JPH05282743A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To enable a head to accurately scan a helical track in spite of secular charge of a tape, dispersion of tape tension in recording and reproducing or variation of a tape running system or the like. CONSTITUTION:This device is provided with a head H which reproduces a prescribed timing signal (sweep signal TG) recorded in a helical track tr, a self correlation detecting circuit 32 which detects self correlation of the sweep signal TG from the head H, a time interval measuring circuit 17 of a phase control means for sending a tape which controls a phase for sending a tape based on a PG signal which is the reference of a rotary phase of a rotary drum and the self correlation detecting output, a speed control circuit 22, and an adder circuit 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus for recording / reproducing signals on / from a tape-shaped recording medium by a so-called helical scan method.

[0002]

2. Description of the Related Art In a conventional helical scan type VTR, a CTL (control) signal is recorded on a control track in the longitudinal direction, and during reproduction, phase servo is performed by a time difference between the reproduction CTL signal and a reference signal (REF signal). Tracking servo is performed by applying.

[0003]

However, in the conventional method of recording the CTL signal on the track in the longitudinal direction,
Due to changes over time in the tape, variations in tape tension during recording and playback, changes in the tape running system, etc., the physical distance between the tilted track (helical track) to be played back and the CTL signal recorded in the longitudinal direction changes. I will end up. Therefore, the conventional method has a problem that the rotary head cannot accurately scan the helical track even if the time difference between the reference signal and the CTL signal is controlled to be constant during reproduction.

Further, for example, a pilot signal is recorded on a helical track like a so-called 8 mm VTR,
Some so-called ATF tracking control is employed in which tracking is performed by controlling so as to minimize a leak signal from an adjacent track during reproduction. However, in such a control method, the minimum point of the leak signal (just track position obtained from the leak signal) and the optimum point of the helical track scan are set due to variations in the recording / reproducing efficiency of the head used during recording / reproduction. However, there is a problem in that accurate scanning cannot be performed.

Further, for example, a method of recording a simple timing signal on each helical track is conceivable.
This method has a drawback in that if a timing signal is lost due to, for example, dropout, it becomes impossible to detect the phase rigidity.

Therefore, the present invention has been proposed in view of the above-mentioned circumstances, and the head is provided even if there is a change over time of the tape, a variation in tape tension during recording / reproduction, a change in the tape running system, or the like. It is an object of the present invention to provide a recording / reproducing apparatus capable of accurately scanning a helical track.

[0007]

The recording / reproducing apparatus of the present invention was proposed in order to achieve the above-mentioned object, and includes a timing signal reproducing means for reproducing a predetermined timing signal recorded on an inclined track. A tape feed phase control based on an autocorrelation detecting means for detecting an autocorrelation of the timing signal from the timing signal reproducing means, a signal serving as a reference of a rotation phase of a rotary drum, and an output signal of the autocorrelation detecting means. And a tape feed phase control means for performing.

As the predetermined timing signal, a sweep signal of 100 kHz to 500 kHz is used, for example.

The recording system of the recording / reproducing apparatus of the present invention is
Sweep signal generating means for generating a sweep signal as a timing signal based on a signal (for example, a PG signal) serving as a reference of the rotation phase of the rotating drum, and the sweep signal generated by the sweep signal generating means are recorded on the inclined track. And a sweep signal recording means.

That is, according to the present invention, in a helical scan type magnetic tape signal recording / reproducing apparatus, a sweep signal synchronized with drum rotation is recorded as a timing signal on a helical track at the time of recording, and the signal is reproduced at the time of reproducing. From the time difference between the timing of the output signal of the autocorrelator that compares the output and the original signal and the timing of the reference signal that indicates the rotation phase of the drum, the vertical direction relative to the running path of the rotary head and the rotary track of the rotary head. It is characterized in that tracking information is detected to detect such a deviation.

In other words, in the present invention, the sweep signal synchronized with the drum rotation is recorded on the helical track, the reproduction timing is detected from the autocorrelation detection result of the signal during reproduction, and the phase servo of the capstan motor is detected. It is possible to realize a control system that is not easily affected by dropouts, level fluctuations, etc.

[0012]

According to the recording / reproducing apparatus of the present invention, the phase difference can be detected from the autocorrelation detection result of the predetermined timing signal reproduced from the inclined track and the signal serving as the reference of the rotation phase of the rotary drum. Tracking control becomes possible by controlling the tape feed phase using this phase difference.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

The recording / reproducing apparatus of the embodiment of the present invention, as shown in FIG. 1, is a timing signal reproducing means for reproducing, for example, a sweep signal TG as a predetermined timing signal recorded on a helical track tr shown in FIG. 4 described later. Head H (only one of heads A to D shown in FIG. 3, which will be described later, is shown in FIG. 1) and the autocorrelation of the timing signal (sweep signal TG) from the timing signal reproducing means. On the basis of the autocorrelation detection circuit 32, a signal (for example, a PG signal) serving as a reference of the rotation phase of the rotary drum, and the output signal of the autocorrelation detection circuit 32 (the reference signal of the rotation phase and the reproduced sweep signal). Time interval measuring circuit 17 as tape feed phase control means for performing tape feed phase control based on the time difference from the autocorrelation detection output of
And a speed control circuit 22, an adding circuit 25, and the like.

In this embodiment, the predetermined timing signal TG is, for example, 100 kHz to 500 kHz.
A sweep signal of kHz is used.

For convenience of explanation, the construction of the recording system of the embodiment of the present invention will be described first.

The recording system of the recording / reproducing apparatus of the embodiment of the present invention comprises:
As shown in FIG. 2, a sweep signal generation circuit that generates a sweep signal TG as a timing signal based on a signal (REF signal, for example, PG signal) serving as a reference of the rotation phase of the rotary drum supplied through a terminal 33. 9 and a sweep signal TG generated by the sweep signal generating circuit 9 are recorded on a plurality of inclined tracks (for example, four helical tracks corresponding to the A head, B head, C head, and D head of the VTR). Recording timing control circuit 10 and switches 11 _A , 11 _B , 1 as means
1 _C , 11 _D, A head H _A , B head H _B , C head H _C , D head H _{D, and the} like.

Here, the above-mentioned A of the recording / reproducing apparatus of the present embodiment.
Head H _A , B head H _B , C head H _C , D head H
_D is arranged on the rotating drum 8 as shown in FIG. Note that FIG. 3 also shows the tape guides 5 and 7 and the magnetic tape 20.

In the recording / reproducing apparatus of the present embodiment shown in FIG. 2, terminals _A , 32 _B , 32 _C and 32 _D are connected to the A head H _A , B head H _B , C head H _C and D head. each a-channel recording signal sent to H _D, B-channel recording signals, C-channel recording signals, D-channel recording signal is supplied. These A to D channel recording signals are sent to one of the switched terminals of the switches 11 _A , 11 _B , 11 _C and 11 _D.

Each of these switches 11 _A , 11 _B , 1
The A to D channel recording signals via 1 _C and 11 _D are amplified by recording amplifiers 12 _A , 12 _B , 12 _C and 12 _D , respectively, and then rotary transformers 13 _A and 1 _D.
3 _B, 13 _C, 13 via respective _D corresponding the A head H _A, B head H _B, C head H _C, is sent to the D head H _D.

At this time, the A head H _A , the B head H _B , the C head H _C and the D head H _D are arranged as shown in FIG.
The rotating drum 8 shown in FIG. 3 rotates at a predetermined rotation speed in the direction indicated by an arrow R in the figure, and the magnetic tape 20 wound around the rotating drum 8 runs at a predetermined tape running speed, thereby rotating the rotation. Each A head H _A of the head 8,
The B head H _B , the C head H _C , and the D head H _D form each helical track tr on the magnetic tape 20 as shown in FIG. Incidentally, in this figure 4 shows only four helical tracks formed by the A~D head H _A to H _D.

Further, in the recording / reproducing apparatus of this embodiment shown in FIG. 2, for example, a PG signal is supplied to the terminal 33 as a signal serving as a reference of the rotation phase of the rotary drum 8. This PG signal is sent to the sweep signal generation circuit 9 and the recording timing control circuit 10.

The sweep signal generation circuit 9 includes the PG
Frequency 100 kHz to 500 kHz based on the signal
To generate the sweep signal TG. The sweep signal TG from the sweep signal generating circuit 9 is sent to the other switched terminals of the switches 11 _A , 11 _B , 11 _C and 11 _D.

Each of these switches 11 _A , 11 _B , 1
The sweep signal TG via the other switched terminals of 1 _C and 11 _D is recorded on the magnetic tape 20 through the same path as described above.

At this time, in this embodiment, each switch 11
_By controlling the switching operation of _A , 11 _B , 11 _C , and 11 _{D by} the switching control signal from the recording timing control circuit 10, the sweep signal TG recorded on the magnetic tape 20 is transferred to the helical track ( are to be recorded in a predetermined position on four tracks) tr corresponding to A~D head H _a to H _D.

That is, as shown in FIG. 4, the recording timing control circuit 10 of the recording / reproducing apparatus of the present embodiment has the above A to
D head H _A to H _D by four helical tracks t
The switching operation of the switches 11 _A , 11 _B , 11 _C and 11 _D is controlled so that the sweep signal TG is recorded in r. Specifically, at each time interval T based on the PG signal from the terminal 33, each helical track t
switches 11 _A , 11 _B , 11 _C , 11 _D corresponding to r
The switching operation of is controlled.

In FIG. 4, the helical track tr on which a video signal or the like formed on the tape is recorded, and the scanning locus of the rotary head for reproducing the signal recorded on the helical track tr ( Arrow A in FIG. 4
Scan path), a signal (PG signal) synchronized with the rotation of the rotary drum, and a sweep signal T recorded for each helical track tr at a time interval T based on the PG signal.
G is shown.

When the scanning locus indicated by the arrow A in FIG. 4 is gradually shifted with respect to the helical track tr, for example, the reproduced sweep signal TG and the PG signal synchronized with the rotation of the rotary drum 8 are reproduced. The relationship of the time difference (i.e., the time interval T) with is as shown in FIG.

That is, as is clear from FIG.
In the apparatus of this embodiment, tracking control becomes possible by detecting the time interval T and controlling the tape feeding phase based on the detection result.

Returning to FIG. 1, the structure of the reproducing system of the recording / reproducing apparatus of this embodiment will be described below.

That is, in the structure of the reproducing system of the recording / reproducing apparatus of this embodiment shown in FIG. 1, the tape reproduction signal from the rotary head H is amplified by the reproduction amplifier 14 and sent to the signal processing circuit 15. For example, a video signal is output from the signal processing circuit 15, and the video signal is output from the terminal 31 to the subsequent stage configuration.

On the other hand, the magnetic tape 20 on which the helical track tr is written is crimped by a pinch roller 19 to a capstan motor 18 driven by a motor drive circuit (amplifier) 21, and the capstan motor 18 rotates. Moving speed of the magnetic tape 20 (tape speed)
Is changing.

Further, an FG signal is generated according to the rotation of the capstan motor 18. The FG signal for detecting the rotation speed of the capstan motor 18 is amplified by the FG signal amplifier 24, and then waveform-shaped by the waveform shaping circuit 23 for pulse-shaping the signal to obtain the speed. It is input to the control circuit 22. The speed control circuit 22 outputs a control signal to the motor drive circuit 21 through the adder circuit 25 so that the frequency of the pulse-shaped FG signal becomes a constant value. This allows the tape speed to be kept constant.

The output of the reproduction amplifier 14 is also sent to the waveform shaping circuit 16. The waveform forming circuit 16 is
The output of the reproduction amplifier 14 (reproduction sweep signal TG) is pulse-shaped. The reproduction sweep signal TG formed into a pulse waveform from the waveform shaping circuit 16 is sent to the autocorrelation detection circuit 32. Details of the autocorrelation detection circuit 32 will be described later.

The output of the autocorrelation detection circuit 32 is reproduced in a pulse shape by the waveform shaping circuit 33 and sent to the time interval measuring circuit 17.

The time interval measuring circuit 17 has a terminal 30.
A PG signal (REF signal) is also supplied via the. The time interval measuring circuit 17 measures the time interval between the timing of the PG signal and the timing of the autocorrelation detection output of the reproduction sweep signal TG.

Here, the time relationship between the autocorrelation detection result of the sweep signal TG reproduced by the rotary heads H and obtained from the autocorrelation detection circuit 32 and the PG signal (REF signal) is as follows. Helical track t
It takes a known value when correctly scanned over r. Therefore, from the time relationship between the PG signal measured by the time interval measuring circuit 17 and the autocorrelation detection result of the sweep signal TG, the deviation amount and the direction of the scanning trajectory of the rotary head H with respect to each helical track can be detected. ..

That is, the time interval measuring circuit 1 of this embodiment
The output of 7 is "0" as a known value obtained when each head H correctly scans the helical track. Therefore, in the present embodiment, a known value (“0”) when each head H correctly scans the helical track.
When the tape speed needs to be increased in accordance with the relationship between the direction detected based on the FG signal and the tape traveling direction, a value proportional to the shift amount when the center value is "positive",
The time interval measuring circuit 17 is configured to output a "negative" value when it is necessary to delay.

The output of the time interval measuring circuit 17 is sent to the adding circuit 25. Therefore, in the present embodiment, by adding the output of the time interval measuring circuit 17 to the output of the speed control circuit 22 by the adding circuit 25, the scanning locus so that the rotary head H correctly scans the helical track tr. Since the deviation with respect to the helical track tr can be corrected, good tracking control becomes possible.

Here, the autocorrelation detection circuit 32 will be described. FIG. 6 shows the sweep signal TG reproduced by the head H of the recording / reproducing apparatus of the present embodiment, the waveform shaping circuit output after the waveform shaping circuit 16 has shaped the reproduced sweep signal TG, and the waveform generation. It shows sampling data when the circuit output is sampled with an appropriate clock.

FIG. 7 shows a specific example (digital autocorrelation detection circuit) of the autocorrelation detection circuit 32 of this embodiment.

In FIG. 7, the terminal 70 is supplied with the waveform shaping circuit output from the waveform shaping circuit 16, and the terminal 82 is supplied with the clock CK. The sweep signal T pulse-shaped in the waveform shaping circuit 16
G is supplied to the data input terminal of the flip-flop 71 via the terminal 70. This flip-flop 71
Of the flip-flop 72 is connected to the data input terminal of the flip-flop 72, and the data output terminal of the flip-flop 72 is connected to the data input terminal of the flip-flop 73. Are connected as well. The clock CK from the terminal 82 is supplied to each clock input terminal of each of the flip-flops 71 to 81. Further, the outputs of the flip-flops 71 to 81 are sent to the adder 91. However, the outputs of the flip-flops 74, 75 and 76 and the flip-flop 7
The outputs of 9, 80 correspond to the corresponding inverters 84,
It is adapted to be sent to the adder 91 via 85, 86, 89 and 90.

In order to realize a circuit for detecting the autocorrelation between the reproduction sweep signal TG and the original signal in the configuration shown in FIG. 7, the clock for obtaining the sampling data shown in FIG. The sampling clock CK may be input, and all of the flip-flops 71 to 81 may be set to "1" when the outputs of the flip-flops 71 to 81 match the sampling of the original signal. Since the autocorrelation detection output of the digital autocorrelation detection circuit becomes the maximum value when the sampling result of the input signal and the sampling data of the original signal match, the sweep signal TG is detected by detecting the time of the peak value. It becomes possible to detect the playback time of.

In FIG. 6 and FIG. 7, in order to facilitate the explanation, the sampling data of the original signal is “11100”.
An example of the autocorrelation detection circuit that obtains the maximum value in the case of 01100 "is shown.

As the autocorrelation detection circuit 32 of the recording / reproducing apparatus of this embodiment, an analog autocorrelation detection circuit as shown in FIG. 8 may be used in addition to the digital autocorrelation detection circuit described above. It is possible.

That is, the analog autocorrelation detection circuit of FIG. 8 detects a plurality of delay lines (DL) 41 for delaying the reproduction signal and whether or not the output of each delay line 41 is at a predetermined level. It is composed of a plurality of window comparators 60 and a resistance adder 61 that adds the outputs of the window comparators 60.

Terminal 40 of this analog autocorrelation detection circuit
The auto-correlation detection output becomes maximum when the reproduction sweep signal TG input to the input signal coincides with the level set in each window comparator 60.

When the timing signal to be recorded on the helical track tr is not the sweep signal TG as described above but a signal of, for example, a single frequency as shown in FIG. 9, the reproduced timing signal has a waveform. After shaping, by measuring the time difference Tb between the rising edge of the first wave and the PG signal synchronized with the rotation of the rotary drum 8, the scanning locus of the rotary head and the helical track tr are measured.
The deviation will be detected. However, in this case, for example, when a part of the reproduction timing signal is dropped due to dropout or the like and the rising edge of the first wave cannot be detected, the deviation between the scanning locus of the rotary head and the helical track tr is , Can not be detected accurately.

On the other hand, when the sweep signal TG is recorded as the timing signal on the helical track tr as in this embodiment, as shown in FIG. 10, the autocorrelation detection of the reproduced sweep signal TG is performed. By measuring the time difference Ta between the output and the PG signal synchronized with the rotation of the rotary drum 8, it is possible to detect the deviation between the scanning track of the rotary head and the helical track tr. In the autocorrelation detection output, even if a part of the reproduction sweep signal TG is lost due to dropout or the like, only the peak level of the output signal fluctuates. Therefore, a deviation between the scanning locus of the rotary head and the helical track tr is generated. You will be able to detect. Therefore, good tracking can be maintained.

That is, as described above, in the present embodiment, the advantage of using the sweep signal TG as the timing signal on the helical track tr is that a reliable autocorrelation detection output can be obtained in a narrow frequency band. With a continuous wave of one frequency, the autocorrelation detection output has a plurality of peak outputs and is difficult to detect. Further, the sweep signal TG is used because it is easier to configure an equivalent circuit of the reproducing system and the like, and it is easier to reproduce even when the waveform is broken, as compared with a signal having a random frequency.

In the above-described embodiment, for example, the PG signal is used as the signal synchronized with the rotation of the rotary drum 8, but the rotary drum 8 to which the rotary head H is attached is used.
If it is a signal that is synchronized with the rotation of, and the time relationship with the reproduction waveform of the sweep signal TG can be measured, then the above PG
It is not limited to signals.

The same applies to the sweep signal TG recorded on the helical track tr.
The frequency and the waveform are not limited as long as they can be reproduced by, and the time relationship with the signal synchronized with the rotation of the rotary drum 8 to which the rotary head H is attached can be measured.

As described above, in the recording / reproducing apparatus of this embodiment, even if the tape is changed over time, the tape tension is varied during recording / reproduction, the tape running system is changed, etc., the video head is driven by the helical track. Can be scanned accurately. Further, since the influence of the reproduction signal level can be ignored, the optimum point of the helical track scanning does not shift due to variations in the recording / reproduction efficiency of the head used during recording / reproduction. Further, since it is not necessary to record the control signal (CTL signal) on the track in the longitudinal direction of the tape,
No fixed head is required, and the mechanism can be simplified. At the same time, since a dedicated recording circuit is not necessary, the circuit can be simplified. Furthermore, even if a part of the sweep signal (timing signal) is lost due to dropout or the like, the phase error can be detected.

[0054]

As is apparent from the above description, in the recording / reproducing apparatus according to the present invention, the predetermined timing signal recorded on the slanted track is reproduced, and the autocorrelation of this timing signal is detected. By controlling the tape feed phase based on the autocorrelation detection output and the signal that serves as the reference of the rotation phase of the rotating drum, for example, changes in the tape over time, variations in tape tension during recording and reproduction, and tape running system Even if there is a change or the like, the head can accurately scan the helical track.

That is, according to the recording / reproducing apparatus of the present invention, since the influence of the reproduction signal level can be ignored, the optimum point of helical track scanning does not shift due to variations in recording / reproducing efficiency of the heads used during recording / reproducing. ..
Further, since it is not necessary to record the control signal (CTL signal) on the track in the longitudinal direction of the tape, the fixed head is not required and the mechanism can be simplified. At the same time, since a dedicated recording circuit is not necessary, the circuit can be simplified. Furthermore, even if a part of the sweep signal (timing signal) is lost due to dropout or the like, the phase error can be detected.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a configuration example of a reproducing system of a recording / reproducing apparatus of an embodiment of the present invention.

FIG. 2 is a block circuit diagram showing a configuration example of a recording system of a recording / reproducing apparatus of an embodiment of the present invention.

FIG. 3 is a diagram showing a rotary head, a rotary drum, and a tape of this embodiment.

FIG. 4 is a diagram showing a tape on which a helical track is formed by the recording / reproducing apparatus of this embodiment.

FIG. 5 is a diagram for explaining a deviation of a scanning locus due to a sweep signal (timing signal) and a PG signal in the present embodiment.

FIG. 6 is a diagram showing a sweep signal reproduced by the structure of the reproducing system of the present embodiment, its waveform shaping circuit output, and its sampling data.

FIG. 7 is a block circuit diagram showing a specific configuration of a digital autocorrelation detection circuit applied to the apparatus of this embodiment.

FIG. 8 is a block circuit diagram showing a specific configuration of an analog autocorrelation detection circuit applied to the device of this embodiment.

FIG. 9 is a diagram for explaining a defect when a single frequency signal is used as a timing signal.

FIG. 10 is a diagram for explaining an advantage when a sweep signal is used as a timing signal.

[Explanation of symbols]

 9 ... Sweep signal generation circuit 10 ... Recording timing control circuit 11 ... Switch 12 ... Recording amplifier 13 ... Rotary transformer H ... Rotary head 15 ... ..Signal processing circuit 16, 23, 33 ... Waveform shaping circuit 17 ... Time interval measuring circuit 18 ... Capstan motor 19 ... Pinch roller 20 ... Magnetic tape 21 ... .... Motor drive circuit 22 ... Speed control circuit 25 ... Addition circuit 32 ... Autocorrelation detection circuit

Claims (1)

[Claims] 1. A timing signal reproducing means for reproducing a predetermined timing signal recorded on an inclined track, an autocorrelation detecting means for detecting an autocorrelation of the timing signal from the timing signal reproducing means, and a rotation of a rotary drum. A recording / reproducing apparatus comprising a tape feed phase control means for controlling a tape feed phase based on a signal serving as a phase reference and an output signal of the autocorrelation detection means.