JPH06119686A - Tracking controller for signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To cope with expansion/contraction of a tape, the variance of tape tension, and the change of a tape running system. CONSTITUTION:A saw tooth wave subjected to frequency modulation or phase modulation is recorded in a prescribed position of an oblique track on the tape. The saw tooth wave reproduced by a head 10 is sampled in a sampling and holding circuit 14 by the sampling signal generated by a sampling timing signal generating circuit 13, and the sample value level is inputted to a comparing circuit 16. It is compared with the center value level of the saw tooth wave as the reference signal generated by a reference level generating circuit 15 to detect the extent and the direction of deviation of the head from the recording track. The difference output of the comparing circuit 16 is added to the output of a speed control circuit 18 by an adder 17, and the result is sent to a capstan motor driving circuit 19 to control the rotation speed of a capstan motor 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking control device for controlling tracking of a rotary magnetic head with respect to an oblique track of a recording medium of a signal recording / reproducing device.

[0002]

2. Description of the Related Art In a helical scan type signal recording / reproducing apparatus, a CTL signal is recorded on a track in a longitudinal direction of a magnetic tape, and phase servo is performed at the time of reproduction by a time difference between a reference signal and a reproduction CTL signal. In this method, the physical distance between the oblique track to be reproduced and the CTL signal recorded in the longitudinal direction changes due to expansion and contraction of the magnetic tape over time, variations in tape tension during recording and reproduction, and changes in the tape running system. Resulting in. Therefore, even if the time difference between the reference signal and the reproduced CTL signal is detected at the time of reproduction and the time difference is controlled to be constant, the video head cannot accurately scan the diagonal track.

Further, in a control system in which a pilot signal is recorded on an oblique track and a leak signal from an adjacent track is minimized at the time of reproduction, due to variations in recording / reproduction efficiency of heads used at the time of recording / reproduction, etc. There is a problem in that accurate scanning cannot be performed because the minimum point of the leak signal and the optimum point of oblique track scanning deviate.

[0004]

SUMMARY OF THE INVENTION In consideration of the above problems, the present invention provides a video head which is capable of expanding and contracting due to aging of the magnetic tape, variations in tape tension during recording and reproduction, and changes in the tape running system. It is another object of the present invention to provide a tracking control device for a signal recording / reproducing device capable of accurately scanning an oblique track.

[0005]

According to the present invention, there is provided a tracking control device for controlling tracking of a rotary magnetic head with respect to an oblique track of a magnetic tape, wherein a saw tooth recorded by frequency modulation or phase modulation at a predetermined position of the oblique track. Reproducing means for reproducing a circular wave (slope wave), sampling means for sampling the sawtooth wave reproduced by the reproducing means with a pulse signal indicating the rotation phase of the rotary magnetic head, and sampling by the sampling means It is characterized by further comprising: comparing means for comparing the sampled value with a predetermined level; and controlling means for controlling the transfer of the recording medium based on the comparison result of the comparing means.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows a tape format in which a sawtooth wave signal (hereinafter referred to as a slope signal) used for tracking control of a tracking control device of the present invention is recorded on an oblique track of a magnetic tape. As shown in FIG. 3, a slope signal, which will be described below, is recorded on a track recorded on the tape 22 in an oblique direction. Further, in FIG. 3, 3A, 3B, and 3C are operation loci of the rotary magnetic head for reproducing the recorded signal, and a signal synchronized with the rotation of the rotary drum (hereinafter, referred to as PG signal). Illustrated.

Further, FIG. 5 shows operation loci 3A, 3B and 3C of the rotary magnetic head showing the principle of the present invention, a slope signal reproduced in each case, and a PG signal mounted on the rotary drum. PG signal from the generator and the PG
The relationship between the sampling timing signal for sampling the slope signal and the sampling level (Sa, Sb, Sc) when the signal is delayed by a certain time (T) is shown in a waveform diagram.

Assuming that the ideal operation locus of the rotary magnetic head is 3C in FIG. 3, the sampling level becomes Sc (median level of the slope signal) as shown in FIG. 5C. Then, in the case of each of the operation loci 3A and 3B, as shown in FIGS. 5A and 5B, the slope signal is sampled after a predetermined time T from the PG signal,
By measuring the levels Sa and Sb, it is possible to detect the deviation amount and the direction of the operation track with respect to the recording track.

Although the PG signal is used as the signal synchronized with the rotation of the rotary magnetic drum in the description,
The signal is not limited as long as it is a signal synchronized with the rotation of the drum to which the rotary head is attached and the time relationship with the reproduced waveform of the timing signal can be measured. In addition, the slope signal recorded on the helical track can also be reproduced by the rotary head, and the signal synchronized with the rotation of the drum to which the rotary head is mounted enables sampling during playback, and the sampling level can be measured. If so, there is no limitation on the frequency or waveform.

FIG. 4 is a plan view of a main part of a general recording / reproducing apparatus of the helical scan type. In FIG. 4, the rotary heads 4A to 4D of channels A to D are arranged on the rotary drum 4 as shown. 1 and 2 are tape guides for keeping the tape running constant, 3 is a magnetic tape, 4 is a cylindrical rotating drum, and each head 4A to
4D is fixed on the rotary drum 4. The rotation speed of the rotating drum and the tape running are controlled so that the recording track as shown in FIG. 3 is formed on the magnetic tape 3 wound around the rotating drum 4.

FIG. 1 shows a block diagram of a recording system of the present invention for recording the slope waveform for tracking control. In FIG. 1, 5 is a recording slope signal generation circuit, 6 is a slope signal recording timing control circuit for controlling the recording timing of the slope signal, and 7A to 7A.
D is switch means for switching the recording signal and the slope signal based on the control signal output of the slope signal recording timing control circuit 6, and 8A to 8D are Ach to Dch.
A recording circuit including a circuit for modulating and amplifying a recording signal and supplying a recording current, 9A to 9D are from a fixed portion to the rotary drum 4
This is a rotary transformer for transmitting a recording signal to each of the above heads 4A to 4D.

With the recording system thus constructed, the recording timing control circuit 6 controls the switch means 7A to 7D so that the slope signal is recorded at a fixed position on each track by each of the heads 4A to 4D, and the recording circuit 8A. Up to 8D, frequency modulation or phase modulation is performed and a slope signal is supplied to each head and recorded on a magnetic tape together with a recording signal.

Next, FIG. 2 shows a reproducing system of the present invention for reproducing the tape recorded in the recording system. Figure 2
In the figure, 10 is a reproducing video head, 11 is a reproducing circuit including an amplifier circuit for demodulating and amplifying a reproduced signal, 1
2 is a signal processing circuit for a video signal, 13 is a sample timing signal generating circuit which receives a PG signal which is a reference signal and generates a sample timing signal, 14 is a sample and hold circuit, 15 is a reference level generating circuit, and 16 is a comparison Reference numeral 17 is an adder, 18 is a speed control circuit, 19 is a motor drive circuit, 20 is an FG signal waveform shaping circuit, 21 is an FG signal amplification circuit, 22 is a magnetic tape on which the slope wave is recorded together with a recording signal, 23 is a capstan motor,
24 is a pinch roller.

The operation of the reproducing system of the present invention thus constructed will be described. In the sample and hold circuit 14, the slope signal reproduced by the video head 10 is
Sampling is performed by the sampling signal from the sample timing signal generation circuit 13, the sample value level of the slope signal is input to the comparison circuit 16, and the reference level generation circuit 15
It is compared with the median level of the slope signal which is the reference signal generated in. Then, a speed control circuit 1 for controlling the tape feed speed by the adder 17 based on the difference output of the comparison circuit 16
It is added to the output of 8 and sent to the capstan motor drive circuit 19 to control the rotation speed of the capstan motor 23.

Here, the sampling output level of the reproduced slope signal in the sample and hold circuit 14 becomes a known value when the video head 10 scans the recording track correctly. That is, the output level of the reference level generation circuit 15 is set so that the level of the median value of the slope signal becomes a known level when the video head 10 correctly scans the recording track, and the comparison circuit 16 sets the level. By making a comparison, it becomes possible to detect the deviation amount of the scanning locus of the video head 10 with respect to the recording track and the direction thereof.

Further, by adding the detection result to the speed control system of the capstan motor 23, the deviation of the scanning track of the reproducing video head 10 from the recording track can be corrected. That is, it is possible to detect a relative deviation (off-track amount) in the vertical direction with respect to the scanning locus of the rotary head and correct the deviation.

[0017]

By recording the slope signal together with the recording signal at the time of tape recording, even if the tape expands or contracts due to a change with time, the tape tension varies during recording and reproduction, or the tape running system changes, The track information necessary for the head to scan the helical track can be detected. Further, since the influence of the variation in the reproduction signal level between the channels can be ignored, the optimum point of the helical track scanning does not shift due to the variation in the recording / reproducing efficiency of the head used at the time of recording / reproducing.

Further, since it is not necessary to record the CTL signal on the track in the longitudinal direction, the fixed head is not required and the mechanism can be simplified. At the same time, the recording circuit dedicated to the fixed head is not required, and the circuit can be simplified. Becomes

[Brief description of drawings]

FIG. 1 is a block diagram of a recording system of the present invention.

FIG. 2 is a block diagram of a reproduction system of the present invention.

FIG. 3 is a diagram showing a head traveling locus.

FIG. 4 is a plan view of a main part of a general rotary head.

FIG. 5 is a waveform diagram illustrating the operation of the present invention.

[Explanation of symbols]

 4A to 4D recording head 5 slope signal generation circuit 6 recording timing control circuit 7A to 7D switch 13 sample timing generation circuit 14 sample and hold circuit 15 reference level generation circuit 16 comparison circuit

Claims (4)

[Claims] 1. A tracking control device for controlling tracking of a rotary magnetic head with respect to an oblique track of a recording medium, a reproducing means for reproducing a tilt wave recorded at a predetermined position of the oblique track, and a reproducing means for reproducing the inclined wave. Sampling means for sampling the inclined wave with a pulse signal indicating the rotation phase of the rotary magnetic head, comparing means for comparing a sample value sampled by the sampling means with a predetermined level, and comparison of the comparing means And a control means for controlling the phase of the recording medium based on the result. 2. The inclined wave is frequency-modulated and recorded on the oblique track.
A tracking control device for the signal recording / reproducing device described. 3. The tracking control device for a signal recording / reproducing apparatus according to claim 1, wherein the inclined wave is phase-modulated and recorded on the oblique track. 4. The tracking control device for a signal recording / reproducing apparatus according to claim 1, wherein the inclined wave is a sawtooth wave.