JPH01184651A - Tracking control device - Google Patents

Abstract

PURPOSE:To prevent an adverse effect by the dislocation of tracking angle at the time of reproducing by adding with first and second tracking error signals based on first and the second tracking control signals of both sides of the each track of a tape and tracking controlling. CONSTITUTION:First and second tracking signals are detected from a first tracking control signal and a second tracking control signal recorded at both sides of each track of a tape respectively by a first tracking error detecting means 1 and a second tracking error detecting means 2 at the time of reproducing. The error signals are added by an error signal adding means 3, and a tracking control is executed based on an adding signal. Thus, the normal/reverse inversion, etc., of the tracking control signal by the dislocation of tracking angle are not generated, a track runout, the S/N of a reproducing signal and the lowering of an error rate are suppressed, and playability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tracking control device, and in particular, to a tracking control device.
The present invention relates to a tracking control device for a helical scan type recording/reproducing device or a reproducing device such as a T.

[Conventional technology]

R-DAT is a rotary head.
) type DAT (Digital Audio Tape)
recorder) and a rotating head type V T
It records and reproduces signals using a helical scan method similar to R (Video Tape Recorder). This R-DAT, for example, digitizes and time-compresses data signals such as stereo music and records them on a 13.6 μm wide track having an angle of 6°22"59.5" with respect to the tape running direction. It is done like this. Also, as per the R-DAT standard, ATF for tracking control is provided on both sides of the part (PCM part) where data signals such as stereo music are recorded.
(Automatic Track Finding)
Signals, sub-codes (S [IB code), etc. that indicate the elapsed time of the song, index numbers, etc.] are recorded, and margins are provided at both ends of each track.

FIG. 7 is a schematic diagram showing an example of a helical scan type rotary head section. As shown in the figure, R-DAT
A rotary head unit such as the above is provided with two paddles 101a and 101b that are opposed to each other by, for example, 180 degrees to a rotating drum 101 that rotates at a constant cycle. Further, the rotary head shown in the figure is for the case where the tape 102 is wound around the rotary drum 101 at a wrap angle of 180° and the running of the tape 102 is controlled.

Fig. 8 is a diagram for explaining the track angle deviation when a tape recorded by the helical scan method is played back in the state shown in Fig. 7, and Fig. 8 (a) shows the head position when there is no track angle deviation. Trace Locus: FIG. 2B shows the head trace trajectory (broken line in the figure) when a track angle deviation occurs. for example,
If the recording deck and playback deck are different, the track angle of the head on the recording deck and the playback deck,
The track angle of the head may be misaligned in the key. This track angle deviation may be due to slightly different adjustment of the tape running system depending on each deck.
This occurs due to the fact that the mounting of the rotating head includes some errors in accuracy, and the track angle changes due to thermal expansion of the traveling system due to temperature changes.

As shown in FIG. 8(a), when there is no track angle deviation, the bed 10 provided on the rotating drum 101
1a and 101b accurately trace on the right track 121 and on track 122, respectively. However, Fig. 8(b)
As shown in FIG.
1b will be traced diagonally on tracks 123 and 124, respectively.

By the way, in the case of R-DAT, the track angle is approximately 6°23' with respect to the tape running direction.
Further, the width of one track is 13.6 μm. In such an R-DAT, for example, if a track angle deviation of about 2 degrees (minutes) occurs, a head tracing a predetermined track at the front end may trace an adjacent track at the rear end. become.

FIG. 9 is a waveform diagram showing the relationship between track angle deviation and detected tracking error, and FIG. 9(a) is a waveform diagram when there is no track angle deviation as shown in FIG. 8(a). FIG. 8(b) is a waveform diagram when a track angle shift as shown in FIG. 8(b) occurs. The waveform diagram in Fig. 9 shows that two heads are provided 180° opposite to the rotating drum in Fig. 7, and the tape is wound around the rotating drum at a wrap angle of 180° to control its running. This shows the case of a rotating head. Specifically, as shown in FIG.
One helad 101a provided on the track 12
H123), the other head 101
b will begin tracing the next track 122 (124).

