HK1064199B - Disc-shaped recording medium disc driving device and method and apparatus for producing disc - Google Patents

Description

Disc-shaped recording medium disc drive apparatus and method and apparatus for producing disc

Technical Field

The present invention relates to a disc-shaped recording medium having lands and/or grooves formed thereon in an annular manner to operate as recording tracks formed in a meandering manner in conformity with a wobble signal, a disc drive apparatus for recording and/or reproducing data for such a disc-shaped recording medium, and a method and apparatus for producing such a disc-shaped recording medium.

Background

Up to now, optical discs having guide grooves, called encircling pregrooves, have been known. If this pregroove is formed, the groove and/or land (the area sandwiched between adjacent turns of the groove) becomes the recording track. With this pregroove formed in the optical disc, the disc drive side responsible for recording and/or reproduction can detect components of both sides of the recording track from the reflected laser light to realize servo control so that the laser light illuminates both sides intensively.

An optical disc has been known so far in which a pregroove signal is made to meander along with a wobble signal corresponding to an FM-modulated or PSK-modulated carrier signal. The modulation component of the wobble signal contains, for example, physical address information of the recording track at the recording position of the wobble signal. Accordingly, the disc drive side responsible for recording and/or reproduction can detect a wobble signal from signals (so-called push-pull signals) indicating fluctuation components on both sides of the recording track to demodulate address information contained in the wobble signal, so as to perform address control of the recording and/or reproducing position.

However, with a system in which, for example, address information is inserted into a wobble signal corresponding to an FM-modulated carrier signal, there arises a problem in that address reproduction characteristics become deteriorated by crosstalk components from adjacent tracks. In a system in which address information is inserted into a wobble signal by PSK modulating a carrier signal, for example, there arises a problem that a higher harmonic of a phase change point is superimposed on a playback signal to deteriorate reproduction characteristics. Further, in the case of PSK modulation, since a higher harmonic component is contained, the circuit configuration of the wobble signal demodulation circuit becomes complicated as a result.

Disclosure of Invention

It is therefore an object of the present invention to provide a disc-shaped recording medium having information such as address information efficiently formed in a wobble component and in which the S/N ratio in reproducing the information contained in the wobble component can be improved, a disc drive apparatus for recording and/or reproducing data for this disc-shaped recording medium, and a method and apparatus for producing such a disc-shaped recording medium.

In order to achieve the above object, the present invention provides a disc-shaped recording medium having lands and/or grooves formed thereon in a ring-shaped manner to operate as recording tracks that meander by means of a wobble signal, wherein:

the wobble signal includes:

first digital information which is MSK-modulated by using a first sinusoidal signal of a predetermined frequency and using a second sinusoidal signal of a frequency different from the predetermined frequency, and

second digital information modulated on the sinusoidal carrier signal by adding even harmonic signals to the sinusoidal carrier signal and by changing the polarity of the harmonic signals in dependence on said second digital information (HMW modulated).

In another aspect, the present invention provides a disc-shaped recording medium having lands and/or grooves formed thereon in an annular manner to operate as recording tracks that meander by means of a wobble signal, wherein:

wherein address units having address information are formed in the wobble signal as predetermined data units, the address information including at least one address of the recording track,

constructing the address unit to include at least one block of bits representing bits forming the address information, an

At least one block is formed in a waveform of a sinusoidal carrier signal including a predetermined number of consecutive cycles by inserting a first bit string modulated with a sinusoidal carrier signal and with a sinusoidal signal MSK of a frequency other than the frequency of the sinusoidal carrier signal and by adding an even harmonic signal to the sinusoidal carrier signal and by forming a second bit string modulated on the sinusoidal carrier signal by changing the polarity of the harmonic signal in accordance with a second bit string (HMW modulation).

The present invention also provides a disc drive apparatus for recording and/or reproducing a disc-shaped recording medium having lands and/or grooves formed thereon in a ring-shaped manner to operate as recording tracks that meander by means of a wobble signal, the disc drive apparatus comprising:

wobble information demodulation means for reproducing the wobble signal from the disc-shaped recording medium and for demodulating the wobble signal to recover digital information contained in the wobble signal;

wherein the wobble information demodulation apparatus includes:

a first demodulation unit for recovering first digital information, which is MSK-modulated by using a first sinusoidal signal of a predetermined frequency and a sinusoidal signal of a frequency different from the predetermined frequency of the first sinusoidal signal; and

a second demodulation unit for recovering the second digital information, which is modulated on the sinusoidal carrier signal by adding the even harmonic signal to the sinusoidal carrier signal and by changing the polarity of the harmonic signal in dependence on the second digital information (HMW modulated).

In another aspect, the present invention provides an apparatus for manufacturing a disc-shaped recording medium by forming lands and/or grooves in a ring-shaped manner on a surface of a main disc of the disc-shaped recording medium, the apparatus comprising:

means for forming lands and/or grooves in a meandering manner by means of a wobble signal, said wobble signal comprising:

first digital information which is MSK-modulated by using a first sinusoidal signal of a predetermined frequency and a second sinusoidal signal of a frequency different from the predetermined frequency of the first sinusoidal signal, and

second digital information modulated on the sinusoidal carrier signal by adding the even harmonic signal to the sinusoidal carrier signal and by changing the polarity of the harmonic signal in dependence on the second digital information (HMW modulated).

In another aspect, the present invention provides a method for manufacturing a disc-shaped recording medium by forming lands and/or grooves in a ring-shaped manner on a surface of a main disc of the disc-shaped recording medium, the method comprising the steps of:

forming lands and/or grooves in a meandering manner by means of a wobble signal comprising:

first digital information which is MSK-modulated by using a first sinusoidal signal of a predetermined frequency and a second sinusoidal signal of a frequency different from the predetermined frequency of the first sinusoidal signal, and

second digital information modulated on the sinusoidal carrier signal by adding the even harmonic signal to the sinusoidal carrier signal and by changing the polarity of the harmonic signal in dependence on the second digital information (HMW modulated).

Drawings

Fig. 1 shows a track configuration of an optical disc incorporating the present invention.

Fig. 2 shows a meandering state of the groove.

Fig. 3 shows MSK and HMW modulated wobble signals.

Fig. 4A to 4E illustrate MSK modulation.

Fig. 5 shows an MSK demodulation circuit for demodulating the MSK modulated wobble signal.

Fig. 6 shows the input wobble signal (MSK stream) and the synchronous detection output signal (MSK × cos (ω t)) of the wobble signal.

Fig. 7 shows integrated output values of synchronous detection output signals of MSK streams, held values of the integrated output values, and data for modulation obtained by MSK demodulation.

Fig. 8A to 8C illustrate HMW modulation.

Fig. 9 shows an HMW demodulation circuit for demodulating the HMW modulated wobble signal.

Fig. 10 shows signal waveforms of a reference carrier signal (cos (ω t)), a data string "1010" as data for modulation, and a second harmonic (± sin (2 ω t), -12dB) generated with the data for modulation

Fig. 11 shows the generated wobble signal (HMW stream).

Fig. 12A and 12B illustrate the synchronous detected output signal, the integrated output value of the synchronous detected output signal, the sample-and-hold value of the integrated output value, and the HMW data for modulation of the HMW stream (HMW χ sin (2 ω t)).

Fig. 13 shows an error correction block of a DVR disk embodying the present invention.

Fig. 14 shows an ECC cluster of a DVR disk.

Fig. 15 shows a relationship between a recording and/or reproducing cluster (RUB) and an address unit of a DVR disc.

Fig. 16 shows a block of bits forming an address unit.

Fig. 17 shows a bit structure of the sync part in the address unit.

Fig. 18A and 18B show signal waveforms of monotone bits in the synchronization section and data for modulation.

Fig. 19A and 19B show signal waveforms of the first sync bit in the sync part and data for modulation.

Fig. 20A and 20B show signal waveforms of the second sync bit in the sync part and data for modulation.

Fig. 21A and 21B show signal waveforms of the third sync bit in the first sync portion and data for modulation.

Fig. 22A and 22B show a signal waveform of the fourth sync bit in the first sync portion and data for modulation.

Fig. 23 shows a bit structure of a data portion in an address unit.

Fig. 24A to 24C show signal waveforms of ADIP bits representing bit "1" and data for modulation in the data portion.

Fig. 25A to 25C show signal waveforms of ADIP bits representing a bit "0" and data for modulation in the data portion.

Fig. 26 shows the entire configuration of the format of the address unit.

Fig. 27 shows the contents of the address information indicated by the ADIP bit.

Fig. 28 shows an error correction block of address information.

