JP2007042201A - Optical disk apparatus, and wobble reproducing method of optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To take out digital information from a wobble signal which is buried in wobble and obtained from a disk with easy means by performing MSK modulation and STW modulation for digital information such as address information. <P>SOLUTION: The optical disk apparatus has a function generating a wobble signal by high pass filters 73a, 73b, AGC circuits 74a, 74b, a differential amplifier 76 in which gain taking output difference of the AGC circuit 74a and the AGC circuit 74b can be set, a low pass filter 77, and a high pass filter 79. An AGC circuit 78 adjusting amplitude is provided so that an input for a through rate limiter circuit 81 becomes constant. The apparatus has the through rate limiter circuit 81 taking out a modulation component from the amplitude-adjusted wobble signal and a low pass filter circuit 82 or an envelope extracting circuit taking out a DC component from an output of the through rate limiter circuit 81, this output value is read, and a signal binarized by binarization circuits 83a, 83b is input to a decoder circuit 84. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disc device and an optical disc wobble reproduction method, and more particularly, an optical disc device and an optical disc for reproducing digital information such as address information embedded in a wobble signal recorded on a recordable optical disc. It is related with the wobble reproduction method.

  Currently, in addition to playback-only optical discs such as CD and DVD, CD-R / RW, DVD-R / RW, DVD + RW / R, DVD-RAM, HD DVD-R / RW, BD-RE, BD-R There are recordable optical discs. In these recordable optical disks, spiral grooves are engraved as recording tracks, and the grooves meander (wobble) in a slightly sinusoidal shape. This is called wobble.

  When this meandering track is scanned with an optical pickup, the amount of light returning to the detector divided into the left and right (inner and outer circumference sides) changes due to wobble. The push-pull signal obtained by subtracting the light amount difference between the left and right detectors is also called a wobble signal. In this wobble, address information indicating an absolute position on the disk is modulated and embedded so that the recording apparatus can write in the correct position.

  As a modulation method for embedding the address, a method of embedding by FM modulation or partial PSK modulation with respect to the fundamental frequency is well known, but the address information is modulated using two modulation methods described below. A scheme has been proposed. One modulation scheme is an MSK (Minimum Shift Keying) modulation scheme as shown in FIG. 1, and FIG. 1 shows waveforms before and after the MSK section. Another modulation method is an STW (Saw Tooth Wobble) modulation method as shown in FIGS. 2A, 2B, and 2C, and the waveform differs depending on the modulated information.

  On the disk, a block in which a carrier signal based on one period of wobble is continuous as a unit is configured as a unit, and the address information converted into digital information is embedded in this unit by MSK modulation, Another area is provided where the information is STW modulated.

  In the method using MSK modulation, an area of MSK modulation is embedded at a specific position in a unit with a specific width in units of a wobble reference carrier period. In this method, an MSK modulation area is embedded after a specific period based on modulation information.

  On the other hand, the method based on STW modulation is a signal in the same region as the reference carrier of the MSK unit in a different area from the MSK modulation unit in the unit, but compared with the sinusoidal meander based on the modulated digital information. A shape that inclines steeply toward the inner periphery of the disk and returns with a gentle inclination toward the outer periphery (hereinafter referred to as STW0), and a shape that undulates with a gentle inclination toward the inner periphery and returns with a steep inclination toward the outer periphery (hereinafter referred to as STW1). ) Is a modulation method in which either one is continuously performed in the unit.

  In this STW modulation method, the wobble shape or the wobble signal obtained from the wobble signal is similar to a saw tooth shape, so it is called STW (Saw Tooth Wobble). As an example, in the method in the Blu-ray disc standard, as shown in FIG. 1, cos (wt)..., W is an angular velocity, t is time, ... cos (1.5 wt), -cos (wt), -cos (1 .5 wt) and cos (wt) followed by MSK modulation (the MSK modulator is also referred to as an MSK mark). Next, STW is a waveform obtained by adding and subtracting (1/4) sin (2 wt) to the cos (wt) signal as the fundamental wave. cos (wt) + (1/4) sin (2wt) is a waveform that returns sharply after a gentle slope, indicating "1" (STW1), and cos (wt)-(1/4) sin (2wt) Is a waveform that returns slowly after a steep slope, and indicates “0” (STW0).