First, if there is no track angle deviation, Fig. 8(a)
and track 12 as shown in FIG. 9(a).
1 (e.g., R-DAT
The ATF signals 121a# and 121b are detected by the - head 101a at times t2 and t, and the tracking signals 122a and 122b recorded on the track 122 are detected by the other head 101b at times t4 and t. Detected in here,
These tracking signals 121! , 121b.

A tracking error detected from 122a and 122b indicates that no track angle deviation has occurred and the two heads 101a and 101b are aligned with tracks 121 and 122b.
22, their values are zero.

Next, when a track angle deviation occurs, as shown in FIG. 8(b) and FIG. 9(b), the tracking signal 123a recorded on the track 123 and 1
23b is detected by one head 101a at times T2 and T3, and the tracking signal 124a right and 124b recorded on track 124 is detected by the other head 101b at times T4 and T. Here, these tracking signals 123a
, 123b, 124a, and 124b, the tracking error detected from the tracking signals 123a and 124b is due to a track angle shift such that the track angle during reproduction is larger than that during recording.
The tracking error corresponding to 24a is negative, and the tracking error corresponding to tracking signals 123b and 124b is positive.

[Problem to be solved by the invention]

FIG. 10 is a diagram for explaining the problems of a conventional tracking control device. As shown in the figure, in conventional tracking control devices, the track angle during playback is greater than that during recording due to, for example, a difference between the deck for recording signals on tape and the deck for playing back the recorded tape. If there is a track angle deviation such that the track angle becomes large, when the head 101a tracing the track 125 detects the tracking signal 125a at the front end, the tracking error is negative (in the figure, the head 1
01a is shifted to the left). Therefore, in conventional tracking control devices, the tape running motor is servo-controlled to increase the tape running speed (to shift the head 101a to the right in the figure) in order to cancel the detected negative tracking error. become.

However, if a track angle deviation occurs, even if the tracking signal 125a at the front end is not detected and servo control is not performed, the tracking error will be correct at the position where the tracking signal 125b at the rear end is recorded (see Figure , the head 101a is shifted to the right).

Therefore, when the tracking signal 125a at the front end where the tracking error is negative is detected and the travel motor is servo-controlled to cancel the negative tracking error, as in the conventional tracking control device, the tracking signal 125a at the rear end At the position where 125b is recorded,
This will further increase the positive tracking error. Further, some conventional tracking control devices are designed to reduce the response sensitivity of servo control so that a certain degree of track angle deviation can be tolerated. However, if the sensitivity of the servo control is made dull, it becomes difficult to remove the effects of normal disturbance loads and perform sufficient head tracking control, and to shorten the time required to achieve normal tracking at startup. .

In this way, conventional tracking control devices cannot perform effective servo control both when there is no track angle deviation and when there is a track angle deviation, and it is difficult to prevent tracking errors caused by track angle deviation. It may increase and disturb servo control, or cause the S/
This has had problems in that it lowers the N ratio and error rate, and furthermore, it causes off-track.

In view of the problems of the conventional tracking control device described above, the present invention aims to improve playability by suppressing off-tracking due to track angle deviation during playback, and reducing the S/N ratio and error rate of the playback signal. With the goal.

[Means to solve the problem]

FIG. 1 is a block diagram showing the principle of a tracking control device according to the present invention.

According to the present invention, when reproducing a tape recorded using the helical scan method, a tracking error is detected from two tracking signals, the first and second tracking signals recorded on both sides of each track of the tape, and the tracking error is detected from the first and second tracking signals recorded on both sides of each track of the tape. A tracking control device that servo-controls a traveling speed, wherein the first
a first tracking error detection means 1 for detecting a first tracking error corresponding to the first tracking signal from the tracking signal; and a second tracking error detection means 1 for detecting a first tracking error corresponding to the second tracking signal from the second tracking signal. a second tracking error detection means 2 for detecting a tracking error; and an error signal addition means 3 for adding the first and second tracking errors;
A tracking control device is provided, characterized in that tracking control is performed using a signal obtained by adding a second tracking error and a second tracking error.

[For production]

According to the tracking control device of the present invention having the above-described configuration, the first tracking error detection means 1 detects the first tracking error corresponding to the first tracking signal, and the second tracking error detection means 1 detects the first tracking error corresponding to the first tracking signal. The means 2 generates a second tracking signal corresponding to the second tracking signal.
tracking error is detected. Furthermore, the error signal adding means 3 adds the first tracking error and the second tracking error. Then, tracking control is performed using a signal obtained by adding the first tracking error and the second tracking error.

By the way, when a track angle shift occurs, the first tracking error and the second tracking error each include tracking error components with the same error amount and different polarities. Therefore, by adding the first tracking error and the second tracking error, the tracking error component caused by the track angle deviation is canceled out, and the normal tracking error that is not caused by the track angle deviation near the center of each track is canceled out. It is possible to calculate and perform tracking control.

That is, the tracking control device of the present invention can perform effective servo control even when a track angle deviation occurs by performing tracking control using a signal obtained by adding two tracking errors.

〔Example〕

Hereinafter, embodiments of a tracking control device according to the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block circuit diagram showing an embodiment of the tracking control device of the present invention, in which independent tracking error detection circuits are provided as first and second tracking error detection means. As shown in the figure, the signals reproduced by the reproduction equalizer amplifier 4 are supplied to tracking error detection circuits 1 and 2, respectively. This reproduction equalizer amplifier 4 is, for example, a two
The signals reproduced by the two heads 101a and 101b are equalized and amplified and then supplied to the two tracking error detection circuits 1 and 2.

Tracking error detection circuits 1 and 2 have a tracking signal detection timing pulse S1 at the rear end and a tracking signal detection timing pulse S at the front end, respectively.
2 is supplied, so that the tracking error detection circuits 1 and 2 can selectively detect the tracking signal at the rear end and the tracking signal at the front end of each track. These timing pulses Sl and S2 are, for example, synchronized by sink filters 61 . Detector 62
The tracking signal detection timing pulse is generated by a tracking signal detection timing pulse generation circuit 6 composed of 63, 64, etc. That is, one input terminal of AND gates 63 and 64 is supplied with an inverted mask signal and a mask signal, respectively, and a sync filter 61 is supplied to the other input terminal of AND gates 3 and 64.
A sync signal (for example, an ATF sync signal) recorded on each track extracted from the output signal of the reproduction equalizer amplifier 4 is supplied by the output signal and the detector 62 .

As a result, tracking signal detection timing pulses S at the front end and rear end are output from the AND gates 63 and 64.
2 and Sl are output.

Tracking error detection circuits 1 and 2 have the same configuration and include pilot filters 11 and 21, respectively.
．． Detection circuit 12.22. Sample hold circuit 13, 2
3 and 16.26. It includes delay circuits 14 and 24 and adders 15 and 25. For example, in the tracking error detection circuit 1, the output signal of the reproduction equalizer amplifier 4 is supplied to the pilot filter 11, and the pilot filter 11 and the detection circuit 12 use the pilot signal recorded at both ends of each track (for example,
ATF pilot signal) is extracted. Further, the output signal of the detection circuit 12 is supplied to the negative end of the sample hold circuit 13 and the adder 15. Furthermore, the output signal of the sample-and-hold circuit 13 is supplied to the plus end of the adder 15, and the output signal of the adder 1
5 is output from the tracking error detection circuit 1 via the sample hold circuit 16 as the tracking error signal SKI. Here, the tracking signal detection timing pulse S1 at the rear end is supplied to the sample hold circuit 13, and the tracking signal detection timing pulse S1 at the rear end is supplied to the sample hold circuit 16 via the delay circuit 14. ing. As a result, the tracking error detection circuit 1 detects a tracking error signal 3 at the rear end corresponding to the pilot signal (tracking signal) at the rear end of each track.
21 will be output. Similarly, the tracking error detection circuit 2 generates a front end tracking error signal S2 corresponding to the front end pilot signal in each track.
Output □. And tracking error detection circuit 1
and two tracking error signals S21 corresponding to the rear end and front end pilot signals output from S21.
and S2□ are respectively supplied to the error signal addition circuit 3.

The error signal addition circuit 3 includes resistors 31, 32 . A delay circuit 33 and a switch circuit 34 are provided. In the error signal adding circuit 3, the output signals (tracking error signals) S2 and S22 of the tracking error detection circuits 1 and 2 are added by resistors 31 and 32,
The added signal S3 is supplied to the input terminal of the switch circuit 340. Here, the error signal addition circuit 3 adds the two tracking error signals S2I and S22 by removing the tracking error caused by the track angle deviation and calculating the tracking error near the center of the two tracking signals on each track. This is to do so. Further, the switch circuit 34 is controlled on/off by a switching pulse S output from the delay circuit 33 to which the tracking signal detection timing pulse S1 of the rear end portion is supplied.

Furthermore, the output signal of the switch circuit 34 is transmitted to the capacitive element 51.
A sample and hold circuit 5 consisting of an amplifier 52 and an amplifier 52
The sample and hold circuit 5 then outputs a servo control signal Ss for controlling the tape running motor.

FIG. 3 is a timing diagram for explaining the operation of the tracking control device shown in FIG. This figure shows the case of a rotary head in which the tape is wound at a wrap angle of 180° and its travel is controlled. As shown in Figure 3(a), the reproduced envelope (tracking error signal) has a waveform in which the signals recorded on each track are continuously reproduced alternately between one head and the other head. ing. That is, the signals 301 and 303 detected by one head and the signal 302 detected by the other head are alternately successive.

As shown in FIG. 3(b), the front end tracking signal detection timing pulse S is the front end signal of the two tracking signals (for example, the ATF signal in R-DAT) recorded on each track. 301a, 30
2a and 303a are signals that become high level corresponding to the detected position, and the tracking signal detection timing pulse S at the rear end is applied to each track as shown in FIG. 3(C). Of the two recorded tracking signals, rear end signals 301b, 302b, 303
b is a signal that becomes high level corresponding to the detected position. These tracking signal detection timing pulses S
1 and S2 are supplied to the tracking error detection circuits 1 and 2, and the tracking error detection circuit 2 for the front end tracking signal outputs a tracking error signal S22 as shown in FIG. 3(d). Further, the tracking error detection circuit 1 for tracking signals at the rear end outputs a tracking error signal Sat as shown in FIG. 3(e).

A signal S obtained by adding two tracking error signals S21 and 322 by the error signal addition circuit 3.

As shown in FIG. 3(f), the fluctuation component due to the track angle deviation is canceled out, and the general deviation component of the head relative to the track remains. This addition signal S3 is supplied to the input terminal of the switch circuit 34.0, and is controlled on/off by a switching pulse S as shown in FIG. 3(g). This switching pulse S4 is a signal obtained by delaying the tracking signal detection timing pulse S at the rear end of the track by the delay circuit 33, and is a signal obtained by delaying the tracking signal detection timing pulse S at the rear end of the track, and is a signal obtained by delaying the tracking signal detection timing pulse S at the rear end of the track.
This is to turn on the switch circuit 34 after the signal 2□ is reliably output, and to send the addition signal Sa to the sample and hold circuit 5. As a result of the above, the sample and hold circuit 5 outputs the servo control signal S5 as shown in FIG. 3(h).

The servo control signal Ss is then supplied to the servo control circuit, and the tape running motor is servo-controlled in accordance with the tracking error of the servo control signal S.

FIG. 4 is a diagram for explaining tracking control by the tracking control device of FIG. 2. As shown in the figure, the tracking control by the tracking control device of FIG. The tracking error component caused by the track angle shift is canceled out from the two tracking errors calculated from the two tracking signals 41a and 41b. Then, near the center of the two tracking signals 41a and 41b (near the center of each track), a normal tracking error that is not caused by track angle deviation is calculated and tracking control is performed. That is, the tracking control device of this embodiment can accurately detect the PCM signal 41C in which the target signal is recorded over a wide range of areas.

FIG. 5 is a block circuit diagram showing a modification of the tracking control device shown in FIG. 2. The tracking control device shown in FIG. 5 is a modification of the tracking control device shown in FIG. 2, in which the error signal addition circuit 3 is composed of resistors 31 and 32. The error signal addition circuit 3 adds the output signals of the tracking error detection circuits 1 and 2 as they are, and the added signal S3 is supplied to the servo control circuit.

FIG. 6 is a block circuit diagram showing another embodiment of the tracking control device of the present invention. The tracking control device in FIG. 6 has one tracking error detection circuit 100 and two sample-hold circuits, whereas the tracking control devices in FIGS. 2 and 5 have two tracking error detection circuits. 10 and 20 constitute first and second tracking error detection means 1 and 2. That is, the output signal of the tracking error detection circuit 100 includes, for example, two tracking error signals 321 and S2□ corresponding to the pilot signals at the rear end and the front end. These two tracking error signals S21 and S22 are divided by a sample hold circuit 10 supplied with the tracking signal detection timing pulse Sl of the rear end and a sample hold circuit 20 supplied with the tracking signal detection timing pulse S2 of the front end. and are respectively supplied to the error signal addition circuit 3. This tracking control device requires only one tracking error detection circuit, and the circuit can be simplified.

In the embodiments described above, the tracking error detection circuit, the tracking signal detection timing pulse generation circuit, the error signal addition circuit 3, etc. are not limited to those shown in FIG. 2, and may have various circuit configurations. It goes without saying that the tracking control device of this embodiment can also be used for tracking control other than R-DAT.

〔Effect of the invention〕

As described above in detail, the tracking control device according to the present invention performs tracking control using a signal obtained by adding tracking errors corresponding to two tracking signals on each track, thereby preventing track deviations due to track angle deviation during playback. , S/ of the reproduced signal
It is possible to suppress a decrease in the N ratio and error rate and improve playability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the principle of a tracking control device according to the present invention, FIG. 2 is a block circuit diagram showing an embodiment of the tracking control device of the present invention, and FIG. 3 is a block diagram showing the principle of a tracking control device according to the present invention. 4 is a diagram for explaining tracking control by the tracking control device in FIG. 2; FIG. 5 is a block circuit diagram showing a modification of the tracking control device in FIG. 2; Fig. 6 is a block circuit diagram showing another embodiment of the tracking control device of the present invention, Fig. 7 is a schematic diagram showing an example of a rotating head section using the helical scan method, and Fig. 8 is a schematic diagram showing an example of a rotating head section using the helical scan method. Figure 7 is a diagram to explain the track angle deviation when playing back the tape in the state shown in Figure 7. Figure 9 is a waveform diagram showing the relationship between the track angle deviation and the detected tracking error. Figure 10 is the conventional tracking. FIG. 3 is a diagram for explaining problems with the control device. (Explanation of symbols) l...first tracking error detection circuit, 2...
2nd tracking error detection circuit, 3...Error signal addition circuit, 4...Reproduction equalizer amplifier, 5...Sample hold circuit, 6...Tracking signal detection timing pulse generation circuit, SI...Track Tracking signal detection timing pulse at the rear end, S2...Tracking signal detection timing pulse at the front end of the track, S3...Signal obtained by adding tracking errors at the front and rear ends, S4...Switching pulse, S5... Servo control signal, S21... Tracking error signal at the rear end of the track, S22... Tracking error signal at the front end of the track.

Claims (1)

[Claims] 1. When playing back a tape recorded by the helical scan method, the first track recorded on both sides of each track of the tape
and a second tracking signal, the tracking control device detects a tracking error from two tracking signals and servo-controls the running speed of the tape, the first tracking signal corresponding to the first tracking signal. a first tracking error detection means for detecting a tracking error; a second tracking error detection means for detecting a second tracking error corresponding to the second tracking signal from the second tracking signal; and error signal addition means for adding a second tracking error, and tracking control is performed using a signal obtained by adding the first and second tracking errors. 2. The apparatus according to claim 1, wherein the first and second tracking error detection means each include an independent tracking error detection circuit. 3. The device according to claim 1, wherein the first and second tracking error detection means have one tracking error detection circuit in common. 4. The apparatus according to claim 1, wherein the error signal addition means adds the first and second tracking errors for each track. 5. The error signal adding means adds the first and second tracking signals after the first and second tracking signals are detected.
5. The apparatus according to claim 4, further comprising a delay circuit for adding tracking errors of . 6. Claim 1, wherein the error signal addition means is configured to add two tracking errors corresponding to first and second tracking signals successively detected on each of adjacent tracks. Equipment described in Section.