JPH0279245A - Information signal regenerating device - Google Patents

Abstract

PURPOSE:To enable the good tracking control even in the case of recording defect and regenerating defect, etc., by inhibiting the use of a tracking error signal when one signal or both signals of a track cannot be regenerated due to some cause or other. CONSTITUTION:The subject device is constituted of means 6-9 and 12-15 for generating a tracking control signal based on a level difference of a regenerative pilot signal from both adjacent tracks to a main reproducing track for individual heads 2a-2f of a reproducing means and an inhibiting means (mean value calculating circuit) 19 for inhibiting the use for the tracking control signal generating means 6-9 and 12-15 with the pilot signal regenerated by a head tracing the adjacent tracks to a head generating a drop-out in a regenerative signal and a track traced by this head during a period of generating the drop-out at least at one of plural heads 2a-2f based on a detected output of a drop-out detecting means 5. By this method, even in the case of a recording defect, a defective tracking control signal is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information signal reproducing device, and more particularly to a device for reproducing information signals from a plurality of parallel tracks each recording a pilot signal for tracking control along with an information signal. Regarding.

[Conventional technology]

In this specification, a helical scan type magnetic recording/reproducing apparatus will be described as an example in which a rotary head records or reproduces signals at an angle with respect to the longitudinal direction of a magnetic tape. This type of magnetic recording and reproducing apparatus requires a tracking device that accurately scans a rotary head over a track during reproduction, and various types of tracking devices are known.

For example, a track dedicated to tracking is provided in the longitudinal direction along the side edge of the magnetic tape, and a control pulse (C
A CTL method for recording TL) is known.

During recording, this method generates a pulse signal synchronized with the rotation of the drum, records this as a CTL signal on the side edge of the tape using a dedicated fixed head, and during playback, this CT
The running phase of the magnetic tape is controlled by detecting the L signal. This allows the rotary head to scan over the drag to be scanned.

However, due to the presence of longitudinal tracks, this CTL method requires a fixed head, and when configuring the device, the tape path etc. must be arranged with the fixed head in mind, which is very disadvantageous. be. Furthermore, since the mounting accuracy of this fixed head directly affects the tracking accuracy, it is not suitable for a high-precision tracking device for high-density recording by narrowing the track. Furthermore, for the same reason, it is difficult to maintain device compatibility, and the cost increases with the addition of a dedicated head.

In an apparatus that performs high-density recording and reproduction under such a background, it is effective to record a pilot signal together with an information signal on a helical track.

A method using this type of pilot signal is the so-called 8
The 4-frequency pilot system used in milliformat video tape recorders (VTRs) and the rotating head type digital audio recorder (R-DAT)
The area division pilot system adopted in 2007 is well known. In the former 4-frequency pilot method, during recording, four types of pilot signals having different frequencies are sequentially and cyclically switched for each track period, frequency-multiplexed with the video signal and recorded on each video track, and during playback, the main signal is By comparing the levels of two types of beat signals obtained by crosstalk from adjacent tracks on both sides of the track being played back, the direction and amount of tracking deviation can be detected, and accurate scanning can be performed on the video track to be scanned. The rotating video head follows and scans the image.

On the other hand, in the latter area-divided pilot method, a dedicated area for recording pilot signals is provided within a recording track, and a plurality of types of pilot signals are recorded.

During playback, the amount of crosstalk between pilot signals from both adjacent tracks within the dedicated area is detected, and tracking control is performed so that they are equal to each other.

Here, the area division pilot system will be explained in more detail by taking as an example a system applied to R-DAT. Figure 6 shows the format recorded in R-DAT. Areas of ATFI and ATF2 in the figure (ATF:
Automatic Track Finding
) is a dedicated area for pilot signals for performing tracking control so that the rotary head correctly scans the recording track during reproduction. A low frequency f1 signal with little azimuth loss is recorded as a pilot signal in at least part of the areas ATFI and ATF2 (f in Fig. 6).
This is used to detect the level of crosstalk from both adjacent tracks during playback, and to obtain a tracking error signal according to the level difference.

