JPS6184176A - Rotary head type reproducing device - Google Patents

Abstract

PURPOSE:To obtain an excellent reproducing signal by providing a counting means which counts a signal to be counted generated associatively with the conveyance of a medium and controlling a stop position accurately even if a special control signal is not recorded in the running direction of a recording medium. CONSTITUTION:Reproducing signals reproduced by heads 5a and 5b are passed through a head switching HSW9 to generate a continuous signal, which is supplied to a video signal processing circuit 14 and a tracking error ATF signal generating circuit 15. The HSW 9 is controlled with a head switching signal 30PG of 30Hz obtained from a detector 12 and a drum PG generator 13. On the other hand, only a four-frequency pilot signal component is separated by the circuit 15 with the continuous signal and processed by a known method to obtain a signal ATF. A variable speed reproducing control circuit 17 equipped with the counting means which counts the signal to be counted performs rotation control over a capstan 10 during still-picture reproduction and slow-motion reproduction by using 30 PG, capstan FG, ATF signals, etc.

Description

[Detailed Description of the Invention] [Technical Field] The invention relates to a rotating F-type reproducing device, in particular, a recording medium that runs at a predetermined speed to trace and record tracks formed at a predetermined pitch with a rotary head. The present invention relates to a device for reproducing signals.

<Description of conventional technology> Hereinafter, in this specification, a rotating 2-helical helical scan type video tape recorder (VTR) will be described as a device of this type.
) will be explained using an example.

Conventionally, in this type of VTR, in order to perform still image playback (FI/STILL) without producing noise par on the screen, the L
The rotational phase of the reproducing head relative to the track is known by reproducing the control signal (CTL) recorded in the operator's direction of the a-type tape, and this phase information is used to stop the tape.

In contrast, in recent years, with the trend toward higher density recording, VTRs have been proposed and put into practice that perform tracking without recording or reproducing the CTL. However, in this type of VTR, it is not possible to easily find the phase relationship between the head and the trunk as in the case of using the above-mentioned CTL, and it is not possible to perform practically effective still reproduction.

In addition, conventional VTR models have been commercialized that alternately perform the above-mentioned fine methyl and normal playback, and have noise-free slow motion playback (fine slow), but they do not record or play back CTL. This fine throw could not be effectively performed with a VTR.

<Object of the Invention> The present invention has been made in view of the above-mentioned background, and even if no special control number 0 is recorded in the running direction of the recording medium, it is possible to accurately control the stop position of the recording medium. , good 11) raw! (The purpose of the present invention is to provide a rotary head type reproducing device capable of obtaining No. F.

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

In the embodiment described below, the present invention is applied to a VTR that employs the well-known four-frequency pyronotka method as a tracking method.

First, the relationship between the trace trajectory of the head and the track during still playback in a VTR, and the track knob error No. 4a (ATF signal) indicating the misalignment between the head and the trunk at that time will be explained.

Here, a case will be explained in which two-field video signals are sequentially played back (so-called frame still playback) in a rotating two-head VTR.

FIGS. 1(A) and 1(CB) are diagrams showing the state on the magnetic tape and the timing of each signal when the tape is stopped without control. FIGS. 2A and 2B are diagrams showing the position on the tape and the timing of each signal when the tape is stopped at an ideal position.

In FIG. 1(A) and FIG. 2(A), 1 is the tracing locus of the head, 2 is the running direction of the tape, 3 is the tracing direction of the head, and 4 is the tape.

f1 to f4 indicate tracks on which PyroSotoy J4 having frequencies f1 to f4 are recorded.

In addition, in Figure 1 (B) and Figure 2 (B), (A) is a 30Hz head switching signal (30PG) synchronized with the rotation of the throat, and (0) is a signal for reproducing a video signal. The frequency of the pilot signal recorded on the track being recorded, (
(c) shows the ATF signal, and (d) shows the enovelope waveform of the reproduced signal.

