JPS60257686A - Rotary head type reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a rotary head type reproducing device, and more particularly, to a rotary head type reproducing device, which uses a pair of shifting means to move recording tracks formed at a predetermined pitch on a recording medium transported by a transporting means. This invention relates to a rotary head-type reproducing machine that reproduces a recorded name by sequentially tracing it with a pair of rotary heads that are displaceable in a direction intersecting the rotational surface of the rotary head. The present invention relates to control of the pair of shifting means when performing reproduction at a speed different from the recording speed, such as reproduction, low-speed reproduction, and reverse reproduction.

<Description of Prior Art> In a rotary head type writer/writer device such as V1'R, playback is performed at an arbitrary speed different from the recording speed, such as stray playback, low-speed playback (including static playback), and reverse playback. Prevents the occurrence of noise bars and provides stable and clear illumination during special playback.
! In order to be able to reproduce the Ii image, it is necessary to ensure that the reproduction head accurately traces one recording track in each scan field.

Conventionally, as one means of realizing such a function,
A pattern signal generator is provided that generates a meandering pattern signal in the distance from the scanning locus of the playback head to the recording track on the tape at a given tape running speed, and the pattern signal obtained from this pattern signal generator is Yo),
A method is known in which a displacement means such as an electro-mechanical transducer (for example, a bimorph element) for displacing the reproducing head in a direction perpendicular to its rotation plane is controlled.

FIG. 1 is a diagram showing the conventional VTI of this yuzu (VTI), and in particular is a diagram showing a schematic configuration of the main parts related to the present invention.
In the figure, 1 is a magnetic tape as a recording medium, and 2A and 2B are magnetic heads for reproduction, which are provided so as to have the same azimuth angle and face each other at 180 degrees. It is attached to the free ends of electro-mechanical transducers 3A and 3B such as. The converting elements 3A and 3B are attached to a rotating member 4 at their tail ends, and the rotating member 4 is rotated by a head rotating motor 5 as shown by the arrow in the figure. Although omitted in the figure,
As is well known, the heads 2A and 2B are rotated while protruding from a slit between a pair of tape guide drums, and the tape 1 is tilted over a range of 180 degrees or more with respect to the drums. It can be wrapped around. 6
is a rotational phase detector for detecting the rotational phase of heads 28 and 2B, and the signal from this detector 6 is used as a head switching signal (hereinafter referred to as H5W signal) and is also attached to the head motor control circuit. Based on the output of the detector 6, the control circuit 7 controls the head motor 5 through the head motor drive circuit 8 so as to rotate the hects 2A and 2B in a predetermined phase and at a predetermined rotational speed. Reference numeral 9 denotes a fixed head (hereinafter referred to as "CTL head") for reproducing control signals (hereinafter referred to as "CTL signal") for reproducing control signals (hereinafter referred to as "CTL signals") recorded at intervals of one frame in the longitudinal direction at the bottom of the tape;
O is a capstan which constitutes a transport means for transporting the tape 1 in the longitudinal direction in cooperation with a pinch roller (not shown), 11 is a capstan motor for rotating the capstan 10, and 12 is a capstan. A frequency signal generator 13 generates a frequency signal corresponding to 100 rotations (hereinafter referred to as capstan FG signal) based on the CTL signal from the CTL head 9 and the capstan FG signal from the frequency i signal generator 12. The capstan O motor 1 rotates the capstan 10 in a predetermined phase and at a predetermined rotation speed.
1 through the cab's tongue motor drive circuit 14. 15 is the H8W signal from the rotational phase detector 6 and the C from the CTL head 9.
Capstan F from TL signal and frequency signal generator 12
During playback at any speed (including stationary and reverse rotation) based on the G signal, the heads 2A and 2
a turn signal generating circuit for generating pattern signals for the electro-mechanical converters 3A and 3B so that each of the signals B traces one recording track on the tape 1;
Reference numeral 16 denotes a conversion element drive circuit for driving the conversion elements 3A and 3B at 1iA# based on the pattern signal from the turn signal generation circuit 15.