  As shown in FIG. 3, 56 wobble periods are one unit. In a unit representing “1” and “0”, the previous 18 wobbles are MSK marks or monotones (cos (not STW) In wt) waveform), one of two types of STWs exists in the rear 38 wobbles. The combination of the MSK mark insertion position and STW0 and STW1 represents digital information, and the digital information is decoded to indicate the minimum unit address on the disc. Actually, as shown in FIG. 3, there are four types of units for monotone unit, reference unit and synchronization in addition to 0/1 information, but the monotone unit and reference unit have only the MSK mark at the head of the unit. Since the synchronization unit has two MSK marks other than the head and is distinguished by changing the insertion position, it can be easily identified if the MSK mark can be detected.

JP 2003-123249 A JP 2003-223722 A JP 2004-227625 A International Publication WO 03/098798 "Dismantling new book next generation optical disc", page 66 (Nikkei Business Publications, issued on October 7, 2003)

  However, conventionally, a method for detecting an MSK-modulated region and determining whether the STW indicates “1” or STW indicating “0” has been proposed in Non-Patent Document 1, Patent Documents 1 and 2, and the like. .

  FIG. 4 is a block diagram of a conventional demodulator circuit based on a heterodyne system. This demodulator circuit includes an MSK modulated signal and an STW modulated signal, and a phase comparator 42, an oscillator 43, and a 1/2 frequency divider 44. Signals phase-adjusted via the phase adjusters 45a and 45b are respectively input to the multipliers 41a and 41b, and the outputs of the multipliers 41a and 41b are integrated by the integrators 46a and 46b. The binarized circuits 48a and 48b are binarized via 47b, and the MSK mark, STW0 and STW1 are input to the decoder circuit 49.

  However, in the conventional method as shown in FIG. 4, for detecting the MSK mark, the phase of the wobble frequency signal is adjusted and multiplied by the input wobble signal, and the output of the multiplier is integrated and binarized. In addition, the STW detection requires phase adjustment of the wobble frequency signal and twice the frequency signal, multiplying it by the input wobble signal, and further integrating the output of the multiplier to binarize. There was a need to do. Therefore, complicated circuits such as a PLL circuit and a multiplication circuit for generating signals having the necessary frequency and phase are required.

  Further, Patent Document 3 discloses an optical disc apparatus for recording / reproducing data with respect to an optical disc on which a sawtooth wobble (STW) is formed. Here, the output is binarized using a differentiation circuit. The STW is discriminated based on the difference between the HIGH and LOW lengths of the pulse, but the noise component is emphasized due to the use of a differentiation circuit. There was a problem that was necessary.

  The present invention has been made in view of such problems, and an object of the present invention is to easily convert digital information such as address information from an optical disc embedded in wobble by MSK modulation and STW modulation. It is an object of the present invention to provide an optical disc apparatus and a wobble reproduction method for an optical disc which are taken out by means.

  The present invention has been made in order to achieve such an object, and the invention according to claim 1 is characterized in that the digital information is STW modulated and embedded in a wobble of an optical disc, and the digital information embedded in the wobble is stored in the wobble. In an optical disk apparatus that reproduces from a wobble signal, the STW modulated signal uses a cosine wave and a sine wave of a specific frequency, and the cosine wave and the sine wave have a specific amplitude ratio according to a modulated digital signal. , A slew rate modulation signal with different directions obtained by addition or subtraction, a slew rate limiter circuit for extracting a modulation component from the wobble signal, and an average value or envelope is extracted from the output signal of the slew rate limiter circuit An extraction circuit and a binarization circuit that obtains a binarized signal from an output signal of the extraction circuit are provided.

  According to a second aspect of the invention, in the first aspect of the invention, the slew rate limiter circuit limits the rising and falling speeds to predetermined limit values in accordance with the input signal frequency and amplitude. It is characterized by being.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the input signal is input before the slew rate limiter circuit so that the amplitude of the input signal to the slew rate limiter circuit does not vary. An AGC circuit having a function of keeping the amplitude of a signal constant is provided.

  The invention according to claim 4 is the STW modulated waveform according to the invention according to claim 1 or 2, wherein the STW modulation waveform having a positive slice level and a negative slice level separately and having different directions is STW modulated. It is characterized by having a judging means for judging three waveforms, which are not normal waveforms.

  Further, the invention according to claim 5 is the invention according to claim 1, wherein the digital information is MSK modulated, embedded in the wobble of the optical disc together with the STW modulation, and the MSK modulated signal having a specific frequency. Using the first cosine wave as a carrier signal and using the second cosine wave having a frequency different from that of the carrier signal, the inverted signal of the first cosine wave, and the inverted signal of the second cosine wave, the phase is A bandpass filter circuit that passes the carrier frequency of the wobble signal in order to detect the MSK modulation region from the signal obtained by modulating the digital signal with the signal combined in a continuous manner and the frequency signal of the carrier signal; Envelope detection circuit for detecting an envelope of a signal that has passed through the bandpass filter circuit, and the envelope detection circuit Characterized by comprising a binarizing circuit for binarizing the output.

