transparent protective layer provided between the signal recording layer in the DVD standard optical disc and the surface of the optical disc is 0.6 mm, and is used to read out signals from the signal recording layer. The numerical aperture of the objective lens to be set is set to 0.6.

  For such CD standard and DVD standard optical disks, the laser light for performing the read operation of the signals recorded on the Blu-ray standard optical disk is a laser light having a short wavelength, for example, a blue-violet light having a wavelength of 405 nm. It is used.

  The thickness of the protective layer provided on the upper surface of the signal recording layer in the Blu-ray standard optical disc is 0.1 mm, and the aperture of the objective lens used to read out signals from the signal recording layer The number is set to 0.85.

  In order to read out signals recorded on a signal recording layer provided on a Blu-ray standard optical disc, it is necessary to reduce the diameter of the laser spot generated by condensing the laser beam. The objective lens used to obtain a desired laser spot shape has a feature that not only the numerical aperture is increased but also the focal length is shortened, so that the radius of curvature of the objective lens is reduced.

  An optical disc apparatus capable of reading signals recorded on all the optical discs of the CD standard, the DVD standard and the Blu-ray standard has been commercialized. An optical pickup device incorporated in such an optical disc apparatus. Includes a laser diode that emits a laser beam having a wavelength corresponding to each of the aforementioned standards and an objective lens that focuses the laser beam emitted from the laser diode onto a signal recording layer provided in each optical disc. Yes.

Many optical pickup devices that can read out signals recorded on optical discs of all the different standards described above include an objective lens that performs a condensing operation of laser light on optical discs of CD standards and DVD standards, and Blu. -Two objective lenses are incorporated which are the objective lenses for condensing the laser beam on the optical disc of the ray standard.

The optical pickup device in which such two objective lenses are incorporated has a problem that the configuration of the optical system becomes complicated and the shape of the optical pickup device becomes large. As a method for solving such a problem, a technique has been developed in which a single objective lens performs a laser beam condensing operation on all standard optical discs. (See Patent Document 1)
Further, not only is it configured to perform the laser beam focusing operation on all such standard optical discs with a single objective lens, but it is also reflected from the signal recording layer provided on the optical disc by a single photodetector. Techniques have been developed that are configured to perform a laser beam detection operation. (See Patent Document 2)
In the optical pickup device, spherical aberration occurs due to the thickness of the protective layer between the disk surface that is the laser light incident surface of the optical disk and the signal recording layer, and the signal reading and recording operations are normal. As a method of solving such a problem, a method of correcting spherical aberration by moving a collimating lens provided between the laser diode and the objective lens in the optical axis direction is often adopted. Yes. (See Patent Document 3)

JP 2006-236414 A JP 2011-175690 A Japanese Unexamined Patent Publication No. 2011-10052

  A laser diode in which laser chips emitting laser beams having different first, second, and third wavelengths are incorporated in the same housing, and first, second, and third laser beams emitted from the laser diode are An optical pickup device including an objective lens that is incident and collects each laser beam on a signal recording layer provided on an optical disc of a different standard will be described with reference to FIG.

  In FIG. 6, reference numeral 1 denotes a first laser chip that emits a first laser light that is blue-violet light having a wavelength of 405 nm, a second laser chip that emits a second laser light that is red light having a wavelength of 655 nm, and a wavelength is 785 nm. Is a laser diode in which a third laser chip that emits a third laser beam that is an infrared color light is incorporated in the same housing, and a drive signal is sent to the laser chip that emits a laser beam having a wavelength corresponding to the type of optical disk Is configured to be supplied.

  Reference numeral 2 denotes a diffraction grating on which the first laser beam, the second laser beam, and the third laser beam emitted from the laser diode 1 are incident, and the laser beam that performs the control operation of the optical pickup device using the sub beam is the 0th order. The main beam that is light, the + 1st order light, and the two subbeams that are −1st order light are separated.

  Reference numeral 3 denotes a half mirror on which the laser beam transmitted through the diffraction grating 2 is incident, and is configured to reflect the S-polarized light emitted from the laser diode 1 and transmit the P-polarized light.

