JP2007334999A - Optical pickup device and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device capable of at least either piece of recording or reproducing information to a DVD and a CD with sufficient characteristic even when an inexpensive diffraction element is used, and to provide an optical disk device thereof. <P>SOLUTION: In the optical pickup device, with respect to tracks 18c, 18d and 19a on which 0th order light is incident, the diffraction grid has combination of a grid spacing and a grid direction where ±primary light is incident between tracks 18c apart by two tracks and a track 18c apart by three tracks, respectively, in the first DVD 18a of a first track pitch and between tracks 18d, 19a apart by one track and a track 18d, 19a apart by two tracks, respectively, in the second DVD 18b and CD 19 of a second track pitch nearly symmetrically with respect to the 0th order light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical pickup device and an optical disk device mounted on an electronic device such as a personal computer or a notebook computer.

  2. Description of the Related Art Conventionally, an optical pickup device used in an optical disc apparatus has been reduced in thickness and size as a notebook computer or the like on which the optical disc apparatus is mounted has been reduced in thickness and size. Accordingly, a laser light source that can emit laser light of two types of wavelengths has started to be used as a laser light source that emits laser light to an optical disk.

  FIG. 19 is a configuration diagram of an optical system of a conventional optical pickup device. The optical pickup device can record and / or reproduce information on DVD and CD. The laser light source 101 emits laser light having a wavelength λ1 (about 650 nm) for DVD and laser light having a wavelength λ2 (about 780 nm) for CD. The diffraction element 102 diffracts the DVD laser light to generate 0th-order light and ± 1st-order laser light, and the DVD diffraction grating 102a diffracts the CD laser light to 0th-order light and ± 1st-order light. And a CD diffraction grating 102b for generating laser light. The generated 0th-order light and ± 1st-order laser light are used for tracking control of the DVD 112 and the CD 113, respectively. The optical element 103 has a slope with a polarization separation film 103a inside. The polarization separation film 103a directs a part of the laser light emitted from the laser light source 101 and directed to the DVD 112 and CD 113 to the second light receiver 111, and directs the laser light reflected and returned from the DVD 112 and CD 113 to the light receiver 110. . The reflection mirror 104 bends the optical path to reduce the size of the optical pickup device. The collimating lens 105 converts the laser light emitted from the laser light source 101, which is divergent light, into substantially parallel light, and converts the parallel laser light reflected and returned by the DVD 112 and CD 113 into focused light. The quarter-wave plate 106 converts the polarization state of the DVD laser light emitted from the laser light source 101, which is P-polarized light, into circularly polarized light, and reflects the polarization state of the laser light reflected by the DVD 112 and returned as circularly polarized light. Convert to S-polarized light. The laser beam for CD is transmitted as P-polarized light. The rising prism 107 is a prism for raising an optical path that has been substantially parallel to the DVD 112 or the CD 113 so far in a direction perpendicular to the DVD 112 or the CD 113. The objective lens 108 is a condensing lens for entering the DVD 112 or the CD 113 with focusing. The detection lens 109 is a lens having different focal lengths in two cross sections perpendicular to the laser beam reflected by the DVD 112 and the CD 113 including the optical axis. The detection lens 109 generates a light beam used for focus control. The light receiver 110 receives laser light emitted from the laser light source 101 and reflected by the DVD 112 and CD 113. The output generates a signal used for tracking control, a signal used for focus control, a reproduction signal of DVD 112 or CD 113, and the like. The second light receiver 111 receives the laser light emitted from the laser light source 101. Based on the output, a signal used for output control of the laser light emitted from the laser light source 101 is generated.

  (Patent Literature 1), (Patent Literature 2), (Patent Literature 3), and (Patent Literature 4) include a laser light source 101 that emits a laser beam for DVD and a laser beam for CD, and a diffraction grating 102a for DVD. And a diffraction element 2 in which a diffraction grating 102b for CD is arranged in series in the optical path is shown. 20A is a perspective view of a conventional diffraction element, FIG. 20B is a cross-sectional view taken along a plane α, FIG. 20C is a top view, and FIG. 20D is a bottom view. In FIG. 20, the diffraction element 102 has a structure in which a diffraction grating 102a for DVD is formed on the upper surface of a substrate 102c, and a diffraction grating 102b for CD is formed on the lower surface. The diffraction gratings 102a and 102b are grooves formed at a predetermined interval, depth, and angle. It may be convex. The light amount and emission direction of ± primary light are determined by the interval, depth, and angle of the grooves. That is, the arrangement when entering the DVD 112 or the CD 113 is determined.

  An example of the arrangement of incident spots when entering the DVD 112 or the CD 113 will be described. FIG. 21A is a diagram showing an arrangement of laser beams incident on a DVD-R / RW, and FIG. 21B is a diagram showing an arrangement of laser beams incident on a CD. In the case of DVD-R / RW, the 0th-order light separated by the DVD diffraction grating 102a is incident on the track 112a as a spot 114. The ± first-order light is incident as a spot 114a at a position separated from the spot 114 by 0.5 track pitch on the opposite side. The direction of the groove of the diffraction grating 102a is determined so that the ± first-order light is inclined by the angle θ1 with respect to the track 112a.

  On the other hand, in the case of a CD, the 0th-order light diffracted by the CD diffraction grating 102 b is incident on the track 113 a as a spot 115. The ± first-order light is incident as a spot 115a on the opposite side from the spot 115 at a position separated by 0.5 track pitch. The direction of the groove of the diffraction grating 102b is determined so that the ± first-order light is inclined by the angle θ2 with respect to the track 113a.

The diffraction grating 102a and the diffraction grating 102b must be accurately manufactured in order to allow ± first-order light to enter the DVD 112 and the CD 113 at a predetermined appropriate position. Furthermore, the relative shift in the groove direction of the diffraction grating 102a and the diffraction grating 102b corresponding to the difference between the angle θ1 and the angle θ2 must be accurately adjusted.
JP-A-9-97448 JP 2003-6891 A JP 2003-162831 A JP 2005-25790 A

  However, since the diffraction element needs to produce a diffraction grating for DVD and a diffraction grating for CD with high accuracy and to combine the diffraction angle for DVD and diffraction grating for CD with high accuracy, It becomes inevitably expensive.

  The present invention solves the above-mentioned conventional problems, and an optical pickup device capable of recording and / or reproducing information with respect to a DVD and a CD with sufficient characteristics even when an inexpensive diffraction element is used, and An object is to provide an optical disk device.

  In order to achieve the above object, the present invention provides a laser light source that emits a laser beam that irradiates a first DVD having a first track pitch and a second DVD that has a second track pitch, and a laser beam that irradiates a CD. A diffraction grating that diffracts laser light emitted from the laser light source into zero-order light and ± first-order light to generate laser light used for tracking control, and the diffraction grating is incident on the zero-order light In the first DVD, between the two and three separate tracks, the second DVD and the CD have one and two separate tracks. In the middle of the optical pickup device, the optical pickup device has a combination of a lattice interval and a lattice direction so that the ± first-order light is incident substantially symmetrically about the zero-order light.

  Consider sharing the diffraction grating for the first DVD, the second DVD, and the CD. The first track pitch is about 0.74 μm, and the second track pitch is about 1.23 μm. The ratio of the track pitch of the first DVD and the second DVD is 0.74: 1.23≈3: 5 = 1.5: 2.5. In the second DVD, with respect to the track on which the 0th order light is incident, the + 1st order light and the −1st order light are substantially point-symmetric with respect to the 0th order light in the middle between the track separated by 1 and the track separated by 2 Assume that the grating interval and grating direction of the diffraction grating are combined so as to be incident on. Then, in the first DVD, with respect to the track on which the 0th-order light is incident, the + 1st-order light and the −1st-order light are approximately centered on the 0th-order light in the middle of the track that is 2 and 3 away. It will be incident point-symmetrically.

  On the other hand, a laser beam for irradiating the CD is incident on the same diffraction grating. The distance between the zero-order light and the ± first-order light of the laser light diffracted by the diffraction grating is proportional to the wavelength. The wavelength of the laser beam applied to the DVD is about 650 nm, and the wavelength of the laser beam applied to the CD is about 780 nm. For this reason, the distance between the zero-order light and the ± first-order light is longer by about 1.2 times for the laser light irradiated on the CD than on the laser light irradiated on the DVD. Since the track pitch of a CD having a capacity of 700 MB is about 1.49 μm, the ratio of the track pitch of the second DVD and CD is 1.23: 1.49≈1: 1.2. Therefore, in the CD, using the same diffraction grating, the 0th order light is intermediate between the track separated by one and the + 1st order light and the track separated by two with respect to the track on which the 0th order light is incident. , And can be made incident substantially symmetrically. In this way, when the + 1st order light and the −1st order light are incident on the track on which the 0th order light is incident approximately symmetrically with respect to the 0th order light between the tracks, the tracking control method is improved. One three-beam differential push-pull method can be employed.

  The optical pickup device of the present invention uses a diffraction grating shared by DVD and CD, and can perform appropriate tracking control for both DVD and CD. Therefore, even if an inexpensive diffractive element is used, at least one of information recording and reproduction can be performed on DVD and CD with sufficient characteristics.

  The invention of claim 1 of the present invention comprises a laser light source that emits a laser beam that irradiates a first DVD having a first track pitch and a second DVD that has a second track pitch, and a laser beam that irradiates a CD. A diffraction grating that diffracts laser light emitted from a laser light source into zero-order light and ± first-order light to generate laser light used for tracking control, and the diffraction grating is for a track on which zero-order light is incident In the first DVD, in the middle of two and three separate tracks, in the second DVD and CD, in the middle of one and two separate tracks, ± primary This is an optical pickup device having a combination of a grating interval and a grating direction in which light is incident substantially symmetrically with respect to zero-order light.

  By using a diffraction grating shared by both DVD and CD, appropriate tracking control can be performed for both DVD and CD. Therefore, even if an inexpensive diffractive element is used, at least one of information recording and reproduction can be performed on DVD and CD with sufficient characteristics.

  A second aspect of the invention is an optical pickup device according to the first aspect of the invention, wherein the first track pitch is about 0.74 μm and the second track pitch is about 1.23 μm.

  By using a diffraction grating shared by both DVD and CD, appropriate tracking control can be performed for both DVD and CD. Therefore, even if an inexpensive diffractive element is used, at least one of information recording and reproduction can be performed on DVD and CD with sufficient characteristics.

  According to a third aspect of the present invention, in the first aspect of the invention, the position where the ± first-order light is incident on the first DVD is a position separated from the zero-order light within a range of 2.50 ± 0.40 track pitch. This is an optical pickup device.

  The tracking control of the first DVD can be performed by the three-beam differential push-pull method.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the position where the ± first-order light is incident on the second DVD is a position separated from the zero-order light within a range of 1.50 ± 0.24 track pitch. This is an optical pickup device.

