JPS5929994B2 - Information signal recording and reproducing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information signal recording and reproducing method, and even in a recording and reproducing system of a rotating recording medium that does not have a guide groove and has relatively large distortion, cross-modulation distortion and bead interference in demodulated video signals can be avoided. It is an object of the present invention to provide a method capable of recording and reproducing a plurality of information signals without causing a problem.

The present applicant previously proposed an "information signal recording and reproducing system" in Japanese Patent Application No. 51-38809. In this method, a plurality of reference signals that are different from each other are sequentially and cyclically recorded for each rotation period of the rotating recording medium approximately in the middle between each of the main information signal recording tracks in a spiral or concentric shape. Among the reproduced signals reproduced by the scanner using a well-known method, at least one of the plurality of reference signals reproduced from both sides of the main information signal recording track is discriminately reproduced, and tracking control is performed based on this. It obtains a signal and performs a tracking operation. According to this method, since the scanning needle guide groove can be eliminated, the sliding area of the scanning needle with respect to the recording medium can be increased, especially when applied to the recording and reproducing system of a capacitance detection type rotating recording medium. , it has various other features such as an extremely long life of the scanning needle and the ability to perform special playback such as slow motion playback and still image playback. However, the above reference signal is recorded and reproduced for tracking purposes, and needs to be separated from the recording band of the main information signal. By the way, in a recording/reproducing method in which information signals are recorded as changes in geometric shapes using countless pits on a rotating recording medium and then reproduced, unlike the case of a magnetic recording/reproducing device, a plurality of information signals are recorded on the same track, e.g. It is necessary to record video signals and audio signals in order to extend the performance time, and for this reason, in order to improve the S/N of the reproduced audio, it is conventionally necessary to record the audio signal by frequency modulating the carrier wave with the audio signal. 1 frequency modulated wave signal) and a video carrier (second frequency modulated wave signal) obtained by frequency modulating another high frequency carrier wave with a video signal, and pass the mixed signal through a limiter. The repetition frequency of the rectangular wave thus obtained represents video information, and the change in its duty cycle represents audio information.Therefore, the above rectangular wave is obtained by pulse width modulating the video carrier with the audio carrier. This is a modulated wave signal, and a so-called duty cycle modulation method has been used to obtain such a rectangular wave.

In this case, if the distortion in the transmission system is large, cross-modulation distortion occurs between the video carrier and the audio carrier, resulting in a phenomenon in which bead interference occurs in the demodulated video signal. In order to reduce this bead interference, it is possible to reduce the ratio of the audio carrier to the video carrier.
It cannot be made very small due to the relationship with N, and it cannot be said to be the best method in a system where the distortion in the transmission system is large. The present invention is suitable for transmission systems in which the distortion of the transmission system is considered to be relatively large, such as recording with laser light and detecting capacitance changes between pits on the recording medium and the scanning needle during reproduction. This is a signal recording and reproducing method, and relates to an improvement of the method previously proposed by the applicant of the present invention, and one embodiment thereof will be described below with reference to the drawings.

FIG. 1 shows a block system diagram of an embodiment of a recording system according to the method of the present invention, and FIG. 2 shows a block system diagram of an embodiment of the main part of FIG.

In FIG. 1, 1 and 2 are audio sources, respectively, and the audio signals outputted from these sources are supplied to frequency modulators 3 and 4, and 3.
43MHz vs. 75kHz, 3.73MHz±75kHz
The signals are modulated into audio carriers FAl and fA2. Therefore, the audio carriers FA,, fA2 correspond to the carrier color signal band (3.58 MHz) of the NTSC color television signal.
±500kHz), but it is of course possible to select other frequencies. These frequencies are selected to be higher than the upper limit frequency of this luminance signal so that the band does not overlap with the separated luminance signal, but there are considerations such as conflicts with other signals to be recorded and reproduced, ease of recording and reproduction, etc. Taking these points into consideration, a frequency that is not very high, for example, a frequency of about 3 MHz to 4 MHz is selected. On the other hand, 5 is a color video signal source, and the color video signal extracted from this is separated into a carrier color signal C and a brightness signal Y by a color signal and brightness signal separation circuit 6, and the brightness signal is limited to a band of 3 MHz. Ru.

