JPS634452A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a screen with less noise burrs and easier to watch not only during the transfer but also immediately after the transfer by performing a tracking control once at the 3rd speed of the medium thereof in case of the change from a 1st speed to a 2nd speed being commanded. CONSTITUTION:A motor 29 to travel a magnetic tape, a circuit 22 to control the rotation of the motor, a generation circuit 20 to generate a reference pilot signal, a forming circuit to form a tracking error signal from a reproduction pilot signal reproduced from the inclined track of a magnetic tape and reference pilot signal, the 1st and 2nd rotary heads 2 of different azimuth apart at 180 deg. each other and a 3rd rotary head 2 for auxiliary of the same azimuth as that of a 1st rotary head are equipped with. The control circuit 22 controls the motor 29 and when the running speed of the magnetic tape is changed from the 1st speed to the 2nd speed, the running speed of the magnetic tape is controlled corresponding to the tracking error signal obtd. in at least one 3rd speed between the 1st speed and 2nd speed. During this time, the signal is reproduced by the 1st or 3rd rotary head.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device typified by a video tape recorder.

[Summary of the invention]

In the present invention, when the running speed of the magnetic tape is switched from the first speed to the second speed, tracking control is also performed at an intermediate speed.

[Conventional technology]

In conventional video tape recorders, a control (CTL) signal is recorded using a fixed head in the longitudinal direction of the magnetic tape, and the phase of the playback signal and the head switching pulse (H3WP) that switches the rotating head is compared and the control (CTL) signal is recorded. Tracking control was performed in response to the error signal. However, this method requires a fixed head that is not necessary for recording and reproducing the original information, so for example
In millimeter video tape recorders and the like, tracking control is performed using so-called four-frequency pilot signals.

In this system, pX valve 6.5fm, Pg gradient 7-
5 f m -P a valve 10.5 fg, P, given 9.
The pilot signals of each frequency of 5f11 are sequentially frequency-multiplexed recorded with respect to the video signal on each inclined track.
, is the horizontal synchronization frequency), the frequency difference with the adjacent track is fl or 3 fl, and a tracking error signal is generated from the level difference between the two.

[Problem that the invention seeks to solve]

By the way, in the cue or review mode, the magnetic tape is run at a high speed that is approximately an integral multiple of that of normal recording and reproduction to reproduce recorded signals. Tracking control has traditionally been performed while in cue or review mode, but tracking control is also required in transitional states such as transitioning from normal playback mode to cue or review mode, or in the opposite direction. was not carried out.

Therefore, the conventional apparatus had the disadvantage that the image was distorted during that time.

Especially when transitioning from normal playback mode or cue mode to review mode, or vice versa,
From the point where the running direction of the magnetic tape is reversed, it is necessary to switch various mechanisms such as tape tension and winding drive system in the stop (still) mode during that time.
The time required for this is approximately several hundred milliseconds or more, which cannot necessarily be ignored. Furthermore, if the tracking state is disturbed during the transition, the time required until the tracking state becomes strong after the transition is completed becomes longer.

Such drawbacks become particularly noticeable when the width of the rotating head is equal to or narrower than the track width, or when a guard band is present.

[Means for solving problems]

The present invention provides a magnetic recording and reproducing device including: a motor for running a magnetic tape; a control circuit for controlling rotation of the motor;
A generation circuit that generates a reference pilot signal, a generation circuit that generates a tracking error signal from a reproduced pilot signal reproduced from an inclined track of a magnetic tape and a reference pilot signal, and comprising a second rotating head and an auxiliary third rotating head having the same azimuth as the first rotating head;
Tracking obtained at at least one third speed between the first speed and the second speed when the control circuit controls the motor and switches the running speed of the magnetic tape from the first speed to the second speed. The running state of the magnetic tape is controlled in response to the error signal, and the first or third
The signal is reproduced by a rotating head.

[Operation] When a command is given to switch from the first speed to the second speed, tracking control is once performed at a third speed intermediate therebetween.

〔Example〕

FIG. 1 is a block diagram of a magnetic recording/reproducing apparatus according to the present invention. In the figure, reference numeral 1 denotes a magnetic tape, on which information is recorded and reproduced by a rotary head 2. The rotating heads 2 are mutually 1
1 for recording and reproducing, separated by 80 degrees and having different azimuths.
Pair of rotating heads A and B, and auxiliary rotating head A for playback only
′. The auxiliary rotary head A' has the same azimuth as the rotary head A, and is arranged near the rotary head B so as to trace the same track as the rotary head A during special reproduction of stills, etc.

During normal reproduction, the signal reproduced by the rotary head A or B is transferred to the rotary transformer 3. The signals are alternately selected via switches 4.6 and output to a CRT or the like via a demodulation circuit (not shown).

One of the reproduced signals from the rotary head A or B is selected by a switch 5, and is supplied to a low-pass filter 8 via an amplifier circuit 7. The low-pass filter 8 separates and extracts the reproduced pilot signal, which is a low frequency component, from the reproduced signal. For example, a frequency conversion circuit 9 consisting of a balanced modulator or the like mixes the reproduced pilot signal and the reference pilot signal generated by the generation circuit 18. This mixed output has frequencies f, and 3
It contains a beat component of fN, and the former is detected by the band-pass filter 10 and the latter by the band-pass filter 11, respectively. The levels of these beat components are detected by the detection circuit 12. ．． 13, and the differential amplifier circuit 1
4, each difference is calculated.

As shown in FIG. 2, pilot signals P to P are sequentially and cyclically recorded in each inclined track T8 to T4 in that order. In normal playback mode, generator circuit 1
8 generates a pilot signal having the same frequency as the pilot signal recorded on the inclined track being traced. Therefore, for example, when the rotary head A traces the inclined track sub-work, when it is in the position shown in FIG. The level of the beat component (''=fm) due to the reproduced pilot signal P, (47, 5f,) as a talk component and the reproduced pilot signal P, , (: 9.5fw) and the beat component (
The levels of the valves 3fw) are approximately equal. - Same figure on the right (b)
Or, as shown in (c), when the trace position shifts to the right or left, the level of the beat component of f1 or the beat component of 3f becomes larger than the other. Therefore, the output of the differential amplifier circuit 14 is.

Negative when the trace locus moves to the right, positive when the trace moves to the left,
It becomes zero when it is correct. When the rotating head B traces the track T2, the reference pilot signal is P, (phantom 7.
5f irises), so the frequency of the beat component due to the pilot signal P3 (no 10.5fN) of the truck T3 on the right becomes 3f, and the frequency of the beat component due to the pilot signal P of the truck T3 on the left (:6.5f++). The frequency of the beat component is fl.

In this way, the polarity of the output signal of the differential amplifier circuit 14 and the direction of deviation of the trace locus are reversed for each field. Therefore, switch 15 is switched to the opposite side for each field.
By taking out the inverted signal or the non-inverted signal by the inverter 16, the polarity of the signal and the direction of deviation of the trace locus are made continuous in each field. The signal generated by the above-described generation circuit and output from the switch 15 becomes a tracking error signal.

This tracking error signal is sample hold circuit 1
7. The tracking error signal is supplied to the drive circuit 23 via the adder circuit 21, and the drive circuit 23 controls the motor 29 that rotates the capstan 24 and therefore the magnetic tape 1 in response to this tracking error signal.

Next, Section 7 describes the effect of transitioning from the normal playback mode to the cue mode in which the video signal is played back by running the magnetic tape at approximately five times the speed of normal recording and playback.
This will be explained with reference to the timing chart shown in the figure.

For example, when the control circuit 22 consisting of a microcomputer or the like is commanded to shift from the normal playback mode to the cue mode (Fig. 7(b)), the control circuit 22 controls the head switching pulse (Fig. 7(a)) that arrives thereafter. This command is latched at the edge timing of )). Then, when a predetermined time t1 has elapsed from the edge of the field (F), the magnification of the running speed of the magnetic tape relative to the normal speed is increased by 1 to 2 (FIG. 7(C)).

When the control circuit 22 inputs the magnification update signal, the generation circuit 20 sends a control signal (
7(d)) is output, and the immediately preceding tracking error signal is held. This hold state continues until a predetermined time t2 has elapsed from the start point of the next field (F2), and after the elapse of time t2, the state is changed to the sampling state for a time t (FIG. 7(d)). The above operations are repeated in the same manner until the magnification is further updated.