  The 1.50 ± 0.24 track pitch in the second DVD corresponds to the 2.50 ± 0.40 track pitch in the first DVD. Therefore, not only can the tracking control be performed by the 3-beam differential push-pull method in the first DVD, but also the tracking control by the 3-beam differential push-pull method can be performed with a margin in the second DVD.

  According to a fifth aspect of the present invention, in the first aspect of the invention, the position where ± 1st order light is incident on a CD having a capacity of 700 MB is separated from the 0th order light by a range of 1.49 ± 0.24 track pitch. It is an optical pickup device that is at the position.

  When the same diffraction grating is used, 1.49 ± 0.24 track pitch in a CD having a capacity of 700 MB corresponds to 2.50 ± 0.40 track pitch in the first DVD. Therefore, not only tracking control by the three-beam differential push-pull method can be performed on the first DVD, but also tracking control by the three-beam differential push-pull method can be performed with a margin on a CD having a capacity of 700 MB. .

  According to a sixth aspect of the present invention, in the first aspect of the present invention, the position where ± 1st order light is incident on a CD having a capacity of 650 MB is separated from the 0th order light within a range of 1.39 ± 0.22 track pitch. It is an optical pickup device that is at the position.

  A 1.49 ± 0.24 track pitch in a CD having a capacity of 700 MB corresponds to a 1.39 ± 0.22 track pitch in a CD having a capacity of 650 MB. Even in a CD having a capacity of 650 MB, tracking control by the three-beam differential push-pull method can be performed with a margin.

  According to a seventh aspect of the present invention, in the first aspect of the invention, the position where the ± first-order light is incident on the first and second DVDs is the distance in the radial direction of the first and second DVDs with respect to the zero-order light. Is an optical pickup device at a position separated by 1.85 ± 0.30 μm.

  The distance that the ± first-order light is 1.85 μm away from the zero-order light corresponds to a distance that is 2.5 track pitches away from the first DVD and 1.5 track pitch away from the second DVD. Further, 0.30 μm corresponds to a 0.40 track pitch in the first DVD and a 0.24 track pitch in the second DVD. Accordingly, tracking control can be performed using the 3-beam differential push-pull method in the first DVD, and tracking control can be performed using the 3-beam differential push-pull method with a margin in the second DVD. Can do.

  According to an eighth aspect of the present invention, in the first aspect of the invention, the position where the ± first-order light is incident on the CD is separated from the zero-order light in a range where the radial distance of the CD is 2.22 ± 0.36 μm. It is an optical pickup device that is at the position.

  When ± 1st order light is 1.85 ± 0.30 μm away from 0th order light in the first and second DVDs, using the same diffraction grating, ± 1st order light is 2 in relation to 0th order light in CD. .22 ± 0.36 μm away. This corresponds to a 1.49 ± 0.24 track pitch for a CD with a capacity of 700 MB, and a 1.39 ± 0.22 track pitch for a CD with a capacity of 650 MB. Tracking control by the differential push-pull method can be performed.

  According to a ninth aspect of the present invention, in the first and second DVDs according to the first aspect of the present invention, the diffraction grating is a ratio I10 / I11 of the light amount I10 of the 0th order light and the light amount I11 of the + 1st order light or the −1st order light. The combination of the refractive index and the grating depth is such that the ratio I20 / I21 of the light amount I20 of the 0th order light and the light amount I21 of the + 1st order light or the −1st order light is 15 to 30 in the CD. This is an optical pickup device.

  Since the I10 / I11 and I20 / I21 are appropriate, tracking control can be properly performed for both DVD and CD.

  According to a tenth aspect of the present invention, in the first aspect of the present invention, there is provided a light receiver that receives the laser light reflected by the first and second DVDs and the laser light reflected by the CD, and the first and second DVDs. And an optical element for directing the reflected laser light and the laser light reflected by the CD to a light receiver, and an optical pickup device provided with a diffraction grating on a surface facing the laser light source of the optical element.

  Since no new parts for forming the diffraction grating are required, the number of parts can be reduced, and the optical pickup device can be made more inexpensive. Further, the optical pickup device can be reduced in size by the amount that does not require new parts.

  According to an eleventh aspect of the present invention, in the first aspect of the present invention, a light receiver for receiving the laser light reflected by the first and second DVDs and the laser light reflected by the CD, a diffraction grating, and the first and second An optical element that is disposed between the DVD or CD of the first and second DVDs and CDs and that reflects the laser light reflected by the first and second DVDs and CDs, and the first and second optical elements that are directed to the light receiver by the optical elements. And a focus error generating element that gives a focus error to the laser light reflected by the DVD and CD.

  A focus error generating element generates laser light for focus control. Neither a diffractive element having a diffraction grating for generating tracking control laser light nor a focus error generating element for generating focus control laser light is disposed directly under the objective lens, so that it has the largest thickness among optical pickup devices. The required thickness of the objective lens portion can be reduced. Therefore, a thin optical pickup device can be obtained.

  According to a twelfth aspect of the present invention, in the invention of the eleventh aspect, the focus error generating element is a lens having a different focal length in two orthogonal sections including the optical axis, which are disposed between the optical element and the light receiver. An optical pickup device.

  Since focal lengths are different between two orthogonal cross sections including the optical axis, a focus control signal can be obtained.

  According to a thirteenth aspect of the present invention, in the eleventh aspect of the present invention, the focus error generating element is provided on an inclined surface of the optical element, and is a diffractive reflection having different focal lengths in two orthogonal sections including the optical axis. An optical pickup device that is a mirror.

  Since focal lengths are different between two orthogonal cross sections including the optical axis, a focus control signal can be obtained. The diffractive reflection mirror can be produced in a planar shape and can be formed on the slope of the optical element. Therefore, it is not necessary to dispose reflection mirrors having different focal lengths in two orthogonal cross sections including the optical axis outside the optical element, and the optical pickup device can be made smaller.

  The invention of claim 14 is the invention of claim 11, further comprising a coupling member that holds the laser light source, the diffraction grating, the light receiver, the optical element, and the focus error generating element as an integral unit and is fixed to the base. An optical pickup device.

  Since the optical components are fixed to a small coupling member as an integrated unit and then fixed to the base, the relative positional relationship among the laser light source, the diffraction element, the light receiver, the optical element, and the focus error generating element is unlikely to change. . For this reason, even if the base is made thin and the overall thickness of the optical pickup device is reduced, the relative positional relationship between these optical components hardly changes, and information recording and reproduction with respect to DVDs and CDs can be stabilized. Can be done. Therefore, it is possible to reduce the thickness of the optical pickup device.

  According to a fifteenth aspect of the present invention, there is provided a laser light source that emits a laser beam that irradiates a first DVD having a first track pitch and a second DVD that has a second track pitch, and a laser light source that emits laser light that irradiates a CD. A diffraction grating that diffracts the emitted laser light into 0th-order light and ± 1st-order light to generate laser light used for tracking control, and the diffraction grating has a first structure with respect to a track on which the 0th-order light is incident. ± 1st order light is 0 in the middle of the two and three separate tracks in the DVD, and in the middle of the one and two separate tracks in the second DVD and CD. This is an optical disk device provided with an optical pickup device having a combination of a grating interval and a grating direction so as to be incident substantially symmetrically with respect to the next light.

  By using a diffraction grating shared by both DVD and CD, appropriate tracking control can be performed for both DVD and CD. Therefore, even if an inexpensive diffractive element is used, at least one of information recording and reproduction can be performed on DVD and CD with sufficient characteristics.

(Embodiment 1)
The first embodiment will be described with reference to the drawings. FIG. 1 is a configuration diagram of an optical system of the optical pickup device according to the first embodiment, and FIG. 2 is a configuration diagram of the optical pickup device according to the first embodiment. The optical pickup device 17 is configured such that various components are attached to the base 12 which is a skeleton directly or via other components. The laser light source 1, the diffraction element 2, the beam splitter 3, the detection lens 9, and the light receiver 10 are held on the coupling member 13 as an integral unit to constitute a laser module 14. The coupling member 13 of the laser module 14 is fixed to the base 12. The objective lens 8 is fixed to a lens holder 15 that forms a part of the objective lens driving device 16, and the lens holder 15 is elastically supported by the main body of the objective lens driving device 16. The main body of the objective lens driving device 16 is fixed to the base 12. The reflection mirror 4, the quarter wavelength plate 6, the rising prism 7, and the second light receiver 11 are directly fixed to the base 12. In FIG. 1, the laser light source 1 to the quarter-wave plate 6 are projected onto a plane parallel to the DVD 18 and CD 19, and the riser prism 7 to the DVD 18 and CD 19 are relative to the plane perpendicular to the DVD 18 and CD 19. Projection.

  First, the optical component will be described. FIG. 3 is a configuration diagram of the laser light source according to the first embodiment. The laser light source 1 was a so-called frame laser light source provided with a plate 1c for fixing a submount 1b for fixing the light emitting element 1a. The thickness of the laser light source 1 is the sum of the thicknesses of the light emitting element 1a, the submount 1b, and the plate 1c plus the necessary thickness for the wiring, and can be reduced. Therefore, the thickness of the optical pickup device 17 can be reduced. The light emitting element 1a is an element that emits a DVD laser beam having a wavelength of about 650 nm to be irradiated on the DVD 18 and a CD laser beam having a wavelength of about 780 nm to be irradiated to the CD 19. However, the light emitting element 1a may be two elements, that is, an element that emits a laser beam for DVD and an element that emits a laser beam for CD.

  The submount 1b is formed of an insulating material having good thermal conductivity such as aluminum nitride. The plate 1c is composed of a plate-like body made of a metal material such as Cu, Cu alloy, Ag, Ag alloy, Al, Al alloy, Fe, or Fe alloy. More preferably, a material having good weldability is coated on the plate-like body by means such as plating or vapor deposition. The plate 1c may be made of a material having good thermal conductivity and high conductivity, such as conductive ceramics.

  The light emitting element 1a and the submount 1b are fixed with solder, and the submount 1b and the plate 1c are fixed with solder including cream solder, a conductive adhesive, or the like. A pattern is formed on the surface of the submount 1b and the plate 1c so that the light emitting element 1a and the lead 1d are appropriately connected, and wiring is performed by wire bonding using a gold wire. The wiring is protected by the protective member 1e. The plate 1c is fixed to the coupling member 13 at a plane portion outside the protective member 1e. Since the plate 1c is fixed to the coupling member 13 with a large area, good and stable assembly accuracy can be realized. A current for driving the light emitting element 1a is supplied from the lead 1d.