Fig. 29 shows an address demodulating circuit of the DVR disk.

Fig. 30A to 30E show control timings of the address demodulation circuit.

Fig. 31A to 31C show signal waveform diagrams based on HMW demodulation of ADIP bits whose encoded contents are "1" by the address demodulation circuit.

Fig. 32A to 32C show signal waveform diagrams based on HMW demodulation of ADIP bits whose encoded contents are "1" by the address demodulation circuit.

Fig. 33 shows a block diagram structure of an optical disc drive embodying the present invention.

Fig. 34 shows the structure of a cutting apparatus of an optical main disc embodying the present invention.

Detailed Description

A wobble system for an optical disc, an optical disc drive for recording and/or reproducing data on and/or from the optical disc, and a method for producing the optical disc will now be explained in detail according to the present invention.

1. Wobble system for optical discs

1-1 general explanation of the wobble System

In the optical disc according to one embodiment of the present invention, as shown in fig. 1, a groove GV working as a recording track is formed. This groove GV is formed spirally from the inside to the outside of the disc. Thus, the optical disc has, seen in a radial cross section, convex lands L and concave grooves GV alternating with each other, as shown in fig. 2.

Meandering with respect to the tangential direction thereof forms the groove GV of the optical disc 1, as shown in fig. 2. The meandering shape of the groove GV is in conformity with the wobble signal. Therefore, with the optical disc drive, the two edge positions of the groove GV are detected from the reflected light of the laser spot LS impinging on the groove GV, and when the laser spot LS is moved along the recording track, the component of the variation of the edge position with respect to the disc radial direction is extracted to reproduce the wobble signal.

In the wobble signal, address information (physical address and other auxiliary information) for recording positions of the recording tracks is included and encoded. Therefore, with current optical disc drives, for example, address information is demodulated from the wobble signal to realize address control at the time of data recording and reproduction, for example.

In the embodiments of the present invention, an optical disc designed for groove recording is explained. However, the present invention can be applied not only to an optical disc for groove recording but also to an optical disc designed for land recording in which data is recorded on a land or to a land-groove recording in which data is recorded on a land and a groove.

With the optical disc 1 of the present embodiment, the wobble signal with the address information is modulated using two modulation systems. One such system is the MSK (minimum shift keying) modulation system, while the other is one in which even harmonics are added to a sinusoidal carrier signal and in which the polarity of the even harmonics is changed depending on the data to be modulated or the sign of the modulated data. I.e. another system in which even harmonics of a sinusoidal carrier signal are added to the sinusoidal carrier signal and in which the polarity of the even harmonics is changed in dependence on the sign of the modulated data. A modulation system in which even harmonics are added to a sinusoidal carrier signal and in which the polarity of the even harmonics is changed depending on the sign of the modulated data is called HMW (harmonic wave) modulation.

In the present embodiment of the optical disc 1, as shown in fig. 3, a block of a sinusoidal carrier signal waveform of a predetermined frequency including a predetermined number of consecutive cycles is formed, and a wobble signal having an MSK modulated part and an HMW modulated part is generated in the block. In the MSK modulation section and in the HMW modulation section, MSK modulation address information and HMW modulation address information are inserted, respectively. That is, the MSK modulated address information and the HMW modulated address information are inserted in different locations in the block. One of the two sinusoidal carrier signals used in the MSK modulation and the HMW modulated carrier signal correspond to the aforementioned reference carrier signal. The MSK modulation section and the HMW modulation section are arranged at different positions in the block, and the reference carrier signal of not less than one period of the reference carrier signal is arranged between the MSK modulation section and the HMW modulation section.

Meanwhile, a part of a block which is not data-modulated and in which only a frequency component representing a reference carrier signal is referred to as a monotone wobble. The sinusoidal signal used as the reference carrier signal is cos (ω t). One period of the reference carrier signal is made one wobble period. The frequency of the reference carrier signal is constant from the inner side to the outer side and is determined according to the linear velocity of the movement of the laser spot along the recording track.

The MSK modulation and HMW modulation methods are explained in further detail.

1-2MSK modulation

First, an address information modulation system using the MSK modulation system is explained.

The MSK modulation is continuous phase FSK (frequency shift keying) modulation with a modulation index of 0.5. In FSK modulation, codes "0" and "1" of modulated data are associated with two carrier signals, i.e., a carrier signal of frequency f1 and a carrier signal of frequency f2, respectively, for modulation. That is, the FSK modulation system is such a system in which a sinusoidal waveform of frequency f1 is output if the modulated data is "0" and a sinusoidal waveform of frequency f2 is output if the modulated data is "1". Further, in continuous phase FSK modulation, two carrier signals are phase-continuous or in-phase at the code switching timing of the modulated data.

In this FSK modulation, a modulation index m is defined. In particular, the modulation index m is defined as

m＝|f1-f2|T

Where T is the transmission rate of the modulated data (1/time of the shortest code length). Continuous FSK modulation for m-0.5 is called MSK modulation.

In the present optical disc 1, the shortest code length L of the modulated data subjected to MSK modulation is equal to two wobble periods, as shown in fig. 4A and 4B. Meanwhile, the shortest code length L of the modulation data may be any selected length provided that it is an integer multiple of the wobble period and at least twice the wobble period. On the other hand, one of the two frequencies used in MSK modulation is the same as the frequency of the reference carrier signal, and the other frequency is 1.5 times the frequency of the reference carrier signal. That is, one of the signal waveforms used for MSK modulation is cos (ω t) or-cos (ω t), and the other is cos (1.5 ω t) or-cos (1.5 ω t).

In inserting the modulated data of the MSK modulation system into the wobble signal of the optical disc 1, the data stream of the modulated data is subjected to differential encoding processing in accordance with a clock corresponding to the wobble period as a unit, as shown in fig. 4C. That is, the data stream of the modulated data and the delayed data delayed by one cycle of the reference carrier signal are subjected to differential encoding processing. The data resulting from the differential encoding process is pre-code (precoding) data.

This preamble data is MSK modulated to produce an MSK stream. As shown in fig. 4D, if the preamble data is "0", the signal waveform of this MSK stream is a waveform of the same frequency as the reference carrier or ccos (ω t) or its inverse waveform-cos (ω t), and if the preamble data is "1", the signal waveform of this MSK stream is a waveform of 1.5 times the frequency of the reference carrier or ccos (1.5 ω t) or its inverse waveform-cos (1.5 ω t). Therefore, if the data string of the modulated data is the pattern "010" as shown in fig. 4B, the signal waveforms of the MSK stream per wobble period are cos (ω t), cos (1.5 ω t), -cos (1.5 ω t), cos (ω t) as shown in fig. 4E.

In the present optical disc 1, the wobble signal is modulated with the address information by making the wobble signal the aforementioned MSK stream. Therefore, the conversion of data from fig. 4B to fig. 4D is referred to as modulation and the conversion of data in the reverse direction is referred to as demodulation.

If the modulated data is differentially encoded by performing the aforementioned MSK modulation method, synchronous detection of the modulated data becomes possible. Synchronous detection becomes possible for the following reasons:

with differentially encoded data (preamble data), a bit asserts itself (becomes "1") at the transcoding point of the modulated data. Since the code pattern length of the modulation data is selected to be at least twice as long as the wobble period, it is necessary to insert the reference carrier signal cos (ω t) or its inverse (-cos (ω t)) into the latter half of the code pattern length of the modulation data. If the bit of the previous code data is "1", at the code switching timing, a waveform having a frequency 1.5 times that of the reference carrier signal is inserted and the data before switching and the data after switching are in phase. Therefore, if the modulation data is "0", the signal waveform inserted into the latter half of the code pattern length of the modulation data must be the waveform of the reference carrier signal (cos (ω t)), but if the modulation data is "1", the signal waveform must be the inverted signal thereof (-cos (ω t)). The synchronous detection output is positive if the modulated data and carrier signals are in phase, and negative if the modulated data and carrier signals are out of phase. Therefore, if the above-mentioned MSK modulated signal is synchronously detected with the reference carrier signal, the modulated data can be demodulated.

Meanwhile, in MSK modulation, modulation occurs in the same phase at the position of code exchange. Therefore, a delay is generated before the synchronous detection signal is inverted in level. Thus, if an MSK modulated signal as described above is to be demodulated, the integration window of the sync detection output is delayed by one half wobble period to produce a correctly detected output.

Fig. 5 shows an MSK demodulation circuit for demodulating modulated data from the MSK stream described above.

The MSK demodulation circuit 10 includes a PLL circuit 11, a Timing Generator (TG)12, a multiplier 13, an integrator 14, a Sample and Hold (SH) circuit 15, and a limiter circuit 16, as shown in fig. 5.

