JPH0469849A - Tracking system - Google Patents

Abstract

PURPOSE:To obtain a good tracking state by superposing two frequencies lower than the frequency of a recording signal on the recording signal detecting two frequency components included in a reproduced signal and using them as a control signal to adjust the rotation of a rotating drum to prescribed phase relations. CONSTITUTION:Detectors 30 and 31 output frequency components f1 and f2 of reproduced outputs of reproducing heads 18a and 19a, and detectors 32 and 33 output frequency components f1 and f2 of reproduced outputs of reproducing heads 18b and 19b. Outputs of these detectors are inputted to switches 35a and 35b, and a comparator 34 compares outputs of detectors 30 and 31 with each other to perform such control that switches 35a and 35b select smaller one of two frequency components. The difference between outputs of switches 35a and 35b is taken by a differential amplifier 36. Phase compensation is performed by a phase compensating circuit 37, and this output and the output of a speed control circuit 38 are added by an adder 39 to drive a capstan motor 41, thereby controlling the reproducing heads 18a and 18b to the best tracking state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tracking method, and more particularly to a tracking method used in a helical scan type magnetic recording and reproducing device that performs simultaneous recording and reproducing using two or more heads.

[Conventional technology] The tracking method used in the conventional helical scan magnetic recording and reproducing device has been put into practical use.
9, the 4' frequencies used for tracking are 1 of 42B and 42d.
output from two oscillators. 42°a oscillates at a frequency of f], 42b oscillates at a frequency of f2, and 42c oscillates at a frequency of f
1.12d oscillates at a frequency of f4. The quantities of ft,, f2゜fa f4 are shown in Figure 3 (b)
As shown in , f 2 − f 1 =
f a, , f 4 - f 1 =
-i b, f3f2=fb, fa -f4-
fa, the outputs of the four oscillators are selected by the frequency selection circuit 43, and the video signal input from the video signal input terminal f1 and the audio signal input from the audio signal input terminal 2 are transmitted to the recording signal processing circuit 3. The signals are modulated by the adder 44 and added by the adder 44. The output of the adder 44 is amplified by a recording amplifier 45 and recorded on the tape 22 by a recording spatula F46. Here, the frequency selection circuit 43 is switched in the order of fl, f2, fa, and f4 by the rotary drum synchronizing pulse signal inputted from the rotation l/ram synchronizing pulse I No. 5 input terminal f-6. Therefore, the frequency distribution of the recording number Z of 8 mm V'T''R is shown in Fig. 3 (a>). zu.

During reproduction, the signal No. 3 read from the 4-retainer 22 by the reproducing head 47 is amplified by the reproducing amplifier 48 and sent to the reproduced signal processing circuit 23 and four adders. The playback signal processing circuit 23 converts the manually input playback signal into the video signal No. 13 and the audio signal, and sends the video signal to the video signal output terminal f2.
4, and the audio signal is output to the audio signal output terminal 25. Ru. Further, an adder 49 adds the output of the regenerative amplifier 48 and the output of the frequency switching circuit 43. Adder 4
The two outputs are a bandpass filter 50 that passes a frequency component of f;l, and a bandpass filter 51 that passes a frequency component of fb. The frequency non-switchable λ signal generator 54 has fl.
Control is performed so that the output of the frequency switching circuit 43 is switched in the order of f4, fa, and f2. In comparison with the playback track, when playing a track on which fl is recorded, use fl, when f2, use f4, when fa, use fa.
When f4, f2 is output. The track where f1 is recorded has f4. Since f2 is recorded on the rear side, when fl is added, fa and fb are generated due to the crosstalk components of the tracks on both sides.

The amplitudes of the outputs of fa and fb are equal when the playback head is in the state shown in Figure 4 (■), fb is larger in the state shown in Figure 4 (0), and fa is larger in the state shown in Figure 4 (■). Therefore, the detected output from the fa acid component bandpass filter 50 is passed through the detector 52, and the detection output from the fb acid component bandpass filter 51 is passed through the detector 53.
When the differential amplifier 36 amplifies the difference between the detection output and the output detected by the reproducing head 47, it becomes zero when the playback head 47 exactly overlaps the track fl, and takes a positive value when it deviates toward f2. The larger the deviation, the larger the value. Also, when it deviates toward A4, it takes a negative value, and the larger the deviation, the larger the value. This is f2 track and f
4 is fa track, fa is f4 track, f2
The same is true when added. Therefore, the output of the differential amplifier 36 is used as a signal representing the tracking state, and the phase compensation circuit 37 performs phase compensation, and the output of the speed control circuit 38 is added to the output of the speed control circuit 38 by the adder 39.
By driving the capstan motor 41 through 0, the reproducing head 47 is controlled to always be in a straight tracking state.

[Problem to be Solved by the Invention J] The conventional tracking method described above requires four frequencies, and the frequency band for tracking is wide, which limits the band of recording signals. If you try to use this for recording with a double azimuth head that records simultaneously with two heads, you will only be able to track one of the two heads, and the mounting height of the two heads on the rotating drum ζJ height. If one head is out of alignment, there is a problem that tracking of the other head cannot be achieved.

[Means for Solving the Problems, J] The tracking method of the present invention includes two magnetic heads attached to a rotating tram at track pitch intervals, and the magnetic heads simultaneously recording data on two adjacent toes of a magnetic tape. A heli-force Lusgian magnetic recording and reproducing device with a double gap node for reproduction! 6, an oscillator that generates two frequencies lower than recording signal frequencies of video signals and audio signals recorded on the magnetic tape;
~ of the two frequencies for simultaneous recording of the two tracks
A recording signal processing circuit that converts one side into a recording signal and outputs it, a switching circuit that switches the frequency to be superimposed every two tracks, and two systems that are regenerated by the double A head. A bandpass filter and a detector that detect the two frequency components included in the reproduced signal and output them as a detected signal, a differential amplifier that outputs the difference between the two detected signals, and the input differential amplifier. The feeding of the magnetic tape and the rotation of the rotary drum are adjusted to have a predetermined phase relationship so that the difference value between the outputs of is constant.

[Example 1 Next, the present invention will be explained with reference to the drawings.

No. 11N is a block diagram of an embodiment of the present invention.

Two frequencies used for dragging are oscillated by an oscillator 4 and an oscillator 5 at fl. The frequencies of fl and f2 are set lower than the recording signal band as shown in FIG.

The relationship between fl and 2 frequencies is not particularly defined.

The embodiment shown in Fig. 1 shows a case where two sets of heads for simultaneous recording are mounted on a rotating drum at a distance of 180". Therefore, recording is performed using four heads. i.e. recording head], 6 a
16b, 1.7a and 17b simultaneously record signals on two tracks each on the Qi 122.

The outputs of oscillator 4 and oscillator 5 are switched by switches 8 and 9.
The output of the switch 8 is selected by the adders 10 and 11.
The output of the switch 9 is output to the adders ]2 and ]3. The switch 8.9 is switched by the head switching signal generation circuit 7, and is controlled so that the track pattern recorded on the tape becomes as shown in FIG. Ru.

In addition, the video signal input from the video signal input terminal 1 and the audio signal input from the audio signal input terminal 2 are processed by the recording signal processing circuit 3 as 16a 16b, 17a, 17b.
are converted into recording signals for each head and sent to adders 10, 11,
It is input to 12 and 13.

The outputs of the adders 10, 11, ] 213 are amplified by recording amplifiers 14a-14b-15a, 15b, respectively,
Head 16a・], 6b・1.7a], 7b
The data is recorded on the tape 22 by. Note that the frequency f]·f2 is set as a frequency that is not affected by azimuth loss due to azimuth recording.

Next, during playback, 18a, 18b and 19a, 1.
Two channels are simultaneously reproduced by two sets of reproduction heads 9b. The output of the reproducing head 1.8a is amplified by the reproducing amplifier 20a, the output of the reproducing head 18b is amplified by the reproducing amplifier 20b, the pressure of the reproducing head 19a is amplified by the reproducing amplifier 2], a, and the output of the reproducing head 1.8a is amplified by the reproducing amplifier 20b. is amplified by the regenerative amplifier 2 ], b. Regenerative amplifier 20a, 20b, 2 ], a, 2 ]
, b are input to the regenerative signal processing circuit 23, and the regenerative amplifier 20a.2], the output of a is input to the switch 55a, and the output is input to the regenerative amplifier 20b.2],
The output of b is input to switch 55[]. The switches 55a and 55b alternately select and output the signal in which the playback head is in contact with the tape from among the two input signals according to the output of the 5-head switching signal generation circuit 7.6 The playback m-number processing circuit 23 Demodulates the video signal and audio signal from the input playback signal and outputs the video signal to the video signal output terminal 2.
4, and the audio signal is output from the audio signal output terminal t! Output from 25.

The output of the switch 55a is input to the bandpass filter 26, 27, and the output of the switch 55b is input to the bandpass filter 28.
・It is input to 29. The bandpass filters 26 and 28 are fl
The bandpass filters 27 and 29 separate the frequency components of f
Separate the two frequency components. From this, the detector 30 which detects the amplitude component of the output of the bandpass filter 26 outputs the frequency component of fl of the reproduction output of the reproduction head 18a19a, and the detector 3 which detects the amplitude component of the output of the bandpass filter 27 outputs the frequency component of the reproduction output of the reproduction head 18a19a. The detector 32 which outputs the frequency component of the reproduction output of the heads 18a and 19a and detects the amplitude component of the output of the bandpass filter 28 is connected to the reproduction head ISb 1.9.
The detector 33 outputs the f1 frequency component of the reproduced output of the bandpass filter 29 and outputs the f2 frequency component of the reproduced output of the reproducing heads 18b and 19b.

The outputs of the detectors 30 and 31 are input to the switch 35a,
The outputs of the detectors 32 and 33 are input to the switch 35b. The comparator 34 compares the magnitude of the output of the detector 30 and the detector 31, and the switch 35 a = 35 b
Control is performed to select the smaller of the two frequency components of and f2.

In FIG. 6, the selection of the switches 35a and 35b is based on the frequency f when the heads 18a and 18)) are in the state (■).
Since the track on which 1 is recorded is being reproduced, the frequency of the 2 components becomes the frequency f2, which is smaller than the frequency component of fl. At this time, the frequency component of f2 is the l'1 stalk component from the immediately following track, and the reproduction spatula l'
The magnitudes of the f2 frequency components of the outputs of 1.8a and ]81) are equal. Further, in the state shown in FIG. 6 (2), the reproducing head 18a is located on the front track of the reproducing track, and the frequency component of f2 becomes large. Furthermore, since the reproduction head 18bi and tfl are on the recorded track, there is no frequency component of f2. Furthermore, in the state shown in FIG. 6, the reproduction output of the reproduction head 18a does not have a frequency component of f2, and the reproduction output of the reproduction head 18b has a large frequency component of f2. Therefore, when the difference between the outputs of the switch 35a and the switch 35b is taken by the differential amplifier 36, the output of the differential amplifier 36 will be zero when the playback head exactly overlaps the playback track, and when it is shifted to the front side. takes a positive value, and the larger the deviation, the larger the value. When it deviates to the rear side of the length, it takes a negative value, and the larger the deviation, the larger the value. Therefore, the output of the differential amplifier 36 is used as a signal representing the tracking state, subjected to phase compensation in the phase compensation circuit 37, and added to the output of the speed control circuit 38 in the adder 39. By driving the motor 41, the reproducing heads 18a and 1.8b are controlled so that they are always in the best tracking state.

In this way, tracking can be performed automatically even when the comparator 34 is controlled to select the larger of the two frequency components f] and f2. At this time switch 3
5a and 35b are selected by heads 18a and 35b in FIG.
1.8 When b is in the state of ■, the track on which 1 is recorded is being played back, so the frequency component of f1 is higher than f1.
Since it is larger than the frequency component of 2, it becomes fl. At this time, the frequency component of fl is the component of the track being played,
The magnitudes of the frequency components of fl in the outputs of the reproducing heads 18a and 18b are equal. Also, when in the state shown in Figure 6 ■,
The reproducing head 18a is located on the front track of the reproducing track, and the frequency component of fl becomes small. Furthermore, since the reproducing head 18b is located on the track where fl is recorded, the frequency component of fl is at its maximum. Also, Figure 6 ■
When it is in the state, the playback output of the playback head 18a is
The frequency component of fl becomes maximum, and the frequency component of fl of the reproduction output of the reproduction heads 1 and 8b becomes small. therefore,
When the difference between the outputs of the switch 35a and the switch 35b is taken by the differential amplifier 36, the output of the differential amplifier 36 becomes zero when the playback head exactly overlaps the playback track, and becomes negative when the playback head is shifted toward the front. The larger the deviation, the larger the value. When the distance is shifted toward the rear of the town, it takes a positive value, and the larger the shift, the larger the value becomes. This is opposite in sign to when the comparator 34 selects the smaller of the two frequency components f] and f2. Therefore, the output of the differential amplifier 36 is used as a signal representing the tracking state, and its sign is inverted via an inverter, and the phase compensation circuit 37
The output of the speed control circuit 38 and the output of the speed control circuit 38 are added together by the adder 39, which is good for driving the capstan motor 41 through the motor drive circuit 40. It can be controlled to be in a tracking state.

Note that in this embodiment, the recording head and the reproducing head are used separately, but the same head may also be used.
Also, four bandpass filters and four detectors are used, but in order to reduce the number of parts, the bandpass filter 2829 and the detector 3233 are removed, and the switch 55a and switch 5
The output of 5b may be time-divided and passed through the bandpass filter 2627 and the detectors 30 and 31, and the output may be sampled and held, returned to the two systems, and output to the switches 35a and 35b for use. Even when simultaneous recording is performed from more than 1 rad, the method of the embodiment shown in FIG.
In the next track to be recorded, this frequency is switched and recorded, and the tracking information is extracted using the outputs of the heads on both sides of three or more heads that are played back simultaneously. be able to.

[Effects of the Invention] As explained above, the present invention provides a helical scan type VTR that performs simultaneous recording using at least two heads.
, by alternately recording two frequencies one minute lower than the recorded signal and obtaining tracking information using the output amplitudes of the two frequency components during playback, tracking can be performed automatically with simple refinement. effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a conventional tracking method, and FIG. 3 is a block diagram showing an example of a conventional tracking method.
4 is a frequency spectrum diagram of the conventional example, FIG. 4 is a track pattern diagram of the conventional example, FIG. 5 is a frequency spectrum diagram of the present embodiment, and FIG. 6 is a track pattern diagram of the present embodiment. ]...Video signal input terminal, 2...Audio signal input terminal, 3...Recording signal processing circuit, 6...Rotating drum synchronization pulse signal input terminal, 7...Head switching signal generation circuit, 8 , 9.55a, 55b, 35a. 35b...Switch switch, 10, 11 1213
．． 39,44.49...Adder, 16a 16b,
17a, 17b, 46-rotating recording magnetic head, 22-=
Magnetic tape, 18a, 18b, 19a, 19b, 47-
Rotating magnetic reproducing head, 23. . Reproduction signal processing circuit, 24... video signal output terminal, 25
・Audio signal pressure terminal, 26, 27, 28° 29.50
．． 51... Bandpass filter, 34... Comparator, 36
...Differential amplifier, 37...Phase compensation circuit, 38...
・Speed control circuit, 40...Motor drive circuit, 4
DESCRIPTION OF SYMBOLS 1... Capstan motor, 43... Frequency selection circuit, 54... Frequency switching signal generation circuit.

Claims (1)

[Claims] 1. In a helical scan type magnetic recording and reproducing device having a double gap head in which two magnetic heads are attached to a rotating drum at a track pitch interval and the magnetic heads simultaneously record and reproduce information on two adjacent tracks of a magnetic tape, an oscillator that generates two frequencies lower than recording signal frequencies of a video signal and an audio signal recorded on a magnetic tape; and an oscillator that superimposes one of the two frequencies on the recording signal and outputs the same when simultaneously recording the two tracks. a recording signal processing circuit, a switching circuit that switches the frequency to be superimposed every two tracks, and detects two frequency components included in the two systems of reproduction signals reproduced by the double gap head and outputs them as detected signals. a bandpass filter and a wave detector; a differential amplifier that outputs the difference between the two detected signals; and a differential amplifier that outputs the difference between the two detected signals; A tracking method comprising means for adjusting the rotation of the drum to a predetermined phase relationship. 2. superimposing one of the two frequencies on a track on which simultaneous recording is performed using at least three of the magnetic heads;
a bandpass filter and a detector that detect the two frequency components included in the outputs of heads at both ends of a plurality of tracks that are simultaneously reproduced and output them as detected signals; and output the two detected outputs to the differential amplifier. The tracking method according to claim 1, characterized in that: