WO2006121153A1

WO2006121153A1 - Optical pickup and information device

Info

Publication number: WO2006121153A1
Application number: PCT/JP2006/309553
Authority: WO
Inventors: Naoharu Yanagawa; Masataka Izawa; Takehisa Okuyama
Original assignee: Pioneer Corporation
Priority date: 2005-05-12
Filing date: 2006-05-12
Publication date: 2006-11-16

Abstract

An optical pickup (100) performs recording and reproduction to and from a plurality of recording mediums (10). The optical pickup is provided with a first spherical aberration correcting means (103) for correcting a spherical aberration corresponding to a substrate thickness of the recording medium, and a second spherical aberration correcting means (107) for correcting the remaining spherical aberration after the correction by the first spherical aberration correcting means, at an accuracy equivalent to that of the spherical aberration correction by the first spherical aberration correcting means or higher.

Description

Optical pickup and information equipment

Technical field

[0001] The present invention relates to a technical field of an optical pickup that emits light when recording or reproducing data on an information recording medium such as a DVD, and an information device including the optical pickup.

Background art

[0002] For example, an information recording medium for optically recording and reproducing data using a laser beam or the like, such as a CD or a DVD, has been developed. Such information recording media have various substrate thicknesses, such as 1.2 mm for CDs, 0.6 mm for DVDs and HD DVDs, for example Blu-ray. If it is a Disc, it has a substrate thickness of 0.1 mm. In order to record or reproduce data on such information recording media having different substrate thicknesses, it is necessary to focus laser light on the recording surface in accordance with the thickness of each substrate. As one technique for this purpose, for example, a technique for condensing laser light on a recording surface according to the substrate thickness using an optical pickup provided with a plurality of objective lenses according to the substrate thickness has been developed. As another method, a method has been developed in which the position of the collimator lens (condensing lens) in the optical path of the laser beam is changed to focus the laser beam on the recording surface according to the substrate thickness. That is, a method of condensing laser light on the recording surface according to the substrate thickness by changing the magnification of the optical system has been developed. (See Non-Patent Document 1).

On the other hand, when data is recorded on or reproduced from such information recording media having different substrate thicknesses with a single objective lens, inherent spherical aberration occurs for each information recording medium. . After dividing the laser beam to correct this spherical aberration into a plurality of beam bundles, a technique for making the spherical aberration of each beam bundle substantially zero (see Patent Document 1), parallel plate laser beams having different thickness portions A technique for changing the position of the light on the optical path (see Patent Document 2) and a technique using a liquid crystal panel (see Patent Document 3) have been developed.

Patent Document 1: Japanese Patent Laid-Open No. 8-249708

Patent Document 2: Japanese Patent Laid-Open No. 5-241095 Patent Document 3: Japanese Patent Laid-Open No. 9-128785

Non-Patent Document 1: “Next generation optical discs to be unified” Nikkei Electronics September 27, 2004 P112- 113

Non-Patent Document 2: Isao ICHIMURA, Fumisada MAEDA, Kiyoshi 0SAT0, Kenji YAMAM0T0, Yutaka KASAMI “Optical recording using blue laser diode (Optical Recording Using a (^ aN Blue- Violet Laser Diode) '' Jpn.J.Appl.Phys 2000 Vol. 39 P937- 942

Disclosure of the invention

Problems to be solved by the invention

[0005] However, the techniques described in Patent Document 1 and Patent Document 2 can only roughly correct spherical aberration, and realize a higher quality recording operation or reproducing operation. From a point of view, it can be said that the technology is never satisfactory. In addition, in the technique described in Patent Document 3, spherical aberration that can be distributed over a wide range is generally used for current information recording media in which the substrate thickness is distributed over a range of 1.2 mm to 0.1 mm. However, there is a technical problem that cannot be corrected.

The present invention has been made in view of, for example, the above-described conventional problems, and for example, an optical pickup capable of suitably correcting spherical aberration, and an information device including such an optical pickup. It is an issue to provide.

Means for solving the problem

[0007] (Optical pickup)

In order to solve the above problems, an optical pickup according to the present invention is an optical pickup for performing at least one of data recording and reproduction on each of a plurality of types of information recording media, and at least one of recording and reproduction of the data. First spherical aberration correction that corrects the spherical aberration when the light beam irradiated to perform the focusing on the information recording medium is corrected according to the substrate thickness of the information recording medium determined by the determining means And a second sphere that corrects the spherical aberration remaining after the correction by the first spherical aberration correcting means to the same degree as or higher than the accuracy of the correction of the spherical aberration by the first spherical aberration correcting means. Surface aberration correction means.

[0008] According to the optical pickup of the present invention, while the spherical aberration is corrected by the respective operations of the first spherical aberration correcting means and the second spherical aberration correcting means, the irradiation means power of the hologram laser element etc. The medium is irradiated. Thereby, data can be recorded on the information recording medium, or data recorded on the information recording medium can be reproduced.

Specifically, the spherical aberration is first corrected by the first spherical aberration correcting means. At this time, the first spherical aberration correcting means is an information recording medium (that is, a light beam irradiated by the optical pickup, which is discriminated by the operation of the discriminating means provided inside or outside the optical pickup, that is, The spherical aberration is corrected according to the thickness of the substrate of the information recording medium that is the target of data recording or reproduction. Here, compared to the second spherical aberration correction method, rough (that is, rough) spherical aberration correction is performed by using, for example, a previously prepared spherical aberration correction amount table corresponding to the disc type. Is done using. After the spherical aberration is corrected by the first spherical aberration correcting means, the spherical aberration is further corrected by the second spherical aberration correcting means. That is, the spherical aberration that cannot be removed by the correction of the spherical aberration by the first spherical aberration correcting means is corrected. This second spherical aberration correction means corrects spherical aberration at a level equivalent to the correction of spherical aberration by the first spherical aberration correction means or at a higher precision (or finer) level.

In summary, the first spherical aberration correction means corrects a relatively rough (in other words, a large level) spherical aberration, and the second spherical aberration correction means corrects the first spherical aberration correction. Spherical aberration that cannot be removed by correction by means is corrected. In particular, because the relatively spherical aberration is corrected by the first spherical aberration correction means, the second spherical aberration correction means is the first spherical surface that does not consider a relatively large level of spherical aberration. It is possible to correct spherical aberration that cannot be removed by correction by the convergence correction means. In addition, since the second spherical aberration correction means corrects spherical aberration that cannot be removed by the correction by the first spherical aberration correction means, the first spherical aberration correction means corrects the relatively rough spherical aberration. It can be performed. That is, each of the first spherical aberration correcting unit and the second spherical aberration correcting unit has a relationship of complementing each other. In this way, spherical aberration can be corrected in two stages, so that spherical aberration can be corrected more suitably. As a result, the spherical aberration can be made zero or almost zero. Since the spherical aberration is corrected according to the substrate thickness of the information recording medium, the first spherical aberration correcting means and the second spherical aberration correcting means can be applied to the information recording medium having any substrate thickness. The spherical aberration is corrected more suitably for each. Accordingly, it is possible to record or reproduce data on a plurality of types of information recording media having different substrate thicknesses while eliminating the adverse effects of spherical aberration.

[0011] One aspect of the optical pickup of the present invention is characterized in that the first spherical aberration correction unit is discriminated by a light beam splitting unit that splits the optical beam into a plurality of light bundles and the discrimination unit. Adjusting means for adjusting each of the plurality of light bundles so as to bring the spherical convergence of each of the plurality of light bundles close to substantially zero according to the substrate thickness of the information recording medium.

[0012] According to this aspect, the light beam irradiated from the irradiation unit is divided into a plurality of light beam bundles (for example, a P-polarized light beam and an S-polarized light beam) by the dividing unit. Thereafter, the adjusting means adjusts each light bundle so that the spherical aberration of each of the plurality of light bundles approaches substantially zero according to the substrate thickness of the information recording medium. Specifically, according to the substrate thickness of the information recording medium, one light bundle that actually records or reproduces data on the information recording medium having the substrate thickness determined by the determining means among a plurality of light bundles. For example, the optical path or the like is adjusted so that the spherical aberration approaches approximately zero. As a result, it is possible to suitably correct a relatively rough spherical aberration according to the thickness of the information recording medium.

In another aspect of the optical pickup of the present invention, the first spherical aberration correction unit has a predetermined property for the light beam in accordance with a substrate thickness of the information recording medium determined by the determination unit. Conversion means for converting into a light beam; and optical path adjusting means for transmitting the light beam having one property and reflecting the light beam having another property different from the one property.

[0014] According to this aspect, the light beam emitted from the irradiation unit has a predetermined property according to the substrate thickness of the information recording medium determined by the conversion unit (for example, having P-polarized light or Converted into a light beam (having a predetermined polarization mode such as S-polarized light). After that, if the optical path adjusting means and the light beam have one property (for example, P-polarized light), If it is transmitted and the other light beam has other properties (for example, s-polarized light), it can be reflected to change the optical path of the light beam. Thereby, the optical path length of the optical beam (more specifically, the optical distance between a hologram laser and a collimator lens described later) can be changed according to the substrate thickness. For this reason, it is possible to suitably correct the relatively rough spherical aberration according to the substrate thickness of the information recording medium.

[0015] In this case, the conversion means preferably converts the light beam electrically. As a result, the light beam is converted by using a mechanical mechanism that can occupy a relatively large space or have a relatively complicated configuration as disclosed in Patent Document 1 and Patent Document 2 described above. There is no need. Thereby, the configuration of the optical pickup can be made relatively simple, and the size of the optical pickup can be made relatively small.

In another aspect of the optical pickup of the present invention, the first spherical aberration correction unit changes the optical path length of the light beam according to the substrate thickness of the information recording medium determined by the determination unit. Thus, the spherical aberration is corrected.

According to this aspect, the optical path length of the light beam (more specifically, the optical distance between a hologram laser and a collimator lens described later) can be changed according to the substrate thickness. Therefore, it is possible to suitably correct relatively rough spherical aberration according to the substrate thickness of the information recording medium.

[0018] In another aspect of the optical pickup of the present invention, a plurality of irradiation means for irradiating a plurality of light beams corresponding to each of the plurality of types of information recording media, each having a different distance from the information recording medium. The first spherical aberration correction unit irradiates the light beam to the information recording medium among the plurality of irradiation units according to the substrate thickness of the information recording medium determined by the determination unit. The spherical aberration is corrected by selecting the irradiation means.

[0019] According to this aspect, the irradiation means for irradiating the light beam can be selectively switched according to the substrate thickness of the information recording medium. Thereby, the optical path length of the light beam (more specifically, the optical distance between a hologram laser and a collimator lens described later) can be changed according to the substrate thickness. Therefore, it is possible to suitably correct relatively rough spherical aberration according to the substrate thickness of the information recording medium. [0020] In the aspect of the optical pickup provided with a plurality of irradiation means as described above, the optical axes of the light beams emitted from the plurality of irradiation means may be different from each other.

[0021] With this configuration, it is possible to suppress or eliminate mutual interference of light beams emitted from a plurality of irradiation means.

