WO2007114389A1 - Dispositif de saisie optique et d'information - Google Patents

Dispositif de saisie optique et d'information Download PDF

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Publication number
WO2007114389A1
WO2007114389A1 PCT/JP2007/057282 JP2007057282W WO2007114389A1 WO 2007114389 A1 WO2007114389 A1 WO 2007114389A1 JP 2007057282 W JP2007057282 W JP 2007057282W WO 2007114389 A1 WO2007114389 A1 WO 2007114389A1
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WO
WIPO (PCT)
Prior art keywords
light
region
received
outer diameter
inner diameter
Prior art date
Application number
PCT/JP2007/057282
Other languages
English (en)
Japanese (ja)
Inventor
Naoharu Yanagawa
Masataka Izawa
Original Assignee
Pioneer Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pioneer Corporation filed Critical Pioneer Corporation
Priority to JP2008508686A priority Critical patent/JPWO2007114389A1/ja
Publication of WO2007114389A1 publication Critical patent/WO2007114389A1/fr

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/13—Optical detectors therefor
    • G11B7/131—Arrangement of detectors in a multiple array
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1356—Double or multiple prisms, i.e. having two or more prisms in cooperation

Definitions

  • the present invention relates to a technical field of an optical pickup that irradiates a laser beam when data is recorded or reproduced on an information recording medium such as a DVD, and an information device including the optical pickup.
  • a multi-layer optical disk or the like that optically records or reproduces an information signal (data) using a laser beam or the like, such as a dual-layer Blu-ray or a dual-layer DVD.
  • Information recording media have been developed.
  • the signal from the selected recording layer may be deteriorated due to the influence of spherical aberration. It tends to narrow the interval.
  • the return light from the multi-layer optical disc is caused by so-called interlayer crosstalk, so that the desired recording layer (hereinafter referred to as “one of the appropriate ones” is selected.
  • Reflected light (hereinafter referred to as “recording layer”) generated by other recording layers other than the one recording layer (hereinafter referred to as “one return light” as appropriate). (Also called “stray light” as appropriate) is also contained at a high level. Therefore, for example, the SZN ratio of signal components such as playback signals may be reduced.
  • a signal component of one return light and a stray light component in a multilayer optical disc are in a trade-off relationship.
  • the stray light component can be lowered to a relatively low level to reduce the effect of stray light, but at the same time, the signal component of one return light is also reduced.
  • the level will be relatively low and the SZN ratio will also decrease.
  • the area of the light-receiving region is increased, it is possible to bring the signal component of one return light to a relatively high level. At the same time, the stray light component also becomes a relatively high level. The technical problem will be that the ratio will also decrease.
  • Non-Patent Document 1 describes a double-layer Blu-ray Disc.
  • the following describes a technique for avoiding the incidence of stray light to a light receiving element by separating the push-pull signal from the signal light by a hologram element in a tracking method during recording or reproduction.
  • Non-Patent Document 2 in order to reduce the influence of stray light contained in signal components from each recording layer of a multilayer information recording medium, it is fixed in a confocal optical system. It describes a technique for spatial filtering (spatial removal) using a pinhole.
  • Patent Document 1 a technique for separating reflected light from each recording layer with high accuracy by utilizing the difference in the angle of the optical axis of the return light of each recording layer force of a two-layer type optical disc. It is described.
  • Non-Patent Document 3 describes, for example, an optical pickup of a multi-layer information recording medium provided with a plurality of light receiving means respectively corresponding to orthogonal optical axes.
  • spot size focus control 1S beam size focus control
  • spot size type focus control will be described with reference to FIG. 11 and FIG.
  • a part of the signal light collected from the condenser lens 108 or 109 is received, for example, through a half mirror whose light transmittance and light reflectance are approximately 0.5.
  • the light is received by the unit (PD3).
  • the other part of the signal light is received by the light receiving part (PD4) through this half mirror.
  • the diameter of a part of the signal light applied to the light receiving unit PD3 and the signal light applied to the light receiving unit PD4 The light diameter of the other part is substantially equal.
  • the sum of the signal components of part of the signal light received in the region “3a” and the region “3c” and the other signal components of the signal light received in the region “4b” is
  • the width “d3” of the region “3b” and the region “4b” is defined so as to be substantially equal.
  • the signal irradiated to the light receiving unit PD3 When light is collected at a position away from the desired recording layer with reference to one direction of the optical axis, the signal irradiated to the light receiving unit PD3 The light diameter of a part of the light is smaller than the light diameter of the other part of the signal light irradiated to the light receiving part PD4.
  • spot size focus control is performed based on the signal component of the signal light.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2005-228436
  • Non-Patent Document 1 "Development of 1-beam tracking system suitable for double-layer Blu-ray disc” Matsushita Electric Industrial Co., Ltd. AV Core Technology Development Center Opto Device Group IEICE Technical Report CPM2005-149 ( 2005-10)) The Institute of Electronics, Information and Communication Engineers ⁇ 31-34
  • Non-Patent Document 2 "3D Multi-layer Bit Recording Memory” Yoshimasa Kawada (Faculty of Engineering, Shizuoka University) Laser Symposium 2005
  • Non-Special Reference 3 “SONY Experimental 3 ⁇ 4etup” ISOM (International Symposium on Optical Memory) Lecture 2004
  • Non-Patent Document 1 As shown in FIG. 10, in the light receiving element for receiving the focus error signal or the RF signal, stray light (“ (See the overlap between Stray light ”and“ Transmitted beam ”), and the SZN ratio of the signal component of the return light from the desired recording layer is reduced due to stray light. There will be technical problems.