The wobble signal (MSK modulated stream) is fed to the PLL circuit 11. The PLL circuit 11 detects an edge component from the input wobble signal to generate a wobble clock synchronized with the reference carrier signal (cos (ω t)). The wobble clock thus generated is sent to the timing generator 12.

The timing generator 12 generates a reference carrier signal cos (ω t) synchronized with the input wobble signal. The timing generator 12 also generates a Clear (CLR) signal and a HOLD (HOLD) signal from the wobble clock. The Clear (CLR) signal is generated at a timing delayed by one half wobble period from the leading edge of the data clock of the modulated data. The minimum code length of the above-mentioned modulated data is two wobble periods. The HOLD signal (HOLD) is a signal generated at a timing delayed from one half wobble period of the trailing edge of a data block of modulated data. The reference carrier signal cos (ω t) generated by the timing generator 12 is sent to the multiplier 13. The generated clear signal (CLR) is sent to the integrator 14 and the generated HOLD signal (HOLD) is sent to the sample and HOLD circuit 15.

The multiplier 13 multiplies the input wobble signal and the reference carrier signal (cos (ω t)) to perform synchronization detection. The output signal of the synchronous detection is sent to the integrator 14.

The integrator 14 integrates the synchronous detection signal through the multiplier 34. At the same time, the integrator 14 clears the integration value to zero at the generation timing of the clear signal (CLR) generated by the timing generator 12.

Sample and HOLD circuit 15 samples the integrated output value of integrator 14 at the timing of the generation of the HOLD signal (HOLD) generated by timing generator 12 to HOLD the sampled value until the generation of the next HOLD signal (HOLD).

The slicing circuit 16 binary-encodes the value held by the sample and hold circuit 15 with the origin (0) as a threshold value, and inverts the sign of the encoded value to output a resultant signal.

The output signal of the limiter circuit 16 becomes modulation data of the modulation data.

Fig. 6 and 7 show a wobble signal (MSK stream) generated by MSK modulation of a data string "0100" as modulated data and signal waveforms of the respective circuits of the MSK demodulation circuit 10 when this MSK demodulation circuit 10 is fed with the wobble signal. In fig. 6 and 7, the abscissa (n) represents the number of periods of the wobbling period. Fig. 6 shows the input wobble signal (MSK stream) and the synchronous detection output signal (MSK × cos (ω t)) of the wobble signal. Fig. 7 shows the integrated output value of the synchronous detection output signal, the sample-and-hold value of the integrated output value, and the modulated data demodulated and output from the slicing circuit 16. Meanwhile, the modulation data of the modulation data output from the slicing circuit 16 is delayed because of the processing delay caused in the integrator 14.

If the modulated data is differentially encoded and MSK modulated as described above, synchronous detection of the modulated data becomes possible as described above.

In the present optical disc 1, the MSK modulated address information as described above is formed in the wobble signal. By MSK modulating the address information and by forming the thus modulated address information into a wobble signal, the content of harmonics in the wobble signal is reduced, thus enabling accurate address detection. Furthermore, since the MSK modulated address information is inserted into the monotone wobble, crosstalk given to adjacent tracks can be reduced and thus the S/N ratio can be improved. Further, in the present optical disc 1, since MSK modulated data can be demodulated by sync detection, the wobble signal can be correctly and easily demodulated.

1-3HMW modulation

A modulation system for address information using the HMW modulation system is explained later.

The HMW modulation system is such a system in which a signal of even harmonics is added to a sinusoidal carrier signal and in which the polarity of the signal of even harmonics is changed depending on the sign of modulation data to modulate a digital code.

With the present optical disc 1, the HMW modulated carrier signal is a signal having the same frequency and phase as those of the reference carrier signal used as the carrier signal in the above-described MSK modulation. The even harmonic signals to be added are sin (2 ω t) and sin (-2 ω t) as the second harmonics of the reference carrier signal (cos (ω t)), the amplitudes of these second harmonics being-12 dB with respect to the amplitude of the reference carrier signal. The minimum code length of the modulated data is twice the wobble period (the period of the reference carrier signal).

If the symbol of the modulated data is "1", sin (2 ω t) is added to the carrier signal, but if the symbol of the modulated data is "0", sin (2 ω t) is added to the carrier signal for modulation.

Fig. 8 shows signal waveforms of the wobble signal modulated by the above-described system. Fig. 8A shows a signal waveform of the reference carrier signal (cos (ω t)), and fig. 8B shows a signal waveform obtained by adding sin (2 ω t) to the reference carrier signal (cos (ω t)), that is, a signal waveform when the modulation data is "1". Fig. 8C shows a signal waveform obtained by adding-sin (2 ω t) to the reference carrier signal (cos (ω t)), that is, a signal waveform when the modulation data is "0".

In the present optical disc 1, the harmonic signal added to the carrier signal is the second harmonic. However, any optional even harmonic may be added in place of the second harmonic. Furthermore, although only the second harmonic is added to the present optical disc 1, a plurality of harmonic signals, such as the second and fourth harmonics, may be added simultaneously.

If a positive or negative even harmonic is added to the reference carrier signal, as described above, the modulated data can be demodulated by synchronous detection with the harmonic signal and integration of the synchronous detection output by the code length time for modulating the data.

Fig. 9 shows an HMW modulation circuit that demodulates modulated data from the HMW modulated wobble signal as described above.

The HMW demodulation circuit 20 includes a PLL circuit 21, a Timing Generator (TG)22, a multiplier 23, an integrator 24, a sample and hold circuit (SH)25, and a limiter circuit 26, as shown in fig. 9.

The wobble signal (HMW modulated stream) is fed to the PLL circuit 21. The PLL circuit 21 detects an edge component from the input wobble signal to generate a wobble clock synchronized with the reference carrier signal (cos (ω t)). The wobble clock thus generated is sent to the timing generator 22.

The timing generator 22 generates a second harmonic signal (sin (2 ω t)) synchronized with the input wobble signal. The timing generator 22 also generates a clear signal (CLR) and a HOLD signal (HOLD). The clear signal (CLR) is a signal generated at the timing of the rising edge of the data clock having the modulation data of two wobble periods as its minimum code length. The HOLD signal (HOLD) is a signal generated at a falling edge of a data clock of the modulated data. The second harmonic generated by the timing generator 22 is sent to the multiplier 23. The resulting clear signal (CLR) is routed to the integrator 24 and the resulting HOLD signal (HOLD) is sent to the sample and HOLD circuit 25.

The multiplier 23 multiplies the input wobble signal and the second harmonic (sin (2 ω t)) to perform synchronization detection. The synchronously detected output signal is sent to the integrator 24.

The integrator 24 integrates the signal synchronously detected by the multiplier 23. At the same time, the integrator 24 clears the integration value to zero at the generation timing of the clear signal (CLR) generated by the timing generator 22.

The sample and HOLD circuit 25 samples the integrated output value of the integrator 24 at the generation timing of the HOLD signal (HOLD) generated by the timing generator 22 to HOLD the sampled value until the generation of the next HOLD signal (HOLD).

The clip circuit 26 binary-encodes the value held by the sample and hold circuit 25 with the origin (0) as a threshold value, and outputs a resultant encoded signal.

The output signal of the limiter circuit 26 becomes modulation data of the modulation data.

Fig. 10 to 12 show signal waveforms used in HMW modulation as the data string "1010" of modulated data, a wobble signal generated by HMW modulation, and output signal waveforms from the respective circuits when the wobble signal is fed to the HMW demodulation circuit 20. In fig. 10 to 12, the abscissa (n) represents the number of periods of the wobbling period. Fig. 10 shows a reference carrier signal (cos (ω t)), a data string "1010" as modulation data, and a second harmonic signal waveform (± sin (2 ω t), -12dB) generated with the modulation data. Fig. 11 shows the generated wobble signal (HMW stream). Fig. 12A shows the synchronous detection output signal (HMW × sin (2 ω t)) of the wobble signal, and fig. 12B shows the integrated output value of the synchronous detection output signal, the sample-hold value of the integrated output, and the modulation data output from the slice circuit 26. At the same time, the modulated data output from the slicing circuit 26 is delayed due to the first delay caused in the integrator 14.

If the modulated data is differentially encoded and MSK modulated as described above, synchronous detection of the modulated data becomes possible.