The frequency dividing circuit 26 is set to a frequency dividing ratio corresponding to the running speed of the magnetic tape (multiplying the normal recording/reproducing speed). Therefore, when the magnification becomes 2, the frequency division ratio of the pulses input from the frequency generator (FG) built into the motor 29 via the amplifier circuit 25 is switched from 1 to 2. As a result, the frequency of the pulses output by the frequency dividing circuit 26 becomes 1/2 that of normal reproduction. The detection circuit 27 compares this frequency with the frequency of a predetermined reference signal and outputs an error signal.

Since the frequency of the reference signal is set so that the error signal is zero during normal reproduction, an error signal (FIG. 7(k)) that increases the speed of the magnetic tape is output at this time. This error signal is input to the drive circuit 23 via the addition circuit 21, so the motor 29 rotates the capstan 24 at approximately twice the normal speed.

When the selection circuit 19 receives a magnification update signal from the control circuit 22, it latches a new magnification at the timing of the edge of the head switching pulse that arrives thereafter, and changes the generation pattern of the reference pilot signal in accordance with the latched magnification. Switch.

That is, the reference pilot signal (FIG. 7(g)) generated and outputted by the generation circuit 18 is
The values are changed and set as shown in Table 1 in response to the bit control signals (FIGS. 7(e) and 7(f)).

One of the occurrence patterns shown in Table 1 and Table 2 is sequentially selected (n is an integer in the table).

The reason for this becomes clear from FIG. In FIG. 11, the horizontal axis represents time in units of fields, and the vertical axis represents the amount of tape movement in units of fields. Figures (a) to (e) show trace trajectories when the magnification is changed from 1 to 5. The magnification is 1 (4n
+1), the reproduced pilot signal of approximately the middle of each field changes sequentially, for example, in the positive direction, such as P1→P2→P3→P4→P. The magnification is 2 (4
n+2), Pyu → P3 → P1 → P, → P2, and 4
Two of the two pilot signals are played back alternately.

Table 2 When the magnification is 3 (4n+3), P1 → P4 → P, → P2
→ P2 and the four pilot signals change sequentially in the opposite direction, and when the magnification is 4 (4n), P engineering → P engineering → P, → P engineering → P□, and one of the four pilot signals are played continuously. When the magnification is 5 (4n+1), the magnification is 1
This is the same as when the magnification is 6 or more, and the pattern is the same as any of the four patterns below. Therefore, if the reference pilot signal is generated as shown in Table 2 in accordance with the magnification, a correct tracking error signal can be obtained approximately in the middle of each field.

Based on this principle, when the magnification is set to 2, the generation circuit 1
8 is the next field (F2) of the acceleration field (F engineering).
), a sampling pulse with a width of time t3 (time t2 is set so as to be) is output (FIG. 7(d)), so the tracking error signal output from the switch 15 is (FIG. 7(1)) is sampled and held by the sample and hold circuit 17 (FIG. 7(m)). This sampled and held tracking error signal is added to the signal from the detection circuit 27 (FIG. 7(k)) by the addition circuit 21, and is supplied to the drive circuit 23. Frequency servo is performed by the output signal of the detection circuit 27, and phase servo is performed by the tracking error signal.The motor 29 is controlled so that the acceleration caused by increasing the magnification by 1 is completed in the first field (F). The servo loop has been adjusted and set.

Also, the time t is set in this manner. In other words, the time t is (N+
It is set so that a tape movement amount of N, -1)/2 fields (1,5 fields) can be obtained. Therefore, in the next field (F2), the output signal of the detection circuit 27 is almost zero.

In the third field (F3), after a predetermined time t1 has elapsed from the first edge of the switching pulse, the multiplication factor is further increased by one to three. Next field (F,
), the generation pattern of the reference pilot signal is changed, and the running error signal is sampled and held approximately in the middle. Similarly, the magnification becomes 4 in the fifth field (Fs), the tracking error signal is sampled and held in the sixth field (F6), the magnification becomes 5 in the seventh field (Fl), and the magnification becomes 5 in the seventh field (Fl). The tracking error signal is sampled and held in the field. With the above operations, the speed for cue playback has been reached, so the subsequent 9th field (F3)
, the tenth field (F, .), etc., the tracking error signal is sampled and held approximately at the center of each field, and the running state of the magnetic tape 1 is controlled in accordance with the held value.

The tape running locus for each field in the above operation is illustrated in FIG. 3. In this figure as well, the horizontal axis represents time in units of fields, and the vertical axis represents the amount of tape movement in units of fields.

By the way, when the magnification is sequentially changed from 1 to 5 by 1, the rotating heads A, B, and A' are respectively shown in FIG. 7 (n), (0),
A signal (RF multiplied signal) as shown in (p) is reproduced and output.

When the output from the rotary head B is an even magnification, the level at approximately the center of each field decreases and noise increases.

Therefore, the selection circuit 28 latches the magnification at the timing of the edge of the head switching pulse, and switches the switch 6 to the lower side in the figure when the latched magnification is an even number, and to the upper side when it is an odd number (Fig. 7 (9) )). Therefore, when the magnification is an odd number, the reproduction signals of the rotary heads A and B are output, and when the magnification is an even number, the reproduction signals of the rotary heads A and A' are respectively output (Fig. 7 (r)). The position of the noise bar on the screen obtained by demodulating the reproduced signal moves sequentially in the vertical direction during the mode transition, and after the transition is completed, it is fixed at a predetermined position to become an easy-to-read screen (FIG. 7(S)).

During the above operation, the rotation direction of the motor 29 is set in the positive direction by the control signals (Fig. 7 (h), (i), (j)) output from the control circuit 22 to the drive circuit 23, and the brake pulse is There is no output, and the capstan 24 remains rotating.

Next, the case of switching from the cue mode to the normal playback mode will be described. The timing chart thereof is shown in FIG. 8, and the tape running trajectory in that case is shown in FIG. 4.

Even in this case, when a command to shift from the cue mode to the normal playback mode (FIG. 8(b)) is input, the control circuit 22 controls the edge of the head switching pulse (FIG. 8(a)) that arrives thereafter. Latch this command at the timing. After that, when a predetermined time t4 has elapsed, the magnification is decreased by 1 to 4 (FIG. 8(C)). Therefore, the division ratio of the frequency dividing circuit 26 is updated from 5 to 4, and the detection circuit 27 outputs an error signal (FIG. 8(k)). At the same time, the drive circuit 23 receives a pulse (see FIG.
h)) and a brake pulse (FIG. 8(i)) are output.

As a result, motor 2 in the deceleration field (F,,)
9 (capstan 24) is reduced to four times the speed of normal playback.

In this case, at time t9,t, the magnification before update is N+1,
When the updated magnification is N, the deceleration field (Fyu,
) is appropriately selected so that a tape movement amount of (N+N+1)/2 fields (4, 5 fields) can be obtained.

A predetermined time t from the first edge of the next field (F,)
2 (approximately at the center of the field (Fi,)), a sampling pulse of a predetermined width t3 (Fig. 8(d)
)) is output, and the tracking error signal at that time (
Figure 8 (1)) is sampled and held (Figure 8 (m
)). At this time, based on Table 2, the same reference pilot signal P is output continuously (Fig. 8 (g)), so
A correct tracking error signal can be obtained.

In this case as well, the reproduction signal of the rotary head A (Fig. 8 (
n)), the reproduction signal of rotary head B when the magnification is an odd number (Fig. 8 (0)), and the reproduction signal of rotary head A' when the magnification is an even number (Fig. 8 (p)). is output (FIG. 8(r)), and an easy-to-see image (FIG. 8(s)) can be obtained.

On the other hand, a timing chart for transitioning from the still mode to the review mode is shown in FIG. Further, the tape running locus at this time is as shown in FIG.

Command to transition from still mode to review mode (9th
9(b)) is input, the control circuit 22 latches this command at the edge timing of the head switching pulse (FIG. 9(a)) that arrives thereafter, and immediately sends a tracking error signal (FIG. 9(1)). )) (Fig. 9(d), (m)).

Then, when a predetermined time t6 has elapsed, the rotation of the capstan 24 is started (FIG. 9(j)), and
The multiplier is increased by 1. In the review mode, the magnetic tape is run in the opposite direction at five times the speed, so if the magnification at that time is -5, the magnification is changed from 0 to -1 (FIG. 9(c)).

Tape running trajectories when the magnetic tape is run in the opposite direction at speeds of magnifications (-1) to (-5) are shown in FIGS. 12(a) to (e), respectively. It can be seen from the figure that even in this case, the reference pilot signal generation pattern may be any of the patterns shown in Table 2. However, since the polarity of the tracking error signal is opposite to that when traveling in the forward direction, it is necessary to make the reference pilot signals P1, P4, Pl, and P2 correspond to the reproduced pilot signals P, Pl, and P4, respectively. be.

Therefore, the frequency dividing ratio of the frequency dividing circuit 26 is set to 1 corresponding to the magnification (-1), and after acceleration in the opposite direction is performed in the acceleration field (F, ,), the next field (Fi2) is When the sampling pulse (FIG. 9(d)) is generated approximately at the center, the reference pilot signal P2 is supplied in response to the reproduced pilot signal P4 (FIG. 9(g)).

Hereinafter, similarly to the case described above, the magnification is updated one by one until the magnification reaches -5.

On the other hand, the timing chart when shifting from the review mode to the still mode is as shown in FIG. 10, and the tape running locus at this time is as shown in FIG.

In this case, in the deceleration field (Fa
)) is input, this command is latched at the edge timing of the head switching pulse (FIG. 10(a)) that arrives thereafter.

When the predetermined time t7 has elapsed since then, the predetermined time t
, the rotational direction of the motor 29 is reversed (FIG. 10(h)), and a brake pulse is output (the first
0(i)), and at this time, the tracking error signal ((1) in FIG. 10) is sampled and held approximately in the middle of the 0th-order field (F32) where the magnification is updated from -5 to -4. (Figure 10(d) 1.(m)). At this time, the reference pilot signal P1 is continuously supplied.

Thereafter, the magnification is updated one by one until the magnification reaches O, as in the case described above.

In the above embodiment, the FG output from the motor 29
Although the pulse is frequency-divided, the reference pulse signal may be multiplied. In short, it is sufficient to provide a magnification circuit that makes either the FG pulse or the reference pulse correspond to the magnification.
Further, the update cycle of the tape speed magnification can be made longer than every two fields, and the length can be changed depending on the magnification.

〔effect〕

As described above, the present invention provides a magnetic recording and reproducing apparatus that includes a motor for running a magnetic tape, a control circuit for controlling the rotation of the motor, a generation circuit for generating a reference pilot signal,
a generating circuit that generates a tracking error signal from a reproduced pilot signal reproduced from an inclined track of a magnetic tape and a reference pilot signal; first and second rotary heads having different azimuths separated from each other by 180 degrees; A third rotating head for auxiliary use having the same azimuth as the rotating head is provided, and when the control circuit controls the motor and switches the running speed of the magnetic tape from the first speed to the second speed,
The running state of the magnetic tape is controlled in response to a tracking error signal obtained at at least one third speed between the first speed and the second speed, and during that time, the first or third rotary head generates a signal. Since the tape is played back, tracking control can be performed even during the transition to a different tape speed, and an easier-to-read screen with fewer noise bars can be obtained not only during the transition but also immediately after the transition.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the magnetic recording/reproducing apparatus of the present invention, and FIG.
The figure is an explanatory diagram of the tracking state of the inclined track, Figures 3 to 6 are explanatory diagrams of the tape running trajectory, Figures 7 to 10 are the timing charts, and Figures 11 and 12 are the double speed. FIG. 3 is an explanatory diagram of a tape running trajectory during playback. 1...Magnetic tape 2...Rotary head 3...Rotary transformer 8...Low pass filter 9...Frequency conversion circuit 10.11...Band pass filter 12.13...Detection circuit 14. ... Differential amplifier circuit 17 ... Sample hold circuit 18 ... Generation circuit 19 ... Selection circuit 20 ... Generation circuit 21 ... Addition circuit 22 ... Control circuit 23 ... Drive circuit 24 ... Capstan 26 ... Frequency dividing circuit 27 ... Detection circuit 28 ... Selection circuit 29 ... Motor or higher

Claims (1)

[Claims] A motor for running a magnetic tape, a control circuit for controlling the rotation of the motor, a generation circuit for generating a reference pilot signal, a reproduced pilot signal reproduced from an inclined track of the magnetic tape, and a control circuit for controlling the rotation of the motor. a generation circuit that generates a tracking error signal from a reference pilot signal;
first and second rotary heads of different azimuths spaced apart and an auxiliary third rotary head of the same azimuth as the first rotary head; the control circuit controls the motor; When switching the running speed of the magnetic tape from the first speed to the second speed, the tracking error signal corresponds to the tracking error signal obtained at at least one third speed between the first speed and the second speed. A magnetic recording/reproducing apparatus characterized in that the running state of the magnetic tape is controlled by the magnetic tape, and during this time, signals are reproduced by the first or third rotary head.