JPH0510737B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tracking control device, and more particularly, to a tracking control device that circulates pilot signals of different frequencies to recording tracks formed sequentially in a row across the running direction on a recording medium. Tracking using an automatic track following method (hereinafter referred to as the ATF method), in which the pilot signal is recorded along with the video signal, and during playback, the frequency components of the pilot signal reproduced from adjacent tracks are detected and the playback head is made to track to a predetermined track. This is suitable for application to a control device.

[Background Art and Problems Therein] As shown in FIG. 1, a four-frequency type tracking control device has been proposed in which pilot signals of four frequencies are sequentially recorded on a recording track.

That is, this tracking control device receives a signal S1, which is a part of the playback output of a rotating video head as a recording/playback head, through a pilot signal detection circuit 1 having a low-pass filter configuration, and detects a pilot signal recorded on a magnetic tape as a recording medium. Create a reproduction pilot signal S2 containing the reproduction output as a component,
This reproduced pilot signal S2 is applied to the error signal forming circuit 3. The error signal forming circuit 3 sends out a tracking error signal S3 formed under the control of the reference signal generating circuit 4.

On the tape 5, as shown in FIG.
A set of four video tracks T1, _T2 , T3, and T4 on which f ₁ , f 2 , f ₃ , and f ₄ are recorded are formed diagonally and closely together so as to be repeated in a cyclical manner. Here, the effective width of the video head constituting the playback head 6 is selected to be approximately equal to the width of the tracks T1 to T4, for example, so that the recording/playback head 6 is currently scanning for playback as shown by the solid line in FIG. If you are tracking correctly on a certain track (this is called a playback track), only one type of pilot frequency component will be included in the playback output by playing back only the pilot signal recorded on that track. As shown in the figure, when the recording/reproducing head 6 is shifted to the right or left with respect to the relevant track, the pilot signal recorded on the track adjacent to the right or left side of the relevant reproduction track is also reproduced, thereby changing the reproduction output. Two types of pilot frequency components are included, and the magnitude of each pilot frequency component is made to correspond to the opposing length of the recording/reproducing head facing the corresponding track.

However, the frequencies of the four types of pilot signals
f _{1 to} f ₄ are selected from the lower band of the color component converted to a low frequency (600 to 700 [kHz]), and are centered around, for example, odd-numbered tracks T1 and T3 among the four circulating tracks T1 to T4. The frequency difference with the pilot signal of the right track is Δf _A , and the frequency difference with the pilot signal of the left track is Δf _B.
The frequency difference between the even-numbered tracks T2 and T4 and the pilot signal of the right track is Δf _B
and the frequency difference between the left track and the pilot signal is Δf _A.

Therefore, head 6 is connected to odd-numbered tracks T1 and T.
3, if there is a signal component with a frequency difference of Δf _A as a frequency component of the pilot signal included in the reproduced signal, it can be seen that the head 6 is shifted to the right, and if there is a signal component with a frequency difference of Δf _B. If there is a component, it can be seen that the head 6 is shifted to the left, and if there is no signal component with a frequency difference of Δf _A and Δf _B , it can be seen that tracking is being performed correctly.

Similarly, head 6 is an even-numbered track T.
2. When reproducing T4, if there is a signal component with a frequency difference of Δf _B as a frequency component of the pilot signal included in the reproduced signal, it is known that the head 6 is shifted to the right, and if the frequency difference is Δf _A If there is a signal component of , it can be seen that the head 6 is shifted to the left.

In this embodiment, the frequencies f 1 , f 2 , f 3 , f 4 assigned to the first, second, third, and fourth tracks _T1 , _T2 , _T3 , and _T4 are f ₁ =102 [ kHz], _f2
= 116 [kHz], f ₃ = 160 [kHz], f ₄ = 146 [kHz], therefore, the difference frequencies Δf _A and Δf _B are Δf _A = |f ₁ −f ₂ | = |f ₃ −f ₄ |=14 [kHz] ...(1) Δf _B = |f ₂ −f ₃ | = |f ₄ −f ₁ |=44 [kHz] ...(2) is selected.

A reproduced signal S1 having such content obtained from the head 6 is given to a pilot signal detection circuit 1 having a low-pass filter configuration, and a reproduced pilot signal S2 obtained by extracting the pilot signal contained in the reproduced signal S1 is sent to a multiplication circuit 14. It is given as the first multiplication input. The reference pilot signal S11 of the reference signal generating circuit 4 is applied to the multiplication circuit 14 as a second multiplication input.

The reference signal generating circuit 4 is connected to a pilot signal generating circuit 16 that generates four types of pilot frequency outputs of frequencies _{f1 to f4} , and a rotating drum (not shown) that scans the tape of a pair of recording/reproducing heads. The switch circuit 17 receives a head switching signal RF-SW (FIG. 3A) which changes the logic level when the head to be switched is switched. In this embodiment, the switch circuit 17 has a quaternary counter circuit that performs a counting operation every time the level of the head switching signal RF-SW changes. The corresponding gate signals are sequentially repeated, and the gates are opened by the gate signals of the tracks T1 to T4, respectively, and the pilot frequencies f1 _{to f4} of the pilot signal generation circuit 16 are activated as shown in FIG. 3B. The outputs are sequentially sent out as a reference pilot signal S11.

