JP2008130142A - Optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device to stabilize a push-pull signal of a sub-beam by stray light, while being compatible with a double-layer optical information recording medium. <P>SOLUTION: The device is provided with a semiconductor laser 102 emitting a light beam L1 having wavelength corresponding to recording/reproducing of the double-layer optical information recording medium 101, a diffraction grating 103 diffracting the light beam L1 of wavelength to a main beam of 0th order diffraction light and a sub-beam of ±1st order diffraction light, a 1/4 wavelength plate 104 polarizes the light beam L1 of linear polarization (p polarization) to circular polarization, a hologram element 105 diffracting the light beam L1 reflected by the double-layer optical information recording medium 101, a first light receiving element group 106 receiving diffracted light from the hologram element 105, and a second light receiving element group 107 or the like. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical information processing apparatus that performs processing such as information recording, reproduction, and erasing on an optical information recording medium such as an optical disk. Alternatively, the present invention relates to an optical pickup device having a detection function of a recording signal and various servo signals.

  Currently, in order to record high-definition video and information, it is necessary to increase the capacity that can be recorded on one optical information recording medium. Therefore, it is considered to provide a plurality of recording layers on the optical information recording medium. As reproduction-only, there are dedicated optical information recording media such as DVD-ROM, DVD-Video, etc., and one-sided two-layer recording is commercialized. For recording only, single-sided, dual-layer optical information recording media such as DVD-R DL (Dual Layer) and DVD + R DL (Double Layer) have been commercialized. As next-generation optical information recording media, optical information recording media for reproduction and recording on one side and two layers such as Blu-Ray Disc and HD-DVD have appeared. Furthermore, optical information recording media for reproduction and recording with four layers and eight layers on one side are considered. In order to reproduce and record such an optical information recording medium, for example, a technique disclosed in Patent Document 1 is proposed.

  Conventionally, an optical pickup device as shown in FIG. 14 has been considered. The operation principle of this conventional optical pickup device will be described below. FIG. 14 is a diagram showing the optical principle of a general optical pickup device using a diffraction grating (hologram). In the optical pickup device shown in FIG. 14, 1 is a semiconductor laser element that emits a laser light source for recording / reproduction, 2 is a collimator lens that makes this laser light source a parallel light beam, 3 is a laser beam that is a main beam, 2 It is a diffraction grating that diffracts a sub-beam of a book. 4 is a polarization beam splitter, 5 is an optical information recording medium, 6 is a rising mirror for directing three beams in the direction of the optical information recording medium 5, 7 is a quarter-wave plate for converting linearly polarized light into circularly polarized light, 8 Is an objective lens for focusing the three beams on the optical information recording medium 5, 9 is a photodetector for receiving the reflected light from the optical information recording medium 5, and 10 is for collecting the reflected light on the photodetector 9. A condensing lens 11 is a hologram element for diffracting reflected light to the photodetector 9. The hologram element 11 has a disk shape as shown in FIG. 15 and has one dividing line 12 passing through the center thereof. In FIG. 15, two types of diffraction areas are formed on the left and right sides of the dividing line 12. Yes. The direction of the dividing line 12 is set to be substantially parallel to the track direction of the optical information recording medium 5 in the beam pattern of the beam reflected from the optical information recording medium 5. And the grating | lattice of each hologram area | region 11A, 11B is formed in circular arc shape.

