JPS60201519A - Rotary head type video signal reproducing device - Google Patents

Abstract

PURPOSE:To obtain a very excellent varying-speed (special) reproducing pattern by using an output obtained from the sampling of a signal representing a shift amount of a head to a track in the timing where the head enters a prescribed region so as to shift a drive signal obtained through a pulse acquired in response to the carrying of a recording medium. CONSTITUTION:Each kind of a pilot signal having plural kinds of different frequencies is recorded on a recording medium while being superimposed respectively on a video signal for one field's share. Then the recorded signal is reproduced. Further, the level of the pilot signal obtained from a track (both adjacent tracks) at both sides of a track (main track) traced mainly by the reproducing head is compared so as to obtain track shift information of the reproducing head and it is used as a tracking control signal. Thus, the operation of the carrying means is made stable and also the head lifting position onto a prescribed region of the recording track is controlled very accurately.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a rotary head type video signal reproducing device, and more particularly, to a rotary head type video signal reproducing device, and more particularly, to a rotary head type video signal reproducing device, and more particularly, to a rotary head type video signal reproducing device. , relates to a rotary head type reproducing device which reproduces a video signal by tracing it with a rotary head which is displaced by a displacement means in a direction intersecting the rotating surface of the rotary head;
More specifically, the present invention relates to control of the shifting means when performing reproduction by transporting the recording medium at a speed different from that during recording, such as high-speed reproduction, low-speed reproduction, and reverse reproduction.

<Description of the Prior Art> In a rotary head type video signal reproducing device such as a VTR, any recording medium transfer speed that corresponds to the recording time, such as low-speed playback, low-speed playback (including static playback), reverse playback, etc. Playback by (
In order to prevent the occurrence of noise bars and enable stable and clear image playback when performing so-called special playback, the playback head records the video signal of each recording track in each scanning field. It is necessary to trace the area accurately.

As one means to realize such a function, conventionally 1.
A pattern signal generator is provided that generates a pattern signal corresponding to the distance from the scanning locus of the playback head to the recording track on the tape at a given tape running speed. Means for controlling a displacement means such as an electro-mechanical transducer (for example, a bi-self element) for displacing the head in a direction intersecting the plane of rotation of the head is known. Here, the conventionally known pattern signal generating device has a scanning locus draw A/signal of the reproducing head, as will be explained in detail with reference to the drawings later.
That is, it is of an absolute phase type that detects a so-called CTL signal and a capstan FG signal related to the rotation of a capstan serving as a tape transport means that effectively divides the interval between the CTL signals.

On the other hand, in recent years, in order to achieve high-density recording, the above-mentioned CTL has been abolished, and one type of pilot signal having a tracking frequency as shown below is superimposed on one field worth of video signal on the recording medium. Record it. and,
This is reproduced by a reproducing head to separate only the pilot signal component. And the tracks on both sides (adjacent tracks) of the track that the playhead is mainly tracing (main track)! By comparing the levels of the pilot signals sent by IIN, information on the track deviation of the playback head is obtained.
This is intended to be the tracking control number 1d (A'l'F signal). A VTR has been proposed that performs 4f tracking.

In order to obtain the above-mentioned pattern signal in a VTR that performs 4f tracking in this way, it is conceivable to form the pattern signal using the above-mentioned capstan FG signal.

However, unlike the CTL signal, this capstan FG signal does not contain information indicating the position of the recording track, so it is difficult to make the head accurately trace the area of the recording track where the video signal is recorded. Not. That is,
If the shifting means is driven using the pattern signal obtained using the capstan FG signal in this way, the trace locus of the rotary head will deviate from parallel to the recording track.

It is also possible to drive the liquid deflection means, but the pilot signal is obtained only after the head starts tracing the recording track, and the entry position for each recording track is not controlled, and the liquid deflection means is controlled after entry. Therefore, the operation of the shifting means is unstable. Moreover, contrary to the capstan-based tape running control circuit, it becomes difficult to perform the capstan servo.

<Object of the Invention> The present invention has been made in view of the above-mentioned drawbacks, and is aimed at stabilizing the operation of the shifting means and extremely accurately controlling the entry position of the head into a predetermined area of the recording track. The object of the present invention is to provide a rotary head type video signal reproducing device that can perform the following functions.

<Explanation based on Examples> Hereinafter, the means described in the present invention for achieving the above-mentioned objectives will be exemplified and explained using examples shown in the accompanying drawings.

Prior to a detailed explanation of the present invention, a conventional VTR will be explained.

First, referring to FIG. 1, in the figure, l 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 180 degrees. , respectively, are attached to the free ends of electro-mechanical conversion elements 3A and 3B, such as bi-self elements, serving as conversion means. The conversion 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 not shown in the figure, as is well known, the heads 2A and 2
B is a reed that is rotated while protruding from a slit between a pair of tape guides and drums, and the tape 1 is wound diagonally around the pair of drums over a range of 180 degrees or more. 6 is 2 heads and 2B
The signal from the detector 6 is used as a head switching signal (hereinafter referred to as H8W signal) and is also used as a head motor control circuit 7.
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 heads 2A and 2B in a predetermined phase and at a predetermined rotational speed.