FIG. 2 shows an example of the configuration of the pattern signal generation circuit 15. In the figure, input terminals 17, 18 and 19 are connected to capstans F"G from the frequency signal generator 12 mentioned above, respectively.
The CTL signal from the CTL head 9 and the H8W signal from the rotational phase detector 6 are input manually. 20 is terminal 17
A binary counter 21#-i is designed to count the capstan FG signal input to the terminal 18 and to be reset by the CTL signal input manually to the terminal 18.
Based on the HSW signal input to terminal 19, the corresponding H8W
A timing signal generation circuit 22 generates a timing signal synchronized with the timing signal 21, and the output of the counter 20 is reset as preset data PD by the timing signal from the timing signal generation circuit 21.
7 is a presettable binary counter that counts the input capstan FG signal; 23 is a D/A converter that D/A converts the output of the presettable counter 22 and outputs a first pattern signal; 25 is an adder, 2
6 is an output terminal for outputting a conversion element control pattern signal (drive signal) which is the output of the adder 25; 27 is an oscillator that generates a clock pulse of a predetermined frequency; 21 is a clock pulse generated by the oscillator 27; 29 is a counter 2 which is reset by the timing signal from the timing signal generation circuit 21.
This is a D/A converter that performs D/A conversion of the output of 8. That is, the output of the counter 22 is related to the transport speed of the recording medium, and the output of the counter 28 is independent of the transport speed of the recording medium.I)
, D/ converter 29 outputs a fixed pattern signal (second pattern signal) for still reproduction.

Next, regarding the operation of the VTR configured as described above during special playback,
In particular, the operation of the pattern signal generation circuit shown in FIG. 2 will be explained with reference to FIGS. 3 and 4. In addition, in Figure 3 (
ψ~(g) is the CTL signal during 1.5x playback, the second
The output of the illustrated counter 2o, the output of the presettable counter 22 (or D/A converter 23), and the adder 25
Figure 4 (4) and (
B) shows the relationship between the center locus of the scanning of the heads 2 and 2B with respect to the center locus of the recording track on the tape 1 during still playback and 1.5x speed playback, respectively.

First, as the head motor 5 rotates the heads 2 and 2B, the rotational phase detector 6 outputs the H8W signal as shown in FIG. As shown in FIG. 3(b), the timing signal generating circuit 21 in FIG.
A timing signal synchronized with each rising edge and falling edge of the signal is output. Then, based on this timing signal, the D/A
The converter 29 moves the heads 2A and 2B from O to 11 tracks within the scanning of 1 field as shown in FIG. 3(C).
A stay pattern signal for continuously varying up to a pitch (hereinafter referred to as TP) is output.

Now, the field signal of one recording track recorded by the recording head having the same azimuth angle as the reproduction heads 2A and 2B is alternately reproduced by the two heads and 2B. When trying to perform stale reproduction, the relationship between the center locus of scanning of heads 2A and 2B with respect to the recording track on tape l at this time is the fourth
The result is as shown in Figure (4). That is, in FIG. 4 (8), the solid line indicates the center locus of the recording track of the field signal recorded by the recording head having the same azimuth angle as the heads 2A and 2B, and the broken line indicates the center locus of the recording track of the field signal recorded by the recording head having the same azimuth angle as the heads 2A and 2B. The white arrows indicate the center locus of the recording track of the field signal recorded once by the recording head with corners, and the white arrows indicate the center locus of the scanning of the heads 2A and 2B.
L indicates the recording locus of the CTL signal (this is the same as in Fig. 4), and as shown in the figure, the head 2
The center trajectory (hereinafter referred to as head trajectory) C of the scanning of the person and 2B is the track trajectory of the truck that momentarily contacts the starting end and left side of the track trajectory a with respect to the center trajectory (hereinafter referred to as track trajectory) a of the track to be reproduced. This is a line segment that diagonally connects the terminal end of . Therefore, in order to correct this and align the head trajectory C with the track trajectory a, the heads 2A and 2B are
If we assume that the running direction of the tape l during recording is + and the opposite direction is -, it can be seen that it is sufficient to continuously shift from 0 to -ITP within one field scan.

