JPS63298743A - Device for tracking magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To always attain accurate tracking control by using the fluctuation of a crosstalk component included in a low frequency chroma signal for the tracking control. CONSTITUTION:The tracking error is detected by detecting the fluctuation of the crosstalk component 23 appearing around a burst signal 20. Then a detection signal of a burst signal detection circuit included in an ACC circuit 13 is utilized. The detection signal is given to a control circuit 19, which controls a tracking servo loop to minimize the detection signal from the ACC circuit 13. Thus, even when the relative position between the head and the recording track is deviated under any relation, the tracking error is detected always accurately to attain optimum tracking control at all times.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tracking device for a magnetic recording/reproducing device, and more particularly to a device for controlling tracking of a magnetic recording/reproducing device such as a VTR.

[Prior Art] FIG. 3 shows recording tracks formed on a videotape. As shown in the figure, recording tracks 2 and 3 are alternately formed on a videotape 1. These recording tracks 2.3 are alternately formed by a pair of magnetic heads provided on the rotating drum of the VTR. That is, the fourth
As shown in the figure, a magnetic head 5a having head gaps 6.7 having mutually different azimuth angles is disposed on the rotating drum.

5b are provided at positions 180° apart, a recording track 2 is formed by the magnetic helad 5a, and a recording track 3 is formed by the magnetic helad 5b. During playback, when each magnetic head traces the video tape 1, signals are played back from recording tracks having the same azimuth angle with almost no loss, but signals are reproduced from recording tracks having different azimuth angles with a large loss. (This is called azimuth loss). This azimuth loss reduces crosstalk from adjacent tracks.

By the way, by detecting the control signal 4 recorded on the video tape 1 and adjusting the relative position between the magnetic head and the recording track as shown in FIG. 5 based on this control signal, signals of the same azimuth can be can be played to the maximum. This is called tracking control.

In conventional tracking control, as shown in Fig. 6, the playback output of the magnetic head 5 is amplified by a head amplifier 8, then integrated by an integrating circuit 9, and the output of this integrating circuit 9 is controlled so as to always have a maximum value. It was controlled by circuit 10. That is, as shown in Fig. 7, the level of the reproduced signal from the magnetic head reaches its maximum when the relative positional relationship between the magnetic head and the recording is in the optimum state as shown in Fig. 7(a). The control circuit 10 controls the capstan motor via a servo circuit so that the reproduction output is always maximized.

[Problems to be Solved by the Invention] In the conventional tracking control system as described in Section 2, the relative position between the magnetic head and the recording track is as shown in FIG.
) If the magnetic head straddles the recording track as shown in Figure 7(c), it can be detected because the reproduced signal decreases, but if the magnetic head straddles the recording track as shown in Figure 7(c), the level of the reproduced signal decreases to As shown in (a), there was no difference from the case where the position was at the optimum position, and effective control could not be performed.

This invention was made to solve the above-mentioned problems.No matter how the relative position between the head and the recording track deviates, tracking errors can always be detected accurately, and accurate tracking can be achieved. An object of the present invention is to provide a tracking device for a magnetic recording/reproducing device that can be controlled.

[Means for Solving the Problems] A tracking device for a magnetic recording and reproducing device according to the present invention uses a crosstalk component for detecting fluctuations in a crosstalk component included in a low frequency chroma signal of a signal reproduced from a magnetic recording medium. The crosstalk detection means includes a talk detection means and a tracking phase control means for controlling the tracking phase so as to minimize the detection output of the crosstalk detection means.

[Operation] This invention focuses on the fact that azimuth loss is small for low-frequency signals, and uses fluctuations in crosstalk components included in low-frequency chroma signals for tracking control to ensure accurate tracking at all times. Tracking control is performed.

[Embodiment] FIG. 1 is a schematic block diagram showing an embodiment of the present invention applied to a VTR. In the figure, the FM reproduction signal from the magnetic head 5 is amplified by a head amplifier 8 and provided to a luminance signal processing circuit 11. The luminance signal processing circuit 11 demodulates the FM reproduction signal into a luminance signal. Further, the output of the head amplifier 8 is given to a low-pass filter 12, and the FM signal is removed from the FM reproduction output. The output of the low-pass filter 12 is an automatic saturation adjustment circuit, or ACC.
(automatic chroma control) circuit 13. This ACC circuit 13 is for making the saturation of the chroma signal constant, and specifically detects the level fluctuation of the burst signal included in the chroma signal and controls it so that it is constant. The output of the ACC circuit 13 is given to a converter 14, and the low frequency chroma signal is converted into an ordinary chroma signal. The output of the converter 14 is passed through a bandpass filter 15 to remove unnecessary frequency components other than the chroma band, and then fed to a comb filter 16 to remove crosstalk components from adjacent tracks. The luminance signal output from the luminance signal processing circuit 11 and the chroma signal output from the comb filter 16 are applied to a mixing circuit 17 and mixed therein. The output of the mixing circuit 17 is amplified by a video amplifier 18 and then output as a composite video signal.

As mentioned above, video heads are configured to have opposite azimuth angles to reduce crosstalk from adjacent tracks, but the magnitude of azimuth loss is determined by the following equation: (i.e. less crosstalk), and the low frequency signal is smaller (i.e. less crosstalk).
In other words, crosstalk becomes large).

This means that the crosstalk component is large in the low frequency chroma signal.

When detecting tracking errors based only on the level of the FM playback output as in the conventional method, it was difficult to distinguish the difference between Figures 7(a) and (c). When the crosstalk component included in the signal is detected and used to detect tracking errors, in the case of Fig. 7(c), crosstalk from both adjacent tracks is picked up and the second
As shown in Figure (b), there are large losstalk components 23 and 24 around the burst signal 20 and chroma signal 21.
appears, so the tracking error in the case of FIG. 7(C) can also be easily detected. In this embodiment, tracking errors are detected by detecting fluctuations in the crosstalk component 23 appearing around the burst signal 20. Specifically, a detection signal from a burst signal detection circuit included in the ACC circuit 13 is used. That is, since the burst signal detection circuit detects not only the original burst signal 20 but also the crosstalk component 23, its detection output varies greatly depending on variations in the crosstalk component 23. The detection signal is given to the control circuit 19. This control circuit 19 includes an integrating circuit, a DC amplifier, etc., and detects fluctuations in the DC level of the detection signal. The output of the control circuit 19 is given to a servo circuit (not shown),
This servo circuit controls the drive of the capstan motor and controls the tracking phase to an appropriate position.

That is, the control circuit 19 controls the tracking servo loop so that the detection signal from the ACC circuit 13 becomes the smallest.

In the above embodiment, the burst signal detection signal of the ACC circuit 13 is used for tracking error detection, but a circuit for detecting fluctuations in the crosstalk component of the low-frequency chroma signal is separately provided, and the output of this circuit is used to detect the tracking error. Tracking control may also be performed.

[Effects of the Invention] As described above, according to the present invention, tracking errors can always be accurately detected no matter how the relative position between the head and the recording track deviates, and it is possible to detect tracking errors that cannot be controlled using conventional methods. Such deviations in relative positional relationships can also be corrected, allowing optimal tracking control to be performed at all times.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram showing an embodiment of the present invention. FIG. 2 is a waveform diagram for explaining crosstalk components appearing in the low frequency chroma signal. FIG. 3 is a diagram showing the state of recording tracks formed on a videotape. FIG. 4 is a perspective view for explaining the azimuth angle of a pair of magnetic heads provided on a rotating drum. FIG. 5 is a diagram showing the optimum position of the magnetic head with respect to the recording track. FIG. 6 is a block diagram showing a conventional tracking control method. FIG. 7 is a diagram showing the relationship between the tracking phase and the reproduced signal in the conventional tracking control system. In the figure, 1 is a video tape, 2 and 3 are recording tracks, 4 is a control signal, 5 is a magnetic head, 8 is a head amplifier, 11 is a brightness signal processing circuit, 12 is a low-pass filter, 13 is an ACC circuit, and 14 is a converter. , 15
16 is a band pass filter, 16 is a comb filter, 17 is a mixing circuit, 18 is a video amplifier, and 19 is a control circuit.

Claims (3)

[Claims] (1) a crosstalk detection means for detecting fluctuations in crosstalk components included in a low-frequency chroma signal of a signal reproduced from a magnetic recording medium; and a method for minimizing the detection output of the crosstalk detection means; A tracking device for a magnetic recording/reproducing device, comprising a tracking phase control means for controlling a tracking phase. (2) A tracking device for a magnetic recording and reproducing apparatus according to claim 1, wherein the crosstalk detection means includes a burst signal detection means for detecting a variation in a crosstalk component in a burst signal of the low-frequency chroma signal. . (3) The burst signal detection means is included in an automatic saturation adjustment circuit for automatically adjusting the saturation of the chroma signal reproduced from the magnetic recording medium.
A tracking device for a magnetic recording and reproducing device as described in 2.