JPH0670845B2 - Rotating head type video signal reproducing device - Google Patents

Description

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

<Prior Art> A rotary head type video signal reproducing apparatus is a magnetic recording / reproducing apparatus (hereinafter referred to as a VTR, which records a video signal while sequentially forming diagonal tracks on a magnetic tape and reproduces it by two rotating heads. This VTR will be described below as an example in the present specification.

With the recent trend toward higher density recording in VTR, many tracking methods have been considered to accurately correct the deviation (tracking error) of the reproducing head from the recording track in order to faithfully trace the recording track. .
As one of the tracking methods, four kinds of pilot signals having different frequencies are sequentially superimposed and recorded on a video signal for one field, and a reproduction track (main track) mainly traced by a head during reproduction and both adjacent tracks There is a method of reproducing a pilot signal from a track and performing tracking using these reproduced pilot signals.
This method can detect a tracking error by comparing the levels of pilot signal components reproduced from both adjacent tracks.

On the other hand, along with the diversification of VTR applications, the number of so-called special playback models such as still image playback, slow motion playback, high-speed search playback, etc., where magnetic tape is run at a speed different from that during recording, is also increasing. In order to prevent the generation of noise bars and reproduce safe and clear images when performing special playback of this kind, make sure that the playback head accurately traces one track without crossing multiple tracks. There is a need.
As one method for realizing such a function, a pattern signal generator for generating a pattern signal according to the distance from the operation track of the reproducing head to the recording track on the tape at an arbitrary tape traveling speed is provided, There is known a method of controlling a displacement means such as an electro-mechanical conversion element (for example, a bimorph element) which displaces a reproducing head in a direction orthogonal to a rotation surface of the reproducing head by a pattern signal obtained from the pattern signal generator.

A tracking error naturally occurs when a variable-speed reproduced image without noise is obtained by the above method. A conventional tracking method for correcting this tracking error is to record a control signal (CTL) that is synchronized with the vertical synchronizing signal of the video signal at one end of the magnetic tape at the time of recording, and reproduce this at the time of reproduction. Such a tracking error is detected, and the tape transfer means such as a capstan and the above-mentioned displacement means are controlled. However, with such a tracking method, tracking takes time. In particular, when the tape is run at a low speed such as when playing back in slow motion, the time interval for playing back the CTL becomes long and the time required for tracking becomes very long. Furthermore, tracking cannot be performed by this method during still reproduction.

Therefore, in order to always obtain the tracking error signal, it is possible to perform the tracking during the variable speed reproduction by using the pilot signal as described above.

However, when performing variable speed reproduction using the above-mentioned shift means in this type of VTR, tracking control cannot be performed until the reproducing head actually traces the track because there is no CTL signal. Therefore, in the initial stage, the center line of the recording track and the center of the trace locus of the reproducing rotary head are parallel to each other, but deviated in the medium traveling direction.

Generally, after the trace is started, the capstan is controlled by using the above-mentioned ATF signal, but it takes some time to follow. Therefore, it is conceivable to add the above-mentioned ATF signal to the pattern signal during variable speed reproduction, but this ATF signal is obtained only when the reproducing circuit head starts tracing the tape. Therefore, as described above, in the case where the trace locus of the reproducing head is always displaced from the recording track in a fixed direction, tracking must be performed for each trace of each track, and the transition means is set to ATF immediately after the start of tracing. Since it is driven by a signal, the transition means cannot perform stable operation. Moreover, tracking is not always taken at the start of tracing, which causes deterioration of the reproduced image.

<Objects of the Invention> The present invention has been made in view of the above-described drawbacks, and it is possible to control the plunge position of the rotary head before it plunges into a recording track, and good tracking can be obtained even immediately after plunge. Moreover, it is an object of the present invention to provide a rotary head type video signal reproducing device which can obtain a high quality variable speed reproduction screen by making the shifting means operate stably.

