WO2014054246A1 - 情報再生装置及び情報再生方法 - Google Patents
情報再生装置及び情報再生方法 Download PDFInfo
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- WO2014054246A1 WO2014054246A1 PCT/JP2013/005686 JP2013005686W WO2014054246A1 WO 2014054246 A1 WO2014054246 A1 WO 2014054246A1 JP 2013005686 W JP2013005686 W JP 2013005686W WO 2014054246 A1 WO2014054246 A1 WO 2014054246A1
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- adaptive equalization
- equalization filter
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- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
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Definitions
- the present invention forms an optical laser spot on one recording track on an information recording medium in which data is recorded on a plurality of adjacent recording tracks, and is based on the reflected light from the optical laser spot.
- An information reproducing apparatus and an information reproducing method for reproducing the data are provided.
- optical disks such as DVD or Blu-ray (registered trademark) Disc (hereinafter referred to as BD) are used as information recording media for storing video or data. These optical disks have higher storage reliability than a hard disk drive (hereinafter referred to as an HDD) or a magnetic tape. Therefore, applications of optical disks are being expanded from applications of recording AV (Audio Video) data such as conventional video or audio, etc. to applications of storing data for a long time.
- AV Audio Video
- optical disks have a storage reliability of 50 years or more, and in terms of long-term storage of data, have a storage reliability of 10 times or more as compared with the lifetime of about 5 years of HDD. Therefore, by moving data for long-term storage from the HDD to the optical disk, it is possible to achieve both long-term storage reliability and reduction of storage cost.
- optical disks that do not require power at the time of data storage can reduce carbon dioxide emissions as green storage as compared to HDDs that consume power at the time of data storage, and power consumption of data centers that has become a major issue in recent years It also leads to the reduction of
- the volume of data that can be stored per volume is about 1/3 of that of HDDs. Therefore, the storage space of the optical disk at the time of data storage is required more than that of the HDD, and especially in applications where cost requirements for the storage space such as a data center are high, it is required to improve the recording density per volume of the optical disk. ing.
- the diffracted light from the groove necessary for trace control of the groove in which the light beam is a track becomes small, and the light beam can not trace the track.
- the wavelength of the light beam irradiated to the optical disk is ⁇ and the numerical aperture of the lens forming the light beam is NA
- the groove or land distance L is smaller than ⁇ / NA ⁇ 0.6
- the limit of the track interval L at which diffracted light can be detected is 650 nm.
- a track pitch of 615 nm is realized to improve the track density (see, for example, Patent Document 1).
- FIG. 31 is a view for explaining the format of another conventional optical disc.
- a recording track 1502 is formed on an optical disc 1501 by a groove.
- Data is recorded in the data recording area 1503, and address information for accessing the data recording area 1503 is recorded in the address information areas 1504, 1505 and 1506.
- the address information is arranged in the same area as the recording data, and the recording data is recorded superimposed on the address information.
- One recording data is recorded in an area constituted by three pieces of address information AD1 (Z05), AD2 (Z06) and AD3 (Z07), and an area constituted by three pieces of address information is a recording unit of data. It becomes a certain data recording area 1503.
- the integral multiple of the length of the data recording area 1503 composed of three pieces of address information does not match the length of the circumference of the track. Therefore, as shown in FIG. 31, the positions on the circumference of the data recording area 1503 are arranged to be shifted for each rotation of the optical disc between the adjacent recording tracks.
- one bit of address information AD1, AD2, AD3 is recorded by partially changing the waveform of the groove wobbling at a constant cycle.
- An area 1507 shown enlarged in the lower part of FIG. 31 is subjected to modulation called MSK (Minimum Shift Keying) in a portion corresponding to the address bit.
- MSK Minimum Shift Keying
- the position of the track where the data is recorded is specified based on the address information AD1, AD2, AD3, and the recording of the data is started, or the position of the track where the data is recorded is specified. Start playing back the data.
- FIG. 32 is a diagram showing the configuration of a conventional information recording and reproducing apparatus.
- the optical disc 101 has a wobbling track as shown in FIG. Information is recorded on the track.
- the optical head 103 irradiates the optical disk 101 with a light beam, and outputs an electrical signal according to the amount of light reflected from the optical disk 101.
- the photodetector of the optical head 103 generates a wobble signal, a data signal and a servo error signal. The photodetector will be described later.
- the spindle motor 102 rotates the optical disc 101.
- the servo controller 104 controls the position at which the optical head 103 irradiates the track of the optical disk 101 with the light beam and the number of rotations of the spindle motor 102 based on the servo error signal.
- the analog processing unit 105 performs HPF (High Pass Filter) processing for suppressing a predetermined DC fluctuation on a data signal from the optical head 103, and LPF (Low Pass Filter) processing for removing high frequency noise unnecessary for data reproduction.
- HPF High Pass Filter
- LPF Low Pass Filter
- An AGC Automatic Gain Control
- AD conversion process for converting an analog signal into a digital signal using a clock signal supplied from a data PLL (Phase Locked Loop) circuit 106 are performed.
- the data PLL circuit 106 generates a clock signal synchronized with the reproduction signal from the data signal processed by the analog processing unit 105.
- the adaptive equalization filter 107 is, for example, an FIR (finite length impulse response) type filter, and the filter coefficients are adjusted so that the data signal processed by the analog processing unit 105 has a desired PR (partial response) characteristic. Update adaptively.
- the data decoder 108 decodes the output of the adaptive equalization filter 107 into binary digital data. Although not shown here, the recorded data is reproduced by performing demodulation processing and error correction processing on the decoding result of the data decoder 108.
- the PR method an optimum method may be selected according to the recording code and the recording linear density.
- the PR method is, for example, the PR1221 method or the PR12221 method.
- the PR equalization error detector 109 generates a PR equalization error signal from the difference between the desired PR expected value waveform generated from the binary digital data decoded by the data decoder 108 and the output waveform of the adaptive equalization filter 107. Generate The adaptive equalization filter 107 changes the filter coefficients so that the PR equalization error signal generated by the PR equalization error detector 109 becomes smaller.
- the analog processing unit 111 performs HPF processing for suppressing a predetermined DC fluctuation with respect to the wobble signal from the optical head 103, LPF processing for removing high frequency noise unnecessary for reproduction of the wobble signal, and suppresses amplitude fluctuation of the wobble signal. And AGC conversion processing for converting an analog signal into a digital signal using a clock signal supplied from the wobble PLL circuit 113.
- a band pass filter (BPF) 112 extracts a signal of a predetermined frequency band from the wobble signal.
- the wobble PLL circuit 113 generates a clock signal synchronized with the wobble signal from the wobble signal processed by the BPF 112.
- the address demodulator 114 demodulates the address information from the wobble signal sampled on the basis of the clock signal generated by the wobble PLL circuit 113.
- the system controller 115 performs overall control of each block and controls communication with the host.
- the recording data modulator 116 modulates user data into a recording data pattern that can be recorded on the optical disc 101.
- the laser driver 117 converts the recording data pattern modulated by the recording data modulator 116 into an optical pulse for forming a mark accurately on the optical disc 101, and outputs the light pulse to the optical head 103.
- the laser light source of the optical head 103 emits a laser beam corresponding to the light pulse.
- a host interface (I / F) 118 exchanges recording data and reproduction data with the host.
- FIG. 33 is a view showing how a laser irradiation spot scans a recording track.
- recording marks 1704 and spaces 1705 are formed on three recording tracks 1701, 1702, and 1703, and a laser irradiation spot 1706 scans in the direction of the arrow on the middle recording track 1702.
- FIG. 34 is a diagram showing the configuration of a conventional photodetector 1800 for reproducing recorded data.
- the photodetector 1800 is divided into four light receiving units 1801, 1802, 1803, 1804, amplifiers 1805, 1806, 1807, 1808 for amplifying output signals from the light receiving units 1801, 1802, 1803, 1804, an amplifier 1805, And an adder 1809 that adds all of the signals A, B, C, and D output from the circuits 1806, 1807, and 1808.
- a reproduction data signal is generated based on the output from the adder 1809.
- wobble signals which are reproduction signals of wobbling data of a track
- the light receiving units 1801, 1802, 1803 and 1804 of the photodetector 1800 are detected by the light receiving units 1801, 1802, 1803 and 1804 of the photodetector 1800 as balanced signals on the left and right with respect to the track scanning direction. Therefore, the wobble signal does not add all of the A, B, C, and D signals output from the four amplifiers 1805, 1806, 1807, and 1808, but instead adds the A signal from the amplifier 1805 and the signal from the amplifier 1806. It is detected by subtracting the C signal from the amplifier 1807 and the D signal from the amplifier 1808 from the value obtained by adding the B signal.
- the recording track as shown in FIG. 33 is irradiated with laser light, and the laser light is scanned in the direction of the arrow shown in FIG. 34, and the reflected light is received by the light detector as shown in FIG. A signal is reproduced.
- the host I / F 118 receives a recording request, recording data, and a logical address from the host.
- the system controller 115 starts the recording operation of the information recording and reproducing apparatus.
- the system controller 115 converts a logical address into a physical address on the optical disc 101 and controls the spindle motor 102 and the servo controller 104 to move the optical head 103 to the vicinity of the designated address.
- the address demodulator 114 demodulates the physical address information near the designated address from the wobble signal.
- the system controller 115 confirms the position of the optical head 103 based on the physical address information demodulated by the address demodulator 114.
- the system controller 115 calculates the difference between the demodulated physical address and the designated address, and moves the optical head 103 by track jump.
- the system controller 115 causes a track jump to an address slightly before the designated address so that recording can be started from the designated address, moves the optical head 103 along the track to the designated address, and records from the designated address.
- the system controller 115 causes the recording data modulator 116 to modulate the recording data from the host, sets the optimum recording power and recording pulse information in the laser driver 117, emits a laser from the designated address position, and starts recording. And execute recording of the specified recording data.
- the host I / F 118 receives a playback request and a logical address from the host.
- the system controller 115 starts the reproduction operation of the information recording and reproducing apparatus.
- the system controller 115 converts a logical address into a physical address on the optical disc 101 and controls the spindle motor 102 and the servo controller 104 to move the optical head 103 to the vicinity of the designated address.
- the address demodulator 114 demodulates the physical address information near the designated address from the wobble signal.
- the system controller 115 confirms the position of the optical head 103 based on the physical address information demodulated by the address demodulator 114. At this time, when the address information superimposed on the recorded data is reproduced by the data decoder 108, the address information reproduced by the data decoder 108 may be used as a reference.
- the system controller 115 calculates the difference between the demodulated physical address and the designated address, and moves the optical head 103 by track jump.
- the system controller 115 causes the track jump to an address slightly before the designated address so that the reproduction can be started from the designated address, moves the optical head 103 along the track to the designated address, and reproduces from the designated address.
- the system controller 115 processes the data signal by the analog processing unit 105, the adaptive equalization filter 107, and the data decoder 108, reproduces the recording data, and transfers the reproduction data to the host via the host I / F 118.
- the light receiving area of the light detector is divided into three on the recording track in the direction in which the light spot scans.
- the reflected light from the recording track on which the light spot is irradiated is received by the main light receiving area, and the reflected light from the track adjacent to the recording track is received by the two sub light receiving areas.
- the signal processing unit equalizes the output signal from the main light receiving area so as not to be correlated with the output signal from the sub light receiving area.
- the output signal from the main light receiving area is not interfered by the output signal from the sub light receiving area, the influence of crosstalk can be eliminated.
- the data detection device performs crosstalk cancellation signal processing ((1) synchronization of reproduction signals of adjacent tracks with channel clock accuracy, and (2) frequency of crosstalk from adjacent tracks to main reproduction tracks.
- a plurality of adaptive equalizer units are provided.
- As a reproduction information signal read from the recording medium a reproduction information signal from a target track targeted for data detection, and a reproduction information signal from a near track adjacent to the target track which is a crosstalk component with respect to the reproduction information signal Of each is input to each of the adaptive equalizer units.
- the data detection apparatus performs binarization processing on the multi-input adaptive equalizer unit that calculates the output of each adaptive equalizer unit and outputs the result as an equalization signal, and the equalization signal output from the multi-input adaptive equalizer unit, and performs binary processing.
- Equalization error is determined from a binarization unit for obtaining data, an equalization target signal obtained based on a binary detection result of the binarization unit, and an equalization signal output from the multi-input adaptive equalizer unit, And an equalization error operation unit that supplies equalization errors to each adaptive equalizer unit as tap coefficient control signals for adaptive equalization.
- the data detection device includes a memory unit that stores the reproduction information signal read from the recording medium.
- the memory controller reads the reproduction information signal from the target track and the reproduction information signal from the close track from the memory unit and supplies the read information signal to each of the plurality of adaptive equalizer units.
- the data detection device detects the phase difference of each reproduction information signal read from the memory unit and input to the plurality of adaptive equalizer units, and based on the detected phase difference, each reproduction information signal from the memory unit And a phase difference detection unit that outputs a correction signal for correcting the read timing of the image.
- the multi-input adaptive equalizer unit has three adaptive equalizer units. In each of the three adaptive equalizer units, the reproduction information signal from the target track, the reproduction information signal from the adjacent track adjacent to one side of the target track, and the reproduction information signal from the adjacent track adjacent to the other side of the target track And are input respectively. Also, the multi-input adaptive equalizer unit performs partial response equalization processing on the reproduction information signal from the target track.
- the binarization unit performs maximum likelihood decoding processing as binarization processing on the equalization signal of the multi-input adaptive equalizer unit.
- the equalization error calculation unit performs equalization error calculation by using the equalization target signal obtained by the convolution process of the binary detection result by maximum likelihood decoding and the equalization signal output from the multi-input adaptive equalizer unit. Ask.
- the reproduction signal includes a reproduction signal (RF signal) obtained by reproducing the recorded information, and an address signal added as address information by wobbling the track according to a predetermined method.
- Crosstalk cancellation signal processing has been proposed to solve the crosstalk problem for RF signals (see, for example, Patent Document 4, Patent Document 5 and Patent Document 6).
- the points of performance improvement in crosstalk cancellation signal processing are (1) synchronization of reproduction signals of adjacent tracks with channel clock accuracy, and (2) reproduction of frequency characteristics of crosstalk affecting adjacent tracks from main tracks. Is a cancellation process in consideration of This is because the amount of crosstalk from the adjacent track differs depending on the recording mark length, and a simple subtraction process can not provide a sufficient performance improvement.
- Patent Document 5 Since the crosstalk cancellation signal processing proposed in Patent Document 5 uses a photodetector in which the light receiving area is divided into three in the direction in which the light spot scans on the recording track, the reproduction recorded in the target track is performed. A signal and a crosstalk signal from an adjacent track can be detected simultaneously. Therefore, in patent document 5, the subject of the synchronization of the reproduction
- the crosstalk cancellation signal processing proposed in Patent Document 6 includes (1) synchronization of reproduction signals of adjacent tracks with channel clock accuracy, and (2) frequency characteristics of crosstalk affecting adjacent reproduction tracks to main reproduction tracks. Is a cancellation process in consideration of the reproduction of In Patent Document 6, in order to synchronize the reproduction signal of the adjacent track in (1), the reproduction signal of the adjacent track is held in the memory at a predetermined timing. Due to such a configuration, Patent Document 6 has the following four major problems.
- An optical disc such as a RAM disc that records data on both land and groove, and by having a CAPA address at the middle of the land and groove, the land and the optical disc do not have a single spiral configuration.
- an optical disc having a double spiral configuration in which data is recorded on both sides of the groove it is necessary to perform track jump or to have a configuration provided with a plurality of optical pickups in order to obtain information on adjacent tracks. is there.
- a new problem arises that the transfer rate of the system is not improved. Further, in the configuration provided with a plurality of optical pickups, the cost of the system is increased.
- Patent documents 4, 5 and 6 do not describe the crosstalk cancellation signal processing of the address signal.
- the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an information reproduction apparatus and an information reproduction method capable of improving reproduction performance.
- An information reproducing apparatus forms one optical laser spot on one recording track on an information recording medium in which data is recorded on a plurality of adjacent recording tracks, and the optical disc
- An information reproducing apparatus for reproducing the data based on reflected light from a laser spot, the first light receiving unit for receiving the reflected light at the central part of the recording track, and the information recording medium with respect to the central part
- An optical detector divided by a dividing line parallel to the recording track scanning direction, and an output signal from the first light receiving unit;
- a data decoder for decoding the reproduced data based on the output waveform from the filter.
- the signal component of the own track scanned by the center of the optical laser spot and the crosstalk component from the track adjacent to the own track are detected from one optical laser spot, and a large-scale circuit is implemented. Without removing the crosstalk component having a predetermined frequency, equalization can be performed to a desired PR characteristic, so that the error rate of the reproduction data can be reduced, and the reproduction performance can be improved. .
- Embodiment 1 of this invention It is a figure which shows the structure of the information recording and reproducing apparatus in Embodiment 1 of this invention. It is a figure which shows the structure of the optical detector for reproduction data detection in Embodiment 1 of this invention. It is a figure which shows the structure of the optical detector for wobble detection in Embodiment 1 of this invention. It is a figure which shows the structure of the adaptive equalization filter in Embodiment 1 of this invention. It is a figure which shows the crosstalk amount from an adjacent track. It is a figure which shows the tap coefficient of the adaptive equalization filter which processed A + D signal, and the tap coefficient of the adaptive equalization filter which processed B + C signal. It is the figure which showed the frequency characteristic of the tap coefficient of FIG.
- Embodiment 2 of this invention It is a figure which shows the structure of the information recording and reproducing apparatus in Embodiment 2 of this invention. It is a figure which shows the relationship between the tap coefficient of an adaptive equalization filter in Embodiment 2 of this invention, and a coefficient value. It is a figure which shows the structure of the information recording and reproducing apparatus in Embodiment 3 of this invention. It is a figure which shows the structure of the optical detector of the optical head in Embodiment 3 of this invention. It is a figure which shows the structure of the photodetector in the 1st modification of Embodiment 3 of this invention. It is a figure which shows the structure of the information recording and reproducing apparatus in the 1st modification of Embodiment 3 of this invention.
- FIG. 18 is a diagram showing a configuration of a light detector in a second modified example of the third embodiment of the present invention. It is a figure which shows the structure of the information recording and reproducing apparatus in the 2nd modification of Embodiment 3 of this invention.
- (A) is a diagram showing a three-divided light receiving unit and a four-divided light receiving unit when no lens shift occurs
- (B) is a three-divided light receiving unit when a predetermined amount of lens shift occurs
- an optical head When an optical head irradiates a laser beam to a recording track, it is a figure which shows typically three light-receiving parts of an optical detector which light-receives reflected light from a recording track, and three tracks.
- a waveform convolution and M ij characteristics and track signals a diagram comparing the optical simulation waveform of the signal S 0.
- a waveform convolution and M ij characteristics and track signals a diagram comparing the optical simulation waveform of the signal S 1.
- a waveform convolution and M ij characteristics and track signals a diagram comparing the optical simulation waveform of a signal S 2. It is a figure which shows the structure of the information recording and reproducing apparatus in Embodiment 4 of this invention. It is a figure which shows the frequency characteristic of the wobble signal in Embodiment 4 of this invention. It is a figure which shows the structure of the information recording and reproducing apparatus in Embodiment 5 of this invention. It is a figure which shows the structure of the information recording medium in Embodiment 5 of this invention. It is a schematic diagram for demonstrating the data arrangement structure of the address information in Embodiment 5 of this invention. In Embodiment 5 of this invention, it is a figure which shows the structure of the address information comprised with several address unit bit.
- FIG. 1 is a diagram showing the configuration of an information recording and reproducing apparatus in the first embodiment of the present invention.
- FIG. 2 is a view showing a configuration of an optical detector for reproduction data detection in Embodiment 1 of the present invention.
- FIG. 3 is a view showing the configuration of the optical detector for wobble detection in Embodiment 1 of the present invention.
- the information recording / reproducing apparatus forms one optical laser spot on one recording track for an optical disc 101 in which data is recorded on a plurality of adjacent recording tracks, and based on the reflected light from the optical laser spot Play back the data.
- the information recording / reproducing apparatus shown in FIG. 1 includes a spindle motor 102, an optical head 103, a servo controller 104, an analog processing unit 105, a data PLL circuit 106, an adaptive equalization filter 107, a data decoder 108, and a PR equalization error detector. 109, analog processing unit 111, BPF 112, wobble PLL circuit 113, address demodulator 114, system controller 115, recording data modulator 116, laser driver 117, host I / F 118, analog processing unit 119, adaptive equalization filter 120, and An adder 121 is provided.
- the reproduction data detection optical detector 200A and the wobble detection optical detector 200B provided in the optical head 103 according to the first embodiment are configured as shown in FIG. 2 and FIG.
- the light receiving unit for receiving the laser light is divided by a dividing line parallel to the track scanning direction.
- the track scanning direction is a direction perpendicular to the radial direction of the optical disc 101.
- the optical detector 200A for detecting reproduced data is provided with four light receiving units 201, 202, 203, 204 divided by a dividing line parallel to the track scanning direction, and light reflected from the information recording medium
- the spot 211 is illuminated as shown by the dotted line in FIG.
- the width (length in the direction perpendicular to the track scanning direction) of the four light receiving units 201, 202, 203, and 204 is optimally designed in consideration of the crosstalk cancellation effect, the noise of the reproduction signal, and the frequency characteristic deterioration. Choose a value.
- the widths of the light receiving units 201, 202, 203, and 204 may be divided at a ratio of 2: 1: 1: 2.
- the light receiving units 202 and 203 receive the reflected light at the central portion of the recording track.
- the light receiving units 201 and 204 receive reflected light of a portion adjacent to the central portion in the radial direction of the optical disc 101.
- the signals output from the four light receiving units 201, 202, 203 and 204 are amplified by the amplifiers 205, 207, 208 and 206, respectively. Further, the signals output from the amplifiers 205 and 206 are added by the adder 209, and the signals output from the amplifiers 207 and 208 are added by the adder 210.
- the signals output from the amplifiers 205, 206, 207, and 208 are defined as the A signal, the D signal, the B signal, and the C signal, respectively, and the output of the adder 209 is the A + D signal. Is a B + C signal.
- the B + C signal is a reproduction signal of a region near the center of the reproduction laser spot
- the A + D signal is a reproduction signal of a region near the end of the reproduction laser spot.
- the amplification amounts of the four amplifiers 205, 206, 207, and 208 may be selected as optimum design values. For example, the amplification amounts of the amplifiers 205, 206, 207, and 208 may be set to a ratio of 6: 1: 1: 6.
- the light receiving units 201, 202, 203, and 204 in FIG. 3 have the same configuration as that of FIG.
- the signals detected by the four light receiving units 201, 202, 203 and 204 are amplified by the amplifiers 212, 214, 215 and 213, respectively.
- the signals output from the amplifiers 212, 213, 214 and 215 are defined as an A 'signal, a D' signal, a B 'signal and a C' signal, respectively.
- the amplification amounts of the four amplifiers 212, 213, 214, and 215 may be selected as optimum design values. For example, the amplification amount of the amplifiers 212, 213, 214, 215 may be set to a ratio of 2: 1: 1: 2.
- the A + D signal and the B + C signal are output from the optical head 103, and are input to the analog processing unit 119 and the analog processing unit 105, respectively.
- the A ′ signal, the B ′ signal, the C ′ signal, and the D ′ signal are output from the optical head 103 and input to the analog processing unit 111.
- the analog processing unit 111 detects the wobble signal by subtracting the C ′ signal and the D ′ signal from the value obtained by adding the A ′ signal and the B ′ signal (A ′ + B′ ⁇ C′ ⁇ D ′). Do.
- the analog processing unit 105 performs HPF processing for suppressing predetermined DC fluctuation, BPF processing for removing high-frequency noise unnecessary for data reproduction, and AGC for suppressing amplitude fluctuation of data signal with respect to the B + C signal from the optical head 103 Processing and ADC processing of converting an analog signal into a digital signal using a clock signal supplied from the data PLL circuit 106 is performed.
- the analog processing unit 119 performs HPF processing for suppressing a predetermined DC fluctuation with respect to the A + D signal from the optical head 103, LPF processing for removing high frequency noise unnecessary for data reproduction, and AGC suppressing an amplitude fluctuation of a data signal. Processing and ADC processing of converting an analog signal into a digital signal using a clock signal supplied from the data PLL circuit 106 is performed.
- the data PLL circuit 106 generates a clock signal synchronized with the reproduction signal from the data signal processed by the analog processing unit 105 and the data signal processed by the analog processing unit 119.
- the adaptive equalization filter 107 equalizes the output signals from the light receiving units 202 and 203.
- the adaptive equalization filter 107 includes, for example, an FIR (finite length impulse response) type filter.
- the data signal processed by the analog processing unit 105 is input to the adaptive equalization filter 107.
- Adaptive equalization filter 107 has a desired PR (partial response) characteristic of the addition result of the data signal processed in adaptive equalization filter 107 and the data signal processed in analog processing section 119 and adaptive equalization filter 120. To adaptively update the filter coefficients.
- FIG. 4 is a diagram showing the configuration of the adaptive equalization filter 107 in the first embodiment of the present invention.
- the adaptive equalization filter 107 shown in FIG. 4 includes a 7-tap FIR filter 401 and a coefficient updating unit 402.
- the input X is an output signal from the analog processing unit 105
- the input Y is an output signal from the PR equalization error detector 109.
- the FIR filter 401 includes six delay elements 4011 to 4016, seven multipliers 4017 to 4023, and an adder 4024.
- Six delay elements 4011 to 4016 for example, delay the input signal at data channel intervals.
- the delay amount of the delay elements 4011 to 4016 may be selected to realize a desired filter characteristic.
- the coefficient updating unit 402 calculates and updates the coefficients so that the output from the PR equalization error detector 109 is reduced, for example, by the least-mean-square (LMS) algorithm.
- the seven multipliers 4017 to 4023 multiply the seven coefficients updated by the coefficient updating unit 402 and seven signals obtained by delaying the input X by six delay elements 4011 to 4016, respectively.
- the adder 4024 adds the seven multiplication results of the multipliers 4017 to 4023 and outputs the result as an adaptive filter output Z.
- the adaptive equalization filter 120 equalizes the output signals from the light receiving units 201 and 204.
- the adaptive equalization filter 120 includes, for example, an FIR filter.
- the data signal processed by the analog processing unit 119 is input to the adaptive equalization filter 120.
- Adaptive equalization filter 120 has a PR (partial response) characteristic desired for the addition result of the data signal processed in adaptive equalization filter 120 and the data signal processed in analog processing unit 105 and adaptive equalization filter 107. To adaptively update the filter coefficients.
- the configuration of the adaptive equalization filter 120 is similar to that of the adaptive equalization filter 107 shown in FIG. However, in each of the adaptive equalization filter 107 and the adaptive equalization filter 120, the optimum number of taps of the FIR filter 401 in FIG. 4 and the optimum coefficient update response characteristic of the coefficient updating unit 402 are selected.
- the adder 121 adds the output signal from the adaptive equalization filter 107 and the output signal from the adaptive equalization filter 120.
- the PR equalization error detector 109 outputs a common error to the adaptive equalization filter 107 and the adaptive equalization filter 120 so that the output signal of the adder 121 has a desired PR characteristic, and the coefficients of the respective filters are output.
- Update In the case of this embodiment, tap coefficients in the adaptive equalization filter 107 and the adaptive equalization filter 120 are calculated and updated so as to be close to a desired PR characteristic and to minimize crosstalk.
- the adder 121 outputs a signal in which the influence of crosstalk is reduced. Therefore, the error rate of the binarized data (reproduction data) decoded by the data decoder 108 is reduced.
- the data decoder 108 decodes the reproduction data based on the output waveform from the adaptive equalization filter 107 and the output waveform from the adaptive equalization filter 120.
- the data decoder 108 binarizes the addition result of the output waveform from the adaptive equalization filter 107 and the output waveform from the adaptive equalization filter 120.
- the PR equalization error detector 109 calculates an equalization target waveform calculated based on the result of binarization processing by the data decoder 108, an output waveform from the adaptive equalization filter 107, and an output waveform from the adaptive equalization filter 120. Calculate the error with the addition result of
- the coefficient update unit 402 of the adaptive equalization filter 107 calculates the coefficient used in the adaptive equalization filter 107 based on the error calculated by the PR equalization error detector 109.
- the coefficient updating unit 402 of the adaptive equalization filter 120 calculates coefficients used in the adaptive equalization filter 120 based on the error calculated by the PR equalization error detector 109.
- the information recording and reproducing apparatus corresponds to an example of an information reproducing apparatus
- the optical detector 200A corresponds to an example of an optical detector
- the light receiving units 202 and 203 correspond to an example of a first light receiving unit.
- the light receiving units 201 and 204 correspond to an example of a second light receiving unit
- the adaptive equalization filter 107 corresponds to an example of a first adaptive equalization filter
- the adaptive equalization filter 120 corresponds to a second adaptation.
- the data decoder 108 corresponds to an example of a data decoder
- the PR equalization error detector 109 corresponds to an example of an error detector
- the coefficient updating unit 402 performs the first coefficient calculation. It corresponds to an example of the unit and the second coefficient calculation unit.
- the A + D signal output from the optical head 103 in FIG. 1 has a component of the reproduction signal of its own track (the reproduction target track scanned by the center of the light spot) and adjacent tracks on both sides of the own track (the center of the light spot And a crosstalk component from the track) on both sides of the reproduction target track being scanned.
- the ratio of the reproduction signal component of the own track to the crosstalk component of the adjacent track is determined by the area of the light receiving unit shown in FIG.
- FIG. 5 is a diagram showing the crosstalk amount from the adjacent track.
- the crosstalk amount shown in FIG. 5 is a reproduction signal obtained when the own track is reproduced in a state where the data is recorded on the adjacent track and the data is not recorded on the own track.
- the crosstalk amount is 1/10 of the signal amplitude of the reproduction signal of the own track, and it is understood that the crosstalk amount greatly affects the reproduction of the own track.
- the amount of crosstalk is not constant because the recording patterns of adjacent tracks on both sides are not the same, and the amount of crosstalk from adjacent tracks differs depending on the recording mark length. That is, since crosstalk has a certain frequency characteristic, the fact that the amount of crosstalk is not constant means that a simple addition operation or subtraction operation can not sufficiently eliminate crosstalk.
- the adaptive equalization filter 120 the correlation between the reproduction signal component of its own track and the PR equalization output and the non-correlation between the crosstalk component and the PR equalization output (to cancel the crosstalk component) are compatible. Calculate the tap coefficient.
- FIG. 6 is a diagram showing tap coefficients of the adaptive equalization filter 120 which processed the A + D signal and tap coefficients of the adaptive equalization filter 107 which processed the B + C signal in FIG.
- FIG. 7 is a diagram showing frequency characteristics of tap coefficients of the adaptive equalization filter 120 which processed the A + D signal and frequency characteristics of tap coefficients of the adaptive equalization filter 107 which processed the B + C signal in FIG.
- FIG. 6 shows the converged tap coefficients of the adaptive equalization filter. Both the numbers of taps of the adaptive equalization filter 107 and the adaptive equalization filter 120 are 15 taps.
- FIG. 7 is a diagram showing the frequency characteristic of the tap coefficient of FIG. In FIG.
- the vertical axis represents the gain ratio
- the horizontal axis represents the normalized frequency normalized at a predetermined frequency.
- the A + D signal including the crosstalk component of the adjacent track can remove the crosstalk component more by raising the high frequency characteristic. Further, in the configuration of the present embodiment in which the signal component of the own track and the crosstalk component from the adjacent track are detected in one spot (one reproduction operation), the signal component of the own track and the crosstalk component are detected. Since the phase does not largely shift, it is not necessary to largely correct the phase shift. Therefore, there is no need to increase the number of taps of the adaptive equalizing filter 107 or the adaptive equalizing filter 120 to take measures against the phase shift, so that the circuit scale does not increase.
- the signal component of the own track and the crosstalk component from the adjacent track are detected in one spot (one reproduction operation), and a large-scale circuit is implemented. It is possible to equalize to a desired PR characteristic without removing crosstalk having a predetermined frequency. Therefore, the error rate of the output signal from data decoder 108 can be reduced.
- the signal phases (delays) of the A and D signals and the signal phases (delay) of the B and C signals in FIG. 2 should be almost absent. However, the signal phases (delays) of the A + D signal and the B + C signal can be corrected by the adaptive equalization filter 107 and the adaptive equalization filter 120.
- the method of dividing the light receiving unit in FIGS. 2 and 3 is not limited to four in the present embodiment.
- the reproduction data detection optical detector 200A and the wobble detection optical detector 200B are separately provided, the reproduction data detection optical detector 200A of FIG. 2 includes the light receiving unit divided into three and the wobble detection optical detector 200A.
- the detector 200B may include a light receiving unit divided into four, and may divide the number of divisions for each signal to be detected. Further, in this case, the division method as shown in FIG. 34 may be used in order to share the wobble detection optical detector 200B with a signal detection unit that detects a servo signal for performing focus control and tracking control.
- one optical laser spot is irradiated on one recording track, the signal component and the crosstalk component are separated from the reflected light of the optical laser spot, only the crosstalk component is removed, and the reproduction performance of the recording data (Reduction of data error rate) and improvement of reproduction performance of address information (reduction of address error rate) can be realized.
- crosstalk cancellation processing from an adjacent track whose influence is increased by narrowing the recording track is applied not only to recording data but also to address information.
- System stabilization can be realized.
- the access performance can be improved, and an increase in circuit scale can be suppressed.
- the volume density of the optical disc can be improved, and a decrease in transfer rate due to unnecessary processing can be suppressed, and a stable system can be realized by the improvement of the reproduction performance.
- FIG. 8 is a diagram showing the configuration of the information recording and reproducing apparatus in the second embodiment of the present invention.
- the waveform shaping (equalization) target for removing the crosstalk component is different.
- the target of waveform equalization after crosstalk component removal is equalization to a desired PR scheme.
- the target of waveform equalization after crosstalk component removal is equalization to a reproduction signal having no crosstalk component.
- the crosstalk component in the case of removing the crosstalk component as described in FIG. 6 and FIG. 7, it is necessary to have a characteristic to emphasize the high frequency component. Therefore, if the high frequency component of the reproduced waveform is unnecessarily emphasized, the crosstalk component may not be sufficiently removed.
- the crosstalk component before emphasizing the high frequency component by equalizing the reproduction waveform to the desired PR characteristic, the crosstalk component is removed and the signal for which the crosstalk component is removed is desired. Equalize the reproduced waveform to the PR characteristic of Thereby, the binarization performance of the data demodulator can be improved and the error rate can be reduced. That is, in the case where the target frequency characteristics are different, the idea is to separate and process without forcibly performing the same process.
- the information recording / reproducing apparatus shown in FIG. 8 includes a spindle motor 102, an optical head 103, a servo controller 104, an analog processing unit 105, a data PLL circuit 106, an adaptive equalization filter 107, a data decoder 108, and a PR equalization error detector. 109, analog processing unit 111, BPF 112, wobble PLL circuit 113, address demodulator 114, system controller 115, recording data modulator 116, laser driver 117, host I / F 118, analog processing unit 119, adaptive equalization filter 122, An adder 123, a delay unit 124, an adder 125, and an adaptive equalization filter 126 are provided.
- the adaptive equalization filter 122 has the same configuration as the adaptive equalization filter 107 shown in FIG. 4. However, the input Y in the adaptive equalization filter 122 is not an output from the PR equalization error detector 109 but a signal output from the adder 125. The adder 125 outputs a crosstalk component. The adaptive equalization filter 122 calculates and updates the coefficients so that the crosstalk component is removed.
- the adaptive equalization filter 107 performs waveform equalization on the addition result of the waveforms of the output signals from the light receiving units 202 and 203 and the output waveform from the adaptive equalization filter 122.
- the data decoder 108 binarizes the output waveform from the adaptive equalization filter 107.
- the adder 123 adds the reproduction signal from the analog processing unit 105 and the reproduction signal from the adaptive equalization filter 122.
- the adaptive equalization filter 122 performs waveform equalization so as to remove the crosstalk component, so the output waveform of the adder 123 becomes a waveform from which the crosstalk component has been removed.
- the output of the adder 123 from which the crosstalk component has been removed is equalized by the adaptive equalization filter 107 so that the desired PR characteristic is obtained and the high frequency component is emphasized.
- the gain change band is different depending on the setting of the PR method.
- the delay unit 124 is delay-adjusted to be in phase with the waveform output from the adaptive equalization filter 126.
- the delay unit 124 delays the signal processing delay necessary for the adaptive equalization filter 107, the data decoder 108, and the adaptive equalization filter 126.
- the adaptive equalization filter 126 sets a target based on the result of the binarization processing by the data decoder 108 and the addition result of the waveforms of the output signals from the light receiving units 202 and 203 and the output waveform from the adaptive equalization filter 122. Output an ideal reproduced waveform.
- the adaptive equalization filter 126 generates an ideal reproduced signal free from noise and crosstalk components from the reproduced signal. That is, the reproduction signal generated by the adaptive equalization filter 126 has a waveform in which the OTF (Optical Transfer Function) characteristic of the reproduction signal is reproduced.
- the adaptive equalization filter 126 has the same configuration as the adaptive equalization filter 107 shown in FIG. However, the input Y in the adaptive equalization filter 126 is not an output from the PR equalization error detector 109 but a signal output from the adder 125. Further, the input X in the adaptive equalization filter 126 is not a reproduction waveform, but is binary data output from the data decoder 108.
- the coefficient updating unit 402 of the adaptive equalization filter 107 is based on an error signal between an equalization target waveform obtained based on the result of binarization processing by the data decoder 108 and an output waveform from the adaptive equalization filter 107.
- the coefficients used in the adaptive equalization filter 107 are calculated.
- Coefficient updating section 402 of adaptive equalization filter 122 adds the result of addition of the waveforms of the output signals from light receiving sections 202 and 203 and the output waveform from adaptive equalization filter 122 and the output waveform from adaptive equalization filter 126.
- the coefficients used in the adaptive equalization filter 122 are calculated based on the error signal.
- the information recording / reproducing apparatus corresponds to an example of an information reproducing apparatus
- the optical detector 200A corresponds to an example of an optical detector
- the light receiving units 202 and 203 correspond to an example of a first light receiving unit.
- the light receiving units 201 and 204 correspond to an example of a second light receiving unit
- the adaptive equalization filter 107 corresponds to an example of a first adaptive equalization filter
- the adaptive equalization filter 122 corresponds to a second adaptation.
- the adaptive equalization filter 126 corresponds to an example of the third adaptive equalization filter
- the data decoder 108 corresponds to an example of a data decoder
- the PR equalization error detector 109 corresponds to an example of the equalization filter.
- the coefficient updating unit 402 corresponds to an example of the error detector
- the coefficient updating unit 402 corresponds to an example of the first coefficient calculating unit and the second coefficient calculating unit.
- FIG. 9 is a diagram showing the relationship between the number of taps of the adaptive equalization filter 126 and the coefficient value in Embodiment 2 of the present invention.
- FIG. 9 shows an example of converged 15-tap coefficient values in the adaptive equalization filter 126.
- the tap coefficient to be obtained has a waveform substantially equivalent to the reproduction signal when one channel bit is reproduced.
- One channel bit is the reference width (reference data) of the recording mark described in FIG. Referring to FIG.
- the reproduced signal It is possible to output an ideal reproduction signal free from noise components and crosstalk components in consideration of the OTF characteristics.
- the coefficient updating unit 402 uses the correlation between the reproduced binary signal (input X) and the difference between the reproduced signal and the ideal waveform (input Y) to reproduce one channel bit, An approximately equivalent waveform (coefficient) is calculated.
- the signal component from the own track and the crosstalk component from the adjacent track are detected in one spot (one reproduction operation), and a large-scale circuit is obtained.
- the error rate of the output signal from data decoder 108 can be reduced.
- FIG. 10 is a diagram showing a configuration of the information recording and reproducing apparatus in the third embodiment of the present invention.
- the large difference is that the reproduction signal divided into three is output from the optical head and the crosstalk component is removed from the three reproduction signals.
- a crosstalk may occur between the crosstalk component of the A signal and the crosstalk component of the D signal due to radial tilt caused by the inclination of the optical head and the optical disk, and off-track in which the laser spot does not scan the center of the track. .
- the third embodiment has a configuration capable of coping with crosstalk components having the above-described bias.
- the tangent between the optical head and the signal processing apparatus (or signal processing circuit) may increase, and the size of the signal processing circuit may also increase. Therefore, it is necessary to select the third embodiment in consideration of the balance between performance and circuit scale.
- transmission of a reproduction signal high band signal
- the information recording / reproducing apparatus shown in FIG. 10 includes a spindle motor 102, an optical head 103, a servo controller 104, a data decoder 108, a PR equalization error detector 109, an analog processing unit 111, a BPF 112, a wobble PLL circuit 113, and an address demodulation.
- FIG. 11 is a diagram showing a configuration of an optical detector of an optical head according to Embodiment 3 of the present invention.
- the optical detector 200C of the optical head 103 of FIG. 10 is configured as shown in FIG. 11, and outputs an A signal, a D signal, and a B + C signal.
- the light receiving units 201 to 204, the amplifiers 205 to 208, and the adder 210 have the same characteristics and configuration as those in FIG.
- the A signal output from the amplifier 205 is output to the analog processing unit 127
- the D signal output from the amplifier 206 is output to the analog processing unit 129
- the B + C signal output from the adder 210 is an analog processing unit. It is output to 128.
- the light receiving unit 201 receives the reflected light of a portion adjacent to one of the central portions in the radial direction of the optical disc 101.
- the light receiving unit 204 receives the reflected light of a portion adjacent to the other in the radial direction of the optical disc 101 with respect to the central portion.
- the analog processing units 127, 128, and 129 have the same configuration as the analog processing units 105 and 119 of FIG.
- the analog processing units 127, 128, and 129 perform HPF processing for suppressing predetermined DC fluctuation with respect to three reproduction signals of A signal, B + C signal, and D signal, and LPF processing for removing high-frequency noise unnecessary for data reproduction.
- AGC processing for suppressing variation in amplitude of the data signal
- ADC processing for converting an analog signal into a digital signal using the clock signal supplied from the data PLL circuit 130.
- the data PLL circuit 130 generates a clock signal synchronized with the reproduction signal from the three reproduction signals processed by the analog processing units 127, 128 and 129.
- the adaptive equalization filters 131, 132, and 133 have the same configuration as the adaptive equalization filter 107 shown in FIG.
- the adaptive equalization filter 131 performs waveform equalization on the output signal from the light receiving unit 201.
- the adaptive equalization filter 132 performs waveform equalization on the output signals from the light receiving units 202 and 203.
- the adaptive equalization filter 133 equalizes the output signal from the light receiving unit 204.
- the adder 134 adds the output waveforms from the three adaptive equalization filters 131, 132, and 133.
- Each of the three adaptive equalization filters 131, 132 and 133 has an optimum coefficient using a common error signal from the PR equalization error detector 109 so that the output waveform from the adder 134 has a desired PR characteristic. Calculate and update.
- the data decoder 108 binarizes the addition result of the output waveform from the adaptive equalization filter 132, the output waveform from the adaptive equalization filter 131, and the output waveform from the adaptive equalization filter 133.
- the PR equalization error detector 109 calculates an equalization target waveform calculated based on the result of binarization processing by the data decoder 108, an output waveform from the adaptive equalization filter 131, and an output waveform from the adaptive equalization filter 132. And the error between the result of addition of the output waveform from the adaptive equalization filter 133 and the result.
- the coefficient updating unit 402 of the adaptive equalization filter 132 calculates coefficients used in the adaptive equalization filter 132 based on the error calculated by the PR equalization error detector 109.
- the coefficient updating unit 402 of the adaptive equalization filter 131 calculates the coefficient used in the adaptive equalization filter 131 based on the error calculated by the PR equalization error detector 109.
- the coefficient update unit 402 of the adaptive equalization filter 133 calculates the coefficient used in the adaptive equalization filter 133 based on the error calculated by the PR equalization error detector 109.
- the information recording and reproducing apparatus corresponds to an example of an information reproducing apparatus
- the optical detector 200C corresponds to an example of an optical detector
- the light receiving units 202 and 203 correspond to an example of a first light receiving unit.
- the light receiving unit 201 corresponds to an example of a third light receiving unit
- the light receiving unit 204 corresponds to an example of a fourth light receiving unit
- the adaptive equalization filter 132 is an example of a first adaptive equalization filter.
- the adaptive equalization filter 131 corresponds to an example of the third adaptive equalization filter
- the adaptive equalization filter 133 corresponds to an example of the fourth adaptive equalization filter
- the data decoder 108 corresponds to the data decoder.
- the PR equalization error detector 109 corresponds to an example of an error detector
- the coefficient updating unit 402 corresponds to an example of a first coefficient calculating unit, a second coefficient calculating unit, and a third coefficient calculating unit. Equivalent to.
- the signal component from the own track and the crosstalk component from the adjacent track are obtained. Can be detected and equalized to the desired PR characteristics while removing crosstalk with a predetermined frequency. Therefore, the error rate of the output signal from data decoder 108 can be reduced. In particular, the error rate can be reduced with respect to the deviation of crosstalk components from two adjacent tracks generated due to radial tilt, off-track, lens shift or the like.
- the optical detector 200C of the optical head 103 includes the light receiving unit divided into four, but the present invention is not particularly limited to this, and the optical detector 200C includes the light receiving unit divided into three. It is also good.
- the case where the optical detector of the optical head 103 of FIG. 10 includes the light receiving unit divided into three will be described.
- FIG. 12 is a diagram showing the configuration of a photodetector in the first modification of the third embodiment of the present invention.
- the optical detector 200D includes three light receiving portions 201, 202, and 203 divided by a dividing line parallel to the track scanning direction, and the light spot 211 reflected from the information recording medium is as shown by a dotted line in FIG. It is irradiated.
- the optical detector 200D outputs an A signal, a B signal, and a C signal.
- the amplifiers 205 to 207 amplify the signals output from the light receiving units 201 to 203, respectively.
- the light receiving units 201 to 203 and the amplifiers 205 to 207 have the same characteristics and configuration as the light receiving units 201 to 203 and the amplifiers 205 to 207 shown in FIG.
- the difference between the optical detector 200D of FIG. 12 and the optical detector 200C of FIG. 11 is whether or not the light receiving portion corresponding to the central portion of the light spot 211 is divided.
- FIG. 13 is a diagram showing the configuration of an information recording and reproducing apparatus in a first modification of the third embodiment of the present invention.
- the information recording / reproducing apparatus shown in FIG. 13 includes a spindle motor 102, an optical head 103, a servo controller 104, a data decoder 108, a PR equalization error detector 109, an analog processing unit 111, a BPF 112, a wobble PLL circuit 113, and an address demodulation.
- the light receiving unit 201 receives the reflected light of a portion adjacent to one of the central portions in the radial direction of the optical disc 101.
- the light receiving unit 203 receives the reflected light of a portion adjacent to the other in the radial direction of the optical disc 101 with respect to the central portion.
- the adaptive equalization filter 131 performs waveform equalization on the output signal from the light receiving unit 201.
- the adaptive equalization filter 132 equalizes the output signal from the light receiving unit 202.
- the adaptive equalization filter 133 equalizes the output signal from the light receiving unit 203.
- the data decoder 108 binarizes the addition result of the output waveform from the adaptive equalization filter 131, the output waveform from the adaptive equalization filter 132, and the output waveform from the adaptive equalization filter 133.
- the wobble PLL circuit 113 detects a wobble signal from the difference between the output signal from the light receiving unit 201 and the output signal from the light receiving unit 203.
- the address demodulator 114 demodulates the address from the wobble signal detected by the wobble PLL circuit 113.
- the information recording and reproducing device corresponds to an example of the information reproducing device
- the optical detector 200D corresponds to an example of an optical detector
- the light receiving unit 202 is a first.
- the light receiving unit 201 corresponds to an example of a third light receiving unit
- the light receiving unit 203 corresponds to an example of a fourth light receiving unit
- the adaptive equalization filter 132 corresponds to a first adaptive equalization.
- the adaptive equalization filter 131 corresponds to an example of a third adaptive equalization filter
- the adaptive equalization filter 133 corresponds to an example of a fourth adaptive equalization filter
- the data decoder 108 corresponds to an example of a filter.
- the PR equalization error detector 109 corresponds to an example of an error detector
- the coefficient updating unit 402 corresponds to a first coefficient operation unit, a second coefficient operation unit, and a third coefficient operation.
- the wobble PLL circuit 113 corresponds to an example of a table detector
- the address demodulator 114 corresponds to an example of the address demodulator.
- the difference between the information recording / reproducing apparatus shown in FIG. 13 and the information recording / reproducing apparatus shown in FIG. 10 is to reproduce the data recorded on the optical disc 101 from the A signal, B signal and C signal from the optical detector 200D, Address information pre-recorded on the optical disc 101 is reproduced from the A signal and the C signal.
- the merit of this configuration is that the signal-to-noise ratio (SNR) of the transmission path can be improved by the reduction of the addition unit for adding a plurality of reproduction signals because the number of divisions of the light receiving unit is small. If the division ratio of the light receiving units 201 to 203 is optimized, the crosstalk information from the adjacent track included in the reproduction signal is removed, and the address information is stabilized from the wobble signal which is the difference signal between the A signal and the C signal. It can be played back. However, if the area of the light receiving area of the light receiving sections 201 and 203 is made too small, not only the reduction of the SN ratio of the reproduction signal but also various kinds of reproduction stress resistance may be deteriorated. Therefore, the division ratio of the light receiving unit needs to be set carefully.
- the area of the light receiving unit 202 may be smaller than the sum of the area of the light receiving unit 201 and the area of the light receiving unit 203 in consideration of the balance between the crosstalk cancellation performance and the address reproduction performance.
- the amount of crosstalk from the adjacent track differs depending on the design parameters of the optical disk such as the spot size and the track pitch, and the radial width of the recording mark formed by the recording operation. If the design parameters of the optical disk such as the spot size and the track pitch are determined, the division width by which the reproduction signal of the own track and the crosstalk signal from the adjacent track can be separated is necessarily determined.
- FIG. 14 is a view showing a relationship between an optical detector divided into three by a dividing line parallel to the track scanning direction, a light intensity distribution of laser light, and recording signals of three tracks.
- the light receiving units 201, 202, 203 and the light spot 211 have the same definition as described above.
- the half size width of the spot size is 0.25 ⁇ m
- the track pitch is 0.23 ⁇ m
- the radial width (mark width) of the recording mark is 0.19 ⁇ m. Since the track pitch is narrower than the half width of the spot size, it can be seen that the signal from the adjacent track leaks into the regions R1 and R2 of the light intensity distribution of the laser light.
- the ratio of the division widths of the light receiving units 201, 202, and 203 for separating the signal of the own track and the signal of the adjacent track can be estimated to be 27:46:27.
- track pitch candidates may be determined in consideration of the surface density of the optical disc and the reproduction performance. For example, the track pitch may be about 0.24 ⁇ m to 0.2 ⁇ m.
- the division ratio between the light receiving portion at the center and the light receiving portion at the end where the crosstalk cancellation effect can be exhibited is 1.5 to 4.5. That is, the radial width of the light receiving portion (first light receiving portion) in the central portion is divided by the radial width of the light receiving portion (third light receiving portion) at one end, and the light receiving portion in the central portion
- the value obtained by dividing the radial width of the first light receiving portion by the radial width of the light receiving portion (the fourth light receiving portion) at the other end is in the range of 0.75 to 2.25. preferable.
- the ratio of the division widths of the light receiving portions 201, 202, and 203 is 1: 2: 1 (end: central portion: end Part).
- the value of the width of the light receiving portion at the center portion / (the width of the light receiving portion at 2 ⁇ the end portion) is 0.75 to 2.25. That is, the value of the radial width of the central light receiving portion (first light receiving portion) divided by the radial width of the light receiving portions (second light receiving portion) at both ends is 0.75 to 2 It is preferable to be in the range of .25.
- division width of only three divisions is described here, the division width may be determined in the same way even in the case of four divisions or five divisions.
- the CN ratio (Carrier to Noise ratio) of the wobble signal capable of securing the address performance can be secured with a predetermined ratio or more by the above division ratio.
- the above division width if it is not possible to secure the CN ratio above a predetermined level, change the spot size or the track pitch, or change the recording width of the recording mark to be formed in the radial direction and change the recording film which can maintain the SN ratio. There is a need to.
- FIG. 15 is a diagram showing a configuration of a photodetector in the second modified example of the third embodiment of the present invention.
- the optical detector 200E illustrated in FIG. 15 includes light receiving units 201, 202, 203, and 204, amplifiers 2401, 2402, 2403, 2404, 2405, 2406, 2407, and 2408, and adders 2409 and 2410.
- the amplifier 2401 outputs an A signal obtained by amplifying the signal output from the light receiving unit 201.
- the amplifier 2402 outputs a B signal obtained by amplifying the signal output from the light receiving unit 202.
- the amplifier 2403 outputs a C signal obtained by amplifying the signal output from the light receiving unit 203.
- the amplifier 2404 outputs a D signal obtained by amplifying the signal output from the light receiving unit 204.
- the amplifier 2405 outputs an E signal obtained by amplifying the signal output from the light receiving unit 201.
- the amplifier 2406 outputs an F signal obtained by amplifying the signal output from the light receiving unit 202.
- the amplifier 2407 outputs an H signal obtained by amplifying the signal output from the light receiving unit 203.
- the amplifier 2408 outputs an I signal obtained by amplifying the signal output from the light receiving unit 204.
- the adder 2409 adds the E signal output from the amplifier 2405 and the F signal output from the amplifier 2406, and outputs a J signal (E + F).
- the adder 2410 adds the H signal output from the amplifier 2407 and the I signal output from the amplifier 2408 and outputs a K signal (H + I).
- the photodetector outputs an A signal, a B signal, a C signal, a D signal, a J signal and a K signal.
- the light receiving units 201 to 204, the amplifiers 2401 to 2408, and the adders 2409 and 2410 have the same characteristics and configuration as the light receiving units 201 to 204, the amplifiers 205 to 208, and the adder 210 shown in FIG. However, the characteristics of each amplifier 2401-2408 may be optimized depending on the configuration.
- the J signal and the K signal are output as signals for generating a wobble signal. Further, if the division ratio between the light receiving unit 201 and the light receiving unit 204 is a division ratio sufficient to detect the wobble signal, the E signal and the I signal may be output as signals for generating the wobble signal.
- FIG. 16 is a diagram showing the configuration of an information recording and reproducing apparatus in a second modification of the third embodiment of the present invention.
- the difference between the optical detector 200E shown in FIG. 15 and the optical detector 200C shown in FIG. 11 is that the signal from the light receiving unit 202 and the signal from the light receiving unit 203 are not added and output, and the wobble signal is detected. And a signal obtained by adding the signal from the light receiving unit 203 and the signal from the light receiving unit 204 as a signal for generating a signal for the purpose. Output.
- the difference between the information recording / reproducing apparatus shown in FIG. 16 and the information recording / reproducing apparatus shown in FIG. 10 is recorded on the optical disc 101 based on the A signal, B signal, C signal and D signal from the optical detector 200E. Data is reproduced, and address information prerecorded on the optical disc 101 is reproduced based on the J signal and the K signal from the optical detector 200E.
- the information recording / reproducing apparatus shown in FIG. 16 includes a spindle motor 102, an optical head 103, a servo controller 104, a data decoder 108, a PR equalization error detector 109, an analog processing unit 111, a BPF 112, a wobble PLL circuit 113, and an address demodulation.
- the reproduction signal from the optical head 103 is increased to four, an analog processing unit 2301 and an adaptive equalization filter 2302 necessary for the crosstalk cancellation process are added.
- the data PLL circuit 130 performs synchronization processing from the four signals from the analog processing units 127, 128, 129, and 2301.
- the adder 134 adds the four signals from the adaptive equalization filters 131, 132, 133 and 2302 and outputs the result to the PR equalization error detector 109.
- the PR equalization error detector 109 generates an error signal from the difference between a signal obtained by adding four signals and an expected value of PR equalization, and generates the generated error signal as four adaptive equalization filters 131, 132, 133, Output to 2302
- the information recording and reproducing apparatus corresponds to an example of the information reproducing apparatus
- the optical detector 200E corresponds to an example of an optical detector
- the light receiving unit 201 is a third.
- the light receiving unit 204 corresponds to an example of a fourth light receiving unit
- the light receiving unit 202 corresponds to an example of a fifth light receiving unit
- the light receiving unit 203 corresponds to an example of a sixth light receiving unit.
- the adaptive equalization filter 131 corresponds to an example of the third adaptive equalization filter
- the adaptive equalization filter 2302 corresponds to an example of the fourth adaptive equalization filter
- the adaptive equalization filter 132 corresponds to the fifth example.
- the adaptive equalization filter 133 corresponds to an example of a sixth adaptive equalization filter
- the data decoder 108 corresponds to an example of a data decoder
- the PR equalization error detector 109 corresponds to an example of the error detector
- the coefficient updating unit 02 corresponds to an example of a first coefficient calculating unit, a second coefficient calculating unit, a third coefficient calculating unit, and a fourth coefficient calculating unit
- the wobble PLL circuit 113 corresponds to an example of a wobble detecting unit.
- the demodulator 114 corresponds to an example of the address demodulator.
- the merit of this configuration is that the center of the light spot 211 in FIG. 15 is shifted from the center of the recording track of the optical disk 101, and the number of divisions of the light receiving unit is increased when the reproduction detector does not appropriately irradiate the reproduction light. And crosstalk cancellation effect can be maintained.