Reference numeral 9 denotes a fixed head for control signal reproduction (hereinafter referred to as C'l) 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.
'L head), 10 constitutes a transport means for transporting the tape 1 in the longitudinal direction in cooperation with a pinch roller of an infusible ball; 11 a capstan for rotating the capstan 10; A motor, 12 a frequency signal generator that generates a frequency signal (hereinafter referred to as a capstan FG signal) corresponding to the rotation of the capstan 10, and 13 a CT
Capstan 1 based on the CTL signal from L head 9 and the capstan FG signal from frequency signal generator 12.
The cab's tongue motor drive circuit 14 controls the cab's tongue motor 11 so as to rotate the cab's tongue motor 11 in a predetermined phase and at a prescribed rotation speed.
This is the carburetor tongue motor control circuit. 15 is the H8VV signal from the rotational phase detector 6 and CTL
Based on the CTL signal from the head 9 and the capstan FG signal from the frequency signal generator 12, the
patterns for electro-mechanical transducers 3A and 3B to cause heads 2A and 2B to each trace one recording track on tape 1 in each scan field; The pattern signal generation circuit h16 that generates the signal is a conversion element drive circuit that drives the conversion elements 3A and 3B based on the pattern signal from the pattern signal generation circuit 15.

FIG. 2 shows an example of the configuration of the pattern signal generation circuit 15. In the figure, input terminals 1-7, 18 and 19 each have a capstan FG from the frequency signal generator 12 mentioned above.
The signals C1'L4i@ from the CTL head 9 and the H8W signal from the rotational phase detector 6 are input. 20 is a binary counter configured to count the capstan FG signal inputted to the terminal 17 and reset by the CTL signal inputted manually to the terminal 18 ~ 21 is the H8W4i@f source inputted to the terminal 19 A timing signal generation circuit 22 generates a timing signal (g) synchronized with the H8W signal, and is preset as data PD of the counter 20 by the timing signal from the timing signal generation circuit 21, and is also output to the terminal 17.
23 is a D/A that converts the output of the presettable counter 22 into a D/A.
converter, 24 is a stay pattern generator that generates a fixed pattern signal for stay reproduction based on the timing signal from the timing signal generation circuit 21, and 25 is the output of the D/A converter 23 and the stay pattern generator. An adder 26 is an output terminal for outputting a conversion element control pattern signal which is an output of the adder 25.

Next, the operation during special reproduction of V T )t having the above configuration will be explained with reference to FIGS. 3 and 4, focusing on the operation of the pattern signal generation circuit shown in FIG. 2. In addition, in Fig. 3, (d) to (2) are especially the CT at 1.5 times speed playback.
The L signal, the output of the second illustrated counter 20, the output of the presettable counter 22 (or D/A converter 23), and the output of the adder 25 are respectively shown.
5) and (81) show the relationship between the center locus of the scans of the heads 2A and 2 to 3 with respect to the center locus of the recording track on the tape 1 during slow playback and 1.5x speed playback, respectively.

First, as the heads 2A and 2B are rotated by the head motor 5, the six rotational phase detectors output an H8Vv signal as shown in FIG. 3(a), and the pattern signal shown in FIG. The timing signal generating circuit 21 in the circuit 15 outputs a timing signal synchronized with each rising edge and falling edge of the H8W signal, as shown in FIG. 3(b). Then, based on this timing signal, the stay signal is
The pattern generator 24 outputs l as shown in FIG. 3(C).
A stay pattern signal is output for continuously converting the heads 2A and 2B from O to 11 track pitches (hereinafter referred to as TP) within scanning of a field.

Here, the so-called field stay is performed in which the field signals of one recording track that have been slightly recorded by the recording head having the same azimuth angle as the two reproduction heads and 2B are alternately reproduced by the two reproduction heads and 2B. When attempting to perform playback, the relationship between the center loci of the scans of the two heads and 2B with respect to the recording track on the tape L at this time is the fourth
The result is as shown in Figure (5). That is, in FIG. 4 (5), the solid line indicates the center trajectory 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. CT
L indicates the recording locus of the CT L signal (this also applies to FIG. Head trajectory) C is a line segment that diagonally connects the starting end of track trajectory a to the end of the track trajectory of the track adjacent to the left with respect to the center trajectory (hereinafter referred to as track trajectory) a of the track to be reproduced. becomes. Therefore, in order to correct this and align the head trajectory C with the track trajectory a, the heads 2A and 2
B, the running direction of tape 1 during recording is +, and the opposite direction is -.
If it is set to 1, it can be seen that it is sufficient to continuously shift from 0 to -ITP within the scan of the l field.

From the above, it can be seen that the stay pattern signal from the stay pattern generator 24 shown in FIG. 3(C) can satisfy the necessary transitions of the two heads and 2B for field stay reproduction.

On the other hand, the capstan FG signal output from the frequency signal generator 12 as the capstan lO 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 are connected to this capstan FG.
The counter 20 is reset every frame by the CTL signal from the CTL head 9, so its count output is a count value of +2 track pitches. With this as the upper limit, the CTL1η number becomes as shown in FIG. 3(d) during 1.5 times speed playback, so the result becomes as shown in FIG. 3(e). In response to this, the presettable counter 22 receives a timing signal from the timing signal generation circuit 21 (FIG. 3(b)).
In order to count the capstan FG signal while presetting the output of the counter 20 at that time,
The count output (or the output of the D/A converter 23) becomes as shown in FIG. 3(f) during 1.5 times speed playback.

Therefore, from the adder 25, the D/A converter 23 at this time
As a result of adding the output of the still pattern generator 24 and the output of the stay pattern generator 24, a pattern signal as shown in FIG. 3(2) is output during 1.5 times speed playback.

Note that the outputs of the counters 20 and 22 and the adder 25 are as follows:
The solid line includes small stepwise changes because the counters 2o and 22 count the capstan FG signal, but it is shown in a simplified manner in the figure.

Here, 1. During δ double speed playback, the head trajectories of heads 2A and 2B with respect to the track trajectories on tape l are shown in Figure 4 (
(b) as shown. That is, in the figure, AHA2 t A
11----- is the head trajectory of head 2A, 131t
B, , B, −−+− is the head trajectory of head 2B,
Also, al a am + am---- indicates the track locus of the field track completely recorded by the recording head having the same azimuth angle as heads 2A and 2B, and in the first field, the head locus A1 is tracked. In order to match the trajectory 8 times, it is necessary to continuously give the head 2A a shift of +0.5 T P from O within the scanning of the first field, and in the second field, the head trajectory B is the same. In order to match the track trajectory A, it is necessary to continuously give the head 2B a shift from +1.5TP to +2TP within the scanning of the second field, and in the third field, the head trajectory A2 is Truck trajectory a! +11'P to +1.5T within the third field scan for head 2A to match the
It is necessary to continuously give a change of up to P minutes, and in the fourth field, the head trajectory Bt is changed to the next track trajectory a,
It is necessary to give the head 2B a transition from +0, 51" P minutes to +l i' P minutes continuously within the scanning of the fourth field in order to match the above. This is a question that will be repeated repeatedly, but
Figure 3 (
It can be seen that the pattern signal shown in the figure satisfies this requirement.

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

The pattern signal obtained from the pattern signal generation circuit 15 in this manner is applied to the conversion element drive circuit 16, which drives the head 2 based on the pattern signal and the H8W signal from the rotational phase detector 6. The electro-mechanical transducers 3A and 3B are driven to bring the person and 2B on track to the track to be reproduced.

Now, in the conventional device, as described above, a pattern signal for controlling the head commensurate with the playback speed at any speed is obtained, but here, in the conventional device, the pattern signal It is clear that the C1'L signal is indispensable for signal formation, and is therefore completely ineffective in a system that does not use the CTL signal.

In contrast, the present invention is designed to obtain a pattern signal for head control commensurate with the playback speed at any speed without using the CTL signal at all.One embodiment of the present invention will be described below. .

FIG. 85 is a block diagram mainly showing the outline of the configuration of the special playback system section of V i"K as an embodiment of the present invention. In FIG. 5, the same components as in FIG. A subtitle is attached and the explanation is omitted.

That is, since the CTL signal ψ is not used in the numbers 1 to 14, the C'T'L head 9 is the same as the conventional V 'I' R shown in FIG. It is unchanging.

In the embodiment shown in FIG. 5, V T )it is C'1
'Instead of the tracking method using the L signal, the following method will be used. That is, a plurality of types (for example, four types) of pilot signals having different frequencies are superimposed on one field of video signals and recorded on a recording medium.

This is then reproduced by a reproducing head to separate only the pilot signal component.

Then, the levels of the pilot signals obtained from the tracks on both sides (both adjacent tracks) of the track that the playback head is mainly tracing (main track) are compared to obtain information on the track deviation of the playback head, and this is used for tracking. The idea is to use it as a control signal. That is, it is assumed that the well-known 4f method tracking is performed.

The functions of each part in FIG. 1 will be briefly explained below.

The reproduction signals obtained from the reproduction heads 2A and 2B include the video signal and the tracking pilot signal as described above. This reproduction signal is amplified by a reproduction amplifier 51 and converted into a continuous signal by the HSW signal, which is then supplied to a video signal reproduction processing circuit 52 and a tracking signal generation circuit 53. The video signal reproduction processing circuit 52 divides the output signal of the reproduction amplifier 51 into the video signal, performs processing such as demodulation, and supplies the original (No. 4 format) reproduction video signal to the output terminal 50.

On the other hand, in the tracking signal generation circuit 53, the output signal of the regenerative amplifier 51 and the pilot signal component are separated, and the levels of the pilot signals obtained from the image are compared to obtain the tracking control signal. This process performs the following processing.

54 is a system control circuit for controlling the operation of each part of the apparatus according to the operation mode of the apparatus. For example, head morph control circuit 7. The capstan motor control circuit 13 (#) 7-king signal generation circuit 53 and the pattern signal generation circuit described later operate differently during recording and playback (depending on the specified tape speed, etc.); A control signal is generated to perform a desired operation in each operation mode.

55 is a conversion element control circuit, and a pattern signal generation circuit 56. Low pass filter (LPF) 5'/.

Subtraction circuit 58. It includes a DC component removal circuit 59 and a conversion element driver circuit. By the output of this conversion element control circuit 855, the aforementioned electro-mechanical conversion elements 3A, 3
B are the playback heads 2A, 2 in each scanning field, respectively.
B is driven to trace one recording track in a positive vfK manner.

FIG. 6 is a diagram showing a detailed configuration of the conversion element control circuit 55, and the operation of generating conversion element control pattern signals and driving them will be explained below using FIG.

