JPH0630198B2 - Magnetic recording / reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus which realizes noiseless slow reproduction and still reproduction by intermittent driving of a magnetic tape.

[Prior art]

2. Description of the Related Art Conventionally, there is a magnetic recording / reproducing apparatus (hereinafter referred to as VTR) in which a control track is provided on a magnetic tape, a control signal is recorded and reproduced on the control track, and the traveling control of the magnetic tape is performed by the control signal. In a VTR of such a system, as one of methods for performing slow reproduction and still reproduction without noise, tape driving during slow reproduction is intermittent driving in which running and stopping are repeated, and the intermittent driving is performed during still reproduction. Some have tried to stop the magnetic tape after several times. In order to obtain a noise-free reproduced image by such a method, the positional relationship between the recording track and the rotary head must always be within a range where noise does not appear on the reproduction screen when the tape is stopped. In order to obtain, the control signal reproduced in the tape running state is used as track position information, and the tape running amount after detecting this control signal is controlled to stop the tape at a position where noise does not appear on the screen. There is.

FIG. 1 shows a control method in such a conventional device. FIG. 1 (a) shows a torm Mt to be given to a capstan motor, FIG. 1 (b) shows a tape speed v, and FIG. The control signals C are shown in FIG. As is clear from this figure, in this control method, from time t0 to t1
The tape is accelerated until the tape travels at a constant speed, and when the control signal C is detected at time t2, the delay time (t3
After -t2), the braking is started, the braking is stopped at the time t4 when the tape speed v is almost zero, and the tape is stopped.
Here, the delay time (t3-t2) is called a tracking delay time, and the tape feed amount is increased or decreased by increasing or decreasing this time. This time is usually adjusted by a variable resistor, and the time can be adjusted to stop the tape at the position where the reproduced image is the best, that is, the optimum tape stop position.

However, in such a conventional device, the user needs to adjust the tracking delay time, and the adjustment work is complicated.

By the way, in order to perform tracking adjustment and the like in the VTR, four pilot signals f1 having different frequencies generated in synchronization with the rotation by the rotary magnetic head.
There is one in which f2, f3, and f4 are sequentially multiplexed with a video signal to be recorded and recorded, and then reproduced. In such a device, the magnetic head and pilot signals f1, f2, f3, f are reproduced or when the magnetic tape is stopped.
If 4 can detect the positional relationship with the recorded video track, that is, the stop position of the magnetic tape, this can be used for the magnetic tape feeding control, and the noise adjustment can be performed without requiring the user's adjustment work. It is considered that slow reproduction and still reproduction can be performed.

[Outline of Invention]