Therefore, in the D/A converter 29 shown in FIG. 2, the output of the counter 28 is converted into a stay pattern signal as shown in FIG. 3 (Q). It can be seen that the required transition can be satisfied.

On the other hand, the capstan FG signal output from the frequency signal generator 12 as the capstan 10 is rotated by the carburetor stan motor 11 is applied to counters 20 and 22 in the pattern signal generation circuit 15 shown in FIG. ,
These counters 20 and 22 count this capstan FG signal, and here, the counter 20 counts 1 by the CTL signal from the CTL head 9.
Since it is reset every frame, the count output has a count value of +2 track pitches as the upper limit.
During playback at 1.5 times the speed, the CTL signal becomes as shown in FIG. 3 (Φ), so it becomes as shown in FIG. In order to count the capstan FG signal while presetting the output of the counter 20 at that point in time as shown in FIG. 3(b), the count output (or the output of the D/A converter 23) is 155
Double speed playback is as shown in FIG. 3(f). Therefore, the adder 25 outputs the result of adding the output of the D/A converter 23 and the output of the stay pattern generator 24 at this time.
During 1.5 times speed playback, a pattern signal as shown in FIG. 3 (gl) is output.

Here, during playback at 1.5x speed, the head trajectories of the two heads and 2B with respect to the track locus on tape 1 are shown in Figure 4 (
It will be as shown in EEI. That is, in the figure, AIIAy g
A3 H------ is the head trajectory of head 2A, B
11B! , B3, --- indicates the head locus of head 2B, and altatl''31----1 indicates the track locus of the field track recorded by the recording head having the same azimuth angle as heads 2A and 2B. In the first field, in order to match the head trajectory A1 with the track trajectory a, it is necessary to continuously give the head 2A a shift from 0 to +0.5 T P within the first field scan. , In the second field, in order to match the head trajectory B with the track trajectory a, it is necessary to continuously apply a change from +1.5 TP to +2 TP to the head 2B within the g2 field.
In the third field, in order to match the head trajectory A2 with the next track trajectory a2, it is necessary to continuously apply a change from +1TP to +1.5TP to the head 2A within the scan of the third field. In the 4th field, in order to match the head trajectory B to the next track trajectory a, +0 is applied to the head 2B within the scanning of the 4th field.
．． It is necessary to continuously apply a transition from 5 T P minutes to +112 minutes, so the above steps are repeated every 4 fields.
It can be seen that the pattern signal shown in FIG. 3(m) satisfies the required transition of B.

The above has been explained using 155x playback as an example, but the pattern signal generation circuit 15 generates a pattern signal for controlling the heads 2A and 2B commensurate with the playback speed not only at 1.5x but at any playback speed. obtained from.

The pattern signal obtained from the pattern signal generation circuit 15 in this manner is applied to the conversion element drive circuit 16, and the drive circuit 16 uses the pattern signal to
The electro-mechanical transducers 3A and 3B are driven to bring the signal on track with respect to the track to be reproduced.

Based on the above principle, conventional devices
A noise-free reproduced video signal was obtained at any reproduction speed by obtaining a pattern signal for driving a shifting means such as a mechanical conversion element.

However, in general, the transition means represented by the electro-mechanical conversion element cannot follow sudden changes in the drive voltage, causing a resonance (ringing) phenomenon. 1I-o Figure 5(a),
(b) is a diagram for explaining the relationship between the drive voltage for the displacement means and the actual displacement. As shown in the figure, if there is a fall (or rise) in the drive voltage as shown by Ta. Particularly in the rising and falling portions that involve extremely large level changes, the resonance period becomes long, resulting in a situation where control is almost impossible.

Therefore, when a driving voltage according to a pattern signal as shown in Fig. 3 is supplied to the shifting means, the driving wJ voltage level changes rapidly at the switching timing of each field.Therefore, in the first half of each field, the rotation The reality is that the displacement of the head cannot be controlled as desired.

Therefore, generally, the pattern signal generated by the pattern signal generation circuit 15 is harmonicized by a low-pass filter (LPF) in the conversion element drive circuit 16, and then supplied to the electro-mechanical conversion elements 3A and 3B. However, if the LPF cut-off frequency cannot be lowered to an extreme level, ringing may occur if the LPF cut-off frequency is not extremely low. It's something to put away.

In addition, as another method, for example, to control the head 2A, it is not necessary to use the no-turn signal of the period corresponding to FIG. Focusing on the fact that it is not necessary to use the pattern signal of the period corresponding to A1 p A2 @------ to do this, a fixed pattern signal for displacing the head 2A and a fixed pattern signal for displacing the head 2B are used. It is undesirable to form the turn signal completely separately, and the pattern signal becomes abrupt just before the effective period used for control for each, which complicates the circuit.

<Object of the invention> The present invention has been made in view of the above-mentioned drawbacks.
It is an object of the present invention to provide a rotary head type reproducing device that can extremely effectively prevent resonance of a shifting means without complicating the circuit configuration and can always perform good tracking.

<Explanation based on examples> The present invention will be explained below using examples.

FIG. 6 is a block diagram showing a pattern signal generation circuit which is a main part of a VTR according to an embodiment of the present invention. In FIG. 6, the same components as in FIG. 2 are given the same numbers and their explanations are omitted. 31 digit 1 field period delay circuit, 32 a z32b are adder circuits, 33
a and 33b are inverting amplifiers, 34a and 34b are analog switches, and 35a.

35b is an adder circuit, 36a and 36b are analog switches, 37 is a differentiation circuit, 38 is an l field period hold circuit, 39 is an inverter, 40ag40
41a and 41b are gate circuits, 42 is an oscillator, 43 is a counter, 44 is a D/A converter, and 45 is a 1/2 frequency divider.

FIGS. 7(a) to 7(V) are timing charts showing the waveforms of each part of FIGS. 6(a) to (1), and the operation will be explained below using the same figures. The timing chart in Figure 7 is 3/4
This is at the time of double speed slow damage.

From the D/A converter 23 and the D/A converter 29, the solid line in FIG. 7(C) and the solid line in FIG.
) are obtained, respectively. By adding these, a pattern signal corresponding to the distance between the recording track and the trace locus of the head can be obtained.

This sudden rise or fall of the butter signal is D/
2TP of the first pattern signal obtained from the A converter 23
rising or falling edge of the second pattern signal
It corresponds to the falling section of P minutes.

Furthermore, as described above, the waveform of the pattern signal that drives the shifting means that shifts the non-reproducing head may be of any waveform. Therefore, during this period, the above first pattern belief @
and 1 for each rising edge or falling edge of the second pattern signal.
If this is done properly, the head during reproduction will not suffer from poor tracking due to the resonance phenomenon of the converting means. In this embodiment, this is realized with a simple circuit configuration.

The differentiating circuit 37 is for detecting a sudden rise or fall of the output waveform of the D/A converter 23, that is, the first pattern signal, and the hold circuit 38 is for detecting the sudden rise or fall of the output waveform of the differentiator 37 Trigger on the rising or falling edge and hold the high level between the l field and the falling edge. On the other hand, the pattern signal delay circuit 31 of Option 1 delays the signal by one field period, as shown in FIG.
), the waveform is as shown by the dotted line, and the adder circuit 32 a, 3
2 b. At this time, the output of the hold circuit 38 is at a high level for one field period immediately before the rising or falling edge of the delayed first pattern signal. Therefore, when the output of the hold circuit 38 is at a high level and the heads 2A and 211 are not reproducing, the sudden level change of the first butter/signal for driving the conversion elements 3A and 3B is compensated for. Addition circuits 32a and 32b add compensation pattern signals for this purpose. ANDGATE 40a.

40b outputs a signal indicating this period at a high level (shown in FIGS. 7(e) and 7(f)), and the compensation pattern signal output from the D/A converter 44 during these periods is Addition circuit 3 via gate circuits 41a and 41b
2a and 32b.

By the way, this compensation signal is a signal as shown in FIG. 7, that is, a pattern signal that can shift the shifting means from 0 to -2 TP in one field period.

Oscillator 42. A counter 43° is formed by a D/A converter 44. That is, the oscillator 42 has an oscillation frequency that is twice the capstan FG signal frequency at a normal tape speed. 2 of the oscillator 27 shown in FIG.
It can be thought of as having twice the oscillation frequency.

Inverting amplifier 33 a r 33 b and switch 34
a and 34b take into account the running direction of the tape, respectively.
When traveling in the reverse direction, signals are output via inverting amplifiers 33a and 33b. The output signals of the analog switches 34a and 34b are shown in FIG. 7(i) Cj). In this way, the signal applied to the conversion element that moves the head during reproduction is prevented from causing a sudden level change immediately before the signal is applied to the conversion element.

In addition, sudden level changes that often occur in the second pattern signal (stay pattern signal) can be reliably compensated for by not applying the second pattern signal during the period when the head is moving during non-reproduction. be able to. The second pattern signal, which is the output of the D/A converter N29, is supplied to adder circuits 35a and 35b. Also, the switch 36a
, 36b are each controlled by the H8W signal, and A1. A
During the period 2-1-, the A side terminal, Bl + Bl--
During the period --, the B side terminals are connected. This causes the output terminal 26a.

26b, pattern signals as shown in solid lines in FIG. The pattern signal is a conventional pattern signal.

By configuring the pattern signal generation circuit as described above, instability caused by ringing of the conversion element is eliminated, and it becomes possible to perform good head tracking. Furthermore, the circuit configuration is relatively simple, unlike the case where completely separate circuits are used to form separate fixed pattern signals to drive a pair of conversion elements.

Incidentally, in recent years, as a tracking method for V1'H, a method has been used in which a tracking pilot signal is superimposed on a video signal and a tracking control signal is obtained by separating this pilot signal from the reproduced video signal. The number is increasing as TRs become smaller. Since VTRs employing this tracking method do not record CTL signals as in the past, the method for creating pattern signals to be applied to the shifting means is also different.

An embodiment in which the present invention is applied to a VTR that does not use such a CTL signal will be described below.

FIG. 8 is a diagram showing the main part configuration of a VTR as another embodiment of the present invention. Components in this figure that are similar to those in FIG. 6 are designated by the same numbers and their explanations will be omitted. Similar to FIG. 6, this figure also shows an example of the structure of a pattern signal generating circuit in place of the pattern signal generating circuit 15 of FIG. 1.

In the figure, 136 is a power-up clear pulse (PU
C) A manually operated terminal 137 is an RS flip-flop 138 which is reset by the PLJC and set by the rise or fall of the timing signal from the timing signal generation circuit 21. is a low-order binary counter that counts the capstan FG signal from the input terminal 17. When the capstan FG signal is received for one frame, that is, for 2 TP, an overflow signal (under the birthmark, OF times It is configured to output a signal and self-reset or return to zero.The Q output of the flip-flop 137 is applied to the reset input of the lower counter 13B, and the reset input of the counter 13 is As long as it is high, it is maintained in the reset state, and when it becomes low, it becomes a count enable. 139 is an upper binary counter for counting the overflow signal from the lower counter 138.
A counter 140 uses the count output of the lower counter 13B as lower binary data, and also outputs the count output of the lower counter 13B as lower binary data.
The D/A in Figure 6 inputs the count output of 9 as upper binary data and converts the composite count value from D/A.
It is a D/A converter similar to converter 23.

) Explain the operation.

