JPH0461019A - Dynamic tracking device - Google Patents

Abstract

PURPOSE:To reduce a main signal recording band and to restrain the deterioration in the S/N of a regenerative signal and a pilot signal by arranging two heads equipped with the gap of azimuth angles different each other on the electric-machine conversion actuator of a rotation cylinder while making the height differ by nearly 1 track pitch. CONSTITUTION:Two heads 1A/1B with different azimuth angles are arranged on one electric-machine conversion actuator 4 while making the height differ by one track pitch, two kinds of pilot signals are recorded on the main signal of one head and the main signal is recorded on the the other head at the time of recording the cross talk component from the adjacent tracks of right and left reproduced by the other head are separated and extracted to be compared, and outputs tracking error amount. The pilot signal reproduced by one head are extracted, tracking error direction is obtained, the tracking error amount is generated from this tracking error direction to be supplied to the actuator 4. Thus, the reduction of the main signal recording band and the deterioration of the S/N of the pilot signal can be restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a dynamic tracking device in a helical scan type magnetic recording/reproducing device.

(Prior Art) Conventionally, as is well known, video tape recorders (hereinafter referred to as VTRs) employ a tracking control method in which the locus of a playback head is aligned with a recording track. This tracking control method records a control signal on the tape with a period equal to the rotation period of the rotary head in the longitudinal direction of the magnetic tape when recording a signal, and when the tape is played back, the control signal is reproduced at a constant period. It is designed to control the feeding speed of the magnetic tape.

On the other hand, home VTRs are required to be smaller, and this demand for smaller size naturally includes the smaller size of the magnetic tape cassette itself. However, even if such magnetic tape cassettes are miniaturized, it is necessary to ensure the recording time itself, so high-density recording has become necessary.

When performing high-density recording in this way, there are two ways to consider: increasing the density in the head running direction (recording track line direction) and increasing the density in the direction perpendicular to this (recording track width direction). However, the former method cannot be expected to significantly improve due to the limitations of short wavelength recording due to the performance of the head and magnetic tape, so the latter method will be adopted.

This requires even higher accuracy in tracking control, which has become difficult with conventional tracking control methods.

Under such circumstances, in an 8mm VTR with a narrow track pitch of 20 μm or 10 μm, during recording, a sine wave of a constant frequency is used for the main signal, and the frequency is varied between adjacent tracks, so that the main signal is recorded every 4 tracks. The ATF (AUt) is a four-frequency pilot method that frequency-multiplexes pilot signals that are the same and controls the feeding speed of the magnetic tape so that the Talostok components of the pilot signals from the left and right adjacent tracks are equal during playback.
og+atic Track Findina) Adopt the system X7- system.

In this ATF system, when tracking deviation occurs, there is a difference between the pilot signal components from the adjacent tracks on the left and right, and the frequency sequence of the recorded pilot signal causes tracking deviation to either the left or the right. You can find out if there are any.

In such a four-frequency pilot ATF system, each pilot signal must be discrete enough to be separated during playback, and as a result, the frequency band occupied by the pilot signal becomes wide, leading to a reduction in the main signal recording band and The reproduced main signal and pilot signal S/N may deteriorate, or the pilot sequence may become complicated.

(Problem to be Solved by the Invention) In the above-mentioned four-frequency pilot ATF system, each pilot signal must be discrete enough to be separated during reproduction, and therefore the frequency band occupied by the pilot signal is wide. This causes problems such as a reduction in the main signal recording band, deterioration of the reproduced main signal and pilot signal S/N, or a complicated frequency sequence of the pilot signal.

The present invention has been made in view of the above-mentioned problems, and it suppresses the reduction of the main signal recording band and the deterioration of the S/N of the reproduced main signal and pilot signal, and also provides high precision with a simplified frequency sequence of the pilot signal. The purpose of this invention is to provide a dynamic tracking device.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides two heads having gaps of mutually different azimuth angles and disposed on an electro-mechanical conversion actuator of a rotary cylinder with approximately one track pitch difference in height. a first recording means for supplying a signal obtained by alternately multiplexing two types of distinguishable pilot signals to an information signal to the head at the one azimuth angle during recording; and a head at the other azimuth angle. A recording circuit having a second recording means for supplying only information signals to the head, and detecting the two types of pilot signals reproduced from the head at the other azimuth angle during reproduction, and comparing their amplitude components. A control direction detection means for detecting a head position control direction, a control signal generation means for generating a tracking error amount from the two types of pilot signals reproduced from the head at one azimuth angle, an output of the control signal generation means and the control. The tracking error generation circuit has a signal forming means that can change the phase of the amount of tracking error according to the output of the direction detecting means and supply it to the electro-mechanical conversion actuator.

Here, the control signal generation means of the tracking error generation circuit causes the electro-mechanical conversion element to control the signal until the amplitude component of one of the two types of pilot signals reproduced by one of the heads reaches a predetermined value or more. The device is characterized in that it includes means for making the applied voltage change in one direction.

Further, the control direction detection means of the tracking error generation circuit supplies a tracking error to the electro-mechanical conversion element until the amplitude components of both of the two types of pilot signals reproduced by the other head become equal to or less than a predetermined value. The present invention is characterized in that it includes a first detection circuit that outputs a switching signal whose amount changes in one direction.

Furthermore, the control direction detecting means of the tracking error generation circuit supplies a tracking error to the electro-mechanical conversion element until the difference between the amplitude components of the two types of pilot signals reproduced by the other head becomes equal to or less than a predetermined value. It is provided with a second detection circuit that outputs a switching signal whose amount changes in one direction.

(Function) With the above-described configuration, two heads with different azimuth angles and different one-track pitch heights are arranged on one electro-mechanical conversion actuator, and during recording, two types of main signals are sent to one head. Record the pilot signal on one head and the main signal on the other head.

Further, during reproduction, the crosstalk components of the pilot signals from the left and right adjacent tracks reproduced by the other head are separated and extracted, compared, and the amount of tracking error is output. Further, a pilot signal reproduced by one head is extracted to obtain a tracking error in one direction, and a tracking error amount is generated from this tracking error direction and supplied to the actuator.

As a result, while maintaining a highly accurate tracking system, a reduction in the main signal recording band and deterioration of the S/N of the reproduced main signal and pilot signal can be suppressed with a simplified pilot sequence.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1(a) is a block diagram showing an embodiment of the dynamic tracking device of the present invention, and FIG. 1(b) is a block diagram showing the main parts of the reproducing head of the same embodiment.

In FIG. 1, heads IA and IB have gaps with different azimuth angles. This head LA, I
B is approximately 1 with the member 2 at a distance X in the head rotation direction F.
Different track pitch heights Y are arranged on the free ends of electro-mechanical conversion actuators 4 fixed to the rotary cylinder 3, thereby forming a rotary head 5. The actuator 4 is a piezoelectric bimorph type actuator in which a forged piezoelectric element that expands and contracts according to the applied voltage is bonded with the voltage polarity reversed and is displaced up and down according to the applied voltage.

During recording, the heads IA and IB of the rotary head 5 are
A recording signal is supplied from a recording circuit 6. This recording circuit 6 has a head I at one of the above azimuth angles.
Two distinguishable approximately constant frequencies f1 in the main signal for A
, f2, and a second recording means 8 for supplying only the main signal to the head IB at the other azimuth angle.

At the time of reproduction, the head IA of the rotary head 5.

The reproduction signal reproduced from the IB is input to the tracking error generation circuit 9, and the tracking error generation circuit 9 outputs a tracking error amount for driving the actuator 4.

This tracking error generation circuit 9 detects the crosstalk components Ca and Cb of the two types of pilot signals reproduced from the head IB at the other azimuth angle, and compares their amplitude components to detect a switching signal. a control direction detection means 10, a control signal generation means 11 for generating a tracking error amount from the two types of pilot signals Pa and Pb reproduced from the head IA at one azimuth angle, and an output of the control signal generation means 11. and a signal forming means 12 that can change the phase (positive or negative) of the tracking error amount according to the output of the control direction detecting means 10 and supply it to the actuator 4.

FIG. 2 is a block diagram showing the configuration of the recording circuit.

The second recording means 8 includes a video signal input terminal 15, an A/D converter 16, a timing signal generator 17, a high-efficiency encoding circuit 18, a correction code addition circuit 19, an interleave circuit 20, and a synchronization It has a signal addition circuit 21, a digital modulation circuit 22, and a B channel recording amplifier 23,
It is structured as follows. That is, the video signal is input from the video signal input terminal 15 to the D/A converter 16 and the timing signal generator 17. Timing signal generator 1
In step 7, a clock is generated based on the video signal and output to each block. On the other hand, the video signal input to the D/A converter 16 is converted into a digital signal according to the timing output from the correction code adding circuit 19, and is input to the high efficiency encoding circuit 18, where it is subjected to pit rate reduction processing. receive.