  • Non-Patent Document 2 in a finite optical system including a confocal optical system, an optimum pinhole, for example, Z depending on the position of the recording layer or the position where tracking is performed, for example, Z Since the position in the axial direction changes, there arises a technical problem that it becomes difficult to appropriately spatially filter the influence of stray light.
  • the present invention has been made in view of, for example, the conventional problems described above.
  • an information recording medium such as a multilayer optical disk
  • data can be reproduced with higher accuracy while reducing the influence of stray light.
  • an optical pickup is an optical pickup that performs at least one of recording and reproduction of data on a recording medium including a plurality of recording layers, and a light source that irradiates laser light;
  • An optical system (such as an objective lens) that guides the laser beam to one of the plurality of recording layers, and the one recording layer when the guided laser beam is focused on the one recording layer.
  • An optical path of inner diameter light that is a portion near the center including the optical axis of the return light in the return light including the signal light reflected by the layer and the stray light reflected by the other recording layer among the plurality of recording layers;
  • An optical path branching unit for example, a prism having a reflective film only in a region irradiated with the inner diameter light
  • An optical path branching unit for branching an optical path of the outer diameter light that is an outer portion of the inner diameter light in the return light, and a reference direction
  • the laser light is guided to one recording track or one data pit row in the one recording layer.
  • Control Control means tilt control means
  • the laser light irradiated with the light source force under the control of the control means is emitted from a plurality of recording layers by an optical system such as an objective lens, a beam splitter, or a prism. It is led to one recording layer and condensed. At the same time, when the light is condensed on one recording layer, the signal light generated in the one recording layer is received by the first and second light receiving means. Therefore, the focused laser beam guided to one recording layer can reproduce data pit rows and marks formed on one recording layer. Therefore, it is possible to reproduce predetermined information from the recording medium. Alternatively, the focused laser beam can form data pit rows and marks in one recording layer. Therefore, it is possible to record predetermined information on the recording medium.
  • an optical system such as an objective lens, a beam splitter, or a prism. It is led to one recording layer and condensed.
  • the signal light generated in the one recording layer is received by the first and second light receiving means. Therefore, the focused laser beam guided to one recording layer can reproduce data pit rows and marks formed on one
  • the optical path branching unit generates the signal light generated in one recording layer and the other recording layer when the guided laser beam is collected in one recording layer.
  • the optical path of the inner diameter light that is a portion near the center including the optical axis of the return light, and the outer diameter light that is the outer portion of the inner diameter light in the return light and has a donut shape
  • the optical path is branched.
  • this optical path branching means for example, a prism having a reflective film only in a region irradiated with inner diameter light can be cited.
  • the branching between the inner diameter light and the outer diameter light is theoretical, empirical, experimental, or simulation depending on the optical properties or physical shape of the optical path branching means such as the size of the reflection film. It can be specified by.
  • the first light receiving means (PD1) has at least three regions along the reference direction, and is arranged so as to receive the outside-diameter light through these three regions.
  • the second light receiving means (PD2) has at least three regions along the reference direction, and is arranged to receive the inner diameter light through these three regions. That is, the first light receiving means includes a signal light generated in one recording layer at a relatively high level through at least three regions and a stray light generated in the other recording layer at a relatively low level. It is possible to receive light with an outside diameter included in.
  • the second light receiving means can receive the inner diameter light including the signal light generated in one recording layer and the stray light generated in the other recording layer through at least three regions.
  • the influence of stray light generated in other recording layers is noticeable based on the signal component of the outer diameter light received through at least three regions of the first light receiving means.
  • tracking control based on the push-pull method can be realized with high accuracy.
  • the effect of stray light generated in other recording layers is controlled based on the signal component of the inner diameter light received through at least three regions of the second light receiving means under the control of the control means.
  • By grasping quantitatively or qualitatively for example, by subtracting the signal component force of the outside light received by the first light receiving means by a level corresponding to the level of the signal component of stray light (cancelling the difference), etc. It is possible to actively use the effects of stray light. Therefore, based on the quantitative or qualitative understanding of stray light effects, the above-mentioned signal components have been improved based on the ideal signal components in signal light, that is, improved signal quality with little or no stray light effects.
  • a focus control based on a so-called spot size method for example, a beam size focus control can be realized with high accuracy.
  • the signal component may be at least one of an RF signal, a wobble signal, and an address signal (LPP).
  • the ideal signal component in the signal light can be obtained by quantitatively or qualitatively understanding the influence of stray light and actively using it.
  • the optical path branching unit has a reflective film on the optical path of the inner diameter light.
  • the optical path of the inner-diameter light and the optical path of the outer-diameter light that is an outer portion of the inner-diameter light are increased based on the optical property or physical shape of the reflective film. It is possible to branch to accuracy.
  • the reference direction is defined based on a radial direction of the recording medium (a direction for receiving a push-pull signal: a Rad direction).
  • the first light receiving means follows the reference direction.
  • the tracking control based on the push-pull method, for example, that significantly reduces the effects of stray light based on the signal component of the outer diameter light received through the regions at both ends of the three regions. It can be realized with higher accuracy.
  • the first light receiving means (PD1) is a first left region located side by side with the first central region (lb) as a center along the reference direction. (La) and the first right region (lc), the second light receiving means (PD2) is located along the reference direction and centered on the second center region (2b),
  • the control means (tracking control) has a second left region (2a) and a second right region (2c), and the control means (tracking control) receives the outer diameter light received in the first left region and the first right region. Based on the signal component, the optical system is controlled so that the laser beam is guided to the one recording track or the one data pit row.