The pattern signal generation circuit 56 is mainly composed of a counter P 101 e, a counter A 102, and a counter B 103, and these counters are up-down counters with up-down parallel inputs.

Note that the input of each counter indicated by CD indicates a countdown input terminal, and CU indicates a countup input terminal. Also, in this example, a binary counter will be used.

Now, the fixed pattern signal required to realize the noiseless special playback described above includes information (phase information) in order to accurately align the entry position of the playback head with respect to the playback track that changes as the tape runs. ) and information (speed information) for matching the slope of the playback track with the trace trajectory of the playback head corresponding to the tape running speed.
(!: must be included at least.

In the pattern signal generation circuit 56 shown in FIG. 6, a counter P101 is used to obtain phase information, and a counter AlO2 and a counter B 103 are used to obtain speed information.

First, the operation of the counter P101 for obtaining phase information will be explained. Counter P101 is the capstan FG generated when the tape moves by 2 T P.
When twice (2n) the number of signals (n) is counted up, it is carried over and outputs a trivial signal from the CR terminal shown in the figure.

This carry signal is then supplied to a reset terminal (indicated by R in the figure) and resets the counter P101. Similarly, when the counter P101 counts down 2n times, the lower digit' is turned off and outputs a lower signal from the BR terminal shown in the figure. This borrow signal is supplied to a preset terminal (shown as PR in the figure), and the counter P 101 is connected to the preset data (2n) generated by the preset data generator 104.
).

For example, in this example, it is assumed that the number (n) of capstan FG signals generated as the tape moves by 2 TP is 24. Therefore, the counter P101 is a counter that repeats 0→48 when counting up, and 48→48 when counting down.
It becomes a counter that repeats O.

209 is an input terminal for the capstan F'G signal, 11 is a frequency 2 multiplier that generates a pulse when the capstan FG signal rises and falls, and 112 is an input terminal for the output pulse of the 2 multiplier 111. This is a pulse generator B that narrows the pulse width. 208 is a high level when the system control circuit 54 is running the tape 1 in the forward direction (the same direction as when recording);
This is a terminal to which a low level signal (hereinafter referred to as F/R signal) is supplied when the vehicle is running in the negative direction (the opposite direction to the recording direction). The F/R signal is connected to the AND gate 114 and the inverter 11.
6 to the AND gate 115. Therefore, the output pulses of the pulse generator B 112 are supplied to the CD terminal of the counter P101 via the AND gate 114 and the OR gate 13B when the tape is running in the positive direction, and to the CD terminal of the counter P101 when the tape is running in the negative direction. ) 115 and the CU of the counter P 101 via the OR gate 137
Supplied to the terminal.

With this configuration, the output data of the counter P101 is determined based on the relative relationship between the track to be reproduced on the running tape (the track recorded by a head having the same azimuth angle as heads 2A and 2B) and the entry position of the reproduction head. It is possible to control each entry position of each playback head by constantly indicating the relative positional deviation (relative phase information). However, since this phase information is only relative phase information, it is valid only when the previous reproducing head entry position matches the reproducing track. On the other hand, in the conventional apparatus using C1''L as shown in FIG. 1, it was possible to obtain the entry phase of the reproducing head as absolute phase information in accordance with the recording position of the CTL signal.

Therefore, in this example, relative phase information is generated in advance by the counter P101 as described above, and at the same time, the entry position of the reproducing head is made to coincide with the reproducing track. This role is taken care of by the rush phase control circuit shown in FIG. 6, 123.
The circuit 123 generates an absolute phase adjustment pulse to control the entry position of the reproducing head so that it coincides with the reproducing track even if it does not coincide with the reproducing track. Regarding this rush phase control circuit 123, the pattern generation circuit 56
A detailed explanation will be provided after the overall explanation.

By the way, the pulse signal counted up or down by the counter P101 is output from the capstan F.
It is obtained by doubling G(ii), but this is done to improve the accuracy of the phase information mentioned above.In other words, the capstan F for 1TP is
This prevents the phase information from becoming coarse due to a decrease in the number of occurrences of G(fi).

Also, the reason why the pulse width is narrowed in the pulse generation circuit B112 will be obvious from the explanation later, but there is an opportunity to count up or count down multiple pulse numbers in each counter. This is because the counter is configured to perform operations equivalent to addition and subtraction.

Additionally, a pulse generation circuit B112 is provided to reduce the probability of a situation in which a plurality of pulse signals are input at exactly the same timing and one cannot be counted. Further, the pulse generating circuit A131 and the pulse generating circuit C113 are also provided for the same purpose, and their explanation will be omitted in the following explanation.

As mentioned above, when the tape is running in the forward direction, the counter P101 counts down the pulses related to the capstan FG signal at that time, and when the tape is running in the reverse direction, it counts up. Regardless of the direction, relative phase information of the entry position when the reproducing head enters the reproduction track of the reproduction head between the groups is output. - For example, if slow motion playback is performed by running the tape in the spinal pressure direction at 1/3 times the tape speed during recording, and in the opposite direction (hereinafter referred to as pressure 1/3 slow), at 1/3 the same tape speed as recording. Taking as an example the case where the tape is run at twice the tape speed and slowed (hereinafter referred to as reverse 1/3 throw), in the case of forward 1/3 slow, the output of counter P101 is generated every 6 field scanning periods. 48→0 is repeated, and in the case of reverse 1/3 slow, 0→48 is repeated every 6 field scanning periods.