  Accordingly, the three beams (one main beam and two sub beams) are incident across the dividing line 12, so that at least twelve ± first-order diffracted lights are formed. The photodetector 9 receiving the ± first-order diffracted light has a light receiving surface as shown in FIG. In this example, a spot size method (SSD method) is used for focus detection, and a phase difference method (DPD method) and a differential push-pull method (DPP method) are used for tracking detection. That is, this light receiving surface is composed of twelve photodetection segments 14 to 25 arranged in three stages, two on the left and right with the center line 13 as the axis of symmetry, each of which the above-mentioned twelve ± first-order diffracted lights reach. It is arranged corresponding to. The middle four light detection segments 18 to 21 correspond to spots by the main beam SP1, and perform focus detection and DPD detection. The upper and lower light detection segments 14 to 17 and 22 to 25 correspond to the light spots by the two sub beams SP2 and SP3, respectively, and perform DPP detection. In addition, each of the middle light detection segments 18 to 21 is divided into four in the horizontal direction to form four cells. Accordingly, there are 24 divided regions on the entire light receiving surface. Further, the light passing through one hologram area 11A is incident on the outer two segments 14, 18, 22 and 17, 21, 25 of the four columns, and the other hologram area 11B is passed through. The pitch and pattern of the hologram are set so that the light passing therethrough is incident on the inner two rows of segments 15, 19, 23 and 16, 20, 24.

  In this example, the focus error signal of the servo error signal is detected FE (SSD) by the SSD method, and the tracking error signal is DPD method TE (DPD) and DPP method TE (DPP) (main push pull TE (MPP) and sub push pull). TE (SPP) calculation) and generated by the following calculation.

FE (SSD) = (B + C + F + G) − (A + D + E + H)
TE (DPD) = phase (A + B, E + F) + phase (C + D, G + H)
TE (MPP) = (A + B + C + D) − (E + F + G + H)
TE (SPP) = I−J
TE (DPP) = TE (MPP) −Gain (TE (SPP))
Here, phase () is a phase comparison, Gain () is a certain coefficient, A, B, C, D, E, F, G, H, I, J are the following using the symbol of the segment shown in FIG. Thus, A = A1 + A2, B = B1 + B2, C = C1 + C2, D = D1 + D2, E = E1 + E2, F = F1 + F2, G = G1 + G2, H = H1 + H2, I = I1 + I2 + I3 + I4, J = J1 + J2 + J3 + J4.
JP 2001-229573 A

  However, in the conventional optical pickup device as shown in FIG. 14, in the case of an optical information recording medium having two recording layers, unnecessary reflection from recording layers other than the recording layer on which information is recorded / reproduced. The light recording boundary (other layer recording boundary stray light) becomes a problem. Specifically, the boundary between the light reflected by the recording layer that is recording / reproducing information and the recording layer that is reflected by the recording layer other than the recording layer that is recording / reproducing information and the non-recording layer If the light is detected in a state where the light overlaps, it is impossible to obtain an accurate light amount. The tracking error signal is detected by the DPP method.

  One problem arises when recording and reproducing a two-layer optical information recording medium with an optical pickup device using such a general diffraction grating (hologram element). The two-layer optical information recording medium has two recording layers in the thickness direction of the medium, and the first recording layer close to the optical pickup device is composed of a translucent recording layer, and the first recording layer is formed by the optical pickup device. By changing the focus between the recording layer and the second recording layer, recording or reproduction can be performed on both layers.

  A problem occurs when detecting a tracking signal of such a two-layer optical information recording medium. The tracking sub push-pull signal of the two-layer optical information recording medium is disturbed. The cause is that it is reflected defocused light from the other recording layer that is not focused and covers the light receiving area of the detector 9.

  This is shown in FIG. FIG. 17 shows a state in which the first recording layer 26 close to the optical pickup device in the two-layer optical information recording medium is focused. On the detector 9, in addition to the focused beam from the focused first recording layer 26, defocused light from the other off-focus layer (second recording layer 27) that is not focused is received. Incident into the area. When the defocused light passes through the recording area 28 and the unrecorded area 29 of the second recording layer 27, the defocusing light particularly affects the tracking error signal due to the unbalance of the light quantity, and the light quantity is larger than the sub-beam among the three beams. The main factor is the defocused light of the main beam having a large size. FIG. 18 shows a state in which defocused light of the main beam is incident so as to cover each segment. The defocused light of the main beam protrudes from the segments 18, 19, 20, and 21 that generate TE (MPP) and reaches the segments 14, 15, 16, 17, 22, 23, 24, and 25 that generate TE (SPP). Incident. Usually, since the gain of the segment that generates the TE (SPP) signal is set to be larger than the gain of the segment that generates the TE (MPP), the defocused light strongly affects the TE (SPP). FIG. 19 shows a TE (SPP) signal when the defocused light passes across the recording area 28 and the unrecorded area 29 of the second recording layer 27 (this time, the case where there is no AC signal) is shown. . As described above, the TE (SPP) signal fluctuates when passing over the recording area 28 and the non-recording area 29, so that there is a problem that a stable tracking error signal cannot be generated. A similar problem occurs when focusing on the second recording layer 27.