In the current optical disc 1, the above-mentioned HMW modulated address information is formed in the wobble signal. By HMW modulating the address information, and by forming the thus modulated address information into the wobble signal, it is possible to limit the frequency component and reduce the higher harmonic component. As a result, the S/N ratio of the demodulated output of the wobble signal can be improved and the address can be correctly detected. Further, the modulation circuit can be constituted by the carrier signal generation circuit, the circuit for generating the harmonic component thereof, and the circuit summing outputs of these circuits, and thus can be simple in structure. In addition, the high frequency component of the wobble signal can be reduced to facilitate cutting in the cast optical disc.

Since the HMW modulated address information is inserted into the monotone wobble, it is possible to reduce crosstalk applied to adjacent tracks to improve the S/N ratio. Furthermore, in the current optical disc, since the HMW modulated data can be demodulated by means of synchronous detection, the wobble signal can be demodulated accurately and extremely easily.

1-4 summary of the invention

In the current embodiment of the optical disc described above, the MSK modulation system and the HMW modulation system are used as the modulation system for modulating the wobble signal with the address information. In the present optical disc 1, one of the frequencies used in the MSK modulation system and the carrier frequency used in the HMW modulation is a sinusoidal signal of the same frequency (cos (ω t)). Further, only a monotone wobble including a carrier signal (cos (ω t)) and in which no modulation data is present is provided between the respective modulation signals in the wobble signal.

In the above-described optical disc 1, no interference is generated between the signal of the frequency used in the MSK modulation and the harmonic used in the HMW modulation, so that the respective modulation components are not affected by the similar (counter) modulation component in detection. Therefore, the respective address information recorded by the two modulation systems can be reliably detected. The result is an improved accuracy of controlling the track position, for example in recording and/or reproducing optical discs.

If the address information recorded by the MSK modulation is of the same data content as the address information recorded by the HMW modulation, the address information can be detected more reliably.

Furthermore, in the present optical disc 1, since one of the frequencies used in the MSK modulation system and the carrier frequency used in the HMW modulation is a sinusoidal signal (cos (ω t)) of the same frequency, and the MSK modulation and the HMW modulation are applied to different parts in the wobble signal, if the harmonic signal of the HMW modulation is applied to the wobble position of the MSK modulated wobble signal for the HMW modulation, this is sufficient in the modulation, thus ensuring that the MSK and HMW modulations are highly facilitated. Furthermore, since the MSK modulation and the HMW modulation are applied to different parts in the wobble signal and at least one period of the monotone wobble is provided between the two modulations, it is possible to achieve more accurate disc manufacturing and more reliable address demodulation.

2. Example of application of DVR

An example of applying the above-described address format to a high-density optical disc called DVR (data and video recording) is explained hereinafter.

Physical characteristics of 2-1DVR disks

First, typical physical parameters of a DVR disc to which this address format is applied are explained. Meanwhile, these physical parameters are merely illustrated, so that the wobble format explained now can also be applied to an optical disc having any other suitable physical characteristics.

The DVR disc of this embodiment is an optical disc that records data according to the phase change system. The disc size is 120mm in diameter and the thickness of the disc is 1.2 mm.

The area on the disc is composed of a lead-in area, a program area, and a lead-out area as viewed from the inner circumferential side. The information area composed of these areas is formed at a diameter position ranging from 44mm to 117 mm.

For recording and/or reproduction, a so-called 405nm blue laser is used. The NA of the lens is 0.85, the track pitch is 0.30 μm, the channel bit length is 0.086 μm and the data bit length is 0.13 μm. The average transfer rate of user data is 35 mbits/sec.

The user data capacity is 22.46 gigabytes.

Data is recorded by a groove recording system. I.e. the tracks are formed at the beginning of the disc by grooves, on which recording is to be performed. This groove is wobbled to record address information of the current disc.

2-2 format for recording and/or reproducing data

The error correction block (ECC block) of the phase change data of the present embodiment of the DVR disk is 64 kbytes (304 bytes × 248 bytes) as shown in fig. 13. This ECC block consists of data of 304 rows by 216 columns and parity of 304 rows by 32 columns, where one symbol is one byte. The parity is generated by a long-distance Reed-Solomon code of LDCs (248, 216, 33) of 304 rows by 216 columns of data with respect to the column direction.

Meanwhile, in the current embodiment of the DVR disc, the recording and/or reproducing unit of the phase change data may be 2 kbytes. In this example, recording and/or reproduction is performed with the above-described error correction blocks of 64 kbytes, and data rewriting is performed on the error correction blocks of desired 2 kbytes.

Turning to the recording and/or reproducing unit of the current embodiment of the DVR disc, an ECC block is an ECC block cluster of 156 symbols by 496 frames, as shown in fig. 14, and one frame connection field, e.g., a PLL, is appended to each of the front and rear sides of the ECC block cluster to form a total of 498 frames of recording and/or reproducing clusters. This recording and/or reproducing cluster is called a RUB (recording unit block).

Each frame of each ECC block cluster is composed of data symbols divided as a unit according to 38 bytes and a sync code or BIS (burst indicator subcode) inserted between the respective data symbols. Specifically, each frame is composed of a synchronization code, a data symbol (38 bytes), BIS, a data symbol (38 bytes) in this order as viewed from the front side. The BIS and the synchronization code may be used to discriminate burst errors in data reproduction. That is, if consecutive syncs and BIS represent a symbol error, the 38-byte data symbol sandwiched between the error-corrupted sync and BIS is also deemed corrupted by a burst error, and pointer erasure correction is performed accordingly.

2-3 address format

2-3-1 relationship between recorded and/or reproduced data and addresses

In the current address format, a single RUB (498 frame) is managed by three address units (ADIP _1, ADIP _2, and ADIP _3) recorded as wobbles, as shown in fig. 15. I.e. separate RUB are recorded for these three address units.

In the current address format, a single address unit is formed by an 8-bit sync part and a 75-bit data part, entirely 83 bits. In the current address format, the reference carrier signal of the wobble signal recorded on the pregroove is a cosine signal (cos (ω t)), and a wobble signal of one bit is formed by 56 periods of the reference carrier signal, as shown in fig. 16. The 'bit' here refers to one bit of information represented by the wobble signal. Therefore, the length of one period (one wobble period) of the reference carrier signal is 69 times the length of one channel of the phase variation. The 56 periods of the reference carrier signal forming one bit are referred to as the following bit block.

2-3-2 sync part

Fig. 17 shows a bit configuration of the synchronization section in the address unit. The sync part is a part for identifying the front end of the address unit and is composed of four, i.e., first to fourth sync blocks (sync block "1", sync block "2", sync block "3", and sync block "4"). Each sync block is formed by a monotone bit and a sync bit that are entirely two-bit blocks.

Turning to the signal waveform of a monotone bit, it is shown in fig. 18A that the first to third wobbles of a bit block composed of 56 wobbles represent a bit synchronization mark BM and the fourth to 56 th wobbles as from the synchronization mark BM are signal waveforms of a monotone wobble (reference carrier signal (cos (ω t)).

The bit synchronization mark BM is a signal waveform obtained by MSK-modulating modulation data of a predetermined code pattern designed to distinguish the front ends of bit blocks. That is, this bit synchronization flag BM is a signal waveform generated by differentially encoding modulated data of a predetermined code pattern and allocating a frequency depending on the symbol of the differentially encoded data. Meanwhile, the minimum code length L of the modulated data is two wobble periods. In the present embodiment, a signal waveform obtained by modulating modulation data with one bit (two wobble periods) MSK of "1" is recorded as the bit synchronization mark BM. That is, this bit synchronization mark BM is a continuous signal waveform having a unit of "cos (1.5 ω t)," cos (ω t), and "cos (1.5 ω t)" according to one wobble period.

Accordingly, a monotone bit can be generated by generating modulation data in which the code length is two wobble periods, for example, "10000.. 00" and modulating this modulation data by MSK, as shown in fig. 18B.

It should be noted that the bit synchronization flag BM is inserted not only at the front end of the monotone bit of the synchronization part but also at the front end of each of the now all bit blocks. This bit synchronization mark BM can therefore be detected and synchronized during recording and/or reproduction for the synchronization of the bit blocks in the wobble signal, which is a synchronization of 56 wobble periods. Also, as explained later, the bit synchronization flag BM may be used as a reference for specifying the insertion position in the bit block of various modulation signals.

In the signal waveform of the sync bit of the first sync block (sync "0" bit), the first to third wobbles of the 56 wobbles constituting the bit block represent the bit sync mark BM, and the 17 th to 19 th and 27 th to 29 th wobbles thereof represent the MSK modulation mark MM, and the waveforms of the remaining wobbles are all monotone wobbles, as shown in fig. 19A.

