JPH0520801B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a recorded signal discrimination method when a rotating head type magnetic recording/reproducing device is used as a video tape recorder (hereinafter referred to as VTR) and a multitrack PCM recorder. be.

Conventional technology In recent years, VHS and Betamax VTRs have been introduced.
8mm with a different tape format than
VTR standards were unified. According to that standard,
The signal processing of video signals is basically the same as the VHS and Betamax systems, but the PCM system is adopted for recording audio signals, and the control system uses a pilot signal for tracking. Also, in order to record this PCM signal, the amount of tape wrapped around the cylinder containing the rotary head, as shown in Figure 2, is approximately the same as the conventional one.
In addition to the 180 degree winding, there is approximately 36 degrees more winding, which corresponds to the PCM recording area. In FIG. 2, 1 and 2 are rotating magnetic heads, 3 is a magnetic tape, arrow 4 is the running direction of the tape, arrow 5 is the rotating direction of the rotating head, and 6 is a cylinder. FIG _. 3 shows _the tape _format of an 8mm VTR in which the tape 3 is wrapped around the cylinder 6 as _shown in FIG. This is a magnetization trajectory recorded by rotating head B. As shown in the figure, the PCM is recorded in an area of 36 degrees, and the video signal is recorded in an area of (180+α) degrees. In addition, as shown in Japanese Patent Application Laid-open No. 58-222402, one track is divided into multiple (6) tracks as shown in Figure 4, and each divided track is How to record and play back signals i.e.
A method of using a VTR as a multitrack PCM device has been proposed. To explain FIG. 4, the first input audio signals are BL1-A ₁ , BL1-B ₁ , BL1
-A ₂ , BL1-B ₂ , . . . are sequentially recorded, and other audio signals are sequentially recorded as BL2-A ₁ , BL2-B ₁ , BL2-A ₂ , and so on. 7 and 8 are optional tracks provided parallel to the longitudinal direction of the tape.

Problems to be Solved by the Invention As explained in the prior art, using a VTR as a multitrack PCM device is of course
It can also be applied to VHS format VTRs. However, as a result, there are two types of tape formats in the same cassette, and it is necessary to set which device is being used during playback.

The present invention can be applied to VTR, multi-track PCM, etc. during playback.
The purpose of this project is to provide a method for automatic identification without the user having to make any troublesome settings.

Measures to Solve the Problems In VHS system VTRs, control signals are recorded on longitudinal tracks at the ends of the tape for tracking during playback. however,
Multitrack using control signals
In order to realize PPCM, the divided tracks must be in a straight line as shown in Figure 4. If they are not aligned, it will be necessary to readjust the tracking shifter for each divided track during playback. On the other hand, if the tracking pilot signal is recorded along with the time-axis compressed audio signal like an 8mm video,
Since tracking can be performed using the reproduced pilot signal reproduced from the divided tracks to be reproduced, it is not necessary for the tracks to be lined up in a straight line as shown in FIG. Therefore, when used as a VTR, a control signal is recorded for tracking, and when used as a multitrack PCM, a tracking pilot signal is recorded, and the presence or absence of the tracking pilot signal is detected during playback. By doing so, two types of discrimination information are obtained.

Function: As described above, the present invention detects whether or not a tracking pilot signal is reproduced during reproduction, and if it is reproduced, the multitrack PCM tape is
If it doesn't play, you can tell it's a VTR tape.

Embodiment First of all, the format of a VHS system VTR used as a multi-track PCM will be explained with reference to FIG. 3 is a magnetic tape, and 13 is a section called a video width where a video signal is recorded during VTR. 9 is a control track, 10 is a first audio track (LCH), 11 is a second audio track (RCH), and 12 is an audio guard. When used as a multi-channel PCM, divide the video width as shown in the figure. That is, track 1 (TR1), track 2 (TR2), track 3 (TR3), and track 4 (TR4). The input audio signals are, for example, TR2-A ₁ , TR2-B ₁ ,
They are recorded sequentially as TR2-A ₂ and TR2-B ₂ .
When used as a VTR, it becomes a single linear track as shown by the broken line, but when using multi-track PCM, pilot tracking is used, so TR1-A ₁ , TR as shown in the figure.
They do not need to be in a straight line like 2-A ₁ , TR3-A ₁ , and TR4-A ₁ . Next, before explaining the main parts of the present invention, a tracking control method using four types of pilot signals will be explained with reference to FIGS. 6 and 7. In FIG. 6, arrow 5 indicates the running direction of the head and indicates the recording magnetization locus of the four-frequency pilot signal. In the same figure, A ₁ , B ₁ , A ₂ ,
B ₂ , . . . are magnetization trajectories recorded on the A head and B head, and f ₁ to _{f 4} represent pilot signals for tracking control. Each pilot signal is recorded superimposed on the information signal, and f ₁ →
The signals are cyclically switched and recorded in the order of f ₂ → f ₃ → f ₄ . The frequency of each pilot signal is
When the frequency of the horizontal synchronization signal of the video signal is f _H ,
The signal has a frequency of 6.5f _H to 10.5f _H. The frequency difference of the pilot signal between each recording magnetic locus is f _H and 3f _H as shown in FIG. Therefore, by detecting the f _H and 3F _H signals using the method described later and comparing their reproduction levels, it is possible to know the amount of deviation in head scanning with respect to the recorded magnetization locus.

FIG. 7 is a block diagram of a processing circuit for obtaining a tracking data signal from a reproduced pilot signal. In the figure, a circuit 15 is a balanced modulation circuit, and a reproduced pilot signal separated from the signal reproduced by the rotary head is inputted from a terminal 16, and a reference signal is inputted from a terminal 17. The reference signal is a signal having the same frequency as the pilot signal recorded on the magnetization trajectory scanned by the head. For example, as shown in Figure 6, the head
When the _B1 track is reproduced and scanned, the pilot signals to be reproduced are _f1 , _f2 , and _f3 , and the frequency of the reference signal is _f2 . The output signal of the balanced modulation circuit 15 is a signal having a frequency that is the sum and difference of the frequencies of the reproduced pilot signal and the reference signal. The difference output signals are signals with frequencies f _H and 3f _H , and the output levels of these signals are the same as the pilot signals recorded on each adjacent track for the track that the head mainly scans for reproduction. is equal to the playback level. Circuits 18 and 19 are f _H and 3f _H
This is a tuning circuit that tunes to a signal with a frequency of .
The output signals of each tuning circuit are detected and rectified in circuits 20 and 21, and then their levels are compared in a comparison circuit 22. The comparison output wave is 1/2V _CC by the inverting circuit 23.
(V _CC is the power supply voltage). The inverted and non-inverted outputs are input to a switch circuit 24, and are alternately switched for each track in response to a head switching signal (H.SW) supplied from a terminal 25, and then output from a terminal 26. This output signal is a tracking error signal. As is clear from FIG. 6, the shift direction of the head with respect to the recording track and the change in the reproduction level of the f _H and 3f _H signals are A _i track (i = 1, 2, 3...)
and B _i track have opposite relationships. Therefore, if the polarity is switched for each track using the inverting circuit 23, the polarity of the tracking error signal obtained at the terminal 26 will be the polarity corresponding to the track deviation regardless of the scanning track.

Next, the operation during recording will be explained using FIG. 8.

Switches 1 (hereinafter referred to as SW1) to SW5 are recording/reproducing switching SWs, where R indicates recording and PB indicates reproduction. The circuit connected to the PB side is shown in Figure 1.
SW6 to SW10 are switches for switching between VTR and multitrack PCM, and are set by the user according to the purpose.

First, we will explain how to use it as a VTR. The video signal input from the terminal 30 is input to the video signal processing circuit 31, where it is separated into a luminance signal and a chrominance signal, the luminance signal is FM modulated, the chrominance signal is low frequency converted, and both signals are added and output. Ru.
The output of the video signal processing circuit 31 is SW8, SW9
It is amplified by recording amplifiers 32 and 33 through the V side of SW2 and SW3, and then sent to the heads 34 and 3 through the R side of SW2 and SW3.
5 and are sequentially recorded as tracks indicated by broken lines in FIG. The video signal amplified by the video signal processing circuit 31 is supplied to a vertical synchronization signal separation circuit 36, where the vertical synchronization signal is separated and supplied to a 1/2 frequency divider circuit 37. The signal whose frequency has been divided into 1/2 by the 1/2 frequency divider circuit 37 to become a square wave is amplified by the recording amplifier 38, and is sent to the control head 39 via the V side of SW10 and the R side of SW1 as shown in FIG. 9 control track. The audio signals input from the audio signal input terminals 40 and 41 are sent to SW6 and SW7.
The signal is supplied to the linear track audio signal processing circuit 42 through the V side of SW4 and SW5, where it is processed for normal AC bias recording, and through the R side of SW4 and SW5.
The audio heads 43 and 44 record on audio tracks 10 and 11 in FIG. Next, the case of using it as a multi-track PCM will be explained. In this case, the video signal cannot be recorded, so the explanation will be omitted. Audio signal input terminals 40, 4
1, the input signal is input to the PCM signal processing circuit 45 via the PC side of SW6 and SW7. P.C.M.
The signal input to the signal processing circuit 45 is A/D converted and then recorded in the RAM, and an error correction code, address code, etc. are added thereto. In accordance with the recording track designation signal supplied from the pulse generator 46, the clock is read out with a higher frequency clock than the clock previously written to the RAM, modulated, and then supplied to the synthesizer 47. The pilot signal generator 48 generates pilot signals of frequencies f ₁ , f ₂ , f ₃ , and f ₄ , and generates signals for each track according to the head switch pulses supplied from the pilot pulse generator 46 as shown in FIG. (This track is TR1-A ₁ , TR2-A ₁ , TR3-A ₁ , TR4-
A ₁ ) i.e. for every half revolution of the cylinder, f ₁
→f ₂ →f ₃ →f ₄ →f ₁ and the signals are sequentially switched and output as shown in Fig. 9h. The output of the pilot signal generator 48 is supplied to a combiner 47, where it is combined with the modulated PCM signal and supplied to gate circuits 49 and 50. For example, when storing data in TR ₂ , the gate circuits 49 and 50 contain information at the timing when the rotary head scans the divided tracks as shown in e and f in FIG.
A high level signal is supplied from the pulse generator 46. The output signals of the gate circuits 49 and 50 are sent to the recording amplifier 3 via the PC side of SW8 and SW9.
After being supplied to SW2, 33 and widened, SW2, SW
TR2-A 1 , TR2-B 1 , TR2-A ₁ , TR2-A 1 , TR2-A ₁ , TR2-A 1 , TR2-A ₁ ,
... is recorded. Next, the operation of the pulse generator 46 will be supplementarily explained using the time chart shown in FIG. The terminal 51 is an input terminal for an output signal (PG signal) of a cylinder rotation phase detector (not shown), and a signal as shown in FIG. 9a is input to the pulse generator 46. The input PG signal triggers the monomultivibrator with a plus pulse and a minus pulse, respectively. The outputs of the two mono-multivibrators are shown in Figure 9 b and c.
The delay amounts t ₁ and t ₂ are set so that the video signal is recorded at a regular position on the tape for one field as before. At the delayed timing of the two monomultis, the flip-flop is triggered to create the head switch pulse of FIG. 9d. This head switch pulse is supplied to the pilot signal generator 48 as described above, and is also supplied from the terminal 53 to the cylinder servo circuit (not shown).

The pulse generator 46 is supplied with track information to be recorded via a terminal 52 from a system control circuit (not shown) during PCM recording and reproduction. In the pulse generator 46, in response to the track instruction input from the terminal 52,
For example, if track 2 is specified, signals e and f are supplied to the gate circuits 49 and 50, and the PCM
The signal processing circuit 45 is supplied with pulses of g. Similarly, when track 4 is designated, the gate circuits 49 and 50 are supplied with the i and k signals, and the PCM signal processing circuit 45 is supplied with the l signal.

Next, the operation during reproduction will be explained using FIGS. 1 and 10. Components that perform the same operations as in FIG. 8 are given the same numbers. During playback, the head 34,
The signal reproduced at 35 is amplified by regeneration amplifiers 60 and 61 via the PB side of SW2 and SW3, and then input to a head switch circuit 62. The head switch circuit 62 switches the signals reproduced from the two heads using a head switch pulse from the pulse generator 46 to form one series of signals. The output of the head switch circuit 62 is LPF6
3, only the pilot signals _f1 to _f4 are extracted.
The output of the LPF 63 is input to the f ₁ tuning circuit 64,
Only the component of f ₁ is selectively amplified. For example, if multi-track PCM is used to record in TR2, the output of the _f1 tuning circuit 64 will have a waveform as shown in FIG. 10m.
FIG. 10 h and d are the same signals as FIG. 9 h and d. The reason why the waveform m is also output at the timings f ₂ and f ₄ of the signal h is reproduced because the head is drawing the signal of the adjacent track during scanning. (6th
Even when a wide head as shown in the figure is used, since the pilot signal is a low frequency signal and there is no azimuth loss, it can naturally be reproduced. ) f ₄ The output of the tuning circuit 64 is
The signal is input to the detection rectifier circuit 65. Detection rectifier circuit 6
5, the first Schmitt circuit 66 is detected and rectified.
is supplied to In the first Schmitt circuit 66,
If it is above the Schmitt level, the configuration is such that a signal as shown in FIG. 10 m is output. 1st
The output of the Schmitt circuit 66 is input to a charging/discharging circuit 67. The output of the charging/discharging circuit 67 is input to a second Schmitt circuit 68. The discharge time constant of the charging/discharging circuit 67 and the Schmitt level of the second Schmitt circuit 68 are set such that, for example, once f ₁ is regenerated, when f ₁ is not regenerated for eight consecutive fields, they become lower than the threshold level. You can set it to . That is, the first Schmitt circuit 66
If there is an output as shown in Figure 10n, the output of the charging/discharging circuit 67 will be as shown in Figure 10o, which is higher than the Schmitt level V _S of the second Schmitt circuit 68. The output of
The level becomes high, and the contacts of analog SW69 to 72 are connected to the PC side. Furthermore, when used as a VTR, the _f1 component is not recorded, so the output of the first Schmitt circuit 66 is at a low level, and the output of the second Schmitt circuit 68 is also low.
The level becomes Low, and the contacts of the analog SWs 69 to 72 are connected to the V side. In this way, switching between VTR and multitrack PCM is automatically performed.

Next, tracking during playback will be explained.
If the analog SW 72 is now connected to the PC side, the output of the LPF 63 is supplied to the pilot processing circuit 73. Pilot regeneration processing circuit 73
is the circuit explained earlier in Figure 7, and LPF63
The reproducing pilot, the reference signal from the pilot generator 48, and the head switching signal from the pulse generator 46 are input, and a tracking error signal is output. The output of the pilot reproduction processing circuit 73 is supplied to a sample hold circuit 74. The sample and hold circuit 74 is supplied with a pulse having a timing near the center of the track designated for reproduction (one of TR1 to TR4 in FIG. 5) from the pulse generator 46, and the sample and hold circuit 74 is supplied with a pulse having a timing near the center of the track designated for reproduction (one of TR1 to TR4 in FIG. 5). The tracking error signal of the track to be tracked is held. The output of the sample hold circuit 74 is passed through a compensation filter 75.
is supplied to The output of the compensation filter 75 is supplied to the synthesis circuit 76 via the PC side of the analog SW 72. In the synthesis circuit 76, the signal is synthesized with the speed error signal of the speed control circuit 80, and is supplied to the capstan motor drive circuit 77, where the power is amplified and the power is supplied to the capstan motor 78. The capstan motor 78 is equipped with a capstan frequency generator, and its signal is supplied to a speed control circuit 80 for speed control.
With the above configuration, during multi-PCM, even if the tracks are not aligned in a straight line as shown in Figure 5,
This allows tracking of the divided tracks to be reproduced. Next, the case of VTR will be explained.
The signal reproduced from the control head 39 is
The signal is amplified by a regenerative amplifier 81 via the PB side of SW1, and a tracking monomulti 82 is triggered. The tracking monomulti 82 pulses the delayed signal and supplies it to a sample hold circuit 83 as a sampling pulse. On the other hand, 1/1 of the vertical synchronization signal output from the reference oscillator 84
The two frequencies are input to a trapezoidal wave generating circuit 85, converted into a trapezoidal wave, and then supplied to a sample hold circuit 83. The output of the sample hold circuit 83 is passed through a compensation filter to the V of the analog SW 72.
The light is then supplied to a combining circuit 76 via the side, and the light is subsequently tracked in a configuration similar to pilot tracking.

Next, the output of the second Schmitt circuit 68 becomes High.
In other words, playback of multitrack PCM will be explained when outputting . Since the analog SW69 is connected to the PC side, the video signal output terminal 87
nothing is output. Also, head switch circuit 6
2 outputs only the divided track signals to be reproduced by the gate circuit 92 and the PCM signal processing circuit 45.
is supplied to The reproduced signal input to the PCM signal processing circuit 45 is demodulated and once written to RAM, subjected to error correction processing, etc., and then read out with a clock having a lower frequency than the write clock to be time-expanded, and then D/A converted. and output. The output signal is analog SW70,7
The signal is amplified by output amplifiers 88 and 89 via the PC side of No. 1, and is output to the audio signal output terminal.

Next, the output of the second Schmitt circuit 68 goes low.
When outputting , analog SW69 to 72 are connected to the V side and enter VTR mode. The output of the head switch circuit 62 is input to the video signal processing circuit 31, where it is separated into a color signal component that has undergone low frequency conversion and a luminance signal component, the luminance signal is FM demodulated, and the chrominance signal is returned to its pre-recording frequency. After that, it is combined with the luminance signal, amplified, and output. The output signal is output to the video output terminal via the V side of the analog SW 69. Also audio head 4
The signals reproduced by 3 and 44 are sent to SW4 and SW5.
After being input to the linear track audio signal processing circuit 42 via the PB side and subjected to reproduction processing such as width expansion,
The signals are amplified by output amplifiers 88 and 89 via the V sides of analog switches 70 and 71, and then output to audio signal output terminals 90 and 91.

Effects of the Invention As explained in the embodiments, when a magnetic recording/reproducing/recording device is used for both a VTR and a multitrack PCM, and when a tracking signal is used as a VTR, a control signal is used to control the multitrack PCM.
When used as a PCM, by using a pilot signal, by detecting the presence or absence of a pilot signal during playback, it is possible to automatically determine whether the tape being used as a VTR is a multi-track PCM tape. , the user does not have to worry about setting up the settings.

In addition to the above effects, by using two types of tracking signals in this way, VHS, β
- It goes without saying that the basic effect is that multi-track PCM can be introduced into existing systems such as MAX, and that the optimum pilot tracking method can be used when used as multi-track PCM.

[Brief explanation of the drawing]

FIG. 1 is an electrical block diagram of an embodiment of the playback side of the apparatus according to the present invention, FIG. 2 is a schematic plan view of the tape running system for 8 mm video, and FIG.
Figure 4 shows the tape pattern in millimeter video, and Figure 4 shows the multitrack pattern in 8mm video.
Figure 5 is a diagram showing the tape pattern in PCM. Figure 5 is a diagram showing the tape pattern when VHS-VTR is converted to multi-track PCM. Figure 6 is a diagram showing the recorded magnetization locus of the pilot signal in the 4-frequency pilot system. The figure is an electrical block diagram for obtaining a tracking error signal from a 4-frequency pilot signal, Figure 8 is an electrical block diagram of an embodiment of the recording side of the device according to the present invention, and Figure 9 supplements Figure 8. FIG. 10 is a timing chart for supplementary explanation of FIG. 1. 46...Pulse generator, 63...LP
F, 64... Tuning amplifier, 65... Detection rectifier circuit, 66... First Schmitts circuit, 67... Charge/discharge circuit, 68... Second Schmitts circuit.

Claims (1)

[Claims] 1. In an apparatus for recording and reproducing information signals as a group of discontinuous recording tracks by winding a magnetic tape diagonally around a cylinder with a built-in rotary head, there is a first recording mode in which video signals are recorded on the diagonal tracks, and a first recording mode in which a video signal is recorded on the diagonal tracks; The track is divided into a plurality of tracks, and each track has a second recording mode in which the audio signal is digitized and time-axis compressed. When recording in the second recording mode, a pilot signal for tracking control is superimposed and recorded on the time-base compressed audio signal, and during playback, a pilot signal for tracking control is recorded. 1. A method for determining a recording mode for a magnetic recording/reproducing apparatus, characterized in that a first recording mode and a second recording mode are determined by detecting the presence or absence of a pilot signal.