If, for example, 16 is obtained as the output of the head entry time counter P101, the entry position of the reproducing head at that time with respect to the reproduction track will be a position shifted by 2/BTP of the conversion element.

In addition, the number of bits necessary for the counter P101 is the number of bits (6 bits in this example) necessary to represent 2n (48 in this example) in binary in the case of a binary counter.

By reading out the data obtained by the counter P 101 at a predetermined timing as the rotary head rotates in this way, it is possible to obtain information on the phase in which the rad enters playback with respect to the playback track. Therefore, the operations of the counter AlO2 and the counter B 103 that operate using this will be explained next.

Counter A 102 and counter B 103 are counters for outputting fixed pattern signals containing phase information and speed information as described above as digital data.

In addition to the phase information obtained by the counter P101, the counter AlO2 and the counter B103 also use the phase information obtained by the counter P101.
This is to generate the above-mentioned speed information to correct the difference in slope between the playback track and the trace trajectory of the playback head, which occurs because the tape runs at a speed different from that during recording when B scans the tape. be. In addition, the counter AlO2
The number of bits of the counter B103 is set to 10 bits in this example, but it is determined by the required shift amount of the conversion element, that is, the maximum tape speed at the time of high-speed search playback that is desired to be made possible.

Counter A 102 and counter B 103 load the output data of counter P 101 as lower 6-bit data at predetermined timings related to the rotations of heads 2A and 2B, respectively. The signal that determines the timing of this load is obtained according to the H8W signal, the load signal (PTJL, A) of the counter AlO2 is sent to the terminal 302, and the load signal (PUL, B) of the counter B 103 is sent to the terminal 20.
4 and 4 are each input. PLIL, A and PLIL
SB is input to the preset terminals (indicated by PR in the figure) of the counter AlO2 and counter B103, respectively.

It goes without saying that when the heads 2A and 2B are rotating with a 180' phase difference, PULlA and PULSB are also input with a 1800 phase difference.

When PLIL, A, PLIL, and B are input to PR, initial data is loaded into counter A 102 and counter B 103, respectively. As mentioned above, the output data of the counter P101 is used as the initial data for the lower 6 bits, but the upper 4 bits ψ are generated by the preset data generation circuit 105. In this embodiment, the data supplied from the circuit 105 is 1000. This converts the output data of counter AlO2 and counter B103 into new offset binary data.
The aim is for the output to be close to 0 level during A conversion.

That is, in this case -- the initial data to be read is 100000
The initial data (from 0000 to 1000110000) is desirable because it is near O and does not generate much DC component as will be described later. By the way, based on the idea that the output data of the preset data generation circuit 105 does not generate a DC component, it is more preferable to change it according to the specified tape running speed. When running the tape, 1011 is generated more often than the circuit 105, and when running the tape at 6 times the same speed in the opposite direction, 0101 is generated more often than the circuit 105.
Counter A to which the initial data is input as described above 1
Similarly to the counter P101 described above, the counter P103 counts pulses having a narrow pulse width and having twice the frequency of the capstan FG signal generated by the pulse generating circuit B112. Further, the counter AlO2 and the counter B103 count the clock pulse signals (CL), which are input to the terminal 210 and are unrelated to the running speed of the tape, via the pulse generating circuit C113.

Here, the clock pulse which is the output of the pulse generating circuit C113 is always guided to the CU copper terminals of both counters A and B.

Also, the output current of the pulse generating circuit B112 is output to the CD terminals of the counters A and B when the tape is running in the forward direction.
When traveling in the negative direction, the counter A, Bo) is configured to be guided to the CU copper terminal. This is because, as is well known, even if the tape running speed is the same, the difference in slope between the trace locus of the playback head and the playback track differs depending on the running direction. For example, if the tape running speed during recording is V,
Assuming that the tape speed during playback is Nv (positive N indicates a positive direction velocity, and negative indicates a negative direction velocity), the amount of head displacement required by the playback head during one field period is TPO(N-
1) The amount will be proportional to twice as much. This means that the slope of the fixed pattern signal is proportional to (1-N) in order to correct this.

Since the frequency of the output pulse of the pulse generating circuit B 112 is proportional to the absolute value of the tape running speed, by counting this frequency, the slope proportional to N is obtained. At this time, if the tape travels in the positive direction, it counts down, and if it travels in the negative direction, it counts up (1-N).
Obtain a slope proportional to . On the other hand, in the l field period, 11
' Since the slope required to displace the read head by P is proportional to l, I T
By counting up the number of pulses corresponding to P (48 in this example), a slope of +1 is obtained. If these are performed simultaneously, a desired slope proportional to (1-N) can be obtained. Therefore, the frequency of the clock pulse generated by the pulse generating circuit C is fvX4B (Hz). However, fv is the field scanning frequency.

A terminal 206 receives a square wave signal (PUL) for specifying the period during which the counter A 102 counts each of the aforementioned pulses.
, C) are supplied with terminals 117 and 119 (PUL, C) are used to gate each pulse. The other terminal 207 receives a rectangular wave signal (PU
L, D) are supplied to the terminals, and 9, PUL, and D are similarly connected to AND gates 118 and 120 to gate each pulse. 121 is an OR gate for guiding both the output pulse of the pulse generation circuit B 112 and the clock pulse output from the pulse generation circuit C113 to the counter AlO2 and the counter B103.