Further, in the areas ATFI and ATF2, a sync signal for determining the position where the pilot signal of the frequency ft is recorded is further recorded. As a sync signal, a sync signal f2 with a frequency f2 is placed on the positive azimuth track (A), and a sync signal with a frequency f3 is placed on the negative azimuth track (B) at a predetermined position (6th
In the figure r2. '3)). frequency f4
The erase signal is recorded for the purpose of erasing the signal before recording.

The pilot signals of frequency fl are all located at different positions in a certain track and both adjacent tracks, and are arranged so that the pilot signals of both adjacent tracks of the certain track can be reproduced and detected at different timings. The recording pattern of such a pilot signal is as shown in FIG. 6 (a four-track sequence is formed by the combination of the above signals, and is controlled so that tracking is performed on a desired track).

Furthermore, in Japanese Patent Application No. 62-265560 previously filed by the present applicant as one of this type of area division pilot systems, two types of pilot signals are used and tracking control is similarly achieved.

[Problem that the invention seeks to solve]

However, even with the pilot method, which is thought to be suitable for high-density recording, in conventional methods, pilot signals are partially unrecorded due to head clogging (clog) that occurs during recording and playback, or damage to the tape. Or it becomes unplayed. As a result, the tracking error signal becomes an abnormal value. This forms a tracking error signal that follows the difference in pilot signal crosstalk between adjacent tracks, so if one or both signals of these two tracks are not regenerated for some reason, there will be a large error in the tracking error signal. This phenomenon disturbs the control of the capstan and adversely affects the reproduced signal.

Against this background, the present invention provides an information signal reproducing device having a plurality of heads for tracing adjacent tracks.
The objective is to enable good tracking control even if there are recording defects, reproduction defects, etc.

[Means for solving problems]

According to the present invention, in an apparatus for reproducing information signals from a plurality of parallel tracks in which a tracking control pilot signal is recorded together with an information signal, a plurality of tracks tracing adjacent tracks are provided. a reproduction means having a head; a means for generating a tracking control signal based on a level difference between reproduction pilot signals from both adjacent tracks of a main reproduction track of each head of the reproduction means; Dropout detection means detects, and during a period in which dropout occurs in at least one of the plurality of heads based on the detection output of the dropout detection means, the head in which dropout occurs in the reproduced signal and the head The tracking control signal generating means is configured to include means for prohibiting a pilot signal reproduced by a head tracing a track adjacent to a track to be traced from being used by the tracking control signal generating means.

[For production]

By configuring as described above, defective tracking control can be avoided even when the playback head itself cannot reproduce signals or when recordings on both adjacent tracks of the main playback track used to form the tracking control signal are defective. No signal was generated.

〔Example〕

Hereinafter, the present invention will be described in Japanese Patent Application No. 1983-2, which was previously filed by the present applicant.
An embodiment in which the tracking method disclosed in No. 65560 is applied to a digital VTR will be described.

FIG. 1 is a diagram showing the configuration of a reproduction system of a digital VTR as an embodiment of the present invention, and FIG.
3 is a diagram showing a recording format on a magnetic tape to be reproduced by the digital VTR of FIG. 1, and FIG. 4 is an enlarged view of the main part of FIG. 3.

In Fig. 3, 1 indicates the magnetic tape, A indicates the scanning direction of the rotary head, B indicates the feeding direction of the magnetic tape, tlNt6 indicates the track, and pilot signals are recorded in the hatched area with vertical lines. It is a part. Figure 4 is an enlarged view of the vicinity of the pilot signal recording area;
The parts marked n't have frequencies f, , f2, respectively.
pilot signals are recorded. The areas before and after this pilot signal recording area are IBG (IBG: Int
er Block Gap). In this area IBG, a signal that does not include the fl+f2 frequency component is recorded or erased. 3 is a recording area for video signals.

In Figure 2, 2a, 2b, 2c, 2d, 2e
, 2f are rotary recording/reproducing heads, which trace the tape L wound around the drum D over an angular range of 180° or more. For heads 2a, 2b, and 2c, head 2
d.

The rotational phases of the heads 2e and 2f are 180° different from each other, and the heads 2a, 2b, and 2c are arranged close to each other, and the head 2d is similar to the head 2d.

2e and 2f are also arranged close to each other. Also, head 2
a.

2c and 2e have the same azimuth angle, similarly head 2b
.

2d and 2f also have the same azimuth angle, and the head 2a
.

Azimuth angle of 2c, 2e and heads 2b, 2d,
The azimuth angle of 2f is different.

When drum D rotates 172 times, the recording/reproducing head is at 2a.

The signals are switched between 2b, 2c and 2d, 2e, 2f, and the three rotating heads are always in contact with the tape 1, thereby recording and reproducing three systems of signals. For example, tracks tl, t2. t3. t4. t5
．． t6 are heads 2a, 2b, 2c, respectively.
2d, 2e, and 2f, respectively.

Regarding the recording operation, each of the heads 2a to 2f records the aforementioned pilot signal when tracing the area fl+f2 of the track tlNt6, and records a video signal when tracing the area {circle around (2)}.

Next, the reproduction system will be explained. In FIG. 1, 1 is a magnetic tape, 2 is a playback head, 3 is a playback amplifier, and the playback signal obtained from the magnetic tape 1 is transmitted through a signal processing circuit 4, a dropout detector 5. The signals are respectively input to a band pass filter (BPF) 6 and a BPF. The outputs of BPF6 and BPF8 are input to a detector 7.9, respectively, and the outputs are selected by changeover switches 10a and 10b and input to a sampling hold (S/H) circuit 12.13 or a comparator (COMP) 14. be done. S/H circuit 12
．． 13 is operated by the output of the comparator I4, and the output signals are respectively input to the subtracter 15. The output of the subtracter 15 is further input to the S/H circuit 16. The S/H 16 is operated by the output of the timing generator 21, and the output is input to the average value calculator 19. The average value calculator 19 is controlled by the signal from the dropout detector 5, and its output is input to the capstan drive circuit 20.

200 and 300 are circuits with the same configuration as circuit 10.0 surrounded by a solid line, and their respective outputs are S as in circuit 100.
/H circuit 17/18. It is input to the average value calculator 19. Two heads are selectively used as the heads 2 in each of the circuits 100, 200, and 300. For example, circuit 100 is connected to heads 2a and 2d, circuit 200 is connected to heads 2b and 2e, and circuit 300 is connected to head 2c.

2f is selectively used. However, in the figure, 2a and 2
The head changeover switches for d, 2b and 2e, 2c and 2f are omitted.

The operation will be explained in detail below. From the magnetic tape l to the recording/reproducing head 2. Among the signals reproduced by the reproduction amplifier 3, the signals related to the recorded data are processed by the signal processing circuit 4 and output as reproduction signals from the terminal 25a. In addition, a dropout detector 5 detects the presence or absence of a dropout in the reproduction signal of the head 2. On the other hand, BPF6
．． The BPF 8 detects frequency components of fl+f2, and the detector 7.9 detects the signal level of f'l+f2. The switch 10a controls the signal level of the pilot signal reproduced from both adjacent tracks of the track to be mainly traced by the head 2, and the switch 10b controls the signal level of the pilot signal reproduced from the track to be mainly traced by the head 2. The selection is made each time the drum D rotates once. switch 10a
The output of the switch 10b is input to the S/H circuits 16 and 17, and the output of the switch 10b is input to the comparator 14.

The comparator 14 detects the rise and fall of the signal level output from the switch 10b in order to generate pulses for sampling the levels of the pilot signals of the two adjacent tracks. The two pulses output by the comparator 14 cause the S/H circuit 12. 13 works. Through this operation, the amount of crosstalk of pilot signals from adjacent tracks is reduced by each S/H circuit 12.1.
This corresponds to the output level of 3. The subtracter 15 is connected to this S/H circuit 12. A tracking error of the head 2 is detected by determining the difference between the output levels of the head 13, and a tracking error signal is output. The above operation is performed for each circuit 100.
, 200, and 300, respectively, and the S/H circuit 1
6. 17. There are 18 inputs. In the timing generator 21, each circuit 100. 200. 300 forms the tracking error signal from the pilot signal, that is, the S/S of each circuit Zoo, 200, 300.
Sampling pulses are generated at a timing after all of the H circuits 13 have operated, and are captured and held inside the S/H circuits 16, 17, and 18, respectively.

In normal times when there is no dropout, the tracking error signals from the three heads obtained by the S/H circuits 16, 17, and 18 are summed by the average value calculator 19, and
The signals are averaged and input to the capstan drive circuit 20 for tracking control. Here, the tracking error signals obtained from the three heads were averaged because the three heads are placed close to each other as shown in Figure 2, and there is little temporal difference in the tracking error signals. Therefore, the purpose is to take the average value in consideration of the stability of capstan control and improve the stability of tracking.

Next, a case will be described in which dropout of the reproduced signal is detected in each of the circuits 100, 200, and 300. Now, if a dropout occurs in the playback signal of head 2b, the fourth
Either no signal was recorded on the track t2 in the figure, or the head 2b was unable to reproduce the signal. In the former case, tracks tl, t2. The tracking error signal obtained from the reproduction signal of any head reproducing track t3 has an abnormal value, and in the latter case, only the tracking error signal obtained from the reproduction signal of the head reproducing track t2 has an abnormal value. It is thought that this is the case. Therefore, if a dropout occurs in the playback signal of the head that should play back a certain track during the period in which the pilot signal is played back, the playback signal of the head that should play back that head and both adjacent tracks of the track traced by the head There is a possibility that all the tracking error signals obtained from the system have abnormal values. Therefore, it is desirable that all tracking error signals obtained from reproduction signals of these heads not be used for tracking control.

By the way, according to the above logic, if a dropout occurs in the reproduced signal of the head 2d and the pilot signal cannot be reproduced, there is a possibility that the tracking error signal obtained from the reproduced signal of the head 2c also has an abnormal value. Yes, but
Since the head 2d traces the tape l with a delay of a period close to the half-rotation period of the drum D relative to the head 2c, the tracking error signal obtained from the reproduction signal of the head 2c is configured not to be used for tracking control. must output the tracking control signal at a timing that is delayed by at least a half-rotation period of the drum D. This increases (degrades) the responsiveness of tracking control.
The circuit configuration also becomes complicated. Similarly, if the pilot signal cannot be reproduced from the reproduction signal of the head 2c, the tracking error signal obtained from the reproduction signal of the head 2d may also have an abnormal value. In this case, although the responsiveness of tracking control is not degraded, the circuit configuration becomes complicated.

Therefore, in the digital VTR of this embodiment, the circuit 100
If dropout detector 5 in circuit 100 . detects a dropout during the period when the pilot signal is to be regenerated, circuit 100 . If the tracking control signal is formed without using the tracking error signal outputted by the circuit 200, and the dropout detector 5 in the circuit 300 detects a dropout during the period in which the pilot signal is to be regenerated, A tracking control signal is formed without using the tracking error signal to be output. Furthermore, the circuit 10
Two or more of 0°200, 300, or circuit 200
If the dropout detector 5 in the controller detects a dropout during the period in which the pilot signal is to be reproduced, the tracking error signals output from these three circuits are not used to form the tracking control signal.

FIG. 5 is a diagram showing an example of the configuration of the average value calculation circuit of FIG.
3 are the circuits 100. 200. This is a terminal to which the detection signal of the dropout detector 5 in 300 is input manually. The output of the dropout detector 5 becomes high level (Hi) when a dropout occurs in the reproduction signal of each system in all periods. On the other hand, a pulse signal is inputted to the terminal 54 from the timing generator 21 and becomes Hi while the head 2 of each system traces the recording area of the pilot signal, and if dropout occurs within this period, the AND gate 55. 56.57 becomes Hi. Mono multi (MM) 58.59.60 is AND gate 55,
It is triggered at the rising edge of the output of 56.57, and is kept Hi for a period corresponding to the pulse width of the pulse signal input to the terminal 54.

The terminal 61 is connected to the timing generator 21 to the S/H circuit 16 . A pulse for operating the terminals 17' and 18 is input, and the timing is set immediately after the pulse signal input to the terminal 54 changes to low level (Lo). As a result, when the inverted outputs of the latch circuits 62, 63, and 64 are Lo, the S/H circuit 16. 17. 18
This indicates that a dropout has occurred in the reproduced signal for forming the tracking error signal output by.

S/H circuits 16, 17. '18 outputs a tracking error signal from terminal 65. 66, 67, and each tracking error signal is supplied to an attenuator 68.69°7.
The level is reduced to 1/3 by 0, added by the post-adder 71, and the average value of each tracking error signal is taken.

Now, no pilot signal is lost due to dropout in any of the circuits 100, 200, and 300 (if the pilot signal is regenerated, the output of the AND gate 72 becomes Hi and the gate circuit 73 is closed, so the output of the adder 71 The average value is supplied as a tracking control signal to the capstan drive circuit 20 via the N side of the switch 74 and the terminal 75.

Next, if a dropout occurs only in the reproduction signal of the head of the circuit 100, the output of the AND gate 76 goes high.
Since the gate 77 is closed, the tracking error signal output from the circuit 300 is supplied to the capstan drive circuit 20 as a tracking control signal.

Furthermore, if a dropout occurs only in the reproduced signal of the head of the circuit 300, the output of the AND gate 78 goes high.
Since the gate 79 is closed, the tracking error signal output from the circuit 100 is supplied to the capstan drive circuit 20 as a tracking control signal.

In other cases, none of the tracking error signals output by the circuits 100, 200, and 300 can be used. The S/H circuit 80 holds the tracking control signal output immediately before. On the other hand, since the output of the NOAH game) 81 becomes Hi, this S/H circuit 80
The output is supplied to the capstan control circuit 20 via the S terminal of the switch 74 as a tracking control signal.

Although the digital VTR of the embodiment described above has a simple circuit configuration, it is possible to minimize the chances of tracking control being performed due to an invalid tracking error signal, and to minimize the possibility that a dropout occurs in the reproduced signal. However, stable tracking control can be performed.

In the above embodiment, the dropout detector 5 is provided after the amplifier 5, but it can also be provided after the switch 10b.

Further, although the above embodiment has been explained using a digital VTR as an example, information signals are reproduced by a plurality of heads tracing a plurality of adjacent tracks, and reproduction pilot signals from both adjacent tracks of the main reproduction track of each head are reproduced. As long as the device forms a tracking control signal based on a level difference, the present invention can be applied to any information signal reproduced from any recording medium, and similar effects can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, stable tracking control can be realized even when recording failures, reproduction failures, etc. occur in a device that reproduces information signals using a plurality of rotating heads that trace adjacent tracks. Ta.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a playback system of a digital VTR as an embodiment of the present invention, FIG. 2 is a diagram showing the head configuration of the digital VTR shown in FIG. 1, and FIGS. 3 and 4 are magnetic tape FIG. 5 is a diagram showing a specific example of the average value calculation circuit in FIG. 1. FIG. 6 is a diagram showing an example of the recording pattern on tape using the area division pilot method. . l is magnetic tape, 2.2a, 2b, 2c, 2d,
2e. 2f is a rotary head, 5 is a dropout detector, 6, 8 is a BPF, 7.9 is a detection circuit, 12゜13 is a sample hold circuit, 14 is a comparator, 15 is a subtracter, 1
6. 17. 18 is a sample hold circuit, 19 is an average calculation circuit, 20 is a capstan drive circuit, 72.76
．． 78 is an AND gate, 73.77, 79 is a gate circuit, 74 is a switch, 80 is a sample hold circuit, 81
is Noah Gate. □8

Claims (1)

[Claims] A device for reproducing information signals from a plurality of parallel tracks each recording a pilot signal for tracking control along with an information signal, the apparatus comprising: a reproducing means having a plurality of heads for tracing adjacent tracks; means for generating a tracking control signal based on a level difference between reproduced pilot signals from both adjacent tracks of a main reproduced track of each head; dropout detection means for detecting a dropout of a reproduced signal of each head; a head in which dropout has occurred in the playback signal and a head that traces a track adjacent to the track traced by the head during a period in which dropout has occurred in at least one of the plurality of heads based on the detection output of the detection means; An information signal reproducing device comprising means for prohibiting a pilot signal reproduced by said tracking control signal generating means from being used.