JPS5914813B2 - magnetic playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording device for recording video signals on a magnetic tape using a rotating magnetic head, and a magnetic reproducing device for reproducing video signals recorded on a magnetic tape using a rotating magnetic head. Regarding the device, in particular, detecting a signal indicating the relative positional relationship between the recording track on the magnetic tape and the rotating magnetic head,
The present invention relates to a magnetic reproducing device suitable for so-called auto-tracking 15, which enables a rotating magnetic head to accurately scan a recording track based on this signal.

That is, according to the present invention, recording is performed by aligning the recording positions of horizontal synchronizing signals of adjacent recording tracks, and 2H (H
(horizontal synchronization signal period), pie head signals of two different frequencies are recorded alternately, and at the time of playback, crosstalk signals or bead signals of adjacent recording tracks reproduced from the magnetic head appear alternately at 0. None,
Based on the pilot signal, a signal indicating the positional relationship between the recording track and the rotary magnetic head is detected during reproduction, and this signal is used to enable the rotary magnetic head to accurately scan the recording track. The object of the present invention is to provide a magnetic reproducing device configured as follows. below,
The present invention will be explained based on illustrated embodiments. FIG. 1 is a block diagram showing an example of the configuration of a magnetic recording/reproducing apparatus embodying the present invention. First, to explain the recording device, we will explain the method of recording the pie head signal of frequency fl and the pilot signal of frequency f2 every 2H (H is the period of the horizontal synchronizing signal) as shown in FIGS. 2 and 3. I'm taking it. The difference between FIG. 352 and FIG. 3 is that the tape running direction and the scanning direction of the rotating magnetic head are opposite. To explain the recording method shown in FIG. 2, a video signal to be recorded is applied to the human C input terminal 31.

This video signal is applied to a frequency modulator 25 to be converted into a frequency modulated video signal, mixed with a pilot signal to be described later in a mixer 24, and applied to the magnetic heads 4 and 5 via a transducer 6. It is recorded on the magnetic tape 1. Next, we will explain how to generate the pilot signal. The block group within the dotted line frame shown in FIG. 1 is the pilot signal generator 54. The video signal to be recorded applied to the input terminal 31 is also applied to a horizontal periodic signal separation circuit 36 and a vertical synchronization signal separation circuit 32, and a horizontal synchronization signal and a vertical synchronization signal are obtained from these circuits, respectively. The vertical synchronizing signal is further delayed by approximately one field by the delay circuit 33. This is to start recording one video track several hours before the vertical synchronization signal. In other words, the number of vertical synchronization signals (H for both recording and playback) is the number H of the signals of the 62 rotating magnetic heads.
This is to prevent the previously set discontinuous portion of the six signals from entering the vertical synchronization signal portion. The vertical synchronization signal thus delayed is applied to the counting circuit 34. A specific circuit diagram of this counting circuit 34 is shown in FIGS. 4 and 5. FIG. 4 shows a ring counter system, and FIG. 5 shows a shift register system. Both outputs give the same signal. FIG. 6 shows signal waveforms of the circuit block described above. Figure 6a shows the video signal waveform applied to the input terminal 31, Figure 6b shows the vertical synchronization signal which is the output waveform of the vertical synchronization signal separation circuit 32, and Figure 6c shows the delay of this vertical synchronization signal. This is a signal waveform delayed by the circuit 33. Further, this signal is applied to a flip-flop 55 (hereinafter referred to as F.F55) to obtain a frequency-divided signal by 1/2 as shown in FIG. 6d. This signal is applied to a servo circuit which will be described later. Furthermore, the delayed vertical synchronizing signal shown in FIG. 6c is added to the counting circuit 34 (the specific number of circuits is shown in FIG. 4 and FIG.
, f, g, h are obtained. On the other hand, input terminal 3
The video signal added to 1 is also added to the horizontal synchronization separation circuit 36.

(The signal waveform in this case is as shown in Figure 7a. Figure 6a
The difference is the scale of the time axis. ) The output signal of this horizontal synchronizing signal separation circuit 36 is as shown in FIG. 7b. Further, the horizontal synchronization signal is applied to a delay circuit 37 for removing the equivalent pulse of the vertical synchronization signal portion.

