JPS5965962A - Tracking control device - Google Patents

Abstract

PURPOSE:To obtain only a signal component of fixed difference frequency and to simplify the constitution of a circuit when tracking is shifted, by rearranging so that sequence of a variation of frequency of a reference pilot signal is not made coincide with tracking sequence of a reproducing head. CONSTITUTION:f2 and f4 in frequencies of a reference pilot signal S11 sent out of a switching circuit 17 are replaced with each other. When a head 6 is shifted to the right, a signal of frequencies f1, f2, f3, etc. is contained in a pilot signal S2 from each track. Accordingly, a signal component having frequencies f1, f4, f3 and f2 of the signal S11, and frequency of difference of frequency of this pilot signal of each track and frequency of a crosstalk pilot signal of an adjacent track whose head is opposed is contained in a multiplication output S12. In this case, difference frequency between frequency of the signal S11 and frequency of the crosstalk pilot signal becomes successively f1-f2, f4-f3, f3-f4 and f2-f1, and it is contained in the multiplication output S12. Accordingly, an error detecting signal S13 always has a DC level corresponding to length by which the head is opposed to the adjacent track.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tracking control device, and more particularly, to a tracking control device in which a plurality of pilot signals of different frequencies are applied to recording tracks formed in sequence on a recording medium so as to cross the running direction of the recording medium. This method is suitable for application to an information recording device using an automatic track following method (hereinafter referred to as the ATF method), in which the information is recorded cyclically together with information, and the reproducing head is made to track each track using a pilot signal reproduced by the reproducing head. It is something.

[Background technology and its problems]

Conventionally, a helical recording type video tape recorder (VTR) having the principle configuration shown in FIG. 1 has been used as a tracking control device for the information recording device in this building. This tracking control device uses four frequencies f1 e f2 + f3 t f4 as pilot signals, and as shown in FIG. The pilot signal detection circuit (1) generates a reproduced pilot signal S2 whose component is the reproduced output of the pilot signal recorded on the magnetic tape as a recording medium, and converts this reproduced pilot signal S2 into an error signal forming circuit. (3). The error signal forming circuit (3) is connected to the lock point control circuit (4).
) and sends out a tracking error signal S3 formed under the control of the controller.

On the tape (5), as shown in FIG.
+f3+f4 are recorded in four video trunks Tl, T2. T3. The sets of T4 are formed diagonally and closely together so as to repeat in a circular manner.

Here, the effective width of the video head forming the playback head (6) of 4.1" is selected to be approximately equal to the width of the tiger 2211 to 140, for example, and this results in the solid line shown in FIG. As shown, the playback head (6) is currently repressing and scanning.
When correctly tracking a track (this is referred to as a playback trunk), by playing back only the pilot signal recorded on that trunk, the number of pilot frequency components included in the playback output is reduced to one type. On the other hand, when the playback head (6) is shifted to the right or to the left with respect to the relevant trunk as shown by the broken line, the 7 plots recorded on the trunk adjacent to the right or left side of the relevant playback trunk are By also reproducing the signal, there are two types of pilot frequency components included in the reproduced output, and the magnitude of each pilot frequency component becomes equal to the opposing length of the reproducing head facing the corresponding track. It is done like this.

However, the four unique pilot signal frequencies f1 to f4
is selected as the lower band of the color component converted to a low frequency (600 to 700 Ckllz), and in the circulating four tracks T1 to T4, for example, the right trunk with odd numbered tracks TI and T3 as the center. The frequency difference with the pilot signal is ΔfA, and the frequency difference with the pilot signal of the left trunk is ΔfB. T4
The frequency difference with the pilot signal of the trunk on the right side 1 is set to be ΔfB, and the frequency difference with the pilot signal of the trunk on the left side is set to be ΔfA.

Therefore, the head (6) is the odd-numbered trunk T1. When reproducing T3, if there is a signal component with a frequency difference of Δ rotation as a frequency component of the pilot signal included in the reproduced signal, it is known that the head (6) is shifted to the right, and the frequency difference is ΔfB. If there is a signal component, it can be seen that the head (6) is in the left-shifted position, and furthermore, the frequency difference is Δ rotation and Δ rotation.
It can be seen that tracking is correct when there is no IE component of fB.

Similarly, the head (6) moves to the even numbered track T2゜T.
4, if there is a signal component with a frequency difference of ΔfI3 as a frequency component of the pilot signal included in the reproduced signal, it can be seen that the head (6) is shifted to the right.
Further, if there is a signal component whose frequency difference is Δ rotation, it can be determined that the head (6) is in a left-shifted state.

In this embodiment, the first. Second. Third. The frequencies f1. f2. f3. f4 assigned to the fourth trunk i"l, T2, T3, T4 are fl-10
2 [kH2].

f 2 = 116 CkHz), f 3 = 160 (
kllz), f 4-146 (kR2), so the difference frequencies ΔfA and ΔfB are ΔfA=lf□
−f21 = l f3− f41 =14[kllz
:1・・・・・・・・・(1) ΔrB=1 f2 f3 l=l fl f,i
1-44[:kllz]......(2) is selected.

The Wagyu signal S1 having such content from the head (6) is given to a pilot signal detection circuit (1) having a low-pass filter configuration, and a reproduced pilot signal S2 is obtained by extracting the pilot signal contained in the reproduced signal S1. It is given as a first multiplication input to the multiplication q1 circuit (14).

The reference pilot signal 811 of the lock point control circuit (4) is applied to the summation circuit (14) as a second multiplication input.

Lock point system (j11 circuit (4) is frequency f~f4)
A pilot frequency generation circuit (16) that generates an output at a quadruple pilot frequency, and a rotating drum (not shown).
In connection with this, the video head has a switch circuit (17) which receives a head switching pulse RF-8W (shown in FIG. 3) which summerizes the logic level every time the tape scanning head of the two video heads is switched. In this embodiment, the switch circuit (17) has a quaternary counter circuit that counts every time the levels of the head switching pulses R and F-8W change, and thus the first to fourth trunks are counted from this counter circuit. The gate signals corresponding to T1 to T4 can be sequentially repeated, and the gates are opened by the gate signals of the trunks T1 to T4, respectively, and the pilot frequencies f1 to f1 of the pilot frequency generation circuit (16) are generated as shown in FIG. 3B.
The output of f4 is sequentially sent out as a reference pilot signal 811.

Note that the reference pilot signal 81.1 obtained at the output end of this switch circuit (17) is connected to the signal line (18) during recording.
is sent to the video head as a recording pilot signal via
While scanning 1 to T4, the corresponding frequency f□ to f4
The pilot signals are sequentially applied to the video heads to be recorded in each of the trunks T1 to T4.

In this way, while the head (6) scans the first to fourth trunks T1 to T4, the regenerated pilot signal S2 obtained at the output terminal of the iron signal detection circuit (1) is By multiplying the reference pilot signal 814 generated in synchronization with the track, when there is a tracking error (generated pyrometry), the frequency component contained in the signal S2 has a frequency that is the difference between the frequency component of the reference pilot signal 8110 and the frequency of the reference pilot signal 8110. A multiplication output S12 is obtained that includes a signal component (actually, the upper multiplication output 812 also includes other signal components such as a sum frequency component). 1
and the second difference frequency detection circuit (addition) and (2]). The first difference frequency detection circuit (20) has a multiplication output of 8
When 12 contains a signal component of the difference frequency Δ rotation based on the above-mentioned formula (1), it is extracted and converted into a DC VC by a DC converting circuit c22) having a rectifier circuit configuration, and then converted to the first DC level.
An error detection signal 813 is obtained. Similarly, the second difference frequency detection circuit (21) extracts the signal component of the difference frequency ΔfB based on the above equation (2) in the output 812 and converts it into a direct current circuit ( 23) to obtain a second error detection signal 814.

Here, the head (6) is the first. Second. Third. When the fourth trunk Tl, T2, "13, T4 is to be trunked (therefore the switch circuit (17) switches between each trunk Tl, T2, T4 as shown in FIG. 3B).
3. At the timing corresponding to T4, the frequency becomes f,,f
2. f3. f4 reference biroso Ha No. 811) is shifted to the right, the playback signal S1 of the head (6)
Fig. 30 shows the regenerated pilot signal S2 obtained based on
As shown in 1, Ayana wave Qf□ and f2. f2 and f31 f3
and f4. The pilot signals of f4 and f are included, and the difference frequencies Δf (-f1 to f2) and ΔfB (-
f2 to f3), Δ rotation (= f3 to i4), ΔfB (= f4
~f□) are generated sequentially. On the other hand, if the head (6) is shifted to the left, the reproduced pilot signal S2
The frequencies are sequentially if4 and fl as shown in FIG. 302.

fl and f2. f2 and f3. It now includes the pilot signals of f3 and f4, and accordingly the multiplication output Si2
is the difference frequency ΔfB (=f4~f1) as shown in FIG. 3 D2.
), ΔfA (=f□~f2), ΔfB (=f2~f3)
.

ΔfA (=f3 to f4) is sequentially included.

Thus, as shown in FIGS. 3E and F (for example, indicating a right-shifted state), the first and second error detection signals 813 rise from the DC level or 0 each time the head (6) switches the trunk to be scanned. and 814 to direct current circuit (22) and (
23).

The first and second error detection signals MS13 and S14 are respectively applied to the noise reduction circuit (24) 1.1. From this input and subtraction input, as shown in FIG. This subtraction output 815 is applied to the first input terminal al of the LJJ switching circuit (25), and the polarity is inverted in the inverting circuit (26) and applied to the second input terminal a2. 'Mr ('2AJ) is set to head (6) by head switching pulse 14F-8W.
is scanning the odd-numbered trunk TI, 'r3, it switches to the first input terminal al side, whereas the even-numbered trunk T2. When T4 is running, a switching operation is performed to the second input terminal a2, and thus when the head (6) is shifted to the right as shown in FIG. A level output 83.6 is obtained (on the other hand, in the left-shift state, the DC level output 8316 has a size corresponding to the left-shift plate and becomes negative polarity),
This is sent out as a tracking error signal S3 via an output amplification circuit (27) consisting of a DC amplifier. Incidentally, if the head (6) is shifted to the right, for example, when the reproduced track is an odd-numbered track 'rl, T3, the ih component of the difference frequency ΔfA will be present at the output terminal of the summation circuit (14). The output from the difference frequency detection circuit (addition) side of 1 is sent to the subtraction circuit (24), and at this time, the output from the changeover switch circuit (25) is switched to the first input terminal al side, so there is no stopping. DC 1 novel tracking error signal S3
Send out. On the other hand, ° [the playback track is even 114th T2. At T4, a signal component of the difference frequency Δfr appears at the output end of the Kakegi 1 circuit (14), so that the output from the second difference frequency detection circuit (21) Ill is changed to the subtraction circuit (
24), and at this time, the selector switch 1 (+
Since the l circuit 25) is switched to the second input terminal a2 side, the negative output of the subtraction circuit (24) is inverted in polarity by the inverting circuit (b)) and sent out as a tracking error signal S3 with a positive DC level. do.

Therefore, this tracking error signal S3 is sent to, for example, the phase servo circuit of the capscun servo loop. ffl positive (i
Use it as number j to increase the running speed of the positive cutting tape,
By making a correction to slow down when it is negative, it is possible to correct the phase shift between the video head and the playback trunk, thus realizing correct tracking servo.

As described above, in the tracking control device having the configuration shown in FIG. In step 1, the frequency of the reference pilot signal is changed so that the way the frequency of the pilot signal that is fixed when the reproducing head (6) is tracking correctly matches the way the frequency of the reference pilot signal changes. As a result, when signal components of the difference frequencies occur alternately, a tracking error signal S3 of a magnitude corresponding to the amount of shift is generated, assuming that a shift to the right or a shift to the left occurs. At the same time, the frequencies of the pilot signals recorded on the second sequentially arranged recording tracks f1° f2 . f3. f4. f,
・・・・・・ The frequency difference between adjacent trunks is ΔfA
, ΔfB, ΔfA, ΔfB... By setting the two difference frequencies Δ rotation and ΔfB to circulate alternately, it is possible to determine whether the tracking error is to the right or to the left. Make it.