  • the first light receiving means (PD1) includes the first left region (la) and the first left region located side by side with the first central region (lb) in the reference direction. It has a right region (lc), and is arranged so as to receive light of an outer diameter through the first central region, the first left region, and the first right region.
  • the second light receiving means (PD2) includes a second left region (2a) and a second right region (2c) that are arranged along the reference direction with the second central region (2b) as a center. And is arranged so as to receive the inner diameter light through the second central region, the second left region, and the second right region.
  • the first light receiving means includes a relatively high level of signal light generated in one recording layer via the first central region, the first left region, and the first right region, and the other recording layer. It is possible to receive outer diameter light that contains stray light generated at a relatively low level.
  • the second light receiving means includes an inner diameter including signal light generated in one recording layer and stray light generated in another recording layer via the second central region, the second left region, and the second right region. It is possible to receive light.
  • Another aspect of the optical pickup of the present invention includes (i) a signal component of the signal light included in the received outer diameter light, and (ii) included in the received inner diameter light.
  • Computation means for computing a difference from the signal component of the stray light is further provided, and the control means is based on the computed difference so as to guide the laser light to the one recording layer. Control the optical system.
  • the influence of the stray light is quantitatively or qualitatively controlled under the control of the control unit based on the difference between the signal component of the signal light and the signal component of the stray light calculated by the calculation unit.
  • the focus control described above in addition to the tracking control described above, based on the ideal signal component in the signal light, that is, the signal component with improved quality with little or no stray light effects. Can be realized with higher accuracy.
  • control means causes the laser light to be applied to the one recording layer based on a signal component of the signal light included in the received outer diameter light.
  • the optical system is controlled to guide.
  • the quality with almost or completely no influence of the stray light is improved under the control of the control means.
  • the above-described focus control can be realized with higher accuracy.
  • the first calculating means for calculating an RF signal included in the data based on a signal component of the outer diameter light received by the first light receiving means is further provided. Prepare.
  • the influence of the stray light generated in the other recording layer based on the signal component of the outer diameter light received by the first calculating means via the three regions of the first light receiving means It is possible to detect the RF signal appropriately while significantly reducing the noise.
  • the RF signal is calculated under the control of the control unit based on the difference between the signal component of the signal light and the signal component of the stray light calculated by the second calculation unit.
  • a predetermined coefficient is calculated.
  • the “predetermined coefficient” according to the present invention is a correction coefficient for grasping the influence of stray light quantitatively or qualitatively and correcting it in signal processing so as to reduce the influence of stray light.
  • the influence of the stray light is grasped quantitatively or qualitatively based on the predetermined coefficient calculated by the first calculation means, and an ideal signal component in the signal light, that is, , Improve quality with little or no stray light effects It is possible to achieve higher-precision RF signal calculations.
  • the control means (focus control) is: (i) Signals at both ends of the outer diameter light received by the first left region and the first right region The sum of the component and the signal component of the central portion of the inner diameter light received in the second central region, and (ii) the light received in the second left region and the second right region. Based on the sum of the signal components at both ends of the inner diameter light and the signal components at the center of the outer diameter light received by the first central region, the laser light is guided to the one recording layer. You may comprise so that an optical system may be controlled.
  • both end portions of the outer diameter light according to the present invention mean portions received in the first left region and the first right region of the outer diameter light of the donut shape.
  • the central portion of the inner diameter light according to the present invention is the second of the circular inner diameter light. It means the part that receives light in the central area.
  • the signal component of the return light including the outer diameter light and the inner diameter light can be used almost or completely.
  • both end portions of the inner diameter light according to the present invention mean portions received in the second left region and the second right region of the circular inner diameter light.
  • the signal component at the center of the outer diameter light received in the first central region the signal component of the return light including the outer diameter light and the inner diameter light can be used almost or completely.
  • the central portion of the outer diameter light according to the present invention means a portion of the outer diameter light of the donut shape that is received by the first central region.
  • the width (dl) in the reference direction of the first central region is (i) when the first central layer is focused on the first recording layer.
  • beam size focus control that is, focus control based on the so-called spot size method, can be realized with higher accuracy based on the signal component of the signal light with almost no loss of light amount.
  • the width of the second central region in the reference direction is (i) when the light is condensed on the one recording layer, the light is received by the second central region.
  • beam size focus control that is, focus control based on the so-called spot size method, can be realized with higher accuracy based on the signal component of the signal light with almost no loss of light amount.
  • the first light receiving means and the second light receiving means are a condensing condensing point when the laser light is condensed on the first recording layer.
  • the optical distance is the same relative to the position.
  • the conjugate light condensing in the first light receiving means and the second light receiving means can be realized with higher accuracy based on a positional relationship in which optical distances are equal with respect to a point position.
  • the width of the first central region in the reference direction is the light diameter of the outer diameter light when condensed on the one recording layer.
  • the inner diameter light may be defined so as to be substantially equal to the width of the second central region in the reference direction.
  • the light diameter of the outer diameter light and the light diameter of the inner diameter light are approximately equal, and in some cases, based on the first center area and the second center area having substantially the same width in the reference direction.
  • beam size focus control that is, focus control based on a so-called spot size method
  • the “light diameter” according to the present invention means a physical length such as a diameter (or radius) that can be measured based on the optical axis of the laser light.
  • this “light diameter” is uniquely defined based on optical characteristics (for example, optical magnification, diffraction angle, principal point position, focal length, etc.) in other optical systems such as a condenser lens. Make sure that you are determined.
  • the width of the first central region in the reference direction is the amount of light received by the outer diameter light received in the first central region.
  • a light receiving amount of the outer diameter light received by the first left region and the first right region is defined to be substantially equal, or (ii) the reference direction of the second central region ,
  • the received light amount of the inner diameter light received in the second central region is substantially equal to the received light amount of the inner light received in the second left region and the second right region. It may be configured to be defined as follows.
  • the focus is based on, for example, beam size focus control, so-called spot size method, based on the first center region and the second center region whose width is defined by the amount of received light described above. Control can be realized with higher accuracy.
  • an information device of the present invention irradiates the recording medium with the above-described optical pickup of the present invention (including various aspects thereof), and the laser beam.
  • Recording / reproducing means for recording or reproducing the data are included in the recording medium.
  • data is recorded on the recording medium or data recorded on the recording medium while enjoying the same benefits as the various benefits of the optical pickup of the present invention described above. Can be played.
  • the optical pickup of the present invention includes a light source, an optical system, an optical path branching unit, a first light receiving unit, a second light receiving unit, and a control unit.
  • the effects of stray light can be grasped quantitatively or qualitatively and actively used, so that the ideal signal component in signal light, that is, stray light Signal components with improved quality with little or no effect can be calculated, and data can be played back or recorded with higher accuracy when playing back or recording on multi-layered recording media. Is possible.
  • the information device of the present invention includes a light source, an optical system, an optical path branching unit, a first light receiving unit, a second light receiving unit, a control unit, and a recording / reproducing unit.
  • a light source an optical system
  • an optical path branching unit a first light receiving unit
  • a second light receiving unit a control unit
  • a recording / reproducing unit a recording / reproducing unit.
  • FIG. 1 is a block diagram showing the basic configuration of an information recording / reproducing apparatus and a host computer according to an embodiment of the information recording apparatus of the present invention.
  • FIG. 2 is a block diagram schematically showing a more detailed configuration of the pickup 100 in the information recording / reproducing apparatus 300 in the example.
  • FIG. 3 is a cross-sectional view on the optical axis that schematically shows the arrangement of the prism and the light receiving portion of the optical pickup according to the present embodiment, and schematically shows the light receiving surface of the light receiving portion. It is a top view.
  • FIG. 4 The light-receiving surface of the light-receiving unit and the tracking included in the optical pickup according to the present embodiment. It is a top view which shows control notionally.
  • FIG. 5 is a plan view conceptually showing a light receiving surface of a light receiving unit and focus control included in the optical pickup according to the present embodiment.
  • FIG. 6 is a plan view on the optical axis conceptually showing the relative positional relationship between the light receiving unit PD1 and the focal point position, and the light receiving unit, included in the optical pickup according to the present embodiment.
  • FIG. 6 is a plan view schematically showing the light diameter on the light receiving surface.
  • FIG. 7 is a plan view on the optical axis conceptually showing the relative positional relationship between the light receiving unit PD2 and the focal point position of the optical pickup according to the present embodiment, and the light receiving unit.
  • FIG. 6 is a plan view schematically showing the light diameter on the light receiving surface.
  • FIG. 8 Another specific example of the light receiving surface of the light receiving unit included in the optical pickup according to the present embodiment.
  • FIG. 9 is a schematic plan view (FIG. 8 (a), FIG. 8 (b) and FIG. 8 (c)).
  • FIG. 9 is a plan view schematically showing a specific example of the divided light receiving surface of the light receiving unit included in the optical pickup according to the present embodiment.
  • FIG. 10 is a plan view of a light receiving means according to a comparative example.
  • FIG. 11 is a cross-sectional view on the optical axis schematically showing the arrangement of the prism and the light receiving unit in the optical pickup that performs the focus control of the beam size method according to the general example, and the light receiving by the light receiving unit. It is a top view which shows a surface typically.
  • FIG. 12 A plan view on the optical axis conceptually showing the relative positional relationship between the light receiving unit and the focal point position in the optical pickup that performs focus control of the beam size method according to the general example.
  • FIG. 4 is a plan view schematically showing a light diameter on a light receiving surface of a light receiving unit.
  • the present embodiment is an example in which the information recording apparatus according to the present invention is applied to an information recording / reproducing apparatus for an optical disc.
  • FIG. 1 is a block diagram showing the basic configuration of the information recording / reproducing apparatus and the host computer according to the embodiment of the information recording apparatus of the present invention.
  • the information recording / reproducing apparatus 300 has a function of recording recording data on the optical disk 10 and a function of reproducing recording data recorded on the optical disk 10.
  • the information recording / reproducing apparatus 300 is an apparatus that records information on the optical disc 10 and reads information recorded on the optical disc 10 under the control of a CPU (Central Processing Unit) 314 for driving.
  • a CPU Central Processing Unit
  • the information recording / reproducing apparatus 300 includes an optical disc 10, an optical pickup 100, a signal recording / reproducing unit 302, an address detecting unit 303, a CPU (drive control unit) 314, a spindle motor 306, a memory 307, and a data input / output control unit 308. , And a bus 309.
  • the host computer 400 includes a CPU (host control means) 401, a memory 402, an operation control means 403, an operation button 404, a display panel 405, a data input / output control means 406, and a bus 407.
  • the CPU host control means
  • the information recording / reproducing apparatus 300 is a host combination equipped with a communication means such as a modem.
  • the user 400 may be configured to be able to communicate with an external network by being housed in the same casing.
  • the CPU (host control means) 401 of the host computer 400 provided with communication means such as i-link directly controls the information recording / reproducing apparatus 300 via the data input / output control means 308 and the bus 309. By doing so, you may be able to communicate with an external network.
  • the optical pickup 100 performs recording / reproduction with respect to the optical disc 10 and includes a semiconductor laser device and a lens. More specifically, the optical pickup 100 irradiates the optical disc 10 with a light beam such as a laser beam at a first power as read light during reproduction, and modulates with a second power as write light at the time of recording. Irradiate.
  • the signal recording / reproducing means 302 records or reproduces the optical disc 10 by controlling the optical pickup 100 and the spindle motor 306. More specifically, the signal recording / reproducing means 302 is constituted by, for example, a laser diode driver (LD dry type) and a head amplifier.
  • the laser diode driver drives a semiconductor laser (not shown) provided in the optical pickup 100.
  • the head amplifier amplifies the output signal of the optical pickup 100, that is, the reflected light of the light beam, and outputs the amplified signal.
  • the signal recording / reproducing means 302 determines the optimum laser power by the OPC pattern recording and reproduction processing together with a timing generator (not shown) under the control of the CPU 314 during the OPC (Optimum Power Control) processing.
  • a semiconductor laser (not shown) provided in the optical pickup 100 is driven so that it can be performed.
  • the signal recording / reproducing means 302, together with the optical pickup 100 constitutes an example of the “recording / reproducing means” according to the present invention.
  • the address detection unit 303 also detects an address (address information) on the optical disc 10 for the reproduction signal power output by the signal recording / reproducing means 302, for example, including a pre-format address signal.
  • a CPU (drive control means) 314 controls the entire information recording / reproducing apparatus 300 by giving instructions to various control means via the bus 309. Note that software or firmware for operating the CPU 314 is stored in the memory 307. In particular, the CPU 314 constitutes an example of “control means” according to the present invention.
  • the spindle motor 306 rotates and stops the optical disc 10, and Works on access. More specifically, the spindle motor 306 is configured to rotate and stop the optical disc 10 at a predetermined speed while receiving spindle servo from a not-shown servo unit or the like.
  • the memory 307 includes general data processing and OPC in the information recording / reproducing device 300, such as a buffer area for recording / reproducing data and an area used as an intermediate buffer for conversion to data used by the signal recording / reproducing means 302. Used in processing.
  • the memory 307 has 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, a variable necessary for the operation of the firmware program, and the like.
  • the RAM area to be stored is configured.
  • the CPU (host control means) 401, the memory 402, the data input / output control means 406, and the bus 407 are substantially the same as the corresponding components in the information recording / reproducing apparatus 300. It is.
  • the CPU 401 displays the operation state of the information recording / reproducing apparatus 300 on the display panel 405 such as a fluorescent tube or LCD via the operation control means 403.
  • the display panel 405 such as a fluorescent tube or LCD
  • Can output One specific example of using the information recording / reproducing apparatus 300 and the host computer 400 in combination as described above is a household device such as a recorder device that records and reproduces video.
  • This recorder device is a device that records video signals from broadcast receiver tuners and external connection jacks on a disc, and outputs the video signals reproduced from the disc to an external display device such as a television.
  • the program stored in the memory 402 is executed by the CPU 401 to operate as a recorder device.
  • the information recording / reproducing apparatus 300 is a disk drive (hereinafter referred to as a drive as appropriate)
  • the host computer 400 is a personal computer workstation.
  • the host computer such as a personal computer and the drive are connected via SCSI / ATAPI data input / output control means 308 (406), and the application such as writing software installed in the host computer controls the disk drive. To do.
  • FIG. 2 is a block diagram conceptually showing a more detailed structure of the optical pickup 100 included in the information recording / reproducing apparatus 300 in the example.
  • the optical pickup 100 includes a semiconductor laser 101, a condensing lens 103, a polarizing beam splitter 105, a reflecting mirror 106, a 1Z4 wavelength plate 107, a condensing lens 108, and a concentrating lens.
  • the optical lens 109, the prism 110, the light receiving parts PD1 and PD2, and the light receiving part PD2 are provided. Therefore, the laser beam LB is emitted from the semiconductor laser 101 in the following order, and is received by the light receiving unit PD1 and the like through each element.
  • the laser beam emitted from the semiconductor laser 101 when guided to the L1 layer of the optical disc that is, the recording layer on the near side as viewed from the irradiation side of the laser beam LB) as the so-called outgoing path.
  • the LB is guided to the L1 layer via the condenser lens 103, the polarization beam splitter 105, the reflection mirror 106, the 1Z4 wavelength plate 107, and the condenser lens 108.
  • the laser beam LB reflected on the L1 layer passes through the condenser lens 108, 1Z4 wavelength plate 107, reflection mirror 106, polarization beam splitter 105, condenser lens 109, and prism 110. Via the light receiver PD1 and PD2. Is done.
  • the optical path of the laser beam LB with respect to the L2 layer (that is, the recording layer on the back side as viewed from the irradiation side of the laser beam LB) is almost the same.
  • the condensing lenses 103, 108 and 109, the polarizing beam splitter 105, the reflecting mirror 106, and the 1 Z4 wavelength plate 107 constitute a specific example of the optical system according to the present invention.
  • the prism 110 constitutes one specific example of the optical path branching unit according to the present invention.