- the optical detector 200E including the light receiving unit divided into four can improve the reproduction tolerance.
- FIGS. 17A and 17B are diagrams for comparing an optical detector provided with a three-divided light receiving unit when a lens shift occurs with an optical detector provided with a four-divided light receiving unit.
- FIG. 17A is a diagram showing a three-divided light receiving unit and a four-divided light receiving unit when lens shift does not occur
- FIG. 17B is a diagram illustrating three cases where a predetermined amount of lens shift occurs. It is a figure which shows a division
- the number of divisions of the light receiving portion is increased, the resistance to the case where the reproduction light is not appropriately irradiated to the optical detector is increased, but the SN ratio of the light receiving portion of the optical detector is lowered. Since there is a trade-off between the reproduction resistance based on the number of divisions and the SN ratio, it is necessary to select an optimum number of divisions and division configuration. Although an example of four divisions is shown here, the light receiving unit may be divided into five or six parts in order to increase resistance to a situation where the reproduction light is not appropriately irradiated to the optical detector, and the number of divisions may be increased. Good.
- FIG. 18 shows three light receiving portions 2602, 2603 and 2604 of an optical detector 2601 that receives reflected light from a recording track when the optical head irradiates laser light to the recording track, and three tracks T 0 and T 1. , T 2 schematically.
- Receiving unit 2602,2603,2604 outputs signals S 0, S 1, S 2 .
- the three signals S 0 , S 1 , S 2 are affected by the tracks T 0 , T 1 , T 2 with different characteristics.
- the signals S 0 , S 1 and S 2 can be expressed by the following matrix operation equation (1).
- M ij is an amount that represents the influence of each track on each signal
- i represents the number of the light receiving unit
- j represents the track number.
- ⁇ 0 , ⁇ 1 and ⁇ 2 represent errors that can not be represented by a simple addition signal.
- FIG. 19 is a diagram showing the M ij characteristics of the signal S 0
- FIG. 20 is a diagram showing the M ij characteristics of the signal S 1
- FIG. 21 is a diagram showing the M ij characteristics of the signal S 2 .
- the M ij characteristic indicates the influence of three tracks in each of the signals S 0 , S 1 and S 2 .
- FIG. 22 is a diagram comparing the waveform obtained by convolution of the M ij characteristic and the track signal with the optical simulation waveform of the signal S 0
- FIG. 23 is the waveform obtained by convolution of the M ij characteristic and the track signal is a diagram that compares the optical simulation waveform of the signal S 1
- FIG. 24 is a diagram comparing the calculated waveform convolution and M ij characteristics and track signal, and an optical simulation waveforms of the signal S 2.
- the signals S 0 , S 1 and S 2 can be expressed by linear convolution operations. That is, as the reproduction signal, the signal from the own track and the signal from the adjacent track are mixed and output, but the signals S 0 , S 1 , and S 2 from the three light receiving sections are passed through the filter of the predetermined characteristics. Thus, signals from adjacent tracks can be removed.
- the terms M ′ 10 / PR, M ′ 11 / PR, M represented by the following equation (3) and multiplied by the signals S 0 , S 1 , S 2 '12 / PR means the filter.
- filter coefficients which have predetermined PR characteristics and can remove crosstalk components from adjacent tracks can be calculated by an adaptive filter using the LMS algorithm.
- the model shown in FIG. 18 is a model limited to the influence of only three tracks, but may be a model considering the influence of five tracks.
- the model shown in FIG. 18 is a model using an optical detector divided into three by a dividing line parallel to the track scanning direction, but may be another number of divisions and a division configuration. In this case, if the amount of influence on each light receiving portion can be expressed by a linear convolution operation, the influence on each light receiving portion can be eliminated or reduced by passing the reproduction signal through a predetermined filter.
- FIG. 25 is a diagram showing the configuration of an information recording and reproducing apparatus in the fourth embodiment of the present invention.
- the crosstalk cancellation processing in the first to third embodiments cancels the crosstalk only for the recorded data signal as a large difference
- the crosstalk cancellation processing in the fourth embodiment is the same as that in FIG.
- the crosstalk is canceled also for the address information formed by wobbling the described track groove.
- the CN ratio ratio of the carrier level of the signal to the noise level
- FIG. 26 is a diagram showing the frequency characteristic of the wobble signal in the fourth embodiment of the present invention.
- FIG. 26 shows an example of measuring the CN ratio.
- the frequency f0 is a reference frequency of the wobble signal
- the C value is an amplitude level (carrier level) of the frequency f0
- the N0 and N1 values are noise levels of the frequency f0.
- the N0 value is a noise level when the adjacent track and the own track are unrecorded
- the N1 value is a noise level when the adjacent track is already recorded. It means that the reproduction performance of the address information is degraded as the difference between the C value and the N value becomes smaller.
- the address information is inserted as wobbling information in which the track groove is MSK modulated.
- the MSK modulator is detected based on the reference wobble signal (unmodulated wobble signal)
- the quality of the reference wobble signal is degraded
- MSK The detection performance of the modulator also deteriorates. Therefore, the reduction of the base noise (removal of the crosstalk component) described in FIG. 26 is a very important point.
- the noise level increases due to the crosstalk component. Also, as the track width is narrowed, the noise level due to the crosstalk component from the adjacent track tends to increase.
- the fourth embodiment provides a signal processing method capable of removing the crosstalk component from the wobble signal. If the signal processing of the fourth embodiment is applied, the noise level of the N1 value in FIG. 26 decreases until it approaches the N0 value, and the reproduction performance of the address information is improved.
- the information recording / reproducing apparatus shown in FIG. 25 includes a spindle motor 102, an optical head 103, a servo controller 104, an analog processing unit 105, a data PLL circuit 106, an adaptive equalization filter 107, a data decoder 108, and a PR equalization error detector. 109, analog processing unit 111, BPF 112, wobble PLL circuit 113, address demodulator 114, system controller 115, recording data modulator 116, laser driver 117, host I / F 118, analog processing unit 119, adaptive equalization filter 120, The adder 121, the adder 135, the WBL error detector 136, and the adaptive equalization filter 137 are provided.
- the information recording / reproducing apparatus shown in FIG. 25 uses the A + D signal including the crosstalk component to remove the crosstalk component that has leaked into the wobble signal.
- the configuration of the adaptive equalization filter 137 is the same as that of the adaptive equalization filter 107 shown in FIG. However, in the adaptive equalization filter 137, the optimum number of taps of the FIR filter 401 in FIG. 4 and the optimum coefficient update response characteristic of the coefficient updating unit 402 are selected.
- an input X is a signal obtained by processing an A + D signal by the analog processing unit 119
- an input Y is a signal from the WBL error detector 136.
- An error signal including a crosstalk component is input from the WBL error detector 136 to the adaptive equalization filter 137.
- the tap coefficients of the adaptive equalization filter 137 are calculated and updated so that the crosstalk component is removed.
- the adder 135 adds the wobble signal from the analog processing unit 111 and the signal from the adaptive equalization filter 137.
- the output of the adder 135 is a wobble signal from which the crosstalk component has been removed, and is input to the address demodulator 114.
- the WBL error detector 136 outputs the difference between the output of the adder 135 and the output signal of the BPF 112. Since the BPF 112 is a filter for PLL, it has filter characteristics for extracting only the wobble component. Although noise is reduced by the BPF 112, the crosstalk component, which is the filter passband, remains unremoved.
- the BPF 112 also removes signals such as MSK modulation.
- the output signal of the BPF 112 can not be used as a signal for address modulation, but can be used as a target value signal of a wobble signal because it is a signal from which crosstalk components outside the filter passband have been removed.
- the signal component from the own track and the crosstalk component from the adjacent track are obtained. Can be detected and equalized to the desired PR characteristics while removing crosstalk with a predetermined frequency. Therefore, the error rate of the output signal of data decoder 108 can be reduced.
- the crosstalk component contained in the wobble signal can be removed using the data signal having the crosstalk component from the adjacent track, and the address error rate can also be improved.
- the configuration of the photodetector of the optical head 103 of FIG. 25 may be as shown in FIG.
- the optical head 103 outputs three signals: an A signal, a B + C signal, and a D signal.
- the information recording and reproducing apparatus uses the A signal and the D signal to remove the crosstalk component of the wobble signal.
- one circuit having the same configuration as that of the adaptive equalization filter 137 may be added. With this configuration, it is possible to reduce the address error rate particularly against the deviation of the crosstalk component from the adjacent track caused by the radial tilt or the off track.
- FIG. 27 is a diagram showing a configuration of an information recording and reproducing apparatus in the fifth embodiment of the present invention
- FIG. 28 is a diagram showing a configuration of an information recording medium in the fifth embodiment of the present invention.
- Patent Document 6 in order to allow a shift in the timing of the reproduction signal of the adjacent track held in the memory to some extent, the tap coefficient of the adaptive equalizer is increased.
- an equalizer of 256 taps is shown to allow for a timing shift of several tens of clocks.
- two equalizers each having at least a multistage tap coefficient for both adjacent tracks are required. Therefore, the increase in the circuit scale and the complication of the circuit have become issues.
- Patent Document 6 the reason why the timing of holding the reproduction signal of the adjacent track in the memory is allowed to some extent is due to an address format or the like.
- the relationship between the address in Blu-ray and the recording data will be described with reference to FIG.
- the adjacent address information and the recording data reference position deviate from the straight line extending in the radial direction with respect to the center of the optical disc. The reason why it is difficult to obtain the timing for holding the reproduction signal in the memory will be described.
- a recording track 1502 is formed on an optical disc 1501 by a groove.
- Data is recorded in the data recording area 1503, and address information for accessing the data recording area 1503 is recorded in the address information areas 1504, 1505 and 1506.
- the address information is arranged in the same area as the recording data, and the recording data is recorded superimposed on the address information.
- One recording data is recorded in an area constituted by three pieces of address information AD1 (Z05), AD2 (Z06) and AD3 (Z07), and an area constituted by three pieces of address information is a recording unit of data. It becomes a certain data recording area 1503.
- the integral multiple of the length of the data recording area 1503 composed of three pieces of address information does not match the length of the circumference of the track. Therefore, as shown in FIG. 31, the positions on the circumference of the data recording area 1503 are arranged to be shifted for each rotation of the optical disc between the adjacent recording tracks.
- one bit of address information AD1, AD2, AD3 is recorded by partially changing the waveform of the groove wobbling at a constant cycle.
- An area 1507 shown enlarged in the lower part of FIG. 31 is subjected to modulation called MSK in a portion corresponding to an address bit.
- MSK modulation
- the recording data of the adjacent recording track is held in the memory based on the address information AD1, AD2 and AD3, the recording data of the adjacent recording track and the recording data of the self recording track mutually
- AD1, AD2 and AD3 the recording data of the adjacent recording track and the recording data of the self recording track mutually
- the fifth embodiment of the present invention it is possible to improve the timing accuracy of holding the reproduction data of the adjacent track in the memory to several channel clocks or less in the radial direction, and to suppress an increase in circuit scale. Therefore, in the fifth embodiment of the present invention, an address format for matching an integer multiple of the wobble period forming the address information and the length of one round of the recording track, and an optimal cross using the address format It is possible to realize talk cancellation signal processing.
- the address information is recorded by the constant angular velocity (CAV) method
- the recording data is recorded by the constant linear velocity (CLV) method.
- the information recording / reproducing apparatus shown in FIG. 27 includes a spindle motor 102, an optical head 103, a servo controller 104, an analog processing unit 105, a data PLL circuit 106, a data decoder 108, a PR equalization error detector 109, and an analog processing unit 111. , BPF 112, wobble PLL circuit 113, address demodulator 114, system controller 115, recording data modulator 116, laser driver 117, host I / F 118, adaptive equalization filter 131, adaptive equalization filter 132, adaptive equalization filter 133 , An adder 134, a timing controller 138 and a memory 139.
- the optical detector of the optical head 103 shown in FIG. 27 has the same configuration as the optical detector shown in FIG.
- the optical detector outputs the A + B + C + D signal as a reproduction signal.
- the analog processing unit 105 converts the reproduction signal into a digital signal synchronized with the clock from the data PLL circuit 106, and stores the reproduction signal converted into the digital signal in the memory 139.
- reproduction waveform data of an adjacent track is required.
- the reproduction waveform data Y of the area to be reproduced, the reproduction waveform data X of the track on the inner circumferential side in the radial direction adjacent to the reproduction area, and the reproduction waveform data of the track on the outer circumferential side adjacent to the reproduction area Z is stored in the memory 139.
- the timing signal stored in the memory 139 is supplied from the timing controller 138.
- the timing signal output from the timing controller 138 is generated using the address information demodulated by the address demodulator 114.
- the address demodulator 114 demodulates the address information of the optical disc 101.
- the timing controller 138 generates a radially in-phase timing signal based on the address information demodulated by the address demodulator 114.
- the memory 139 generates a reproduction waveform of data recorded on a first recording track for which reproduction of data is desired based on the timing signal, and a second recording track adjacent to one of the first recording track in the radial direction of the optical disc 101.
- the reproduction waveform of the data recorded in the second recording track and the reproduction waveform of the data recorded in the third recording track adjacent to the other in the radial direction of the optical disc 101 with respect to the first recording track are held.
- the adaptive equalization filter 132 equalizes the reproduced waveform from the first recording track held in the memory 139.
- the adaptive equalization filter 131 equalizes the reproduced waveform from the second recording track held in the memory 139.
- the adaptive equalization filter 133 equalizes the reproduced waveform from the third recording track held in the memory 139.
- the data decoder 108 binarizes the addition result of the output waveform from the adaptive equalization filter 132, the output waveform from the adaptive equalization filter 131, and the output waveform from the adaptive equalization filter 133.
- the PR equalization error detector 109 calculates an error between the equalization target waveform calculated based on the binarization processing result by the data decoder 108 and the addition result.
- the coefficient updating unit 402 of the adaptive equalization filter 132 calculates coefficients used in the adaptive equalization filter 132 based on the error calculated by the PR equalization error detector 109.
- the coefficient updating unit 402 of the adaptive equalization filter 131 calculates the coefficient used in the adaptive equalization filter 131 based on the error calculated by the PR equalization error detector 109.
- the coefficient update unit 402 of the adaptive equalization filter 133 calculates the coefficient used in the adaptive equalization filter 133 based on the error calculated by the PR equalization error detector 109.
- boundaries of address blocks storing address information are aligned in the radial direction. Then, the address information is reproduced, the boundary of the address block is detected, and a timing signal for storing the reproduced waveform data in the memory 139 is generated from the detection signal of the boundary of the address block.
