JPH0762928B2 - Playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A Industrial Field B Outline of Invention C Conventional Technology D Problems to be Solved by the Invention E Means for Solving Problems (Fig. 1) F Action G Example G1 Structure Description G2 Specific Action Description H Effect of the Invention A Field of Industrial Application The present invention relates to a reproducing apparatus that employs a so-called ATF (Automatic Track Finding) system as a tracking system.

B. SUMMARY OF THE INVENTION The present invention, during still reproduction, pilots of adjacent recording tracks before and after adjacent ones in one field period in which the frequency of pilot signals of recording tracks scanned by a plurality of reproducing heads are at a predetermined level. Since the reference pilot signal having the same frequency as the signal is generated from the reference pilot signal generating means (8) by the control means (9), the difference frequency component detecting means (1
The levels of the detection signals from (0) and (13) can be emphasized, whereby the reproducing heads (2A), (2A ′), (2
The subtle deviation of the scanning position to the adjacent recording track in (B) is sharply detected to promptly reduce the noise due to the track deviation during still reproduction.

C Conventional Technology Conventionally, there is known a rotary head type video tape recorder (VTR) that performs so-called ATF system tracking. That is, a pilot signal whose frequency cyclically changes for each inclined recording track formed continuously on the magnetic tape is recorded, and the difference between the pilot signal reproduced by the reproducing head and the reference pilot signal is multiplied. The signal of the frequency component is detected, the capstan motor is controlled based on the detected signal, and the tracking is automatically adjusted.

D. Problems to be Solved by the Invention By the way, this ATF type tracking servo does not work when the tape is not running, works only while the tape is running, and has a slow response. Therefore, if there is no period during which the tape is moving, such as in the still playback mode or the slow playback mode with intermittent feed, or in the short mode, the tracking servo cannot fully follow and noise due to tracking deviation occurs. There was a problem of leaving it as it was.

E Means for Solving Problems (FIG. 1) The present invention is designed to reproduce by recording a pilot signal whose frequency cyclically changes for each inclined recording track formed continuously on a magnetic tape (1). Heads (2A), (2A '),
The detection signal of the difference frequency component after the multiplication of the pilot signal reproduced in (2B) and the reference pilot signal is detected, and the reference pilot signal generating means (8) for generating the reference pilot signal and the detection signal Based on the driving means (17) for controlling the capstan motor (16) and the control means (9) for controlling the reference pilot signal generating means (8) and the driving means (17), tracking is automatically performed. In the reproducing device for adjustment, the control means (9) is
During normal playback, multiple playback heads (2A), (2A '),
A reference pilot signal having a frequency equal to the frequency of the pilot signal of the recording track scanned by (2B) is generated from the reference pilot signal generating means (8), and at the time of still reproduction, a plurality of reproducing heads (2A), (2A) ′),
In one field period in which the frequency of the pilot signal of the recording track scanned by (2B) is at a predetermined level, the reference pilot signal having a frequency equal to the frequency of the pilot signal of the recording track immediately before and one adjacent to the recording track adjacent thereto is used as a reference. A reproducing apparatus characterized in that the capstan motor (16) is controlled by the pilot signal generating means (8) and the driving means (17) is controlled to perform tracking adjustment within a certain range. is there.

In the configuration above F action, the capstan motor is controlled even during still reproduction, and the tracking adjustment is performed within a certain range. Therefore, even if there is no period during which the tape is moving, or even in a short mode, sufficient tracking servo is achieved. Is possible.

G Example Hereinafter, an example of the present invention will be described with reference to FIG.

In the same figure, (1) is a magnetic tape, and on this magnetic tape (1), recording tracks T _A and T _B having different recording azimuths are alternately arranged as shown in FIG. Formed in
Then, the frequencies are f ₁ , f ₂ , f ₃ , and for each recording track T _A , T _B.
Four types of pilot signals that cyclically change as f ₄ , f ₁ , ... Are video signals (low-frequency conversion carrier color signal C _L and FM modulation luminance signal Y _FM
(Combined signal with) and frequency multiplexed. The frequencies f ₁ , f ₂ , f ₃ , f ₄ of the pilot signal are selected in the lower band side of the low-frequency conversion carrier color signal C _L , for example 102 kHz, 118 kH, respectively.
z, 164 kHz, 148 kHz, and the frequency difference between the pilot signal of a certain recording track and the pilot signal of the adjacent recording track is Δf _A = 16 kHz, Δf _B = 46 kHz.

