JPH0266764A - Tracking controller - Google Patents

Abstract

PURPOSE:To stabilize an error signal with a simple constitution by detecting the reproducing level of a video based on a pilot signal and executing the correction to display a low pass filter characteristic to an error signal. CONSTITUTION:When fluctuation occurs at a tracking error detecting signal S3, a reproducing level signal component is fluctuated. At this time, a CPU 47A prepares the gain value data to display a low pass filter characteristic in accordance with the change of a reproducing level signal component based on a fetched target value data. The data are used for the correction operation of the gain of an error signal component included in the error detecting signal S3, and consequently, the tracking position of the reproducing head for the recording track of a magnetic tape is not fluctuated. Thus, a tracking error signal is stabilized and the tracking control is facilitated with a simple constitution.

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A: Industrial field of application B: Outline of the invention C: Prior art (Figs. 5 and 6) D: Problems to be solved by the invention (Figs. 5 to 7) E: Means for solving the problem (Figs. 1 and 2) F Effect (Fig. 1) G Embodiment (Figs. 1 to 4) H Effects of the invention The present invention is suitable for application to a type of automatic track following type (ATF type) tracking control device.

B. Summary of the Invention The present invention provides a pilot signal recording type tracking control device that detects the playback level of a video signal based on the pilot signal and performs a correction operation on the tracking error signal so as to exhibit low-pass filter characteristics. By doing so, it is possible to easily realize a tracking control device that can stabilize a tracking error signal with a simple configuration.

C. Prior Art This type of tracking control device is designed to cyclically record four-frequency pilot signals f1 to f4 together with a video signal onto recording tracks that are sequentially formed across the running direction of a magnetic tape. 4-frequency ATF)
A racking control device has been proposed (Japanese Unexamined Patent Publication No. 57-2
02185).

This 4-frequency ATF I-racking control device is
As shown in FIG. 5, from a reproduced video signal S1 reproduced by a reproduction head (consisting of a recording and reproduction head, but functioning as a reproduction head in the reproduction mode) consisting of two or four rotating video heads. , a 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, and an error signal forming circuit 3
give to The error signal forming circuit 3 sends out a tracking error detection signal S3 formed under the control of the reference pilot signal forming circuit 4.

As shown in FIG. 6, on the magnetic tape 5, there are recording tracks TAI, TBI, and T in which four-frequency pilot signals f, , f2, f3, f are superimposed and recorded on a video signal.
A2, TB2 (TAI and TA2, TBI and TB2
(each having the same azimuth angle) are formed diagonally and closely together so that they are repeated in a cyclical manner.

Here, in principle, as shown by the solid line in FIG.
When tracking in the just tracking state, the pilot signals f+, fz, f3, r4 reproduced from the recording track being tracked,
Pilot signals (f4 and fz), (r+ and rs
), (rz and f4), and (f3 and fl) are detected by the pilot signal detection circuit 1 as signal components of the reproduced video signal S1.
given to.

Here, as shown by the broken line in FIG. 6, when scanning the recording tracks TAI, TBI, TA2, and TB2 with the reproducing head 6 shifted to the left (or right) in the running direction, the adjacent left (or right adjacent) ) recording tracks TB2, T
AI, TBI, TA2 (or TBI, TA2, TB2
, TAI) pilot signals f4, fo, f2, f3
(or f2, f3, f4, fl) increases in accordance with the amount of track deviation.

By the way, the frequency values of the four-frequency pilot signals f1 to f4 are such that the difference frequencies ΔfA and Δf3 with respect to adjacent pilot signals are predetermined values, for example, Δfa −l f+
fzl=l fs f.

-16(k)lz'l ・・・・・・
(1) Δfn = l fz f31
= l f4 f+-46CkHz)
・・・・・・ So that (2) is obtained, f I
=102 (kHz), f z=us (kHz)
, f :+=164 (k)lz) , f 4=14
8 (kHz).

Then, the recording tracks TAI and TA2 where the odd-numbered pilot signals f1 and f3 are recorded are transferred to the playback head 6.
is scanning with left shift (or right shift), the regenerated pilot signal S2 has a difference frequency ΔfB (or Δf
The signal level of the pilot signal increases as shown in A), and the reproduction radar 6 scans with a leftward (or rightward) shift in the recording tracks TBI and TB2 where the even-numbered pilot signals f2 and f4 are recorded. When this happens, the signal level of the pilot signal becomes large so that the difference frequency becomes ΔfA (or ΔfB) in the regenerated pilot signal S2.

The error signal forming circuit 3 multiplies this reproduced pilot signal S2 by the reference pilot signal 311 in the multiplication circuit 14 to generate a multiplication output S12 including the difference frequency ΔfA or Δf8, and the difference frequencies ΔfA and Δf! The signal component of 1 is extracted by the AfA difference frequency detection circuit 20 and the Δf8 difference frequency detection circuit 21 having a band-pass filter configuration, and is provided to the error signal output circuit 22 as error detection signals S13 and 314.

Here, the reference pilot signal forming circuit 4 generates a pilot signal f of four frequencies obtained from the pilot signal generating circuit 16,
, f, , f8, f by selecting in the switch circuit 17 using the head switching signal RF-3W.
The playback head 6 selects recording tracks TAI, TBI, TA2,
At the timing of scanning TB2, pilot signals f, , fz, fi, f4 at predetermined signal levels are supplied to the multiplication circuit 14 as reference pilot signals S11.

The error signal output circuit 22 obtains the subtraction output of the error detection signals S13 and S14 in the subtraction circuit 23, and tracks 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 TAI and TA2. It is sent as an error detection signal S3, and in response to this, the playback head 6 detects the recording track TBI.
At the timing of scanning TB2 and TB2, the polarity of the subtracted output is inverted by the inverter 25 and sent through the switching input terminal P2 of the switch circuit 24 as a tracking error detection signal S3.

Here, the difference output 514 between the error detection signals S13 and 314
The polarity and value of -313 (=ΔfIl−ΔfA) are as follows:
This shows the difference in the amount of crosstalk between the pilot signals from the left (or right) recording track when scanning B2, and thus the track deviation direction and track deviation amount, and the playback head 6 scans the recording tracks TAI, TBI, TA2. , T
When in the leftward (or rightward) state with respect to B2, the polarity becomes pressure, negative, positive, negative (or negative, positive, negative, positive) in this order.

Therefore, if the switch circuit 24 is switched to the switching input terminal P2 side at the timing when the polarity of the difference signal 514-313 becomes negative (or positive) in the leftward (or rightward) state, all recording tracks can be When the playback head 6 is shifted to the left (or shifted to the right) from TAI to TB2, the polarity of the tracking error detection signal S3 is positive (or negative).
become.

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 using the tracking error detection signal S3, the rad 6
This means that all recording tracks TA1 to TB2 can be scanned while maintaining the just tracking state.

D Problems to be Solved by the Invention By the way, the tracking error detection signal S3 formed in the error signal forming circuit 3 is determined based on the amount of crosstalk between pilot signals recorded on adjacent recording tracks. 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, the fluctuation part is treated as a tracking error fluctuation and a tracking operation is performed to cancel it out. There is a possibility that tracking deviation may occur in the reproducing head 6.

To solve this problem, conventionally, a method has been used in which the tracking error detection signal S3 is stabilized in the output level stabilization circuit 31.

The output level stabilization circuit 31 has a tracking error detection signal acquisition switch circuit 34 and a recording level detection switch circuit 35, and is shown in FIG. 7(B) by the switch control signal ■1 sent from the controller 33. By turning on the tracking error detection signal acquisition switch circuit 34 at the timing of the first and second tracking error detection sections M1 and M3 of the reference pilot signal S11, the pilot signals f0 and f2 are
, f3, f, are the error signal components obtained from the recording track where f, , ERRI, ERR2, ERR3 are recorded.
, ERR4 (FIG. 7(D)) are input to the variable gain amplifier circuit 36 via the input capacitor 37.

On the other hand, the recording level detection switch circuit 35 is turned on by the switch control signal ■2 of the controller 33 at the timing of the recording level detection period M2 of the reference pilot signal Sll, and thereby the reproduction level of the tracking error detection signal S3 is turned on. Signal component L P B+ 1L
P Bz , L P B3, LPB4 (Figure 7 (D
)) is sampled and held in a hold circuit 40 consisting of a resistor 38 and a capacitor 39 (7th
Figure (E)).

The playback level signal components LPB+, LPBz, LPBs, and LPB4 held in the hold circuit 40 are as follows:
is given to the variable gain amplifier circuit 36 as a gain control signal,
(Then, when the recording detection level held in the hold circuit 40 changes from the reference value, the variable gain amplifier circuit 36 is controlled to a gain that compensates for this change.
Level fluctuations occurring in the tracking error detection signal S3 based on noise and tracking fluctuations are stabilized.

The tracking error signal S21 obtained from the output level stabilization circuit 31 in this way is given to the capstan servo amplifier circuit 41 as a correction signal for the reference speed signal REF, and thus the capstan motor 42 is included in the tracking error detection signal S3. The reproduction head 6 is controlled to a speed that returns the error signal components ERRI to ERR4 to zero, thereby controlling the reproducing head 6 to a just tracking state.

However, the conventional configuration shown in FIG. 5 has the disadvantage that the number of circuit elements is large, and the wiring between each circuit element and the controller 33 is relatively complicated.

In addition to this, if it is necessary to run the magnetic tape 5 in various modes such as playback mode and cue/review mode, the patterns of switch control signals (1) and (2) given from the controller 33 to the switch circuits 34 and 35 may be changed. It is complicated to have to change it each time.

The present invention has been made in consideration of the above points, and in stabilizing and controlling the output level of the tracking error signal,
The present invention attempts to propose a tracking control device with a simple configuration that can reduce the number of parts at once and eliminate the need to use complicated patterns.

E Means for Solving Problem E In order to solve this problem, in the present invention, pilot signals f, -f, whose frequencies change sequentially and cyclically, are recorded in the recording tracks TAI to TB2, and each of the recording tracks is In a tracking control device that performs tracking control on a reproducing head 6 based on a tracking error detection signal S3 corresponding to a difference in the amount of crosstalk between pilot signals f1 to f4 obtained from recording tracks adjacent on both sides during reproduction of TAI to TB2, tracking is performed. Based on target value data X(nT) representing changes in reproduction level signal components LPBI-LPB4 of error detection signal S3, gain value data exhibiting low-pass filter characteristics according to changes in reproduction level signal components LPB, to LPB4. Create Y (nT),
The error signal components ERR, -ERR, of the tracking error detection signal S3 are determined by the gain value data Y (nT).
The error data E stabilized by correcting the
A stabilizing means 45 is provided which calculates RR(NEW) and sends out a tracking error signal S22 based on the calculation result.

The reproduction level signal components LPB and -LPB4 included in the F-effect tracking error detection signal S3 represent the recording levels of the pilot signal and video signal recorded on the recording track.

Therefore, the stabilizing means 45 reproduces the reproduction level signal components LPB, .
By calculating gain value data Y (nT) that exhibits low-pass filter characteristics based on LPB4 and determining the signal level of error data according to the gain value data Y (nT), the circuit as a whole can be improved. A tracking control device with a simple configuration that can significantly reduce the number of elements can be realized.

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

In FIG. 1, in which parts corresponding to those in FIG. D
The signal is converted into ATAs and inputted to a stabilization control circuit 47 composed of a microcomputer.

The stabilization control circuit 47 is a central processing unit (CPU) 4
7A, the reproduction level signal components LPB, ~LPB4 and the error signal components ERR, ~ERR4 (FIG. 2(D)) of the human-powered digital signal DATA33 are set at a predetermined sampling period T/2 synchronized with the head switching signal RF-3W.
After being captured into the memory 47B by the sampling pulse SAMP (FIG. 2(E)) (FIG. 2(F)),
The stabilization processing calculation is executed, and the stabilization processing calculation result is sent as digital output data DATAsz□ to the capstan servo amplifier circuit 41 as a tracking error signal S22 via the digital/analog conversion circuit 48.

As shown in FIGS. 2A to 2D, the error signal forming circuit 3 generates the error signal component ERR in the same manner as described above with respect to FIGS. 7A to 7D.

~ERR, and playback level signal component LPB, ~LPB
The analog/digital conversion circuit 46 generates a tracking error detection signal S3 including the error signal components ERR, ~ERR4 and the reproduction level signal component L.
PB, -LPB are sequentially and alternately sampled every period T by the sampling pulse SAMP and written to the write data register REGI as data DATAS3 of the memory 47B (FIG. 3).

Based on the error data and playback level data taken in in this way, the CPU 47A sends the output data DAT A st* obtained by executing the stabilization processing program shown in FIG. 4 to the digital/analog conversion circuit 48. By giving the tracking error signal S
22 is sent.

That is, the CPU 47A uses the sampling pulse SAMP
(Fig. 2 (E)), the stabilization processing routine RTO is entered at the timing of each pulse, and the input data DATA 33 obtained at the output terminal of the analog/digital conversion circuit 46 is written in the data register in step SPI. Import into REGI.

Subsequently, the CPU 47A moves to step SP2 and writes the input data D A written in the write data register REGI.
T A s s is the error signal component ERR□ (i-1
~4).

If a negative result is obtained in step SP2, this means that the content of the input data DATA is the error signal component E R of the tracking error detection signal S3.
This indicates that the reproduction level signal component L P B i (1=1 to 4) (FIG. 2 (F)) is not Ri (t = 1 to 4), and at this time, the CPU 47A inputs the input data D A The absolute value of T A S 3 is the target value data
(nT) is the target value data register REG3 (third
Figure).

Subsequently, the CPU 47A moves to step SP4 and calculates the gain value data Y (nT) by repeating the calculation by executing the calculation of the following formula % formula %(), and writes this into the gain value data register REG4 of the memory 47B. After, step S
At P5, the stabilization processing routine RTO ends.

In equation (3), gain value data Y(nT) represents the nth repeated calculation result with the calculation period T,
Target value data X (nT) and previous gain value data Y (n
T-T) is multiplied by a coefficient J = 2-5 and added to the previous gain value data Y (nT-T), and the addition result is obtained as new gain value data Y (nT). means to carry out.

Here, the coefficient data J=2-5 is written in advance in the coefficient data register REG5 (FIG. 3) of the memory 47B.

On the other hand, if a positive result is obtained in step SP2 described above, this means that the sampling pulse SAMP
(FIG. 2(E))
This means that the input data DATA S 3 taken in is the error signal component ERRt (i=1 to 4), and at this time, the CPU 47A moves to step SP6 and calculates the following formula % formula % (). Execute.

In this step SP6, the CPU 47A writes the input data D A T written into the write data register REG1.
A S3 is set as the detected error data ERR (DET), and new error data ERR (NE
W), and the calculation result is stored in the error data register R.
It is written to EG2 as error data ERR (NEW).

In the case of this embodiment, the coefficients of equation (4) are stored in advance in the memory 47.
The coefficient data of B is written in REG6 (FIG. 3).

After completing this calculation, the CPU 47A performs step SP7.
The tracking error signal S22 is transferred to the capstan servo amplifier circuit by reading out the error data ERR (NEW) held in the error data register REG2 and giving it to the digital/analog conversion circuit 48 as output data DATA, □2. 41, in step SP8 the stabilization processing routine RT
End O.

In the above configuration, when a fluctuation occurs in the tracking error detection signal S3 based on noise or fluctuation in tracking operation, this changes to the playback level signal components LPB, ~LPB,
fluctuate the signal level.

At this time, the CPU 47A performs step 5Pi-3 in FIG.
When calculating the gain value data Y (nT) through the processing loop of P2 to 5P3-3P4-3P5, the target value data X (
Based on this and previous gain value data Y (nT-
The previous gain value data Y (n
By performing an operation such as adding to T-T),
In the end, it is possible to form gain value data Y (nT) that changes to exhibit low-pass filter characteristics.

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

This gain value data Y(nT) corrects the gain of the error signal component ERR4 (i=1 to 4) included in the tracking error signal S3 by the CPU 47A executing the processing of steps 5P2-3P6-3P7-3P8. used for

In this way, the signal level of the tracking error signal S22 output to the capstan servo amplifier circuit 41 is corrected so as not to be affected by fluctuations in the tracking error detection signal S3, and as a result, the signal level of the tracking error signal S22 outputted to the capstan servo amplifier circuit 41 is corrected so as not to be affected by fluctuations in the tracking error detection signal S3.
The tracking position of the reproducing head 6 with respect to B2 can be prevented from changing.

In performing such a correction operation, the configuration shown in FIG. 1 requires a significantly smaller number of circuit components than the conventional configuration shown in FIG. 5.

Furthermore, with the configuration shown in Fig. 1, even when the operation mode of the video tape recorder is switched to playback mode, cue/review mode, review mode, etc., the sampling pulse SAMP (Fig. 2 (E)) is used as the head switching signal. Since it is synchronized with RF-3W, there is no need to prepare a special sampling pattern, and in this respect as well, it is possible to realize a tracking control device with a simpler configuration compared to the conventional case shown in Fig. 5. .

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

FIG. 6 is a block diagram showing the darkness, FIG. 6 is a route map showing its recording format, and FIG. 7 is a signal waveform diagram showing signals of each part in FIG.

1...Pilot signal detection circuit, 3...
・Error signal forming circuit, 4...Reference pilot signal forming circuit, 45...Stabilization circuit, 47...
...Stabilization control circuit.

Claims (1)

[Claims] A pilot signal whose frequency changes sequentially and cyclically is recorded on a recording track, and corresponds to the difference in the amount of crosstalk between the pilot signals obtained from adjacent recording tracks on both sides when each recording track is reproduced. In a tracking control device that performs tracking control of a playback head based on a tracking error detection signal, the tracking control device controls tracking control according to a change in the playback level signal component based on target value data representing a change in the playback level signal component of the tracking error detection signal. Gain value data exhibiting low-pass filter characteristics is created, and stabilized error data is obtained by correcting the error signal component of the tracking error detection signal using the gain value data, and based on the result of the calculation, stabilized error data is obtained. A tracking control device comprising stabilizing means for sending out a tracking error signal.