JP2013186914A - Optical disk, layer discrimination information recording method, layer discrimination method, and recording and playback device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grooveless disk medium capable of accurately performing layer discrimination by easily forming a pattern for enabling layer discrimination in each recording layer before recording data on a recording layer of a disk, a recording and playback method and a recording and playback device.SOLUTION: In an optical disk having a plurality of recording layers without the presence of a guide groove structure and a guide layer having a guide groove structure, a layer discrimination pattern capable of discriminating a recording layer is recorded at a predetermined position of at least one of the innermost peripheral side and the outermost peripheral side of each recording layer. Further, the layer discrimination pattern is made to be a repeated pattern having a different period in each recording layer, and layer discrimination is performed from the period of a signal obtained by scanning this area with a light spot.

Description

  The present invention relates to an optical disc that reproduces information from or records information on an optical disc using a laser, a method for discriminating a recording layer of the optical disc, and a recording / reproducing apparatus for the optical disc.

  As background art, there exists patent document 1, for example. The abstract of Patent Document 1 describes, as a problem, “to provide a multilayer optical information recording medium having tilt stability equivalent to that when the number of recording layers is small without causing a reduction in recording capacity”. Has been. As a solution, “two-photon absorption corresponding to light (blue light) having a guide track layer S corresponding to light (red light) having a wavelength in the range of 390 nm to 420 nm and light having a wavelength in the range of 650 nm to 680 nm”. A layer including an information layer M having a plurality of recording layers made of material is taken as one unit, and a plurality of units (U1, U2, U3) are sequentially stacked on the cover layer C. In this way, the guide track layer Since the S and the information layer M correspond to light of different wavelengths, the servo control can be performed in the same manner as when the number of recording layers is small without causing a reduction in recording capacity. " ing.

JP 2007-200427

  In recent years, in order to increase the recording capacity in the Blu-ray Disc (TM) standard optical disc, an optical disc having three or four recording layers has been developed and standardized. In the future, it is expected that an optical disc having a larger number of recording layers will be developed for the purpose of further increasing the capacity.

  In the above-mentioned Patent Document 1, a layer having a physical groove structure (hereinafter referred to as a guide layer) for performing tracking servo control is provided, and an optical disc that does not have a land / groove structure in a recording / reproducing layer (recording layer) (Grooveless disc) is shown, and even when a large number of recording layers are laminated, the manufacture is facilitated.

  On the other hand, in the conventional recording type optical disc, address information can be acquired even in an unrecorded state by detecting a minute meandering amount of the guide groove of the recording layer and a prepit. Since there is no guide groove or pre-pit, address information cannot be obtained from an unrecorded recording layer.

On the other hand, Patent Document 1 discloses that “the reproduction signal processing circuit 2 is based on the output signal (a plurality of photoelectric conversion signals) of the light receiver PD1 and addresses information, synchronization information, focus error signal, track error signal, etc. Is acquired (paragraph 0068). Here, “PD1” is indicated as “a photodetector that receives light reflected from the guide layer” (paragraph 0123).
When recording a grooveless disc as described above, the address information can be referred to in the disc before the data is recorded on the recording layer in order to determine the recording layer on which the recording layer laser beam is focused. Therefore, there is a possibility that data is recorded while focusing on the wrong layer.

  Therefore, in the present invention, before recording data on the recording layer of the disc, a grooveless disc medium capable of easily forming a pattern capable of layer discrimination on each recording layer and accurately performing layer discrimination, An object is to provide a recording / reproducing method and a recording / reproducing apparatus.

  The above problem is solved by, for example, the invention described in the claims.

  According to the present invention, it is possible to accurately determine the layer of a grooveless disc.

Outline of optical disk according to the present invention Block configuration showing one embodiment of an optical disc apparatus according to the present invention Structure of optical disk according to the present invention Processing flow of optical disc device 101 when optical disc 102 is inserted Detailed configuration of controller Cross-sectional view of the area where layer discrimination information is recorded Layer identification information recording process flow Layer discrimination pattern and layer discrimination signal Example of playback signal spectrum for a single recording pattern Block configuration showing a first embodiment of the layer discrimination means Outline of the operation of the first embodiment of the layer discrimination means Second example of outline of optical disc according to the present invention Second example of layer discrimination pattern Sectional drawing of the optical disk of the periphery in which the layer discrimination | determination information in Example 3 is recorded Recording processing flow of layer discrimination information in embodiment 3 Block configuration of layer discriminating means in embodiment 4 Block configuration of layer discrimination reference signal generating means in embodiment 4 Block configuration of an example of quadrature detection means in the fourth embodiment Block configuration of layer discriminating means in embodiment 5 Processing Flow of Microprocessor in Embodiment 5 Layer discrimination pattern and layer discrimination signal in embodiment 6

(Outline)
In the embodiment described below, an optical disc having both a guide layer having a track (guide groove) structure that has an annular shape and a spiral shape with respect to the center, and a recording layer that does not have a track structure, For such an optical disc, the recording layer is irradiated with laser light according to the recording data while tracking the guide groove of the guide layer, so that the same spiral arrangement as the guide groove of the guide layer is formed on the recording layer. The present invention relates to an optical disk recording apparatus and an optical disk recording method for performing recording by forming a recording mark row.

  In the optical disc as described above, since the guide groove structure does not exist in the recording layer of the disc, the address information obtained from the guide groove of the recording layer in the past cannot be obtained from the unrecorded area of the recording layer. For this reason, it is difficult to identify which recording layer is the focused recording layer.

  Therefore, in the following embodiments, user data is recorded for the first time with layer discrimination information that enables discrimination of the focused recording layer at a predetermined position on at least one of the innermost and outermost sides of each recording layer. It was decided to perform the recording process before this.

  In addition, when the layer discrimination information itself is recorded, it is in an unrecorded state and the layer discrimination using the layer discrimination information cannot be performed. However, at this time, the layer discrimination information should be recorded by correctly focusing on the target layer. The invention has been devised with respect to the possible radial dimensions of each recording layer, the radial position of movement to another recording layer, and the order of recording on each recording layer. The main points are the following three points.

  First, with respect to the dimensions of each recording layer of the optical disc to which the present invention is applied, the radius on the side for recording the layer discrimination information among the inner radius and the outer radius is different for each recording layer. Here, it is assumed that the layer discrimination information is recorded on the inner circumference side, the names of the respective recording layers are L0, L1, L2,..., Lm in ascending order of the inner radius, and the inner radii of the respective recording layers are r0, r1. , r2,..., rm (r0 <r1 <r2,... rm-1 <rm).

  Second, the radius position when moving to another recording layer in the recording process of the layer discrimination information is determined between the inner radius of the recording layer to be moved and the next smaller inner radius. If the recording layer of the movement destination is Ln, it corresponds to the range from radius rn + 1 to radius rn. Also, address information indicating the position of the board surface is recorded on the guide layer, and when moving the recording layer, the recording layer is moved after moving the radial position according to the address information recorded on the guide layer. I will do it.

  Third, the order of the recording layers for recording the layer discrimination information is L0, L1, L2,..., Lm according to the order of decreasing inner radius. Further, the boundary position on the inner circumference side of the area for recording the layer discrimination information gives different dimensions depending on the recording layer, and the layer discrimination information to be recorded on the Ln layer which is the recording layer having the n + 1th smallest inner radius is It is determined to be provided between the inner radius rn and the next smallest inner radius rn + 1. Further, the boundary position on the outer peripheral side is set to be on the outer peripheral side with respect to the radius Ro determined on the outer peripheral side with respect to rm (maximum inner radius in all recording layers) in any recording layer.

  When recording processing of the layer discrimination information according to the above three conditions is performed, the recording layer existing at the radial position where the interlayer movement is performed, the recording layer of the moving target which is in an unrecorded state, and the layer discrimination information are already recorded. It is only one of the recording layers other than the moving target. Therefore, by determining whether or not the recording layer at the transfer destination is unrecorded, it is possible to determine the success or failure of the movement to the recording layer that is the transfer target. Further, when the recording layer moves to a recording layer other than the target, it is possible to determine the recording layer as the movement destination.

  Further, the layer discrimination information is a repetitive pattern having a different period for each recording layer. Peak detection of the spectrum of the signal obtained by detecting the return light intensity from the repetitive pattern is possible without tracking servo. For example, even when the tracking servo is not adjusted, the recording layer can be identified. it can.

  Below, the detail of embodiment of this invention is demonstrated based on drawing.

(Details of the embodiment of the present invention)
FIG. 2 is a block diagram showing an embodiment of the optical disc apparatus according to the present invention.

  The optical disc device 101 records or reproduces information by irradiating an optical disc 102 mounted on the device with laser light, and communicates with a host 103 such as a PC (Personal Computer) through an interface such as SATA (Serial Advanced Technology Attachment). Do.

  The structure of the optical disk 102 is illustrated in FIG. The optical disk 102 has a guide layer having a track (guide groove) structure and N recording layers (N ≧ 1, N is a natural number) not having a track structure. The optical disc apparatus 101 can generate laser spots LSW and LSg in the recording layer and the guide layer, respectively, by the objective lens 311.

  The optical disc apparatus 101 is provided in the controller 201, an optical pickup 203, a slider motor 204 that moves the optical pickup 203 in the radial direction of the optical disc 102, slider driving means 205 that drives the slider motor 204, and the optical pickup 203. Aberration correction driving means 206 for driving the spherical aberration correction element 309, a spindle motor 207 for rotating the optical disk 102, a spindle control means 208 for generating a rotation signal for rotating the spindle motor 207, and a spindle The spindle driving means 209 that drives the spindle motor 207 in accordance with the rotation signal generated by the control means 208 and generates an FG signal having a frequency corresponding to the rotation speed of the spindle motor 207, the recording layer of the optical disk 102, and the laser spot LSW Focus that generates a recording layer focus error signal indicating the amount of deviation from the focus position Difference signal generation means 211, focus control means 212 for generating a focus drive signal according to the recording layer focus error signal, and focus drive means 213 for driving an actuator 312 provided in the optical pickup 203 according to the focus drive signal A tracking error signal generating means 214 for generating a recording layer tracking error signal indicating the amount of positional deviation between the recording layer track and the laser spot LSW on the recording layer, and a laser spot LSg on the guide layer track and the guide layer of the optical disc 102. A tracking error signal generating unit 210 that generates a guide layer tracking error signal indicating the amount of misalignment with the tracking layer, a tracking control unit 215 that generates a tracking drive signal according to the recording layer tracking error signal or the guide layer tracking error signal, and tracking Depending on the drive signal, the actuator 312 A tracking drive unit 216 that moves, a focus error signal generation unit 217 that generates a guide layer focus error signal indicating the amount of deviation between the guide layer of the optical disc 102 and the focal position of the laser spot LSg, and a guide layer focus error signal A relay lens control unit 218 that generates a relay lens driving signal and a relay lens driving unit 219 that drives the relay lens 321 in accordance with the relay lens driving signal are provided.

  The optical pickup 203 performs servo control on the guide layer, and data on a guide layer optical system for reproducing an address and disc-specific information corresponding to the position on the disc, and a plurality of recording layers at different distances from the guide layer. Is composed of a recording layer optical system for recording / reproducing data.

First, the operation of the recording layer optical system will be described. The laser driver 301 is controlled by the controller 201 and outputs a current for driving the laser diode 302. This drive current is applied with high frequency superposition of several hundred MHz in order to suppress laser noise. The laser diode 302 emits a laser beam LBw having a wavelength of 405 nm, for example, with a waveform corresponding to the drive current. The emitted laser light becomes parallel light by the collimator lens 303, a part of the light is reflected by the beam splitter 304, and is condensed on the power monitor 306 by the condenser lens 305. The power monitor 306 feeds back a current or voltage corresponding to the intensity of the laser light to the controller 201. Thereby, the intensity of the laser beam LBw focused on the recording layer of the optical disc 102 is maintained at a desired value such as 2 mW. On the other hand, the laser beam LBw that has passed through the beam splitter 304 is reflected by the polarization beam splitter 307, and the convergence / divergence is controlled by the spherical aberration correction element 309 driven by the aberration correction drive means 206, and passes through the dichroic mirror 308. . The dichroic mirror 308 is an optical element that reflects light of a specific wavelength and transmits light of other wavelengths. Here, it is assumed that light having a wavelength of 405 nm is transmitted and light having a wavelength of 650 nm is reflected. The laser beam LBw that has passed through the dichroic mirror 308 becomes circularly polarized light by the quarter-wave plate 310 and is focused as a laser spot LSW on the recording layer of the optical disk 102 by the objective lens 311. Here, the spherical aberration correction element 309 is controlled from the controller 201 via the aberration correction driving means 206 so as to be at a predetermined position corresponding to the recording layer of the grooveless disk. The intensity of the laser beam LBwr reflected by the optical disc 102 is modulated according to information recorded on the optical disc 102. The light is linearly polarized by the quarter-wave plate 310, passes through the dichroic mirror 308, and passes through the polarization beam splitter 307 and the spherical aberration correction element 309. The transmitted laser light LSW is condensed on the detector 314 by the condenser lens 313. The detector 314 detects the intensity of the laser beam LBwr and outputs a signal corresponding to this to the controller 201. The focus error signal generation unit 211 generates a recording layer focus error signal for the recording layer from the signal output from the detector 314. The focus control unit 212 outputs a focus drive signal corresponding to the focus error signal to the focus drive unit 213 in response to a command signal from the controller 201. The focus driving means 213 drives the actuator 312 according to the focus drive signal to displace the position of the objective lens 307 in the direction perpendicular to the recording surface, and the recording layer focus servo so that the laser beam LBw is focused on the recording layer. Take control. The signal output from the detector 310 is also input to the tracking error signal generation unit 214 to generate a recording layer tracking error signal for the recording layer. The tracking control unit 215 outputs a tracking drive signal corresponding to the output of the tracking error signal generation unit 214 or the tracking error signal generation unit 210 to the tracking drive unit 216 according to a control signal from the controller 201.
Next, the guide layer optical system will be described. Similar to the recording layer optical system, the laser driver 301 is controlled by the controller 201 and outputs a current for driving the laser diode 315. The laser diode 315 emits laser light LBg having a wavelength of 650 nm, for example. A part of the laser beam LBg is monitored by a power monitor 319 through a collimator lens 316, a beam splitter 317, and a condenser lens 318. By feeding back the monitored power to the controller 201, the intensity of the laser beam LBg focused on the guide layer of the optical disc 102 is maintained at a desired power such as 3 mW. The laser beam LBg that has passed through the beam splitter 317 passes through the polarization beam splitter 320 and is controlled by the relay lens 321 to converge and diverge. The laser beam LBg that has passed through the relay lens 321 is reflected by the dichroic mirror 308, passes through the quarter-wave plate 310, and is condensed as a laser spot LSg on the guide layer of the optical disk 102 by the objective lens 311. The laser beam LBgr reflected by the optical disk 102 is reflected by the polarization beam splitter 320 and condensed on the detector 323 by the condenser lens 322.

  The detector 323 detects the intensity of the laser beam LBgr and outputs a signal corresponding to the intensity to the controller 201. The controller 201 generates a signal corresponding to the track formed by wobbling the guide layer based on the output from the detector 323, and further, based on this, a synchronization signal for controlling the rotation of the optical disc 102, recording or reproduction A clock signal serving as a reference for performing the above is generated, and an address corresponding to the position on the disk that the laser spot LSg follows is reproduced. The synchronization signal output from the controller 201 and the FG signal output from the spindle driving means 209 are input to the spindle control means 208. The spindle control means 208 outputs a spindle drive signal based on an FG signal having a frequency corresponding to the rotational speed of the spindle motor 207 when the optical disk 102 is rotated at a constant angular velocity by the control signal from the controller 201, and the optical disk 102 is When rotating at a constant linear velocity, a spindle drive signal based on the synchronization signal reproduced from the guide layer is output. In the spindle driving means 212, spindle control is performed by driving the spindle motor 207 in accordance with the spindle driving signal so that the rotational speed of the optical disk becomes a predetermined value. The focus error signal generation means 217 generates a guide layer focus error signal corresponding to the deviation between the guide layer of the optical disc 102 and the in-focus position of the laser spot LSg from the signal output from the detector 323, and the relay lens control means 218 A relay lens driving signal corresponding to the layer focus error signal is generated. The relay lens driving means 219 performs guide layer focus servo control so that the laser spot LSg is focused on the guide layer by driving the relay lens 321 according to the relay lens drive signal. Further, the tracking error signal generation unit 210 generates a guide layer tracking error signal corresponding to the positional deviation between the track of the guide layer of the optical disc 102 and the laser spot LSg from the signal output from the detector 323, and the tracking control unit 215 Output to. The tracking control unit 215 outputs a tracking drive signal corresponding to the output of the tracking error signal generation unit 214 or the tracking error signal generation unit 210 to the tracking drive unit 216 according to a control signal from the controller 201.

  When recording on the recording layer, the laser spot LSW is recorded on the recording layer by driving the actuator 312 with the focus drive signal generated based on the recording layer focus error signal output from the focus error signal generating unit 211. The recording layer focus servo control is performed so as to focus on the layer, and the relay lens 315 is driven by the relay lens drive signal generated based on the guide layer focus error signal output from the focus error signal generation unit 217. Guide layer focus servo control is performed so that the laser spot LSg is focused on the guide layer in the recording layer. In addition, a tracking drive signal generated based on the guide layer tracking error signal output from the tracking error signal generation unit 210 is output from the tracking control unit 215 to the tracking drive unit 216 by the control signal from the controller 201. The tracking drive means 216 performs the tracking servo control so that the laser spot LSg follows the track of the guide layer by driving the actuator 312 in accordance with the tracking drive signal. The slider control means 220 that receives the control signal from the controller 201 outputs a slider drive signal for driving the slider motor 204 based on the average value of the tracking drive signal. In accordance with this slider drive signal, the slider motor 204 is driven by the slider drive means 205, and the optical pickup 203 is moved in the disk radial direction so that the actuator 312 operates in the vicinity of the center position of the movable range in the disk radial direction. Data to be recorded on the recording layer input from the host 103 and address information corresponding to the position on the disk where the data is recorded are output to the controller 201. The controller 201 modulates the input data and address information by a predetermined method based on the reference clock signal reproduced from the guide layer, and outputs it to the laser driver 301. The laser driver 301 outputs a drive current corresponding to the output of the controller 201 to the laser diode 302, and the laser diode 302 emits the laser beam LBw with a corresponding intensity, whereby recording is performed on the recording layer of the optical disc 102. As a result, recording is performed on the recording layer while following the tracks formed on the guide layer, so that information is recorded on the recording layer along the same locus as the spiral of the track of the guide layer. For example, when the guide layer track is formed in a spiral shape from the inner periphery to the outer periphery, the track recorded by the recording layer is formed in a spiral shape from the inner periphery to the outer periphery in the same manner. .