  4A is a perspective configuration diagram of the diffraction grating according to the first embodiment, FIG. 4B is a cross-sectional view taken along the plane A, and FIG. 4C is a bottom view. The diffraction element 2 of Embodiment 1 has a configuration in which a diffraction grating 2a is formed on the surface of a substrate 2b. The substrate 2b is an optical glass such as BK7. In the first embodiment, the diffraction grating 2a is a large number of parallel irregularities formed on the surface of the substrate 2a. In the first embodiment, the diffraction grating 2a is described as having a groove formed on the surface of the substrate 2a. However, the diffraction grating 2a may be formed with a convex. Further, although the diffraction grating 2a is provided on the lower surface side of the diffraction element 2, it may be on the upper surface side. The laser beam for DVD having a wavelength of about 650 nm and the laser beam for CD having a wavelength of 780 nm emitted from the laser light source 1 are incident on the diffraction element 2 from the lower surface side of the diffraction element 2 and are emitted toward the DVD 18 and CD 19 from the upper surface side. Is done. At this time, the diffraction grating 2a diffracts the DVD laser light and the CD laser light emitted from the laser light source 1 to generate 0th order light and ± 1st order laser light used for tracking control. The 0th order light is also called a main beam, and ± 1st order light is also called a side beam. The light quantity ratio between the zero-order light and the ± first-order light diffracted and generated by the diffraction grating 2a is mainly determined by the refractive index n, the depth d of the diffraction grating 2a, and the wavelength λ of the passing light, and the emission of the ± first-order light. The direction to be determined mainly depends on the distance p of the diffraction grating 2a, the direction θ of the diffraction grating 2a with respect to the direction parallel to the radial direction of the DVD 18 or CD 19, and the wavelength λ of the light passing therethrough.

  FIG. 5 is a configuration diagram of the beam splitter according to the first embodiment. The beam splitter 3 is an optical element that directs the DVD laser light reflected by the DVD 18 and the CD laser light reflected by the CD 19 to the light receiver 10. The beam splitter 3 is formed of optical glass or the like, and an inclined surface 3a is provided therein, and a polarization separation film 3b is formed on the inclined surface 3a. The polarization separation film 3b is composed of a multilayer dielectric film. The polarization separation film 3b transmits most of DVD laser light and CD laser light emitted from the laser light source 1 and being P-polarized light, and reflects a part thereof. In the first embodiment, about 85% is transmitted. The transmitted light is directed to the DVD 18 and the CD 19, and the reflected light is directed to the second light receiver 11. The polarization separation film 3b reflects 95% or more of the DVD laser light reflected by the DVD 18 and converted to S-polarized light. Further, it reflects about 15% of the laser beam for CD that is still P-polarized light reflected by CD19. The reflected light travels toward the light receiver 10.

  6A is a diagram showing the function of the detection lens of the first embodiment, and FIG. 6B is a diagram showing the shape of the condensed spot on the light receiving portion of the light receiving element of the light receiver when DVD and CD are close to each other. FIG. 6C is a diagram showing the shape of the focused spot on the light receiving portion of the light receiving element of the light receiver when the DVD and CD are far away. The detection lens 9 is a focus error generating element that gives a focus error to the laser beam for DVD and the laser beam for CD directed to the light receiver 10 by the beam splitter 3. The detection lens 9 gives a focus error to the laser beam for DVD and the laser beam for CD by having different values of the focal length in two orthogonal cross sections including the optical axis. In FIG. 6A, the detection lens 9 is a cylindrical lens, and one surface serves as a flat plate for laser light in the vertical direction of the paper, and serves as a concave lens for laser light in an orthogonal direction. The distance gets longer. The opposite surface is a flat plate. Therefore, when the light receiving portion 10b of the light receiving element 10a of the light receiver 10 is arranged between the focusing position 22 where the laser beam in the vertical direction on the paper is focused and the focusing position 23 where the laser beam in the direction orthogonal to the focal point is focused, A substantially circular focused spot appears at the center of the light receiving portion 10b.

  As shown in FIG. 6B, when the DVD 18 and the CD 19 approach the optical pickup device 17, the focusing position 22 where the laser beam in the vertical direction on the paper is focused approaches the light receiver 10, and the laser beam in the orthogonal direction is emitted. The in-focus position 23 for focusing is moved away from the light receiver 10. Therefore, the condensing spots of the light receiving part B and the light receiving part D become small, and the condensing spots of the light receiving part A and the light receiving part C become large. On the contrary, as shown in FIG. 6C, when the DVD 18 and CD 19 are moved away from the optical pickup device 17, the focusing position 22 where the laser beam in the vertical direction on the paper is focused is moved away from the light receiver 10 and the laser in the orthogonal direction is moved. The in-focus position 23 at which the light is focused approaches the light receiver 10. Therefore, the condensing spots of the light receiving part B and the light receiving part D become large, and the condensing spots of the light receiving part A and the light receiving part C become small. The difference between the outputs of the light receiving parts A and C and the outputs of the light receiving parts B and D is used as a focus control signal. The detection lens 9 in the optical pickup device 17 of the first embodiment is disposed at an angle of 45 ° in a plane perpendicular to the optical axis. The outer shape of the lens unit itself is circular. As described above, by disposing the detection lens 9 of the first embodiment, signals for focus control for DVD and CD can be obtained.

  FIG. 7 is a layout diagram of the light receiving portions of the light receiving elements of the light receiver according to the first embodiment. The light receiver 10 has a configuration in which a light receiving element 10a having a light receiving portion 10b is directly connected to a wiring board. Laser light reflected by the DVD 18 and CD 19 and passing through the detection lens 9 enters the light receiving unit 10b. The light receiving unit 10b includes DVD light receiving units A to L and CD light receiving units a to h.

  The laser beam for DVD and the laser beam for CD, which are emitted from the laser light source 1, diffracted by the diffraction grating 2 a, reflected by the DVD 18 and CD 19, and whose focal position is changed by the direction of the detection lens 9, are received by the light receiver 10. Incident on the part 10b. In the laser beam for DVD, the 0th order light is received by the light receiving parts A, B, C and D, one of the ± 1st order lights is received by the light receiving parts E, F, G and H, and the other is received by the light receiving parts I, J, K and L. Is incident on. In the laser beam for CD, zero-order light is incident on the light-receiving portions a, b, c, and d, one of the ± primary lights is incident on the light-receiving portions e and g, and the other is incident on the light-receiving portions f and h. The laser light incident on the light receiving unit 10b is converted into an electrical signal and output according to the amount of light incident on each light receiving unit. The output signal is used for focus control and tracking control. Further, when information recorded on the DVD 18 and CD 19 is reproduced, the information is also obtained from the output signal.

  The second light receiver 11 has a configuration in which a light receiving element having a light detection unit is directly connected to a wiring board. The second light receiver 11 converts the received light into an electrical signal corresponding to the amount of the received laser light and outputs it. The output signal is used for output control of laser light emitted from the laser light source 1.

  The reflection mirror 4 is a mirror for bending the optical path in order to reduce the size of the optical pickup device 17. A total reflection film is formed on the surface of the reflection mirror 4.

  The collimating lens 5 is made of optical glass or optical plastic. The collimating lens 5 converts the laser beam for DVD and the laser beam for CD, which are diverging light emitted from the laser light source 1, into substantially parallel light. Further, DVD laser light that is substantially parallel light reflected by the DVD 18 and CD laser light that is substantially parallel light reflected by the CD 19 are converted into focused light. The collimating lens 5 is a biconvex aspheric lens.

  The quarter-wave plate 6 has a phase that acts as a quarter-wave plate for laser light with a wavelength for DVD and does not substantially act as a wave plate for laser light with a wavelength for CD. ing. Therefore, the DVD laser light from the collimating lens 5 is converted from P-polarized light to circularly-polarized light. The laser beam for CD is transmitted as P-polarized light. Also, the DVD laser light reflected by the DVD 18 is converted from circularly polarized light to S-polarized light. The laser beam for CD reflected by CD 19 is transmitted as P-polarized light.

  The rising prism 7 is a triangular prism that reflects twice inside to change the traveling direction of the laser light to a direction perpendicular to the DVD 18 and CD 19. The rising prism 7 is made of optical glass or optical plastic. The rising prism 7 expands the width of the DVD laser light emitted from the laser light source 1 in the direction perpendicular to the DVD 18 and the width of the CD laser light in the direction perpendicular to the CD 19 and enters the objective lens 8. Also has work. Since the direction perpendicular to the DVD 18 and the CD 19 is the thickness direction of the optical pickup device 17, the thickness of the optical pickup device 17 can be reduced by using the rising prism 7.

  The objective lens 8 is a bifocal lens and is made of optical glass or optical plastic. The laser light made into substantially parallel light by the collimator lens 5 is condensed by the objective lens 8 so as to focus on the information recording surfaces of the DVD 18 and CD 19 corresponding to the respective wavelengths. The objective lens 8 uses a combination of a condensing lens and a Fresnel lens or a hologram lens, a combination in which a condensing lens for DVD is provided with an aperture restricting means during CD reproduction, and absorbs the difference in thickness and numerical aperture between the DVD 18 and the CD 19. It can also be used.

  The DVD 18 includes a DVD-ROM, a DVD ± R / RW, and a DVD-RAM. A DVD 18 having a track pitch of about 0.74 μm is defined as a first DVD 18a, and the first DVD 18a includes a DVD-RAM. The first track pitch is the track pitch of the first DVD 18a. A DVD 18 having a track pitch of about 1.23 μm is used as a second DVD 18b, and the second DVD 18b includes a DVD-R / RW. The second track pitch is the track pitch of the second DVD 18b. CD19 includes CD, CD-ROM, CD-R / RW and the like. CD 19 has a capacity of 700 MB, a track pitch of about 1.49 μm, and a capacity of 650 MB, and a track pitch of about 1.60 μm. Both DVD 18 and CD 19 can be recorded and reproduced except for a reproduction-only medium.

  Next, the state of the zero-order light and the ± first-order light generated by diffracting by the diffraction grating 2a on the DVD 18 or CD 19 will be described. FIG. 8 is a diagram showing an arrangement on the DVD or CD of the laser light diffracted by the diffraction grating of the first embodiment. Laser light emitted from the laser light source 1 and diffracted by the diffraction grating 2 a of the diffraction element 2 is incident on the DVD 18 or CD 19. The directions of the tracks 18c, 18d and 19a of the DVD 18 and CD 19 are parallel to the tangential direction of the circumference of the DVD 18 and CD 19.

  In the first DVD 18a, the zero-order light spot 20 is condensed on the track 18c. In the first DVD 18a, the track pitch of the track 18c is about 0.74 μm. The spot 20a of ± first-order light is condensed in the middle of the track 18c two away from the track 18c on which the spot 20 of the zero-order light is condensed and the track 18c three away. At that time, the spot 20a of the + 1st order light and the spot 20a of the −1st order light are condensed at a substantially point-symmetrical position around the spot 20 of the 0th order light. The direction in which the ± first-order spot 20a and the zero-order spot 20 are aligned is inclined by an angle φ with respect to the direction of the track 18c. This angle φ corresponds to the direction θ of the diffraction grating 2 a with respect to the direction parallel to the radial direction of the DVD 18 or CD 19.

