JP2004288227A - Optical pickup apparatus and optical disk drive apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately detect various signals by reducing adverse effects of the reflected light beams from a far side recording layer, i.e., flare, made on the signals while focusing is made onto a recording layer near the objective lens. <P>SOLUTION: In the optical pickup apparatus, an optical disk having two recording layers is irradiated with a light flux from a semiconductor laser through the objective lens, the reflected light beams from the disk are guided onto a light receiving element through the objective lens, a hologram 20 and a grating and information on the disk is reproduced. As a light receiving region of the hologram 20, two regions C and D which are used to detect the push-pull signals and one region AB which is used to detect focus error signals, total of three regions are formed and an optical axis is set within the region AB. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical pickup device such as an optical card device and an optical disk drive device.
[0002]
[Prior art]
FIG. 10 is a schematic diagram showing an optical system relating to an optical pickup device of an optical disk drive device, wherein 1 is a semiconductor laser, 2 is a glass plate, and 3 is a three-beam generation formed on a surface of the glass plate 2 on the semiconductor laser 1 side. , A hologram formed on the surface of the glass plate 2 opposite to the surface on which the grating 3 is formed, 5 a holographic pickup, 6 a collimating lens, 7 an objective lens, 8 an optical disk, and 9 a light receiving element. Show.
[0003]
FIG. 11 is a side view showing the internal configuration of the holographic pickup, in which a semiconductor laser 1 and a light receiving element 9 are mounted on a substrate, and a glass plate 2, a grating 3 and a hologram 4 are arranged facing the semiconductor laser 1. It is a unit.
[0004]
Light emitted from a semiconductor laser 1 as a light source is separated into a main beam (0-order light) and two sub-beams (± primary light) by a grating 3 that is a diffraction grating for three beams, and then a hologram 4 Reach Then, only the light (0th-order diffracted light) transmitted through the hologram 4 becomes parallel light by the collimating lens 6 and is condensed on the optical disk 8 after passing through the objective lens 7. The return light reflected by the optical disk 8 passes through the objective lens 7 and the collimator lens 6 again together with the main beam and the sub beam, and is then guided to the hologram 4. Then, only the light (first-order diffracted light) diffracted by the hologram 4 is incident on the light receiving element 9 to generate various signals.
[0005]
The optical disk 8 has two recording layers 8a and 8b at intervals of several tens of μm (about 40 to 70 μm). FIG. 10 shows a case where the recording layer 8a on the side closer to the objective lens 7 is focused. Things. In FIG. 10, reflected light 10 indicated by a solid line is a light beam reflected by the recording layer 8a on the optical disk 8 closer to the objective lens 7, and reflected light 11 indicated by a broken line is reflected on the optical disk 8 farther from the objective lens 7. This is a light beam reflected by the recording layer 8b.
[0006]
FIG. 12 is an explanatory view showing a state of the hologram and the reflected light 10 from the recording layer 8a and the reflected light 11 from the recording layer 8b on the hologram. The hologram 4 is divided into three areas AB, C, and D by two division lines.
[0007]
FIG. 13 is an explanatory diagram showing a state of reflected light 10 from the light receiving element 9 and the recording layer 8a, and reflected light 11 from the recording layer 8b. Since the luminous flux, which is a total of three beams of the main beam and the two sub beams by the grating 3, is divided by the hologram 4 having three regions, the reflected light 10 from the recording layer 8a has nine spots. The reflected light 11 from the recording layer 8b is not condensed on the light receiving element 9 and has nine flares.
[0008]
In FIG. 13, a to h indicate eight light receiving surfaces of the light receiving element 9, and the relationship between the light receiving surfaces to which the light beams diffracted in the three regions AB, C, and D of FIG. 12 reach is as follows. .
The diffracted light of the main beam from AB is between the light receiving surface a and the light receiving surface b.
The diffracted lights of the sub-beams from AB are outside the light receiving surface a and the light receiving surface b (that is, not received),
The diffracted light of the main beam from C is incident on the light receiving surface c.