This separation circuit 6 is known and consists of a low-pass filter, a combination of high-pass filters, or a comb filter. When a comb-shaped filter is used, it is also possible to extend the video band to 3 MHz or more, although this is related to the above-mentioned audio carrier. The separated luminance signal Y becomes input to the pre-emphasis circuit 7 and the sync separation circuit 8, respectively. Further, the separated carrier color signal C is sent to a color subcarrier generator 9.
and the color signal conversion circuit 10, respectively. This color subcarrier generator 9 extracts the color burst signal from the carrier color signal using the burst gate pulse generated by the synchronization separation circuit 8, and generates a color burst signal at a frequency equal to the color subcarrier frequency (3.579545 MHz in the case of an NTSC color video signal). F
Generates a single continuous wave of sc. The signal is then supplied to an index signal generator 12 and a pilot signal generator 13, which will be described later. Further, the color signal conversion circuit 10 converts the separated carrier color signal into a frequency that is a difference from the signal of 1×Fsc generated from the single continuous wave from the color subcarrier generator 9. Therefore, the color subcarrier frequency is set to 1× by the color signal conversion circuit 10.
The Fsc low-pass converted carrier color signal is extracted. Here, when recording an NTSC color video signal,
The frequency −×Fsc is 1.5340907 MHz, which has a relationship of FH with respect to the horizontal scanning frequency fH=156734263 KHz, and the relationship of frequency isotarleaving is maintained. said audio carrier FAl,
fA2, the luminance signal from the pre-emphasis circuit 7, and the index signal from the index signal generator 12 are each supplied to a mixer 14, where they are combined and then processed by a frequency modulator 15 to generate, for example, a sync chip of 5.5 MHz, 1 pedestal, 6.1 MHz, and 1 white peak. The frequency is modulated to 7.5MHz.

The modulated signal is added to the low-pass converted carrier color signal in an appropriate level relationship in a mixer 16, and then the amplitude is limited in an amplitude limiter 17 to perform so-called duty cycle modulation ( The main information signal (pulse width modulated) is taken out from the output terminal 18. On the other hand, a part of the output signal of the index signal generator 12 is supplied to a pilot signal generator 13 as described later, where it is converted into a pilot signal and then taken out from an output terminal 19. The above-mentioned main information signal is input to, for example, a laser light modulator (not shown) and converted into a modulated light beam, which is then applied to a rotating recording medium coated with photoresist in a geometric manner according to the repetition frequency of the information signal. The change in shape is recorded by forming a spiral or concentric main track.

The pilot signal (reference signal) is also input to another laser light modulator (not shown) and converted into a modulated light beam.
The incident optical path to the objective lens is adjusted and recorded in the intermediate portion between adjacent tracks of the main track in the same manner as above. Here, the recording track pitch is approximately 1.6 to 6 μm.
If the track width of the main track is made slightly narrower than this, the distance between the tracks of this main track is approximately 0.6~
A pilot signal will be recorded at 2 μm. Note that the recording track pitch and the track width of the main track may be equal. The recorded recording medium undergoes a well-known process and is press-molded in the same way as an audio record disc. For example, after a conductive material is deposited thinly, a dielectric material such as styrene is attached, and the recording medium is used for reproduction. next,
Index signal generator 12, indicated by dashed line 11 in FIG.
The circuit section consisting of the pilot signal generator 13 and the pilot signal generator 13 will be explained in more detail with reference to FIG.

Hereinafter, for convenience of explanation, an example will be described in which the rotating recording medium is a disk and four fields of NTSC system output are recorded per one rotation of the disk, followed by one video signal. In FIG. 2, 21 is a synchronization signal input terminal separated by the synchronization separation circuit 8, and 22 is an input terminal for a continuous wave of a single frequency Fsc generated by the color subcarrier generator 9.

