JPH0750522B2 - Rotating head type video signal reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rotary head type video signal reproducing apparatus, and more particularly, to a predetermined area of a recording track formed with a predetermined track pitch on a recording medium transferred by a transfer means. The present invention relates to a rotary head type reproducing device for reproducing a video signal by tracing with a rotary head that is displaced by a displacement means in a direction intersecting the rotation surface,
More specifically, it relates to the control of the above-mentioned shift means when the recording medium is transported and reproduced at a speed different from that at the time of recording, such as high speed reproduction, low speed reproduction and reverse reproduction.

<Description of Prior Art> In a rotary head type video signal reproducing device such as a VTR, high speed reproduction, low speed reproduction (including still reproduction), reverse reproduction, etc. reproduction at an arbitrary recording medium transfer speed different from that at the time of recording (so-called) When performing special playback, in order to prevent the generation of noise bars and enable stable and clear image playback, the playback head must record the video signal of each recording track in each scanning field. It is necessary to trace the existing area accurately.

As one means for realizing such a function, conventionally,
A pattern signal generator that generates a pattern signal according to the distance from the scanning track of the reproducing head to the recording track on the tape at any tape running speed is provided, and the pattern signal obtained from this pattern signal generator is used to reproduce. Means for controlling the displacement means such as an electro-mechanical conversion element (for example, a bimorph element) that displaces the head in the direction intersecting the rotation surface thereof are known. Here, as will be described later in detail with reference to the drawings, the conventionally known pattern signal generating device predicts the distance from the scanning track of the reproducing head to the recording track on the tape on the tape for one frame. Control signal recorded at intervals, that is, so-called CT
It is of the absolute phase type that is detected by the L signal and the capstan FG signal related to the rotation of the capstan as a tape transfer means for effectively dividing the interval of the CTL signal.

On the other hand, in recent years, in order to realize high density recording, a VTR has been proposed in which the above CTL is abolished and the following tracking method is used. That is, a plurality of types (for example, four types) of pilot signals having mutually different frequencies are superposed one by one on the video signal for one field and recorded on the recording medium. Then, this is reproduced by the reproducing head to separate only the pilot signal component. Then, the levels of the pilot signals obtained from the tracks (both adjacent tracks) on both sides of the track (main track) which is mainly traced by the read head are compared to obtain track deviation information of the read head, and this is used for tracking control. It is intended to be a signal (ATF signal). So-called 4f
A VTR that performs method tracking has been proposed.

In the case where the above-mentioned pattern signal is to be obtained in the VTR which carries out the tracking in the 4f system, it is conceivable to form the pattern signal by using the above-mentioned capstan FG signal.

However, unlike the CTL signal, this capstan FG signal does not include information indicating the position of the recording track, and it is not possible for the head to accurately trace the area where the video signal of the recording track is recorded. Can not. That is, when the displacement means is driven by using the pattern signal obtained by using the capstan FG signal in this way, the trace locus of the rotary head shifts in parallel with the recording track. AT obtained from the regenerated pilot signal to correct this shift
It is possible to mix the F signal with the pattern signal to drive the transition means, but the pilot signal is obtained only when the head starts tracing the recording track, and the plunge position to each recording track is not controlled. Since the displacement means is controlled after the entry, the operation of the displacement means is not stable. In addition, it will be against the tape running control circuit by the capstan, and it will be difficult to perform the capstan servo.

<Objects of the Invention> The present invention has been made in view of the above-described drawbacks, and it is possible to stabilize the operation of the displacement means and control the plunge position of the head with respect to a predetermined area of the recording track extremely accurately. It is an object of the present invention to provide a rotary head type video signal reproducing device.

<Explanation by Examples> Hereinafter, the means taken in the present invention for achieving the above-mentioned object will be illustrated and explained by the examples shown in the accompanying drawings.

Prior to the description of the embodiments of the present invention, a conventional VTR will be described.