Note that the reference pilot signal S11 obtained at the output end of this switch circuit 17 is sent to the recording/reproducing head 6 as a recording pilot signal S4 via the signal line 18 during recording.
While the fourth tracks T1-T4 are being scanned, pilot signals of corresponding frequencies _{f1- f4} are sequentially applied to the heads 6 to record on the respective tracks T1-T4.

In this way, while the head 6 scans the first to fourth tracks T1 to T4, the reproduced pilot signal S2 obtained at the output terminal of the pilot signal detection circuit 1 is generated in synchronization with the reproduced track. By multiplying the reference pilot signal S11 by the frequency component contained in the reproduced pilot signal S2 when there is a tracking error,
A multiplication output S12 comprising a difference signal component having a frequency different from the frequency of the reference pilot signal S11.
(Actually, the multiplication output S12 also includes other signal components such as the frequency component of the sum). The multiplication output S12 is given to first and second difference frequency detection circuits 20 and 21, each of which is configured with a bandpass filter.

The first difference frequency detection circuit 20 has a multiplication output S12.
When the signal component of the difference frequency Δf _A based on the above equation (1) is extracted, it is converted to DC by the DC conversion circuit 22 having a peak detection circuit configuration, and the first error detection of the DC level is performed. A signal S13 is obtained. Similarly, when the multiplication output S12 includes a signal component of the difference frequency Δf _B based on the above equation (2), the second difference frequency detection circuit 21 extracts the signal component and sends it to the DC conversion circuit 23. An error detection signal S14 is obtained.

Here, when the head 6 is about to track the first, second, third, and fourth tracks T1, T2, T3, and T4 (therefore, the switch circuit 17 tracks each track T1, T2, and T4 as shown in FIG. T2, T
3. At the timing corresponding to T4, the frequency is f ₁ ,
If it is shifted to _the right, _the reproduced pilot signal S2 obtained based on the reproduced signal S1 of the head ₆ is transmitted.
As shown in FIG. 3 C1, pilot signals of frequencies f ₁ and f ₂ , f ₂ and f ₃ , f ₃ , and f ₄ , f ₄ and f ₁ are included, and the third signal is output as the multiplication output S12. As shown in Figure D1, the difference frequency Δf _A (=f ₁ ~ _{f 2} ),
Δf _B (=f ₂ ~ f ₃ ), Δf _A (= f ₃ ~ f ₄ ), Δf _B (= f ₄ ~ _{f 1}
) in sequence. On the other hand, head 6
is shifted to the left, the reproduced pilot signal S2 sequentially changes frequencies f ₄ and f ₁ , as shown in FIG. 3 (C2).
It now includes pilot signals of f ₁ and f ₂ , f ₂ and f ₃ , f ₃ and f ₄ , and accordingly, the multiplication output S12 has a difference frequency Δf _B (=f _{4 )} as shown in FIG. 3D2. ~ _f1 ),
Δf _A (=f ₁ to f ₂ ), Δf _B (= f ₂ to f ₃ ), Δf _A (= f ₃ to _{f 4}
) signal components are sequentially included.

Thus, as shown in FIGS. 3E and F (for example, showing a right-shifted state), the first and second error detection signals S13 and S14 whose DC level rises from 0 each time the track scanned by the head 6 changes. can be obtained from the DC converting circuits 22 and 23.

First and second error detection signals S13 and S1
4 are given to the subtraction circuit 24 as an addition input and a subtraction input, respectively, thereby producing the first and second error detection signals S13 and S as shown in FIG. 3G.
14 is obtained alternately, a subtraction output S15 that changes in an alternating current manner is obtained. This subtracted output S15 is applied to the first input terminal a1 of the direct changeover switch circuit 25, and its polarity is inverted in the inverting circuit 26 and applied to the second input terminal a2.

The changeover switch circuit 25 receives the head changeover signal RF-
For example, when the head 6 is scanning odd-numbered tracks T1 and T3 by the SW, the first input terminal a1
When scanning the even-numbered tracks T2 and T4, the second input terminal a2
Thus, as shown in FIG. 3H, when the head 6 is in the rightward deviation state, a positive DC level output S16 of a magnitude corresponding to the rightward deviation amount is obtained (in contrast, when the head 6 is in the leftward deviation state, (at this time, the DC level output S16 has a magnitude corresponding to the leftward shift amount and has a negative polarity), and is sent as a tracking error signal S3 via an output amplification circuit 27 consisting of a DC amplifier.

Incidentally, if the head 6 is shifted to the right, for example, when the reproduced track is an odd numbered track T1 or T3, the output terminal of the multiplication circuit 14 will be shifted from the first difference frequency detection circuit 20 side due to the appearance of the signal component of the difference frequency Δf _A. The output is given to the subtraction circuit 24, and since the changeover switch circuit 25 is switched to the first input terminal a1 at this time, it sends out a tracking error signal S3 of a positive DC level. On the other hand, when the reproduced tracks are even-numbered T2 and T4, a signal component of the difference frequency Δf _B appears at the output terminal of the multiplication circuit 14, so that the output from the second difference frequency detection circuit 21 is sent to the subtraction circuit 24. Moreover, at this time, the changeover switch circuit 25 is switched to the second input terminal a2 side, so the polarity of the negative output of the subtraction circuit 24 is inverted by the inverting circuit 26, and a tracking error signal S3 of a positive DC level is generated. Send as.