First, when the device is powered on or set to playback mode, the flip-flop 137 is reset and its Q output becomes NO, thereby keeping the lower counter 138 in the reset state. It will look like this. Next, the head motor 5 starts rotating the heads 2A and 2B. When the -1SW signal is outputted from the rotational phase detector 6, the timing signal generating circuit 21 outputs the 4-iH8W signal as in the pattern signal generating circuit 15 of FIGS. 2 and 6. A timing signal synchronized with each rising edge and falling edge of the signal is output.

When a timing signal is output from the timing signal button generation circuit 21, the flip-flop 137 is set by the first signal and its Q output becomes low, so the lower counter 138 is released from the reset state, and thereafter , the capstan FG signal outputted from the frequency signal generator 12 as the capstan 10 is rotated by the carburetor stan motor 11 is counted. Also, upper counter 1
39 is reset every time the timing signal is received. Here, as described above, the lower counter 138 outputs the OF times signal when it receives the capstan FG for 2 TP, and also resets itself or returns to zero.

Therefore, the combined count output of these counters 138 and 139 (or the output of the D/A converter 140) is shown in FIG.
It will be as shown in C).

Note that the operations of other parts and the waveforms of each part are exactly the same as the example shown in FIG.

Therefore, as shown in FIG. 8, by applying the present invention even to a VTR that does not use a CTL signal, instability in tracking control due to ringing of the conversion element can be eliminated very easily.

As explained above, according to the present invention, the third pattern signal is formed to eliminate the sudden level change of the first pattern signal related to the movement of the recording medium, and A control putter 746 for each of a plurality of heads is created by appropriately combining these three types of pattern signals together with the second pattern (No. 6) showing the relationship between the trace trajectories of the track and the head.
It is possible to obtain a rotating head-type nuisance device that can effectively prevent the phenomenon of joint movement of the head displacement means with an extremely simple circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of the main part of a conventional V l' i(c), FIG. 2 is a diagram showing an example of the pattern signal generation circuit of the VTR shown in FIG. 1, and FIG. Figure 2 is a diagram showing waveforms at various parts; Figures 4 (5) and (B) are diagrams showing the relationship between recording tracks on the tape and head scanning during still playback and 15x playback, respectively; FIG. 5 is a diagram for explaining the relationship between the driving force and the actual displacement for the displacement means, and FIG.
FIG. 8 is a block diagram showing the main part configuration of a VTR according to another embodiment of the present invention. 1 is a magnetic tape as a recording medium, 2A and 2B are rotating heads, 3A and 3B are electromechanical conversion elements as displacement means, 10 is a capstan, 11 is a capstan motor, and 12 is a first pulse. capstan FG
Signal generator, 20 is a counter, 22 is a presettable counter, 23 is an IJ/A that outputs the first pattern signal
Converter 29 outputs all second pattern signals 1)/A
Converters 32a, 32b, 35a, 35b are adder circuits, 36a, 36b are analog switches, 44 is a D/A converter that outputs the third pattern signal, 45 is a 1/
A 2 frequency divider, 138 and 139 are counters, and 140 is a D/A converter that outputs the first pattern signal. Continuing from page 1 of Canon Co., Ltd. @ Inventor Tatsuzo Ushiro [Partner] Inventor Ken Nagahama - Inside the company

Claims (1)

[Claims] (1) Recording tracks formed at a predetermined pitch on the recording medium being transported (by the transporting means) are sequentially transported by a pair of rotary heads that are displaced by a pair of displacement means in a direction intersecting the rotating surface. means for forming a first pattern signal from a first pulse signal obtained in connection with the rotation of the rotary head; a vibration means for generating a second pulse signal related to the rotation of the rotary head; means for generating a second pattern signal based on the first pattern signal; means for generating a third pattern signal for eliminating sudden changes in the first pattern signal; 2 pattern signals are used to drive the shifting means for displacing the rotating head during reproduction, and for the shifting means for displacing the rotating heads for non-writers, at least the first pattern signal and the #3 pattern signal are used. A rotary head type reproducing device comprising a driving means for driving using a putter No. 715.