The output is as shown in FIG. 7c, and is delayed by approximately 1H from the original horizontal synchronizing signal. It is preferable to match the original horizontal synchronizing signal by delaying 1H, but there is no problem even if the time is slightly shorter than 6H.

Now, this delayed horizontal synchronization signal is F. F38, and a signal frequency-divided by 1/2 as shown in FIGS. 7D and 7E is obtained. Furthermore, these signals are F. F39 and F. Added to F4O. F. 7th from F39, 4O
The signals shown in Figures F, g, h, and i are obtained. Furthermore, F. F3
The rising edge of FIG. 7f in FIG. 9 is differentiated and waveform-shaped by the waveform shaping circuit 35 to obtain the signal shown in FIG. In addition to F4O are Figure 7 F, g, h, i
F. so that the phase relationship is as shown in . This is to reset F4O.

Next, the gate circuits 41, 4.2, 43, and 44 will be explained.

E, f, g, h in FIG. 6 obtained from the counting circuit 34 (this order corresponds to the numbers of the output terminals of the counting circuit 34 in FIGS. 4 and 5. ,f,g,h
correspond to the above-mentioned FIG. 6 E, f, g, and h. ) are applied to gate circuits 41, 42, 43, and 44. Furthermore, these gate circuits 41, 42, 43, and 44 have the above-mentioned functions.
Since the signals F, g, h, and i in FIG. 7 obtained from 39 and 4O are added (the polarities of the pulses are made to correspond with the symbols Q and Q shown in FIG. 1 and FIG. 7). ) 4 rectangular wave pulses with a 4H period are output from each gate circuit 41 to 44.
A gated signal for one field period is obtained for every other field. The phases of these gated pulses (4H period pulses FIG. 7 F, g, h, i) are shifted by π/2. The 4H period pulse signals gated in this manner are mixed in a mixer 45.

At the output of this mixer 45, a gate signal as shown in FIG. 8 is obtained. A in this figure coincides with the recording end 56 of the video track 52 shown in FIG. Also the 8th
Fl, f2 shown in the figure and Fl, f2 shown in FIG. 2 match. That is, if F, , f2 are recorded during the period shown in FIG. 8, a recording pattern as shown in FIG. 2 will be obtained. The method of generating the pilot signal will be described below. The gate signal shown in FIG. 8 described above is applied to the gate circuit 47 and the phase inverter 49.

An inverted signal of the gate signal shown in FIG. 8 is obtained at the output of the phase inverter 49. The inverted gate signal is applied to gate circuit 50. The gate circuits 47 and 50 have F,
Since the pilot signals of the oscillator 48, which generates a signal with a frequency of F2, and the oscillator 61, which generates a signal with a frequency of F2, are added, pilot signals gated with the above-mentioned gate signals are obtained, respectively. When the gated pilot signals thus obtained are mixed in a mixer 46, continuous pilot signals in the arrangement Fl and f2 shown in FIG. 8 are obtained. If this signal is mixed with the above-mentioned frequency modulated video signal (by the frequency modulator 25) in the mixer 24 and supplied to the magnetic heads 4 and 5 via the R terminal of the 6 switch 20B, the result will be as shown in FIG. It is recorded with a recording pattern. Note that the servo system for the drum motor, etc. is the same as a normal TR, so I will not mention it here.When recording, please use the F. The signal shown in FIG. 6d, which is obtained by frequency-dividing the vertical synchronizing signal obtained from F55, is used as a reference.

This signal is amplified by the amplifier 22 and applied to the control head 17 via the changeover switch 20A<17)R terminal for recording. Furthermore, F. as shown in FIG. 6d. The signal of F55 is applied to the phase comparator 13 via the R terminal of the changeover switch 20c. This phase comparator 13 receives a rotational phase pulse (amplified by an amplifier 12) generated from the fixed magnetic head 7 every time the permanent magnet 8 attached to the drum 3 comes over the fixed magnetic head 7.

