JPH0273790A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To automatically discriminate the existing TV system and the HDTV system by reproducing the recording tape of the existing TV system and the recording tape of the HDTV system in any reproduction mode. CONSTITUTION:Both the tape recorded by the existing system and the system corresponding to the HDTV system are reproduced by either system at reproduction. In this case, the frequency of the horizontal synchronizing signal of a reproduction signal obtained from the tape recorded by the existing system is nearly 63kHz because its spectrum is shifted toward high frequencies by 4 times that at the recording, while the horizontal synchronizing signal frequency of the HDTV system is 33.75kHz. Thus, the frequency or the difference from the frequency is discriminated and the reproduction signal processing system and the drive speed mode of a disk motor 5 and a capstan motor 7 are selected to discriminate the two systems automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing device, and particularly to a magnetic recording and reproducing device suitable for recording and reproducing two or more information signal inputs.

[Conventional technology]

As a television broadcasting system, a high-definition television system has been developed in which the number of scanning lines in one frame is 1125, approximately twice the current 525 (NTSC). Hereinafter, this method will be referred to as HD TV (Illight Defini-ti
on TV) method.

To transmit HDTV signals as broadcast signals.

The baseband requires a transmission band exceeding 20 MHz, and the most promising transmission method for broadcasting such wideband signals in high quality nationwide is to transmit FM signals via satellite. .

Book I (Bandwidth compression is essential for transmitting D TV signals in one channel. In this way, H
As an example of technology for transmitting DTV signals.

There is the MUSE method developed and announced by NIIK.

If HDTV broadcasting based on the MUSE system comes to be carried out via a broadcasting satellite, it is assumed that the current broadcasting system and HDTV broadcasting will be carried out simultaneously.

At present, a single VTR capable of supporting both the current system broadcasting and HDTV system broadcasting as described above has not been realized.

If we consider a VTR capable of recording and reproducing both current broadcasting and HD TV broadcasting, a switch is required to switch the signal processing mode. If such a switch is provided and configured to be operated manually, the operation will be cumbersome.

In order to deal with this situation, a VTV system that automatically determines and plays back current system broadcast recordings and HD TV system recordings is available.
We suggest TR.

As applicable to this, on the same magnetic tape,
There is a determination of the presence or absence of FM audio in a HiFi VTR that records two types of FM modulated signals (video and audio).

Regarding this, please refer to Japanese Patent Publication No. 61-36283, Japanese Patent Publication No. 5
No. 8-114678 is mentioned.

[Problem to be solved by the invention]

In the above conventional technology, since the carrier frequency for video signal modulation and that for audio signal modulation are clearly determined, FM
Even in a six-line VTR in which the presence or absence of audio can be easily determined based on the signal level of the carrier frequency, a method can be considered in which the difference between the FM modulation carrier frequencies of both methods is utilized to determine the presence or absence of both methods.

The frequency allocation at this time is shown in FIG.

On the other hand, in order to realize an HDTV type VTR, a system (an HDTV compatible system) is required whose tape head relative speed is about four times that of the current VTR. That is, if the recording wavelength is kept constant, the signal frequency increases by about 4 times, so the relative speed needs to increase by about 4 times. In order to automatically discriminate and reproduce the above two formats in this VTR, first, for example, reproduction is performed using an HD TV compatible system. At this time, the carrier frequency of the reproduced FM signal of the tape recorded with the current system is about four times that of recording, and the allocation is about the same as that of HDTV recording. Therefore, there is a problem in that it is difficult to discriminate based on the signal level of the carrier frequency.

An object of the present invention is to provide a reproduction determination circuit of the above two types.

[Means to solve the problem]

The above object is achieved by the following method. Both tapes recorded with current systems and HD TV compatible systems can be used with either system, e.g.
Play on compatible systems. At this time, the tape recorded with the current system will be played back at a relative tape speed that is about four times that of recording. This playback output is HD T
The signal is input to the reproduction signal processing circuit of the V-compatible system, and after FM detection, passes through a de-emphasis circuit to obtain a reproduction video signal. This reproduced video signal will be converted to a frequency approximately four times that of recording. Therefore, the horizontal synchronization signal frequency in this reproduced video signal is approximately 63 kIh (15,
It becomes 734kl (zX4). On the other hand, the horizontal synchronization signal frequency of HD TV system is now 33.75! Iz, automatic discrimination between the two systems is possible by determining these frequencies and switching between the two systems.

[For production]

With this magnetic recording and reproducing device (π, when playing back a tape recorded with the current system or a tape recorded with an HD TV compatible system, first, the tape recorded with one of the systems, such as H
Playback on a DTV compatible system.

At this time, the spectrum of the reproduced signal obtained from the tape recorded with the current system will shift to a frequency about four times that of recording. Therefore, the frequency of the horizontal synchronizing signal at this time is approximately 63kl(x).

On the other hand, the horizontal synchronization signal frequency of HDTV system is 33.75
It is kHz. Therefore, the above-mentioned two systems are discriminated by determining the difference in their frequencies or the difference in their periods, and selecting the rotational speed mode of the reproduction signal processing system, the disk motor, and the capstan motor. In this way, each tape can be played back in accordance with its recording mode.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 3 to 6.

Figure 1 shows a multimedia-compatible V T to which the present invention is applied.
It is a block diagram of R.

In Figure 1, 1 is a magnetic tape, 2 is a disk, 3,
4 is a magnetic head, 5 is a disk motor, 6 is a capstan shaft, and 7 is a capstan motor.

8 is a capstan servo circuit, 9 is a disk servo circuit, 10 is a capstan phase control circuit, 11 is a capstan speed control circuit, 12 is a switch circuit, 13 is n (n
>1) Frequency divider circuit, 14 is disk phase control circuit, 15 is disk speed control circuit, 1G is switch circuit, 17 is n
(n>1) frequency dividing circuit; 18 is an HDTV system reproduction signal processing circuit; 19 is a current TV system reproduction signal processing circuit; 20 is a switch circuit; 21 is the above-mentioned two system discrimination circuit; 22a.

22b is a magnet, 23 is a tack head, and 24 is a monitor cut circuit.

The magnetic tape 1 is run by a capstan motor, and the capstan motor 7 is controlled to rotate at a constant speed by a capstan servo circuit 8. Here, when playing back an HD TV recording tape.

It is necessary to increase the relative speed of the head tape to about four times that of the current playback system. At that time, the motor rotational speed information (obtained from a 5-frequency generator FG, for example) is frequency-divided by a 4-frequency divider circuit 13 with n=4 and inputted to the capstan speed control circuit. 7. A quadruple speed circuit for reproduction using the current method can be obtained.

The magnetic heads 3.4 have different azimuth angles, are mounted on the disk 2 at an angle of 180' to each other, and are rotated together with the disk 2 by the disk motor 5. The magnetic tape 1 is wrapped around the disk 2 by more than 180°, so that a so-called overlap portion is formed at the portion where the head 3.4 simultaneously contacts the magnetic tape IJ:, ie, on the track. Two magnets 2 on disk 2
2a and 22b are attached to each other at an angle of 180a, which is detected by the tack head 23 and the heads 3 and 4
A tack pulse synchronized with the rotation of the tack head 23 is obtained from the tack head 23. The tack pulse from the tack head 23 is input to the disk phase control circuit 14, and after the phase is adjusted so that the heads 3, 4 and the magnetic tape 1 have a predetermined relative positional relationship, the tack pulse is adjusted to the rotation of the heads 3, 4. A synchronized pulse (H8W) with a duty ratio of 50% is obtained. This pulse switches the outputs of the heads 3 and 4 to obtain continuous reproduction output.

Here too, when playing back an HD TV recording tape,
It is necessary to increase the relative speed of the head tape to about four times that of the current reproduction system. In the disk motor 5 as well, the rotational speed information of the motor is frequency-divided by the 4-frequency divider circuit 17 in the same way as the capstan motor 7 and the disk speed control circuit 15
By inputting , it is possible to obtain the quadruple speed rotation of the disc motor 5 during the current method of reproduction. At this time, by simultaneously rotating the capstan motor 7 and the disk motor 5 at four times the speed, the trajectory traced by the heads 3 and 4 on the magnetic tape 1, that is, the tracing angle of the head 3°4, is changed from that during playback using the current system. , has the effect of being able to be the same during 4x speed playback.

In this VTR, we will discuss automatic discrimination during playback between current system recording tapes and HD TV system recording tapes.

When the magnetic tape 1 is attached, it is not possible to distinguish between the two methods. Therefore, first, as the reproduction mode of the HDTV system, both the disk motor 5 and the capstan motor 7 are set to rotate at four times the speed. At this time, magnetic tape 1 is HD T
If the tape is recorded in the V format, the signal can be reproduced without any problem. - If the magnetic tape 1 is a tape recorded using the current method, the carrier frequency of the reproduced FM signal will be four times that of recording. Therefore, the carrier frequency allocation of the reproduced signal is almost the same as that of the HDTV system. Therefore, the single playback output is converted to HD TV.
When a video signal is obtained by inputting it to the reproduction signal processing circuit 18, performing FM detection, and passing through a de-emphasis circuit, the frequency will be four times that of recording. In other words, the synchronization signal frequency is quadrupled. Therefore, the horizontal synchronization signal frequency is.

15.734klrzX4=62.936kllz, vertical synchronization signal frequency is 59.941rzx'=2401
(Z) On the other hand, the horizontal synchronization signal frequency in the HDTV system is 33.75 kl (z, and the vertical synchronization signal frequency is 6
0 tlz. By detecting one of the above two types of synchronization signals and switching between the capstan motor speed, disk motor speed, and playback signal processing circuit using the output of the discrimination circuit 21 that discriminates between the above two methods based on the frequency, current TV The playback mode of the magnetic tape 1 recorded using this method can be set and played back. At this time, in order to eliminate the unsightly appearance on the screen until one discrimination is completed when the current TV system recording tape is played back in the HDTV system, a monitor cut circuit 24 is provided that does not output a playback signal until the discrimination is completed. .

Next, the discrimination circuit portion of the present invention will be explained in detail.

FIG. 3 is a block diagram of the same, in which the same parts as in FIG. 1 are given the same reference numerals. 25.26 is a reproduction amplifier, 27 is a switch circuit, 28 is an equalizer circuit, 29 is a limiter circuit, 3
0 is an FM detection circuit, 31 is a low-pass filter, 32 is a de-emphasis circuit, 33 is a synchronization signal separation circuit, and 34 is a synchronization signal period detection circuit.

The reproduction outputs of the heads 3 and 4 are transmitted to the reproduction amplifier 25.
Amplify by 26. Thereafter, the switch circuit 27 is switched using a pulse (I (SW)) with a duty ratio of 50% synchronized with the rotation of the heads 3 and 4, which is formed from the tack pulse from the tack head 23 described above, and a continuous reproduction output is generated. The continuous playback output from the switch circuit 27 is transmitted to the HDTV.
The signal is input to the system reproduction signal processing circuit 18. This signal processing circuit 18 is similar to the current TV system reproduction signal processing circuit 19. First, an equalizer circuit 28 that compensates for the frequency characteristics present in the tape head reproduction system, and a limiter circuit 29 that eliminates level fluctuations included in the reproduction output from the heads 3 and 4.
The signal is then input to the FM detection circuit 30. The video signal demodulated by this FM detection circuit 30 is input to a low-pass filter 31 for removing the FM carrier component. Thereafter, the signal is input to the de-emphasis circuit 32. This is FM
The problem with modulation is that demodulation noise is proportional to frequency, so in order to maintain the S/N ratio, high frequency parts are emphasized and recorded (pre-emphasis). On the other hand, de-emphasis circuit 3
2, the gain can be reduced during playback by the amount emphasized by pre-emphasis. In this way, the SN ratio is improved. The video signal obtained here is input to the discrimination circuit 21. This circuit 21 includes a synchronization separation circuit 33 that separates a synchronization signal from an input video signal, and a cycle detection circuit 3 that detects the cycle of the synchronization signal and discriminates between the two methods described above.
Consists of 4.

Next, a specific circuit of the discrimination circuit of the present invention will be explained with reference to FIG. The same parts as in FIG. 3 are given the same reference numerals. 35 is a clamp circuit, 36° 37 is a reference power supply, 38 is a capacitor, 39 is a comparator, 40 is a transistor, 41
is a circuit power supply, 47 is a retrievable mono-multi vibrator (abbreviated as mono-multi), 48 is a pulse forming circuit,
49 is a D flip-flop.

The leading edge of the synchronizing signal of the input video signal is suppressed to a predetermined level by the clamp circuit 35. This clamp circuit 35
The predetermined level (V c ) of is Vc = V knee 0,7 (V) (1) where the voltage value of the reference power supply 36 is vl.
becomes. The output of this clamp circuit 35 is input to a comparator 39. One input of the comparator 39 is the base 1g power supply 37, and if the voltage value v2 thereof is set as 2>vc, the synchronization signal can be easily separated. A circuit for detecting the period of the separated synchronization signal will be explained using the timing chart of FIG. The pulse width of the monomulti 47 is set to be slightly longer than the period of the higher of the two signal frequencies to be compared. In other words, 2 of (a) and (d) in Figure 5
When comparing input signals with different periods, set the period to be longer than the period of the signal in (a). At this time, mono multi 4
When the signal (a) is input to 7.

As shown in FIG. 5(b), the Q output remains at a high level. The monomulti 47 is trigged at the rising edge of the input signal. On the other hand, when the signal shown in FIG. 5(d) is input to the monomulti 47, its Q output becomes as shown in FIG. 5(e). Therefore, a pulse forming circuit 48 forms a pulse synchronized with the falling edge of the synchronization signal input to the monomulti 47. That is, in FIG. 7, pulses (c) and (f) are formed for two types of inputs (a) and (d), respectively. If this pulse is used as the clock input of the D-Flinopfromp 49, the Q2 output will be high level in case (a) and low level in case (d), meaning that two types of signal frequencies can be distinguished. .

So far, we have described a method of first reproducing the magnetic tape 1 in the HDTV system reproduction mode and determining it.Next, we will describe a method of first reproducing the magnetic tape 1 in the current TV system reproduction mode and determining it.

FIG. 6 shows its block diagram. The same parts as in FIG. 1 are given the same reference numerals. 50 is a discrimination circuit for the above two methods;
51 is a monitor circuit for HDTV video signals.

In this case, tapes recorded using the current TV system can be played back without any problem. On the other hand, when playing back a tape recorded using the I(D TV system), the rotational speed of the capstan motor and the disk motor will be reduced to 1/4. Therefore, the frequency allocation of the played FM signal will be is - at the time of recording. Therefore, it is about the same as that of the current TV system, so it cannot be determined by the carrier frequency. Therefore, as described above, the frequency of the synchronization signal of the reproduced video signal is detected and the difference is determined. .

When playing back a tape recorded in HDTV format, the horizontal synchronizing signal frequency is 33.75kl (zX
1/4=8.438kl (z, vertical synchronization signal frequency is
601 (zX1/4=1511z.

On the other hand, when playing back a tape recorded using the current TV system,
They are 15.734 to 7 and 59.94 to 7, respectively. If these frequencies are discriminated by the discrimination circuit 50 similar to the above,
This means that two methods can be distinguished.

Next, another method of the above two discrimination methods will be explained using FIG. 7. Here, as can be seen from the frequency allocation in Figure 2, in the current TV system, the color signal is converted to the low frequency range and recorded by multiplexing one frequency, whereas in the HDTV system, this method is not used. In Figure 2 (
As shown in c), the luminance signal portion and the color signal portion are recorded separately on the recording signal waveform, that is, multiplexed on the time axis. Therefore, when playing back a tape recorded with the current TV system, there is a color signal carrier in the low range, whereas when playing back a tape recorded with the HD TV system, there is no carrier in the low range. .

This discrimination method attempts to discriminate between the above two methods by utilizing this difference.

In FIG. 7, the same parts as in FIG. 3 are given the same reference numerals. 52 is a discrimination circuit, 53 is a bandpass filter, 54 is a comparator, 55 is a reference power supply, 56 is an envelope detection circuit, 57
is a waveform shaping circuit.

In this determination method as well, first, reproduction is performed in the HD TV system reproduction mode. In this case, the carrier frequency of the low frequency conversion color signal on the current TV system recording tape is 629 kl.
(zX4A2.5M+(z (VH3 system). Therefore, the center frequency of the bandpass filter 53 is
The signal level of this carrier is detected as M) (z. That is, the output of the bandpass filter 53 is input to the comparator 54. This output is compared with the voltage value of the reference power supply 55, and carriers exceeding a predetermined value are detected. The cured signal is input to an envelope detection circuit 56 to obtain its envelope output.The envelope output is waveform-shaped by a waveform shaping circuit 57, and if it is above a predetermined level, it is determined that it is the current TV system.

On the other hand, when reproduction is performed in the current TV system reproduction mode, the center frequency of the filter corresponding to the band-pass filter 53 may be 629 kHz.

In this case, since the reproduced signal processing circuit of the current TV system separates the color signal and the luminance signal and then processes each signal, the output signal of the separated color signal at this time is sent to the comparator 54. If the output level after passing through the envelope detection circuit and waveform shaping circuit is below a predetermined value, it is determined that the tape is an HDTV recording tape, as described above. in this case.

This has the advantage that a filter corresponding to the bandpass filter 53 is not required.

The above two discrimination methods have the advantage that no special signal is required for discrimination.

Another discrimination method is to use the control pulse (CTLP) used for phase control using FIG. 8. During HDTV recording, the capstan motor is rotated at four times the speed of current TV recording, so when reproducing in a different mode, the CTLP frequency changes.

Both CT LPs are recorded at the 172 frequency of the vertical synchronization signal, or 30 Hz. Therefore, when a current TV system recording tape is played back in the HDTV system playback mode, the CTLP playback frequency is approximately 1201h. Conversely, when an HDTV recording tape is played back in the current TV playback mode, the CTLP playback frequency is 7.5.
)1z, becomes. This method detects this frequency difference.

FIG. 8 is a block diagram of another of the above-mentioned two-system discrimination methods, in which the same reference numerals as in FIG. 1 and the same parts are given the same reference numerals. 58 is a capstan servo circuit, 59
6 is a capstan motor phase control circuit, 60 is a control head, and 61 is a two-system discrimination circuit.

, 1, l The Con+-Call pulses reproduced from the control head 60 are used to advance the tape during reproduction and the magnetic head 3,
A phase control signal is output from the capstan motor phase control circuit 59 so that the relationship with the rotational position of No. 4 matches that at the time of recording. First, when reproduction is performed in the HD TV format reproduction mode, a discrimination circuit 61 detects the CTLP frequency, discriminates the format, and switches the capstan motor, disk motor, and reproduction signal processing circuit based on the discrimination output of the circuit 61. On the other hand, the same procedure can be used when first playing in the current TV format playback mode and making the determination.

FIG. 9 shows magnetic tape patterns recorded in the current TV system and HD TV system. In the current TV system,
Although it is recorded with 1 field and 1 recording track, HD
In the TV system, the capstan motor rotational speed is four times that of the current TV system, so one field is recorded with four recording tracks.

FIG. 10 is a specific circuit diagram of the one-line discriminating circuit, in which 62 is a pulse shaping circuit, 63 is a counter, 64 is a count value discriminating circuit, and 67 is a D flip-flop.

The CTLP reproduced from the control head 60 is shaped by a pulse shaping circuit 62, and this output pulse is used to control the counter 6.
Preset 3. On the other hand, the clock output of the clock generation circuit 64 is input to the counter 63 and counted. The output of this counter 61 is determined by monitoring one output bit, for example, and if it remains at a low level (becomes a high level).

The current playback mode is determined to be incorrect. A clock pulse formed by inputting CTLP to the pulse forming circuit 65, CTLP, and the discrimination output of the count value discrimination circuit 66 of the one-cycle counter 63 are input to the D flip-flop 67 and held there. The output of this D flip-flop 67 switches the capstan motor, disk motor, and reproduction signal processing circuit.

〔Effect of the invention〕

According to the present invention, recording tape of the current TV system and HDT
By reproducing the V format recording tape in one of the reproduction modes, it is possible to detect the difference in the frequency of the synchronizing signal in the reproduced video signal, which has the effect of automatically distinguishing between the two formats.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a diagram of frequency allocation during recording in the current TV system and HDTV system, and HDTV system recording signal waveform diagram, and Fig. 3 is a block diagram of the discrimination circuit portion of the present invention. , FIG. 4 is a specific circuit diagram of the discrimination circuit of the present invention, FIG. 5 is a timing chart of FIG. 4,
FIG. 6 is a block diagram of another embodiment of the present invention, and FIG. 7 is a block diagram of another embodiment of the present invention.
FIG. 8 is a block diagram of another method of discrimination, FIG. 9 is an explanatory diagram of a magnetic tape pattern, and FIG. 10 is a specific circuit of the discrimination circuit of FIG. 8. It is a diagram. DESCRIPTION OF SYMBOLS 11... Capstan speed control circuit, 15... Disk speed control circuit, 12, 16.20... Switch circuit, 13, 17-n frequency division circuit, 2L, 50... Discrimination circuit, 24.51 ...Monitor cut circuit, 33...
・Synchronization separation circuit, 34... Period detection circuit, 35...
Clamp circuit, 36.37...Group 1! ! Power supply, 38・
...Capacitor, 39...Comparator, 40...Transistor, 47...Retrievable monomulti, 48...
- Pulse forming circuit, 49...D flip-flop. Yu (α)

Claims (1)

[Claims] It has one or more recording and reproduction information signal processing circuits, records each information signal on diagonal tracks of the magnetic tape with a rotating magnetic head at a relative speed of the tape head corresponding to each information signal, and In a magnetic recording and reproducing apparatus for reproduction, a selection means for selecting one set of the reproduction information signal processing circuit and the tape head relative speed, and recording information signal discrimination based on the output of the reproduction information signal processing circuit selected by the selection means. A magnetic recording/reproducing apparatus comprising means for controlling the selection means by the output of the recording information signal determining means.