  Accordingly, the present invention takes into consideration the problems of the conventional optical pickup device as described above, and is capable of dealing with at least two layers of optical information recording media, and at the same time, realizes more accurate and stable recording and / or reproduction. An optical pickup device capable of detecting an error signal is provided.

  According to a first aspect of the present invention, there is provided a semiconductor laser element that emits a light beam, a diffraction grating that diffracts the light beam into a main beam and two sub-beams, and a diffracted light diffracted by the diffraction grating on an optical information recording medium. A condensing optical system for condensing on the surface, a hologram element for diffracting the return light reflected from the optical information recording medium, and a plurality of light receiving elements for receiving the diffracted light diffracted by the hologram element The hologram element is divided into a first area and a second area by a dividing line that is substantially parallel to the track direction of the optical information recording medium, and further in a direction substantially perpendicular to the track direction. The first region is divided into a first first region and a first second region, and the second region is a second first region located next to the first first region. And next to the first two regions The diffracted light which is divided into the second two regions and diffracted by the first one region and the second one region of the hologram element is sent to the plurality of light receiving elements and the track of the optical information recording medium. The diffracted light that is diffracted and incident so as to be substantially aligned in a direction substantially parallel to the direction is diffracted by the first two regions and the second two regions of the hologram element, The light receiving element that diffracts and enters the plurality of light receiving elements so as to be substantially aligned in a direction substantially parallel to a track direction of the optical information recording medium and contributes to a push-pull signal of the sub beam. In the optical pickup device, the element is divided into six regions by a dividing line parallel to a direction perpendicular to the track direction.

  Further, according to a second aspect of the present invention, the semiconductor laser element emits light beams of two different wavelengths, and a sub beam generated from the light beam of one wavelength is divided into six regions in a focused state. The sub-beams that are incident on four of the light receiving elements and are generated from the light beam of the other wavelength are incident on four of the light receiving elements that are divided into six regions in the focused state, and are divided into six regions. Further, two of the light receiving elements are optical pickup devices in which both sub beams generated from light beams having two different wavelengths are incident.

  According to a third aspect of the present invention, the diffraction grating generates a sub-beam in a substantially semicircular region, and the area of the light-receiving element of the sub-beam is approximately halved so that the optical information recording medium is focused. An optical pickup device that reduces a stray light offset of a tracking signal caused by return light reflected from a portion other than a recording layer.

  According to a fourth aspect of the present invention, each of the first, first, second, second and second regions of the hologram element is close to the optical information recording medium with respect to the light receiving element. A region where power is applied so that an image is formed at a position and a region where power is applied so that an image is formed at a position far from the optical information recording medium with the light receiving element as a reference are alternately strip-shaped. The optical pickup device is characterized in that the optical pickup device is formed.

  According to a fifth aspect of the present invention, there is provided the optical pickup device, wherein the light receiving element is disposed on both sides of the beam emitted from the semiconductor laser.

  According to a sixth aspect of the present invention, the light receiving element is formed on a semiconductor substrate, and the semiconductor laser is mounted on the semiconductor substrate.

  According to a seventh aspect of the present invention, an output for generating a focus error signal is output from the light receiving element disposed on one side of the semiconductor laser, and a tracking error signal is generated from the light receiving element disposed on the other side of the semiconductor laser. This is an optical pickup device characterized by

  An eighth aspect of the present invention is an optical pickup device characterized in that the diffraction grating and the hologram element are formed by one optical member.

