JPH03230690A - Magnetic video recording and reproducing device - Google Patents

Abstract

PURPOSE:To record and reproduce a new broadcast television signal and to reproduce a video recording tape in compliance with the current standard VTR by discriminating whether a reproduction signal is a video signal by the new broadcast system or by the current broadcast system and controlling a switch in response to the result of discrimination. CONSTITUTION:A decoding circuit 15B of a transmission line decides whether or not a signal reproduced from a magnetic tape 4 is a new broadcast television signal or a current standard TV signal, turns a switch 8 to the position (p) in the case of the new broadcast TV signal and turns the switch 8 to the position (q) in the case of the current standard TV signal. As the decision method, decision is implemented depending, e.g. whether or not a resample clock is obtained from an output signal of a waveform equalizing circuit 14B. Thus, not only the video recording and reproduction of the new broadcast system signal but also the reproduction of the magnetic tape recorded by the current standard VTR is attained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a helical scan type magnetic recording and reproducing device using a magnetic tape as a recording medium, and particularly relates to a high-definition television system signal and a standard television system signal. The present invention relates to a magnetic recording/playback device that is capable of recording and playing back signals.

[Prior art] In recent years, HD technology has been introduced, which has a more detailed screen and a richer sense of reality than current standard television systems such as the NTSC and PAL systems (hereinafter referred to as the current standard TV system).
(High Definition) New television broadcasting systems (hereinafter referred to as new broadcasting systems) such as high-definition television systems have been developed, and experimental broadcasts are being conducted in some areas ahead of practical application. . Along with this, video tape recorders (hereinafter referred to as VTRs) for general home use that are compatible with this new broadcasting system have been introduced.
Development is also progressing, for example, Technical Report of the Television Society, Vol. 11. No. 24 (November 1988)
.

As described in pp. 37-42, a prototype device using a digital recording method has been announced.

[Problems to be Solved by the Invention] By the way, general household VTRs compatible with the new broadcasting system (hereinafter referred to as "new broadcasting system compatible VTRs"), including the prototype described in the above-mentioned known documents, cannot handle the signals of the new broadcasting system. (hereinafter referred to as the new broadcast TV signal) is a dedicated device for recording and reproducing signals of the current standard TV system (hereinafter referred to as the current standard TV signal). In addition, this VTR compatible with the new broadcasting system is compatible with current standards such as playing back magnetic tapes recorded by home VTRs (hereinafter referred to as current standard VTRs) that are compatible with the current standard TV system, such as VH5 standard VTR and 8 mm video. Compatibility with VTRs is not considered.

In other words, it is said that the penetration rate of current standard VTRs using the current NTSC system has already reached 70%. There are a huge number of home-made soft tapes made by people and commercially available soft tapes containing movies, etc.

Therefore, if the VTRs compatible with the new broadcasting system that will become popular in the future are not compatible with the VTRs of the current standard, general users may use VTRs compatible with the new broadcasting system instead of the VTRs of the current standard that they have been using up until now.
If you own a TR and only use it, the recorded tapes you have accumulated up to now will be completely useless, and if you try to use such recorded tapes as well, the current standard A VTR is also required. As described above, having to own a VTR for each TV system is problematic for general households in terms of installation space and economy.

The purpose of the present invention is to solve such problems and to not only record and play back new broadcasting system signals, but also to at least support the current standard VT.
An object of the present invention is to provide a magnetic recording and reproducing device which is also capable of reproducing magnetic tapes recorded using R.

[Means for Solving the Problems] In order to achieve the above object, the present invention uses a part or all of a head for reproducing a magnetic tape on which a video signal according to a new broadcasting system is recorded to reproduce video signals according to the current broadcasting system. a tape reproducing mechanism for reproducing a magnetic tape on which a video signal is recorded; a first reproducing processing means for reproducing the reproduced video signal according to the new broadcasting system; a second reproduction processing means for performing reproduction processing; a determining means for determining the type of reproduction signal of the tape reproduction mechanism;
．． and switch means for selecting one of the output video signals of the second reproduction processing means.

[Function] When a video signal according to the new broadcasting method is divided into multiple channels and recorded, multiple sets of heads are provided for playback, and one set of heads is used to record the video signal according to the current broadcasting method. When used for reproduction and a video signal according to the new broadcasting system is recorded in one channel, one set of heads is provided, by which the video signal according to the current broadcasting system is also reproduced. This allows the head to be used in common for reproducing video signals of either system.

In addition, the signal formats of the video signals according to the new broadcasting system and the video signals according to the current broadcasting system are different, and due to this difference in signal format, the playback signal is different from the video signal according to the new broadcasting system and the video signal according to the current broadcasting system. It can be determined that the first . Automatic switching of the second reproduction processing means becomes possible.

[Embodiment] The biggest factor in determining the standard of a VTR is the required band of television signals to be recorded and reproduced.

Several new broadcasting systems have been proposed as the next television signal system, but in Japan, the HDTV system with 1125 scanning lines, called the high-definition system, is the
In Europe, HD-M has 1250 scanning lines.
A C (Multiplex A analogueCo
In America, ATV (Advanced Te1) has 1050 scanning lines.
(evision) method is considered to be the most promising. In any of these methods, the video signal band must be at least 20 MHz in the camera output baseband, which is approximately five times the video signal band currently broadcast in each country. do.

However, when actually transmitting such a new broadcast system signal, the signal band must be compressed without deteriorating the image quality. For this reason, in the HDTV system, sub-Nyquist sampling is applied to the video signal to
(Multiple Sub-NyquistS
A transmission signal compressed to an 8 MHz band called an 8 MHz band is used.

Even this is approximately twice the video signal band of the current standard ITV system. For this reason, in home VTRs, MUSE
When receiving a broadcast signal, the 8 MHz band is used, and when a baseband signal is supplied from a video camera, the 2 MHz band is used.
A band of approximately 0 MHz must be assumed.

On the other hand, with respect to the recording method for VTRs, analog recording methods using FM modulation have conventionally been common, but in recent years, digital recording methods have also become popular because they cause less deterioration in image quality. For example, the MUSE signal is sampled at a frequency of 16 and 2 MHz.

If quantization is performed using 8 bits, the transmission rate is 129.6 Mbps (Mega bit per 5e).
However, if compression means such as differential PCM conversion and dynamic range adaptation are applied to this, the band can be compressed to about 18. Furthermore, during recording, data increases by about 20% due to the addition of error correction codes. Therefore, when recording the MUSE signal on a recording medium, the transmission rate is approximately 80 Mbps. However, this means that even in current standard VTRs, such as VH8 standard VTRs, the rotating head drum is moved at twice the current speed (60 rpm).
s), two two-channel multi-heads are mounted on the rotary head drum facing each other at 180 degrees, and recording is achieved by dividing the channels. In particular, if new materials such as vapor-deposited tape are used, the track width of each head can be increased by 10
It may be about μm. At this time, the current 172-inch cassette tape (tape thickness 20 μm) allows a practically sufficient recording time of about 3 hours.

In addition, when recording the MUSE signal in analog form, this MUSE signal is directly FM modulated and the carrier frequency is 15 to 20.
A one-channel video head (1
Record with two video heads facing each other at 80°, or
Alternatively, double the time axis of the MUSE signal and divide it into two systems, each with a carrier frequency of about 7 to 10 MHz.
M wave and rotate the drum at the current speed (30 rpm)
s) and recording with a two-channel multi-head. In either case, the track width of the head can be approximately 10 μm, and a practically sufficient recording time can be obtained using current cassette tapes.

When recording baseband signals in analog or digital format, it is possible to use many more types of band compression techniques, and even if the original band is as wide as 20 MHz, it is possible to obtain the same recording time as above. It is expected that

Therefore, it is quite possible to apply the mechanical system of the current standard VTR and create a VTR compatible with the new broadcasting system that is compatible with the current standard VTR. From the viewpoint of user needs, it is important that this device also has at least the function of reproducing tapes already recorded on current standard VTRs. Furthermore, even if this function is provided, it is important to avoid increasing the number of component parts as much as possible. Especially regarding the number of video heads mounted on the rotating head drum.
It is necessary to prevent it from increasing. Separate heads for playing back tapes recorded with current standard VTRs and heads for recording and playing new broadcast TV signals would not only increase costs, but also increase the difficulty of installing the heads. Moreover, this is undesirable because it causes a deterioration in the performance of the rotary transformer that transmits signals to and from the circuit system.

Furthermore, when recording and reproducing signals of the new broadcasting system and playing back tapes using the current standard VTR as described above, at least the playback system must include a circuit for reproducing and processing the new broadcast TV signal and a current standard VTR such as a VH8 standard VTR. It is necessary to have a circuit that reproduces and processes similar signals, and from the viewpoint of user convenience, it is important to be able to automatically determine which circuit should process the signal based on the reproduced signal and automatically select it. . Moreover, it is also important to determine which specific parts should be switched to optimize the operation of the apparatus based on the determination result.

Examples of the present invention that can realize the above are described below.
This will be explained using drawings.

FIG. 1 is a block diagram showing an embodiment of a magnetic recording and reproducing apparatus according to the present invention, in which 1 is an input terminal, 2 is a recording processing system, and 3
A, 3B are recording heads, 3A'3B' are playback heads, 4
is a magnetic tape, 5A and 5B are regenerative amplifiers, and 6 is a new broadcast T.
A V signal reproduction processing system 47 is a current standard TV signal reproduction processing system, 8 is a switch, 9 is an output terminal, and 10 is a sampling and quantization circuit.

11 is a high efficiency encoding circuit, 12 is a transmission line encoding circuit, 1
3A and 13B are recording amplifiers, 14A and 14B are waveform equalization circuits, 15A and 15B are transmission path decoding circuits, 16 is a code expansion decoding circuit, 17 is a D/A converter, 18 is an FM equalization circuit, and 19 is an FMS. Adjustment device, 2o is de-emphasis circuit, 2
1 is a noise reduction circuit, and 22 is an LPF (low pass filter).

23 is a frequency converter, 24 is a BPF (band pass filter), 25 is a comb filter, and 26 is an adder.

Next, the operation of this embodiment will be explained, but first.

Recording of a new broadcast signal will be explained.

In FIG. 1, a magnetic tape 4 is running and a recording head 3 is mounted on a rotating head drum (not shown).
A and 3B scan the magnetic tape 3, and the recording processing system 2 becomes operational.

The video signal of the new broadcasting method mentioned above is input from input terminal 1 to MU.
Input as SE signal or baseband signal, etc.
The signal is supplied to a sampling and quantization circuit 10. In the sampling and quantization circuit 10, when the input video signal is a MUSE signal,
For example, if the signal is a baseband signal with a quantization frequency of 16.2 MHz and a quantization bit number of 8 bits, it is quantized with a sampling frequency of 64 and 8 MHz, respectively, and a quantization bit number of 8 bits. This quantized video signal is then supplied to the high-efficiency encoding circuit 11, and the MUSE
In the case of a signal, the data rate is compressed to about 1, and in the case of a baseband signal, the data rate is compressed to about 1, and the data rate is converted by the transmission line encoding circuit 12 and an error correction code is added. The recording signal has a transmission rate of about 100 Mbps. This recording signal is divided into two channels,
After being amplified by recording amplifiers 13A and 13B, the signals are supplied to recording heads 3A and 3B and recorded on magnetic tape 4.

Next, the reproduction operation of the magnetic tape 4 on which the new broadcast TV signal has been recorded as described above will be explained.

During reproduction, the magnetic tape 4 runs, and the reproduction heads 3A' and 3B' mounted on the rotary head drum reproduce and scan the magnetic tape 4, and the reproduction amplifiers 4A and 4B
The playback processing systems 6 and 7 become operational. Note that the reproducing head 3A' may be the same as the recording head 3A, and the reproducing head 3B' may be the same as the recording head 3B.

The reproduced signals from the reproduction heads 3A' and 3B' are amplified by reproduction amplifiers 5A and 5B, respectively, and then sent to a waveform equalization circuit 14A,
14B to compensate for the frequency characteristics of the tape-head system, and further supplied to the transmission line decoding circuits 15A and 15B to correct code errors due to dropouts occurring in the tape-head system, and to compensate for the frequency characteristics of the tape-head system. is played. The output signals of these transmission line decoding circuits 15A and 15B are combined in a code expansion decoding circuit 16, and are processed in the recording side processing system 2 in the opposite manner to the high efficiency encoding circuit 11 to produce the quantized original signal. decoded into a video signal. This video signal is converted into an analog signal (MUSE signal or baseband signal) by the D/A converter 17, and after the clock component is removed, it is output from the output terminal 9 via the switch 8 closed to the p side. Output.

Next, the playback operation when the magnetic tape 4 has already been recorded with a current standard VTR will be explained.

In this case, servo is applied so that the reproducing head 3B' traces the tracks on the magnetic tape 4 correctly.

The reproduction signal from the reproduction head 3B' is amplified by the reproduction amplifier 5B and then supplied to the FM equalization circuit 18 and the LPF 22. As is well known, this reproduced signal is frequency-multiplexed with an FM-modulated luminance signal and a low-frequency conversion chromaticity signal.

First, the FM equalization circuit 18 compensates for the frequency characteristics of the reproduced signal due to the tape-head system, removes the low-frequency conversion chromaticity signal, and extracts the FM-modulated luminance signal. This luminance signal is demodulated by an FM demodulator 20. The demodulated luminance signal is given characteristics complementary to the pre-emphasis characteristics during recording in a de-emphasis circuit 20, and unnecessary components outside the band are removed.

The signal is supplied to a noise reduction circuit 21 for S/N improvement.

On the other hand, the LPF 22 extracts a low frequency converted chromaticity signal from the reproduced signal, and the frequency converter 23 corrects phase fluctuations due to jitter, etc.
It is converted into a chromaticity signal of 3.58 MHz). This chromaticity signal is passed through a BPF 24 to remove unnecessary frequency components generated due to the above frequency conversion, and then passed through a comb filter 24.
5, the magnetic tape 4 is subjected to interference removal from adjacent tracks and S/N improvement processing.

The reproduced luminance signal from the noise reduction circuit 21 and the chromaticity signal from the comb filter 25 are frequency-multiplexed by an adder 26 and then outputted from an output terminal 9 via a switch 8 closed to the q side.

In the above manner, the playback head 3B' is connected to the current standard TV.
Compatibility with current standard VTRs can be maintained by using both the magnetic tape on which signals are recorded and the magnetic tape on which new broadcast TV signals are recorded.

Here, the transmission path decoding circuit 15B determines whether the new broadcast TV signal reproduced from the magnetic tape 4 is the current standard TV signal, and when it is the new broadcast TV signal, closes the switch 8 to the p side. When the signal is a current standard TV signal, the switch 8 is closed to the q side. This determination is made, for example, by determining whether or not a sample clock can be obtained from the output signal of the waveform equalization circuit 14B, as described above.

Since the current standard TV signal is recorded in analog form, the sample clock is not recovered in the current standard TV signal that is being played back.

FIG. 2 is a diagram showing the relative positional relationship between the heads 2A and 2B in FIG. 1.

In the figure, recording heads 3A and 3B constitute one two-channel multihead.

These recording heads 3A and 3B are mounted on a rotating head drum (not shown), and although not shown in FIG.
G and 3D are recording heads 3A and 3B on the rotating head drum.
1806, respectively. Here, the recording heads 3A and 30 and the recording heads 3B and 3D are at the same height position. In addition, the recording heads 3A and 3C
The track width of all the recording heads does not necessarily have to be the same, but here, let us assume that the track width of α8 is α8, and the track width of recording heads 3B and 3D is α2.
It is set equal to m, etc. The spacing β between the recording heads 3A and 3B and the recording heads 3C and 3D may be zero, but if crosstalk from adjacent tracks becomes a problem, β≠
It may be set to 0. Further, as mentioned above, the recording heads 3A and 3C1 and the recording heads 3B and 3D must face each other at 180 degrees on the rotating head drum.
, the recording heads 3C and 3D do not necessarily have to be arranged at the same circumferential position of the rotary head drum as shown in FIG. For example, they may be separated by about 60°. The recording heads 3A, 3B, 3C, and 3D are given different azimuth angles to reduce adjacent crosstalk. Generally, this can be arbitrarily determined within a range that has an azimuth effect, but here.

Azimuth angle +6° for recording head 3B, recording head 3D
It is set to -6°. No particular provisions are made here for the recording heads 3A and 3C.

Current standard VTR1 For example, in the VH8 standard VTR standard, the recording track pitch is 58 μm in SP mode (2 hour recording mode) and 19 μm in EP mode (6 hour recording mode).
μm, and the azimuth angle of the head is +6° and -6°. therefore.

If the recording heads 3A, 3B, 3C, and 3D are configured as shown in FIG. 2, for example, it is possible to play back a recorded tape on a current standard VTR.

Moreover, since the track width of the head is 10 μm, which is narrower than the width of the recording track on the magnetic tape recorded by this current standard VTR, there is no interference from adjacent tracks, and, for example, there is no interference from adjacent tracks. Good reproduced images with less noise can be obtained.

FIG. 3 is a block diagram showing a specific example of the transmission path decoding circuit 15B in FIG. , 32 is a buffer circuit, 33 is VC○(
voltage controlled oscillator), 34 is a phase shifter, 35 is a D-FF (
36 is an error correction circuit, 37 is an output terminal, 38 is a BPF, 39 is a rectifier circuit, 40 is a detection circuit, 41 is a DC voltage source, 42 is a comparator, 43.44 is an output terminal .

In the figure, from the input terminal 27 to the waveform equalization circuit 14B (
The output signal of FIG. 1) is input. This input signal is delayed by a delay circuit 28 consisting of a shift register or the like. The output signal of this delay circuit 28 and the input signal from the input terminal 27 are supplied to an ExOR circuit 29, and a pulse is output at each rising or falling edge of this input signal. This pulse is sent to the ExOR circuit 3 along with the output pulse of ■c033.
0.

ExOR circuit 30. LPF31. Buffer circuit 32, V
CO33 constitutes a PLL (phase 0'/group). Here, if the input signal from the input terminal 1 is a digitized new broadcast TV signal, the pulse interval of the output pulse of the ExOR circuit 29 is always the same as this digital new broadcast TV signal.
The bit period of the V signal (i.e., the transmission line encoding circuit 12
(Period of the sampling clock used in Figure 1)
The VC○33 operates in synchronization with the output pulse of the ExOR circuit 29, and outputs a clock whose phase is ahead of this sampling clock by π/2 radians and whose cycle is the same as that of this sampling clock.

The output clock of this vC○33 is delayed by π Palladian in the phase shifter 34, and is supplied from the output terminal 44 to the subsequent decompression/decoding circuit 16 (Fig. 1).
5 as a clock, and the input signal supplied to its data terminal is resampled (data strobe) and supplied to the error correction circuit 36 from the Q terminal. This error correction circuit 36 corrects data errors in the input signal due to dropouts in the tape-head system, and connects the output terminal 37 to the decoding section (not shown) of the transmission line decoding circuit 14B.
is supplied to

On the other hand, the constant cycle clock (or the output clock of the phase shifter 34) from the VCO 33 is also supplied to the BPF 38. The BPF 38 has a characteristic of passing only components near the frequency of the clock output from the VCO 33 or the phase shifter 34 when the input signal is a digital new broadcast TV signal.

Therefore, this constant cycle clock passes through the BPF 38, and the rectifier circuit 39. A detection circuit 40 generates a DC voltage according to the level of the clock, and a comparator 42 compares it with a constant DC voltage from a DC voltage source 42. This comparator 4
The output of No. 2 is supplied as a switching control signal from output terminal 43 to switch 8 (FIG. 1).

When the input signal from the input terminal 27 is a digital new broadcast TV signal, the output clock of the vc○33 or the phase shifter 34 passes through the BPF 38 because its frequency is within the passband of the BPF 38, as described above. Comparator 4
The appearance level of 2 is high level. As a result, the switch 8 (FIG. 1) is switched to the p side. In contrast,
When the output signal from the input terminal 27 is an analog current standard TV signal, the output pulse of the ExOR circuit 29 has a random cycle, and the VCO 33 does not synchronize with this, which is different from when the input signal is a digital new broadcast TV signal. Generate clocks of different frequencies. Therefore, the output clock from the VCO 33 or the phase shifter 34 cannot pass through the BPF 38, the output level of the comparator 42 becomes a low level, and the switch 8 is switched to the q side.

In this way, it is automatically determined whether the signal reproduced from the magnetic tape 4 (FIG. 1) is a new broadcast TV signal or a current 11'$TV signal, and depending on the result of this determination, the switch 8
will be automatically switched, eliminating the need for any discrimination or operation by the user.

Note that instead of directly using the reproduced clock as described above, it is determined whether the PLL is locked based on whether or not there is a high frequency component in the output of the LPF 31 or the buffer circuit 32, and the switch 8 is activated based on the result of this determination. It can also be controlled.

FIG. 4 is a block diagram showing another embodiment of the magnetic recording and reproducing apparatus according to the present invention, in which 4S is an AGC (automatic gain control) circuit, 46 is a channel divider, 47A, 47B are pre-emphasis circuits, 48A, 48B is FM modulator, 49A
, 49B is an FM equalization circuit.

50A and 50B are FM demodulators, 51A and 51B are de-emphasis circuits, 52 is a channel multiplexer, and 53 is a noise reduction circuit; parts corresponding to those in FIG. 1 are given the same reference numerals and redundant explanations will be omitted. .

In the figure, for example, MU input from input terminal 1
The SE signal is set at a constant level by the AGC circuit 45, and is divided into two channels by alternating, for example, every scanning line by the channel divider 46, and the time axis is expanded, so that the frequency band of each channel becomes 172. You can get the signal of the channel. After the high frequencies of each channel signal are emphasized by pre-emphasis circuits 47A and 47B,
The signal is FM modulated by FM modulators 48A and 48B, amplified by recording amplifiers 13A and 13B, and sent to recording head 3A.

3B and recorded on the magnetic tape 4.

When reproducing the magnetic tape 4 on which the new broadcast TV signal is recorded as described above, the respective channel signals reproduced from the magnetic tape 4 by the reproducing head 3A'3B' are amplified by the reproducing amplifiers 5A and 5B. Thereafter, the signal is processed by FM equalization circuits 49A, 49B, FM demodulators 50A, 50B, and de-emphasis circuits 51A, 51B, and an FM demodulated two-channel signal is obtained. These processes are carried out by the FM equalization circuit 18 in the current standard TV signal reproduction processing system 7. F
M demodulator 19. This is similar to the processing performed by the de-emphasis circuit 2o, but the only difference is the characteristics. Also, F
Unlike the FM equalization circuit 18, the M equalization circuits 49A and 49B do not have a function of removing low-frequency converted chromaticity signals.

The respective channel signals outputted from the de-emphasis circuits 51A and 51B are supplied to the channel multiplexer 52, each of which is compressed twice in the time axis and added.
I get a signal. This MUSE signal undergoes noise removal processing in a noise reduction circuit 53, passes through a switch 8 closed to the P side, and is outputted from an output terminal 9.

Current mark 1! When reproducing the magnetic tape 4 on which the TV signal is recorded, the switch 8 is switched to the q side, and the reproducing processing system 7 operates in the same manner as in the embodiment shown in FIG.

The switching of the switch 8 is performed by detecting whether or not a low frequency conversion chromaticity signal exists in the frequency converter 23 to determine whether the reproduced signal is a new broadcast TV signal or a current standard TV signal. This is done by This allows automatic switching of the switch 8.

FIG. 5 is a block diagram showing a specific example of the frequency conversion 1!23 in FIG.
power terminal, 57 is a balanced modulation circuit, 58 is ■X○ (voltage controlled crystal oscillator), 59 is a phase comparator, 60 is an output terminal, 6
1 is an input terminal.

In the same figure, the low frequency conversion chromaticity signal of the current standard TV signal separated by the LPF 22 is input to the input terminal 54. This low frequency converted chromaticity signal is detected by a detection circuit consisting of a transistor Ql and a capacitor C1, and a transistor Q2
．． Q3. A comparator consisting of resistors R1°R2 sets the reference voltage E1.
The level is compared with. The output of this comparator is the inverter 5
5, the level is inverted at step 5, and the signal is output as a switching control signal from output terminal 56 and supplied to switch 8.

Here, the low-pass conversion chromaticity signal is unique to the recording signal of the current standard and does not exist in the recording signal of the new broadcasting system, so the switching control signal obtained at the output terminal 56 is The level is low when the signal is a standard TV signal, and the level is high when the signal is a new broadcast TV signal. This causes switch 8
is automatically switched depending on the type of playback signal.

On the other hand, the low-pass converted chromaticity signal inputted from the input terminal 54 is also supplied to the balanced modulation circuit 57, and is returned to the original chromaticity subcarrier frequency band (NTS
In the case of the C method, the frequency is band-converted to around 3.58 MHz), output from the output terminal 60, and supplied to the BPF 24 (FIG. 4).

Note that the phase of the converted subcarrier generated by the VXO58 is
As is well known, the phase of the burst signal obtained at the output terminal 60 is controlled by the output of the phase comparator 59, which compares the phases, so that the phase of the burst signal obtained at the output terminal 60 matches the phase of the reference signal of the chromaticity subcarrier frequency supplied from the input terminal 61. has been done.

FIG. 6 is a block diagram showing another specific example of the frequency converter 23 in FIG. 4, 62 is an output terminal, and parts corresponding to those in FIG. Omitted.

In this specific example, the balanced modulation circuit 57. It determines whether the reproduced signal is a current standard TV signal or a new broadcast TV signal depending on whether the PLL consisting of the VX○58° phase comparator 59 is locked or not, and the signal representing the determination result is used for switching control. A signal is supplied from the output terminal 62 to the switch 8 (FIG. 4).

That is, it may be a known color killer signal (a signal that becomes high level when the PLL does not lock, assuming that there is no low-frequency conversion chromaticity signal), and by driving the switch 7 with this signal, the desired purpose can be achieved. can be achieved.

FIG. 7 is a block diagram showing still another embodiment of the magnetic recording and reproducing apparatus according to the present invention, 63 is a discrimination circuit, and parts corresponding to those in FIG. is attached.

In this figure, a new broadcast TV signal is recorded and reproduced as a one-channel signal, and therefore, in the embodiment of FIG. 4, a channel splitter 46. Pre-emphasis circuit 47A, FM modulator 48A, recording amplifier 13A, recording head 3A, reproduction head 3A', reproduction amplifier 5A, FM equalization circuit 49A, FM demodulator 50A, de-emphasis circuit 51A, and channel multiplexer 52 are excluded. It has the same configuration as the one. Therefore, the recording and reproducing operations of this embodiment are also similar to those of the embodiment shown in FIG.

However, in this embodiment, the output signal of the noise reduction circuit 53 determines whether the reproduced signal is a new broadcast TV signal or not.
A determination circuit 63 is provided to determine whether the signal is a current standard TV signal, and the switch 8 is controlled based on the output of this determination.

The recording head and the reproducing head need only one channel, and as shown in FIG. 8, the recording head 3B,
3D is installed.

Azimuth angle of recording head 3B is +6°, recording head 3D
If the azimuth angle of is -6@, then Figure 1.

Similar to the embodiment shown in FIG. 4, it is also possible to reproduce video signals from a magnetic tape that has already been recorded with a current standard VTR.

The same applies to the reproducing head 3B', but it goes without saying that the recording head and the reproducing head may be used in common.

FIG. 9 is a circuit diagram showing a specific example of the discrimination circuit 63 in FIG. 7, in which 64 is an input terminal, 65 is a non-inverting buffer, and 66 is an output terminal.

This specific example is a case where a new broadcast TV signal such as a MUSE signal is directly FM modulated and recorded and reproduced.

As is well known, the MUSE signal does not have a negative polarity synchronization signal (an amplitude separable synchronization signal with a polarity opposite to that of the video part of the video signal) like the current NTSC video signal, but only within the amplitude range of the video signal. It has a positive synchronization signal. Therefore, by detecting whether or not the amplitude of the negative synchronization signal can be separated, it is possible to determine whether the signal is a new broadcast TV signal or a current standard TV signal.

In FIG. 9, the luminance signal output from the noise reduction circuit 53 (FIG. 7) is input from the input terminal 64. This luminance signal is supplied to a peak clamp circuit consisting of a capacitor C2 and a transistor Q4, and the portion of the luminance signal with the lowest DC potential is clamped to a potential lower than the DC voltage E2 by the base-emitter voltage of the transistor Q4. In the luminance signal of the current NTSC system, the leading edge of the negative synchronization signal is clamped to the above potential, and in the case of the MUSE signal, the lowest level of the video is clamped to the above potential.

The luminance signal clamped in this way is transferred to the transistor Q
5. It is supplied to a comparator consisting of Q6 and resistors R3 and R4, and is compared in level with a DC voltage E3 having a potential higher than the clamp potential within the level of the negative synchronizing signal supplied to the base of transistor Q6. As a result of this comparison, the emitter output of the emitter follower consisting of the transistor Q7 and the resistor R6 is at a high level only during the synchronization signal period when the current NTSC luminance signal is input.
When the MUSE signal is input, the level is almost uniformly high throughout the entire period. The emitter output of this emitter follower is converted into a direct current by an LPF consisting of a resistor R5 and a capacitor C3, and is supplied as a switching control signal from an output terminal 66 to a switch (FIG. 7) via a non-inverting buffer 65. This switching control signal is at a high level when a MUSE signal is input, and is at a low level when a brightness signal of the current NTSC system is input. toggle.

FIG. 10 is a block diagram showing another specific example of the discrimination circuit 63 in FIG.
71 is an AND circuit, 71 is a latch circuit, and 72 is an output terminal.

This is for recording by adding a negative synchronization signal to the MUSE signal or baseband signal. A negative synchronization signal with a time @TN of approximately 4 μsec is added to the current NTSC luminance signal, but in new broadcast TV signals, the horizontal blanking period is short, so even if a negative synchronization signal is added, the time is The width TM is approximately 1 μSeC.

This specific example is for a case where a negative synchronization signal is added to the new broadcast TV signal as well, and the type of reproduced signal is determined based on the difference in time width of the negative synchronization signal.

In FIG. 10, a reproduction signal is input from an input terminal 67, and a negative synchronization separation circuit 68 separates a synchronization pulse in which only the negative synchronization signal is at a high level.

This negative polarity synchronous separation circuit 68 includes, for example, a clamp circuit formed of capacitor C2 and transistor Q4 in FIG. 9, transistor Q7, and so on. The circuit configuration up to the emitter follower formed with the resistor R6 may be the same.

The separated high level synchronization pulse is supplied to the positive edge trigger terminal of the monostable multivibrator 69 and the AND circuit 70. The time constant τ of the monostable multivibrator 69 is chosen such that T M <τ<TN.

The ζ output of this monostable multivibrator 69 is supplied to an AND circuit 70.

Therefore, the output of the AND circuit 70 is the current NTSC
When the brightness signal of the system is input, the pulse becomes high level every horizontal period, and when the new broadcast TV signal is input, the pulse becomes low level all the time. This AND circuit 70
The output of the output terminal 72 is latched and inverted by the latch circuit 71ρ.
In this case, a switching control signal similar to that of the specific example shown in FIG. 9 is obtained.

FIG. 11 is a block diagram showing still another specific example of the discrimination circuit 63 in FIG.
75 and 76 are detection circuits, and 77 is a comparator, and parts corresponding to those in FIG. 10 are given the same reference numerals and redundant explanations will be omitted.

This specific example is also for recording and reproducing by adding a negative synchronization signal to the new broadcast TV signal. The negative sync frequency of the TV signal is 33
．． This takes advantage of the difference from 75kHz.

In FIG. 11, the synchronization pulses output from the negative synchronization separation circuit 68 are supplied to BPFs 73 and 74, but these BPFs 73 and 74 have different passbands, and the new broadcast TV output from the negative synchronization separation circuit 68 is The synchronization pulse of the signal passes through the BPF 73, is detected by the detection circuit 75, and is then supplied to the comparator 77. The synchronization pulse of the current standard TV signal output from the negative polarity sync separation circuit 68 passes through the BPF 74.
The signal is detected by a detection circuit 76 and supplied to a comparator 77 . The output of the comparator 72 is supplied as a switching control signal from the output terminal 72 to the switch 8 (FIG. 7).

Here, when a new broadcast TV signal is input from the input terminal 67, a high level DC voltage is output from the detection circuit 75, so that the switching control signal obtained at the output terminal 72 is at a high level. Current standard TV from terminal 67
When a signal is input, a high level DC voltage is output from the detection circuit 76, and the switching control signal becomes low level.

In addition, new broadcast T such as MUSE signal and baseband signal
If a V signal is recorded and played back at a tape-head relative speed twice that of the current standard TV signal such as the current NTSC system, the playback synchronization frequencies will be close to each other when played back at a constant speed. However, since the synchronization frequency of the original signal is not in an exact double-half relationship, it is possible to determine it.

In addition to the discrimination using these synchronization signals, the discrimination can also be made by detecting the presence or absence of a burst signal for time axis correction using the discrimination circuit 63. This is because this burst signal is unique when recording and playing back new broadcast TV signals, and in many cases it is added to the back porch of the horizontal synchronization signal, so it is not possible to separate it based on its timing. You can judge by.

In addition, in FIGS. 1 and 7, the switching control signal for the switch 8 may be generated by the frequency converter 23 as in the embodiment shown in FIG. , a discrimination circuit 63 may be provided as in the embodiment shown in FIG. 7 to discriminate the output luminance signal of the noise reduction circuit 21 to form a switching control signal for the switch 8; In the figure, the switching control signal for the switch 8 may be formed by determining the output luminance signal of the noise reduction circuit 53 or 21.

The above embodiments were intended only for the playback of video signals for pre-recorded tapes using current standard VTRs; however,
It goes without saying that the audio signal can also be played back at the same time on a tape recorded by a VTR, such as 8mm video, Beta Hi-Fi, etc., in which the audio signal is frequency-multiplexed with the video signal and recorded.

However, in VHS high-fidelity VTRs and the like, as is well known, audio signals are recorded deep into the magnetic tape using heads with different azimuth angles (30').

In this case, in the above embodiment, it is not possible to reproduce the audio signal recorded in the deep layer. An embodiment of the present invention that solves this problem will be described next.

FIG. 12 is a block diagram showing such an embodiment of the magnetic recording and reproducing apparatus according to the present invention, in which 78A and 78A' are variable elements, 79 is a reproduction audio processing system, 80 is a BPF, 81 is an FM demodulator, and 82 is a The noise reduction circuit includes an output terminal 83, a detection circuit 84, and an AND circuit 85. Parts corresponding to those in FIG.

In the figure, a recording head 3A and a reproducing head 3A' are
Each is attached to a movable element such as a bimorph plate or a voice coil, and the height of the attachment is made variable. A reproduction audio processing system 79 is also provided, and the recording head 3A.

By limiting the azimuth angle of the reproducing head 3A'' to 30', deep recorded audio signals can also be reproduced from a tape recorded by a VHS high-fidelity VTR.

When the magnetic tape 4 is a tape recorded by this VHS high-fidelity VTR, the mounting height of the reproducing head 3A' is changed by the variable element 78A', and is used for reproducing deep recorded audio signals.

Here, since the video signal reproduction processing is the same as that in the embodiment shown in FIG. 1, its explanation will be omitted.

The audio signal reproduced by the reproduction head 3A' is reproduced by reproduction amplification 1.
After being amplified by 15A, it is supplied to BPF80 and the audio F
Unnecessary signals outside the M signal band are removed, the FM demodulator 82 returns the signal to a baseband audio signal, the noise reduction circuit 82 improves the S/N, and the signal is output from the output terminal 83.

As described above, compatible playback of not only video signals but also audio signals is possible.

Furthermore, the audio FM signal output from the BPF 80 is detected by a detection circuit 84, and the level of the detection output is inverted.
The signal is supplied to the ND circuit 85. This AND circuit 85 has
A determination signal indicating the presence or absence of clock recovery from the transmission line decoding circuit 15 shown in FIGS. 1 and 3 is also supplied, and a switching control signal for the switch 8 is output from the AND circuit 85.

The method of recording audio signals by FM modulating them is described in 'IIA V.
Although it is used in HS high-fidelity VTRs, it is thought that new broadcasting systems such as high-definition will use digital recording. Therefore, it is thought that the audio FM modulation signal does not exist on the magnetic tape on which the new broadcast TV signal was recorded, and by determining this together with the result of detecting the clock reproduction described above, the reliability of the switching operation of the switch 8 is further increased. do.

In addition, it is also conceivable to switch the switch 7 based on whether a signal based on the audio recording standard of the new broadcast TV signal can be detected. In this case, a method such as detecting and determining whether a unique clock of the audio signal can be reproduced may be used.

Next, the recording head 3A and the reproducing head 3 in FIG.
A', assuming that the recording head 3B and the reproducing head 3B' are the same head, the positions of the heads to be attached according to the signals recorded on the magnetic tape 4 or recorded will be explained with reference to FIG.

On a rotating drum (not shown), a head 3A with an azimuth angle of 130' mounted on a variable element 78A and a variable element 78
The head 3C mounted on C with an azimuth angle of +30' is placed 18o opposite to the head 3C at the same mounting height.
Head 3B with azimuth angle of +6″ and azimuth angle of 16°
The heads 3D are fixedly arranged at the same mounting height and facing each other by 180 degrees. Furthermore, in order to be able to change the mounting height of the heads 3A and 3C,
With respect to C, the heads 3B and 3D are shifted by 60° in the circumferential direction of the rotary head drum.

First, when recording and reproducing a new broadcast TV signal, the heads 3A and 3B and the heads 3C and 3D are connected to each other as shown in FIG. 13(a), just as in the embodiment shown in FIG. The magnetic tape 4 is mounted at different heights, and recording signals from each head are recorded and reproduced on tracks separated from each other. The azimuth angles of the heads 3B and 3D are 6 degrees, and the azimuth angles of the heads 3A and 3C are 30', so a sufficient azimuth effect can be expected, so the heads 3A and 3B.

The spacing β between the traces of the heads 3C and 3D may be zero. β=0. Each head 3 on the magnetic tape 4 in the case of guard panless recording with head track width = 10 μm
The scanning trajectories A to 3D are shown in FIG. 14(a) using track pattern coordinates.

When playing a recorded tape recorded by a current standard VTR,
The installation height of heads 3A and 3C is different.

It is changed by movable elements 78A and 78C.

First, when playing back a tape recorded in SP mode (track pitch = 58 μm) on a VHS high-fidelity VTR, the audio signal is compared to the video signal at the same point on the magnetic tape 4 at 0 to 18 digits. Since the data are recorded in front of each other and in opposite azimuths to each other, as shown in Fig. 13 (
As shown in b).

The head 3A with an azimuth angle of -30° is moved to a position where it can scan the same recording track as the head 3B with an azimuth angle of +66, and the head 3A reproduces the audio signal and the head 3B reproduces the video signal. The scanning locus of each head at this time is
4 (b).

Also, when playing back a tape recorded in EP mode (track pitch = 19 μm) with a VHS high-fidelity VTR, the audio signal is different from the video signal.

At the same point on the magnetic tape, 11 to 318 fields are recorded in advance and in the same azimuth direction, so as shown in FIG. is moved to a position where it can scan the same recording track as head 3D with an azimuth angle of -6 degrees, and head 3A plays back the audio signal and head 3D plays the video signal.In the EP mode, as described above, At the same point on the magnetic tape 4, the audio signal precedes the video signal by about two fields, so the head 3A is located above the heads 3D and 3B, that is, temporally, as shown in FIG. It is desirable to move to the track position following the head.The scanning locus of each head at this time is shown in Fig. 14 (c).
).

Furthermore, since the audio signal is recorded before the video signal, as shown in FIGS. In this case, it is preferable to place the heads 3A, 3C that reproduce audio signals at a position where they scan ahead of the heads 3B, 3D that reproduce video signals, in order to bring the reproduction timings of both sides closer together.

In addition, in FIGS. 4 and 7, VHS
It is also possible to make the audio compatible with a high-fidelity VTR.

Next, a method of connecting the reproducing head and the reproducing amplifier in FIGS. 1, 4, 7, and 12 will be explained.

When playing back a recorded tape of a current standard VTR, the frequency band of the playback amplifier 5B is 10MHz for the video signal.
However, new broadcast TV signals require a wider range of about 20 MHz. In the case of the present invention,
If you set it to around 20MHz, there will be no problem with basic functionality, but when playing recorded tapes with current standard VTRs, the band of the playback amplification amount of 5B is unnecessarily wide, so amplifier noise becomes a problem. This will degrade the S/N.

Also, the regenerative amplifier 5A in FIG. 12 may amplify the audio signal, and in this case, the frequency band is 2M.
Hz is also fine.

From the above, it is desirable to change the frequency band of the reproducing amplifier depending on the content of the tape to be reproduced.

FIG. 15 is a diagram showing a specific example of how to connect the reproducing head and reproducing amplifier in FIGS. 1, 4, and 7, in which 86A and 86B are rotary transformers, 87 is a switch, and 88 is a step-up. The transformer 89 is an input terminal, and parts corresponding to those in the above drawings are given the same reference numerals.

In the figure, first, when reproducing the magnetic tape 4 on which the new broadcast TV signal is recorded, the reproduction signal of the reproduction head 3A' is transmitted to the reproduction amplifier 5A via the rotary transformer 86A.
The playback signal from the playback head 3B' is supplied to the playback head 3B' via a rotary transformer 86B, and the switch 8 is closed as shown in the figure.
7 and is supplied to the regenerative amplifier 5B.

When reproducing a magnetic tape recorded on a current standard VTR, the switch 87 is switched in the opposite direction from that shown in the figure in response to a switching control signal from an input terminal 89. As this switching control signal, the switching control signal of the switch 8 described above can be used. The reproduction signal from the reproduction head 3B' is supplied to the reproduction amplifier 5B via a rotary transformer 86B and a step-up transformer 88, and a switch 87.

The turns ratio of rotary transformers 86A and 86B is.

When the connection of switch 87 is shown, the frequency band is selected to be, for example, 20 MHz. In reality, the ratio is often 1:1. At this time, if the turn ratio of the step-up transformer 88 is 1;2, for example, the frequency band on the head 3B' side when the switch 87 is connected in the opposite direction as shown in the figure is approximately 10 MHz, and the frequency band of the input to the regenerative amplifier 5B is approximately 10 MHz. Since the level increases by a factor of 2, the S/
N also increases by 6 dB, and the above-mentioned inconvenience can be solved.

FIG. 16 is a diagram showing a specific example of a method of connecting the reproducing head and the reproducing amplifier in FIG. Reference signs are added to omit redundant explanations.

In the figure, when playing back the magnetic tape 4 on which new broadcast TV signals are recorded, the switch 90 is closed as shown, and when playing back a recorded tape using a current standard VTR such as a VHS high-fidelity VTR, the switch 90 is closed. 90 closes on the opposite side from that shown.

When reproducing the magnetic tape 4 on which the new broadcast TV signal is recorded, it is similar to the specific example shown in FIG.
When playing back a recording tape recorded by an S high-fidelity VTR, an audio signal is played back by the playback head 3A'.
This audio signal passes through a rotary transformer 86A, a step-up transformer 91, and a switch 90, and is supplied to the regenerative amplifier 5A. The reproduction of the video signal in this case is similar to the specific example shown in FIG.

In this specific example, when an audio signal is supplied to the regenerative amplifier 5A via the step-up transformer 91, the transmission band only needs to be about 2 MHz.

Therefore, the turns ratio of the step-up transformer 91 is 1
:8, which can be larger than the step-up transformer 88 in the video signal transmission path, and the S/N ratio against amplifier noise can be further improved.

Note that in FIGS. 15 and 16, the rotary transformers 86A and 86B are arranged between the reproducing head 3A'3B' and the regenerative amplifiers 5A and 5B, respectively. , regenerative amplifiers 5A, 5B,
Step up transformer 91.88. switch 90.8
7 may be mounted on a rotating drum.

Further, the switching control signal from the input terminal 89 that controls the switch 90.87 may be the same as the switching control signal that controls the switch 8 in the previous embodiment. That is, if the switch 90.87 is closed in the direction shown when the switching control signal is at a high level, and closed in the opposite direction when the switching control signal is at a low level, the playback signal from the magnetic tape 4 can be processed optimally. can be applied automatically.

Although the embodiments of the present invention have been described above, the present invention is not limited only to these embodiments.

That is, in the above embodiment, compatibility with a VH5 standard VTR was mainly explained, but this is not a limiting condition. The point is to make it possible to play back recorded tapes of current standard VTRs using the same head.

Further, although the number of channels of the multihead is set to 2 or 1, this is not a limitation on the present invention. Of the three or more channels, two or one channel may be selected to perform the above operation.

Furthermore, although we have only explained the playback function for the current standard TV signal, this is the minimum necessary function, and
Needless to say, it may also be provided with a recording function.

Furthermore, in FIGS. 12 and 13, the head mounted on the movable element is a head with an azimuth angle of 30', but it may be a head with an azimuth angle of 6°,
Moreover, both may be sufficient.

Note that if the track width of these heads is extremely narrow, for example, 1 μm or less, the above objective may be achieved without changing the mounting height of these heads.
In this case, the head may be fixed without providing a movable element.

Furthermore, in the above embodiment, the current standard TV signal is converted to NTSC.
However, it is also possible to use PAL or SECAM; in this case, HD-MA will be used as the new broadcast TV signal.
It may be a C method or the like.

Furthermore, although we have only shown that the video signal circuit is switched using the automatic discrimination results of the playback signal, other means such as the number of rotations of the rotating head drum, the running speed of the magnetic tape, and the operation display on the display panel can be used as necessary. All you have to do is switch.

Furthermore, when recording a new broadcast TV signal, the shape and size of the tape cassette may be different from the tape cassette used in the current standard VTR.

If new protrusions, identification holes, etc. are provided on the tape cassette, a switch may be activated by detecting these.

[Effects of the Invention] As explained above, according to the present invention, it becomes possible to record and playback new broadcast TV signals as well as playback recorded tapes using the current standard VTR, eliminating the need for the current standard VTR, and furthermore, allowing the current standard VTR to be used. Tapes recorded in the past will no longer be wasted because they cannot be played back, and the signal format recorded on the magnetic tape being used will be automatically determined and the optimal processing will be performed on the playback signals. This eliminates the need for the user to perform complicated operations.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the magnetic recording/reproducing apparatus according to the present invention, FIG. 2 is a diagram showing the relative positional relationship of the heads in FIG. 1, and FIG. 3 is a transmission path decoding diagram in FIG. 1. FIG. 4 is a block diagram showing a specific example of the circuit, FIG. 4 is a block diagram showing another embodiment of the magnetic recording/reproducing apparatus according to the present invention, and FIGS. 5 and 6 are specific examples of the frequency converter shown in FIG. 4. FIG. 7 is a configuration diagram showing still another embodiment of the magnetic recording/reproducing apparatus according to the present invention, FIG. 8 is a diagram showing the relative positional relationship of the heads in FIG. 7, and FIGS. 1st
1 is a block diagram showing a specific example of the discrimination circuit in FIG. 7, FIG. 12 is a block diagram showing still another embodiment of the magnetic recording/playback device according to the present invention, and FIG. 13 is a block diagram showing a specific example of the discrimination circuit in FIG. 12. Figure 1 showing the positional relationship of each head for each type of
FIG. 4 is a diagram showing the head scanning locus on the magnetic tape for each head positional relationship shown in FIG. 13, and FIG. FIG. 16 shows a specific example of the connection circuit between the read head and the regenerative amplifier in the embodiment shown in FIG. 12. It is a diagram. 1...Input terminal for video signal of new broadcasting system, 2
... Recording processing system, 3A, 3B... Recording head, 3A', 3B'... Playback head, 4
. . . Magnetic tape, 6 . . . Reproduction processing system for reproducing video signals of the new broadcasting system, 7 . . . Reproduction processing system for reproducing video signals of the current standard broadcasting system, 8.・・・・・・
・Switch, 9... Output terminal for reproduced video signal, 15... Transmission line decoding circuit, 23...
Frequency converter, 63...Discrimination circuit, 78A, 7
8A'...Variable element, 79...Reproduction processing system for reproduced audio signal, 83...Output terminal for reproduced audio signal, 84...Detection circuit, 85...
・AND circuit. Figure 2 Figure Figure Figure 7 Figure 2 3 4 5 Figure B Figure ○ Figure Figure 13 (a) (C) 22:=:==:〉 Figure 1 F4-1t /f

Claims (1)

[Claims] A magnetic tape that is divided into 1 and N (where N is an integer of 2 or more) channels and on which a video signal according to a new broadcasting system is recorded is reproduced by N sets of heads; a tape reproducing mechanism for reproducing a video signal from a magnetic tape on which a video signal according to the current broadcasting system is recorded in a channel using a first specific head of one set of the N sets of heads; a first reproduction processing means for reproducing the video signal; a second reproduction processing means for reproducing the reproduced video signal according to the current broadcasting system; a discriminating means for discriminating whether the signal is a video signal according to the current broadcasting system, and one of the output video signals of the first and second reproduction processing means is selected according to the discriminating result of the discriminating means. 1. A magnetic recording and reproducing apparatus, comprising a first switch means configured to enable reproduction of video signals according to a new broadcasting system and a current broadcasting system. 2. In claim 1, n_1( to which the reproduction signal of the first specific head is supplied)
>1) A step-up transformer with a double step ratio, and selecting the playback signal of the first specific head when playing back a magnetic tape on which a video signal according to the new broadcasting system is recorded, and a step-up transformer having a double step ratio; and a second switch means for selecting a reproduction signal of the first specific head outputted from the step-up transformer and supplying the selected reproduction signal to a reproduction amplifier, respectively, when reproducing a magnetic tape on which is recorded. magnetic recording and playback device. 3. In claim 1, the magnetic tape on which the video signal according to the current broadcasting system is recorded further has an audio signal recorded in a deep part of the magnetic tape parallel to the recording track of the video signal,
The tape reproducing mechanism reproduces the audio signal using a set of second specific heads other than the first specific head among the N sets of heads, and includes audio reproduction processing means for reproducing the reproduced audio signal. A magnetic recording and reproducing device characterized by being provided with. 4. The magnetic tape according to claim 3, further comprising a movable means for changing the mounting height of one of the first and second specific heads on the rotating drum, and on which a video signal according to the new broadcasting system is recorded. During playback, the N sets of heads respectively play back and scan the recording tracks of each channel on the magnetic tape, and the video signal according to the current broadcasting system is recorded in the shallow layer, and the audio signal is recorded in the deep layer. A magnetic recording and reproducing apparatus characterized in that the first and second specific heads are configured to separately scan the recording track of the video signal and the recording track of the audio signal when reproducing the magnetic tape. . 5. In claim 4, the video signal according to the current broadcasting system and the audio signal are recorded in a first recording mode at a first tape speed or in a second recording mode at a second tape speed lower than the first tape speed. When reproducing the magnetic tape in the first recording mode, the recording track of the audio signal is reproduced by the first specific head that scans and reproduces the recording track of the video signal. Said second
When the specific head is positioned within 1/2 field in advance, and when reproducing the magnetic tape in the second recording mode, the second specific head is positioned approximately 2 fields ahead of the first specific head. A magnetic recording and reproducing device characterized in that it is located as follows. 6. In claim 3, 4 or 5, n_1(
>1) A first step-up transformer with a step-up ratio of 1) and n_2( to which the reproduction signal of the second specific head is supplied)
>1) A second step-up transformer with a double step-up ratio, and selecting the reproduction signal of the first specific head when reproducing the magnetic tape on which the video signal according to the new broadcasting method is recorded, and selecting the reproduction signal of the first specific head, When reproducing a magnetic tape on which a video signal is recorded according to the method, a second reproducing signal for selecting the first specific head outputted from the first step-up transformer and supplying the reproduced signal to the first reproducing amplifier, respectively. a switch means for selecting a reproduction signal of the second specific head when reproducing a magnetic tape on which a video signal according to the new broadcasting system is recorded, and reproducing a magnetic tape on which a video signal according to the current broadcasting system is recorded; and a third switch means for selecting the reproduction signal of the second specific head output from the second step-up transformer and supplying the selected reproduction signal to the respective second reproduction amplifiers. playback device. 7. The magnetic recording and reproducing device according to claim 6, characterized in that n_2>n_1. 8. Claim 3, 4, 6 or 7, wherein the determining means makes the determination by detecting whether or not the reproduced signal of the second specific head is an audio signal. magnetic recording and playback device. 9. Claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein the video signal according to the new broadcasting system is digitized and recorded on the magnetic tape, and the video signal according to the current broadcasting system is frequency modulated. 1. A magnetic recording and reproducing apparatus, characterized in that a multiplexed signal of a converted luminance signal and a low frequency converted chromaticity signal is recorded on the magnetic tape. 10. The magnetic recording and reproducing apparatus according to claim 9, wherein the determining means makes the determination based on whether or not a digital clock of a fixed period can be reproduced from the reproduction signal by the tape reproducing mechanism. 11. A magnetic tape with one set of heads, on which the video signal according to the new broadcasting system is frequency-modulated and recorded in one channel, and the video signal according to the current broadcasting system is frequency-modulated with a luminance signal and low-frequency conversion color. a tape reproducing mechanism for reproducing a magnetic tape recorded as a multiplexed signal with a video signal; a first reproducing processing means for reproducing the reproduced video signal according to the new broadcasting method; a second reproduction processing means for reproducing a video signal according to the system; and a determining means for determining whether a signal reproduced by the tape reproduction mechanism is a video signal according to the new broadcasting system or a video signal according to the current broadcasting system. , a switch means for selecting one of the output video signals of the first and second reproduction processing means according to the determination result of the determination means, and a switch means for selecting one of the output video signals of the first and second reproduction processing means, and the switch means selects one of the video signals output from the first and second reproduction processing means, and the video signal according to the new broadcasting system and the current broadcasting system is selected. A magnetic recording/playback device characterized in that it is configured to enable playback. 12. In claim 11, the video signal according to the new broadcasting system has a horizontal scanning period different from that of the video signal according to the current broadcasting system, and a negative synchronization signal is added to each horizontal scanning period, and the discriminating means comprises: , a magnetic recording and reproducing apparatus characterized in that the determination is made based on a difference in the period of a negative synchronizing signal of the video signal processed by the first or second reproduction processing means. 13. In claim 11, the video signal according to the new broadcasting system is added with a negative synchronization signal having a different time width from the negative synchronization signal of the video signal according to the current broadcasting system for each horizontal scanning period, and the discriminating means The magnetic recording and reproducing apparatus is characterized in that the determination is made based on a difference in the time width of the negative synchronization signal of the video signal processed by the first or second reproduction processing means. 14. The magnetic recording and reproducing device according to claim 9 or 11, wherein the determining means performs the determining based on whether or not the low-frequency converted chromaticity signal can be separated from the signal reproduced by the tape reproducing mechanism. Device. 15. In claim 9 or 11, the discrimination means performs the discrimination based on whether or not burst detection means for frequency converting the low frequency converted chromaticity signal to a high frequency band detects a burst signal. A magnetic recording and playback device featuring: 16. Claim 9 or 11, characterized in that the discrimination means makes the discrimination based on whether or not a negative synchronization signal is detected from the video signal processed by the second reproduction processing means. Magnetic recording and playback device.