  Further, the invention described in claim 6 is characterized in that, in the invention described in claim 5, the determination level of the binarization circuit has a function of providing hysteresis.

  According to a seventh aspect of the present invention, in the fifth aspect of the present invention, an integration circuit that outputs a signal obtained by integrating the output of the slew rate limiter circuit, and the integration circuit is reset at the detection timing of the MSK modulation. And resetting the integrator output after the reset in the reset circuit as a slice level, and binarizing the signal before the reset.

  According to an eighth aspect of the present invention, there is provided an optical disc reproducing method in which digital information is STW modulated and embedded in a wobble of an optical disc, and the digital information embedded in the wobble is reproduced as a wobble signal. However, using a cosine wave and a sine wave of a specific frequency, the cosine wave and the sine wave have a specific amplitude ratio and are added or subtracted in accordance with the modulated digital signal, and the sawtooth wave shape has a different direction. A modulation signal is extracted from the wobble signal in the STW-modulated region using a slew rate limiter circuit, and an average value is extracted from the output signal of the slew rate limiter circuit using a filter circuit Or extracting an envelope using an envelope detector; and From the output signal of the filter circuit, characterized by a step of obtaining a binary signal using a binarization circuit.

  The invention according to claim 9 is the invention according to claim 8, wherein the digital information is MSK modulated, embedded in the wobble of the optical disc together with the STW modulation, and the MSK modulated signal having a specific frequency. Using the first cosine wave as a carrier signal and using the second cosine wave having a frequency different from that of the carrier signal, the inverted signal of the first cosine wave, and the inverted signal of the second cosine wave, the phase is A band-pass filter circuit is used to pass the carrier frequency of the wobble signal in order to detect the MSK modulation region from the signal obtained by modulating the digital signal with the signal combined in a continuous manner and the frequency signal of the carrier signal. And detecting an envelope of the signal that has passed through the bandpass filter circuit using an envelope detection circuit. A step, the output of the envelope detection circuit, characterized by a step of binarizing using a binarizing circuit.

  The present invention embeds digital information representing an address on a disc with a signal having a different MSK-modulated frequency at a specific position in accordance with the digital information with respect to most reference frequencies, and the frequency existing after that is wobbled. With an optical disk device that records or reproduces optical disks with wobbles that are modulated by using STW1 and STW0, which have different sawtooth shapes at the reference frequency of An optical pickup that receives the reflected laser light and extracts it as an electrical signal, a wobble signal extraction means that extracts a wobble signal from a signal output from the optical pickup, and a circuit that detects an STW shape by a slew rate limiter circuit , A circuit for extracting an average value (DC level) from the output, and STW1 from the output A circuit that determines whether it is STW0 and outputs it as binary data, a band-pass filter that passes the wobble reference frequency, a circuit that detects the envelope of the output, and a binarization circuit that detects the MSK mark from the envelope signal And address information composed of digital information embedded in the wobble is extracted.

  The slew rate limiter circuit is a circuit that limits the output slew rate (rising and falling speeds), and the increase side coefficient and the decrease side coefficient can be set in accordance with the wobble frequency and wobble amplitude. When an appropriate slew rate limit value is set for this wobble frequency, the output will be a triangular wave signal, and the average value of the slew rate limiter output will be the center level for normal waveforms that are not particularly modulated, but will be moderate. The average value (DC level) of the triangular waveform changes depending on whether the STW returns steeply after the inclination or the STW returns gently after the steep inclination.

  At this time, since the output of the slew rate limiter circuit cannot be binarized as it is, only the DC component is extracted and binarized through a low-pass filter circuit or an envelope detection circuit. According to the Blu-ray Disk standard, the direction of the sawtooth waveform lasts for a certain period, and it is only necessary to be able to determine the direction at the end of the unit. Therefore, a method using a signal obtained by integrating the triangular wave for a certain period may be considered. The start point of a certain interval is determined by recognizing the MSK modulated wobble shown in FIG.

  When the wobble signal is passed through a narrowband bandpass filter that passes the wobble reference frequency, the wobble amplitude of the bandpass filter output suddenly decreases because the wobble at the position of the MSK mark is different in frequency. To suddenly return to the original amplitude level. By taking the envelope of the bandpass filter output and binarizing it, the MSK position can be recognized, and the STW detection integrator is reset by this timing signal.

  This integrator integrates the output of the slew rate limiter circuit after reset by the MSK mark, and in the case of STW0, since the DC is negative, the output of the integrator decreases downward. In the case of STW1, since the DC is positive, the output of the integrator increases.

  Also, in the timing signal indicating the MSK mark position, if the number of wobble periods between the first MSK mark and the next MSK mark (or up to the third) is counted, the digital embedded in the unit It can be determined whether the data is 1 or 0, or whether it is a synchronous unit, a reference unit, or a monotone unit at the head of the unit.

  As described above, the optical disc apparatus and the optical disc playback method according to the present invention can receive embedded digital information from an optical disc in which addresses are embedded using wobbles using MSK modulation and STW modulation, such as a Blu-ray disc. In order to read out, an MSK modulated area (MSK mark) is detected and taken out as digital information specifying 0/1 from the position information, and whether the shape of the STW modulated wobble signal indicates “1”. , “0” is determined, and the digital information embedded in the specific area can be easily and reliably extracted from the position information of the MSK mark and the demodulation result of the STW modulation wobble.

  According to the present invention, in recording / playback of a disc using STW wobbles without using the conventional heterodyne method, the wobble is steeply returned after STW, or after steep inclination, Whether the STW returns gently or not can be stably and reliably performed by a simple method, and the circuit scale in the optical disc apparatus for recording / reproducing the target disc can be reduced.

  The slew rate limiter circuit used in the present invention can also be used as a slew rate limiter circuit used to remove the LPP on the DVD-R / RW disc and reduce wobble jitter.

  Also, the MSK mark position can be detected without using the conventional heterodyne method, and the synchronization timing and the reset timing of the integrator that integrates the slew rate limiter output of the STW modulator can be obtained by a simple method.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 7 is a block diagram showing Embodiment 1 of the optical disc apparatus of the present invention, and is a block diagram for extracting a wobble signal of the optical disc in the STW modulation method. In the figure, reference numeral 71 is an optical pickup, 72a and 72b are adders, 73a, 73b, 75a, 75b, 77 and 79 are high-pass filters, 74a, 74b and 78 are AGC circuits (automatic gain control circuit; output amplitude constant circuit), Reference numeral 76 denotes a differential amplifier, 81 denotes a slew rate limiter circuit, 82 denotes an average value or envelope extraction circuit, 83a and 83b denote binarization circuits, and 84 denotes a decoder circuit. FIG. 6 is a block diagram of a demodulation circuit using a slew rate limiter circuit, which is used in FIG.

  For the wobble signals of STW0 and STW1, in principle, as shown in FIG. 2, a slew rate limiter circuit (to be described later) shown in FIG. 5 generates a triangular wave signal, and the configuration shown in FIG. When applied to the low-pass filter 62, the DC change of the output of the slew rate limiter circuit 61 is extracted, and the binarization circuit 63 can easily perform binarization. This means that a signal equivalent to the signal obtained by the conventional heterodyne system shown in FIG. 4 can be obtained with a simple circuit without using a signal having a frequency twice the wobble frequency and a multiplier. In the present invention, this point is the maximum feature point.

  In other words, the optical disc apparatus of the present invention performs STW modulation on digital information and embeds it in the wobble of the optical disc, and reproduces the digital information embedded in this wobble from the wobble signal. The slew rate limiter circuit 61 extracts a modulation component from the wobble signal in the STW modulated region, and obtains a signal that limits the rising and falling speeds to a predetermined limit value. The filter circuit 62 extracts an average value or an envelope from the output signal of the slew rate limiter circuit 61. Further, the binarization circuit 63 obtains a binarization signal from the output signal of the filter circuit or envelope detection circuit 62.

  The STW modulated signal is obtained by using a cosine wave and a sine wave of a specific frequency, and adding or subtracting these cosine wave and sine wave with a specific amplitude ratio according to the modulated digital signal. This is a sawtooth modulation signal with different orientations.

  The wobble signal generated by reading from an actual optical disc includes noise due to the presence / absence of pits and low-frequency amplitude fluctuations due to crosstalk between adjacent wobbles, and is configured as shown in FIG.

  As shown in FIG. 7, when a wobble signal is extracted from a signal obtained from a meandering groove formed on an optical disc, an adder 72a is used to calculate the difference between the right and left reflected light amounts by the optical pickup 71. The A and D side outputs (A + D signal) and the B and C side outputs (B + C signal) by the adder 72b are generated.

