JPS61139903A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To maintain an interchangeability to a conventional device, and also to obtain a high tone quality by constituting the titled device so that a sound signal can be superposed and recorded on a track which has recorded a video signal, and recording of the sound signal can select one of FM and PCM recordings. CONSTITUTION:A sound signal which has been applied to a terminal 20 passes through a recording side sound signal processing circuit 21 and selects by a switch 32 one of a PCM code modulator 33 or an FM modulator 34, and it is amplified 19, and thereafter, superposed and recorded on a track which has recorded a video signal of a magnetic tape through rotary heads 11, 12. At the time of reproduction, the sound signal is reproduced by the rotary head 11 and 12, amplified 26, and thereafter, decoded to a sound signal by a PCM decoder 30 through a changeover switch 29, and outputted to a terminal 28 through a voice processing circuit 27. In this regard, reproduction of an FM voice recording tape can be realized easily, too, by providing an FM demodulator 31 as necessary. Accordingly, a tape which has been recorded by a device of this constitution can be reproduced by a conventional device which records a voice by a fixed head, and also a tape which has been recorded by the conventional device can be reproduced by this device, as well.

Description

DETAILED DESCRIPTION OF THE INVENTION For industrial applications, the present invention is directed to a rotary head video tape recorder (hereinafter referred to as VT).
The present invention relates to a magnetic recording and reproducing apparatus configured to improve the quality of audio signals in the audio signal (referred to as R).

BACKGROUND OF THE INVENTION In conventional VTRs, video signals are transmitted by a rotating head.
Each audio signal was recorded on a dedicated track on the magnetic tape by a fixed head. However, as the length of VTRs increases, the tape running speed has become slower, and in this case, the same wave number characteristics and S/N of the audio signal deteriorate, resulting in the problem of not being able to obtain high-quality reproduced sound. Ta. In order to obtain high quality playback sound even at low tape speeds,
Modulate and record the audio signal on the video track of the VTR7
A method (for example, electronic withdrawal magnetic recording study group material MR83-19, pages 9-14) has been put into practical use.

FIG. 6 shows the frequency allocation in this recording method, and FIG. 7 shows the recording state in the depth direction of the magnetic tape.

In FIG. 6, 1 is a luminance signal containing a frequency modulated synchronization signal, and 2 is a low frequency or switched carrier chrominance signal. 3 is a signal obtained by frequency modulating (FM) an audio signal, and is recorded by an audio-dedicated head at an azimuth angle different from that for the video signal in the band between the low frequency conversion carrier color signal 2 and the FM luminance signal 1. be done.

As is clear from FIG. 7, the same wave number modulated audio signal is transmitted to the magnetic layer 4 with a large recording current before the video signal.
The video signal is then recorded in the surface layer 4b of the magnetic layer 4. In addition, 5 indicates a base film.

In the case of such a conventional example, the audio signal is recorded in FM, so the S/N ratio is high, the quality is good, and the sound quality does not deteriorate even if the tape running speed is slowed down, so it is suitable for long-term VTR recording. It can be said that this is one of the most effective recording methods. Moreover, it is noteworthy that it utilizes the deep layer of the magnetic tape magnetic layer, which was not previously used.

However, in recent years, there have been many opportunities to come into contact with high-quality audio sources such as compact discs and audio PCM broadcasts via broadcasting satellites, and there has been a growing consensus that the above-mentioned VTR audio recording system is not fully satisfactory. The main points are that head switching noise occurs, the distortion rate is high, and after-recording is impossible.

PCM recording of audio is a good way to eliminate these problems, but current consumer VTRs do not have the recording density to record PCM wideband audio signals added to video signals. .

As mentioned above, in order to improve the sound quality of a VTR, it is necessary to improve the sound P.
CM recording is the best, but since it is impossible to record audio PCM signals along with video signals with conventional consumer VTRs due to recording bandwidth, FM recording of audio is adopted, which is not always satisfactory. There was a problem in that the audio quality was not as good as it could be.

In view of the above-mentioned problems, the present invention records an audio signal in the shallow layer of the video track where the video signal is recorded using PCMj, and a wideband digital signal to achieve high sound quality of a VTR, and also to improve the sound quality of a VTR. The present invention is designed to be compatible with recording systems, and provides a magnetic recording/reproducing device that can perform both FM audio recording and PCM audio recording.

Means for Solving the Problems In order to solve the above problems, the magnetic recording and reproducing apparatus of the present invention has a first rotary head for recording and reproducing video signals and a second rotary head having a different azimuth angle. The audio signal is recorded over the trunk on which the audio signal is recorded, and the video signal and the audio signal are reproduced by heads having different azimuth angles, and the audio signal is recorded by either frequency modulation recording or code modulation recording. It is structured so that it can be selected.

Effects of the present invention With the above-described configuration, when recording and reproducing extremely high quality audio is desired, the first rotary head records the video signal, and then the second rotating head with a different azimuth angle records the video signal.
The rotating head records the PCM audio signal at a low level. If playback is performed using each head, since the azimuth angles are different, the video signal and the PCM audio signal will be played back separately, making it possible to obtain reproduced sound of extremely high quality at the same time as the video signal. It also has an FM audio recording function and
When playing on a conventional VTR that does not have a commercial audio recording function, the video signal is recorded with the first rotating head, and then the FM audio signal is recorded at a low level with the second rotating head. This also makes it possible to record FM audio. Therefore, it is possible to provide compatibility in which video signals and high-fidelity audio signals (based on FM recording) can be played back by playing a tape recorded according to the present invention on a VTR having an FM recording system for audio signals.

Embodiment Below, a magnetic recording and reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a recording state diagram in the depth direction of the magnetic layer for explaining the present invention in detail.

When video signals are recorded on magnetic tape using a rotating head in the conventional manner, the depth of the recording layer is 0.25 of the recording wavelength.
~0.3 times, and 0.3 to 0 for current consumer VTRs.
．． This means that recording is made to a depth of 8 μm, and since the thickness of the magnetic layer 6 of a general magnetic tape is 2 to 4 μm, a non-recording layer 6C exists as shown in FIG. The conventional example explained in FIGS. 6 and 7 utilizes this non-recording layer, but due to the nature of wood, only long wavelength (low frequency band) signals can be recorded. In fact, the shallow part of the tape magnetic layer is suitable for recording broadband signals.
Video signals are recorded only on the surface.

The present invention focuses on the fact that recording and reproducing video signals does not require a high S/N for recording and reproducing digital signals and FM audio recording, and a broadband The digital signal still records the FM audio signal and uses it as an audio signal recording layer. Note that 7 in FIG. 2 indicates a base film. Hereinafter, first, PCM audio recording will be explained. For reproducing digital signals, the S/N is 1s d.
If B, the bit error rate is about 10, which is close to a practical value. It is sufficient if an S/N of 20 to 30 dB can be secured with a margin. Therefore, digital signals to be recorded in a shallow layer may be recorded at a depth that satisfies the above-mentioned value for S/N. The depth of the recording layer can be controlled by, for example, a recording current, and if a video signal is recorded at the optimum current (reproduction output power 11, current value 1), the recording current of the digital signal is % to % is sufficient. Naturally, the digital signal is recorded in a shallow layer after the recorded video signal, so the playback output of the video signal decreases, but the extent of this is small because the digital signal recording layer is extremely thin. It falls to 3~edB. Moreover, since the noise due to the surface nature of the tape is recorded in the shallow layer of the digital signal, it is difficult to directly affect the reproduction of the video signal, and modulation noise is reduced, so the actual S/N reduction of the video signal is 2 to 2.
It remains at around 3dB. In this way, it is possible to suppress the S/N deterioration of the previously recorded video signal and record a digital signal having a practical code error rate thereon.

By the way, if the occupied bands of the video signal and the digital signal are far apart, it is possible to obtain the desired signal from the reproduced signal using a filter, but consider the case where the two signals are close to each other or overlap. For example, it is necessary to make the azimuth angle of the rotary head for recording and reproducing video signals different from the azimuth angle of the rotary head for recording and reproducing digital signals. Generally, it is known that if the gap direction of the reproducing head is inclined by θ with respect to the gap direction of the recording head, the following loss will occur.

However, W Nidlab 2 width λ: Recording wavelength Therefore, the reproduction output of the video signal rotary head does not pick up the signal recorded on the digital signal recording layer 6a, but reproduces only the video signal, and the digital signal rotary head The azimuth angle of the reproduction output can be set so that only the digital signal is reproduced without picking up the signal from the video signal recording layer 6b. For example, if the azimuth angle of the video and digital heads is set to 3
Practical track width of 1.5 by varying 0'
It is possible to share the band of both signals over the entire band of ~2% tk or more. As a result, as shown in Fig. 3, the frequency-modulated luminance signal 1 and the low-band-converted carrier fading signal 2 are frequency-multiplexed and recorded on the video signal recording layer 6b. A broadband digital signal 16 can be recorded on the digital signal recording layer 6a. In the case of 1 frequency allocation shown in Figure 3, the S/N deterioration of the video signal is only 2 to 3 dB, which is approximately 41 Ik.
This means that, for example, an audio signal can be digitally recorded using a PCJ, and the audio F signal explained in the conventional example of FIGS. 6 and 7 can be recorded.
This shows that it is possible to record and play back audio signals much better than M recording. Of course, digital signals can be used for other purposes than PCM audio signals.

FIG. 4 is a diagram showing an example of the configuration of a rotary head group for realizing the magnetic recording and reproducing method of the present invention. The magnetic tape 1o travels in the direction of the arrow AK, and the rotating cylinder 16 rotates in the direction of the arrow B at 301, so-called rotation 2 helical type V.
It is TR. In this case, the video signal gutter 13 contacts the tape before the audio signal gutter 11, and the video signal head 1
4 contacts the tape before the audio signal head 12. For example, the azimuth angles of the video signal heads 13 and 14 are set to ±6°, and the audio heads 11 and 1
The azimuth angle of 2 is ±30'. With this configuration, a video signal is first recorded on the track on the magnetic tape, and then an audio signal is recorded on the shallow layer by a separate azimuth head. The recording current of each head is the video signal head 13,
14 is set to the optimum recording current, a fraction of the optimum current is supplied to the audio signal head, and settings are made so that the audio signal is recorded only in the shallow layer portion.

Next, FM audio recording will be explained.

As already explained in the conventional example shown in FIGS. 6 and 7,
In audio FM recording, FM audio signals are recorded in the deep layer of the magnetic layer. To reproduce this, the video signal recording layer acts as a kind of space, and the signal actually picked up by the head is attenuated by about 1 s dB, so the C/N is 30 to 35 dB.
That's about it. Therefore, even in the case of FM audio recording, an S/N ratio comparable to that of a video signal is not required, and it is possible to record at a low recording level in the shallow layer of the tape. FIG. 5 shows a spectrum diagram showing shallow layer recording/reproducing characteristics. (a) shows the case where a 4Vh single frequency was recorded (bl is 2.
This is the characteristic when recording 51h at a low level, and even though the C/N deterioration of 4- is slight from these, l-+f
It is shown that rllC2,sih signal e can be obtained at a/N-:3sdB 8 degrees. Therefore, it can be said that it is also possible to record the FM audio signal on the video signal track. In that case, in order to maintain compatibility with the conventional FM audio recording system, the azimuth angle of the second rotary head should be set almost the same, and the frequency allocation should be set the same as the conventional example shown in Figure 6. It is necessary to set this in advance and to approximately align the scanning loci (tracks on the tape) of the rotary head.

FIG. 1 is a block diagram of essential parts of an embodiment of the present invention. In this embodiment, the audio P is recorded and played back simultaneously with the video signal.
So-called high-fidelity V, which is capable of recording and playing commercials and also records FM audio signals deep within the video signal.
It shows a configuration that is compatible with TR. In the figure, a video signal is applied to a terminal 17, passed through a recording side video signal processing circuit 18, amplified by a recording amplifier 19, and recorded on a magnetic tape through rotary heads 13 and 14. The recording side video processing circuit 18 frequency-modulates the luminance signal, performs low frequency conversion on the carrier color signal, and converts it into the frequency bands of the luminance signal 1 and carrier color signal 2 shown in FIG. Next, the audio signal applied to the terminal 2o passes through the recording side audio signal processing circuit 21, selects either the PCM code modulator 33 or the FM modulator 34 with the switch 32, and is amplified by the recording amplifier 22.
The information is rotated and recorded on magnetic tape through channels 11 and 12.

Next, the time of reproduction will be explained. Video and audio signals recorded on magnetic tape are played back using dedicated heads with different azimuth angles. The video signal is reproduced by the rotary heads 13 and 14, amplified by an amplifier 23, and then input to a reproduction side video signal processing circuit, demodulated to the original video signal, and outputted to a terminal 26. The audio signal is reproduced by the rotary heads 11 and 12, amplified by an amplifier 26, passed through a changeover switch 29, decoded into an audio signal by a PCM decoder 30, and outputted to a terminal 28 via an audio processing circuit 27. This reproduced audio signal is digitally recorded and reproduced on a magnetic tape using PCML, and it goes without saying that high-quality reproduced sound can be obtained that is not affected by the characteristics of the tape.

Note that it is also easy to provide an FM demodulator 31 as necessary to realize reproduction of an FM audio recording tape. In addition, FM
The demodulator 31 and the switch 29 can be deleted when the reproduction of FM audio by this device is unnecessary. .

The FM audio recorded by the apparatus of this embodiment can be reproduced by a conventional FM audio recording type VTR.

That is, in the existing device, FM audio is recorded in the deep layer of the video signal, whereas in this embodiment, the FM audio is recorded in the shallow layer of the video signal. If you select the same values, set the head height to satisfy the tracking conditions, and match the conditions such as the FM carrier frequency and modulation degree, it is possible to reproduce FM audio using a conventional VTR. It is. Further, the FM demodulator 31 in the embodiment
By providing this, it is possible to reproduce FM audio recorded by a conventional VTR and the apparatus according to this embodiment.

Effects of the Invention According to the present embodiment, as described in E, what is used for the second rotary head having a different azimuth angle from the first rotary head for recording and reproducing video signals in a VTR, and the second rotary head for recording and reproducing video signals on the track on which the video signal is recorded. The system is equipped with a means for overlapping recording of audio signals on the camera, and is configured so that either FM recording or PCM recording can be selected for audio signal recording, thereby maintaining compatibility with VTRs that perform FM deep recording and playback in existing formats. , it is also possible to record and play back PCM audio using the second rotary head. Therefore, a tape recorded with the device according to the present invention can be played back with the conventional device, and a tape recorded with the conventional device can be played back with the device according to the present invention. ::
4f! 6. Etn54'Iil;Ia J It is possible to achieve high sound quality in a VTR while maintaining full compatibility with the device.

Furthermore, in the apparatus according to the present invention, since the audio signal is recorded in the shallow layer, it is possible to perform after-recording of the audio.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a magnetic recording/reproducing device according to an embodiment of the present invention, Fig. 2 is a recording state diagram in the depth direction of a magnetic tape for detailed explanation of the present invention, and Fig. 3 is an example of a frequency allocation tandem. 4 is a configuration diagram of a magnetic head used in the present invention, FIG. 6 is a single frequency recording spectrum diagram according to the present invention, and FIGS. 6 and 7 are frequency allocation diagrams for explaining conventional examples. FIG. 2 is a diagram showing the recording state in the depth direction of the magnetic tape. 13.14... Rotating head for video, 11.12
...Rotary head for audio, 29.32...
Changeover switch, 3-3...PCM code modulator,
34...FM modulator, 30...PCM
Decoder, 31...FM demodulator, 6...
Magnetic layer, 6a...Audio signal recording layer, sb...
...Video signal recording layer, 6C...Non-recording layer, 3
...FM audio band, 16...PCM signal band. Name of agent: Patent attorney Souo Nakao and 1 other person
2 Figure 3 Figure 4 Figure f Figure 5

Claims (3)

[Claims] (1) It has a first rotary head for recording and reproducing video signals and a second rotary head with a different azimuth angle, and the audio signal is recorded overlappingly on the track where the video signal is recorded, and the heads with different azimuth angles 1. A magnetic recording and reproducing apparatus, comprising means for reproducing a video signal and an audio signal, and configured to select either frequency modulation recording or code modulation recording for recording the audio signal. (2) The audio signal recorded by the second rotary head is recorded by the first rotary head after the video signal is recorded by the first rotary head.
2. The magnetic recording and reproducing apparatus according to claim 1, wherein recording is performed at a recording level lower than the recording level of the rotary head. (3) It has a first rotary head for recording and reproducing video signals and a second rotary head with a different azimuth angle, and the audio signal is recorded overlappingly on the track where the video signal is recorded, and the heads have different azimuth angles. A means for reproducing a video signal and an audio signal is provided, and the recording of the audio signal is configured so that either frequency modulation recording or code modulation recording can be selected, and reproduction is also performed by selecting one of the modulation methods and demodulating. A magnetic recording and reproducing apparatus according to claim 1, characterized in that it is configured as follows.