In this way, the counter A 102 and the counter B 103 take in initial data for determining the entry position of the head into the counters P1olj and jt during the period in which the playback rads 2A and 2B trace the recording track on the tape, respectively. , and by counting each pulse so as to obtain an inclination proportional to the inclination between the tracing locus of the reproducing head and the recording track, the reproducing head accurately traces the desired recording track when the tape is running at an arbitrary speed. This means that we were able to generate a fixed butterfly signal as digital data.

Next, the manner in which each timing signal is generated in this example will be explained in detail using the timing chart of FIG.

In Fig. 7, (A) is the H8VV signal, and when it is high level, two playback heads play back, and when it is low level, playback head 2B plays back one field worth of video signal on each recording track. Each period is indicated. Also this H8W
The signal is a 30 Hz rectangular wave signal of fv760 Hz, and is supplied to each part of the apparatus as a 30 Hz timing pulse related to the rotation of the head, which is 1130 PG. (b) is the capstan FG signal, and e'3 is the pulse (FGP) generated by the pulse generation circuit B112 in relation to this capstan FG signal. Teru. 2) A pulse (CLP) is generated by the pulse generation circuit C113 by narrowing the clock pulse (CL) inputted from the terminal 210, and (E) is a 60Hz timing pulse (60PG) that is phase-locked with the H8W signal. )(f) is the rectangular wave signal (PυL1C) supplied to the terminal 206, ()) is the rectangular wave signal (PUL, D) supplied to the terminal 20f, (a) is the counter A
A pulse (PUL) is supplied to terminal 202 to preset 102.

A), (S) are pulses (PLIL, B) supplied to the terminal 204 to preset the counter B103.
, (to) is a sampling pulse supplied to the terminal 205, (f) is an analog representation of the output data of the counter P101, and (b) is a pulse (PUL, E) outputted from the terminal 203.

Since the period during which the playback head 2A plays back the video signal for one field of each recording track is the period in which the H8W signal (B) is at a high level, it is originally the valid period N of the fixed pattern signal.
J (period φ including the above-mentioned phase information and velocity information) is sufficient for this period alone. However, as described above, the electro-mechanical transducer causes a resonance (ringing) phenomenon in response to a sudden change in applied voltage. Furthermore, in one recording track, in addition to the area where one field worth of video signals is recorded, there is an area where other signals (for example, digital audio signals) are recorded. Furthermore, it is necessary to obtain a tracking control signal from an area where other signals are recorded. The period in which the outputs of the pulse generation circuit B 112 and the pulse generation circuit C 113 can be counted is defined as the period when the H8W signal is at high level and the 1/2 field scanning period immediately before that.This period is the period when the high level of PLILSC (to) It is given as a period. This PULSC (e) can be freely formed by a logic circuit (not shown) using the H8W signal (a) and 60PG (e). The reason for the same tl'l is also given for PUL%D (g). It is then formed as shown in FIG.

The timing of taking in the initial data of the counter A 102 and the counter B 103 is determined by the pulses PUL, A (S), PUL, B (E) input to the PR terminal of each counter. This timing may be any timing as long as it is not included in the valid period of the fixed pattern signal.

In this example, in consideration of prevention of the ringing phenomenon described above, the fixed pattern signal is set immediately after the effective period so that no large level change occurs in the fixed pattern signal just before the effective period.

For example, PUL, A, and PUL, B may be formed using the falling edges of PUL, C, PLIL, DC. In addition, PUL, 5 (7) AhiP
LIL, EeiF) Vc will be explained in detail later.

Furthermore, the fixed pattern signal generated (according to this example) will be specifically illustrated and explained by setting the tape running speed. FIG. 8 is a timing chart showing fixed pattern signals (Vi) and (Vll) when the tape running speed is O (so-called still playback) and when it is the same as recording (so-called standard playback). FG shown in FIG. 8 (ii) and (iii),
The FGPs are those for standard playback.

Also, Fig. 8 (Vi) and (Vil) are color/ri A10
2(7) This is an analog display of output data. During still playback, FGP is not generated, and only CLP is counted by counter A 102 m counter B 103. Therefore, the output of the counter AlO2 becomes as shown in FIG. 8 (■1). Also counter PIO
Since the output data of 1 is always a constant number, the counter B10
The output of 3 has the same waveform as Fig. 8 (■1) and the phase is 18CP.
The waveform will be different by that amount. On the other hand, during standard playback, as shown in the diagram (F
GP and CLP are on the same frequency), counter A 10
2 and counter B103 count down FGP and count up CLP within the valid period of the fixed pattern, so that both of their outputs have very little fluctuation.

At this time, the output of the counter B has a waveform shifted by the level for ITP driving the conversion element with respect to the output (Vil) of the counter AlO2. This is because the timing at which the value of the counter P101 is taken differs by one field scanning period, during which time the counter P101 counts FGP by ITP.

Figure 9 shows the relationship between the recording track on the tape and the trace locus of the playback head at the time of the forward and reverse 1/3 slots.
FIG. 11 is a timing chart showing the fixed pattern signal (V) at the time of reverse 1/3 slot.

