WO2012114583A1 - Light pick-up device - Google Patents

Light pick-up device Download PDF

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Publication number
WO2012114583A1
WO2012114583A1 PCT/JP2011/075385 JP2011075385W WO2012114583A1 WO 2012114583 A1 WO2012114583 A1 WO 2012114583A1 JP 2011075385 W JP2011075385 W JP 2011075385W WO 2012114583 A1 WO2012114583 A1 WO 2012114583A1
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Prior art keywords
light
regions
spectroscopic element
region
diffraction
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PCT/JP2011/075385
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French (fr)
Japanese (ja)
Inventor
謙司 永冨
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三洋電機株式会社
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Publication of WO2012114583A1 publication Critical patent/WO2012114583A1/en

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1353—Diffractive elements, e.g. holograms or gratings
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1395—Beam splitters or combiners
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
    • G11B2007/0006—Recording, reproducing or erasing systems characterised by the structure or type of the carrier adapted for scanning different types of carrier, e.g. CD & DVD
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
    • G11B2007/0009—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage
    • G11B2007/0013—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage for carriers having multiple discrete layers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1372—Lenses
    • G11B7/1374—Objective lenses
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1372—Lenses
    • G11B7/1376—Collimator lenses

Definitions

  • the first and second regions and the third and fourth regions have different areas, and each region spreads away from the center of the spectroscopic element.
  • the spectroscopic element further imparts an optical action to the luminous flux so that when the luminous flux passing through each of the regions is irradiated onto the sensor unit, the shape of the luminous flux approaches a fan shape having an apex angle of 90 degrees. .
  • FIG. 1 is a diagram showing a light beam convergence state.
  • FIG. 6A shows a laser beam (signal light) reflected by the target recording layer, a laser beam reflected by a layer deeper than the target recording layer (stray light 1), and a layer shallower than the target recording layer. It is a figure which shows the convergence state of a laser beam (stray light 2).
  • FIG. 4B is a diagram showing the configuration of the anamorphic lens used in this principle.
  • the focal line position (M21) due to convergence in the curved surface direction is closer to the anamorphic lens than the focal line position (M22) due to convergence in the planar direction.
  • the anamorphic lens is designed so that the focal line position (M21) due to the convergence of the stray light 2 in the curved surface direction is farther from the anamorphic lens than the focal line position (S2) due to the convergence of the signal light in the planar direction.
  • the anamorphic lens is divided into four regions A to D.
  • the signal light incident on the regions A to D is distributed on the surface S0 as shown in FIG.
  • the stray light 1 incident on the regions A to D is distributed as shown in FIG. 2C on the surface S0.
  • the stray light 2 incident on the areas A to D is distributed on the surface S0 as shown in FIG.
  • FIG. 4 shows a surface when the traveling directions of the light beams (signal light, stray light 1 and 2) passing through the four areas A to D shown in FIG. 2A are changed in different directions by the same angle. It is a figure which shows the distribution state of the signal light and stray light 1 and 2 on S0.
  • 4A is a view of the anamorphic lens viewed from the optical axis direction of the anamorphic lens (the traveling direction of the laser light when the anamorphic lens is incident)
  • FIG. 4B is a distribution state of the signal light and stray light 1 and 2 on the surface S0.
  • the signal light is distributed in the state of FIG. 5C in the signal light region as described above.
  • the signal light passing through the light flux areas a to h shown in FIG. That is, the signal light passing through the light flux areas a to h in FIG. 9A is guided to the irradiation areas a to h shown in FIG. 4D on the surface S0 on which the sensor unit of the photodetector is placed.
  • FIGS. 7B and 7C are enlarged views of the left part and the upper part of the sensor layout in the signal light irradiation area on the light receiving surface when the spectroscopic element H0 is used.
  • the shapes of the sensor portions P11, P12, P13, and P14 are slightly changed for convenience in comparison with the case of FIG.
  • FIG. 8A shows the configuration of the spectroscopic element H1.
  • FIG. 4A is a plan view of the spectroscopic element H1 when viewed from the anamorphic lens side shown in FIGS.
  • FIG. 8A shows the planar direction and curved surface direction of the anamorphic lens in FIG. 1B and the direction of the track image of the laser light incident on the spectroscopic element H1.
  • FIG. 8B is a diagram showing light beam regions a1 to h1 obtained by dividing the laser light incident on the spectroscopic element H1 into eight regions so as to correspond to the boundary lines of the diffraction regions of the spectroscopic element H1.
  • FIG. 9A shows the irradiation of signal light when the laser light passing through the light flux regions a1 to h1 of FIG. 8B is irradiated to the sensor portions P11 to P18 by the spectroscopic element H1 of FIG. It is a schematic diagram which shows an area
  • FIG. 10C is an enlarged schematic diagram showing an irradiation region in the vicinity of the sensor portions P14 and P16.
  • the spectroscopic element H3 is different from the spectroscopic element H2 only in that a lens effect is given to the diffraction regions H3a to H3h. In the following, only the lens effect imparted to the diffraction regions H3a to H3h will be described for convenience.
  • the irradiation regions b3 and c3 are brought closer to each other as they approach the center of the sensor layout from the apex angle of the signal light region, and the irradiation regions f3 and g3 become closer to the center of the sensor layout from the apex angle of the signal light region. Get close to each other.
  • the optical pickup device includes a semiconductor laser 101, a half-wave plate 102, a diverging lens 103, a two-wavelength laser 104, a diffraction grating 105, a diverging lens 106, a composite prism 107, Front monitor 108, collimator lens 109, drive mechanism 110, reflection mirrors 111 and 112, quarter-wave plate 113, rising mirrors 114 and 115, two-wavelength objective lens 116, and BD objective lens 117 , A spectroscopic element H3, an anamorphic lens 118, and a photodetector 119.
  • the semiconductor laser 101 emits BD laser light (hereinafter referred to as “BD light”) having a wavelength of about 405 nm.
  • BD light BD laser light
  • the half-wave plate 102 adjusts the polarization direction of the BD light.
  • the diverging lens 103 adjusts the focal length of the BD light so as to shorten the distance between the semiconductor laser 101 and the composite prism 107.
  • the composite prism 107 has a dichroic surface 107 a and a PBS (Polarizing Beam Splitter) surface 107 b inside.
  • the dichroic surface 107a reflects BD light and transmits CD light and DVD light.
  • the semiconductor laser 101, the two-wavelength laser 104, and the composite prism 107 are arranged so that the optical axis of the BD light reflected by the dichroic surface 107a and the optical axis of the CD light transmitted through the dichroic surface 107a are aligned with each other.
  • the optical axis of the DVD light transmitted through the dichroic surface 107a is shifted from the optical axis of the BD light and the CD light by a gap G shown in FIG.
  • the front monitor 108 outputs a signal corresponding to the amount of received light.
  • a signal from the front monitor 108 is used for output power control of the semiconductor laser 101 and the two-wavelength laser 104.
  • the collimator lens 109 converts BD light, CD light, and DVD light incident from the composite prism 107 side into parallel light.
  • the drive mechanism 110 moves the collimating lens 109 in the optical axis direction according to the control signal when correcting the aberration.
  • the driving mechanism 110 includes a holder 110a that holds the collimating lens 109, and a gear 110b that sends the holder 110a in the optical axis direction of the collimating lens 109.
  • the gear 110b is connected to a driving shaft of the motor 110c.
  • BD light, CD light, and DVD light that have been converted into parallel light by the collimator lens 109 are reflected by the two reflecting mirrors 111 and 112 and enter the quarter-wave plate 113.
  • the quarter-wave plate 113 converts BD light, CD light, and DVD light incident from the reflection mirror 112 side into circularly polarized light, and reflects BD light, CD light, and DVD light incident from the rising mirror 114 side.
  • the light is converted into linearly polarized light orthogonal to the polarization direction when entering from the mirror 112 side. Thereby, the reflected light from the disk is reflected by the PBS surface 107b.
  • the rising mirror 114 is a dichroic mirror that transmits BD light and reflects CD light and DVD light in a direction toward the two-wavelength objective lens 116.
  • the rising mirror 115 reflects BD light in a direction toward the BD objective lens 117.
  • the number of steps of the diffraction pattern arranged in the diffraction regions H3a to H3i can be set to other steps.
  • the diffraction regions H3a to H3i can be configured using the technique described in Japanese Patent Application Laid-Open No. 2006-73042, for example. If this technique is used, the diffraction efficiency with respect to BD light, CD light, and DVD light can be adjusted further finely.
  • the photodetector 119 includes BD sensor units B1 to B8 that receive the BD light separated by the spectroscopic element H3, and a CD sensor that receives CD light that has not been separated by the spectroscopic element H3 and has passed through the spectroscopic element H3.
  • the signal light of the BD light separated by the spectroscopic element H3 is applied to the apex portion of the signal light region.
  • the main beam (0th order diffracted light) of the CD light is a signal of the BD light on the light receiving surface of the photodetector 119. Irradiates the center of the light region.
  • the quadrant sensor C01 is arranged at the center position of the main beam of CD light.
  • the quadrant sensors C02 and C03 are arranged on the light receiving surface of the photodetector 119 in the direction of the track image with respect to the main beam so as to receive the sub beam of CD light.
  • the diffraction regions H3b, H3c, H3f, and H3g are set to have larger areas than the diffraction regions H3a, H3d, H3e, and H3h, and the diffraction regions
  • the boundary line between H3a and H3b, the boundary line between the diffraction regions H3c and H3d, the boundary line between the diffraction regions H3e and H3f, and the boundary line between the diffraction regions H3g and H3h include a straight line portion p4.
  • the spectroscopic element H3 is disposed in front of the anamorphic lens 118.
  • the spectroscopic element H3 may be disposed in the subsequent stage of the anamorphic lens 118, or the spectroscopic element is disposed on the incident surface or the exit surface of the anamorphic lens 118.
  • a diffraction pattern that imparts the same diffractive action as that of H3 to the laser light may be integrally arranged.
  • spectroscopic elements H4 to H9 shown in FIGS. 18A to 18C, 19A, 19C, and 19D may be used.
  • the plane direction and curved surface direction of the anamorphic lens in each figure and the direction of the track image of the BD light incident on each spectroscopic element are the same as those shown in FIG. Further, the same lens effect as that of the corresponding diffraction region in FIG. 13C is given to the diffraction regions of the spectroscopic elements H4 to H9.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Head (AREA)

Abstract

[Problem] To provide a light pick-up device capable of smoothly suppressing an effect due to stray light while minimizing the degradation of a detected signal caused by the displacement of a sensor. [Solution] A dispersive element (H3) has diffraction regions (H3a to H3i). The laser light incident on the diffraction regions (H3a to H3h) is diffracted in directions (Va to Vh), respectively. The laser light incident on the diffraction regions (H3i) is diffracted so as not to be radiated on the sensor. The diffraction regions (H3a to H3h) impart a lens effect to the incident laser light in an arrow direction. Such a lens effect is set to become larger in a horizontal direction as the distance from the center is increased in the diffraction regions (H3b, H3c, H3f, H3g), and is set to become larger in a vertical direction as the distance from the center is decreased in the diffraction regions (H3a, H3d, H3e, H3h). Hereby, even if a displacement occurs in a sensor layout, a radiation region will tend to cover a sensor unit

Description

光ピックアップ装置Optical pickup device
　本発明は、光ピックアップ装置に関するものであり、特に、複数の記録層が積層された記録媒体に対してレーザ光を照射する際に用いて好適なものである。 The present invention relates to an optical pickup device, and is particularly suitable for use when irradiating a recording medium on which a plurality of recording layers are laminated with laser light.
　近年、光ディスクの大容量化に伴い、記録層の多層化が進んでいる。一枚のディスク内に複数の記録層を含めることにより、ディスクのデータ容量を顕著に高めることができる。記録層を積層する場合、これまでは片面２層が一般的であったが、最近では、さらに大容量化を進めるために、片面に３層以上の記録層が配されたディスクも実用化されている。ここで、記録層の積層数を増加させると、ディスクの大容量化を促進できる。しかし、その一方で、記録層間の間隔が狭くなり、層間クロストークによる信号劣化が増大する。 In recent years, with the increase in capacity of optical discs, the number of recording layers has been increasing. By including a plurality of recording layers in one disc, the data capacity of the disc can be remarkably increased. In the past, when recording layers were stacked, two single-sided layers were common, but recently, in order to further increase the capacity, a disc having three or more recording layers on one side has been put to practical use. ing. Here, when the number of recording layers is increased, the capacity of the disk can be increased. However, on the other hand, the interval between the recording layers is narrowed, and signal deterioration due to interlayer crosstalk increases.
　記録層を多層化すると、記録／再生対象とされる記録層（ターゲット記録層）からの反射光が微弱となる。このため、ターゲット記録層の上下にある記録層から、不要な反射光（迷光）が光検出器に入射すると、検出信号が劣化し、フォーカスサーボおよびトラッキングサーボに悪影響を及ぼす惧れがある。したがって、このように記録層が多数配されている場合には、適正に迷光を除去して、光検出器からの信号を安定化させる必要がある。 When the recording layer is multilayered, the reflected light from the recording layer (target recording layer) to be recorded / reproduced becomes weak. For this reason, when unnecessary reflected light (stray light) is incident on the photodetector from the recording layers above and below the target recording layer, the detection signal may be deteriorated, which may adversely affect the focus servo and tracking servo. Therefore, when a large number of recording layers are arranged in this way, it is necessary to properly remove stray light and stabilize the signal from the photodetector.
　以下の特許文献１には、記録層が多数配されている場合に、適正に迷光を除去し得る光ピックアップ装置の新たな構成が示されている。この構成によれば、光検出器の受光面上に、信号光のみが存在する方形状の領域（信号光領域）を作ることができる。記録媒体からの反射光は、信号光領域の頂角付近に照射される。信号光領域の頂角付近に、光検出器のセンサを配置することで、検出信号に対する迷光による影響を抑制することができる。 The following Patent Document 1 shows a new configuration of an optical pickup device that can appropriately remove stray light when a large number of recording layers are arranged. According to this configuration, a rectangular region (signal light region) where only signal light exists can be formed on the light receiving surface of the photodetector. The reflected light from the recording medium is irradiated near the apex angle of the signal light region. By arranging the sensor of the photodetector near the apex angle of the signal light region, the influence of stray light on the detection signal can be suppressed.
特開２００９－２１１７７０号公報JP 2009-2111770 A
　上記構成の光ピックアップ装置では、信号光領域の互いに向かい合う一対の頂角付近に照射される反射光の光量を、他の一対の頂角付近に照射される反射光の光量よりも大きくするのが望ましい。これにより、トラッキングエラー信号の適正化を図ることができる。かかる光量の調整は、それぞれの頂角付近に照射される反射光の面積を変えることにより実現され得る。 In the optical pickup device having the above-described configuration, the amount of reflected light irradiated near the pair of apex angles facing each other in the signal light region is set larger than the amount of reflected light irradiated near the other pair of apex angles. desirable. As a result, the tracking error signal can be optimized. Such adjustment of the amount of light can be realized by changing the area of the reflected light irradiated in the vicinity of each apex angle.
　しかし、このように反射光の面積を変えると、これに応じて反射光の形状が変わるため、各反射光の形状がセンサの形状に合い難くなる。このため、センサに位置ずれが生じると、かかる位置ずれ量に応じて検出信号が劣化する惧れがある。 However, if the area of the reflected light is changed in this way, the shape of the reflected light changes accordingly, so that the shape of each reflected light is difficult to match the shape of the sensor. For this reason, if a positional deviation occurs in the sensor, the detection signal may be degraded according to the amount of the positional deviation.
　本発明は、このような点に鑑みてなされたものであり、迷光による影響を円滑に抑制すると共に、センサの位置ずれによる検出信号の劣化を抑制することができる光ピックアップ装置を提供することを目的とする。 The present invention has been made in view of such a point, and provides an optical pickup device that can smoothly suppress the influence of stray light and suppress the deterioration of a detection signal due to a displacement of the sensor. Objective.
　本発明の主たる態様に係る光ピックアップ装置は、レーザ光源と、前記レーザ光源から出射されたレーザ光を記録媒体上に収束させる対物レンズと、前記記録媒体によって反射された前記レーザ光が入射されるとともに、第１の方向に前記レーザ光を収束させて第１の焦線を生成し、且つ、前記第１の方向に垂直な第２の方向に前記レーザ光を収束させて第２の焦線を生成する非点収差素子と、前記記録媒体によって反射された前記レーザ光が入射されるとともに、第１ないし第４の領域に入射された各光束の進行方向を互いに異ならせ、これら４つの光束を互いに離散させる分光素子と、センサ部を備えると共に当該センサ部により前記離散された各光束を受光して検出信号を出力する光検出器と、を備える。ここで、前記第１の方向と前記第２の方向にそれぞれ平行で且つ互いにクロスする第１および第２の直線の交点を前記分光素子の中心に整合させたとき、前記第１および第２の直線によって作られる一組の対頂角が並ぶ方向に前記第１および第２の領域が配置され、他の一組の対頂角が並ぶ方向に前記第３および第４の領域が配置され、前記第１および第２の領域が並ぶ方向が、前記分光素子に投影された前記記録媒体のトラック像の方向と平行となるように前記非点収差素子が配置される。前記第１および第２の領域と前記第３および第４の領域とは互いに面積が異なり、各領域は、前記分光素子の中心から離れるに従って広がっている。前記分光素子は、さらに、前記各領域を通る光束が前記センサ部に照射されるときに、これら光束の形状が頂角を９０度とする扇形に近づくように、これら光束に光学作用を付与する。 An optical pickup device according to a main aspect of the present invention is configured to receive a laser light source, an objective lens that converges laser light emitted from the laser light source on a recording medium, and the laser light reflected by the recording medium At the same time, the laser beam is converged in a first direction to generate a first focal line, and the laser beam is converged in a second direction perpendicular to the first direction to generate a second focal line. The astigmatism element for generating the laser beam and the laser beam reflected by the recording medium are incident, and the traveling directions of the light beams incident on the first to fourth regions are made different from each other. And a photodetector that includes a sensor unit and receives each of the light beams dispersed by the sensor unit and outputs a detection signal. Here, when the intersection of the first and second straight lines that are parallel to and cross each other in the first direction and the second direction are aligned with the center of the spectroscopic element, the first and second The first and second regions are arranged in a direction in which a set of vertical angles formed by a straight line are arranged, and the third and fourth regions are arranged in a direction in which the other set of vertical angles are arranged, The astigmatism element is arranged so that the direction in which the second regions are arranged is parallel to the direction of the track image of the recording medium projected onto the spectroscopic element. The first and second regions and the third and fourth regions have different areas, and each region spreads away from the center of the spectroscopic element. The spectroscopic element further imparts an optical action to the luminous flux so that when the luminous flux passing through each of the regions is irradiated onto the sensor unit, the shape of the luminous flux approaches a fan shape having an apex angle of 90 degrees. .
　本発明によれば、迷光による影響を円滑に抑制すると共に、センサの位置ずれによる検出信号の劣化を抑制することができる光ピックアップ装置を提供することができる。 According to the present invention, it is possible to provide an optical pickup device that can smoothly suppress the influence of stray light and suppress the deterioration of the detection signal due to the displacement of the sensor.
　本発明の効果ないし意義は、以下に示す実施の形態の説明により更に明らかとなろう。ただし、以下の実施の形態は、あくまでも、本発明を実施する際の一つの例示であって、本発明は、以下の実施の形態によって何ら制限されるものではない。 The effect or significance of the present invention will become more apparent from the following description of embodiments. However, the following embodiment is merely an example for carrying out the present invention, and the present invention is not limited by the following embodiment.
実施の形態に係る技術原理（光線の収束状態）を説明する図である。It is a figure explaining the technical principle (convergence state of a light ray) which concerns on embodiment. 実施の形態に係る技術原理（光束の分布状態）を説明する図である。It is a figure explaining the technical principle (distribution state of a light beam) which concerns on embodiment. 実施の形態に係る技術原理（信号光と迷光の分布状態）を説明する図である。It is a figure explaining the technical principle (distribution state of signal light and stray light) concerning an embodiment. 実施の形態に係る技術原理（光束の分離方法）を説明する図である。It is a figure explaining the technical principle (separation method of a light beam) which concerns on embodiment. 実施の形態に係るセンサ部の配置方法を示す図である。It is a figure which shows the arrangement | positioning method of the sensor part which concerns on embodiment. 実施の形態に係る技術原理の好ましい適用範囲を示す図である。It is a figure which shows the preferable application range of the technical principle which concerns on embodiment. 実施の形態に係る技術原理に基づく分光素子の例示図である。It is an illustration figure of the spectroscopic element based on the technical principle which concerns on embodiment. 実施の形態に係る技術原理に基づく分光素子の例示図である。It is an illustration figure of the spectroscopic element based on the technical principle which concerns on embodiment. 実施の形態に係る技術原理に基づくセンサ部上の照射領域を示す図およびプッシュプル信号を生成するための演算回路の例示図である。It is a figure which shows the irradiation area | region on the sensor part based on the technical principle which concerns on embodiment, and an illustration figure of the arithmetic circuit for producing | generating a push pull signal. 実施の形態に係る技術原理に基づくセンサ部上の照射領域を示す図および信号光と迷光との干渉について説明する図である。It is a figure which shows the irradiation area | region on the sensor part based on the technical principle which concerns on embodiment, and a figure explaining interference with a signal light and a stray light. 実施の形態に係る技術原理に基づく照射領域のシミュレーション結果を示す図である。It is a figure which shows the simulation result of the irradiation area | region based on the technical principle which concerns on embodiment. 実施の形態に係る技術原理に基づくセンサレイアウトの位置ずれが生じた状態を示す図である。It is a figure which shows the state which the position shift of the sensor layout based on the technical principle which concerns on embodiment produced. 実施の形態に係る技術原理に基づく分光素子の例示図、レンズ効果を説明する図およびセンサ部上の照射領域を示す図である。It is an illustration figure of the spectroscopic element based on the technical principle which concerns on embodiment, the figure explaining a lens effect, and the figure which shows the irradiation area | region on a sensor part. 実施の形態に係る技術原理に基づく照射領域のシミュレーション結果を示す図である。It is a figure which shows the simulation result of the irradiation area | region based on the technical principle which concerns on embodiment. 実施の形態に係る技術原理に基づくセンサレイアウトの位置ずれが生じた状態を示す図である。It is a figure which shows the state which the position shift of the sensor layout based on the technical principle which concerns on embodiment produced. 実施例に係る光ピックアップ装置の光学系を示す図である。It is a figure which shows the optical system of the optical pick-up apparatus which concerns on an Example. 実施例に係る光検出器のセンサレイアウトを示す図である。It is a figure which shows the sensor layout of the photodetector which concerns on an Example. 実施例に係る分光素子の変更例を示す図である。It is a figure which shows the example of a change of the spectroscopic element which concerns on an Example. 実施例に係る分光素子の変更例を示す図である。It is a figure which shows the example of a change of the spectroscopic element which concerns on an Example.
　以下、本発明の実施の形態につき図面を参照して説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
　＜技術的原理＞
　まず、図１ないし図６を参照して、本実施の形態に適用される技術的原理について説明する。 <Technical principle>
First, the technical principle applied to this embodiment will be described with reference to FIGS.
　図１は、光線の収束状態を示す図である。同図（ａ）は、ターゲット記録層によって反射されたレーザ光（信号光）、ターゲット記録層よりも深い層によって反射されたレーザ光（迷光１）、ターゲット記録層よりも浅い層によって反射されたレーザ光（迷光２）の収束状態を示す図である。同図（ｂ）は、本原理に用いるアナモレンズの構成を示す図である。 FIG. 1 is a diagram showing a light beam convergence state. FIG. 6A shows a laser beam (signal light) reflected by the target recording layer, a laser beam reflected by a layer deeper than the target recording layer (stray light 1), and a layer shallower than the target recording layer. It is a figure which shows the convergence state of a laser beam (stray light 2). FIG. 4B is a diagram showing the configuration of the anamorphic lens used in this principle.
　同図（ｂ）を参照して、アナモレンズは、レンズ光軸に平行に入射するレーザ光に対し、曲面方向と平面方向に収束作用を付与する。ここで、曲面方向と平面方向は、互いに直交している。また、曲面方向は、平面方向に比べ曲率半径が小さく、アナモレンズに入射するレーザ光を収束させる効果が大きい。 Referring to FIG. 5B, the anamorphic lens imparts a converging action in the curved surface direction and the planar direction to the laser light incident parallel to the lens optical axis. Here, the curved surface direction and the planar direction are orthogonal to each other. Further, the curved surface direction has a smaller radius of curvature than the planar direction, and has a large effect of converging the laser light incident on the anamorphic lens.
　なお、ここでは、アナモレンズにおける非点収差作用を簡単に説明するために、便宜上、“曲面方向”と“平面方向”と表現しているが、実際には、互いに異なる位置に焦線を結ぶ作用がアナモレンズによって生じれば良く、図１（ｂ）中の“平面方向”におけるアナモレンズの形状を平面に限定するものではない。なお、アナモレンズに収束状態でレーザ光が入射する場合は、“平面方向”におけるアナモレンズの形状は直線状（曲率半径＝∞）となり得る。 Here, in order to simply explain the astigmatism action in the anamorphic lens, for the sake of convenience, they are expressed as “curved surface direction” and “planar direction”, but in reality, the action of connecting the focal lines to different positions. However, the shape of the anamorphic lens in the “planar direction” in FIG. 1B is not limited to a plane. When laser light is incident on the anamorphic lens in a convergent state, the shape of the anamorphic lens in the “plane direction” can be a straight line (curvature radius = ∞).
　同図（ａ）を参照して、アナモレンズによって収束させられた信号光は、曲面方向および平面方向の収束により、それぞれ異なる位置で焦線を結ぶ。曲面方向の収束による焦線位置（Ｓ１）は、平面方向の収束による焦線位置（Ｓ２）よりも、アナモレンズに近い位置となり、信号光の収束位置（Ｓ０）は、曲面方向および平面方向による焦線位置（Ｓ１）、（Ｓ２）の中間位置となる。 Referring to FIG. 5A, the signal light converged by the anamorphic lens forms focal lines at different positions due to convergence in the curved surface direction and the planar direction. The focal line position (S1) due to the convergence in the curved surface direction is closer to the anamorphic lens than the focal line position (S2) due to the convergence in the planar direction, and the convergence position (S0) of the signal light is the focal position in the curved surface direction and the planar direction. This is an intermediate position between the line positions (S1) and (S2).
　アナモレンズによって収束させられた迷光１についても同様に、曲面方向の収束による焦線位置（Ｍ１１）は、平面方向の収束による焦線位置（Ｍ１２）よりも、アナモレンズに近い位置となる。アナモレンズは、迷光１の平面方向の収束による焦線位置（Ｍ１２）が、信号光の曲面方向の収束による焦線位置（Ｓ１）よりも、アナモレンズに近い位置となるよう、設計されている。 Similarly, for the stray light 1 converged by the anamorphic lens, the focal line position (M11) due to convergence in the curved surface direction is closer to the anamorphic lens than the focal line position (M12) due to convergence in the planar direction. The anamorphic lens is designed such that the focal line position (M12) due to the convergence of the stray light 1 in the plane direction is closer to the anamorphic lens than the focal line position (S1) due to the convergence of the signal light in the curved surface direction.
　アナモレンズによって収束させられた迷光２についても同様に、曲面方向の収束による焦線位置（Ｍ２１）は、平面方向の収束による焦線位置（Ｍ２２）よりも、アナモレンズに近い位置となる。アナモレンズは、迷光２の曲面方向の収束による焦線位置（Ｍ２１）は、信号光の平面方向の収束による焦線位置（Ｓ２）よりも、アナモレンズから遠い位置となるよう、設計されている。 Similarly, for the stray light 2 converged by the anamorphic lens, the focal line position (M21) due to convergence in the curved surface direction is closer to the anamorphic lens than the focal line position (M22) due to convergence in the planar direction. The anamorphic lens is designed so that the focal line position (M21) due to the convergence of the stray light 2 in the curved surface direction is farther from the anamorphic lens than the focal line position (S2) due to the convergence of the signal light in the planar direction.
　また、焦線位置（Ｓ１）と焦線位置（Ｓ２）の間の収束位置（Ｓ０）において、信号光のビームが最小錯乱円となる。 In addition, at the convergence position (S0) between the focal line position (S1) and the focal line position (S2), the signal light beam becomes a minimum circle of confusion.
　以上を考慮して、面Ｓ０上における信号光および迷光１、２の照射領域の関係について検討する。 Considering the above, the relationship between the irradiation area of the signal light and the stray light 1 and 2 on the surface S0 will be examined.
　ここでは、図２（ａ）に示すように、アナモレンズが、４つの領域Ａ～Ｄに区分される。この場合、領域Ａ～Ｄに入射した信号光は、面Ｓ０上において、図２（ｂ）のように分布する。また、領域Ａ～Ｄに入射した迷光１は、面Ｓ０上において、図２（ｃ）のように分布する。領域Ａ～Ｄに入射した迷光２は、面Ｓ０上において、図２（ｄ）のように分布する。 Here, as shown in FIG. 2A, the anamorphic lens is divided into four regions A to D. In this case, the signal light incident on the regions A to D is distributed on the surface S0 as shown in FIG. Further, the stray light 1 incident on the regions A to D is distributed as shown in FIG. 2C on the surface S0. The stray light 2 incident on the areas A to D is distributed on the surface S0 as shown in FIG.
　ここで、面Ｓ０上における信号光と迷光１、２を光束領域毎に取り出すと、各光の分布は、図３（ａ）ないし（ｄ）のようになる。この場合、各光束領域の信号光には、同じ光束領域の迷光１および迷光２の何れも重ならない。このため、各光束領域内の光束（信号光、迷光１、２）を異なる方向に離散させた後に、信号光のみをセンサ部にて受光するように構成すると、対応するセンサ部には信号光のみが入射し、迷光の入射を抑止することができる。これにより、迷光による検出信号の劣化を回避することができる。 Here, when the signal light and the stray lights 1 and 2 on the surface S0 are extracted for each light flux region, the distribution of each light is as shown in FIGS. 3 (a) to 3 (d). In this case, the stray light 1 and the stray light 2 in the same light flux region do not overlap with the signal light in each light flux region. For this reason, when the light beams (signal light, stray light 1 and 2) in each light beam region are dispersed in different directions and then only the signal light is received by the sensor unit, the corresponding sensor unit receives the signal light. Only incident light can be input, and the incidence of stray light can be suppressed. Thereby, degradation of the detection signal due to stray light can be avoided.
　このように、領域Ａ～Ｄを通る光を分散させて面Ｓ０上において離間させることにより、信号光のみを取り出すことができる。本実施の形態は、この原理を基盤とするものである。 Thus, only the signal light can be extracted by dispersing the light passing through the regions A to D and separating them on the surface S0. The present embodiment is based on this principle.
　図４は、図２（ａ）に示す４つの領域Ａ～Ｄを通る光束（信号光、迷光１、２）の進行方向を、それぞれ、異なる方向に、同じ角度だけ変化させたときの、面Ｓ０上における信号光と迷光１、２の分布状態を示す図である。図４（ａ）は、アナモレンズの光軸方向（アナモレンズ入射時のレーザ光の進行方向）からアナモレンズを見た図、同図（ｂ）は、面Ｓ０における信号光、迷光１、２の分布状態を示す図である。 FIG. 4 shows a surface when the traveling directions of the light beams (signal light, stray light 1 and 2) passing through the four areas A to D shown in FIG. 2A are changed in different directions by the same angle. It is a figure which shows the distribution state of the signal light and stray light 1 and 2 on S0. 4A is a view of the anamorphic lens viewed from the optical axis direction of the anamorphic lens (the traveling direction of the laser light when the anamorphic lens is incident), and FIG. 4B is a distribution state of the signal light and stray light 1 and 2 on the surface S0. FIG.
　同図（ａ）では、領域Ａ～Ｄを通った光束（信号光、迷光１、２）の進行方向が、入射前の各光束の進行方向に対して、それぞれ、方向Ｄａ、Ｄｂ、Ｄｃ、Ｄｄに、同じ角度量α（図示せず）だけ変化する。なお、方向Ｄａ、Ｄｂ、Ｄｃ、Ｄｄは、平面方向と曲面方向に対して、それぞれ、４５度の傾きを持っている。 In FIG. 6A, the traveling directions of the light beams (signal light, stray light 1 and 2) that have passed through the regions A to D are the directions Da, Db, Dc, Dd changes by the same angular amount α (not shown). The directions Da, Db, Dc, and Dd have an inclination of 45 degrees with respect to the plane direction and the curved surface direction, respectively.
　この場合、方向Ｄａ、Ｄｂ、Ｄｃ、Ｄｄにおける角度量αを調節することにより、面Ｓ０上において、同図（ｂ）に示すように各光束領域の信号光と迷光１、２を分布させることができる。その結果、図示の如く、信号光のみが存在する信号光領域を面Ｓ０上に設定することができる。この信号光領域に光検出器の複数のセンサ部を配置することにより、各領域の信号光のみを、対応するセンサ部にて受光することができる。 In this case, by adjusting the angle amount α in the directions Da, Db, Dc, and Dd, the signal light and the stray lights 1 and 2 in each light flux region are distributed on the surface S0 as shown in FIG. Can do. As a result, as shown in the figure, it is possible to set a signal light region where only signal light exists on the surface S0. By arranging a plurality of sensor portions of the photodetector in this signal light region, only the signal light in each region can be received by the corresponding sensor portion.
　図５は、センサ部の配置方法を説明する図である。同図（ａ）は、ディスクからの反射光（信号光）の光束領域を示す図であり、同図（ｂ）は、図１（ａ）の構成において、アナモレンズの配置位置と面Ｓ０に、それぞれ、アナモレンズと、従来の非点収差法に基づく光検出器（４分割センサ）を配置したときの、光検出器上における信号光の分布状態を示す図である。図５（ｃ）および（ｄ）は、面Ｓ０上における、上述の原理に基づく信号光の分布状態とセンサレイアウトを示す図である。 FIG. 5 is a diagram illustrating a method for arranging the sensor units. FIG. 4A is a diagram showing a light flux region of reflected light (signal light) from the disk, and FIG. 4B shows the arrangement position of the anamorphic lens and the surface S0 in the configuration of FIG. It is a figure which shows the distribution state of the signal beam | light on a photodetector when each arrange | positions the anamorphic lens and the photodetector (4-part dividing sensor) based on the conventional astigmatism method. FIGS. 5C and 5D are diagrams showing a signal light distribution state and a sensor layout based on the above-described principle on the surface S0.
　トラック溝による信号光の回折の像（トラック像）の方向は、平面方向および曲面方向に対して４５度の傾きを持っている。同図（ａ）において、トラック像の方向が左右方向であるとすると、同図（ｂ）ないし（ｄ）では、信号光におけるトラック像の方向は、上下方向となる。なお、同図（ａ）には、説明の便宜上、光束が８つの光束領域ａ～ｈに区分されており、同図（ｂ）、（ｄ）には、光束領域ａ～ｈにそれぞれ対応するセンサ部上の照射領域ａ～ｈが示されている。また、トラック像が実線で示され、オフフォーカス時のビーム形状が点線によって示されている。 The direction of the signal light diffraction image (track image) by the track groove has an inclination of 45 degrees with respect to the plane direction and the curved surface direction. If the direction of the track image is the left-right direction in FIG. 6A, the direction of the track image in the signal light is the vertical direction in FIGS. For convenience of explanation, the light beam is divided into eight light beam regions a to h in FIG. 5A, and FIGS. 4B and 4D correspond to the light beam regions a to h, respectively. Illuminated areas a to h on the sensor unit are shown. Further, the track image is indicated by a solid line, and the beam shape at the time of off-focus is indicated by a dotted line.
　なお、トラック溝による信号光の０次回折像と一次回折像の重なり状態は、波長／（トラックピッチ×対物レンズＮＡ）で求められることが知られており、同図（ａ）、（ｂ）、（ｄ）のように、４つの光束領域ａ、ｄ、ｅ、ｈに一次回折像が収まる条件は、波長／（トラックピッチ×対物レンズＮＡ）＞√２となる。 It is known that the overlapping state of the 0th-order diffraction image and the first-order diffraction image of the signal light by the track groove is obtained by wavelength / (track pitch × objective lens NA), and FIGS. , (D), the condition that the first-order diffraction image fits in the four light flux regions a, d, e, and h is wavelength / (track pitch × objective lens NA)> √2.
　従来の非点収差法では、光検出器のセンサ部Ｐ１～Ｐ４（４分割センサ）が同図（ｂ）のように設定される。この場合、光束領域ａ～ｈの光強度に基づく検出信号成分をＡ～Ｈで表すと、フォーカスエラー信号ＦＥとプッシュプル信号ＰＰは、
　ＦＥ＝（Ａ＋Ｂ＋Ｅ＋Ｆ）－（Ｃ＋Ｄ＋Ｇ＋Ｈ）　　…（１）
　ＰＰ＝（Ａ＋Ｂ＋Ｇ＋Ｈ）－（Ｃ＋Ｄ＋Ｅ＋Ｆ）　　…（２）
の演算により求まる。 In the conventional astigmatism method, the sensor portions P1 to P4 (quadrant sensor) of the photodetector are set as shown in FIG. In this case, when the detection signal components based on the light intensities in the light flux regions a to h are represented by A to H, the focus error signal FE and the push-pull signal PP are
FE = (A + B + E + F) − (C + D + G + H) (1)
PP = (A + B + G + H) − (C + D + E + F) (2)
It is obtained by the operation of
　これに対し、上記図４（ｂ）の分布状態では、上述の如く、信号光領域内に、図５（ｃ）の状態で信号光が分布している。この場合、同図（ａ）に示す光束領域ａ～ｈを通る信号光は、同図（ｄ）のようになる。すなわち、同図（ａ）の光束領域ａ～ｈを通る信号光は、光検出器のセンサ部が置かれる面Ｓ０上では、同図（ｄ）に示す照射領域ａ～ｈへと導かれる。 On the other hand, in the distribution state of FIG. 4B, the signal light is distributed in the state of FIG. 5C in the signal light region as described above. In this case, the signal light passing through the light flux areas a to h shown in FIG. That is, the signal light passing through the light flux areas a to h in FIG. 9A is guided to the irradiation areas a to h shown in FIG. 4D on the surface S0 on which the sensor unit of the photodetector is placed.
　したがって、同図（ｄ）に示す照射領域ａ～ｈの位置に、同図（ｄ）に重ねて示す如くセンサ部Ｐ１１～Ｐ１８を配置すれば、同図（ｂ）の場合と同様の演算処理によって、フォーカスエラー信号とプッシュプル信号を生成することができる。すなわち、この場合も、光束領域ａ～ｈの光束を受光するセンサ部からの検出信号をＡ～Ｈで表すと、同図（ｂ）の場合と同様、フォーカスエラー信号ＦＥとプッシュプル信号ＰＰは、上記式（１）、（２）の演算により取得することができる。 Therefore, if the sensor portions P11 to P18 are arranged at the positions of the irradiation areas a to h shown in FIG. 4D, as shown in FIG. 4D, the same arithmetic processing as in FIG. Thus, a focus error signal and a push-pull signal can be generated. That is, also in this case, when the detection signals from the sensor units that receive the light beams in the light beam regions a to h are represented by A to H, the focus error signal FE and the push-pull signal PP are expressed as in the case of FIG. , And can be obtained by the calculations of the above formulas (1) and (2).
　以上のように、本原理によれば、従来の非点収差法に基づく場合と同様の演算処理にて、迷光の影響が抑制されたフォーカスエラー信号とプッシュプル信号（トラッキングエラー信号）を生成することができる。 As described above, according to the present principle, the focus error signal and the push-pull signal (tracking error signal) in which the influence of stray light is suppressed are generated by the same arithmetic processing based on the conventional astigmatism method. be able to.
　なお、上記原理による効果は、図６に示すように、迷光１の平面方向の焦線位置が面Ｓ０（信号光のスポットが最小錯乱円となる面）よりも非点収差素子に接近した位置にあり、且つ、迷光２の曲面方向の焦線位置が面Ｓ０よりも非点収差素子から離れた位置にあるときに奏され得るものである。すなわち、この関係が満たされていれば、信号光と迷光１、２の分布は上記図４に示す状態となり、面Ｓ０において、信号光と迷光１、２が重なり合わないようすることができる。換言すれば、この関係が満たされる限り、たとえ、信号光の曲面方向の焦線位置よりも迷光１の平面方向の焦線位置が面Ｓ０に接近し、あるいは、信号光の平面方向の焦線位置よりも迷光２の曲面方向の焦線位置が面Ｓ０に接近したとしても、上記原理に基づく効果は奏され得る。 The effect of the above principle is that, as shown in FIG. 6, the position of the focal line in the plane direction of the stray light 1 is closer to the astigmatism element than the surface S0 (the surface where the spot of signal light is the minimum circle of confusion). And the focal line position of the stray light 2 in the curved surface direction can be achieved when the position is farther from the astigmatism element than the surface S0. That is, if this relationship is satisfied, the distribution of the signal light and the stray lights 1 and 2 is in the state shown in FIG. 4, and the signal light and the stray lights 1 and 2 can be prevented from overlapping on the plane S0. In other words, as long as this relationship is satisfied, the focal line position in the plane direction of the stray light 1 is closer to the plane S0 than the focal line position in the curved surface direction of the signal light, or the focal line in the plane direction of the signal light is Even if the focal line position in the curved surface direction of the stray light 2 rather than the position approaches the surface S0, the effect based on the above principle can be achieved.
　＜分光素子Ｈ０＞
　図７（ａ）は、領域Ａ～Ｄに入射した光束の進行方向を図４（ａ）に示すように変化させるための分光素子Ｈ０の構成を示す図である。図７（ａ）は、分光素子Ｈ０を図１（ａ）、（ｂ）に示したアナモレンズ側から見たときの平面図である。図７（ａ）には、図１（ｂ）のアナモレンズの平面方向、曲面方向と、分光素子Ｈ０に入射するレーザ光のトラック像の方向が併せて示されている。 <Spectroscopic element H0>
FIG. 7A is a diagram showing the configuration of the spectroscopic element H0 for changing the traveling direction of the light beam incident on the regions A to D as shown in FIG. 4A. FIG. 7A is a plan view when the spectroscopic element H0 is viewed from the anamorphic lens side shown in FIGS. 1A and 1B. FIG. 7A shows the planar direction and curved surface direction of the anamorphic lens in FIG. 1B and the direction of the track image of the laser light incident on the spectroscopic element H0.
　図示の如く、分光素子Ｈ０は、正方形形状の透明板にて形成され、光入射面に回折パターン（回折ホログラム）が形成されている。分光素子Ｈ０の光入射面は、４つの回折領域Ｈ０ａ～Ｈ０ｄに区分されており、分光素子Ｈ０の境界線はトラック像の方向に対して４５度となっている。これら回折領域Ｈ０ａ～Ｈ０ｄに、それぞれ、図４（ａ）の光束領域Ａ～Ｄを通るレーザ光が入射するよう、分光素子Ｈ０が配置される。回折領域Ｈ０ａ～Ｈ０ｄは、入射されたレーザ光を回折作用により、それぞれ図４（ａ）の方向Ｄａ～Ｄｄに回折させる。 As shown in the figure, the spectroscopic element H0 is formed of a square-shaped transparent plate, and a diffraction pattern (diffraction hologram) is formed on the light incident surface. The light incident surface of the spectroscopic element H0 is divided into four diffraction regions H0a to H0d, and the boundary line of the spectroscopic element H0 is 45 degrees with respect to the direction of the track image. The spectroscopic element H0 is arranged so that the laser beams passing through the light flux areas A to D in FIG. 4A are incident on the diffraction areas H0a to H0d, respectively. The diffraction regions H0a to H0d diffract the incident laser light in the directions Da to Dd in FIG.
　図７（ｂ）、（ｃ）は、分光素子Ｈ０を用いた場合の受光面上における信号光の照射領域について、センサレイアウトの左側部分と上側部分を拡大した図である。同図では、センサ部Ｐ１１、Ｐ１２、Ｐ１３、Ｐ１４の形状が、便宜上、図５（ｄ）の場合に比べやや変更されている。 FIGS. 7B and 7C are enlarged views of the left part and the upper part of the sensor layout in the signal light irradiation area on the light receiving surface when the spectroscopic element H0 is used. In the figure, the shapes of the sensor portions P11, P12, P13, and P14 are slightly changed for convenience in comparison with the case of FIG.
　分光素子Ｈ０が用いられる場合には、図示の如く、各センサ部に照射される光束の形状は、頂角を９０度とする扇形となる。このため、センサ部Ｐ１１、Ｐ１２、Ｐ１４、Ｐ１６が破線に示す位置にずれても、照射領域ａ、ｈの頂角部分はセンサ部Ｐ１１、Ｐ１２の頂角部分に略隙間なく位置付けられ、照射領域ｂ、ｃの頂角部分は、センサ部Ｐ１４、Ｐ１６の頂角部分に略隙間なく位置付けられる。すなわち、センサレイアウトの位置ずれが生じても、図示の如く、照射領域がセンサ部からはみ出さない。このため、検出信号の精度の低下が抑制され得る。 When the spectroscopic element H0 is used, as shown in the figure, the shape of the light beam applied to each sensor unit is a fan shape with an apex angle of 90 degrees. For this reason, even if the sensor parts P11, P12, P14, and P16 are displaced to the positions indicated by the broken lines, the apex angle portions of the irradiation areas a and h are positioned without substantial gaps in the apex angle parts of the sensor parts P11 and P12. The apex angle portions of b and c are positioned without substantial gaps at the apex angle portions of the sensor portions P14 and P16. That is, even if the position of the sensor layout is displaced, the irradiation area does not protrude from the sensor unit as shown in the figure. For this reason, a decrease in the accuracy of the detection signal can be suppressed.
　＜分光素子Ｈ１＞
　分光素子Ｈ０は、以下のように変更・改良され得る。なお、このような分光素子の構成、作用、効果の詳細は、本件出願人が先に出願した特願２０１０－２２２４２２号に記載されている。 <Spectroscopic element H1>
The spectroscopic element H0 can be changed or improved as follows. Details of the configuration, operation, and effect of such a spectroscopic element are described in Japanese Patent Application No. 2010-222422 filed earlier by the present applicant.
　図８（ａ）は、分光素子Ｈ１の構成を示す図である。同図（ａ）は、分光素子Ｈ１を図１（ａ）、（ｂ）に示したアナモレンズ側から見たときの平面図である。図８（ａ）には、図１（ｂ）のアナモレンズの平面方向、曲面方向と、分光素子Ｈ１に入射するレーザ光のトラック像の方向が併せて示されている。図８（ｂ）は、分光素子Ｈ１に入射するレーザ光を、分光素子Ｈ１の回折領域の境界線に対応するよう、８つの領域に区分した光束領域ａ１～ｈ１を示す図である。 FIG. 8A shows the configuration of the spectroscopic element H1. FIG. 4A is a plan view of the spectroscopic element H1 when viewed from the anamorphic lens side shown in FIGS. FIG. 8A shows the planar direction and curved surface direction of the anamorphic lens in FIG. 1B and the direction of the track image of the laser light incident on the spectroscopic element H1. FIG. 8B is a diagram showing light beam regions a1 to h1 obtained by dividing the laser light incident on the spectroscopic element H1 into eight regions so as to correspond to the boundary lines of the diffraction regions of the spectroscopic element H1.
　図８（ａ）を参照して、分光素子Ｈ１の光入射面は、図示の如く、８つの回折領域Ｈ１ａ～Ｈ１ｈに区分されている。回折領域Ｈ１ａ、Ｈ１ｄ、Ｈ１ｅ、Ｈ１ｈは、面積が互いに等しく、また、回折領域Ｈ１ｂ、Ｈ１ｃ、Ｈ１ｆ、Ｈ１ｇは、面積が互いに等しい。回折領域Ｈ１ｂ、Ｈ１ｃ、Ｈ１ｆ、Ｈ１ｇは、それぞれ、回折領域Ｈ１ａＨ１ｄ、Ｈ１ｅ、Ｈ１ｈ、よりも、面積が大きい。 Referring to FIG. 8A, the light incident surface of the spectroscopic element H1 is divided into eight diffraction regions H1a to H1h as shown. The diffraction regions H1a, H1d, H1e, and H1h have the same area, and the diffraction regions H1b, H1c, H1f, and H1g have the same area. The diffraction regions H1b, H1c, H1f, and H1g each have a larger area than the diffraction regions H1aH1d, H1e, and H1h.
　回折領域Ｈ１ａ～Ｈ１ｈは、入射されたレーザ光を回折作用により、それぞれ方向Ｖａ～Ｖｈに回折させる。方向Ｖａ、Ｖｈは、図４（ａ）の方向Ｄａから、それぞれ、図示の如く、下方向と上方向の成分が僅かに加えられている。同様に、方向Ｖｆ、Ｖｇは、図４（ａ）の方向Ｄｂから、それぞれ、図示の如く、左方向と右方向の成分が僅かに加えられている。また、方向Ｖｂ、Ｖｃは、図４（ａ）の方向Ｄｃから、それぞれ、図示の如く、右方向と左方向の成分が僅かに加えられている。また、方向Ｖｄ、Ｖｅは、図４（ａ）の方向Ｄｄから、それぞれ、図示の如く、下方向と上方向の成分が僅かに加えられている。 The diffraction regions H1a to H1h diffract the incident laser light in directions Va to Vh, respectively, by the diffraction action. In the directions Va and Vh, components in the downward direction and the upward direction are slightly added from the direction Da in FIG. Similarly, in the directions Vf and Vg, components in the left direction and the right direction are slightly added from the direction Db in FIG. Further, in the directions Vb and Vc, components in the right direction and the left direction are slightly added from the direction Dc in FIG. Further, in the directions Vd and Ve, the components in the downward direction and the upward direction are slightly added from the direction Dd in FIG.
　分光素子Ｈ１の回折領域Ｈ１ａ、Ｈ１ｄ、Ｈ１ｅ、Ｈ１ｈと回折領域Ｈ１ｂ、Ｈ１ｃ、Ｈ１ｆ、Ｈ１ｇとの境界線は、上下方向に延びた直線部ｐ１、ｐ２、ｐ３を有し、これら直線部間の境界線は、上下左右方向に対して４５度の角度を有する直線となっている。 The boundary lines between the diffraction regions H1a, H1d, H1e, and H1h of the spectroscopic element H1 and the diffraction regions H1b, H1c, H1f, and H1g have linear portions p1, p2, and p3 extending in the vertical direction. The boundary line is a straight line having an angle of 45 degrees with respect to the vertical and horizontal directions.
　分光素子Ｈ１は、中心をレーザ光の光軸が貫くように配置され、図８（ｂ）に示した光束領域ａ１～ｈ１は、それぞれ、回折領域Ｈ１ａ～Ｈ１ｈに入射する。このとき、分光素子Ｈ１に入射する光束に含まれるトラック像が、分光素子Ｈ１の直線部ｐ２に十分掛かるよう、分光素子Ｈ１の境界線が設定されている。これにより、回折領域Ｈ１ａ、Ｈ１ｄ上における光束領域ａ１、ｄ１の照射領域は、回折領域Ｈ１ｂ、Ｈ１ｃ上における光束領域ｂ１、ｃ１の照射領域よりも小さくなる。同様に、回折領域Ｈ１ｅ、Ｈ１ｈ上における光束領域ｅ１、ｈ１の照射領域は、回折領域Ｈ１ｆ、Ｈ１ｇ上における光束領域ｆ１、ｇ１の照射領域よりも小さくなる。 The spectroscopic element H1 is arranged so that the optical axis of the laser beam passes through the center, and the light beam regions a1 to h1 shown in FIG. 8B are incident on the diffraction regions H1a to H1h, respectively. At this time, the boundary line of the spectroscopic element H1 is set so that the track image included in the light beam incident on the spectroscopic element H1 is sufficiently applied to the linear portion p2 of the spectroscopic element H1. Thereby, the irradiation areas of the light flux areas a1 and d1 on the diffraction areas H1a and H1d are smaller than the irradiation areas of the light flux areas b1 and c1 on the diffraction areas H1b and H1c. Similarly, the irradiation regions of the light beam regions e1 and h1 on the diffraction regions H1e and H1h are smaller than the irradiation regions of the light beam regions f1 and g1 on the diffraction regions H1f and H1g.
　図９（ａ）は、図８（ｂ）の光束領域ａ１～ｈ１を通るレーザ光が、図８（ａ）の分光素子Ｈ１により、センサ部Ｐ１１～Ｐ１８に照射されるときの信号光の照射領域を示す模式図である。なお、光束領域ａ１～ｈ１を通る信号光の照射領域は、照射領域ａ１～ｈ１として示されている。 FIG. 9A shows the irradiation of signal light when the laser light passing through the light flux regions a1 to h1 of FIG. 8B is irradiated to the sensor portions P11 to P18 by the spectroscopic element H1 of FIG. It is a schematic diagram which shows an area | region. Note that the irradiation areas of the signal light passing through the light flux areas a1 to h1 are indicated as irradiation areas a1 to h1.
　図９（ａ）に示す如く、光束領域ａ１～ｈ１を通る信号光は、それぞれ、センサ部Ｐ１１、Ｐ１６、Ｐ１４、Ｐ１７、Ｐ１８、Ｐ１３、Ｐ１５、Ｐ１２に照射される。このとき、光束領域ａ１～ｈ１を通る迷光１、２は、図４（ｂ）と略同様に、信号光領域の外側に照射される。 As shown in FIG. 9A, the signal light passing through the light flux regions a1 to h1 is irradiated to the sensor portions P11, P16, P14, P17, P18, P13, P15, and P12, respectively. At this time, the stray lights 1 and 2 passing through the light flux areas a1 to h1 are irradiated to the outside of the signal light area in substantially the same manner as in FIG.
　また、図９（ａ）に示す如く、信号光領域の頂角部分における２つの照射領域（たとえば、照射領域ａ１、ｈ１）は、一定の距離だけ互いに離れている。他方、各頂角部分に配置された２つのセンサ部（例えばＰ１１、Ｐ１２）の間には所定の隙間が存在する。頂角部分の２つの照射領域の隙間は、対応する２つのセンサ部の隙間よりも大きい。かかる照射領域間の隙間は、上述したように、方向Ｖａ～Ｖｈに上下方向または左右方向の成分が僅かに含まれることにより設定される。 Further, as shown in FIG. 9A, two irradiation areas (for example, irradiation areas a1 and h1) in the apex portion of the signal light area are separated from each other by a certain distance. On the other hand, there is a predetermined gap between two sensor portions (for example, P11 and P12) arranged at each apex angle portion. The gap between the two irradiation areas at the apex angle portion is larger than the gap between the two corresponding sensor parts. As described above, the gap between the irradiation regions is set by slightly including components in the vertical direction or the horizontal direction in the directions Va to Vh.
