JPS5955685A - Recording and reproducing system of sound by magnetic disc - Google Patents

Abstract

PURPOSE:To reproduce continuous sound signals with a simple constitution, by recording a sound signal in a skipped field once and then multiplying the sound signal at the time of skip with a signal in a field to be recorded to record the multiplied signal while reading out the sound signal at the time of skip in the succeeding field period to be recorded. CONSTITUTION:A sound signal b1 at the time of skip is modulated to a high frequency carrier by a modulator 3, the modulated signal is mixed with a refference signal (p) required for positional modulation/demodulation of the video signal through a switch 4 and then the mixed signal is recorded in a recording spare head 6 through an amplifier 5. When the sound signal b1 at the time of skip is to be multiplied with a sound signal b2 of the succeeding field to be recorded to store the multiplied signal in a recording magnetic head 13, the sound signal b1 is taken out by a reproducing spare head 7 through an amplifier 8 and a BPF 9 and mixed with the succeeding sound signal b2 passing through an LPF 10. The mixed signal is FM modulated and multiplied by a modulator 11, mixed with a modulated video signal a2, recorded on the head 13 and then reproduced by a reproducing circuit consisting of a reproducing magnetic head 1, a demodulating circuit 14, a switch 15, and BPFs 16, 17.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an audio signal recording method in magnetic recording, in particular, when field skip recording a video signal, the audio at the time of skipping is recorded in a manner that increases the utilization efficiency of the recording area of a magnetic disk. The present invention relates to an audio recording system and a reproducing system for magnetic disks that can reproduce continuous audio from the recorded signals.

Conventionally, when recording video signals on magnetic tapes or magnetic disks, the frequency modulation method (I'M) using slope atomath and the phase modulation method have been used as methods that improve the recording density and are not affected by crosstalk between adjacent tracks. (PM) is known.

Among these, the PM recording method (1) synchronizes the carrier modulated by the luminance signal with the relative movement between the magnetic medium and the video head, and (2) converts this carrier into the luminance signal with a modulation index mp of 1.3 radians or less. (3) This modulated luminance signal is recorded in such a way that the recording positions of the vertical and horizontal synchronizing signals are aligned between adjacent tracks, and the phase of the carrier is also aligned between adjacent tracks. (a) Since mp≦1.3, the amplitude of the carrier component of each track is approximately constant, and since the carrier component is in the same phase between tracks, the video head does not move to the adjacent track during playback. The carrier in the reproduced signal remains constant even if it straddles, and (b) since the same <mp≦1.3,
Sideband components of the following order and above can be ignored, and the synchronization signal positions are aligned between tracks, so even if the video head straddles adjacent tracks during playback, the sideband components of the playback signal will not be synthesized from multiple frames or multiple fields. Therefore, (c) high-density recording is performed using a card panless method so that there is no gap between tracks or there is partial overwriting between tracks during recording.
On the other hand, it is known that even if there is a tracking error during reproduction, the luminance signal can be demodulated without any problem of crosstalk.

In addition, in the case of a color video signal, the color signal is also recorded, so
Under the same conditions as the luminance signal, the subcarrier is phase-modulated with a chrominance signal and recorded, or the subcarrier is carrier-suppressed and amplitude-modulated with a chrominance signal so that the phase of the carrier is aligned between tracks. This allows cyclotalk to be tolerated. Alternatively, the phase of the color signal is rotated by 90 degrees for each horizontal scan and the phase is reversed for each track (PS method), just as in the tilt athomus recording method, or one horizontal scan is performed for a certain track. For each track, the phase of the color signal is inverted and recorded, and adjacent tracks are recorded with a constant phase (pH method). This makes it possible to cancel crosstalk.

As mentioned above, is the trend toward higher density magnetic recording progressing?
On the other hand, the audio signal that accompanies the video signal has conventionally been considered only to the extent that it is recorded on a separate track for audio. This limits the overall utilization of the magnetic medium and requires an extra head for audio signals. To solve these problems, it may be possible to record the audio signal together with the video signal by frequency multiplexing, but if the video signal is recorded with a guard band, there is no problem, but if the video signal is recorded without a guard band, then the adjacent track Since there is no correlation between the audio signals, simple multiplex recording will cause audio crosstalk and is not practical.

