JP2014175030A - Optical integrated element, optical head device, and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical integrated element which is easy to assemble and is small-sized, an optical head device, and an optical disk device.SOLUTION: An optical head device 1 includes a light source unit 21, an objective lens 26, an objective lens actuator 28, a photodetector 33 having a plurality of light receiving surfaces, a polarizing beam splitter 23, a hologram 29, and a reflecting element 35 with a first surface 30 having such wavelength selectivity as to transmit laser light at a prescribed wavelength and reflect laser light at the other wavelengths and with a second surface 31 reflecting and diffracting the laser light at the prescribed wavelength transmitted through the first surface 30 and is configured so that the laser light at the other wavelengths reflected by the first surface 30 impinges on corresponding light receiving surfaces out of the plurality of light receiving surfaces and the laser light at the prescribed wavelength transmitted through the first surface 30 and reflected by the second surface 31 is transmitted through the first surface 30 again and impinges on a corresponding light receiving surface.

Description

  The present invention relates to an optical disk device that records and reproduces data on an optical disk, an optical head device that forms part of the optical disk device, and an optical integrated device that forms part of the optical head device.

  Equipped with three types of laser light sources that emit laser beams of different wavelengths, and supports data recording and playback on three types of optical discs: CD (compact disc), DVD (digital versatile disc), and BD (Blu-ray disc) Possible optical head devices are widespread. In addition, a small-sized optical head device including a light source unit integrated by narrowing the distance between the light emitting points of three types of laser light sources to several hundred μm or less is also used. Further, in order to reduce the size of the optical head device, the optical axes of the three types of laser light emitted from the light source unit including the three types of laser light sources are matched using a flat light guide, and each laser beam is set to 1 A technique for making light incident on a common light receiving surface of two light receiving element chips has also been proposed (see, for example, Patent Document 1).

Japanese Patent Laying-Open No. 2010-27148 (for example, summary, FIG. 1)

  In the optical head device described in Patent Document 1, each laser beam is detected by a common light receiving surface of one light receiving element chip for miniaturization, but is incident on the light receiving element chip using a flat light guide. Since the optical axes of the three types of laser light coincide with each other, extremely high accuracy is required for the positional relationship among each of the three types of laser light sources, the light receiving surface of the light receiving element chip, and the light guide means of the flat plate. There is a problem that.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and an object thereof is to provide an optical integrated device, an optical head device, and an optical disc device that are easy to assemble and have a small size.

  An optical integrated device according to an aspect of the present invention includes a plurality of laser light sources, and selectively emits one of a plurality of laser beams having different wavelengths generated by the plurality of laser light sources. A light source unit, a plurality of light receiving surfaces for receiving the plurality of laser beams, each of the light receiving surfaces outputting a detection signal having a signal level corresponding to the amount of received light, and the light source A separation element that separates the laser light emitted from the unit and directed to the optical disk and a laser light reflected by the optical disk, a deflection element that changes a traveling direction of the laser light reflected by the optical disk and separated by the separation element, A first surface having a wavelength selectivity for passing a laser beam having a predetermined wavelength among the plurality of laser beams and reflecting a laser beam having another wavelength; and the first surface. A reflection element having a second surface for reflecting and diffracting the laser beam having the predetermined wavelength, and passing the deflection element and reflecting the laser beam of the other wavelength reflected by the first surface, The laser light having the predetermined wavelength is incident on a corresponding light receiving surface among the plurality of light receiving surfaces, passes through the deflection element, passes through the first surface, and is reflected by the second surface. The separation element, the deflection element, the reflection element, and the photodetector are arranged so as to pass again through one surface and enter a corresponding light receiving surface of the photodetector.

  An optical head device according to another aspect of the present invention includes a plurality of laser light sources, and selectively selects any one of a plurality of laser lights having different wavelengths generated by the plurality of laser light sources. A light source unit that emits light, a laser beam that is directed toward the optical disc, an objective lens that collects reflected light diffracted by the information track of the optical disc, and a drive signal received from the outside, and the value of the drive signal An objective lens actuator that shifts the objective lens at least in the radial direction of the optical disc, and a plurality of light receiving surfaces that receive the plurality of laser beams, each of the plurality of light receiving surfaces receiving light. A photodetector that outputs a detection signal having a signal level corresponding to the amount of light; the laser light emitted from the light source unit and directed to the optical disc; A separation element that separates the laser light reflected by the disk, a deflecting element that changes a traveling direction of the laser light reflected by the optical disk and separated by the separation element, and a predetermined wavelength of the plurality of laser lights A first surface having a wavelength selectivity that allows laser light to pass therethrough and reflects laser light having other wavelengths, and a second surface that reflects and diffracts the laser light having the predetermined wavelength that has passed through the first surface. A laser beam having the other wavelength that has passed through the deflection element and reflected by the first surface is incident on a corresponding light-receiving surface of the plurality of light-receiving surfaces, and the deflection is performed. The laser beam having the predetermined wavelength that has passed through the element, passed through the first surface, and reflected by the second surface is allowed to pass through the first surface again, and is applied to the corresponding light receiving surface of the photodetector. The separating element so as to be incident , Characterized in that a said deflection element, said reflective element, and the light detector.

  An optical disc apparatus according to another aspect of the present invention has a plurality of laser light sources, and selectively emits one of a plurality of laser beams having different wavelengths generated by the plurality of laser light sources. A light source unit that collects the laser light directed to the optical disc, an objective lens that collects the reflected light diffracted by the information track of the optical disc, and a drive signal received from the outside, to the value of the drive signal An objective lens actuator that shifts the objective lens at least in a radial direction of the optical disc by a corresponding amount, and a plurality of light receiving surfaces that receive the plurality of laser beams, and each of the plurality of light receiving surfaces includes a received light amount A light detector that outputs a detection signal of a signal level corresponding to the laser light, and the laser light emitted from the light source unit and directed to the optical disc A separation element that separates the laser light reflected by the optical disk, a deflecting element that changes a traveling direction of the laser light reflected by the optical disk and separated by the separation element, and a predetermined wavelength of the plurality of laser lights A first surface having a wavelength selectivity that allows laser light to pass therethrough and reflects laser light having other wavelengths, and a second surface that reflects and diffracts the laser light having the predetermined wavelength that has passed through the first surface. And a servo circuit that sets the drive signal supplied to the objective lens actuator based on detection signals from the plurality of light receiving surfaces of the light detector, and passes through the deflection element. The laser beam having the other wavelength reflected by the first surface is incident on a corresponding light receiving surface among the plurality of light receiving surfaces, passes through the deflection element, passes through the first surface, and The separation element, the deflecting element, and the reflection so that the laser beam having the predetermined wavelength reflected by the surface of 2 passes through the first surface again and is incident on a corresponding light receiving surface of the photodetector. An element and the photodetector are arranged.

  According to the present invention, the size of the photodetector can be reduced by shifting the irradiation position of the laser beam having a predetermined wavelength among the plurality of laser beams having different wavelengths. The apparatus and the optical disk apparatus can be reduced in size.

It is a figure which shows schematically the structure of the optical disk apparatus based on Embodiment 1 and 2 of this invention. 1 is a perspective view schematically showing a configuration of an optical head device according to Embodiment 1. FIG. FIG. 3 is a side view schematically showing an optical path of BD laser light incident on a photodetector of the optical head device of FIG. 2. FIG. 3 is a side view schematically showing an optical path of DVD laser light incident on a photodetector of the optical head device of FIG. 2. FIG. 3 is a side view schematically showing an optical path of CD laser light incident on a photodetector of the optical head device of FIG. 2. 6 is a plan view showing a hologram of the optical head device according to Embodiments 1 and 2. FIG. It is a figure which shows the light beam divided into 7 by the light-receiving surface and hologram of the photodetector of the optical head apparatus of FIG. It is a figure which shows schematically the irradiation area | region of the laser beam irradiated to the hologram of FIG. 6 (when there is no shift of an objective lens). FIG. 7 is a diagram schematically showing an irradiation area of laser light irradiated on the hologram of FIG. 6 (when the objective lens is shifted to the inner peripheral side of the optical disk in the radial direction). FIG. 7 is a diagram schematically showing an irradiation region of laser light irradiated on the hologram of FIG. 6 (when the objective lens is shifted to the outer peripheral side of the optical disc in the radial direction). (A)-(c) is a figure which shows the change of the signal level of the detection signal by the shift of the radial direction of the objective lens of the optical head apparatus which concerns on Embodiment 1 and 2. FIG. FIG. 5 is a diagram showing an irradiation region of laser light focused on an information track of an information recording layer of an optical disc in the optical head device according to Embodiments 1 and 2. It is a figure which shows roughly the irradiation area | region of the laser beam for DVD divided | segmented with the light-receiving surface and diffraction grating of the photodetector of FIG. It is a figure which shows roughly the irradiation area | region of the laser beam for DVD divided | segmented with the light-receiving surface and diffraction grating of the photodetector in a comparative example. It is a figure which shows schematically the light-receiving surface of the photodetector of FIG. 2, and the irradiation area | region of the laser beam for CD. FIG. 6 is a perspective view schematically showing a configuration of an optical head device according to a second embodiment. It is a side view which shows roughly the optical path of the laser beam for BD which injects into the photodetector of the optical head apparatus of FIG. It is a side view which shows roughly the optical path of the laser beam for DVD which injects into the photodetector of the optical head apparatus of FIG. It is a side view which shows roughly the optical path of the laser beam for CD which injects into the photodetector of the optical head apparatus of FIG. FIG. 17 is a diagram schematically showing a light receiving surface of the light detector of FIG. 16 and a light beam irradiation area divided into seven by a hologram (when there is no radial shift of the objective lens). It is a figure which shows schematically the irradiation area | region of the laser beam for BD divided | segmented with the light-receiving surface of the photodetector and the diffraction grating in a comparative example. It is a figure which shows roughly the irradiation area | region of the laser beam for DVD divided | segmented with the light-receiving surface and diffraction grating of the photodetector of FIG. It is a figure which shows schematically the light-receiving surface of the photodetector of FIG. 16, and the irradiation area | region of the laser beam for CD.

