초록 ▼

There is provided an optical disc having preformed thereon a spiral wobbled track as a grove and/or land along with data is to be recorded. The track is wobbled for a series of predetermined signal units each composed of an FSK information bit part based on a waveform resulted from FSK modulation o

There is provided an optical disc having preformed thereon a spiral wobbled track as a grove and/or land along with data is to be recorded. The track is wobbled for a series of predetermined signal units each composed of an FSK information bit part based on a waveform resulted from FSK modulation of information bit and a singe-frequency part based on a waveform of a single frequency. The FSK modulation uses two different frequencies of which the one is the same as the single frequency and the other is different from the single frequency. These different frequencies are in such a relation that each of them has an even number of wobbles and an odd number of wobbles alternately in a predetermined cycle.

대표청구항 ▼

The invention claimed is: 1. A disc-shaped recording medium comprising: preformed thereon a spiral, wobbled track as a groove or land along which data is recorded, wherein the wobble of the track is a series of predetermined signal units each consisting of an FSK information bit part corresponding

The invention claimed is: 1. A disc-shaped recording medium comprising: preformed thereon a spiral, wobbled track as a groove or land along which data is recorded, wherein the wobble of the track is a series of predetermined signal units each consisting of an FSK information bit part corresponding to a waveform resulted from FSK (frequency shift keying) modulation of information bit and a single-frequency part corresponding to the waveform of a single frequency, wherein the FSK modulation is an MSK (minimum shift keying) modulation. 2. The disc-shaped recording medium as set forth in claim 1, wherein two different frequencies are used in the FSK modulation; one of the frequencies being the same as the single frequency while the other is different from the single frequency; and these frequencies being in such a relation that each of the frequencies has an even number of wobbles and an odd number of wobbles alternately in a predetermined cycle. 3. The disc-shaped recording medium as set forth in claim 2, wherein the other frequency has a frequency 1.5 times or 1/1.5 times higher than that of the one frequency. 4. The disc-shaped recording medium as set forth in claim 1, wherein in the FSK information bit part, a 2-wobble period of a frequency as the single frequency corresponds to one channel bit as information bit. 5. The disc-shaped recording medium as set forth in claim 1, wherein the period length of the FSK information bit part is an integral multiple of the period of the single frequency. 6. The disc-shaped recording medium as set forth in claim 1, wherein in the predetermined unit, the period length of the single-frequency part is more than 10 times of that of the FSK information bit part. 7. The disc-shaped recording medium as set forth in claim 1, wherein an integral multiple in the predetermined unit corresponds to a time length of a recording unit of data to be recorded to the track. 8. The disc-shaped recording medium as set forth in claim 1, wherein the channel clock frequency of data to be recorded to the track is an integral multiple of the single frequency. 9. The disc-shaped recording medium as set forth in claim 1, wherein a frequency as the single frequency is a one between a tracking servo frequency band and a read signal frequency band. 10. The disc-shaped recording medium as set forth in claim 1, wherein the FSK information bit part is formed on the basis of a waveform resulted from FSK modulation of information bit as address information. 11. The disc-shaped recording medium as set forth in claim 1, wherein the FSK modulation for the FSK information bit part uses two different frequencies of which the one is continuous in phase with the other at the point of shift from one to the other. 12. The disc-shaped recording medium as set forth in claim 1, wherein in the FSK information bit part resulted from MSK modulation of the information bit, a predetermined wobble period of the frequency as the single frequency corresponds to one channel bit as information bit. 13. The disc-shaped recording medium as set forth in claim 12, wherein: the FSK information bit part resulted from MSK modulation of the information bit includes two different frequencies of which the one is the same as the single frequency and the other is a frequency x times higher than the single frequency; and the predetermined wobble period includes a period of four wobbles of the one frequency and a period of x wobbles of the other frequency and three wobbles of the one frequency. 14. The disc-shaped recording medium as set forth in claim 13, wherein x=1.5. 15. A cutting apparatus comprising: means for generating a series of predetermined signal units each composed of a signal part resulted from FSK modulation of information bit and a signal part of a single frequency, wherein the FSK modulation is an MSK (minimum shift keying) modulation; means for generating a drive signal on the basis of the signal supplied from the signal generating means; a laser source means; means for deflecting laser light from the laser source means on the basis of the drive signal from the drive signal generating means; and means for cutting a disc substrate by radiating the laser light to the disc substrate through the laser light deflecting means to form, on the disc substrate, a wobbled track including a series of predetermined units each composed of an FSK information bit part based on a waveform resulted from FSK modulation of the information bit and a single-frequency part based on the waveform of the single frequency. 16. A disc drive for recording or reproducing data to or from a disc-shaped recording medium having preformed thereon a spiral, wobbled track as a groove or land along which data is to be recorded and in which the wobble of the track is a series of predetermined signal units each consisting of an FSK information bit part corresponding to a waveform resulted from FSK modulation of information bit and a single-frequency part corresponding to the waveform of a single frequency, wherein the FSK modulation is an MSK (minimum shift keying) modulation, the apparatus comprising: a head means for radiating laser light to a track to generate a return light signal; means for extracting a wobbling signal about wobbling of the track from the return light signal; and a wobbling information decoding means for making FSK demodulation of the wobbling signal to decode information represented by the information bit. 17. The disc drive as set forth in claim 16, wherein the wobbling information decoding means includes a clock reproduction unit to generate, by a PLL, a wobble reproduction clock on the basis of a signal corresponding to a single-frequency part of the wobbling signal, an FSK demodulator to make FSK demodulation of the wobbling signal corresponding to the FSK information bit part of the wobbling signal to provide demodulation data, and a decoder to decode required information composed of the information bit from the demodulation data supplied from the FSK demodulator. 18. The disc drive as set forth in claim 17, wherein the FSK demodulator includes a correlation detection circuit to make FSK demodulation by detecting a correlation as to the wobbling signal. 19. The disc drive as set forth in claim 18, wherein the correlation detection circuit detects a correlation between the wobbling signal and a delay signal resulted from delaying of the wobbling signal by a period of the wobble reproduction clock. 20. The disc drive as set forth in claim 17, wherein the FSK demodulator includes a frequency detection circuit to make FSK demodulation by detecting a frequency of the wobbling signal. 21. The disc drive as set forth in claim 20, wherein the frequency detection circuit detects a number of rising edges or falling edges of the wobbling signal, existent within one period of the wobble reproduction clock. 22. The disc drive as set forth in claim 17, wherein: the FSK demodulator includes a correlation detection circuit to make FSK demodulation by detecting a correlation as to the wobbling signal and a frequency detection circuit to make FSK demodulation by detecting a frequency of the wobbling signal; and the decoder decodes the required information using both the demodulation data demodulated by the correlation detection circuit and that demodulated by the frequency detection circuit. 23. The disc drive as set forth in claim 22, wherein the decoder decodes the required information from a logical product of the demodulated data from the correlation detection circuit and that from the frequency detection circuit when the PLL is being pulled in the clock reproduction unit, and it decodes the required information from a logical sum of the demodulated data from the correlation detection circuit and that from the frequency detection circuit when the PLL is stable in the clock reproduction unit. 24. The disc drive as set forth in claim 17, wherein: the decoder includes a gate generator to generate a gate signal for the PLL in the clock reproduction unit based on the fact that it decodes sync information as one of the required information; and the PLL functions on the basis of the gate signal to provide a PLL operation based solely on a part, corresponding to the single frequency, of the wobbling signal. 25. The disc drive as set forth in claim 17, further comprising a spindle servo means for making spindle servo control using the wobble reproduction clock. 26. The disc drive as set forth in claim 17, further comprising means for generating an encode clock synchronous with the wobble reproduction clock and which is to be used for encoding data to be recorded. 27. The disc drive as set forth in claim 17, wherein the wobbling information decoding means includes an MSK demodulator for making MSK modulation of an MSK modulation signal corresponding to the FSK information bit part of the wobbling signal to generate demodulation data. 28. The disc drive as set forth in claim 27, wherein the MSK demodulator demodulates the MSK modulation signal in units of a predetermined wobble period of the frequency as the single frequency to provide the modulation signal.