Reference numeral 4 denotes a quarter-wave plate provided at a position where the laser beam reflected by the half mirror 3 is incident. The incident laser beam is changed from linearly polarized light to circularly polarized light and vice versa. It functions to convert polarized light into linearly polarized light. Reference numeral 5 denotes a collimating lens for converting the incident laser light into parallel light as the laser light transmitted through the quarter-wave plate 4 is incident. The collimating lens 5 is rotated by a lead screw 6A that is rotationally driven by an aberration correction motor 6. It is configured to be displaced in the axial direction. That is, the collimating lens 5 is displaced in the optical axis direction by the rotational driving operation of the lead screw 6A by the rotation of the aberration correcting motor 6, and the thickness of the protective layer of the optical disc is displaced by the collimating lens 5 displacement operation. It is configured to correct spherical aberration generated based on the above.

  Reference numeral 7 denotes an objective lens provided at a position where the laser light transmitted through the collimating lens 5 is incident, and has a function of condensing the laser light on each signal recording layer provided on each optical disk described later. It is. A diffraction zone for setting the numerical aperture is provided on the incident surface of the objective lens 7. Further, by providing a numerical aperture setting element that regulates the numerical aperture between the objective lens 7 and the collimating lens 5, it is possible to set the numerical aperture suitable for each laser beam.

L1 is a first optical disc D1 (Blu-ray) having a short distance from the surface of the optical disc to the signal recording layer.
-Ray standard), L2 is the signal recording layer in the second optical disk D2 (DVD standard), the distance from the surface of the optical disk to the signal recording layer being longer than the first optical disk D1, L3 is the signal recording layer from the surface of the optical disk This shows the position of the signal recording layer in the third optical disc D3 (CD standard) whose distance to is longer than the second optical disc D2.

  In such a configuration, the first laser light emitted from the first laser chip incorporated in the laser diode 1 is transmitted through the diffraction grating 2, the half mirror 3, the quarter wavelength plate 4, and the collimating lens 5. 7, the signal recording layer L1 provided on the first optical disc D1 is irradiated as a focusing spot by the focusing operation of the objective lens 7, and the first recording layer L1 is irradiated to the signal recording layer L1. The laser light is reflected as return light by the signal recording layer L1.

  Further, the second laser light emitted from the second laser chip incorporated in the laser diode 1 is the same as the first laser light described above, the diffraction grating 2, the half mirror 3, the quarter wavelength plate 4, and the collimating lens. After being incident on the objective lens 7 via 5, the signal recording layer L2 provided on the second optical disc D2 is irradiated as a focused spot by the focusing operation of the objective lens 7, but the signal recording layer L2 The second laser light applied to the light is reflected as return light by the signal recording layer L2.

  And the 3rd laser beam radiated | emitted from the 3rd laser chip incorporated in the laser diode 1 is the diffraction grating 2, the half mirror 3, 1/4 wavelength similarly to the 1st laser beam and 2nd laser beam which were mentioned above. After being incident on the objective lens 7 through the plate 4 and the collimating lens 5, the signal recording layer L3 provided on the third optical disc D3 is irradiated as a focused spot by the focusing operation of the objective lens 7. The third laser light applied to the signal recording layer L3 is reflected as return light by the signal recording layer L3.

  The return light reflected from each signal recording layer L1, L2, L3 provided on each optical disc D1, D2, D3 is incident on the half mirror 3 through the objective lens 7, the collimating lens 5, and the quarter wavelength plate 4. The The return light incident on the half mirror 3 in this way is changed to linearly polarized light in the P direction by the phase changing operation by the quarter wavelength plate 4. Accordingly, the return lights of the first laser light, the second laser light, and the third laser light are not reflected by the half mirror 3 but are transmitted as control laser light.

Reference numeral 8 denotes an AS plate that functions as an aberration correction plate on which the control laser beam transmitted through the half mirror 3 is incident. The AS plate 8 generates a focus error signal based on the magnitude of astigmatism generated by the half mirror 3. Therefore, the correction is made so that the size is suitable, and the coma aberration generated in the half mirror 3 is corrected. Reference numeral 9 denotes a photodetector that is irradiated with control laser light through the AS plate 8, and is provided with a light receiving portion such as a well-known quadrant sensor.

  The optical pickup device includes a signal generation operation and an astigmatism method associated with a reading operation of a signal recorded on a signal recording layer of an optical disc by an irradiation operation of a main beam onto a light receiving unit provided in the above-described photodetector 9. The focus error signal generating operation for performing the focusing control operation by the above and the tracking error signal generating operation for performing the tracking control operation by the irradiation operation of the two sub beams are configured. Since such control operations for generating various signals are well known, the description thereof is omitted.

  In the optical pickup device having such a configuration, the first laser light, the second laser light, and the third laser light are generated from the laser diode 1 by supplying a drive signal to the laser chip corresponding to the standard of the optical disk to be used. Radiated. The first laser beam, the second laser beam, and the third laser beam emitted from the laser diode 1 are incident on the objective lens 7 through the diffraction grating 2, the half mirror 3, the quarter wavelength plate 4, and the collimator lens 5. As a result of the focusing operation of the objective lens 7, the light is focused on the signal recording layer L1 of the first optical disc D1, the signal recording layer L2 of the second optical disc D2, and the signal recording layer L3 of the third optical disc D3.

  The first laser beam focused on the signal recording layer L1 of the first optical disc D1, the signal recording layer L2 of the second optical disc D2, and the signal recording layer L3 of the third optical disc D3 by the focusing operation of the objective lens 7, After the laser beam and the third laser beam are reflected by each signal recording layer, they pass through the objective lens 7, the collimator lens 5, the quarter wavelength plate 4, the half mirror 3, and the AS plate 8 to the photodetector 9. Will be irradiated. As a result, as is well known, a focus error signal and a tracking error signal are generated from signals obtained from the respective light receiving units incorporated in the photodetector 9, and focusing control operation and tracking control are performed by using such error signals. Operation is performed. As a result of performing the control operation in such an optical pickup device, it is possible to read out the signals recorded in the signal recording layers L1, L2, and L3 of the first optical disc D1, the second optical disc D2, and the third optical disc D3. I can do it.

  A first laser chip that generates and emits a first laser beam that performs a reading operation of a signal recorded on a first optical disc D1 that is Blu-ray standard, and a signal that is recorded on a second optical disc D2 that is a DVD standard The second laser chip that generates and emits the second laser light that performs the operation and the third laser chip that generates and emits the third laser light that performs the reading operation of the signal recorded on the third optical disc D3 that is the CD standard are the same. Signal recording provided on the first optical disc D1, the second optical disc D2, and the third optical disc D3 of different standards for the laser diode 1, the first laser beam, the second laser beam, and the third laser beam incorporated in the housing One objective lens 7 that focuses light on the layers L1, L2, and L3, and the signal recording layers L1, L2, and L3. The optical pickup device composed of one photodetector 9 that is irradiated with the control laser light that is the reflected first laser light, second laser light, and third laser light is configured as described above. .

  In the optical pickup device having such a configuration, spherical aberration occurs due to the thickness of the protective layer between the surface of each optical disk and the signal recording layer. As is well known, such spherical aberration is used for aberration correction. The collimator lens 5 is corrected by the displacement operation in the optical axis direction of the collimator lens 5 by the lead screw 6 </ b> A that is rotationally driven by the motor 6.

A laser diode 1 in which a first laser chip, a second laser chip, and a third laser chip are incorporated in one housing is called a three-wavelength laser diode, and is disclosed in Japanese Patent Application Laid-Open No. 2011-175690. The second laser chip and the third laser chip are manufactured on a single substrate by a monolithic technique, which is a semiconductor technique, as disclosed in Japanese Patent Laid-Open Publication), and the first laser chip includes the second laser chip and the third laser chip. It is formed on a substrate different from the substrate on which the laser chip is formed. That is, the first laser chip, the second laser chip, and the third laser chip are incorporated in one casing by a technique called a hybrid.

  In the three-wavelength laser diode having such a configuration, the second laser chip and the third laser chip are manufactured by the monolithic technique as described above, so that the distance between the two laser chips, that is, between the light emitting points can be shortened. In addition, there is an advantage that the variation in distance between the light emitting points can be reduced. On the other hand, since the first laser chip is incorporated into the second laser chip and the third laser chip manufactured by monolithic technology by hybrid technology, the light emitting point of the second laser chip and the light emitting point of the first laser chip are In addition to being unable to shorten the distance between the light emitting points, there is a disadvantage that the variation in distance between the light emitting points becomes large.

  When the distance between the light emitting point of the first laser chip that emits the first laser light and the light emitting point of the second laser chip that emits the second laser light is increased, the first laser light emitted from the laser diode 1 is increased. There will be a shift between the optical axis and the optical axis of the second laser light. As a result, when the light receiving unit incorporated in the photodetector 9 is used for both the first laser beam and the second laser beam, the light receiving unit is generated by the control laser beam that is the reflected laser beam of the first laser beam. The position of the spot and the position of the spot generated in the light receiving unit by the control laser light that is the reflected laser light of the second laser light are shifted.

  If the position of the spot generated by the return light of the first laser beam and the position of the spot generated by the return light of the second laser beam are deviated, the same light receiving unit cannot be used. In the pickup device, a diffractive optical element 10 for correcting the optical axis is provided between the half mirror 3 and the AS plate 8 as shown in FIG. In addition, the optical pickup device having such a configuration is configured to correct the optical axis of the first laser light by correcting the optical axis of the diffractive optical element 10.

  The diffractive optical element 10 corrects the optical axis of the first laser light, that is, does not act on the optical axes of the second laser light and the third laser light, that is, has wavelength selection characteristics. It is configured. Since a technique for adding such a wavelength selection characteristic to an optical element is well known, its description is omitted.

  The diffractive optical element 10 includes a housing constituting an optical pickup device, that is, a laser diode 1, a diffraction grating 2, a half mirror 3, a quarter wavelength plate 4, a collimating lens 5, an AS plate 8, a photodetector 9, and the like. It is bonded and fixed to the mounting portion provided on the mounted base, but as described above, between the light emitting point of the first laser chip and the light emitting point of the second laser chip incorporated in the laser diode 1. Since there is variation in the distance, the spot generated by the control laser light that is the return light of the first laser light is received by the spot generated by the control laser light that is the return light of the second laser light. There is a problem that irradiation is not generated on the light receiving portion provided at the position where the light is applied.

  The present invention is intended to provide an optical pickup device that can solve such a problem.

  According to the present invention, a laser diode that emits at least a first laser beam and a second laser beam having different wavelengths and a first laser beam and a second laser beam emitted from the laser diode are provided on each optical disc having different standards. An objective lens for focusing on each signal recording layer, and a first laser light and a return light of the second laser light reflected from each signal recording layer, and a light receiving portion for the first laser light and the second laser light The optical axis of the first laser light is adjusted by a photodetector provided with a light-receiving unit that also serves as a light source, a displacement operation in the direction of the optical axis, and a rotational displacement operation about the optical axis. In the optical pickup device including the diffractive optical element that leads to the light receiving unit, a holder to which the diffractive optical element is fixed is provided, and the holder is attached to the optical pickup device. It is provided so that it can be displaced linearly and rotationally with respect to the ging, and the holder is held in an adjustable state by the elastic force of a leaf spring that presses the holder against the housing. .

  Further, according to the present invention, a pair of pressing arm portions are provided on the leaf spring, and the pressing arm portions are brought into contact with a curved surface formed on the upper surface of the holder so that the holder is held in an adjustable state. It is characterized by.

  The present invention is characterized in that the plate spring is fixed to the housing by screwing of a fixing screw, and a position regulating member for defining the position of the plate spring is formed in the housing.

  Furthermore, the present invention is characterized in that a V-shaped groove is provided in the housing, and the holder is held in an adjustable state by an inclined wall constituting the V-shaped groove.

  Further, the present invention is characterized in that the fixing operation of the diffractive optical element is performed by fixing the holder to the housing with an adhesive.

  The present invention is characterized in that an adhesive application portion for applying an adhesive to the holder and the housing is formed.

  Furthermore, the present invention is characterized in that a recess is formed by an adhesive application part formed on the holder and an adhesive application part formed on the housing.

  The optical pickup device of the present invention uses a diffractive optical element provided to correct the optical axis of the first laser light in the first laser light and the second laser light, which have different optical axes emitted from the laser diode. Since the spot position with respect to the light receiving portion of the first laser light is adjusted by moving it straight in the axial direction and rotating around the optical axis, the light receiving portion for the first laser light and the light receiving portion for the second laser light In addition, it is possible to obtain an accurate control signal as a signal for performing a focus control operation or the like of the optical pickup device.