The diffracted light of the sub-beam from C is respectively applied to the light receiving surface e and the light receiving surface g,
The diffracted light of the main beam from D is incident on the light receiving surface d.
The diffracted light of the sub-beam from D is received on the light receiving surface f and the light receiving surface h, respectively.
[0009]
Here, when the signals output from the light receiving surfaces a to h are expressed by using the same symbols a to h,
The focus error signal (FES)
FES = ab
The track error signal (TES) is
TES = (cd) -α ((e + g)-(f + h))
The track cross signal (TCS)
TCS = (c + d) -α ((e + g) + (f + h))
The lens position signal (LPS) is
LPS = (cd) + α ((e + g) − (f + h))
The information reproduction signal (RFS)
RFS = a + b + c + d
It can be expressed as. This is an application of a so-called push-pull method.
[0010]
[Patent Document 1]
Japanese Patent No. 2594445
[Patent Document 2]
JP-A-11-353698
[0011]
[Problems to be solved by the invention]
By the way, in FIG. 13, not only the reflected light 10 from the recording layer 8a but also the reflected light 11 from the recording layer 8b enters the light receiving surface of the light receiving element 9 unevenly. Therefore, the FES, TES, TCS, LPS, and RFS cannot be detected normally.
[0012]
The present invention reduces the influence on various signals due to reflected light 11 from the recording layer on the far side, that is, flare, particularly when the recording layer on the side close to the objective lens is focused, and properly controls various signals. It is an object of the present invention to provide an optical pickup device and an optical disk drive device capable of detecting.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 irradiates a light beam from a semiconductor laser to an optical disk having two recording layers via an objective lens, and transmits reflected light from the optical disk to the objective lens and the light beam. An optical pickup device for guiding information to an optical disc through a light receiving element through a separating means, wherein two areas for detecting a push-pull signal and a focus error signal are detected as light receiving areas of the light beam separating means. And an optical axis center of the reflected light in the light beam separating means is included in one area for detecting the focus error signal. With this configuration, the reflected light from the recording layer farther from the objective lens of the optical disc when the focus is on the recording layer closer to the objective lens, that is, the flare is a focus error signal (FES) and a track. It is possible to reduce the influence on the error signal (TES), the track cross signal (TCS), the lens position signal (LPS), and the information reproduction signal (RFS).
[0014]
The invention according to claim 2 is characterized in that, in the invention according to claim 1, a dividing line for dividing the three regions is constituted by three straight lines and one curve. With this configuration, it is easy to increase the components of the track error signal (TES) and the track cross signal (TCS), and the track error signal (TES), the track cross signal (TCS), and the lens position signal ( LPS) quality can be improved.
[0015]
According to a third aspect of the present invention, in the first aspect, a dividing line for dividing the three regions is formed of three straight lines, and at least two angles formed by the respective straight lines are larger than 90 °. It is characterized by the following. With this configuration, the components of the track error signal (TES) and the track cross signal (TCS) can be increased, and the track error signal (TES), the track cross signal (TCS), and the lens position signal (TCS) can be increased. LPS) quality can be improved.
[0016]
The invention according to claim 4 is the invention according to claim 1, 2, or 3, wherein when the light beam from the objective lens is focused on a recording layer of the two recording layers that is closer to the objective lens, Reflected light from one of the recording layers that is far from the objective lens is irradiated to one area for detecting the focus error signal. With this configuration, the reflected light from the recording layer farther from the objective lens of the optical disc when the focus is on the recording layer closer to the objective lens, that is, the flare is a focus error signal (FES) and a track. The error signal (TES), the track cross signal (TCS), the lens position signal (LPS), and the information reproduction signal (RFS) can be completely eliminated.
[0017]
The invention according to claim 5 irradiates a light beam from a semiconductor laser to an optical disk having two recording layers via an objective lens, and receives reflected light from the optical disk via the objective lens and a light beam separating means. An optical pickup device for reproducing information on an optical disc, wherein two areas for detecting a push-pull signal and one area for detecting a focus error signal are provided as light receiving areas of the light beam separating means; A total of four regions including one region including the center of the optical axis of the reflected light in the light beam separating means are formed. With this configuration, the reflected light from the recording layer farther from the objective lens of the optical disc when the focus is on the recording layer closer to the objective lens, that is, the flare is a focus error signal (FES) and a track. The error signal (TES), the track cross signal (TCS), the lens position signal (LPS), and the information reproduction signal (RFS) can be completely eliminated.
[0018]
The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the light beam separating means is a hologram element. With this configuration, an inexpensive optical pickup device can be provided.
[0019]
According to a seventh aspect of the present invention, there is provided an optical disk drive device including the optical pickup device according to any one of the first to sixth aspects. With this configuration, it is possible to provide a highly reliable optical disk drive.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0021]
FIG. 1 is an explanatory view showing a configuration of a hologram provided in an optical pickup device according to the first embodiment of the present invention, and 20 indicates a hologram which is a light beam separating means.
[0022]
The device according to the first embodiment is obtained by forming a hologram 20 shown in FIG. 1 on a glass plate 2 instead of the hologram 4 in the optical pickup device shown in FIG.
[0023]
The hologram 20 has a total of three areas of two areas (C and D) for detecting a push-pull signal and one area (AB) for detecting a focus error signal. The dividing line for dividing is constituted by three straight lines and one curve. That is, it is divided into two regions by a substantially semicircular curve and two straight lines starting from both ends of the curve with respect to the center of the reflected light 10 from the recording layer 8a. Is defined as an area AB. Further, the remaining area is divided into two areas by one straight line, which are referred to as an area C and an area D.
[0024]
Here, the radius of the curve is set to be equal to or larger than the radius of the spot when the reflected light 11 from the recording layer 8b enters the hologram 20. As a result, the spot diameter when the reflected light from the side closer to the objective lens 7, that is, the reflected light 10 from the recording layer 8a enters the hologram 20, is such that the reflected light 11 from the recording layer 8b enters the hologram 20. The reflected light 10 from the recording layer 8a is applied to the areas AB, C and D, and the reflected light 11 from the recording layer 8b is applied to the area AB. Become.
[0025]
FIG. 2 is an explanatory diagram showing the state of reflected light from a recording layer closer to the objective lens and reflected from a recording layer farther from the objective lens, which is diffracted by the light receiving element and the hologram. Since the reflected light 11 from the recording layer 8b is applied to the area AB in the hologram 20, the flare of the reflected light 11 from the recording layer 8b uniformly enters only the light receiving surfaces a and b.
Focus error signal
FES = ab
Track error signal
TES = (cd) -α ((e + g)-(f + h))
Track cross signal
TCS = (c + d) -α ((e + g) + (f + h))
Lens position signal
LPS = (cd) + α ((e + g) − (f + h))
Information reproduction signal
RFS = a + b + c + d
Can be detected normally.
[0026]
FIG. 3 is an explanatory view showing a configuration of a hologram provided in the optical pickup device according to the second embodiment of the present invention, and 21 indicates a hologram which is a light beam separating means.
[0027]
The device according to the second embodiment is such that a hologram 21 shown in FIG. 3 is formed on a glass plate 2 instead of the hologram 4 in the optical pickup device shown in FIG. 10, and the hologram 21 is a hologram 20 shown in FIG. The position of the straight line portion in the dividing line between the region AB and the regions C and D in the direction indicated by the arrow in FIG. 3, ie, the division of the region C and the region D with respect to the center of the reflected light 10 from the recording layer 8a. This is set on the opposite side of the line to increase the area for detecting the push-pull signal.
[0028]
With this configuration, as in the first embodiment, the influence of the flare of the reflected light 11 from the recording layer 8b can be reduced, and
Track error signal
TES = (cd) -α ((e + g)-(f + h))
Track cross signal
TCS = (c + d) -α ((e + g) + (f + h))
Lens position signal
LPS = (cd) + α ((e + g) − (f + h))
The quality is improved.
[0029]
FIG. 4 is an explanatory diagram showing the configuration of a hologram provided in the optical pickup device according to the third embodiment of the present invention, and 22 indicates a hologram which is a light beam separating means.
[0030]
The device according to the third embodiment is obtained by forming a hologram 22 shown in FIG. 4 on the glass plate 2 instead of the hologram 4 in the optical pickup device shown in FIG. The position of the straight line portion in the dividing line between the region AB and the regions C and D is set on the rotation direction side indicated by the arrow in FIG. The area for detecting the push-pull signal is increased.
[0031]
With this configuration, as in the first embodiment, the influence of the flare of the reflected light 11 from the recording layer 8b can be reduced, and
Track error signal
TES = (cd) -α ((e + g)-(f + h))
Track cross signal
TCS = (c + d) -α ((e + g) + (f + h))
Lens position signal
LPS = (cd) + α ((e + g) − (f + h))
The quality is improved.
[0032]
FIG. 5 is an explanatory view showing the configuration of a hologram provided in the optical pickup device according to the fourth embodiment of the present invention, and 23 indicates a hologram which is a light beam separating means.
[0033]
The device according to the fourth embodiment is such that a hologram 23 shown in FIG. 5 is formed on a glass plate 2 instead of the hologram 4 in the optical pickup device shown in FIG.
[0034]
The hologram 23 forms a dividing line for dividing the three regions by three straight lines, and at least two angles θ1 and θ2 formed by the respective straight lines are larger than 90 °.
[0035]
The position of the intersection of the three straight lines is out of the area of the light spot due to the reflected light 11, and the angles θ1 and θ2 between the dividing line between the area C and the area D and the other two are the other two. Is desirably set such that the straight line becomes a circular tangent to the light spot.
[0036]
With such a configuration, all the light spots due to the reflected light 11 are included in the area AB, and the influence of flare can be reduced. Also,
Track error signal
TES = (cd) -α ((e + g)-(f + h))
Track cross signal
TCS = (c + d) -α ((e + g) + (f + h))
Lens position signal
LPS = (cd) + α ((e + g) − (f + h))
The quality is improved.
[0037]
FIG. 6 is an explanatory diagram showing a configuration of a hologram provided in an optical pickup device according to a fifth embodiment of the present invention, and 24 indicates a hologram which is a light beam separating means.
[0038]
The device according to the first embodiment is obtained by forming a hologram 24 shown in FIG. 6 on the glass plate 2 instead of the hologram 4 in the optical pickup device shown in FIG.
[0039]
The hologram 24 has a total of two areas (C and D) for detecting the push-pull signal, one area (AB) for detecting the focus error signal, and one area (I) including the optical axis center. It has four regions, and is divided into each region by four dividing lines. In other words, the region I is separated from the other region by a circular dividing line centered on the optical axis and larger than the diameter of the light spot of the reflected light 11, and the other region is divided by three straight dividing lines. AB, area C, and area D.
[0040]
FIG. 7 is an explanatory diagram showing a state of reflected light diffracted by the hologram shown in FIG. Since the luminous flux, which is a total of three beams of the main beam and two sub-beams by the grating 3, is divided by the hologram 24 having four regions, the reflected light 10 from the recording layer 8a has 12 spots. . The reflected light 11 from the recording layer 8b is not condensed on the light receiving element 9 and has three flares.
[0041]
The light receiving element 9 has nine light receiving surfaces a to i. A light beam diffracted in four regions AB, C, D, and I shown in FIG. The relationship is as follows.
The diffracted light of the main beam from AB is between the light receiving surface a and the light receiving surface b.
The diffracted light of the main beam from C is incident on the light receiving surface c.
The diffracted light of the sub-beam from C is respectively applied to the light receiving surface e and the light receiving surface g,
The diffracted light of the main beam from D is incident on the light receiving surface d.
The diffracted light of the sub-beam from D is respectively applied to the light receiving surface f and the light receiving surface h,
The diffracted light of the main beam from I is incident on the light receiving surface i,
Received. Also,
The diffracted light of the sub-beam from AB is outside the light receiving surface a and the light receiving surface b, respectively.
The diffracted lights of the sub-beams from I are outside the light receiving surface i, respectively.
Irradiated. That is, the light is not received by the light receiving element 9.
[0042]
Here, when the signals output from the light receiving surfaces a to i are expressed by using the same symbols a to i,
The focus error signal (FES)
FES = ab
The track error signal (TES) is
TES = (cd) -α ((e + g)-(f + h))
The track cross signal (TCS)
TCS = (c + d) -α ((e + g) + (f + h))
Lens position signal
LPS = (cd) + α ((e + g) − (f + h))
The information reproduction signal (RFS)
RFS = a + b + c + d + i
It becomes.
[0043]
As described above, since the flare of the reflected light 11 from the recording layer 8b is incident only on the light receiving surface i, the above signals can be normally detected.
[0044]
The embodiment of the present invention has been described above, but the embodiment according to the present invention is not limited to the above. For example, in the above-described embodiment, a hologram element is described as a light beam separating unit. However, an optical element such as a prism or a lens using refraction may be applied instead of the hologram element.
[0045]
Incidentally, in recent years, DVDs (Digital Versatile Discs) have become widespread as optical discs for storing a large amount of information. DVD-RAM / WO, DVD-R, DVD + R and DVD-RAM, DVD-RW, DVD + RW discs are writable (recordable) DVDs. The former DVD-RAM / WO, DVD-R, and DVD + R are DVDs that can be written only once (also referred to as DVD Write Once). The latter DVD-RAM, DVD-RW, and DVD + RW are DVDs that can be written multiple times. Information is recorded and reproduced on these DVD + R and DVD + RW discs, that is, optical discs by an optical disc drive device as shown in FIG.
[0046]
FIG. 8 is a functional block diagram showing an example of a main configuration of the optical disk drive. In the figure, 51 is an optical disk, 52 is a spindle motor, 53 is an optical pickup device, 54 is a motor driver, 55 is a read amplifier, 56 is servo means, 57 is a DVD decoder, 58 is an ADIP decoder, 59 is a laser controller, and 60 is a laser controller. DVD encoder, 61 is DVD-ROM encoder, 62 is buffer RAM, 63 is buffer manager, 64 is DVD-ROM decoder, 65 is ATAPI / SCSI interface, 66 is D / A converter, 67 is ROM, 68 is CPU, 69 Indicates a RAM, LB indicates a laser beam, and Audio indicates an audio output signal.
[0047]
In FIG. 8, arrows indicate the directions in which data mainly flows, and for simplification of the drawing, the CPU 68 that controls each block in FIG. Omitted. In the ROM 67, a control program described in a code decodable by the CPU 68 is stored. When the power of the optical disk drive is turned on, the control program is loaded into a main memory (not shown), and the CPU 68 controls the operations of the above-described units according to the program and temporarily stores data and the like necessary for the control. It is stored in the RAM 69.
[0048]
The configuration and operation of the optical disk drive are as follows.
[0049]
The optical disk 51 is driven to rotate by a spindle motor 52. The spindle motor 52 is controlled by a motor driver 54 and servo means 56 so that the linear velocity or the angular velocity becomes constant. This linear velocity or angular velocity can be changed stepwise.
[0050]
The optical pickup device 53 incorporates the configuration shown in FIGS. 1 to 7, the focus actuator, the track actuator, the light receiving element 9 (see FIG. 10) and the position sensor, and irradiates the optical disk 51 with laser light LB. The optical pickup device 53 can be moved in the sledge direction by a seek motor. In these focus actuator, track actuator, and seek motor, the spot of the laser beam LB is located at a target position on the optical disk 51 by the motor driver 54 and the servo unit 56 based on signals obtained from the light receiving element and the position sensor. Is controlled as follows.
[0051]
Then, at the time of reading, the reproduction signal obtained by the optical pickup device 53 is amplified by the read amplifier 55 and binarized, and then input to the DVD decoder 57. The input binary data is subjected to 8/16 demodulation in the DVD decoder 57. It should be noted that the recording data is modulated in a group of 8 bits (8/16 modulation). In this modulation, 8 bits are converted to 16 bits. In this case, the combined bits are attached so that the number of “1” and “0” up to that time are equal on average. This is called “DC component suppression”, and the slice level fluctuation of the DC-cut reproduction signal is suppressed.
[0052]
The demodulated data is subjected to deinterleaving and error correction. After that, this data is input to the DVD-ROM decoder 64, and further error correction processing is performed to improve the reliability of the data. The data on which the error correction processing has been performed twice is temporarily stored in the buffer RAM 62 by the buffer manager 63, and is sent to the host computer (not shown) via the ATAPI / SCSI interface 65 in a state of being prepared as sector data. It is transferred at a stretch. In the case of music data, the data output from the DVD decoder 57 is input to the D / A converter 66 and extracted as an analog audio output signal Audio.
[0053]
At the time of writing, data transmitted from the host computer through the ATAPI / SCSI interface 65 is temporarily stored in the buffer RAM 62 by the buffer manager 63. Thereafter, the write operation is started. In this case, however, it is necessary to position the laser spot at the write start point before that. In the case of DVD + RW / + R, this point is determined by a wobble signal which is previously carved on the optical disk 51 by meandering of the track.
[0054]
Note that the above-mentioned point is obtained by land pre-pits instead of wobble signals in DVD-RW / -R, and by pre-pits in DVD-RAM / RAM / WO.
[0055]
The wobble signal on the DVD + RW / + R disc contains address information called ADIP (ADless In Pre-groove), and this information is extracted by the ADIP decoder 58. Further, the synchronization signal generated by the ADIP decoder 58 is input to the DVD encoder 60, and enables writing of data to an accurate position on the optical disk 51. The data in the buffer RAM 62 is added with an error correction code and interleaved by the DVD-ROM encoder 61 and the DVD encoder 60, and is recorded on the optical disk 51 via the laser controller 59 and the optical pickup 53.
[0056]
Further, a configuration may be employed in which address information is obtained from land pre-pits or pre-pits.
[0057]
FIG. 9 is a schematic diagram of an information processing apparatus using an optical disk drive. The information processing device includes a main control device 70, an interface 71, a recording device 72, an input device 73, a display device 74, an optical disk drive device 75 having the configuration shown in FIG. Main controller 70 includes a CPU, a microcomputer, a main memory, and the like, and controls the entire information processing apparatus.
[0058]
The interface 71 is a two-way communication interface with the optical disk drive device 75, and conforms to a standard interface such as ATAPI and SCSI. The interface 71 is connected to the interface 65 of the optical disk drive shown in FIG. The connection between the interfaces may be not only a cable connection using a communication line such as a communication cable (for example, a SCSI cable), but also a wireless connection using infrared rays or the like.
[0059]
A recording device 72 such as a hard disk drive (HDD) stores a program described in a code that can be read by a microcomputer of the main control device 70. When the drive power supply of the information processing device is turned on, the program is loaded into the main memory of the main controller 70.
[0060]
The display device 74 includes a display unit (not shown) such as a CRT, a liquid crystal display (LCD), or a plasma display panel (PDP), and displays various information from the main control device 70.
[0061]
The input device 73 includes at least one input medium (not shown) of, for example, a keyboard, a mouse, and a pointing device, and notifies the main control device 70 of various information input by a user. The information from the input medium may be input by a wireless method. Further, as a unit in which the display device 70 and the input device 73 are integrated, there is, for example, a CRT with a touch panel.