In the signal waveform of the sync bit of the second sync block (sync "1" bit), the first to third wobbles of the 56 wobbles constituting the bit block represent the bit sync mark BM, and the 19 th to 21 th and 29 th to 31 th wobbles thereof represent the MSK modulation mark MM, and the waveforms of the remaining wobbles are all monotone wobbles, as shown in fig. 20A.

In the signal waveform of the sync bit of the third sync block (sync "2" bit), the first to third wobbles of the 56 wobbles constituting the bit block represent the bit sync mark BM, and the 21 st to 23 th and 31 st to 33 th wobbles thereof represent the MSK modulation mark MM, and the waveforms of the remaining wobbles are all monotone wobbles, as shown in fig. 21A.

In the signal waveform of the sync bit of the fourth sync block (sync "3" bit), the first to third wobbles of 56 wobbles constituting the bit block represent the bit sync mark BM, and the 23 th to 25 th and 33 th to 35 th wobbles thereof represent the MSK modulation mark MM, and the waveforms of the remaining wobbles are all monotone wobbles, as shown in fig. 22A.

The MSK modulation flag MM is a signal waveform generated by MSK modulating modulated data of a predetermined code pattern, similarly to the bit synchronization flag BM. That is, the MSK modulation flag MM is a signal waveform generated by differential encoding of modulation data of a predetermined code pattern and by frequency allocation according to the symbol of the differentially encoded data. Meanwhile, the minimum code length L of the modulation data corresponds to two wobble periods. In the present example, a signal waveform having one bit corresponding to two wobble periods and set to "1" obtained by MSK modulation data is recorded as the MSK modulation flag MM. That is, this MSK modulation flag MM is a continuous waveform, composed of "cos (1.5 ω t)," cos (ω t) and — cos (1.5 ω t) "with one wobble period as a unit.

That is, the sync bit of the first sync block (sync "0" bit) can be generated by generating the data stream shown in fig. 19B, the code length of which is two wobble periods, and the data stream thus generated by MSK modulation. Similarly, the sync bit of the second sync block (sync "1" bit), the sync bit of the third sync block (sync "2" bit), and the sync bit of the fourth sync block (sync "3" bit) can be generated by generating the data stream shown in fig. 20B and by MSK-modulating it, by generating the data stream shown in fig. 21B and by MSK-modulating it, and by generating the data stream shown in fig. 22B and by MSK-modulating it, respectively.

Meanwhile, the sync bit insertion pattern for the bit blocks of the two MSK modulation flags MM is unique with respect to the insertion pattern of the MSK modulation flags MM in the remaining bit blocks. Accordingly, during recording and/or reproduction, the insertion pattern of the MSK modulated flag in the bit block is verified by MSK demodulating the wobble signal and the address unit can be synchronized by discriminating at least one of the four sync bits, thereby realizing demodulation and decoding of the data part as now explained.

2-3-3 data part

Fig. 23 shows a bit configuration of a data portion in an address unit. The data portion holds real data of address information and is composed of 15, i.e., ADIP blocks 1 to 15 (ADIP block "1" to ADIP block "15"). Each ADIP block consists of one monotone bit and four ADIP bits.

The signal waveform of the monotone bit is similar to that shown in fig. 18.

The ADIP bit represents one bit of real data. The signal waveform varies with the code content of the real data bits.

If the symbol content represented by the ADIP bit is "1", the 1 st to 3 rd wobbles, the 13 th to 15 th wobbles, and the 19 th to 55 th wobbles of the bit block constituting the 56 wobbles become bit synchronization flag BM, MSK modulation flag MM, and HMW "1" modulation sections composed of reference carrier signals (cos (ω t)) and sin (2 ω t) added thereto, respectively, and the waveforms of the remaining wobbles are all monotone wobbles. That is, by generating modulation data whose code length is two wobble periods, for example, "100000100.. 00", MSK modulating the modulation data thus generated, as shown in fig. 24B, and by adding sin (2 ω t) whose amplitude is equal to-12 dB to the wobbles of the 19 th to 55 th MSK modulated signal waveforms, as shown in fig. 24C, ADIP bits whose symbol contents are "1" can be generated.

If the symbol content represented by the ADIP bit is "0", the 1 st to 3 rd wobbles, the 15 th to 17 th wobbles, and the 19 th to 55 th wobbles of the bit block constituting the 56 wobbles become modulated parts of the bit synchronization flags BM, the MSK modulation flags MM, and the HMW "0" composed of the reference carrier signal (cos (ω t)) and sin (2 ω t) added thereto, respectively, and the waveforms of the remaining wobbles are all monotone wobbles. That is, by generating modulation data whose code length is two wobble periods, for example, "100000010.. 00", MSK modulating the modulation data thus generated, as shown in fig. 25B, and by adding-sin (2 ω t) whose amplitude is equal to-12 dB to the wobble of the 19 th to 55 th MSK modulated signal waveform, as shown in fig. 25C, ADIP bits whose symbol content is "0" can be generated.

The ADIP bit distinguishes its bit content depending on the insertion position of the MSK modulation flag MM. That is, if the MSK modulation flag MM is inserted in the 13 th to 15 th wobbles, it represents a bit "1", whereas if the MSK modulation flag MM is inserted in the 15 th to 17 th wobbles, it represents a bit "0". Also, the ADIP bits indicate the same bit contents modulated by HMW as the bit contents indicated by the insertion position of the MSK modulation flag MM. Thus, the ADIP bits represent the same bit content for two different modulation systems, thus ensuring reliable data decoding.

Fig. 26 shows the format of an address unit displayed by integrating the above-described sync and data portions.

In the current address format of the optical disc 1, the bit synchronization mark BM, the MSK modulation mark MM, and the HMW modulation part are dispersedly arranged in one address unit, as shown in fig. 26. At least one wobble period of the monotone wobble is arranged between the modulated signal portions. As a result, there is no risk of interference between the individual modulated signals, thereby ensuring reliable demodulation of the individual signals.

Contents of 2-3-4 address information

Fig. 27 shows the contents of the address information indicated by the ADIP bits in the data portion. In one address unit it contains 60(4X15) ADIP bits, so that 60 bits of information content are displayed for the data string. This 60-bit address information is composed of 3-bit layer information (layer) indicating the number of layers in the case of multiple layered recording, 19-bit RUB information (RUB) indicating an RUB address, 2-bit address number information (address number/RUB) indicating the number of address units in the RUB, 12-bit auxiliary information (auxiliary data) stating recording conditions such as a recording mode, and 24-bit parity information (parity), as shown in fig. 27.

The 24-bit parity is a so-called nibble-based Reed-Solomon code having four bits as one symbol (RS (15, 9, 7)). Specifically, error correction encoding is performed with a code length of 15 nibbles, data of 9 nibbles, and parity of 6 nibbles, as shown in fig. 28.

2-4 address demodulation circuit

An address demodulation circuit for demodulating address information from the above-described DVR disc of the address format is explained later.

Fig. 29 is a block diagram showing an address demodulating circuit.

The address demodulating circuit 30 includes a PLL circuit 31, a timing generator 32 of MSK, a multiplier 33 of MSK, an integrator 34 of MSK, a sample and hold circuit 35 of MSK, a slice circuit 36 of MSK, a synchronous decoder 37, an MSK address decoder 38, a timing generator 42 of HMW, a multiplier 43 of HMW, an integrator 44 of HMW, a sample and hold circuit 45 of HMW, a slice circuit 46 of HMW, and an HMW address decoder 47, as shown in fig. 29.

The wobble signal reproduced from the DVR disc is fed to the PLL circuit 31. The PLL circuit 31 detects an edge component from the input wobble signal to generate a wobble clock synchronized with the reference carrier signal (cos (ω t)). The wobble clock thus generated is fed to the timing generator 32 of the MSK and the timing generator 42 of the HMW.

The timing generator 32 of the MSK generates a reference carrier signal (cos (ω t)) synchronized with the input wobble signal. The timing generator 32 of MSK also generates a clear signal (CLR) and a HOLD signal (HOLD) from the wobble clock. The clear signal (CLR) is a signal generated at a timing delayed by one and a half wobble periods from the leading edge of the data clock having the modulation data with the minimum code length equal to two wobble periods. The HOLD signal (HOLD) is a signal generated at a timing delayed by one half wobble period from the trailing edge of the data clock of the modulated data. The reference carrier signal (cos (ω t)) generated by the timing generator 32 of the MSK is fed to the multiplier 33 of the MSK. The generated clear signal (CLR) is fed to the integrator 34 of the MSK. The generated HOLD signal (HOLD) is fed to the sample and HOLD circuit 35 of the MSK.