  • the light receiving portions PD1 and PD2 constitute one specific example of the first and second light receiving means according to the present invention.
  • the semiconductor laser 101 emits the laser light LB, for example, in an elliptical light emission pattern that spreads in the vertical direction compared to the horizontal direction.
  • the condensing lens 103 makes the incident laser beam LB substantially parallel light and enters the polarized beam splitter 105.
  • the polarization beam splitter 105 is an optical element that branches the optical path based on the polarization direction. Specifically, the laser beam LB having one polarization direction is transmitted with little or no light loss, and is incident from the optical disk side, and the polarization direction is the other direction. A certain laser beam LB is reflected with little or no light loss. The reflected light reflected by the polarization beam splitter 105 is received by the light receiving parts PD1 and PD2 via the condenser lens 109 and the prism 110.
  • the reflection mirror 106 reflects the laser beam LB with little or no loss of light amount.
  • the 1Z4 wavelength plate 107 converts a linearly polarized laser beam into a circularly polarized light or converts a circularly polarized laser beam into a linearly polarized light by giving a phase difference of 90 degrees to the laser light. Is possible.
  • the condensing lens 108 condenses the incident laser beam LB and irradiates it on the recording surface of the optical disc 10.
  • the condensing lens 108 is configured to include, for example, an actuator unit, and has a drive mechanism for changing the arrangement position of the condensing lens 108. More specifically, the actuator unit can focus on the L1 layer and the L2 layer of the optical disc by moving the position of the objective lens 108 in the focus direction.
  • the condensing lens 109 condenses the reflected light reflected by the polarization beam splitter 105.
  • the prism 110 when the laser beam is condensed on the L1 layer, the prism 110 has an optical axis in the return light including the signal light generated in the L1 layer and the stray light generated in the L2 layer.
  • the optical path of the inner diameter light that is the inner portion of the boundary surface defined based on the predetermined distance and the optical path of the outer diameter light that is the outer portion of the boundary surface are branched.
  • the light receiving unit PD1 receives the inner diameter light, and the light receiving unit PD2 receives the outer diameter light.
  • FIG. 3 is a cross-sectional view on the optical axis that schematically shows the arrangement of the prism and the light receiving unit included in the optical pickup according to the present embodiment, and the light receiving surface of the light receiving unit.
  • FIG. 4 is a plan view conceptually showing the light receiving surface of the light receiving unit and tracking control included in the optical pickup according to the present embodiment.
  • the prism 110 is arranged adjacent to the condenser lens 109 and the light receiving parts PD1 and PD2.
  • the light receiving unit PD1 includes a region “la”, a region “lb”, and a region “lc” along a reference direction corresponding to the radial direction of the optical disc.
  • the light receiving unit PD2 is configured to include a region “2a”, a region “2b”, and a region “2c” along the reference direction corresponding to the radial direction of the optical disc.
  • the prism 110 for example, in the case where the laser light is condensed on the L2 layer of the plurality of recording layers, in the return light including the signal light generated in the L2 layer and the stray light generated in the L1 layer
  • the optical path of the inner diameter light which is the portion near the center including the optical axis of the return light
  • the optical path of the outer diameter light which is the outer portion of the inner diameter light in the return light
  • This prism may be a prism with a reflective film only in the region irradiated with the inner diameter light.
  • the branching between the inner diameter light and the outer diameter light is theoretical, empirical, experimental, or depending on the optical properties or physical shape of the light branching means such as the size of the reflective film. It can be defined by simulation or the like.
  • the prism 110 has a reflection film of a predetermined size on the internal optical path, and the inner diameter light can be branched by this reflection film and received by the light receiving unit PD2.
  • the inner diameter light is signal light generated in the L2 layer (see the large dotted line in Fig. 3) and stray light generated in the L1 layer (thick solid line in Fig. 3). Included).
  • the outer diameter light includes signal light generated in the L2 layer (see the large dotted line in Fig. 3) at a relatively high level, and stray light generated in the L1 layer at a relatively low level. Including.
  • the small dotted line of dots in Fig. 3 indicates the inner diameter light that is not received by the light receiving unit PD1.
  • Tracking control is performed based on the tracking error signal that is the difference between the two. Specifically, a tracking error signal is detected based on the following equation (1).
  • the tracking error signal is received by (i) the signal component of the outside light received in the region “la” of the light receiving unit PD1, and (ii) received by the region “lc” of the light receiving unit PD1. It is the difference from the value of the signal component of the outer diameter light. Specifically, based on the value of the tracking error signal, the irradiated laser beam (laser beam) can be moved along the radial direction of the optical disc in the outer circumferential direction or the inner circumferential direction. Is possible.
  • the light receiving unit PD1 includes the signal light generated in the L2 layer at a relatively high level via the region “la”, the region “lb”, and the region “lc”. It is possible to receive outer diameter light that contains stray light generated at a relatively low level.
  • the light receiver PD 2 receives the inner diameter light including the signal light generated in the L2 layer and the stray light generated in the L1 layer via the region “la”, the region “lb”, and the region “lc”. Is possible.
  • the L1 layer Tracking control based on, for example, the push-pull method, in which the influence of the generated stray light is significantly reduced, can be realized with high accuracy.
  • the influence of stray light generated in the L1 layer is quantitatively or qualitatively determined based on the signal component of the inner diameter light received by the light receiving unit PD2, for example, Only the level corresponding to the level of the stray light signal component is affected by the stray light by subtracting (cancelling the difference) the signal component force of the outside light received by the light receiving unit PD1. Can be actively used.