Further, (2A) and (2B) are rotating magnetic heads having different so-called azimuth angles, and are arranged at angular intervals of about 180 °. The heads (2A) and (2B) are made to make one revolution in one frame, and the heads (2A) are made to scan on the magnetic tape (1) in an odd field.
In the even field, the head (2B) scans the magnetic tape (1). Where head (2A)
The azimuth angles of (2B) and (2B) correspond to the recording azimuths of the recording tracks T _A and T _B. Further, (2A ′) is a rotary magnetic head for special reproduction, which has the same azimuth angle as the head (2A) and is arranged in the vicinity of the head (2B). During still reproduction, the heads (2A) and (2A) The reproduction signal is alternately obtained for each field from ′).

The reproduction signals from the heads (2A), (2A '), and (2B) are supplied to the video signal processing circuit (4) through the reproduction amplifier (3), and the output terminal (4) derived from this processing circuit (4). 5)
The video signal S _V is output to.

The output signal of the reproduction amplifier (3) is supplied to the pilot signal detection circuit (6) having a low-pass filter structure. The pilot signal detected by the detection circuit (6) is supplied to the multiplication circuit (7). Then, the reference pilot signal is supplied from the pilot signal generator (8) to the multiplication circuit (7).

Further, (9) is a system control circuit, and the RF switching pulse RFSWP is supplied to the system control circuit (9), and the pilot signal generator (8) is supplied.
The operation is controlled by the system control circuit (9).

That is, during normal playback in normal playback mode and slow playback mode (by intermittent feed), the head (2A),
Reference pilot signal whose frequency is f ₁ , f ₄ , f ₃ , f ₂ with respect to frequencies f ₁ , f ₂ , f ₃ , f ₄ of the pilot signals of recording tracks T _A , T _B scanned by (2B) Is generated. Also, during still playback in still playback mode and slow playback mode (by intermittent feed), basically, a frequency reference equal to the frequency of the pilot signal of the recording track T _A scanned by the heads (2A) and (2A ') is used. Although the pilot signal is generated, in the one field period when the RF switching pulse RFSWP is at the high level "1", the recording track TB before and after the adjacent recording track T _B in the first and second periods, respectively, is detected. The frequency is equal to the frequency of the pilot signal. For example, head (2A), (2A ')
The frequency of the pilot signal of the recording track T _A scanned by
When f ₁ , the frequency is f ₁ → f ₄ → within one field.
The frequency of the pilot signal of the recording track T _A scanned by the heads (2A) and (2A ′) is changed to f _{3 by} switching f ₁ → f ₂ → f ₁ in order.
, The frequency is f ₃ → f ₂ → f ₃ within one field.
→ f ₄ → f ₃ are switched in sequence.

FIG. 3B shows the frequency change of the reference pilot signal generated from the pilot signal generator (8) in the slow reproduction mode by intermittent feeding, for example. Simultaneous A is RF
A switching pulse RFSWP is shown, among which f _{1 to} f
Reference numeral ₄ represents the frequency of the pilot signal of the recording track scanned by the head.