  In the second DVD 18b, the zero-order light spot 20 is condensed on the track 18d. The 0th order light and the ± 1st order light in the second DVD 18b are exactly the same as the 0th order light and the ± 1st order light in the first DVD 18a. In the second DVD 18b, the track pitch of the track 18d is about 1.23 μm. The spot 20a of ± first-order light is condensed in the middle of the track 18d one distance away from the track 18d on which the spot 20 of the zero-order light is condensed and the track 18d two distances away. At that time, the spot 20a of the + 1st order light and the spot 20a of the −1st order light are condensed at a substantially point-symmetrical position around the spot 20 of the 0th order light. The direction in which the ± first-order spot 20a and the zero-order spot 20 are aligned is also inclined by an angle φ with respect to the direction of the track 18d.

  In the CD 19, the zero-order light spot 21 is condensed on the track 19a. The track pitch of CD 19 is about 1.49 μm or 1.60 μm. The spot 21a of ± first-order light is condensed in the middle of the track 19a one distance away from the track 19a where the spot 21 of the zero-order light is condensed and the track 19a two distances away. At that time, the spot 21a of the + 1st order light and the spot 21a of the −1st order light are collected at a substantially point-symmetrical position with the spot 21 of the 0th order light as a center. The direction in which the ± first-order spot 21a and the zero-order spot 21 are aligned is inclined by an angle φ with respect to the direction of the track 19a. This angle φ is the same as the direction in which the ± 20th-order spot 20a of the DVD laser light and the zero-order spot 20 are aligned, and the direction of the diffraction grating 2a relative to the direction parallel to the radial direction of the DVD18 or CD19. This corresponds to θ.

  The direction in which the ± first-order light diffracted by the diffraction grating 2a is emitted is mainly determined by the grating interval p and the grating direction θ of the diffraction grating 2a. Therefore, it is important to determine the combination of the lattice spacing p and the lattice direction θ so that the ± first-order light is arranged as described above.

  FIG. 9A is a diagram showing the arrangement of laser beams incident on the first DVD of the first embodiment, FIG. 9B is a diagram showing the arrangement of laser beams incident on the second DVD, and FIG. FIG. 9C is a diagram showing an array of laser beams incident on a CD having a capacity of 700 MB, and FIG. 9D is a diagram showing an array of laser beams incident on a CD having a capacity of 650 MB. In the first DVD 18a, the zero-order light spot 20 diffracted and generated by the diffraction grating 2a is condensed on the track 18a, and the ± first-order light spot 20a is in a direction parallel to the track 18a of the DVD-RAM. The light is collected with a deviation of angle φ. At this time, the ± first-order spot 20a is shifted from the zero-order spot 20 by about 1.85 μm in the radial direction of the first DVD 18a. The amount of deviation corresponds to about 2.5 track pitches in the first DVD 18a having a track pitch of about 0.74 μm. In the second DVD 18b, the zero-order light spot 20 diffracted and generated by the diffraction grating 2a is collected on the track 18d, and the ± first-order light spot 20a is parallel to the track 18d of the second DVD 18b. On the other hand, the light is condensed by an angle φ. Accordingly, the ± 20th-order light spot 20a is shifted from the 0th-order light spot 20 by about 1.85 μm in the radial direction of the second DVD 18b. The amount of deviation corresponds to about 1.5 track pitch in the second DVD 18b having a track pitch of about 1.23 μm.

  On the other hand, in a CD having a capacity of 700 MB, the spot 21 of the 0th order light diffracted and generated by the diffraction grating 2a is condensed on the track 19a, and the spot 21a of ± 1st order light is focused on the track 19a of the CD having a capacity of 700MB. Condensing light is also shifted by an angle φ with respect to the parallel direction. At this time, the interval between the spot of the zeroth order light and the spot of the ± first order light is proportional to the wavelength. That is, the interval between the zero-order light spot 21 and the ± first-order light spot 21a for CD is 780 nm / 650 nm = 1. Twice as much. Accordingly, the ± first-order spot 21a of the CD is shifted from the spot 21 of the zero-order light by about 1.85 μm × 1.2 = about 2.22 μm in the radial direction of the 700 MB CD. The amount of deviation corresponds to about 1.5 track pitch in a 700 MB CD having a track pitch of about 1.49 μm. In addition, in the 650 MB CD, the zero-order light spot 21 diffracted and generated by the diffraction grating 2a is condensed on the track 19b, and the ± first-order light spot 21a is parallel to the track 19b of the 650 MB CD. On the other hand, the light is condensed by an angle φ. Therefore, the ± first-order light spot 21a is shifted from the zero-order light spot 21 by about 2.22 μm in the radial direction of the CD of 650 MB. The amount of deviation corresponds to about 1.38 track pitch in a 650 MB CD having a track pitch of about 1.60 μm.

  The tracking control method uses the 3-beam differential push-pull method when the difference in the radial position of the DVD 18 or CD 19 between the spot of ± 1st order light and the spot of 0th order light is close to an odd multiple of 0.5. Can be adopted. That is, if the diffraction grating 2a is configured and arranged so that the 0th-order light is incident on the track and the ± 1st-order light is incident between the tracks, tracking control of the three-beam differential push-pull method is performed. be able to. In the first embodiment, the first-order DVD 18a, the second DVD 18b, and the 700-MB capacity CD in the radial direction of the DVD 18 and the CD 19 of the zero-order light spots 20 and 21 and the ± first-order light spots 20a and 21a. The difference in position is about 1.5 track pitch, about 2.5 track pitch, and about 1.5 track pitch, respectively. Since all are close to an odd multiple of 0.5, the tracking control of the 3-beam differential push-pull method can be employed. Further, even in a CD having a capacity of 650 MB, the difference in the radial position of the CD 19 between the spot 21 of the zero order light and the spot 21a of the ± first order light is about 1.38 track pitch, which is an odd multiple of 0.5. Close to the track pitch, tracking control of the three-beam differential push-pull method can be employed. As described above, the diffraction grating 2a of the first embodiment diffracts the laser beam for DVD and the laser beam for CD and diffracts the zero-order light and ±± that are preferably used for tracking control of the three-beam differential push-pull method. Primary light can be generated.

  Actually, the diffraction grating 2a varies such as the refractive index of the material, the grating depth, and the grating interval, the wavelength of the laser beam, the variation when assembling the optical pickup device 17, the variation of the DVD 18 and the CD 19, and so on. Variations occur in the radial distance between the next-light spot 20 and the ± first-order light spot 20a and the radial distance between the zero-order light spot 21 and the ± first-order light spot 21a on the CD 19. If this variation is within about 0.4 times the track pitch, tracking control of the three-beam differential push-pull method can be used. In addition, within about 0.2 times, it is possible to stably perform tracking control even for a poor DVD 18 or CD 19 that is out of specification.

  In this case, it is the first DVD 18a that strictly satisfies the condition of the track pitch. That is, in the first DVD 18a, if the ± first-order light spot 20a is separated from the track on which the zero-order light spot 20 is collected within a range of about 2.50 ± 0.40 track pitch, three beams A differential push-pull method can be used. This corresponds to a radial distance of the DVD 18 of 1.85 ± 0.30 μm, and corresponds to about 1.50 ± 0.24 track pitch in the second DVD 18b. A distance of 1.85 ± 0.30 μm corresponds to 2.22 ± 0.36 μm in CD19. This distance corresponds to approximately 1.49 ± 0.24 track pitch for a CD 19 with a capacity of 700 MB, and approximately 1.39 ± 0.22 track pitch for a CD 19 with a capacity of 650 MB.

  In addition, in the first DVD 18a, if the ± first-order light spot 20a is separated from the track on which the zero-order light spot 20 is collected within a range of about 2.50 ± 0.20 track pitch, it is from the standard. Tracking control can be stably performed even for a bad DVD 18 or CD 19 that is out of place. This corresponds to a distance of 1.85 ± 0.15 μm in the radial direction of the DVD 18, and corresponds to about 1.50 ± 0.12 track pitch in the second DVD 18b. A distance of 1.85 ± 0.15 μm corresponds to 2.22 ± 0.18 μm in CD19. This distance corresponds to approximately 1.49 ± 0.12 track pitch for a CD 19 with a capacity of 700 MB and approximately 1.39 ± 0.11 track pitch for a CD 19 with a capacity of 650 MB.

  Next, the light amounts of 0th-order light and ± 1st-order light generated by the diffraction grating 2a will be described. FIG. 10A is a diagram showing the relationship between the grating depth of the first embodiment and the diffraction efficiency of the zero-order light and ± first-order light, and FIG. 10B is the grating depth of the first embodiment and the zero-order light. It is a figure which shows the relationship between the light quantity ratio of and +/- primary light. FIG. 11A is an enlarged view of the lattice depth of FIG. 10A, and FIG. 11B is an enlarged view of the lattice depth of FIG. 10B. In general, the phase difference ψ of light having a wavelength λ that passes through the diffraction grating 2a having a refractive index n and a grating depth d can be expressed as ψ = {(n−1) × d} / λ. When the phase difference ψ is an even multiple of 0.5, the diffraction is 0%, and the amount of zero-order light is maximized. On the contrary, when the phase difference ψ is an odd multiple of 0.5, the diffraction is 100%, and the light quantity of ± first-order light is maximized. This is graphed with the refractive index of BK7 as the substrate 2b being 1.51, the wavelength of the laser beam for DVD being 650 nm, and the wavelength of the laser beam for CD being 780 nm. a). 10 (a) and 11 (a), η10 is the diffraction efficiency of the 0th-order light for DVD, η11 is the diffraction efficiency of either the + 1st-order light or the −1st-order light for DVD, and η20 is the 0th-order light for CD. The diffraction efficiency of light, η21, is the diffraction efficiency of one of the + 1st order light and the −1st order light for CD. In general, the diffraction efficiencies of the + 1st order light and the −1st order light of the diffraction grating 2a of the first embodiment are the same. η10 is proportional to the light amount I10 of the 0th order light for DVD, η11 is proportional to the light amount I11 of the + 1st order light or −1st order light for DVD, and η20 is proportional to the light amount I20 of the 0th order light for CD. Η21 is proportional to one light quantity I21 of the + 1st order light or the −1st order light for CD. In both the laser beam for DVD and the laser beam for CD, the diffraction efficiency of the 0th-order light and the diffraction efficiency of one of the + 1st-order light and the −1st-order light show opposite trends with respect to the grating depth d. Further, the increase and decrease of the laser beam for DVD is repeated at a shorter cycle than the laser beam for CD because the wavelength is shorter.

  FIGS. 10 (b) and 11 (b) show the light quantity ratio between the 0th order light and the ± 1st order light based on the results of FIGS. 10 (a) and 11 (a). This is the light amount ratio between the 0th order light and the + 1st order light or the −1st order light of the laser beam for DVD, and is the same as the diffraction efficiency ratio η10 / η11. I20 / I21 is the light quantity ratio of the CD laser light to the zero-order light and the + 1st-order light or the −1st-order light of the CD laser light, and is the same as the diffraction efficiency ratio η20 / η21. In the case of the DVD 18, tracking control can be easily performed when the light quantity ratio I10 / I11 between the 0th order light and the + 1st order light or the −1st order light is 10 or more and 20 or less. In the case of the CD 19, tracking control can be easily performed when the light quantity ratio I20 / I21 between the zero-order light and the ± first-order light is 15 or more and 30 or less. 10B and 11B, when BK7 having a refractive index n of 1.51 is used, the above light quantity ratio can be satisfied when the grating depth d is 140 nm or more and 190 nm or less. That is, the diffraction grating 2a can generate light that can be used for tracking control by diffracting DVD laser light, and can also generate light that can be used for tracking control by diffracting laser light for CD. can do. In addition, it is preferable that the light quantity ratio I10 / I11 is 12.5 or more and 17.5 or less and the light quantity ratio I20 / I21 is 20 or more and 25 or less because tracking control becomes easier. In that case, the lattice depth d is 150 nm or more and 170 nm or less.

  Next, calculation of the tracking control signal and the focus control signal will be described. In FIG. 7, the electrical signals for DVD converted into light incident on the light receiving portions A, B, C, D, E, F, G, H, I, J, K, and L are converted into A, B, C, D, and E. , F, G, H, I, J, K, and L. The electric signals for CD that are incident on the light receiving portions a, b, c, d, e, f, g, and h and converted are a, b, c, d, e, f, g, and h. The tracking error signal TES for DVD includes DVD-ROM: TES = ph (A, D) -ph (B, C), DVD ± R / RW, −RAM: TES = {(A + B) − (C + D)} −. Kt × {(E + I + F + J) − (G + K + H + L)}. Here, ph (X, Y) is a voltage obtained by converting the detected phase difference between X and Y, and Kt is a constant determined according to the operation setting. The tracking error signal TES of DVD ± R / RW and −RAM is a tracking control signal by the 3-beam differential push-pull method. That is, a tracking control method using a three-beam differential push-pull method can be used for the first DVD 18a and the second DVD 18b. The DVD-ROM tracking error signal TES is a tracking control signal by a method called a phase difference method.

  The focus error signal FES for DVD is DVD-ROM, DVD ± R / RW: FES = (A + C) − (B + D), DVD-RAM: FES = {(A + C) − (B + D)} + Kt × {(E + I + G + K) − (H + L + F + J)}.

  The tracking error signal TES for CD is CD-R / RW / ROM: TES = {(a + b) − (c + d)} − Kt × {(e + f) − (g + h)}, CD-ROM: ph (a, d ) -Ph (b, c). The tracking error signal TES of the CD-R / RW / ROM is a tracking control signal by the 3-beam differential push-pull method. The tracking error signal TES of the CD-ROM is a tracking control signal called a phase difference method. Usually, a three-beam differential push-pull method that can perform tracking control more stably is used. However, for example, when reproducing a bad disk whose CD-ROM pit height is not within the standard, the tracking error signal TES may not be output successfully by the three-beam differential push-pull method. Even in such a case, the phase difference method can output the tracking error signal TES well, so that it can be used as a preliminary tracking control method. Thus, since it is possible to perform tracking control even when reproducing a poor CD 19 that is out of the standard that cannot be tracked, it is possible to deal with a wider range of CDs 19 as an optical disk device.

  The focus error signal FES for CD is CD-R / RW / ROM: FES = (a + c)-(b + d).

  As described above, the DVD laser light and the CD laser light diffracted into the zero-order light and the ± first-order light by the diffraction grating 2a of the first embodiment are received by the light receiver 10 of the first embodiment. The light enters the light receiving portion 10b of the element 10a. Then, it is converted into a suitable tracking error signal TES and focus error signal FES.

  Next, the overall configuration and manufacturing method of the optical pickup device 17 will be described. FIG. 12 is a perspective view of the base of the first embodiment. The base 12 is made of an alloy material such as Zn alloy or Mg alloy, or a hard resin material. In this Embodiment 1, it is the optical pick-up apparatus 17 corresponding to a thin shape, and the base 12 was also made thin. For the base 12, it is desirable to use an alloy material that is easy to ensure rigidity even if it is thin.

  The base 12 has bearing portions 12a and 12b for attaching to the guide shaft of the optical disc apparatus. The base 12 includes a laser module mounting portion 12c and an objective lens driving device mounting portion 12d, which are large openings, adjacent to each other. The laser module 14 is attached to the laser module attachment portion 12c, and the objective lens drive device 16 is attached to the objective lens drive device attachment portion 12d. A reference surface 12e for attaching the laser module 14 was provided on the outer portion of the opening of the laser module attaching portion 12c. Further, the second light receiver mounting portion 12f, the reflection mirror mounting portion 12g, the collimator lens mounting portion 12h, and the quarter wavelength plate mounting portion 12i are used with reference to the reference surface 12e so that each optical component can be mounted with high accuracy in position and angle. A rising prism mounting portion 12j is provided.

  FIG. 13A is a perspective view of the upper surface side of the coupling member of the first embodiment, and FIG. 13B is a perspective view of the lower surface side. The coupling member 13 has a shape in which an annular portion 13a is provided between substantially symmetrical arm portions 13b. The arm part 13b is in a position shifted from the center part of the annular part 13a. The coupling member 13 is preferably formed of a material that is relatively lightweight and has high precision shape workability, heat dissipation, and the like. For example, Zn, Zn alloy, Al, Al alloy, Ti, Ti alloy, and the like are preferable. Used for. In the first embodiment, considering the cost and the like, the coupling member 13 is configured by Zn die casting.

  The left and right arms 13b are provided with a reference surface 13c and a V-groove 13d at the tip. The reference surface 13c and the V-groove 13d serve as a reference when assembling the laser module 14 or attaching the laser module 14 to the base 12. The surface of the annular portion 13a is in a direction substantially perpendicular to the reference surface 13c, and the reference surface 13c is the surface of the arm portion 13b on the side close to the central portion of the annular portion 13a. The surface of the annular portion 13a is also parallel to the axis of the V groove 13d.

  A contact surface 13f for fixing the plate 1c of the laser light source 1 is provided on the lower surface side of both the arm portions 13b and the annular portion 13a connected to the arm portions 13b. Each contact surface 13f was provided with a groove 13k and a recess 13l continuous to the groove 13k. A cream solder for fixing the plate 1c is disposed in the recess 13l, and flows into the plate 1c via the groove 13k to fix the plate 1c and the contact surface 13f of the coupling member 13. In the first embodiment, the recess 13l is disposed on the arm portion 13b side, and the groove 13k is disposed on the annular portion 13a side.

  The main part of the laser light source 1 is accommodated in the space 13e of the annular portion 13a. As a part of the annular portion 13a, the arms 13b were directly connected to ensure the strength of the coupling member 13. A lead 1d of the laser light source 1 is disposed at this connecting portion. Since the lead 1d is thin, it does not interfere with this connecting portion.

  On the other hand, the through-hole 13g was provided in the side surface on the opposite side to the arm part 13b of the annular part 13a, and the convex part 13h was provided in the circumference | surroundings of the through-hole 13g in the outer side surface part of the annular part 13a. The surface of the convex portion 13h was parallel to the reference surface 13c. The diffraction element 2 is fixed to the convex portion 13h. Laser light emitted from the laser light source 1 through the through hole 13g enters the diffraction element 2. Moreover, the wall part 13m extended from the lower surface side of the convex part 13h to the opposite side to the arm part 13b was provided, and the through-hole 13n was provided in the wall part 13m. The through-hole 13n is a hole for inserting a diffraction element holding member of a diffraction element assembling apparatus that arranges the diffraction element 2 and performs position adjustment and angle adjustment.

  Convex portions 13i are provided on both sides of the convex portion 13h. The plane created by the surface of the convex portion 13i is parallel to the reference surface 13c and is farther from the reference surface 13c than the convex portion 13h. The beam splitter 3 is disposed on the convex portion 13i. The beam splitter 3 is fixed by a wall portion 13m. Further, the wall portion 13m, which is the annular portion 13a on one side of the convex portion 13h and the convex portion 13i, is extended to provide a U-shaped contact surface 13j. The contact surface 13j is formed in a direction perpendicular to the reference surface 13c and perpendicular to the plane formed by connecting the axes of the V-grooves 13d on both sides. The light receiver 10 is fixed to the contact surface 13j. The light receiving element 10a of the light receiver 10 is disposed at the center of the U-shape of the contact surface 13j.

  FIG. 14 is a configuration diagram of the laser module according to the first embodiment. The laser module 14 is configured by holding the laser light source 1, the diffraction element 2, the beam splitter 3, the detection lens 9, and the light receiver 10 as an integrated unit on the coupling member 13. In the laser light source 1, the plate 1c is fixed to the contact surface 13f. Fixing is performed by welding or bonding with an adhesive. It is preferable to weld using a metal such as cream solder because heat generated by the laser light source 1 can be easily released to the coupling member 13 because of high thermal conductivity. As the adhesive, a thermosetting adhesive, an anaerobic adhesive, or the like is used. When fixing, the position adjustment in the X direction and the Z direction and the angle adjustment in the θy direction in the in-plane direction of the plate 1c and the contact surface 13f are performed. Since the plate 1c having a large area is fixed to the coupling member 13, good and stable assembly accuracy can be realized.

  The diffraction element 2 is fixed to the convex portion 13h by adhesion. The beam splitter 3 is fixed to the convex portion 13i by adhesion. An adhesive such as an ultraviolet curable adhesive, a thermosetting adhesive, or an anaerobic adhesive is used for bonding the diffraction element 2 and the beam splitter 3. The diffraction element 2 performs position adjustment in the X direction and Y direction and angle adjustment in the θz direction. The adjustment in the X direction and the Y direction may be omitted as long as the assembly apparatus has a high accuracy with which the diffractive element 2 is initially arranged on the coupling member 13, but it is preferable to adjust the position in the Y direction. A laser beam for DVD and a laser beam for CD are emitted sequentially or simultaneously, and a straight line connecting the zero-order light for DVD and the zero-order light for CD and either ± 1 for DVD or CD The diffraction element 2 is adjusted by rotating it in the θz direction so that the straight line connecting the next light becomes a predetermined angle. This adjustment is to adjust the direction in which the emission position of the laser beam for DVD and the emission position of the laser beam for CD are aligned and the direction in which the diffraction grating 2a of the diffraction element 2 is aligned. The laser beam and the CD laser beam can be incident on the predetermined light detection unit 10b of the light receiver 10, respectively. The beam splitter 3 adjusts the position in the X direction. Further, adjustment in the Z direction may be performed.

  The detection lens 9 is fixed to a detection lens holder 9a fixed to the light receiver 10 in advance. The detection lens 9 is applied to the detection lens holder 9a, and the position adjustment in the Y and Z directions and the angle adjustment in the θx direction between the detection lens 9 and the light receiving element 10a of the light receiver 10 are performed. Further, the detection lens holder 9 a to which the detection lens 9 and the light receiver 10 are attached is fixed to the contact surface 13 j of the coupling member 13. Position adjustment in the X direction, Y direction, and Z direction and angle adjustment in the θx direction, θy direction, and θz direction are performed on the coupling member 13. For fixing the light receiver 10 and the detection lens holder 9a, fixing the detection lens holder 9a and the detection lens 9, and fixing the detection lens holder 9a and the coupling member 13, respectively, an ultraviolet curable adhesive and a thermosetting adhesive Adhesives such as anaerobic adhesives are used.

  In order to correspond to the thin optical pickup device 17, the thickness of the coupling member 13 is also thin. However, the distance between the optical components fixed to the coupling member 13 can be reduced. Assume that each optical component of the laser module 14 is fixed to the base 12 instead of the coupling member 13. Since the base 12 is thin, it tends to be easily deformed by stresses such as temperature and changes with time. For this reason, positional deviation or angular deviation between the optical components may occur. However, since the coupling member 13 is small, it is difficult to deform due to stress such as temperature and change with time. That is, a laser light source 1 that emits laser light, a diffraction element 2 including a diffraction grating 2a that generates tracking control light, a beam splitter 3 that separates forward light and return light, and focus control light The detection lens 9 that generates the light and the light receiver 10 that receives the laser light are fixed to the small coupling member 13 as an integrated unit, thereby preventing the occurrence of positional deviation and angular deviation between the optical components. Is obtained. Therefore, stable and high quality recording / reproducing characteristics can be obtained. In addition, the optical pickup device can be thinned.

  In the first embodiment, in the objective lens driving device 16, the lens holder 15 to which the objective lens 8 is fixed is elastically supported on the apparatus main body by a support member. A focus coil and a tracking coil are fixed to the lens holder 15. A magnet is fixed to the apparatus main body. The objective lens driving device 16 generates an electromagnetic force between the objective coil 8 and the magnet by passing a current through the focus coil or the tracking coil, and moves the objective lens 8 mounted on the lens holder 15 in the focus direction or the tracking direction. The drive current passed through the focus coil or tracking coil is controlled based on the focus error signal FES or tracking error signal TES generated from the electrical signal output by converting the amount of laser light incident on the light receiver 10.

  As shown in FIG. 2, the optical pickup device 17 of the first embodiment is configured by attaching various components to the base 12 directly or via other components. In the laser module 14, the reference surface 13 c of the coupling member 13 is fixed to the reference surface 12 e of the base 12. The main part of the laser module 14 is accommodated in the laser module mounting part 12c. The laser module 14 is adjusted in position and angle in the plane of the reference plane 13c and the reference plane 12e. For fixing, an adhesive such as an ultraviolet curable adhesive, a thermosetting adhesive, or an anaerobic adhesive is used.

  The main body of the objective lens driving device 16 on which the objective lens 8 is mounted is fixed to the base 12. The objective lens driving device 16 is accommodated in the objective lens driving device mounting portion 12 d of the base 12. When the objective lens driving device 16 is fixed to the base 12, position adjustment and angle adjustment of the objective lens 8 are performed. For fixing, an adhesive such as an ultraviolet curable adhesive, a thermosetting adhesive, or an anaerobic adhesive is used. The reflecting mirror 4 is attached to the reflecting mirror attaching portion 12g of the base 12, the collimating lens 5 is attached to the collimating lens attaching portion 12h, the quarter wavelength plate 6 is attached to the quarter wavelength plate attaching portion 12i, and the rising prism 7 is The second light receiver 11 is directly fixed to the second light receiver mounting portion 12f at the rising prism mounting portion 12j. For fixing, an adhesive such as an ultraviolet curable adhesive, a thermosetting adhesive, or an anaerobic adhesive is used. The collimating lens 5 may be fastened using a leaf spring or the like while being movable.

  In order to assemble the optical pickup device 17, first, the reflecting mirror 4, the quarter wavelength plate 6, and the rising prism 7 are respectively connected to the reflecting mirror mounting portion 12 g, the quarter wavelength plate mounting portion 12 i of the base 12, and the rising prism. Fix to the mounting portion 12j or finely adjust the position and angle to fix. Further, the collimating lens 5 is attached to the base 12. The collimating lens 5 is attached to be movable in the optical axis direction. Next, the laser module 14 is attached to the base 12. Then, the reference surface 13c of the coupling member 13 is brought into close contact with the reference surface 12e of the base 12, and the position adjustment in the X direction and the Y direction and the angle adjustment in the θz direction are performed. Laser light is emitted and position adjustment in the X and Y directions is performed so as to pass through the center of the collimating lens 5. Further, the angle adjustment in the θz direction is performed so that the zero-order light and the ± first-order light are incident on the tracks of the DVD 18 and the CD 19 at a predetermined angle φ. Then, the laser module 14 is fixed to the base 12. Next, the objective lens driving device 16 is attached to the objective lens driving device attaching portion 12d of the base 12. Laser light is emitted to adjust the angle of the objective lens 8 in the θx direction and θy direction by moving the entire objective lens driving device 16. Next, position adjustment of the objective lens 8 in the X and Y directions is performed by moving the entire objective lens driving device 16 so that the laser beam passes through the center of the objective lens 8, and the objective lens driving device 16 is fixed to the base 12. . Next, the position of the collimating lens 5 is adjusted in the optical axis direction (X direction). The second light receiver 11 is separately fixed to the second light receiver mounting portion 12 f of the base 12.

  The laser module 14 may form a contact surface for attaching the second light receiver 11 at a predetermined position of the coupling member 13, and the second light receiver 11 may be fixed to the contact surface. Since the distance from the beam splitter 3 can be shortened, all the light emitted from the beam splitter 3 can be incident on the second light receiver 11, and the generation of stray light can be suppressed. Further, since the distance from the beam splitter 3 can be shortened, the spectroscopic pickup device 17 can be downsized. The second light receiver mounting portion 12f provided on the base 12 can be omitted.

  In the first embodiment, the diffraction grating 2a is provided on the surface of the substrate 2b as a part of the diffraction element 2, but may be provided on the surface of the beam splitter 3 facing the laser light source 1. By doing so, since the diffraction element 2 can be eliminated, the number of parts can be reduced, and the optical pickup device 17 can be made cheaper. Further, the optical pickup device 17 can be reduced in size by the amount that the diffraction element 2 is eliminated.

  Next, the optical path will be described. In FIG. 1, a laser beam for DVD and a laser beam for CD are emitted from a laser light source 1 toward a DVD 18 and a CD 19, respectively. The laser beam for DVD and the laser beam for CD emitted from the laser light source 1 enter the diffraction element 2. The diffraction grating 2a of the diffraction element 2 diffracts the DVD laser beam and the CD laser beam to generate 0th order light and ± 1st order light used for tracking control. Next, the laser beam for DVD and the laser beam for CD are incident on the beam splitter 3, and most of them are emitted as they are toward the DVD 18 and CD 19. Part of the light is reflected by the polarization separation film 3b on the inclined surface 3a, enters the second light receiver 11, and is converted into an electric signal. The converted electrical signal output from the second light receiver 11 is used for controlling the amount of laser light emitted from the laser light source 1. The laser beam for DVD and the laser beam for CD emitted from the beam splitter 3 toward the DVD 18 and the CD 19 are reflected by the reflection mirror 4, bent on the optical path, and incident on the collimating lens 5. The laser beam for DVD and the laser beam for CD, which have been divergent light, are converted into substantially parallel light by the collimator lens 5 and enter the quarter-wave plate 6. The laser beam for DVD is converted from P-polarized light to circularly-polarized light by the quarter wavelength plate 6. The laser beam for CD passes through the quarter-wave plate 6 with P polarization. The laser beam for DVD and the laser beam for CD are incident on the rising prism 7, reflected twice inside, and then emitted in a direction perpendicular to the DVD 18 and CD 19. At that time, the width of the light flux in the direction perpendicular to the DVD 18 and CD 19 incident on the rising prism 7 is expanded and emitted from the rising prism 7. The laser beam for DVD and the laser beam for CD emitted from the rising prism 7 are incident on the objective lens 8, converted into focused light, and focused on the information recording surfaces of the DVD 18 and CD 19, respectively.

  The DVD laser light and the CD laser light reflected by the DVD 18 and CD 19 are converted into parallel light by the objective lens 8, enter the rising prism 7, and converted into a direction substantially parallel to the DVD 18 and CD 19. . The laser beam for DVD is converted from circularly polarized light to S polarized light by the quarter wavelength plate 6. The laser beam for CD passes through the quarter-wave plate 6 with P polarization. The laser beam for DVD and the laser beam for CD, which were parallel light, are converted into focused light by the collimator lens 5, reflected by the reflection mirror 4, and incident on the beam splitter 3. The laser beam for DVD and the laser beam for CD reflected by the polarization separation film 3b on the inclined surface 3a of the beam splitter 3 are incident on the detection lens 9. The detection lens 9 has different focal positions on two orthogonal cross sections including the optical axis, and generates DVD laser light and CD laser light used for focus control. The DVD laser light and the CD laser light emitted from the detection lens 9 enter the light receiver 10. The light receiver 10 receives the laser beam for DVD and the laser beam for CD by the light receiving unit 10b of the light receiving element 10a, converts the received light amount into an electrical signal, and outputs it. The output electric signal is calculated as a tracking error signal TES and a focus error signal FES and used for tracking control and focus control of the objective lens 8.

  Note that the temperature of the laser light source 1 rises as it continues to emit light at a high output. As the temperature rises, the polarization plane of the laser light emitted from the laser light source 1 that was only P-polarized light rotates to have an S-polarized component. As a result, the amount of light incident on the second light receiver 11 may fluctuate. Removing the S-polarized light component incident on the second light receiver 11 is one effective means for suppressing this phenomenon. For this purpose, a polarizing film may be disposed between the beam splitter 3 and the second light receiver 11, or a prism having a polarization separation film that transmits P-polarized light and reflects S-polarized light may be disposed on the inner slope. good.