  • the signal component may be at least one of an RF signal, a wobble signal, and an address signal (LPP).
  • LPP address signal
  • FIG. 5 is a plan view conceptually showing the light receiving surface of the light receiving unit and the focus control included in the optical pickup according to the present embodiment.
  • the control means such as CPU (i) receives the signal component of the outside light received in the region “la” and the region “lc”, and the light component in the region “2b”. And (ii) the signal component of the inner diameter light received in the region “2a” and the region “2c” and the outer diameter received in the region “lb”. Based on the sum of the signal components of the light, an optical system such as an objective lens is controlled so that the laser light is guided to a desired recording layer. In particular, focus control is performed on the basis of a signal having a relatively low frequency band compared to tracking control. Therefore, even if the signal component of the inner diameter light is used, the effect of stray light is almost or completely eliminated. I also add that I can say that there is no such thing.
  • FIG. 6 is a plan view on the optical axis that conceptually shows the relative positional relationship between the light receiving unit PD1 and the light collecting point position of the optical pickup according to the present embodiment, and It is a top view which shows typically the light diameter on the light-receiving surface of a light-receiving part.
  • the light receiving part PD2 in Fig. 6 Corresponds to the above-described regions “2a”, “2b”, and “2c” and has regions that have the same width as the regions “la”, “lb”, and “lc” in the light receiving unit PD1, respectively. The description is tentatively described as regions “2 ax”, “2bx”, and “2cx”.
  • the relationship is approximately equal to the sum of the signal component of the outer diameter light and the light diameter of the outer diameter light irradiated to the light receiving unit PD1 and the light receiving unit.
  • the light diameter of the outer diameter light irradiated on PD2 is substantially equal, and the focus error signal is zero, specifically, the sum of (i) described above is received in the region “la”.
  • the signal component at the left end of the outer diameter light see the black part in the middle of Fig. 6) and the signal component at the right end of the outer diameter light received in the area "lc" (the black part at the middle in Fig.
  • the area of the black part in the lower part of Fig. 6 is larger than the area of the shaded part.
  • the light diameter of the outer diameter light irradiated to the light receiving portion PD1 is larger than the light diameter irradiated to the light receiving portion PD2.
  • FIG. 7 is a plan view on the optical axis conceptually showing the relative positional relationship between the light receiving unit PD2 and the light collecting point position, which is included in the optical pickup according to the present embodiment, and It is a top view which shows typically the light diameter on the light-receiving surface of a light-receiving part.
  • the width “d2” of the region “2b” of the light receiving unit PD2 it is preferable that the following relationship is established. That is, as shown in the middle part of FIG. 7, when the light is condensed on a desired recording layer, (0 the signal component of the inner diameter light received in the region “2b”, the region “lax”, and the region “lcx” And (ii) the inner diameter light received in the region “2a” and the region “2c”. It is preferable that the relationship that is substantially equal to the sum of the signal component of the inner diameter light and the signal component of the inner diameter light received in the region “lbx” is established.
  • the light diameter of the inner diameter light irradiated on the light receiving portion PD2 is substantially equal to the light diameter of the inner diameter light irradiated on the light receiving portion PD1, and the focus error signal is zero. It is. Specifically, the sum of (i) described above is received by the signal component at the center of the inner diameter light received in the region “2b” (see the black portion in the middle of FIG. 7) and received by the region “lax”. The signal component at the left end of the inner diameter light (see the middle black area in Fig. 7) and the signal component at the right end of the inner diameter light received in the region "lcx" (see the middle black area in Fig. 7) ).
  • the sum of (ii) described above is the signal component at the left end of the inner diameter light received in the region “2a” (see the hatched portion in the middle of FIG. 7) and the light received in the region “2c”.
  • the signal component at the right end of the inner diameter light (see the middle hatched area in Fig. 7) and the signal component at the center of the inner diameter light received in the region "lbx" (see the middle hatched area in Fig. 7)
  • the sum In other words, if the middle part of FIG. 7 is interpreted with the amount of light corresponding to the area, it can be said that the area of the black part in FIG. 7 and the area of the hatched part are substantially equal.
  • the width “d2” of the region “2b” of the light receiving unit PD2 is determined as described above, as shown in the lower part of FIG. (I)
  • the influence of stray light is remarkably reduced by using the signal component of the outer diameter light received in the region “la” and the region “lc”.
  • the signal component of the inner diameter light received in the region “2b” the signal component of the return light including the outer diameter light and the inner diameter light can be used almost or completely.
  • the signal light generated in the desired recording layer and the stray light generated in the other recording layers are obtained by using the signal components of the inner diameter light received in the region “2a” and the region “2c”. It is possible to receive the inner diameter light including the light with little or no loss of light quantity.
  • the signal component of the outside light received in the region “lb” the signal component of the outside light and the return light including the inside light can be used almost or completely. is there.
  • beam size focus control so-called spot size, based on the signal component of the signal light with little or no loss of light quantity. Focus control based on the method can be realized with higher accuracy.
  • FIG. 8 is a plan view schematically showing another specific example of the light receiving surface of the light receiving unit included in the optical pickup according to the present embodiment (FIGS. 8A and 8B). ) And Figure 8 (c)).
  • FIG. 9 shows the divided light receiving surface of the light receiving unit in the optical pickup according to the present embodiment. It is a top view which shows a specific example typically.
  • the width “dl” of the region “lb” in the reference direction such as the radial direction of the optical disc is the desired recording width.