- the position of the reproduction waveform data of the own track and the position of the reproduction waveform data of the adjacent track can be aligned with high accuracy. That is, since the reproduction waveform data adjacent to the reproduction waveform data of the own track can be stored in the memory 139, the scale of the circuit for correcting the position can be reduced.
- the number of taps of the adaptive equalization filters 131, 132, and 133 in FIG. 27 may be designed in consideration of the intersymbol interference amount of the reproduction waveform data.
- the intersymbol interference amount is determined by the relationship between the beam spot and the recording linear density. For example, when there is interference of about 10 channel bits, the number of taps of the adaptive equalization filters 131, 132, and 133 is designed to be about ten taps in consideration of other interference such as tilt or aberration. However, in this case, the interval of the number of taps is the channel bit interval.
- the information recording and reproducing apparatus corresponds to an example of an information reproducing apparatus
- the address demodulator 114 corresponds to an example of an address demodulator
- the timing controller 138 corresponds to an example of a timing controller.
- the memory 139 corresponds to an example of the memory
- the adaptive equalization filter 132 corresponds to an example of the first adaptive equalization filter
- the adaptive equalization filter 131 or the adaptive equalization filter 133 corresponds to the second adaptive equalization filter.
- the data decoder 108 corresponds to an example of a data decoder
- the PR equalization error detector 109 corresponds to an example of an error detector
- the coefficient updating unit 402 corresponds to a first coefficient calculator and a second coefficient calculator. It corresponds to an example of the coefficient calculating unit of
- FIG. 28 is a diagram for explaining the format of the optical disc in the fifth embodiment of the present invention.
- the optical disc 1401 has recording layers on both sides. In FIG. 28, only one side of the optical disc 1401 is shown, and the other side has the same structure.
- Groove tracks 1405 and 1407 are recording tracks formed by grooves on the optical disc 1401.
- the land track 1406 is a recording track formed by lands on the optical disc 1401.
- the address blocks 1402, 1403 and 1404 are formed by dividing the groove tracks 1405 and 1407 and the land track 1406 by straight lines extending radially from the center of the optical disk 1401.
- the groove track 1405 and the groove track 1407 are alternately repeated in the radial direction across the land track 1406.
- the groove tracks 1405 and 1407 and the land track 1406 form a recording track.
- the address blocks 1402, 1403 and 1404 radially divided into three locations have three independent address information 1408, 1409, 1410, 1411, 1412 and 1413 respectively.
- the address information 1408 1409 1410 1411 1412 1413 is recorded by wobbling the groove tracks 1405 1407.
- the three pieces of address information 1408, 1409, and 1410 form one set, and the address values of the three pieces of address information 1408, 1409, and 1410 sequentially increase. Further, three pieces of address information 1411, 1412, and 1413 form one set, and the three pieces of address information 1411, 1412, and 1413 sequentially increase in address value.
- the optical disc 1401 includes groove tracks 1405 and 1407 and land tracks 1406 formed between two groove tracks 1405 and 1407 adjacent to each other.
- the groove tracks 1405 and 1407 record address information indicating position information in the recording surface of the optical disc 1401 in a predetermined pattern by wobbling of grooves.
- the groove tracks 1405 and 1407 may be formed by one groove spirally formed on the recording surface.
- the groove tracks 1405 and 1407 may be configured by a plurality of grooves formed concentrically on the recording surface.
- the lower part of FIG. 28 shows a schematic view in which a part of the track is enlarged.
- the optical disc 1401 of the fifth embodiment is characterized in that the phases of the wobbles are aligned between adjacent grooves. That is, the length of one circumference of the groove track is configured to be an integral multiple of the period of the wobble.
- the width of the land track 1406 sandwiched by the groove tracks 1405 and 1407 does not change, and can maintain a constant width.
- the integral multiple of the wobbling period of the portion other than the address information of the recording track (groove track 1405, 1407) matches the length of one round of the recording track. Also, an integral multiple of the period of the address information matches the length of one round of the recording track.
- the wobble phase of the adjacent recording track is the recording track. Every time I shift gradually. For this reason, although the width of the groove track can be kept constant, the width of the land track changes frequently, and the land track has a shape not suitable for recording.
- the wobble phase of the adjacent groove changes for each recording track. Therefore, a beat is generated in the wobble signal, which causes deterioration of the generation performance of the recording clock generated by the PLL circuit based on the reproduction performance of the address or the wobble.
- This phenomenon is more pronounced when using lands as recording tracks. Since the wall surface of the land is composed of two adjacent wobbling grooves, the phase of the land changes completely asynchronously, and the wobble signal can not even be detected, and the recording clock can not be generated. Therefore, data can not be recorded on the land.
- the structure of the optical disc which is the first point of the fifth embodiment, will be described below.
- the beat phenomenon due to the land wobble can be eliminated by arranging the wobble cycles of adjacent grooves on the entire surface of the optical disc. This makes it possible to detect a stable wobble signal even on the land.
- address information is recorded by modulating the wobble of the groove by using different address bit patterns in the groove track 1405 and the groove track 1407 on both sides of the land track 1406.
- the address information can be obtained even on the land track 1406 sandwiched between the groove track 1405 and the groove track 1407.
- FIG. 29 is a schematic diagram for explaining the data arrangement structure of the address information in the fifth embodiment.
- the optical disc according to the fifth embodiment is composed of two kinds of groove tracks 1405 and groove tracks 1407 alternately switched in one rotation, and the groove track 1405 and groove track 1407 change the data pattern for recording address information.
- the optical disc according to the fifth embodiment is composed of two kinds of groove tracks 1405 and groove tracks 1407 alternately switched in one rotation, and the groove track 1405 and groove track 1407 change the data pattern for recording address information.
- one bit of address data is composed of address unit bits 1900 composed of 56 wobbles.
- address data 1902 and 1903 are address data of 1/0 recording format (Type 1) in groove track 1405 respectively
- address data 1904 and 1905 are 1/0 recording format in groove track 1407 ( It is address data of Type 2).
- MSK wobble 1906 hatchched portion in FIG. 29
- the shape of the wobble is changed at two places.
- the MSK wobble 1906 having a special wobble pattern it comprises a normal wobble 1907 having a normal wobble pattern.
- a plurality of types of 1/0 data can be expressed by changing the appearance position of the MSK wobble 1906 having this special wobble pattern.
- the wobble signal of the MSK wobble 1906 is represented by cos (1.5 ⁇ t), -cos ( ⁇ t) and -cos (1.5 ⁇ t), and the wobble signal of the normal wobble 1907 is represented by cos ( ⁇ t).
- a sync pattern 1901 commonly used for the groove track 1405 and the groove track 1407 and address data 1902 of the 0/1 pattern corresponding to the groove tracks 1405 and 1407. , 1903, 1904, and 1905 are used.
- the position of the MSK wobble 1906 is different for each pattern. Therefore, it is possible to demodulate the address data 1902, 1903, 1904 and 1905 without interfering with each other. Therefore, the pattern of the address data 1902, 1903, 1904, and 1905 of the groove adjacent to the land is formed as a pattern that does not interfere with each other, so that the address data can be demodulated even when the land is traced. . This can be realized by the patterns of the address data 1902, 1903, 1904 and 1905 being different in the track scanning direction.
- the synchronization pattern 1901 which is information for identifying the start position of the address is the same information between adjacent groove tracks, and a common pattern can be used because no common interference occurs.
- FIG. 30 is a diagram showing the structure of address information 1408, 1409, 1410, 1411, 1412, 1413, which is composed of a plurality of address unit bits 1900, in the fifth embodiment of the present invention.
- the synchronization pattern 1901 is data common to the adjacent groove track 1405 and groove track 1407, the common pattern is used.
- one synchronization pattern 1901 is used, but the reliability of synchronization can also be improved by using a plurality of synchronization patterns 1901.
- the synchronization pattern in the fifth embodiment is one type, it is also possible to use a pattern in which the position of the MSK wobble 1906 is different for the synchronization pattern. Also in this case, since the synchronization pattern is common between the adjacent groove track 1405 and groove track 1407, it is not necessary to prepare separate synchronization patterns for the groove track 1405 and the groove track 1407, respectively. Thus, the number of necessary wobble patterns can be reduced by using a common wobble pattern for data common to adjacent groove tracks.
- the address data 2001 is address data used for the groove track 1405
- the error correction code 2002 is an error correction code added for correcting an error of the address data 2001
- both recording types are Type 1 Is used.
- the address data 2003 is address data used for the groove track 1407
- the error correction code 2004 is an error correction code added to correct an error of the address data 2003, and both are recorded as Type 2 The format is used.
- a designated address that designates a position to be played back and a playback request including the playback length are input to the system controller 115 via the host I / F 118.
- the system controller 115 controls the spindle motor 102, the optical head 103 and the servo controller 104 based on the reproduction address information from the address demodulator 114 to move the spot of the optical head 103 to the groove track 1405, Start playback.
- the timing controller 138 generates a timing signal based on the timing signal generation instruction from the system controller 115 and the address blocks 1402 and 1404, which are address information reproduced by the address demodulator 114, and generates the generated timing signal. Output to the memory 139. In this case, as shown in FIG. 28, the timing signal is started to be output at the boundary between the address block 1404 and the address block 1403 and is output for a reproduction length instructed by the host.
- the memory 139 holds reproduction data recorded in the address block 1403 of the groove track 1405.
- the system controller 115 controls the spindle motor 102, the optical head 103 and the servo controller 104 based on the reproduction address information from the address demodulator 114 to move the spot of the optical head 103 to the land track 1406.
- Start playback of the address The timing controller 138 generates a timing signal based on the timing signal generation instruction from the system controller 115 and the address blocks 1402 and 1404, which are address information reproduced by the address demodulator 114, and generates the generated timing signal.
- Output to the memory 139 In this case, as shown in FIG. 28, the timing signal is started to be output at the boundary between the address block 1404 and the address block 1403 and is output for a reproduction length instructed by the host.
- the memory 139 holds the reproduction data recorded in the address block 1403 of the land track 1406.
- the system controller 115 controls the spindle motor 102, the optical head 103 and the servo controller 104 based on the reproduction address information from the address demodulator 114 to move the spot of the optical head 103 to the groove track 1407.
- Start playback of the address The timing controller 138 generates a timing signal based on the timing signal generation instruction from the system controller 115 and the address blocks 1402 and 1404, which are address information reproduced by the address demodulator 114, and generates the generated timing signal.
- Output to the memory 139 In this case, as shown in FIG. 28, the timing signal is started to be output at the boundary between the address block 1404 and the address block 1403 and is output for a reproduction length instructed by the host.
- the memory 139 holds reproduction data recorded in the address block 1403 of the groove track 1407.
- the reproduced waveform data recorded in the address block 1403 of the groove track 1405 whose phases are aligned in the radial direction, and the reproduced waveform data recorded in the address block 1403 of the land track 1406;
- the reproduced waveform data recorded in the address block 1403 of the groove track 1407 is stored.
- the crosstalk component can be removed by the processing described in the second embodiment, and the error rate of the data demodulated by the data decoder 108 is reduced. Can.
- the procedure for storing the reproduced waveform data in the memory 139 is not limited to the above. Further, the reproduction waveform data of the three recording tracks may not be stored in the memory 139, and the reproduction waveform data of the two recording tracks may be stored in the memory 139 and the crosstalk cancellation processing may be performed. When two pieces of reproduction waveform data are used, the effect of eliminating the crosstalk component is reduced more than when three pieces of reproduction waveform data are used, but the crosstalk component of the recording track adjacent to one can be eliminated.
- address information indicating position information in the recording surface of the optical disc is recorded by a predetermined pattern by wobbling of the recording track, and an integral multiple of the wobbling period of the portion other than the address information of the recording track is the recording track
- the length of one cycle matches, and the integral multiple of the period of the address information matches the length of one cycle of the recording track.
- Addresses are arranged in the format configuration of the optical disk as described above, a timing controller for detecting address boundaries is provided, and reproduction waveform data of recording data of three recording tracks using timing signals of the timing controller Is stored in memory.
- the reproduction waveform data can be stored in a state where the phases are aligned in the radial direction, it is not necessary to largely correct the phase.
- a phase correction circuit that corrects the phase of several tens of channel bits is not necessary, and a signal processing circuit that removes crosstalk components can be configured on a small scale.
- An information reproducing apparatus forms one optical laser spot on one recording track on an information recording medium in which data is recorded on a plurality of adjacent recording tracks, and the optical disc
- An information reproducing apparatus for reproducing the data based on reflected light from a laser spot, the first light receiving unit for receiving the reflected light at the central part of the recording track, and the information recording medium with respect to the central part
- An optical detector divided by a dividing line parallel to the recording track scanning direction, and an output signal from the first light receiving unit;
- a data decoder for decoding the reproduced data based on the output waveform from the filter.
- the optical detector receives the first light receiving portion that receives the reflected light at the central portion of the recording track, and the reflected light at a portion adjacent to the central portion in the radial direction of the information recording medium
- a second light receiving portion is divided by a dividing line parallel to the track scanning direction.
- the first adaptive equalization filter equalizes the output signal from the first light receiving unit.
- the second adaptive equalization filter equalizes the output signal from the second light receiving unit.
- the data decoder decodes the reproduced data based on the output waveform from the first adaptive equalization filter and the output waveform from the second adaptive equalization filter.
- the signal component of the own track scanned by the center of the optical laser spot and the crosstalk component from the track adjacent to the own track are detected from one optical laser spot, and a large-scale circuit is not implemented. Since the crosstalk component having a predetermined frequency can be equalized to a desired PR characteristic while removing the crosstalk component, the error rate of the reproduction data can be reduced, and the reproduction performance can be improved.
- the data decoder binarizes the addition result of the output waveform from the first adaptive equalization filter and the output waveform from the second adaptive equalization filter.
- an error detector for calculating an error between the equalization target waveform calculated based on the binarization processing result by the data decoder and the addition result, and the error calculated based on the error detector. Calculating a coefficient used in the second adaptive equalization filter on the basis of the first coefficient calculation unit calculating the coefficient used in the first adaptive equalization filter; and the error calculated by the error detector It is preferable to further comprise a second coefficient calculating unit.
- the data decoder binarizes the addition result of the output waveform from the first adaptive equalization filter and the output waveform from the second adaptive equalization filter.
- the error detector calculates an error between the equalization target waveform calculated based on the binarization processing result by the data decoder and the addition result.
- the first coefficient calculator calculates coefficients used in the first adaptive equalization filter based on the error calculated by the error detector.