  When reproducing the information recorded on the recording layer, the actuator 312 is driven by the focus drive signal generated based on the recording layer focus error signal output from the focus error signal generating means 211, thereby causing the recording layer to laser. The recording layer focus servo control is performed so that the spot LSW is focused on the recording layer, and the relay lens 321 is controlled by the relay lens driving signal generated based on the guide layer focus error signal output from the focus error signal generation unit 217. By driving, guide layer focus servo control is performed so that the laser spot LSg is focused on the guide layer by the guide layer. The tracking error detection unit 214 outputs a tracking error signal corresponding to the deviation between the track formed by the locus of information recorded on the recording layer and the laser spot LSW irradiated on the recording layer. A tracking drive signal generated based on the recording layer tracking error signal output from the tracking error signal generation unit 214 is output from the tracking control unit 215 to the tracking drive unit 216 by the control signal from the controller 201. The tracking drive means 216 drives the actuator 312 in accordance with the tracking drive signal, and tracking servo control is performed so that the laser spot LSW follows the track formed by the locus of information recorded on the recording layer, and recording is performed from the detector 313. A reproduction signal from the layer is output. The slider control means 220 that receives the control signal from the controller 201 outputs a slider drive signal for driving the slider motor 204 based on the average value of the tracking drive signal. In accordance with this slider drive signal, the slider motor 204 is driven by the slider drive means 205, and the optical pickup 203 is moved in the disk radial direction so that the actuator 312 operates in the vicinity of the center position of the movable range in the disk radial direction. The controller 201 generates a synchronization signal for controlling the rotation of the optical disc 102 from the input reproduction signal and a clock signal that serves as a reference for reproduction, and processes such as amplification, equalization, and decoding for the reproduction signal The recording mark on the disk is discriminated, and further, data obtained by performing demodulation and error correction is output to the host 103.

  Here, the same laser driver 301 is used to drive the laser diode 302 and the laser diode 315, but each laser diode may be provided with a unique laser driver. Further, the spherical aberration correction element 309 may be disposed at a position that affects both the 405 nm optical system and the 650 nm optical system, and may be disposed between the quarter wavelength plate 310 and the dichroic mirror 308, for example. .

  FIG. 4 shows a processing flow of the optical disc apparatus 101 when the optical disc 102 is inserted into the optical disc apparatus 101.

  When the optical disk 102 is inserted into the optical disk apparatus 101 in S401, the optical disk apparatus 101 confirms the presence / absence of a disk and the disk type in S402. At this time, for example, the optical disc apparatus 101 can irradiate the optical disc 102 with laser light and perform recognition by reflected light.

  Next, in S403, adjustment processing for making various parameters in the optical disc apparatus 101 suitable for the inserted optical disc 102 is performed. Examples of the various parameters include adjusting the amplification factor of the amplifier included in the focus control unit 212 and the tracking control unit 215 in accordance with the reflectance of the optical disc 102.

  After performing various adjustments, the management information of the optical disc 102 is read in S404.

  When the processing proceeds to S405, the recording or reproduction is possible, and recording or reproduction can be performed in accordance with a command from the host 103.

  The timing of the adjustment process S403 is not limited to this, and a part of the adjustment process may be performed after the management information read S404.

(Configuration example of controller 201)
FIG. 5 shows an example of the controller 201 that enables recording / reproduction of the optical disc 102 described above.

  The controller 201 includes a host interface unit 501, a buffer memory control unit 502, a buffer memory 503, a microprocessor 504, a layer determination unit 505, an address determination unit 507, a recording timing signal generation unit 508, a reproduction data demodulation unit 513, and a recording data modulation unit. 514, emission signal generation means 515, wobble detection means 516, PLL 517, unrecorded discrimination means 518, and register 519, respectively. LBw is the output light for the recording layer, LBwr is the return light from the recording layer, LBg is the output light for the guide layer, and LBgr is the return light from the guide layer.

  The host interface unit 501 is a unit that performs communication between the host 103 and the optical disc apparatus 101. When the write command is received, the recording data is stored in the buffer memory 503 via the buffer memory control means 502, and a signal indicating that the write command has been issued is transmitted to the microprocessor 504. On the other hand, when the read command is received, the reception of the command is transmitted to the microprocessor 504, and the process of reproducing the data in the area specified by the command from the optical disk 102 is started, and the obtained data is completely stored in the buffer memory 503. At the same time, the data is transferred to the host 103 via the buffer memory control means 502.

  The microprocessor 504 controls the entire optical disc device 101 based on a processing procedure stored in a program memory (not shown). In response to reception of a read command or write command from the host 103, the slider control means 220 is set so that the light spot on the disk moves in the vicinity of the recording / reproducing position. Set to start tracking servo. On the other hand, address information for starting processing is given to the recording timing signal generating means 508 when a write command is received and to the reproduction data demodulating means 513 when a read command is received.

  The recording data modulation means 514 adds error correction code or modulation processing to the recording data stored in the buffer memory 503, and generates recording data converted into a format for recording on the optical disk 102. .

  The reproduction data demodulating means 513 detects the processing start position according to the address information for starting the processing from the microprocessor 504, and discriminates the data corresponding to the mark and space on the disk from the signal detected by the detector 314. Then, data to be transferred to the host 103 is generated by performing demodulation processing, error correction processing, etc., and stored in the buffer memory 503 via the buffer memory control means 502.

  The wobble detection means 516 detects the wobble signal from the output of the detector 323 that detects the return light LBgr from the guide layer. The PLL 517 generates a multiplied clock that is phase-synchronized with the wobble signal.

  The address discriminating means 507 discriminates the address information of the tracking radius position based on the output of the detector 323 that detects the return light LBgr from the guide layer.

  The recording timing signal generation means 508 receives the address information for starting recording from the microprocessor 504 and the address information from the address determination means 507, and the light spot on the guide layer passes the recording start position and the recording start timing. The signal is output to the light emission signal generating means 515.

The light emission signal generation unit 515 is a unit that transmits a recording waveform corresponding to a data pattern to be recorded on the optical disc 102 to the laser driver 301. A recording waveform corresponding to the data pattern to be recorded is generated from the recording data generated by the recording data modulation means 514. When recording the layer discrimination pattern, transmission to the laser driver 301 is started at the timing when the recording start timing signal from the recording timing signal generation means 508 is obtained. The transmission rate to be transmitted follows the frequency of the recording clock from the PLL 517.
The layer discriminating means 505 focuses the laser beam spot for the recording layer based on the signal detected from the return light from the recorded area of the layer discriminating information recorded in the specific radius range on each recording layer. The recording layer is discriminated, and the result is output to the microprocessor 504.

  The unrecorded discriminating means 518 discriminates whether the focused area is a recorded area or an unrecorded area based on the output of the detector 314 that detects the amount of return light from the recording layer, and the result is determined by the microprocessor 504. Output to. For example, when the top level and the bottom level of the light intensity detected by the detector 314 are detected and the top level has an amplitude greater than or equal to a certain level, and the difference between the top level amplitude and the bottom level amplitude is not greater than a certain level, unrecorded It is determined that

  The register 519 is a means for the microprocessor 504 to store the setting value of the processing parameter of each means in the figure, and the stored value is given to each means by connection not shown.

  Next, an example of the structure of the optical disc applied to this embodiment will be described with reference to FIGS.

(Example of optical disc applied to this embodiment)
FIG. 1 is a schematic diagram of an example of an optical disc according to the present invention, in which a laser beam is incident in an example of a disc having five recording layers from the L0 layer to the L4 layer and one guide layer. The board surface and the cross section viewed from above. The recording layer does not have to be five layers, and may be an N layer (N is a natural number).

In the present embodiment, in addition to the fact that the radial position differs from layer to layer with respect to the inner radius of the recording layer, the magnitude relation of the inner radius is not changed over the entire circumference.
In addition, the names of the recording layers in this embodiment are determined as L0, L1, L2, L3, and L4, corresponding to the order of decreasing inner radius. Furthermore, the inner radius of the guide layer is made smaller than any recording layer.

  In the cross-sectional view of FIG. 1, the order of arrangement in the thickness direction of each recording layer is determined so that the inner radius increases sequentially from the incident side, but even if this order is changed, the present invention It is possible to obtain an effect.

(Recording position of layer discrimination information in the optical disc of the present invention)
FIG. 6 shows an outline of a cross section in the vicinity of the innermost circumference where layer discrimination information is recorded and the recording position of the layer discrimination information on the optical disc 102 of the present invention. The layer discriminating information is information unique to the recording layer and recorded over a specific radius range of each recording layer in order to discriminate each recording layer.
In FIG. 6, 601 is a buffer area for L0 discrimination information.
Reference numeral 602 denotes an L0 discrimination information recording area.
Reference numeral 603 denotes an L1 discrimination information buffer area.
Reference numeral 604 denotes an L1 discrimination information recording area.
Reference numeral 605 denotes an L2 discrimination information buffer area.
Reference numeral 606 denotes an L2 discrimination information recording area.
Reference numeral 607 denotes a buffer area for Ln-2 discrimination information.
Reference numeral 608 denotes an Ln-2 discrimination information recording area.
Reference numeral 609 denotes a buffer area for Ln-1 discrimination information.
Reference numeral 610 denotes an Ln-1 discrimination information recording area.

  Further, r0, r1, r2, r3, r4, rn-2, and rn-1 shown as radial positions are the inner radii of L0, L1, L2, L3, L4, Ln-2, and Ln-1, respectively. Ri is determined on the outer peripheral side of rn-1. Ro is the reference radius position of the outer peripheral edge of the layer discriminating information recording area similarly determined for all recording layers, and is further determined on the outer periphery than Ri. An area for recording user data from the host 103 is provided on the outer periphery further than Ro. Here, the radius range in which the inner peripheral edge of the discrimination information recording area of each layer is provided is referred to as a discrimination information buffer area, and the boundary of the discrimination information recording area in this range is indicated by diagonal lines.

  The boundary on the inner peripheral side of the L0 discrimination information buffer area 601 is provided between the inner radius r0 of L0 and the inner radius r1 of L1. Further, the L0 discrimination information recording area 602 is provided between the inner radius r1 of L1 and Ro which is the reference radius position of the boundary on the outer peripheral side of the layer discrimination information recording area. In such an arrangement, the layer discrimination information for L0 is recorded such that the inner boundary exists within the range of the L0 discrimination information buffer area 601, and the outer boundary is further to the outer periphery than the radius Ro. Determine to do.

The same applies to the other recording layers. In Lk (k is a natural number smaller than n−1), the boundary on the inner peripheral side of the buffer area for Lk discrimination information is the inner radius rk of Lk and the inner radius rk + of Lk + 1. Provided between 1 (radius Ri for k = n−1). Further, the Lk discrimination information recording area has an inner radius rk + 1 of Lk + 1 (radius Ri for k = n-1) and a reference radius position on the outer boundary of the layer discrimination information recording area. Provided between some Ro. In such an arrangement, the Lk layer discrimination information is recorded such that the boundary on the inner peripheral side is in the range of the buffer region for the Lk discrimination information, and the outer peripheral end is on the outer peripheral side with respect to the radius Ro.
When the layer discrimination information of each layer is recorded in such an arrangement, the layer discrimination information is formed in all the recording layers in the range between the radius Ri and the radius Ro.
Therefore, when moving between the layers, by referring to the address information of the guide layer in advance and moving between the radii Ri and the radius Ro once and moving between the layers, the movement result can be any recording layer. The success or failure of the movement can be determined from the layer discrimination information, and an accurate interlayer movement can be realized.

(Recording process of layer discrimination information)
FIG. 7 shows a recording processing flow for recording the layer discrimination information at the layer discrimination information recording position on the optical disc shown in FIG. This layer discrimination information recording process needs to be performed before the optical disk apparatus performs the data recording process for the first time on the disk. For example, the recording may be performed immediately after being inserted into the optical disc device 101 for the first time, or may be recorded when a write command is received for the first time. In addition, recording is performed when a command for recording layer discrimination information is received from the host, and a write command for recording user data is not accepted until layer discrimination information is recorded. Also good.

  In FIG. 7, S701 is a step of focusing the guide layer laser light on the guide layer and applying focusing servo and tracking servo. As described above, since the wobble signal and the address information are obtained from the guide layer, it is possible to generate a recording clock and determine the position on the board surface.

  S702 is a step of initializing the recording layer number m to be recorded in the layer discrimination information to 0. For example, if m = 0, the L0 layer is targeted.

  S703 is a step of moving the radial position from rm to rm + 1. The radial position can be determined by referring to address information on the guide layer. Alternatively, if the difference in radius between the recording layers is sufficiently larger than the control accuracy of the slider drive, the address information need not be referred to. For m = n-1, we define rn = Ri and move between radius rn-1 and Ri.

  S704 is a step of focusing the recording layer emission light LBw on the Lm layer and applying focusing servo.

  S705 is a step of checking the recording state at the radial position for the recording layer to which the focusing servo is applied in S704. Since the layer discrimination information is not recorded in the target layer, if the interlayer movement is successful, the layer discrimination information is not detected, and the unrecorded discriminating means 518 can discriminate that it is in an unrecorded state. Be expected. If not recorded, the process proceeds to step S706.

  On the other hand, if the recording layer is not unrecorded, it is determined that the recording layer has moved to an unintended recording layer, and the layer discrimination means 505 is used to detect the layer discrimination information. After that, step S704 is executed again. Since the recording layer that has reached in error can be determined in step S709, the processing parameter such as the correction amount of spherical aberration by the spherical aberration correction element 309 is updated in consideration of the determination result, and step S704 is executed again. , Improve the probability of success.

  S706 is a step of recording the layer discrimination information of the Lm layer. This step is executed in a state where tracking servo is performed on the guide layer by the guide layer emission light 509. The radial position to be recorded is as described above, the inner peripheral edge is in the range of the Lm discrimination information buffer area (between the radius rm and the radius rm + 1), and the outer peripheral edge is on the outer peripheral side from the radius Ro. To record. When performing adjustment recording for adjusting the recording conditions of the layer discrimination information of each layer, a recording condition adjustment step is provided between the steps of S705 and S706, and the discrimination information buffer area of each recording layer is provided. Make adjustment records.

  S707 is a step of determining whether or not the recording layer is the last recording layer.

  S708 is a step of incrementing the recording layer number m when it is determined in S707 that the recording layer is not the last recording layer, and a series of processes are performed from the step S703 on the next recording layer.

  According to the layer discrimination information recording position in FIG. 6 and the processing flow in FIG. 7, the unrecorded layer is only the target layer for recording the layer discrimination information at the radial position at which focusing servo to the recording layer is started, In all recording layers other than the target layer, layer discrimination information is already recorded. For this reason, even if the focused recording layer is wrong, it can be judged by checking the layer discrimination information, and recording of the layer discrimination information on the wrong recording layer can be prevented.

(Example of discriminating information on the disc)
FIG. 8 shows an example of the recording mode of the layer discrimination information on the recording layer and an example of the obtained layer discrimination signal.
The upper part of FIG. 8 represents layer discrimination information on the Lk layer (k is a natural number), and a recording mark and a space portion having a single length Mk are repeatedly arranged in the circumferential direction. Here, the length Mk of the recording mark and the space portion is made different for each recording layer. In the following, layer discrimination information in a format in which a single pattern formed by a recording mark and a space is repeated with a unique period for each recording layer is referred to as a layer discrimination pattern.

  The lower part of FIG. 8 represents a layer discrimination signal obtained from the layer discrimination pattern shown in the upper diagram. In this embodiment, a layer discrimination signal is obtained from a signal representing the total amount of return light output from the detector 314. A rectangular wave with a fixed period or a signal close to a trapezoidal wave or sine wave can be obtained. Here, if the light spot LSW has a linear velocity V on the recording layer in the circumferential direction, the period of the layer discrimination signal is 2Mk / V, the frequency is V / 2Mk, and if the linear velocity is constant, the length of the mark Depends on Mk. Therefore, as described above, the length of the mark and the space portion is recorded differently for each recording layer, and each recording layer is scanned with a light spot at the same speed during reproduction. The recording layer is discriminated from the frequency.

  In addition, the fundamental frequency component of the reproduction signal obtained from the repeated pattern can be observed on the spectrum in the same way without tracking servo if the recording layer laser light is focused on each recording layer. It is.

  Fig. 9 compares the spectrum of the playback signal obtained from an area where 8T-length marks and 8T-length spaces are repeatedly recorded on a BD-RE disc under two conditions, with and without tracking servo. Is. In both cases, a steep peak was observed at the fundamental frequency of the repeated pattern of 8.25 MHz. Although the BD-RE disc is exemplified here, the recording / reproducing principle in the recording layer does not change even in the grooveless disc, and the same result can be obtained.

  As described above, when layer discrimination is performed based on the fundamental frequency component of the reproduction signal obtained from the repetitive pattern, if the recording layer laser light is focused on each recording layer, the recording layer can be recorded without performing tracking servo. Discrimination becomes possible.

(First example of layer discrimination means)
FIG. 10 shows a first example of the layer discriminating means. FIG. 11 is an outline of the operation.
Reference numeral 1001 denotes a reproduction signal, and reference numeral 1002 denotes a period counting clock.
Reference numeral 1003 denotes a mark edge detection signal.
Reference numeral 1004 denotes layer discrimination result information.

Further, the layer discriminating means of this configuration has the elements of a filter circuit 1005, a mark edge detecting means 1006, an edge interval counter 1007, a count value holding means 1008, an averaging means 1009, and a comparing means 1010.
The reproduction signal 1001 is a signal indicating the intensity of the return light from the recording layer detected by the detector 314, and the amplitude varies depending on the presence or absence of the recording mark at the scanning position of the light spot on the recording layer. When each layer discrimination region is in focus, the amplitude fluctuates at a constant period as shown in the lower part of FIG.

  The filter circuit 1005 is for removing unnecessary frequency components from the reproduction signal. The high frequency cutoff frequency of the filter circuit 1005 is larger than the maximum of the fundamental frequencies of the layer discrimination signals of all recording layers, and the low frequency cutoff frequency is the lowest of the fundamental frequencies of the layer discrimination signals of all recording layers. Set to a lower frequency than the one.

  The mark edge detection means 1006 is for detecting the timing when the light spot passes through the edge of the mark on the disc. The output signal of the filter circuit 1005, which is a reproduction signal in which the DC component is suppressed, is zero level in amplitude. A signal indicating the timing of crossing is generated. In particular, in the operation example in FIG. 11, a signal is generated at a timing when the reproduction signal amplitude crosses the zero level from the minus side to the plus side. Further, since the zero cross period includes an error due to noise and waveform distortion, the zero cross interval is represented as T1, T2,..., T9 in FIG.

The period counting clock 1002 uses a clock having a frequency proportional to the speed (linear velocity) at which the recording layer laser light spot scans the recording layer. For example, a clock generated by PLL 517 and obtained by multiplying the frequency of the wobble signal obtained from the guide layer may be used. Further, a clock signal that oscillates at a fixed frequency may be used as long as the linear velocity is considered to be controlled to be constant.
The edge interval counter 1007 is a counter that is incremented in the cycle of the cycle count clock 1002, and transfers the count value to the subsequent count value holding unit 1008 at the timing of the mark edge detection signal 1003 output by the mark edge detection unit 1006. Return the count value to 0. At this time, a value proportional to the zero cross interval is obtained as the transfer value to the count value holding means 1008 which is the count value immediately before returning the count value to 0. In FIG. 11, the proportionality constant is set to a, and the count values immediately before being cleared are aT1, aT2,.