  • the width “d2” in the reference direction of the region “2b” is approximately equal. Even so,
  • the beam size Focus control based on the so-called spot size method can be realized with higher accuracy.
  • the width of the region “lb” in the reference direction is the outer width received by the region “lb” when the light is condensed on a desired recording layer.
  • the light reception amount of the radial light and the light reception amount of the outer diameter light received in the region “la” and the region “lc” may be defined to be substantially equal.
  • the width in the reference direction of the region “2b” is the amount of light received by the inner diameter light received by the region “2b” and the amount of light received by the inner diameter light received by the regions “2a” and “2c”. It may be stipulated to be approximately equal.
  • the beam size focus control that is, the focus control based on the so-called spot size method is further enhanced. It is possible to realize with accuracy.
  • the light receiving unit PD1 may be divided into a larger number of regions based on the three divided regions “la”, “lb”, and “lc”. That is, as shown in the second row of FIG. 9, the region “lb” may be divided into a region “lbr” and a region “lbl” in the left-right direction, and may be divided into four in total.
  • the received light amount of the outer diameter light received in the region “lbr” and the region “lbl” is substantially equal to the received light amount of the outer diameter light received in the region “la” and the region “lc”. It may be specified as follows.
  • the region “la” force is divided into the region “1 & 1:” and the region “lal” in the horizontal direction, and the region “lc” is
  • the area “lcr” and the area “lcl” may be divided into a total of five.
  • the received light amount of the outer diameter light received in the region “lb” and the received light amount of the outer diameter light received in the region “lar”, the region “lal”, the region “lcr”, and the region “lcl”. May be defined to be substantially equal.
  • the region “la” force is divided into the region “la r” and the region “lal” in the left-right direction, and the region “lb”
  • the region “lbr” and the region “lbl” may be divided in the direction
  • the region “lc” may be divided into the region “lcr” and the region “lcl” in the left-right direction, for a total of six.
  • the amount of received light may be defined to be substantially equal. More specifically, regarding the number of such divisions, if a predetermined calculation defined based on the number of divisions is performed after receiving light, theoretically, empirically, experimentally, or by simulation, etc. Individual and specific decisions can be made.
  • the light receiving part PD2 can be divided in substantially the same manner.
  • the shape of the region “lb” is centered on the optical axis of the light diameter “R” of the outer diameter light when condensed on the desired recording layer. It may be a circle. Further, the shape of the region “2b” may be a circular shape centering on the optical axis of the light diameter “r” of the inner diameter light when condensed on a desired recording layer.
  • beam size focus control that is, focus control based on a so-called spot size method can be realized with higher accuracy based on the same circular shape as the light diameter.
  • a BD Blu-ray Disc
  • a DVD Blu-ray Disc
  • a DVD may be reproducible by corresponding to a blue laser and a red laser. Or, based on 3 beams! /, So that you can play CDs.
  • the present invention is not limited to the above-described embodiments, and the entire specification can be changed as appropriate without departing from the gist or concept of the invention which can be read, and an optical pickup with such a change.
  • information devices are also included in the technical scope of the present invention.
  • the optical pickup and the information device according to the present invention are used for an optical pickup that irradiates a laser beam when data is recorded or reproduced on an information recording medium such as a DVD. Further, it can be used for an information device including the optical pickup.

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  • Optics & Photonics (AREA)
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Abstract

Dispositif de saisie optique (100) équipé comme suit: (i) source lumineuse fournissant un faisceau laser, (ii) système optique (108 ou autre) guidant le faisceau produit sur une couche d'enregistrement appartenant à une pluralité de couches d'enregistrement, (iii) système de division de trajet lumineux, pour la division de lumière de retour, qui comprend de la lumière de signal produite dans une couche d'enregistrement et de la lumière parasite produite dans une autre couche d'enregistrement, en un trajet lumineux pour la lumière de diamètre interne au niveau d'une partie proche du centre et un trajet optique pour la lumière de diamètre externe au niveau d'une partie extérieure à la lumière de diamètre interne, (iv) premier système de réception lumineuse (PD1) mis en place pour recevoir la lumière de diamètre externe (v) second système de réception lumineuse (PD2) mis en place pour recevoir la lumière de diamètre interne, et (vi) système de contrôle (3124 ou autre) permettant de contrôler un système optique pour guider le faisceau laser vers une piste d'enregistrement ou une rangée de puits de données, sur la base de la lumière de diamètre externe reçue et de la lumière de diamètre interne.
PCT/JP2007/057282 2006-03-31 2007-03-30 Dispositif de saisie optique et d'information WO2007114389A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010211843A (ja) * 2009-03-09 2010-09-24 Hitachi Media Electoronics Co Ltd 光ピックアップ装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002015439A (ja) * 2000-06-29 2002-01-18 Sony Corp 光ディスクドライブおよびそれにおけるフォーカスオフセットキャリブレーション方法
JP2005317161A (ja) * 2004-04-30 2005-11-10 Sharp Corp 光ピックアップユニットおよびそれを備えた光ピックアップ装置、情報記録／再生装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002015439A (ja) * 2000-06-29 2002-01-18 Sony Corp 光ディスクドライブおよびそれにおけるフォーカスオフセットキャリブレーション方法
JP2005317161A (ja) * 2004-04-30 2005-11-10 Sharp Corp 光ピックアップユニットおよびそれを備えた光ピックアップ装置、情報記録／再生装置

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010211843A (ja) * 2009-03-09 2010-09-24 Hitachi Media Electoronics Co Ltd 光ピックアップ装置

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