<Description Using Embodiments> Hereinafter, means taken in the present invention to achieve the above-mentioned object will be illustrated and described with reference to embodiments 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, Electricity such as bimorph element as 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 figure, 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.
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, HSW signal) and is also attached to the 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 at a predetermined phase and a predetermined rotation speed. Reference numeral 9 is a fixed head for reproducing a control signal (hereinafter, CTL signal) which reproduces a control signal (hereinafter, CTL signal) recorded in the lower portion of the tape at intervals of one frame in the longitudinal direction, and 10 is a pinch roller (not shown). A capstan which constitutes a transfer means for transferring the tape 1 in the longitudinal direction in cooperation with each other, 11 is a capstan motor for rotating the capstan 10, and 12 is 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, and 22 presets the output of the counter 20 according to the timing signal from the timing signal generation circuit 21.
A presettable binary counter that counts the capstan FG signal that is preset as the data PD and that is input to the terminal 17, 23 is a D / A converter that performs D / A conversion of the output of the presettable counter 22, 24 Is a stale pattern generator that generates a fixed pattern signal for stale reproduction based on the timing signal from the timing signal generation circuit 21, and 25 is an output of the D / A converter 23 and an output of the stale pattern generator 24. Is an output terminal for outputting the conversion element control pattern signal output from 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) are CTL signals, especially when playing back at 1.5x speed
Output of counter 20 shown, presettable counter 22
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 at the time of stale reproduction and 1.5 × speed reproduction, 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. On the other hand, the timing signal generating circuit 21 in the pattern signal generating circuit 15 shown in FIG. 2 outputs the rising and falling edges of the HSW signal as shown in FIG. 3 (b). The synchronized timing signal is output. And based on this timing signal, the stale pattern generator
From 24, a stale pattern signal for continuously converting the heads 2A and 2B from 0 to -1 track pitch (hereinafter referred to as TP) within one field scan as shown in FIG. 3 (c). Is output.

Here, so-called field-stealing reproduction is performed in which the field signals of one recording track recorded by the recording head having the same azimuth angle as the reproducing heads 2A and 2B are alternately reproduced by both heads 2A and 2B. In the event of an attempt, 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 is the head.
2A and 2B, the center track of the recording track of the field signal recorded by the recording head having the same azimuth angle, the wavy line of the field signal recorded by the recording head having a different azimuth angle from the head 2A and 2B. The central locus of the recording track is shown by the white arrows in the heads 2A and 2B.
The central locus of the run of CTL and CTL shows the recording locus of the CTL signal (this is the same in FIG. 4B), and the scanning of the heads 2A and 2B is performed as shown in the figure. The center locus (hereinafter referred to as head locus) C is diagonal to 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. It is a line segment that connects the two. 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. From 0-
It turns out that it is enough to change continuously up to 1 TP.

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

On the other hand, the capstan by the capstan motor 11
The capstan FG signal output from the frequency signal generator 12 accompanying the rotation of 10 is the pattern signal generation circuit shown in FIG.
It is attached to the counters 20 and 22 in 15, and these counters 20 and 22 count the capstan FG signal. Here, the counter 20 is set to 1 by the CTL signal from the CTL head 9. Since the count output is reset every frame, the count value for the +2 track pitch is the upper limit, and the CTL signal becomes as shown in FIG. 3 (d) during 1.5 × speed reproduction. It becomes like. And, on the other hand, the presettable counter 22
Is a count output (or D / A) for counting 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 generating circuit 21. The output of the converter 23) is as shown in FIG. 3 (f) during 1.5 × speed reproduction. Therefore, from the adder 25, the D / A converter at this time
As a result of adding the output of 23 and the output of the stale pattern generator 24, a pattern signal as shown in FIG. 3 (g) is output during 1.5 × speed reproduction.

Note that the outputs of the counters 20 and 22 and the adder 25 actually include small step 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 locus of the head 2A, B ₁ , B ₂ , B ₃ ... is the head locus of the head 2B, and a ₁ , a
₂ and a ₃ indicate the track loci of the field tracks recorded by the recording head having the same azimuth angle as the heads 2A and 2B. In the first field, the head locus A is aligned with the track locus a ₁ . Therefore, it is necessary to continuously give the head 2A a transition from 0 to +0.5 TP in the scanning of the first field. In the second field, the head locus B ₁ is also adjusted to match the transformer locus a _1. It is necessary to continuously give a shift from +1.5 TP to +2 TP within 2nd field scan for 2B.
In the field, in order to match the head locus A ₂ to the next track locus a ₂ , it is necessary to continuously give the head 2A a transition from +1 TP to +1.5 TP within the scanning of the third field. In order to match the head locus B ₂ to the next next track locus a ₃ , it is necessary to continuously give a shift from +0.5 TP to +1 TP to the head 2B within the scanning of the fourth field. Although it is repeated in four field cycles, it is understood that the pattern signal shown in FIG. 3 (g) satisfies the above required 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.

By the way, in the conventional device, as described above, the pattern signal for head control corresponding to it at the time of reproducing at an arbitrary speed is obtained, but here in the conventional device, It is clear that the CTL signal is indispensable for forming the pattern signal, and therefore 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 in the original 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 described later have different operations during recording and reproduction, and also depending on the specified 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 shown by each counter CD 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 generating circuit 56 shown in FIG. 6, the counter P101 is for obtaining phase information, and the counters A102 and B103 are 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 in the figure. Then, this carrier signal is supplied to a 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 (2n) generated by the preset data generator 104.
Equivalent to).

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 a capstan FG signal input terminal, 111 is a frequency doubler that generates a pulse at the rising and falling 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. . 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 the vehicle is traveling to. The F / R signal is supplied to the AND gate 115 via the AND gate 114 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 by doing so, 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 signal. So 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. 6A. This circuit 123 generates an absolute phase adjusting pulse so that the inrush position of the reproducing head is matched even if it does not match the reproducing track. Control in the direction of 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 counted up or down by the counter P101 is obtained by doubling the capstan FG signal, but this 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 generation number of the capstan FG signal to the TP is reduced 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 following explanation, each counter has a session to count up or down multiple pulse signals, and the counters will be configured to perform operations equivalent to addition and subtraction. Is. That is, the pulse generation circuit B112 is provided for the purpose of reducing the probability that a plurality of PALU 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 count P101 counts down the pulse related to the capster 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 reproduction is performed, the same as in the reverse direction (hereinafter referred to as the forward 1/3 slow)
The case where the tape is run at a tape speed of 3 times and the throw is performed (hereinafter referred to as the inverse 1/3 slow) will be described as an example. In the case of the positive 1/3 slow, the output of the counter P101 is output every 6 field scanning periods. Repeats 48 → 0, and in the case of reverse 1/3 slow, repeats 0 → 48 every 6 field scanning period. If, for example, 16 is obtained as the output of the head rush counter P101, the rush position 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 from the playback track by 2/3 TP in the negative direction.

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 shift amount of the conversion element, that is, the maximum tape speed during high-speed search reproduction desired. .

Counter A102 and count 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 counter A102 and counter B103 preset terminals (represented by PR in the figure), respectively. Head 2A and head 2B
When and are rotating 180 degrees out of phase, PUL and A
It goes without saying that PUL and B are also input with 180 ° different phases.

When PUL, A, PUL, and B are input to PR, respectively,
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 / as so-called offset binary data.
This is aimed at making the output close to 0 level when A-converting.

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 is generated from the circuit 105 when the tape is run at 10x speed in the forward direction, and 0101 when the tape is run at 6x speed in the reverse direction.
May be generated by the circuit 105.

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 and 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. Further, the output pulse of the pulse generating 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 running to the negative direction. . 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, suppose that the tape running speed at the time of recording is v, and the tape speed at the time of reproducing is Nv (N indicates a positive direction speed and N indicates a negative direction speed, respectively).
Then, the head displacement required by the reproducing head during one field period is proportional to (N-1) times TP. 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, the slope required to shift the reproducing head by 1 TP in one field period is proportional to 1, so if the number of pulses corresponding to 1 TP (4 in this example) is counted up in one field period, the slope will increase. +
Get one. And if these are performed simultaneously, a desired inclination proportional to (1-N) can be obtained.

Therefore, the frequency of the clock pulse generated by the pulse generation circuit C is fv × 48 (Hz). Correct fv is the field scan frequency.

A terminal 206 is a terminal to which a rectangular wave signal (PUL.C) for designating a period in which the counter A102 counts each pulse described above is supplied, and PUL and C perform AND gates 117 and 119 to output each pulse. You are gated. On the other hand, the terminal 207 is a terminal to which a rectangular wave signal (PUL.D) for specifying the period in which the counter B103 counts each pulse is supplied.
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 count A102 and the counter B103 respectively fetch the initial data for determining the plunge position of the head from the counter P101 during the period when the reproducing heads 2A and 2B trace the recording track on the tape, and By counting each pulse so that the tracing locus has an inclination proportional to the inclination of the recording track, a fixed pattern signal for the reproducing head to accurately trace the desired recording track during tape running at an arbitrary speed is obtained. It 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. Further, this HSW signal is a 30 Hz rectangular wave signal when fv is 60 Hz, 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, and both show the waveforms at the time of positive 1/3 slow. There is. (D) is a pulse (CLP) generated by 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 a rectangular wave signal (PUL.C) supplied to the terminal 206, (G) is the terminal
A square wave signal (PUL.D) supplied to 207, (H) is a pulse (PUL.A) supplied to the terminal 202 for presetting the counter A102, and (L) is for presetting the counter B103. Pulse supplied to terminal 204 (PUL.B),
(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).
Is.

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, the electromechanical conversion element causes a resonance (linking) phenomenon in response to a rapid change in applied voltage. Further, in one recording track, there is an area where other signals (for example, digital audio signal) 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 valid period of the fixed pattern signal, that is, the period in which the counter A102 can count the output of the pulse generating circuit B112 and the pulse generating circuit C113 is the period when the HSW signal is high level and immediately before that. 1/2 field scanning period. PUL.C during this period
It is given as the high level period of (f). This PUL.
C (f) can be easily formed by a logic circuit (not shown) by the HSW signal (a) and 60PG (e). PUL.D (g) is formed as shown in FIG. 7 for the same reason.

The timing for fetching the initial data of counter A102 and counter B103 is the pulse PUL.A input to the PR terminal of the counter.
(L), determined by 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. The PUL.A (re) and PUL.B (h) may be formed by using the falling edges of PUL.A (f) and PUL.D (g), for example. The details of PUL.S (nu) and PUL.E (wo) will be described 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 for setting the fixed pattern signals to (vi) and (vii) when the tape running speed is 0 (so-called still reproduction) and when recording is the same (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, and the counter A1
02 and counter B103 are FGP within the fixed pattern effective period.
By counting down and counting up CLP, both outputs become almost unchanged.
At this time, the counter B outputs the counter A102 (vii).
The output of is a waveform shifted by the level for driving the conversion element by ITP. This is because the timing of taking in the value of the counter P101 is different for one field scanning period, and the counter P101 is in the meantime.
Is to count FGP for 1 TP.

6 (A) and 6 (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. Timing chart for setting pattern signal to (V), Figure 11 shows reverse 1 /
It is a timing chart which makes a fixed pattern signal into (V) at the time of 3 throws.

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
The center line of the trace locus of the head 2A when the displacement due to 3A is 0, b _{0 to} b ₅ are the center lines of the trace locus of the head 2B when the displacement due to the conversion element 3B is 0, and X is the running of the tape. It is an arrow shown.

As is well known, in the normal 1/3 slow and the reverse 1/3 slow, every other recording track is traced 6 times and reproduced. For example, in FIG. 9 (A), recording track A ₁
Is traced six times b ₁ , a ₂ , b ₂ , a ₃ , b ₃ , a ₄ . First
0 (V) A and B are fixed patterns (analog display of the output data of the counter A102 and counter B103) generated by this example in association with this, and P is an analog display of the output data of the counter P. Is.

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. The counter is started, the count is stopped at the point w, and the output of the counter P is fetched again. It will be apparent from comparison with FIG. 9A that the desired fixed pattern signal is obtained by this repetition.

Also in FIG. 11 (V), A and B are fixed patterns generated by this example, P is an analog display of the output data of the counter P, and similarly, the output data of the counter P is displayed on the counter A at point u. 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.

Therefore, the inrush phase control circuit 123 that matches the inrush position of the reproducing head with the recording track to be reproduced to bring the phase information closer to the absolute information will be described next.

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 signal (AT
FA, ATF.B) are subtracted from the fixed pattern signals for the heads 2A and 2B, respectively. This is because the deviation from the trace locus track of the reproducing heads 2A and 2B when the conversion elements 3A and 3B are driven only by the fixed pattern signal is corrected.
The fixed pattern signal may be shifted according to ATF.A or ATF.B.

ATF and A input to the terminal 201A are sampled and held by the sample hold circuit (S / H) 132 using a timing pulse (PUL.S) indicating the intermediate timing of each scan field as a sampling pulse. The timing of PUL.S is as shown in FIG.

The output of this S / H 132 is the comparators 133, 134 and the resistors R ₁ ,
It is supplied to the voltage detection circuit consisting of R ₂ and R ₃ , and when the voltage is equal to or higher than the predetermined voltage E ₁ , a high level output is obtained from the comparator 133 and E
_{When the} voltage is lower than the predetermined voltage E ₂ lower than _{1, a} high level output is obtained from the comparator 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 PUL.A described above and AND gate 1
Supply to 35,136.

If ATF, A is E ₁ or more at the timing of PUL.S, the AND gate 135 supplies a pulse to the CD terminal of the counter P101. On the other hand, if ATF and A are equal to or less than the timing E _{2 of} PUL.S, the AND gate 136 supplies a pulse to the CU terminal of the counter P101.

This is because the rush position of the reproducing head 2A is ahead of the track when ATF and A are E ₁ or higher, almost on-track when E ₁ or lower and E ₂ or higher, and reached when E ₂ or lower. Based on the judgment. That is, if the plunge position of the head 2A is advanced with respect to 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. The 2B plunge positions both approach the on-track state. Further, if the plunge position of the head 2A is behind the track, the fixed pattern signal is similarly shifted upward and approaches the on-track state. This is done in the form that while the counter P101 is counting FGP, it counts one interrupt pulse every two files and one scanning period. For example, in the initial stage, the rush position of the head to the track is 1
If it is shifted by / 2TP, the counter P101 counts two interrupt pulses, so that the inrush position is on-track. That is, in this case, the time required to be on-track is 48 × 1 / fv, and the on-track state can be drawn within 1 second. Further, according to the configuration of this example, it is of course possible to correct the shift of the plunge position caused by the slip of the capstan with the tape.

Further, by adopting such a configuration, even in the stale reproduction, it is possible to shift the fixed pattern signal to 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.

In this way, 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 / 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 53 (PU
Supply as L, E). In the case of 4f type tracking, the signal processing method is different because the pilot signal obtained from that track and the pilot signal obtained from both adjacent tracks are different each time the reproduction track is updated. 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 done using this PUL.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 subtractor 171 subtracts ATF, A and ATF, B from the fixed pattern signals for the heads 2A, 2B, respectively. Reference numeral 59 is a DC component removal circuit that detects the average of the DC components contained in the output signal of the subtraction circuit 58 by the integrator 180 and removes it using the differential amplifiers 181 and 182. Differential amplifier 18
The output signals of 1 and 182 are applied from the terminals 211 and 212 to the electromechanical conversion elements 3A and 3B through the 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 use two pulses every two field periods, or to determine the supply interval and the number of pulses according to ATF.A. The same circuit 12
The sampling timing of the S / H 132 of 3 is also arbitrary, and the S / H 132 may not be provided.

As a fixed pattern shifting method, the number of pulses counted by the counter P101 is changed as described above, but it can be performed by changing the preset data generated by the preset data generator 104. .

<Explanation of Effect> As described above with reference to the embodiment, according to the present invention, the recording amount of the recording head is detected by the head, and the count value of the counter is shifted in accordance with the detection amount of the recording track displacement. It is possible to obtain a rotary head type video signal reproducing device capable of making the entry position to the track on track. Therefore, good tracking can always be obtained, and the shifting unit can stably operate, so that a high-quality variable speed 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 one specific example of the pattern signal generating circuit in FIG. 1, and FIG. 3 is each circuit in FIG. Of the input and output waveforms at the time of 1.5 × speed reproduction, FIG. 4 (A) and FIG. 4 (B) are at the time of stale reproduction and 1.
FIG. 6 is a diagram showing the relationship between the central locus of scanning of the head and the central locus of the recording stock on the tape during 5 × speed reproduction. FIG. 5 is a diagram showing the configuration of the essential parts of a VTR as an 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 the time of positive 1/3 throw, and FIG. 11 is a timing chart showing a fixed pattern signal at the time of reverse 1/3 throw. 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 phase means, and 12 is a capstan FG signal A rotation detection element for generating a signal, 55 is a conversion element control circuit, 101 is a counter, 123 is an inrush phase control circuit, 131 is a pulse generation circuit, 132 is a sample hold circuit, 133 and 134 are operational amplifiers, 135 and 136 are AND gates respectively, 13
7,138 are OR gates.

 ─────────────────────────────────────────────────── ─── 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) Reference JP-A-56-80821 (JP, A) JP-A-56-65332 (JP, A)

Claims (2)

[Claims] 1. A video signal is reproduced by tracing a recording track formed with a predetermined track pitch on a recording medium by a rotary head which is displaced by a displacement means in a direction intersecting with a rotation surface thereof. An apparatus, comprising: a transfer means for transferring the recording medium; and a pulse obtained in association with the recording medium transfer operation of the transfer means, and the count value can be shifted by a predetermined value related to the track pitch. A counter, a means for detecting the amount of deviation between the rotary head and the recording track, a means for shifting the count value of the counter according to the output of the detection means, and the rotary head based on the count value of the counter. And a means for controlling the plunge position with respect to the recording track via the shifting means. 2. The rotary head type video signal reproducing apparatus according to claim 1, wherein the counter is an up / down counter.