  The count value holding means 1008 receives the values aT1, aT2,... Of the preceding edge interval counter 1007 at the timing of the mark edge detection signal 1003, and holds the value until the timing of the next mark edge detection signal 1003. This value is ideally a constant value proportional to the period of the layer discrimination pattern, but in order to suppress variations due to various disturbances, an average value is obtained using averaging means 1009. The averaging means 1009 is realized by a low-pass filter having a cutoff frequency that is sufficiently smaller than the frequency at which the reproduction signal crosses zero. In FIG. 11, an outline of the behavior of the detected zero-crossing interval after averaging is shown by a solid line in the graph of the item of averaging means.

The comparison means 1010 compares the average value of the zero cross intervals obtained by the averaging means 1009 with the expected value for layer discrimination prepared for all recording layers in advance, for layer discrimination closest to the average value of zero cross intervals The recording layer corresponding to the expected value is determined, and layer determination result information 1004 is output following the determination result. In FIG. 11, the L1 layer discrimination expected value is closest to the output value of the averaging means, and the comparison means 1010 outputs the layer discrimination result information 1004 corresponding to the L1 layer.
As described above, the recording layer can be identified.

  According to the first embodiment described above, the layer discrimination information can be recorded in the desired recording layer without mistakes in the recording layer even in the optical disc in which the recording groove structure does not exist in the recording layer. Also, after the layer discrimination information is formed, the recording layer can be discriminated by referring to it. Furthermore, by applying a layer discrimination pattern consisting of repetition of a fixed period as the layer discrimination information, it is possible to discriminate the recording layer without performing tracking servo.

  The above description is based on an example in which an area for recording the layer discrimination information is provided at the inner peripheral edge of the disc. However, as shown in FIG. 12, the radial position of the outer peripheral edge is different for each recording layer. The same effect can be obtained even if an area for recording the layer discrimination information is provided. The radial position and recording order for recording the layer discrimination information are the same as described above if the definition of the recording layer name is made in the order of the radius at the outer peripheral end and the inner and outer peripheral sides of the radial position in FIG. Therefore, explanation is omitted.

(Form using layer discrimination pattern with mark length proportional to radial position)
A second embodiment of the present invention is shown below. Description of the same parts as those in the first embodiment is omitted.

  In the present embodiment, the layer discrimination pattern recorded on the disc and the recording / reproducing method thereof are different from those of the disc described in the first embodiment.

  The layer discrimination pattern in the present embodiment is as shown in FIG. A length proportional to the radial position is given to the mark and the space, and the size differs depending on the radial position. In order to obtain such a pattern, when recording the layer discrimination pattern, the disc rotation method is set to CAV (constant angular velocity) control, and the intensity of the recording light emission waveform is repeatedly changed at a constant frequency regardless of the tracking radius position. A mark is formed using the waveform to be generated. Note that this frequency varies depending on the recording layer.

  On the other hand, also when the layer discrimination signal is generated from the layer discrimination pattern formed in this way to discriminate the recording layer, the disc rotation method is set to CAV (constant angular velocity) control. Similar to the recording light emission waveform, the layer discrimination signal obtained at this time has a constant frequency regardless of the radial position. Therefore, the recording layer can be identified by using the clock signal oscillating at a fixed frequency as the cycle counting clock 1002 and applying the layer discrimination means of FIG. 10 and evaluating the zero-cross cycle of the layer discrimination signal. is there.

  According to the second embodiment described above, when the layer discrimination signal is generated from the layer discrimination pattern and the recording layer is discriminated, the signal from the guide layer is not required, and the optical system for the guide layer is not provided. The recording layer can also be identified in the drive device.

(Form in which layer discrimination information is provided on both the inner and outer circumferences)
A third embodiment of the present invention is shown below. In the present embodiment, layer discrimination information is recorded both in the vicinity of the innermost periphery and in the vicinity of the outermost periphery with the user data area separated from the disc of FIG. 1 or FIG. 12 described in the first embodiment. Here, the description will be made on the premise of a disk provided with different inner radii for each recording layer as shown in FIG. When using a disc with the outer radius different for each recording layer as shown in FIG. 12, the same effect can be realized if the inner periphery and the outer periphery are interchanged with respect to the following description.

FIG. 14 shows the outline of the cross section near the innermost circumference and the vicinity of the outermost circumference where the layer discrimination information is recorded, and the recording position of the layer discrimination information on the optical disc of this embodiment.
Reference numeral 1401 denotes an outer periphery L0 discrimination information recording area.
Reference numeral 1402 denotes an outer periphery L1 discrimination information recording area.
Reference numeral 1403 denotes an outer periphery L2 discrimination information recording area.
Reference numeral 1404 denotes an outer circumference Ln-2 discrimination information recording area.
Reference numeral 1405 denotes an outer circumference Ln-1 discrimination information recording area.

  Also. Ri0, ri1, ri2, ri3, ri4, rin-2, and rin-1 shown as radial positions are the inner radii of L0, L1, L2, L3, L4, Ln-2, and Ln-1, respectively. Rii is determined on the outer peripheral side of rn-1. Rio is the reference radius position of the boundary on the outer peripheral side of the recording area of the layer discrimination information similarly determined for all recording layers, and is further determined on the outer periphery than Rii.

  Roi is a boundary radius on the inner peripheral side provided in common in the recording area of the layer discrimination information on the outer peripheral side of each recording layer. Roo is the reference radius position on the outer periphery side of the layer discrimination information recording area determined in the same manner for all recording layers, and is further determined on the outer periphery than Roi.

  The boundary on the inner circumference side of the buffer area 1501 for the inner circumference L0 discrimination information is provided between the inner radius ri0 of L0 and the inner radius ri1 of L1. The inner circumference L0 discrimination information recording area 1502 is provided between the inner radius ri1 of L1 and the reference radius position Rio of the outer circumference edge of the layer discrimination information recording area. In such an arrangement, the layer discrimination information 1502 for the inner circumference L0 is recorded so that the inner circumference end is in the range of the inner circumference L0 discrimination information buffer area 1501 and the outer circumference end is on the outer circumference side than the radius Rio. Determine to do.

  The same applies to the other recording layers, and in the Lk layer (k is a natural number smaller than n−1), the boundary on the inner peripheral side of the buffer region for the inner peripheral Lk discrimination information is within the inner radius rik and Lk + 1 of Lk. Provided between radius rik + 1 (radius Rii for k = n−1). Further, the inner circumference Lk discrimination information recording area has an inner radius rk + 1 of Lk + 1 (radius Rii for k = n-1) and a reference radius position at the outer edge of the layer discrimination information recording area. Provided between certain Rios. In such an arrangement, the layer discrimination information for Lk is recorded such that the inner peripheral edge is in the range of the inner peripheral Lk discrimination information buffer area and the outer peripheral edge is on the outer peripheral side than the radius Rio.

  The radial position of the layer discrimination information recording area on the outer peripheral side is the same regardless of the recording layer, and the radius Roi is changed to the radius Roo. With this arrangement, in addition to the innermost circumference, the layer discrimination information recording area is provided in all the recording layers in the range from the outermost radius Roi to the radius Roo. In this way, depending on the moving target and the radial position before the movement, either the range from the radius Rii to Rio on the innermost circumference side or the layer discrimination information from the range from the radius Roi to the radius Roo can be selected. In other words, the distance of interlayer movement can be reduced. Also, even if a defect or the like occurs at one of the radial positions, it is possible to perform layer discrimination by referring to the other.

  FIG. 15 shows a recording processing flow of the layer discrimination information recording area in the present embodiment. The difference from that shown in FIG. 7 is that the step of recording the outer periphery layer discrimination information of the Lm layer is added after step S706 of recording the layer discrimination information of the Lm layer as S1501. According to the processing flow shown in FIG. 15, since the movement between the recording layers is performed only on the inner peripheral side where the radial position is shifted, the layer discrimination information on the inner peripheral side can be obtained without error in the recording layer as in the first embodiment. In addition to being able to record, layer discrimination information can also be recorded on the outer peripheral side where the radial position is not shifted, without error in the recording layer.

  The recording pattern of the layer discrimination information and the detection method / device thereof can be the same as those in the first or second embodiment.

  According to the form of Example 3 described above, in addition to being able to record the inner circumference side layer discriminating information without making a mistake in the recording layer as in Example 1, it is the same on the outer circumference side where the radial position is not shifted. It is possible to record the layer discrimination information without making a mistake in the recording layer. Further, if any layer discriminating information is selected and referred according to the movement target or the radial position before the movement, the distance of the interlayer movement can be reduced. Further, even if a defect or the like occurs at one of the radial positions, the other can be referred to.

(Mode for applying a layer discrimination method based on frequency component power value detection)
A fourth embodiment of the present invention will be described below. In the present embodiment, for a reproduction signal obtained from the layer discrimination pattern, a power value at a frequency provided in advance corresponding to each recording layer is obtained, and the frequency component having the maximum power value is obtained from these. Based on this, the recording layer is determined.

