JP3116541B2 - Recording and playback device - Google Patents

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 a signal on / from a tape-shaped recording medium by a so-called helical scan system.

[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 a longitudinal direction, and a phase servo is performed by a time difference between the reproduced CTL signal and a reference signal (REF signal) during reproduction. The tracking servo is performed by applying.

[0003]

However, in the conventional method of recording the CTL signal on the longitudinal track,
The physical distance between the inclined track (helical track) to be reproduced and the CTL signal recorded in the longitudinal direction changes due to the temporal change of the tape, the variation of the tape tension at the time of recording and reproduction, the change of the tape running system, and the like. I will. For this reason, the conventional method has a problem that the rotating 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, a pilot signal is recorded on a helical track, for example, as in a so-called 8 mm VTR,
In some cases, so-called ATF tracking control, which performs tracking by controlling the leakage signal from an adjacent track to a minimum during reproduction, is employed. However, in such a control method, the minimum point of the leak signal (the just track position obtained from the leak signal) and the optimum point of the helical track scanning due to variations in the recording and reproducing efficiency of the head used at the time of recording and reproducing. Is shifted, so that there is still a problem that scanning cannot be performed accurately.

Further, for example, a method in which a simple timing signal is recorded on each helical track can be considered.
This method has a drawback that if a timing signal is lost due to, for example, dropout, the phase error cannot be detected.

Accordingly, the present invention has been proposed in view of the above-described circumstances, and even if there is a change in the tape with time, a variation in the tape tension during recording and reproduction, a change in the tape running system, etc. It is an object of the present invention to provide a recording / reproducing apparatus capable of accurately scanning a helical track.

[0007]

SUMMARY OF THE INVENTION A recording / reproducing apparatus according to the present invention has been proposed to achieve the above-mentioned object, and has a signal (for example, P
G signal), and a sweep signal recording means for recording the sweep signal generated by the sweep signal generation means on an inclined track.

Here, the sweep signal is, for example, 10
A sweep signal of 0 kHz to 500 kHz is used.

Further, the reproducing system of the recording / reproducing apparatus of the present invention comprises:
A sweep signal reproducing unit for reproducing a sweep signal recorded on the inclined track; an autocorrelation detecting unit for detecting an autocorrelation of an output signal from the sweep signal reproducing unit; a signal serving as a reference of a rotation phase of the rotating drum; Tape feed phase control means for controlling the tape feed phase based on the output signal of the autocorrelation detection means.

That is, according to the present invention, in a helical scan type magnetic tape signal recording / reproducing apparatus, a sweep signal synchronized with the rotation of a drum is recorded as a timing signal on a helical track at the time of recording, and the signal is reproduced at the time of reproduction. 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 representing the rotation phase of the drum, the relative position of the rotating head and the helical track in the vertical direction with respect to the traveling locus of the rotating head It is characterized in that tracking information detection for detecting a physical deviation is performed.

In other words, in the present invention, a sweep signal synchronized with the rotation of the drum is recorded on a helical track, and at the time of reproduction, the reproduction timing is detected from the autocorrelation detection result of the signal, and the phase servo of the capstan motor is detected. , A control system that is not easily affected by dropouts, level fluctuations, and the like can be realized.

[0012]

According to the recording / reproducing apparatus of the present invention, the sweep signal generated based on the signal serving as the reference of the rotation phase of the rotating drum is recorded on the inclined track. This sweep signal is easy to detect. By performing phase detection using this sweep signal at the time of subsequent reproduction, accurate tracking control can be performed.

[0013]

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

As shown in FIG. 1, the recording / reproducing apparatus according to the embodiment of the present invention uses a timing based on a signal (REF signal, eg, PG signal) which is supplied via a terminal 33 and serves as a reference for the rotational phase of the rotating drum. Sweep signal T as signal
A sweep signal generating circuit 9 for generating G, and a sweep signal TG generated by the sweep signal generating circuit 9 are transmitted to a plurality of inclined tracks (for example, A head, B head, C head of VTR).
(4 helical tracks for head and D head)
, A recording timing control circuit 10 as a sweep signal recording means and switches 11 _A , 11 _B , 11 _C ,
11 _D and A head H _A, B head H _B, C head H _C, is made of a D head H _D, and the like.

In the present embodiment, the sweep signal TG
Is a sweep signal of, for example, 100 kHz to 500 kHz.

Here, the above-mentioned A of the recording / reproducing apparatus of this embodiment is described.
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. FIG. 2 also shows the tape guides 5, 7 and the magnetic tape 20.

[0017] In the recording and reproducing apparatus of the present embodiment shown in FIG. 1, the terminal _{32 A, 32 B, 32 C} , 32 D, the A head H _A, B head H _B, C head H _C, 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~D channel recording signal is sent to switch _{11 A, 11 B, 11 C} , 11 D each one of the switching terminal of the.

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 the recording amplifiers 12 _A , 12 _B , 12 _C and 12 _D , respectively, and then the rotary transformers 13 _A and 1 _D are amplified.
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.
Is rotated at a predetermined rotation speed in a direction indicated by an arrow R in the figure, and the magnetic tape 20 wound around the rotation drum 8 runs at a predetermined tape running speed, whereby the rotation is performed. Each A head H _A of the head 8,
B head H _B, C head H _C, on the magnetic tape 20 by the D head H _D, each helical track tr, as shown in FIG. 3 is formed. Note that this FIG. 3 shows only four helical tracks formed by the A~D head H _A to H _D.

In the recording / reproducing apparatus of this embodiment shown in FIG. 1, a terminal 33 is supplied with, for example, a PG signal as a signal serving as a reference of the rotational 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
100kHz to 500kHz based on the signal
Is generated. The sweep signal TG from the sweep signal generation circuit 9 is sent to the other switched terminal of each 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 terminal 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
The _{A, 11 B, 11 C,} 11 D of the switching operation by controlling the switching control signal from the recording timing control circuit 10, the sweep signal TG is recorded on the magnetic tape 20, 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. 3, the recording timing control circuit 10 of the recording / reproducing apparatus of this embodiment
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 of the helical tracks t
switches 11 _A , 11 _B , 11 _C , 11 _D corresponding to r
Is controlled.

FIG. 3 shows the helical track tr formed on a tape on which, for example, a video signal or the like is recorded, and the scanning trajectory of a rotary head for reproducing the signal recorded on the helical track tr ( Arrow A in FIG.
, A signal synchronized with the rotation of the rotating drum (PG signal), and a sweep signal T recorded for each helical track tr at time intervals T based on the PG signal.
G is shown.

When the scanning locus indicated by the arrow A in FIG. 3 is gradually shifted with respect to, for example, the helical track tr, the reproduced sweep signal TG and the PG signal synchronized with the rotation of the rotary drum 8 are reproduced. 4 (that is, the time interval T) is as shown in FIG.

That is, as is apparent from FIG.
In the present embodiment, tracking control can be performed by detecting the time interval T and controlling the tape feed phase based on the detection result.

Next, FIG. 5 shows the configuration of the reproducing system of the recording / reproducing apparatus of the present embodiment.

That is, as shown in FIG. 5, the recording / reproducing apparatus according to the embodiment of the present invention reproduces the sweep signal TG recorded as a timing signal on the helical track tr as shown in FIG. A head H as a means (only one of the A to D heads is shown in FIG. 5), an autocorrelation detecting circuit 32 for detecting an autocorrelation of the sweep signal TG from the sweep signal reproducing means, Based on a signal (for example, a PG signal) serving as a reference for the rotation phase of the rotating drum and the output signal of the autocorrelation detection circuit 32, the difference between the signal serving as the reference for the rotation phase and the autocorrelation detection output of the reproduced sweep signal is obtained. Time interval measurement circuit 17 and speed control circuit 2 as tape feed phase control means for performing tape feed phase control based on a time difference)
2, an addition circuit 25 and the like.

That is, in the configuration of the reproducing system of the recording / reproducing apparatus of this embodiment shown in FIG. 5, the tape reproducing signal from the rotary head H is amplified by the reproducing 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 a terminal 31 to a subsequent configuration.

On the other hand, the magnetic tape 20 on which the helical track tr is written is pressed against a capstan motor 18 driven by a motor drive circuit (amplifier) 21 by a pinch roller 19, and the rotation of the capstan motor 18 is performed. 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 an amplifier 24 for the FG signal, and then subjected to waveform shaping by a waveform shaping circuit 23 for shaping the signal into a pulse shape. It is input to the control circuit 22. The speed control circuit 22 outputs a control signal to the motor drive circuit 21 via the addition circuit 25 so that the frequency of the FG signal whose waveform is shaped like a pulse becomes a constant value. This allows the tape speed to be kept constant.

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

The output of the autocorrelation detecting circuit 32 is reproduced in a pulse form 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 a 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 each rotary head H and obtained from the autocorrelation detection circuit 32 and the PG signal (REF signal) is as follows. Helical truck t
It takes a known value when it scans over r correctly. Therefore, from the time relationship between the PG signal measured by the time interval measurement circuit 17 and the autocorrelation detection result of the sweep signal TG, the amount of displacement of the scanning trajectory of the rotary head H with respect to each helical track and its direction can be detected. .

That is, the time interval measuring circuit 1 of this embodiment
The output of 7 is "0", which is a known value obtained when each head H correctly scans on the helical track. Therefore, in this embodiment, a known value ("0") when each of the heads 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 advancing direction, a value proportional to the deviation amount when the center value is
The time interval measuring circuit 17 is configured to output a “negative” value when it is necessary to delay the time.

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 trajectory is adjusted so that the rotary head H scans the helical track tr correctly. Can be corrected with respect to the helical track tr, and good tracking control can be performed.

Here, the autocorrelation detection circuit 32 will be described. FIG. 6 shows a sweep signal TG reproduced by the head H of the recording / reproducing apparatus of the present embodiment, a waveform shaping circuit output after the reproduction sweep signal TG has been waveform-shaped by the waveform shaping circuit 16, and the waveform generation. And sampled 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 output of the waveform shaping circuit from the waveform shaping circuit 16 is supplied to a terminal 70, and a clock CK is supplied to a terminal 82. The sweep signal T shaped into a pulse by 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
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. Connected similarly. 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, 76 and the flip-flop 7
9 and 80 are output from corresponding inverters 84 and 84, respectively.
The data is sent to the adder 91 via 85, 86, 89, 90.

In the configuration shown in FIG. 7, in order to realize a circuit for detecting the auto-correlation between the reproduced sweep signal TG and the original signal, a clock for obtaining the sampling data shown in FIG. What is necessary is just to set it so that when it is input as the sampling clock CK and the outputs of the flip-flops 71 to 81 coincide with the sampling of the original signal, all become “1”. The auto-correlation detection output of the digital auto-correlation detection circuit has the maximum value when the sampling result of the input signal and the sampling data of the original signal match, so that by detecting the time of the peak value, the sweep signal TG is detected. Can be detected.

In FIGS. 6 and 7, for ease of explanation, the sampling data of the original signal is "11100".
An example of an autocorrelation detection circuit that obtains the maximum value in the case of 01100 ″ is shown.

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

That is, the analog autocorrelation detecting circuit shown in FIG. 8 detects a plurality of delay lines (DL) 41 for delaying a reproduced signal and detects whether the output of each delay line 41 is at a predetermined level. And a resistance adder 61 for adding the outputs of the respective window comparators 60.

Terminal 40 of this analog autocorrelation detection circuit
When the reproduction sweep signal TG inputted to the window coincides with the level set in each window comparator 60, the autocorrelation detection output becomes maximum.

When the timing signal to be recorded on the helical track tr is not a 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 the shaping, the time difference Tb between the rising edge of the first wave and the PG signal synchronized with the rotation of the rotating drum 8 is measured, so that the scanning trajectory of the rotating head and the helical track tr are measured.
Will be detected. However, in this case, for example, if a part of the reproduction timing signal is lost due to dropout or the like and the rising edge of the first wave cannot be detected, the deviation between the scanning track of the rotating head and the helical track tr is determined. Cannot 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, the autocorrelation detection of the reproduced sweep signal TG is performed as shown in FIG. 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 trajectory of the rotary head and the helical track tr. The output of the autocorrelation detection indicates the deviation between the scanning trajectory of the rotary head and the helical track tr because 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. It can be detected. Therefore, good tracking can be maintained.

That is, as described above, in this embodiment, the advantage of using the sweep signal TG as the timing signal for the helical track tr is that a reliable autocorrelation detection output can be obtained in a narrow frequency band. In a continuous wave of one frequency, the autocorrelation detection output has a plurality of peak outputs, which makes it difficult to detect. Further, as compared with a signal of a random frequency, an equivalent circuit or the like of a reproducing system is easily formed, and it is easy to reproduce even a waveform collapse. Therefore, the sweep signal TG is used.

In the above-described embodiment, for example, a PG signal is used as a 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 the signal is synchronized with the rotation of the sweep signal and can measure the time relationship with the reproduction waveform of the sweep signal TG, the PG
It is not particularly limited to signals.

The same applies to the sweep signal TG recorded on the helical track tr.
The frequency, waveform, etc., are not limited as long as the time relationship with a 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 the present embodiment, the video head can be used for the helical track even if the tape changes over time, the tape tension varies at the time of recording / reproducing, or the tape running system changes. 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 the variation of the recording and reproduction efficiency of the head used at the time of recording and reproduction. Further, since there is no need to record a control signal (CTL signal) on a track in the longitudinal direction of the tape,
The need for a fixed head is eliminated, and the mechanism can be simplified. At the same time, since a dedicated recording circuit is not required, the circuit can be simplified. Further, even if a part of the sweep signal (timing signal) is lost due to dropout or the like, a phase error can be detected.

[0053]

As is clear from the above description, in the recording / reproducing apparatus according to the present invention, a sweep signal based on a signal serving as a reference of the rotation phase of the rotating drum is recorded on the inclined track, so that it can be used later. If this sweep signal is used at the time of reproduction, the head can accurately scan the helical track even if there is, for example, a temporal change of the tape, a variation in the tape tension at the time of recording / reproduction, or a change in the tape running system.

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 the helical track scanning does not shift due to variations in the recording / reproduction efficiency of the head used for 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, a fixed head is not required, and the mechanism can be simplified. At the same time, since a dedicated recording circuit is not required, the circuit can be simplified. Further, even if a part of the sweep signal (timing signal) is lost due to dropout or the like, a phase error can be detected.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a rotary head, a rotary drum, and a tape according to the embodiment.

FIG. 3 is a diagram showing a tape on which a helical track is formed by the recording / reproducing apparatus of the embodiment.

FIG. 4 is a diagram for explaining a shift of a scanning locus due to a sweep signal (timing signal) and a PG signal according to the present embodiment.

FIG. 5 is a block circuit diagram showing a configuration example of a reproduction system of the recording / reproduction device according to the embodiment of the present invention.

FIG. 6 is a diagram showing a sweep signal reproduced by the configuration of the reproduction 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 device of the embodiment.

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

FIG. 9 is a diagram for explaining a disadvantage 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: Rotating 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.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 15/467

Claims (1)

(57) [Claims] 1. A sweep signal generating means for generating a sweep signal based on a signal serving as a reference of a rotation phase of a rotary drum, and a sweep signal recording for recording the sweep signal generated by the sweep signal generating means on an inclined track. And a recording / reproducing apparatus.