  High-pass filters 73a and 73b for removing the DC offset components of the A + D signal and B + C signal, AGC circuits 74a and 74b for aligning the amplitudes of the A + D signal and the B + C signal to remove the RF component and the common-mode noise component, and the AGC circuit A differential amplifier 76 that can set a gain that takes the difference between the 74a output and the AGC circuit 74b output, a low-pass filter 77 that can change the cut-off according to the double speed to remove a noise component, and a DC offset or a low-frequency fluctuation And a high-pass filter 79 that removes the wobble signal.

  Further, even if the generated wobble signal is amplitude-modulated by crosstalk between adjacent tracks, it has a function of the AGC circuit 78 that adjusts the amplitude so that the input to the slew rate limiter circuit 81 becomes constant.

  Further, a slew rate limiter circuit 81 that extracts a modulation component from an amplitude-adjusted wobble signal and a low-pass filter circuit 82 that extracts a DC component from the output of the slew rate limiter circuit 81 are provided. The output value is read, and the signal binarized by the binarization circuits 83a and 83b is input to the decoder circuit 84 to decode the address.

  FIG. 5 is a diagram showing a slew rate limiter circuit used in the optical disk apparatus of the present invention. In the figure, reference numerals 51, 52 and 56 are constant current sources, 53 is an input terminal, 55 is an output level correction circuit, and 57 is an output terminal. Is shown. Here, an example of a slew rate limiter circuit 61 determined by a constant current I1 and a capacitance value C1 is shown (for example, see Patent Document 4). In the first embodiment, the slew rate value can be adjusted to the recording / reproducing speed by changing the constant current I1 and the capacitance value C1. The slew rate limiter circuit 61 shown in FIG. 5 includes a MOS transistor Q1, a current source 51 for supplying a constant current I1, a current source 52 for supplying a constant current I2, and a capacitor serving as a load for the MOS transistor Q1. C1.

  When the level of the input voltage Vin increases steeply, the MOS transistor Q1 is turned on, and the output voltage Vout is determined by the difference (I2-I1) between the constant current I2 and the constant current I1 and the capacitance value C1 of the capacitor C1. Increase at slew rate. On the other hand, when the level of the input voltage Vin sharply decreases, the MOS transistor Q1 is turned on, and the output voltage vout decreases at a slew rate determined by the constant current I1 and the capacitance value C1.

  Further, an output level correction circuit 55 including an operational amplifier OP1, an N-type MOS transistor Q2, and a current source 56 is provided. The operational amplifier OP1 includes a MOS transistor Q2 and a current source 56.

  In the first embodiment of the present invention shown in FIG. 7, the slew rate limit value of the slew rate limiter circuit 81 is 50 to 300 mV / wobble amplitude per 1 × speed (wobble frequency 956 kHz) of a Blu-ray disc with respect to a wobble amplitude of about 250 mVpp. About usec is selected, and the increase side coefficient and the decrease side coefficient are the same. Under this condition, when the wobble waveform shown in FIG. 2A is input, the slew rate limiter circuit 81 generates a signal having a triangular waveform of the STW waveform as shown in FIG.

  The output signal of the triangular wave-like slew rate limiter circuit 81 has a high DC level when the input waveform is a waveform that returns steeply after a gentle slope, and when the waveform returns slowly after a steep slope, the DC level is Lower. As shown in the waveform shown in FIG. 2C, when a low-pass filter circuit 82 is applied to the output of the slew rate limiter circuit 81, it can be extracted as a signal having a different average value (DC level). Further, as apparent from the waveform, by extracting the envelope (either the upper side or the lower side) of the output of the slew rate limiter circuit 81 instead of the low-pass filter circuit 82, it can be extracted as a signal having a different DC level.

  FIGS. 8A to 8D are diagrams showing operation waveforms based on real waveforms in the first embodiment of the present invention, and show output waveforms of the circuit of the embodiment based on actual Blu-ray disc playback signals. 8A is a Blu-ray wobble signal, FIG. 8B is a slew rate limiter output, FIG. 8C is a low pass filter output of the slew rate limiter output, and FIG. 8D is a slew rate limiter output. Is an output obtained by resetting and integrating at the MSK timing. 9A to 9D are partially enlarged waveform diagrams of FIGS. 8A to 8D.

  In the first embodiment, the operation waveform based on the actual waveform shown in FIG. 8C and the waveform shown in FIG. 9C (time axis expansion in FIG. 8C) are several kHz to 50 kHz at BD 1 × speed. A DC component is extracted from the output signal of the slew rate limiter circuit 81 by a low-pass filter circuit 82 of about the same level. By binarizing this signal, modulated data can be extracted from the STW modulation section.

  In addition, in order to determine three types of STW0, STW1, and normal cos (wt) waveforms that are not STW modulated, a comparator with separate positive side slice level and negative side slice level is prepared, and ternary in 2 bits. It is also possible to determine.

  If the signal input to the slew rate limiter circuit 81 is passed through a high-pass filter with a high cut-off range that does not affect the STW waveform, the fluctuation of the DC of the slew rate limiter output is reduced by a low-frequency fluctuation component. Although it becomes easy to digitize, a high high-pass filter cannot be so high because the phase relationship between the 1 × frequency component and the 2 × frequency component included in the STW waveform changes.

  In the wobble of about 950 kHz of BD 1 × speed, the primary is 100 kHz or less. A high-pass filter such as a linear phase or a Bessel type with little phase change within the STW band can increase the order and cut-off, and can be more resistant to low-frequency fluctuations.

  In an LSI, an offset may also occur in the output signal of the slew rate limiter circuit due to manufacturing variations, so it is desirable to provide an offset adjustment function.

  FIG. 10 is a block diagram showing Embodiment 2 of the optical disk apparatus of the present invention, and is a block diagram for extracting a wobble signal of the optical disk in the MSK modulation and STW modulation systems. Constituent elements having the same functions as those in FIG. The block diagram shown in FIG. 10 is the same as the block diagram shown in FIG. 7 except for the configuration for extracting the MSK mark, that is, the band-pass filter circuit 85 that passes the carrier frequency from the wobble signal in the MSK modulated region. An envelope detector (detection) circuit 86 for detecting the envelope of the signal that has passed through the band-pass filter circuit 85, and a binarization circuit 87 for binarizing the output of the envelope detector circuit 86.

  In addition, MSK-modulated signal detection uses a first cosine wave having a specific frequency as a carrier signal, a second cosine wave having a frequency different from the carrier signal, an inverted signal of the first cosine wave, MSK modulation is detected from a signal obtained by modulating a digital signal using a signal that is a combination of signals that are continuous in phase using an inverted signal of a cosine wave and a signal having a carrier signal frequency.

  As described above, the optical disk apparatus according to the second embodiment of the present invention uses the wobble signal in the area subjected to STW modulation with respect to the wobble signal in which digital information (address information on the disk) is embedded using MSK modulation and STW modulation. To output modulated information based on an average value (DC component) or an integrated value of the output via a slew rate limiter circuit 81, an average value extraction circuit 82, and binarization circuits 83a and 83b, and a bandpass filter. The circuit 85, the envelope detector circuit 86, and the binarization circuit 87 detect MSK modulation, and the synchronization timing and the modulated information are extracted from the extracted MSK modulation position information and STW wobble demodulation result. .

  That is, in the above-described first embodiment, as shown in the waveforms shown in FIGS. 8D and 9D, a slew rate limiter output can be used instead of the low-pass filter by using a conventional integrator with a reset function. it can. In the present invention, as shown in FIG. 10, the following method, which is not a conventional method, is used as the timing for resetting the integrator with reset.

  Similar to the first embodiment, a function for generating a wobble signal, a band-pass filter circuit 85 for passing a wobble frequency, an envelope detector circuit 86 for taking an envelope of the output of the band-pass filter circuit 85, and an envelope detector circuit 86 A device having a function of binarizing the output by a binarization circuit (comparator) 87 is used to detect an MSK-modulated region, and a digital signal that becomes 1 is generated by the MSK unit. This digital signal can be used as the reset timing of the integrator.

  The band-pass filter circuit 85 uses a second-order type with a gain of -3 dB at frequencies of about +10 to + 15% and -10 to -15% with respect to the wobble frequency. The envelope detector circuit 86 performs subtraction using a peak hold circuit and / or a bottom hold circuit. The peak hold circuit or the bottom hold circuit is set to droop about 10% to 30% in one wobble cycle.

  FIGS. 11A to 11D are diagrams showing the bandpass filter output and the envelope detector output. FIG. 11A is a Blu-ray wobble signal and slew rate limiter output. FIG. 11B is a bandpass. The filter output and its peak hold waveform and bottom hold waveform, FIG. 11C shows the binarized output of the peak hold output, and FIG. 11D shows the output obtained by resetting and integrating the slew rate limiter output at the MSK timing. Yes. 12 (a) to 12 (d) are partially enlarged waveform diagrams of FIGS. 11 (a) to 11 (d).