By doing this, the playback head (6) sequentially moves from wJ1 to
1st → 3rd → 4th → 1st... Trunk T1 →
The reference pilot signal 511 (third
The frequency of figure B) is f1 → f2 → f3 → f4 → f1...
..., if the reproduction head is shifted to the right or left, the difference frequency from the frequency component of the reproduction pilot signal S2 (01 or C2 in Figure 3) is Δ.
fA → ΔfB → Δ rotation → ΔfB... (Figure 3 DI
) or ΔfB → ΔfA → ΔfB → ΔfA...
(D2 in FIG. 3) occurs.

However, in the case of the configuration shown in FIG. 1, in order to obtain a right-shift tracking error signal or a left-shift tracking error (number
) and (23) outputs 813 and 514 (Fig. 3 E and F) are input to the subtraction circuit (24) to create a subtraction output 815 (Fig. 3 G) that changes in an alternating current manner. The inversion circuit (26) and changeover switch circuit (
25) to partially invert the polarity of the subtracted output 815, thus obtaining a tracking error signal 83 (FIG. 3-1) with a positive or negative DC level in case of right or left deviation, respectively.

In this way, in order to create the tracking error signal S3 in the case of the 4''14 configuration in the m1 diagram, a changeover switch circuit (25) is used to invert the polarity of the subtraction output 815 in synchronization with the head switching signal ratio F-8W. In addition to requiring an inverting circuit (26), a control system for synchronously operating the changeover switch circuit (c25) is also essential.

[Purpose of the invention]

The present invention aims to simplify fAi of the overall configuration by reducing the changeover switch circuit (25) and inverting circuit (26) of the configuration shown in FIG. 1 to 5 so that they can be omitted. .

[Summary of the invention]

In order to achieve such an object, the present invention rearranges the order of changes in the frequency of the reference pilot signal so that it does not match the tracking order of the reproducing head, so that it always remains constant even when the restraining head deviates from the correct tracking state. (i.e. either ∆ rotation or ∆fB)
Only the i-d component of the difference frequency can be obtained.

Embodiment Below, an embodiment of the present invention will be described in detail with reference to FIG. 4, in which parts corresponding to those in the first embodiment are denoted by the same reference numerals.

In this case, the tracking control device omits the changeover switch circuit (25) and the inversion circuit (26) in FIG. As shown in FIG. 3, the reference pilot signals f4 and f2 corresponding to even-numbered tracks are in the same order as if they were swapped with each other.

In this case, the switch circuit (17) has a counter circuit that counts in response to the head switching pulse ILI"-8W as described above with reference to FIG. 1, and during recording, the output of this counter circuit is used to change the pilot frequency from f1 to f.
By switching in the order of 2 → f3 → f4 → f1..., the first → second → third → fourth → first...
Tracks T1→T2→T3→T4→T1...
Record the pilot signal on... In addition to this, when receiving a separate recording hold switching signal S4 indicating that this is the playback mode, the switch circuit (17) converts the output code of the counter circuit to change the pilot frequency to f.
1→f4→f3→f2→f1 .

In the configuration of FIG. 4, the head (6) is the first. 2nd゜3rd. Fourth track TI, T2. T3. When trying to track T4, the reference pilot signal 511 (
FIG. 5B) shows each track TI, T2. At the timing corresponding to T3°T4, the frequency changes to fl, f4°f3. It becomes f2. In this state, if the head (6) is shifted to the right, the reproduced pilot signal S2 includes tracks TI, T2, and T3 as shown in FIG. 5C1.

T4 to frequencies f0 and f2. f2 and f3 #F3, ff and fl pilot signals are included.

1 4 Therefore, the multiplication output 812 of the multiplication circuit (14) is as shown in FIG.
As shown in I-, the frequency f1 of the reference pilot signal all
゜f4. f3. f2, the track TI that the head (6) is trying to track, T2. T3. T4 pilot signal (this is called the main pilot signal) frequency f□, f2. f31 f4 and head (6)
The adjacent track T2. T3. T4. A signal component having a frequency different from the frequency f2 t f3 + f4, fl of the TI pilot signal (this is called a crosstalk pilot signal) is included in the multiplication output 812 of the multiplication circuit (14).

Here, the frequency f1 of the reference pilot signal 811. f4゜f3. f2 and crosstalk pilot signal frequency f2
+f3tf4. The difference frequency with f is sequentially ΔfA (=f.

~ f2), Δ rotation (-f4 ~ f3), ΔfA (= f3 ~ f
4).

ΔfA(=f2~f1), which is included in the calculated power 8120)) Figure 5 DI). Therefore, the error detection signal 813 of the DC conversion circuit (22) on the difference frequency detection circuit (20) side is shifted to the right at the timing when the head (6) is scanning any track of the trunks T1 to T4, as shown in FIG. 5 E1. This results in a DC level corresponding to the length facing the momentary connection trunk.

Incidentally, for the first and third trunks T1 and T3, the frequencies f□ and f3 of the reference pilot signal 811 are equal to the frequencies f0 and f3 of the main pilot signal, so no signal component of the difference frequency is sent to the multiplication output 812. Further, for the second and fourth tracks T2 and T4, the reference pilot signal 8110 frequencies f4 and f2 are the difference frequencies (=f4 to f4) from the frequencies f2 and f4 of the main pilot signal.
2) is generated in the multiplication output 812, and this difference frequency is ΔfA (14 (kHz) from equation (1) above)
) or ΔfB (44 (kHz) from equation (2) above)
) is not equal to any of the values (=146-116=addition [
klIz]), so the difference frequency Δ rotation and Δ
Difference frequency detection circuits (20) and (21) for detecting fB
It does not affect the outputs of the DC conversion circuits (22) and (23).

Therefore, since the detection circuit (21) of the difference frequency ΔfB also does not produce a detection output, the error detection signal 51 of the DC conversion circuit (73)
4 (FIG. 5 F1..) will maintain the 0 level.

Therefore, the subtraction circuit (24) has a difference frequency Δ rotation detection circuit (
Since only the error detection signal 813 on the (additional side) side is given as an addition input, it is directly sent as the subtraction output 815 (Gl in Fig. 5) of the m8 circuit (24), and is further outputted as a positive DC signal via the output amplifier circuit (27). This will be sent as a level right shift dragging error signal S3.

The above describes the operation when the head (6) is shifted to the right. However, if the head (6) is shifted to the left, playback will not be possible.
2, each track TI, T2 . T
3. From T4, frequencies f4 and f□, fl and f2. f2
and f31 The pilot signals of f3 and f4 are included. Therefore, in this case, the multiplication output 812 of the multiplication circuit (14)
As shown in FIG. 5D2, the frequency f1+f4 . of the reference pilot signal 811. f3. f2 and the frequency of the crosstalk pilot signal f4. The frequency ΔfB (= fl - f4), ΔfB (= f4 ~
f1), ΔfB (= f3 to f2), ΔfB (two f2 to f
3) is generated, which is detected by the difference frequency ΔfB detection circuit (21) and sent from the DC converting circuit (23) to the DC level error detection No. 5 514 (corresponding to the left-shifted view of the head (6)). Fig. 5 F2) is obtained.

In contrast, reference pilot signals 8110 frequencies f1 and f3 for the first and third trunks T1 and T3
Since it is equal to the frequencies f□ and f3 of the main pilot signal, the signal component of the difference frequency is not sent to the multiplication 3'F output S2. Further, for the second and fourth trunks T2 and T4, the difference frequency between the reference pilot signal 8110 frequencies f4 and f2 and the main pilot signal frequencies f2 and f4 is not equal to either Δ rotation or ΔfB, so the difference frequency detection circuit It does not affect the error detection signals SI3 and 814 of the DC conversion circuits (22) and (23) in (Add) and (21). Therefore, the error detection signal 513 (E2 in FIG. 5) on the side of the difference frequency ΔfA maintains the O level.

In this way, only the error detection signal 814 on the side of the detection circuit (21) of the difference frequency ΔfB is given to the subtraction circuit (24) as a subtraction input, so this is directly applied to the subtraction circuit (24).
) is sent as the subtraction output 515 (Fig. 5 02),
Furthermore, it is sent out as a left shift tracking error signal S3 at a negative DC level via the output amplifier circuit (27).

As described above, according to the configuration shown in FIG. 4, compared to the case shown in FIG.
4, it is possible to obtain a tracking control device with a simple configuration that does not require the changeover switch circuit (25) and inversion circuit (26) shown in FIG.

In the above description, 2! for the even-numbered second and fourth tracks T2 and T4! i! Although the frequencies f2 and f4 of the i quasi-pilot signals are swapped, the above-mentioned problem may also be achieved by swapping the frequencies f1 and f3 of the reference pilot signals for the odd-numbered first and third trunks T1 and T3. You can get the same effect as in the case.

[Application example]

Although the present invention has been described above as being applied to tracking control of a playback head in a recording mode, the present invention is not limited to this, but can be applied widely to the case where a head is trunked in each mode in an ATF type tracking control device. Can be applied.

For example, when obtaining a still image consisting of a still image, a frame-by-frame image, or a reverse frame-by-frame image, the shaded area (
3o) and (31) (the scanning trajectory of the head is 14
If the head can be tracked so that the overlapping area of the adjacent trunks is equal, noise bars can be prevented from occurring in the still image. Head switching 4i with a weight of 6 on the A and B heads as shown: A method of giving a reference pilot signal S11 of the same frequency as the pilot signal that is iC0 to the trunk to be tracked at the position of No. 3 F-8W is considered. It will be done.

In this case, if the reference pilot signal 8110 frequencies corresponding to the second and fourth tracks T2 and T4 are set to f4 and f2, respectively, as shown in FIG. The circuit can be omitted. In addition, B1 to B4 in FIG. 7 are tracks T, respectively.
1 and T2 to T1 and T4. If you select only one of these states, you can obtain a methyl image, and if you sequentially switch between the four states, you can obtain a frame-by-frame image or a reverse frame-by-frame image. A sent image is obtained.

Also, in the fast forward mode, for example, when reproducing images in triple speed mode along the head scanning locus (32) as shown in FIG. 8, the reference pilot signal 511 ( For example, the frequency change in Fig. 9B) is f1→f4→f3→f2→f0...
By making the following changes, the same effect as in the above case can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the frequency of crosstalk pilot No. 15 obtained from the trunk adjacent to the track to be tracked due to head misalignment,
By changing the frequency of the reference pilot signal 811 each time the trunk scanned by the head is changed so that the frequency difference from the frequency of the corresponding reference pilot signal always becomes a predetermined value ΔrB or ΔrB, Since it is possible to immediately obtain a DC level error detection signal based on the signal component of the difference frequency of the predetermined value and use this error detection signal almost as it is as a tracking error signal, it is possible to use this error detection signal almost directly as a tracking error signal. Therefore, the changeover switch circuit (25) and the inverting circuit (26) can be omitted, and a tracking control device that can simplify the 41'4 configuration can be obtained.

[Brief explanation of the drawing]

Figure 1 shows JltX, an ATF type tracking control device.
3! l! Figure 2 is a block diagram showing the 411 configuration, Figure 2 is a route map showing the track pattern recorded on the tape, and Figure 3 is a route map showing the track pattern recorded on the tape.
4 is a block diagram showing an embodiment of the tracking control device according to the present invention. FIG. 5 is a signal waveform diagram showing signals of each part of the device. 9 to 9 are route maps showing examples of application of the present invention. (1)...Pilot signal detection circuit, (3)...Error signal formation circuit, (4)...Lock point control circuit, (
14) Multiplication circuit, (16) Pilot frequency generation circuit, (■7) Switch circuit, (20)
, (21)... 1st. 20th difference frequency detection circuit, (
22) , (2:3)...DC converting circuit, (24)
...Decreased power. Circuit, (25)...changeover switch circuit, C2t3)・
... Inversion circuit, (27) ... Output amplification circuit. 3 3rd 4th Seki 5th 6th Figure

Claims (1)

[Claims] Sequentially record a pilot signal whose frequency changes cyclically for each track, and track it because the head is misaligned during playback.The frequency of the reproduced pilot signal reproduced from the trunk adjacent to the trunk and the reference pilot signal In a tracking a'lJ control device, the tracking error signal corresponding to the direction and value of the head deviation is obtained based on the signal component having the difference frequency. , characterized in that the frequency of the reference pilot No. 46 is cyclically changed so that the difference from the frequency of the regenerated pilot signal regenerated from the instantaneously connected trunk becomes a predetermined value. Trunking control device fjiL.