The present invention has been made in view of the above point, and video signals to be sequentially recorded are first, second, third and fourth pilot signals having different frequencies generated in synchronization with the rotation of the rotary magnetic head. In a magnetic recording / reproducing apparatus which multiplexes and records and reproduces on / from a magnetic tape, at least one of slow reproducing means or still reproducing means for performing a series of running operations of acceleration, constant speed, braking and stopping on a magnetic tape based on a command signal, Signal amplitude detection means for separating and detecting the amplitudes of the two pilot signals of the first, third or second and fourth contained in the reproduced signal from the magnetic tape, and signal amplitude comparison for comparing the amplitudes of these two pilot signals Means for inputting the output of the signal amplitude comparing means and the switching signal of the circuit magnetic head, and during one field period defined by the switching signal,
Whether or not the magnitude relationship between the amplitudes of the two pilot signals is inverted, and when the magnitude relationship between the amplitudes is not inverted, the magnitude relationship between the amplitudes is determined. When there is such an inversion, the amplitude at the time before or after the inversion is determined. A means for outputting a region designating signal indicating which region of the magnetic tape stop position is divided into four parts according to the magnitude relationship, and a reversal of the magnitude relationship between the head switching position of the rotary head switching signal and the amplitude. The pilot signal reproduced from the magnetic tape when the magnetic tape is stopped, having means for outputting a distance signal indicating how far the stop position is from one end of the four-divided area depending on the position. Of the tape stop position detecting means for detecting the tape stop position by the reproduction pilot signal, the command signal and the tape stop position detecting means. By the force, when the tape stop position is in an area other than the predetermined two areas of the four areas, the constant speed running time of the magnetic tape is set to a length such that the tape stop position comes to the predetermined two areas. Therefore, a traveling time determining means for determining a constant speed traveling time during the slow reproduction and the still reproduction is provided, and the video track and the rotary magnetic head are read from the reproduction pilot signal in the tape stopped state during the slow reproduction and the still reproduction. By detecting the relative position of the tape and the constant speed running time of the magnetic tape according to the detected output, the tape can be automatically sent to the tape stop position where noise does not appear on the screen. It is an object of the present invention to provide a magnetic recording / reproducing apparatus that can easily obtain a noiseless slow reproduction image and still reproduction image.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a schematic structure of a VTR according to an embodiment of the present invention. In the figure, reference numeral 52 is a tape stop position detecting device, and 60 is a magnetic tape according to the output of the tape stop position detecting device 52. A running time determining means for determining a constant speed running time. In the running time determining means 60, 51 and 55 are charge / discharge circuits and one-shot circuits for inputting an acceleration signal Sα for controlling the acceleration time of the capstan motor. Reference numeral 53 is a circuit, 53 is a comparator that receives the output of the charging / discharging circuit 51 and the output signal O3 of the tape stop position detection device 52, 54 is a NOR circuit that receives the acceleration signal Sα and the output of the comparator 53, and 56 is a tape. When the output signal O1 of the stop position detecting device 52 is "H", N
It is a switch circuit that outputs the output of the OR circuit 54 and outputs the output of the one-shot circuit 55 when it is "L". The detection command signal So is a signal that becomes "H" when the tape is stopped and "L" when the tape is running. Further, the output of the switch circuit 56 becomes a constant speed signal Sc for controlling the constant speed traveling time of the capstan motor. The structure of the capstan motor drive system to which the constant speed signal Sc is input is omitted.

Next, the tape stop position detection device 52 will be described in more detail.

Here, the relationship between the stop position of the magnetic tape and the amplitude of the reproduction pilot signal will be described first.

FIG. 4 shows video tracks 2a, 2 on the magnetic tape 1.
b, 2c, 2d and the loci 4a, 4b, 4c of the magnetic heads 3a, 3b (the magnetic head 3b is not shown) at the lower end, the upper end, and the center when the magnetic tape 1 is stopped. In the figure, arrows A and B indicate the traveling directions of the magnetic tape 1 and the magnetic heads 3a and 3b, respectively. T is the track width of the video tracks 2a-2d,
W is the head width of the magnetic heads 3a and 3b, and P is the track pitch in the longitudinal direction of the magnetic tape 1. Further, pilot signals f1 to f4 are recorded on each of the video tracks 2a to 2d in a multiplexed manner with the video track signal.
The video tracks 2a, 2b, 2c and 2d are recorded by two magnetic heads having different azimuths, and the video tracks 2a and 2c and 2b and 2d are respectively recorded by the same magnetic head. . Also, 5
The reproducing heads a and 5b are both magnetic heads 3 during reproduction.
It is a switching point which is a position where switching is performed between a and 3b.

Here, the stop position of the magnetic tape 1 is set to the magnetic heads 3a, 3
This is represented by the intersection between the running locus 4c at the center of b and the switching point 5a. As shown in the figure, the intersection between the center of the video track 2d 'and the switching point 5a is set to 0, and the direction opposite to the tape running A is set. Determine the coordinate x.
That is, the stop position of the magnetic tape 1 in FIG. 4 is x = 1.
9P, and the video tracks 2a to 2d are periodically recorded with respect to the pilot signal with four tracks as one cycle, so that all stop positions can be represented by x = 0 to 4P.

The frequencies of the pilot signals f1 to f4 are |
f1-f2 || f3-f4 | = fa, | + 1-f4 |
A signal of about 100 KHz to 200 KHz that satisfies the conditions of | f2-f3 | = fb, fa ≠ fb, and fa, f
b is several 10 KHz. For example, f1, f
2, f3, f4 in order of 102KHz, 118KHz, 164
KHz and 148 KHz, in which case fa and fb are 16 KHz and 46 KHz, respectively. The pilot signal f
Since the frequencies 1 to f4 are lower than that of the video signal, the influence of the azimuth effect of the magnetic heads 3a and 3b is small, and the magnetic heads having different azimuths from those at the time of recording can be reproduced.

FIG. 5 (a) is a stop position of the magnetic tape 1 shown in FIG.
That is, in the state of x = 1.9P, the reproduction track width T1, of the video tracks 2a, 2c in one field period.
It shows T3. Here, the reproduction track width means the width of the overlapping portion of the magnetic head and the video track. In the figure, the horizontal axis is the time t normalized by one field time tf, and t / tf = 0 and 1 correspond to the times when the head centers of the magnetic heads 3a and 3b pass through the switching points 5a and 5b, respectively. To do. Also,
In the figure, the head width W of the magnetic heads 3a and 3b is 1.6 times the track width T. Fig. 5 (b) is Fig. 5 (a)
Similarly to the reproduction track width T of the video tracks 2b and 2d
2 and T4 are shown. In the figure, t / t
The values of the reproduction track widths T2 and T4 coincide with each other at the time point tx when f = 0.9, and the magnitude relationship between the two track widths is reversed when t> tx.

FIG. 6 shows the relationship between the value of the stop position x of the magnetic tape 1 and the reproduction track widths T1 and T3 during one field period. Here, the region of 0 <x <P is X1, the region of P ≦ x ≦ 2P is X2, the region of 2P <x <3P is X3, and the region of 3P ≦ x ≦ 4P is X4. As is clear from the figure, the presence / absence of inversion of the magnitude relationship between the reproduction track widths T1 and T3 during one field period is detected,
If there is no reversal, the presence or absence of the reversal and the magnitude relationship between the reproduction track widths T1 and T3 are used. If there is the reversal, the presence or absence of the reversal and the reproduction track width T1, before or after the reversal. By using the magnitude relationship of T3, the stop position x of the magnetic tape 1 is determined to be the regions X1, X2,
It can be determined which of X3 and X4.

FIG. 7 shows the relationship between the stop position x of the magnetic tape and the time point tx at which the magnitude relationship between the reproduction track widths T1 and T3 is reversed. Note that tx is the time when the start point of the field is 0. According to the figure, when the stop position x of the magnetic tape is in the area X1 or X3, the above tx
Can be used to detect the value of the stop position x.

Thus, by utilizing the relationship that the reproduction track width is proportional to the amplitude of the pilot signal included in the reproduction signal of the magnetic head, and the relationship between the stop position of the magnetic tape and the reproduction track width, The stop position can be detected.

FIG. 9 is a schematic block diagram of a tape stop position detecting device 52 for realizing this. In the figure, 30 is a signal amplitude detecting means for separating and detecting the amplitudes of two pilot signals contained in a reproduced signal reproduced by a reproducing means (not shown). Is a balanced modulator, 7a and 7b are bandpass filters having center frequencies fa and fb, and 8a and 8b are detectors. Reference numeral 9 denotes a comparator (signal amplitude comparison means) which compares the amplitudes of two input signals and outputs a high potential (hereinafter abbreviated as “H”) or a low potential (hereinafter abbreviated as “L”) depending on the magnitude. Is a detection signal output means for outputting a signal corresponding to the stop position of the magnetic tape 1,
In the detection signal output means 40, 10, 14 and 20 are pulse generators that generate positive polarity pulses when the input signal rises and falls, and 11, 15 and 21 operate when the input signal to the trigger terminal T rises. Further, when the reset terminal R is "H", the D-flip-flop is in a reset state (the output terminal Q is "L"), 12 and 16 are inverting circuits, 13
Is an exclusive OR circuit, 17, 18, 22 are AND circuits, 1
Reference numeral 9 is an OR circuit, 23 is a triangular wave generator that generates a triangular wave in synchronization with an input signal, and 24 is a sample hold circuit.

Next, the operation will be described.

Here, first, the operation of the tape stop position detecting device 52 will be described with reference to the time chart shown in FIG. This time chart shows an example in which the stop position x of the magnetic tape 1 is x = 2.5P as shown in FIG.

First, it is assumed that the stop position detection command So is issued at time t = t0 as shown in FIG. Before this time, each of the D-flip-flops 11, 15 and 21 is in a reset state and each output terminal Q is "L".

Further, the reproduction signals of the rotary magnetic heads 3a and 3b and the pilot signal f2 are input to the balanced modulator 6, but as shown in FIG. 8, during the reproduction signal of the rotary magnetic head 3a, the pilot signal f2 is added. In addition, pilot signals f1 and f3 are included. Therefore, the balanced modulator 6 to which these signals are input is, as described above, | f1-f2 | = fa, | f2.
A signal including the beat signals whose frequencies are fa and fb, which is −f3 | = fb, is output. The reproduced signal may be obtained by amplifying the signal reproduced by the circuit magnetic heads 3a and 3b and then passing through a filter having the pilot signals f1, f2, f3 and f4 in the pass band.
Then, the band-pass filters 7a and 7b separate and detect beat signals having frequencies fa and fb (hereinafter abbreviated as beat signals fa and fb) from the output of the balanced modulator 6, and the detectors 8a and 8b are detected.
b outputs respective signal levels as shown in FIGS. 10 (c) and 10 (d). The outputs of the wave detectors 8a and 8b are input to the comparator 9 and the magnitude comparison is performed. Now, since the stop position of the magnetic tape 1 is x = 2.5P, FIG.
As shown in (d) and (e), the detectors 8a and 8b output at time t.
= T2, the same value is obtained, and the output of the comparator 9 is inverted at this point. Further, as in this example, when there is an inversion of the magnitude relationship of the signal levels of the beat signals fa and fb within the field period, the output of the comparator 9 is inverted even at the time t = t1 which is the field start point. .

The magnitude of the signal amplitude of the beat signals fa and fb depends on the pilot signal f included in the reproduction signals of the magnetic heads 3a and 3b.
It matches the magnitude of the signal amplitude of 1 and f3.

Next, the pulse generator 10 generates a positive-polarity pulse in synchronization with the rising and falling of the output of the comparator 9, as shown in FIG. 10 (f), and this pulse triggers the D-flip-flop 11. Input to the terminal T. Further, the data terminal D of the D-flip-flop 11 is connected to "H", and by the input of the positive pulse to the trigger terminal T at the time t = t1, the output terminal Q, that is, the output O1 ( The area designating signal) becomes "H" as shown in FIG.

On the other hand, the output of the comparator 9 and the head switching signal Sw for switching the magnetic heads 3a and 3b as shown in FIGS. 10 (e) and 10 (b) are input to the exclusive OR circuit 13, and the output thereof (see FIG. ) Is input to the pulse generator 14, a signal obtained by removing the positive polarity pulse synchronized with the rising and falling of the head switching signal Sw from the signal shown in FIG. can get. The D-flip-flop 15 is triggered by the output of the pulse generator 14, and the output "H" of the comparator 9 input to the data terminal D is output to the output terminal Q thereof (see (j) in the same figure). At this time, since the output terminal Q of the D-flip-flop 11 is also "H" as described above, the output of the AND circuit 18 becomes "H", which causes the output O2 (area designating signal) of the OR circuit 19 to be output. "H" is output (see (k) in the figure).

Further, the pulse generator 20 outputs a positive polarity pulse in synchronization with the rising and falling of the head switching signal Sw as shown in FIG. 10 (l), and its output is the D-flip-flop 2
1 is input to the trigger terminal T. Here, since the data terminal D of the D-flip-flop 21 is connected to its output terminal, the output terminal Q receives the first trigger pulse input after the stop position detection command So is issued as shown in FIG. Then, it becomes "H", and thereafter, "H" and "L" are repeated with two field periods as one cycle. Also, the triangular wave generator 23
Is increased from the potential Va at a constant increase rate (Vb-Va) / tf in synchronization with the rising of the output terminal Q of the D-flip-flop 21 as shown in FIG. Potential is Vb in synchronization with the fall of the output terminal Q of
A signal that decreases from V to Va is output. Then, the sample-hold circuit 24 is an AND which is the logical product of the output of the pulse generator 14 and the output from the output terminal Q of the D-flip-flop 21 as shown in (i) and (m) to (p) of FIG. The output of the triangular wave generator 23 is sampled and held by using the output of the circuit 22 as a sampling pulse, and the potential of the output O3 (distance signal) becomes V. Here, the potential V is V = (Va + Vb) / 2, as is clear from the correspondence with FIG.

The above description is for the case where the tape stop position x is x = 2.5P. However, if the tape stop position x is in the area X3, the tape stop position detection device 52 operates in the same manner and outputs O1.
Is "H", the output O2 is "H", and the potential of the output O3 is Va +.
(X−2P) × (Vb−Va) / P. The ninth
As is apparent from FIGS. 10 and 10, the tape stop position detection device 52 outputs the output O after the detection command So is issued regardless of the timing when the stop position detection command So is issued.
The stop position information is output for 1 and O2 after 1 field time, and for the output O3 after 2 field time.

Next, when the stop position x is in the region X1, the detectors 8a,
8b, each output of the comparator 9 is shown in FIG. 10 (c), (d),
The signal of (e) has a polarity inverted signal, and "L" is output to the output terminal Q of the D-flip-flop 15. "H" is output to the output O1 as in the case of x = 2.5P described above, and the output O2 is "L". Further, the potential of the output O3 becomes Va + x * (Vb-Va) / P.

Further, when the stop position x is in the region X2 or X4, the magnitude relationship between the reproduction track widths T1 and T3, that is, the magnitude relationship between the signal amplitudes of the beat signals fa and fb is not reversed as shown in FIG. -Flip-flop 11
Output terminal Q, that is, the output O1 remains "L". At this time, the output of the comparator 9 is directly output to the output O2, and becomes "H" when x is in the region X2 and "L" when x is in the region X4. At this time, output O3
Is independent of the stop position x.

To summarize the above description, according to the tape stop position detecting device 52, as shown in FIG.
"H" and "L" cause the stop position x to be in the regions X1, X2,
It can be detected which of X3 and X4, and when x is in the regions X1 and X3, the value of x can be detected from the potential of the output O3.

Next, the operation when the slow reproduction and the still reproduction without noise are realized by using the output signal of the tape stop position detection device 52 will be described.

Here, slow reproduction and still reproduction are performed using two heads having the same azimuth as the azimuth of the head recording the tracks 2b and 2d shown in FIGS. As is clear from the figure, the optimum tape stop position x for stably reproducing the video signal is x = 0.5P, 2.
It is 5P. Therefore, the tape stop position detection device 52
If the tape feed control is performed according to the relationship between the feed length 1 of the magnetic tape 1 and tx / tf as shown in FIG. 12 after the tape stop position x is detected by, noiseless slow playback and still playback are realized. it can. In the figure, point E is x = 2.5P, tx / tf shown in FIG.
= 0.5, and in this case, the current tape stop position is the optimum position, so it is indicated that the tape length of 2.0P corresponding to one frame should be sent in the next tape feeding.

This tape feeding control, that is, the operation of controlling the constant speed running time of the capstan motor will be described with reference to the time chart of FIG. Note that FIG. 3 shows the case where the tape stop position x is in the area X1 or X3.

As shown in FIGS. 3 (a) and 3 (e), at time t0, the magnetic tape 1
Is in a stopped state and is accelerated from this state for (t2-t0) time. At this time, the output of the charging / discharging circuit 51 is as shown in FIG.
As shown in, from the low potential VL before the time t0 to (t1-t
It changes to the high potential VH in 0) time. Where both potentials V
L, VH and output signal O3 of the tape stop position detector 52
And the change ranges Va and Vb of VL <Va <Vb <VH, and t1 <t2. Charge / discharge circuit 51
Starts discharging after (t3-t2) time from the acceleration end time t2. During this discharging, the output of the charging / discharging circuit 51 outputs the triangular wave generator 2 of the tape stop position detecting device 52.
The times that coincide with the potentials Vb and Va of 3 are t5 and t, respectively.
7, and the time when it matches the potential V of the output signal O3 is t
If it is 6, the tape 1 is kept at a constant speed ve from time t2 to time t6 as shown in FIGS. Here, the charging / discharging circuit 51 is set so as to satisfy (t7−5t) · ve = P, and therefore, the potential V of the output signal O3 is set.
Is changed in the range of Vb to Va, the time (t6
-T5) changes in the range of 0 to (t7-t5). That is, the tape length sent from time t5 to t6 is 0 to
It will change between P.

Further, in this case, acceleration running at time t0 to t2, time t2 to t2
The tape length (shaded area in the figure) sent by the constant speed running of 5t and the braking at the times t6 to t8 is set to be 1.5P. Therefore, this and the controlled tape lengths O to P are set. Thus, when the stop position x is in the region X1 or X3, the magnetic tape 1 can be sent to the optimum stop position according to the relationship between the stop position and the tape feed length shown in FIG. Here, in the tape speed shown in FIG. 3 (e), the tape feed length is obtained by integrating the tape speed with time.

The above is the case where the stop position x is in the areas X1 and X3, but the operation when the stop position x is in the areas X2 and X4 will be described below. At this time, the output signal O of the tape stop position detection device 52
1 is "L", and the switch circuit 56 receiving this outputs the output of the one-shot circuit 55 as the constant speed signal Sc. The one-shot circuit 55 is shown in FIGS. 3 (a) and (d).
As shown in, the signal that becomes "H" only during the period of time (t4-t2) is output in synchronization with the rising of the acceleration signal Sα. Therefore, in this case, the magnetic tape 1 is (t2-t0).
Time acceleration, (t4-t2) constant speed, (t8-t
6) The braking is controlled during the time (between times t4 and t8 ') (shown by the one-dot chain line in FIG. 3 (e)). Here, the falling time point t4 of the one-shot circuit 55 is (t5-t
4) -ve = 0.5P is set to satisfy,
Therefore, the tape feed length in this case can be set to 1P in combination with the hatched portion in FIG. 3 (e) being set to 1.5P as described above. As a result, when the tape stop position x is in the area X2 or X4 at the start of slow reproduction or still reproduction, the tape 1 is first fed by 1P to position the tape 1 in the area X1 or 3, and the next tape The magnetic tape 1 can be fed from the feeding to the optimum tape stop position as described above.

In this embodiment, the tape stop position detection device 52 detects the tape stop position, and the constant speed running time of the tape is controlled based on this information to optimize the tape stop for slow reproduction and still reproduction. Since the tape is fed to the position, it is possible to very easily obtain the slow reproduction image and the still reproduction image without noise, without requiring any adjustment work by the user.

In the above embodiment, in the tape stop position detecting device 52, the signal amplitudes of the pilot signals f1 and f3 included in the reproduction signals of the magnetic heads 3a and 3b are changed to the pilot signal f2.
However, the same detection can be performed by using the pilot signal f4 instead of the pilot signal f2, and further the pilot signals f2 and f4 can be detected.
Even if a signal different from the above is used, it can be similarly detected by appropriately selecting the center frequencies of the bandpass filters 7a and 7b. Further, the signal amplitudes of the pilot signals f1 and f3 can be obtained by inputting the reproduction signals of the magnetic heads 3a and 3b into band filters whose center frequencies are f1 and f3, respectively, and detecting their outputs. Further, in the tape stop position detecting device 52 of the above-mentioned embodiment, the signal amplitudes of the pilot signals f1 and f3 are compared, but the same detection can be performed by using the pilot signals f2 and f4. Needless to say.

Further, in the above embodiment, the tape stop position detecting device 52
Triangle wave generator 23, sample hold circuit 2
4, the analog signal processing is adopted in the charging / discharging circuit 51 and the like, but it goes without saying that the same function can be realized by digital signal processing using a clock signal and a counter.

Further, the tape feeding direction may be forward or reverse, and therefore, not only in the normal slow reproduction, but also in the reverse slow reproduction, the same effect as that of the above-described embodiment is obtained.

〔The invention's effect〕

As described above, according to the present invention, the first, second, third and fourth pilot signals having different frequencies, which are generated in synchronization with the rotation of the rotary magnetic head, are multiplexed to the video signal to be sequentially recorded. In a magnetic recording / reproducing apparatus for recording and reproducing data, a magnetic tape and at least one of slow reproducing means or still reproducing means for performing a series of running operations of acceleration, constant speed, braking and stopping on a magnetic tape based on a command signal. Signal amplitude detecting means for separating and detecting the amplitudes of the two pilot signals of the first, third or second and fourth included in the reproduced signal from the signal, and signal amplitude comparing means for comparing the amplitudes of the two pilot signals, The output of the signal amplitude comparison means and the switching signal of the rotary magnetic head are input, and the two pilot signals are input in one field period defined by the switching signal. Depending on whether the amplitude magnitude relationship is inverted or not, and if the amplitude magnitude relationship is not reversed, the magnetic tape is determined by the magnitude relationship between the amplitudes, and if there is any inversion, depending on the magnitude relationship before or after the inversion. The stop position is determined by a means for outputting a region indicating signal indicating which region the stop position is in which one cycle is divided into four, and the head switch position of the rotary head switch signal and the reversal position of the magnitude relationship of the amplitude. Has a means for outputting a distance signal indicating how far it is from one end of the four-divided area, and when the magnetic tape is stopped, the pilot signal reproduced from the magnetic tape is separated and extracted. The tape stop position detecting means for detecting the tape stop position by the reproduction pilot signal, and the tape by the command signal and the output of the tape stop position detecting means. When the stop position is in a region other than the predetermined two regions in the four regions, the constant speed running time of the magnetic tape is set to a length such that the stop position of the tape reaches the predetermined two regions. The tape stop position is detected from the pilot signal included in the reproduction signal by providing the traveling time determining means for determining the constant speed traveling time during the reproduction and the still reproduction, and the tape feeding time during the intermittent feeding is detected according to the result. Since the constant speed travel time is determined, there is an effect that good slow reproduction and still reproduction can be realized without adjustment.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a conventional tape running control, FIG. 2 is a schematic configuration diagram of a VTR according to an embodiment of the present invention, and FIG. 3 is a time chart diagram for explaining the operation of the VTR. FIG. 4 is a diagram showing the relationship between the video track of the magnetic tape and the locus of the magnetic head. FIG. 5 is a diagram showing the reproduction track width when the magnetic tape is reproduced in a stopped state.
FIG. 7 is a diagram showing the relationship between the stop position of the magnetic tape and the reproduction track width. FIG. 7 is a diagram showing the relationship at the time when the relationship between the stop position of the magnetic tape and the reproduction track width is reversed. FIG. 9 is a diagram for explaining the operation of a tape stop position detection device for a VTR according to an embodiment of the invention, FIG. 9 is a configuration diagram of the device, and FIG. 10 is a time chart diagram for explaining the operation. Is a diagram showing the relationship between the output of the tape stop position detecting device and the tape stop position, and FIG. 12 is a diagram showing the relationship between the stop position of the magnetic tape and the feed length. 1 ... Magnetic tape, 2 ... Video track, 3a ... Magnetic head (reproducing means), 9 ... Comparator (signal amplitude comparing means), 30 ... Signal amplitude detecting means, 40 ... Detection signal outputting means, 52 ...... Tape stop position detection device, 60
...... Means for controlling running time. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A set of four video tracks of a magnetic tape is set as one cycle, and four pilot signals of first, second, third and fourth frequencies different from each other are provided together with a video signal on each of the four video tracks. In a magnetic recording / reproducing device that sequentially records and reproduces with multiple rotating magnetic heads, acceleration, constant speed, braking,
At least one of the slow reproducing means or the still reproducing means for performing a series of running operation of stop, and the amplitudes of the two pilot signals of the first, third or second and fourth contained in the reproduction signal from the magnetic tape The signal amplitude detecting means for separate detection, the signal amplitude comparing means for comparing the amplitudes of the two pilot signals, the output of the signal amplitude comparing means and the switching signal of the rotary magnetic head are input, and are defined by the switching signal. Whether there is a reversal of the magnitude relationship between the amplitudes of the two pilot signals, and if there is no reversal of the magnitude relationship between the amplitudes in one field period, the magnitude relationship between the amplitudes is detected. If there is an inversion, before the reversal. Alternatively, an area designating signal indicating which area of the magnetic tape stop position is divided into four is output depending on the magnitude relationship of the amplitude at a later point in time. And the head switching position of the rotary head switching signal and the reversal position of the magnitude relationship of the amplitude, a distance signal indicating how far the stop position is from one end of the four-divided area. A tape stop position detecting means for separating and extracting the pilot signal reproduced from the magnetic tape when the magnetic tape is stopped, and detecting the tape stop position by the reproduced pilot signal; and the command signal. According to the output of the tape stop position detection means, when the tape stop position is in an area other than the predetermined two areas of the four areas, the constant speed running time of the magnetic tape is determined by the tape stop position. A traveling time determining means for determining a constant speed traveling time at the time of the slow reproduction and the still reproduction is provided so as to have a length that comes in two areas. Magnetic recording / reproducing device.