During still playback, the trace locus of the video track and the head causes a undulation of one torano period in one field. Now, if the tape stops in the state shown in Figure 1 (A), the maximum point of one head's output will be the video signal on the screen, but the minimum point of the other head's output (indicated by an x in the figure) will be the video signal on the screen. After all, since it is a video signal within the screen, noise par will appear on the playback screen.

Therefore, in order to prevent noise par from appearing on the screen,
As shown in Figure 2, the maximum output point of the throat and the minimum output point of the head should match the head JJJ exchange point.In other words, the entry position of the head should be matched with the track to be reproduced or its All you have to do is stop it so that it matches the adjacent track, and if you consider the ATF signal at this time, the ATF signal is O level (more precisely, rail VJ determined by the difference in frequency characteristics, etc.) This shows that UEj is accurately tracing the recorded trunk trajectory, so when changing the head v'J, A T F (if J is 0 and \) It can be seen that good still reproduction can be achieved.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a diagram showing a schematic configuration of a VTR as an embodiment of the present invention. In Fig. 3, 4 is a magnetic tape, 5a,
5b are rotary playback heads, respectively.・＼Throat 5a, 5b
The tiles have different magnetization directions. Reference numeral 6 denotes a ring that rotates the rotary heads 5a and 5b, and guides the magnetic tape 4 on its outer peripheral surface. The reproduction signal reproduced by the heads 5a and 5b is sent to the head switching circuit (H5W).
The signal is made into a continuous signal via the video signal processing circuit 14 and the ATF signal generation circuit 15. HSW9 is controlled by 30PG obtained by detector 12 and generator 13.

The continuous signal obtained by the H5W9 is processed in a video signal processing circuit 14 into a signal format (for example, NT) in which the video signal components are separated.
The signal is returned to a video signal (equivalent to an SC signal) and output.

On the other hand, based on this continuous signal, the ATF signal generation circuit 15 outputs 4
Only the frequency pilot signal components are separated and an ATF signal is obtained by well-known signal processing. To briefly explain this signal processing, the track to be played (
The pilot signal superimposed on the main track (main track) is multiplied by a signal with the same frequency (Local Pikotsu No. 143), and the difference between the pilot signal and the pilot signal reproduced from the tracks on both sides adjacent to the main track is leveled. Compare and detect tracking errors.

This is to obtain the ATF signal.

The ATF signal obtained in this way is supplied to the capstan motor control circuit 8, and the capstan lO during normal playback is
This control is performed via the capsun drive circuit 7.

As is well known, the capstan 10 moves the tape 4 in cooperation with a pitch a-ra (not shown). Further, this rotation is detected by a detector 11, and the detector 11 generates, for example, X pulses per one rotation of the capstan lO, and these pulses are transmitted to the capstan motor control circuit 8 and The signal is supplied to a variable speed regeneration control circuit 8, which will be explained in detail later. This capstan FC is supplied to a capstan motor control circuit 8 to form a speed control loop.

The variable speed regeneration control circuit 17 uses the aforementioned 30PG, capstan FC, ATF signals, and further signals obtained from the system controller 16.

This variable speed playback control circuit 17 is a circuit for controlling the rotation of the capstan lO during still playback and slow motion playback, and will be exemplified below using a specific circuit example.

FIG. 4 is a diagram showing a specific example of the variable speed regeneration control circuit 17 in FIG. 3. FIGS. 5('fL) to (g) are timing charts showing waveforms of each part of FIGS. 4(a) to (g), and the operation of the circuit shown in FIG. 4 will be explained below using FIG. 5. do.

In Figure 4, 20 is Capsta 7FG during recording.
Clock of the same frequency as 4. (terminal to which the number is supplied, 2
2 is the terminal where ATFc number (b) is input, 26 is 30P
Terminal where G is input.

28 is a terminal to which a low level signal is supplied from the system controller 16 when still reproduction is commanded; 30
is a terminal to which capstar 7FG is supplied.

32 is the level when the head is in an off-drag state (
Habo O level → shown in the 511th VJ) is the threshold!
A conoparator, 34 is a monomulti to obtain the pulse generated at the rising edge of the co/pa rake, and 36 is a flip-flop (F F) set by the pulse generated by the monomulti 34, which is supplied to one terminal 26. The generated 3opG(a) is supplied to the monomulti 38, and a pulse generated at its rising edge is obtained. This pulse resets the FF 36 through the OR gate 40.

The output (d) of FF36 is supplied to AND gate 42,
While this FF 36 is set, the counter 46 counts the clock signal supplied from the terminal 20 by 1 (count amplifier). When the counter 46 stops counting amplifier by the clock signal, the monomulti 38 The generated pulse is F through the gate 44 (or game) 40.7
Cent F48. The FF 48 is reset by pollow generated by the counter 46 counting down the capstan FG, and a lock signal is supplied to the output terminal 52 via the AND gate 50 while the FF 48 is being centered.

A step-by-step explanation will be given below. When a command for still playback is issued from the system controller 16, the rotation of the capstan IO is stopped by -1 at an arbitrary timing. The ATF signal at this time is shown in Figure 5 (b
) of A (point &Ia), and make this ATF signal become C of Fig. 5(b).
Field still) can be realized.

Now, the ATF signal (b) is at the above-mentioned on-track level VJ.
F
This is the period in which the output signal (d) of F36 is at a high level, and this (d) shows the phase difference between the ATF signal (b) and 30PG (a) from the ideal state. This period counter 46
is counting the clock signal, but the tape length when the tape is transported at the tape running speed during recording (= during normal playback) during the high level period of the output signal (d) of the FF36 is This corresponds to the distance of tape displacement from the tape stop position. Therefore, if the clock signal input from the terminal 20 is set as the frequency of the capstan 7FG during recording in advance, the count value of the counter 46 will be generated from now until the capstan 10 is rotated and the tape reaches the ideal stop position. Shows the number of capstan FCs. In other words, after the clock signal is counted up by the counter 46 in this way, the capstan / is rotated and the counter 46 counts down the capstan FG generated at that time by 7, and the total value fl(a becomes zero is ideal). It is sufficient to judge that the tape is at the desired stop position and stop the tape running.In other words, in Fig. 5, when the output signal (g) of FF 48 is at a high level, the capstan 10 is
It is driven by a clock signal passed through the clock gate 50, and the driving is stopped by outputting a pollo signal from the counter 46.

According to the VTR equipped with the above-mentioned variable speed reproduction f, II control circuit, the phase difference between ATF No. 4 and 30PG is converted into the number of pulses, and the corresponding failure capstar 7FG is counted.
By stopping the tape running when the count reaches zero.

By stopping the tape at an ideal stop position, a good reproduced video signal can be obtained even when the tape is stopped.

FIG. 6 is a diagram showing another example of the variable speed regeneration control circuit 17 shown in FIG. 3. Further, FIG. 7 is a timing chart for explaining the operation of FIG. 6.

In Figure 6, 27 is 30PC (shown in m7 diagram (a))
This is the terminal to which the 30 PGit monomulti 35.37 shifts the phase and shapes the waveform, and the pulse as shown in FIG. 7(b) (hereinafter referred to as PG pulse) is supplied from the monomulti 37. Output. The terminal 29 is a terminal to which a command signal to stop the tape is supplied from the system controller 16, and this command signal is approximately 1 frame (=
2 field) shall be kept at a high level for 1 period.

Now, when a tape stop command is supplied from the terminal 29, the PG pulse generated from the monomulti 37 while the command signal is at a high level is gated by the 77 gate 41, and this pulse (7th U; 4(m) ) is supplied as a trigger pulse to a monomulti 43 consisting of a T clip-flop. Monomulti (MM) 43 is a monomulti for tracking 7g adjustment, and includes a resistor R1 and an IITf resistor R.
The pulse (7th
By adjusting the pulse width (shown in Figure (C)), tracking can be adjusted to a certain extent repeatedly. Incidentally, the rise of the output of the monomulti 43 is made to almost match the rise of the output of the 30PG.

Mono multi 43 CL small output No. 71A (C)
is supplied to the Ck terminal of the D flip-flop (DFF) 47, thereby changing the Q output of the DFF 47 from the low level to the noise level.

From terminal 21 is the capstan FC in record 1Ijr.
A clock signal of the same frequency as the DFF is supplied, and the DFF
When the Q output of 47 becomes high level, this clock signal starts counting up in counter 53 via AND gate 55 and OR gate 59. On the other hand, an ATF signal (shown in FIG. 7(e)) is supplied to the terminal 23, and this ATF signal is compared by a comparator 33 with the level (VJ) when the head is in an off-drag state. Therefore, the output of the conoparator 33 (Fig. 7(f)
The reproducing head is in an on-track state at the falling and rising edges of the signal (shown in FIG. 1). These falling and rising edges are detected by an edge detection circuit comprising an inverter 39& and an exclusive OR circuit 39b, and are converted into narrow pulses. This edge pulse resets the DFF 47 via the AND gate 45.

Therefore, the Q output of 0FF47 (shown in FIG. 7(d)) is from the rise of the Q output of monomulti 43 (shown in FIG. 7(C)) to the aforementioned edge pulse (7th u L l
(lower) reaches a high level. Therefore, the color/receiver 53 counts up the clock signal during this period.

Further, while the Q output of the DFF 47 is at a high level, the tape length when the tape is transported at the tape running speed during recording corresponds to the distance of the tape position shift from the ideal tape position. That is, it shows the number of capstans FG that occur after the tape passes the ideal stop position.

Therefore, after the counter 53 counts up the clock signal in this way, the capstan is rotated, and the capstan FG generated at that time is further counted and amplified by the counter 53, and the count value is nF (where n is integer,
F is a failure of the capstan FG that occurs when the tape is transferred one track pitch), then it is sufficient to stop tape running assuming that the tape is at the ideal stop position.

The output of the monomulti 49 (shown in FIG. 7(g)) goes to a high level for more than a frame period (preferably approximately one frame period) from the rise of the Q output of the mono multi 43 to 17, and at least this high level During the level period, the counter 53 should stop counting up the clock signal. The fall of the output of the monomulti 49 in turn triggers the DFF 51, and the Q output of the DFF 51 changes to high level. Also, the Q output (shown in Figure 7(i))
is supplied to the capstan motor control circuit 8 via the terminal 61, and the capstan IO is activated. In response to this, the capstan FG input from the terminal 31 is counted up by the counter 53 via the AND gate 57° and the OR gate 59. The number of capstan FGs generated when the tape is transferred one track pitch is set to 16.
If the tape is configured to set the stop position in units of two frames, when the count value of the counter 53 reaches 64, the tape will be at the ideal stop position. That is, if the counter 53 is a pinary counter, when the 8th bit becomes <+ to 1, the color/return 53 supplies a high level output to the reset terminal of 0FF51, and the tape is at the ideal stop position. At this time, the Q output of the DFF 51 changes to a low level. Therefore, the color/return 53 counts the capstan/G while the Q output of the DFF 51 is at a high level (shown at 71i5t2).

When the Q output of DFF51 changes to low level, color/returns 5.
3 stops the count-up of the capstan 7FG, and the Q output of the DFF 51 changes to high level, which is supplied to the capstan motor control circuit via the terminal 61, thereby stopping the capstan 710, and the tape is kept at the ideal level. It will stop at the stop position. In addition, Figure 7 (j)
shows the current actually applied to the capstan motor (output of the capstan motor drive circuit 7), and FIG. 7(k)
is a signal that detects the actual rotation direction of the capstan lO,
FIG. 7 (see) shows the period during which the brake is applied to the capsta 710. That is, when the DFF 51 is reset, a brake is applied to the capstan 10, and an extremely weak drive +tLiQ is applied in the forward direction just before stopping l-. If the capstan IO is stopped in this manner, the capstan IO will not be reversed and will stop extremely stably.

As mentioned above, in a VTR equipped with a variable speed playback control circuit as shown in Figure jS6, the ideal tape can be reproduced by counting the number of Capstar 7FGs according to the phase difference between the 30PG and ATF signals. This allows the tape to be stopped at an ideal position.

Also, if this is used, good still playback can be achieved.

Although the above explanation does not specifically mention slow motion playback, for example, if the circuit shown in Figure 6 is used, when the tape is stopped as described above, the capstan is normally played during the L2 period. As well as driving as time,
This can be achieved by setting the pulse intensity of the output of the monomulti 49 to two field periods and repeating this stopping operation many times.

In addition, as a first stage for providing a tracking error signal, a tracking error signal based on a well-known four-frequency power formula may be used.It goes without saying that the tracking error signal can also be obtained using a simple enovelope detection circuit, for example. .

Furthermore, regarding the capstan stop control method: A4
In the example shown in the figure, it is also possible to reduce the rotational speed of the capstan before the l value of the counter 46 reaches O (for example, when it reaches 8), and to remove the influence of in/yar and stop the capstan. Also, in the example in Figure 6, before the 21a value was 64 (
For example, by reducing the running speed of the tape at 56), it is possible to similarly remove the influence of inertia and stop the tape at an ideal stopping position with great accuracy.

Furthermore, in order to obtain a number corresponding to the phase difference between the 1230 PG and ATF signals, a similar effect can be obtained by forming a signal having a level corresponding to the phase difference and A/D converting this.

Theory of Effects IJI> As explained above using the embodiments, according to the present invention, even if a special signal corresponding to the track pitch is not provided in the running direction of the recording medium.

It was possible to obtain a rotary head type playback device that can accurately control the stop position of the recording medium and obtain a good playback video signal.

[Brief explanation of drawings]

FIGS. 1(A) and CB) show the case where the tape is stopped without the VTR 1 control. Figure 1a shows the appearance on the tape and the timing of each signal. Figures 2 (A) and (B) show the appearance on the tape and the timing of each signal when the tape is stopped at an ideal position. Figure shown. FIG. 3 is a diagram showing a schematic configuration of a VTR as an embodiment of the present invention. FIG. 4 is a diagram showing a specific example of the variable speed regeneration control circuit in FIG. 3. Figure 55 is a timing chart for explaining the operation of the circuit shown in ft54. :1IJ6 is a diagram showing a specific example of the variable speed regeneration control circuit in FIG. 3. FIG. 7 is a timing chart for explaining the operation of the circuit shown in FIG. 4. 1 is a trace locus, 4 is a magnetic tape as a recording medium,
5a and 5b are reproducing rotary heads, respectively. IO is the rotation detection of the capstor/ included in the transfer means, and Ll is the rotation detection of the capstor/! , 13 is a tram PG generation circuit, 15
is the ATF signal generation circuit. Reference numeral 17 is a variable speed reproduction control circuit, and reference numerals 46 and 53 are numbers included in the counting means. (gfu

Claims (1)

[Claims] A device for reproducing recorded signals by tracing tracks formed at a predetermined pitch with a rotating head by running a recording medium at a predetermined speed, and generating a first periodic signal related to the rotation period of the rotating head. means for generating a second periodic signal related to a fluctuation period of the tracking error signal indicating the deviation between the track and the head;
counting a number of counted signals generated in connection with the medium transporting operation of the transporting means, the number of which corresponds to a transport means for running the recording medium and a phase difference between the first periodic signal and the second periodic signal; 1. A rotary head type reproducing apparatus comprising: a counting means for controlling the transfer means; and means for controlling the transfer means based on the counting output of the counting means.