The multiplier 33 of the MSK multiplies the input wobble signal and the reference carrier signal (cos (ω t)) by a method of performing a sync detection process. The sync detection output signal is fed to the integrator 34 of the MSK.

The integrator 34 of the MSK integrates the signal synchronously detected by the multiplier 33 of the MSK. At the same time, the integrator 34 of the MSK clears the integration value to "0" at the generation timing of the clear signal (CLR) by the timing generator 42 of the HMW.

The sample and HOLD circuit 35 of MSK samples the integrated output value of the integrator 34 of MSK at the generation timing of the HOLD signal (HOLD) by the timing generator 32 of MSK to HOLD the sampled value until the occurrence of the next HOLD signal (HOLD).

The slice circuit 36 of MSK binary-encodes the value held by the sample and hold circuit 35 of MSK with the origin (0) as a threshold value, and inverts the sign of the binary-encoded value to output a resultant signal.

The output signal of the clipping circuit 36 of MSK becomes the MSK modulated data stream.

The sync decoder 37 detects sync bits in the sync part from the bit pattern of the modulated data output from the slicing circuit 36 of the MSK. The sync decoder 37 synchronizes the address unit from the detected sync bits. Based on the synchronization timing of the address units, the sync decoder 37 generates an MSK detection window indicating the wobble position of the MSK modulated data in the ADIP bits of the data part and an HMW detection window indicating the wobble position of the HMW modulated data in the ADIP bits of the data part. The timing of the sync position of the address unit detected from the sync bits, the timing of the MSK detection window, and the timing of the HMW detection window are shown in fig. 30A, 30B, and 30C, respectively.

The sync decoder 37 sends the MSK detection window and the HMW detection window to the MSK address decoder 38 and to the HMW timing generator 42, respectively.

The demodulated stream output from the slicing circuit 36 of the MSK is fed to an MSK address decoder 38, which MSK address decoder 38 detects the insertion position of the MSK modulation flag MM in the ADIP bits of the demodulated data stream based on the MSK detection window to check the content of the symbols represented by the ADIP bits. That is, if the insertion pattern of the MSK modulation flag of the ADIP bit is the pattern shown in fig. 24 or the pattern shown in fig. 25, the content of the symbol is verified as "1" or "0", respectively. A bit string obtained from the result of the check is output as MSK address information.

The HMW timing generator 42 generates a second harmonic (sin (2 ω t)) synchronized with the input wobble signal. HMW timing generator 42 generates a clear signal (CLR) and a HOLD signal (HOLD) from the HMW detection window. The clear signal (CLR) is a signal generated at the timing of the leading edge of the HMW detection window. The HOLD signal (HOLD) is a signal generated at the timing of the rear edge of the HMW detection window. The second harmonic (sin (2 ω t)) generated by the HMW timing generator 42 is sent to the HMW multiplier 43. The resulting clear signal (CLR) is sent to the HMW integrator 44. The resulting HOLD signal (HOLD) is sent to the HMW sample and HOLD circuit 45.

The HMW multiplier 43 multiplies the input wobble signal by the second harmonic (sin (2 ω t)) by performing a synchronous detection process. The synchronously detected output signal is sent to the integrator 44 of the HMW.

The HMW integrator 44 performs integration processing on the signal synchronously detected by the HMW multiplier 43. The HMW integrator 44 clears the integration value to "0" at the generation timing of the clear signal (CLR) by the HMW timing generator 42, and HOLDs the sampled value until the next occurrence of the HOLD signal (HOLD).

The HMW sample and HOLD circuit 45 samples the integrated output value of the HMW integrator 44 at the generation timing of the HOLD signal (HOLD) by the HMW timing generator 42, for example, HOLDs the sampled value until the occurrence of the next HOLD signal (HOLD). That is, the HMW modulated data has 37 wobbles in one bit block, so that if a clear (HOLD) signal is generated when n is 0, n is the number of wobbles, as shown in fig. 30D, the sample and HOLD circuit 45 of HMW samples the integrated value when n is 36, as shown in fig. 30E.

The HMW slicing circuit 46 binary-encodes the value held by the HMW sample-and-hold circuit 45 with the origin (0) as a threshold value to output the resultant binary-encoded value.

The output signal of the HMW slicing circuit 46 becomes the modulated data stream.

The HMW address decoder 47 verifies the content of the code represented by each ADIP bit from the modulated data stream. The bit string obtained from the verification result is output as HMW address information.

Fig. 31 shows a signal waveform when ADIP bits with code content "1" are HMW demodulated by the HMW address decoder 47. The abscissa (n) of fig. 31 shows the number of periods of the wobbling period. Fig. 31A shows a reference carrier signal (cos (ω t)), modulated data with code content "1" and a second harmonic signal waveform (sin (2 ω t), -12dB) generated with the modulated data. Fig. 31B shows the generated wobble signal. Fig. 31C shows an output signal (HMWXsin (2 ω t)) of synchronous detection of a wobble signal, an integrated output value of the synchronous detection output signal, a sample-and-hold value of the integrated output, and modulated data output by the limiter circuit of HMW 46.

Fig. 32 shows a signal waveform when ADIP bits with code content "1" are HMW demodulated by the HMW address decoder 47. The abscissa (n) of fig. 32 shows the number of periods of the wobbling period. Fig. 32A shows a reference carrier signal (cos (ω t)), modulated data with code content "1" and a second harmonic signal waveform (sin (2 ω t), -12dB) generated with the modulated data. Fig. 32B shows the generated wobble signal. Fig. 32C shows an output signal (HMWXsin (2 ω t)) of synchronous detection of a wobble signal, an integrated output value of the synchronous detection output signal, a sample-and-hold value of the integrated output, and modulated data output by the limiter circuit of HMW 46.

As described above, the address decoder 47 detects the synchronization information of the address unit recorded by the MSK modulation and implements the MSK demodulation and the HMW demodulation based on the detection timing.

3. Principle structure of optical disk drive

The principle structure of an optical disc drive configured to record and/or reproduce data on and/or from a phase-change optical disc to which the above-described address format is applied will now be explained.

Fig. 33 shows a block diagram of an optical disc drive.

The spindle motor 61 rotationally operates the optical disc 1 loaded on the turntable at a Constant Linear Velocity (CLV) at the time of recording and/or reproducing.

The optical head 62 includes a laser diode as a laser source, a photodetector that detects reflected light, an objective lens that focuses the laser light on the disc, and a biaxial unit that keeps the objective lens moving in the tracking and focusing directions.

The matrix circuit 63 generates a playback signal, a focus error signal, a tracking error signal, and a wobble signal (push-pull signal) from signals detected by the photodetectors of the optical head 62.

The laser driver 64 energizes a laser diode in the optical head 62 to emit light.

The servo circuit 65 implements focus servo control, tracking servo control, and slip servo control based on the focus error signal, tracking error signal, and slip error signal detected by the matrix circuit 63.

The spindle circuit 66 operates the spindle motor 61.

A read-write (RW) circuit 67 performs recording compensation on the recorded data during recording, and generates a clock from a reproduction signal during reproduction to binary-encode a reproduction signal based on the data clock to generate reproduction data.

The modulation/demodulation circuit 68 performs modulation/demodulation processing, for example, run-length limited modulation/demodulation, on the recording and/or reproduction data.

The ECC encoder/decoder 69 performs ECC encoding or ECC decoding on the recording and/or reproducing data.

The clock generator 60 generates a clock timing signal from the wobble signal to send the clock timing signal thus generated to the read-write circuit 67, the wobble demodulation circuit 51, and the address decoder 52.

The demodulation circuit 51 demodulates the data modulated into the wobble signal. The address decoder 52 decodes the address information of the optical disc 1 from the modulated data of the demodulation circuit 51. The demodulation circuit 51 and the address decoder 52 may be configured as shown in fig. 29, for example.

The system controller 53 constitutes various components of the present optical disc drive 50.

In the above-described optical disc drive 50, recording and/or reproducing data and control commands are exchanged by, for example, the AV system 55.

With the optical disc drive 50 described above, a recording command and, for example, recording data, such as a picture bit stream, for example, MPEG2 picture bit stream, are sent from the AV system 55. The ECC encoder/decoder 69ECC blocks the recording data transmitted from the AV system 55 and then performs data modulation for recording by the modulation/demodulation circuit 68. The system controller 53 acquires the current address information from the address decoder 52 and, based on this address information, transfers the recording position of the optical disc 1 to a desired address. The read/write circuit 52 performs recording compensation on the recording data and starts the laser driver 44 at the clock timing generated by the clock generator 60 to record the data on the optical disc 1.