  According to a ninth aspect of the present invention, there is provided an optical pickup device, wherein the semiconductor substrate including the diffraction grating, the hologram element, the semiconductor laser, and the plurality of light receiving elements is incorporated in one package. It is.

  According to a tenth aspect of the present invention, there is provided an optical pickup apparatus characterized in that a wavelength of a light beam emitted from the semiconductor laser includes a 650 nm band.

  The eleventh aspect of the present invention is an optical pickup device characterized in that a wavelength of a light beam emitted from the semiconductor laser includes a 405 nm band.

  According to the optical pickup device of the present invention, it is possible to cope with an optical information recording medium of at least two layers, and to detect a tracking error signal that realizes more accurate and stable recording and / or reproduction. It is.

  Embodiments according to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 schematically shows the configuration of the optical pickup device according to the first embodiment of the present invention.

  The optical pickup device shown in FIG. 1 includes a semiconductor laser 102 that emits a first light beam L1 corresponding to recording and reproduction of the optical information recording medium 101 and a second light beam L2 having a longer wavelength than L1. The diffraction beam 103 for diffracting the light beam L1 and the light beam L2 into a main beam of 0th order diffracted light and a sub beam (not shown) of ± 1st order diffracted light, and light beams L1 and L2 of linearly polarized light (p polarized light) A quarter-wave plate 104 that circularly polarizes the light beam, a hologram element 105 that diffracts the light beam L1 and the light beam L2 reflected from the optical information recording medium 101, and diffracted light from the hologram element 105 An integrated circuit substrate 108 in which a first light receiving element group 106 and a second light receiving element group 107 for receiving light are formed on the same substrate is provided. Further, the diffraction grating 103 and the hologram element 105 are formed of an optical substrate 109 formed of an integral optical element. Further, a collimator lens 110 and an objective lens 111 are provided between the quarter wavelength plate 104 and the optical information recording medium 101. The optical substrate 109 and the integrated circuit substrate 108 are integrated by a package 112. The first light receiving element group 106 is a light receiving element group for generating a tracking error signal, and the second light receiving element group 107 is a light receiving element group for generating a focus error signal.

  Next, the operation of the optical pickup device of this embodiment will be described.