  The waveforms shown in FIGS. 11B and 12B are obtained by passing the actual wobble signal through the band-pass filter circuit 85 and taking the peak or bottom level by the envelope detector circuit 86. By binarizing this signal with a comparator 87 with hysteresis, the MSK mark can be easily detected as in the binary waveform shown in FIGS. 11 (c) and 12 (c). In the determination of the slice level, a fixed slice is sufficient by the AGC circuit 78, but the peak or bottom is detected by the envelope detector circuit 86 of the slow droop plate that is not followed by the MSK mark, and the output is divided at a specific ratio. It is also possible to determine the slice level.

  When an integrator that is reset at the detection timing of the MSK mark is used, the waveforms shown in FIGS. 11D and 12D are obtained. Further, from the signal timing obtained by binarizing the envelope detector output, the head of the unit, 0/1 information, synchronization information, reference information, and the like can be determined.

  After reading the output of the integrator that integrates the output of the slew rate limiter at the timing of the first MSK mark of the unit, the integrator is reset. For the read value, a comparator having a positive slice level and a negative slice level is prepared separately, and ternary determination is performed with 2 bits. By collectively determining the determination based on the MSK mark position and the determination based on the STW signal, the modulated data can be reliably reproduced.

  FIG. 13 is a flowchart for explaining a method for reproducing the address information embedded in the wobble of the optical disc according to the present invention. The optical disc reproducing method of the present invention is to reproduce the digital information embedded in the wobble from the wobble signal with respect to the optical disc embedded in the wobble by MSK modulation and STW modulation of the digital information.

  The processing differs depending on whether the wobble signal in the STW modulated area is reproduced or the wobble signal in the MSK modulated area is reproduced (S1). These processes are different processes but are performed in parallel. In the STW area, the MSK detection circuit operates in the same manner as in the monotone area (not STW or not subjected to MSK modulation). The STW detection circuit is not affected because the MSK mark portion is too short. The STW detection circuit outputs an intermediate value between STW0 and STW1 in the monotone portion. In order to reproduce (demodulate) the modulated information from the wobble signal in the STW modulated area, a modulation component is extracted using a slew rate limiter circuit, and a signal for limiting the rising and falling speeds to a predetermined limit value is obtained. Step (S2a), step (S3a) for extracting an average value from the output signal of the slew rate limiter circuit using a filter circuit, or extracting an envelope using an envelope detection circuit, and this filter circuit or envelope detection Obtaining a binarized signal from the output signal from the circuit using a binarizing circuit (S4a), and for detecting an MSK modulated region, a bandpass filter circuit is used. A step of passing the frequency (S1b), and an envelope of the signal that has passed through the band-pass filter circuit. A step (S2b) of detecting the signal using an envelope detection circuit, and a step (S3b) of binarizing the output of the envelope detection circuit using a binarization circuit. (S5).

  As described above, in the optical disc reproducing method of the present invention, the embedded digital information can be easily extracted from the optical disc in which digital information such as address information is MSK modulated and STW modulated and embedded in the wobble.

It is a figure which shows the waveform before and behind the MSK part. (A) thru | or (c) is a figure which shows a STW signal waveform, a slew rate limiter output waveform, and its low-pass filter output waveform. It is a figure which shows the ADIP unit (it comprises 56 wobbles of a Blu-ray disc standard). It is a block diagram of a demodulation circuit by the conventional heterodyne system. It is a figure which shows a slew rate limiter circuit. It is a block diagram of a demodulation circuit using a slew rate limiter circuit. It is a block diagram which shows Example 1 of the optical disk apparatus of this invention. (A) thru | or (d) is a figure which shows the operation | movement waveform by the real waveform in Example 1 of this invention. (A) thru | or (d) are the partial expanded waveform diagrams of Fig.8 (a) thru | or (d). It is a block diagram which shows Example 2 of the optical disk apparatus of this invention. (A) thru | or (d) is a figure which shows a band pass filter output and an envelope detector output. 12 (a) to 12 (d) are partially enlarged waveform diagrams of FIGS. 11 (a) to 11 (d). It is a figure which shows the flowchart for demonstrating the method to reproduce | regenerate the address information embedded in the wobble of the optical disk of this invention.