<< 1 >> Embodiment 1
<< 1-1 >> Configuration of Optical Disc Device FIG. 1 is a diagram schematically showing a configuration of an optical disc device according to Embodiments 1 and 2 of the present invention. As shown in FIG. 1, the optical disk apparatus includes a turntable 3a on which an optical disk 60 is mounted, a spindle motor 3 as a disk drive unit that rotationally drives the turntable 3a during recording or reproduction, and data reproduction for the optical disk 60. Alternatively, it includes an optical head device 1 (in the second embodiment to be described later, an optical head device 2) that records data, and a moving unit 4 that shifts the optical head device 1 in the radial (radius) direction of the optical disk. Further, the optical disc apparatus has an electric signal level corresponding to the amount of light received by the light receiving surface (light receiving element) of the light detector (light detector 33 shown in FIG. 2 described later) of the optical head device 1. It has a matrix circuit 5 to which signals are supplied, a signal reproducing circuit 6, a servo circuit 7, a spindle control circuit 8, a laser control circuit 9, a thread control circuit 10, and a controller 11.

  The matrix circuit 5 includes a reproduction signal generation unit, a focus error detection unit, and a track error detection unit using a matrix arithmetic circuit and an amplifier circuit, and a plurality of light receiving surfaces (described later) of the photodetector of the optical head device 1. 7, a high-frequency signal reproduction signal RS, a focus error signal FES for servo control, a track error signal TES, and the like are generated from output signals from FIG. The reproduction signal RS output from the matrix circuit 5 is supplied to the signal reproduction circuit 6, and the focus error signal FES and the track error signal TES output from the matrix circuit 5 are supplied to the servo circuit 7.

  The signal reproduction circuit 6 performs binarization processing and reproduction clock generation processing on the reproduction signal RS from the matrix circuit 5 to generate reproduction data. The data decoded to the reproduction data is transferred to, for example, a device as an AV (Audio / Visual) system or a host device such as a personal computer (PC).

  The servo circuit 7 generates various servo drive signals for focus and track from the focus error signal FES and the track error signal TES supplied from the matrix circuit 5, and causes the optical head device 1 to perform a servo operation. That is, the servo circuit 7 generates a focus drive signal FDS and a track drive signal TDS as drive signals according to the focus error signal FES and the track error signal TES, and the focus coil and the track coil of the objective lens actuator of the optical head device 1. Drive. Thus, a focus servo loop and a track servo loop are formed by the optical head device 1, the matrix circuit 5, and the servo circuit 7.

  The spindle control circuit 8 controls the rotation of the spindle motor 3. The laser control circuit 9 controls the intensity of the laser light emitted from the optical head device 1. The sled control circuit 10 shifts the optical head device 1 in the radial direction (radial direction) of the optical disc 60 by the moving unit 4 so that the optical head device 1 reproduces data at a desired position in the radial direction of the optical disc 60 (or The optical head device 1 can record data at a desired position in the radial direction of the optical disk 60).

  Various operations of the servo system and the reproduction system as described above are controlled by a controller 11 formed by a microcomputer. The controller 11 executes various processes in accordance with commands supplied from the host device.

<< 1-2 >> Configuration of Optical Head Device FIG. 2 is a perspective view schematically showing the configuration of the optical head device 1 according to the first embodiment. In the optical head device 1, three types of semiconductor lasers (laser light sources) that generate three types of laser beams having different wavelengths are integrated so that the distance between the light emitting points of adjacent laser light sources is several hundred μm or less. The light source unit 21, the diffraction grating 22, and a polarization beam splitter 23 as a separation element that separates the laser light directed to the optical disk 60 and the laser light reflected by the optical disk 60 are provided. Further, the optical head device 1 condenses laser light directed to the quarter wavelength plate 24, the collimator lens 25, and the optical disc 60, and the reflected light diffracted by the information track 61 of the information recording layer of the optical disc 60. Is provided with an objective lens 26 for condensing light, a movable holding portion 27 for holding the objective lens 26, and an objective lens actuator 28 for driving the movable holding portion 27 in the focus direction or the radial direction of the optical disc 60. Further, the optical head device 1 includes a hologram 29 as a deflecting element (diffraction element), a BD / CD laser light reflecting surface 30, a DVD laser light reflecting surface 31, and an astigmatism that imparts astigmatism to the laser light. An optical element 32 and a photodetector 33 are provided. Both the light source unit 21 and the light detector 33 are fixed to the support structure 20, and the light source unit 21 and the light detector 33 have an integral structure.

  The light source unit 21 includes three types of laser light sources 21B, 21D, and 21C. The light emitting points of the three laser light sources 21B, 21D, and 21C are arranged linearly in the radial direction, and generate BD laser light in order from the negative (−) side in the radial direction (that is, the center side of the optical disc 60). The light emitting point of the BD laser light source 21B, the light emitting point of the DVD laser light source 21D for generating DVD laser light, and the light emitting point of the CD laser light source 21C for generating CD laser light are arranged in this order. That is, the plurality of laser light sources (21B, 21D, and 21C) generate laser light having a shorter wavelength as they are positioned linearly in the radial direction of the optical disc 60 and on the inner side (minus side) in the radial direction. It is arranged to become. The light emitting point of the DVD laser light source 21D at the center of the three light emitting points is preferably arranged on the optical axis AX of the collimator lens 25. As a result, it is possible to average the degradation of the laser beam condensing performance as compared with the case where any of the light emitting points at both ends of the three light emitting points is disposed on the optical axis of the collimator lens 25. That is, it is possible to prevent the deterioration of the light collecting performance from being excessively biased to either the BD laser beam or the CD laser beam. Furthermore, on the light detector 33, the radial direction plus (+) side of the position where the first light beam 101 (shown in FIG. 7 to be described later) generated from the BD laser beam arrives, the BD Position where the laser beam for DVD reaches the negative (−) side in the radial direction of the position where the second and third light beams 102 and 103 (shown in FIG. 7 described later) generated from the laser beam for laser arrive. And a position where the laser beam for CD reaches. For this reason, the radial length required for arranging all the light receiving surfaces can be shortened, and the chip size of the photodetector 33 can be reduced.