  In the present invention, the holder on which the diffractive optical element for performing optical axis correction is fixed is held in an optical axis adjustable state with respect to the housing by the elastic force of the leaf spring. A linear displacement operation and a rotational displacement operation can be easily performed.

  Further, according to the present invention, since the position regulating member for regulating the position of the leaf spring that performs the holding operation of the holder with respect to the housing is provided, the holding operation of the holder by the leaf spring can be accurately performed.

Furthermore, since the adhesive application part which applies the adhesive which fixes a holder to a housing is formed in this invention, the application | coating operation | work of an adhesive agent can be performed correctly and easily.

  In the present invention, since the recess is formed by the adhesive application portion formed on the holder and the adhesive application portion formed on the housing, the adhesive leaks from a desired location. Can be prevented.

It is a front view of the principal part which shows the Example of the optical pick-up apparatus which concerns on this invention. It is a perspective view of the components incorporated in the optical pickup device according to the present invention. It is a disassembled perspective view which shows the principal part of the optical pick-up apparatus which concerns on this invention. It is a top view which shows the principal part of the optical pick-up apparatus which concerns on this invention. It is explanatory drawing which shows the positional relationship of the light-receiving part incorporated in the photodetector of the optical pick-up apparatus which concerns on this invention, and a spot. It is the schematic which shows the optical system of the optical pick-up apparatus which concerns on this invention.

  A plurality of laser beams radiated from one laser diode can be used to read out signals recorded on optical disks of different standards, and at least two laser beams can be read out. The fixing position of the diffractive optical element for adjusting the optical axis incorporated in the optical pickup device equipped with the photodetector incorporating the dual-purpose light receiving portion that receives the return light reflected from the signal recording layer of the optical disc can be adjusted. An optical pickup device is provided.

  FIG. 1 is a front view showing the main part of the optical pickup device of the present invention, FIG. 2 is a perspective view of components incorporated in the optical pickup device of the present invention, and FIG. 3 is an exploded perspective view showing the main part of the optical pickup device of the present invention. 4 and 4 are plan views showing the main part of the optical pickup device of the present invention.

2, 11 is a holder to which the diffractive optical element 10 shown in FIG. 6 is fixed by press-fitting or bonding, and curved surfaces 11A and 11B on which pressing arms 12A and 12B of a leaf spring 12 described later are pressed on the upper surface. And adhesion parts 11C and 11D to which an adhesive is applied are formed. Further, the contact portions 11E, 11F, 11G, 11H (1
1G and 11H are formed on the back side in FIG. ) Is formed.

  The holder 11 to which the diffractive optical element 10 is fixed is configured as described above, and such a holder 11 has a housing 13 to which an optical component constituting the optical pickup device is fixed as shown in FIGS. It is made to be accommodated in the accommodating part 14 provided in this. The storage portion 14 is provided as a V-shaped groove, and the contact portions 11G and 11H formed on the holder 11 are in contact with the inclined walls 14A and 14B of the V-shaped groove. Although not shown, an inclined wall is also formed on the back side of the V-shaped groove, and the contact portions 11E and 11F formed on the holder 11 are in contact with the inclined wall. .

The leaf spring 12 that presses the holder 11 is formed with pressing arm portions 12A and 12B that contact curved surfaces 11A and 11B formed on the holder 11, and is formed on the housing 13 of the fixing screw 15. It is configured to be fixed to the housing 13 by screwing into the screw hole 16. In a state where the holder 11 in which the diffractive optical element 10 is fixed is stored in the storage portion 14 provided in the housing 13, the fixing screw 15 is screwed into the screw hole 16 provided in the housing 13. The leaf spring 12 can temporarily fix the holder 11 to the housing 13. That is, when the leaf spring 12 is fixed to the housing 13 by screwing the fixing screw 15 into the screw hole 16, the pressing arm portions 12A and 12B formed on the leaf spring 12 are curved surfaces 11A formed on the holder 11. And it will be in the state which press-contacted to 11B.

  In FIGS. 3 and 4, 13 </ b> A is a positioning protrusion formed on the housing 13 and is provided so as to engage with a positioning notch 12 </ b> C formed on the leaf spring 12. 13B is a positioning recess formed in the housing 13, and is provided so as to engage with a positioning projection 12D formed in the leaf spring 12. The leaf spring 12 can be positioned by such an engaging operation between the positioning protrusion 13A and the positioning notch 12C and an engaging operation between the positioning recess 13B and the positioning protrusion 12D. Therefore, the holding and holding operation of the holder 11 with respect to the housing 13 by the leaf spring 12 can be performed accurately.

  As described above, the fixing and holding operation of the holder 11 to the housing 13 by the leaf spring 12 is performed. In this state, the pressing arm portions 12A and 12B provided on the leaf spring 12 as shown in FIG. Since the pressing force acts on the curved surfaces 11A and 11B of the holder 11, the contact portions 11G and 11H formed on the holder 11 are pressed against the inclined walls 14A and 14B of the V-shaped groove. become. Similarly, the contact portions 11E and 11F formed on the holder 11 are in press contact with the inclined wall of the V-shaped groove provided at the back. Therefore, in this state, the holder 11 is supported in the storage position by the contact relationship between the inclined walls 14A and 14B of the V-shaped groove and the contact portions 11G, 11H, 11E, and 11F with the inclined walls (not shown). Therefore, the rotary displacement operation in the directions of arrows A and B shown in FIG. 1 and the linear displacement operation in the directions of arrows C and D shown in FIG. 4 are maintained.

  In such a configuration, the holder 11 is supported so as to be capable of rotational displacement in the directions of arrows A and B shown in FIG. 1, and the direction of such rotational displacement is performed around the optical axis of the laser beam. It is configured as follows. Further, the holder 11 is supported so as to be able to perform a linear displacement operation in the directions of arrows C and D shown in FIG. 4, and the direction of the linear displacement operation is performed with respect to the optical axis direction of the laser beam. It is configured.

  As described above, the holding operation of the holder 11 to which the diffractive optical element 10 is fixed to the housing 13 by the leaf spring 12 is performed, but the relationship between the light receiving portion incorporated in the photodetector 9 and the spot is illustrated. This will be described with reference to FIG.

  In FIG. 5, 9A, 9B and 9C are a main beam light-receiving unit, a first sub-beam light-receiving unit and a second sub-beam light-receiving unit incorporated in the photodetector 9, for example, each of which is a four-divided sensor. It is configured. The main beam light-receiving unit 9A, the first sub-beam light-receiving unit 9B, and the second sub-beam light-receiving unit 9C act as light-receiving units to which the return light of the first laser beam and the second laser beam is irradiated. That is, it is configured to serve also as a light receiving unit that receives the return light of the first laser light and the second laser light. The light receiving unit that receives the third laser light is provided so as to receive only the third laser light, and is omitted in the present embodiment.

  In FIG. 5, M1 is a main beam spot of the second laser light generated by the control laser light that is the reflected light from the signal recording layer of the second laser light, That is, it shows a state in which it is located at the optimum position as the set position. B1, B2 and B3 are main beam spots of the first laser beam generated by the control laser beam which is the reflected light from the signal recording layer of the first laser beam, and B1 is the center of the main beam light receiving portion 9A. In other words, B2 and B3 are deviated in the linear direction and also in the rotational direction.

  When the position of the main beam spot of the first laser beam is at the position indicated by B1, that is, when it is deviated only in a linear direction with respect to the set position of the main beam light receiving portion 9A, the diffractive optical element 10 is irradiated The displacement can be corrected by linearly displacing in the axial direction. When the position of the main beam spot is at the position B2 or B3, that is, in the linear direction and the rotational direction with respect to the set position of the main beam light receiving unit 9A If they are also shifted, both of the shifts can be corrected by linearly displacing the diffractive optical element 10 in the optical axis direction and rotating about the optical axis.

  In the present invention, as described above, the holder 11 that is held in an adjustable state by the storage portion 14 provided in the housing 13 by the elastic force of the leaf spring 12 is linearly displaced in the direction of arrow C or D in FIG. In addition, the positional displacement of the spot generated by the reflected light of the first laser beam with respect to the light receiving portion can be corrected by rotationally displacing in the arrow A or B direction in FIG.

