JP2606314B2 - Tracking control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A Industrial application field B Outline of the invention C Conventional technology (FIGS. 5 and 6) D Problems to be solved by the invention (FIGS. 5 to 7) E Means for solving the problems (FIGS. 1 and 2) F function (FIG. 1) G embodiment (FIGS. 1 to 4) H Effect of the invention A Industrial application Field of the Invention The present invention relates to a tracking control device, and in particular, to pilot signal recording. It is suitable to be applied to a tracking control device of an automatic tracking type (ATF system).

SUMMARY OF THE INVENTION The present invention relates to a tracking control apparatus for a pilot signal recording type, in which a reproduction level of a video signal is detected based on a pilot signal and a correction operation for exhibiting a low-pass filter characteristic is performed on the tracking error signal. With this configuration, a tracking control device that can stabilize the tracking error signal with a simple configuration can be easily realized.

As C prior art this kind of tracking control device, 4 frequency pilot signal f ₁ ~f ₄ as going to cyclically recorded together with the video signal to the recording tracks which are sequentially formed so as to cross the traveling direction of the magnetic tape A four-frequency ATF tracking control device has been proposed (Japanese Patent Laid-Open No. 57-202185).

This four-frequency ATF tracking control device
As shown in the figure, from a playback video signal S1 played back by a playback head consisting of two or four rotating video heads (consisting of a recording / playback head, but functioning as a playback head in a playback mode). The pilot signal component included in the reproduced video signal S1 is extracted by a pilot signal detection circuit 1 having a low-pass filter configuration to obtain a reproduced pilot signal S2, which is provided to an error signal forming circuit 3.
The error signal forming circuit 3 comprises a reference pilot signal forming circuit 4
The tracking error detection signal S3 formed under the control of (1) is transmitted.

As shown in Figure 6 is formed on the magnetic tape 5, 4 pilot signals f ₁ of frequency component, f _2, f _3, f ₄ formed by recorded superimposed on the video signal recording tracks TA1, TB1, TA2, A set of TB2s (TA1 and TA2, and TB1 and TB2 each have the same azimuth angle) is formed obliquely and closely so as to sequentially and cyclically repeat.

Here, in principle, as shown by a solid line in FIG. 6, when the reproduction head 6 tracks the recording tracks TA1, TB1, TA2, and TB2 in the fast tracking state, the reproduction head 6 reproduces the data from the recording track. The pilot signals f ₁ , f ₂ , f ₃ , and f ₄ are cross-talked from recording tracks adjacent on both sides thereof (f ₄ and f _4).
f _2), (f ₁ and f _3), (f ₂ and f _4), (f ₃ and f ₁₎ and is applied to the pilot signal detecting circuit 1 as a signal component of the reproduced video signal S1.

Here, as shown by the broken line in FIG. 6, when the recording tracks TA1, TB1, TA2, and TB2 are scanned in a state where the reproducing head 6 is deviated leftward (or rightward) in the traveling direction, the leftmost (or rightmost) is recorded. ) Recording track TB2, TA1, TB1, TA2
(Or TB1, TA2, TB2, TA1) pilot signals f ₄ , f ₁ ,
The amount of crosstalk from f ₂ , f ₃ (or f ₂ , f ₃ , f ₄ , f ₁ ) increases in accordance with the amount of track deviation.

Meanwhile 4-frequency frequency values of the pilot signals f ₁ ~f ₄ of the difference frequency Delta] f _A and Delta] f _B of the adjacent pilot signals
Is a predetermined value, for example, Δf _A = | f ₁ −f ₂ | = | f ₃ −f ₄ | = 16 [kHz] (1) Δf _B = | f ₂ −f ₃ | = | f ₄ −f ₁ | = 46 [kHz] …… (2) so that f ₁ = 102 [kHz], f ₂ = 118 [kHz], f ₃ =
164 [kHz] and f ₄ = 148 [kHz] are selected.

So when the odd-numbered pilot signals f ₁ and f ₃ reproducing head 6 recording tracks TA1 and TA2 are recorded is scanned in the left shift (or right shift) state, the difference frequency is reproduced pilot signal S2 the signal level of Delta] f _B (or Delta] f _a) to become such pilot signal is increased, and the even-numbered pilot signal f ₂ and f ₄ reproducing head 6 is left shifted in the recording track TB1 and TB2 are recorded (or When scanning in the right-shift state, the signal level of the pilot signal such that the difference frequency becomes Δf _A (or Δf _B ) increases in the reproduced pilot signal S2.

The error signal forming circuit 3 multiplies the reproduced pilot signal S2 by the multiplication circuit 14 with the reference pilot signal S11 to generate a multiplication calculation force S12 including the difference frequency Δf _A or Δf _B , and generates the multiplication force S12 including the difference frequencies Δf _A and Δf _B. The signal component is extracted in a Δf _A difference frequency detection circuit 20 and a Δf _B difference frequency detection circuit 21 having a bandpass filter configuration, and an error detection signal S13
And S14 to the error signal output circuit 22.

Here, the reference pilot signal forming circuit 4 outputs the pilot signals f _{1 for} four frequencies obtained from the pilot signal generating circuit 16,
By selecting f ₂ , f ₃ , and f ₄ in the switch circuit 17 by the head switching signal RF-SW, the pilot of the predetermined signal level is scanned at the timing when the reproducing head 6 scans the recording tracks TA1, TB1, TA2, and TB2. The signals f ₁ , f ₂ , f ₃ , and f ₄ are supplied to the multiplication circuit 14 as the reference pilot signal S11.

The error signal output circuit 22 obtains the subtraction output of the error detection circuits S13 and S14 in the subtraction circuit 23, and outputs the subtraction output through the switching input terminal P1 of the switch circuit 24 at the timing when the reproducing head 6 scans the recording tracks TA1 and TA2. A king error detection signal S3 is sent out. At the timing when the reproducing head 6 scans the recording tracks TB1 and TB2, the polarity of the subtracted output is inverted by the inverter 25 and the signal is tracked through the switching input terminal P2 of the switch circuit 24. Transmitted as King error detection signal S3.

Here, the difference output S14−S13 of the error detection signals S13 and S14
The polarity and value of (= Δf _B −Δf _A ) are determined by the crosstalk amount of the pilot signal from the left (or right) recording track when the reproducing head 6 scans the recording tracks TA1, TB1, TA2, and TB2. The reproduction head 6 indicates the recording track TA, and thus the direction of the track deviation and the amount of the track deviation.
1, the polarity when TB1, TA2, and TB2 are left-shifted (or right-shifted) are sequentially positive, negative, positive, negative (or negative, positive,
Negative, positive).

Therefore, if the switch circuit 24 is switched to the switching input terminal P2 when the polarity of the difference signal S14-S13 becomes negative (or positive) in the left shift (or right shift) state, all the recording tracks can be obtained. When the reproducing head 6 is in the left shift (or right shift) state in TA1 to TB2, the polarity of the tracking error detection signal S3 becomes positive (or negative).

Therefore, if the capstan servo system of the magnetic tape 5 is controlled in the direction in which the tracking error detection signal S3 becomes 0 by the tracking error detection signal S3, the reproducing head 6 can control all the recording tracks TA1 to TB2. Thus, scanning can be performed while maintaining the just tracking state.

D. Problems to be Solved by the Invention Incidentally, the tracking error detection signal S3 formed in the error signal forming circuit 3 is determined based on the crosstalk amount of the pilot signal recorded on the adjacent recording track. On the other hand, if the signal level of the tracking error detection signal S3 fluctuates based on noise or fluctuations in the tracking scanning state, a tracking operation is performed to cancel the fluctuating portion as a tracking error fluctuation. After all, the playback head 6
May cause tracking deviation.

In order to solve this problem, a method of stabilizing the tracking error detection signal S3 in the output level stabilizing circuit 31 has been conventionally used.

Output level stabilizing circuit 31 includes a tracking error detection signal take-switching circuit 34 and the recording level detection switch circuit 35, switch control signal I'm connexion Figure 7 to ₁ sent from the controller 33 (B ), The pilot signal f is turned on by turning on the switching circuit 34 for taking in the tracking error detection signal at the timing of the first and second tracking error detection sections M1 and M3 of the reference pilot signal S11. _{1, f 2, f 3,} f 4, an error signal is obtained from the recording track being recorded component ER
R ₁ , ERR ₂ , ERR ₃ , ERR ₄ (FIG. 7 (D)) are input to the variable gain amplifier circuit 36 via the input capacitor 37.

Recording level detection switch circuit 35 on the other hand, the controller 33 at the timing of the recording level detection period M2 of the reference pilot signal S11 operate Yotsute on the switch control signal I _2, thereby the tracking error detection signal S3 The reproduction level signal components LPB ₁ , LPB ₂ , LPB ₃ , LPB ₄ (the seventh
(D) is sampled and held in a hold circuit 40 including a resistor 38 and a capacitor 39 (seventh embodiment).
(E).

Reproduction level signal component held by the hold circuit 40
LPB ₁ , LPB ₂ , LPB ₃ , and LPB ₄ are provided as a gain control signal to the variable gain amplifying circuit 36, and thus the variable gain amplifying circuit
When the recording detection level held by the hold circuit 40 changes from the reference value, the gain 36 is controlled to a gain that compensates for this, and is generated in the tracking error detection signal S3 based on noise and tracking fluctuation. Stabilize level fluctuations.

The tracking error signal S21 obtained from the output level stabilizing circuit 31 in this manner is supplied to the capstan servo amplifier circuit 41 as a correction signal for the reference speed signal REF, and thus the capstan motor 42 receives the tracking error detection signal. Error signal components ERR _{1 to} ER included in S3
It is controlled in such a rate that pull back the R ₄ to 0, thereby reproducing head 6 is controlled to Jiyasu Toto Raţ King state.

However, the conventional configuration shown in FIG. 5 has a drawback that the number of components of the circuit element is large, and furthermore, there is a problem that wiring between the circuit elements and between the controller 33 is relatively complicated.

In addition to this, when it is necessary to run the magnetic tape 5 in various modes such as a reproduction mode and a queue / review mode, the controller 33 supplies the switch circuits 34 and 35.
There are switch control signal I ₁ and the complexity must be changed each time the pattern of I ₂ applied to.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points. For stabilizing and controlling the output level of a tracking error signal, the number of components can be reduced at once, and a simple pattern can be used which does not need to use a complicated pattern. A tracking control device having a configuration is proposed.

In the present invention for solving means above problems to solve E problems, recording the pilot signal f ₁ ~f ₄ whose frequency varies sequentially cyclically to the recording track TA1～TB2, each recording track TA1 tracking controller for tracking control playback head 6 based on the tracking error detection signal S3 corresponding to the difference between the crosstalk amount of playback the pilot signal f ₁ ~f ₄ obtained from adjacent recording track on both sides of ~TB2 , The reproduction level signal component LPB ₁ of the tracking error detection signal S3
Based on the target value data X (nT) representing a change in ~LPB _4,
Create the gain value data Y (nT) as exhibits low-pass filter characteristic in accordance with a change in the reproduction level signal component LPB ₁ ~LPB _4, the Yotsute tracking error detection signal S3 to the gain value data Y (nT) Error data ERR (NEW) stabilized by correcting the error signal components ERR _{1 to} ERR ₄
And stabilizing means 45 for transmitting a tracking error signal S22 based on the calculation result.

F acts tracking error detection reproduction level signal component contained in the signal S3 LPB ₁ ~LPB ₄ represents the recording level of the pilot signal and the video signal recorded on the recording track.

Therefore, the stabilizing means 45 outputs the reproduction level signal components LPB _{1 to} LPB ₄
The gain value data Y (nT) exhibiting a low-pass filter characteristic is obtained by calculation based on
By determining the signal level of the error data in accordance with (nT), it is possible to realize a tracking control device having a simple configuration that can significantly reduce the number of circuit elements as a whole.

G Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIG. 1 in which parts corresponding to those in FIG. 5 are denoted by the same reference numerals, a tracking error detection signal S3 sent from the error signal forming circuit 3 is digitally input to an analog / digital conversion circuit 46 of a stabilizing circuit 45. Data DATA _S3
And input to the stabilization control circuit 47 having a microcomputer configuration.

The stabilization control circuit 47 controls the reproduction level signal component of the input digital signal DATA _S3 by the central processing unit (CPU) 47A.
LPB ₁ ~LPB ₄ and the error signal component ERR ₁ ~ERR ₄ (FIG. 2 (D)), and head switching signal of a predetermined synchronizing the RF-SW sampling period T / 2 of the sampling pulse SAMP (Figure 2 (E )) (FIG. 2 (F)), executes the stabilization processing operation, and outputs the stabilization processing operation result as digital output data DATA _S22 via the digital / analog conversion circuit 48. The signal is sent to the capstan servo amplifier circuit 41 as a tracking error signal S22.

As the error signal forming circuit 3 shown in FIG. 2 (A) ~ (D), in the same manner as described above for FIG. 7 (A) ~ (D), the error signal component ERR ₁ Err ₄ and the playback level signal component LPB ₁ ~LPB ₄ generates tracking error detection signal S ₃ comprising an analog / digital conversion circuit 46 is the error signal component ERR ₁ Err ₄ and reproduction level signal component LPB ₁
.. LPB ₄ are sampled at intervals of a period T according to a sampling pulse SAMP alternately and sequentially.
The data is written in the write data register REG1 as the data DATA _{S3 in} FIG.

The CPU 47A outputs the output data DATA obtained by executing the stabilization processing program shown in FIG. 4 based on the error data and the reproduction level data thus captured.
By providing _S22 to the digital / analog conversion circuit 48, a tracking error signal S22 is transmitted.

That is, the CPU 47A enters the stabilization processing routine RT0 at the timing of each pulse in synchronization with the sampling pulse SAMP (FIG. 2 (E)), and performs analog /
Input data DA obtained at the output terminal of the digital conversion circuit 46
TA _S3 is taken into the write data register REG1.

Subsequently, the CPU 47A proceeds to step SP2 to determine whether or not the input data DATA _S3 written in the write data register REG1 is an error signal component ERR _i (i = 1 to 4).

If a negative result is obtained in step SP2, this means that the content of the input data DATA _S3 is not the error signal component ERR _i (i = 1 to 4) of the tracking error detection signal S3 but the reproduction level signal component LPB _i ( i = 1 to 4) (FIG. 2 (F)). At this time, the CPU 47A sets the absolute value of the input data DATA _S3 as the target value data X (nT) in the target value data register REG3 (third). (Fig.)

Subsequently, the CPU 47A proceeds to step SP4 to execute the following equation: Y (nT) = Y (nT−T) +2 ⁻⁵ {x (nT) −Y (nT−T)} (3) After calculating the gain value data Y (nT) by repetitive calculation and writing it in the gain value data register REG4 of the memory 47B, the stabilization processing routine RT0 is terminated in step SP5.

In the equation (3), the gain value data Y (nT) represents the result of the n-th repetitive operation with the operation cycle being T,
Target value data X (nT) and previous gain value data Y (nT-T)
^Is multiplied by a coefficient j = 2 ⁻⁵ to obtain the previous gain value data Y (n
T−T) is added to new gain value data Y (n
T) means to execute an iterative operation as obtained as:

Here, the coefficient data j = 2 ^-5 has been written in the coefficient data register REG5 (FIG. 3) of the memory 47B in advance.

On the other hand, if a positive result is obtained in step SP2 described above, this means that the sampling pulse SAMP (second
Figure (E)) input data DATA _S3 the error signal taken in by connexion write data register REG1 into components ERR _{i (i} = 1~
4) means that the CPU 47A has step
Moving to SP6 Execute the operation of

In this step SP6, the CPU 47A sets the input data DATA _S3 written in the write data register REG1 as detection error data ERR (DET), and the gain written in the gain value data register REG4 by the processing in steps SP3 and SP46. New error data ERR using value data Y (nT)
(NEW), and the calculation result is written to the error data register REG2 as error data ERR (NEW).

In the case of this embodiment, the coefficient K in the equation (4) is stored in the memory 47 in advance.
It has been written to the B coefficient data register REG6 (FIG. 3).

After this operation is completed, the CPU 47A proceeds to step SP7, reads out the error data ERR (NEW) held in the error data register REG2, and supplies the error data ERR (NEW) to the digital / analog conversion circuit 48 as output data DATA _S22. After outputting the king error signal S22 to the capstan servo amplifier circuit 41, the stabilization processing routine RT0 is terminated in step SP8.

If variation occurs in the tracking error detection signal S3 based on the variation of the noise and tracking operations in the above configuration, which varies the signal level of the reproduction level signal component LPB ₁ ~LPB _4.

At this time, the CPU 47A executes the steps SP1-SP2-SP3 in FIG.
Gain value data Y (nT) by the processing loop of -SP4 -SP5
In executing the calculation of (1), based on the newly acquired target value data X (nT) in step SP1, the value of ^2-5 times the difference between this value and the previous gain value data Y (nT-T) is set to the previous gain value. By performing an operation of adding to the value data Y (nT-T), it is possible to form gain value data Y (nT) that changes to exhibit a low-pass filter characteristic.

As a result, the gain value data Y (nT) indicating the fluctuation of the reproduction level of the tracking error detection signal S3 is held in the gain value data register REG4 while being constantly updated.

The gain value data Y (nT) is transmitted from the CPU 47A to step SP2.
By executing the processing of -SP6-SP7-SP8, the error signal component ERR _i (i
= 1 to 4).

Thus, the signal level of the tracking error signal S22 output to the capstan servo amplifier circuit 41 is corrected so as not to receive the fluctuation of the tracking error detection signal S3. As a result, the signal level for the recording tracks TA1 to TB2 of the magnetic tape 5 is corrected. The tracking position of the reproducing head 6 can be kept from changing.

In performing such a correction operation, according to the configuration of FIG. 1, the number of circuit components is significantly reduced as compared with the conventional configuration of FIG.

Further, according to the configuration shown in FIG. 1, even when the operation mode of the video tape recorder is switched to a reproduction mode, a key / review mode, a review mode, or the like, the sampling pulse SAMP (FIG. 2 (E)) changes the head switching signal. RF−
Since it is synchronized with SW, there is no need to prepare any special sampling pattern.
As compared with the conventional case shown in the figure, a tracking control device with a much simpler configuration can be realized.

H Effects of the Invention As described above, according to the present invention, it is possible to easily realize a tracking control device that requires a much simpler configuration than the conventional case for stabilizing a tracking error signal.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a tracking control device according to the present invention, FIG. 2 is a signal waveform diagram showing signals of various parts thereof, and FIG. 3 is a schematic line showing a detailed configuration of a memory 47B of FIG. 4 is a flowchart showing a stabilization processing routine of the CPU 47A of FIG. 1, FIG. 5 is a block diagram showing a conventional tracking control device, FIG. 6 is a schematic diagram showing a recording format thereof, FIG. The figure is a signal waveform diagram showing signals of respective parts in FIG. 1 pilot signal detection circuit, 3 error signal forming circuit, 4 reference pilot signal forming circuit, 45 stabilizing circuit, 47 stabilizing control circuit.

Claims (1)

(57) [Claims] 1. A pilot signal whose frequency sequentially changes in a cyclic manner is recorded on a recording track, and corresponds to the difference in the amount of crosstalk between the pilot signals obtained from recording tracks adjacent on both sides during reproduction of each recording track. A tracking control device for performing tracking control of a playback head based on a tracking error detection signal, comprising: a tracking control device for controlling a playback head signal based on a change in the playback level signal component based on target value data representing a change in a playback level signal component of the tracking error detection signal. In this manner, gain value data that exhibits low-pass filter characteristics is created, and the error signal component of the tracking error detection signal is corrected by the gain value data to obtain stabilized error data. Stabilizing means for transmitting a tracking error signal based on the Tracking control apparatus according to claim.