  FIG. 3 is a side view schematically showing the optical path of the BD laser light incident on the photodetector 33 of the optical integrated device 1a of the optical head device 1 of FIG. FIG. 4 is a side view schematically showing the optical path of the DVD laser beam incident on the photodetector 33 of the optical integrated device 1a of the optical head device 1 of FIG. FIG. 5 is a side view schematically showing the optical path of the CD laser beam incident on the photodetector 33 of the optical integrated element 1a of the optical head device 1 of FIG. As shown in FIGS. 3 to 5, the optical integrated device 1a has three types of laser light sources 21B, 21D, and 21C, and three types of wavelengths generated by these laser light sources 21B, 21D, and 21C and having different wavelengths from each other. A light source unit 21 that selectively emits one of the laser beams, and a plurality of light receiving surfaces (B1 to B8, D1 to D8, and C1 to C4) that receive the plurality of laser beams. Each of the light receiving surfaces separates a photodetector 33 that outputs a detection signal having a signal level corresponding to the amount of received light, and a laser beam emitted from the light source unit 21 toward the optical disc 60 and a laser beam reflected by the optical disc 60. A polarizing beam splitter 23 as a separating element, and a hologram 29 as a deflecting element that changes the traveling direction of the laser beam separated by the polarizing beam splitter 23. It has wavelength selectivity that allows laser light of a predetermined wavelength (DVD laser light) out of the three types of laser light to pass and reflects laser light of other wavelengths (BD laser light and CD laser light). BD / CD laser light reflecting surface 30 as a first surface, and a second surface for reflecting and diffracting laser light of a predetermined wavelength (DVD laser light) that has passed through the BD / CD laser light reflecting surface 30 And a reflecting element 35 having a laser beam reflecting surface 31 for DVD. In the optical integrated device 1a, as shown in FIG. 3 and FIG. 5, laser light of other wavelengths that have passed through the hologram 29 and reflected by the BD / CD laser light reflecting surface 30 (BD laser light and CD laser). Light) is incident on the corresponding light receiving surfaces (B1 to B8, C1 to C4) of the plurality of light receiving surfaces, passes through the hologram 29, as shown in FIG. 4, and the laser light reflecting surface 30 for BD / CD. The laser light having a predetermined wavelength (DVD laser light) reflected by the DVD laser light reflecting surface 31 passes again through the BD / CD laser light reflecting surface 30, and the corresponding light reception by the light detector 33 is performed. The polarizing beam splitter 23, the hologram 29, the BD / CD laser light reflecting surface 30 and the DVD laser light reflecting surface 31 of the reflecting element 35, and the laser light reflecting surface 31 for DVD so as to be incident on the surfaces (D1 to D8); It is arranged detectors 33.

<< 1-3 >> Recording / Reproducing Operation Using BD Laser Light A case of recording / reproducing BD will be described. The BD laser light emitted from the BD laser light source 21 </ b> B of the light source unit 21 passes through the diffraction grating 22, the polarization beam splitter 23, the quarter wavelength plate 24, and the collimator lens 25. (In this case, the light is focused on the information track 61 of the information recording layer of BD 60). The laser beam condensed on the information track 61 is diffracted by the information track 61 of the optical disc 60 to become reflected light, passes through the objective lens 26, the collimator lens 25, and the quarter-wave plate 24, and is polarized by the polarization beam splitter 23. Reflected. The laser light reflected by the polarization beam splitter 23 passes through the hologram 29, is reflected by the BD / CD laser light reflecting surface 30, passes through the astigmatic optical element 32, and is irradiated to the photodetector 33.

  The BD / CD laser light reflecting surface 30 has a high reflectance with respect to light having wavelengths of about 405 [nm] and about 780 [nm] which are BD laser light and CD laser light, and is a DVD laser light. This is a surface on which a multilayer film having a high transmittance with respect to light having a wavelength of about 660 [nm] is formed.

  FIG. 6 is a plan view showing a hologram 29 of the optical head device according to Embodiment 1 (and Embodiment 2 described later). As shown in FIG. 6, the hologram 29 includes a first diffraction region 291, a second diffraction region 292, a third diffraction region 293, and a fourth diffraction region (diffraction regions) divided into six parts. Diffraction region 294, fifth diffraction region 295, and sixth diffraction region 296.

  The first diffractive region 291 is a region irradiated with a light beam (main beam) that is a 0th-order laser beam among the reflected light diffracted by the information track 61 of the information recording layer of the optical disc 60 (in a broken-line circle). And a region including the entire region (hatched region 298) irradiated with the light beam (sub beam) which is the laser beam of the −1st order light in the main beam reflected light. .

  The second diffractive region 292 is a region irradiated with a light beam (main beam) that is a 0th-order laser beam among the reflected light diffracted by the information track 61 of the information recording layer of the optical disc 60 (in a broken-line circle). And a region including the entire region (hatched region 299) irradiated with the main beam and the light beam (sub beam) which is the laser beam of the + 1st order light of the reflected light. .

  The third diffractive region 293, the fourth diffractive region 294, the fifth diffractive region 295, and the sixth diffractive region 296 are the zero-order light of the reflected light diffracted by the information track 61 of the information recording layer of the optical disc 60. A region irradiated with a light beam (main beam) that is a laser beam (a circular region 297 shown in FIG. 6), and a laser beam of + 1st order light or −1st order light of the main beam and reflected light. This is a region that does not include a region (hatching region 298, 299) irradiated with a certain light beam (sub beam).

The light quantity ratio of the + 1st order light, the 0th order light, and the −1st order light, which are diffracted lights separated by the first to sixth diffraction regions 291 to 296 of the hologram 29, is expressed by the following equation, for example.
+ 1st order light: 0th order light: -1st order light = 1: 8: 1

  FIG. 7 is a diagram schematically showing irradiation regions of the light beams (BD laser light) 101 to 107 divided into seven by the light receiving surface of the photodetector 33 and the hologram 29 in FIG. 2 (in the radial direction of the objective lens 26). When there is no shift).

  The photodetector 33 includes a first diffraction region 291, a second diffraction region 292, a third diffraction region 293, a fourth diffraction region 294, a fifth diffraction region 295, and a sixth diffraction region of the hologram 29. The hologram 29 is the light beam (main beam) that is the 0th-order light of the diffracted light generated by the 296 (that is, the 0th-order laser light of the reflected light diffracted by the information track 61 of the information recording layer of the optical disc 60). A plurality of light-receiving surfaces B1, B2, B3, and B4 that receive the first light beam 101 (circular hatching region) that is the light beam of zero-order light among the diffracted light generated by diffracting (transmitting). Have.

  The light detector 33 receives the second light beam 102 that is the + 1st-order light among the diffracted light generated in the first diffraction region 291 of the hologram 29, and the second light of the hologram 29. And a light receiving surface B6 for receiving the third light beam 103 which is the + 1st order light of the diffracted light generated in the diffraction region 292. The diffracted light to be used may be −1st order light among the diffracted lights generated in the first or second diffractive areas 291 and 292 of the hologram 29.

  Further, the photodetector 33 is generated in the fourth light beam 104 which is the + 1st order light of the diffracted light generated in the third diffraction region 293 of the hologram 29 and in the fourth diffraction region 294 of the hologram 29. It has a light receiving surface B7 for receiving the fifth light beam 105 which is the + 1st order light in the diffracted light. Further, the photodetector 33 is generated by the sixth light beam 106 which is the + 1st order light among the diffracted light generated in the fifth diffraction region 295 of the hologram 29 and the sixth diffraction region 296 of the hologram 29. It has a light receiving surface B8 for receiving the seventh light beam 107 which is the + 1st order light in the diffracted light. The diffracted light to be used may be −1st order light among the diffracted lights generated in the third, fourth, fifth and sixth diffraction regions 293, 294, 295 and 296 of the hologram 29. .

  The first light beam 101 that is the zero-order laser beam generated by the hologram 29 (passed through the hologram 29) reaches the light receiving surfaces B1, B2, B3, and B4.

  Of the diffracted light generated by the first diffraction region 291 of the hologram 29, the second light beam 102 which is the + 1st order light reaches the light receiving surface B5 and is generated by the second diffraction region 292 of the hologram 29. The third light beam 103 which is the + 1st order light of the diffracted light reaches the light receiving surface B6.

  The fourth light beam 104 which is the + 1st order light of the diffracted light generated by the third diffraction region 293 of the hologram 29 and the +1 of the diffracted light generated by the fourth diffraction region 294 of the hologram 29 The fifth light beam 105 as the next light reaches the light receiving surface B7. Further, the sixth light beam 106 which is the + 1st order light among the diffracted light generated by the fifth diffraction region 295 of the hologram 29 and the diffracted light generated by the sixth diffraction region 296 of the hologram 29 The seventh light beam 107 which is the + 1st order light reaches the light receiving surface B8. In the following description, the signal levels of the electrical signals (detection signals) generated by photoelectric conversion on the light receiving surfaces B1, B2, B3, B4, B5, B6, B7, and B8 are the same as the signs indicating the light receiving surfaces. Indicated as B1, B2, B3, B4, B5, B6, B7, B8.

The matrix circuit 5 receives the detection signals B1, B2, B3, B4, B5, B6, B7, and B8 of the photodetector 33, and generates a focus error signal FES by the calculation of the following astigmatism method. In the following description, the signal level of the focus error signal is also expressed as FES.
FES = (B1 + B3) − (B2 + B4)

Further, the matrix circuit 5 generates the track error signal TES by the following equation. In the following description, the signal level of the track error signal is also expressed as TES.
TES = (B5−B6) −k × (B7−B8)
Here, k is a constant.