  In the optical pickup device 17 according to the first embodiment, the diffraction grating 2a is commonly used for DVD and CD, and the first DVD 18a has two separate tracks and three for the track on which the zero-order light is incident. In the second DVD 18b and CD 19, in the middle of the separated track, the ± first-order light is incident substantially symmetrically about the zero-order light in the middle of the one-separated track and the two-separated track. The diffraction grating 2a has a combination of the grating interval p and the grating direction θ. Since the distance between the zero-order light and the ± first-order light of the laser light diffracted by the diffraction grating 2a is proportional to the wavelength, the CD laser light is 1.2 times longer than the DVD laser light. Become. If the distance in the radial direction between the zero-order light and the ± first-order light on the DVD 18 is about 1.85 μm, the distance in the radial direction on the CD 19 is about 2.22 μm. This distance corresponds to about 2.5 track pitches for the first DVD 18a, about 1.5 track pitches for the second DVD 18b, and about 1.39 track pitches or about 1.49 track pitches for CD19. If the track pitch is close to an odd multiple of 0.5, a three-beam differential push-pull method, which is one of tracking control methods, can be employed. Therefore, appropriate tracking control can be performed for both the DVD 18 and the CD 19. For this reason, even if an inexpensive diffraction element 2 is used, at least one of information recording and reproduction can be performed on the DVD 18 and the CD 19 with sufficient characteristics.

(Embodiment 2)
The second embodiment will be described with reference to the drawings. FIG. 15 is a configuration diagram of an optical system of the optical pickup device according to the second embodiment. The optical pickup device according to the second embodiment has a configuration in which the detection lens 9 and the beam splitter 3 of the optical pickup device according to the first embodiment are eliminated and an integrated prism 24 is disposed instead. Since the configuration other than the detection lens 9 and the beam splitter 3 is the same as that of the first embodiment, the description of the first embodiment is cited.

  FIG. 16 is a configuration diagram of the integrated prism of the second embodiment. The integrated prism 24 is an optical element for directing the DVD laser light reflected by the DVD 18 and the CD laser light reflected by the CD 19 to the light receiver 10, and the DVD laser light and the CD light directed to the light receiver 10. A focus error generating element for giving a focus error to the laser beam. The integrated prism 24 is made of optical glass or the like, and includes inclined surfaces 24a and 24b. A polarization separation film 24c and a total reflection film 24f are formed on the inclined surface 24a. The polarization separation film 24c is composed of a multilayer dielectric film. The polarization separation film 24c is arranged so that the DVD laser light and the CD laser light emitted from the laser light source 1 cross the optical path toward the DVD 18 and CD 19. The polarization separation film 24c is emitted from the laser light source 1 and transmits most of the DVD laser light and CD laser light, which are P-polarized light, and reflects a part thereof. In the second embodiment, about 85% is transmitted. The transmitted light is directed to the DVD 18 and CD 19, and the reflected light is directed to the second light receiver 11. The polarization separation film 24c reflects 95% or more of the DVD laser light reflected by the DVD 18 and converted to S-polarized light. Further, it reflects about 15% of the laser beam for CD that is still P-polarized light reflected by CD19. The total reflection film 24f is composed of a metal film or a multilayer dielectric film. The total reflection film 24f is formed on the optical path of the DVD laser light and the CD laser light reflected by the reflection mirror 24d toward the light receiver 10.

  A diffractive reflection mirror 24d is formed on the slope 24b of the integrated prism 24. The reflection mirror 24 is a diffraction grating in which a total reflection film 24e is formed on the unevenness formed in parallel on the inclined surface 24b. The total reflection film 24e is composed of a metal film or a multilayer dielectric film. The diffraction grating emits diffracted light in a direction perpendicular to the length direction of the unevenness. By curving the unevenness, the emission direction of the diffracted light in the diffraction grating plane can be changed. Further, the wider the interval between the concave and convex arrays, the light is emitted in a direction closer to the normal direction of the diffraction grating surface. By utilizing the fact that the direction in which the diffracted light is emitted can be controlled by this, the reflection mirror 24d is configured such that the focal lengths are different between two orthogonal sections including the optical axis. Accordingly, the reflection mirror 24d is a focus error generating element that gives a focus error to the DVD laser light and the CD laser light that travel toward the light receiver 10.

  The optical path will be described. The laser beam for DVD and the laser beam for CD emitted from the laser light source 1 are diffracted into zero-order light and ± first-order light by the diffraction grating 2 a of the diffraction element 2 and enter the integrated prism 24. Except for a part reflected toward the second light receiver 11 by the polarization separation film 24b on the inclined surface 24a, most of the laser light for DVD and the laser light for CD are transmitted to the DVD 18 and CD 19. The laser beam for DVD and the laser beam for CD pass through the reflection mirror 4, the collimating lens 5, the quarter wavelength plate 6, the rising prism 7, and the objective lens 8 and reach the DVD 18 and CD 19. The laser beam for DVD and the laser beam for CD are reflected by the DVD 18 and CD 19 and pass through the objective lens 8, the rising prism 7, the quarter wavelength plate 6, the collimator lens 5, and the reflecting mirror 24, and the integrated prism 24. Is incident on. The process from the reflection mirror 4 to the DVD 18 and CD 19 and back to the reflection mirror 4 is the same as that described in the first embodiment. The DVD laser light and the CD laser light incident on the integrated prism 24 are reflected by the polarization separation film 24c on the inclined surface 24a and travel toward the diffractive reflection mirror 24d on the inclined surface 24b. The laser beam for DVD and the laser beam for CD to which the focus error is given by the reflection mirror 24d are reflected and incident on the total reflection film 24f on the inclined surface 24a, and further reflected and directed to the light receiver 10. The laser beam for DVD and the laser beam for CD incident on the light receiving unit 10b of the light receiving element 10a of the light receiver 10 are converted into electric signals and output, respectively, for tracking control and focus control as in the first embodiment. Used.

  In the optical pickup device of the second embodiment, the diffraction grating 2a is shared for DVD and CD, and a three-beam differential push-pull method, which is one of tracking control methods, can be adopted. Therefore, appropriate tracking control can be performed for both the DVD 18 and the CD 19. For this reason, even if an inexpensive diffraction element 2 is used, at least one of information recording and reproduction can be performed on the DVD 18 and the CD 19 with sufficient characteristics. Further, by forming the reflection mirror 24d on the slope 24b inside the integrated prism 24, it is not necessary to arrange the detection lens 9. Therefore, the optical pickup device 17 can be made smaller.

  In addition, it is good also as following structures. The function of the quarter-wave plate 6 is to convert DVD laser light and CD laser light emitted from the laser light source 1 from P-polarized light to circularly-polarized light, and to reflect the DVD laser light reflected by the DVD 18 and CD 19. The laser beam for CD is changed so as to be converted from circularly polarized light to S polarized light. Further, the total reflection film 24f on the inclined surface 24a of the integrated prism 24 is abolished, and the entire surface is used as the polarization separation film 24c. The characteristics of the polarization separation film 24c are converted so that most of the P-polarized light is transmitted and most of the S-polarized light is reflected in both the DVD laser light and the CD laser light. Even in this case, the diffraction grating 2a can be commonly used for DVD and CD, and a three-beam differential push-pull method, which is one of tracking control methods, can be employed. Therefore, appropriate tracking control can be performed for both the DVD 18 and the CD 19. For this reason, even if an inexpensive diffraction element 2 is used, at least one of information recording and reproduction can be performed on the DVD 18 and the CD 19 with sufficient characteristics. Further, by forming the reflection mirror 24d on the slope 24b inside the integrated prism 24, it is not necessary to arrange the detection lens 9. Therefore, the optical pickup device can be made smaller.

(Embodiment 3)
The third embodiment will be described with reference to the drawings. FIG. 17A is a top configuration diagram of the optical pickup module of the third embodiment, FIG. 17B is a bottom configuration diagram, and FIG. 18 is a configuration diagram of the optical disc apparatus of the third embodiment. The third embodiment is an optical disk device provided with the optical pickup device 30 of the first or second embodiment.

  In FIG. 17, the drive mechanism of the optical disk device 47 including a rotation drive unit that rotates and drives the DVD 18 and CD 19 and a moving unit that moves the optical pickup device 30 closer to and away from the rotation drive unit is referred to as an optical pickup module 40. The base 31 forms a framework of the optical pickup module 40, and the optical pickup module 40 is configured by disposing each component directly or indirectly on the base 31.

  The rotation drive unit includes a spindle motor 32 having a turntable 32a on which the DVD 18 and CD 19 are placed. The spindle motor 32 is fixed to the base 31. The spindle motor 32 generates a rotational driving force that rotates the DVD 18 and the CD 19.

  The moving unit includes a feed motor 33, a screw shaft 34, and guide shafts 35 and 36. The feed motor 33 is fixed to the base 31. The feed motor 33 generates a rotational driving force necessary for the optical pickup device 30 to move between the inner periphery and the outer periphery of the DVD 18 or CD 19. A stepping motor, a DC motor, or the like is used as the feed motor 33. The screw shaft 34 has a groove formed in a spiral shape, and is connected to the feed motor 33 directly or via several stages of gears. In the third embodiment, it is connected to the feed motor 33 through a gear. The guide shafts 35 and 36 are fixed to the base 31 via holding members at both ends. The guide shafts 35 and 36 support the optical pickup device 30 movably. The optical pickup device 30 includes a rack 37 having guide teeth that mesh with the grooves of the screw shaft 34. Since the rack 37 converts the rotational driving force of the feed motor 33 transmitted to the screw shaft 34 into a linear driving force, the optical pickup device 30 can move between the inner periphery and the outer periphery of the DVD 18 or CD 19.

  Note that the rotation driving unit is not limited to the configuration described in the third embodiment as long as it can rotate the DVD 18 or the CD 19 at a predetermined rotation speed. The moving unit is not limited to the configuration described in the third embodiment as long as it can move the optical pickup device 30 to a predetermined position between the inner periphery and the outer periphery of the DVD 18 or CD 19.

  The optical pickup device 30 is obtained by attaching a cover 29 to the configuration of the optical pickup device described in the first embodiment or the second embodiment. The optical pickup device 30 can perform appropriate tracking control for both the DVD 18 and the CD 19 by using the diffraction grating 2a shared by the DVD and the CD. For this reason, even if an inexpensive diffraction element 2 is used, at least one of information recording and reproduction can be performed on the DVD 18 and the CD 19 with sufficient characteristics. The inclination of the guide shafts 35 and 36 is adjusted by an adjustment mechanism that constitutes a holding member so that the laser light emitted from the objective lens 8 of the optical pickup device 30 is incident on the DVD 18 or CD 19 at a right angle.

  The FPC 38 electrically connects the optical pickup device 30 and the main body of the optical disk device 47. The FPC 38 is a conductive wire for supplying electric power to the optical pickup device 30 from the main body side of the optical disk device 47 and sending an electric signal, and also for sending an electric signal from the optical pickup device 30 to the main body side of the optical disk device 47. It is also a conductive wire.