First, referring to FIG. 1, in the drawing, 1 is a magnetic tape as a recording medium, 2A and 2B are reproducing magnetic heads, which are provided so as to face each other by 180 degrees with the same azimuth angle. , Such as a bimorph element as a conversion means
It is attached to the free ends of the mechanical conversion elements 3A and 3B.
The conversion elements 3A and 3B are attached to the rotary member 4 at their tail ends, and the rotary member 4 is rotated by a head rotation motor 5 as shown by the arrow in the figure. Although not shown in the drawing, as is well known, the heads 2A and 2B are rotated in a state of protruding from a slit between a pair of tape guide drums, and the tape 1 is rotated against the pair of drums.
It is wound diagonally over a range of 180 degrees or more. Reference numeral 6 is a rotational phase detector for detecting the rotational phases of the heads 2A and 2B. The signal from the detector 6 is used as a head switching signal (hereinafter referred to as HSW signal) and attached to the head / motor control circuit 7. Based on the output of the detector 6, the control circuit 7 drives the head motor 5 so as to rotate the heads 2A and 2B at a predetermined phase and a predetermined rotation speed.
It is controlled through the motor drive circuit 8. 9 is a fixed head for reproducing a control signal (hereinafter, CTL head) which reproduces a control signal (hereinafter, CTL signal) recorded in the lower part of the tape at intervals of one frame in the longitudinal direction, 10 is a pinch roller (not shown) A capstan forming a transfer means for transferring the tape 1 in the longitudinal direction in cooperation with each other, 11 a capstan motor for rotating the capstan 10, and 12 a frequency signal corresponding to the rotation of the capstan 10. A frequency signal generator for generating (hereinafter, capstan FG signal), 13 is a predetermined phase and a predetermined rotation of the capstan 10 based on the CTL signal from the CTL head 9 and the capstan FG signal from the frequency signal generator 12. A capstan motor control circuit for controlling the capstan motor 11 through a capstan motor drive circuit 14 so as to rotate by a number.
15 is the HSW signal from the rotary phase detector 6, the CTL signal from the CTL head 9, and the capstan FG from the frequency signal generator 12.
An electro-mechanical device for causing the heads 2A and 2B to trace one recording track on the tape 1 in each scanning field during reproduction at an arbitrary speed (including stationary and reverse rotation) based on the signal. A pattern signal generation circuit that generates a pattern signal for the conversion elements 3A and 3B, and 16 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 generating circuit 15. In the figure, the capstan FG signal from the frequency signal generator 12, the CTL signal from the CTL head 9 and the HSW signal from the rotary phase detector 6 are input to the input terminals 17, 18 and 19, respectively. . 20 is the capstan FG input to terminal 17
A binary counter designed to count the signals and be reset by the CTL signal input to the terminal 18, 21 is the HSW signal based on the HSW signal input to the terminal 19.
A timing signal generation circuit for generating a timing signal synchronized with the signal, 22 is a capstan FG signal that is preset as output preset data PD of the counter 20 by the timing signal from the timing signal generation circuit 21 and is input to the terminal 17. Presettable to count
Binary counter, 23 is the presettable counter
D / A converter for D / A converting the output of 22; 24: Still pattern generator for generating a fixed pattern signal for stale reproduction based on the timing signal from the timing signal generation circuit 21; 25: D / A An adder for adding the output of the A converter 23 and the output of the still pattern generator 24, and 26 is an output terminal for outputting the conversion element control pattern signal which is the output of the adder 25.

Next, the operation of the VTR having the above-described structure during special reproduction will be described with reference to FIGS. 3 and 4, focusing on the operation of the pattern signal generating circuit shown in FIG. In addition, in FIG.
(D) to (g) show the CTL signal, the output of the second illustrated counter 20, and the presettable counter 22 in particular when reproducing at 1.5 times speed.
The output of (or D / A converter 23) and the output of adder 25 are shown respectively, and FIGS. 4 (A) and 4 (B) are on the tape 1 during still playback and 1.5 × speed playback, respectively. 3 shows the relationship between the central locus of the recording tracks and the central locus of scanning of the heads 2A and 2B.

First, when the head motor 5 rotates the heads 2A and 2B, the rotation phase detector 6 outputs HS as shown in FIG. 3 (a).
The W signal is output, while the timing signal generating circuit 21 in the pattern signal generating circuit 15 shown in FIG. 2 synchronizes with each rising and falling of the HSW signal as shown in FIG. 3 (b). The timing signal is output. And based on this timing signal, the still pattern generator 24
From the head, as shown in FIG. 3 (c), the heads 2A and 2B are moved from 0 to -1 track pitch (hereinafter, T
A still pattern signal for continuous conversion up to P) minutes is output.

Now, the so-called field still reproduction in which the field signal of one recording track recorded by the recording head having the same azimuth angle as that of the reproducing heads 2A and 2B is reproduced alternately by both heads 2A and 2B is now attempted. In this case, the relationship of the scanning center loci of the heads 2A and 2B with respect to the recording tracks on the tape 1 at this time is as shown in FIG. 4 (A). That is, in FIG. 4 (A), the solid line indicates the head 2A.
And the center locus of the recording track of the field signal recorded by the recording head having the same azimuth angle as 2B, the broken line indicates the recording of the field signal recorded by the recording head having an azimuth angle different from those of the heads 2A and 2B. In the center of the track, the white arrows indicate the heads 2A and 2B.
The central locus of the scanning of CTL and the recording locus of the CTL signal are indicated by CTL (this is the same in FIG. 4B), and the scanning of the heads 2A and 2B is performed as shown. The center locus (hereinafter referred to as head locus) C of the track is the center locus (hereinafter referred to as track locus) a of the track to be reproduced, and the start end of the track locus a and the end of the track locus b of the adjacent track on the left side are paired. It becomes a line segment that connects corners. Therefore, in order to correct this and to match the head locus c with the track locus a, if the heads 2A and 2B are set to + in the running direction of the tape 1 at the time of recording and − in the opposite direction, within one field scan. 0
It is understood that it is sufficient to continuously change from 1 to −1 TP.

From the above, the still pattern generator shown in FIG.
It can be seen that the still pattern signal from 24 is sufficient to meet the required displacement of heads 2A and 2B for field still reproduction.

On the other hand, the capstan by the capstan motor 11
The capstan FG signal output from the frequency signal generator 12 with the rotation of 10 is the pattern signal generation circuit 15 shown in FIG.
Counters 20 and 22 in
20 and 22 are to count the capstan FG signal, but here, the counter 20 is the CTL head 9
Since it is reset every 1 frame by the CTL signal from, the count output is up to the count value of +2 track pitch, and the CTL signal becomes as shown in Fig. 3 (d) during 1.5x speed reproduction. It becomes like FIG. 3 (e). And, on the other hand, the presettable counter 22
Counts the capstan FG signal while presetting the output of the counter 20 at that time by the timing signal (FIG. 3 (b)) from the timing signal generation circuit 21, so the count output (or D / A conversion) The output of the device 23) is as shown in FIG. Therefore, as a result of adding the output of the D / A converter 23 and the output of the still pattern generator 24 at this time from the adder 25, a pattern signal as shown in FIG. Is output.