) has also been added. Therefore, the phase comparator 13 obtains a phase error signal of both of the above signals, and if this signal is applied to the drum motor 16 via the first drive circuit 14 including a phase compensation circuit, the phase comparator 13→drive circuit 14 → Drum motor 16 → Motor shaft 9 → Drum 3 → Rotation detection mechanism of permanent magnet 8 and fixed head 7 → Amplifier 12 → Phase comparator 13 Since a phase control loop is formed, the rotating magnetic head can detect the input image. It rotates synchronously with a predetermined phase difference with respect to the vertical synchronization signal of the signal.

The switches 20A, 20B, and 20C are interlocked, and the movable contact piece is on the R terminal side during recording. Further, the carbstan motor 23 rotates at a predetermined number of rotations regardless of recording or reproduction. The recording method for obtaining the recording pattern shown in FIG. 2 has been described above. A case where the scanning direction of the rotary head is different from the case shown in FIG. 2 shown in FIG. 3 will be explained. In this case, as can be seen from FIG. 3, by recording Fl and f2 alternately for 2H, a predetermined magnetic recording pattern can be obtained. Therefore, in Figure 1, F. F3
9 or F. The square wave signal of F4O every 2H may be applied to the gate circuit 44, and the inverted signal of the gate circuit 47 may be applied to the gate circuit 50. As mentioned above, the recording method has been described.As mentioned above, the pilot signal may be a continuous signal of the frequencies Fl and f2, but for example, recording of a color signal converted to a low frequency, which is often used recently, is also possible. If this method is used, the six pilot signals f1 and F2 will fall within the band of this converted color signal, causing a problem. Therefore, if a method is adopted in which the pilot signal is recorded only during the blanking period of the horizontal synchronization signal, as shown in FIG.
Time division. and recorded together with the low frequency converted color signal. The recording pattern shown in Figure 9 is when the air gears of the two rotating magnetic heads have opposite inclinations, and this eliminates crosstalk between adjacent tracks of frequency-modulated high-frequency signals. This method is sometimes used6 and is generally called azimuth recording.
This recording method is thus also possible in azimuth recording. By the way, in order to record the pilot only in the blanking portion of the horizontal synchronization signal as described above, the horizontal synchronization signal of the horizontal synchronization signal separation circuit 36 is used as a gate signal to record the pilot signal obtained from the mixer 46. The pilot signal may be gated and the gated pilot signal may be added to the mixer 24 and recorded.

Next, the playback device will be explained. During playback, the movable contacts of the switches 20A, 20B, and 20C are connected to the P terminal.

First, regarding the control of the rotating magnetic head device 2, the carbstan motor 23 is set to have the same rotation speed so that the tape speed is the same during recording and during reproduction.

By doing this, a differentiated reproduction signal having the same period as the recording control signal (see FIG. 6d) can be obtained from the control head 17. Only the positive direction pulse signal of this reproduced signal is amplified by an amplifier 21 6 and a delay circuit 1
5, the phase is adjusted to be the same as that during recording. This is to compensate for the fact that there is some delay in the control head 7 and amplifier 21. Next, the output of this delay circuit 15 is sent to switch 2.
It is applied to the phase comparator 13 via 0C. This phase comparator 13 has a fixed head 7 as in the case of recording described above.
Since the rotational phase pulse from . . . is added, a phase control loop is formed in the same manner as described above, and the six-drum motor 16 rotates synchronously with the control signal as a reference signal. By doing so, the rotary head can scan the recording drum shown in FIGS. 2 and 3 described above. Thus, the above-mentioned recorded signals are reproduced from the rotating magnetic heads 4 and 5. The signals reproduced from the rotating magnetic heads 4, 5 are applied to the amplifier 26 via the rotary, transformer 6 and switch 20B, and are amplified. (Actually, since it has two heads, two amplifiers are required, but they are not shown.) Then, the demodulator 2
7 (normal frequency modulated wave demodulator) and an amplifier 28, the signal is outputted to an output terminal 29 as a video signal. If a monitor television receiver is connected to the output terminal 29, the reproduced image can be viewed. In the above reproduction method, a good reproduced image can be obtained if the recording track can be scanned accurately, but in reality the recording track is not as straight as shown in Figures 2 and 3. It is often curved.

That is, as shown in FIG. 10, the recording track may be S-shaped. This type of curvature may be S-shaped or C-shaped.
It may be written in font, and it varies depending on the deck.
The cause of this curvature of the recording track is when the rotation axis and the rotating drum surface are not at right angles but are tilted, or when the reed that regulates the height position of the tape in the 6-drum is bent, or when the 6-tape is bent. This is due to cases where the vehicle moves up and down in a direction perpendicular to the running direction. The degree of this curvature is approximately ±5 μm even if the mechanical accuracy is considerably improved6, and is considered to be even larger in the normal case. If the track pitch P mentioned above is set to about 10 μm, for example, if scanning is performed in a straight line as shown by the dotted line in FIG. The reproduction output of the rotary head also decreases to 5070 degrees compared to the case of accurate scanning. Here, even if there is a curvature of the recording track during the 6th reproduction, the drive is moved to rotate along the curvature to perform scanning.

Let's explain the tracking method below.

First, the track width T of the rotating magnetic head is set to be equal to or greater than the recording track width pitch P and smaller than 2P, as shown in FIG.

If this is done, one part of the recording will be double recorded, but in the double recorded part, the signal recorded after the previously recorded part will be erased and a new recording will be made, so the recording track pitch will be P. on the other hand. In the case of playback, the rotating magnetic head straddles the track as shown in Figure 11, and the cap of the magnetic head shown in the figure is tilted to prevent the signal of the adjacent track from being played back (to account for so-called crosstalk). Take methods etc.

However, by tilting the cap in this way, crosstalk of signals with short recording wavelengths, that is, high frequency signals such as frequency-modulated video signals, can be removed, but crosstalk of high frequency signals such as the above-mentioned low-frequency converted color carrier wave signals can be removed. Cannot be removed. Furthermore, since the pilot signal must also be a signal with a frequency close to the subcarrier frequency of the low-frequency converted color signal, tracking is performed using the crosstalk signal. First, a method for detecting track deviation will be described. The amplified rotary head reproduction output from amplifier 26, previously described in FIG.

A concrete circuit block diagram of this track deviation detector 30 is shown in FIG. 12, FIG. 13, and FIG. 14. 1st
The track deviation detector shown in FIG. 2 will be explained. 1st
In FIG. 2, the amplified reproduction signal of the rotary head described above is applied to terminal 57.

The signal waveform shown in FIG. 15a shows the reproduced signal. This reproduced signal also includes crosstalk signals from adjacent tracks, as described above.

Next, this signal is applied to bandpass filters 59, 64 (hereinafter referred to as B.P, F59, 64) centered at frequencies F, , f2, and each B.P. P. Frequency F at F59,64
The pilot signals of l and f2 are separated. Figure 15B,
C is the above B. P. This is the output signal of F59, 64, and the second
As you can see by comparing it with the figure, (I, ii in Figure 2
,llll... is shown when the part is being played,
The pilot signal of frequency f1 (corresponding to Fig. 15 a (2) I, ii, iil...) is regenerated every 2H (the opening of the figure), and the pilot signal of frequency f1 is regenerated. In the portion where no signal is recorded, a pilot signal of frequency f1 is reproduced as crosstalk from an adjacent track (part C in the figure). B. F. F64 output signal (15th
The same applies to Figure b). Next, B5P. The output of F59 is applied to the 6-detection circuit 60, and the signal shown in FIG. 15d is obtained. B. P. The output of F64 is also applied to the detection circuit 65 to obtain the signal shown in FIG. 15e. Furthermore, the signal shown in FIG. 15d from the detection circuit 60 is clipped by a clipping circuit 61. A 2H width pulse signal is obtained at the portion where the pilot signal of frequency f1 is reproduced (the opening in FIG. 15b). This pulse signal is applied to a waveform shaping circuit 62, where this signal (FIG. 15 f1) is differentiated and its rising portion is waveform-shaped to obtain the signal shown in FIG. 15 g. Furthermore, the signal shown in FIG. 15g is applied to the delay circuit 63 and delayed by 1H to obtain the signal shown in FIG. 15j.
On the other hand, the output signal of the above-mentioned detection circuit 65 (the signal shown in FIG. 15e) is applied to a sample hold circuit 66 and a voltage comparison circuit 67.

The sample hold circuit 66 includes the waveform shaping circuit 6 described above.
Since the signal in FIG. 15g of FIG. 2 is added as a gate signal, the output of this sample hold circuit 66 is
As shown in FIG. 15h, the voltage at the beginning of the crosstalk section in FIG. 15e is held, resulting in the signal shown in FIG. 15b. Next, the signal shown in FIG. 15h is applied to the voltage comparison circuit 67. Since the signal shown in FIG. 15e, which is the output signal of the detection circuit 65, is also added to the voltage comparison circuit 67, a difference voltage signal between the two signals as shown in FIG. 15 is obtained here. This differential voltage signal is further applied to a sample hold circuit 68, sampled and held by the sample pulse shown in FIG. 15j of the delay circuit 63 described above. The output signal is shown in Fig. 15k,
This signal provides a signal with a voltage amplitude proportional to the amount of deviation, which changes from positive to negative depending on the direction of track deviation. By applying this signal to an electromechanical transducer element capable of moving the rotary head, which will be described later, it is possible to cause the rotary head to scan along the curvature of the track described above.

By the way, the track deviation detector 30 shown in FIG. 13 is the same as that shown in FIG. 12 within the dotted line in FIG.

The numbers of each circuit block within the dotted line are the same as those in FIG. Furthermore, circuit blocks other than those within the dotted line in FIG. 13 that have the same function as those shown in FIG. 12 have dashes added to their numbers. As can be seen from the block diagram in FIG. 13, the blocks with dots are either the clip circuit 61 to the delay circuit 63 or the detection circuit 6 in FIG.
5, and the sample and hold circuits 66 to 68 are connected after the waveform circuit 60.

As shown in FIGS. 15D and 15E, this waveform is 2H alternating: it is the same even if the circuit blocks are replaced as described above. In the case of FIG. 13, the detection every 2H explained in FIG. 12 is performed every 1H, making it possible to perform detailed detection. Note that the mixer 69 in FIG. 13 was detected by the above-mentioned 2H (however, the detection points were different by 180 points).

This is used to mix track deviation signals. Next, the first
The track deviation detector 30 shown in FIG. 4 will now be explained. Since the input/output signals are the same as those in FIGS. 12 and 13 above, terminal numbers 57 and 58 are given the same numbers.

Now, the reproduction signal of the rotating magnetic head applied to the input terminal 57 is applied to a low-pass filter 706 and a band filter 76 centered at frequency f1 or F2. First, the main scanning track (same as above; in Fig. 2):,;
j;...) and the adjacent track Fl, f2 bead (frequency f-1f1-F2l)
), the envelope becomes as shown in Figure 16a. The low-pass filter 70 is for removing the above-described frequency-modulated video signal, and only the pilot signal is obtained from the output of this filter 70. This signal waveform is similar to the signal waveform shown in FIG. 16a. (Although the width is different overall, the envelope remains the same.
) The signal obtained from the filter 70 is applied to an envelope detection circuit 71, and only the change component of the envelope due to the bead as shown in FIG. 16B is obtained. Furthermore, the signal shown in FIG. 16b is added to the detection circuit 72.
Here, the signal is detected and rectified, and a signal as shown in FIG. 16c is obtained. On the other hand, B. P. Figure 16a added to F76
This B. P. Only the pilot signal of frequency f1 is taken out by F76.

(The signal waveform is the same as that in FIG. 15b.) Further, the signal extracted in this manner is applied to a detection circuit 77. A signal as shown in FIG. 16d is obtained from this detection circuit 77. Furthermore, this signal is applied to a clip circuit 78 to provide a first clip representing the recorded portion of the f1 frequency.
A rectangular wave signal during 2H as shown in Figure 6e is obtained. This signal is then applied to waveform shaping circuits 79 and 80. This waveform shaping circuit 79 converts the above-mentioned rectangular wave signal (Fig. 16e
) and shapes its rising edge to obtain the pulse shown in Figure 16f.The waveform shaping circuit 80 differentiates the rectangular wave signal (Figure 16e) and shapes its falling edge. The signal shown in FIG. 16g is obtained. These pulse signals (FIG. 16F, g) are mixed in a mixer 81 to produce a signal shown in FIG. 16H. Furthermore, since this signal is applied to the 1H delay circuit 82, the signal shown in FIG. 16 is obtained. Now, the pulse signals H and i in FIG.
added to.

Since the signal shown in FIG. 16c obtained from the above-mentioned detection circuit 72 is added to the sample hold circuit 73, this signal is sampled and held by the above-mentioned sample pulse (FIG. 16h). The signal shown in FIG. 16j is obtained. Furthermore, 6 this signal is applied to the voltage comparator circuit 7.
Added to 4. Since the signal shown in FIG. 16c, which is the output signal of the detection circuit 72 described above, is also applied to the voltage comparison circuit 74, a difference signal as shown in FIG. 16k is obtained here. Furthermore, this signal is applied to a sample and hold circuit 75.

This sample hold circuit 75 includes the above-mentioned delay circuit 8.
Since the sampling pulse shown in FIG. 16 from 2 is added, a signal indicating the track deviation shown in FIG. 16 is obtained at the output terminal 58 of the sup-hold circuit 75.
still. The method shown in Fig. 12 detects from which track the most crosstalk signal is emitted based on the deviation of the rotating head from the track, and the direction of the deviation is determined by the direction in which the crosstalk is directed to the pilot signal of the main scanning track. This method obtains a track deviation signal by comparing whether it is coming out earlier than the other one.

Although FIG. 13 is similar to FIG. 12, it is a method of detecting it more finely (temporally).

The one in FIG. 14 detects track deviation based on the magnitude of the bead signals of the signals of frequencies Fl and f2 (the deviation is toward the side with a larger bead amount), and detects the deviation of the main scanning track. This is a method of determining the direction of track deviation based on the reproduction order of the pilot signals. I will now explain this point in a little more detail.

In Fig. 2, there are snakes 1i, [Ii,...
Consider the case where a track indicated by . . . is being scanned. The symbols 1, ii, and iii are the same as I, ll, and iii shown in the signal in Figure 16a.10 In other words, when scanning I, ii, and llll on the track, The signal is played.

Now, when part i is being scanned, the frequency of track l is f1, and on the right side a signal of the same frequency f1 is recorded, so no bead signal is generated.

On the left side, the F2 signal is recorded, so (F, -F2)
A bead signal is generated. Therefore, in this case, if the 6 bead signal force is strong, it will be shifted to the left. Next I
When scanning part i 6 The right side of that track is F2
Since it is a signal, a bead signal of 61f1-F2l is generated. Since the left side is the same signal of f1, no bead occurs.
Therefore, as in the case of j, in the portion Ii, the amount of bead signal decreases when it is closer to the left side. Considering this, in the tracks recorded as shown in FIG. 2, the direction can be determined by knowing the bead signal amount of the main track signal. In other words, it is written 6f or 2H consecutively, so if there is a large amount of beads in the first 1H period, it indicates that it has shifted to the left, and if there is a large amount of beads in the next 1H period, it indicates that it has shifted to the right. shows. Whether the main signal is f1 or F2 can be determined by the polarity of the signal shown in FIG. 16e, so if only the amount of bead is detected, its direction can be determined, and a track deviation signal can also be obtained. The track deviation signal thus obtained is applied through the brush 11 and the slip ring 10 to an electro-mechanical transducer which will be described below.

FIG. 17 is a block diagram of the electro-mechanical conversion element 83 attached to the drum 3, the rotary drum 3, and the rotary head 4. This electro-mechanical conversion element 83 is made by gluing piezoelectric elements 87 and 89 together as shown in FIG. The surface of this piezoelectric element has gold or silver vapor deposited films 86, 88,
90 is attached. A piezoelectric element 8 is formed using this vapor-deposited film as an electrode.
7 and 89 whose polarization directions are opposite to each other (the bonded surface is the deposited film 88 = center electrode) can be used as an electro-mechanical transducer. That is, if this bonded piezoelectric element 83 is firmly attached to the rotating drum 3 with a screw 85 together with a piezoelectric element retainer 84 made of metal, it becomes a cantilever beam with the portion 92 as a fulcrum. Further, a lead wire 93 is joined to this center electrode 88, and one electrode of the slip ring 10 is connected with the lead wire 93, and the rotating drum 3 (metal) is connected to the other electrode of the slip ring with a lead wire (not shown). When a voltage is applied between the electrodes, the tip of the piezoelectric element moves in the direction shown by arrow 91 in FIG. This movement is due to the electrostrictive effect of the piezoelectric elements 87 and 89. In this bonded piezoelectric element, the electrode 86 and the electrode 90 are electrically connected by the piezoelectric element presser 84 and the screw 85, so that between the center electrode 88 and the electrode 86, the center electrode 88
The same voltage in the same direction is applied between and the electrode 90. Since the direction of polarization is reversed, for example, piezoelectric element 87
When the piezoelectric element 89 extends in the direction shown on the right of the arrow 94, the piezoelectric element 89 contracts in the direction shown on the left of the arrow 94. The rotating head at the tip of the bonded piezoelectric element then moves in the downward direction of arrow 91. Needless to say, in the opposite case to the above, the robot moves in the upward direction of the arrow 91.

From the above, tracking can be performed by applying the track deviation signal obtained from the track deviation detector 30 described above between the electrodes of this bonded piezoelectric element.

In other words, by applying the signal indicating the track deviation described above to the piezoelectric element 83 shown in FIG. For example, track deviation detector 30 → brush 1L slip ring 10 → rotating drum 3 → bonded piezoelectric elements 83 (2 pieces) → rotating head 4
, 5 magnetic tape 1→recording track 52→rotary transformer 6→switch 20B→amplifier 26→track deviation detector 30, and the rotating magnetic head accurately scans the recording track.

Note that the bonded piezoelectric element 83 is connected to the electrode 88 during recording.
and electrodes 86 and 90 are short-circuited so that no voltage is applied between the electrodes. In addition, in the case of the recording method shown in FIG. 9, if a comparison is made only in the portion where the pilot signal is recorded, the results are exactly the same as those described above.

That is, the above-mentioned sampling pulses (G, j in the case of FIG. 15) may be made to correspond to the portion where the pilot is recorded. As described above, since the present invention detects track deviation based on recorded pilot signals, it has the great effect of accurately detecting the amount and direction of track deviation in guard bandless recording methods. Further, by applying the track deviation signal obtained here to the electro-mechanical conversion element, tracking control can be easily performed, which is a great effect, and its value is extremely great.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a magnetic recording/reproducing apparatus using the present invention, FIGS. 2, 3, and 9 are track pattern diagrams on a magnetic tape, and FIGS. A specific circuit diagram of the counting circuit 34 shown in FIG. 6, 7, and 8 are circuit block signal waveform diagrams of FIG. 1, FIGS. 10 and 11 are explanatory diagrams of tracking control, and FIG. 12. 13 and 14 are specific circuit block diagrams of the track deviation detector 30, FIGS. 15 and 16 are waveform diagrams of each block signal shown in FIGS. 12 and 13, and FIG. 17 is an electrical/mechanical A perspective view of the structure of the conversion element, FIG. 18a is a front view thereof, and FIG. 18b is a side view thereof. 2...Rotating) Tsudo drum, 30...
Track deviation detector, 54...Pilot signal recording device, 83...Electro-mechanical conversion element.

Claims (1)

[Claims] 1 Pilot signals of different frequencies f_1 and f_2 are recorded alternately in 2H (H is horizontal synchronization signal section) in one recording trajectory, and between adjacent recording trajectory,
A track that reproduces a magnetic tape on which pilot signals of the frequencies f_1 and f_2 are recorded alternately for 1H, with no gaps between adjacent recording trajectories, and whose width is equal to or larger than the width of the recording trajectories. The recording locus on the magnetic tape is scanned using a rotating magnetic head with a width of 100 mm, and a track deviation is detected by a pilot signal reproduced by the rotating magnetic head, and tracking is automatically performed. An electro-mechanical transducer that moves the magnetic head perpendicular to its scanning direction, and a beat signal (frequency f=|f_1-f_2|) from adjacent tracks in the pilot signal reproduced by the rotary head.
), a gate signal generating means for waveform-shaping the pilot signal of f_1 or f_2 to obtain a gate signal at the time when the beat of f_1 or f_2 occurs, and a gate signal generating means for detecting the level of the beat signal from the level detector. An error signal generating means for obtaining a track deviation signal by sampling and holding the gate signal is provided, and the error signal is added to the electro-mechanical conversion element to perform tracking control. playback device.