  First, when reproducing or recording the optical information recording medium 101, the semiconductor laser 102 is driven, and the light beam L1 emitted from the semiconductor laser 102 is transmitted through the diffraction grating 103 to the main beam of 0th order diffracted light and the subbeams of ± 1st order diffracted light ( (Not shown) diffracted, and by the quarter wavelength plate 104, the p-polarized light beam L1 becomes circularly polarized light, is condensed and reflected by the optical information recording medium 101 through the collimator lens 110 and the objective lens 111, The light passes through the objective lens 111 and the collimator lens 110 again, enters the quarter-wave plate 104, becomes s-polarized light, and enters the hologram element 105 that is a light beam branching unit. As shown in FIG. 2, the hologram element 105 is divided into four regions 115, 116, 117, and 118 by a dividing line 114 parallel to a track of the optical information recording medium 101 and a dividing line 114 perpendicular to the track. The four divided regions of the hologram element 105 are regions 115a, 116a, 117a, and 118a to which power is applied so as to form an image at a position close to the optical information recording medium 101 with the light receiving element groups 106 and 107 as a reference. And regions 115b, 116b, 117b, and 118b to which power is applied so as to form an image at a position far from the optical information recording medium 101 with respect to the light receiving elements 106 and 107 are alternately formed in a strip shape. ing. The light receiving element groups 106 and 107 of the integrated circuit board 108 are as shown in FIG. The light receiving element group 106 is divided into 10 parts such as eyes, fields, and eye shapes, and the light receiving element group 107 is divided into 5 parts. The main beam of the light beam L1 incident on the hologram element 105 is diffracted by the region 115 to become the spot 115DM in FIG. 3, diffracted by the region 116 to become the spot 116DM in FIG. 3, and diffracted by the region 117. 3 to be spot 117DM in FIG. 3, and diffracted by region 118 to become spot 118DM in FIG. The sub-beam of the light beam L1 incident on the hologram element 105 is diffracted by the region 115 to become the spot 115DS in FIG. 3, diffracted by the region 116 to become the spot 116DS in FIG. 3, and diffracted by the region 117. 3 becomes spot 117DS in FIG. 3, and is diffracted by region 118 to become spot 118DS in FIG. Similarly for the light beam L2, the light beam L2 emitted from the semiconductor laser 102 is diffracted by the diffraction grating 103 into a main beam of 0th-order diffracted light and a sub-beam (not shown) of ± 1st-order diffracted light, and ¼ wavelength. On the plate 104, the p-polarized light beam L1 becomes circularly polarized light, is condensed and reflected by the optical information recording medium 101 through the collimator lens 110 and the objective lens 111, and again passes through the objective lens 111 and the collimator lens 110 to be 1 / The light enters the four-wave plate 104 and becomes s-polarized light, and enters the hologram element 105 that is a light beam branching unit. The main beam of the light beam L2 incident on the hologram element 105 is diffracted by the region 115 into the spot 115CM in FIG. 3, diffracted by the region 116 into the spot 116CM in FIG. 3, and diffracted by the region 117. The spot 117CM shown in FIG. 3 is received, and is diffracted by the region 118 to become the spot 118CM shown in FIG. The sub beam of the light beam L2 incident on the hologram element 105 is diffracted by the region 115 to become the spot 115CS in FIG. 3, diffracted by the region 116 to become the spot 116CS in FIG. 3, and diffracted by the region 117. 3 becomes spot 117CS in FIG. 3, and is diffracted by region 118 to become spot 118CS in FIG.

  Next, the focus error signal of the servo error signal is detected FE (SSD) by the SSD method, and the tracking error signal is DPD method TE (DPD) and DPP method TE (DPP) (main push pull TE (MPP) and sub push pull). TE (SPP) calculation) and generated by the following calculation.

FE (SSD) = GH
TE (DPD) = phase (A, D) −phase (B, C)
TE (MPP) = (C + D) − (A + D)
TE (SPP) = EF
TE (DPP) = TE (MPP) −Gain (TE (SPP))
Here, phase () is a phase comparison, Gain () is a certain coefficient, A, B, C, D, E, F, G, and H are as follows using the symbol of the segment shown in FIG. = A101, B = B101, C = C101, D = D101, E = E101 + E102 + E103, F = F101 + F102 + F103, G = G101 + G102 + G103, H = H101 + H102.

Next, a two-layer optical information recording medium will be described. FIG. 5 shows a state in which the first recording layer 120 close to the optical pickup device in the two-layer optical information recording medium 119 is focused. In addition to the focused beam from the first recording layer 120 focused on the light receiving element groups 106 and 107, defocusing from the other off-focus layer (second recording layer 121) that is not focused. Light enters the light receiving element groups 106 and 107. When the defocused light passes across the recording area 122 and the unrecorded area 123 of the second recording layer 121, the defocused light particularly affects the tracking error signal due to the unbalance of the light quantity, and the light quantity is more than the sub-beam among the three beams. The main factor is the defocused light of the main beam having a large size. FIG. 6 shows a state in which the defocus light of the main beam is incident so as to cover each segment (only the defocus light incident on the light receiving element group 106 for tracking error signals is shown). The defocused light of the main beam protrudes from the segments A, B, C, and D that generate TE (MPP) and enters the segments E and F that generate TE (SPP). Usually, the gains of the segments E and F that generate the TE (SPP) signal are set larger than the gains of the segments A, B, C, and D that generate the TE (MPP). SPP) is strongly affected. FIG. 7 shows a TE (SPP) signal when the defocused light passes across the recording area 122 and the unrecorded area 123 of the second recording layer 121 (this time, the case where there is no AC signal) is shown. . Thus, even if the TE (SPP) signal passes across the recording area 122 and the unrecorded area 123, it generates a substantially flat and stable tracking error signal. This makes it possible to generate a stable tracking error signal because the output changes of the segments E and F are substantially uniform even when the defocused light crosses the recording / non-recording boundary. FIG. 8 shows a state in which defocused light of the main beam is incident so as to cover each segment when focused on the second recording layer 121. In this case as well, a stable tracking error signal can be generated.
As an example of the diffraction of the hologram element 105 of the present invention, in the above embodiment, the case of the beam spot of FIG. 3 has been described. However, the present invention is not limited to this. For example, the beam spot of FIG. Also good.
Further, as an example of the recording surface of a plurality of layers of the optical information recording medium, the above embodiment has been described with respect to the case where the recording surface has two recording layers. An optical information recording medium may be used, and in this case as well, the same effect as in the case of two layers can be exhibited.

  Further, in the above embodiment, the optical pickup device of the present invention has been described with respect to a configuration in which an optical information recording medium capable of recording and reproduction is handled. However, the present invention is not limited to this. For example, only recording or reproduction is possible. An optical pickup device may be used.

  In the above embodiment, the quarter wavelength plate 104 is disposed between the hologram element 105 and the collimator lens 110. However, the quarter wavelength plate 104 may be integrated with the hologram element 105. The quarter wavelength plate 104 may be disposed between the objective lens 111 and the collimator lens 110.

  In the above embodiment, the wavelength of the light beam of the semiconductor laser may be a 650 nm band corresponding to the DVD system of the optical information recording medium, or corresponds to the HD-DVD and Blu-Ray Disc system of the optical information recording medium. A 405 nm band may be used. The semiconductor laser may oscillate only a single wavelength.

  According to the present embodiment, it is possible to cope with at least two layers of optical information recording media, and it is possible to detect a tracking error signal that realizes more accurate and stable recording / reproduction.

(Second Embodiment)
A schematic diagram of an optical pickup device in the second embodiment of the present invention is as shown in FIG. 1, as in the first embodiment. However, as shown in FIG. 9, in the diffraction grating 103, no grating is formed in the effective area 124 of the main beam, and the sub-beam 125 is effective in a substantially semicircular area 125 in the direction parallel to the track of the optical information recording medium. Thus, the lattice 126 is formed.

  Next, the spots on the light receiving element 108 in this embodiment will be described. FIG. 10 is a spot diagram on the light receiving element 108 in this embodiment, and on the light receiving element groups 106 and 107, a condensed beam spot from the focused recording layer of the optical information recording medium is shown. Here, in FIG. 3, which is the first embodiment, four spots 115DS, 116DS, 117DS, and 118DS are generated for each of the preceding sub-beam and the following sub-beam of the light beam L1, and the preceding sub-beam and the rear of the light beam L2 are generated. Four spots of 115CS, 116CS, 117CS, and 118CS are generated for each row sub-beam. In the second embodiment, the effective area of the sub-beam on the diffraction grating 103 is almost a semicircle. As shown in FIG. 10, there are two spots each for the preceding sub beam and the succeeding sub beam, or the remaining two spots have sufficiently small intensities. Therefore, the light receiving area of the sub beam can be reduced to approximately half. In the present embodiment, the defocused light of the main beam from the off-focus layer 121 when entering the first recording layer 120 in the two-layer optical information recording medium in FIG. 5 is incident so as to cover each segment. FIG. 12 shows the state (only the defocused light incident on the light receiving element group 106 for tracking error signals is shown). The defocused light of the main beam protrudes from the segments A, B, C, and D that generate TE (MPP) and enters the segments E and F that generate TE (SPP). In comparison, the detected amount of stray light is small, and stable TE (SPP) can be obtained. In addition, the defocused light of the main beam from the off-focus layer 120 is incident so as to cover each segment when focusing on the second recording layer 121 in the two-layer optical information recording medium of FIG. FIG. 13 shows only defocused light incident on the tracking error signal light receiving element group 106. Even in this case, stable TE (SPP) can be obtained.

As an example of the diffraction of the hologram element 105 of the present invention, in the above embodiment, the case of the beam spot of FIG. 10 has been described. However, the present invention is not limited to this. For example, the beam spot of FIG. Also good.
Further, as an example of the recording surface of a plurality of layers of the optical information recording medium, the above embodiment has described the case of having two recording surfaces. However, the present invention is not limited to this. For example, the recording surface has three or more recording surfaces. An optical information recording medium may be used, and in this case as well, the same effect as in the case of two layers can be exhibited.

  Further, in the above embodiment, the optical pickup device of the present invention has been described with respect to a configuration in which an optical information recording medium capable of recording and reproduction is handled. However, the present invention is not limited to this. For example, only recording or reproduction is possible. An optical pickup device may be used.

  In the above embodiment, the quarter wavelength plate 104 is disposed between the hologram element 105 and the collimator lens 110. However, the quarter wavelength plate 104 may be integrated with the hologram element 105. The quarter wavelength plate 104 may be disposed between the objective lens 111 and the collimator lens 110.

  In the above embodiment, the wavelength of the light beam of the semiconductor laser may be a 650 nm band corresponding to the DVD system of the optical information recording medium, or corresponds to the HD-DVD and Blu-Ray Disc system of the optical information recording medium. A 405 nm band may be used.

  According to the present embodiment, it is possible to cope with at least two layers of optical information recording media, and it is possible to detect a tracking error signal that realizes more accurate and stable recording / reproduction.

  The optical pickup device according to the present invention is compatible with at least two layers of optical information recording media, and can detect a tracking error signal that realizes more accurate and stable recording and / or reproduction. Useful as a device.

1 is a schematic cross-sectional view showing a configuration of a main part of an optical system of an optical pickup device according to a first embodiment and a second embodiment of the present invention. Schematic configuration diagram of the hologram element of the optical pickup device of the first embodiment and the second embodiment of the present invention 1 is a schematic plan configuration diagram of an integrated circuit board of an optical pickup device according to a first embodiment of the present invention. 1 is a schematic plan configuration diagram of an integrated circuit board of an optical pickup device similar to the first embodiment of the present invention. Schematic sectional view of a two-layer optical information recording medium The main beam spot image figure which defocused on the schematic plane block diagram of the integrated circuit board of the optical pick-up apparatus of the 1st Embodiment of this invention Signal at recording / unrecording boundary of TE (SPP) of optical pickup apparatus according to first embodiment of the present invention The main beam spot image figure which defocused on the schematic plane block diagram of the integrated circuit board of the optical pick-up apparatus of the 1st Embodiment of this invention Schematic configuration diagram of a diffraction grating of an optical pickup device according to a second embodiment of the present invention Schematic plan view of an integrated circuit board of an optical pickup device according to a second embodiment of the present invention Schematic plan view of an integrated circuit board of an optical pickup device similar to the second embodiment of the present invention The main beam spot image figure defocused on the schematic plane block diagram of the integrated circuit board of the optical pick-up apparatus of the 2nd Embodiment of this invention The main beam spot image figure defocused on the schematic plane block diagram of the integrated circuit board of the optical pick-up apparatus of the 2nd Embodiment of this invention Optical principle configuration diagram of a general optical pickup device using a diffraction grating (hologram) Schematic configuration diagram of hologram element of general optical pickup device Schematic plan view of a photodetector of a general optical pickup device Schematic sectional view of a two-layer optical information recording medium Image of main beam spot defocused on schematic plan view of photodetector of general optical pickup device Signal of unrecorded / recorded boundary of TE (SPP) of general optical pickup device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor laser element 2 Collimator lens 3 Diffraction grating 4 Polarizing beam splitter 5 Optical information recording medium 6 Rising mirror 7 1/4 wavelength plate 8 Objective lens 9 Photodetector 10 Condensing lens 11 Hologram element 101 Optical information recording medium 102 Semiconductor Laser 103 Diffraction grating 104 1/4 wavelength plate 105 Hologram element 106 First light receiving element group 107 Second light receiving element group 108 Integrated circuit substrate 109 Optical substrate 110 Collimator lens 111 Objective lens 112 Package 119 Two-layer optical information recording medium

Claims (11)

A semiconductor laser element emitting a light beam;
A diffraction grating that diffracts the light beam into a main beam and two sub-beams;
A condensing optical system for condensing the diffracted light diffracted by the diffraction grating onto the recording surface of the optical information recording medium;
A hologram element that diffracts the return light reflected from the optical information recording medium;
A plurality of light receiving elements that receive the diffracted light diffracted by the hologram element;
The hologram element is divided into a first area and a second area by a dividing line substantially parallel to the track direction of the optical information recording medium, and further divided in a direction substantially perpendicular to the track direction. The first region is a first one region and a first two region, and the second region is a second first region located next to the first one region. The diffracted light divided into the second two regions located next to the first two regions and diffracted by the first one region and the second one region of the hologram element is The light is diffracted and incident on the light receiving element so as to be substantially aligned in a direction substantially parallel to the track direction of the optical information recording medium, and the first 2 region and the second 2 of the hologram element are incident. The diffracted light diffracted by the area of the optical information recording medium is transmitted to the plurality of light receiving elements. The light receiving element that is diffracted and incident so as to be aligned substantially in a straight line in a direction substantially parallel to the track direction is divided so that the light receiving element that can contribute to the push-pull signal of the sub beam is parallel to the direction perpendicular to the track direction An optical pickup device divided into six regions by lines.   The semiconductor laser element emits light beams of two different wavelengths, and a sub beam generated from the light beam of one wavelength is incident on four of the light receiving elements divided into six regions in a focused state. The sub-beam generated from the light beam of the other wavelength is incident on four of the light receiving elements divided into six regions in the focused state, and two of the light receiving elements divided into the six regions are The optical pickup device according to claim 1, wherein both sub-beams generated from light beams having two different wavelengths are incident.   The diffraction grating generates a sub beam in a substantially semicircular region, and halves the area of the light receiving element of the sub beam, thereby returning the reflected light other than the focused recording layer of the optical information recording medium. 3. The optical pickup device according to claim 1, wherein stray light offset of a tracking signal caused by the noise is reduced.   The first, first 2, second 1, and second 2 regions of the hologram element have power so that an image is formed at a position close to the optical information recording medium with respect to the light receiving element. The provided areas and the areas to which power is applied so as to form an image at a position far from the optical information recording medium with reference to the light receiving element are alternately formed in a strip shape. The optical pickup device according to any one of claims 1 to 3.   5. The optical pickup device according to claim 1, wherein the light receiving elements are arranged on both sides of a beam emitted from the semiconductor laser. 6.   6. The optical pickup device according to claim 1, wherein the light receiving element is formed on a semiconductor substrate, and the semiconductor laser is mounted on the semiconductor substrate.   An output for generating a focus error signal is output from the light receiving element disposed on one side of the semiconductor laser, and an output for generating a tracking error signal is output from the light receiving element disposed on the other side of the semiconductor laser. The optical pickup device according to claim 1.   8. The optical pickup device according to claim 1, wherein the diffraction grating and the hologram element are formed by a single optical member.   The said diffraction grating, the said hologram element, the said semiconductor laser, and the said semiconductor substrate provided with these several light receiving elements are integrated in one package, The any one of Claim 1 to 8 characterized by the above-mentioned. Optical pickup device.   10. The optical pickup device according to claim 1, wherein a wavelength of a light beam emitted from the semiconductor laser includes a 650 nm band. 10.   11. The optical pickup device according to claim 1, wherein a wavelength of a light beam emitted from the semiconductor laser includes a 405 nm band.

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