Therefore, if this tracking error signal S3 is used as a correction signal in the phase servo circuit of the capstan servo loop and corrected so that the tape running speed is slowed down when it is positive and increased when it is negative, the video head and playback speed are corrected. It can correct the phase shift with the track,
In this way, a correct ATF tracking servo can be realized.

In the above principle configuration, the principle has been described assuming that when the head 6 correctly tracks each track, no difference frequency component is generated at the output terminal of the multiplication circuit 14. However, in reality, even in this tracking state, the reproduced signal S1 of the head is Pilot signals for adjacent tracks on the left and right sides are generated.

That is, in practice, when guard bands are not provided between tracks during recording, newly recorded tracks are sequentially recorded in the recording mode so as to partially overlap already recorded adjacent tracks. Therefore, in this case, the width of the head 6 is larger than the width of each of the tracks T1 to T4, so that when tracking correctly, the head 6 protrudes into the adjacent tracks on the left and right sides. Therefore, since the head 6 reproduces the pilot signals of the tracks adjacent to the left and right sides, error detection signals S13 and S14 (Fig. 3E and F) is generated from the DC conversion circuits 22 and 23.

Furthermore, when a guard band is provided, the width of the head 6 becomes almost equal to the width of the track, but the pilot signals recorded on the adjacent tracks on the left and right sides are mixed into the reproduced signal of the head 6 as a crosstalk signal. do. Therefore, the error detection signal S1
3 and S14 include a signal component of a difference frequency corresponding to a crosstalk signal.

However, since the pilot signals mixed into the reproduced output S1 of the head 6 from the adjacent tracks are simultaneously generated as signal components of difference frequencies Δf _A and Δf _B at the output terminal of the multiplication circuit 14, the error detection signals S13 and S14 are When they are subtracted from each other in the subtraction circuit 24, they cancel each other out. Moreover, when the head 6 is tracking correctly, the head 6 is in a symmetrical position with respect to the tracks adjacent to the left and right sides.
The protrusion lengths of the left and right sides are almost equal, and the magnitude of the crosstalk is also almost the same for the left and right sides.In the end, the content of the subtraction output S15 is equivalent to the above case in which the width of the head 6 is considered to be almost equal to the width of the track, and Therefore, the tracking operation of the tracking control device is not adversely affected by the difference frequency components occurring simultaneously from the adjacent tracks on both sides, due to the head width being larger than the track width or due to crosstalk.

By the way, using the ATF tracking control device with the above configuration, you can use the normal recording mode (this is called
(referred to as SP mode), and a long-time recording mode (referred to as LP mode) that records video signals at 1/2 the tape speed of SP mode.
A video tape recorder (VTR) that records and plays back in two recording modes is being considered.

In order to record video signals on the tape at different tape speeds, the relationships between the tracks formed by recording in the slow tape speed mode, ie, the LP mode, are as shown in FIG. It is necessary to form recording tracks so that they are connected to each other without at least a guard band intervening. However, when recording is performed in SP mode, which has a tape speed that is approximately twice as fast as the rotational speed of the head that satisfies these conditions, as shown in Figure 5, there is a considerable difference between the tracks formed on the tape. A wide guard band will be formed.

If there is a wide guard band G as in the case of recording in the SP mode shown in Figure 5, when the recording/playback head is just tracking each track during playback, the signal will cross the guard band G and arrive from the adjacent track. Since the crosstalk component based on the pilot signal is extremely small, the difference signals Δf _A and Δf _B
There is a problem that information about the system cannot be obtained.

To solve this problem, set the playback mode to LP.
A recording/playback head is prepared corresponding to each mode and has a head width large enough to obtain the crosstalk of the pilot signals recorded on the adjacent tracks when the SP mode or SP mode is selected. It may be possible to select a recording/playback head corresponding to the selected playback mode in accordance with the mode selection and obtain a playback pilot signal for use in ATF tracking control. However, with this method, there is a problem in that the number of recording/reproducing heads must be prepared in accordance with the reproduction mode.

For example, in the case of a VTR having an LP mode and an SP mode as described above, two heads must normally be prepared for each mode, so a total of four recording/playback heads must be provided. In practice, it is necessary in addition to this to provide at least one flying erase head. If such a large number of recording/reproducing heads are mounted on the rotating drum, the structure on the rotating drum becomes complicated and large, so it is desirable to reduce the number of heads mounted on the rotating drum as much as possible.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and
The present invention attempts to propose a tracking control device that can obtain an ATF tracking error signal using a common recording/reproducing head without providing a recording/reproducing head for each reproduction mode.

[Summary of the invention]

In order to achieve this purpose, the present invention includes:
By reproducing a pilot signal from a recording track using an erase head which is not used during reproduction in principle, an ATF tracking error signal can be reliably obtained.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 6 by assigning the same reference numerals to parts corresponding to those in FIG.
It is sent as an error signal S3.