[0022] In the aspect of the optical pickup including a plurality of irradiation means as described above, the optical beam irradiated from other irradiation means excluding at least one irradiation means among the plurality of irradiation means is the information recording medium. Further, a coma aberration correcting unit that corrects coma aberration when the light is focused on may be further provided.

[0023] With this configuration, in addition to the above-described spherical aberration, coma can also be suitably corrected. In particular, when the optical axes of the light beams irradiated by the plurality of irradiation means are different from each other as described above, the light beams may be irradiated using the off-axis of the collimator lens. In such a case, coma generated by irradiating the light beam using the off-axis of the collimator lens can be suitably corrected. Therefore, even when the optical axes of the light beams emitted from each of the plurality of irradiation means are different, data recording or data reproduction can be suitably performed.

[0024] In the aspect of the optical pickup including the coma aberration correcting unit as described above, at least two of the plurality of irradiating units generate the same amount of coma aberration in opposite directions with respect to the collimator lens. (Or arranged at positions shifted by the same amount in the opposite directions with respect to the central axis of the collimator lens)!

[0025] With this configuration, it is possible to relatively reduce the correction amount of the frame difference with respect to the light beams emitted from the two irradiation units. Thereby, the configuration of the coma aberration correcting unit can be made relatively simple.

In another aspect of the optical pickup of the present invention, the first spherical aberration correction unit includes a collimator lens that is movable along the optical axis of the optical beam.

[0027] According to this aspect, the optical distance between a hologram laser (to be described later) and a collimator lens can be changed according to the substrate thickness. For this reason, according to the substrate thickness of the information recording medium

Therefore, it is possible to suitably correct relatively rough spherical aberration. In another aspect of the optical pickup of the present invention, the second spherical aberration correcting unit calculates the amount of the spherical aberration based on the reflected light of the light beam from the information recording medium. The spherical aberration is corrected based on the calculated amount of spherical aberration.

[0029] According to this aspect, the second spherical aberration correction unit can correct the spherical aberration while monitoring the actual amount of spherical aberration calculated by the calculation unit. Specifically, for example, the spherical aberration can be corrected so that the actual amount of spherical aberration calculated by the calculating means becomes substantially zero. Thereby, it is possible to suitably correct spherical aberration that cannot be removed by correction by the first spherical aberration correcting means. Since the spherical aberration can be corrected based on the actual amount of spherical aberration, the spherical aberration can be corrected relatively easily.

[0030] In the aspect of the optical pickup that corrects the spherical aberration based on the amount of the spherical aberration calculated as described above, a dividing unit that divides the reflected light and a plurality of light receiving units that receive the divided reflected light. And may further comprise means.

[0031] With this configuration, it is recognized that the amount of spherical aberration is substantially zero when the level of reflected light received by each of the plurality of light receiving means is the same. be able to. Therefore, by monitoring the level of reflected light received by each of the plurality of light receiving means, it is possible to suitably correct spherical aberration that cannot be removed by the correction by the first spherical aberration correcting means.

In another aspect of the optical pickup of the present invention, the second spherical aberration correction means includes a liquid crystal element.

[0033] According to this aspect, it is possible to suitably and relatively easily correct spherical aberration at a fine level using a liquid crystal element.

In another aspect of the optical pickup of the present invention, the second spherical aberration correction unit is a signal obtained by detecting reflected light of the optical beam, and the recording medium of the optical beam is The spherical aberration is corrected so that the signal level of the signal that changes depending on the spot position on the body (for example, RF signal, LPP signal, wobble signal, CAPA signal, TE signal, pre-pit signal, emboss signal, etc.) is substantially maximized. To do. [0035] According to this aspect, the second spherical aberration correction unit preferably performs correction of spherical aberration that cannot be removed by correction by the first spherical aberration correction unit by monitoring the signal levels of these signals. be able to.

[0036] Another aspect of the optical pickup of the present invention includes: a condensing unit that condenses the light beam on the recording medium; and a moving unit that moves the condensing unit along the optical axis of the light beam. The discriminating unit discriminates the substrate thickness based on the waveform of the reflected light of the light beam detected while moving the light collecting unit.

[0037] According to this aspect, for example, when the light beam is irradiated while moving a focusing means such as an objective lens, the focus of the light beam is adjusted to the surface or recording surface of the information recording medium. For example, an S-shaped curve can be obtained as the reflected light waveform. Therefore, the length (that is, the substrate thickness) between the surface of the information recording medium and the recording surface of the information recording medium can be recognized based on the two S-shaped force curves. Therefore, the substrate thickness of the information recording medium can be suitably determined based on the waveform of the reflected light of the light beam detected while moving the condensing means.

[0038] In the aspect of the optical pickup including the condensing means and the moving means as described above, a plurality of types of light beams for performing at least one of recording and reproduction of the data on each of the plurality of types of information recording media are irradiated. And irradiating means for selectively irradiating a predetermined one type of light beams among the plurality of types of light beams at the time of determination by the determining means. The substrate thickness may be determined based on the waveform of the reflected light of one type of light beam.

[0039] With this configuration, it is not necessary to irradiate the information recording medium with all of a plurality of types of light beams, so that the substrate thickness can be determined efficiently.

[0040] In the aspect of the optical pickup that selectively irradiates one type of light beam as described above, the one type of light beam has the maximum data recording capacity among the plurality of types of information recording media. It may be configured to be a light beam corresponding to various information recording media.

[0041] With this configuration, the substrate thickness can be suitably determined regardless of which type of information recording medium is selectively irradiated with one type of light beam.

[0042] In the aspect of the optical pickup including the light collecting means and the moving means as described above, the light collecting is performed. Measuring means for measuring a moving amount of the moving means by the moving means, and the discriminating means is configured to detect a waveform of the reflected light when the light beam is focused on the surface of the information recording medium. And determining the thickness of the substrate based on the amount of movement of the condensing means until the waveform of the reflected light is detected when the light beam is condensed on the recording surface of the information recording medium. It may be configured as ヽ.

[0043] With this configuration, the moving amount of the light collecting means is measured by the measuring means. At this time, the amount of movement of the condensing means from when the light beam is focused on the surface of the information recording medium to when the light beam is focused on the recording surface of the information recording medium is as follows: The length (ie, substrate thickness) between the surface of the recording medium and the recording surface of the information recording medium is directly or indirectly shown. In other words, the amount of movement of the condensing means from when the first S-shaped curve as the reflected light waveform is obtained until the second S-shaped curve as the reflected light waveform is obtained is This corresponds to the length (ie, substrate thickness) between the surface of the information recording medium and the recording surface of the information recording medium. Therefore, the substrate thickness of the information recording medium can be suitably determined based on the reflected light waveform of the light beam detected while moving the condensing means.

In another aspect of the optical pickup of the present invention, there is provided irradiation means for irradiating a plurality of types of light beams for performing at least one of recording and reproduction of the data with respect to each of the plurality of types of information recording media. Further, the discriminating unit discriminates the substrate thickness by controlling the irradiating unit to sequentially irradiate the information recording medium with each of the plurality of types of light beams.

[0045] According to this aspect, there is provided a light beam that sequentially irradiates a plurality of types of optical beams corresponding to each of a plurality of types of information recording media, and can actually read data on the information recording medium. Determined. Then, the type of the information recording medium is determined from the determined light beam, and as a result, the substrate thickness of the information recording medium is determined.

[0046] In another aspect of the optical pickup of the present invention, the second spherical aberration correction unit is irradiated with a plurality of data irradiated to perform at least one of recording and reproduction of the data with respect to each of the plurality of types of information recording media. Among the types of light beams, the spherical aberration is corrected after the light beam corresponding to the substrate thickness determined by the determining means is irradiated.

[0047] According to this aspect, the optical beam for actually recording or reproducing data is used. As an elephant, correction of spherical aberration that could not be removed by correction by the first spherical aberration correction means is performed by the second spherical aberration correction means. Therefore, the second spherical aberration correcting unit can suitably correct the spherical aberration.

[0048] (Information equipment)

In order to solve the above problems, the information device of the present invention is an information device that performs at least one of data recording and reproduction on each of a plurality of types of information recording media, and determines the substrate thickness of the information recording medium. The information recording method wherein the discriminating means discriminates the spherical aberration when the light beam irradiated to perform at least one of recording and reproduction of the data is focused on the information recording medium. A first spherical aberration correcting unit that corrects according to the substrate thickness of the medium; and the spherical aberration remaining after the correction by the first spherical aberration correcting unit is used to correct the spherical aberration by the first spherical aberration correcting unit. Irradiating the information recording medium with at least one of the data recording and reproduction, the second spherical aberration correcting means for correcting the same or higher accuracy than the second spherical aberration correcting means. And a reproducing means for lines.

[0049] According to the information device of the present invention, data is recorded on an information recording medium such as an optical disc or information recording while enjoying the same benefits as the various advantages of the optical pickup of the present invention described above. Data recorded on the medium can be reproduced.

[0050] These effects and other advantages of the present invention will become apparent from the embodiments described below.

[0051] As described above, the optical pickup of the present invention includes the first spherical aberration correcting unit and the second spherical aberration correcting unit. Accordingly, it is possible to suitably correct spherical aberration.

[0052] Further, the information device of the present invention includes a determining unit, a first spherical aberration correcting unit, a second spherical aberration correcting unit, and a recording / reproducing unit. Therefore, it is possible to record data on the information recording medium and reproduce data recorded on the information recording medium while preferably correcting the spherical aberration.

Brief Description of Drawings

FIG. 1 is a block diagram schematically showing an overall configuration of an information recording / reproducing apparatus including an optical pickup according to an embodiment.

[FIG. 2] Of the information recording / reproducing apparatus according to the present embodiment, in particular, a more detailed configuration of the pickup. It is a block diagram shown roughly.

FIG. 3 is a flowchart conceptually showing a flow of operations of the information recording / reproducing apparatus in the example.

IV] is an explanatory diagram conceptually showing the amount of movement of the objective lens and the detection signal of the reflected light when calculating the substrate thickness.

FIG. 5 is a cross-sectional view conceptually showing one specific configuration of a first spherical aberration correction element and one aspect of correction of spherical aberration by the first spherical aberration correction element.

FIG. 6 is a cross-sectional view conceptually showing another specific configuration of the first spherical aberration correcting element and another aspect of correcting the spherical aberration by the first spherical aberration correcting element.

FIG. 7 is a cross-sectional view conceptually showing another specific configuration of the first spherical aberration correcting element and another aspect of correcting the spherical aberration by the first spherical aberration correcting element.

FIG. 8 is a sectional view conceptually showing the specific structure of a second spherical aberration correction element.

[9] FIG. 9 is a plan view conceptually showing an aspect of splitting reflected light when detecting spherical aberration.

FIG. 10 is a graph conceptually showing the level of spherical aberration correction of each of the first spherical aberration correcting element and the second spherical aberration correcting element.

[11] FIG. 11 is a cross-sectional view schematically showing one configuration of the first spherical correction element movable by a mechanical mechanism.

FIG. 12 is a cross-sectional view schematically showing another configuration of the first spherical correction element movable by a mechanical mechanism.

[13] FIG. 13 is a block diagram schematically showing a basic configuration of an information recording / reproducing measure according to a first modification.

FIG. 14 is a flowchart conceptually showing a flow of operations of the information recording / reproducing measure in accordance with the first modified example.

[15] FIG. 15 is a block diagram schematically showing a basic configuration of an information recording / reproducing measure according to a second modification.

[16] FIG. 16 is a block diagram schematically showing a basic configuration of an information recording / reproducing measure according to a third modification.

[17] A block that schematically shows the basic configuration of the information recording / reproducing measure according to the third modification. FIG.

Explanation of symbols

10 Optical disc

100 optical pickup

101 hologram laser

102 LCD λ Ζ2 plates

103 First spherical aberration correction element

104 Collimator lens

107 Second spherical aberration correction element

108 Objective lens

109 Actuator

110 Objective lens Ζ Position sensor

111 LCD drive

113 Hologram element

114 '-116 photodetector

117 Coma correction element

300 Information recording and playback device

313 Signal recording / reproducing means

314 CPU

314a Correction instruction section

314b Disc discriminator

314c Aberration calculator

314d Laser switching instruction section

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode for carrying out the present invention will be described in each embodiment in order with reference to the drawings.

[0056] (Configuration of recording / reproducing apparatus)

First, referring to FIG. 1, information recording comprising an embodiment according to the optical pickup of the present invention. A basic configuration of the playback apparatus (that is, the embodiment according to the information apparatus of the present invention) will be described. FIG. 1 is a block diagram schematically showing an overall configuration of an information recording / reproducing apparatus 300 including the optical pickup 100 according to the present embodiment. The information recording / reproducing apparatus 300 reproduces data recorded on each of a plurality of types of optical discs 10 having different substrate thicknesses and a function for recording data on each of a plurality of types of optical discs 10 having different substrate thicknesses. With functionality. In this embodiment, as a specific example of a plurality of types of optical disks 10, a CD with a substrate thickness of 1.2 mm, a DVD or HD DVD with a substrate thickness of 0.6 mm, and a Blu-ray Disc with a substrate thickness of 0.1 mm are assumed. And proceed with the explanation.

As shown in FIG. 1, the information recording / reproducing apparatus 300 includes a disk drive 301 in which the optical disk 10 is actually loaded and data is recorded and reproduced, and data recording and recording on the disk drive 301 are performed. And a host computer 302 such as a personal computer for controlling reproduction!

The disk drive 301 includes an optical disk 10, a spinner motor 311, an optical pickup 100, a signal recording / reproducing means 313, a CPU (drive control means) 314, a memory 315, a data input / output control means 316, and a bus 317. It is configured. The host computer 302 includes data input / output control means 318, CPU 319, memory 320, nose 321, operation Z display control means 322, operation buttons 323, and display panel 324.

The optical pickup 100 is configured to include, for example, a semiconductor laser device and a lens in order to record data on the optical disc 10. More specifically, the optical pickup 100 irradiates the optical disk 10 with the laser light LB as read light at the first power during reproduction, and as write light at the second power while being modulated during recording. The detailed configuration of the optical pickup 100 will be described later (see FIG. 2).

The spindle motor 311 rotates and stops the optical disc 10 and operates when accessing the optical disc 10. More specifically, the spindle motor 311 is configured to rotate and stop the optical disc 10 at a predetermined speed while receiving spindle servo from a servo unit (not shown) or the like.

The signal recording / reproducing means 313 records and reproduces data with respect to the optical disc 10 by controlling the spindle motor 311 and the optical pickup 100. More specifically, signal recording The reproducing unit 313 includes, for example, a laser diode driver (LD driver), a head amplifier, and the like. The laser diode driver drives the laser chip provided in the optical pickup 100 with current to emit laser light. The head amplifier amplifies the output signal of the optical pickup 100, that is, the reflected light of the laser beam LB, and outputs the amplified signal.

[0062] The memory 315 is used in general data processing in the disk drive 301 such as a data buffer area and an area used as an intermediate buffer when data is converted into data usable by the signal recording / reproducing means 313. . The memory 315 stores a program for operating as a recorder device, that is, a ROM area in which firmware is stored, a buffer for temporarily storing recording / playback data, and a variable necessary for the operation of the firmware program and the like. RAM area is configured.

A CPU (drive control means) 314 is connected to the signal recording / reproducing means 313 and the memory 315 via the bus 317, and controls the entire disk drive 301 by giving instructions to various control means. Normally, software or firmware for operating the CPU 314 is stored in the memory 315.

The data input / output control means 316 controls external data input / output to / from the disk drive 301 and stores and retrieves data in / from the data buffer on the memory 315. The drive control command issued from the external host computer 302 connected to the information recording device 300 via an interface such as SCSI or ATAPI is transmitted to the CPU 314 via the data input / output control means 316. The Similarly, data is exchanged with the host computer 302 via the data input / output control means 316.

The operation Z display control means 322 is for receiving and displaying an operation instruction for the host computer 302, and for example, transmits an instruction by the operation button 323 such as recording and reproduction to the CPU 319. The CPU 319 transmits a control command (command) to the information recording / reproducing device 300 via the data input / output unit 318 based on the instruction information from the operation Z display control unit 322 to control the entire disk drive 301. . Similarly, the CPU 319 can send a command requesting the disk drive 301 to send the operating status to the host. As a result, the operating state of the disk drive 301 such as recording can be grasped. 19 can output the operating state of the disk drive 301 to the display panel 324 such as a fluorescent tube or an LCD via the operation / display control means 322.

[0066] The memory 320 is an internal storage device used by the host computer 302. For example, a ROM area in which a firmware program such as BIOS (Basic Input / Output System) is stored, an operating system, an operation of an application program, etc. The RAM area that stores the necessary variables is also configured. Also, it is not shown in the figure via the data input / output control means 318, and may be connected to an external storage device such as a node disk.

One specific example of using the disk drive 301 and the host computer 302 in combination as described above is a household device such as a recorder device that records video. This recorder device is a device that records broadcast reception tuners and video signals of external connection terminal power on a disc. The program stored in the memory 320 is executed by the CPU 319 to operate as a recorder device. In another specific example, the disk drive 301 is a disk drive (hereinafter referred to as a drive as appropriate), and the host computer 302 is a personal computer or a workstation. A host computer such as a Norsonano computer and a drive are connected via data input / output control means 316 and 318 such as SCSI and ATAPI, and application capabilities such as reading software installed in the host computer 302 are used. Control the disk drive 301.

[0068] Next, with reference to FIG. 2, a more detailed configuration of the pick-up 100 included in the information recording / reproducing apparatus 300 according to the present embodiment will be described. FIG. 2 is a block diagram schematically showing a more detailed configuration of the pickup 100 in the information recording / reproducing apparatus 300 according to the present embodiment.

As shown in FIG. 2, the optical pickup 100 includes a hologram laser 101, a liquid crystal λ 2 plate 102, a first spherical aberration correction element 103, a collimator lens 104, a noise mirror 105, and an aperture limiting element. 106, second spherical aberration correction element 107, objective lens 108, actuator 110, objective lens Ζ position sensor 110, liquid crystal drive 111, condenser lens 112, hologram element 113, and photodetector 114. 116.

The hologram laser 101 constitutes a specific example of the “irradiation means” of the present invention, and a laser chip or a substrate that can emit laser light LB of a plurality of wavelengths (not shown) It has a ram element or the like. The laser chip and the light receiving element are arranged on the same substrate, and the hologram element is provided opposite to the output side of the laser beam LB on the substrate. The laser chip emits a laser beam LB corresponding to the type of the optical disk 10 having a plurality of types. More specifically, the laser chip irradiates, for example, a laser beam LB (ie, infrared laser beam) having a wavelength of 780 nm, for example, when recording or reproducing data on a CD, for example, data on a DVD. When recording or reproducing data, for example, when irradiating laser light LB having a wavelength of 660 nm (that is, red laser light) and recording or reproducing data on, for example, an HD DVD or Blu-ray Disc, For example, laser light LB having a wavelength of 420 nm (ie, blue-violet laser light) is irradiated. The light receiving element receives the input laser beam LB. The hologram element transmits the laser beam LB output from the laser chip as it is, and also receives a laser beam LB (that is, the reflection of the laser beam LB from the optical disc 10) that is also incident on the surface force opposite to the incident surface of the laser beam LB. Light) is refracted and focused on a light receiving element on the substrate. Thus, the hologram laser 11 has functions as a plurality of light sources and detectors.

[0071] Instead of the hologram laser 101 including a laser chip and a light receiving element together, a configuration including a plurality of laser chips and a plurality of light receiving elements may be employed.

[0072] The liquid crystal λ 2 plate 102 is a λ 2 plate provided with a liquid crystal element capable of changing the alignment state of liquid crystal molecules. The liquid crystal λΖ2 plate 102 changes the orientation state of the liquid crystal molecules, thereby electrically changing the polarization direction of the laser beam LB incident on the liquid crystal λΖ2 plate 102 according to the substrate thickness of the optical disk 10. Change to polarized light (or even other polarized light). The liquid crystal substrate 2 plate 102 is configured to change the polarization direction of the laser beam LB under the control of a correction instruction unit 314a described later.

The first spherical aberration correcting element 103, together with the liquid crystal λ 2 plate 102 and the collimator lens 104, constitutes one specific example of the “first spherical aberration correcting means” in the present invention, and the incident laser beam LB The optical path of the laser beam LB is changed according to the polarization direction of the laser beam (in other words, according to the substrate thickness of the optical disk 10). For example, when S-polarized laser beam LB is incident, the laser beam LB is propagated in one optical path, and negatively polarized laser beam LB is incident. In this case, the laser beam LB is propagated in another optical path having an optical path length longer than the one optical path. The first spherical aberration correction element 103 may be configured to change the optical path of the laser beam L under the control of a correction instruction unit 314a described later. Further, the detailed configuration and operation of the first spherical aberration correcting element 103 will be described in detail later (see FIGS. 5 to 7 and the like).

The collimator lens 104 converts the incident laser light LB into substantially parallel light and causes the half mirror 105 to radiate humans.

The half mirror 105 transmits the laser beam LB incident from the hologram laser 101 side by 90% as it is, and the laser beam LB (that is, the laser beam LB from the optical disk 10 is also incident on the side force of the optical disk 10). Reflected light) is transmitted by 90% and reflected by 10%. The reflected light of 10% reflected by the half mirror 105 is condensed on the photodetectors 114 to 116 via the condenser lens 112 and the hologram element 113.

The aperture limiting element 106 includes, for example, a liquid crystal shirt or the like, and the substrate thickness of the optical disc 10

In other words, the numerical aperture (NA) of the objective lens 108 on the emission side of the laser beam LB is substantially changed according to the type. For example, when recording or playing back data on a DVD or HD DVD with a substrate thickness of 0.6 mm, the liquid crystal shirt is controlled so that the effective numerical aperture of the object lens 108 is “0.65”. To do. On the other hand, for example, when recording or reproducing data on a Blu-ray Disc having a substrate thickness of 0.1 mm, the liquid crystal shutter is set so that the substantial numerical aperture of the objective lens 108 becomes “0.85”. Control the cutter.

The second spherical aberration correction element 107 constitutes a specific example of “second spherical aberration correction means” of the present invention, and includes, for example, a liquid crystal panel. The second spherical aberration correction element 107 follows the instruction from the liquid crystal drive 111 under the control of the correction instruction unit 314a that operates based on the actual amount of spherical aberration monitored by an aberration amount calculation unit 314c described later. The refractive index in the liquid crystal panel is appropriately changed. More specifically, when the refractive index in the liquid crystal panel changes, the optical path or partial phase of the laser beam LB transmitted through the second spherical aberration correction element 107 changes, and as a result, the spherical aberration is corrected. Is done. A specific configuration of the second spherical aberration correction element 107 will be described later in detail (see FIG. 8). The objective lens 108 constitutes a specific example of the “condensing unit” of the present invention, and condenses the incident laser beam LB and irradiates it on the recording surface of the optical disc 10.

The actuator unit 109 constitutes one specific example of the “moving means” of the present invention, and has a drive mechanism for changing the arrangement position of the objective lens 108. More specifically, the actuator unit 109 moves the position of the objective lens 108 in the focus direction (the Z direction, that is, the left and right direction in FIG. 2).

The objective lens Z position sensor 110 constitutes one specific example of the “measuring means” of the present invention, and the absolute or relative position of the objective lens in the Z direction (that is, the light of the laser beam LB). Measure along the axis, or absolute or relative position in the focus direction. Further, the objective lens Z position sensor 110 outputs the measured position of the objective lens in the Z direction to a disc determination unit 314b described later.

The liquid crystal drive 111 drives the liquid crystal panel included in the second spherical aberration correction element 107 under the control of a correction instruction unit 314a described later. More specifically, the liquid crystal drive 111 includes the second spherical aberration correction element 107 by applying a predetermined voltage to the second spherical aberration correction element 107 under the control of a correction instruction unit 314a described later. Changes the alignment state of liquid crystal molecules in the liquid crystal panel. As a result, the refractive index in the liquid crystal panel changes partially, and spherical aberration is corrected.

The condensing lens 112 fluoresces the reflected light reflected by the half mirror 105.

The hologram element 113 is disposed between the condensing lens 112 and the condensing point of the reflected light collected by the condensing lens 112. The hologram element 113 divides the reflected light spot formed on the hologram element 113 into a plurality of divided spot areas, and a part of the reflected light in each spot area is detected by the photodetectors 114 to 116. The light is condensed according to the deviation. A more detailed configuration or operation of the hologram element 113 will be described later in detail (see FIG. 9).

The photodetectors 114 to 116 constitute a specific example of the “light receiving means” of the present invention, and receive a part of the reflected light in the plurality of spot regions collected by the hologram element 113, and The light intensity level and the like are detected. The photodetectors 114 to 116 output the detected light intensity level and the like to an aberration amount detection unit 314c described later. In addition, the CPU 314 includes a correction instruction unit 314a, a disc determination unit 314b, and an aberration amount detection unit 314c.

[0086] The correction instruction unit 314a is based on the type (or substrate thickness) of the optical disc 10 output from the disc determination unit 314b, and the first spherical aberration correction element 103 (further, the liquid crystal λ 2 plate 102). To control. The liquid crystal drive 111 that drives the liquid crystal panel in the second spherical aberration correction element 107 is controlled based on the amount of spherical aberration output from the aberration amount detection unit 314c. That is, the correction instruction unit 314a determines the correction amount of the spherical aberration in each of the first spherical aberration correction element 103 and the second spherical aberration correction element 107, and corrects the spherical aberration based on the determined correction amount. As shown, each element in the optical pickup 100 is controlled.

The disc discrimination unit 314b constitutes a specific example of the “discrimination unit” in the present invention, and is absolute or relative in the Z direction of the objective lens output from the objective lens Z position sensor 110. Based on the correct position and the detection signal of the reflected light output from the hologram laser 101, the type (or substrate thickness) of the optical disk 10 loaded on the information recording / reproducing apparatus 300 is discriminated. The disc discriminating unit 314b outputs the discriminated type (or substrate thickness) of the optical disc 10 to the correction instruction unit 314a.

The aberration amount detection unit 314c constitutes one specific example of the “calculation unit” of the present invention, and is actually generated based on the light intensity level output from the photodetectors 114 to 116. Calculate the amount of spherical aberration. The aberration calculation unit 314c outputs the calculated amount of spherical aberration to the correction instruction unit 314a.

[0089] (Operational principle of information recording / reproducing apparatus)

Next, the operation principle of the information recording / reproducing apparatus 300 according to the present embodiment will be described with reference to FIGS. Here, the overall operation flow of the information recording / reproducing apparatus 300 according to the present embodiment will be described with reference to FIG. 3, and a more detailed description will be given with reference to FIGS. 4 to 10 as appropriate. I will add. FIG. 3 is a flowchart conceptually showing a flow of operations of the information recording / reproducing apparatus 300 in the example.

As shown in FIG. 3, first, the laser beam corresponding to the optical disc 10 having the maximum recording capacity among a plurality of types of optical discs 10 to which the information recording / reproducing apparatus 300 performs data recording or reproduction. LB is irradiated. Specifically, the information recording / reproduction according to the present embodiment is performed. Of the multiple types of optical discs 10 to which the live device 300 records and reproduces data, the optical disc 10 having the largest recording capacity has a recording capacity of approximately 25 GB to 27 GB (provided that one side has one layer). Blu-ray Disc. Accordingly, a blue-violet laser beam (that is, a laser beam LB having a wavelength of 420 nm) for recording or reproducing data on the Blu-ray Disc is irradiated from the hologram laser 101 (step S101). At this time, the tracking servo and focus servo remain open.

Subsequently, the objective lens 108 is moved in the Z direction by the operation of the actuator unit 109 while irradiating the laser beam LB (step S102). Specifically, it is preferable to move the objective lens 108 so that the objective lens 108 gradually approaches the optical disk 10 (more specifically, the left side force in FIG. 2 is also directed to the right side). Thereafter, the substrate thickness of the optical disc 10 is calculated based on the so-called S-curve detected as the objective lens 108 moves and the position of the objective lens 108 at that time (step S103).

Here, the calculation operation of the substrate thickness will be described in more detail with reference to FIG. FIG. 4 is an explanatory diagram conceptually showing the amount of movement of the objective lens 108 and the detection signal of the reflected light when calculating the substrate thickness.

As shown in the upper part of FIG. 4 (a), the focal point of the laser beam LB coincides with the surface of the optical disc 10 as the objective lens 108 moves. That is, as the objective lens 108 moves, the laser beam LB is focused on the surface of the optical disc 10. In this case, a so-called S-shaped signal waveform (S-shaped curve) appears in the reflected light detection signal, as shown on the left side of FIG. Thereafter, as shown in the lower part of FIG. 4A, after the objective lens 108 is further moved by the distance d, the focal point of the laser beam LB coincides with the recording surface of the optical disc 10. Even in this case, a so-called S-shaped signal waveform (S-curve) appears in the reflected light detection signal as shown on the right side of FIG.

Note that since the reflectance of the surface of the optical disk 10 is smaller than the reflectance of the recording surface of the optical disk 10, the focal point of the laser beam LB is the surface of the optical disk 10 as shown in FIG. The amplitude of the S-shaped signal waveform when it matches is smaller than the amplitude of the S-shaped signal waveform when the focal point of the laser beam LB matches the k recording surface of the optical disc 10.

[0095] At this time, until the laser beam LB matches the surface of the optical disc 10 and the force also matches the recording surface. The amount of movement of the objective lens 108 in between indicates the substrate thickness of the optical disc 10 directly or indirectly. Therefore, the disc discriminating unit 314b monitors the detection signal of the reflected light output from the hologram laser 101, and after obtaining the first S-shaped signal waveform, the second S-shaped signal waveform is obtained. The amount of movement d of the objective lens 108 until the signal waveform is obtained is calculated from the output of the objective lens Z position sensor 110. Thereby, the substrate thickness of the optical disk 10 is calculated.

[0096] If the moving speed of the objective lens 108 is constant, the time from when the first S-shaped signal waveform is obtained until the second S-shaped signal waveform is obtained. The substrate thickness of the optical disk 10 can also be calculated by detecting ΔΤ. That is, by multiplying the moving speed of the objective lens 108 and the time ΔΤ between the time when the first S-shaped signal waveform is obtained and the time when the second S-shaped signal waveform is obtained. The substrate thickness of the optical disk 10 can be calculated. As a result, it is not necessary to provide the objective lens Z position sensor 110, and the configuration of the optical pickup 100 can be simplified.

Note that the S-shaped signal waveform described above is generally used during a focusing operation, and in the present embodiment, this is used effectively to calculate the substrate thickness of the optical disc 10. I'm out. Accordingly, it is possible to calculate the substrate thickness of the optical disk 10 without increasing the processing load of the information recording / reproducing apparatus 300.

In FIG. 3 again, subsequently, the type of the optical disc 10 is determined based on the substrate thickness calculated in step S103 by the operation of the disc determination unit 314b (step S104). Thereafter, rough correction of spherical aberration (that is, correction of spherical aberration by the first spherical aberration correction element 103) is performed under the control of the correction instruction unit 314a (step S105).

Here, referring to FIG. 5 to FIG. 7, the specific configuration of the first spherical aberration correction element 103 and the specific mode of correction of spherical aberration by the first spherical aberration correction element 103 (ie, rough correction) Will be described. FIGS. 5 to 7 are sectional views conceptually showing a specific configuration of the first spherical aberration correcting element 103 and a specific mode of correcting the spherical aberration by the first spherical aberration correcting element 103, respectively. .

As shown in FIG. 5, the first spherical aberration correcting element 103a constitutes a specific example of the “optical path adjusting means” of the present invention, and is a prism having a configuration similar to a pen tab rhythm. First The spherical aberration correction element 103a includes an incident surface 1031, a light separation surface 1032, mirrors 1033a and 1033b, and an output surface 1034.

The incidence surface 1031 and the emission surface 1034 transmit the laser light LB emitted from the hologram laser 101 regardless of the polarization direction.

[0102] The light separation surface 1032 includes a dielectric multilayer film including a polarization separation film. The light separation surface 1032 selectively transmits a specific polarization component of the laser light LB and the other of the laser light LB. It selectively reflects the polarization component of. For example, the light separation surface 1032 shown in FIG. 5 selectively transmits the P-polarized component of the laser beam LB and selectively reflects the S-polarized component of the laser beam LB. At this time, it is preferable that the light separation surface 1032 be disposed with an angle of approximately 45 degrees with respect to the optical axis from the hologram laser 101.

Each of mirrors 1033a and 1033b reflects laser beam LB. Each of the mirrors 1033a and 1033b has the same optical axis as the laser beam LB of the P-polarized component transmitted on the light separation surface 1032 and the laser beam LB of the S-polarized component reflected on the light separation surface 1032. It arrange | positions so that it may radiate | emit from an incident surface.