Therefore, when recording audio, the present inventors periodically allocate carriers with different frequencies to each track in order to change the carrier of the audio recorded on each track within the track that the video head straddles during playback. proposed a method of angle-modulating the audio signal and multiplexing it with the modulated video signal (patent application filed on the same day by the applicant; title of the invention;
audio signal recording method in magnetic recording).

Referring to FIG. 1, a case will be described in which a modulated audio signal is recorded by frequency modulation and is reproduced by a scanning reproducing magnetic head that spans tracks on both sides at the time of reproduction.

In this case, since the reproducing magnetic head 1 straddles tracks on both sides, two audio carriers '1+' with different frequencies are used.
f2, as shown in FIG. 1, one audio carrier f is frequency-modulated and recorded with the audio signal to be recorded on the first track T1, and then the other audio carrier f is recorded.
2 is frequency-modulated and recorded with the audio signal to be recorded on the next track T2. In this way, audio carriers f1. of different frequencies are transmitted between adjacent tracks. f! Modulated audio signals that are frequency-modulated are recorded alternately. In this case, the audio carrier '1+f2, which has a different frequency, is frequency-modulated with an audio signal, and the nine-modulated audio signal Fl m F2 has a frequency spectrum lower than that of the color signal C, as shown in FIG. 100-200 KHz) E or
Band between color signal C and luminance signal Y (several hundred KHz) F
Alternatively, the luminance signal Y is multiplexed into a higher band (several MHz) G and recorded.

During reproduction, as shown in FIG. 1, the reproducing magnetic head 1 is scanned over the tracks on both sides, and the band filter I is switched for each track. Extracts and reproduces only the audio signal.

This audio recording method eliminates audio crosstalk between adjacent tracks even when scanning with a wide magnetic playback head, and eliminates the need for a dedicated audio track, making the use of the recording area of the magnetic disk more efficient. In other words, recording density in a broad sense can be increased.

In such an audio signal recording system, when a video signal is magnetically recorded by field skipping, a problem arises as to how to handle the audio during field skipping.

Field skip recording is a method in which video images of similar fields are thinned out and recorded to the extent that the image quality is not adversely affected when almost similar video images are consecutive, and during playback, the recorded tracks are Since the upper field is repeatedly reproduced by the number of fields thinned out, the movement of the surface may be somewhat unnatural, but even if the recording medium is the same and the recording density is the same, the recording time can be saved, so in a broad sense, the recording density This can be said to be a method that can increase the

Furthermore, one of the advantages of adopting this field skip method is that, especially in concentric recording, the recording head must be moved within a very short time when moving from the end of one track to the beginning of the next track. This means that the constraints on the control mechanism ± can be relaxed. For example, when recording one field of an NTS (4-format video signal) in one rotation of the disk without field skipping, it is necessary to control the head movement so that the head movement ends within microseconds. On the other hand, when field skipping is performed for each field, the head only needs to be moved slowly for one field, that is, 1/6o seconds, and the head control mechanism is greatly simplified.

On the other hand, the recorded information is bound to be interrupted in some places in terms of time.

Therefore, an object of the present invention is to provide an audio recording method suitable for the video signal recording method based on guard panless recording as proposed above, which uses a simple circuit to record audio as a continuous signal during field skip recording. An object of the present invention is to provide an audio recording method and a reproducing method for a reproducible magnetic disk.

This object of the present invention can be achieved in the following manner. That is, the audio recording method of the present invention uses audio carriers with different frequencies for adjacent tracks of a magnetic disk, and frequency-modulates or phase-modulates the audio carriers for each track's audio signal to obtain a modulated audio signal. In the recording method, when field-skip recording a video signal, the audio signal during the field skip, that is, the audio signal during the period when recording is stopped, is frequency-modulated and recorded on an auxiliary track, and this recorded audio signal is used next. The audio signal of the field to be recorded is multiplexed with the audio signal of the field to be recorded while being read out during the period of the field to be recorded, and the audio signal is recorded on the video track. The same track on the disk is repeatedly scanned by a reproducing magnetic head for an extra number of fields, and from the multiplexed audio signal output obtained by the reproducing magnetic head, the audio signal corresponding to each field is extracted for each field. By sequentially switching bandpass filters with different frequency bands, the signals are separated and reproduced.

