JPH03127353A - Tracking controller - Google Patents

Abstract

PURPOSE:To perform the tracking control with high precision by using the level difference between signals, which is obtained by regenerating a recorded signal with two heads, to obtain the tracking error. CONSTITUTION:When the recorded signal is regenerated by rotary heads where two heads different in azimuth are used as a pair, two heads A and B which are slightly wider than the pair of heads and have the same azimuth difference are used as a pair 20 to scan tracks. When both heads correctly scan each track, reproduced output levels are approximately equal to each other; but if either of heads is deviated from a track, the reproduced output level of one head is not changed only in the wider part but that of the other head is reduced by the extent of deviation from the track. The level difference between signals from two heads is used as the tracking error, and servo is applied to eliminate the difference, thereby performing the tracking control. Thus, the tracking control with high precision is relatively easily performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tracking control device for a rotary head when signals such as video and audio are reproduced from a recording medium by a rotary head.

[Summary of the invention]

The present invention relates to a tracking control device, and when reproducing a signal recorded by a rotating bed made up of a set of two heads with different azimuths, a similar but different head slightly wider than the set of heads is used. 2 with azimuth
The above track is scanned with two heads at 1 wL. If both heads are scanning each track correctly, the playback output level is almost the same, and if one of the heads deviates from the track, For one head, the playback output level does not change only in the wide part, but for the other head
The playback output level of the two heads decreases by the amount that they are off track. Similarly, if the track shifts to the other side, the head output level will be reversed. Then, the level difference between the signals from these two heads is regarded as a tracking error, and a servo is applied to perform tracking control so that the difference disappears.

[Conventional technology]

Conventionally, in devices that record and playback using a rotating head,
As a method of tracking control so that the rotating head correctly scans the recording track, a low-frequency tracking pilot signal is superimposed on the video signal and recorded on the track, and during playback, the amount of crosstalk of the pilot signal from the adjacent track is detected. A so-called ATF method is known in which tracking servo is performed using
lTechnical Report Vol.31
No. 6 [Dec, 1985] K. Yamada et al. “4-frequency pilot system tracking servo JP, 115-1
24).

[Problem to be solved by the invention]

However, the method using pilot signals of four different frequencies as described above has the disadvantage that the circuit configuration becomes complicated.

Further, the frequency of the pilot signal is about 130 kHz, and when overwritten, the erasure rate of the pilot signal deteriorates and the C/N of the signal deteriorates, so there is an inconvenience that the precision of tracking control deteriorates.

Furthermore, when a pilot signal is superimposed on a signal such as video or audio to be recorded or reproduced, there is a problem in that mutual interference occurs and the S/N of the reproduced signal decreases.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a device which employs a circuit configuration that does not require a pilot signal, and which enables relatively simple and accurate tracking control.

[Means for Solving the Problems] In order to achieve the above object, a tracking control device according to the present invention has a reproducing head that is a set of two heads having different azimuths that are slightly wider than the recording track width. The apparatus is equipped with a rotary head and a control means for treating the level difference between the reproduction signals reproduced by the reproducing and reproducing heads as a tracking error and performing control so that the difference disappears.

[For production]

In the present invention, two heads with different azimuths are combined into one
When reproducing signals recorded by a set of rotating heads, the track is scanned using a set of two heads that are slightly wider than the set of heads and have similar different azimuths. If the heads are scanning each track correctly, the playback output level will be almost the same, and if the head deviates from the track on either side, the playback output level will not change for the wide part of one head. The reproduction output level of the other head decreases by the amount that it deviates from the track. Similarly, if the track shifts to the other side, the head output level will be reversed. Then, the level difference between the signals from these two heads is regarded as a tracking error, and tracking control is performed by applying servo so that the difference disappears.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an overall block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing a recording track on a tape being reproduced, and FIG.
The figure is an explanatory diagram of the operation of this embodiment.

In FIG. 1, 1G(a) and 10(b) are RF circuits, 11(a)! s and 11(b) are RF envelope detection circuits, and 12 is a level comparator for detecting a level difference between the RF envelopes. The operation of the tracking control device of this embodiment configured as described above will be explained below with reference to FIGS. 2 and 3.

First, a set of two heads with different azimuths is used to move the recorded track as shown in FIG. Reproduce.

Note that the maximum width of this reproducing head is 1.5 times the track width T shown in FIG. A, 81 pairs of heads are the third
When tracing as shown in Figure 3(a), the output levels of both heads are almost equal, but if both heads shift to the left as shown in Figure 3(b), the output level of Head A decreases, and the output level of Head B decreases. The output level does not change over a wide range of degrees Celsius. Similarly, when it shifts to the right, the opposite happens. These relationships are shown in Figure 3 (C
) is shown.

Therefore, the output of the level comparator 12 shown in FIG. 1, ie, the level difference between both heads, becomes as shown in FIG. 3(d), and can be used as the tracking error signal E.

As described above, according to this embodiment, the tracking error signal is extracted from the originally recorded signal without using the pilot signal, which simplifies the circuit configuration, and also reduces S/H due to waveform interference. There is no.

Furthermore, the response speed is faster than the control pulse method (CTL method), which records a reference signal in the longitudinal direction of the tape and uses that signal to operate the capstan servo during playback. The response is fast.

(Effects of the Invention) As explained above, according to the present invention, since the tracking error is obtained using the level difference between the originally recorded signal and the signal reproduced by the two heads, highly accurate tracking can be achieved. Control is possible. In addition, there is no need to detect a pilot signal, the circuit configuration is simplified, there is no waveform interference during reproduction, and the practical effects are great.

[Brief explanation of the drawing]

Fig. 1 is an overall block diagram of a tracking control device according to an embodiment of the present invention, Fig. 2 is a diagram showing recording tracks on a tape being reproduced in the embodiment, and Fig. 3 is an explanation of the operation of the embodiment. It is a diagram. tO(a), 10(b)---RF circuit, 11(
a), 11(b) ---Envelope detection circuit, 12
... Level comparator, 20... Playback head.

Claims (1)

[Scope of Claims] 1) A rotary head having a reproduction head consisting of a set of two heads with different azimuths slightly wider than the recording track width, and the level of each reproduction signal reproduced by the reproduction head. A tracking control device characterized by comprising: a control means that treats the difference as a tracking error and performs control so that the difference disappears.