In Figure 9, @, Ao, A, , A are the center lines of recording tracks recorded with heads having the same azimuth angle as the reproducing heads 2A and 2B, respectively, and BO9Bl is the center line of the recording track recorded with the heads having the same azimuth angle as the reproducing heads 2A and 2B, respectively. This is the center line of recording tracks recorded by heads having different azimuth angles. On the other hand, a1 to a6 are the center lines of the trace locus of the head 2A when the displacement by the conversion element 3A is set to 0, bo#b is the center line of the trace locus of the head 2B when the displacement by the conversion element 3B is set to O, X is an arrow indicating the running of the tape.

As is well known, in forward 1/3 slow and reverse 1/3 slow, every other recording track is traced six times and reproduced. For example, in FIG. 9(5), recording track A1
bl e a9 e bt y am e bs e
Trace over 6 times a4. Figure 10 (Ino A
, B is the fixed pattern (
P is an analog representation of the output data of the counter A 102 and counter B 103), and P is an analog representation of the output data of the counter P.

Taking as an example the operation of aligning locus a2 with track A8 in FIG. 9(6), counter P at point U shown in FIG.
The output of counter A is taken in, and at the 7th point, counter A
It starts counting at point W, stops counting at point W, and takes in the output of counter P again. Desired by this repetition! r) It will be clear from a comparison with the 9th position that a luhong pattern signal can be obtained.

In Fig. 11 (V), A and H are fixed patterns generated by this example, and P is an analog display of the output data of counter P. Similarly, the output data of counter P is taken into counter A at point Fcu. , start counting at 7 points,
Counting is stopped at point W and the output of counter P is taken in again. It is also clear from comparison with FIG. M9 (b) that the fixed pattern signal shown in FIG. 11 is a desired fixed pattern signal.

In the above manner, the trace locus of the head can be aligned with the recording track, but as mentioned above, the phase information is relative.

Next, a description will be given of the entry phase control circuit 123 that makes the entry position of the reproducing head coincide with the recording track to be reproduced so that the phase information approaches absolute information.

In this example, a tracking control signal is used to match the inrush phase. This tracking control signal is supplied from the above-mentioned tracking control circuit 53, but in this example, since the above-mentioned 4f method tracking is performed, the playback signal is obtained from each of the playback heads 2A and 2B. Regarding the head - a tracking control signal can be obtained at all times. In this example as well, as is clear from FIGS. 5 and 86, the tracking control signals (A'l'FSA, ATF, B) obtained from the playback heads 2A and 2B have fixed patterns for the heads 2A and 2B. The signal is subtracted.

This converter element 3A only uses fixed pattern signals.

Since the deviation between the trace locus of the reproducing heads 2A and 2B and the track when the reproducing head 3B is driven is corrected, the fixed pattern signal may be shifted by using the ATF, A or ATFSB.

ATF inputted to the terminal 201A, A is the sample and hold circuit (S/H) 132, which indicates the timing at which each scanning field starts, that is, the timing at which the rotary head enters the area of the recording track where the video signal is recorded. The pulse (PLIL, S) is sampled and held as a sampling pulse. The timing of PUL and S is as shown in FIG. This S/H132
The output of comparators 133, 134 and resistors R,, R
,,R, supply voltage to another voltage detection circuit, predetermined voltage E
When the voltage is 1 or more, a high level output is obtained from the comparator 133, and when the voltage is below a predetermined voltage 4, which is lower than El, a high level output is obtained from the comparator 134.

The output of the comparator 133 is AND GO) 135,
The output of comparator 134 is provided to AND gate 136, which gates the pulses from pulse generation circuit A 131. Pulse generation circuit A 131 is the above-mentioned P, ULSA
narrows the pulse width and supplies it to AND gates 135 and 136. If ATF, A is above the average at the timing of PUL, S, the AND gate 135 sets the
It is supplied to the CD terminal of 101.

On the other hand, if ATF and A are 4 or less at the timing of PULSS, the AND gate 136 outputs the pulse to the counter P101.
Supplied to the CD terminal of

This is ATF. When A is E1 or more, the playback head 2A advances toward the track, and when A is less than E1 or more than E2, it is t.
tty on track, E! The following cases are considered to be late. That is, if the head 2A is advancing with respect to the track, the counter P101 is counted down once every two field scanning period, and the output of the counter P101 is shifted downward, so that the fixed turn signal is also shifted downward, so that the head 2A, Both 2B are approaching on-track status. Further, if the head 2A is behind the track, the fixed turn signal is similarly shifted upward and the on-track state approaches. This is counter P101 is FG
While counting P, interrupt pulses are counted one by one in two field scanning periods. For example, if the entry position of the head relative to the track is initially shifted by 1/2 TP, the counter P101 counts 24 interrupt pulses, resulting in an on-track state. That is, in this case, the time it takes to become on-track is 48×1/f v, which means that the on-track state can be achieved within 451 seconds. Further, according to the configuration of this example, it is possible to correct the entry position deviation caused by the slip of the capstan with the tape.

Further, by employing such a configuration, even in stay reproduction, it is possible to achieve an on-track state of %4 by shifting the fixed pattern signal, so that extremely good tracking is possible. Furthermore, there is no need to take timing when stopping the tape, and the control of the entire apparatus can be simplified.

Furthermore, as in the example above, the ATF signal is sampled at the timing when the head enters the video area, and this sampling output is used to shift the pattern signal to record the entry position when the head enters the video area. It can be precisely matched on the track. Even when the recording track is not linear, the ATF signal obtained from the reproduction pilot signal at the entry position of the previous video area is used to determine the entry position of the head. At the timing when the head enters the recording track, the head is accurately positioned on the recording track simply by controlling the shifting means using the shifted pattern signal.

Further, following the head for the curvature of the recording track thereafter is performed by the ATF signal supplied to the subtraction circuit 58.

In this way, the pattern signal generating circuit 56 controls the converting elements 3A, 3B so that the reproduction heads 2A, 2B can trace a desired recording track at an arbitrary tape running speed.
The fixed pattern signal for driving the D/A converter 10
6.107.

Note that the OR game) 151 in FIG. 6 outputs a pulse signal when the carry signal or borrow signal of the counter P101 is generated. This means updating the reproduced track, so a track update pulse ( PUL, E). In the case of 4f tracking, each time a reproduced track is updated, the pilot signal obtained from that track and the pilot signals obtained from both adjacent tracks are different, so the signal processing method is different. For example, when processing a pilot signal component in a reproduced signal by multiplying it by a predetermined reference signal, the frequency of the reference signal to be multiplied is different. This switching is performed using PLILSE.

Next, the remaining portions of the conversion element control circuit 55 will be explained using diagram M6. The LPFs 161 and 162 each have a vertical rise W l 71 to prevent the above-mentioned ringing phenomenon in the summer.
The fixed butterfly Δ of 2B is applied to the tic head 2. Reference numeral 59 denotes a DC component removal circuit that uses an integrator 180 to detect the average of the DC components contained in the output signal of the subtraction circuit 58, and removes it using differential amplifiers 181 and 182. The output signals of the differential amplifiers 181 and 182 are passed through amplifiers 191 and 192, LPFs 193 and 194, and high voltage amplifiers 195 and 196, respectively, to terminals 211 and 212.
It is applied to mechanical transducer elements 3A and 3B.

In the above example, the inrush phase control circuit 123 controls the counter P.
Although the pulse supplied to 101 is one pulse per two field periods, the present invention is not limited to this.

For example, 2 pulses every 2 field periods, ATF
It is also possible to determine the supply interval and the number of pulses depending on lA.

In addition, in the above example, we considered accurately tracing an area in a recording track where one field worth of video signal is recorded, but it is also possible to accurately trace an arbitrary predetermined area in a recording track. The present invention is applicable. For example, in a recording track, there is an area before the video area where the digital audio signal that the head traces is recorded, and if you want to accurately trace this audio area, the ATF immediately after the head enters this audio area. By using signals, the audio domain can be accurately traced as well.

In this case, it goes without saying that the video area can also be accurately traced.

As explained above, according to the present invention, the drive signal obtained using the pulse obtained in response to the movement of the recording medium is used to detect the deviation of the head relative to the track at the timing when the head enters a predetermined area. A rotating head type that stabilizes the operation of the shifting means and extremely accurately controls the entry position of the head with respect to a predetermined area of the recording track by shifting the output of a sampled signal indicating the fin. It has become possible to obtain a video signal reproducing device, and as a result, it has become possible to obtain an extremely good variable speed (special) reproducing screen.

[Brief explanation of drawings]

Figure 1 shows a V as an example of a conventional rotary head type playback device.
A diagram showing a schematic configuration of the main parts of the TR, particularly related to the present invention, FIG. 2 is part 4 f of the pattern signal generation circuit in diagram M1.
Figure 3 is a diagram showing the input and output waveforms of each circuit in Figure 2 during 1.5x speed playback, Figure 4 (5) and Figure 4 (the success is during still playback and 1.
A diagram showing the relationship between the center trajectory of the recording track on the tape and the center trajectory of the scanning head during 5x speed playback. is a diagram showing a specific circuit example of the conversion element and control circuit shown in FIG. 5, FIG. 7 is a timing chart showing how each timing signal is generated in FIG. 6, and FIG. Timing chart showing fixed pattern signals during playback, Figure 9, @ indicates forward, reverse 1
A diagram showing the relationship between the recording track on the tape and the trace locus of the playback head at one time in the /3 slot, Figure 10 is a timing chart showing the fixed pattern signal at one time in the forward 1/3 slot, and Figure 11 is a timing chart showing the fixed pattern signal at the time in the forward 1/3 slot. 7 is a timing chart showing a fixed pattern signal during a slot. 1 is a magnetic tape as a recording medium, 2A and 2B are rotary heads for reproduction, 3A and 3B are electro-mechanical conversion elements as transfer means, IO is a capstan included in the transfer means, and 12 is a capstan FG signal. 55 is a conversion control circuit, 56 is a pattern signal generation circuit as a drive signal, 101 is an up/down counter, and 132 is a sample and hold circuit. Applicant Canon Co., Ltd.

Claims (1)

[Claims] An apparatus for reproducing a video signal by tracing a predetermined area of a recording track formed at a predetermined track pitch on a recording medium with a rotary head that is displaced by a displacement means in a direction intersecting the rotating surface of the recording track, the apparatus comprising: , transport means for transporting the recording medium; means for generating a seventh drive signal for driving the displacement means using pulses obtained in connection with the recording medium transport operation of the head transport means; means for generating an error signal indicating a positional deviation between the head and the recording track according to the output; a sampling means for sampling the error signal at a timing when the head enters the predetermined area; and an output of the sampling means. and means for shifting the drive signal level according to the rotational head type video signal reproducing apparatus.