Explanation of symbols

41a, 41b multiplier 42 phase comparator 43 oscillator 44 1/2 divider 45a, 45b phase adjuster 46a, 46b integrator 47a, 47b sample hold circuit 48a, 48b binarization circuit 49 decoder circuit 51, 52, 56 Constant current source 53 Input terminal 55 Output level correction circuit 57 Output terminal 61 Slew rate limiter circuit 62 Low pass filter 63 Binarization circuit 71 Optical pickup 72a, 72b Adders 73a, 73b, 75a, 75b, 77, 79 High pass filter 74a, 74b, 78 AGC circuit (constant output amplitude circuit)
76 Differential Amplifier 81 Slew Rate Limiter Circuit 82 Average Value or Envelope Extraction Circuit 83a, 83b Binarization Circuit 84 Decoder Circuit 85 Band Pass Filter Circuit 86 Envelope Detector Circuit 87 Binarization Circuit

Claims (9)

In an optical disc apparatus that performs digital signal STW modulation and embeds it in a wobble of an optical disc, and reproduces the digital information embedded in the wobble from a wobble signal.
Direction obtained by adding or subtracting the cosine wave and sine wave at a specific amplitude ratio according to the modulated digital signal using a cosine wave and a sine wave of a specific frequency. A slew rate limiter circuit for extracting a modulation component from the wobble signal,
An extraction circuit for extracting an average value or an envelope from the output signal of the slew rate limiter circuit;
An optical disc apparatus comprising: a binarization circuit that obtains a binarized signal from an output signal of the extraction circuit.   2. The optical disc apparatus according to claim 1, wherein the slew rate limiter circuit limits a rising speed and a falling speed to a predetermined limit value in accordance with an input signal frequency and amplitude.   An AGC circuit having a function of keeping the amplitude of the input signal constant before the slew rate limiter circuit so that the amplitude of the input signal to the slew rate limiter circuit does not fluctuate. Item 3. The optical disk device according to Item 1 or 2.   And a determination unit configured to determine three waveforms, that is, a STW modulation waveform having a positive slice level and a negative slice level separately, and an STW modulation waveform having different directions and a normal waveform not subjected to STW modulation. Item 3. The optical disk device according to Item 1 or 2.   The digital information is MSK modulated and embedded in the wobble of the optical disc together with the STW modulation, and the first cosine wave having a specific frequency, which is the MSK modulated signal, is used as a carrier signal, and a second frequency having a frequency different from the carrier signal is used. Using a cosine wave, an inverted signal of the first cosine wave, an inverted signal of the second cosine wave, a signal combined so that phases are continuous, and a frequency signal of the carrier signal, a digital signal A band pass filter circuit that passes the carrier frequency of the wobble signal in order to detect an MSK modulation region from the modulated signal, an envelope detection circuit that detects an envelope of the signal that has passed through the band pass filter circuit, and And a binarization circuit for binarizing an output of the envelope detection circuit. The optical disk apparatus according to.   6. The optical disk apparatus according to claim 5, wherein the determination level of the binarization circuit has a function of providing hysteresis.   An integrator circuit that outputs a signal obtained by integrating the output of the slew rate limiter circuit; and a reset circuit that resets the integrator circuit at the detection timing of the MSK modulation, and the output of the integrator after reset in the reset circuit 6. The optical disk apparatus according to claim 5, wherein the signal before resetting is binarized with a slice level. In an optical disc reproducing method for digital information being STW modulated and embedded in a wobble of an optical disc, and reproducing the digital information embedded in the wobble as a wobble signal,
Direction obtained by adding or subtracting the cosine wave and sine wave at a specific amplitude ratio according to the modulated digital signal using a cosine wave and a sine wave of a specific frequency. Extracting a modulation component from the wobble signal in the STW modulated area using a slew rate limiter circuit,
Extracting an average value from the output signal of the slew rate limiter circuit using a filter circuit or extracting an envelope using an envelope detector;
Obtaining a binarized signal from the output signal of the filter circuit using a binarizing circuit. The digital information is MSK modulated and embedded in the wobble of the optical disc together with the STW modulation, and the first cosine wave having a specific frequency, which is the MSK modulated signal, is used as a carrier signal, and a second frequency having a frequency different from the carrier signal is used. Using a cosine wave, an inverted signal of the first cosine wave, an inverted signal of the second cosine wave, a signal combined so that phases are continuous, and a frequency signal of the carrier signal, a digital signal In order to detect the MSK modulation region from the modulated signal, a step of passing the carrier frequency of the wobble signal using a band pass filter circuit, and an envelope of the signal passing through the band pass filter circuit And detecting the output of the envelope detection circuit using a binarization circuit Wobble reproduction method of an optical disk according to claim 8, characterized in that a step of binarizing have.

Images