- the second coefficient calculating unit calculates coefficients used in the second adaptive equalization filter based on the error calculated by the error detector.
- the first adaptive equalization filter is a waveform of an addition result of a waveform of an output signal from the first light receiving unit and an output waveform from the second adaptive equalization filter.
- Equalizing the data decoder binarizes the output waveform from the first adaptive equalization filter, and the result of the binarization processing by the data decoder and an output signal from the first light receiving unit A third adaptive equalization filter that outputs an ideal reproduced waveform based on the addition result of the second waveform and the output waveform from the second adaptive equalization filter, and the binarization processing result by the data decoder
- the first adaptive equalization filter equalizes the addition result of the waveform of the output signal from the first light receiving unit and the output waveform from the second adaptive equalization filter.
- the data decoder binarizes the output waveform from the first adaptive equalization filter.
- the third adaptive equalization filter is based on the binarization processing result by the data decoder and the addition result of the waveform of the output signal from the first light receiving unit and the output waveform from the second adaptive equalization filter. Output an ideal reproduced waveform.
- the first coefficient calculator is configured to calculate a first coefficient based on an error signal between an equalization target waveform obtained based on a result of binarization processing by the data decoder and an output waveform from the first adaptive equalization filter.
- the second coefficient calculation unit is configured to add the result of adding the waveform of the output signal from the first light receiving unit and the output waveform from the second adaptive equalization filter, and the output waveform from the third adaptive equalization filter.
- the coefficients used in the second adaptive equalization filter are calculated based on the error signal.
- the signal component of the own track scanned by the center of the optical laser spot and the crosstalk component from the track adjacent to the own track are detected from one optical laser spot, and a large-scale circuit is not implemented.
- equalization can be performed to a desired PR characteristic, so that the error rate of the reproduction data can be reduced, and the reproduction performance can be improved.
- a value obtained by dividing the radial width of the first light receiving portion by the radial width of the second light receiving portion is in the range of 0.75 to 2.25. Is preferred.
- the value obtained by dividing the radial width of the first light receiving portion by the radial width of the second light receiving portion is in the range of 0.75 to 2.25, the value from the adjacent track can be obtained.
- the crosstalk component can be removed with high accuracy.
- the second light receiving unit is a third light receiving unit that receives the reflected light of a portion adjacent to one of the central portion in the radial direction of the information recording medium; And a fourth light receiving unit for receiving reflected light of a portion adjacent to the other in the radial direction of the information recording medium with respect to a central portion, wherein the second adaptive equalization filter is configured to receive the light from the third light receiving unit.
- a fourth adaptive equalization filter for equalizing the output signal from the fourth light receiving section further comprises: The addition result of the output waveform from the first adaptive equalization filter, the output waveform from the third adaptive equalization filter, and the output waveform from the fourth adaptive equalization filter is binarized and the data is processed.
- Equalization calculated based on the result of binarization processing by the decoder An error detector that calculates an error between a reference waveform and the addition result, and a first coefficient that calculates a coefficient used in the first adaptive equalization filter based on the error calculated by the error detector A calculating unit; a second coefficient calculating unit that calculates a coefficient used in the third adaptive equalization filter based on the error calculated by the error detector; and the error calculated by the error detector It is preferable to further include a third coefficient operation unit that calculates coefficients used in the fourth adaptive equalization filter based on the above.
- the second light receiving unit includes the third light receiving unit that receives the reflected light of a portion adjacent to one of the central portions in the radial direction of the information recording medium, and the information recording unit relative to the central portion. And a fourth light receiving unit that receives the reflected light of a portion adjacent to the other in the radial direction of the medium.
- the second adaptive equalization filter is a third adaptive equalization filter that waveform-equalizes an output signal from a third light-receiving unit, and a fourth adaptation that waveform-equalizes an output signal from a fourth light-receiving unit And an equalization filter.
- the data decoder binarizes the addition result of the output waveform from the first adaptive equalization filter, the output waveform from the third adaptive equalization filter, and the output waveform from the fourth adaptive equalization filter. .
- the error detector calculates an error between the equalization target waveform calculated based on the binarization processing result by the data decoder and the addition result.
- the first coefficient calculator calculates coefficients used in the first adaptive equalization filter based on the error calculated by the error detector.
- the second coefficient calculating unit calculates coefficients used in the third adaptive equalization filter based on the error calculated by the error detector.
- the third coefficient calculator calculates coefficients used in the fourth adaptive equalization filter based on the error calculated by the error detector.
- crosstalk components from adjacent tracks can be removed using output signals from the three light receivers.
- the second light receiving unit is a third light receiving unit that receives the reflected light of a portion adjacent to one of the central portion in the radial direction of the information recording medium; And a fourth light receiving unit for receiving reflected light of a portion adjacent to the other in the radial direction of the information recording medium with respect to a central portion, wherein the second adaptive equalization filter is configured to receive the light from the third light receiving unit.
- a fourth adaptive equalization filter for equalizing the output signal from the fourth light receiving section, and the data decoder further comprises: Binarizing the addition result of the output waveform from the first adaptive equalization filter, the output waveform from the third adaptive equalization filter, and the output waveform from the fourth adaptive equalization filter;
- the output signal from the light receiving unit 3 and the output signal from the fourth light receiving unit A wobble detector for detecting a wobble signal from a difference between, preferably further comprises an address demodulator for demodulating an address from said detected wobble signal by the wobble detector.
- the second light receiving unit includes the third light receiving unit that receives the reflected light of a portion adjacent to one of the central portions in the radial direction of the information recording medium, and the information recording unit relative to the central portion. And a fourth light receiving unit that receives the reflected light of a portion adjacent to the other in the radial direction of the medium.
- the second adaptive equalization filter is a third adaptive equalization filter that waveform-equalizes an output signal from a third light-receiving unit, and a fourth adaptation that waveform-equalizes an output signal from a fourth light-receiving unit And an equalization filter.
- the data decoder binarizes the addition result of the output waveform from the first adaptive equalization filter, the output waveform from the third adaptive equalization filter, and the output waveform from the fourth adaptive equalization filter.
- the wobble detection unit detects the wobble signal from the difference between the output signal from the third light receiving unit and the output signal from the fourth light receiving unit.
- the address demodulator demodulates the address from the wobble signal detected by the wobble detector.
- the address information can be stably reproduced from the wobble signal while removing the crosstalk component from the adjacent track by using the output signals from the three light receivers.
- the radial width of the first light receiving portion divided by the radial width of the third light receiving portion and the radial width of the first light receiving portion is preferably in the range of 1.5 to 4.5.
- the radial width of the first light receiving portion divided by the radial width of the third light receiving portion and the radial width of the first light receiving portion are the radius of the fourth light receiving portion. If the value divided by the width of the direction is in the range of 1.5 to 4.5, crosstalk components from adjacent tracks can be removed with high accuracy.
- the second light receiving unit is a third light receiving unit that receives the reflected light of a portion adjacent to one of the central portion in the radial direction of the information recording medium; And a fourth light receiving unit for receiving reflected light of a portion adjacent to the other in the radial direction of the information recording medium with respect to a central portion, wherein the first light receiving unit is for the third light receiving unit.
- a fifth light receiving unit adjacent to the central side in the radial direction of the information recording medium, and a sixth light receiving adjacent to the central side in the radial direction of the information recording medium with respect to the fourth light receiving unit A third adaptive equalization filter that waveform-equalizes an output signal from the third light receiving unit, and an output signal from the fourth light receiving unit.
- a fourth adaptive equalization filter for waveform equalization, said first adaptive equalization filter A fifth adaptive equalization filter for equalizing the output signal from the fifth light receiving unit; and a sixth adaptive equalizing filter for equalizing the output signal from the sixth light receiving unit
- the data decoder includes an output waveform from the third adaptive equalization filter, an output waveform from the fourth adaptive equalization filter, an output waveform from the fifth adaptive equalization filter, and the sixth.
- the addition result with the output waveform from the adaptive equalization filter is binarized, and the error between the equalization target waveform calculated based on the binarization processing result by the data decoder and the addition result is calculated.
- An error detector; a first coefficient calculator configured to calculate a coefficient used in the fifth adaptive equalization filter based on the error calculated by the error detector; and the above calculated by the error detector The sixth based on the error.
- the second light receiving unit includes the third light receiving unit that receives the reflected light of a portion adjacent to one of the central portions in the radial direction of the information recording medium, and the information recording unit relative to the central portion. And a fourth light receiving unit that receives the reflected light of a portion adjacent to the other in the radial direction of the medium.
- the first light receiving unit is a fifth light receiving unit adjacent to the third light receiving unit on the central side in the radial direction of the information recording medium, and the fourth light receiving unit is in the radial direction of the information recording medium
- a sixth light receiving unit adjacent to the central portion.
- the second adaptive equalization filter is a third adaptive equalization filter that waveform-equalizes an output signal from a third light-receiving unit, and a fourth adaptation that waveform-equalizes an output signal from a fourth light-receiving unit And an equalization filter.
- the first adaptive equalization filter is a fifth adaptive equalization filter that waveform-equalizes an output signal from a fifth light-receiving unit, and a sixth adaptation that waveform-equalizes an output signal from a sixth light-receiving unit And an equalization filter.
- the data decoder comprises an output waveform from the third adaptive equalization filter, an output waveform from the fourth adaptive equalization filter, an output waveform from the fifth adaptive equalization filter, and a output waveform from the sixth adaptive equalization filter.
- the addition result with the output waveform is binarized.
- the error detector calculates an error between the equalization target waveform calculated based on the binarization processing result by the data decoder and the addition result.
- the first coefficient calculator calculates coefficients used in the fifth adaptive equalization filter based on the error calculated by the error detector.
- the second coefficient calculating unit calculates coefficients used in the sixth adaptive equalization filter based on the error calculated by the error detector.
- the third coefficient calculator calculates coefficients used in the third adaptive equalization filter based on the error calculated by the error detector.
- the fourth coefficient calculator calculates coefficients used in the fourth adaptive equalization filter based on the error calculated by the error detector.
- crosstalk components from adjacent tracks can be removed using output signals from the four light receivers.
- a first addition signal obtained by adding an output signal from the third light receiving unit and an output signal from the fifth light receiving unit, and an output from the fourth light receiving unit A wobble detection unit for detecting a wobble signal from a difference between a signal and a second addition signal obtained by adding the output signal from the sixth light receiving unit, and demodulating an address from the wobble signal detected by the wobble detection unit And an address demodulator.
- the wobble detection unit adds the output signal from the third light receiving unit to the output signal from the fifth light receiving unit, and the output signal from the fourth light receiving unit.
- the wobble signal is detected from the difference between the second addition signal obtained by adding the output signal from the sixth light receiving unit and the second addition signal.
- the address demodulator demodulates the address from the wobble signal detected by the wobble detector.
- the address information can be stably reproduced from the wobble signal while removing the crosstalk component from the adjacent track using the output signals from the four light receivers.
- An information reproducing apparatus forms one optical laser spot on one recording track on an information recording medium in which data is recorded on a plurality of adjacent recording tracks, and An information reproducing apparatus for reproducing the data based on light reflected from an optical laser spot, wherein address information indicating position information in the recording surface of the information recording medium is recorded according to a predetermined pattern by wobbling of the recording track.
- An address demodulator which matches and demodulates the address information of the information storage medium;
- a timing controller for generating a timing signal in phase in the radial direction based on address information; and a reproduction waveform of data recorded on a first recording track for which reproduction of the data is desired based on the timing signal
- a memory holding a reproduction waveform of data recorded in a second recording track adjacent to the first recording track, and a waveform of the reproduction waveform from the first recording track held in the memory
- a first adaptive equalization filter for equalizing, a second adaptive equalization filter for waveform equalization of the reproduced waveform from the second recording track held in the memory, and the first adaptive equalization
- a data decoder that binarizes the addition result of the output waveform from the filter and the output waveform from the second adaptive equalization filter, and the binar
- the address information indicating the position information in the recording surface of the information recording medium is recorded by the predetermined pattern by the wobbling of the recording track. Further, the integral multiple of the wobbling period of the portion other than the address information of the recording track coincides with the length of one round of the recording track. Furthermore, an integral multiple of the period of the address information matches the length of one round of the recording track. Then, the address demodulator demodulates the address information of the information recording medium. The timing controller generates a radially in-phase timing signal based on the address information demodulated by the address demodulator.
- the memory reproduces a reproduction waveform of data recorded on a first recording track desired to reproduce data and a reproduction of data recorded on a second recording track adjacent to the first recording track based on the timing signal. Hold the waveform.
- the first adaptive equalization filter equalizes the reproduced waveform from the first recording track held in the memory.
- the second adaptive equalization filter equalizes the reproduced waveform from the second recording track held in the memory.
- the data decoder binarizes the addition result of the output waveform from the first adaptive equalization filter and the output waveform from the second adaptive equalization filter.
- the error detector calculates an error between the equalization target waveform calculated based on the binarization processing result by the data decoder and the addition result.
- the first coefficient calculator calculates coefficients used in the first adaptive equalization filter based on the error calculated by the error detector.
- the second coefficient calculating unit calculates coefficients used in the second adaptive equalization filter based on the error calculated by the error detector.
- the reproduction waveform can be held in a state where the phases are aligned in the radial direction, it is not necessary to largely correct the phase, and a phase correction circuit to correct the phase is unnecessary, and a small scale signal processing circuit to remove crosstalk components Can be composed of
- an information reproducing method comprising: forming an optical laser spot on one recording track on an information recording medium in which data is recorded on a plurality of adjacent recording tracks; An information reproducing method for reproducing the data based on reflected light from an optical laser spot, the method comprising: a first light receiving step for receiving the reflected light at a central portion of the recording track; and the information recording with respect to the central portion.
- a second light receiving step for receiving reflected light of a portion adjacent in the radial direction of the medium; a first adaptive equalization filter processing step for waveform equalizing an output signal in the first light receiving step; A second adaptive equalization filter processing step of waveform equalizing an output signal in the light receiving step; an output waveform in the first adaptive equalization filter processing step and the second adaptation Including a data decoding step of decoding the reproduced data on the basis of an output waveform in the filter processing steps.
- the reflected light at the central portion of the recording track is received.
- the second light receiving step reflected light of a portion adjacent to the central portion in the radial direction of the information recording medium is received.
- the output signal in the first light receiving step is waveform-equalized.
- the output signal in the second light receiving step is waveform-equalized.
- the reproduction data is decoded based on the output waveform in the first adaptive equalization filter processing step and the output waveform in the second adaptive equalization filter processing step.