Examples of the method of the present invention will be described below. In this embodiment, an example will be explained in which both the audio recording method and the audio reproducing method are recorded using frequency modulation. Furthermore, the field skip is assumed to skip one field, and skips the video signal ais Bay ag... of the odd numbered field shown in FIG.・Should be recorded.

Furthermore, it is assumed that one field is recorded on one track on the magnetic disk 2, as shown in FIG. 4, and each track is formed concentrically on the magnetic disk 2.

In the audio recording system of this embodiment, the audio signal b1. of the field skipped during field skip recording.
b3. b, . . . are video signals al, 8B.

Since it is skipped together with al,..., the audio signal at the time of skipping is... b3. The audio signal b when skipping so that b,... is not interrupted! , b3. As shown in FIG. 4, an auxiliary track To for temporarily recording bs... is provided on the outermost circumference of the magnetic disk 2. This auxiliary track To has a field audio signal bhb3.bhb3. b5... are recorded once.

For example, when recording the audio signal b1 at the time of skip, as shown in FIG. 5(a), the audio signal b1 at the time of skip is recorded.
1 by the modulator 3), then frequency-modulated with a carrier of a higher frequency than the audio signal 4b2 of the recorded Zubesa field,
It is mixed with a reference signal P necessary for phase modulation and demodulation of the video signal to be recorded on the same auxiliary track To through the switch 4 which is turned on during the skip period, and is recorded by the recording auxiliary head 6 through the amplifier 5. In this case, the frequency array after modulation of the audio signal b1 during skipping is as shown in FIG. 6(a).

The skip audio signal b1 once recorded on the auxiliary track qlo in this way is used when recording the audio signal bm of the next field to be recorded (the second field in FIG. 3(a)) on the track of the magnetic disk. is shown in Figure 5 (b
) As shown in FIG.
The audio signal of the next field to be recorded is extracted through b! The recorded data is multiplexed with the recording magnetic head (video head) 13 and recorded. In this case, Fig. 5 (b
), the skipped audio signal b1 extracted by the playback auxiliary head 7 through the bandpass filter 9 is mixed with the audio signal b11 of the next field to be recorded, which has been passed through the low-pass filter 10, and then sent to the modulator. 11 is frequency modulated and multiplexed, and further modulated video signal a! The mixed signal is mixed with the signal, passed through an amplifier 12, and recorded on a track on a magnetic disk by a recording magnetic head 13. Figure 3 (b)
In the state shown in FIG. 3(C), the audio signal b! , b2 are recorded on the same track, and the modulated audio signal b at this time
1. b! The frequency arrangement is as shown in FIG. 6(b). still,
These audio signals are based on the low band (100~
200 KHz), a frequency band between the modulated chromaticity signal and the modulated luminance signal (several hundred kHz), or a high frequency band (several MHz) of the modulated luminance signal.

In this case, the video signal recording method may be the above-mentioned PM modulation method or the inclined azimuth recording method using FM modulation. Any recording method may be used.

Next, an audio reproduction method for reproducing audio signals multiplexed and recorded on tracks ± of a magnetic disk in this manner will be described.

As mentioned above, when reproducing audio signals, the video signal recording method assumes panless recording and can ignore the influence of crosstalk from adjacent tracks, so the scanning width is larger than the track width as shown in Figure 1. Reproduction can be performed using the magnetic head 1. In this embodiment, the reproducing magnetic head 1 has a scanning width that spans both adjacent tracks (ie, three tracks). To reproduce, the wide magnetic reproduction head 1 scans the same track repeatedly by the number of skipped fields. In this embodiment, since the skip is one field, the same track is scanned one extra time, that is, twice in total. By this repeated scanning, the same video signal for two fields is obtained. On the other hand, in the case of an audio signal, as shown in the schematic block diagram of FIG. 7, an example of an audio reproduction circuit, the audio signal is transmitted from the reproduction magnetic head 1 through the demodulation circuit 14,
By selectively connecting bandpass filters 16 and 17 having different frequency bands to the switch 15, the audio signal b1 of the skipped field and the audio signal b2 of the next field to be recorded are separately extracted. Tsumashi, 1
Audio signal b1 of the field skipped in the second scan
is extracted, and in the second scan, the audio signal S of the next field to be recorded is extracted. In this way, the audio signals multiplexed and recorded on the tracks of the magnetic disk are reproduced from the state shown in FIG. 3(C) to the state shown in FIG. 3(a).

Note that in the embodiments of the audio recording method and the audio reproducing method described above, for convenience, explanations have been given based on the case where the skip period is one field, but the number of fields to be skipped is not limited to one field. Further, in the above embodiment, the audio signal modulated by frequency modulation was recorded on the magnetic disk, but it can be similarly modulated by phase modulation.

As explained above, according to the audio recording method of the present invention,
When performing field skip recording of a video signal, the audio signal at the time of skipping is once recorded on an auxiliary track, and this audio signal is read out at the time of the next field to be recorded and multiplexed with the audio signal of this field to be recorded and recorded. Since this method eliminates the need for a dedicated audio track during skipping, it is possible to achieve high-density recording in the broad sense described above. Furthermore, according to the audio reproduction method of the present invention, the audio signals multiplexed and recorded in the audio recording method are separated by switching band filters, and then reproduced by retrieving the signals, which is a simple method. Depending on the configuration, it is possible to perform field-skip recording, that is, to reproduce continuous audio signals despite intermittent recording.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating a conventional audio recording system, FIG. 2 is a diagram showing its frequency arrangement, FIGS. Figures (a) to (C) are schematic diagrams showing fields for explaining the recording method;
The figure is a schematic diagram of a magnetic disk, Figures 5 (a) and (b)
is a schematic block diagram of a recording circuit implementing the audio recording method,
FIGS. 6(a) and 6(b) are diagrams showing the frequency arrangement of the audio signal at the time of skipping and the mixed audio signal, and FIG. 7 is a schematic block diagram of a reproducing circuit implementing the audio reproducing method. In the drawing, 1 is a reproduction magnetic head, 2 is a magnetic disk, 3.11 is a frequency modulator, 4.15 is a changeover switch, 5.8.12 is an amplifier, 6 is a recording auxiliary head, and 7 is a reproduction auxiliary head. Head, 9.16.17 is a bandpass filter, 10 is a low-pass filter, 13 is a recording magnetic head (video head), 14 is a demodulation circuit, a1+ am+ 83+ a4°°1 is a video signal, bl
+ bl + bl + b4... is an audio signal. l1lo is an auxiliary track. Figure 6 (a) (b)
Figure 7 6

Claims (2)

[Claims] (1) An audio carrier that records a luminance signal and/or a color signal of a video signal on a magnetic disk without forming a gap between adjacent tracks, and at the same time has a different frequency for each adjacent track on the magnetic disk. In a magnetic disk audio recording system in which a modulated audio signal obtained by frequency-modulating or phase-modulating the audio signal of each track is recorded on the adjacent track, when performing field skip recording of the video signal,
An auxiliary track is provided on the magnetic disk, and the audio signal of the field to be skipped is temporarily recorded on this auxiliary track, and the audio signal of the skipped field is read out during the period of the next recording field while recording the field to be recorded. An audio recording method for a magnetic disk, which is characterized in that the audio signal is multiplexed with the audio signal and recorded on the magnetic disk. (2) An audio carrier that records a luminance signal and/or a color signal of a video signal on a magnetic disk without forming a gap between adjacent tracks, and at the same time has a different frequency for each adjacent track on the magnetic disk. When field skip recording of the video signal is performed in a recording method in which the modulated audio signal obtained by frequency modulating or phase modulating the audio signal of each track is recorded on an adjacent track, The audio signal of the field to be skipped is once recorded on the auxiliary track, and this skipped audio signal is read out during the period of the next field to be recorded and multiplexed with the audio signal of the field to be recorded. Repeatedly scanning the same track on the disk by the number of sysquigged fields by a reproducing magnetic head, and sequentially switching bandpass filters with different frequency bands from the multiplexed audio signal output obtained from the reproducing magnetic head. A magnetic disk audio playback method that is characterized by separating and playing back the audio.