[0062]
The information processing apparatus has an operating system (OS). It is assumed that all devices constituting the information processing apparatus are managed by the OS.
[0063]
【The invention's effect】
According to the present invention configured as described above, the reflected light from the recording layer far from the objective lens of the optical disc when focusing on the recording layer near the objective lens, that is, the flare is focused. It is possible to reduce the influence on the error signal (FES), the track error signal (TES), the track cross signal (TCS), the lens position signal (LPS), and the information reproduction signal (RFS).
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a hologram provided in an optical pickup device according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing the state of reflected light from a recording layer closer to an objective lens and reflected light from a recording layer farther from the objective lens, diffracted by a light receiving element and a hologram;
FIG. 3 is an explanatory diagram showing a configuration of a hologram provided in an optical pickup device according to a second embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a configuration of a hologram provided in an optical pickup device according to a third embodiment of the present invention.
FIG. 5 is an explanatory diagram showing a configuration of a hologram provided in an optical pickup device according to a fourth embodiment of the present invention.
FIG. 6 is an explanatory diagram showing a configuration of a hologram provided in an optical pickup device according to a fifth embodiment of the present invention.
FIG. 7 is an explanatory view showing a state of reflected light diffracted by the hologram shown in FIG. 6;
FIG. 8 is a functional block diagram showing an example of a main configuration of an optical disk drive device.
9 is a schematic diagram of an information processing apparatus using the optical disk drive device shown in FIG.
FIG. 10 is a schematic diagram showing an optical system related to an optical pickup device of the optical disk drive device.
FIG. 11 is a side view showing the internal configuration of a holographic pickup.
FIG. 12 is an explanatory diagram showing a state of reflected light from a recording layer on the side closer to the hologram and the objective lens subjected to hologram diffraction, and reflected light from a recording layer on the side farther from the objective lens;
FIG. 13 is an explanatory diagram showing a state of reflected light diffracted by the hologram shown in FIG.
[Explanation of symbols]
1 Semiconductor laser
2 Glass plate
3 grating
20,21,22,23,24 Hologram
5 Holo pickup
6 Collimating lens
7 Objective lens
8 Optical disk
8a, 8b recording layer
9 Light receiving element
10,11 reflected light

Claims (7)

A light beam from a semiconductor laser is irradiated onto an optical disk having two recording layers via an objective lens, and reflected light from the optical disk is guided to a light receiving element via the objective lens and light beam separating means, thereby reproducing information on the optical disk. Optical pickup device,
The light beam separating means includes two areas for detecting a push-pull signal and one area for detecting a focus error signal as light receiving areas, and focuses an optical axis of reflected light in the light beam separating means on the focus. An optical pickup device, wherein the optical pickup device is included in one area for detecting an error signal. 2. The optical pickup device according to claim 1, wherein a dividing line for dividing the three regions is constituted by three straight lines and one curved line. 2. The optical pickup device according to claim 1, wherein a dividing line for dividing the three regions is constituted by three straight lines, and at least two of the angles formed by the straight lines are larger than 90 [deg.]. When a light beam from the objective lens is focused on a recording layer of the two recording layers that is closer to the objective lens, reflected light from a recording layer of the two recording layers that is farther from the objective lens generates the focus error. 4. The optical pickup device according to claim 1, wherein the light is irradiated to one area for detecting a signal. A light beam from a semiconductor laser is irradiated onto an optical disk having two recording layers via an objective lens, and reflected light from the optical disk is guided to a light receiving element via the objective lens and light beam separating means, thereby reproducing information on the optical disk. Optical pickup device,
As a light receiving area of the light beam separating means, two areas for detecting a push-pull signal, one area for detecting a focus error signal, and one area including an optical axis center of reflected light in the light beam separating means. An optical pickup device, wherein a total of four regions are formed. The optical pickup device according to any one of claims 1 to 5, wherein the light beam separating means is a hologram element. An optical disk drive device comprising the optical pickup device according to any one of claims 1 to 6.

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