  The cover 39 has an opening to expose the objective lens 8 of the optical pickup device 30 and the turntable 32a of the spindle motor 32. Furthermore, in the case of the third embodiment, the feed motor 33 and the guide shaft 36 are also exposed so that the thickness of the optical pickup module 40 is reduced by the thickness of the cover 39.

  In FIG. 18, the housing 41 is configured by combining an upper housing 41a and a lower housing 41b and fixing them together using screws or the like. The tray 42 is provided in the casing 41 so as to be able to appear and retract. The tray 42 arranges the optical pickup module 40 from the lower surface side. The tray 42 has an opening and exposes at least a part of the objective lens 8, the turntable 32 a of the spindle motor 32, and the cover 39. The bezel 43 is provided on the front end surface of the tray 42 and is configured to close the entrance / exit of the tray 42 when the tray 42 is stored in the housing 41. The bezel 43 is provided with an eject switch 44. When the eject switch 44 is pressed, the engagement between the housing 41 and the tray 42 is released, and the tray 42 can be brought into and out of the housing 41. The rails 45 are slidably attached to both sides of the tray 42 and the housing 41, respectively. There is a circuit board (not shown) inside the housing 41 and the tray 42, and a signal processing system IC, a power circuit, and the like are mounted. The external connector 46 is connected to a power / signal line provided in an electronic device such as a computer. Then, electric power is supplied into the optical disc device 47 via the external connector 46, an electric signal from the outside is guided into the optical disc device 47, or an electric signal generated by the optical disc device 47 is sent to an electronic device or the like. To do.

  As described above, the optical pickup device 30 mounted on the optical disk device 47 of the third embodiment uses the diffraction grating 2a shared for DVD and CD, and is suitable for both DVD18 and CD19. Tracking control can be performed. For this reason, even if an inexpensive diffraction element 2 is used, at least one of information recording and reproduction can be performed on the DVD 18 and the CD 19 with sufficient characteristics. Therefore, the optical disk device 47 according to the third embodiment can record and / or reproduce information with respect to the DVD 18 and the CD 19 with sufficient characteristics and can be inexpensive.

  As described above, the optical pickup device and the optical disc device of the present invention can perform recording and / or reproduction of information on DVD and CD with sufficient characteristics even when an inexpensive diffraction element is used. For this reason, it is preferably installed in electronic devices such as personal computers and notebook computers that are particularly required to be inexpensive.

Configuration diagram of an optical system of the optical pickup device of the first embodiment Configuration diagram of optical pickup device according to Embodiment 1 Configuration diagram of laser light source according to the first embodiment (A) The perspective block diagram of the diffraction grating of this Embodiment 1, (b) Sectional drawing by the plane A, (c) Bottom view Configuration diagram of beam splitter of Embodiment 1 (A) The figure which shows the function of the detection lens of this Embodiment 1, (b) The figure which shows the condensing spot shape on the light-receiving part of the light receiving element of a light receiver when DVD and CD are near, (c) DVD, The figure which shows the condensing spot shape on the light-receiving part of the light receiving element of a light receiver when CD is far Arrangement of the light receiving portion of the light receiving element of the light receiver of the first embodiment The figure which shows the arrangement | sequence on DVD and CD of the laser beam diffracted by the diffraction grating of this Embodiment 1 (A) The figure which shows the arrangement | sequence of the laser beam which injected into 1st DVD of this Embodiment 1, (b) The figure which shows the arrangement | sequence of the laser beam which injected into 2nd DVD, (c) CD of 700MB capacity | capacitance (D) The figure which shows the arrangement | sequence of the laser beam which injected into 650MB capacity | capacitance CD (A) A diagram showing the relationship between the grating depth of this Embodiment 1 and the diffraction efficiencies of 0th order light and ± 1st order light, (b) the grating depth of this Embodiment 1 and the relationship between 0th order light and ± 1st order light Diagram showing the relationship of light intensity ratio (A) The figure which expanded the lattice depth of Fig.10 (a), (b) The figure which expanded the lattice depth of FIG.10 (b) The perspective view of the base of this Embodiment 1 (A) The perspective view of the upper surface side of the coupling member of this Embodiment 1, (b) The perspective view of the lower surface side Configuration diagram of laser module according to the first embodiment Configuration diagram of the optical system of the optical pickup device of the second embodiment Configuration diagram of integrated prism of Embodiment 2 (A) Top view configuration diagram of optical pickup module of Embodiment 3, (b) Bottom view configuration diagram Configuration diagram of optical disk apparatus according to Embodiment 3 Configuration diagram of optical system of conventional optical pickup device (A) Perspective view of a conventional diffractive element, (b) Cross-sectional view on plane A, (c) Top view, (d) Bottom view (A) The figure which shows the arrangement | sequence of the laser beam which injected into DVD-R / RW, (b) The figure which shows the arrangement | sequence of the laser beam which injected into CD

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 1a Light emitting element 1b Submount 1c Plate 1d Lead 1e Protection member 2 Diffraction element 2a Diffraction grating 3 Beam splitter 3a Slope 3b Polarization separation film 4 Reflecting mirror 5 Collimating lens 6 1/4 wavelength plate 7 Rising prism 8 Objective lens DESCRIPTION OF SYMBOLS 9 Detection lens 10 Light receiver 10a Light receiving element 10b Light receiving part 11 2nd light receiver 12 Base 12a, 12b Bearing part 12c Laser module attachment part 12d Objective lens drive unit attachment part 12e Reference surface 12f 2nd light receiver attachment part 12g Reflective mirror Mounting portion 12h Collimating lens mounting portion 12i 1/4 wavelength plate mounting portion 12j Rising prism mounting portion 13 Connecting member 13a Annular portion 13b Arm portion 13c Reference surface 13d V-groove 13e Space portion 13f, 13j Abutting surface 13g , 13n Through-hole 13h, 13i Convex part 13k Groove 13l Concave part 13m Wall part 14 Laser module 15 Lens holder 16 Objective lens driving device 17 Optical pickup device 18 DVD
18a First DVD
18b Second DVD
18c, 18d track 19 CD
19a, 19b Track 20, 20a, 21, 21a Spot 22, 23 In-focus position 24 Integrated prism 24a, 24b Slope 24c Polarization separation film 24d Reflection mirror 24e, 24f Total reflection film 30 Optical pickup device 30a Cover 31 Base 32 Spindle motor 32a Turntable 33 Feed motor 34 Screw shaft 35, 36 Guide shaft 37 Rack 38 FPC
39 Cover 40 Optical Pickup Module 41 Case 41a Upper Case 41b Lower Case 42 Tray 43 Bezel 44 Eject Switch 45 Rail 46 External Connector 47 Optical Disc Device

Claims (15)

A laser light source that emits a laser beam that irradiates a first DVD having a first track pitch and a second DVD that has a second track pitch, and a laser beam that irradiates a CD;
A diffraction grating that diffracts laser light emitted from the laser light source into zero-order light and ± first-order light to generate laser light used for tracking control,
The diffraction grating is intermediate between a track separated by two and three separated in the first DVD with respect to a track on which the 0th-order light is incident, and 1 in the second DVD and the CD. In the middle between two separate tracks and two separate tracks, there is a combination of a lattice interval and a lattice direction so that the ± first-order light is incident substantially symmetrically about the zero-order light. An optical pickup device characterized by the above. 2. The optical pickup device according to claim 1, wherein the first track pitch is about 0.74 [mu] m, and the second track pitch is about 1.23 [mu] m. 2. The position where the ± first-order light is incident on the first DVD is a position separated from the zero-order light within a range of 2.50 ± 0.40 track pitch. Optical pickup device. 2. The position where the ± first-order light is incident on the second DVD is a position separated from the zero-order light within a range of 1.50 ± 0.24 track pitch. Optical pickup device. The position at which the ± first-order light is incident on the CD having a capacity of 700 MB is a position separated from the zero-order light by a range of 1.49 ± 0.24 track pitch. 1. The optical pickup device according to 1. The position where the ± first-order light is incident on the CD having a capacity of 650 MB is a position distant from the zero-order light within a range of 1.39 ± 0.22 track pitch. 1. The optical pickup device according to 1. The position where the ± first-order light is incident on the first and second DVDs is such that the radial distance of the first and second DVDs relative to the zero-order light is 1.85 ± 0.30 μm. The optical pickup device according to claim 1, wherein the optical pickup device is at a position separated from each other. The position where the ± first-order light is incident on the CD is a position where the radial distance of the CD is away from the zero-order light in a range of 2.22 ± 0.36 μm. Item 5. The optical pickup device according to Item 1. In the first and second DVDs, the diffraction grating has a ratio I10 / I11 of the light amount I10 of the 0th order light and the light amount I11 of the + 1st order light or the −1st order light to 10 or more and 20 or less, and 0 in the CD. A combination of a refractive index and a grating depth is set such that a ratio I20 / I21 of the light quantity I20 of the secondary light and the light quantity I21 of the + 1st-order light or -1st-order light is 15 or more and 30 or less. Item 5. The optical pickup device according to Item 1. A light receiver for receiving the laser light reflected by the first and second DVDs and the laser light reflected by the CD;
An optical element for directing the laser light reflected by the first and second DVDs and the laser light reflected by the CD to the light receiver,
The optical pickup device according to claim 1, wherein the diffraction grating is provided on a surface of the optical element facing the laser light source. A light receiver for receiving the laser light reflected by the first and second DVDs and the laser light reflected by the CD;
An optical element disposed between the diffraction grating and the first, second DVD, or CD, and directing laser light reflected by the first, second DVD, and the CD to the light receiver;
And a focus error generating element that gives a focus error to the laser beams reflected by the first and second DVDs and the CD directed to the light receiver by the optical element. 1. The optical pickup device according to 1. 12. The lens according to claim 11, wherein the focus error generating element is a lens having a different focal length in two cross sections orthogonal to each other including the optical axis, which is disposed between the optical element and the light receiver. Optical pickup device. 12. The diffractive reflection mirror, wherein the focus error generating element is a diffractive reflection mirror provided on an inclined surface of the optical element and having different focal lengths in two orthogonal sections including the optical axis. Optical pickup device. 12. A coupling member that holds the laser light source, the diffraction grating, the light receiver, the optical element, and the focus error generation element as an integral unit and is fixed to a base. Optical pickup device. A laser light source that emits a laser beam that irradiates a first DVD having a first track pitch and a second DVD that has a second track pitch, and a laser beam that irradiates a CD;
A diffraction grating that diffracts laser light emitted from the laser light source into zero-order light and ± first-order light to generate laser light used for tracking control,
The diffraction grating is intermediate between a track separated by two and three separated in the first DVD with respect to a track on which the 0th-order light is incident, and 1 in the second DVD and the CD. Light having a combination of a lattice interval and a lattice direction such that the ± first-order light is incident substantially symmetrically with respect to the zero-order light in the middle between two separate tracks and two separate tracks An optical disc apparatus comprising a pickup device.

Images