  As described above, the diffractive optical element 10 can be temporarily fixed at an optimal position by performing the linear displacement operation and the rotational displacement operation of the holder 11 that is held in an adjustable state. In a state where such a fixing operation is performed, the holder 11 can be firmly fixed to the housing 13 by applying an adhesive to the adhesive application portions 11C and 11D provided in the holder 11. Adhesive application portions 13C and 13D are formed at positions facing the adhesive application portions 11C and 11D provided on the holder 11 of the housing 13.

  For example, an ultraviolet curable adhesive is applied to a recess formed by the adhesive application portions 11C and 11D formed on the holder 11 and the adhesive application portions 13C and 13D formed on the housing 13. The holder 11 can be firmly fixed to the housing 13 by curing the adhesive by irradiation with ultraviolet rays. The diffractive optical element 10 fixed to the holder 11 can be fixed at an optimal position by the fixing operation of the holder 11.

  Since the adhesive application portions 11C and 11D formed on the holder 11 and the adhesive application portions 13C and 13D formed on the housing 13 form a recess where the adhesive is applied, In addition to preventing leakage of the agent, it is possible to reliably and easily apply the adhesive to a desired position.

  As described above, the linear displacement operation in the optical axis direction and the displacement operation in the rotation direction around the optical axis of the diffractive optical element 10 that corrects the deviation of the optical axis of the laser beam can be accurately performed. Axis correction can be performed accurately. Therefore, the present invention is very large when implemented in an optical pickup device configured to use a laser diode incorporating a laser chip that emits a plurality of laser beams having different optical axes and to also serve as a photodetector. There is an effect.

  The present invention is applied not only to an optical pickup device for reading signals recorded on an optical disc of Blu-ray standard, an optical disc of DVD standard, and an optical disc of CD standard, but also to optical pickup devices of other different standards. I can do it.

  Further, although the case where the present invention is implemented in an optical pickup device using a three-wavelength laser diode has been described, it is needless to say that the present invention can be implemented in an optical pickup device using a two-wavelength laser diode.

DESCRIPTION OF SYMBOLS 1 Laser diode 3 Half mirror 4 1/4 wavelength plate 5 Collimating lens 7 Objective lens 8 AS plate 9 Photodetector 10 Diffractive optical element 11 Holder 12 Leaf spring 13 Housing 14 Storage part

Claims (7)

A laser diode that emits at least a first laser beam and a second laser beam having different wavelengths, and each signal recording that is provided on each optical disc having a different standard for the first laser beam and the second laser beam emitted from the laser diode. An objective lens for condensing light on the layer, and a first laser beam and a return beam of the second laser beam that are reflected from each signal recording layer, and a light receiving unit that also serves as a light receiving unit for the first laser beam and the second laser beam. The optical axis of the first laser beam is adjusted by a photodetector provided with a portion, a displacement operation in the direction of the optical axis and a rotational displacement operation about the optical axis, and the first laser beam is transmitted to the light receiving unit. A diffractive optical element for guiding, and a holder for fixing the diffractive optical element is provided, and the holder can be linearly displaced with respect to the housing of the optical pickup device Displaceably arranged, and the optical pickup apparatus is characterized in that so as to retain the holder to the adjustment state by the elastic force of the pressing to the plate spring of the holder relative to the housing. A pair of pressing arm portions are provided on the leaf spring, and the holder is held in an adjustable state by bringing the pressing arm portions into contact with a curved surface formed on the upper surface of the holder. 2. The optical pickup device according to 1. 3. The optical pickup device according to claim 2, wherein the plate spring is fixed to the housing by screwing of a fixing screw, and a position regulating member for defining the position of the plate spring is formed on the housing. 2. The optical pickup device according to claim 1, wherein a V-shaped groove is provided in the housing, and the holder is held in an adjustable state by an inclined wall constituting the V-shaped groove. 5. The optical pickup device according to claim 1, wherein the diffractive optical element is fixed by fixing the holder to the housing with an adhesive. The optical pickup device according to claim 5, wherein an adhesive application portion for applying an adhesive is formed on the holder and the housing. The optical pickup device according to claim 6, wherein a recess is formed by an adhesive application portion formed on the holder and an adhesive application portion formed on the housing.

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