  FIG. 8 is a diagram schematically showing an irradiation region of the light beam irradiated on the hologram 29 (when there is no shift of the objective lens 26). FIG. 9 is a diagram schematically showing the irradiation region of the light beam irradiated on the hologram 29 (when the objective lens 26 is shifted to the inner peripheral side of the optical disk in the radial direction). FIG. 10 is a diagram schematically showing the irradiation region of the light beam irradiated on the hologram 29 (when the objective lens 26 is shifted to the outer peripheral side of the optical disk in the radial direction). FIG. 9 shows that when the objective lens 26 is shifted in the inner peripheral direction of the optical disc 60, the light beam is shifted to the left in FIG. 9 (the spot moving direction by the lens shift). FIG. 10 shows that when the objective lens 26 is shifted in the outer circumferential direction of the optical disc 60, the light beam is shifted to the right of FIG. 10 (the opposite direction to that in FIG. 8).

  FIGS. 11A to 11C are diagrams showing changes in the detection signal due to the radial shift of the objective lens 26. FIG. 11 (a) to 11 (c), respectively, when the objective lens 26 is not shifted in the radial direction, when the objective lens 26 is shifted toward the inner periphery of the optical disk, and when the objective lens 26 is shifted toward the outer periphery of the optical disk. It is. 11A to 11C show signals when the focus servo is on and the track servo is off.

  As can be understood from FIGS. 11A and 8, when there is no radial shift of the objective lens 26, the waveform of the signal (B5-B6) is a push-pull waveform having no offset with respect to GND (broken line). It becomes. At this time, the DC waveform (solid line) of the signal (B7-B8) is also a waveform having no offset with respect to GND (broken line).

  As can be understood from FIGS. 11B and 9, when the objective lens 26 is shifted to the inner peripheral side in the radial direction (toward the inner periphery), the waveform of the signal (B5-B6) is GND (broken line). The push-pull waveform is offset positively with respect to the reference. At this time, the DC waveform (solid line) of the signal (B7-B8) is also a waveform that is offset positively with respect to GND (broken line). Therefore, the value of the signal (B7-B8) represents a value corresponding to the shift amount of the objective lens 26, and is a constant multiple (k times) of the value of the signal (B7-B8) from the value of the (B5-B6) signal. ) Is subtracted to obtain a track error signal TES with offset cancelled.

  As can be understood from FIG. 11C and FIG. 10, when the objective lens 26 is shifted to the inner peripheral side in the radial direction (toward the inner periphery), the waveform of the signal (B5-B6) is GND (broken line). The push-pull waveform is offset negatively with respect to the reference. At this time, the DC waveform (solid line) of the signal (B7-B8) is also a waveform that is offset negatively with respect to GND (broken line). Therefore, the value of the signal (B7-B8) represents a value corresponding to the shift amount of the objective lens 26, and is a constant multiple (k times) of the value of the signal (B7-B8) from the value of the (B5-B6) signal. ) Is subtracted to obtain a track error signal TES with offset cancelled.

<< 1-4 >> Recording / Reproducing Operation Using DVD Laser Light A case of recording / reproducing a DVD will be described. In FIG. 2, the DVD laser light emitted from the light source unit 21 passes through the diffraction grating 22. The ± first-order diffracted light generated by the diffraction grating 22 has a predetermined light quantity ratio at the wavelength of the DVD laser light. The light quantity ratio of the + 1st order light, the 0th order light, and the −1st order light, which are diffracted light, is expressed by the following equation, for example.
+ 1st order light: 0th order light: -1st order light = 1: 20: 1
The laser beam divided by the diffraction grating 22 passes through the polarizing beam splitter 23, the quarter-wave plate 24, and the collimator lens 25, and is transmitted through the objective lens 26 to the information track 61 of the information recording layer of the optical disc (here, DVD) 60. It is focused on.

  FIG. 12 is a diagram showing the laser light focused on the information track 61 of the information recording layer of the optical disc 60. The main beam 201 (circular hatching region) that is the zero-order laser beam of the diffracted light generated by the diffraction grating 22 is collected on the information track 61. Of the diffracted light generated by the diffraction grating 22, the sub beam 202 that is the laser light of the + 1st order light and the sub beam 203 that is the laser light of the −1st order among the diffracted light generated by the diffraction grating 22 are the main beam. With respect to 201, the light is condensed at a position shifted in the radial direction by a distance that is half the distance between the information tracks 61.

  The main beam 201 and the sub beams 202 and 203 are diffracted by the information track 61 of the optical disc 60 to become reflected light, pass through the objective lens 26, the collimator lens 25, and the quarter wavelength plate 24, and are reflected by the polarization beam splitter 23. , Passes through the hologram 29, passes through the BD / CD laser light reflecting surface 30, is reflected by the DVD laser light reflecting surface 31, passes through the BD / CD laser light reflecting surface 30 again, and is an astigmatic optical element 32. , And the light detector 33 is irradiated.

  The DVD laser light reflecting surface 31 has a high reflectance with respect to light of about 660 [nm] which is the wavelength of the DVD laser light. At the same time, a blazed diffraction grating is preferably formed on the DVD laser light reflecting surface 31 in order to deflect the DVD laser light. The blazed diffraction grating simultaneously has a function of diverging laser light in order to offset the difference in optical path length between the BD laser light and the CD laser light. That is, the optical path length of the DVD laser light that has passed through the BD / CD laser light reflecting surface 30 is longer than that of the BD laser light and the CD laser light. Therefore, the size of the irradiation spot is adjusted to an appropriate size by slightly diverging the laser beam.

  FIG. 13 is a diagram schematically showing an irradiation region of the DVD laser light divided by the light receiving surface of the photodetector 33 of FIG. 2 and the diffraction grating 22. The main beam 201, the sub beam 202, and the sub beam 203 reflected by the DVD laser light reflecting surface 31 are deflected by the diffractive action, and are tangential in FIG. 13 rather than the case of being reflected by the BD / CD laser light reflecting surface 30. It has reached the plus (+) side of the direction. The photodetector 33 has a plurality of light receiving surfaces D1, D2, D3, and D4 that receive the main beam 201 that is the zero-order laser light of the diffracted light generated by the diffraction grating 22. In addition, light receiving surfaces D5 and D6 that receive the sub beam 202 that is the laser light of the + 1st order light among the diffracted light generated by the diffraction grating 22 are provided. Further, light receiving surfaces D7 and D8 for receiving the sub beam 203 which is the laser beam of the −1st order light among the diffracted lights generated by the diffraction grating 22 are provided.

  FIG. 14 shows the light receiving surface and diffraction of the photodetector 33a when the main beam 201a, the sub beam 202a, and the sub beam 203a are reflected by the reflecting surface arranged at the position of the BD / CD laser light reflecting surface 30 in the comparative example. FIG. 3 is a diagram schematically showing an irradiation region of DVD laser light divided by a grating 22; Compared with FIG. 13 showing the first embodiment, the light receiving surfaces D1, D2, D3, D4, D5, D6, D7, and D8 need to be arranged on the negative (−) side in the tangential direction as a whole. Therefore, the length L33 in the tangential direction necessary for arranging all the light receiving surfaces in the first embodiment of FIG. 13 is the tangential necessary for arranging all the light receiving surfaces in the comparative example of FIG. It is shorter than the length L33a in the direction. For this reason, the optical integrated device 1a and the optical head device 1 according to Embodiment 1 can reduce the length in the tangential direction.

  In FIG. 13, the main beam, which is the zero-order laser beam generated by the diffraction grating 22 (passed through the diffraction grating 22), reaches the light receiving surfaces D1, D2, D3, and D4.

  The sub beam 202 which is the laser light of the + 1st order light among the diffracted light generated by the diffraction grating 22 reaches the light receiving surfaces D5 and D6. Of the diffracted light generated by the diffraction grating 22, the sub beam 203, which is the -1st order laser beam, reaches the light receiving surfaces D7 and D8. In the following description, the signal levels of electrical signals (detection signals) generated by photoelectric conversion on the light receiving surfaces D1, D2, D3, D4, D5, D6, D7, and D8 are the same as the signs indicating the light receiving surfaces. D1, D2, D3, D4, D5, D6, D7, D8.

The matrix circuit 5 receives the detection signals D1, D2, D3, D4, D5, D6, D7, and D8 of the photodetector 33, and generates a focus error signal FES by the calculation of the following astigmatism method.
FES = (D1 + D3) − (D2 + D4)

In addition, the matrix circuit 5 generates the track error signal TES by a general differential push-pull method of the following equation.
TES = (D1 + D2) − (D4 + D3) −k × {(D5−D6) + (D7−D8)}
Here, k is a constant.

<< 1-5 >> Recording / Reproducing Operation Using CD Laser Light A case of recording / reproducing a CD will be described. In FIG. 2, the CD laser light emitted from the light source unit 21 passes through the diffraction grating 22. The diffraction grating 22 is set so that the ± first-order diffracted light becomes smaller with respect to the wavelength of the laser beam for CD, and almost 100% of the light passing through the diffraction grating 22 is zero-order diffracted light. . The laser beam that has passed through the diffraction grating 22 passes through the polarization beam splitter 23, the quarter-wave plate 24, and the collimator lens 25, and is focused on the information track 61 of the information recording layer of the optical disc 60 by the objective lens 26. The laser light is diffracted by the information track 61 of the optical disk 60 to become reflected light, passes through the objective lens 26, the collimator lens 25 and the quarter wavelength plate 24, is reflected by the polarization beam splitter 23, passes through the hologram 29, The light is reflected by the BD / CD laser light reflecting surface 30, passes through the astigmatic optical element 32, and is irradiated to the photodetector 33.