With such a first spherical aberration correction element 103, the optical path length of the P-polarized component laser beam LB and the optical path length of the S-polarized component laser beam LB can be changed. Specifically, the optical path length of the laser beam LB of the P-polarized component is longer than the optical path length of the laser beam LB of the S-polarized component. At this time, the liquid crystal λ 2 plate 102 constituting one specific example of the “conversion means” of the present invention is applied to the first spherical aberration correction element 103 according to the substrate thickness of the optical disc 10 under the control of the correction instruction unit 314a. The polarization direction of the incident laser beam LB can be arbitrarily converted (that is, set). In other words, the optical path length of the laser beam LB can be changed according to what polarization component the laser beam LB emitted from the liquid crystal λ 2 plate 102 has. The change in the optical path length of the laser beam LB corresponds to the change in the optical distance from the hologram laser 101 to the collimator lens 104. By changing the optical distance from the hologram laser 101 to the collimator lens 104, the correction amount of the spherical aberration added to the laser beam LB can be changed. More specifically, by changing the optical distance from the hologram laser 101 to the collimator lens 104, the collimator lens 104 changes, for example, the laser beam LB of a Ρ-polarized component into a parallel light beam, for example, while it changes, for example, an S-polarized component. For laser beam LB For example, a refractive index different from the refractive index given to the P-polarized component is given. This is equivalent to correcting the spherical aberration at a relatively large level. Therefore, by changing the polarization direction of the laser beam LB emitted from the liquid crystal λ 2 plate 102 according to the substrate thickness of the optical disc 10, correction of spherical aberration according to the substrate thickness of the optical disc 10 at a relatively large level. It can be performed.

[0105] For example, when recording or reproducing data on a Blu-ray Disc (that is, the optical disc 10 having a substrate thickness of 0.1 mm) as an example of the optical disc 10, the correction instruction unit 314a transmits the laser beam LB. The liquid crystal λ 2 plate 102 is controlled so that the polarization direction is converted to S-polarized light. As a result, the S-polarized component laser light LB is emitted from the liquid crystal λ 2 plate 102, and as a result, the optical path length of the laser light LB becomes relatively short. On the other hand, when recording or reproducing data on an HD DVD (that is, an optical disc 10 having a substrate thickness of 0.6 mm) as an example of the optical disc 10, the correction instruction unit 314a changes the polarization direction of the laser beam LB to P-polarization. The liquid crystal λ 2 plate 102 is controlled so as to convert into As a result, the laser beam LB of the polarization component is emitted from the liquid crystal λ 2 plate 102, and as a result, the optical path length of the laser beam LB becomes relatively long.

Of course, the optical path length of the laser beam LB can be changed by the same procedure for the optical disc 10 having another substrate thickness (for example, the optical disc 10 having a substrate thickness of 1.2 mm). For example, when recording or reproducing data on a DVD as an example of the optical disc 10 (that is, the optical disc 10 having a substrate thickness of 0.6 mm), the correction instruction unit 314a changes the polarization direction of the laser beam LB to S. The liquid crystal λ 2 plate 102 is controlled so as to be converted into polarized light. As a result, the laser light LB of the S-polarized component is emitted from the liquid crystal λ 2 plate 102, and as a result, the optical path length of the laser light LB becomes relatively short. At this time, since the DVD substrate thickness is the same as the HD DVD substrate thickness, the reflectivity of the laser beam LB from the optical disc 10 is detected, or the disc code recorded on the optical disc 10 is detected. By reading, the type of the optical disk 10 may be identified in more detail. On the other hand, when recording or reproducing data on a CD (that is, an optical disk 10 having a substrate thickness of 1.2 mm) as an example of the optical disk 10, the correction instruction unit 314a changes the polarization direction of the laser beam LB to P-polarized light. The liquid crystal display Z2 plate 102 is controlled to be converted into As a result, the liquid crystal λ Ζ2 plate 102 emits laser light of P-polarized component L B is emitted, and as a result, the optical path length of the laser beam LB becomes relatively long.

In this case, a light separation surface 1032, mirrors 1033a and 1033b, etc. are arranged in the first spherical aberration correction element 103a so that the spherical aberration can be suitably corrected for each optical disc 10. It is preferable. Therefore, the arrangement of these constituent elements is such that the type of optical disk 10 (or substrate thickness) that can be handled by the information recording / reproducing apparatus 300 is the wavelength of the laser beam LB corresponding to the type of optical disk 10 or a plurality of types. Considering the amount of spherical aberration that can occur in each of the optical discs 10, and various parameters of the components of the optical system in the optical pickup 100, experimental, empirical, mathematical or theoretical, simulation, etc. It is preferable to individually specify using.

As shown in FIG. 6, the first spherical aberration correction element 103b is a prism including an entrance surface 1031, light separation surfaces 1032a and 1032b, mirrors 1033a and 1033b, and an exit surface 1034. Even in the first spherical aberration correcting element 103b having such a configuration, similarly to the first spherical aberration correcting element 103a described above, the spherical aberration corresponding to the substrate thickness of the optical disk 10 is relatively high. Correction can be performed.

[0109] If the optical path length of the laser beam LB can be changed by providing the above-described light separation surface 1032, mirror 1033, or the like, or similar components, the arrangement and shape of the light separation surface 1032, mirror 1033, etc. Furthermore, the shape of the first spherical aberration correction element 103 and the like can adopt any configuration. Further, in addition to or in place of the P-polarized component and the S-polarized component described above, the other optical components may be used to further change the optical path length of the laser beam LB. Further, if the optical path length of the laser beam LB having a specific property can be selectively changed, it can function as the first spherical aberration correction element 103 described above. Therefore, the optical path length may be changed based on other properties or characteristics of the laser beam LB in addition to or instead of the polarization component. In this case, in place of or instead of the liquid crystal λ 2 plate 102, an element that can set or convert other characteristics or characteristics of the laser beam LB is used as the hologram laser 101 and the first element. It is preferable to dispose it between the spherical aberration correction element 103.

As shown in FIG. 7, the first spherical aberration correction element 103c constitutes a specific example of the “optical path adjusting means” of the present invention, and includes a cuboid calcite (CaCO 3). . [0111] Calcite has a crystal structure called a sodium nitrate structure and has unique optical properties. That is, calcite separates laser light incident from a specific direction of the crystal into two polarization components (for example, a P-polarization component and an S-polarization component), and for each of the polarization components orthogonal to each other, Have different refractive indices. For example, the laser beam LB of the P-polarized component has a refractive index n = l.8, while the laser beam LB of the S-polarized component has a refractive index n = l.6. Therefore, since each of the laser beams LB having two polarization components travels through the crystal having different refractive indexes by an equal distance, the optical path length of each laser beam LB (more specifically, each laser beam LB is air The optical path length (assuming that it is transmitted inside) can be changed substantially. Therefore, similarly to the first spherical aberration correction elements 103a and 103b described above, it is possible to perform correction at a relatively large level of spherical aberration according to the substrate thickness of the optical disc 10.

In this case as well, the size and type of the first spherical aberration correction element 103c (that is, the size and type of calcite) are the types of optical discs 10 that the information recording / reproducing apparatus 300 can handle (or (Substrate thickness) and the wavelength of the laser beam LB according to the type of the optical disk 10, the amount of spherical aberration that can occur in each of the multiple types of optical disks 10, and various parameters of the components of the optical system in the optical pickup 100 In consideration of the characteristics of calcite and calcite, it is preferable to specify them experimentally, empirically, mathematically or theoretically, or individually using simulation or the like.

In FIG. 3 again, subsequently, the laser beam LB having a wavelength corresponding to the optical disc 10 being loaded is irradiated by the operation of the hologram laser 101 (step S106). Specifically, the laser beam LB corresponding to the type of the optical disc 10 determined in step 104 is irradiated. More specifically, if it is determined that the loaded optical disc 10 is, for example, a CD, a laser beam LB having a wavelength of 780 nm (ie, infrared laser beam) is irradiated. If it is determined that the loaded optical disk 10 is, for example, a DVD, a laser beam LB having a wavelength of 660 nm (that is, a red laser beam) is irradiated. If it is determined that the loaded optical disc 10 is, for example, an HD DVD or a Blu-ray Disc, a laser beam LB having a wavelength of 420 nm (that is, a blue-violet laser beam) is irradiated. [0114] Subsequently, the focus servo and tracking servo are closed (in other words, the focus servo and tracking servo are switched ON) by the operation of the servo circuit (not shown), and the tracking process and the focusing process are executed. (Step S107).

[0115] After that, zero correction of spherical aberration (that is, correction of spherical aberration by the second spherical aberration correction element 107) is performed (step S108), and then data is recorded on the optical disc 10 or the optical disc 10 is recorded. The recorded data is played back (step S109).

Here, referring to FIG. 8 and FIG. 9, the specific configuration of the second spherical aberration correction element 107 and the specific mode of correction of the spherical aberration by the second spherical aberration correction element 107 (ie, zero correction) Will be described. FIG. 8 is a sectional view conceptually showing the specific configuration of the second spherical aberration correcting element 107, and FIG. 9 conceptually shows how the reflected light is divided when detecting the spherical aberration. FIG.

As shown in FIG. 8 (a), the second spherical aberration correction element 107 includes glass substrates 1071a and 1071b, transparent electrodes 1072a and 1072b, self-directing films 1073a and 1073b, and liquid crystal 1074. Prepare. Transparent electrodes 1072a and 1072b configured, for example, with ITO (Indium Titan Oxide) force are deposited on the inner surfaces of the glass substrates 1071a and 1071b. In addition, alignment films 1073a and 1073b are provided on the inner surfaces of the transparent electrodes 1072a and 1072b to give the liquid crystal molecules in the liquid crystal molecules a predetermined molecular orientation. A liquid crystal 1074 having birefringence such as a nematic liquid crystal is sealed between the alignment films 1073a and 1074b. That is, the liquid crystal 1074 has a birefringence effect in which the refractive index differs between the direction of the optical axis of the liquid crystal molecules in the liquid crystal 1074 and the direction perpendicular thereto.

[0118] As shown in Fig. 8 (b), at least one of the transparent electrodes 1072a and 1072b is divided into a matrix, and each of the divided electrode portions (that is, the cells in Fig. 8 (b)) is divided. A different voltage can be applied to the liquid crystal 1074 for each corresponding part). The application of powerful voltages to each of the divided electrode parts (that is, the plurality of matrix parts constituting the transparent electrode 1072a or 1072b) is controlled by the operation of the liquid crystal drive 111 that is controlled by the correction instruction part 314a. Is done.

[0119] Thus, different voltages can be applied to each of the plurality of divided electrode parts, The refractive index of the liquid crystal 1074 can be changed in a shape corresponding to the divided electrode portion. In other words, the refractive index in the liquid crystal 1074 can be changed into a matrix. Therefore, an optical path difference can be imparted (in other words, the optical path length can be changed) for each beam of the laser beam LB that passes through each matrix portion. The second spherical aberration correcting element 107 uses a liquid crystal 1074 to give an optical path difference. For this reason, the second spherical aberration correction element 107 has a smaller level than the first spherical aberration correction element 103 that uses the components such as the light separation surface 1032 and the mirror 1033 described above to provide an optical path difference. The optical path difference can be given. Further, since different optical path differences can be given to the liquid crystals 1074 corresponding to the divided electrode parts, different optical path differences can be given in more detail. Therefore, the second spherical aberration correction element 107 is compared with the first spherical aberration correction element 103 by controlling the voltage applied to each of the plurality of electrode portions divided according to the spherical aberration. Aberrations can be corrected at a finer level. In other words, the second spherical aberration correction element 107 can correct spherical aberration that cannot be removed by the correction by the first spherical aberration correction element 103.

At this time, the amount of spherical aberration actually generated by irradiating the optical disc 10 with the laser beam LB is calculated, and the applied voltage is controlled so that the amount of spherical aberration becomes substantially zero. The As shown in FIGS. 2 and 9, the amount of spherical aberration is calculated based on the intensity distribution of the effective beam spot of the reflected light on the hologram element 113 disposed between the condenser lens 112 and the photodetectors 114 to 116. The In other words, it is calculated based on the light intensity distribution on the far field. As shown in FIG. 9, the reflected light radiated onto the hologram element 113 is, for example, concentrically divided by the hologram element 113 and then condensed on the corresponding photodetectors 114 to 116, respectively. For example, the light corresponding to the outermost peripheral part of the effective beam spot of the reflected light is condensed on the photodetector 114, and the light corresponding to the middle part of the effective beam spot of the reflected light is condensed on the photodetector 115 to be reflected light. The light corresponding to the innermost peripheral portion of the effective beam spot is collected to the photodetector 116. The intensity of the reflected light detected by each of the photodetectors 114 to 116 is output to the aberration amount calculation unit 314c in FIG.

[0121] In the aberration amount calculation unit 314c of Fig. 2, the detection is made by each of the photodetectors 114 to 116. The amount of spherical aberration is calculated by comparing the intensities of reflected light with each other. Specifically, if the intensity of the reflected light detected by each of the photodetectors 114 to 116 has the same value, the aberration amount calculation unit 314c calculates the amount of small spherical aberration. On the other hand, if the intensity of the reflected light detected by each of the photodetectors 114 to 116 has a large difference, the aberration amount calculation unit 314c calculates the amount of large spherical aberration. In addition, the aberration amount calculation unit 314c further calculates the direction of spherical aberration and the like (that is, information on whether the spherical aberration is generated in the positive direction or the negative direction, for example). Also good. Information such as the calculated amount of spherical aberration is output to the correction instruction unit 314a.

[0122] The correction instruction unit 314a controls the voltage applied to the liquid crystal 1074 in FIG. 8 so that the second spherical aberration correction element 107 performs correction so that the spherical aberration becomes zero or substantially zero. Controls drive 111. Specifically, the liquid crystal drive 111 is applied so that a voltage capable of realizing a state in which the intensity of the reflected light detected by each of the photodetectors 114 to 116 has an equivalent value is applied to each of the divided electrode portions. Control. The liquid crystal drive 111 controls the voltage applied to each of the divided electrode units based on the control of the correction instruction unit 314a. As a result, a state in which the intensity of the reflected light detected by each of the photodetectors 114 to 116 has an equivalent value (that is, a state in which the spherical aberration is zero or substantially zero) is realized.

As described above, according to the information recording / reproducing apparatus 300 in the example, the optical path (optical path length) of the laser beam LB is changed by the first spherical aberration correction element 103, so that The spherical aberration is corrected at a large (in other words, rough) level. Further, the second spherical aberration correction element 107 controls the refractive index of the liquid crystal 1074 in a vigorous manner, thereby correcting spherical aberration that cannot be removed by the correction by the first spherical aberration correction element 103. In particular, since the first spherical aberration correction element 103 corrects the spherical aberration at a relatively large level, the second spherical aberration correction element 107 considers a relatively large level of spherical aberration. Accordingly, it is possible to suitably correct spherical aberration that cannot be removed by the correction by the first spherical aberration correcting element 103. Further, since the second spherical aberration correction element 107 corrects spherical aberration that cannot be removed by the correction by the first spherical aberration correction element 103, the first spherical aberration correction element 103 has a relatively large level. The spherical aberration can be suitably corrected. That is, the first spherical aberration correction element 103 and the second spherical aberration Each of the difference correction elements 107 has a complementary relationship of correcting spherical aberration that the other party cannot correct.

Here, the level of spherical aberration correction of each of the first spherical aberration correcting element 103 and the second spherical aberration correcting element 107 will be described in more detail with reference to FIG. FIG. 10 is a graph conceptually showing the level of spherical aberration correction of each of the first spherical aberration correcting element 103 and the second spherical aberration correcting element 107.

As shown in FIG. 10, the spherical aberration is corrected by the first spherical aberration correction element 103 until the residual aberration amount is approximately “0.02 rais”. Thereafter, the residual aberration remaining after the correction by the first spherical aberration correcting element 103 is corrected by the second spherical aberration correcting element 107 so as to be substantially “0”. Specifically, for example, the first spherical aberration correction element 103 corrects spherical aberration in the order of mm, and then the second spherical aberration correction element 107 occurs due to the substrate thickness variation in the order of several hundred nm. Spherical aberrations of a level smaller than the mm order are corrected. As a result, as shown by the bottom line of the graph in FIG.

Then, in the first spherical aberration correction element 103, the spherical aberration correction mode is changed according to the substrate thickness (or type) of the optical disk 10. Therefore, the optical disk 10 having any substrate thickness (specifically, for example, a CD having a substrate thickness of 1.2 mm, a DVD or HD DVD having a substrate thickness of 0.6 mm, and a Blu— ray disc), the first spherical aberration correction element 103 can preferably correct spherical aberration. Then, the second spherical aberration correction element 107 calculates the amount of spherical aberration actually occurring and corrects the spherical aberration while performing, for example, feedback control so that the amount becomes zero or substantially zero. ing. For this reason, it is possible to correct the spherical aberration more preferably after recognizing the aspect of the spherical aberration actually occurring. As described above, since the spherical aberration can be corrected in two levels, the spherical aberration can be corrected more suitably. As a result, the spherical aberration can be made zero or almost zero. Therefore, it is possible to preferably record or reproduce data on a plurality of types of optical discs 10 having different substrate thicknesses while suitably eliminating the adverse effects due to spherical aberration.

[0127] Power! In addition, the first spherical aberration correction element 103 (and the liquid crystal λ 2 plate 102) described above and the first Each of the two spherical aberration correction elements 107 is electrically controlled. For this reason, it is not necessary to adopt a mechanical mechanism that requires a relatively complicated configuration or that can relatively increase power consumption. Thereby, the configuration of the optical pickup 100 can be simplified, and the optical pickup 100 can be further reduced in size. In addition, the power consumption of the optical pickup 100 can be reduced. This is an excellent advantage not found in the above-mentioned Patent Documents 1 and 2.

[0128] Power! In addition, according to the information recording / reproducing apparatus 300 in the embodiment, the intensity distribution of reflected light on the far field is used when calculating the amount of spherical aberration. This is due to the fact that it is difficult to recognize the intensity distribution when the reflected light is focused on a small spot. Thus, by using the intensity distribution of the reflected light on the far field, the amount of spherical aberration can be calculated more appropriately and more accurately.

Note that the amount of aberration shown in FIG. 10 is merely a specific example, and it goes without saying that the amount of aberration may differ depending on the substrate thickness or the irradiation condition of the laser beam LB. For example, the correction amount by the first spherical aberration correction element 103 may be small, and on the other hand, the correction amount by the second spherical aberration correction element 107 may be large. Further, when the optical disk 10 having an extremely different substrate thickness is loaded, it may be assumed that the correction by the first spherical aberration correction element 103 cannot be suitably performed. In this case, the adverse effect due to the spherical aberration can be suitably eliminated by the correction by the second spherical aberration correcting element 107.

[0130] In the first spherical aberration correction element 103, the configuration and arrangement of the light separation surface 1032, the mirror 1033, and the like in FIG. 5 are not necessarily fixed. For example, the optical path of the laser beam LB may be changed by changing the configuration or arrangement of the light separation surface 1032, the mirror 1033, or the like according to the polarization direction of the incident laser beam LB. It is preferable to electrically change the configuration and arrangement of the light separation surface 1032 and the mirror 1033, for example. For example, an element that reflects light like a mirror when a voltage is applied, and transmits light like a transmissive film when no voltage is applied may be used. However, the configuration and arrangement of the light separation surface 1032 and the mirror 1033 may be changed using a mechanical mechanism. In the example shown in FIGS. 5 to 7, in the liquid crystal λ 2 plate 102 in FIG. 2, the laser beam LB polarized in a specific direction is selectively incident on the first spherical aberration correction element 103. It is configured as follows. However, even if the liquid crystal λ Ζ2 plate 102 is omitted, it is possible to use the fact that the laser beam LB is separated into the Ρ-polarized component and the S-polarized component on the light separation surface 1032 and calcite. The various benefits described above can be enjoyed. That is, after the laser beam LB is separated into the Ρ-polarized component and the S-polarized component on the light separation surface 1032 and calcite, the recording operation is not performed by condensing the laser beam LB of one of the polarization components on the recording surface. I use it for playback. If the laser beam LB of the other polarization component is not used for recording or reproducing operation without being collected on the recording surface, the laser beam LB polarized in a specific direction is selectively used as the first spherical aberration correction element. It is possible to enjoy the same benefits as those incident on 103.

In this case, the first spherical aberration correcting element 103 constitutes one specific example of each of the “dividing means” and the “adjusting means” of the present invention. More specifically, the light separating surface 1032 and calcite force described above constitute one specific example of the “dividing means” of the present invention, and the above-described mirror 1033 and calcite are the “adjusting means (optical path adjusting means) J of the present invention. One specific example is configured.

[0133] Needless to say, the first spherical aberration correction element 103 is not limited to the specific configuration described above. Furthermore, a configuration including a plurality of first spherical aberration correction elements 103 may be employed. For example, a first spherical aberration correction element used when recording and reproducing data on a Blu-ray Disc and HD DVD as a specific example of the optical disc 10, and a DVD as a specific example of the optical disc 10 The first spherical aberration correction element used when recording and reproducing data on the CD may be provided. In short, spherical aberration can be corrected if an element capable of changing the optical path length of the laser beam LB substantially or optically is inserted in the optical path of the laser beam LB. It can be used as the first spherical aberration correction element 103 according to the above.

Note that the first spherical aberration correction element 103 may be an element movable by a mechanical mechanism as shown in FIGS. 11 and 12. Here, each of FIGS. 11 and 12 is a cross-sectional view schematically showing a configuration of the first spherical correction element 103 movable by a mechanical mechanism.

As shown in FIG. 11, it is inserted on the optical path of the laser beam LB and on the optical path of the laser beam LB. An optical path correction element that can continuously change the thickness of the laser beam LB on the optical path by moving in the orthogonal direction may be used as the first spherical aberration correction element 103. In this case, as the substrate thickness of the optical disk 10 increases, the optical path correction element is moved by the operation of a mechanical mechanism such as a motor in the direction in which the thickness of the optical path correction element in the optical path of the laser beam LB decreases. The As a result, the positive spherical aberration that occurs when the substrate thickness of the optical disk 10 increases can be canceled by the negative spherical aberration that occurs when the thickness of the optical path correction element in the optical path of the laser beam LB decreases. On the other hand, when the substrate thickness of the optical disk 10 is reduced, the optical path correction element is moved by the operation of a mechanical mechanism such as a motor, for example, in the direction of increasing the thickness of the optical path correction element in the optical path of the laser beam LB. The As a result, the negative spherical aberration that occurs when the substrate thickness of the optical disk 10 is reduced can be canceled by the positive spherical aberration that occurs when the thickness of the optical path correction element in the optical path of the laser beam LB increases. Thus, even when the first spherical correction element 103 shown in FIG. 11 is used, a large level of spherical aberration can be suitably corrected.

[0136] Also, as shown in FIG. 12, the thickness of the laser beam LB in the optical path is gradually increased by being inserted in the optical path of the laser beam LB and moving in a direction orthogonal to the optical path of the laser beam LB. An optical path correction element that can be changed may be used as the first spherical aberration correction element 103.

However, in consideration of the benefits that can be enjoyed by not having the mechanical mechanism described above, the first spherical aberration correction element 103 having the configuration shown in FIGS. 5 to 7 can be used. Note that it is more preferable.

[0138] The aperture limiting element 106 may be configured to have polarization dependency. That is, the numerical aperture can be selectively changed with respect to the laser beam LB having a predetermined polarization component that is selectively applied to the optical disc 10 according to the type (or substrate thickness) of the optical disc 10. May be. Of course, it does not have to have polarization dependency, or may be configured so as to have wavelength dependency. In this case, the aperture limiting element 106 is configured such that the wavelength of the laser beam LB corresponding to CD is 780 nm, the wavelength of the laser beam LB corresponding to DVD is 660 nm, and the wavelength of the laser beam LB corresponding to HD DVD or Blu-ray Disc. The wavelength transmission filter corresponding to each of 420 nm may be combined. [0139] Further, instead of the liquid crystal λ 2 plate, a λ 2 plate made of a predetermined resin may be taken in and out of the optical path of the laser beam LB using a mechanical mechanism. However, in view of the benefits that can be enjoyed by not having the mechanical mechanism described above, it is preferable to use a liquid crystal λ / 2 plate.

[0140] Further, the collimator lens 104 may be configured to move along the optical path of the laser beam LB (in other words, along the optical axis of the collimator lens 104). Even with this configuration, an effect equivalent to the effect of correcting the spherical aberration by the first spherical aberration correcting element 103 described above can be obtained.

In addition to or instead of operating based on the actual amount of spherical aberration calculated by the aberration amount calculation unit 314c, the second spherical aberration correction element 107 converts the reflected light of the laser beam LB into a hologram. It may be configured to operate based on the signal level such as RF signal, LPP signal, or wobble signal obtained by receiving light with the light receiving element in laser 101! / ヽ. More specifically, the second spherical aberration correction element 107 is a signal that changes depending on the spot position of the laser beam LB on the optical disc 10 (for example, RF signal, LPP signal, wobble signal, CAPA signal, TE signal, pre-pit signal). , Embossing, etc.) so that the signal level is almost the maximum level (or so that the recording operation and playback operation are not adversely affected), while monitoring these signal levels, You may comprise so that aberration may be corrected. Even with this configuration, it is possible to obtain the same effect as the spherical aberration correction by the second spherical aberration correction element 107 based on the actual spherical aberration amount calculated by the aberration amount calculation unit 314c. However, based on the actual amount of spherical aberration calculated by the aberration amount calculation unit 314c, it is possible to recognize in which direction the spherical aberration is generated. In which direction the spherical aberration is generated, it is difficult or impossible to recognize from the signal level of the RF signal, LPP signal, and wobble signal. For this reason, it is preferable that the viewpoint power of correcting spherical aberration more easily or efficiently is to correct spherical aberration based on the actual amount of spherical aberration calculated by the aberration amount calculation unit 314c.

[0142] In addition to the correction of the spherical aberration by the first spherical aberration correction element 103 and the second spherical aberration correction element 107 described above, a focus error signal that is performed under the control of the CPU 314 or the like. The spherical aberration may be corrected at a finer level by using the offset adjustment of the signal. As a result, a predetermined offset is added to the target signal level of the focus error signal (that is, the target signal level is set such that a focus position shift occurs according to the focus error signal), so that the laser beam LB In addition to adjusting the spot diameter on the optical disk 10, spherical aberration can be corrected on the m order. At this time, if the offset adjustment of the focus error signal is performed, a new spherical aberration may occur. Therefore, when the offset adjustment of the focus error signal is used, the spherical aberration becomes substantially zero by repeatedly performing the offset adjustment of the focus error signal and the correction of the spherical aberration by the second spherical aberration correction element 107. It is preferable to operate. It can be said that the CPU 314 for performing the offset adjustment of the focus error signal has a configuration corresponding to a specific example of the “second spherical aberration correcting unit” of the present invention.

[0143] (First modification of information recording / reproducing apparatus)

Next, the information recording / reproducing apparatus 300a according to the first modification will be described with reference to FIG. 13 and FIG. FIG. 13 is a block diagram schematically showing the basic configuration of the information recording / reproducing measure 300a according to the first modification. FIG. 14 is a block diagram of the information recording / reproducing measure 300a according to the first modification. It is a flowchart which shows notionally the flow of operation | movement. Note that the same reference numerals or step numbers are assigned to the same configurations and operations as those of the information recording / reproducing apparatus 300 described above, and detailed description thereof is omitted. Hereinafter, a configuration and operation different from those of the information recording / reproducing apparatus 300 will be described in detail.

As shown in FIG. 13, an information recording / reproducing apparatus 300a according to the first modification has a configuration similar to that of the information recording / reproducing apparatus 300 described above.

[0145] The information recording / reproducing apparatus 300a according to the first modification does not particularly have the objective lens Z position sensor 110. Therefore, the information recording / reproducing apparatus 300a according to the first modification determines the type (or substrate thickness) of the optical disc 10 by the following method.

As shown in FIG. 14, the information recording / reproducing apparatus 300a according to the first modification irradiates a laser beam LB having a predetermined wavelength among the plurality of laser beams LB corresponding to the plurality of optical disks 10. (Step S201). After that, the disk servo (for example, focus servo and tracking servo) is switched on (step S202) and rough correction of spherical aberration is performed. (That is, correction of spherical aberration by the first spherical aberration correction element 103) is performed (step S1 05).

[0147] Thereafter, it is determined whether or not it is possible to read predetermined data on the optical disc 10 (step S203).

[0148] As a result of this determination, if it is determined that predetermined data on the optical disc 10 can be read (step S203; Yes), the disc ID or the like recorded on the optical disc 10 is obtained ( Step S205). As a result, the type of the optical disc 10 can be determined, and the substrate thickness of the optical disc 10 can be determined based on the determined type of the optical disc 10. Thereafter, similarly to the information recording / reproducing apparatus 300 described above, the laser beam LB having a wavelength corresponding to the optical disc 10 being loaded is irradiated (step S106), and the focus servo and tracking servo are switched on (step S107). ), Zero correction of spherical aberration (that is, correction of spherical aberration by the second spherical aberration correction element 107) is performed (step S108), and then data is recorded on the optical disk 10 or data recorded on the optical disk 10 is reproduced. Is performed (step S109).

[0149] On the other hand, when it is determined that the predetermined data on the optical disc 10 cannot be read

(Step S202: No), the operation mode of the laser chip on the hologram laser 101 is switched by a laser driver or the like so as to irradiate the laser beam LB having a different wavelength (Step S204). Thereafter, the operation force of steps S202, S105 and S203 is repeated.

[0150] As described above, according to the information recording / reproducing apparatus 300a according to the first modification, the optical disk 10 is irradiated while sequentially switching a plurality of types of laser beams LB, and predetermined data on the optical disk 10 is transferred. If it is determined that the data could actually be read, the disk ID is obtained. As a result, the type (or substrate thickness) of the optical disk 10 can be determined. That is, the information recording / reproducing apparatus 300a according to the first modified example irradiates the optical disc 10 with each of a plurality of types of laser beams LB in a brute force manner. Is determined. For this reason, there is no need to provide the objective lens Z position sensor 110 unlike the information recording / reproducing apparatus 300, so that the configuration of the information recording / reproducing apparatus 300a can be made relatively simple.

[0151] (Second modification of information recording / reproducing apparatus) Next, an information recording / reproducing apparatus 300b according to the second modification will be described with reference to FIG. FIG. 15 is a block diagram schematically showing the basic configuration of the information recording / reproducing measure 300b according to the second modification. It should be noted that the same configuration and operation as the information recording / reproducing apparatuses 300 and 300a described above will be given the same reference numerals or step numbers, and detailed description thereof will be omitted. Hereinafter, a configuration and operation different from those of the information recording / reproducing apparatuses 300 and 300a will be described in detail.

As shown in FIG. 15, the optical pickup 10 Ob of the information recording / reproducing apparatus 300b according to the second modification includes a plurality of hologram lasers 101a and 101b, a collimator lens 104, a half mirror 105, and an aperture limiting element. 106, second spherical aberration correction element 107, objective lens 108, actuator 109, objective lens Z position sensor 110, liquid crystal drive circuit 111, condensing lens 112, hologram element 113, and photodetectors 114 to 116 With. The CPU 314 further includes a laser switching instruction unit 314d.

The plurality of hologram lasers 101a and 101b are arranged such that the distance to the collimator lens 104 (in other words, the distance to the optical disc 10) is different. Then, the laser switching instruction unit 314d selects which of the plurality of hologram lasers 101a and 101b irradiates the laser beam LB according to the type (or substrate thickness) of the optical disc 10, and a plurality of holograms. Laser light LB is irradiated from a hologram laser selected from among the lasers 101a and 101b.

For example, when recording or reproducing data with respect to a Blu-ray Disc, the laser switching instruction unit 314d is configured to irradiate the laser beam LB from the hologram laser 101a disposed on the side far from the collimator lens 104. Output instructions. On the other hand, when recording or reproducing data with respect to, for example, HD D VD, the laser switching instruction unit 314d is configured so that the laser beam LB is emitted from the hologram laser 101b disposed on the side closer to the collimator lens 104. Outputs instructions.

[0155] Thereby, the spherical aberration that occurs when the substrate thickness of the optical disk 10 is reduced or increased, and the reverse occurs when the distance between the hologram laser irradiated with the laser beam LB and the collimator lens 104 is changed. It can be canceled out by spherical aberration. As a result, similar to the first spherical aberration correction element 103, the spherical aberration can be corrected at a relatively large level. Can do.

Incidentally, the spherical aberration that could not be corrected by switching the hologram laser 101a or 101b irradiated with the laser beam LB is the same as the information recording / reproducing apparatus 300 described above. The spherical aberration correction element 107 corrects the spherical aberration at a finer level.

[0157] (Third Modification of Information Recording / Reproducing Device)

Next, with reference to FIG. 16, an information recording / reproducing apparatus 300c according to a third modification will be described. FIG. 16 is a block diagram schematically showing the basic configuration of the information recording / reproducing measure 300c according to the third modification. Note that the same reference numerals or step numbers are assigned to the same configurations and operations as those of the information recording / reproducing apparatuses 300, 300a, and 300b described above, and detailed description thereof is omitted. Hereinafter, configurations and operations different from those of the information recording / reproducing apparatuses 300, 300a, and 300b will be described in detail.

As shown in FIG. 16, the information recording / reproducing apparatus 300c according to the third modification has the same configuration as the information recording / reproducing apparatus 300b according to the second modification described above. In the information recording / reproducing apparatus 300c according to the third modification, in particular, the hologram laser 101b is disposed on the optical axis of the collimator lens 104, and the hologram laser 101a is disposed outside the optical axis of the collimator lens 104.

[0159] By arranging the plurality of hologram lasers 101a and 101b in this way, the hologram laser 101a and the hologram laser 101b (more specifically, the laser beam LB and the hologram laser irradiated from the hologram laser 101a) The inconvenience of interference with the laser beam LB irradiated with the 101b force can also be suppressed, thereby eliminating the adverse effects caused by the interference between the hologram laser 101a and the hologram laser 101b. Recording operation or playback operation can be realized.

[0160] Further, by arranging the hologram laser 101a outside the optical axis of the collimator lens 104, coma aberration occurs with respect to the laser light LB emitted from the hologram laser 101a. In the information recording / reproducing apparatus 300c according to the second modified example, the holographic laser 101a that corrects this coma aberration is on the optical path of the laser beam LB emitted from the hologram laser 101a and is connected to the hologram laser 101a and the collimator. For example, liquid crystal between the lens 104 A coma aberration correcting element 117 including a panel and the like is arranged. Thereby, the coma aberration can be appropriately corrected, and a more suitable recording operation or reproducing operation can be realized.

[0161] (Fourth modification of information recording / reproducing apparatus)

Subsequently, an information recording / reproducing apparatus 300d according to a fourth modification will be described with reference to FIG. FIG. 17 is a block diagram schematically showing the basic configuration of the information recording / reproducing measure 300d according to the fourth modification. In addition, about the structure and operation | movement similar to the information recording / reproducing apparatus 300, 300a, 30Ob, and 300c mentioned above, the detailed description is abbreviate | omitted by giving the same referential mark or step number. Hereinafter, a configuration and operation different from those of the information recording / reproducing apparatus 300, 300a, 300b, and 300c will be described in detail.

As shown in FIG. 17, the information recording / reproducing apparatus 300d according to the fourth modification includes the information recording / reproducing apparatus 300b according to the second modification and the information recording / reproducing apparatus 300c according to the third modification. It has the same configuration. In particular, the information recording / reproducing apparatus 300d according to the fourth modification is disposed so that the same amount of coma aberration is generated in the opposite direction with respect to the force collimator lens 104 of the hologram lasers 101a and 101b. With this configuration, the amount of coma aberration generated with respect to the laser beam LB irradiated with the power of the hologram lasers 101a and 101b is set, for example, by the hologram laser of the information recording / reproducing apparatus 300c according to the third modification. The amount of coma aberration generated with respect to the laser beam LB irradiated from 101a can be reduced (specifically, halved). Accordingly, the coma aberration correction amount to be corrected by the coma aberration correcting element 117 is also reduced accordingly. Thereby, the coma aberration correcting element 117 can be set relatively easily.

[0163] In the fourth embodiment, coma aberration occurs in the laser beam LB irradiated with the respective forces of the hologram lasers 101a and 101b. Therefore, the coma aberration correcting element 117 is used in each of the hologram lasers 101a and 101b. It is preferable that the laser beam LB is disposed on the optical path of the laser beam LB irradiated with force and between each of the hologram lasers 101 a and 101 b and the collimator lens 104.

Note that the information recording / reproducing apparatuses 300 and 300a to 300d described above are appropriately configured. It goes without saying that an information recording / reproducing apparatus appropriately selected and combined can also receive the various benefits described above, and is naturally within the scope of the present invention.

[0165] In the present invention, the force referred to only spherical aberration correction. Since spherical aberration correction and focus error signal offset adjustment are closely related, spherical aberration correction and focus error signal offset adjustment are performed alternately to optimize both. It is also included in the technical scope of the present invention.

Further, in the above-described embodiment, a DVD or the like is described as a specific example of the optical disc, and further, a force that describes a recorder or a player related to the optical disc as an example of a recording / reproducing device. The present invention is not limited to this, and can be applied to other high-density recording or various recording media compatible with a high transfer rate and its recorder or player.

[0167] The present invention is not limited to the above-described embodiments, but can be appropriately modified within the scope of the claims and the entire specification without departing from the gist or philosophy of the invention which can be read. Optical pickups and information devices are also included in the technical scope of the present invention.

Industrial applicability

[0168] An optical pickup and an information device according to the present invention include an optical pickup that emits light when recording data on or reproducing data from an information recording medium such as a DVD, and an information device including the optical pickup. Is available.

Claims

The scope of the claims

[1] An optical pickup for performing at least one of data recording and reproduction with respect to each of a plurality of types of information recording media,

The spherical aberration when the light beam irradiated to perform at least one of recording and reproduction of the data is focused on the information recording medium is the substrate thickness of the information recording medium determined by the determining means. A first spherical aberration correction means for correcting in response,

Second spherical aberration correction means for correcting the spherical aberration remaining after correction by the first spherical aberration correction means to the same or higher accuracy as the correction of the spherical aberration by the first spherical aberration correction means. When

An optical pickup comprising:

[2] The first spherical aberration correcting means is

A light beam splitting means for splitting the light beam into a plurality of beam bundles;

Adjusting means for adjusting each of the plurality of light bundles so that the spherical aberration of each of the plurality of light bundles is brought close to substantially zero according to the substrate thickness of the information recording medium determined by the determination means;

The optical pickup according to claim 1, further comprising:

[3] The first spherical aberration correcting means is

Conversion means for converting the optical beam into a light beam having a predetermined property according to the substrate thickness of the information recording medium determined by the determination means;

Optical path adjusting means that transmits the light beam having one property and reflects the light beam having another property different from the one property;

The optical pickup according to claim 1, further comprising:

[4] The first spherical aberration correcting unit corrects the spherical aberration by changing an optical path length of the light beam according to a substrate thickness of the information recording medium determined by the determining unit. The optical pickup according to claim 1.

[5] The distance from the information recording medium is different, and further includes a plurality of irradiation means for irradiating a plurality of light beams corresponding to each of the plurality of types of information recording media, the first spherical aberration correction means, The information recording medium discriminated by the discriminating means The spherical aberration is corrected by selecting one irradiating means for irradiating the information recording medium with the light beam according to the substrate thickness of the plurality of irradiating means. The optical pickup according to item 1.

6. The optical pickup according to claim 5, wherein each of the optical axes of the light beams irradiated from each of the plurality of irradiation means is different.

[7] Other irradiating means force except at least one irradiating means among the plurality of irradiating means. Coma aberration correction for correcting coma aberration when the irradiated light beam is condensed on the information recording medium. 6. The optical pickup according to claim 5, further comprising means.

8. The at least two irradiating means among the plurality of irradiating means are arranged so as to generate the same amount of coma aberration in opposite directions with respect to the collimator lens. The optical pickup described in 1.

[9] The optical pickup according to [1], wherein the first spherical aberration correcting means includes a collimator lens movable along the optical axis of the light beam.

[10] The second spherical aberration correcting means is based on the amount of spherical aberration calculated by the calculating means for calculating the amount of spherical aberration based on the reflected light of the light beam from the information recording medium. The optical pickup according to claim 1, wherein the spherical aberration is corrected.

[11] a dividing means for dividing the reflected light;

A plurality of light receiving means for receiving the divided reflected light;

The optical pickup according to claim 10, further comprising:

12. The optical pickup according to claim 1, wherein the second spherical aberration correcting means includes a liquid crystal element.

[13] The second spherical aberration correction means is a signal obtained by detecting reflected light of the light beam, and a signal level of the signal that varies depending on a spot position of the light beam on the information recording medium. 2. The optical pickup according to claim 1, wherein the spherical aberration is corrected so that becomes substantially maximum.

[14] Light condensing means for condensing the light beam on the recording medium; Moving means for moving the condensing means along the optical axis of the light beam;

Further comprising

2. The optical pickup according to claim 1, wherein the determination unit determines the thickness of the substrate based on a waveform of reflected light of the light beam detected while moving the condensing unit. .

[15] Irradiation means for irradiating a plurality of types of light beams for performing at least one of recording and reproduction of the data with respect to each of the plurality of types of information recording media; and In the discrimination by the above, a predetermined one type of light beam is selectively irradiated out of the plurality of types of light beams,

15. The optical pickup according to claim 14, wherein the discriminating unit discriminates the substrate thickness based on a waveform of the reflected light of the one kind of light beam.

16. The one type of light beam is a light beam corresponding to an information recording medium having a maximum data recording capacity among the plurality of types of information recording media. The optical pickup described in 1.

[17] The apparatus further includes a measuring unit that measures the amount of movement of the condensing unit by the moving unit, and the determining unit includes the reflected light when the light beam is collected on the surface of the information recording medium. Based on the amount of movement of the condensing means from when the waveform is detected until the waveform of the reflected light is detected when the light beam is condensed on the recording surface of the information recording medium, 15. The optical pickup according to claim 14, wherein the thickness of the substrate is discriminated.

[18] The apparatus further comprises irradiation means for irradiating a plurality of types of light beams for performing at least one of recording and reproduction of the data with respect to each of the plurality of types of information recording media, 2. The optical pickup according to claim 1, wherein the thickness of the substrate is determined by controlling the irradiation unit so that each of the light beams is sequentially irradiated onto the information recording medium.

[19] The second spherical aberration correction means includes: the plurality of types of optical beams irradiated to perform at least one of recording and reproduction of the data with respect to each of the plurality of types of information recording media; After the light beam corresponding to the substrate thickness determined by the determining means is irradiated 2. The optical pickup according to claim 1, wherein the spherical aberration is corrected.

An information device that performs at least one of data recording and reproduction on each of a plurality of types of information recording media,

Discriminating means for discriminating a substrate thickness of the information recording medium;

The substrate thickness of the information recording medium determined by the determining means is the spherical aberration when the light beam irradiated to perform at least one of the data recording and reproduction is focused on the information recording medium. First spherical aberration correction means for correcting according to

Second spherical aberration correction means for correcting the spherical aberration remaining after correction by the first spherical aberration correction means to the same or higher accuracy than the accuracy of correction of the spherical aberration by the first spherical aberration correction means; ,

Recording / reproducing means for performing at least one of recording and reproduction of the data by irradiating the information recording medium with the light beam;

An information device comprising: