JPH0461018A - Dynamic tracking device - Google Patents

Abstract

PURPOSE:To reduce a main signal recording band and to restrain the deterioration of S/N or a regenerative main signal and a pilot signal by mounting a third head with the track width of a first head less than the track width of a first head on a rotational head. CONSTITUTION:Heads 1A/1B with different azimuth angles are provided on an actuator 4 by the difference in grade of a track pitch, a third head IC is provided in an another position, the first head IC is provided in an another position, the first head 1A scans the scanning track of the third head 1C at the time of recording, and a main signal is multiplied while switching two kinds of pilot signals by a track. At the time of reproduction, the cross talk component of the pilot signal from the adjacent tracks to right and left reproduced by the second head 1B is compared while performing separation and extraction to generate a tracking error amount, a tracking error direction is obtained by extracting the pilot signal reproduced by the first head 1A, and performs on tracking while the polarity of tracking error amount to be supplied to the actuator 4. Thus, the reduction of a main signal recording band and the deterioration of S/N of the regenerative main signal and the pilot signal can be restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) 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 magnetic tape in the longitudinal direction 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-use VTRs are required to be smaller, and this demand naturally includes a reduction in the size of the magnetic tape 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, the running direction of the head (
There are two possibilities: increasing the density in the recording track line direction) and increasing the density in the direction perpendicular to this (recording track width direction), but the former is a short-wavelength recording depending on the performance of the head and magnetic tape. Due to the limitations of , no significant improvement can be expected, so the latter method will be adopted.

For the second reason, even higher integration of tracking control is required, which is compared to conventional trackers. It has become difficult to control the

Under these circumstances, in an 8mm VTR with a narrow track pitch of 20 μm or 10 μm, a sine wave of a constant frequency is applied to the main signal during recording, and the frequency is varied between adjacent tracks, so that the main signal is recorded every 4 tracks. A 4-frequency pilot type ATF (Auth
oa+atic Track Finding) system is adopted.

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 signal must be discrete to the extent that they can be separated during playback. Therefore, the frequency band occupied by the pilot signal becomes wide, and the main signal recording The bandwidth may be reduced, the reproduced main signal and 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 as discrete as possible 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 first and second heads having gaps of mutually different azimuth angles, which are mounted on an electro-mechanical conversion actuator of a rotary cylinder with approximately one track pitch height different from each other. and the azimuth angle is set at a different position on the rotating cylinder so that the azimuth angle difference between the second head and the second head is smaller than the azimuth angle difference between the second head and the first head. a rotary head having a third head set at an azimuth angle substantially equal to the azimuth angle and having a track width less than or equal to the rack width of the first head; a first recording means for recording two types of distinguishable pilot signals to a deep part of the magnetic layer of the magnetic tape by switching them each time the third head scans the magnetic tape; a recording circuit having a second recording means for supplying an information signal to the third head and causing the first head to scan and record the recording trace of the third head; control direction detection means for detecting the two types of pilot signals that are reproduced and comparing their amplitude components to detect a head position control direction, from the two types of pilot signals that are reproduced from the head at one azimuth angle; control signal generating means for generating a tracking error amount;
and a tracking error generation circuit having a signal forming means for changing the phase of a tracking error amount according to the output of the control signal generating means and the output of the control direction detecting means and supplying the signal to the electro-mechanical conversion actuator. Features.

Here, the control direction detection means of the tracking error generation circuit supplies the control direction to the electro-mechanical conversion element until amplitude components of both of the two types of pilot signals reproduced by the second head become equal to or less than a predetermined value. until the difference between the amplitude components of the two types of pilot signals reproduced by the first detection circuit that outputs a switching signal in which the tracking error amount changes in one direction and the second head becomes equal to or less than a predetermined value. Electricity
and a second detection circuit that outputs a switching signal in which the direction of change of the tracking error 1 supplied to the mechanical conversion element is one direction.

(Function) With the above-described configuration, two heads with different azimuth angles are provided on the actuator with a step of one track pitch, and
A third head is provided at a different position, and the first head is
By scanning the scanning trace of the third head, two types of pilot signals Pa and Pb are switched and multiplexed onto the main signal for each track.

During playback, crosstalk components Ca and Cb of pilot signals from the left and right adjacent tracks played back by the second head
are extracted and compared to generate a tracking error amount, and the pilot signals Pa and Pb reproduced by the first head are extracted to obtain a tracking error in one direction, thereby determining the polarity of the tracking error amount. is controlled and supplied to the actuator for on-tracking.

By operating in this way, while maintaining a highly accurate tracking system, it is possible to suppress the reduction of the main signal recording band and the deterioration of the S/N of the reproduced main signal and pilot signal by using a simplified pilot sequence. can.

(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, head IA has a gap of, for example, +10 degrees azimuth, and head 1B has, for example, a gap of -10 degrees azimuth.

The heads LA and IB are arranged on the free end of an electromechanical transducer actuator 4 fixed to a rotary cylinder 3, with an interval X of one member 2 and a height Y of about one track pitch different in the head rotation direction F. ing. In addition, the rotating cylinder 3
It is located at a different position from the actuator 4 on the head I.
A third head IC is attached at a position 180 degrees opposite A and at the same height as the head IA. This head IC has an azimuth angle of 30 degrees, and the width of this is the head IA.
The selection is the same as or wider than this. In this way, the heads IA, IB, IC, member 2, rotary cylinder 3, and actuator 4 constitute the rotary head 5. In addition,
The actuator 4 is a piezoelectric bimorph type actuator that is made by bonding a forged piezoelectric element that expands and contracts according to the applied voltage with the voltage polarity reversed and displaces up and down according to the applied voltage.

During recording, a recording signal is supplied from the recording circuit 6 to the heads IA and IB of the rotary head 5, and a pilot signal is supplied from the recording circuit 6 to the head IC. This recording circuit 6 switches the two types of distinguishable pilot signals of substantially constant frequencies fl and f2 to the head IC each time the third head IC scans the magnetic tape, and sends them to the magnetic tape magnetic layer. The first step is to record deep information.
a recording means 7; and a second recording means 8 which supplies information signals to the heads IA and IB and causes the helad IA to scan and record a recording trace on the magnetic tape of the third head IC. It consists of

During reproduction, the reproduction signal reproduced from the head IAIB of the rotary head 5 is input to the tracking error generation circuit 9, and the tracking error generation circuit 9 outputs the tracking error amount for driving the actuator 4. ing.

This tracking error generation circuit 9 detects the crosstalk components Ca and Cb of the two types of pilot signals reproduced from the head 1B 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 has a video signal input terminal 15, A, /
D converter 16, evening/f-ming signal generator 17, high efficiency encoding circuit 18, correction code addition circuit 19, interleave circuit 20, synchronization signal addition circuit 21, digital modulation circuit 22, A .

It has B channel recording amplifiers 23A and 23B, and is configured as follows. That is, the video signal is input from the video signal input terminal 5 to the D/A converter 16 and the timing signal generator 17. The timing signal generator 17 generates a clock based on the video signal and outputs it 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 undergoes pit rate reduction processing. 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 to be transmitted. Assume that DPCM is used. The video signal whose bit rate has been reduced by DPCM processing is input to the correction code adding circuit 19,
A correction code is added for error correction processing during playback, and the interleave circuit 20 performs rearrangement processing in units of blocks to improve error correction ability at the time of playback dropout. The signal is divided into two systems so that it can be recorded on two tracks. A synchronizing signal adding circuit 21 adds synchronizing data to the two interleaved video data, and a digital modulating circuit 22 rearranges the data so as to suppress direct current and low frequency components. This is because a rotary transformer that does not transmit DC components is used as a transmission means to the rotary head 5, and in magnetic recording, if the recording signal frequency is too low, the reproduction output will decrease. This is done to suppress mutual interference with the main signal during playback when the tracking pilot signal is frequency multiplexed and recorded with the main signal.

The two systems of digitally modulated video data are supplied to the head IA via the A channel recording amplifier 23A and to the head IB via the B channel recording amplifier 23B. Further, in the second recording means 8, the signal timing is set so that the head IA scans and records the recording trace of the magnetic tape of the third head IC.

The first recording means 7 includes an f1 generator 24, an f2 generator 25, a changeover switch 26, and an amplifier 28, and is configured as follows. That is, 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. Each time the tape is scanned, fl and f2 are switched, and amplifier 2
8. The recording signal output from the amplifier 28 is supplied to the head IC.

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

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

Further, the changeover switch 34 sets the actuator 4 to ground potential during recording, and the tracking error generation circuit 9 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 signals shown in FIG. 3(b) are amplified by A and B channel recording amplifiers 23A and 23B, and then supplied to heads IA and IB via rotary transformers (not shown) to be recorded on the tape.

On the other hand, in the first recording means 7, the low frequency pilot signal f1 or f2 is recorded as the third
The signal becomes the signal shown in FIG. 3(c) or FIG. 3(d) and is input to the amplifier 28. The signal amplified by the amplifier 28 is
By being supplied to the head IC via a rotary transformer (not shown), the information is recorded in the deep part of the magnetic layer of the magnetic tape 30.

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 simultaneously formed every time the image is scanned, the rotation frequency is the same as the field frequency of 59.94 Hz if the video signal is of the NTSC format.

Incidentally, 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 rotary head 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.

As shown in FIGS. 4 and 5, the recording order of the three heads is that the head IC takes the lead first, and two types of pilot signals fl and f2 are sent to the magnetic tape 30 in the head traveling direction F. The signal is switched every time the signal is scanned, and after being amplified relatively largely by the amplifier 28, it is recorded by the head IC in the pilot signal recording layer 37 deep in the magnetic layer 36 provided on the base film 35 of the magnetic tape 30.

Next, the head I mounted on the actuator 4
As shown in FIGS. 4 and 5, while A scans the needle mark of the pilot signal formed by the head IC,
The pilot signal of the video digital data output from the A channel recording amplifier 23A remains recorded in the pilot signal recording layer of the magnetic layer 36 in the surface layer (main signal recording layer 38).
Only the data will be recorded over and over again.

FIG. 6 is a block diagram showing the configuration of a reproduction circuit including a tracking error generation circuit.

In FIG. 6, during reproduction, the rotary head 5 is controlled to rotate at a constant cycle, and the rotational speed is approximately the same as that during recording. On the other hand, the feeding speed of the table 30 is controlled to be the same speed as the track pitch during recording.

In this state, the heads IA and IB mounted on the actuator 4 obtain reproduction output according to the magnetization pattern recorded when scanning the tape 30. 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 de-interleaving circuit 46, an error correction circuit 47, a directing circuit 48, and four D/A conversion circuits, which process the video signal and output it as a video signal from the video signal output terminal 50. Output.

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 RPF 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.

The frequency f1 and f2 components of the reproduction output signal of the A head input to the fl BPF53A and f2 BPF54A are extracted, and the pilot signal component of fl or f2 is extracted depending on how much the A head is on-track to the +azimuth track. extracted, each detection circuit 55, detection circuit 56
is input and detected. In addition, the pie fours 1 of frequencies f1 and f2 detected by the detection circuit 55 and the detection circuit 56
- Signals Pa and Pb are input to an adder 57 and also to five comparators 60, respectively. In the adder 57,
The frequency f1 and f2 components of the pilot t signal are added, and a positive voltage corresponding 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 a reference voltage of 0 [V], and depending on the output of the adder 57, if the f1 component is large, a digital signal of ``H level'' is output, and if the f2 component is large, a digital signal of ``L'' level is output to the OR gate 62. supplied to

On the other hand, the detection 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 ■, it is an L" level, and if it is smaller than the reference voltage ■, it is an H" level digital signal. is output to the AND gate 61, and the AND gate 61 outputs the detected output level of the frequency f1 and f2 components to the "H" level if both are smaller than the reference voltage ■, and to the "HI" level if either one is larger than the reference voltage ■. A digital signal is output to OR gate 62. In addition to this, the OR gate 62 has frequencies f1 and f2.
Are the detection output levels of both components smaller than the reference voltage V?
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 applies the signal to the actuator 4 until the amplitude component of one of the two types of pilot signals reproduced by the other head IB reaches a predetermined value or more. It has a configuration in which the direction of change in the tracking error amount is one direction, and specifically, it is configured as follows. That is, the control signal generation means 11 includes fl BPF63B,
It includes an f2 BPF 64B, a detection circuit 65, a detection circuit 66, an adder 67, and a polarity inversion circuit 68.

The reproduced output signal from head IB input to fI BPF6BB and f2 BPF64B has frequencies fl,
The f2 component is extracted, and if it is off-rack, the crosstalk components Ca and Cb of the fl or f2 pilot signal are extracted from the adjacent positive azimuth track,
The detection circuit 65 and the detection circuit 66 manually perform the detection. Pilot I/signal crosstalk component C of fl and f2 caused by head IB detected by the detection circuit 65 and detection circuit 66
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 is inverted. Supplied to circuit 68.

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 selector switch 7 and an integrating circuit 72.
, and an amplifier 73, and is configured as follows.

A switching signal from the control direction detection means 10 switches the changeover switch 71. The changeover switch 71 selects normal rotation or inversion of the addition result of the pilot signal crosstalk components fl and f2 by the head IB, and supplies the result to the integration 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 72.
The voltage is amplified to the drive voltage of the actuator 4 and supplied to the actuator 4 via the changeover switch 34. Here, the changeover switch 34 is on the recording side during recording operation,
The electrode of the actuator 4 is at a reference potential (ground potential). As a result, the actuator 4 is not displaced, so that the phase of each head with respect to the tape remains unchanged except for the feeding of the tape 30, and an L-rack pattern as shown in FIG. 4 can be formed.

The operation of the embodiment configured as described above will be explained using FIG. 7.

In the configuration of the heads IA, IB and actuator 4 according to this embodiment, there are roughly four types of phase relationships between the head IAIB and the recording track during off-track.
This is shown in cases (1) to (4) in the figure. In this figure, it is assumed that when the polarity of the voltage applied to the actuator 4 is positive, it moves to the right, and when it is negative, it moves to the left, and the phases of the heads LA and 1B move relative to recording 1 to rack.

[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 the head 1B has a frequency of f2. At this time, the f2 component reproduced from head IB satisfies f2>fl. Therefore, the adder 67 outputs a voltage with a negative tracking error amount corresponding to the difference between the f1 component and the f2 component.

On the other hand, the pilot signal component reproduced by head 1A is f
l, 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, and the output of the selector switch 71 becomes "H" level.
The normal output of the adder 67 is selected, and a negative voltage is applied to the actuator 4. As a result, head IA and head IB are moved to the left in the drawing. This puts you on track.

[Case (2)] Case 2 is a case where the pilot signal frequency of the same positive azimuth track is fl, and the head IA is slightly off l-rack to the left. At this time.

Cross 1 to - of the pilot signal reproduced by head IB
The crosstalk component is fl, and the crosstalk component reproduced by the head IB satisfies 1>f2. Therefore, the adder 67 outputs a positive voltage according to the difference between the f1 component and the f2 component.

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>f
2 holds true. Therefore, the output voltage polarity of the adder 57 becomes positive, and the output of the comparator 58 becomes the ``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 selector switch 71 selects the output of the adder 67, and the actuator 4 is supplied with a positive voltage of 1 to the amount of racking error. will be applied. As a result, the heads LA 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 component reproduced by head IB l > 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 ■, 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, the polarity reversing circuit 68 in the changeover switch 71
The inverted output of is selected. The voltage corresponding to this tracking error amount is applied as a voltage with negative polarity.
The throats IA and IB move to the left in the diagram.

[Case (4)] In case (4), the pilot signal frequency of the azimuth track is f2, 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 for the regenerated molecule 2 from head IB, fl < f2 holds true.

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 head IA is f2, and the regenerated molecule 1 from head IA is fl
<f2 holds true. Therefore, the output voltage polarity of the adder 57 becomes negative, and the output of the adder 57 becomes "L" level. Furthermore, if the detection output of the pilot signal f2 is greater than the reference voltage ■, the outputs of the five comparators are “
It becomes L” level, and the output of AND gate 61 becomes °゛L”
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, IDO IA and IB move to the right side 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 becomes on-track.

Also, if you are off-track, cases (1) to (4)
) as well as reverse polarity azimuth as shown in case (6),
or the head], A, and IB may be located in the vicinity thereof. At this time, the pilot signal reproduced by the head IA is obtained from the left and right tracks, so the output level of the adder 57 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, and the voltage may not converge forever or become stable on the 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 LA 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 configuration. .

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 output of the l and f2 components is the voltage V at the comparator 59.60.
If both detection outputs are smaller than the voltage ■, the outputs of the comparators 59 and 60 will both be "H" level, and the outputs of the AND gate 61 and OR gate 62 will also be "H" level.
level, the selector switch 71 forcibly selects the output of the adder 67, applies a negative voltage to the actuator 4, and moves the heads LA and IB to the left.

Here, if the reference voltage ■ is set to an appropriate value and the outputs of the five comparators and the output of the AND gate 61 go to the "L" level, the state becomes case (]) and on-tracking occurs.

At the head position indicated by the dotted line in case (6), the crosstalk component element 1 is reproduced from the head node IB, and the adder 67 outputs a positive voltage according to the difference from the f2 component. After that, in the same way, the selector switch 7]- forcibly selects the output of the adder 67, and the positive voltage is applied to the actuator 4.
The actuator 4 will move to the right in the figure. This results in case (2) and on-track.

The head IA is on-track with the above configuration.

Sufficient reproduction output can be obtained by IB.

In this embodiment, as a process when the amount of off-track is large, the moving direction of the head is fixed until the Pylon I signal component reproduced by the head IA reaches a predetermined level or higher. The azimuth is opposite to that of the four L-signal recording tracks, so when the amount of OFF 1 to RACK is large, the deep pilot reproduced by the azimuth loss effect, depending on the azimuth angle difference between the head IA and head IC. It is conceivable that the signal crosstalk component will be considerably smaller. In this case, the control operation for fixing the moving direction of the head IA may become unstable. For this reason, the head IB records the deep pilot signal 1.
~Rack has the same azimuth, and the azimuth angle difference is smaller than head IA, and the deep pilot signal crosstalk component reproduced by the azimuth loss effect does not become relatively small, so the pilot signal crosstalk component reproduced by head IB is Stable operation can be achieved by detecting that the level difference between fl and f2 of the pilot signal crosstalk components reproduced by the head IB is below a predetermined level.

Regarding the head track width, the surface layer 38 of the magnetic layer 36 where the pilot signal is recorded by the head IC is
The present invention will work even if the width is slightly larger or smaller than the track pitch, as long as the width allows complete overlapping recording by A, and if the height difference between the two heads on the head actuator is also at a position where overlapping recording can be performed in the same way, It works even if there is some offset to either side.

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

In addition, regarding overlapping recording of pilot signals by the head IA during recording, it was explained that the height of the head actuator is adjusted in advance during recording.
The height may be adjusted during recording.

As described above, according to this embodiment, by simply recording two types of pilot signals, tracking control can be performed to the closest correct track during playback, regardless of the position of the head with respect to the recording track. Since the main signal recorded in the magnetic layer deep part 37 of the tape 30 is recorded at a different azimuth angle from the main signal recorded in the magnetic layer surface part 38 of the magnetic tape 30, the main signal reproduced by the first head IA becomes a pilot due to the azimuth loss effect. Since the pilot signal is not recorded in the deep part of the rack magnetic layer, the crosstalk component of the pilot signal is considerably suppressed.

〔Effect of the invention〕

As described above, according to the present invention, by simply recording two types of pilot signals, no matter where the head is positioned with respect to the recording track during reproduction, it is possible to carry out racking control to the nearest correct track. Further, according to the present invention, there is an effect that the sequence for recording and reproducing pilot signals 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 actuator used in the same example, Figure 2 is a block diagram showing details of the recording circuit of the same example, Figure 3 is an explanatory diagram showing the recording signal frequency spectrum, FIG. 4 is an explanatory diagram showing the recording track pattern on the tape, FIG. 5 is a perspective view showing the recording track pattern on the tape, FIG. 6 is a block diagram showing the playback circuit of the same embodiment, and FIG. 7 is a diagram during playback. FIG. 3 is an explanatory diagram for explaining the I-racking operation of FIG. IA, IBIC...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 detection means, 11... Control signal generation means, 12...Signal formation means. 6th evil

Claims (2)

[Claims] (1) First and second heads having gaps of different azimuth angles are disposed on an electro-mechanical conversion actuator of a rotating cylinder with approximately one track pitch difference in height, and the first
The azimuth angle is set to an azimuth angle that has a smaller azimuth angle difference with the second head than the azimuth angle difference with the second head, or is set to an azimuth angle that is approximately equal to the azimuth angle of the second head, and the track width is set to an azimuth angle that is substantially equal to the azimuth angle of the second head. a rotary head having a third head attached thereto whose track width is less than or equal to the track width of the first head; and a rotary head that transmits two types of distinguishable pilot signals to the third head during recording; a first recording means that switches each time the head scans to record to the deep layer of the magnetic layer of the magnetic tape; a first recording means that supplies information signals to the first and second heads; a recording circuit having a second recording means for scanning and recording by the first head; and, during reproduction, detecting the two types of pilot signals reproduced from the head at the other azimuth angle 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; A dynamic tracking device comprising: a tracking error generating circuit having a signal forming means capable of changing the phase of a tracking error amount according to the output of the control direction detecting means and supplying the signal to the electro-mechanical conversion actuator. (2) The control direction detection means of the tracking error generation circuit supplies the control direction to the electro-mechanical conversion element until the amplitude components of both of the two types of pilot signals reproduced by the second head become equal to or less than a predetermined value. until the difference between the amplitude components of the two types of pilot signals reproduced by the first detection circuit that outputs a switching signal in which the tracking error amount changes in one direction and the second 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 electro-mechanical conversion element is one direction.