Note that the outputs of the counters 20 and 22 and the adder 25 actually include stepwise changes because the counters 20 and 22 count the capstan FG signal, but they are shown in simplified form in the figure. is there.

Here, the head loci of the heads 2A and 2B with respect to the track locus on the tape 1 at the time of 1.5 × speed reproduction are as shown in FIG. 4 (B). That is, in the figure, A ₁ A ₂ , A ₃ ... is the head 2A
The head locus of B ₁ , B ₂ , B ₃ ... is recorded by the head locus of head 2B, and a ₁ , a ₂ , a ₃ ... is recorded by the recording head having the same azimuth angle as heads 2A and 2B. Shows the track locus of the field track. In the first field, in order to match the head locus A ₁ with the track locus a ₁ , the head 2A changes from 0 to +0.5 TP within the first field scan. Must be continuously given, and in order to match the head locus B ₁ with the track locus a ₁ in the second field, the head 2B must be + 1.5T within the scanning of the second field.
It is necessary to continuously give a transition from P minutes to +2 TP minutes, and in order to match the head locus A ₂ to the next next track locus a ₂ in the 3rd field, from the +1 TP minute to the head 2A within the scanning of the 3rd field. It is necessary to continuously give a shift of up to + 1.5TP, and in the 4th field the head locus B ₂
In order to match the next track locus a ₃ to the head 2B, it is necessary to continuously give a displacement from +0.5 TP to +1 TP in the scanning of the fourth field to the head 2B.
Although it is repeated in the field cycle, it is understood that the pattern signal shown in FIG. 3 (g) satisfies the necessary displacement of the heads 2A and 2B.

The above description is based on the case of 1.5x speed reproduction, but the pattern signal for controlling the heads 2A and 2B corresponding to it at any reproduction speed not limited to 1.5x speed is output from the pattern signal generation circuit 15 described above. can get.

The pattern signal thus obtained from the pattern signal generation circuit 15 is applied to the conversion element drive circuit 16, and the drive circuit
Reference numeral 16 denotes an electro-mechanical conversion element 3A and an electro-mechanical conversion element 3A for making the heads 2A and 2B on-track with respect to the track to be reproduced based on the pattern signal and the HSW signal from the rotary phase detector 6.
It comes to drive 3B.

In the conventional device, as described above, the pattern signal for head control corresponding to that at the time of reproducing at an arbitrary speed is obtained. Here, in the conventional device, the pattern signal is obtained. It is clear that the CTL signal is indispensable for the formation of the signal, so that it is completely ineffective in a system that does not use the CTL signal.

On the other hand, the present invention does not use the CTL signal at all,
A pattern signal for head control corresponding to the reproduction at an arbitrary speed is obtained, and one embodiment thereof will be described below.

FIG. 5 is a block diagram mainly showing the outline of the configuration of the special reproduction system section of the VTR as an embodiment of the present invention. Fifth
In the figure, the same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In other words, CTLs with numbers 1 to 14
Since no signal is used, the components are almost the same as the conventional VTR shown in FIG. 1 except that the CTL head 9 is not provided.

In the VTR of the embodiment shown in FIG. 5, the following method is used instead of the tracking method using the CTL signal. That is, a plurality of types (for example, four types) of pilot signals having mutually different frequencies are superposed one by one on the video signal for one field and recorded on the recording medium. Then, this is reproduced by the reproducing head to separate only the pilot signal component.

Then, the levels of the pilot signals obtained from the tracks (both adjacent tracks) on both sides of the track (main track) which is mainly traced by the read head are compared to obtain track deviation information of the read head, and this is used for tracking control. It is a signal. That is, the well-known 4f method tracking is performed.

The functions of the respective units in FIG. 5 will be briefly described below.

The reproduced signals obtained from the reproducing heads 2A and 2B include the video signal and the tracking pilot signal as described above. This reproduction signal is amplified by the reproduction amplifier 51 and made into a continuous signal by the HSW signal, and is supplied to the video signal reproduction processing circuit 52 and the tracking signal generation circuit 53. The video signal reproduction processing circuit 52 separates the video signal from the output signal of the reproduction amplifier 51, performs processing such as demodulation and supplies the reproduction video signal of the above signal form to the output terminal 50.

On the other hand, in the tracking signal generation circuit 53, the pilot signal component is separated from the output signal of the reproduction amplifier 51, the levels of the pilot signals obtained from both adjacent tracks are compared, and a well-known process for obtaining a tracking control signal is performed. It is a thing.

Reference numeral 54 is a system control circuit for controlling the operation of each part of the device according to the operation mode of the device. For example, the head motor control circuit 7, the capstan motor control circuit 13, the tracking signal generation circuit 53, and the pattern signal generation circuit to be described later have different operations during recording and reproduction, and also depending on the designated tape speed and the like. ,
These generate control signals so that desired operation can be performed in each operation mode.

55 is a conversion element control circuit, which is a pattern signal generation circuit
56, a low pass filter (LPF) 57, a subtraction circuit 58, a DC component removal circuit 59 and a conversion element drive circuit 60. By the output of the conversion element control circuit 55, the electro-mechanical conversion elements 3A and 3B described above are reproduced by the reproducing head 2 in each scanning field.
A and 2B are driven so as to accurately trace one recording track.