In addition, the output S15 of the subtraction circuit 24 is received by the sample hold circuit 33 of the recording/playback mode detection circuit 32, and its sample hold output S3
2 is applied as a comparison input to the comparator circuit 34 and compared with the reference level signal S33 of the reference power supply 35, and when the signal level of the output signal S32 becomes higher than the reference level VR of the reference level signal S33, it rises to logic "H". The detection output signal S34 is sent to the ATF control circuit 36.
It is designed to be detected.

The ATF control circuit 36 has a built-in recording/playback mode determination circuit that receives the detection output signal S34 and determines whether the playback mode matches the recording mode. A mode detection signal S35 representing the following is applied to the reproduction pilot signal selection circuit 37, and when the recording mode is the LP mode, the reproduction pilot signal selection circuit 37 is switched to the LP mode contact 37L side, and when the recording mode is the SP mode, the reproduction pilot signal selection circuit 37 is switched to the LP mode contact 37L side. Switch the reproduction pilot signal selection circuit 37 to the SP mode contact 37S side.

When the reproduction pilot signal selection circuit 37 is switched to the LP mode contact 37L side, the reproduction pilot signal selection circuit 37 supplies the output S36 of the reproduction circuit 38 as the reproduction output S1 to the pilot signal detection circuit 1, and also supplies the output S36 of the reproduction circuit 38 to the pilot signal detection circuit 1 as the reproduction output S1.
When switched to the S side, the output S37 of the erase pilot signal circuit 39 is sent to the pilot signal detection circuit 1 as a reproduction output S1.

Here, the recording/playback mode detection circuit 32 detects that when the tape speed during recording and the tape speed during playback are different, the scanning locus of the recording/playback head during playback crosses a plurality of tracks, so that the pilot signal detection circuit 1 The regenerated pilot signal S obtained at the output end of
2 changes at a speed faster or slower than the circulation speed of the reference pilot signal S11, resulting in an error signal S obtained at the output of the error signal forming circuit 3.
Focusing on the point that the signal level of No. 3 undulates at a period corresponding to the speed difference, the level of the sample hold output S32 of the sample hold circuit 33 is the same as the reference signal S33.
A mode detection signal S34 indicating the difference between the recording mode and the playback mode when the level becomes higher than the level VR.
It is designed to send out. The principle of the mode detection circuit 32 that operates in this manner is disclosed in Japanese Patent Application No. 141975/1982 (Japanese Patent Application Laid-open No. 31456/1983).

By the way, the waveform of the ATF error signal S3 obtained based on the tape currently being played is the same when a tape recorded in LP mode is played back in SP mode, and conversely, when a tape recorded in SP mode is played back in LP mode. Since there is a difference in the waviness period between the two, the playback pilot selection circuit 37 is set to mode detection so that the playback mode matches the recording mode by determining this waviness period in the recording/playback mode determination circuit of the ATF control circuit 36. It can be switched by signal S35.

In this embodiment, the ATF control circuit 36 provides a mode check signal section in a time-division manner during the switching period of the reference pilot signal S11, which is given as a reference signal when the error signal forming circuit 3 performs the ATF tracking operation. The mode detection operation is performed using the section. i.e.
The ATF control circuit 36 is composed of a microcomputer, and supplies a 2-bit selection signal S45 to the switch circuit 17 of the reference pilot signal generation circuit 4 based on the rising and falling edges of the head switching signal RF-SW (FIG. 7A). At the same time, as shown in FIG. 7C, a reference pilot signal S11 having a sequence in which pilot frequencies _f1 to _f4 are repeatedly switched in sequence for each field section of the head switching signal RF-SW is obtained. frequency
A mode check signal section W31 of a predetermined length is provided at the beginning of the sections f ₁ , f ₂ , f ₃ , f ₄ and pilot frequencies f ₄ , f ₁ , f ₂ , f ₃ are inserted in sequence. The switch circuit 17 is controlled by a switch.

Assuming that when the tape is recorded and played back while running at the standard speed, it is in the just tracking playback state, the frequency signals f ₄ , f ₁ , f ₂ , inserted in the mode check section W31,
f ₃ is the frequency signal f ₁ , f ₂ ,
For f ₃ and f ₄ , the difference frequency Δf _B (=f ₄ ~ ₁ ), Δf _A
(=f ₁ ~ _{f 2} ), Δf _B (= f ₂ ~ ₃ ), and Δf _A (= f ₃ ~ ₄ ) are not generated in the multiplication output S12, so that the detection output S13 and the signal components are generated at the timing of the section W31. S14
are obtained (Fig. 7 D and E).

In contrast, the reference pilot signal S11
Regarding the original frequency signal of the ATF control signal section W32, when the head is just tracking, the pilot frequencies f ₁ , f ₂ , f ₃ , f ₄ of the reference pilot signal S11 and the like are shown in FIG. 7C. Since the reproduced pilot signals of the same frequency are obtained, the detection outputs S13 and S14 cannot be obtained, whereas when the head is shifted to the right or left, the difference signals Δf _A , Δf _B , Δf _A , Δf _B are obtained. Sequential output S
13, S14, S13, and S14 are obtained.

Therefore, when the head is in the straight tracking state, the output signal S15 of the subtraction circuit 24 alternately switches to negative and positive in the interval W31 and maintains the 0 level in the interval W32, as shown in FIG. 7I. .

ATF control circuit 36 is sample hold circuit 3
Sample and hold signal S47 for 1 and 33
and 2 as shown in FIG. 7 H and G as S48.
Give a phase signal. Here sample hold circuit 3
The sample hold signal S48 for 3 is in the section W
31, the logic level falls to "L" and causes the sample and hold circuit 33 to perform a sampling operation and send it out as it is as an output signal S32, and then during the period W.
32, the signal S48 rises to logic "H", so that the input signal that has arrived so far is held and continues to be sent out as the output signal S32. Therefore, the output signal S32 is the seventh
1 of the head switching signal RF-SW as shown in Figure K.
Each field section has a polarity and a magnitude corresponding to the signal level of the difference signal Δf _A or Δf _B included in the multiplication output S12.

This output signal S32 is compared with the reference level VR of the reference signal S33 in the comparator circuit 34, and thus a comparison output S34 having a period in which the signal rises to logic "H" is obtained in units of one field period of the head switching signal RF-SW. . This comparison output S34
The period of the logic "H" level section has a magnitude corresponding to the difference between the circulating frequency of the pilot frequencies _f1 to _f4 of the reference pilot signal S11 and the circulating frequency of the reproduced pilot signal S2. 36 can determine the difference between the recording and reproducing modes by determining the period of the comparison output S34.

On the other hand, the sample-and-hold signal S47 to the sample-and-hold circuit 31 rises to logic "H" during the period W31 and continues in the period W3 so as to cause the sample-and-hold circuit 31 to operate inversely to the circuit 33.
It falls to logic "L" during 2. In this way, the level of the output S16 during the section W32 is captured and sent out as the sample output S31, and at the same time, in the next section W31, the signal level of the signal S16 that has arrived so far is held and sent out as the hold output S31. It is made to do.

Here, the hold output S31 of the sample and hold circuit 31 is a switching circuit controlled by a switching control signal S46 (FIG. 7G) that switches the logic level in synchronization with the head switching signal RF-SW (FIG. 7A). 25, an inverting circuit 26 is installed every other field section.
Thus, an error signal S3 is sent to the output terminal of the switching circuit 25 by inverting the polarity of the output of the sample and hold circuit 33 by an inverter.

In this way, one of the head switching signals RF-SW
Mode check signal section W in the field section
During the section W32 excluding 31, an ATF tracking signal section is formed in which the ATF tracking operation described above with reference to FIG. Figure 7 J).

In this way, the ATF control circuit 36
1, the output S16 is input to the sample-and-hold circuit 33 to hold its signal level, and in the following period W32, the output S16 is input to the sample-and-hold circuit 31 to hold the signal level. The input signal and the ATF error signal S32 can be obtained time-divisionally separated from the output S16, and thus the ATF error signal S32 can be obtained separately from the output S16.
At the same time as the VTR is operated for ATF tracking, it is possible to determine whether the recording and reproduction modes match or mismatch based on the output S32 of the sample hold circuit 33 without adversely affecting the ATF tracking operation.

The reproducing circuit 38 includes a pair of recording/reproducing heads, that is, an A head 41A and a B head 41B, and the reproducing output is transmitted to the reproducing pilot signal amplifying circuit 4 through rotary transformers 42A and 42B, respectively.
3A and 43B, and its output is applied via contacts 44A and 44B of a switching circuit 44, and further through a buffer amplifier circuit 45 to a contact 37L of a reproduction pilot signal selection circuit 37. Here, the switching circuit 44 receives a head switching signal as a switching control signal.
RF-SW is applied, and when the heads 61A and 61B are scanning the tape, they are switched to contact 44A or 44B in synchronization with this.

The erase pilot signal selection circuit 39 also has an erase head 51, which is connected to a switching circuit 53 through a rotary transformer 52.
The switch circuit 53 is switched and controlled by a separate mode selection circuit (not shown), and when the mode selection circuit commands the playback mode, the playback mode contact
It is connected to the erase signal generation circuit 54 through REC, and when the regeneration mode is commanded, the regeneration contact
Reproduction pilot signal amplification circuit 55 through the PB side
It is connected to contact 37S of reproduction pilot signal selection circuit 37 via.

In this embodiment, the A head 41A and the B head 41B are arranged in the rotational direction K of the drum as shown in FIG.
The heads 41A and 41B are mounted on the rotating drum 61 with an angular interval of approximately 180° relative to the
Erase head 5 with an angular interval of approximately 90° between
1 is arranged.

Thus, along the outer peripheral surface of the drum 61, the arrow K2
The erase head 51 scans the tape 62 running in the direction of the tape 62 to erase the video signals recorded on the two adjacent tracks. The A head 61A scans the first track, and then the B head 41B scans the second track.
As a result of the accompanying scanning, video signals are recorded by the A head and the B head, respectively.

In this way, during playback, the erase head 51 used when recording a tape is transferred to the playback pilot signal selection circuit 37 via the playback pilot signal amplification circuit 55 by switching the switching circuit 53 (FIG. 6) to the playback side contact PB. Connected. On the other hand, the pair of recording and reproducing heads 41A and 41B each have a reproducing pilot signal amplifying circuit 43A during reproduction.
and 43B to the reproduction pilot signal selection circuit 37.

In the above configuration, on the tape recorded in the SP mode, as shown in FIGS. 9 and 10, there are tracks T11 to T14, T21 to T24, T3, which are formed by repeatedly recording pilot frequencies _f1 to _f4 in sequence.
1 to T34... are formed in sequence with the guard band G interposed between them.

When reproducing a video signal from this tape, the head 41A tracks an odd numbered track and scans the odd numbered track, and then the head switches and the B head 41B scans the even numbered track. However, before the pair of heads 41A and 41B scan the corresponding tracks, the erase head 51 scans across the two tracks.

That is, in the section Q1 of FIG. 9, the B head 41B is on the track T14 as shown in FIG. 10A.
A state is obtained in which the erase head 51 scans the first half of the next two tracks T21 and T22 while scanning the latter half of the track T21 and T22. Therefore, in this state, the B head 41B reproduces the pilot frequency _f4 from the track T14 as the reproduced signal S52 (FIG. 9B).
2), the state applied to the reproduction pilot signal amplification circuit 43B is obtained, and the erase head 5
A state is obtained in which a reproduced output S53 (FIG. 9C) obtained by reproducing the pilot frequencies f1 and _f2 recorded in tracks T21 and T22 from ₁ to 1 is supplied to the reproduced pilot signal amplifying circuit 55.

At this time, the reproduction pilot signal selection circuit 37
Since a tape recorded in SP mode is being played back, the mode detection signal S35 switches to the SP mode contact 37S side, and thus the playback output S53 of the erase head 51 is given to the pilot signal detection circuit 1 as the playback signal S1. It will be done. At this time, the reference signal generation circuit 4 generates the reference pilot signal S.
11 (FIG. 9D), a difference signal Δf _A is generated at the output S12 _of the multiplier circuit 14, which is transmitted to the difference signal detection circuit 2.
It is sampled and held in the sample and hold circuit 31 via the subtraction circuit 24 as the 0 side output S13. In this section Q1, the head switching signal RF-SW switches the switch circuit 25 to the contact a1 side, so that the error signal S3 (FIG. 9B) is obtained as a positive DC level.

Next, when entering the section Q2 in FIG. 9, the erase head 51 is moved to the track T21 as shown in FIG. 10B.
and move to the latter half of T22 and track T.
The A head 41A starts scanning the first half of the image.
Therefore, the pilot frequency _f1 recorded in the track T21 from the A head becomes the reproduction output S51 (9th
Figure B1) shows the reproduction pilot signal amplification circuit 43.
given to A. Also in this period Q2, the pilot frequencies f ₁ and f ₂ of tracks T21 and T22 are obtained from the erase head 51 as an output S53 (FIG. 9C), which is applied to the pilot signal detection circuit 1 as a reproduced output S1. However, in the section Q2, the head switching signal RF-SW
changes the logic level, so the content of the reference pilot signal S11 (Fig. 9D) changes to the pilot frequency _f2.
Switch to . Therefore, in this case as well, the difference signal Δf _A is obtained as the output S12 of the multiplication circuit 14, and this is sampled and held in the sample and hold circuit 31 as the output S13. However, in this section Q2, the logic level of the head switching signal RF-SW is being switched, so the switching circuit 25 switches to the contact a2 side in response to this, and thus the inverting circuit 26 inverts the negative level error output. signal S3
(Fig. 9E) is sent out.

Next, when entering section Q3 in FIG. 9, the A head 41A is scanning the track T21 as shown in FIG. 10C, but the erase head 51 is not scanning the tape. At this time, the reproduction output S51 of the pilot frequency _f1 is output from the A head 41A (Fig. 9B).
1) is obtained, but no reproduction output is obtained from the erase head 51 (FIG. 9C). Therefore, neither the difference signal Δf _A nor Δf _B is obtained at the output S12 of the multiplication circuit 14, and thus the error output S3 (FIG. 9E) becomes a 0 level state.

Then, when entering section Q4 in Figure 9, the area D in Figure 10 is reached.
As shown in FIG. 3, the B head 41B is scanning the track T22, but the erase head 51 is not scanning the tape. Therefore, the pilot frequency recorded in track T22 from head 41B
f ₂ is obtained as the reproduced output S52 (Fig. 9B
2), the pilot frequency is not obtained at the output S53 of the erase head 51 (FIG. 9C), and therefore the error signal S3 (FIG. 9E) remains at 0 level.

Next, when it comes to section Q5 in Fig. 9, E in Fig. 10 is reached.
As shown in , the B head 41B scans the latter half of the track T22 and the erase head 51 scans the adjacent
The state is such that the first half of the book tracks T23 and T24 are being scanned. At this time, the erase head 51
reproduces the pilot frequencies f ₃ and f ₄ recorded on tracks T23 and T24 (FIG. 9C), and the reference pilot signal S11 (FIG. 9D) sends out the pilot frequency f ₃ . Therefore, the difference frequency Δf _A (=f ₃ to f ₄ ) is obtained at the output S12 of the multiplication circuit 14, and this is sent out as a positive level error signal S3 (FIG. 9E) through the contact a1 of the switching circuit 25. Ru.

Next, when entering the section Q6 in FIG. 9, the erase head 51 is moved to the track T23 as shown in FIG. 10F.
and the latter half of T24 and A head 41A.
is in a state where it scans the first half of the track T23. Therefore, the pilot frequency reproduced from the erase head 51 is f ₃ and
f ₄ , whereas the reference pilot signal S11
Since the pilot frequency (FIG. 9D) is switched to f ₄ , a difference signal Δf _A is obtained at the output S12 of the multiplier circuit 14, and this is transmitted through the contact a2 of the switching circuit 25 to the negative level error signal S3 (the fourth It is sent as Figure 9E).

Subsequently, when entering section Q7 in FIG. 9, the erase head 51 stops scanning the track as shown in FIG. 10G, so the pilot frequency is no longer obtained at its output S53 (FIG. 9C), and thus an error signal is generated. The level of S3 (FIG. 9E) becomes 0 level.

Then, when entering section Q8 in FIG. 9, the erase head 51 does not scan the tape and the B head 41B scans the track T24, as shown in FIG. 10H. Therefore, the pilot frequency is not outputted to the output S53 (FIG. 9C) of the erase head 51, and therefore the level of the error signal S3 (FIG. 9E) becomes 0 level.

Thereafter, the operations in sections Q1 to Q8 are repeated in the same manner, and thus the error signal S3 is generated in sections Q1 and Q5.
An error signal S3 is obtained which has a positive level in the period Q2 and a negative level in the following sections Q2 and Q6. By the way, the absolute values of the positive and negative levels of this error signal S3 are almost equal when the heads 41A and 41B are just tracking, but when the capstan servo driven by the error signal S3 Since the system includes mechanical components such as a capstan motor, the response time is significantly longer than the length of sections Q1 to Q8, so in the end, the error signal is generated from the perspective of the capstan servo system as a whole. The state is equivalent to the result of integrating S3 (ie, 0). Eventually, the capstan servo system will be in the same state as when no error signal is applied, thus achieving a stable state.

The operations described above are for the state in which the heads 41A and 41B are just tracking the track, but if this has shifted to the right, for example, FIGS. 11A and B correspond to FIGS. 10A and 10B. Since the left end of the erase head 51 cannot face the entire width of the track T21, the signal level of the pilot frequency _f1 component of the output signal S53 decreases.

Therefore, when the difference output S12 between the output S53 of the erase head 51 and the reference pilot signal S11 is obtained in the section Q2, Δf _A included in the output S12 is obtained.
The signal level of the error signal S3 decreases, and the integral value of the negative signal portion of the error signal S3 decreases by this decrease.
In the end, the signal level of the error signal S3 effectively increases from the 0 level in the positive direction. Therefore, at this time, the capstan servo system delays the phase of the tape so as to cancel out this increase, thereby returning the tape to the straight tracking state described above with respect to FIGS. 10A and 10B.

The same applies to the case of left shift.

The above describes the case where playback is performed in SP mode, but when playback is performed in LP mode, tracks T11 to T14, T21 are
～T24, T31～T41...Guard band G between
At this time, the erase head 51 is in a state where it straddles four tracks, but since the reproduction pilot signal selection circuit 37 is switched to the LP mode side contact 37L, the erase head 51 is in a state where it straddles the four tracks. 41B outputs S51 and S5
The ATF tracking error signal forming operation is executed in the error signal forming circuit 3 based on the playback output obtained as 2, and thus the video signal can be played back while the heads 41A and 41B are just tracking each track. . At this time, the output S53 of the erase head 51 is not used.

In addition, in order to perform the above operation, the mode detection circuit 3
2 detects when reproduction is performed in a mode different from the recording mode and outputs a detection output signal S34.
is applied to the ATF control circuit 36 to generate the mode detection signal S.
35, the reproduction pilot signal selection circuit 37 is operated to switch the head so that the recording mode always matches the reproduction mode.
It is designed to be able to execute ATF tracking control.

As described above, according to the configuration shown in FIG. 6, when reproducing a video signal recorded in a mode in which a wide guard band is formed between recording tracks formed on a tape, an erase head is used. By obtaining a pilot signal from an adjacent track, an error signal can be reliably generated, and thus the recording/reproducing head can perform just tracking. In this way, it is not necessary to provide a recording/reproducing head for each mode, and thus reproduction in a plurality of modes can be reliably performed without making the structure around the rotating drum large and complicated.

Incidentally, when trying to obtain an ATF tracking error signal from the recording/playback head based on the pilot signal recorded on the adjacent track, when the guard bands GL and GR are wide, the ATF tracking error signal is sent from the head HE as shown in Figure 12. The error signal ER obtained based on the reproduced pilot signal is determined by the just tracking position in the characteristic curve when the tracking deviates to the right or left from the just tracking position 0 of the track T0 to be tracked. It is generally considered that the differential coefficient of the curve passing through becomes close to 0, which makes it difficult to perform straight tracking at the 0 point.
However, according to the configuration shown in FIG. 6, since the tracking error signal is obtained using the erase head, it is possible to effectively avoid such problems in the vicinity of the 0 point and in the case of just tracking.

Therefore the video signal obtained from the playback head HE
YFM sensitivity can also be maintained at a high value. Incidentally, the relationship between the sensitivity of the video signal YFM and the tracking deviation is quite sensitive as shown in Figure 13.
Video output even with slight tracking deviation
Although there is a risk that the YFM may deteriorate, the configuration shown in FIG. 6 can realize just tracking with high sensitivity, so this risk can be effectively avoided.

FIG. 14 shows another embodiment of the present invention, and as shown by assigning the same reference numerals to corresponding parts as in FIG. The reproduced pilot signals S53A and S53B obtained from each head 61A and 61B (C1 and C2 in FIG. 15)
The error signal S3 is corrected based on the difference signal between the pilot frequency of the reference pilot signal S11 and the pilot frequency of the reference pilot signal S11.

In this case, the erase heads 61A and 61B are provided in the erase pilot signal circuit 39 of FIG. 6, and their output signals S53A and S53B maintain a phase difference of 90° with respect to the head switching signal RF-SW (FIG. 15A). The reproduction output S1 to the pilot signal detection circuit 1 can be obtained while being switched alternately. The rest of the structure is the same as that shown in FIG.

In the above configuration, the signals of each part when playing back in SP mode are shown in FIG. 15 in correspondence with FIG.
The relationship between A and 61B and each track is shown in FIG. 16 in correspondence with FIG. 10. In this case, in the section Q1, as shown in FIG. 16A, the pilot frequency _f1 is obtained from the track T21 by the erase head 61A, and a difference signal from the reference pilot signal _f1 is obtained. From the erase head 61B, a reproduced output S53B of the pilot frequency _f2 is obtained, and a difference signal between this and the pilot frequency _f2 of the reference pilot signal S11 is obtained. Erase head 6
1A to output S53A at pilot frequency _f1 .
Based on this, the reference pilot signal S11 is
The difference signal from the pilot frequency _f1 is obtained. Thus, in the just tracking state, the level of the ATF tracking error signal S3 becomes 0 level as shown in FIG. 15E.

In this way, erase heads 61A and 6
1B, it is possible to always obtain outputs S53A and S53B consisting of pilot frequencies _f1 to _f4 , so ATF tracking can be applied at all times.
In this way, the same effect as in the above case can be obtained.

17 and 18 show an embodiment in which a tape recorded in LP mode is played back using the head configuration shown in FIG. 14. In correspondence with FIG. 15, FIG. 17 shows the various parts. In this case, two types of pilot frequencies f 1 and 2 recorded on two adjacent tracks from the erase heads 61A and 61B, respectively, are shown in _FIG . f ₂ , f ₂ and
The pilot frequencies of f ₃ , f ₃ and f ₄ , f ₄ and f ₁ , ... are obtained alternately and the reference pilot signal S is generated based on these.
11 to obtain a difference signal. As described above, according to the configuration shown in FIG. 14, ATF tracking operation can be reliably realized even when playing back a tape recorded in LP mode.

〔Effect of the invention〕

As described above, according to the present invention, the head used for erasing information as a flying erase head during recording is also used as a head for obtaining a reproduction pilot signal during reproduction, thereby achieving a simple configuration. Definitely ATF
A tracking control device capable of performing a tracking operation can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the principle configuration of the ATF tracking control device, Fig. 2 is a schematic diagram showing its tracking pattern, Fig. 3 is a signal waveform diagram showing signals of each part in Fig. 1, Figs. Fig. 5 is a schematic diagram showing changes in the track pattern when switching the recording mode, Fig. 6 is a block diagram showing an embodiment of the tracking control device according to the present invention, and Fig. 7 shows signals of each part thereof. Signal waveform diagram, Figure 8 is a schematic diagram showing the arrangement of the head, Figure 9 is a signal waveform diagram showing the signals of each part in Figure 6, Figures 10 and 11 are the position of the head in each time interval. FIGS. 12 and 13 are characteristic curve diagrams showing changes in the sensitivity of the error signal and video signal with respect to tracking deviation of the head. FIG. 14 is a head arrangement according to another embodiment of the present invention. Figure 15 is a signal waveform diagram showing the signals of each part in that case, Figure 16 is a diagram showing the position of the head in each time interval, and Figure 17 is a diagram of each part in other modes. A signal waveform diagram showing the signals, and FIG. 18 is a schematic diagram showing the position of the head in that case. 1...Pilot signal detection circuit, 3...Error signal formation circuit, 4...Reference signal generation circuit, 14...
... Multiplication circuit, 20, 21 ... Difference signal detection circuit, 2
2, 23...DC conversion circuit, 24...Subtraction circuit, 2
5...Switching circuit, 32...Mode detection circuit, 37
... Regeneration pilot signal selection circuit, 38 ... Regeneration circuit, 39 ... Erase pilot signal circuit, 4
1A, 41B... Recording/playback head, 51... Erase head.

Claims (1)

[Claims] 1 Recording a plurality of pilot signals with different frequencies onto tracks formed in sequence on a recording medium by a recording/reproducing head accompanying an erasing head,
The pilot signal is reproduced from the track to obtain a difference frequency component between the reproduced pilot signal and the reference pilot signal, and a tracking error signal for the tracking position of the recording head is obtained in accordance with this difference frequency component. A tracking control device characterized in that the pilot signal of the track is reproduced using the erase head during reproduction.