This is because digital signals have a larger amount of information than analog signals, and in order to reduce the amount of tape consumed per unit time, the redundancy of the video signal is used to reduce the amount of data l to be transmitted. Assume that DPCM is used. The video signal whose bit rate has been reduced by DPCM processing is input to a correction code adding circuit 19, where a correction code is added for error correction processing during playback, and an interleave circuit 20 improves error correction capability at the time of playback dropout. For this purpose, we perform a block-by-block sorting process,
Furthermore, one field of video signal data is divided into two signal systems so that it can be recorded separately on two tracks. A synchronization signal addition circuit 21 adds synchronization data to the two interleaved video data, and a digital modulation circuit 22 rearranges the data so as to suppress DC and low frequency components. A rotary transformer that does not transmit a DC component is used as a transmission means to the rotary disk 5, and in magnetic recording, if the recording signal frequency is too low, the reproduction output will decrease.
This is done in order to suppress mutual interference with the main signal during reproduction when the low frequency tracking pilot signal described below is frequency multiplexed and recorded with the main signal. One of the two digitally modulated video data is supplied to the head IB via the B channel recording amplifier 23.

The first recording means 7 includes an f1 generator 24, an f2 generator 25, a changeover switch 26, an adder 27, and an A channel recording amplifier 28, and is configured as follows. That is, the other of the two digitally modulated video data is input to the adder 27. f1 generator 24,
The pilot signals of two types of frequencies f1 and f2 from the f2 generator 25 are input to the changeover switch 26, and the rotary head 5 is outputted from the timing signal generator 17 in phase synchronization with the rotation period of the rotary head 5. Adder 2 switches fl and f2 every time the tape is scanned.
Supply to 7. The other of the two lines of video data is input to the adder 27, which is multiplexed on the frequency axis with pilot signals f1 and f2 that switch each time the rotary head 5 scans the tape, and is sent to the A channel recording amplifier 28. Supplied.

The recording signal output from the A channel recording amplifier 28 is supplied to the head IA.

Note that a tape 30 is wound around the rotating head 5 at a predetermined angle, and this tape 30 is wrapped around the capstan 31,
It is designed to run between pinch rollers 32.

The capstan 31 is rotationally driven by a capstan motor 33.

A clever changeover switch 34 sets the actuator 4 to ground potential during recording and connects the tracking error generation circuit 9 to the ground potential during playback.
It is possible to supply the amount of tracking error from .

Next, the frequency spectrum of the signal input to the digital modulation circuit and each channel recording amplifier will be explained using FIG.

FIG. 3(a) shows the input signal spectrum of the digital modulation circuit 22, and shows that random digital data has direct current and low frequency components.

As mentioned above, the rotary head type magnetic recording/reproducing device does not have the ability to record or reproduce this direct current and low frequency components. Therefore, by rearranging the digital data in the digital modulation circuit 22,
Record the spectrum as shown in b) with DC and low frequency components suppressed. The signal shown in FIG. 3(b) is amplified by the B channel recording amplifier 23, and then supplied to the head IB via a rotary transformer (not shown) to be recorded on the tape.

On the other hand, on the first recording means 7 side, the low frequency pilot signal f1 or f2 is frequency-multiplexed with respect to the signal shown in FIG. 3(b), and the signal shown in FIG. 3(C) or FIG. 3(d) is The signal is then input to the A channel recording amplifier 28.

The signal amplified by the A channel recording amplifier 28 is supplied to the head IA via a rotary transformer (not shown) and recorded on the tape.

The rotary head 5 rotates in synchronization with the input video signal, and data for one field of the input video signal is divided into two tracks and recorded, and the head 5 rotates in synchronization with the input video signal. Since two tracks are formed at the same time every time it is scanned, its rotational frequency is the same as the field frequency of the video signal, which is 60 [Hz].

By the way, the phase of the recorded video signal is adjusted in advance to the rotational phase of the head relative to the tape 30, such that the tape 30 is wound around the rotating rod 5 at an angle of 180 degrees. The feeding speed of the tape 30 is controlled in synchronization with the input video signal and at an appropriate track pitch. A track pattern on the tape 30 recorded in this manner is shown in FIG.

FIG. 5 is a block diagram showing the configuration of a reproduction circuit including a tracking error generation circuit.

In FIG. 5, during reproduction, the rotary head 5 is controlled to rotate at a constant cycle, and the rotational speed is almost the same as that during recording. On the other hand, the feeding speed of the tape 3o is controlled to be the same speed as the track pitch during recording.

In this state, the heads LA and IB mounted on the actuator 4 obtain reproduction output according to the magnetization pattern recorded when scanning the tape 3o. This playback output is input to an A-channel preamplifier 41 and a B-channel preamplifier 42 via rotary transformers, amplified, and then supplied to a tracking error generation circuit 9 and a video signal processing system 40.

Here, the video signal processing system 40 includes equivalent circuits 43A, 43
B, clock regeneration circuit 44, and digital demodulation circuit 4
5, a deinterleave circuit 46, and an error correction circuit 4
7, an apparatus circuit 48, and a D/A conversion circuit 49, which process the video signal and output it as a video signal from the video signal output terminal 5o.

Further, the tracking error generation circuit 9 has the following configuration.

That is, the control direction detection means 10 of the tracking error generation circuit 9 detects the tracking error supplied to the actuator 4 until the amplitude components of both of the two types of pilot signals reproduced by one head IA become equal to or less than a predetermined value. The first detection circuit 51 outputs a switching signal whose amount changes in one direction, and the actuator operates until the difference between the amplitude components of the two types of pilot signals reproduced by one head IA becomes equal to or less than a predetermined value. 4, which outputs a switching signal in which the direction of change in the amount of tracking error supplied to 4 is one direction.
A detection circuit 52 is provided.

The first detection circuit 5 of the control direction detection means 10
1 is composed of an fI BPF 53A, an f2 BPF 54A, a detection circuit 55, a detection circuit 56, an adder 57, and a comparator 58. Further, the second detection circuit 52 has fI
It is composed of a BPF 53A, an f2 BPF 54A, a detection circuit 55, a detection circuit 56, comparators 59 and 60 for comparison with the voltage V, an AND gate 61, and an OR gate 62.

fI BPF53A, f2 BPF54A are input to the A-nod playback output signal, the frequency f1ζf2 component is extracted, and the A head is turned on +azimuth track).
The pilot signal component of fl or f2 is extracted according to the racked portion, and the pilot signal component of fl or f2 is extracted and sent to each detection circuit 55,
6 and is detected. Further, the pilot signals Pa and Pb of frequencies f1 to f2 detected by the detection circuit 55 and the detection circuit 56 are input to the adder 57 and to each comparator 59 and 60. In the adder 57,
The frequency fl of the pilot signal and the f2 component are added to the comparator 58, and a positive voltage equal to the added component is supplied to the comparator 58, and if the f2 component is large, a negative voltage corresponding to the added component is supplied to the comparator 58. The comparator 58 compares it with the O(V) reference voltage, and depending on the output of the adder 57, a digital signal of "H" level if the f1 component is large and "L" level if the f2 component is large is sent to the OR gate 62. supplied to

On the other hand, the detected outputs of the fl and f2 components given to the comparators 59 and 60 are respectively compared with the reference voltage V, and if it is larger than the reference voltage ■, the digital The signal is output to the AND gate 61, and the AND gate 61 turns "H" if the detection output levels of the frequency f1 and f2 components are both smaller than the reference voltage ■.
If either level is larger than the reference voltage V, an L'' level digital signal is output to the OR gate 62.
Are the detection output levels of both components smaller than the reference voltage ■?
Or, when the f1 component is larger than the f2 component, “H”
A level digital signal is output as a switching signal.

In addition, the control signal generating means 11 in the tracking error generating circuit 9 controls the actuator until the amplitude component of one of the two types of pilot signals reproduced by the other IB reaches a predetermined value or more. It has a structure in which the direction of change of the amount of tracking error applied to 4 is one direction, and specifically, it is structured as follows. In other words, the control signal generation means 11 uses the fl BPF63B
, f2 BPF64B, detection circuit 65, detection circuit 66,
It includes an adder 67 and a polarity inversion circuit 68.

The reproduction output signal from head IB input to fl BPF63B and f2 BPF64B has a frequency fl
, the f2 component is extracted, and if it is off-rack, the crosstalk components Ca and Cb of the pilot signal of fl or f2 are extracted from the adjacent positive azimuth track, and are manually detected by the detection circuit 65 and the detection circuit 66. be done.

The head IB detected by the detection circuit 65 and the detection circuit 66
Pilot signal crosstalk component C of fl, f2 by
a.

cb is subtracted by an adder 67, and if the f1 component is large, a corresponding positive voltage is supplied to the signal forming means 12, and if the f2 component is large, a corresponding negative voltage is directly supplied to the signal forming means 12, and the polarity inverting circuit 68 supply to.

This polarity inversion circuit 68 inverts the voltage polarity of the output of the adder 67, and outputs a negative voltage corresponding to the f1 component to the signal forming means 12 if the f2 component is large, and a positive voltage corresponding to the large f2 component to the signal forming means 12. do.

The signal forming means 12 includes a changeover switch 71 and an integration circuit 72.
, and an amplifier 73.1. , is structured as follows. A switching signal from the control direction detection means 10 switches the changeover switch 71. The changeover switch 71 is for head IB.
The pilot signal crosstalk components fl, f2
The addition result is selected between normal rotation and inversion, and is supplied to the integrating circuit 72. The integrating circuit 72 integrates the integrated signal with a time constant depending on the response speed of the actuator 4, and then transmits the integrated signal to the integrating circuit 7.
2, the voltage is amplified to the drive voltage of the actuator 4, and is supplied to the actuator 4 via the changeover switch 34. here,
The changeover switch 34 is on the recording side during recording operation, and the electrode of the actuator 4 is at the reference potential (ground potential).As a result, the actuator 4 is not displaced, and the phase of each head relative to the tape is also the same as the tape 30. The track pattern shown in FIG. 4 can be formed without any change except for the feeding.

The operation of the embodiment configured as described above will be explained using FIG. 6.

Head LA during off-track with the configuration of heads IA, IB and actuator 4 according to this embodiment.

There are four types of phase relationships between the IB and the recording track, and these are shown in cases (1) to (4) in Figure 6. In this figure, when the polarity of the voltage applied to the actuator 4 is positive, the right side , when the negative electrode is on the left side, the head IA,
It is assumed that the phase of IB moves with respect to the recording track.

[Case (1)] In case (1), the pilot signal frequency of the azimuth track is fl, and the head IA is slightly off-track to the right of the track. At this time, the crosstalk component of the pilot signal reproduced by head IB has a frequency of f2. At this time, the f2 component reproduced from head IB satisfies f2 > fl. therefore,
The adder 67 outputs a negative tracking error voltage corresponding to the difference between the f1 and f2 components.

On the other hand, the pilot signal component reproduced by the head IA is f
1, and fl>f2 holds true for the f1 component from head IA. Therefore, the output voltage polarity of the adder 67 becomes positive, and the output of the comparator 58 becomes "H" level. As a result, the output of the OR gate 62 becomes "H" level regardless of the output of the AND gate 61, the changeover switch 71 selects the normal output of the adder 67, and a negative voltage is applied to the actuator 4. Become. As a result, head IA and head IB are moved to the left in the drawing. This puts you on track.

[Case (2)] In case 2, the pilot signal frequency of the same positive azimuth track is fl, and the head IA is slightly off-track to the left. At this time, the crosstalk component of the pilot signal reproduced by head IB is fl,
Crosstalk component element 1 reproduced by head IB > f2
becomes. Therefore, from the adder 67, the f1 component and f2
A positive voltage is output according to the difference between the two components.

On the other hand, the pilot signal component reproduced by the head IA is f
l, and the regenerated molecule 1 from head IA is fl >
f2 holds true. Therefore, the output voltage polarity of the adder 57 becomes positive, and the output of the comparator 58 becomes "H" level. As a result, the output of the OR gate 62 becomes "H" level regardless of the output of the AND gate 61, the output of the adder 67 is selected by the changeover switch 71, and a voltage corresponding to the positive tracking error amount is applied to the actuator 4. That will happen. As a result, the heads IA and IB are moved to the right in the drawing, so that they are on-track.

[Case (3)] In case (3), the pilot signal frequency of the azimuth track is f2, and the head IA is slightly off-track to the right in the drawing. At this time, the crosstalk component of the pilot signal reproduced by head IB is fl, and the crosstalk component element 1 > f
It becomes 2. Therefore, the adder 67 outputs a positive voltage according to the difference from the f2 component.

On the other hand, the pilot signal component reproduced by the head IA is f
2, and the regenerated molecule 1 from head IA is fl <
f2 holds true. Therefore, the output voltage polarity of adder 57 becomes negative, and the output of comparator 58 becomes "L" level. On the other hand, if the detection output of component 2 of the pilot signal is greater than the reference voltage V, the output of the comparator 59 is “L”.
" level, and the output of the AND gate 61 also becomes "L" level. As a result, the output of the OR gate 62 becomes "L" level.
" level, and the changeover switch 71 selects the inverted output of the polarity inversion circuit 68. This tracking error amount voltage is applied as a voltage with negative polarity, and the heads IA and IB are on the left side in the figure. Move to.

[Case (4)] In case (4), the pilot signal frequency of the azimuth track is approximately 2, and the head IA is slightly off-track to the left.

At this time, the crosstalk component of the pilot signal reproduced by head IB is f2, and fl<f2 holds true for the regenerated molecule 2 from head IB.

Therefore, the adder 67 outputs a negative voltage corresponding to the difference from the f1 component.

On the other hand, the pilot signal component reproduced by the head IA is f
2, and 1 is the reproduced component from the head IA, fl <
f2 holds true. Therefore, the output voltage polarity of adder 57 becomes negative, and the output of adder 57 becomes "L" level. Furthermore, assuming that the detection output of the pilot signal f2 is greater than the reference voltage V, the output of the comparator 59 is ``
The output of the AND gate 61 becomes “L” level.
level. Therefore, the output of the OR gate 62 is “
The changeover switch 71 selects the inverted output of the adder 67. Therefore, the actuator 4 has
A voltage with a positive tracking error amount is applied. Therefore, heads LA and IB move to the right in the drawing.

As described above, when off-tracking in the four types of cases, the head is controlled in the direction of the nearest track of the same azimuth, and in cases (1) and (2), the dotted line in case (5), case (3), In case (4), it converges to the solid line of case (5) and the on-track noise occurs.

Also, if you are off-track, cases (1) to (4)
) as well as reverse polarity azimuth as shown in case (6),
Alternatively, the heads LA and IB may be located in the vicinity thereof. At this time, since the pilot signal reproduced by the head IA is obtained from the left and right tracks, the adder 5
Since the output level of the actuator 7 becomes very small and the output of the comparator 58 and the output of the OR gate 62 become unstable, in the worst case, the switching signal of the changeover switch 71 changes frequently, and the polarity of the voltage applied to the actuator 4 changes accordingly. It changes accordingly, and it may not converge forever, or it may become stable on a reverse azimuth track.

For this reason, unless the detected output of the fl and f2 components of the pilot signal output from the head IA exceeds a certain level, the switching signal of the changeover switch 71 is fixed to one side, and the head is forcibly moved in the on-track direction. Take control.

At the positions of heads IA and IB shown by solid lines in case (6), head IB reproduces pilot signal crosstalk component 2, and adder 67 outputs a negative voltage according to the difference from the f1 component. .

Furthermore, the pilot signal components of fl and f2 are minutely reproduced from the head IA, and the output of the adder 57 also becomes minute, and as a result, the output of the comparator 58 becomes unstable. On the other hand, f
The detected outputs of the l and f2 components are compared with the voltage V by the comparators 59 and 60, and assuming that both detected outputs are smaller than the voltage ■, the outputs of the comparators 59 and 60 are both at "H" level,
The outputs of the AND gate 61 and the OR gate 62 also become "H" level, and the changeover switch 71 forces the adder 67
output is selected, a negative voltage is applied to the actuator 4, and the heads IA and IB are moved to the left.

Here, if the reference voltage (2) is set to an appropriate value and the output of the comparator 59 and the output of the AND gate 61 go to "L" level, case (1) is reached and on-track is achieved.

At the dotted head position in case (6), head IB reproduces crosstalk component 1, and adder 67 reproduces f.
A positive voltage is output according to the difference between the two components. Similarly, the selector switch 71 forcibly selects the output of the adder 67, a positive voltage is applied to the actuator 4, and the actuator 4 moves to the right in the figure. This results in case (2) and on-track.

With the above configuration, sufficient reproduction output can be obtained by the on-track head IAIB.

In this embodiment, as a process when the amount of off-track is large, the moving direction of the head is fixed until the pilot signal component reproduced by the head IA reaches a predetermined level or higher. The head I
This can be achieved by reducing the crosstalk component of the pilot signal reproduced by the head IB to a predetermined level or lower, or by reducing the level difference between the reproduced crosstalk components fl and f2 by the head IB to a predetermined level or lower.

The present invention can be applied even if the head track width is slightly larger or smaller than the track pitch, and can be applied even if the height difference between the two heads on the head actuator is slightly offset to either side.

In addition, although the method of multiplexing the pilot signal to the main signal was frequency multiplexing, other methods such as time division multiplexing and changing the appearance rate of "1" and "0" in the digital signal can be used to modify the spectrum of a specific frequency. The two types of pilot signals may be distinguished by different frequencies here, but they may also be distinguished by changing the phase, and the present invention is not limited to this method.

Furthermore, although the actuator 4 is of a piezoelectric bimorph type,
An electrostrictive bimorph, a moving coil, or the like may also be used.

〔Effect of the invention〕

As described above, according to the present invention, by simply recording two types of pilot signals, tracking control can be performed to the nearest track during playback, regardless of the position of the head with respect to the recording track. Since no signal is recorded and the frequency bandwidth occupied by the pilot signal on the other track is narrow, interference with the main signal can be minimized, and the pilot signal can be recorded,
This has the advantage that the sequence during playback can be simply configured.

[Brief explanation of drawings]

FIG. 1(a) is a block diagram showing an embodiment of the present invention.
Figure (b) is a block diagram showing the configuration of the head and head actuator used in the same example, Figure 2 is a block diagram showing details of the recording circuit of the same example, and Figure 3 shows the recording signal frequency spectrum. FIG. 4 is an explanatory diagram showing the recording track pattern on the tape, FIG. 5 is a block diagram showing the reproduction circuit of the same embodiment, and FIG. 6 is an explanatory diagram for explaining the tracking operation during reproduction. be. IA, IB...head, 3...rotating cylinder, 4.
... Actuator, 5... Rotating head, 6... Recording circuit, 7... First recording means, 8... Second recording means, 9... Tracking error generation circuit, 10... Control Direction detecting means, 11... Control signal generating means, 12... Signal forming means. -do θ Fig. 5 - and → Fig. 6

Claims (4)

[Claims] (1) A rotary head in which two heads having gaps of different azimuth angles are arranged on an electro-mechanical conversion actuator of a rotary cylinder with approximately one track pitch difference in height; a first recording means for supplying a signal in which two types of distinguishable pilot signals are alternately multiplexed with an information signal to a head having an azimuth angle of A recording circuit having two recording means, and a control direction detection device that detects the two types of pilot signals reproduced from the head at the other azimuth angle during reproduction, and compares their amplitude components to detect the head position control direction. control signal generation means for generating a tracking error amount from the two types of pilot signals reproduced from the head at one azimuth angle; A dynamic tracking device comprising: a tracking error generation circuit having a signal forming means capable of changing a phase and supplying the signal to the electro-mechanical conversion actuator. (2) The control signal generating means of the tracking error generating circuit causes the electro-mechanical transducer to generate a signal until the amplitude component of one of the two types of pilot signals reproduced by one of the heads reaches a predetermined value or more. 2. The dynamic tracking device according to claim 1, further comprising means for making the applied voltage change in one direction. (3) The control direction detection means of the tracking error generation circuit supplies tracking to the electro-mechanical conversion element until amplitude components of both of the two types of pilot signals reproduced by the other head become equal to or less than a predetermined value. 2. The dynamic tracking device according to claim 1, further comprising a first detection circuit that outputs a switching signal in which the error amount changes in one direction. (4) The control direction detecting means of the tracking error generation circuit detects the electric current until the difference between the amplitude components of the two types of pilot signals reproduced by the other head becomes equal to or less than a predetermined value.
2. The dynamic tracking device according to claim 1, further comprising a second detection circuit that outputs a switching signal whose direction of change in the amount of tracking error supplied to the mechanical transducer is unidirectional.