　このような隙間により、センサ部Ｐ１１～Ｐ１８が、面Ｓ０（図１（ａ）参照）内で上下左右に位置ずれを生じた場合でも、照射領域ａ１～ｈ１はセンサ部Ｐ１１～Ｐ１８内に位置付けられ易くなる。よって、かかる位置ずれによるセンサ部Ｐ１１～Ｐ１８の検出信号の精度の低下が抑制され得る。 Due to such a gap, even when the sensor units P11 to P18 are displaced in the vertical and horizontal directions within the surface S0 (see FIG. 1A), the irradiation areas a1 to h1 are positioned in the sensor units P11 to P18. It becomes easy to be done. Therefore, it is possible to suppress a decrease in the accuracy of the detection signals of the sensor units P11 to P18 due to such positional deviation.
　分光素子Ｈ１が用いられる場合、プッシュプル信号は、図９（ｂ）の演算回路によって生成される。同図には、トラック像の方向が示されている。 When the spectroscopic element H1 is used, the push-pull signal is generated by the arithmetic circuit in FIG. In the figure, the direction of the track image is shown.
　演算回路では、センサ部Ｐ１１、Ｐ１２から出力された信号を加算回路１１で加算した信号と、センサ部Ｐ１７、Ｐ１８から出力された信号を加算回路１２で加算した信号とが減算回路１３で減算され、信号ＰＰ１が生成される。センサ部Ｐ１３、Ｐ１４から出力された信号を加算回路１４で加算した信号と、センサ部Ｐ１５、Ｐ１６から出力された信号を加算回路１５で加算した信号とが減算回路１６で減算され、信号ＰＰ２が生成される。さらに、信号ＰＰ１から、信号ＰＰ２を乗算回路１７でｋ倍した信号が減算され、プッシュプル信号ＰＰが生成される。 In the arithmetic circuit, a signal obtained by adding the signals output from the sensor units P11 and P12 by the adding circuit 11 and a signal obtained by adding the signals output from the sensor units P17 and P18 by the adding circuit 12 are subtracted by the subtracting circuit 13. , Signal PP1 is generated. A signal obtained by adding the signals output from the sensor units P13 and P14 by the adder circuit 14 and a signal obtained by adding the signals output from the sensor units P15 and P16 by the adder circuit 15 are subtracted by the subtractor circuit 16, so that the signal PP2 is obtained. Generated. Further, a signal obtained by multiplying the signal PP2 by k by the multiplication circuit 17 is subtracted from the signal PP1 to generate a push-pull signal PP.
　この演算回路において、乗算回路１７の乗数ｋを調整することにより、プッシュプル信号ＰＰに重畳されるレンズシフトによるＤＣ成分を取り除くことができる。このとき、分光素子Ｈ１を用いると、照射領域ｂ１、ｃ１、ｆ１、ｇ１の面積が照射領域ａ１、ｄ１、ｅ１、ｈ１の面積よりも大きいため、信号ＰＰ２の大きさが信号ＰＰ１の大きさに接近する。このため、乗数ｋを小さくすることができる。このように乗数ｋを小さくできるため、ノイズ成分が乗算回路１７によって増幅されるのを抑制でき、良好なプッシュプル信号ＰＰを得ることができる。 In this arithmetic circuit, by adjusting the multiplier k of the multiplication circuit 17, the DC component caused by the lens shift superimposed on the push-pull signal PP can be removed. At this time, when the spectroscopic element H1 is used, since the areas of the irradiation regions b1, c1, f1, and g1 are larger than the areas of the irradiation regions a1, d1, e1, and h1, the magnitude of the signal PP2 becomes the magnitude of the signal PP1. approach. For this reason, the multiplier k can be reduced. Since the multiplier k can be reduced in this way, it is possible to suppress the noise component from being amplified by the multiplication circuit 17 and obtain a good push-pull signal PP.
　また、このような分光素子Ｈ１が用いられると、上下のトラック像が、それぞれ、直線部ｐ２に掛かるため、レンズシフトが生じても、上下のトラック像は、回折領域Ｈ１ａ、Ｈ１ｈと回折領域Ｈ１ｄ、Ｈ１ｅに均等に掛かる。このため、レンズシフトが生じても、デトラックに基づく信号ＰＰ１の振幅は変わらず、プッシュプル信号ＰＰの振幅も、レンズシフトに応じて変化が生じることはない。 When such a spectroscopic element H1 is used, since the upper and lower track images are respectively applied to the straight line portion p2, the upper and lower track images are formed in the diffraction regions H1a and H1h and the diffraction regions H1d even if a lens shift occurs. , H1e evenly. For this reason, even if a lens shift occurs, the amplitude of the signal PP1 based on the detrack does not change, and the amplitude of the push-pull signal PP does not change according to the lens shift.
　なお、分光素子Ｈ１を用いる効果は、上記特願２０１０－２２２４２２号に詳細に記載されている。 The effect of using the spectroscopic element H1 is described in detail in the above Japanese Patent Application No. 2010-222422.
　＜分光素子Ｈ２＞
　分光素子Ｈ０は、さらに、以下のように変更・改良され得る。 <Spectroscopic element H2>
The spectroscopic element H0 can be further changed and improved as follows.
　図８（ｃ）は、分光素子Ｈ２の構成を示す図である。同図（ａ）は、分光素子Ｈ２を図１（ａ）、（ｂ）に示したアナモレンズ側から見たときの平面図である。図８（ｄ）は、分光素子Ｈ２に入射するレーザ光を、分光素子Ｈ２の回折領域の境界線に対応するよう、９つの領域に区分した光束領域ａ２～ｉ２を示す図である。 FIG. 8C is a diagram showing the configuration of the spectroscopic element H2. FIG. 5A is a plan view of the spectroscopic element H2 when viewed from the anamorphic lens side shown in FIGS. FIG. 8D is a diagram showing light flux regions a2 to i2 obtained by dividing the laser light incident on the spectroscopic element H2 into nine regions so as to correspond to the boundary lines of the diffraction regions of the spectroscopic element H2.
　図８（ｃ）を参照して、分光素子Ｈ２の中心には、方形状の回折領域Ｈ２ｉが形成されている。回折領域Ｈ２ｉは、この領域に入射するレーザ光が、センサ部Ｐ１１～Ｐ１８上に照射せず、センサ部Ｐ１１～Ｐ１８から離れた場所に照射するよう設定されている。なお、回折領域Ｈ２ｉの面積は、後述する信号光と迷光の干渉が効果的に抑制されるように設定される。 Referring to FIG. 8C, a square diffraction region H2i is formed at the center of the spectroscopic element H2. The diffraction region H2i is set so that the laser light incident on this region does not irradiate the sensor units P11 to P18 but irradiates a place away from the sensor units P11 to P18. The area of the diffraction region H2i is set so that interference between signal light and stray light, which will be described later, is effectively suppressed.
　回折領域Ｈ２ａ、Ｈ２ｄ、Ｈ２ｅ、Ｈ２ｈは、面積が互いに等しく、また、回折領域Ｈ２ｂ、Ｈ２ｃ、Ｈ２ｆ、Ｈ２ｇは、面積が互いに等しい。回折領域Ｈ２ｂ、Ｈ２ｃ、Ｈ２ｆ、Ｈ２ｇは、それぞれ、回折領域Ｈ２ａ、Ｈ２ｄ、Ｈ２ｅ、Ｈ２ｈよりも、面積が大きい。回折領域Ｈ２ａ～Ｈ２ｈの回折作用は、分光素子Ｈ１の回折領域Ｈ１ａ～Ｈ１ｈの回折作用と同じである。 The diffraction areas H2a, H2d, H2e, and H2h have the same area, and the diffraction areas H2b, H2c, H2f, and H2g have the same area. The diffraction regions H2b, H2c, H2f, and H2g each have a larger area than the diffraction regions H2a, H2d, H2e, and H2h. The diffraction action of the diffraction regions H2a to H2h is the same as that of the diffraction regions H1a to H1h of the spectroscopic element H1.
　分光素子Ｈ２の回折領域Ｈ２ａ、Ｈ２ｄ、Ｈ２ｅ、Ｈ２ｈと回折領域Ｈ２ｂ、Ｈ２ｃ、Ｈ２ｆ、Ｈ２ｇとの境界線は、直線部ｐ４を有し、直線部ｐ４以外は、何れも上下左右方向に対して４５度の角度を有する直線となっている。 The boundary line between the diffraction regions H2a, H2d, H2e, and H2h of the spectroscopic element H2 and the diffraction regions H2b, H2c, H2f, and H2g has a straight line portion p4. It is a straight line having an angle of 45 degrees.
　また、分光素子Ｈ２に入射する光束に含まれるトラック像は、分光素子Ｈ２の直線部ｐ４に十分掛かるよう、分光素子Ｈ２の境界線が設定されている。これにより、回折領域Ｈ２ａ、Ｈ２ｄ上における光束領域ａ２、ｄ２の照射領域は、回折領域Ｈ２ｂ、Ｈ２ｃ上における光束領域ｂ２、ｃ２の照射領域よりも小さくなる。同様に、回折領域Ｈ２ｅ、Ｈ２ｈ上における光束領域ｅ２、ｈ２の照射領域は、回折領域Ｈ２ｆ、Ｈ２ｇ上における光束領域ｆ２、ｇ２の照射領域よりも小さくなる。その他の分光素子Ｈ２の構成は、分光素子Ｈ１と同様となっている。 Further, the boundary line of the spectroscopic element H2 is set so that the track image included in the light beam incident on the spectroscopic element H2 is sufficiently applied to the linear portion p4 of the spectroscopic element H2. Thereby, the irradiation areas of the light flux areas a2 and d2 on the diffraction areas H2a and H2d are smaller than the irradiation areas of the light flux areas b2 and c2 on the diffraction areas H2b and H2c. Similarly, the irradiation areas of the light flux areas e2 and h2 on the diffraction areas H2e and H2h are smaller than the irradiation areas of the light flux areas f2 and g2 on the diffraction areas H2f and H2g. The structure of the other spectroscopic element H2 is the same as that of the spectroscopic element H1.
　図１０（ａ）は、図８（ｄ）の光束領域ａ２～ｈ２を通るレーザ光が、図８（ｃ）の分光素子Ｈ２により、センサ部Ｐ１１～Ｐ１８に照射されるときの信号光の照射領域を示す模式図である。この場合も、信号光領域の頂角部分における２つの照射領域（たとえば、照射領域ａ２、ｈ２）は、一定の距離だけ互いに離れている。他方、各頂角分に配置された２つのセンサ部（例えばＰ１１、Ｐ１２）の間には所定の隙間が存在する。頂角部分の２つの照射領域の隙間は、対応する２つのセンサ部の隙間よりも大きい。これにより、分光素子Ｈ１と同様、センサ部Ｐ１１～Ｐ１８に位置ずれが生じても、検出信号の精度の低下が抑制され得る。 FIG. 10A shows the irradiation of the signal light when the laser light passing through the light beam regions a2 to h2 of FIG. 8D is irradiated to the sensor portions P11 to P18 by the spectroscopic element H2 of FIG. 8C. It is a schematic diagram which shows an area | region. Also in this case, two irradiation regions (for example, irradiation regions a2 and h2) in the apex portion of the signal light region are separated from each other by a certain distance. On the other hand, there is a predetermined gap between two sensor portions (for example, P11 and P12) arranged for each apex angle. The gap between the two irradiation areas at the apex angle portion is larger than the gap between the two corresponding sensor parts. As a result, similarly to the spectroscopic element H1, even if a positional deviation occurs in the sensor units P11 to P18, a decrease in the accuracy of the detection signal can be suppressed.
　さらに、分光素子Ｈ２を用いる場合にも、図９（ｂ）の演算回路を用いることで、分光素子Ｈ１を用いる場合と同様、プッシュプル信号ＰＰのオフセット（ＤＣ成分）が効果的に抑制され、良好なプッシュプル信号ＰＰを得ることができる。 Further, even when the spectroscopic element H2 is used, the offset (DC component) of the push-pull signal PP is effectively suppressed by using the arithmetic circuit of FIG. 9B, as in the case where the spectroscopic element H1 is used. A good push-pull signal PP can be obtained.
　さらに、分光素子Ｈ２を用いる場合には、以下の効果を奏することができる。 Furthermore, when the spectroscopic element H2 is used, the following effects can be obtained.
　図１０（ｂ）は、センサ部Ｐ１１、Ｐ１２近傍の照射領域を示す拡大模式図である。 FIG. 10B is an enlarged schematic diagram showing an irradiation region in the vicinity of the sensor portions P11 and P12.
　図示の如く、センサ部Ｐ１１の左下近傍には、破線で示すように光束領域ａ２、ｈ２を通る迷光１が照射され、センサ部Ｐ１２の左上近傍には、破線で示すように光束領域ａ２、ｈ２を通る迷光２が照射される。 As shown, stray light 1 passing through the light flux areas a2 and h2 is irradiated near the lower left of the sensor part P11 as shown by a broken line, and light flux areas a2 and h2 are shown near the upper left of the sensor part P12 as shown by a broken line. The stray light 2 passing through is irradiated.
　ここで、分光素子Ｈ２の中心部分の境界線が図１８（ｃ）のようにＸ字状に形成されると、光束領域ｉ２を通るレーザ光の一部が図１０（ｂ）の斜線部分に照射される。すなわち、迷光１の照射領域ａ２、ｈ２の上側の三角形の斜線部分にも迷光１が照射され、迷光２の照射領域ａ２、ｈ２の下側の三角形の斜線部分にも迷光２が照射され、信号光の照射領域ａ２、ｈ２の左側の三角形の斜線部分にも信号光が照射される。この場合、信号光と迷光とが隣接しているため干渉が生じ易く、センサ部Ｐ１１、Ｐ１２の検出信号が劣化する惧れがある。しかしながら、図８（ｃ）に示した分光素子Ｈ２によれば、回折領域Ｈ２ｉによって斜線部分の迷光が除去されるため、信号光と迷光とが干渉し難くなり、検出信号の劣化が抑制され得る。 Here, when the boundary line of the central portion of the spectroscopic element H2 is formed in an X shape as shown in FIG. 18C, a part of the laser light passing through the light beam region i2 is shown in the hatched portion of FIG. Irradiated. That is, the stray light 1 is also irradiated to the diagonally shaded portions on the upper side of the irradiation areas a2 and h2 of the stray light 1, the stray light 2 is also irradiated to the diagonally shaded parts on the lower side of the irradiation areas a2 and h2 of the stray light 2 and the signal Signal light is also irradiated to the shaded portion of the triangle on the left side of the light irradiation areas a2 and h2. In this case, since the signal light and the stray light are adjacent to each other, interference is likely to occur, and the detection signals of the sensor units P11 and P12 may be deteriorated. However, according to the spectroscopic element H2 shown in FIG. 8C, since the stray light in the hatched portion is removed by the diffraction region H2i, it becomes difficult for the signal light and the stray light to interfere with each other, and deterioration of the detection signal can be suppressed. .
　図１０（ｃ）は、センサ部Ｐ１４、Ｐ１６近傍の照射領域を示す拡大模式図である。 FIG. 10C is an enlarged schematic diagram showing an irradiation region in the vicinity of the sensor portions P14 and P16.
　図示の如く、センサ部Ｐ１６の右上近傍には、破線で示すように光束領域ｂ２、ｃ２を通る迷光１が照射され、センサ部Ｐ１４の左上近傍には、破線で示すように光束領域ｂ２、ｃ２を通る迷光２が照射され、信号光の照射領域ｂ２、ｃ２の上側の三角形の斜線部分にも信号光が照射される。 As illustrated, stray light 1 passing through the light flux regions b2 and c2 is irradiated near the upper right of the sensor unit P16 as shown by a broken line, and light flux regions b2 and c2 are shown near the upper left of the sensor unit P14 as shown by a broken line. Stray light 2 passing through the signal light is irradiated, and the signal light is also irradiated to the hatched portion of the triangle above the signal light irradiation areas b2 and c2.
　この場合も、図１０（ｂ）の場合と同様、回折領域Ｈ２ｉによって斜線部分の迷光が除去されるため、信号光と迷光とが干渉し難くなり、検出信号の劣化が抑制され得る。同様に、センサ部Ｐ１３、１５と、センサ部Ｐ１７、Ｐ１８近傍の照射領域においても、信号光と迷光とが干渉し難くなり、検出信号の劣化が抑制され得る。 In this case as well, as in the case of FIG. 10B, the stray light in the hatched portion is removed by the diffraction region H2i, so that the signal light and the stray light are difficult to interfere with each other, and the deterioration of the detection signal can be suppressed. Similarly, the signal light and stray light are less likely to interfere with each other in the irradiation regions in the vicinity of the sensor units P13 and 15 and the sensor units P17 and P18, and deterioration of the detection signal can be suppressed.
　図１１は、上記分光素子Ｈ２を用いた場合の、センサレイアウト上における信号光の照射領域のシミュレーション結果を示す図である。同図（ａ）～（ｄ）は、それぞれ、センサレイアウトの左側部分と、上側部分と、右側部分と、下側部分を拡大した図である。なお、センサ部Ｐ１１～Ｐ１８の形状は、便宜上、後述する実施例のセンサ部Ｂ１～Ｂ８と同様の形状となっている。 FIG. 11 is a diagram showing a simulation result of the signal light irradiation region on the sensor layout when the spectroscopic element H2 is used. FIGS. 4A to 4D are enlarged views of the left part, the upper part, the right part, and the lower part of the sensor layout, respectively. The shapes of the sensor portions P11 to P18 are the same as those of the sensor portions B1 to B8 in the embodiments described later for convenience.
　図１１（ａ）～（ｄ）に示すように、信号光の照射領域ａ２～ｈ２は、センサ部上に位置付けられている。また、各図における２つの照射領域は、センサ部の隙間を挟んで位置付けられており、２つの照射領域の間隔は、センサ部の隙間よりも大きくなっている。これにより、上述したように、センサ部Ｐ１１～Ｐ１８が面Ｓ０（図１（ａ）参照）内で上下左右に位置ずれを生じた場合でも、検出信号の精度の低下が抑制される。 As shown in FIGS. 11A to 11D, the signal light irradiation areas a2 to h2 are positioned on the sensor section. In addition, the two irradiation areas in each figure are positioned with a gap between the sensor parts, and the interval between the two irradiation areas is larger than the gap between the sensor parts. As a result, as described above, even when the sensor units P11 to P18 are displaced in the vertical and horizontal directions within the surface S0 (see FIG. 1A), a decrease in the accuracy of the detection signal is suppressed.
　図１２は、図１１に示す状態から、センサレイアウトの位置ずれが生じた状態を示す図である。同図（ａ）～（ｄ）は、それぞれ、センサレイアウトの位置が右方向、下方向、左方向、上方向に所定量だけずれた場合を示している。なお、位置ずれが生じていない場合のセンサレイアウトの位置は、破線により示されている。 FIG. 12 is a diagram illustrating a state in which the position of the sensor layout has shifted from the state illustrated in FIG. FIGS. 4A to 4D show cases where the position of the sensor layout is shifted by a predetermined amount in the right direction, the downward direction, the left direction, and the upward direction, respectively. Note that the position of the sensor layout in the case where no positional deviation has occurred is indicated by a broken line.
　図１２（ａ）に示すように、センサレイアウトの位置が右方向に所定量ずれると、信号光の照射領域ａ２、ｈ２の点線で示す部分が、それぞれ、センサ部Ｐ１１の左下とセンサ部Ｐ１２の左上からはみ出してしまう。同様に、図１２（ｂ）～（ｄ）に示すように、センサレイアウトの位置が所定量ずれると、信号光の照射領域の点線で示す部分が、センサ部からはみ出してしまう。このように、センサレイアウトの位置が所定量ずれてしまうと、信号光の照射領域がセンサ部からはみ出し、検出信号の精度が低下する惧れがある。 As shown in FIG. 12A, when the position of the sensor layout is shifted by a predetermined amount in the right direction, the portions indicated by dotted lines of the signal light irradiation areas a2 and h2 are the lower left of the sensor part P11 and the sensor part P12, respectively. It protrudes from the upper left. Similarly, as shown in FIGS. 12B to 12D, when the position of the sensor layout is shifted by a predetermined amount, the portion indicated by the dotted line of the signal light irradiation region protrudes from the sensor portion. Thus, if the position of the sensor layout is shifted by a predetermined amount, the irradiation area of the signal light may protrude from the sensor unit, and the accuracy of the detection signal may be reduced.
　＜分光素子Ｈ３＞
　図１２を参照して説明した問題を解消するために、以下の構成を用いることができる。この構成は、本発明の一つの実施形態となるものである。 <Spectroscopic element H3>
In order to solve the problem described with reference to FIG. 12, the following configuration can be used. This configuration is one embodiment of the present invention.
　図１３（ａ）は、分光素子Ｈ３の構成を示す図である。同図（ａ）は、分光素子Ｈ３を図１（ａ）、（ｂ）に示したアナモレンズ側から見たときの平面図である。図１３（ｂ）は、分光素子Ｈ３に入射するレーザ光を、分光素子Ｈ３の回折領域の境界線に対応するよう、９つの領域に区分した光束領域ａ３～ｉ３を示す図である。 FIG. 13A is a diagram showing the configuration of the spectroscopic element H3. FIG. 4A is a plan view when the spectroscopic element H3 is viewed from the anamorphic lens side shown in FIGS. FIG. 13B is a diagram showing light beam regions a3 to i3 obtained by dividing the laser light incident on the spectroscopic element H3 into nine regions so as to correspond to the boundary lines of the diffraction regions of the spectroscopic element H3.
　なお、分光素子Ｈ３の回折領域Ｈ３ａ～Ｈ３ｉの形状および面積は、上述の分光素子Ｈ２の回折領域Ｈ２ａ～Ｈ２ｉと同じである。回折領域Ｈ３ｂ、Ｈ３ｃからなる領域と、回折領域Ｈ３ｆ、Ｈ３ｇからなる領域が、それぞれ、請求項１における「第１の領域」と「第２の領域」に対応し、回折領域Ｈ３ａ、Ｈ３ｈからなる領域と、回折領域Ｈ３ｄ、Ｈ３ｅからなる領域が、それぞれ、請求項１における「第３の領域」と「第４の領域」に対応する。また、回折領域Ｈ３ｉは、請求項３における「第５の領域」に対応する。 The shape and area of the diffraction regions H3a to H3i of the spectroscopic element H3 are the same as the diffraction regions H2a to H2i of the spectroscopic element H2. The region composed of the diffraction regions H3b and H3c and the region composed of the diffraction regions H3f and H3g correspond to the “first region” and the “second region” in claim 1, respectively, and are composed of the diffraction regions H3a and H3h. The region and the region composed of the diffraction regions H3d and H3e correspond to the “third region” and the “fourth region” in claim 1, respectively. The diffraction region H3i corresponds to a “fifth region” in claim 3.
　分光素子Ｈ３は、分光素子Ｈ２に比べ、回折領域Ｈ３ａ～Ｈ３ｈにレンズ効果が付与されている点においてのみ相違している。以下には、便宜上、回折領域Ｈ３ａ～Ｈ３ｈに付与されたレンズ効果についてのみ説明を行う。 The spectroscopic element H3 is different from the spectroscopic element H2 only in that a lens effect is given to the diffraction regions H3a to H3h. In the following, only the lens effect imparted to the diffraction regions H3a to H3h will be described for convenience.
　図１３（ｃ）は、分光素子Ｈ３の回折領域Ｈ３ａ～Ｈ３ｈが有するレンズ効果を概念的に示す図である。回折領域Ｈ３ａ、Ｈ３ｄは上方向に、回折領域Ｈ３ｅ、Ｈ３ｈは下方向に、回折領域Ｈ３ｂ、Ｈ３ｇは左方向に、回折領域Ｈ３ｃ、Ｈ３ｆは右方向に、入射するレーザ光に対してレンズ効果を付与する。また、回折領域Ｈ３ｂ、Ｈ３ｃ、Ｈ３ｆ、Ｈ３ｇは、分光素子Ｈ３の中心から左右方向に離れるに従ってレンズ効果が大きくなるように設定されている。回折領域Ｈ３ａ、Ｈ３ｄ、Ｈ３ｅ、Ｈ３ｈは、分光素子Ｈ３の中心から上下方向に離れるに従ってレンズ効果が小さくなるように設定されている。このようなレンズ効果は、回折領域Ｈ３ａ～Ｈ３ｈの回折作用を表す位相関数に２乗の項を持たせることにより実現される。 FIG. 13 (c) is a diagram conceptually showing the lens effect of the diffraction regions H3a to H3h of the spectroscopic element H3. The diffraction regions H3a and H3d are in the upward direction, the diffraction regions H3e and H3h are in the downward direction, the diffraction regions H3b and H3g are in the left direction, and the diffraction regions H3c and H3f are in the right direction. Give. The diffraction regions H3b, H3c, H3f, and H3g are set so that the lens effect increases as the distance from the center of the spectroscopic element H3 increases in the left-right direction. The diffraction regions H3a, H3d, H3e, and H3h are set so that the lens effect decreases as the distance from the center of the spectroscopic element H3 increases in the vertical direction. Such a lens effect is realized by giving a square term to the phase function representing the diffraction action of the diffraction regions H3a to H3h.
　図１３（ｄ）は、図１３（ｂ）の光束領域ａ３～ｈ３を通るレーザ光が、図１３（ａ）の分光素子Ｈ３により、センサ部Ｐ１１～Ｐ１８に照射されるときの信号光の照射領域を示す模式図である。この場合も、図１０（ａ）に示す分光素子Ｈ２と同様、光束領域ａ３～ｈ３を通る信号光は、各センサ部に照射され、光束領域ａ３～ｈ３を通る迷光１、２は、図４（ｂ）と略同様に、信号光領域の外側に照射される。 FIG. 13D shows the irradiation of the signal light when the laser light passing through the light beam regions a3 to h3 of FIG. 13B is irradiated to the sensor units P11 to P18 by the spectroscopic element H3 of FIG. It is a schematic diagram which shows an area | region. Also in this case, similarly to the spectroscopic element H2 shown in FIG. 10A, the signal light passing through the light flux regions a3 to h3 is irradiated to each sensor unit, and the stray lights 1 and 2 passing through the light flux regions a3 to h3 are shown in FIG. As in (b), the light is irradiated outside the signal light region.
　また、分光素子Ｈ２と同様、照射領域ａ３、ｄ３、ｅ３、ｈ３は、照射領域ｂ３、ｃ３、ｆ３、ｇ３に比べて面積が小さくなる。かかる面積の調整と、分光素子Ｈ３の回折領域の境界線に直線部ｐ４が設けられていることにより、レンズシフトによるプッシュプル信号ＰＰのオフセット（ＤＣ成分）が効果的に抑制できる。また、回折領域Ｈ３ｉに入射する迷光が除去されるため、分光素子Ｈ２と同様、信号光と迷光とが干渉し難くなり（図１０（ｂ）、（ｃ）参照）、検出信号の劣化が抑制され得る。 Also, similarly to the spectroscopic element H2, the irradiation areas a3, d3, e3, and h3 have a smaller area than the irradiation areas b3, c3, f3, and g3. By adjusting the area and providing the straight line portion p4 at the boundary line of the diffraction region of the spectroscopic element H3, the offset (DC component) of the push-pull signal PP due to lens shift can be effectively suppressed. Further, since stray light incident on the diffraction region H3i is removed, similarly to the spectroscopic element H2, the signal light and stray light are less likely to interfere (see FIGS. 10B and 10C), and the deterioration of the detection signal is suppressed. Can be done.
　さらに、分光素子Ｈ３では、図１３（ｃ）に示すレンズ効果により、以下の効果が奏され得る。 Furthermore, in the spectroscopic element H3, the following effects can be achieved by the lens effect shown in FIG.
　図１４は、上記分光素子Ｈ３を用いた場合の、センサレイアウト上における信号光の照射領域のシミュレーション結果を示す図である。同図（ａ）～（ｄ）は、それぞれ、センサレイアウトの左側部分と、上側部分と、右側部分と、下側部分を拡大した図である。 FIG. 14 is a diagram showing a simulation result of the irradiation area of the signal light on the sensor layout when the spectroscopic element H3 is used. FIGS. 4A to 4D are enlarged views of the left part, the upper part, the right part, and the lower part of the sensor layout, respectively.
　図１４（ａ）～（ｄ）に示すように、信号光の照射領域ａ３～ｈ３は、センサ部上に位置付けられている。また、各図における２つの照射領域は、センサ部の隙間を挟んで位置付けられている。 As shown in FIGS. 14A to 14D, the signal light irradiation areas a3 to h3 are positioned on the sensor section. In addition, the two irradiation areas in each figure are positioned with a gap between the sensor portions interposed therebetween.
　各図の２つの照射領域は、上記レンズ効果により、図１１（ａ）～（ｄ）に比べて、図中の矢印に示すように一方の端部が近づけられている。すなわち、上記レンズ効果により、照射領域ａ３、ｈ３は、センサレイアウトの中心から信号光領域の頂角に近づくにつれて、互いに近づけられ、照射領域ｄ３、ｅ３は、センサレイアウトの中心から信号光領域の頂角に近づくにつれて、互いに近づけられる。また、照射領域ｂ３、ｃ３は、信号光領域の頂角からセンサレイアウトの中心に近づくにつれて、互いに近づけられ、照射領域ｆ３、ｇ３は、信号光領域の頂角からセンサレイアウトの中心に近づくにつれて、互いに近づけられる。 In the two irradiation areas in each figure, one end portion is brought closer as shown by the arrows in the figure as compared with FIGS. 11 (a) to 11 (d) due to the lens effect. That is, due to the lens effect, the irradiation areas a3 and h3 are brought closer to each other as the apex angle of the signal light area is approached from the center of the sensor layout, and the irradiation areas d3 and e3 are made closer to the apex of the signal light area from the center of the sensor layout. As you get closer to the corner, you get closer to each other. Further, the irradiation regions b3 and c3 are brought closer to each other as they approach the center of the sensor layout from the apex angle of the signal light region, and the irradiation regions f3 and g3 become closer to the center of the sensor layout from the apex angle of the signal light region. Get close to each other.
　かかるレンズ効果により、照射領域ａ３、ｈ３の両方を囲む領域の形状と、照射領域ｄ３、ｅ３の両方を囲む領域の形状と、照射領域ｂ３、ｃ３の両方を囲む領域の形状と、照射領域ｆ３、ｇ３の両方を囲む領域の形状は、それぞれ、分光素子Ｈ３を用いる場合に比べ、頂角が９０度の扇形に近づく。 Due to the lens effect, the shape of the region surrounding both of the irradiation regions a3 and h3, the shape of the region surrounding both of the irradiation regions d3 and e3, the shape of the region surrounding both of the irradiation regions b3 and c3, and the irradiation region f3 , G3, the shape of the region surrounding both of them is closer to a fan shape with an apex angle of 90 degrees compared to the case where the spectroscopic element H3 is used.
　図１５は、図１４に示す状態から、センサレイアウトの位置ずれが生じた状態を示す図である。同図（ａ）～（ｄ）は、それぞれ、センサレイアウトの位置が右方向、下方向、左方向、上方向に所定量だけずれた場合を示している。なお、同図（ａ）～（ｄ）の位置ずれ量は、図１２（ａ）～（ｄ）の位置ずれ量と同じである。 FIG. 15 is a diagram showing a state in which the position of the sensor layout has shifted from the state shown in FIG. FIGS. 4A to 4D show cases where the position of the sensor layout is shifted by a predetermined amount in the right direction, the downward direction, the left direction, and the upward direction, respectively. It should be noted that the amount of misalignment in FIGS. 12A to 12D is the same as the amount of misalignment in FIGS.
　図１５（ａ）に示すように、センサレイアウトの位置が図１２（ａ）と同程度ずれても、照射領域ａ３、ｈ３は、センサ部Ｐ１１、Ｐ１２からはみ出ることがない。また、図１５（ｃ）に示すように、センサレイアウトの位置が図１２（ｃ）と同程度ずれても、照射領域ｄ３、ｅ３は、センサ部Ｐ１７、Ｐ１８からはみ出ることがない。さらに、図１５（ｂ）に示すように、センサレイアウトの位置が図１２（ｂ）と同程度ずれても、点線領域に示すように、図１２（ｂ）に比べて照射領域ｂ３、ｃ３からはみ出す量が少なくなる。また、図１５（ｄ）に示すように、センサレイアウトの位置が図１２（ｄ）と同程度ずれても、点線領域に示すように、図１２（ｄ）に比べて照射領域ｆ３、ｇ３からはみ出す量が少なくなる。これにより、センサレイアウトの位置がずれた場合でも、信号光の照射領域がセンサレイアウトからはみ出すことによる検出信号の精度の低下が、分光素子Ｈ２に比べて抑制され得る。 As shown in FIG. 15 (a), even if the position of the sensor layout is shifted to the same extent as in FIG. 12 (a), the irradiation areas a3 and h3 do not protrude from the sensor portions P11 and P12. Further, as shown in FIG. 15C, even if the position of the sensor layout is shifted to the same extent as in FIG. 12C, the irradiation areas d3 and e3 do not protrude from the sensor portions P17 and P18. Further, as shown in FIG. 15B, even if the position of the sensor layout is shifted to the same extent as in FIG. 12B, as shown in the dotted line region, the irradiation areas b3 and c3 are compared with those in FIG. The amount that protrudes is reduced. Further, as shown in FIG. 15 (d), even if the position of the sensor layout is shifted to the same extent as in FIG. 12 (d), as shown in the dotted line region, as shown in FIG. The amount that protrudes is reduced. Thereby, even when the position of the sensor layout is shifted, a decrease in the accuracy of the detection signal due to the irradiation area of the signal light protruding from the sensor layout can be suppressed as compared with the spectroscopic element H2.
　このように、分光素子Ｈ３を用いる場合には、図１３（ｃ）に示すレンズ効果によって信号光領域の各頂角の位置に照射される２つの信号光を含む領域の形状が、頂角を９０度とする扇形に近づくため、図１５に示すようにセンサ部Ｐ１１～Ｐ１８に位置ずれが生じても、かかる位置ずれによりセンサ部Ｐ１１～Ｐ１８から各照射領域がはみ出しにくくなり、検出信号の精度の低下が抑制される。 As described above, when the spectroscopic element H3 is used, the shape of the region including the two signal lights irradiated to the positions of the respective vertex angles of the signal light region by the lens effect shown in FIG. Since it approaches a fan shape of 90 degrees, even if a position shift occurs in the sensor parts P11 to P18 as shown in FIG. 15, the irradiation area does not easily protrude from the sensor parts P11 to P18 due to the position shift, and the accuracy of the detection signal Is suppressed.
　なお、分光素子Ｈ３を用いる場合、上記レンズ効果によって、隣り合う照射領域が互いに接近する。このため、図１５（ａ）、（ｃ）の状態からセンサ部Ｐ１１、Ｐ１２およびセンサ部Ｐ１７、Ｐ１８が上下方向に僅かに変位しても、センサ部Ｐ１１、Ｐ１２、Ｐ１７、Ｐ１８の検出信号が変化する。同様に、図１５（ｂ）、（ｄ）の状態からセンサ部Ｐ１４、Ｐ１６およびセンサ部Ｐ１３、Ｐ１５が左右方向に僅かに変位しても、センサ部Ｐ１３～１６の検出信号が変化する。したがって、センサ部Ｐ１１～Ｐ１８の検出信号を参照することで、光検出器の位置調整を円滑かつ適正に行うことができる。 In addition, when the spectroscopic element H3 is used, adjacent irradiation regions approach each other due to the lens effect. For this reason, even if the sensor parts P11 and P12 and the sensor parts P17 and P18 are slightly displaced in the vertical direction from the states of FIGS. 15A and 15C, the detection signals of the sensor parts P11, P12, P17 and P18 are not detected. Change. Similarly, even if the sensor units P14 and P16 and the sensor units P13 and P15 are slightly displaced in the left-right direction from the states of FIGS. 15B and 15D, the detection signals of the sensor units P13 to P16 change. Therefore, the position adjustment of the photodetector can be performed smoothly and appropriately by referring to the detection signals of the sensor units P11 to P18.
　以下の実施例には、上記分光素子Ｈ３を用いた光ピックアップ装置の具体的構成例が示されている。 In the following examples, specific configuration examples of the optical pickup device using the spectroscopic element H3 are shown.
　＜実施例＞
　本実施例は、ＢＤ、ＤＶＤおよびＣＤに対応可能な互換型の光ピックアップ装置に本発明を適用したものである。上記原理は、ＢＤ用の光学系にのみ適用され、ＣＤ用の光学系とＤＶＤ用の光学系には従来の非点収差法によるフォーカス調整技術と３ビーム方式（インライン方式）によるトラッキング調整技術が適用されている。 <Example>
In this embodiment, the present invention is applied to a compatible optical pickup device that can handle BD, DVD, and CD. The above principle is applied only to the optical system for BD, and the focus adjustment technique by the conventional astigmatism method and the tracking adjustment technique by the three-beam method (in-line method) are applied to the optical system for CD and the optical system for DVD. Has been applied.
　図１６（ａ）、（ｂ）は、本実施例に係る光ピックアップ装置の光学系を示す図である。図１６（ａ）は、立ち上げミラー１１４、１１５よりもディスク側の構成を省略した光学系の平面図、図１６（ｂ）は、立ち上げミラー１１４、１１５以降の光学系を側面から透視した図である。 FIGS. 16A and 16B are diagrams showing an optical system of the optical pickup device according to the present embodiment. FIG. 16A is a plan view of the optical system in which the configuration on the disk side of the rising mirrors 114 and 115 is omitted, and FIG. 16B is a perspective view of the optical system after the rising mirrors 114 and 115 from the side. FIG.
　図示の如く、光ピックアップ装置は、半導体レーザ１０１と、１／２波長板１０２と、ダイバージングレンズ１０３と、２波長レーザ１０４と、回折格子１０５と、ダイバージングレンズ１０６と、複合プリズム１０７と、フロントモニタ１０８と、コリメートレンズ１０９と、駆動機構１１０と、反射ミラー１１１、１１２と、１／４波長板１１３と、立ち上げミラー１１４、１１５と、２波長対物レンズ１１６と、ＢＤ対物レンズ１１７と、分光素子Ｈ３と、アナモレンズ１１８と、光検出器１１９を備えている。 As illustrated, the optical pickup device includes a semiconductor laser 101, a half-wave plate 102, a diverging lens 103, a two-wavelength laser 104, a diffraction grating 105, a diverging lens 106, a composite prism 107, Front monitor 108, collimator lens 109, drive mechanism 110, reflection mirrors 111 and 112, quarter-wave plate 113, rising mirrors 114 and 115, two-wavelength objective lens 116, and BD objective lens 117 , A spectroscopic element H3, an anamorphic lens 118, and a photodetector 119.
　半導体レーザ１０１は、波長４０５ｎｍ程度のＢＤ用レーザ光（以下、「ＢＤ光」という）を出射する。１／２波長板１０２は、ＢＤ光の偏光方向を調整する。ダイバージングレンズ１０３は、半導体レーザ１０１と複合プリズム１０７との距離を短縮するようＢＤ光の焦点距離を調整する。 The semiconductor laser 101 emits BD laser light (hereinafter referred to as “BD light”) having a wavelength of about 405 nm. The half-wave plate 102 adjusts the polarization direction of the BD light. The diverging lens 103 adjusts the focal length of the BD light so as to shorten the distance between the semiconductor laser 101 and the composite prism 107.
　２波長レーザ１０４は、波長７８５ｎｍ程度のＣＤ用レーザ光（以下、「ＣＤ光」という）と、波長６６０ｎｍ程度のＤＶＤ用レーザ光（以下、「ＤＶＤ光」という）をそれぞれ出射する２つのレーザ素子を同一ＣＡＮ内に収容している。 The two-wavelength laser 104 has two laser elements that respectively emit a laser beam for CD having a wavelength of about 785 nm (hereinafter referred to as “CD light”) and a laser beam for DVD having a wavelength of about 660 nm (hereinafter referred to as “DVD light”). Are accommodated in the same CAN.
　図１６（ｃ）は、２波長レーザ１０４内におけるレーザ素子（レーザ光源）の配置パターンを示す図である。同図（ｃ）は、２波長レーザ１０４をビーム出射側から見たときのものである。同図（ｃ）において、ＣＥおよびＤＥは、それぞれ、ＣＤ光およびＤＶＤ光の発光点を示している。ＣＤ光およびＤＶＤ光の発光点間のギャップはＧである。 FIG. 16C is a diagram showing an arrangement pattern of laser elements (laser light sources) in the two-wavelength laser 104. FIG. 2C shows the two-wavelength laser 104 as viewed from the beam emission side. In FIG. 5C, CE and DE indicate the light emission points of CD light and DVD light, respectively. The gap between the emission points of CD light and DVD light is G.
　なお、ＣＤ光の発光点ＣＥとＤＶＤ光の発光点ＤＥとの間のギャップＧは、後述の如く、ＤＶＤ光が、ＤＶＤ光用の４分割センサに適正に照射されるように設定される。このように、２つの光源を同一ＣＡＮ内に収容することで、複数ＣＡＮの構成に比べて光学系を簡素化することができる。 Note that the gap G between the light emission point CE of the CD light and the light emission point DE of the DVD light is set so that the DVD light is appropriately irradiated onto the four-divided sensor for DVD light, as will be described later. Thus, by accommodating two light sources in the same CAN, the optical system can be simplified as compared with the configuration of a plurality of CAN.
　図１６（ａ）に戻り、回折格子１０５は、ＣＤ光およびＤＶＤ光を、それぞれ、メインビームと２つのサブビームに分割する。回折格子１０５は、２段ステップ型の回折格子である。また、回折格子１０５には、１／２波長板が一体化されている。一体化された１／２波長板によって、ＣＤ光とＤＶＤ光の偏光方向が調整される。ダイバージングレンズ１０６は、２波長レーザ１０４と複合プリズム１０７との距離を短くするようＣＤ光およびＤＶＤ光の焦点距離を調整する。 16A, the diffraction grating 105 divides the CD light and the DVD light into a main beam and two sub beams, respectively. The diffraction grating 105 is a two-step step type diffraction grating. The diffraction grating 105 is integrated with a half-wave plate. The polarization direction of the CD light and the DVD light is adjusted by the integrated half-wave plate. The diverging lens 106 adjusts the focal lengths of the CD light and the DVD light so as to shorten the distance between the two-wavelength laser 104 and the composite prism 107.
　複合プリズム１０７は、内部に、ダイクロイック面１０７ａと、ＰＢＳ（Polarizing Beam Splitter）面１０７ｂを有している。ダイクロイック面１０７ａは、ＢＤ光を反射し、ＣＤ光とＤＶＤ光を透過する。半導体レーザ１０１、２波長レーザ１０４および複合プリズム１０７は、ダイクロイック面１０７ａにより反射されたＢＤ光の光軸とダイクロイック面１０７ａを透過したＣＤ光の光軸が互いに整合するように、配置される。ダイクロイック面１０７ａを透過したＤＶＤ光の光軸は、ＢＤ光とＣＤ光の光軸から、図１６（ｃ）に示すギャップＧだけずれる。 The composite prism 107 has a dichroic surface 107 a and a PBS (Polarizing Beam Splitter) surface 107 b inside. The dichroic surface 107a reflects BD light and transmits CD light and DVD light. The semiconductor laser 101, the two-wavelength laser 104, and the composite prism 107 are arranged so that the optical axis of the BD light reflected by the dichroic surface 107a and the optical axis of the CD light transmitted through the dichroic surface 107a are aligned with each other. The optical axis of the DVD light transmitted through the dichroic surface 107a is shifted from the optical axis of the BD light and the CD light by a gap G shown in FIG.
　ＢＤ光、ＣＤ光およびＤＶＤ光は、それぞれ、一部がＰＢＳ面１０７ｂによって反射され、大部分がＰＢＳ面１０７ｂを透過する。このようにＢＤ光、ＣＤ光およびＤＶＤ光の一部がＰＢＳ面１０７ｂによって反射されるよう、１／２波長板１０２と、回折格子１０５（一体化された１／２波長板）が配置される。 BD light, CD light, and DVD light are each partially reflected by the PBS surface 107b and mostly transmitted through the PBS surface 107b. In this way, the half-wave plate 102 and the diffraction grating 105 (integrated half-wave plate) are arranged so that a part of the BD light, CD light, and DVD light is reflected by the PBS surface 107b. .
　なお、このように回折格子１０５が配置されると、ＣＤ光のメインビームおよび２つのサブビームと、ＤＶＤ光のメインビームおよび２つのサブビームは、それぞれ、ＣＤおよびＤＶＤのトラックに沿うようなる。ＣＤによって反射されたＣＤ光のメインビームと２つのサブビームは、後述する光検出器１１９上のＣＤ用の４分割センサに照射される。ＤＶＤによって反射されたＤＶＤ光のメインビームと２つのサブビームは、後述する光検出器１２０上のＤＶＤ用の４分割センサに照射される。 When the diffraction grating 105 is arranged in this manner, the main beam and two sub beams of the CD light and the main beam and two sub beams of the DVD light are along the tracks of the CD and DVD, respectively. The main beam and the two sub beams of the CD light reflected by the CD are applied to a four-divided sensor for CD on a photodetector 119 described later. The DVD main beam and the two sub-beams reflected by the DVD are applied to a DVD quadrant sensor on a photodetector 120 described later.
　ＰＢＳ面１０７ｂにより反射されたＢＤ光、ＣＤ光、ＤＶＤ光は、フロントモニタ１０８に照射される。フロントモニタ１０８は、受光光量に応じた信号を出力する。フロントモニタ１０８からの信号は、半導体レーザ１０１と２波長レーザ１０４の出射パワー制御に用いられる。 BD light, CD light, and DVD light reflected by the PBS surface 107b are irradiated to the front monitor 108. The front monitor 108 outputs a signal corresponding to the amount of received light. A signal from the front monitor 108 is used for output power control of the semiconductor laser 101 and the two-wavelength laser 104.
　コリメートレンズ１０９は、複合プリズム１０７側から入射するＢＤ光、ＣＤ光およびＤＶＤ光を平行光に変換する。駆動機構１１０は、収差補正の際に、制御信号に応じてコリメートレンズ１０９を光軸方向に移動させる。駆動機構１１０は、コリメートレンズ１０９を保持するホルダ１１０ａと、ホルダ１１０ａをコリメートレンズ１０９の光軸方向に送るためのギア１１０ｂとを備え、ギア１１０ｂは、モータ１１０ｃの駆動軸に連結されている。 The collimator lens 109 converts BD light, CD light, and DVD light incident from the composite prism 107 side into parallel light. The drive mechanism 110 moves the collimating lens 109 in the optical axis direction according to the control signal when correcting the aberration. The driving mechanism 110 includes a holder 110a that holds the collimating lens 109, and a gear 110b that sends the holder 110a in the optical axis direction of the collimating lens 109. The gear 110b is connected to a driving shaft of the motor 110c.
　コリメートレンズ１０９により平行光とされたＢＤ光、ＣＤ光およびＤＶＤ光は、２つの反射ミラー１１１、１１２により反射され、１／４波長板１１３に入射する。１／４波長板１１３は、反射ミラー１１２側から入射するＢＤ光、ＣＤ光およびＤＶＤ光を円偏光に変換するとともに、立ち上げミラー１１４側から入射するＢＤ光、ＣＤ光およびＤＶＤ光を、反射ミラー１１２側から入射する際の偏光方向に直交する直線偏光に変換する。これにより、ディスクからの反射光は、ＰＢＳ面１０７ｂにより反射される。 BD light, CD light, and DVD light that have been converted into parallel light by the collimator lens 109 are reflected by the two reflecting mirrors 111 and 112 and enter the quarter-wave plate 113. The quarter-wave plate 113 converts BD light, CD light, and DVD light incident from the reflection mirror 112 side into circularly polarized light, and reflects BD light, CD light, and DVD light incident from the rising mirror 114 side. The light is converted into linearly polarized light orthogonal to the polarization direction when entering from the mirror 112 side. Thereby, the reflected light from the disk is reflected by the PBS surface 107b.
　立ち上げミラー１１４は、ダイクロイックミラーであり、ＢＤ光を透過するとともに、ＣＤ光およびＤＶＤ光を２波長対物レンズ１１６に向かう方向に反射する。立ち上げミラー１１５は、ＢＤ光をＢＤ対物レンズ１１７に向かう方向に反射する。 The rising mirror 114 is a dichroic mirror that transmits BD light and reflects CD light and DVD light in a direction toward the two-wavelength objective lens 116. The rising mirror 115 reflects BD light in a direction toward the BD objective lens 117.
　２波長対物レンズ１１６は、ＣＤ光およびＤＶＤ光を、それぞれ、ＣＤおよびＤＶＤに対して適正に収束させるよう構成されている。また、ＢＤ対物レンズ１１７は、ＢＤ光をＢＤに適正に収束させるよう構成されている。２波長対物レンズ１１６とＢＤ対物レンズ１１７は、ホルダ１３１に保持された状態で、対物レンズアクチュエータ１３２により、フォーカス方向およびトラッキング方向に駆動される。 The two-wavelength objective lens 116 is configured to properly converge the CD light and the DVD light with respect to the CD and the DVD, respectively. The BD objective lens 117 is configured to properly converge the BD light onto the BD. The two-wavelength objective lens 116 and the BD objective lens 117 are driven in the focus direction and the tracking direction by the objective lens actuator 132 while being held by the holder 131.
　分光素子Ｈ３は、図１３（ａ）に示した分光素子である。分光素子Ｈ３に入射したＢＤ光、ＣＤ光およびＤＶＤ光のうち、ＢＤ光は、８つの光束に区分され、分光素子Ｈ３による回折作用によって、各光束の進行方向が変えられる。ＣＤ光とＤＶＤ光は、大半が分光素子Ｈ３による回折作用を受けずに、分光素子Ｈ３を透過する。 The spectroscopic element H3 is the spectroscopic element shown in FIG. Of the BD light, CD light, and DVD light incident on the spectroscopic element H3, the BD light is divided into eight light fluxes, and the traveling direction of each light flux is changed by the diffractive action of the spectroscopic element H3. Most of the CD light and the DVD light pass through the spectroscopic element H3 without being diffracted by the spectroscopic element H3.
　分光素子Ｈ３は、正方形形状の透明板にて形成され、光入射面にステップ型の回折パターン（回折ホログラム）が形成されている。回折パターンのステップ数およびステップ高さは、ＢＤ光の波長に対する＋１次の回折効率が高くなり、ＣＤ光とＤＶＤ光の波長に対する０次の回折効率が高くなるよう設定される。回折角は、回折パターンのピッチによって調整される。 The spectroscopic element H3 is formed of a square-shaped transparent plate, and a step-type diffraction pattern (diffraction hologram) is formed on the light incident surface. The number of steps and the step height of the diffraction pattern are set so that the + 1st order diffraction efficiency with respect to the wavelength of the BD light is increased and the 0th order diffraction efficiency with respect to the wavelengths of the CD light and the DVD light is increased. The diffraction angle is adjusted by the pitch of the diffraction pattern.
　分光素子Ｈ３の回折領域Ｈ３ａ～Ｈ３ｉは、たとえば、８段ステップ型の回折パターンとされる。この場合、１ステップあたりの段差が７．３５μｍに設定される。これにより、ＢＤ光の＋１次回折光の回折効率を８１％としながら、ＣＤ光とＤＶＤ光の０次回折光の回折効率を、それぞれ、９９％および９２％とすることができる。この場合、ＢＤ光の０次回折効率は、７％となる。ＣＤ光とＤＶＤ光は、回折領域Ｈ３ａ～Ｈ３ｉにより略回折を受けずに、光検出器１１９上の、後述する４分割センサに照射される。 The diffraction regions H3a to H3i of the spectroscopic element H3 are, for example, 8-step diffraction patterns. In this case, the step per step is set to 7.35 μm. Thereby, the diffraction efficiency of the 0th-order diffracted light of the CD light and the DVD light can be set to 99% and 92%, respectively, while the diffraction efficiency of the + 1st-order diffracted light of the BD light is 81%. In this case, the 0th-order diffraction efficiency of BD light is 7%. The CD light and the DVD light are irradiated to a quadrant sensor, which will be described later, on the photodetector 119 without being substantially diffracted by the diffraction regions H3a to H3i.
　なお、回折領域Ｈ３ａ～Ｈ３ｉに配される回折パターンのステップ数を他のステップ数にすることもできる。また、回折領域Ｈ３ａ～Ｈ３ｉを、たとえば、特開２００６－７３０４２号公報に記載の技術を用いて構成することもできる。この技術を用いると、ＢＤ光、ＣＤ光およびＤＶＤ光に対する回折効率を、さらに細かく調整することができる。 Note that the number of steps of the diffraction pattern arranged in the diffraction regions H3a to H3i can be set to other steps. In addition, the diffraction regions H3a to H3i can be configured using the technique described in Japanese Patent Application Laid-Open No. 2006-73042, for example. If this technique is used, the diffraction efficiency with respect to BD light, CD light, and DVD light can be adjusted further finely.
　アナモレンズ１１８は、分光素子Ｈ３側から入射したＢＤ光、ＣＤ光およびＤＶＤ光に非点収差を導入する。アナモレンズ１１８は、図１（ａ）、（ｂ）のアナモレンズに相当する。アナモレンズ１１８を透過したＢＤ光、ＣＤ光およびＤＶＤ光は、光検出器１１９に入射する。光検出器１１９は、各光を受光するためのセンサレイアウトを有している。 The anamorphic lens 118 introduces astigmatism into the BD light, CD light and DVD light incident from the spectroscopic element H3 side. The anamorphic lens 118 corresponds to the anamorphic lens shown in FIGS. The BD light, CD light, and DVD light transmitted through the anamorphic lens 118 enter the photodetector 119. The photodetector 119 has a sensor layout for receiving each light.
　図１７は、光検出器１１９のセンサレイアウトを示す図である。 FIG. 17 is a diagram showing a sensor layout of the photodetector 119.
　光検出器１１９は、分光素子Ｈ３によって分離されたＢＤ光を受光するＢＤ用のセンサ部Ｂ１～Ｂ８と、分光素子Ｈ３によって分離されずに分光素子Ｈ３を透過したＣＤ光を受光するＣＤ用の４分割センサＣ０１～Ｃ０３と、分光素子Ｈ３によって分離されずに分光素子Ｈ３を透過したＤＶＤ光を受光するＤＶＤ用の４分割センサＤ０１～Ｄ０３とを有する。分光素子Ｈ３によって分離されたＢＤ光の信号光は、信号光領域の頂角部分に照射される。 The photodetector 119 includes BD sensor units B1 to B8 that receive the BD light separated by the spectroscopic element H3, and a CD sensor that receives CD light that has not been separated by the spectroscopic element H3 and has passed through the spectroscopic element H3. There are four-divided sensors C01 to C03, and four-divided sensors D01 to D03 for DVD that receive DVD light transmitted through the spectroscopic element H3 without being separated by the spectroscopic element H3. The signal light of the BD light separated by the spectroscopic element H3 is applied to the apex portion of the signal light region.
　光束領域ａ～ｈを通るＢＤ光の信号光をそれぞれ受光可能なように、信号光領域の４つの頂角付近に、図示の如く、それぞれ、センサ部Ｂ１、Ｂ２、センサ部Ｂ３、Ｂ５、センサ部Ｂ４、Ｂ６、センサ部Ｂ７、Ｂ８が配置される。なお、センサ部Ｂ１～Ｂ８は、信号光領域の４つの頂角部分の内側に照射されるＢＤ光の照射領域を十分含み得るように配置されている。これにより、経年劣化等によりセンサ部Ｂ１～Ｂ８の位置ずれが生じた場合にも、センサ部Ｂ１～Ｂ８は、分光素子Ｈ３によって分離された信号光を十分に受光することが可能となる。センサ部Ｂ１～Ｂ８上におけるＢＤ光の信号光の照射領域は、図１３（ｄ）に示すセンサ部Ｐ１１～Ｐ１８上における照射領域と略同じである。 As shown in the figure, sensor portions B1, B2, sensor portions B3, B5, and sensors are respectively provided near the four apex angles of the signal light region so that the signal light of the BD light passing through the light flux regions a to h can be received. Parts B4 and B6 and sensor parts B7 and B8 are arranged. The sensor portions B1 to B8 are arranged so as to sufficiently include the irradiation area of the BD light irradiated on the inside of the four apex angle portions of the signal light area. As a result, even when the sensor units B1 to B8 are displaced due to aging or the like, the sensor units B1 to B8 can sufficiently receive the signal light separated by the spectroscopic element H3. The irradiation area of the signal light of BD light on the sensor parts B1 to B8 is substantially the same as the irradiation area on the sensor parts P11 to P18 shown in FIG.
　ＢＤ光とＣＤ光の光軸は、上記のようにダイクロイック面１０７ａによって整合しているため、ＣＤ光のメインビーム（０次回折光）は、光検出器１１９の受光面上において、ＢＤ光の信号光領域の中心に照射される。４分割センサＣ０１は、ＣＤ光のメインビームの中心位置に配置される。４分割センサＣ０２、Ｃ０３は、ＣＤ光のサブビームを受光するよう、光検出器１１９の受光面上において、メインビームに対しトラック像の方向に配置される。 Since the optical axes of the BD light and the CD light are aligned by the dichroic surface 107a as described above, the main beam (0th order diffracted light) of the CD light is a signal of the BD light on the light receiving surface of the photodetector 119. Irradiates the center of the light region. The quadrant sensor C01 is arranged at the center position of the main beam of CD light. The quadrant sensors C02 and C03 are arranged on the light receiving surface of the photodetector 119 in the direction of the track image with respect to the main beam so as to receive the sub beam of CD light.
　ＤＶＤ光の光軸は、上記のようにＣＤ光の光軸からずれているため、ＤＶＤ光のメインビームと２つのサブビームは、光検出器１１９の受光面上において、ＣＤ光のメインビームと２つのサブビームからずれた位置に照射される。４分割センサＤ０１～Ｄ０３は、それぞれ、ＤＶＤ光のメインビームと２つのサブビームの照射位置に配置される。なお、ＣＤ光のメインビームとＤＶＤ光のメインビームとの距離は、図１６（ｃ）に示すＣＤ光とＤＶＤ光の発光点間のギャップＧによって決まる。 Since the optical axis of the DVD light is deviated from the optical axis of the CD light as described above, the main beam of the DVD light and the two sub beams are separated from the main beam of the CD light on the light receiving surface of the photodetector 119. Irradiated to a position deviated from one sub-beam. The four-divided sensors D01 to D03 are respectively arranged at the irradiation positions of the main beam and the two sub beams of DVD light. The distance between the main beam of CD light and the main beam of DVD light is determined by the gap G between the light emission points of CD light and DVD light shown in FIG.
　以上、本実施例によれば、ＢＤ光の信号光の照射領域は、図１３（ｄ）に示すように、信号光領域の４つの頂角部分の内側に分布し、ＢＤ光の迷光１、２の照射領域は、図４（ｂ）に示す状態と略同様に、信号光領域の外側に分布する。したがって、図１７に示したセンサ部Ｂ１～Ｂ８によって、ＢＤ光の信号光のみを受光することができる。これにより、迷光による検出信号の劣化が抑制され得る。 As described above, according to the present embodiment, the signal light irradiation region of the BD light is distributed inside the four apex portions of the signal light region as shown in FIG. The irradiation region 2 is distributed outside the signal light region in substantially the same manner as in the state shown in FIG. Therefore, only the signal light of the BD light can be received by the sensor units B1 to B8 shown in FIG. Thereby, deterioration of the detection signal due to stray light can be suppressed.
　また、本実施例によれば、図１３（ｄ）または図１４（ａ）～（ｄ）に示すように、信号光領域の４つの頂角部分にそれぞれ分布する２つの照射領域の外側部分または内側部分が、対応する２つのセンサ部の隙間を挟んで互いに離れている。これにより、センサ部Ｂ１～Ｂ８に位置ずれが生じても、センサ部Ｂ１～Ｂ８の検出信号が劣化し難くなる。また、信号光領域の４つの頂角部分にそれぞれ分布する２つの照射領域の外側部分または内側部分が、対応する２つのセンサ部の隙間を挟んで互いに近づいている。これにより、センサ部Ｂ１～Ｂ８の検出信号を参照することにより、面Ｓ０内でのセンサ部Ｂ１～Ｂ８の位置調整を行うことができ、センサ部Ｂ１～Ｂ８を適正に設置することが可能となる。 Further, according to the present embodiment, as shown in FIG. 13 (d) or FIGS. 14 (a) to 14 (d), the outer portions of the two irradiation regions respectively distributed in the four apex portions of the signal light region, or The inner portions are separated from each other with a gap between the corresponding two sensor portions. As a result, even if positional deviation occurs in the sensor units B1 to B8, the detection signals of the sensor units B1 to B8 are less likely to deteriorate. In addition, the outer part or the inner part of the two irradiation regions respectively distributed in the four apex angle portions of the signal light region are close to each other with a gap between the corresponding two sensor portions interposed therebetween. Thereby, by referring to the detection signals of the sensor units B1 to B8, the position of the sensor units B1 to B8 in the surface S0 can be adjusted, and the sensor units B1 to B8 can be properly installed. Become.
　また、本実施例によれば、図１３（ｄ）に示すように、回折領域Ｈ３ｂ、Ｈ３ｃ、Ｈ３ｆ、Ｈ３ｇは、回折領域Ｈ３ａ、Ｈ３ｄ、Ｈ３ｅ、Ｈ３ｈに比べて面積が大きく設定され、回折領域Ｈ３ａ、Ｈ３ｂの境界線と、回折領域Ｈ３ｃ、Ｈ３ｄの境界線と、回折領域Ｈ３ｅ、Ｈ３ｆの境界線と、回折領域Ｈ３ｇ、Ｈ３ｈの境界線には、直線部ｐ４が含まれている。これにより、レンズシフトによるプッシュプル信号ＰＰのオフセット（ＤＣ成分）が効果的に抑制され得る。また、回折領域Ｈ３ｉに入射するレーザ光はセンサ部Ｂ１～Ｂ８上に照射されないため、信号光と迷光とが干渉し難くなり、検出信号の劣化が抑制され得る。 In addition, according to the present embodiment, as shown in FIG. 13D, the diffraction regions H3b, H3c, H3f, and H3g are set to have larger areas than the diffraction regions H3a, H3d, H3e, and H3h, and the diffraction regions The boundary line between H3a and H3b, the boundary line between the diffraction regions H3c and H3d, the boundary line between the diffraction regions H3e and H3f, and the boundary line between the diffraction regions H3g and H3h include a straight line portion p4. Thereby, the offset (DC component) of the push-pull signal PP due to the lens shift can be effectively suppressed. Further, since the laser light incident on the diffraction region H3i is not irradiated onto the sensor portions B1 to B8, the signal light and the stray light are difficult to interfere with each other, and the detection signal can be prevented from deteriorating.
　また、本発明の実施例によれば、図１５（ａ）～（ｄ）に示すようにセンサレイアウトの位置がずれた場合でも、照射領域がセンサ部からはみ出し難くなるため、検出信号の精度の低下が抑制され得る。 Further, according to the embodiment of the present invention, even when the position of the sensor layout is shifted as shown in FIGS. 15A to 15D, the irradiation area is difficult to protrude from the sensor portion. The decrease can be suppressed.
　なお、本実施例において、回折領域Ｈ３ａ～Ｈ３ｈに付与されるレンズ効果は、図１３（ｃ）に示すように設定された。このようなレンズ効果は、センサ部Ｂ１～Ｂ８上の照射領域の形状がセンサ部Ｂ１～Ｂ８上に効率的に収まるように設定される。すなわち、センサ部Ｂ１～Ｂ８の頂角に合わせて、照射領域ａ３～ｈ３の形状が頂角を９０度とする扇形に近づくように、適宜レンズ効果が設定されれば良い。 In this example, the lens effect imparted to the diffraction regions H3a to H3h was set as shown in FIG. 13 (c). Such a lens effect is set so that the shape of the irradiation region on the sensor units B1 to B8 can be efficiently accommodated on the sensor units B1 to B8. That is, the lens effect may be set appropriately so that the shape of the irradiation areas a3 to h3 approaches a sector shape with the apex angle being 90 degrees in accordance with the apex angles of the sensor portions B1 to B8.
　以上、本発明の実施例について説明したが、本発明は、上記実施例に何ら制限されるものではなく、また、本発明の実施例も上記以外に種々の変更が可能である。 Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the embodiments of the present invention can be variously modified in addition to the above.
　たとえば、上記実施例では、光入射面に回折パターンが形成された分光素子Ｈ３を用いてＢＤ光を分光させたが、これに替えて、複数の面を有するプリズムからなる分光素子を用いてＢＤ光を分光させても良い。このようなプリズムの入射面には、分光素子Ｈ３の回折領域Ｈ３ａ～Ｈ３ｈに対応する８つの曲面と、回折領域Ｈ３ｉに対応する１つの面が形成される。回折領域Ｈ３ａ～Ｈ３ｈに対応する曲面に入射する光は、図１３（ａ）のＶａ～Ｖｈの方向に屈折されると共に、図１３（ｃ）に示すレンズ効果が付与される。回折領域Ｈ３ｉに対応する面に入射する光は、センサ部Ｂ１～Ｂ８上には入射しない。これにより、上記分光素子Ｈ３を用いた場合と同様、ＢＤ光の信号光は、受光面上において図１３（ｄ）に示す如く照射される。 For example, in the above-described embodiment, the BD light is dispersed using the spectroscopic element H3 having a diffraction pattern formed on the light incident surface. Instead, the BD light is separated using a spectroscopic element composed of a prism having a plurality of surfaces. The light may be dispersed. On the incident surface of such a prism, eight curved surfaces corresponding to the diffraction regions H3a to H3h of the spectroscopic element H3 and one surface corresponding to the diffraction region H3i are formed. The light incident on the curved surfaces corresponding to the diffraction regions H3a to H3h is refracted in the directions Va to Vh in FIG. 13A and has the lens effect shown in FIG. 13C. Light incident on the surface corresponding to the diffraction region H3i does not enter the sensor portions B1 to B8. Thereby, as in the case of using the spectroscopic element H3, the signal light of the BD light is irradiated on the light receiving surface as shown in FIG.
　なお、上記プリズムからなる分光素子を用いる場合、ＢＤ光を受光するための光学系と、ＣＤ光とＤＶＤ光を受光するための光学系は、別々に構成することが可能である。すなわち、図１６（ｂ）に示すＢＤ対物レンズ１１７には、ＢＤ用の光学系にてＢＤ光が導かれ、２波長対物レンズ１１６には、ＢＤ用の光学系とは別のＣＤ／ＤＶＤ用の光学系にてＣＤ光とＤＶＤ光が導かれる。ＢＤ用光学系は、ＢＤ光を発するレーザ光源と、ＢＤにて反射されたＢＤ光を受光する一つの光検出器を有し、ＣＤ／ＤＶＤ用の光学系は、ＣＤ光とＤＶＤ光を発するレーザ光源と、ＣＤ、ＤＶＤにて反射されたＣＤ光、ＤＶＤ光を受光する、ＢＤ光用の光検出器とは別の光検出器を有する。ＣＤ／ＤＶＤ用の光検出器は、ＣＤ光とＤＶＤ光をそれぞれ個別に受光する２つのセンサ群を有する。ＢＤ用光学系は、上記実施例と同様、ＢＤによって反射されたＢＤ光に非点収差を導入するアナモレンズを備える。上記プリズムからなる分光素子は、たとえば、このアナモレンズの前段に配置される。 In the case of using the spectroscopic element comprising the prism, the optical system for receiving BD light and the optical system for receiving CD light and DVD light can be configured separately. That is, the BD light is guided to the BD objective lens 117 shown in FIG. 16B by the optical system for BD, and the two-wavelength objective lens 116 is for CD / DVD different from the optical system for BD. CD light and DVD light are guided by the optical system. The optical system for BD has a laser light source that emits BD light and one photodetector that receives the BD light reflected by the BD, and the optical system for CD / DVD emits CD light and DVD light. A laser light source and a photodetector different from the photodetector for BD light that receives CD light and DVD light reflected by the CD and DVD are included. The photodetector for CD / DVD has two sensor groups that individually receive CD light and DVD light. The BD optical system includes an anamorphic lens that introduces astigmatism into the BD light reflected by the BD, as in the above embodiment. The spectroscopic element comprising the prism is disposed, for example, in the front stage of the anamorphic lens.
　また、上記実施例では、分光素子Ｈ３がアナモレンズ１１８の前段に配置されたが、分光素子Ｈ３をアナモレンズ１１８の後段に配置しても良く、あるいは、アナモレンズ１１８の入射面または出射面に、分光素子Ｈ３と同様の回折作用をレーザ光に付与する回折パターンを一体的に配しても良い。 In the above-described embodiment, the spectroscopic element H3 is disposed in front of the anamorphic lens 118. However, the spectroscopic element H3 may be disposed in the subsequent stage of the anamorphic lens 118, or the spectroscopic element is disposed on the incident surface or the exit surface of the anamorphic lens 118. A diffraction pattern that imparts the same diffractive action as that of H3 to the laser light may be integrally arranged.
　また、上記実施例において、分光素子Ｈ３の中心には回折領域Ｈ３ｉが形成されたが、これに替えて、入射するレーザ光を遮光する遮光領域が形成されても良い。この場合、ＢＤ光を受光するための光学系と、ＣＤ光とＤＶＤ光を受光するための光学系は、別々に構成することが可能である。 In the above embodiment, the diffraction region H3i is formed at the center of the spectroscopic element H3. However, instead of this, a light shielding region for shielding incident laser light may be formed. In this case, the optical system for receiving BD light and the optical system for receiving CD light and DVD light can be configured separately.
　また、分光素子Ｈ３に替えて、図８（ａ）の分光素子Ｈ１に図１３（ｃ）のレンズ効果を追加した分光素子を用いることもできる。 Further, instead of the spectroscopic element H3, a spectroscopic element obtained by adding the lens effect of FIG. 13C to the spectroscopic element H1 of FIG.
　また、上記実施例の分光素子Ｈ３の替わりに、図１８（ａ）～（ｃ）、図１９（ａ）、（ｃ）、（ｄ）に示す分光素子Ｈ４～Ｈ９が用いられても良い。各図におけるアナモレンズの平面方向、曲面方向と、各分光素子に入射するＢＤ光のトラック像の方向は、図１３（ａ）に示す方向と同じである。また、分光素子Ｈ４～Ｈ９のそれぞれ回折領域には、図１３（ｃ）の対応する回折領域と同様のレンズ効果が付与されている。 Further, in place of the spectroscopic element H3 of the above embodiment, spectroscopic elements H4 to H9 shown in FIGS. 18A to 18C, 19A, 19C, and 19D may be used. The plane direction and curved surface direction of the anamorphic lens in each figure and the direction of the track image of the BD light incident on each spectroscopic element are the same as those shown in FIG. Further, the same lens effect as that of the corresponding diffraction region in FIG. 13C is given to the diffraction regions of the spectroscopic elements H4 to H9.
　図１８（ａ）を参照して、分光素子Ｈ４は、分光素子Ｈ３の中心に形成されている回折領域Ｈ３ｉが横方向に広げられた分光素子である。図示の如く、分光素子Ｈ４の中心付近と外縁付近にある境界線は、分光素子Ｈ３と同様、上下左右方向と４５度の角度をなしている。この場合も、上記分光素子Ｈ３と同様の効果が奏される。 18A, the spectroscopic element H4 is a spectroscopic element in which a diffraction region H3i formed at the center of the spectroscopic element H3 is expanded in the lateral direction. As shown in the figure, the boundary lines near the center and the outer edge of the spectroscopic element H4 form an angle of 45 degrees with the vertical and horizontal directions as in the spectroscopic element H3. Also in this case, the same effect as the spectral element H3 is achieved.
　図１８（ｂ）を参照して、分光素子Ｈ５は、分光素子Ｈ４の中心に形成されている回折領域Ｈ４ｉが変形された分光素子である。図示の如く、回折領域Ｈ５ｉは、正方形形状の領域に、右上、左上、左下、右下から４５度の方向に所定の幅の領域が加えられた形状となっている。この場合も、上記分光素子Ｈ３と同様の効果が奏される。また、回折領域Ｈ５ｉのうち４５度方向に延びた領域により、面Ｓ０上において信号光と迷光とがさらに重畳され難くなり、複数の記録層の中からターゲットとなる記録層の判別が容易になり、ターゲットとなる記録層に対して迅速にレーザ光の焦点位置を合わせることができるようになる。 Referring to FIG. 18B, the spectroscopic element H5 is a spectroscopic element in which the diffraction region H4i formed at the center of the spectroscopic element H4 is deformed. As shown in the figure, the diffraction region H5i has a shape in which a region having a predetermined width is added to a square region in a direction of 45 degrees from the upper right, upper left, lower left, and lower right. Also in this case, the same effect as the spectral element H3 is achieved. Further, the region extending in the 45 degree direction in the diffraction region H5i makes it difficult for the signal light and the stray light to be superimposed on the surface S0, so that the target recording layer can be easily identified from the plurality of recording layers. The focal position of the laser beam can be quickly adjusted with respect to the target recording layer.
　図１８（ｃ）を参照して、分光素子Ｈ６は、分光素子Ｈ３において、回折領域Ｈ３ｉの替わりに中心を通る境界線がＸ字状に形成され、回折領域Ｈ３ａ～Ｈ３ｈが中心まで広げられた分光素子である。この場合、分光素子Ｈ６には、分光素子Ｈ３と異なり中心近傍に回折領域が形成されていないため、信号光と迷光との干渉を抑制し難くなる。しかしながら、センサレイアウトの位置ずれが生じても、センサ部Ｂ１～Ｂ８上の信号光の照射領域がセンサ部Ｂ１～Ｂ８上に位置付けられ易くなる。 Referring to FIG. 18C, in the spectroscopic element H6, in the spectroscopic element H3, a boundary line passing through the center is formed in an X shape instead of the diffraction area H3i, and the diffraction areas H3a to H3h are expanded to the center. It is a spectroscopic element. In this case, unlike the spectroscopic element H3, the spectroscopic element H6 is not formed with a diffraction region near the center, so that it is difficult to suppress interference between signal light and stray light. However, even if the sensor layout is misaligned, the signal light irradiation areas on the sensor parts B1 to B8 are easily positioned on the sensor parts B1 to B8.
　図１９（ａ）を参照して、分光素子Ｈ７は、分光素子Ｈ６の回折領域を４個にした分光素子である。分光素子Ｈ７の回折領域Ｈ７ａ～Ｈ７ｄは、入射されたレーザ光を回折作用により、それぞれ図４（ａ）の方向Ｄａ～Ｄｄに回折させる。回折領域Ｈ７ａ～Ｈ７ｄのレンズ効果は、図１９（ｂ）に示すように、上記分光素子Ｈ３と同様に設定される。ただし、分光素子Ｈ７では、図中の破線部分に回折領域の境界線がないため、破線部分で隣り合う２つの領域のレンズ効果は、破線領域において滑らかに変化するよう、回折領域Ｈ７ａ～Ｈ７ｄが構成される。 Referring to FIG. 19 (a), the spectroscopic element H7 is a spectroscopic element having four diffraction regions of the spectroscopic element H6. The diffraction regions H7a to H7d of the spectroscopic element H7 diffract the incident laser light in the directions Da to Dd in FIG. The lens effects of the diffraction regions H7a to H7d are set in the same manner as the spectral element H3 as shown in FIG. 19B. However, in the spectroscopic element H7, since there is no boundary line of the diffraction region in the broken line portion in the figure, the diffraction regions H7a to H7d are arranged so that the lens effect of two regions adjacent to each other in the broken line portion changes smoothly in the broken line region. Composed.
　この場合、回折領域Ｈ７ａ～Ｈ７ｄを通る信号光は、センサ部Ｂ１～Ｂ８上において４つの照射領域となるため、センサレイアウトの位置が上下方向と左右方向にずれることにより、それぞれ、センサ部Ｂ１、Ｂ２、Ｂ７、Ｂ８と、センサ部Ｂ３～Ｂ６の検出信号の精度が低下し易くなる。しかしながら、センサレイアウトの位置が上下方向と左右方向にずれる場合に、センサ部Ｂ３～Ｂ６と、センサ部Ｂ１、Ｂ２、Ｂ７、Ｂ８の検出信号の精度の低下が抑制され得る。 In this case, since the signal light passing through the diffraction regions H7a to H7d becomes four irradiation regions on the sensor units B1 to B8, the position of the sensor layout is shifted in the vertical direction and the horizontal direction. The accuracy of the detection signals of B2, B7, B8 and the sensor units B3 to B6 tends to be lowered. However, when the position of the sensor layout is shifted in the vertical direction and the horizontal direction, a decrease in the accuracy of the detection signals of the sensor units B3 to B6 and the sensor units B1, B2, B7, and B8 can be suppressed.
　図１９（ｃ）を参照して、分光素子Ｈ８は、分光素子Ｈ７の境界線をさらに簡素にした分光素子である。分光素子Ｈ８の回折領域Ｈ８ａ～Ｈ８ｄの境界線は、左右方向の直線に対して４５度よりも大きい角度をなしている。また、図１９（ｄ）を参照し、分光素子Ｈ９は、分光素子Ｈ８の境界線を曲線にした分光素子である。分光素子Ｈ８、Ｈ９においても、分光素子Ｈ７と同様にレンズ効果が設定され、分光素子Ｈ７と同様の効果が奏され得る。 Referring to FIG. 19C, the spectroscopic element H8 is a spectroscopic element in which the boundary line of the spectroscopic element H7 is further simplified. The boundary lines of the diffraction regions H8a to H8d of the spectroscopic element H8 form an angle larger than 45 degrees with respect to the horizontal straight line. Referring to FIG. 19D, the spectroscopic element H9 is a spectroscopic element in which the boundary line of the spectroscopic element H8 is curved. In the spectroscopic elements H8 and H9, the lens effect is set similarly to the spectroscopic element H7, and the same effect as the spectroscopic element H7 can be obtained.
　この他、本発明の実施の形態は、特許請求の範囲に示された技術的思想の範囲内において、適宜、種々の変更が可能である。 In addition, the embodiment of the present invention can be variously modified as appropriate within the scope of the technical idea shown in the claims.
　　１０１　…　半導体レーザ（レーザ光源）
　　１１７　…　ＢＤ対物レンズ（対物レンズ）
　　１１８　…　アナモレンズ（非点収差素子）
　　１１９　…　光検出器
　　Ｂ１～Ｂ８　…　センサ部
　　Ｈ３～Ｈ９　…　分光素子
　　Ｈ３ｂ、Ｈ３ｃ、Ｈ３ｆ、Ｈ３ｇ　…　回折領域（第１および第２の領域）
　　Ｈ３ａ、Ｈ３ｄ、Ｈ３ｅ、Ｈ３ｈ　…　回折領域（第３および第４の領域）
　　Ｈ３ｉ　…　回折領域（第５の領域）
　　Ｈ４ｂ、Ｈ４ｃ、Ｈ４ｆ、Ｈ４ｇ　…　回折領域（第１および第２の領域）
　　Ｈ４ａ、Ｈ４ｄ、Ｈ４ｅ、Ｈ４ｈ　…　回折領域（第３および第４の領域）
　　Ｈ４ｉ　…　回折領域（第５の領域）
　　Ｈ５ｂ、Ｈ５ｃ、Ｈ５ｆ、Ｈ５ｇ　…　回折領域（第１および第２の領域）
　　Ｈ５ａ、Ｈ５ｄ、Ｈ５ｅ、Ｈ５ｈ　…　回折領域（第３および第４の領域）
　　Ｈ５ｉ　…　回折領域（第５の領域）
　　Ｈ６ｂ、Ｈ６ｃ、Ｈ６ｆ、Ｈ６ｇ　…　回折領域（第１および第２の領域）
　　Ｈ６ａ、Ｈ６ｄ、Ｈ６ｅ、Ｈ６ｈ　…　回折領域（第３および第４の領域）
　　Ｈ７ｂ、Ｈ７ｃ　…　回折領域（第１および第２の領域）
　　Ｈ７ａ、Ｈ７ｄ　…　回折領域（第３および第４の領域）
　　Ｈ８ｂ、Ｈ８ｃ　…　回折領域（第１および第２の領域）
　　Ｈ８ａ、Ｈ８ｄ　…　回折領域（第３および第４の領域）
　　Ｈ９ｂ、Ｈ９ｃ　…　回折領域（第１および第２の領域）
　　Ｈ９ａ、Ｈ９ｄ　…　回折領域（第３および第４の領域） 101 ... Semiconductor laser (laser light source)
117 ... BD objective lens (objective lens)
118 ... Anamo lens (astigmatism element)
119: Photodetector B1 to B8: Sensor unit H3 to H9: Spectroscopic element H3b, H3c, H3f, H3g: Diffraction region (first and second regions)
H3a, H3d, H3e, H3h ... Diffraction region (third and fourth regions)
H3i: Diffraction region (fifth region)
H4b, H4c, H4f, H4g ... Diffraction region (first and second regions)
H4a, H4d, H4e, H4h ... Diffraction region (third and fourth regions)
H4i: Diffraction region (fifth region)
H5b, H5c, H5f, H5g ... Diffraction region (first and second regions)
H5a, H5d, H5e, H5h ... Diffraction region (third and fourth regions)
H5i: Diffraction region (fifth region)
H6b, H6c, H6f, H6g ... Diffraction region (first and second regions)
H6a, H6d, H6e, H6h ... Diffraction region (third and fourth regions)
H7b, H7c ... Diffraction region (first and second regions)
H7a, H7d: Diffraction region (third and fourth regions)
H8b, H8c ... Diffraction region (first and second regions)
H8a, H8d ... Diffraction region (third and fourth regions)
H9b, H9c ... Diffraction region (first and second regions)
H9a, H9d: Diffraction region (third and fourth regions)

Claims (6)

  1. 　レーザ光源と、
    　前記レーザ光源から出射されたレーザ光を記録媒体上に収束させる対物レンズと、
    　前記記録媒体によって反射された前記レーザ光が入射されるとともに、第１の方向に前記レーザ光を収束させて第１の焦線を生成し、且つ、前記第１の方向に垂直な第２の方向に前記レーザ光を収束させて第２の焦線を生成する非点収差素子と、
    　前記記録媒体によって反射された前記レーザ光が入射されるとともに、第１ないし第４の領域に入射された各光束の進行方向を互いに異ならせ、これら４つの光束を互いに離散させる分光素子と、
    　センサ部を備えると共に当該センサ部により前記離散された各光束を受光して検出信号を出力する光検出器と、を備え、
    　前記第１の方向と前記第２の方向にそれぞれ平行で且つ互いにクロスする第１および第２の直線の交点を前記分光素子の中心に整合させたとき、前記第１および第２の直線によって作られる一組の対頂角が並ぶ方向に前記第１および第２の領域が配置され、他の一組の対頂角が並ぶ方向に前記第３および第４の領域が配置され、
    　前記第１および第２の領域が並ぶ方向が、前記分光素子に投影された前記記録媒体のトラック像の方向と平行となるように前記非点収差素子が配置され、
    　前記第１および第２の領域と前記第３および第４の領域とは互いに面積が異なり、各領域は、前記分光素子の中心から離れるに従って広がっており、
    　前記分光素子は、さらに、前記各領域を通る光束が前記センサ部に照射されるときに、これら光束の形状が頂角を９０度とする扇形に近づくように、これら光束に光学作用を付与する、
    ことを特徴とする光ピックアップ装置。     A laser light source;
    An objective lens for converging the laser light emitted from the laser light source onto a recording medium;
    The laser light reflected by the recording medium is incident, the laser light is converged in a first direction to generate a first focal line, and a second perpendicular to the first direction is generated. An astigmatism element that converges the laser beam in a direction to generate a second focal line;
    A spectroscopic element that makes the laser light reflected by the recording medium incident thereon, makes the traveling directions of the light beams incident on the first to fourth regions different from each other, and makes the four light beams discrete from each other;
    A photodetector that includes a sensor unit and that receives each of the light fluxes separated by the sensor unit and outputs a detection signal;
    When the intersecting point of the first and second straight lines that are parallel to and cross each other in the first direction and the second direction are aligned with the center of the spectroscopic element, the first and second straight lines are formed. The first and second regions are arranged in the direction in which the set of vertical angles are arranged, and the third and fourth regions are arranged in the direction in which the other set of vertical angles are arranged,
    The astigmatism element is arranged so that the direction in which the first and second regions are arranged is parallel to the direction of the track image of the recording medium projected onto the spectroscopic element,
    The first and second regions and the third and fourth regions have different areas, and each region spreads away from the center of the spectroscopic element,
    The spectroscopic element further imparts an optical action to the luminous flux so that when the luminous flux passing through each of the regions is irradiated onto the sensor unit, the shape of the luminous flux approaches a fan shape having an apex angle of 90 degrees. ,
    An optical pickup device characterized by that.
  2. 　請求項１に記載の光ピックアップ装置において、
    　前記第１および第２の領域は前記第３および第４の領域よりも面積が大きく、
    　前記第１および第２の領域を通る光束に付与される前記光学作用は、これら第１および第２の領域が並ぶ方向に平行な２方向の収束作用を含み、これら第１および第２の領域による２方向の収束作用は、前記分光素子の中心から遠くなるに従って大きくなるよう設定され、前記第３および第４の領域を通る光束に付与される前記光学作用は、これら第３および第４の領域が並ぶ方向に平行な２方向の収束作用を含み、これら第３および第４の領域による２方向の収束作用は、前記分光素子の中心に近づくに従って大きくなるよう設定されている、
    ことを特徴とする光ピックアップ装置。     The optical pickup device according to claim 1,
    The first and second regions have a larger area than the third and fourth regions,
    The optical action imparted to the light beam passing through the first and second regions includes a converging action in two directions parallel to the direction in which the first and second regions are arranged, and the first and second regions. Is set so as to increase as the distance from the center of the spectroscopic element increases, and the optical action imparted to the light beam passing through the third and fourth regions is determined by the third and fourth. Including the convergence action in two directions parallel to the direction in which the regions are arranged, the convergence action in the two directions by the third and fourth regions is set so as to increase as it approaches the center of the spectroscopic element.
    An optical pickup device characterized by that.
  3. 　請求項１または２に記載の光ピックアップ装置において、
    　前記分光素子の中心部分にさらに第５の領域が配置され、
    　前記第５の領域を通る光束は、前記センサ部上に照射されない、
    ことを特徴とする光ピックアップ装置。     The optical pickup device according to claim 1 or 2,
    A fifth region is further arranged in the central portion of the spectroscopic element,
    The light flux passing through the fifth region is not irradiated on the sensor unit.
    An optical pickup device characterized by that.
  4. 　請求項１ないし３の何れか一項に記載の光ピックアップ装置において、
    　前記第１および第２の領域がそれぞれ前記トラック像に垂直な方向に２分割されて４つの分割領域が形成され、
    　前記第３および第４の領域がそれぞれ前記トラック像に平行な方向に２分割されて４つの分割領域が形成され、
    　前記分光素子は、前記第１の領域の２つの前記分割領域を通る光束部分が前記光検出器上で離間し、前記第２の領域の２つの前記分割領域を通る光束部分が前記光検出器上で離間し、前記第３の領域の２つの前記分割領域を通る光束部分が前記光検出器上で離間し、前記第４の領域の２つの前記分割領域を通る光束部分が前記光検出器上で離間するよう、前記各分割領域を通る前記光束部分の進行方向を変化させる、
    ことを特徴とする光ピックアップ装置。     In the optical pick-up device according to any one of claims 1 to 3,
    The first and second regions are each divided into two in a direction perpendicular to the track image to form four divided regions,
    The third and fourth regions are each divided into two in a direction parallel to the track image to form four divided regions,
    In the spectroscopic element, a light beam portion passing through the two divided regions of the first region is separated on the photodetector, and a light beam portion passing through the two divided regions of the second region is the photodetector. A light beam portion that is spaced above and passes through the two divided regions of the third region is spaced apart on the photodetector, and a light beam portion that passes through the two divided regions of the fourth region is the photodetector. Changing the traveling direction of the light beam portion passing through each of the divided regions so as to be separated from the upper side;
    An optical pickup device characterized by that.
  5. 　請求項１ないし４の何れか一項に記載の光ピックアップ装置において、
    　前記第１および第２の領域と、前記第３および第４の領域との間の境界が、前記第３および第４の領域の並び方向に平行な直線部分を含む、
    ことを特徴とする光ピックアップ装置。     The optical pickup device according to any one of claims 1 to 4,
    A boundary between the first and second regions and the third and fourth regions includes a straight line portion parallel to an arrangement direction of the third and fourth regions;
    An optical pickup device characterized by that.
  6. 　請求項１ないし５の何れか一項に記載の光ピックアップ装置において、
    　前記分光素子は、前記第１ないし第４の領域を通った各光束が前記光検出器の受光面上において直方形の異なる４つの頂角の位置にそれぞれ導かれるよう、４つの前記光束の進行方向を、前記第１および第２の方向に対し４５度の方向で、且つ、所定の角度だけ変化させる、
    ことを特徴とする光ピックアップ装置。     The optical pickup device according to any one of claims 1 to 5,
    In the spectroscopic element, the four light beams travel so that the light beams that have passed through the first to fourth regions are respectively guided to four vertex angles in different rectangular shapes on the light receiving surface of the photodetector. Changing the direction in a direction of 45 degrees with respect to the first and second directions and by a predetermined angle;
    An optical pickup device characterized by that.
PCT/JP2011/075385 2011-02-24 2011-11-04 Light pick-up device WO2012114583A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010055737A (en) * 2008-08-01 2010-03-11 Sanyo Electric Co Ltd Optical pickup device, focus adjusting method, and optical disk device
JP2010272145A (en) * 2009-04-20 2010-12-02 Sanyo Electric Co Ltd Optical pickup device and optical disk device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010055737A (en) * 2008-08-01 2010-03-11 Sanyo Electric Co Ltd Optical pickup device, focus adjusting method, and optical disk device
JP2010272145A (en) * 2009-04-20 2010-12-02 Sanyo Electric Co Ltd Optical pickup device and optical disk device

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