In the present embodiment, the configuration of the layer discriminating means 505 is different from that of the first to third embodiments. In addition, with respect to the frequency of the reproduction signal obtained from the layer discrimination pattern, the mark and space of the layer discrimination pattern should be set so that the larger frequency is not an integral multiple of the smaller frequency in any two recording layer pairs. The length should be determined. This is because when the power of the harmonic component of the signal has a level close to the power of the fundamental frequency, it is misclassified as being focused on another recording layer with the same frequency as the harmonic as the layer discrimination frequency. This is in order to avoid the danger of doing.
Except for the above points, the present embodiment is implemented in the same manner as the first to third embodiments. Description of these same parts is omitted.
The layer discriminating means 505 in the present embodiment is configured as shown in FIG. 16, and includes a filter circuit 1601, an AGC circuit 1602, an L0 discriminating reference signal generating unit 1603, an L1 discriminating reference signal generating unit 1604, and an L2 discriminating reference. Signal generation means 1605, Ln-2 discrimination reference signal generation means 1606, Ln-1 discrimination reference signal generation means 1607, L0 quadrature detection means 1608, L1 quadrature detection means 1609, L2 quadrature detection means 1610, Ln- 2 quadrature detection means 1611, Ln-1 quadrature detection means 1612, and maximum value determination means 1617.

  Also, 1620 is a layer discrimination processing clock, 1613 is an L0 discrimination signal power value, 1614 is an L1 discrimination signal power value, 1615 is an L2 discrimination signal power value, 1616 is an Ln-2 discrimination signal power value, and 1617 Ln-1 discrimination signal power value, 1619 is layer discrimination result information, and 1621 is a layer discrimination signal.

The reproduction signal 1001 is a signal indicating the intensity of the return light from the recording layer detected by the detector 314, and the amplitude varies depending on the presence or absence of the recording mark at the scanning position of the light spot on the recording layer. The filter circuit 1601 is for removing unnecessary frequency components from the reproduction signal 1001. The high frequency cutoff frequency of the filter circuit 1601 is larger than the maximum of the fundamental frequencies of the layer discrimination signals of all recording layers, and the low frequency cutoff frequency is the lowest of the fundamental frequencies of the layer discrimination signals of all recording layers. Set to a lower frequency than the one. The AGC circuit 1602 is an amplifier that sequentially controls the amplification factor so that the output signal has a constant amplitude when the signal from the filter circuit 1601 is input. The layer discrimination signal 1621 processed by the filter circuit 1601 and the AGC circuit 1602 has a frequency corresponding to the recording layer during reproduction of the layer discrimination pattern area of each recording layer, and has the same amplitude regardless of the recording layer. It becomes a repeating pattern. This signal is input to the L0 quadrature detection means 1608, the L1 quadrature detection means 1609, the L2 quadrature detection means 1610, the Ln-2 quadrature detection means 1611, and the Ln-1 quadrature detection means 1612, respectively.
L0 discrimination reference signal generation means 1603, L1 discrimination reference signal generation means 1604, L2 discrimination reference signal generation means 1605, Ln-2 discrimination reference signal generation means 1606, Ln-1 discrimination reference signal generation means 1607, The layer discrimination processing clock 1620 is input, and a sine wave and a cosine wave having the same frequency as the fundamental frequency of the layer discrimination signal 1621 expected to be obtained from each recording layer are generated, and the L0 orthogonal detection means 1608, The L1 orthogonal detection means 1609, the L2 orthogonal detection means 1610, the Ln-2 orthogonal detection means 1611, and the Ln-1 orthogonal detector are output.

  As the layer discrimination processing clock 1620, a clock linked to the frequency of the layer discrimination signal is used. Specifically, if the layer discrimination pattern is recorded so that the mark length and space length are constant regardless of the radius as shown in Fig. 8, a clock synchronized with the wobble detection signal is used. When the control method is CLV (constant linear velocity) control, a clock generated from an oscillator that oscillates at a fixed frequency may be used. Also, as shown in Fig. 13, if the mark length and space length proportional to the radial position are given, the rotation control method is CAV (constant angular velocity) control and generated from an oscillator that oscillates at a fixed frequency. Use a clock.

  L0 quadrature detection means 1608, L1 quadrature detection means 1609, L2 quadrature detection means 1610, Ln-2 quadrature detection means 1611, Ln-1 quadrature detection means 1612 are L0 discrimination reference signal generation means 1603, L1 Quadrature detection using sine wave and cosine wave from discrimination reference signal generation means 1604, L2 discrimination reference signal generation means 1605, Ln-2 discrimination reference signal generation means 1606, Ln-1 discrimination reference signal generation means 1607 Thus, the power value of the frequency component corresponding to each recording layer is detected from the layer discrimination signal 1621, and these values are output to the maximum value judging means 1617. Maximum value determination means 1617 determines the frequency component of the largest power value from the input power value information of each frequency component, and based on this result, it is determined that the recording layer laser light is in focus. Layer discrimination result information 1620 corresponding to the recording layer is generated and can be referred to in the processing of the microprocessor 504.

  FIG. 17 is an example of each recording layer discriminating reference signal generating unit in the layer discriminating information discriminating unit of FIG. 16, and has a counter 1701, a sine wave pattern generating memory 1702, and a cosine wave pattern generating memory 1703 therein. 1704 is a quadrature detection sine wave, and 1705 is a quadrature detection cosine wave.

  The counter 1701 is a counter that is incremented at the timing of the layer discrimination processing clock 1620, and the value returns to 0 when the maximum value provided according to the frequency of the assumed layer discrimination signal is reached. Both the sine wave pattern generation memory 1702 and the cosine wave pattern generation memory 1703 are memory elements that are preset so that the address value and the data output value have a relationship between the phase and amplitude of the sine wave and cosine wave. The signal from the counter 1701 is used as an address signal, and a sine wave and a cosine wave are output in conjunction with the increment of the counter 1701 by the layer discrimination processing clock 1620.

In the example of FIG. 17, a counter whose value is cleared to 0 when the maximum value is 15 is used as the counter 1701, while the sine wave pattern generation memory 1702 and the cosine wave pattern generation memory 1703 have one cycle at 16 addresses. Since the data is provided as described above, a sine wave having a frequency obtained by dividing the frequency of the layer discrimination processing clock 1620 by 1/16 is obtained.
FIG. 18 shows an example of quadrature detection means.
Both 1801 and 1802 are multiplication means.
Both 1803 and 1804 are low-pass filters, which are given the same cutoff frequency.
Reference numeral 1807 denotes an adding means. Reference numeral 1808 denotes a power value signal of a synchronous component.
In this device, out of the frequency components included in the layer discrimination signal 1621, the frequency of the quadrature detection sine wave 1704 and the quadrature detection cosine wave 1705 is the center, and only the cut-off frequency range of the low-pass filters 1803 and 1804 is used. A signal (1/4 of the power value) proportional to the power value of the frequency component in a narrow frequency band having a range above and below is obtained. By reducing the cut-off frequency of the low-pass filter and narrowing the frequency range in which the power value is detected, the recording layer discrimination accuracy can be increased.

  According to Example 4 described above, recording layer discrimination with higher accuracy than the layer discrimination means described in Example 1 is possible, and accurate recording layer discrimination is possible even when a larger number of recording layers is provided. realizable.

(Applying layer discrimination method based on spectrum peak frequency)
A fifth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the layer discriminating means 505 is different from the fourth embodiment, and the other parts are common. The sampled reproduction waveform is stored in the memory, and the peak of the spectrum is obtained from the stored waveform data by calculation of a program executed by the microprocessor 504 to perform layer discrimination. For example, Fast Fourier Transform (FFT) can be applied as a process for obtaining a spectrum.

FIG. 19 shows an example of the configuration of the layer discriminating means according to this embodiment, which comprises a filter circuit 1601, an AGC circuit 1602, an A / D conversion means 1901, a waveform memory 1906, a data memory 1909, and a microprocessor 504.
In FIG. 19, reference numeral 1001 denotes a reproduction signal.
Reference numeral 1902 denotes a layer discrimination sampling waveform.
Reference numeral 1903 denotes a waveform sampling clock.
Reference numeral 1906 denotes a sampling start signal.
Reference numeral 1907 denotes a sampling completion signal.
Reference numeral 1908 denotes waveform memory storage data.

  The reproduction signal 1001 is a signal indicating the intensity of the return light from the recording layer detected by the detector 314, and the amplitude varies depending on the presence or absence of the recording mark at the scanning position of the light spot on the recording layer. In this embodiment, the layer discriminating information is the repetitive pattern shown in FIG. 8 or FIG. 13, and the amplitude of the reproduction signal also varies at a constant period according to this.

  Both the filter circuit 1601 and the AGC circuit 1602 are the same as those described in the fourth embodiment. That is, the filter circuit 1601 is an amplifier that removes unnecessary frequency components from the reproduction signal 1001 and sequentially controls the amplification factor so that the output signal has a constant amplitude when the signal from the AGC circuit 1602 or the filter circuit 1601 is input. is there.

  The A / D conversion means 1901 samples the reproduction signal processed by the filter circuit 1601 and the AGC circuit 1602 at the timing of the waveform sampling clock 1903 and converts it into a digital signal, which is used as a layer discrimination sampling waveform 1902 as a waveform memory 1910. Output to.

  The layer discrimination sampling waveform 1902 uses a clock linked to the frequency of the layer discrimination signal. Specifically, if the layer discrimination pattern is recorded so that the mark length and the space length are constant regardless of the radius as shown in FIG. 8, a clock synchronized with the wobble detection signal is used. However, as long as the rotation control method is CLV (constant linear velocity) control, a clock generated from an oscillator that oscillates at a fixed frequency may be used. Also, as shown in Fig. 13, if the mark length and space length proportional to the radial position are given, the rotation control method is CAV (constant speed constant) control and generated from an oscillator that oscillates at a fixed frequency. Use a different clock.

A so-called FIFO memory is used as the waveform memory 1910. The layer discrimination sampling waveform 1902 is stored in the order of sampling in the cycle of the waveform sampling clock 1903, and when the microprocessor reads out the values, they are read out in the stored order.
The waveform memory 1910 initializes the stored value and the internal write address value and read address value (not shown) at the timing of the sampling start signal 1906 from the microprocessor 504, and when the stored data amount exceeds a certain amount, the sampling completion signal 1907 Is output to the microprocessor 504.
The microprocessor 504 can initialize and read the stored value by outputting a sampling start signal 1906 to the waveform memory 1910. The waveform memory 1910 also receives a sampling completion signal as an interrupt signal or a monitor register. Connect so that the timing of 1907 can be detected. Further, it is connected to a data memory 1909 for storing processing data stored in a program memory (not shown).
FIG. 20 shows a flowchart of the processing of the microprocessor 504 in this embodiment.
After focusing on the recording layer is completed, the processing of this flowchart is performed.

S2001 is a step for initializing and starting the sampling counter. Specifically, it is a process for giving the sampling start signal 1906 from the microprocessor 504 to the waveform memory 1910.
S2002 is a step of receiving the sampling completion signal 1907, and is a step of waiting for the waveform data of a predetermined length to be stored in the waveform memory 1910.

  S2003 is a step of reading waveform data and storing it in the data memory 1909 after data of a predetermined length is stored in the waveform memory 1910.

  S2004 is a step of obtaining a spectrum by performing fast Fourier transform (FFT) on the waveform data stored in the data memory 1909.

  S2005 is a step for obtaining a frequency having a maximum value for the spectrum obtained in S2004.

  S2006 is a step of receiving the result of S2005 and discriminating the focused recording layer from the detected peak frequency. The detected peak frequency and each layer discrimination frequency are compared, and the recording layer corresponding to the closest discrimination frequency is used as the discrimination result.

  According to the configuration of Example 5 described above, it is possible to discriminate the recording layer with higher accuracy than the mode of the layer discriminating unit described in Example 1 as in the method of Example 4, and the number of recording layers can be increased. Even when the recording layer is provided, accurate recording layer discrimination can be realized.

(Form using a layer discrimination pattern modulated by pulse width)
A sixth embodiment of the present invention will be described with reference to FIG. In this embodiment, the layer discrimination pattern is different from the above-described example. Except this point, the second embodiment is the same as the first to sixth embodiments.

  FIG. 21 shows the mark arrangement on the disk surface from the top, the waveform of the reproduction signal obtained by scanning this area with the light spot, and the band-limited reproduction signal obtained by passing this reproduction signal through the filter circuit. Represents a waveform.

  The mark arrangement gives a mark length and a space length following a waveform obtained by pulse width modulation (PWM) of a sine wave. Note that pulse density modulation may be used instead of pulse width modulation.

  The reproduction signal is a binary signal in which a sine wave is subjected to pulse width modulation (PWM) according to the mark arrangement. This waveform has the same fundamental frequency component as the frequency of the sine wave before modulation, and a spectrum with a particularly strong peak at the frequency corresponding to the pulse interval after modulation. By reducing the pulse interval as much as possible, The frequency of the peak of the component and the peak of the peak caused by the modulation can be separated.

  When a binary signal obtained in this manner is used to suppress a peak caused by modulation in the filter circuit, a sine wave having the same frequency component as that of the reproduction signal before modulation is obtained.

  When such a layer discrimination pattern is applied, a layer discrimination signal with less harmonics can be obtained compared to the case where a pattern consisting of a single length mark and space combination is applied. Can suggest errors in discrimination in the layer discrimination means of Example 5.

  According to the first to sixth embodiments described above, a pattern that enables layer discrimination can be formed on each recording layer of the grooveless disc in a desired recording layer without erroneous layer discrimination even in an unrecorded state. Is possible. In addition, after the pattern is formed, it is possible to accurately determine the layer by referring to the pattern.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

  Furthermore, each of the above-described configurations may be configured such that a part or all of the configuration is configured by hardware, or is realized by executing a program by a processor. Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

  Further, the recording medium is not limited to the optical disc, and the present invention can be applied to various recording media.

101 Optical disk device
102 optical disc
201 controller
203 Optical pickup
301 Laser driver
302 Laser diode
309 Spherical aberration correction element
311 Objective lens
312 Actuator
314 Detector
315 laser diode
323 detector
501 Host interface means
502 Buffer memory control means
503 buffer memory
504 microprocessor
505 layer discrimination means
507 Address discrimination means
508 Recording timing signal generation means
513 Playback data demodulation means
514 Recording data modulation means
515 Light emission signal generation means
516 Wobble detection means
517 PLL
518 Unrecorded discriminating means

Claims (27)

It has an annular shape,
A plurality of recording layers having no guide groove structure;
A guide layer having a guide groove structure;
Have
The inner radius of the recording layer is different for each recording layer,
The order of the inner radius of the recording layer is constant over the entire rotation angle,
The inner radius of the guide layer is smaller than any recording layer,
2. An optical disc according to claim 1, wherein address information indicating the position of the board surface is recorded on the guide layer. Each recording layer has a layer discrimination area where information for layer discrimination is recorded,
The boundary on the inner circumference side of the layer discrimination region exists at a radius position smaller than the next smaller inner radius of the recording layer,
The boundary on the outer peripheral side of the layer discriminating region exists in a radius position larger than the maximum inner radius position in any recording layer,
The optical disk according to claim 1. It has an annular shape,
A plurality of recording layers having no guide groove structure;
A guide layer having a guide groove structure;
Have
The outer radius of the recording layer is different for each recording layer,
The order of the outer radius of the recording layer is constant over the entire rotation angle,
The outer radius of the guide layer is larger than any recording layer,
2. An optical disc according to claim 1, wherein address information indicating the position of the board surface is recorded on the guide layer. Each recording layer has a layer discrimination area where information for layer discrimination is recorded,
The boundary on the outer peripheral side of the layer discriminating region exists at a radius position that is larger than the outer radius next to the recording layer,
The boundary on the inner peripheral side of the layer discrimination region exists in a radius position smaller than the maximum outer radius position in any recording layer,
The optical disk according to claim 3. A user data area for recording user data received by the optical disc recording apparatus from the host device;
Having a second layer discrimination region,
A user data area exists in a radius between the layer discrimination area and the second layer discrimination area;
5. The optical disc according to claim 2, wherein there is a radius position range in which the second layer discrimination region exists in common to all recording layers. In the layer discriminating area, a mark having a constant length regardless of the radius in the same recording layer, and
There is a layer discrimination pattern in which spaces having the same length as the mark are alternately arranged in the circumferential direction,
The length of the mark and space is different for each recording layer,
The optical disc according to claim 2, claim 4, or claim 5. In the layer discrimination area, recording marks are arranged at equal intervals in the circumferential direction,
The length of the recording mark is increased or decreased with a certain number of periods,
A layer discriminating pattern in which the increase / decrease period of the recording mark length is different for each recording layer is recorded,
The optical disc according to claim 2, claim 4, or claim 5. In the layer discrimination region, there is a layer discrimination pattern in which a mark having a length proportional to a radial position and a space having the same length as the mark are repeatedly arranged in the circumferential direction,
6. The optical disk according to claim 2, wherein a ratio between the length of the mark and the space and a radial position differs for each recording layer. A layer discrimination information recording method for recording layer discrimination information on an optical disc having a plurality of recording layers having no guide groove structure,
The optical disc further includes a guide layer having a structure of the recording area and a guide groove, the inner radius is different for each recording layer, and the order of the inner radius for each recording layer is constant over the entire circumference. Has the structure
A moving step of moving a radial position for irradiating the laser beam;
A focusing step for focusing the laser beam on the recording layer;
A recording step for recording layer discriminating information for discriminating the recording layer on the focusing recording layer;
For the plurality of recording layers, and the moving step comprises:
If there are multiple recording layers where layer discrimination information is not recorded,
If only one of them moves to the position between the smallest inner radius and the second smallest inner radius, the inner radial position of the recording layer and the radial position Ri determined on the outer peripheral side of the recording layer. Move between
The focusing step includes
Following the moving step, focusing is performed on the recording layer having the smallest inner radius among the recording layers in which no layer discrimination information is recorded,
The recording step includes
A radius further on the inner circumference side than the second smallest inner radius position in a state where tracking servo is performed on the guide groove by the guide layer laser beam having the same optical axis as the laser beam for focusing on the recording layer. From the position, the layer discrimination information is recorded over a range from the radial position Ri to the radial position Ro determined on the outer peripheral side,
When the recording of the layer discrimination information of the layer is completed, the process returns to the step again,
A layer discrimination information recording method, wherein the layer discrimination information is recorded on all the recording layers in an earlier order as the recording layer has a smaller inner radius position. A layer discrimination information recording method for recording layer discrimination information on an optical disc having a plurality of recording layers having no guide groove structure,
The optical disc further includes a guide layer having a structure of the recording area and a guide groove, and the outer radius is different for each recording layer, and the order of the outer radius for each recording layer is constant over the entire circumference. Has the structure
A moving step of moving a radial position for irradiating the laser beam;
A focusing step for focusing the laser beam on the recording layer;
A recording step for recording layer discriminating information for discriminating the recording layer in the focusing recording layer;
For the plurality of recording layers,
The moving step includes
If there are multiple recording layers where no layer discrimination pattern is recorded,
If only one of them exists between the largest outer radius position and the second largest outer radius position, the outer radius position of the recording layer and the radius determined on the inner circumference side of the recording layer. Move between positions Ri,
The focusing step includes
Following the step of moving the radius position, focusing is performed on the recording layer having the largest outer radius among the recording layers in which the layer discrimination information is not recorded,
The recording step includes
From the radial position larger than the second largest outer radius in a state where the tracking servo is performed on the guide groove by the guide layer laser light having the same optical axis as the laser light for focusing on the recording layer, the radius Recording the layer discrimination information over a range up to the radial position Ro determined on the inner circumference side from the position Ri,
When the recording of the layer discrimination information of the layer is completed, by returning to the moving step again,
A layer discrimination information recording method, wherein the layer discrimination information is recorded on all the recording layers in an earlier order as a recording layer having a larger outer radius position. After completing the step of recording the layer discriminating information on the focusing recording layer,
While returning to the moving step again,
The optical disc recording apparatus further comprises a step of recording second layer discrimination information on the opposite side across the user data area for recording user data received from the host device.
The layer discrimination information recording method according to claim 9 or 10. During the rotation of the optical disc at a constant linear velocity, the recording step is performed by emitting the laser light with an intensity that changes with a specific period with respect to the recording layer that is focused,
The layer discrimination information recording method according to any one of claims 9 to 11. Performing the recording step by causing the laser beam to be emitted with an intensity that changes in a cycle proportional to the radial position with respect to the focusing recording layer while the optical disc is rotated at a constant rotation speed. Features
The layer discrimination information recording method according to any one of claims 9 to 11. While the optical disk is rotated at a constant rotation speed, the recording step is performed by emitting the laser beam with an intensity that changes with a specific period with respect to the focusing recording layer,
The layer discrimination information recording method according to any one of claims 9 to 11. The guide groove is oscillated in a radial direction with a constant length in the circumferential direction as a period, and a signal obtained by detecting the oscillation amount in a state where tracking servo is performed on the guide groove by the guide layer laser beam. Based on the generated clock, the recording step is performed by changing the emission intensity of the laser beam,
The layer discrimination information recording method according to any one of claims 9 to 14. In the guide layer, address information indicating a position on the surface of the optical disc is recorded,
The moving step is performed based on address information detected by using a guide groove laser beam for focusing on the guide layer, which has the same optical axis as the laser beam for focusing on the recording layer. The layer discrimination information recording method according to any one of claims 9 to 15. After the focusing step,
The method further includes the step of determining the recording state of the area in which the layer discrimination information is recorded, and when it is determined that the recording state is not an unrecorded state, the focusing step is executed again,
When it is determined that it is in an unrecorded state, the recording step is performed,
The layer discrimination information recording method according to any one of claims 9 to 16. A step of focusing a laser beam on the layer discriminating region on the recording layer with respect to the optical disc according to claim 6 or 7,
Controlling the rotational speed so that the linear speed at which the light spot by the laser beam scans on the board surface is constant;
Discriminating a recording layer focused on the laser beam based on a frequency component of the return light amount obtained from the light spot and fluctuating. The step of focusing laser light on the layer discrimination region on the recording layer with respect to the optical disc according to claim 8,
Controlling the rotational speed so that the rotational speed of the optical disc is constant;
Discriminating a recording layer focused on the laser beam based on a frequency component of the return light amount obtained from the light spot and fluctuating. The step of focusing laser light on the layer discrimination region on the recording layer for the optical disc according to claim 6 or 7,
And a step of discriminating a recording layer focused on the laser beam based on a ratio between a frequency at which a return light amount obtained from the light spot fluctuates and a rotation speed for rotating the optical disc. The layer discrimination method according to any one of claims 18 to 20,
Determining the recording layer comprises:
A high frequency cutoff frequency greater than the maximum of the fundamental frequencies of the signals obtained from the layer discrimination pattern of all recording layers and the fundamental frequency of the layer discrimination signals of all recording layers with respect to the signal for detecting the return light amount Filtering with a filter circuit having a low-pass cutoff frequency lower than the smallest one of
Count the period when the amplitude of the signal obtained from the filter circuit is zero level,
Each of the counted period is compared with the same number of reference values as the number of recording layers determined corresponding to the layer discrimination information of all recording layers,
A layer discrimination method, wherein, based on the comparison result, a recording layer corresponding to the reference value closest to the counted cycle is discriminated as a recording layer in which the laser beam is focused. The layer discrimination method according to any one of claims 18 to 20,
Determining the recording layer comprises:
The frequency is determined corresponding to the layer discrimination pattern of all recording layers, and the same number of sine wave signals and cosine wave signals as the number of recording layers are generated,
For the signal detecting the return light amount,
It has a high frequency cutoff frequency that is higher than the maximum of the fundamental frequencies of the layer discrimination signals of all recording layers, and a low frequency cutoff frequency that is lower than the minimum of the fundamental frequencies of the layer discrimination signals of all recording layers. Filter using a filter circuit,
For the signal obtained from the filter circuit, the amplitude is made constant using AGC,
For the signal from the AGC, by performing quadrature detection using the sine wave signal and the cosine wave signal as a reference signal, power at the same frequency as the reference signal is detected,
A layer discrimination method comprising: discriminating a recording layer corresponding to the reference signal under a condition where the largest power is detected as a recording layer in which the laser beam is focused. In the layer discrimination method according to claim 18 or 20,
Determining the recording layer comprises:
For the signal detecting the return light amount,
It has a high frequency cutoff frequency that is higher than the maximum of the fundamental frequencies of the layer discrimination signals of all recording layers, and a low frequency cutoff frequency that is lower than the minimum of the fundamental frequencies of the layer discrimination signals of all recording layers. Using the signal filtered with the filter circuit,
Sampling the signal obtained from the filter circuit at a constant period,
Storing the sampled signal in a waveform memory;
When a certain amount of sampling is completed, the waveform data is read from the waveform memory,
Perform fast Fourier transform based on the waveform data,
Detecting the maximum value of the spectrum obtained as a result of the fast Fourier transform;
A layer discrimination method, wherein the recording layer is made a layer discrimination result based on a frequency at which the maximum value is obtained. An optical disc recording / reproducing apparatus according to claim 6,
An optical pickup that irradiates the optical disk with laser light and generates a signal based on the laser light reflected by the optical disk;
A layer discriminating unit that inputs a return light signal proportional to the intensity of the return light obtained by irradiating the layer discrimination region of the optical disc with laser light;
The layer discriminating unit discriminates a recording layer irradiated with a laser beam based on a period or a frequency at which the intensity of the return optical signal changes;
Optical disc recording / reproducing apparatus. The layer discriminating means includes a filter circuit,
Mark edge detection means;
An edge interval counter;
A count value holding means;
Averaging means;
A comparison means;
With
The filter circuit has the return optical signal as an input,
It has a higher cutoff frequency that is higher than the maximum fundamental frequency of the layer discrimination signal for all recording layers, and a lower cutoff frequency that is lower than the lowest fundamental frequency of the layer discrimination signals for all recording layers. And
The mark edge detection means generates a mark edge detection signal that detects the timing at which the amplitude value of the return optical signal crosses the center level,
The edge interval counter transfers the value to the count value holding means at the subsequent stage and clears the count value at the generation timing of the mark edge detection signal,
By counting the period between the mark edges by incrementing the value at a constant period between the generation timing of the mark edge detection signal,
The count value holding means updates the value to the value transferred from the edge interval counter at the generation timing of the mark edge detection signal, and holds the value until the next generation timing of the mark edge detection signal,
The averaging means obtains an average value of the count value holding means by a low-pass filter circuit,
The comparison means compares the average value with the same number of reference values as the number of recording layers determined corresponding to the layer discrimination pattern of all recording layers, and selects the reference value closest to the average value,
25. The optical disc recording / reproducing apparatus according to claim 24, wherein the recording layer is discriminated based on the selected reference value. The layer discriminating means includes a filter circuit and
AGC circuit,
Layer discrimination reference signal generating means corresponding to each recording layer;
Orthogonal detection means corresponding to each recording layer;
Maximum value judging means;
With
The filter circuit has the return optical signal as an input,
It has a higher cutoff frequency that is higher than the maximum fundamental frequency of the layer discrimination signal for all recording layers, and a lower cutoff frequency that is lower than the lowest fundamental frequency of the layer discrimination signals for all recording layers. And
The AGC circuit amplifies the output amplitude of the filter circuit to be constant,
The layer discrimination reference signal generating means corresponding to each recording layer generates a sine wave and a cosine wave having a frequency unique to each recording layer,
The frequency unique to the recording layer is the ratio of the linear velocity to the circumferential period of the layer discrimination pattern on the disc,
The quadrature detection means corresponding to the recording layer has a frequency unique to the recording layer included in the output signal of the AGC circuit by quadrature detection using a sine wave and a cosine wave having a frequency unique to the recording layer as reference signals. Find the power of the component,
25. The optical disk recording according to claim 24, wherein the maximum value determination means determines the maximum power value detected by the orthogonal detection means, and determines the recording layer from the frequency at which the power value is obtained. Playback device. The layer discriminating means includes a filter circuit,
AGC circuit,
A / D conversion means,
Waveform memory,
With a microprocessor,
The filter circuit has the return optical signal as an input,
It has a higher cutoff frequency that is higher than the maximum fundamental frequency of the layer discrimination signal for all recording layers, and a lower cutoff frequency that is lower than the lowest fundamental frequency of the layer discrimination signals for all recording layers. And
The AGC circuit amplifies the output amplitude of the filter circuit to be constant,
The A / D conversion means samples the signal from the AGC circuit at a constant clock timing and outputs it as a digital signal,
The waveform memory stores the digital signal from the A / D conversion means,
The microprocessor performs a fast Fourier transform on the waveform data stored in the waveform memory to obtain a spectrum,
The recording layer is discriminated based on the frequency at which the value of the spectrum is maximum,
25. An optical disk recording / reproducing apparatus according to claim 24.

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