- the signal component of the own track scanned by the center of the optical laser spot and the crosstalk component from the track adjacent to the own track are detected from one optical laser spot, and a large-scale circuit is not implemented. Since the crosstalk component having a predetermined frequency can be equalized to a desired PR characteristic while removing the crosstalk component, the error rate of the reproduction data can be reduced, and the reproduction performance can be improved.
- the reproduction performance can be improved, and one optical laser spot is formed on one recording track on an information recording medium in which data is recorded on a plurality of adjacent recording tracks,
- the present invention is useful for an information reproducing apparatus and an information reproducing method for reproducing the data based on the reflected light from the optical laser spot.
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Abstract
Description
図1は、本発明の実施の形態1における情報記録再生装置の構成を示す図である。図2は、本発明の実施形態1における再生データ検出用光学検出器の構成を示す図である。図3は、本発明の実施形態1におけるウォブル検出用光学検出器の構成を示す図である。
図8は、本発明の実施の形態2における情報記録再生装置の構成を示す図である。まず、図1の実施の形態1との差分を説明する。大きな差分は、クロストーク成分を除去するための波形整形(等化)目標が異なる点である。実施の形態1では、クロストーク成分除去後の波形等化の目標が、所望のPR方式への等化であった。これに対して、実施の形態2では、クロストーク成分除去後の波形等化の目標が、クロストーク成分が無い再生信号への等化である。再生信号の周波数特性に対して、目標のPR方式の周波数特性の高域特性が不足している場合は、適応等化フィルタで高域成分を強調する必要がある。これは、波形を歪ませる原因となる。さらに、図6及び図7で説明したようにクロストーク成分を除去する場合、高域成分を強調する特性である必要がある。よって、不必要に再生波形の高域成分を強調すると、クロストーク成分を十分に除去できない場合がある。
図10は、本発明の実施の形態3における情報記録再生装置の構成を示す図である。まず、図1の実施の形態1との差分を説明する。大きな差分は、光ヘッドから3分割された再生信号が出力され、3つの再生信号からクロストーク成分を除去する点である。光ヘッドと光ディスクとの傾きによって発生するラジアルチルト、及びレーザスポットがトラックの中心を走査しないオフトラックなどにより、A信号のクロストーク成分とD信号のクロストーク成分とに偏りが発生する場合がある。この場合、偏りを除去できるように両隣のトラックからの漏れこみ信号を別々に処理する構成が望ましい。
図25は、本発明の実施の形態4における情報記録再生装置の構成を示す図である。まず、図1の実施の形態1~3との差分を説明する。大きな差分として、実施の形態1~3のクロストークキャンセル処理は、記録されたデータ信号に対してのみのクロストークをキャンセルしているが、実施の形態4のクロストークキャンセル処理は、図31で説明したトラック溝をウォブリングすることによって形成されたアドレス情報に対してもクロストークをキャンセルする。アドレス情報の再生性能の評価方法の一つとして、CN比(信号のキャリアレベルとノイズレベルとの比)の評価がある。
図27は、本発明の実施の形態5における情報記録再生装置の構成を示す図であり、図28は、本発明の実施の形態5における情報記録媒体の構成を示す図である。まず、従来技術の課題について説明する。上記「発明が解決しようとする課題」の項において、特許文献6の4つの課題を説明した。仮に、課題1~課題3を許容するシステムであっても、隣接トラックの再生データと自トラックの再生データとをメモリに入力するタイミングが課題となる。特許文献6において、隣接トラックのクロストーク成分と同期させるために、所定のタイミングで隣接トラックの再生信号がメモリに保持される。メモリに保持する隣接トラックの再生信号のタイミングのずれをある程度許容するために、特許文献6では、適応イコライザのタップ係数を増やして対応している。特許文献6では、数十クロックのタイミングずれを許容するために、256タップのイコライザが示されている。特許文献6の構成では、少なくとも多段のタップ係数を保有するイコライザを両隣接トラック分の2つ必要とする。そのため、回路規模の増大及び回路の複雑化が課題となっている。
Claims (11)
- 隣接する複数の記録トラック上にデータが記録された情報記録媒体に対して、一つの記録トラック上に一つの光学レーザスポットを形成して、前記光学レーザスポットからの反射光に基づいて前記データを再生する情報再生装置であって、
前記記録トラックの中心部の反射光を受光する第1の受光部と、前記中心部に対して前記情報記録媒体の半径方向に隣接する部分の反射光を受光する第2の受光部とに、記録トラック走査方向に平行な分割線により分割された光学検出器と、
前記第1の受光部からの出力信号を波形等化する第1の適応等化フィルタと、
前記第2の受光部からの出力信号を波形等化する第2の適応等化フィルタと、
前記第1の適応等化フィルタからの出力波形と前記第2の適応等化フィルタからの出力波形とに基づいて再生データを復号するデータ復号器と、
を備える情報再生装置。 - 前記データ復号器は、前記第1の適応等化フィルタからの出力波形と前記第2の適応等化フィルタからの出力波形との加算結果を2値化処理し、
前記データ復号器による2値化処理結果に基づいて算出される等化目標波形と、前記加算結果との誤差を算出する誤差検出器と、
前記誤差検出器によって算出された前記誤差に基づいて前記第1の適応等化フィルタにおいて用いられる係数を演算する第1の係数演算部と、
前記誤差検出器によって算出された前記誤差に基づいて前記第2の適応等化フィルタにおいて用いられる係数を演算する第2の係数演算部とをさらに備えることを特徴とする請求項1記載の情報再生装置。 - 前記第1の適応等化フィルタは、前記第1の受光部からの出力信号の波形と前記第2の適応等化フィルタからの出力波形との加算結果を波形等化し、
前記データ復号器は、前記第1の適応等化フィルタからの出力波形を2値化処理し、
前記データ復号器による2値化処理結果と、前記第1の受光部からの出力信号の波形と前記第2の適応等化フィルタからの出力波形との加算結果とに基づいて理想的な再生波形を出力する第3の適応等化フィルタと、
前記データ復号器による2値化処理結果に基づいて求められる等化目標波形と、前記第1の適応等化フィルタからの出力波形との誤差信号に基づいて、前記第1の適応等化フィルタにおいて用いられる係数を演算する第1の係数演算部と、
前記第1の受光部からの出力信号の波形と前記第2の適応等化フィルタからの出力波形との加算結果と、前記第3の適応等化フィルタからの出力波形との誤差信号に基づいて、前記第2の適応等化フィルタにおいて用いられる係数を演算する第2の係数演算部とをさらに備えることを特徴とする請求項1記載の情報再生装置。 - 前記第1の受光部の半径方向の幅を前記第2の受光部の半径方向の幅で割った値は、0.75~2.25の範囲であることを特徴とする
請求項1~3のいずれかに記載の情報再生装置。 - 前記第2の受光部は、前記中心部に対して前記情報記録媒体の半径方向の一方に隣接する部分の反射光を受光する第3の受光部と、前記中心部に対して前記情報記録媒体の半径方向の他方に隣接する部分の反射光を受光する第4の受光部とを含み、
前記第2の適応等化フィルタは、前記第3の受光部からの出力信号を波形等化する第3の適応等化フィルタと、前記第4の受光部からの出力信号を波形等化する第4の適応等化フィルタとを含み、
前記データ復号器は、前記第1の適応等化フィルタからの出力波形と前記第3の適応等化フィルタからの出力波形と前記第4の適応等化フィルタからの出力波形との加算結果を2値化処理し、
前記データ復号器による2値化処理結果に基づいて算出される等化目標波形と、前記加算結果との誤差を算出する誤差検出器と、
前記誤差検出器によって算出された前記誤差に基づいて前記第1の適応等化フィルタにおいて用いられる係数を演算する第1の係数演算部と、
前記誤差検出器によって算出された前記誤差に基づいて前記第3の適応等化フィルタにおいて用いられる係数を演算する第2の係数演算部と、
前記誤差検出器によって算出された前記誤差に基づいて前記第4の適応等化フィルタにおいて用いられる係数を演算する第3の係数演算部とをさらに備えることを特徴とする請求項1記載の情報再生装置。 - 前記第2の受光部は、前記中心部に対して前記情報記録媒体の半径方向の一方に隣接する部分の反射光を受光する第3の受光部と、前記中心部に対して前記情報記録媒体の半径方向の他方に隣接する部分の反射光を受光する第4の受光部とを含み、
前記第2の適応等化フィルタは、前記第3の受光部からの出力信号を波形等化する第3の適応等化フィルタと、前記第4の受光部からの出力信号を波形等化する第4の適応等化フィルタとを含み、
前記データ復号器は、前記第1の適応等化フィルタからの出力波形と前記第3の適応等化フィルタからの出力波形と前記第4の適応等化フィルタからの出力波形との加算結果を2値化処理し、
前記第3の受光部からの出力信号と前記第4の受光部からの出力信号との差分からウォブル信号を検出するウォブル検出部と、
前記ウォブル検出部によって検出された前記ウォブル信号からアドレスを復調するアドレス復調器とをさらに備えることを特徴とする請求項1記載の情報再生装置。 - 前記第1の受光部の半径方向の幅を前記第3の受光部の半径方向の幅で割った値及び前記第1の受光部の半径方向の幅を前記第4の受光部の半径方向の幅で割った値は、1.5~4.5の範囲であることを特徴とする
請求項5又は6記載の情報再生装置。 - 前記第2の受光部は、前記中心部に対して前記情報記録媒体の半径方向の一方に隣接する部分の反射光を受光する第3の受光部と、前記中心部に対して前記情報記録媒体の半径方向の他方に隣接する部分の反射光を受光する第4の受光部とを含み、
前記第1の受光部は、前記第3の受光部に対して前記情報記録媒体の半径方向の前記中心部側に隣接する第5の受光部と、前記第4の受光部に対して前記情報記録媒体の半径方向の前記中心部側に隣接する第6の受光部とを含み、
前記第2の適応等化フィルタは、前記第3の受光部からの出力信号を波形等化する第3の適応等化フィルタと、前記第4の受光部からの出力信号を波形等化する第4の適応等化フィルタとを含み、
前記第1の適応等化フィルタは、前記第5の受光部からの出力信号を波形等化する第5の適応等化フィルタと、前記第6の受光部からの出力信号を波形等化する第6の適応等化フィルタとを含み、
前記データ復号器は、前記第3の適応等化フィルタからの出力波形と前記第4の適応等化フィルタからの出力波形と前記第5の適応等化フィルタからの出力波形と前記第6の適応等化フィルタからの出力波形との加算結果を2値化処理し、
前記データ復号器による2値化処理結果に基づいて算出される等化目標波形と、前記加算結果との誤差を算出する誤差検出器と、
前記誤差検出器によって算出された前記誤差に基づいて前記第5の適応等化フィルタにおいて用いられる係数を演算する第1の係数演算部と、
前記誤差検出器によって算出された前記誤差に基づいて前記第6の適応等化フィルタにおいて用いられる係数を演算する第2の係数演算部と、
前記誤差検出器によって算出された前記誤差に基づいて前記第3の適応等化フィルタにおいて用いられる係数を演算する第3の係数演算部と、
前記誤差検出器によって算出された前記誤差に基づいて前記第4の適応等化フィルタにおいて用いられる係数を演算する第4の係数演算部とをさらに備えることを特徴とする請求項1記載の情報再生装置。 - 前記第3の受光部からの出力信号と前記第5の受光部からの出力信号とを加算した第1の加算信号と、前記第4の受光部からの出力信号と前記第6の受光部からの出力信号とを加算した第2の加算信号との差分からウォブル信号を検出するウォブル検出部と、
前記ウォブル検出部によって検出された前記ウォブル信号からアドレスを復調するアドレス復調器とをさらに備えることを特徴とする請求項8記載の情報再生装置。 - 隣接する複数の記録トラック上にデータが記録された情報記録媒体に対して、一つの記録トラック上に一つの光学レーザスポットを形成して、前記光学レーザスポットからの反射光に基づいて前記データを再生する情報再生装置であって、
前記情報記録媒体の記録面内の位置情報を示すアドレス情報が、前記記録トラックのウォブリングによる所定のパターンによって記録され、
前記記録トラックの前記アドレス情報以外の部分のウォブリングの周期の整数倍が、前記記録トラックの一周の長さと一致し、
前記アドレス情報の周期の整数倍が、前記記録トラックの一周の長さと一致し、
前記情報記録媒体の前記アドレス情報を復調するアドレス復調器と、
前記アドレス復調器によって復調された前記アドレス情報に基づいて、半径方向に位相の合ったタイミング信号を生成するタイミング制御器と、
前記タイミング信号に基づいて、前記データの再生を所望する第1の記録トラックに記録されたデータの再生波形と、前記第1の記録トラックに隣接する第2の記録トラックに記録されたデータの再生波形とを保持するメモリと、
前記メモリに保持された前記第1の記録トラックからの前記再生波形を波形等化する第1の適応等化フィルタと、
前記メモリに保持された前記第2の記録トラックからの前記再生波形を波形等化する第2の適応等化フィルタと、
前記第1の適応等化フィルタからの出力波形と前記第2の適応等化フィルタからの出力波形との加算結果を2値化処理するデータ復号器と、
前記データ復号器による2値化処理結果に基づいて算出される等化目標波形と、前記加算結果との誤差を算出する誤差検出器と、
前記誤差検出器によって算出された前記誤差に基づいて前記第1の適応等化フィルタにおいて用いられる係数を演算する第1の係数演算部と、
前記誤差検出器によって算出された前記誤差に基づいて前記第2の適応等化フィルタにおいて用いられる係数を演算する第2の係数演算部と、
を備える情報再生装置。 - 隣接する複数の記録トラック上にデータが記録された情報記録媒体に対して、一つの記録トラック上に一つの光学レーザスポットを形成して、前記光学レーザスポットからの反射光に基づいて前記データを再生する情報再生方法であって、
前記記録トラックの中心部の反射光を受光する第1の受光ステップと、
前記中心部に対して前記情報記録媒体の半径方向に隣接する部分の反射光を受光する第2の受光ステップと、
前記第1の受光ステップにおける出力信号を波形等化する第1の適応等化フィルタ処理ステップと、
前記第2の受光ステップにおける出力信号を波形等化する第2の適応等化フィルタ処理ステップと、
前記第1の適応等化フィルタ処理ステップにおける出力波形と前記第2の適応等化フィルタ処理ステップにおける出力波形とに基づいて再生データを復号するデータ復号ステップと、
を含む情報再生方法。
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JPWO2014054246A1 (ja) | 2016-08-25 |
JP6075379B2 (ja) | 2017-02-08 |
CN103975389B (zh) | 2016-12-28 |
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