A playback command is fed from the AV system 55 to the optical disc drive 50 during reproduction. The system controller 53 acquires the current address information from the address decoder 52 and, based on the address information thus acquired, shifts the playback position of the optical disc 1 to a desired address. The read/write circuit 67 binary-encodes a signal reproduced from an address and demodulates the signal reproduced from the address by the modulation/demodulation circuit 68. The ECC encoder/decoder 69 transmits an MPEG2 picture bitstream obtained by error correction of the modulated data to the AV system 55.

4. Method for manufacturing optical disk

A method of manufacturing an optical disc to which the above-described address format is applied will now be explained.

The manufacturing process of an optical disc is roughly divided into a so-called mastering process and a disc forming process (reproducing process). The mastering process is a process before a metal master disc (stamper) used in the disc forming process is completed, and the disc forming process is a process of mass-producing optical discs from the stamper by a method of duplicating the stamper.

In the mastering process, a photosensitive resin is coated on a polished glass substrate to form a photosensitive film, which is then cut by exposure to form a concave area or groove. During the cutting, pit cutting for forming pits or grooves is performed in an area corresponding to the embossed area at the radially innermost side of the disc and wobble cutting for forming wobble grooves is performed in an area corresponding to the area where the grooves are formed. At the completion of the cutting, after information thereof is transferred onto a metal surface by, for example, electric fusion to form a stamper required for reproducing the disc, predetermined processing such as development is performed.

Fig. 34 shows a cutting apparatus for performing wobble cutting on a master optical disc.

The cutting device 70 is composed of a light unit 82 for irradiating a light beam on a substrate 81 on which a cut photosensitive resin is applied, a rotation driving unit 83 for rotationally driving the substrate 81, and a signal processor 84 for converting input data into a recording signal and controlling the light unit 82 and the rotation driving unit 83.

The optical unit 82 includes a laser source 71, such as a He-Cd laser, and an optical modulator 72. The optical unit 82 reacts to the wobble signal stream generated by the signal processor 84, cutting the pregroove, which causes a meandering progression of the laser beam emitted by the laser source 71.

The rotation driving unit 83 rotates the substrate 81 so that the pre-grooves are spirally formed from the inside, thereby radially moving the substrate 81 in a controlled manner.

The signal processor 84 includes, for example, an address generator 73, an MSK modulator 74, an HMW modulator 75, an adder 76, and a reference clock generator 77.

The address generator 73 generates address information for the pregroove of the MSK modulated optical disc and address information for the pregroove of the HMW modulated optical disc to transmit the thus generated address information to the MSK modulator 74 and the HMW modulator 75.

Based on the reference clock generated by the reference clock generator 77, the MSK modulator 74 generates two frequencies, i.e., cos (ω t) and cos (1.5 ω t). The MSK modulator 74 also generates a data stream from the address information at predetermined timing positions formed by synchronously modulating data with a reference clock. The MSK modulator 74 MSK modulates the data stream with two frequencies of cos (ω t) and cos (1.5 ω t) to generate an MSK modulated signal. In the part of the data stream in which the address information is not MSK modulated, the MSK modulator 74 generates a signal having a waveform of cos (ω t) (monotone wobble).

Based on the reference clock generated by the reference clock generator 77, the HMW modulator 75 generates the second harmonic (± sin (2 ω t)) synchronized with cos (ω t) generated by the MSK modulator 74. The HMW modulator 75 outputs the second harmonic at the timing of the address information recorded by HMW modulation. This timing corresponds to a monotone wobble without MSK modulation. At this time, the HMW modulator 75 outputs + sin (2 ω t) and-sin (2 ω t) in an exchange manner depending on the digital symbol of the input address information.

The adder 76 adds the second harmonic signal output from the HMW modulator 75 to the MSK modulated signal output from the MSK modulator 74.

The output signal of the adder 76 is sent as a wobble signal stream to the optical unit 82.

Accordingly, the cutting apparatus 70 can record the wobble modulated with the address information on the optical disc using two modulation systems, i.e., the MSK modulation system and the HMW modulation system.

Also, in the present cutting apparatus 70, one of the frequencies used in the MSK modulation system and the carrier frequency used in the HMW modulation represent a sine wave signal of the same frequency (cos (ω t)) as that used in the HMW modulation. In the wobble signal, a monotone wobble having no modulation data between the wobble signals and containing only a carrier signal (cos (ω t)) is provided.

Further, in the present cutting apparatus 70, one of the frequencies used in the MSK modulation system and the carrier frequency used in the HMW modulation represent sinusoidal waveform signals of the same frequency (cos (ω t)). The MSK modulation and the HMW modulation are applied to different parts of the wobble signal, while the harmonic signal is added to the location intended for generating the HMW modulation of the modulated signal. Thus, the flow can be modulated very simply twice.

Industrial applicability

In the disc-shaped recording medium according to the present invention, first digital information modulated using a first sinusoidal signal of a predetermined frequency and using a second sinusoidal signal MSK of a frequency different from the predetermined frequency, and second digital information modulated on the sinusoidal carrier signal by adding an even-order harmonic signal to the sinusoidal carrier signal and by changing the polarity of the harmonic signal in accordance with the second digital information (HMW modulation) are formed into the wobble signal of the recording track.

With this disc-shaped recording medium according to the present invention, information, such as address information, can be efficiently formed in the wobbling component in order to improve the S/N ratio of the information in reproducing the information thus formed in the wobbling component.

According to the disc drive apparatus of the present invention, the wobble information demodulating means includes a first demodulating unit for recovering first digital information which is MSK modulated by using a first sinusoidal signal of a predetermined frequency and a sinusoidal signal of a frequency different from the predetermined frequency of the first sinusoidal signal, and a second demodulating unit for recovering second digital information which is modulated on the sinusoidal carrier signal by adding an even harmonic signal to the sinusoidal carrier signal and by changing the polarity of the harmonic signal in accordance with the second digital information (HMW modulated).

With the disc drive apparatus according to the present invention, it is possible to demodulate a wobble signal with a high S/N from a disc-shaped recording medium in which information such as address information has been efficiently formed into a wobble component thereof.

In the method and apparatus for generating a disc according to the present invention, lands and/or grooves of a disc-shaped recording medium can be produced with meandering by means of a first digital information in which a sinusoidal carrier signal is MSK modulated by using a first sinusoidal signal of a predetermined frequency and a sinusoidal signal of a frequency different from the predetermined frequency of the first sinusoidal signal, and a wobble signal in which a second digital information is modulated on the sinusoidal carrier signal by adding an even-order harmonic signal to the sinusoidal carrier signal and by changing the polarity of the harmonic signal in accordance with the second digital information (HMW modulated).

With the apparatus for producing a disc, according to the present invention, it is possible to produce such a disc-shaped recording medium in which, for example, address information can be efficiently formed into a wobbling component and in which information in the formed wobbling component can be reproduced with an improved S/N ratio.

Claims (30)

1. A method of forming a land and/or a groove on a disc-shaped recording medium in a wrap-around manner to operate as a recording track, the method comprising the steps of: generating a wobble signal including first digital information and second digital information modulated onto a sinusoidal carrier signal, wherein the first digital information is MSK modulated by using a first sinusoidal signal of a predetermined frequency and using a second sinusoidal signal having a frequency different from the predetermined frequency; the second digital information is modulated onto the sinusoidal carrier signal by adding even harmonic signals to the sinusoidal carrier signal and by changing the polarity of the harmonic signals in accordance with the HMW modulated second digital information; and

cutting the disc-shaped recording medium in response to the wobble signal to form the land and/or groove in a meandering manner in accordance with the wobble signal.

2. The method of claim 1, wherein the frequency of the first sinusoidal signal used in the MSK modulation is the same as the frequency of the carrier signal used in the HMW modulation.

3. Method according to claim 1, wherein address information of said recording track is contained in said first digital information and/or said second digital information.

4. A method according to claim 3, wherein address information is recorded in address units formed by a predetermined number of cycles of said carrier signal as a unit; and wherein

The MSK modulated first address information and the HMW modulated second address information are recorded at different locations in the address unit.

5. A method according to claim 3, wherein one or more periods of said carrier signal are recorded between MSK modulated first address information and HMW modulated second address information.

6. The method of claim 4, wherein the MSK modulated first address information and the HMW modulated second address information represent the same information.

7. A method according to claim 1, wherein the spirally formed groove serves as a recording track.

8. The method of claim 1, wherein the first digital information and the second digital information comprise information of the same content.

