JPH0214454A - Tracking control circuit - Google Patents

Abstract

PURPOSE:To realize a correct tracking by detecting a pilot signal recorded onto the track of an alignment purpose from the output of a head to trace both adjoining tracks and controlling the tracking with the comparison result of the pilot signal levels. CONSTITUTION:At the time of reproducing, a head HB reproduce-detects the crosstalk of the pilot signal of a D track, the components of a pilot signal f1 are fetched by a band-pass filter 27, and a detection is executed by a detecting circuit 30. When heads HA and HB complete the traces of the magnetic tape, next, heads HC and HD start the traces. Here, by comparing the level of the crosstalk from the D track to an E track with the level of the crosstalk from the D track to a C track by means of a comparator 38, tracking error information can be obtained. Thus, only at a reproducing device side, the correct tracking can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tracking control circuit that controls tracking in a digital recording system that records digital signals on a tape-shaped recording medium using a plurality of rotary heads.

[Conventional technology]

In recent digital signal recording, digital VT
As typified by R, the amount of information per unit time has become enormous. Therefore, digital recording requires higher density as well as wider bandwidth, and methods for achieving this include:
A so-called multi-track recording method has been proposed in which a plurality of tracks are simultaneously formed using a plurality of rotating heads.

On the other hand, from the viewpoint of high-density recording, it is desired to reduce the track pitch as much as possible.

In response to the decrease in track pitch, it has become an important issue to be able to accurately trace the recording track with the playback head during playback, and in digital magnetic recording technology, area-divided ATF (Automatic Track F
(inding) has been considered and put into practical use.

The area-divided ATF method has more accurate tracking than the tracking method that uses CTL (control) signals, and the ATF method separates from the digital information area.
By providing an area, there is an advantage that the band necessary for recording digital information can be secured.

For example, as shown in FIG. 3, there are two rotary heads H, H1 on one side and two rotary heads H1 on the other side facing each other by 180'' on a rotary drum 10. rotating heads HC, HD
are arranged, and tracks are formed diagonally on the magnetic tape 12. At the beginning and end of the track, an ATF area is provided in addition to an information area for recording information. FIG. 6 shows the ATF area in the trunk pattern on the magnetic tape 14. As shown in FIG. During playback, two heads HA, H1; HC, H! For example, when the head HA traces the B trunk, it detects the crosstalk of the pilot signal recorded on the C track at point ■, and traces it to the A track at point ■. Crosstalk in recorded pilot signals can be detected. If the frequency of the pilot signal is kept low enough, azimuth loss will hardly be a problem. Tracking error information can be obtained by extracting crosstalk from both adjacent tracks using a band pass filter and comparing the magnitudes of the values.

For the track pattern in FIG. 6, the head Ha,
The tracking error information obtained from H+t is averaged, and the capstan motor is controlled using the average value to control tracking.

[Problem to be solved by the invention]

However, in the above conventional example, the head that records the pilot signal on the A track (head Ht+) is different from the head that records the pilot signal on the C track (head Hyo), so there is a difference in performance between the recording head and the recording amplifier. Therefore, the strength of the magnetization pattern of the pilot signal on the magnetic tape differs between the A track and the C track, resulting in an offset in tracking during reproduction. To prevent this, it is necessary to adjust the head recording current of the recording system or the gain of the playback thread, but when considering compatible playback, it is necessary to set the magnetization pattern strength on the magnetic tape to a specified value. Correcting offset is very difficult.

So-called DAT (Digital Audio T)
In a two-head type digital magnetic recording device such as APE, the recording heads forming both adjacent tracks are the same, so the magnetization pattern intensities are equal. Therefore, the above problems can be said to be unique to the multi-track recording method.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tracking control circuit that can extremely easily correct tracking offset during playback in such a multi-track recording digital recording/playback system.

[Means to solve the problem]

The tracking control circuit according to the present invention records digital information simultaneously on a tape-shaped recording medium using a plurality of rotary heads, and records a pilot signal for tracking in an area different from the recording area of the digital information. - In a playback system, a tracking control circuit that aligns a rotary head with a recording track, the first and second tracking control circuits detecting a pilot signal recorded on a track to be aligned from the output of a head that traces both adjacent tracks. The present invention is characterized in that it comprises a pilot detection means, and a comparison means for comparing pilot signal levels detected by the first and second pilot detection means, and tracking is controlled based on the comparison result of the comparison means.

[Effect]

By comparing the outputs of the first and second pilot detection means with the comparison means, it is possible to quantitatively know the amount of offset from the alignment target track. Therefore, accurate tracking can be achieved using the comparison means of the comparison means.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a digital VTR will be described below with reference to the drawings.

The arrangement of the rotating head on the rotating drum is as described above (as shown in Figure 3). Figure 1 is a block diagram of the configuration of the pilot signal recording/reproducing circuit system in one embodiment of the present invention. Figure 2 shows the trunk pattern near the ATF area according to Figure 1. This ATF area is
Located at the beginning of the track. In FIG. 1, 20 is an oscillator for the pilot signal f1, 21 is a timing pulse generation circuit, 22 is a magnetic head, 24 is a gate circuit for recording the pilot signal fl at a predetermined position at the beginning of the track, and each It is opened and closed by a timing pulse generated by a timing pulse generation circuit 21 based on the rotational phase of the head.

During recording, the heads HA and Hc send pilot signals f,
is recorded in the ATF area 26 (FIG. 2).

At this time, a high frequency signal from the high frequency signal generation circuit 23 is applied to the heads H1+, )(Il+ via the R terminals of the switches SWI and SW2, and is used as a substitute for the erase signal.

pilot signal f, to two helads HA, H8 on one side;
By recording only with one head Ha, Hc of Hc, H++, AT
The F area 26 is provided on every other track as shown in FIG. 2, but in the case of the head configuration shown in FIG. 3, the relative positions of the B track and C track, and the C track and E track, are Since it is determined only by accuracy, the required tracking accuracy can be obtained even with a track pattern as shown in FIG. 2 (especially the ATF area 26).

Next, the reproduction operation will be explained. 27.28 is a band pass filter (BPF) that extracts the pilot signal f.
, 30.34 is a detection circuit, and 32.36 is a detection circuit 30.
A sample hold (S
/H) circuit, 38° 40 is a comparison circuit. First, the head H8 reproduces and detects the crosstalk of the pilot signal of the C track at point 2, and reproduces and detects the crosstalk of the pilot signal of the B track at point 2. BPF2
7, the component of the pilot signal f, (i.e., crosstalk)
is extracted and detected by the detection circuit 30. Point■
The detection output at is held in the S/H circuit 32.

When the heads HA, H, finish tracing the magnetic tape, the heads Hc, H, start tracing next. Focusing on the head HD tracing the E track, the head H9 first reproduces and detects the crosstalk of the pilot signal of the F track at point 2, and reproduces and detects the crosstalk of the pilot signal of the C track at point 2. B.P.
A component (ie, crosstalk) of the pilot signal f is extracted at F28 and detected by the detection circuit 34. Here, by comparing the level of crosstalk from the C track to the E track with the level of crosstalk from the C track to the C track (held by the S/H circuit 32), the tracking error is detected. You can get information. At this time, the switch 42 is connected to the A side, and the S
By keeping the /H circuit 44 in an operating state, an ATF signal can be obtained from the S/H circuit 44.

The crosstalk signal from the head H at point (3) is held in the S/H circuit 36, and then
, H, are compared by the comparison circuit 40 with the crosstalk from the F trunk to the C track (output of the head H6) when tracing the magnetic tape.

In this way, since the tracking error information is obtained alternately in the comparison circuits 38 and 40, the switch 4
2 and activates the S/H circuit 44 at the timing when tracking error information is obtained.
F signal is obtained.

The tracking error information is a comparison between the playback output of head H3 and the playback output of Herad Hi, so of course head H! , H, and variations in the gain of the reproduction amplifier may cause an offset in dragging, but these are all problems with the reproduction system and can be dealt with by adjusting each reproduction device individually.

Using the ATF signal obtained in this way, the capstan
By controlling the motor, it is possible to prevent variations in magnetization pattern strength of pilot signals on the magnetic tape from affecting tracking.

This means achieving good tracking performance during compatible playback.

The present invention detects a pilot signal recorded on a track with a magnetic head that traces both adjacent tracks during reproduction, and obtains tracking error information by comparing the detected signals. This method can be applied to any multi-track recording type digital magnetic recording device using this method, regardless of the number of heads, the position of the ATF area, or the track pattern of the pilot signal.

Figure 4 shows 3 channels on each side, 6 channels in total (Head Hai Hm, He; H+w+ Ht, H
FIG. 5 shows the ATF area arrangement of the track pattern when applied to a digital magnetic recording device having the structure of F), and FIG. 5 shows the head structure thereof. In this example, two types of pilot frequency losses, fz, are used. Even in this recording method, good tracking can be obtained even during compatible playback by forming tracking error information from crosstalk signals to both adjacent tracks sandwiching the track.

〔Effect of the invention〕

As can be easily understood from the above explanation, according to the present invention, accurate tracking can be achieved only on the playback device side.
Therefore, good information reproduction can be performed even during compatible reproduction.

[Brief explanation of the drawing]

Figure 1 is a block diagram of an embodiment of the invention, Figure 2 is a block diagram of an embodiment of the invention.
A track pattern diagram near the TF area, FIG. 3 is a head configuration diagram, and FIG. 4 shows the ATF area arrangement of the track pattern when applied to a digital magnetic recording device with 3 channels on one side and 6 channels in total. FIG. 5 shows the head configuration, and FIG. 6 shows the track pattern in the conventional example. 20... Oscillator 22... Magnetic head 24... Gate times 1m26.28... Band pass filter 3
0.34--Detection circuit 32.36--Sample/hold circuit 38.40--Comparison circuit box diagram

Claims (1)

[Claims] In a digital recording/playback system that simultaneously records digital information on a tape-shaped recording medium using a plurality of rotating heads and records a pilot signal for tracking in an area separate from the recording area of the digital information, the rotating head is used for recording. A tracking control circuit for aligning tracks, comprising first and second pilot detecting means for detecting a pilot signal recorded on a track to be aligned from the output of a head tracing both adjacent tracks; and comparing means for comparing the pilot signal levels detected by the second pilot detecting means, and controlling tracking based on the comparison result of the comparing means.