In the multiplication circuit (7), the pilot signal detected by the pilot signal detection circuit (6) and the reference pilot signal from the pilot signal generator (8) are multiplied, and the output of each of the difference frequencies A signal or the like is output. In this case, during normal playback in normal playback mode and slow playback mode with intermittent feed, head (2A),
When the scanning position of (2B) scans the center of the recording track to be scanned, the difference frequency signal of frequency Δf _A = 16 kHz and the difference frequency signal of frequency Δf _B = 46 kHz are output at the same level. As the position shifts to the recording track side one before, the level of the difference frequency signal of the frequency Δf _B becomes higher than the level of the difference frequency signal of the frequency Δf _A , and conversely the scanning position is 1
The level of the difference frequency signal of the frequency Δf _A becomes higher than the level of the difference frequency signal of the week number Δf _B as it shifts toward the recording track after that. In still playback mode and still playback in slow playback mode by intermittent feed, basically the same as the above-mentioned normal playback, but the RF switching pulse
In one field period when RFSWP is at the high level "1", the frequency of the reference pilot signal is made equal to the frequency of the pilot signal of the previous recording track and the recording track after the first recording signal in the second period. So this first and second
During this period, the level of the difference frequency signal of frequency Δf _B and the level of the difference frequency signal of frequency Δf _A are emphasized.

Further, the output signal of the multiplication circuit (7) is supplied to the detection circuit (10) of the difference frequency Δf _A composed of a band pass filter, and the output signal of this detection circuit (10) is a direct current conversion circuit (11).
The output signal S _A of the DC conversion circuit (11) is supplied to one input terminal of the comparator (12). The output signal of the multiplication circuit (7) is supplied to the detection circuit (13) of the difference frequency Δf _B composed of a bandpass filter, and the output signal of this detection circuit (13) is supplied to the DC conversion circuit (14). The output signal S _B of the DC conversion circuit (14) is supplied to the other input terminal of the comparator (12). From this comparator (12), for example S _A> zero when S _B, S _A> negative value corresponding to the difference when the S _B, S _A <S positive value corresponding to the difference when the _B Is output. The output signal of this comparator (12) is
The ATF error signal E _ATF is supplied to the adder (15).

Further, (16) is a capstan motor, and (17) is its drive circuit. Further, (18) is a frequency generator, and a frequency signal corresponding to the rotation speed of the capstan motor (16) from this frequency generator (18) is supplied to a speed servo circuit (19), and this speed servo is generated. The speed error signal E _S from the circuit (19) is supplied to the adder (15).

The output signal from the adder (15) is supplied as a control signal to the drive circuit (17), and during normal reproduction in the normal reproduction mode and the slow reproduction mode, the control signal causes the rotation of the capstan motor (16). Controlled. That is, the rotation speed of the capstan motor (16) is controlled to be constant by the speed error signal E _S. Also, the ATF error signal E _ATF
Thus, the rotation phase of the capstan motor (16) is controlled, and this ATF error signal E _ATF is zero, that is, the head (2
The scanning positions of A) and (2B) are set to the center of the recording track to be scanned.

The output signal of the comparator (12) is supplied to the shift trigger circuit (20), and the output signal from the shift trigger circuit (20) is supplied to the system control circuit (9).

During still playback in still playback mode and slow playback mode, high level "1" of RF switching pulse RFSWP
The frequency of the reference pilot signal from the pilot signal generator (8) is made equal to the frequency of the pilot signal of the preceding and following recording track T _B within one field period which is Sampled in a period, a period before the first period and a period after the second period. The control signal is supplied from the system control circuit (9) to the drive circuit (17) in response to this sampling signal within one field period when the subsequent RF switching pulse RFSWP is at the low level "0". That is, for example, a signal S _ON which becomes a high level “1” corresponding to the period for moving the capstan motor (16) and the capstan motor (16)
For example, the signal S _{F / R} is supplied at a low level “0” when rotating normally, and at a high level “1” when rotating in reverse. As a result, the capstan motor (16) is controlled to rotate forward or backward by a predetermined phase.

G2 Description of specific operation In this example, for example, when still playback in still playback mode or slow playback mode, the scanning position of the head (2A) with respect to the recording track T _A (f ₁ ) is as shown in FIG. 4A. The output signal of the comparator (12) is as shown in FIG. 7B when scanning is performed with a large deviation to the previous recording track T _B (f ₄ ) side. When the threshold level of the shift trigger circuit (20) is as shown by the broken line in FIG. 9B, the output signal of the shift trigger circuit (20) is as shown in FIG. Then, by sampling this at the position of the arrow, a 4-bit sampling signal [0,0,0,0]
Is obtained. In this case, the period during which the signal S _ON is at the high level “1” is set to be large and the signal S _{F / R} is at the low level “0”.
Therefore, the capstan motor (16) is largely controlled in the normal direction so that the scanning position of the head (2A) becomes the center of the recording track T _A (f ₁ ).

Further, as shown in FIG. 5A, the scanning position of the head (2A) with respect to the recording track T _A (f ₁ ) is the previous recording track T _B.
When it is slightly offset to the (f ₄ ) side, the comparator (12)
, And the output signal of the shift trigger circuit (20) are as shown in B and C of the same figure, and the 4-bit sampling signal is [0,0,1,0]. In this case, the period in which the signal S _ON is at the high level “1” is set small, the signal S _{F / R} is set at the low level “0”, and the capstan motor (16) is controlled to be small and forward. , Head (2A) scanning position is recording track
It is controlled to be the center of T _A (f ₁ ).

When the scanning position of the head (2A) is at the center of the recording track T _A (f ₁ ) as shown in FIG. 6A, the output signal of the comparator (12) and the output signal of the shift trigger circuit (20) are As shown in B and C of the same figure, the 4-bit sampling signal is [1,0,1,0]. In this case, the signal S _ON
Is set to zero and the signal S
_{The F / R} is kept at the low level “0”, and the capstan motor (16) is not controlled to rotate forward or reverse.

Further, as shown in FIG. 7A, the scanning position of the head (2A) with respect to the recording track T _A (f ₁ ) is one after the recording track T _B.
When it is slightly offset to the (f ₄ ) side, the comparator (12)
, And the output signal of the short trigger circuit (20) are as shown in B and C of the same figure, and the 4-bit sampling signal is [1,0,1,1]. In this case, the period during which the signal S _ON is at the high level “1” is set small, the signal S _{F / R} is set at the high level “1”, and the capstan motor (16) is controlled to be small in reverse. The scanning position of the head (2A) is the recording track T _A.
It is controlled to be the center of (f ₁ ).

Further, as shown in FIG. 8A, the scanning position of the head (2A) with respect to the recording track T _A (f ₁ ) is the recording track T _B after one.
When it is largely offset to the (f ₂ ) side, the comparator (12)
, And the output signal of the short trigger circuit (20) are as shown in B and C of the same figure, and the 4-bit sampling signal is [1,1,1,1]. In this case, the period during which the signal S _ON is at the high level “1” is set to be large, the signal S _{F / R} is set to the high level “1”, and the capstan motor (16) is largely reverse-controlled. The scanning position of the head (2A) is the recording track T _A.
It is controlled to be the center of (f ₁ ).

Although detailed description is omitted, the sampling signal of 4 bits may take other values corresponding to the scanning position of the head (2A), and as described above, the signal S _ON is turned on in accordance with the scanning position of the head (2A). Is controlled to the high level "1" and the state of the signal S _{F / R} is controlled so that the scanning position of the head (2A) is the recording track T _A.
It is controlled to be the center of (f ₁ ).

Further, FIG. 9 shows an example of the time chart when the capstan motor (16) is reversely controlled during still reproduction in the case of 1/5 slow reproduction mode, and FIG. 9A shows the RF switching pulse RFSWP. , B in the figure shows the signal S _ON , and C in the figure shows the signal S _ON .
_{F / R.} In the figure, during normal reproduction, the signal S _ON is at a high level “1”, at which time the signal S _{F / R} is at a low level “0”, the capstan motor (16) is controlled to rotate normally, and At the end of this normal playback, the signal S
_{F / R} becomes high level “1” and capstan motor (16)
Is braked. The first frame during still playback, which follows this normal playback, is not processed because the capstan motor (16) has not stopped sufficiently, and the first 1-field period of the second frame during subsequent still playback. The output signal of the shift trigger circuit (20) is sampled. Here, when the scanning position of the head (2A) is greatly deviated to the recording track T _B (f ₂ ) after the head as shown in FIG. 8A with respect to the recording track T _A (f ₁ ), The 4-bit sampling signal becomes [1,1,1,1], and the signal S _ON becomes high level "1" for a predetermined period, for example, 3 msec from the beginning of the following 1 field period, and the signal S
_{The F / R} is a high level “1”, and the capstan motor (1
6) is reversely controlled so that the scanning position of the head (2A) becomes the center of the recording track T _A (f ₁ ). Also,
The output signal of the shift trigger circuit (20) is sampled during the first one field period of the third frame during the subsequent still reproduction. Here, when the scanning position of the head (2A) is slightly offset from the recording track T _A (f ₁ ) to the next recording track T _B (f ₂ ) as shown in FIG. 7A, 4-bit sampling signal is [1,0,1,1]
From the beginning of the following 1 field period, the signal S _ON becomes high level “1” for a predetermined period, for example 2 msec, and the signal S _{F / R} becomes high level “1”, and the capstan motor (16) reverses. It is controlled so that the scanning position of the head (2A) becomes the center of the recording track T _A (f ₁ ). Also, the output signal of the shift trigger circuit (20) is sampled during the first one field period of the fourth frame during the subsequent still reproduction. Here, when the scanning position of the head (2A) is at the center of the storage track T _A (f ₁ ) as shown in FIG. 6A, the sampling signal of 4 bits is [1,
0,1,0], and the signal S _ON does not become high level “1” in the following 1 field period, and the capstan motor (1
In 6), neither normal rotation nor reverse rotation control is performed.

Further, FIG. 10 shows an example of the time chart when the capstan motor (16) is controlled to rotate normally during still playback in the 1/5 slow playback mode. RFSWP, signal S _{ON in} figure B, signal S in figure C
_{F / R.} In the figure, during normal reproduction, the signal S _ON is at a high level “1”, at which time the signal S _{F / R} is at a low level “0”, the capstan motor (16) is controlled to rotate normally, and At the end of this normal playback, the signal S
_{F / R} becomes high level “1” and capstan motor (16)
Is braked. The capstan motor (16) is not yet fully stopped in the first frame during still playback that continues during this normal playback, so no processing is performed. The first one-field period of the second frame during subsequent still playback The output signal of the shift trigger circuit (20) is sampled. Here, when the scanning position of the head (2A) is greatly offset from the recording track T _A (f ₁ ) to the previous recording track T _B (f ₂ ) as shown in FIG. 4A, The 4-bit sampling signal becomes [0,0,0,0], and the signal S _ON becomes a high level "1" for a predetermined period, for example, 3 msec from the beginning of the subsequent 1 field period, and the signal S
_{The F / R} is kept at the low level "0", the capstan motor (16) is controlled to rotate normally, and the scanning position of the head (2A) is set to the center of the recording track T _A (f ₁ ). Controlled. Further, the output signal of the shift trigger circuit (20) is sampled during the first one field period of the third frame during the subsequent still reproduction. Where the recording track T
When the scanning position of the _A (f ₁₎ head relative to (2A) is Katayose one small in FIG. 5 A of the previous As shown in a recording track T _B (f ₄₎ side, 4 sampling signal bit is [0,0,1,0], the signal S _ON is kept at the high level “1” for a predetermined period, for example, 2 msec, and the signal S _{F / R} is kept at the low level “0” from the beginning of the following 1 field period. The capstan motor (16) is controlled to rotate normally, and the head (2A)
Is controlled so that the scanning position of is the center of the recording track T _A (f ₁ ). In addition, the shutter trigger circuit (2
The output signal of 0) is sampled. Here, when the scanning position of the head (2A) is at the center of the recording track T _A (f ₁ ) as shown in FIG. 6A, the 4-bit sampling signal becomes [1,0,1,0], During the subsequent 1 field period, the signal S _ON does not become high level “1”, and the capstan motor (16) is not controlled to rotate forward or reverse.

As described above, according to this example, during still reproduction in the still reproduction mode and the slow reproduction mode by intermittent feed, the capstan motor (16) is set to the normal state based on the output signal from the comparator (12), that is, the ATF error signal. It is controlled to rotate or reverse, and the tracking is adjusted within a certain range. Therefore, according to this example, it is possible to quickly reduce the noise due to the track shift during still reproduction.

In the above embodiment, the frequency of the reference pilot signal generated by the pilot signal generator (8) during still reproduction in the still reproduction mode or the slow reproduction mode (by intermittent feed) is basically the head (2A). , (2A ') are made equal to the frequency of the pilot signal of the recording track T _A to be scanned, and in the one field period where the RF switching pulse RFSWP is at the high level "1", they are adjacent in the first and second periods, respectively. It is made equal to the frequency of the pilot signal of the preceding and following tracks T _B , but the recording tracks T _A scanned by the heads (2A) and (2A ′) are also set in the first and second periods.
If the frequency is equal to the frequency of the pilot signal of, the output signal from the comparator (12) corresponds to FIG. 4B, FIG. 5B, FIG. 6B, FIG. 7B and FIG. 8B. , Fig. 4D, 5th
As shown in FIG. D, FIG. 6D, FIG. 7D and FIG. 8D, the output signal from the shift trigger circuit (20) is the fourth signal.
As shown in FIGS. E, 5E, 6E, 7E and 8E. Therefore, the states shown in FIGS. 4E and 5E and the states shown in FIGS. 7E and 8E are indistinguishable from each other, and accurate control based on this cannot be achieved.

Further, in the above embodiment, but is equal to the frequency of the one before and one after the pilot signal track T _B of the respective adjacent first and second time periods, in the first and second periods if equal to the frequency of the respective adjacent one after and one pilot signal before the track T _B, the comparator (1
The output signal from 2) corresponds to FIGS. 4B, 5B, 6B, 7B, and 8B, and corresponds to FIGS.
As shown in FIG. F, FIG. 6F, FIG. 7F, and FIG. 8F, the output signal from the shift trigger circuit (20) is the fourth signal.
As shown in FIGS. G, 5G, 6G, 7G, and 8G. Therefore, it is impossible to obtain the data of the marked difference, and it is not possible to perform accurate control based on this.

Therefore, it is desirable to make the frequency equal to the frequency of the pilot signal of the adjacent track T _B before and after the adjacent track T _B in the first and second periods, respectively, as in the above embodiment.

H Effect of the Invention According to the present invention described above, the capstan motor is controlled based on the ATF error signal during still reproduction and the tracking adjustment is performed within a certain range. Therefore, noise due to track deviation during still reproduction is promptly generated. Can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS.
The figure is a figure for the explanation. (1) is magnetic tape, (2A) (2B) and (2A ') are
Magnetic head, (6) is pilot signal detection circuit, (7)
Is a multiplication circuit, (8) is a pilot signal generator, (9) is a system control circuit, (12) is a comparator, (16) is a capstan motor, (17) is a drive circuit, and (20) is a shift trigger circuit. Is.

Claims (1)

[Claims] 1. A pilot signal whose frequency cyclically changes is recorded for each inclined recording track continuously formed on a magnetic tape, and the pilot signal reproduced by a reproducing head is multiplied by a reference pilot signal. And a reference pilot signal generating means for generating the reference pilot signal, a driving means for controlling the capstan motor based on the detection signal, and a reference pilot signal generating means. Means and a control means for controlling the driving means, and in the reproducing apparatus for automatically adjusting the tracking, the control means controls the frequency of the pilot signal of the recording track scanned by the plurality of reproducing heads during normal reproduction. Generate a reference pilot signal having a frequency equal to To make it in, at the time of still reproduction, the frequency of the pilot signal of the recording track to be scanned a plurality of the reproducing head is a predetermined level 1
In the field period, the adjacent previous and 1 respectively
A reference pilot signal having a frequency equal to the frequency of the pilot signal of the subsequent recording track is generated from the reference pilot signal generating means, and the driving means is controlled, whereby the capstan motor is controlled and the constant range is maintained. A playback device in which tracking adjustment is performed inside.