  FIG. 15 is a diagram schematically showing the light receiving surface of the photodetector 33 in FIG. 2 and the irradiation region of the CD laser light. The photodetector 33 has a plurality of light receiving surfaces C1, C2, C3, and C4 that receive the light beam 301 (circular hatching region).

  The light beam 301 reaches the light receiving surfaces C1, C2, C3, and C4. In the following description, the signal levels of electric signals (detection signals) generated by photoelectric conversion on the light receiving surfaces C1, C2, C3, and C4 are the same as C1, C2, C3, C4 write.

The matrix circuit 5 receives the detection signals C1, C2, C3, and C4 of the light detector 33, and generates a focus error signal FES by calculation of the following astigmatism method.
FES = (C1 + C3) − (C2 + C4)

Further, the matrix circuit 5 generates a track error signal TES by a general phase difference calculation of the following equation.
TES = φ (C1 + C3) −φ (C2 + C4)
Here, φ represents the phase of the signal.

<< 1-6 >> Effects of First Embodiment As described above, in the first embodiment, the optical integrated element 1a in which the light source unit 21 and the photodetector 33 are integrated is used. Thereby, there is an effect that it is possible to prevent the mutual positional relationship between the light source unit 21 and the photodetector 33 from being shifted.

  In the first embodiment, the DVD laser light reflecting surface 31 of the optical integrated device 1a is formed with a blazed diffraction grating to deflect the DVD laser light. The DVD laser light receiving surfaces D1, D2, D3, D4, D5, D6, D7, and D8 are entirely arranged on the plus (+) side in the tangential direction by the deflection by the DVD laser light reflecting surface 31. The length L33 in the tangential direction necessary for arranging all the light receiving surfaces can be shortened. That is, as shown in FIGS. 7, 13, and 15, a plurality of light receiving surfaces B <b> 1 to B <b> 8, D <b> 1 to D <b> 8, and C <b> 1 to C <b> 4 of the photodetector 33 correspond to a plurality of laser beams for DVD. The light receiving surfaces D1 to D8 and the plurality of light receiving surfaces C1 to C4 corresponding to the CD laser light are arranged within the range of the width L33 in the tangential direction where the plurality of light receiving surfaces B1 to B8 corresponding to the BD laser light are present. Has been. For this reason, in Embodiment 1, there exists an effect that the chip size of the tangential direction of the photodetector 33 can be made small. Further, as shown in FIGS. 7, 13, and 15, the plurality of light receiving surfaces B <b> 1 to B <b> 8, D <b> 1 to D <b> 8, and C <b> 1 to C <b> 4 of the photodetector 33 correspond to a plurality of DVD laser beams. The plurality of light receiving surfaces C1 to C4 corresponding to the light receiving surfaces D1 to D8 and the CD laser light have a radial width (in a direction orthogonal to L33) where the plurality of light receiving surfaces B1 to B8 corresponding to the BD laser light exist. (Length). For this reason, in Embodiment 1, the chip size in the radial direction of the photodetector 33 can also be reduced.

  Further, the function of diverging the laser light by the blazed diffraction grating on the DVD laser light reflecting surface 31 makes it possible to adjust the optical path length and optimize the size of the light spot on the photodetector 33.

<< 2 >> Embodiment 2
<< 2-1 >> Configuration of Optical Disc Device The configuration of the optical disc device according to the second embodiment is the same as that of the first embodiment except for the configuration of the optical head device 2. Therefore, FIG. 1 is also referred to in the description of the second embodiment. In the second embodiment, the method for generating the focus error signal FES and the track error signal TES for BD, DVD, and CD is the same as that in the first embodiment. Reference is also made to FIGS. 6 and 8 to 12.

<< 2-2 >> Configuration of Optical Head Device FIG. 16 is a perspective view schematically showing the configuration of the optical head device 2 according to the second embodiment. In FIG. 16, the same reference numerals are given to the same or corresponding components as those shown in FIG. In the optical head device 2, the light source unit 21 and the light detector 53 are fixed to and integrated with the support structure 40. A light source unit 21, a diffraction grating 22, a polarizing beam splitter 23, and a quarter-wave plate 24, which are integrated with three types of laser light sources having different wavelengths so that the distance between the light emitting points is several hundred μm or less. And the collimator lens 25, the objective lens 26 for condensing the laser beam directed to the optical disc 60, and the reflected light diffracted by the information track 61 of the information recording layer of the optical disc 60, and the objective lens 26 are held. A movable holding part 27, an objective lens actuator 28 for driving the movable holding part 27 in a focus direction or a radial direction of the optical disc 60, a hologram 29 as a deflection element (diffraction element), and a DVD / CD laser light reflecting surface 50. A BD laser light reflecting surface 51, an astigmatic optical element 32 for providing astigmatism, and a photodetector 53. . The structure of the light source unit 21 is the same as that of the first embodiment.

  FIG. 17 is a side view schematically showing the optical path of the BD laser light incident on the photodetector 53 of the optical integrated element 2a of the optical head device 2 of FIG. FIG. 18 is a side view schematically showing the optical path of the DVD laser light incident on the photodetector 53 of the optical integrated element 2a of the optical head device 2 of FIG. FIG. 19 is a side view schematically showing the optical path of the laser beam for CD incident on the photodetector 53 of the optical integrated element 2a of the optical head device 2 of FIG. As shown in FIG. 17 to FIG. 19, the optical integrated device 1a has three types of laser light sources 21B, 21D, and 21C, and three types of different wavelengths generated by these laser light sources 21B, 21D, and 21C. A light source unit 21 that selectively emits one of the laser beams, and a plurality of light receiving surfaces (B1 to B8, D1 to D8, and C1 to C4) that receive the plurality of laser beams. Each of the light receiving surfaces separates a light detector 53 that outputs a detection signal having a signal level corresponding to the amount of received light, and a laser beam emitted from the light source unit 21 toward the optical disc 60 and a laser beam reflected by the optical disc 60. Polarization beam splitter 23 as a separating element, and hologram as a deflection element that changes the traveling direction of the laser beam separated by the polarization beam splitter 23 9 and wavelength selectivity that allows laser light of a predetermined wavelength (B laser light) of three types of laser light to pass and reflects laser light of other wavelengths (laser light for DVD and laser light for CD). A DVD / CD laser light reflecting surface 50 as a first surface having a second surface and a second laser beam reflecting and diffracting laser light of a predetermined wavelength (BD laser light) that has passed through the DVD / CD laser light reflecting surface 50. And a reflecting element 55 having a BD laser light reflecting surface 51 as the surface. In the optical integrated device 2a, as shown in FIGS. 18 and 19, laser light of other wavelengths that have passed through the hologram 29 and reflected by the DVD / CD laser light reflecting surface 50 (DVD laser light and CD laser light). Light) is incident on the corresponding light receiving surfaces (D1 to D8, C1 to C4) of the plurality of light receiving surfaces, passes through the hologram 29, as shown in FIG. 17, and the DVD / CD laser light reflecting surface 50 for DVD / CD. The laser light having a predetermined wavelength (BD laser light) reflected by the BD laser light reflecting surface 51 is again passed through the DVD / CD laser light reflecting surface 50, and the corresponding light reception by the photodetector 53 is performed. The polarizing beam splitter 23, the hologram 29, the DVD / CD laser light reflecting surface 50 of the reflecting element 55, and the BD laser light reflecting surface 51 so as to be incident on the surfaces (B1 to B8). And it is disposed an optical detector 53.

<< 2-3 >> Recording / Reproducing Operation Using BD Laser Light A case of BD recording / reproducing will be described. The BD laser light emitted from the light source unit 21 passes through the diffraction grating 22, the polarization beam splitter 23, the quarter wavelength plate 24, and the collimator lens 25, and the information track 61 on the information recording layer of the optical disk 60 is transmitted by the objective lens 26. It is focused on. The laser light is diffracted by the information track 61 of the optical disk 60 to become reflected light, passes through the objective lens 26, the collimator lens 25 and the quarter wavelength plate 24, is reflected by the polarization beam splitter 23, passes through the hologram 29, It passes through the DVD / CD laser light reflecting surface 50, is reflected by the BD laser light reflecting surface 51, passes again through the DVD / CD laser light reflecting surface 50, passes through the astigmatic optical element 32, and is detected by light. Irradiates the vessel 53. The DVD / CD laser light reflecting surface 50 has high reflectivity with respect to light having wavelengths of about 660 [nm] and about 780 [nm], which are DVD laser light and CD laser light. This is a surface on which a multilayer film having a high transmittance with respect to light having a wavelength of about 405 [nm] is formed.

  FIG. 6 is a plan view showing the hologram 29 shown in FIG. As shown in FIG. 6, the hologram 29 includes a first diffraction region 291, a second diffraction region 292, a third diffraction region 293, and a fourth diffraction region (diffraction regions) divided into six parts. Diffraction region 294, fifth diffraction region 295, and sixth diffraction region 296.

  The first diffractive region 291 is a region irradiated with a light beam (main beam) that is a 0th-order laser beam among the reflected light diffracted by the information track 61 of the information recording layer of the optical disc 60 (in a broken-line circle). And a region including the entire region (hatched region 298) irradiated with the light beam (sub beam) which is the laser beam of the −1st order light in the main beam reflected light. .

  The second diffractive region 292 is a region irradiated with a light beam (main beam) that is a 0th-order laser beam among the reflected light diffracted by the information track 61 of the information recording layer of the optical disc 60 (in a broken-line circle). And a region including the entire region (hatched region 299) irradiated with the main beam and the light beam (sub beam) which is the laser beam of the + 1st order light of the reflected light. .

  The third diffraction region 293, the fourth diffraction region 294, the fifth diffraction region 295, and the sixth diffraction region 296 are lasers of the 0th-order light of the reflected light diffracted by the information track 61 of the information recording layer of the optical disc 60. It is a region (circular region 297 shown in FIG. 6) irradiated with a light beam (main beam) that is light, and is a laser beam of + 1st order light or −1st order light of the main beam and reflected light. This is a region that does not include a region (hatching region 298, 299) irradiated with a light beam (sub beam).

The light quantity ratio of the diffracted light separated by the first to sixth diffraction regions 291 to 296 of the hologram 29 is expressed by the following equation, for example.
+ 1st order light: 0th order light: -1st order light = 1: 8: 1

  The BD laser light reflecting surface 51 has a high reflectance with respect to light having a wavelength of about 405 [nm], which is a BD laser light. At the same time, a blazed diffraction grating is formed to deflect the BD laser beam. The blazed diffraction grating simultaneously has a function of diverging laser light in order to cancel out the difference in optical path length.

  FIG. 20 is a diagram schematically showing an irradiation region of the light beam divided into seven by the light receiving surface of the photodetector 53 and the hologram 29 in FIG. 16 (when there is no radial shift of the objective lens 26).

  The light beam reflected by the BD laser light reflecting surface 51 is deflected by a diffractive action, and is minus (−) in the tangential direction of FIG. 20 than when reflected by the DVD / CD laser light reflecting surface 50. Has reached.

  The photodetector 53 includes a first diffraction region 291, a second diffraction region 292, a third diffraction region 293, a fourth diffraction region 294, a fifth diffraction region 295, and a sixth diffraction region of the hologram 29. The hologram 29 is the light beam (main beam) that is the 0th-order light of the diffracted light generated by the 296 (that is, the 0th-order laser light of the reflected light diffracted by the information track 61 of the information recording layer of the optical disc 60). A plurality of light receiving surfaces B1, B2, B3, and B4 that receive a first light beam 401 (circular hatching region) that is a light beam of 0th-order light among diffracted light generated by diffracting (transmitting) is provided. Have.

  Further, the photodetector 53 has a light receiving surface B5 that receives the second light beam 402 that is the + 1st order light of the diffracted light generated in the first diffraction region 291 of the hologram 29. Further, it has a light receiving surface B <b> 6 that receives the third light beam 403 that is the + 1st order light among the diffracted light generated in the second diffraction region 292 of the hologram 29. The diffracted light to be used may be −1st order light among the diffracted lights generated in the first or second diffractive areas 291 and 292 of the hologram 29.

  Further, the photodetector 53 is generated in the fourth light beam 404 that is the + 1st order light of the diffracted light generated in the third diffraction region 293 of the hologram 29 and in the fourth diffraction region 294 of the hologram 29. Light receiving surface B7 that receives the fifth light beam 405 that is the + 1st order light in the diffracted light, and the + 1st order light in the diffracted light generated in the fifth diffraction region 295 of the hologram 29. , And a seventh light beam 407, which is the + 1st order light of the diffracted light generated in the sixth diffraction region 296 of the hologram 29, has a light receiving surface B8. The diffracted light to be used may be −1st order light among the diffracted lights generated in the third, fourth, fifth and sixth diffraction regions 293, 294, 295 and 296 of the hologram 29. .

  FIG. 21 shows a comparative example, which schematically shows the light receiving surface of the photodetector 53 and the irradiation region of the BD laser light when the light beam is reflected by the DVD / CD laser light reflecting surface 50. is there. Compared with FIG. 20, the light receiving surfaces B1, B2, B3, B4, B5, B6, B7, and B8 are generally located on the plus (+) side in the tangential direction, so that all the light receiving surfaces are arranged. Comparing the required length in the tangential direction in FIG. 20 (Embodiment 2) and FIG. 21 (Comparative Example), the length L53 in FIG. 20 (Embodiment 2) is as shown in FIG. 21 (Comparative Example). In this case, the length is shorter than L53a.

  The first light beam 401 that is the zero-order laser beam generated by the hologram 29 (passed through the hologram 29) reaches the light receiving surfaces B1, B2, B3, and B4.

  The second light beam 402, which is the + 1st order light among the diffracted light generated by the first diffraction region 291 of the hologram 29, reaches the light receiving surface B5 and is generated by the second diffraction region 292 of the hologram 29. The third light beam 403 that is the + 1st order light of the diffracted light reaches the light receiving surface B6.

  The fourth light beam 404 that is the + 1st order light in the diffracted light generated by the third diffraction region 293 of the hologram 29 and the +1 of the diffracted light generated by the fourth diffraction region 294 of the hologram 29 The fifth light beam 405 that is the next light reaches the light receiving surface B7, and the sixth light beam 406 that is the + 1st order light among the diffracted light generated by the fifth diffraction region 295 of the hologram 29; The seventh light beam 407, which is the + 1st order light of the diffracted light generated by the sixth diffraction region 296 of the hologram 29, reaches the light receiving surface B8. In the following description, the signal levels of the electrical signals (detection signals) generated by photoelectric conversion on the light receiving surfaces B1, B2, B3, B4, B5, B6, B7, and B8 are the same as the signs indicating the light receiving surfaces. Indicated as B1, B2, B3, B4, B5, B6, B7, B8.

The matrix circuit 5 receives the detection signals B1, B2, B3, B4, B5, B6, B7, and B8 of the photodetector 53, and generates a focus error signal FES by the calculation of the following astigmatism method.
FES = (B1 + B3) − (B2 + B4)

Further, the matrix circuit 5 generates the track error signal TES by the following equation.
TES = (B5−B6) −k × (B7−B8)
Here, k is a constant.

  The shift of the objective lens 26 and the irradiation region of the light beam applied to the hologram 29 are shown in FIGS. 9 and 10 and are the same as those in the first embodiment. The shift of the objective lens 26 and the change of the detection signal are as shown in FIGS. 11A to 11C and are the same as those in the first embodiment.

<< 2-4 >> Recording / Reproducing Operation Using DVD Laser Light A case of recording / reproducing a DVD will be described. In FIG. 16, the DVD laser light emitted from the light source unit 21 passes through the diffraction grating 22. The ± first-order diffracted light generated by the diffraction grating 22 has a predetermined light quantity ratio at the wavelength of the DVD laser light. The light quantity ratio of the diffracted light is expressed by the following equation, for example.
+ 1st order light: 0th order light: -1st order light = 1: 20: 1
The laser beam divided by the diffraction grating 22 passes through the polarization beam splitter 23, the quarter-wave plate 24 and the collimator lens 25 and is focused on the information track 61 of the information recording layer of the optical disc 60 by the objective lens 26.

  FIG. 12 is a diagram showing the laser light focused on the information track 61 of the information recording layer of the optical disc 60. The main beam 501 (circular hatching region) that is the zero-order laser beam of the diffracted light generated by the diffraction grating 22 is collected on the information track 61. Of the diffracted light generated by the diffraction grating 22, a sub beam 502 that is laser light of + 1st order light and a sub beam 503 that is laser light of −1st order light among the diffracted light generated by the diffraction grating 22 is a main beam. With respect to 501, the light is condensed at a position shifted in the radial direction by a distance that is half the interval of the information track 61.

  The main beam 501 and the sub beams 502 and 503 are diffracted by the information track 61 of the optical disc 60 to become reflected light, pass through the objective lens 26, the collimator lens 25, and the quarter wavelength plate 24, and are reflected by the polarization beam splitter 23, The light passes through the hologram 29, is reflected by the DVD / CD laser light reflecting surface 50, passes through the astigmatic optical element 32, and is irradiated onto the photodetector 53.

  The DVD / CD laser light reflecting surface 50 has a high reflectivity with respect to light of about 660 [nm] and about 780 [nm], which are wavelengths of the DVD laser light and the CD laser light, and is a BD laser. This is a surface on which a multilayer film having a high transmittance with respect to light having a wavelength of about 405 [nm] is formed.

  FIG. 22 is a diagram schematically showing an irradiation region of the DVD laser light divided by the light receiving surface of the photodetector 53 and the diffraction grating 22 of FIG. The photodetector 53 has a plurality of light receiving surfaces D1, D2, D3, and D4 that receive a main beam 501 that is a zero-order laser beam of the diffracted light generated by the diffraction grating 22. In addition, light receiving surfaces D5 and D6 that receive the sub beam 502 that is the laser light of the + 1st order light among the diffracted light generated by the diffraction grating 22 are provided. Further, light receiving surfaces D7 and D8 for receiving a sub beam 503 which is a laser beam of −1st order light among the diffracted lights generated by the diffraction grating 22 are provided.

  The main beam 501 that is the zero-order laser beam generated by the diffraction grating 22 (passed through the diffraction grating 22) reaches the light receiving surfaces D1, D2, D3, and D4.

  The sub beam 502 which is the laser light of the + 1st order light among the diffracted light generated by the diffraction grating 22 reaches the light receiving surfaces D5 and D6. Of the diffracted light generated by the diffraction grating 22, the sub beam 503, which is the -1st order laser beam, reaches the light receiving surfaces D7 and D8. In the following description, the signal levels of electrical signals (detection signals) generated by photoelectric conversion on the light receiving surfaces D1, D2, D3, D4, D5, D6, D7, and D8 are the same as the signs indicating the light receiving surfaces. D1, D2, D3, D4, D5, D6, D7, D8.

The matrix circuit 5 receives the detection signals D1, D2, D3, D4, D5, D6, D7, and D8 of the light detector 53, and generates a focus error signal FES by the calculation of the following astigmatism method.
FES = (D1 + D3) − (D2 + D4)

In addition, the matrix circuit 5 generates the track error signal TES by a general differential push-pull method of the following equation.
TES = (D1 + D2) − (D4 + D3) −k × {(D5−D6) + (D7−D8)}
Here, k is a constant.

<< 2-4 >> Recording / Reproduction Operation Using CD Laser Light A case of CD recording / reproduction will be described. In FIG. 16, the CD laser light emitted from the light source unit 21 passes through the diffraction grating 22. The diffraction grating 22 is set so that the ± first-order diffracted light is smaller than the CD laser light, and almost 100% of the light passing through the diffraction grating 22 is zero-order diffracted light. The laser beam that has passed through the diffraction grating 22 passes through the polarization beam splitter 23, the quarter-wave plate 24, and the collimator lens 25, and is focused on the information track 61 of the information recording layer of the optical disc 60 by the objective lens 26. The laser light is diffracted by the information track 61 of the optical disk 60 to become reflected light, passes through the objective lens 26, the collimator lens 25 and the quarter wavelength plate 24, is reflected by the polarization beam splitter 23, passes through the hologram 29, The light is reflected by the DVD / CD laser light reflecting surface 50, passes through the astigmatic optical element 32, and is irradiated to the photodetector 53.

  FIG. 23 is a diagram schematically showing the light receiving surface of the photodetector 53 in FIG. 16 and the irradiation region of the CD laser light. The light detector 53 has a plurality of light receiving surfaces C1, C2, C3, and C4 that receive the light beam 601 (circular hatching region).

  The light beam 601 reaches the light receiving surfaces C1, C2, C3, and C4. In the following description, the signal levels of electrical signals (detection signals) generated by photoelectric conversion on the light receiving surfaces C1, C2, C3, and C4 are the same as C1, C2, C3, C4 write.

The matrix circuit 5 receives the detection signals C1, C2, C3, and C4 of the light detector 53, and generates a focus error signal FES by calculation of the following astigmatism method.
FES = (C1 + C3) − (C2 + C4)

Further, the matrix circuit 5 generates a track error signal TES by a general phase difference calculation of the following equation.
TES = φ (C1 + C3) −φ (C2 + C4)
Here, φ represents the phase of the signal.

<< 2-5 >> Effect of Embodiment 2 As described above, in Embodiment 2, the integrated optical element 2a in which the light source unit 21 and the photodetector 53 are integrated is used. Thereby, there is an effect that it is possible to prevent the positional relationship between the light source unit 21 and the light detector 53 from shifting.

  In the second embodiment, the BD laser light reflecting surface 51 of the integrated optical element 2a is formed with a blazed diffraction grating to deflect the BD laser light. By the deflection by the BD laser light reflecting surface 51, the BD laser light receiving surfaces B1 to B8 can be disposed on the plus (+) side in the tangential direction as a whole, and all the light receiving surfaces are disposed. The required length L53 in the tangential direction can be shortened. That is, as shown in FIGS. 20, 22, and 23, a plurality of light receiving surfaces B <b> 1 to B <b> 8, D <b> 1 to D <b> 8, and C <b> 1 to C <b> 4 of the light detector 53 correspond to a plurality of DVD laser beams. The light receiving surfaces D1 to D8 and the plurality of light receiving surfaces C1 to C4 corresponding to the CD laser light are arranged within the range of the width L53 in the tangential direction where the plurality of light receiving surfaces B1 to B8 corresponding to the BD laser light are present. Has been. For this reason, in Embodiment 2, there exists an effect that the chip size of the photodetector 53 can be made small. Further, as shown in FIGS. 20, 22, and 23, a plurality of light receiving surfaces B1 to B8, D1 to D8, and C1 to C4 of the light detector 53 corresponding to a plurality of DVD laser beams. The light receiving surfaces D1 to D8 and the plurality of light receiving surfaces C1 to C4 corresponding to the CD laser light have a radial width (in a direction orthogonal to L53) where the plurality of light receiving surfaces B1 to B8 corresponding to the BD laser light exist. (Length). For this reason, in Embodiment 1, the chip size in the radial direction of the photodetector 33 can also be reduced.

  Further, the function of diverging the laser beam by the blazed diffraction grating on the BD laser beam reflecting surface 51 can adjust the optical path length and optimize the size of the light spot on the photodetector 53.

  DESCRIPTION OF SYMBOLS 1, 2 Optical head apparatus, 1a, 2a Integrated optical element, 3 Spindle motor, 3a Turntable, 4 Moving part, 5 Matrix circuit, 6 Signal reproduction circuit, 7 Servo circuit, 8 Spindle control circuit, 9 Laser control circuit, 10 Thread control circuit, 11 controller, 20 support structure, 21 light source unit, 22 diffraction grating, 23 polarization beam splitter (separation element), 24 1/4 wavelength plate, 25 collimator lens, 26 objective lens, 27 movable holding part, 28 Objective lens actuator, 29 hologram (deflection element), 30 BD / CD laser light reflection surface, 31 DVD laser light reflection surface, 32,52 astigmatic optical element, 33,53 photodetector, 50 DVD / CD laser Light reflecting surface, for 51 BD Laser light reflecting surface, 60 optical disc, 61 information track, 101,401 first light beam (laser light reflected by BD), 102,402 second light beam (laser light reflected by BD), 103,403 first 104, 404 4th light beam (laser light reflected by BD), 105, 405 5th light beam (laser light reflected by BD), 106, 406 Sixth light beam (laser light reflected by BD), 107,407 seventh light beam (laser light reflected by BD), 201,501 main beam (laser light reflected by DVD), 202,502 + 1 order Sub-beam which is light (laser light reflected by DVD), 203,503 sub-beam which is primary light 301, 601 light beam (laser light reflected by CD), 291 first diffraction region, 292 second diffraction region, 293 third diffraction region, 294 fourth diffraction region, 295 first 5 diffraction region, 296 sixth diffraction region, 297 region irradiated with light beam (main beam), 298 region irradiated with overlapping light beam (sub beam), 299 layer irradiated with overlapping light beam (sub beam) B1, B2, B3, B4, B5, B6, B7, B8 Light receiving surface (or signal level), C1, C2, C3, C4 Light receiving surface (or signal level), D1, D2, D3, D4, D5 , D6, D7, D8 Photosensitive surface (or signal level), FES focus error signal (or signal level), TES track error signal (or Signal level).

Claims (18)

A light source unit that has a plurality of laser light sources, and selectively emits any one of a plurality of laser lights having different wavelengths generated by the plurality of laser light sources;
A plurality of light receiving surfaces that receive the plurality of laser beams, and each of the plurality of light receiving surfaces outputs a detection signal having a signal level corresponding to the amount of received light; and
A separation element that separates the laser light emitted from the light source unit and directed to the optical disk and the laser light reflected by the optical disk;
A deflection element that changes the traveling direction of the laser light reflected by the optical disc and separated by the separation element;
A first surface having wavelength selectivity that allows laser light of a predetermined wavelength among the plurality of laser beams to pass and reflects laser light of other wavelengths, and the predetermined wavelength that has passed through the first surface. A reflective element having a second surface for reflecting and diffracting the laser beam of
The laser light having the other wavelength that has passed through the deflection element and reflected by the first surface is incident on a corresponding light-receiving surface among the plurality of light-receiving surfaces, passes through the deflection element, and the first surface. The separation element, so that the laser beam of the predetermined wavelength that has passed through and reflected by the second surface passes through the first surface again and is incident on a corresponding light receiving surface of the photodetector, An optical integrated device comprising: the deflecting device, the reflecting device, and the photodetector.   The plurality of laser light sources are arranged so as to be laser light sources that generate laser light having a shorter wavelength as they are positioned linearly in the radial direction of the optical disc and inside the radial direction. The optical integrated device according to claim 1. The plurality of laser light sources includes a first laser light source that generates a first laser light having a first wavelength, and a second laser light that generates a second laser light having a second wavelength longer than the first wavelength. Two laser light sources, and a third laser light source that generates a third laser light having a third wavelength longer than the second wavelength,
The laser beam of the predetermined wavelength includes the second laser beam having the second wavelength,
The laser beam of the other wavelength includes the first laser beam having the first wavelength and the second laser beam having the second wavelength. The optical integrated device described. The plurality of laser light sources includes a first laser light source that generates a first laser light having a first wavelength, and a second laser light that generates a second laser light having a second wavelength longer than the first wavelength. Two laser light sources, and a third laser light source that generates a third laser light having a third wavelength longer than the second wavelength,
The laser beam of the predetermined wavelength includes the first laser beam having the first wavelength,
The laser light of the other wavelength includes the second laser light having the second wavelength and the third laser light having the third wavelength. The optical integrated device described.   Of the plurality of light receiving surfaces of the light detector, a plurality of light receiving surfaces corresponding to the second laser light and a plurality of light receiving surfaces corresponding to the third laser light are used as the first laser light. 5. The optical integrated device according to claim 3, wherein the integrated optical element is disposed within a range of a width in a tangential direction in which a plurality of corresponding light receiving surfaces exist.   The optical integrated device according to claim 1, wherein the second surface of the reflective element has a function of diverging reflected light. A light source unit that has a plurality of laser light sources, and selectively emits any one of a plurality of laser lights having different wavelengths generated by the plurality of laser light sources;
An objective lens for condensing the laser beam toward the optical disc and condensing the reflected light diffracted by the information track of the optical disc;
An objective lens actuator that receives a drive signal from the outside and shifts the objective lens at least in a radial direction of the optical disc by an amount according to the value of the drive signal;
A plurality of light receiving surfaces that receive the plurality of laser beams, and each of the plurality of light receiving surfaces outputs a detection signal having a signal level corresponding to the amount of received light; and
A separation element that separates the laser light emitted from the light source unit and directed to the optical disk and the laser light reflected by the optical disk;
A deflection element that changes the traveling direction of the laser light reflected by the optical disc and separated by the separation element;
A first surface having wavelength selectivity that allows laser light of a predetermined wavelength among the plurality of laser beams to pass and reflects laser light of other wavelengths, and the predetermined wavelength that has passed through the first surface. A reflective element having a second surface for reflecting and diffracting the laser beam of
The laser light having the other wavelength that has passed through the deflection element and reflected by the first surface is incident on a corresponding light-receiving surface among the plurality of light-receiving surfaces, passes through the deflection element, and the first surface. The separation element, so that the laser beam of the predetermined wavelength that has passed through and reflected by the second surface passes through the first surface again and is incident on a corresponding light receiving surface of the photodetector, An optical head device comprising: the deflection element, the reflection element, and the photodetector.   The plurality of laser light sources are arranged so as to be laser light sources that generate laser light having a shorter wavelength as they are positioned linearly in the radial direction of the optical disc and inside the radial direction. The optical head device according to claim 7. The plurality of laser light sources includes a first laser light source that generates a first laser light having a first wavelength, and a second laser light that generates a second laser light having a second wavelength longer than the first wavelength. Two laser light sources, and a third laser light source that generates a third laser light having a third wavelength longer than the second wavelength,
The laser beam of the predetermined wavelength includes the second laser beam having the second wavelength,
The laser light of the other wavelength includes the first laser light having the first wavelength and the second laser light having the second wavelength. The optical head device described. The plurality of laser light sources includes a first laser light source that generates a first laser light having a first wavelength, and a second laser light that generates a second laser light having a second wavelength longer than the first wavelength. Two laser light sources, and a third laser light source that generates a third laser light having a third wavelength longer than the second wavelength,
The laser beam of the predetermined wavelength includes the first laser beam having the first wavelength,
The laser light of the other wavelength includes the second laser light having the second wavelength and the third laser light having the third wavelength. The optical head device described.   Of the plurality of light receiving surfaces of the light detector, a plurality of light receiving surfaces corresponding to the second laser light and a plurality of light receiving surfaces corresponding to the third laser light are used as the first laser light. The optical head device according to claim 9, wherein the optical head device is arranged within a range of a width in a tangential direction in which a plurality of corresponding light receiving surfaces exist.   The optical head device according to claim 7, wherein the second surface of the reflective element has a function of diverging reflected light. A light source unit that has a plurality of laser light sources, and selectively emits any one of a plurality of laser lights having different wavelengths generated by the plurality of laser light sources;
An objective lens for condensing the laser beam toward the optical disc and condensing the reflected light diffracted by the information track of the optical disc;
An objective lens actuator that receives a drive signal from the outside and shifts the objective lens at least in a radial direction of the optical disc by an amount according to the value of the drive signal;
A plurality of light receiving surfaces that receive the plurality of laser beams, and each of the plurality of light receiving surfaces outputs a detection signal having a signal level corresponding to the amount of received light; and
A separation element that separates the laser light emitted from the light source unit and directed to the optical disk and the laser light reflected by the optical disk;
A deflection element that changes the traveling direction of the laser light reflected by the optical disc and separated by the separation element;
A first surface having wavelength selectivity that allows laser light of a predetermined wavelength among the plurality of laser beams to pass and reflects laser light of other wavelengths, and the predetermined wavelength that has passed through the first surface. A reflective element having a second surface for reflecting and diffracting the laser beam of
A servo circuit that sets the drive signal supplied to the objective lens actuator based on detection signals from the plurality of light receiving surfaces of the photodetector; and
The laser light having the other wavelength that has passed through the deflection element and reflected by the first surface is incident on a corresponding light-receiving surface among the plurality of light-receiving surfaces, passes through the deflection element, and the first surface. The separation element, so that the laser beam of the predetermined wavelength that has passed through and reflected by the second surface passes through the first surface again and is incident on a corresponding light receiving surface of the photodetector, An optical disc apparatus comprising: the deflection element, the reflection element, and the photodetector.   The plurality of laser light sources are arranged so as to be laser light sources that generate laser light having a shorter wavelength as they are positioned linearly in the radial direction of the optical disc and inside the radial direction. The optical disk apparatus according to claim 13. The plurality of laser light sources includes a first laser light source that generates a first laser light having a first wavelength, and a second laser light that generates a second laser light having a second wavelength longer than the first wavelength. Two laser light sources, and a third laser light source that generates a third laser light having a third wavelength longer than the second wavelength,
The laser beam of the predetermined wavelength includes the second laser beam having the second wavelength,
The laser beam of the other wavelength includes the first laser beam having the first wavelength and the second laser beam having the second wavelength. The optical disk device described. The plurality of laser light sources includes a first laser light source that generates a first laser light having a first wavelength, and a second laser light that generates a second laser light having a second wavelength longer than the first wavelength. Two laser light sources, and a third laser light source that generates a third laser light having a third wavelength longer than the second wavelength,
The laser beam of the predetermined wavelength includes the first laser beam having the first wavelength,
The laser beam of the other wavelength includes the second laser beam having the second wavelength and the third laser beam having the third wavelength. The optical disk device described.   Of the plurality of light receiving surfaces of the light detector, a plurality of light receiving surfaces corresponding to the second laser light and a plurality of light receiving surfaces corresponding to the third laser light are used as the first laser light. The optical disk apparatus according to claim 15 or 16, wherein the optical disk device is disposed within a range of a width in a tangential direction in which a plurality of corresponding light receiving surfaces exist.   18. The optical disc apparatus according to claim 13, wherein the second surface of the reflective element has a function of diverging reflected light.

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