9. The method of claim 1, wherein:

modulating the first digital information so that data having a code length equal to an integral multiple of a period of the first sinusoidal signal for modulation and the first sinusoidal signal of the one period are differentially encoded, where the integral is equal to or greater than 2, to generate differentially encoded data having a code length derived from differential encoding equal to the one period of the first sinusoidal signal, and so that the first and second sinusoidal signals are selected depending on a sign of the differentially encoded data.

10. The method of claim 1, wherein the frequency of the second sinusoidal signal is 3/2 times the frequency of the first sinusoidal signal.

11. The method of claim 1, wherein:

in the first digital information, an MSK modulation flag obtained by MSK modulating modulated data of a predetermined code pattern is inserted into a bit block formed by a predetermined number of consecutive periods of the first sinusoidal signal, and a symbol of the first digital information is represented by an insertion position of the MSK modulation flag in the bit block.

12. The method of claim 11, wherein a bit synchronization flag obtained by MSK modulating the modulated data of the predetermined code pattern is inserted at the front end of the bit block.

13. A method according to claim 12, wherein the data content of the first digital information is represented by synthesizing codes represented by respective bit blocks in an information unit formed by a plurality of successive bit blocks.

14. The method of claim 13, wherein an insertion scheme of the MSK modulation flag obtained by MSK modulating modulated data of a predetermined code pattern in one or more pilot bit blocks of the information unit is an insertion scheme unique from other bit blocks.

15. The method of claim 1, wherein said second digital information is HMW modulated by adding a-12 dB harmonic signal to said sinusoidal carrier signal.

16. The method of claim 1, wherein said second digital information is HMW modulated by adding a second harmonic signal of a sinusoidal carrier signal to said sinusoidal carrier signal.

17. A method of forming a land and/or a groove, which operate as a recording track, on a disc-shaped recording medium in a circumferential manner, the method comprising the steps of: :

generating a wobble signal including an address unit formed as a predetermined data unit representing address information including an address or addresses of a recording track, the address unit being structured to include one or more bit blocks representing bits forming the address information, and the one or more bit blocks being formed in a waveform including a predetermined number of consecutive periods of a sinusoidal carrier signal by:

inserting a first bit string MSK modulated using the sinusoidal carrier signal and using a sinusoidal signal of a frequency otherwise different from that of the sinusoidal carrier signal, and inserting a second bit string HMW modulated on the sinusoidal carrier signal by adding an even harmonic signal to the sinusoidal carrier signal; and

changing the polarity of the harmonic signal according to the HMW modulated second bit string, an

Cutting the disc-shaped recording medium in response to the wobble signal to form the land and/or groove in a meandering manner in accordance with the wobble signal.

18. The method of claim 17, wherein

The first and second bit strings are inserted at different positions in the bit block.

19. The method of claim 18, wherein there is at least one period of said carrier signal between said first and second bit strings.

20. The method of claim 17, wherein the first and second bit strings represent the same bit string.

21. The method of claim 17, wherein

A bit synchronization flag obtained by MSK-modulating the modulated data for a predetermined pattern is inserted in the front end of the bit block.

22. The method of claim 17, wherein:

the address unit includes one or more sync blocks having a waveform formed by a sinusoidal carrier signal of a predetermined number of consecutive cycles and an MSK modulation flag inserted into the waveform, wherein the MSK modulation flag is obtained by MSK modulating modulated data of a predetermined code pattern, while an insertion pattern of the MSK modulation flag is a unique insertion pattern.

23. The method of claim 22, wherein: the synchronization block is inserted in front of the address unit.

24. The method of claim 17, wherein: the frequency of the sinusoidal signal used in MSK modulation is 3/2 times the frequency of the carrier signal.

25. The method of claim 17, wherein: the harmonic signal used in HMW modulation is the second harmonic signal with an amplitude of-12 dB relative to the carrier signal.

26. The method of claim 17, wherein: the first bit string is represented by an insertion position of an MSK modulation flag in the bit block, the MSK modulation flag being obtained by MSK modulating modulation data of a predetermined bit pattern.

27. The method of claim 17, wherein: the first bit is modulated with a period of the carrier signal by differentially encoded data having a code length twice a period of the carrier signal for modulation to generate differentially encoded data having a code length resulting from differential encoding equal to one period of the carrier signal;

while the frequency is selected in dependence on the sign of the differentially encoded data.

28. A disc drive apparatus for recording and/or reproducing a disc-shaped recording medium having lands and/or grooves formed thereon in a circling manner to operate as recording tracks, the lands and/or grooves meandering according to a wobble signal, the disc drive apparatus comprising:

wobble information demodulating means for reproducing the wobble signal from the disc-shaped recording medium and for demodulating the wobble signal to recover first digital information and second digital information contained in the wobble signal, the wobble information demodulating means including a first demodulating unit for recovering first digital information which is MSK modulated by using a first sinusoidal signal of a predetermined frequency and a sinusoidal signal of a frequency different from the predetermined frequency of the first sinusoidal signal, and a second demodulating unit for recovering second digital information which is modulated onto a sinusoidal carrier signal by adding an even-order harmonic signal to the sinusoidal carrier signal and by changing the polarity of the harmonic signal in accordance with the HMW modulated second digital information;

an address decoder for decoding address information of the recording track contained in the first digital information and/or the second digital information; and

control means for controlling a recording or reproducing position for the disc-shaped recording medium based on the address information,

wherein the first demodulation unit includes:

a first PLL circuit for generating a wobble clock synchronized with the wobble signal;

a first timing generator for generating a reference carrier signal synchronized with the wobble signal and generating a clear signal and a hold signal based on a wobble clock generated by a first PLL circuit;

a first multiplier for multiplying the wobble signal by the reference carrier signal to perform synchronization detection, thereby outputting a synchronization detection signal;

a first integrator for integrating the synchronous detection signal and clearing the integrated value to zero at a generation timing of the clear signal generated by the first timing generator;

a first sample-and-hold circuit for sampling an integrated value of the first integrator at a generation timing of the hold signal generated by a first timing generator and holding the sampled value until generation of a next hold signal;

a first clipping circuit for binary-coding the value held by the first sample-and-hold circuit and inverting the sign of the coded value to output a resultant signal,

and the second demodulation unit includes:

a second PLL circuit for generating a wobble clock synchronized with the wobble signal;

a second timing generator for generating a second harmonic signal synchronized with the wobble signal and generating a clear signal and a hold signal based on a wobble clock generated by a second PLL circuit;

a second multiplier for multiplying the wobble signal by the second harmonic signal to perform synchronous detection, thereby outputting a synchronous detection signal;

a second integrator for integrating the synchronous detection signal and clearing the integrated value to zero at a generation timing of the clear signal generated by the second timing generator;

a second sample-and-hold circuit for sampling an integrated value of the second integrator at a generation timing of the hold signal generated by a second timing generator and holding the sampled value until generation of a next hold signal;

a second clipping circuit for binary-coding the value held by the second sample-and-hold circuit and outputting a resultant signal.

29. An apparatus for manufacturing a disc-shaped recording medium by forming lands/grooves in a circumferential manner on a surface of a master of the disc-shaped recording medium, the apparatus comprising:

a wobble signal generator for generating a wobble signal including first digital information and second digital information, the first digital information being MSK-modulated by a first sinusoidal signal using a predetermined frequency and a second sinusoidal signal using a frequency different from the predetermined frequency of the first sinusoidal signal; said second digital information being modulated onto said sinusoidal carrier signal by adding even harmonic signals to said sinusoidal carrier signal and by changing the polarity of said harmonic signals in accordance with said HMW modulated second digital information;

a rotation driving unit for driving a master disc of the disc-shaped recording medium to rotate; and

an optical unit for cutting a master of a rotating disc-shaped recording medium in response to the wobble signal to form the land and/or groove in a meandering manner in accordance with the wobble signal.

30. A method for manufacturing a disc-shaped recording medium by forming lands/grooves in a circumferential manner on a surface of a master of the disc-shaped recording medium, the method comprising the steps of:

generating a wobble signal including first digital information and second digital information, the first digital information being MSK modulated by a first sinusoidal signal using a predetermined frequency and a second sinusoidal signal using a frequency different from the predetermined frequency of the first sinusoidal signal; said second digital information being modulated onto said sinusoidal carrier signal by adding even harmonic signals to said sinusoidal carrier signal and by changing the polarity of said harmonic signals in accordance with said HMW modulated second digital information;

driving a master disc of a disc-shaped recording medium to rotate; and

cutting a master of a rotating disc-shaped recording medium in response to the wobble signal to form the lands and/or grooves in a meandering manner in accordance with the wobble signal.