FIG. 6 is a diagram showing a detailed structure of the conversion element control circuit 55. The operation of generating conversion element control pattern signals and driving them will be described below with reference to FIG.

The pattern signal generation circuit 56 includes a counter P101 and a counter A102.
And a counter B103, which are up-down parallel input up-down counters. The input indicated by CD of each counter is a countdown input terminal, and the CU is a countup input terminal. In this example, a binary counter will be used.

Now, the fixed pattern signal required to realize the noiseless special reproduction as described above is the information (phase information) for accurately matching the plunge position of the reproducing head with respect to the reproducing track, which changes as the tape runs. And the information (speed information) for matching the inclination of the reproduction track with the trace locus of the reproduction head corresponding to the running speed of the tape.

In the pattern signal generation circuit 56 shown in FIG. 6, the counter P101 outputs the phase information, the counter A102 and the counter B1.
03 is for obtaining speed information.

First, the operation centered on the counter P101 for obtaining the phase information will be described. Counter P101 is 2 of the number (n) of capstan FG signals generated when the tape moves by 2TP.
When the number is doubled (2n), the carry is carried and the carry signal is output from the CR terminal shown. Then, this carry signal is supplied to the reset terminal (indicated by R in the figure) to reset the counter P101. Similarly, when the counter P101 counts down 2n times, it carries a digit down and outputs a borrow signal from the BR terminal shown in the figure. This borrow signal is supplied to the preset terminal (indicated by PR in the figure), and the counter P101 outputs preset data (2
equivalent to n).

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

209 is an input terminal for the capstan FG signal, 111 is a frequency doubler that generates a pulse at the rising and falling edges of the capstan FG signal, and 112 is a pulse generator B that narrows the pulse width of the output pulse of the doubler 111. Is. 208 is a high level when the tape 1 is running in the positive direction (same direction as when recording) from the system control circuit 54, and a negative level (reverse direction when recording)
This is a terminal to which a low-level signal (hereinafter referred to as F / R signal) is supplied when traveling to. F / R signal is AND gate 1
It is supplied to the AND gate 115 via 14 and the inverter 116. Therefore, the output pulse of the pulse generator B112 is supplied to the CD terminal of the counter P101 via the AND gate 114 and the OR gate 138 when the tape is traveling in the positive direction, and the AND gate 115 and the gate when the tape is traveling in the negative direction. It is supplied to the CU terminal of the counter P101 via the OR gate 137.

With this configuration, the output data of the counter P101 is relative to the track to be reproduced on the running tape (the track recorded by the head having the same azimuth angle as the heads 2A and 2B) and the plunge position of the reproducing head. Positional deviation (relative phase information) is always indicated, and it is possible to control each plunge position of each reproducing head. However, since this phase information is only relative phase information, it is effective only when the immediately preceding reproducing head plunge position matches the reproducing track. On the other hand, in the device using the conventional CTL as shown in Fig. 1, C
The rush phase of the reproducing head could be obtained as absolute phase information according to the recording position of the TL device.

Therefore, in this example, the preliminary counter P101 generates the relative phase information as described above, and at the same time, the plunge position of the reproducing head is matched with the reproducing track. This role is handled by the inrush phase control circuit shown in FIG.
By generating an absolute phase adjusting pulse 23, even if the plunge position of the reproducing head does not coincide with the reproducing track, control is performed so as to make it coincide. The inrush phase control circuit 123 will be described in detail after the description of the entire pattern generation circuit 56.

By the way, the pulse signal which is counted up or down by the counter P101 is obtained by doubling the capstan FG signal, which is done in order to improve the accuracy of the above-mentioned phase information. That is, the TP becomes narrower as the recording density becomes higher, and the number of capstan FG signals generated for the TP is prevented from decreasing to prevent the phase information from becoming coarse.

In addition, the pulse width is narrowed in the pulse generation circuit B112 is
As will be apparent from the explanation below, because each counter has the opportunity to count up or down multiple pulse signals, and the counter is configured to perform operations equivalent to addition and subtraction. is there.

That is, the pulse generation circuit B112 is provided for the purpose of reducing the probability that a plurality of pulse signals are input at exactly the same timing and one of them cannot be counted. The pulse generating circuit A131 and the pulse generating circuit C113 are also provided for the same purpose, and the description thereof will be omitted in the following description.

As described above, the counter P101 counts down the pulse related to the capstan FG signal at that time when the tape is running in the forward direction, and counts it up when running in the reverse direction, so the tape running Regardless of the direction, the relative phase information of the plunge position is outputted when plunging into the reproducing track of the reproducing head at that moment. For example, when the tape is run in the forward direction at a tape speed that is 1/3 of the recording speed and slow motion playback is performed (hereinafter referred to as the positive 1/3 slow), it is 1/3 times the recording speed in the reverse direction. When the tape is run at the tape speed of and the throw is performed (hereinafter referred to as the reverse 1/3 throw)
In case of slow, counter P101 every 6 field scanning period
Output is repeated 48 → 0, and in the case of reverse 1/3 throw, 0 → 48 is repeated every 6 field scanning period. If, for example, 16 is obtained as the output of the head inrush counter P101, the inrush position with respect to the reproducing track of the reproducing head at that time is a positive 1/3 throw, assuming that the displacement amount of the conversion element is 0. Also in the case of the reverse 1/3 throw, the position is shifted by 2 / 3TP in the negative direction from the playback track.

Further, the required number of bits of the counter P101 is the number of bits (6 bits in this example) required to represent 2n (48 in this example) in binary in the case of a binary counter.

By thus reading the data obtained by the counter P101 at a predetermined timing accompanying the rotation of the rotary head, it is possible to obtain the rush phase information of the read head with respect to the playback track. Therefore, the operations of the counter A102 and the counter B103 that operate using this will be described next.

The counter A102 and the counter B103 are counters for outputting a fixed pattern signal including the phase information and speed information as described above as digital data. Also counter
In addition to the phase information obtained by the counter P101, the A102 and the counter B103 show the reproduction track and the trace locus of the reproduction head, which are generated when the reproduction head 2A, 2B scans the tape at a speed different from that during recording. It is for generating the above-mentioned speed information for correcting the difference in inclination.
Although the number of bits of the counter A102 and the counter B103 is 10 bits in this example, it is determined by the required amount of conversion element conversion, that is, the maximum tape speed during high-speed search reproduction that is desired. .

Counter A102 and counter B103 are head 2A and head 2 respectively.
The output data of the counter P101 is loaded as the lower 6-bit data at a predetermined timing related to the rotation of B. A signal for determining the load timing is obtained according to the HSW signal, the load signal (PUL, A) of the counter A102 is input from the terminal 302, and the load signal (PUL, B) of the counter B103 is input from the terminal 204. . PUL, A and PUL, B are input to preset terminals (represented by PR in the figure) of counter A102 and counter B103, respectively. When head 2A and head 2B are rotating 180 degrees out of phase, PUL,
It goes without saying that A, PUL, and B are also input 180 degrees out of phase.

When PUL, A, PUL and B are input to PR respectively, counter A10
2. The counter B103 is loaded with initial data.
As described above, the lower 6-bit initial data is the counter
The output data of P101 is used, but the upper 4 bits are generated by the preset data generation circuit 105. In this embodiment, the data supplied from the circuit 105 is 1000. This is because the output data of the counter A102 and the counter B103 is D / A as so-called offset binary data.
When converting, the output is aimed to be close to 0 level. That is, in this case, the initial data loaded is from 1000000000 to 1000110000, and the initial data is near 0, which is desirable because a DC component as described later does not occur so much. By the way, it is more preferable to change the output data of the preset data generation circuit 105 according to the running speed of the designated tape from the idea that the direct current component is not generated. That is, for example, 1011 may be generated by the circuit 105 when the tape is run at 10 times normal speed, and 0101 may be generated by the circuit 105 when the tape is run at 6 times reverse speed.

The counter A102 and the counter B103, to which the initial data are input as described above, count the pulses having a narrow pulse width having the frequency twice that of the capstan FG signal generated by the pulse generation circuit B112, like the counter P101 described above. . Further, the counter A102 and the counter B103 are clock pulse signals (C
L) is counted through the pulse generation circuit C113.

Here, the clock pulse output from the pulse generation circuit C113 is always guided to the CU terminals of both counters A and B. The output pulse of the pulse generation circuit B112 is configured to be guided to the CD terminals of the counters A and B when the tape is running in the positive direction and to the CU terminals of the counters A and B when the tape is running to the negative direction. There is. This is because, as is well known, the difference in inclination between the trace locus of the reproducing head and the reproducing track differs depending on the traveling direction even if the tape traveling speed is the same. For example, when the tape running speed during recording is v, the tape speed during playback is Nv.
Assuming that N is a positive speed and N is a negative speed, the head displacement required by the reproducing head during one field period is proportional to (N-1) times TP. Become.
This means that the inclination of the fixed pattern signal to be obtained is proportional to (1-N) to correct it.

Since the frequency of the output pulse of the pulse generating circuit B112 is proportional to the absolute value of the tape running speed, the inclination proportional to N is obtained by counting this. At this time, if the tape running is in the positive direction, the countdown is performed, and if it is in the negative direction, the countup is performed to obtain a slope proportional to (-N). On the other hand, since the slope required to displace the reproducing head by 1 TP in one field period is proportional to 1, the slope can be increased by counting up the number of pulses (48 in this example) corresponding to 1 TP in one field period. Get +1. And if you do these at the same time (1-N)
It is possible to obtain a desired slope proportional to. Therefore, the frequency of the clock pulse generated by the pulse generation circuit C is
It means fv x 48 (Hz). However, fv is a field scanning frequency.

The terminal 206 is a terminal to which a rectangular wave signal (PUL, C) for designating the period in which the counter A102 counts each pulse described above is supplied, and PUL, C are AND gates 117 and 119.
And gate each pulse. The other terminal 207 is a terminal to which a rectangular wave signal (PUL, D) for designating a period in which the counter B103 counts each pulse is supplied.
UL and D similarly AND gates 118 and 120 to gate each pulse. Reference numeral 121 is an OR gate for guiding both the output pulse of the pulse generating circuit B112 and the clock pulse output by the pulse generating circuit C113 to the counter A102 and the counter B103.

In this way, the counter A102 and the counter B103 take in initial data from the counter P101 for determining the plunge position of the head during the period when the reproducing heads 2A and 2B trace the recording track on the tape, respectively, and A fixed pattern signal for the reproducing head to accurately trace a desired recording track when the tape is running at an arbitrary speed by counting each pulse so as to obtain a slope proportional to the trace between the trace locus and the recording track. Can be generated as digital data.

Next, how each timing signal is generated in this example will be described in detail with reference to the timing chart of FIG. In FIG. 7, (a) is an HSW signal, and is a period during which the reproducing head 2A reproduces a video signal for one field on each recording track when the reproducing head 2A is at a high level and the reproducing head 2B is at a low level. Are shown respectively. This HSW signal is 30Hz when fv is 60Hz.
Is a rectangular wave signal of, and is supplied to each part of the apparatus as a 30 Hz timing pulse related to the rotation of the head, a so-called 30 PG. (B) shows the capstan FG signal, and (C) shows the pulse (FGP) generated by the pulse generation circuit B112 in relation to this capstan FG signal. There is. (D) is a pulse (CLP) generated from the pulse generation circuit C113 by narrowing the clock pulse (CL) input from the terminal 210, and (e) is a 60 Hz timing pulse (60PG) phase-locked with the HSW signal. (F) is terminal 20
Square wave signal (PUL, C), (G) supplied to 6 is terminal 20
7 is a square wave signal (PUL, D), (H) is a pulse (PUL, A) supplied to the terminal 202 for presetting the counter A 102, and (L) is for presetting the counter B 103. Pulse (PUL, B) supplied to terminal 204 at
(Nu) is a sampling pulse supplied to the terminal 205,
(L) is an analog display of the output data of the counter P101, and (W) is the pulse output from the terminal 203 (PUL,
E).

Since the HSW signal (a) is a high level period during which the reproducing head 2A reproduces the video signal for one field of each recording track, the effective period of the fixed pattern signal (the phase information and the speed information described above are originally This period alone is enough to include the period). However, as described above, the electromechanical conversion element causes a resonance (ringing) phenomenon in response to a rapid change in the applied voltage. Further, in one recording track, there is an area where other signals (for example, digital audio signals) are recorded in addition to the area where the video signal for one field is recorded. Furthermore, the tracking control signal must be obtained from the area in which other signals are recorded. For this reason, in this example, the effective period of the fixed pattern signal, that is, the counter A1
A period in which 02 can count the outputs of the pulse generating circuit B112 and the pulse generating circuit C113 is a period in which the HSW signal is at a high level and a 1/2 field scanning period immediately before that. This period is given as a high level period of PUL and C (f). The PUL and C (f) can be easily formed by a logic circuit (not shown) by the HSW signal (a) and 60PG (e). PU
L and D (g) are formed as shown in FIG. 7 for the same reason.

The timing of fetching the initial data of counter A102 and counter B103 is the pulse PU input to the PR terminal of each counter.
Determined by L, A (re), PUL, B (h). 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 the prevention of the ringing phenomenon described above, the period immediately before the effective period of the fixed pattern signal is set so as not to cause a large level change in the fixed pattern signal. For this PUL, A (re) and PUL, B (h), for example, PU
It may be formed by using the falling edges of L, C (f), PUL, and D (g). The PUL, S (nu) and PUL, E (wo) will be described in detail later.

Further, the fixed pattern signal generated in this example will be illustrated and described by specifically setting the tape traveling speed. FIG. 8 is a timing chart showing fixed pattern signals (vi) and (vii) when the tape running speed is 0 (so-called still reproduction) and at the same time as recording (so-called standard reproduction).
The FG and FGP shown in FIGS. 8 (ii) and (iii) are those at the time of standard playback, respectively. 8 (vi) and (vii) are counter A.
This is an analog display of the output data of 102. During still playback, FGP is not generated, and only CLP is counted by counter A102 and counter B103.
Therefore, the output of the counter A102 is as shown in FIG. 8 (vi). Further, since the output data of the counter P101 is always a constant number, the output of the counter B103 has the same waveform as in FIG. 8 (vi), but the phase is different by 180 °. On the other hand, during standard playback, the FGP and CLP have the same frequency as shown in the figure, and the counter A102
Also, the counter B103 counts down FGP and counts up CLP within the valid period of the fixed pattern, so that their outputs are substantially unchanged.

At this time, the counter B outputs the counter A102 (vii).
The output of is a waveform shifted by the level that drives the conversion element for 1TP. This is because the timing of fetching the value of the counter P101 is different for one field scanning period, during which the counter P101 is
This is because FTP is counted for 1 TP.

9 (A) and 9 (B) are diagrams showing the relationship between the recording track on the tape and the trace locus of the reproducing head at the forward / reverse 1/3 throw, and FIG. 10 is the fixed at the forward 1/3 throw. FIG. 11 is a timing chart showing the pattern signal (v), and FIG. 11 is a timing chart showing the fixed pattern signal (v) at the reverse 1/3 slow.

In FIGS. 9A and 9B, A ₀ , A ₁ and A ₂ are the center lines of recording tracks recorded by the heads having the same azimuth angle as the reproducing heads 2A and 2B, and B ₀ and B, respectively. ₁ for each playback head 2A
And 2B is a center line of a recording track recorded by a head having an azimuth angle different from 2B. On the other hand, a _{1 to} a ₆ are conversion elements 3A
The center line of the trace locus of the head 2A when the displacement by 0 is ₀ , b _{0 to} b ₅ are the center lines of the trace locus of the head 2B when the displacement by the conversion element 3B is 0, and X indicates the running of the tape. It is an arrow.

As is well known, in the normal 1/3 slow and reverse 1/3 slow, every other recording track is traced 6 times and reproduced.
For example, in FIG. 9 (A), the recording track A _{1 is set} to b ₁ , a ₂ ,
Trace 6 times of b ₂ , a ₃ , b ₃ and a ₄ . A and B in FIG. 10 (v) are fixed patterns (the analog output data of the counter A102 and the counter B103 are displayed) generated by this example, and P is the analog display of the output data of the counter P. It is a thing.

Taking as an example the operation of aligning the locus a ₂ of FIG. 9 (A) with the track A ₁ , the output of the counter P is taken into the counter A at the point u shown in FIG. 10, and the counter A is taken at the point v. Counting is started, the counting is stopped at point w, and the force of the counter P is taken again. By repeating this, the desired fixed pattern signal can be obtained in FIG. 9 (A).
It will be clear from the comparison with.

Also in FIG. 11 (v), A and B are fixed patterns generated in this example, and P is an analog display of the output data of the counter P. Similarly, at the point u, the output data of the counter P is transferred to the counter A. It takes in, starts counting at point v, stops counting at point w, and takes in the output of the counter P again. It is also clear from comparison with FIG. 9 (B) that the fixed pattern signal shown in FIG. 11 is a desired fixed pattern signal.

As described above, the trace locus of the head can be matched with the recording track, but as described above, the phase information is relative only with this. So, next, match the plunge position of the reproducing head with the recording track to be reproduced,
Inrush phase control circuit 123 that makes phase information closer to absolute information
Will be described.

In this example, a tracking control signal is used to match the inrush phases. This tracking control signal is supplied from the above-mentioned tracking control circuit 53. In this example, the reproducing head 2 is used to perform the above-mentioned 4f system tracking.
While the reproduction signal is being obtained from each of A and 2B, the tracking control signal can always be obtained for each head. Also in this example, as is clear from FIGS. 5 and 6, the tracking control signals (ATF,
A, ATF, B) are subtracted from the fixed pattern signals for heads 2A, 2B. This is a conversion element using only fixed pattern signals
Since the deviation between the trace loci of the reproducing heads 2A and 2B and the tracks when driving 3A and 3B is corrected, this AT
The fixed pattern signal may be shifted by F, A or ATF, B.

ATF and A input to the terminal 201A are timings indicating the start timing of each scan field in the sample hold circuit (S / H) 132, that is, the timing at which the rotary head rushes into the area where the video signal of the recording track is recorded. The pulse (PUL, S) is sampled and held as a sampling pulse. The timing of PUL and S is as shown in FIG. The output of this S / H132 is the comparator 133,
The voltage is supplied to a voltage detection circuit composed of 134 and resistors R ₁ , R ₂ , and R ₃ , and a high level output is obtained from the comparator 133 when the voltage is equal to or higher than the predetermined voltage E _1, and a comparator when the voltage is equal to or lower than the predetermined voltage E ₂ lower than E _1. Higher level output than 134.

The output of the comparator 133 is supplied to the AND gate 135, and the output of the comparator 134 is supplied to the AND gate 136 to gate the pulse from the pulse generation circuit A131. Pulse generator
A131 narrows the pulse width of the above PUL and A and supplies it to the AND gates 135 and 136. If ATF and A are PUL and S and E ₁ or more, AND gate 135 counts pulses P
Supply to the 101 CD terminal. On the other hand, if ATF and A are equal to or less than E ₂ at the timing of PUL and S, the AND gate 136 supplies a pulse to the CU terminal of the counter P101.

This is based on the judgment that the reproducing head 2A is ahead of the track when ATF and A are E ₁ or more, is almost on-track when E ₁ or less and E ₂ or more, and is delayed when E ₂ or less. . That is, if the head 2A moves ahead of the track, the counter P101
Is counted down once every two field scanning periods, and the output of the counter P101 is shifted downward, so that the fixed pattern signal is also shifted downward, so that both heads 2A and 2B approach the on-track state. Further, if the head 2A is behind the track, the fixed pattern signal is similarly shifted upward and approaches the on-track state. This is counter P101
1 in every 2 field scanning period while counting FGP
It is executed in the form of counting interrupt pulses one by one. For example, if the rush position of the head with respect to the track is deviated by 1 / 2TP in the initial stage, the counter P101 counts 24 interrupt pulses, and the on-track state is set. In other words, in this case, the time until it becomes on-track becomes 48 × 1 / fv, and it can be pulled into the on-track state within 1 second. Further, according to the configuration of the present example, it is of course possible to correct the plunge position shift caused by the slip of the capstan with the tape.

Further, by adopting such a configuration, even in the still reproduction, the fixed pattern signal can be shifted to bring it into the on-track state, so that extremely good tracking becomes possible. Further, it is not necessary to take timing when stopping the tape, and the control of the entire apparatus can be simplified.

Further, as in the above example, the ATF signal is sampled at the timing when the head enters the video area, and the pattern signal is shifted using this sampling output to record the entry position when the head enters the video area. Can be matched exactly on the track. In other words, even if the recording track is not linear, the AT obtained from the reproduction pilot signal at the plunge position of the video area one or two before
Since the plunge position of the head is determined using the F signal,
At the timing of entering the video area, the head is exactly on the recording track only by controlling the shift means with the shifted pattern signal.

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

In this manner, the pattern signal generating circuit 56 outputs a fixed pattern signal for driving the conversion elements 3A, 3B so that the reproducing heads 2A, 2B can trace a desired recording track at an arbitrary tape running speed. It can be generated via the / A converters 106 and 107.

The OR gate 151 in FIG. 6 outputs a pulse signal when the carry signal or borrow signal of the counter P101 is generated. Since this means updating the reproduced track, the track control pulse (PU
Supply as L, E). In the case of the 4f system tracking, the pilot signal obtained from that track and the pilot signal obtained from both adjacent tracks are different every time the reproduction track is updated, and thus the signal management method is different. For example, when the pilot signal component in the reproduced signal is multiplied by a predetermined reference signal for processing, the frequency of the reference signal to be multiplied is different. This switching is performed by using these PUL and E.

Next, the remaining portion of the conversion element control circuit 55 will be described with reference to FIG. The LPFs 161 and 162 respectively remove the high frequency component of the fixed pattern signal in order to further prevent the above ringing phenomenon. The subtracters 171, 172 subtract ATF, A and ATF, B from the fixed pattern signals of the heads 2A, 2B, respectively. 59 is an integrator 180 that detects the average of the DC components contained in the output signal of the subtraction circuit 58,
Is a DC component removing circuit for removing the DC component. Differential amplifier
Output signals of 181 and 182 are applied to electro-mechanical conversion elements 3A and 3B from terminals 211 and 212 via amplifiers 191,192, LPFs 193,194 and high voltage amplifiers 195,196, respectively.

In the above example, the inrush phase control circuit 123 uses the counter P101.
The pulse supplied to 1 pulse was set to 1 pulse in 2 field periods, but the pulse is not limited to this. For example, it is possible to set two pulses for every two field periods, or to determine the supply interval and the number of pulses according to ATF and A.

Further, in the above example, it is considered that the area where the video signal for one field is recorded in the recording track is accurately traced. However, the present invention is also applicable to the case where it is desired to accurately trace an arbitrary predetermined area in the recording track. Is applicable. For example, in the recording track, there is an area where the digital audio signal traced by the head is recorded before the video area, and if you want to trace this audio area accurately, the area immediately after the head plunges into this audio area.
By using the ATF signal, the audio area can be accurately traced as well. In this case, it goes without saying that the video area can also be traced accurately.

<Explanation of Effect> As described above, according to the present invention, the drive signal obtained by using the pulse obtained according to the transfer of the recording medium shifts the head with respect to the track at the timing when the head plunges into a predetermined area. A rotary head type video signal reproduction capable of stabilizing the operation of the transition means and controlling the plunge position of the head with respect to a predetermined area of the recording track extremely accurately by shifting the signal indicating the quantity using the sampled output. The device can be obtained, and as a result, a very good variable speed (special) reproduction screen can be obtained.

[Brief description of drawings]

FIG. 1 shows a VT as an example of a conventional rotary head reproducing apparatus.
FIG. 2 is a block diagram showing a schematic configuration of a main part of R, particularly relevant to the present invention, FIG. 2 is a block diagram showing a specific example of the pattern signal generating circuit in FIG. 1, and FIG. Shows the input and output waveforms at 1.5 times speed reproduction of Fig. 4, Fig. 4 (A) and Fig. 4 (B) at still reproduction and 1.
FIG. 6 is a diagram showing the relationship between the center locus of scanning of the head and the center locus of recording tracks on the tape during 5 × speed reproduction; FIG. 5 is a diagram showing the essential structure of a VTR as one embodiment of the present invention; 5 is a diagram showing a concrete circuit example of the conversion element control circuit shown in FIG. 5, FIG. 7 is a timing chart showing how each timing signal is generated in FIG. 6, and FIG. 8 is a still reproduction and standard reproduction. 10 is a timing chart showing a fixed pattern signal at the time, FIGS. 9 (A) and 9 (B) are diagrams showing the relationship between the recording track on the tape and the trace locus of the reproducing head at the time of forward / reverse 1/3 throw, FIG. FIG. 11 is a timing chart showing a fixed pattern signal at a positive 1/3 throw, and FIG. 11 is a timing chart showing a fixed pattern signal at a reverse 1/3 throw. Reference numeral 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 displacement means, 10 is a capstan included in the transfer means, and 12 is a capstan FG signal. Is a rotation detection element, 55 is a conversion element control circuit, 56 is a pattern signal generation circuit as a drive signal, 101 is an up / down counter, and 132 is a sample hold circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Takei, Inventor Masahiro Takeno, 770 Shimonoge, Takatsu-ku, Kawasaki, Kanagawa Canon Inc., Tamagawa Plant (72) Kenichi Nagasawa 770, Shimonoge, Takatsu-ku, Kawasaki, Kanagawa Tamagawa Plant (56) References Japanese Patent Laid-Open No. Sho 56-80821 (JP, A) Actual exploitation Sho 57-200978 (JP, U)

Claims (1)

[Claims] 1. A device for reproducing a video signal by tracing a predetermined area of a recording track formed on a recording medium with a predetermined track pitch by a rotary head which is displaced by a displacement means in a direction intersecting with a rotation surface thereof. A transfer unit configured to transfer the recording medium; a unit configured to generate a drive signal for driving the displacement unit using a pulse obtained in connection with a recording medium transfer operation of the transfer unit; Means for generating an error signal indicating a positional deviation between the head and the recording track in accordance with the output of, a sampling means for sampling the error signal at a timing when the head plunges into the predetermined area, and a sampling means According to the output, the drive signal level is increased by a predetermined amount at the timing when the head enters the predetermined area. Rotary head comprising a means for shift-type video signal reproducing apparatus.