JPS61148659A - Information signal reproducing device - Google Patents

Abstract

PURPOSE:To obtain an excellent tracking error signal in reproducing information signals from a recording medium in which the information is recorded in superposition on the pilot signals of frequencies f1-f4 one after one by multiplying the output from the head which is not being used in the reproducing by (f2+f3)/2. CONSTITUTION:The reproduction output signal from heads Hc and Hd is also supplied to a multiplier 23 after being made to continuous signals by a switch 15. By the multiplier 23 the signal outputted from the switch 15 and the reference signal of frequency f0=(f2+f3)/2 that is oscillated by an oscillator 20, are multiplied. When assuming that the f0 is 8.5fH, its frequency component of difference between the frequencies f1-f4 and itself respectively is 2fH, fH, fH, 2fH. The levels of detecting circuits 26 and 27 are compared by a comparing circuit 28. The output of this comparing circuit 28 is so controlled that it intermittently undergoes an inverse amplifier 29 at every 1/60sec which is the time 1 track is traced, and is taken out by a switch 30, and in consequence, the tracking error signal is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field> The present invention relates to an information signal reproducing device, and more particularly, the present invention relates to an information signal reproducing device in which four types of pilot signals having different frequencies are reproduced once per track.
The present invention relates to a device for reproducing information signals from a recording medium in which each type of information signal is recorded in a predetermined order in a superimposed manner.

<Description of the Prior Art> Conventionally, as this type of device, a video tape recorder (of the type that performs tracking control using a so-called 4-frequency system) has been used.
This type of VTR will be described below as an example.

FIG. 1 is a diagram showing a recording pattern by this type of VTR. In FIG. 1, 1 is a magnetic tape, and 2 is a recording track group. f1 of each track in recording track group 2,
f2. f3. f4 indicates the frequency of the pilot signal superimposed on the video signal of each track. For example, f1
=102. KHzΦ6.5fH, f2=118.9KH
9.5 f in z+7.5fH, f3=148.7KHz
H, f a= 165.2KHzΦl O, 5f l
(where f)i is the horizontal scanning frequency.), generally f4-f3-f2-fl and f2≠f
It is set to be 3. Ha.

Hb are heads with different azimuth angles, f1, f4
The track on which the q pilot signal is superimposed (hereinafter referred to as TR
I, TR4) is head Ha, f2. Tracks on which the f3 pilot signal is superimposed (hereinafter referred to as TR2 and TR3)
are respectively recorded and reproduced by head Hb. The interval between each track (indicated by Tp in FIG. 1) is set narrower than the width of the heads Ha and Hb, and well-known guard panless azimuth overwriting is performed during recording.

The method for obtaining a tracking error signal in this type of VTR is as follows.

If the head is on track as shown in Figure 1,
Pilot signals superimposed on tracks on both sides adjacent to the track on which the video signal is being reproduced (main track) are also reproduced from this head. This is because the pilot signal has a lower frequency than the video signal and does not cause azimuth loss associated with azimuth recording. By comparing the pilot signal levels reproduced from both adjacent tracks, the positional relationship between the head and the main track can be detected, and this is used as a tracking error signal.

By the way, when obtaining a tracking error signal using such a four-frequency method, if the recording head and the reproducing head have the same head width, an accurate tracking error signal can be obtained only when recording is performed without guard panning. It was something.

FIG. 2 is a diagram showing a recording pattern on a magnetic tape in which guard bands are formed between tracks. f1, f2
．． f3. Regarding f4, it is the same as in FIG. Now, assuming that the head Ha is tracing the TRI, even if an attempt is made to obtain a tracking error signal using the method described above, the head Ha will not be able to locate anywhere between the position shown at Ha' and the position shown at Hr in FIG. However, the tracking error signal does not change, so tracking control is impossible. Generally, the head moves the magnetic tape l in the state shown by Ha' or Hf, depending on the characteristics of the servo system of the capstan that runs the tape. will be traced. Therefore, it was not possible to obtain a satisfactory reproduced video signal from a recording pattern in which a guard band was formed.

On the other hand, in the field of VTRs, models that are capable of recording at a track pitch narrower than the normal track pitch have been proposed and put into practice so as to enable long-time recording. By the way, in a VTR that performs 4-frequency tracking fjlil, if you try to realize recording and playback with different track pitches like this, the head width of the recording and playback head will be changed from the normal recording and playback head width because it is necessary to perform guard panless recording. Mode (SP)
If you record in the recording/playback mode (hereinafter referred to as LP) to achieve long-time recording and playback, which must be set wider than the track pitch of the current track pitch, all of the recording will be overwritten, and this will affect the quality of the video signal. It was impossible to record and play back.

It is also conceivable to provide dedicated recording and reproducing heads with different head widths for each of the SP and LP. However, recent VTRs are
Trick plays such as slow-motion playback and still image playback are also becoming necessary functions, and for that purpose, it is necessary to provide another dedicated head, which increases the number of heads. The problem is that it shortens the life of the tape and makes adjustment of the rotating head cylinder difficult. Furthermore, various problems arise, such as an increase in the cost of the VTR, signal deterioration due to crosstalk between rotary transformers, and obstacles to making the 9-turn head cylinder smaller and thinner.

<Object of the Invention> In view of the above problems, the present invention provides an accurate tracking error signal using a pilot signal recorded in a superimposed manner with an information signal even in a recording format in which there is a guard band between tracks. It is an object of the present invention to provide an information signal reproducing device that can obtain information signals.

<Explanation based on Examples> The present invention will be described in detail below using an example in which the present invention is applied to a VTR.

(First Example) Figures 3 (A) and (B) are diagrams showing the head configuration of the VTR of this example, and Figures 4 (A) and (B) explain the state of tape tracing by this VTR. FIG. 5 is a diagram showing a schematic configuration of the reproduction system of the VTR of this embodiment.

In FIG. 3(A), 11 is a head Ha.

It is a rotary cylinder having Hb, Hc, and Hd, and the head Ha and head Hb are rotary heads for recording and reproducing regardless of LP or SP. Head Ha and head Hb
As shown in Figure 3 (B), the plane of rotation is the same and the rotation angle is tao to each other.
It has a phase difference of '. and have different azimuth angles. Head Hc.

Head Hd is a rotating head for performing special reproduction in LP and SP, and both heads Ha.

Rotates on the same plane of rotation as Hb. However, head Hc,
The head Hd is delayed in rotational phase by 90 degrees with respect to the heads Ha and Hb. Further, the azimuth angles of both the head HC and the head Hd are the same as the head Ha. Note that the heads Ha to Hd are all assumed to have the same head width.

In FIGS. 4A and 4B, 12 is a group of recording tracks in the LP, and 13 is a group of recording tracks in the SP. Now, when playing an LP, the head Ha is shown in Figure 4 (
If TRI is traced in an on-track state as shown in A), the center line of the scanning locus at the center of the head Hc immediately thereafter coincides with the boundary between TRI and TR2. Further, if the head Hb traces TR3 in an on-track state, the center line of the scanning locus of the head Hd immediately thereafter coincides with the boundary between TR3 and TRI. Head Ha is TR
Similarly, when head Hb traces TR2 in an on-track state, head He traces TR2 immediately after tracing TR2.
R4 and TR3 and the head Hd trace on the boundary between TR2 and TR4.

On the other hand, during SP playback, the head Ha is
If TRI is traced in an on-track state as shown in , the center line of the scan locus of the head Hc immediately thereafter coincides with the center line of the guard band between TRI and TR2.

Further, if the head Hb traces TR3 in an on-track state, the center line of the scanning locus of the head Hd immediately thereafter coincides with the center line of the guard band between TR3 and TR1. Of course, when head Ha traces TR4 and head Hb traces TR2 in an on-track state, immediately after that, head He traces TR4 and TR3, respectively.
The head Hd traces on the guard band between TR2 and TR4.

As is clear from the above explanation, in both SP and LP modes, when the magnetic tape L is run at the same speed as during recording and the video signals are played back by the heads Ha and Hb, the head Ha
, Hb to be on-track is that the levels of the two types of pilot signals reproduced by the heads He and Hd are equal. In other words, by comparing the reproduction levels of these two types of pilot signals from the heads Hc and Hd, the amount of deviation of the heads Ha and Hb from the main track can be detected.

Therefore, as long as the direction of the tracking error is detected, this can be used as a tracking error signal.

Next, the operation of the part shown in FIG. 5 will be explained. First, the operation during normal playback will be explained. The signals reproduced from the heads Ha and Hb are taken out alternately by a switch 14,
After being made into a continuous signal, the signal is supplied to the video signal processing circuit 21 via the N-side terminal of the switch 18, and is subjected to well-known reproduction signal processing. The video signal converted into the original television signal form by the video signal processing circuit 21 is outputted via the terminal 21. The switching of the switch 14 is controlled by a 30H2 rectangular wave signal obtained from a detector 16 that detects the rotational phase of the cylinder 11.

On the other hand, the reproduced output signals of the heads Hc and Hd are also converted into continuous signals by the switch 15 and then supplied to the multiplier 23 . At this time, the switch 15 converts the 30Hz rectangular wave signal obtained from the detector 16 into the rotational phase difference between the head Hc and the head Ha.
That is, the switching is controlled by a 30 Hz rectangular wave signal whose phase is shifted by 90'.

The multiplier 23 multiplies the signal output from the switch 15 by the reference signal of frequency fQ (=LL÷E) oscillated by the oscillator 20. fQ to 8.5 f)
If l, then fl, f2.

The frequency components of the difference between f3 and f4 are respectively 2f)l.

fH, fH, 2fH. Here, referring to FIG. 4, the frequency components of the difference between the pilot signals reproduced from mutually adjacent tracks and fO are f)i on one side and 2fH on the other, and the direction in which these are generated is every track. The opposite is true.

A bandpass filter (BPF) 24 converts f)(component into B
PF25 is 2f) (for separating each component,
These outputs are level detected by detection circuits 26 and 27, respectively. The outputs of these detection circuits 26 and 27 are output from the comparison circuit 28.
The levels are compared. The output of this comparison circuit 28 is alternately taken out from the switch 30 through the inverting amplifier 29 and without passing through the inverting amplifier 29 every 1 track tracing period (1760 seconds) to obtain a tracking error signal.

Note that the switch 30 is switched at 30Hz obtained from the phase shifter 17.
is controlled by a square wave signal. The tracking error signal thus obtained is supplied to the capstan motor control circuit 31 to control the phase of the capstan 32. A pinch roller 33 pinches the tape l together with the capstan 32. With the above configuration, the heads Ha and Hb can be completely on-track on the recording track during normal reproduction. The above operation is SP.

The only difference between SP and LP is that the control target of the speed control system in the capstan motor control circuit is common to LP.

Next, special playback will be explained. Here, still reproduction will be explained using the head Hc and the head Hd. The stopping position of the tape 1 in the LP is determined so that both the head Hc and the head Hd trace within the dashed line ST1 in FIG. 4(A). Further, in SP, both the head Hc and the head Hd are determined to trace within the dashed line indicated by SP2 in FIG. 4(B). At this time, the area where the reproduced video signal is obtained is ST1.
This is the hatched portion in ST2, and as is clear from these, so-called field still playback without noise bars can be performed.

During still playback, switch 1B is set to SP.

Regardless of LP, it is connected to the terminal shown on the T side in the figure.

The continuous wave signal obtained by the switch 15 is sent to the video signal processing circuit 2.
1. Control of the tape stop position at this time is not directly related to the present invention and will therefore be omitted.

According to the VTR of the above embodiment, if the track pitch is less than twice the head width of each head, no matter what track pitch is being recorded, an accurate tracking error signal can be obtained by simply switching the control target of the capstan control system. can be detected.

In addition, in the above configuration, since guard panless recording is performed on the LP, head H& and head Hb are used as before.
It is also possible to obtain a tracking error signal by comparing the levels of pilot signals reproduced from adjacent tracks using the outputs of the two tracks.

Regarding the head widths of the head Hc and the head Hd,
As long as the centers of these heads are arranged so as to rotate on the same plane of rotation as the centers of the heads Ha and Hb, they can be freely selected.

(Second example) In the current situation where VTRs are becoming smaller.

In order to downsize the rotating head cylinder, a type of VTR has been proposed in which n (n is an integer of 3 or more) video heads with the same phase difference are attached to the same cylinder, thereby recording and playing sequentially. Figures (A) and (B) are diagrams showing the head configuration and mutual positional relationship with the magnetic tape of an embodiment in which the present invention is applied to a VTR with four heads and a phase difference of 90' between each head. 0 In the figure, 1 denotes a rotary head for the magnetic tapes He, Hf, Hg, and Hf, respectively, 51 is a cylinder that holds these heads, and 52.53 denotes a magnetic tape 1 that extends over an angular range of 2700 or more on the outer peripheral surface of the cylinder 51. This is a loading member for winding.

Generally, when tracing a video track using n rotary heads sequentially, 360
It is necessary to wrap the wire by more than X (l new)°. In this case, if n is an even number, the well-known azimuth recording can be realized by using heads each having a different magnetization direction.

When the head He finishes tracing on the magnetic tape 1, the head Hf, which is rotating 90' ahead of it, rushes onto the magnetic tape l.

Then, when the head Hf finishes tracing on the magnetic tape I, the head Hg starts tracing on the magnetic tape ■, and the heads He, Hf.

Trace the tape in the order of Hg, Hh, and He. In this way, helical tracks are sequentially formed on the video tape 1 at a predetermined pitch, and video signals can be recorded and reproduced. At this time, the tape is of course run at a predetermined speed in its longitudinal direction by a capstan or the like, and during playback it is run at the same speed as during recording.

Here, it is assumed that heads He and Hg have the same azimuth angle, and heads Hf and Hh have the same azimuth angle different from heads He and Hg. Figure 7 (A)
, (B) are diagrams showing the state of recording on a magnetic tape by the head shown in FIGS. 6(A) and ('B).

Assuming that head He has now finished tracing TRI,
Head Hf starts tracing TR2. Also TR2
is head Hf, TR4 is head Hg, TR3 is head H
h will be traced individually.

Incidentally, as shown in FIG. 6(B), each head He.

It is assumed that Hf, Hg, and Hh have the same head width and rotate on the same rotation plane. It is also assumed that each head width sp is narrower than TP.

Next, the state of tracing of each head in this embodiment will be explained with reference to FIGS. 7(A) and 7(B). L.P., S.
P In either case, at the timing when head He finishes tracing TRI and head Hf starts tracing TR2, head Hg is at a position 2:l from the center line of TRI and the center line of TR2. Tracing on a certain line. On the other hand, the head Hh traces a line located at a distance of 1:2 from the center line of TRI and the center line of TR2. Therefore, at this time, by comparing the f1 configuration and the f2 configuration included in the mixed output of the heads Hg and Hh, the direction and magnitude of the tracking error can be determined. Similarly head H
At the timing when f finishes tracing TR2, the head Hh and head He output a mixed output, and at the timing when head Hg finishes tracing TR4, the head He and head H
A tracking error signal can be similarly obtained by using the mixed output of head Hf and head Hg at the timing when head Hh finishes tracing TR3.

FIG. 8 is a diagram showing the main part configuration of the VTR of this embodiment, and FIG. 9 is a timing chart showing the waveform of the numbered part in FIG.
The operation of each part will be explained below. Components in FIG. 8 that are similar to those in FIG. 5 are given the same numbers.

The playback outputs of the heads He, Hf, Hg, and Hh are selectively taken out by switches 54, 55, 56, and 57, and converted into continuous signals, which are then sent to the video signal processing circuit 21.
supplied to The reproduced video signal converted back into the television signal form by the video signal processing circuit 21 is outputted from the output terminal 22.

Here, control of the switches 54, 55, 56, and 57 will be explained. 58 is a detector for the rotational phase of the cylinder 51. If one field is a video signal of l/60 seconds,
Since this cylinder 51 rotates 45 times per second, it is assumed that a rectangular wave signal of duty 50 is obtained at 45 Hz. (
This 45Hz square wave signal (Pl) shown in Figure 9 Pi)
is doubled by PLL (phase locked loop) 59 and becomes 90H.
Obtain 2 (7) pulses (P2). Furthermore, pulse P2 is l/
The frequency is divided by 1/3 by the 3 frequency divider 60 and 30H2 (7) pulses (
P3), and the pulse P3 is further divided by 1 by the 1/2 frequency divider 61.
The frequency is divided by 72 to obtain a 15Hz pulse (P4).

Pulse P3 repeats high level and low level every one field period, and pulse P3 and pulse P4 are supplied to logic gates shown at 62.63 and 64.65.
Figure 9 P5. Pulses shown as P6°P7 and P8 are obtained.

Pulses P5, P6, P7, and P8 are respectively connected to switches 54.
, 55.

56 and 57, resulting in head He.

Output signals are selectively extracted in the order of Hf, Hg, and Hf to form a continuous signal.

On the other hand, pulse P1 and pulse P2 are logic gates 66.67
．． 68. 69 is supplied, and Fig. 9 → P9. PIO, Fi
1. Obtain a pulse as shown at P12. These pulses →
P9, PIO.

pH and Pl2 are for each head He and Hf, respectively.

It shows the timing when Hg and Hh are traced on the magnetic tape l. And these are logic gates 70,7
1,72.73 and the aforementioned pulses P5, P6
, P7, and P8, that is, pulses P13 . . . , P13 . PL4. P15. Obtain P16. Pulse P1
3. P14. P15. When P16 is at a high level, the heads He, Hf, Hg, and Hh are tracing on a line located at a 1:2 or 2:1 ratio with respect to the center line of two adjacent tracks. At this time, the heads He, Hf, H
g.

All reproduced outputs of Hh are supplied to a multiplier 78.

A reference signal having a frequency of n÷U is supplied from an oscillator 79 to the multiplier 78, and is supplied to the multiplier 78 to generate 4 reproduction signals.

The f4 component is converted into a 2fH component, and the f2 and f3 components are converted into fH acid components.

The timing indicated by tl in Fig. 9, that is, the head H
At the timing when e finishes tracing the TRI, the multiplier 78 is supplied with the reproduced outputs of the heads Hf and Hg, which include pilot signals having frequencies f1 and f2. BPF80.81 is f
This is a filter for separating the )l component and 2f)l component, and the outputs of the BPFs 80 and 81 are level-detected in detection circuits 82 and 83, and then compared in level in a comparison circuit 84.

Here, the f)l component corresponds to f2 and the 2fH component corresponds to fl, so the direction in which f2 is generated is the tape traveling direction, so the output of the comparison circuit 84 directly becomes a tracking error signal.

The switch 86 is controlled by a signal obtained by shifting the phase of the pulse P3 by 90 degrees by a phase shifter 91, and at the timing of tl, the comparator circuit 84
Sample the output signal directly from the circuit (S/H)
Supply to 90.

As the sampling pulse of S/H90, inverter 87.88. The rising and falling edges of pulse P3 detected by an edge detection circuit including exclusion pull-off circuit 89 are used. The level sampled by the S/H 90 is held for one field period until the next sampling, and is supplied to the capstan motor control circuit 31 to control the rotational phase of the capstan 32.

Similarly, at the timing shown at t2 in FIG. 9, that is, when the head Hf finishes tracing TR2, the 1 multiplier 7
8 to f2. f4 components are obtained, respectively 2f)1 and f)l
The components are detected and compared. At this time, since the direction in which f4 is generated is the tape traveling direction, the comparison circuit 84
The output of is supplied to the S/H 90 via an inverting amplifier 85. t3. The S/H 90 updates the hold level at each timing t4.

According to the VTR of the above-described embodiment, the cylinder diameter is
Despite the small size of /3, it is possible to obtain a good tracking error signal in both SP and LP modes by using only one type of recording/reproducing head.

(Regarding partial changes in configuration, etc.) Although all of the above explanations have been made regarding VTRs, the present invention can also be applied to other models such as digital audio tape recorders, and four types of pilots can be used. The signals are f1, f2°f4. 1 per track in f3 order
The present invention can be applied to an apparatus for obtaining reproduced information signals from a recording medium in which different types of information signals are recorded in a superimposed manner.

Explanation of the effect> As explained above, according to the present invention, fl.

f2. f3. When reproducing an information signal from a recording medium in which four types of pilot signals each having a frequency of f4 are recorded superimposed on an information signal, the output of the head that is not used for reproduction has (f2+f3)/2. By multiplying signals, it is possible to obtain an information signal reproducing device that can easily obtain a good tracking error signal regardless of the presence or absence of a guard band.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing recording patterns by a conventional VTR. Figure 2 is a diagram showing a recording pattern on a magnetic tape in which guard bands are formed between tracks, Figure 3 (A), (
B) is a diagram showing the head configuration of a VTR according to an embodiment of the present invention, FIGS. A diagram showing a schematic configuration of a reproduction system of a VTR according to the same embodiment.
Figures 7(A) and (B) are diagrams for explaining the state of tape tracing by the VTR of the same embodiment, and Figure 8 is a schematic diagram of the playback system of the VTR of the same embodiment. FIG. 9 is a timing chart showing the waveforms of each part in FIG. 8. 1 is a magnetic tape as a recording medium, 12° 13 is a track group, 20 is an fO oscillator, 23 is a multiplier, 24.25
are band-pass filters, 26 and 27 are detection circuits, 28 are comparison circuits, 31 are capstan motor control circuits, 32 are capstans, 78 are multipliers, 79 are fO oscillators, and 80 and 81 are band-pass filters, respectively. ,82.83
84 is a comparison circuit, 90 is a sample and hold circuit, Ha and Hb are respectively rotary heads as second heads, and Hc. Hd is a rotating head as a first head, He, H
f, Hg, Hh are rotating heads fl as the first head or the second head, respectively. f2. f3. f4 is the frequency of each pilot signal. 1 口Ha AP yan 2 口 4th ward (A) 4th prisoner (B) Tz Yumo 6 Zaoto (BnMe Hf Mjl l+y
7th Ward (A) 7th Exit ('B)

Claims (1)

[Claims] The respective frequencies are f_1, f_2, f_3, f_4 (however, f_4-f_3=f_2-f_1 and f_2≠f_
3) The four types of pilot signals are f_1, f_2,
A device for reproducing information signals from a recording medium in which one type of information signal is recorded in the order of f_4 and f_3 for each track in a superimposed manner, and a predetermined frequency f_0 ( However, f_0=(f_2+f_3
)/2) and detects a tracking error of a second head that reproduces the information signal using the multiplication output.