JPS6280803A - Information signal recording device - Google Patents

Abstract

PURPOSE:To attain excellent consecutive recording by using a pilot signal specific in plural pilot signals so as to stop the recording at the end of recording and reproduced by a rotary erasure head tracing the recording medium ahead a rotary recording head at the start of recording. CONSTITUTION:Heads A, B having a prescribed azimuth angle mutually in the carrying direction 2 of a magnetic tape 1 are used to form recording tracks A1, B1, A2, B2, A3, B3, pilot signals having four kinds of different frequencies f1-f4 are recorded sequentially on a recording track 4 in the running direction 3 of the heads at each track and the frequency difference from adjacent tracks is fH for the right side and 3fH for the left side. The frequency differences fH and 3fH are extracted to compare the level in this way and the deviation of head from the main scanning track is obtained. Thus, the titled device is provided with a local pilot generator 7, BPFs 9, 10, detectors 11, 12, a level comparator circuit 13 and an inverting amplifier 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for recording a plurality of different types of pilot signals cyclically for each track together with an information signal.

[Conventional technology]

Conventionally, as this type of information signal recording device, for example, a helical scan type video tape recorder (hereinafter referred to as VTR) that performs tracking control using the n4 frequency method has been used.
There is.

In this VTR, the following methods have been conventionally used to seamlessly record a new video signal from the end of the video signal already recorded on the magnetic tape. Ta. First, when a temporary stop is commanded during recording, the magnetic tape is immediately rewound by a predetermined amount for a predetermined time t0. Then, once the magnetic tape is stopped, and then the temporary stop is released, the magnetic tape is run at a normal running speed while controlling tracking. Furthermore, during a certain time t1, what about the mouse that was rewound earlier? After running the tape for a small amount of time, a new video signal was recorded from the beginning of the track in synchronization with the head switching signal.

[Problem that the invention seeks to solve]

In the conventional information signal recording apparatus as described above, when recording a new signal following an already recorded information signal, the above-mentioned period t. and 1. Since a new signal is overwritten on a track that has already been recorded during a period corresponding to the difference, there is a problem in that the reproduced image quality of that portion deteriorates.

This invention has been made to solve these problems, and is an information signal that can perform good continuous recording without overwriting the already recorded portion at the start of recording and without disturbing the track pattern. The purpose is to provide a recording device.

[Means for solving problems]

In the information signal recording device according to the present invention, when recording is finished, recording is stopped at a track where a specific pilot signal is recorded among the plurality of types of pilot signals, and when recording is started, the information signal is placed on the recording medium prior to the rotating recording head. The recording start timing is determined using a pilot signal reproduced by a rotating erasing head that traces the data.

[For production]

In the above configuration, the FEH is put into the playback state, the pilot signal already recorded on the recording medium is played back, and the recording state is constantly monitored using the playback pilot signal, so that recording can be performed at good timing. Now you can start.

〔Example〕

First, a method of creating a tracking control signal using the four-frequency method used in the embodiment of the present invention will be briefly described. FIG. 5 is a diagram showing a recording magnetization locus of a VTR that performs tracking using a four-frequency system, and FIG. 6 is a block diagram showing a main part of a reproducing circuit for obtaining a tracking error signal.

In FIG. 5, numeral 1 indicates a magnetic tape, and arrow 2 indicates the direction in which the magnetic tape 1 is transported.

AIs Bt t A2 s B2 . . . are recording tracks recorded by heads A and B, each having a predetermined azimuth angle with respect to each other, and arrow 3 indicates the scanning direction of the heads. On the recording track 4, pilot signals of four different frequencies (indicated by f, to f4) are sequentially recorded for each field (that is, for each track) together with the video signal.

The recording order of pilot signals is the order shown in FIG.
For example, track A1 has fl, for example 102.5 KE
(6.5fH in z) Rack B1 has fl, for example 11
8.9 KF (z near, 5fH,) rack A2 has f3
, for example, 165.2 KHz = 10.5 fH,) rack B2 has fl, for example, 9.5 f in 148.7 KHz.
A pilot signal of H, is recorded superimposed on the video signal. (Note that fH indicates the frequency of the horizontal synchronizing signal.) The frequency difference of pilot signals between adjacent recording trunks is fH or 3fH as shown in the figure. When the head scans track Ai (i=1.2.3...), the frequency difference with the pilot signal of the adjacent track on the right side of the figure is always fH, and the frequency difference with that on the left side is always 3fH. be. Also, the head is Bi (""is 2,3
(Contest) When scanning a track, the frequency difference with the adjacent track on the right side is always 3fH, and the frequency difference with the adjacent track on the left side is always fH.

Note that since the pilot signals f and -f4 are both relatively low frequency signals, even in azimuth recording, the head can reproduce the pilot signals from adjacent tracks other than the main scanning track as crosstalk. That is, the pilot signal detected when the head is main-scanning track A2 is a composite signal containing frequency components of f4+f2+f3, and the center of the head's trace locus exactly matches the center line of the main-scan track. (on-track), the pilot signals f, , f4 of the adjacent tracks are at the same level, and if the head slightly deviates from track A2 toward the B2 side, fl is larger than fl, and the head slightly deviates from track A2 toward the B2 side. If it shifts to the Bi side, fl is reproduced larger than fl.

Therefore, the difference signal between the pilot signal on the main scanning track and each pilot signal on both adjacent tracks, that is, fH and 3fH
By separating and extracting the signals and comparing the levels of both difference signals, the direction and amount of deviation of the head from the main scanning track can be determined.

FIG. 6 is a circuit block diagram of such a four-frequency system. In the figure, a reproduced signal in which a video signal and a pilot signal are superimposed is input from terminal 5, and a low-pass filter (LPF) is input.
, 6, only the pilot signal component is separated. A multiplier 8 multiplies the pilot signal component by the local pilot signal generated by the generation circuit 7. The local pilot signal is a signal having the same frequency as the pilot signal recorded on the main scanning track, and as described in the explanation in FIG. 5, if the current track A2 is the main scanning track, the output of the LPF 6 is f2. The frequency of the local pilot signal is f, including f, components.

It is. Therefore, the output of multiplier 8 is f,, f,, f
A signal having a frequency of the sum and difference of 3 and f3 is output t'
L. The band pass filter (BPF) 9 is a circuit that extracts only fH1 and 3fH signals from the sum and difference signals, and the output is sent to the next stage detection circuit 1.
1 and 12 for detection and rectification, respectively.

Next, the fH signal component and the 3 fH signal component are supplied to a level comparison circuit 13, which outputs a signal corresponding to the level difference between them. That is, when the reproduction level of the fH signal is higher than the reproduction level of the 3fH signal, a positive potential corresponding to the level difference is extracted, and in the opposite case, a negative potential is extracted. As a result, a signal containing information on the amount and direction of the head's track deviation is output, so this can be used as a tracking error signal.

Next, if this continues as it is, as explained in FIG. 5, the relationship between the track Ai and the track Bi in the head deviation direction tracking error signal will be opposite to each other.
Furthermore, it is necessary to provide a switching circuit 16 downstream of the level comparator 13, which selectively outputs what passes through the inverting amplifier 14 and what does not pass, using a head switching signal 15.

A VTR equipped with FEH using such a tracking method will be explained with reference to FIGS. 7, 8, and 9.

In FIG. 7, recording and reproducing heads A and B are arranged on a rotating drum to face each other with a phase difference of 180 degrees, and the FEH is a pair of recording and reproducing heads A and B.
H is provided 90 degrees behind head A in the rotation direction and 90 degrees ahead of head B in the rotation direction.

The head widths and relative mounting heights of these heads A, B, and FEH are shown in FIG. In FIG. 8, a pair of heads A and B have a width slightly wider than the trunk width Tw, that is, WAWB, and a pair of heads A and B have a width that is more than twice the track width Tw, that is, WFE! FEE with
are shown corresponding to the state shown in FIG. In other words, 1 B0 → A due to heads A and B having different azimuth angles.
l-+B I-+ A 2-+ B 2→A3→33
3-+A4, and the pilot signals fl+f2s f3+f4 explained in FIG.
is recorded along with the information signal.

FIG. 8 shows the timing at which head A has completed recording and tracing on track A4, and head B is about to begin recording and tracing on the next track, track B4. In this state, FEH is head A.
, B, and is supplied with an erasing signal to erase the track that is about to be recorded by heads A and H in advance. For that reason, FE
The relative height of the FEH is such that the left end of the FEH is located to the right of the width wA of the track A4 so as not to affect the already recorded track A4.

FIG. 9 is a diagram showing the trace state of each head on the track during reproduction. In FIG. 9, when the head A is accurately tracing the track A where the pilot signal fl is recorded (just tracking), the FE
If H is set to regenerate state, the adjacent pilot signal f
Each pilot signal f2゜f, , f4 is obtained from track B1 where 2 is recorded, and a pilot signal f adjacent thereto, and track A1 where a pilot signal f adjacent thereto is recorded, and track B where a pilot signal f adjacent thereto is recorded.
, and the pilot signal f! of track A that head A is tracing. is not detected.

Furthermore, the detected pilot No. 6'2*f3
+f4 detection level is f3. f2 is detected at a large level, and f4 is detected at a level smaller than them.

In the ninth @, when the head B shown by the dotted line traces the track B where the pilot signal f2 is recorded in the next field, this FEH is the same as the above-mentioned tracing state.

Also, when head A is just tracking track A where pilot signal fs is recorded, FE
The detected pilot signals of H are fl, f,.

fl, and the detection levels of these signals are f,,f,.

is large, and f2 is detected at a level smaller than them.

1FXJ is a block diagram showing the main part configuration of a VTR which is an embodiment of the present invention, and FIG. 2 is a circuit diagram of the circuit shown in FIG.
FIG. 4 is a diagram showing the positional relationship of heads when recording a new signal following an already recorded track.

In Fig. 1, 18 is FEH, 19 is a regeneration amplifier (A
24125 is a detector, 2G is a comparison vessel, 27
is a terminal.

In the apparatus configured as described above, FIG. 2 shows the timing immediately before recording a new signal following such a recorded track, with the track recorded by head B as the final track. .

Now, when a temporary stop is commanded during recording, the magnetic tape is recorded up to the recording track f4, the magnetic tape is rewound by a predetermined amount, and the magnetic tape is temporarily stopped. Next, when the temporary stop is released, the magnetic tape is run at a normal running speed while tracking is controlled. At this time, the FEH shown in Figure 1
18 is set to regeneration mode and the vehicle is run while reproducing the pilot signal. The reproduced pilot signal reproduced by the FEH 18 is amplified by the AMPL 9, and then sent to the recording/reproducing head A.

A multiplier 20 multiplies the local pilot signal supplied to B by a local pilot signal having the same frequency. The outputs of the BPFs 22 and 23 are respectively sent to the next stage detector 24.
．． 25 for detection and rectification. Next, the fH signal component and the 4 fH signal component are supplied to a comparator 26,
A signal corresponding to the level difference between signals fH and 4fH is output.

A temporary stop is made during recording, and then, after the stop command is released, the tape starts running while tracking control is performed by heads A and B in the head configuration shown in FIG. If the phase relationship of each head at this time is as shown in FIG. 9, the output of the tracking signal by the FEH 18 will be obtained at the terminal 27 in accordance with the amount of the fH acid component 4fH component, so that the power supply voltage +Vcc, which is half of (Vcc), is obtained.

After that, when the tape advances and the end of FEH is reproducing half of the unrecorded part as shown in Figure 2, only the f4 signal component is obtained from the already recorded part, so fH
Since the signal component of fl becomes large and the signal component of fl cannot be obtained, the component of 4fH becomes 0, and the output of the comparator 26 at the terminal 27 becomes high. Therefore, if this high signal is detected and the recording mode is set at the next timing when head A starts tracing, there will be no overwritten portion, and when this joint portion is reproduced, there will be no deterioration in the reproduced image quality.

In addition, FIG. 3 is an example of a modified version of the circuit in FIG.
The phase relationship between H and the head is shown in FIG.

In Figure 3, 4fH and 3f from the FEH playback output.
The objective can be achieved similarly by comparing the components of H. Here, it is assumed that the track to be recorded immediately before the end of recording is the track in which f is recorded.

That is, in FIG. 4, when the end of FEH is reproducing half of the unrecorded portion, only the signal component of f is obtained from the recorded portion of the tape, so the component of 4fH becomes large.
Conversely, since the f4 signal component is not obtained, the 3fH component becomes 0, and the output of the comparator 26a at the terminal 27a becomes high.

Therefore, if this high signal is detected and the recording mode is set at the next trace start timing of head B, there will be no overwritten portion.

Please note that the installation of the FEH is as shown in Figure 2 or Figure 4 depending on the height accuracy.
Even if the phase relationship shown in the figure cannot be obtained, the same effect as in the above example can be obtained by adjusting the gain of the BPF in FIGS. 1 and 3.

〔Effect of the invention〕

As explained above, the present invention reproduces the pilot signal of the already recorded track using FEH, and uses the reproduced output to determine the recording start timing, thereby creating a new recording section between the already recorded section and the newly recorded section. There is an effect that there is no overwriting in the joint portion and that the track pattern is not disturbed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main part configuration of a VTR as an embodiment of the present invention, FIG. 2 is a diagram showing the positional relationship of the head on the recording medium in the VTR of the embodiment of FIG. 1, and FIG. The figure is a block diagram showing a modification of FIG. 1, FIG. 4 is a diagram showing the positional relationship between the FEH and the head corresponding to the modification of FIG. 2, and FIG. Figure 6 is a block diagram of four-frequency tracking control, Figure 7 is a diagram showing an example of the rotational positional relationship between the FEH and the head, and Figure 8 is the recording when using the FEH. FIG. 9 is a diagram showing an example of the positional relationship of the heads during playback of a recorded tape. In the figure, 18 is F'F:W, 19 is AMP, 20 is a multiplier, 21 is a local pilot signal generator, 22.
23 is a band pass filter (BPF), 24.degree. 25 is a detector, and 26 is a comparator. Agent Patent Attorney 1) Haru Kitatake 1 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5' Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] A device for recording a plurality of different types of pilot signals together with an information signal cyclically for each track, which includes a rotating recording head and a rotating erasing head that traces a recording medium in advance of the rotating recording head, and when recording is finished, the above-mentioned An information signal characterized in that recording is stopped at a track for recording a specific pilot signal among a plurality of types of pilot signals, and when recording starts, the recording start timing is determined using the pilot signal reproduced by the rotary erasing head. Recording device.