A synchronizing signal input from the input terminal 21 is supplied to a horizontal synchronizing signal separation circuit 23 and a vertical synchronizing signal separation circuit 26, respectively. The horizontal synchronizing signal separated by the circuit 23 is applied as a trigger pulse to a monostable multivibrator (hereinafter referred to as MM) 24. The output pulse of MM24 is MM25
is applied as a trigger pulse. As a result, MM2
The pulses, which are adjusted to appropriate positions by 4 and to appropriate widths by MM25, are extracted from MM25 and supplied to JK flip-flops 38 and 45, which will be described later. On the other hand, the vertical synchronizing signal separated by the circuit 26 is counted down to 1 by the counter 27, then triggers the MM28, and further
The output of M28 triggers MM29.

As a result, in the same way as above, the appropriate position is set with MM28 and the appropriate width is set with MM29. The Q and Q output pulses of the MM 29 having a frequency divided by the vertical synchronization frequency are supplied to the J and K inputs of a JK flip-flop (hereinafter referred to as J-KFF) 30. This position is located within the vertical retrace period of the equalization pulse immediately after the vertical synchronization signal so that the index signal can be easily extracted during playback, and the pulse width is 1H (
H is selected to be approximately a horizontal scanning period) to several H. J
-KFF3O is applied with the synchronizing signal from the input terminal 21 as a clock pulse, so it outputs a signal obtained by resynchronizing the output of MM29 with the synchronizing signal, and supplies this to gate circuits 31, 40, and 41, respectively.

The gate circuit 31 removes the synchronizing signal portion from the output of the J-KFF3O using the synchronizing signal from the terminal 21, and then applies it to the pulsed oscillator 32 as a control signal. The pulsed oscillator 32 is a well-known circuit that oscillates only when the control signal is logic [0] or [1]. In this case, it is configured to oscillate when the logic is "O", and the oscillation frequency is about 1 MHz. It's summery. This oscillation frequency is arbitrary, but from the relationship with S/N and band, it is several hundred KHz to 2
Approximately MHz is appropriate. Further, the output pulse of the gate circuit 31 is supplied to the mixer 34 via the inverting amplifier 33,
After being mixed with the output signal of the pulsed oscillator 32 at an appropriate level ratio, the output signal is output from the output terminal 35 as an index signal (reference signal) to the mixer 1 shown in FIG.
4. As is clear from the above explanation, this index signal is output every four field periods within the vertical blanking period of 1H to several H immediately after the vertical synchronization signal, and is converted into a luminance signal by the mixer 14 shown in FIG. On the other hand, Fig. 4A
are mixed as shown by diagonal lines. Next, the continuous wave of the single frequency Fsc inputted to the terminal 22 is switched by the waveform shaping circuit 36 and made into a rectangular wave.

This rectangular wave is applied to counters 31, 44, and 48, respectively, and counted down to 1/7, 1/5, and 1/13, respectively. The repetition frequency taken out from the counter 37 is 51
1.36357kHz (=-×3.579545MHz
) is the signal of J-K. It is applied as a clock pulse to the FF 38, and the output of the MM 25, which has been resynchronized with the output of the counter 37, is outputted to the gate circuit 42 and is also supplied to the gate circuit 42. J-KFF3
Since the output of the counter 37 is interleaved in frequency with the horizontal synchronization signal (luminance signal), the phase has changed with respect to the output of the MM 25, and is provided for re-synchronizing. On the other hand, the output pulse of the J-KFF3O is counted down to one by a flip-flop (hereinafter referred to as FF) 39, and is made into a rectangular wave that repeats "O" and "1" every four fields. The Q output of this FF39 is J-KFF
It is gated together with the output of 3O by a gate circuit 40, and the output becomes the input of the gate circuit 42. The other inputs of the gate circuit 42 are the output of the J-KFF38 and the output of the counter 37, so the output of the gate circuit 42 is 4 field cycles, during the horizontal retrace period, and excluding the output width of the J-KFF3O. The signal is such that the output pulse of the counter 37 exists during the period. The output of the gate circuit 42 is applied to the MM43 as a trigger pulse, and the duty cycle is 50.
%, the pilot signal FPl is obtained.

In addition, 715.909kHz (=τ×3.579545MHz) taken out from the counter 44
) is a pulse with a duty cycle of 50% during the period excluding the output width of J-KFF3O during the horizontal retrace period with 4 field cycles by J-KFF45, gate circuits 41, 46, and MM4r, as described above. and is supplied to the mixer 52 as a pilot signal FP2.

FPl and fP2 are output alternately every four field periods, and the gate circuits 40 and 41 do not output the index signal during a certain period, but another pilot signal FP3 is input during this period, and the timing at which FPl and fP2 are switched is changed. It can be used for detection.

In other words, 275.34 taken out from the counter 48
The signal of 961 kHz (=-x3.579545 MHz) is generated by the J-K
J-KFF4 with outputs Q and Q of FF3O as J and K inputs
9 as a clock pulse, and is applied to the gate circuit 50. The gate circuit 50 uses the output pulse of the J-KFF 49 as a gate pulse, outputs the output signal of the counter 48 as a gate pulse, and triggers the MM 5l. As a result, a pulse of 275.34961 kHz with a duty cycle of 50% is supplied to the mixer 52 as a pilot signal FP3 from MM5l. Above FPl,f
P2 and FP3 are added together in mixer 52 and terminal 53
The signal is then guided as a pilot signal to the terminal shown at 19 in FIG.

As a result, the pilot signals FPl and fP2 are recorded every four field periods and in correspondence with the horizontal blanking period of the video signal to avoid bead interference with the video signal recorded on the main track. However, at the recording switching position, FP, is recorded as shown in FIG. 4B.

The phase relationship between the luminance signal and FPl, fP2, fP3 is the fourth
The result will be as shown in Figures A and B. Pilot signal FPl,f
Since the frequencies of P2 and fP3 are selected by the counters 3r, 44, and 48 to be an odd multiple of 1 of the horizontal scanning frequency, they are in a frequency iso-leave relationship with the luminance signal, and the carrier color that has been low-pass converted The band is different from the signal band.

Therefore, when FPl and fP2 are recorded continuously as shown in Figure 4C, it is necessary to lower the recording level to a certain extent in order to reduce the bead interference on the video signal. It is possible to secure a recording level sufficient to maintain a good S/N ratio. In this way, when FP1 and fP2 are recorded as continuous signals, there are advantages such as improving the accuracy and stability of tracking servo during reproduction and also being able to continuously detect jitter. In addition, the pilot signal FP,
, fP2, and fP3 are shown as rectangular wave outputs in the figure, but they can also be recorded as sine waves by passing them through a low-pass filter. FIG. 3 shows an example of the frequency spectrum of the recording signal by the recording system of FIGS. 1 and 2.

I is the carrier shift frequency band of the frequency-modulated luminance signal, Fa is the 5.5 MHz frequency corresponding to the sync chip, Fb is the 6.1 MHz frequency corresponding to the pedestal, and FO is the 7.5 MHz frequency corresponding to the white peak. indicates the frequency of Further, the lower sideband L of the frequency-modulated luminance signal is indicated, and the lower sideband U is indicated. Further, L indicates the lower sideband of the signal frequency modulated by the audio carrier, and U indicates the upper sideband of the signal frequency modulated by the audio carrier.
Here, the audio carriers FAl and fA2 have frequencies of 3.43 MHz and 3.73 MHz, as described above, and their frequency spectra are shown by . That is, the audio signal is frequency modulated twice. Further, V indicates the band of the carrier color signal that has been low-pass converted, and in this embodiment, as an example, 1.53409
It occupies a band of 0.07MHz±500kHz. Here, the band L<15V overlaps, but since the overlapping part of the band L corresponds to the sync chip part and there is no carrier color signal there, it does not interfere with the demodulated audio. As mentioned above, the audio carrier frequency-modulated with the audio signal is superimposed on the luminance signal band-limited to approximately 3 MHz, and then frequency modulation is performed at the same time, and the carrier color signal is low-frequency converted to band V. is transmitted as the main information signal using so-called duty cycle modulation.

When transmitting a carrier color signal using this duty cycle modulation, a signal indicated by a band is generated. F.P.
, , fP2 and fP3 are located in the lower open frequency band of band V.

Separating the occupied bands of the pilot signal and the main information signal is necessary because they are reproduced by the same reproduction scanner. FIG. 5 schematically shows the outline of a track pattern on a disk recorded by the method of the present invention.

In the figure, the solid line indicates the track center line of the main track where the main information signal is recorded, and the pilot signal (reference The pilot signal (reference signal) FP2 is recorded at the position indicated by the cross mark, and the main track is the switching position (position indicated with diagonal lines) between the reference signals FP1 and FP2. Alternatively, an index signal (reference signal) or pilot signal FP3 is recorded in the intermediate portion. Note that the reference signal FP3
The recording position is recorded in one vertical blanking period recording section among the four vertical blanking period recording sections recorded per one rotation of the disk. FIG. 6 shows a block diagram of an embodiment of the regeneration system of the method of the present invention.

As mentioned above, the main information signals are a color video signal and an audio signal, and the audio carriers FAl and fA2, which are obtained by frequency modulating separate carrier waves with two channels of audio signals, are frequency division multiplexed onto the luminance signal. A frequency-modulated wave signal is generated by frequency-modulating another high-frequency carrier wave with a multiplexed signal, while the carrier color signal is frequency-converted to the lower frequency side of the frequency-modulated wave signal while maintaining the frequency interleaf relationship. However, a signal obtained by amplitude control of these frequency modulated wave signals and a low frequency converted carrier color signal after mixing is recorded on the disk. An information signal reproduced from this disk by known means such as detecting a change in capacitance between the disk and an electrode of a scanning needle serving as a reproduction scanning element is supplied from an input terminal 61 to an AGC circuit 62a, where it is set at a constant level. be done. Here, as a reproduction method of F2Pl and fP2,
When the reproduction scanner is accurately scanning the main track, it does not scan the recording tracks FPl and fP2, so FPl
, fP2 are not regenerated and the pilot signal of either FPl or fP2 is regenerated only when a tracking deviation occurs, or when the main track is being scanned accurately, the relative of FPl or fP2 is There is a case of constant reproduction of FP, , fP2 in which the reproduction level ratio is constant and the occurrence of tracking deviation is detected when this relative level ratio is no longer a constant value. In any case, when tracking deviation occurs, FP1 or FP2 is reproduced and exists in the above-mentioned reproduced signal. The reproduced signal from the AGC circuit 62a is supplied to band filters 63 and 64, which will be described later, of the AGC circuit 62b1, respectively.

Here, the AGC circuit 62a may be unnecessary depending on the reproduced information signal, and the AGC circuit 62b is configured to perform AGC operation only in the pilot signal band. AGC
The output signal of circuit 62b is supplied to bandpass filter 65,
Here, only the signal components in the pilot signal frequency bands of FPl, fP2, and fP3 are filtered to the band amplifiers 66 and 67.
and 68, and the reproduced pilot signals of FP, , fP2, and fP3 are separated, amplified, and taken out. The AGC circuit 62b is supplied with the output signal of the bandpass filter 65 as a control signal, and operates so that the sum of the reproduction levels of FP1 and FP2 is always constant. Of the above reproduced pilot signals, FPl and fP2 are input to the tracking servo circuit 69, used to generate a tracking servo drive current, and sent to the output terminal 7 as a tracking control signal.
0 to the tracking servo mechanism.

Here, when the recording position of the reference signal (index signal) FP3 is considered as the starting point, the reference signal FPl or FP2 recorded on the outer track of the tracks on both sides of the main track during one rotation period of the disk and the inner track The recording positional relationship of the reference signal FP2 or FPl recorded on the track is as follows:
As can be seen from FIG. 5, the inputs FP, , fP2 of the tracking servo circuit 69 must be input to the tracking servo circuit 69 in order to properly track the main track, since the inputs FP, , fP2 change alternately every period of one rotation of the disk.
It is necessary to substantially reverse each rotation of the disk. Therefore, since the signal FP3 which has been tuned and amplified by the band amplifier 68 is outputted at the recording switching point of FPl and fP2 for each rotation period of the disk, the index signal FP3 is transmitted to the switch SW2 and the detection circuit connected to the contact c. FFr2 is triggered through 71, and logic "O", "1" is generated at the phase where FP3 exists every time the disk rotates.
FP is sent to the tracking servo circuit 69 with a rectangular wave that repeats
, , fP2 as a switching signal for switching the polarity, a correct error signal can be obtained.

Specifically, in the tracking servo circuit 69, the envelope detection output of each output reference signal of the band amplifiers 66 and 6r is connected to an inverting input terminal and a non-inverting input terminal of a differential amplifier (none of which are shown) via a switch circuit. The above switch circuit switches the input to the differential amplifier every time the signal FP3 is regenerated. The inverting input terminal of the amplifier is always supplied with the reference signal FPl or FP2 reproduced from the outer side of the disk, and the non-inverting input terminal is supplied with the reference signal FP2 reproduced from the inner side of the disk.
Alternatively, FPl is always supplied.

On the other hand, the main information signal in the reproduced signal is filtered through the band filter 63.
The carrier chrominance signal that has been low-pass converted by the bandpass filter 64, the luminance signal that has been frequency modulated by the bandpass filter 64, and the audio signal that has been frequency modulated are separated.

The above separated reproduced low-pass conversion carrier color signal is supplied to the ACC circuit 73, where the burst gate pulse generator R
4, the color burst signal is extracted by the burst gate pulse generated from the reproduction synchronization signal, and the level is adjusted based on the burst level. The extracted color burst signal is supplied to a phase comparator 75, where the phase is compared with the output of a variable frequency oscillator (hereinafter referred to as VFO) 76, and a phase error voltage is extracted. By supplying the signal to the VFO 76 through the switch SW and varying its oscillation frequency, the APC loop is closed and the oscillation frequency of the VFO 76 is controlled in accordance with the color burst signal. The oscillation frequency in this case is centered at 1.5340907 MHz and includes reproduction jitter. In addition, the reproduced low frequency conversion carrier color signal whose level has been adjusted by the ACC circuit 73 is reproduced by taking the difference frequency from the signal containing jitter generated at -Fsc from the output of the VFO 76 in the color signal conversion circuit 77. One jitter component is canceled and the color subcarrier frequency Fsc is returned to approximately 3.58 MHz to form a carrier color signal, which is then supplied to mixer R8.

The reproduced signal filtered by the band filter 64 is sent to the FM demodulator 7.
After being subjected to FM demodulation and appropriate de-emphasis at step 9, the signals are supplied to a synchronizing signal separation circuit 80, a low-pass filter 81, and band filters 82 and 83 for separating only the audio carriers FAl and fA2, respectively. . The output of the synchronization signal separation circuit 80 is supplied to a gate pulse generation circuit 84, where it is formed into a gate pulse for a period of 1H to several H immediately after the vertical synchronization signal, and then supplied to a gate circuit 85. In addition, the audio carrier FA is transmitted from the low-pass filter 81.
FM demodulated signal excluding l, fA2, i.e. band 3MH
The demodulated luminance signal below z is sent to the gate circuit 85.
On the other hand, it is supplied to the mixer 78, where it is mixed with the reproduced carrier color signal from the color signal conversion circuit R7 to form the original reproduced color video signal, and is led to the output terminal 86. Further, only the index signal is extracted from the demodulated luminance signal by the gate circuit 85, appropriately amplified by the band amplifier 8r, and applied to the contact d of the switch SW2. This switch SW2 is closed to contact d when using the index signal added to the luminance signal, and is closed to contact c when using the pilot signal FP3.
For example, FP3 is used for information signals without vertical blanking periods, such as audio multi-channel records. Here, FP
Since l has a frequency that is 1/3 of the low-pass conversion color subcarrier frequency, the output signal of the VFO 76 is input to the counter 88.
After counting down to 1/3 at
It is also possible to create an APC loop by returning the phase error voltage to the FO 76. In this case, since the phase comparison is performed at a low frequency, there is an advantage that even if the phase error is large, it can be tracked. It also has the advantage that it can be used to detect playback jitter even in the case of audio multi-channel records that do not have color burst signals. On the other hand, the audio carriers FAl and fA2 are separated by band filters 82 and 83 and then supplied to demodulators 90 and 91 where they are FM demodulated and guided to output terminals 92 and 93. It should be noted that although the low-frequency converted carrier color signal is generated as a bead component in the demodulated video signal, it is considerably reduced compared to the case of bead interference of the audio carrier due to the eye accumulation effect due to the frequency interleaf relationship.

FIG. 7 shows a block diagram of the essential parts of another embodiment of the regeneration system of the method of the present invention.

In the figure, the same parts as in FIG. 6 are given the same reference numerals.
Output reproduction pilot signal FPl of band amplifiers 66, 6r
, fP2 are converted into continuous waves by ringing oscillators 101 and 102, and then supplied to frequency discriminators 105 and 106 via amplitude limiters 103 and 104, where the frequencies are discriminated, and then mixed in a mixer 10r. A speed error signal is taken out from this mixer 107 and outputted from a terminal 108 to a known speed error correction mechanism (not shown) such as an arm stretcher. In addition, in each of the above embodiments, for convenience of explanation, reference signals are referred to as index signals and pilot signals FPl, fP.
2 and fP3, the index signal does not need to be recorded. As described above, the information signal recording and reproducing method according to the present invention is characterized in that the information signal recording and reproducing method according to the present invention is a method for recording and reproducing information signals modulated by an audio signal.
One or more carriers with a frequency higher than the upper limit frequency of the luminance signal are superimposed on the luminance signal, and another carrier is frequency-modulated with the superimposed signal to generate a frequency-modulated wave signal, and the carrier color signal is Converting the frequency modulated wave signal to the lower frequency side and so that the color subcarrier frequency becomes a frequency interleaf with the horizontal synchronization signal, and converting the frequency modulated wave signal and the low frequency converted carrier color signal. The mixed signal is passed through an amplitude limiter so that the frequency-modulated wave signal is expressed as a repetition frequency, and the low-pass converted carrier color signal is pulse-width-modulated expressed as a change in duty cycle. The pulse is recorded as a main information signal on a spiral or concentric main track on a rotating recording medium as a change in geometrical shape, and the pulse is alternately switched every rotation period of the rotating recording medium. The first and second reference signals inserted at this switching position and the third reference signal inserted at this switching position occupy a frequency band lower than the recording band of the main information signal and have different frequencies from each other. The first and second reference signals are selected to have a frequency interleaf with the horizontal synchronization signal, and are recorded approximately in the middle between each track of the main tracker, and the third reference signal is recorded on the main track. Alternatively, each of the first to third reference signals is recorded on a substantially intermediate portion between each track of the main track, and during reproduction, the first to third reference signals are picked up and reproduced by a reproduction scanner that scans the rotating recording medium. for differentially reproducing and supplying the reproduced first and second reference signals to a tracking control circuit to compare the levels of the detection outputs of both reference signals and correcting the tracking deviation of the reproducing scanner from the main track; Since a tracking error signal is generated and the polarities of the first and second reference signals supplied to the tracking control circuit are substantially inverted every time the third reference signal is reproduced, the following It has the following characteristics.

1 Even if the distortion in the transmission system is relatively large, a luminance signal, a carrier color signal, and one or more audio signals can be recorded and played back on the same track without causing noticeable bead interference in the demodulated video signal. be able to.

2. Since the first to third reference signals (pilot signal, index signal) are generated by counting down the color subcarrier, they have extremely good frequency stability.

3. The first and second reference signals can be recorded continuously at a recording level with a sufficient S/N ratio.

When the reference signal is continuously recorded in connection with 43,
The accuracy and stability of the tracking servo during reproduction can be improved compared to the case of intermittent recording, and the accuracy of speed error detection can also be improved.

5 If the detection output of the reference signal FP3 recorded in the intermediate portion between each track of the main track is used as the tracking polarity reversal signal supplied to the tracking servo circuit, it is possible to Tracking can also be suitably performed on a disk on which information signals without line erasure periods are recorded.

6. A signal obtained by counting down the output signal of the VFO and the signal obtained by counting down the output signal of the VFO are applied to a variable frequency oscillator (VFO) that generates a frequency conversion signal used to return the low frequency conversion carrier color signal to the original band during reproduction. By applying a phase error signal obtained by phase comparison with the first or second reference signal as a frequency control voltage, when the phase comparison is performed using a color burst signal in a low-pass conversion carrier color signal. It is possible to track even when the phase error is larger.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a recording system according to the method of the present invention, FIG. 2 is a block diagram of an embodiment of the main part of FIG. 1, and FIG. 3 is a frequency diagram of a recording signal according to the method of the present invention. A diagram showing an example of a spectrum. FIGS. 4A to 4C are waveform diagrams of main parts of signals recorded by the recording system of the method of the present invention, and FIG. 5 is an example of a track pattern of a rotating recording medium recorded by the method of the present invention. FIG. 6 is a block system diagram of one embodiment of the regeneration system of the method of the present invention, and FIG. 7 is a block diagram of main parts of another embodiment of the regeneration system of the method of the present invention. . 1, 2... Audio source, 3, 4... Frequency modulator, 5... Color video signal source, 6...
... Color signal, luminance signal separation circuit, 9 ... Color subcarrier generator, 10 ... Color signal conversion circuit, 12.
...Index signal generator, 13...
Pilot signal generator, 18... Main information signal output terminal, 19, 53... Pilot signal output terminal, 27, 37, 44, 48... Counter, 6
2a, 62b...AGC circuit, 69...
・Tracking servo circuit, R3...ACC circuit, 7r...color signal conversion circuit, R9, 9O, 9
l...FM demodulator, 81...Low pass filter, 101, 102...Ringing oscillator.

Claims (1)

[Claims] 1. One or more carriers modulated by an audio signal and having a frequency higher than the upper limit frequency of the luminance signal are superimposed on the luminance signal, and another carrier is frequency-modulated with the superimposed signal to produce a frequency-modulated wave signal. The carrier color signal is converted to the lower frequency side of the frequency modulated wave signal and the color subcarrier frequency is frequency interleaved with the horizontal synchronization signal, and the carrier color signal is converted to the lower frequency side of the frequency modulated wave signal and The mixed signal is passed through an amplitude limiter so that the frequency-modulated wave signal is expressed as a repetition frequency, and the low-pass converted carrier color signal is expressed as a change in duty cycle. A pulse width modulated pulse is taken out, and the pulse is recorded as a main information signal on a spiral or concentric main track on a rotating recording medium as a change in geometrical shape, and one rotation period of the rotating recording medium is recorded as a main information signal. The first and second reference signals that are alternately switched at each switching position and the third reference signal that is inserted at this switching position occupy a frequency band lower than the recording band of the main information signal, and
The first and second reference signals are selected to have frequencies that are different from each other and are frequency interleaved with the horizontal synchronization signal, and the first and second reference signals are recorded in a substantially intermediate portion between each track of the main track, and the third reference signal is is recorded on the main track or approximately in the middle between each track of the main track, and during playback, the first to third signals are picked up and played back by a playback scanner that scans the rotating recording medium. The reference signals are respectively differentially reproduced, the reproduced first and second reference signals are supplied to a tracking control circuit, and the levels of the detection outputs of both reference signals are compared to determine the tracking deviation of the reproduced scanner from the main track. A tracking error signal for correction is generated, and the polarities of the first and second reference signals supplied to the tracking control circuit are substantially inverted each time the third reference signal is reproduced. An information signal recording and reproducing method characterized by: