JPS6016793B2 - Video signal recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal recording apparatus applied to, for example, a rotating two-head type VTR'.

As shown in FIG. 1, in a rotary two-head type VTR, a magnetic tape 2 is transferred in the direction of arrow a in a circle-shaped manner on the circumferential surface of a cylindrical tape guide 1, and the magnetic tape 2 is rotated at an angle of 180 degrees with respect to the magnetic tape 2. Two rotating magnetic heads 3a and 3b (rotating in the direction of arrow b) arranged with an angular interval of , are arranged to alternate in pairs.

Then, as shown in FIG. 2, the magnetic tape 2 has sequentially inclined tracks such that the track Ta by the rotating magnetic head 3a and the track Tb by the rotating magnetic head 3b are adjacent to each other. In this case, one field of the video signal is recorded as one track (Ta or T° C.). Further, as shown in FIG. 2, the running speed of the magnetic tape 2, the diameter of the tape guide 1, and the rotating magnetic heads 3a and 3 are adjusted so that the horizontal synchronizing signals of adjacent tracks Ta and Tb are aligned in a direction perpendicular to these tracks.
An angular spacing of b is chosen.

Therefore, the starting end of the recording position in the track Ta where the video signal of a certain odd field is recorded and the starting end of the recording position in the track Tb' where the video signal of a certain even field is recorded are in the extending direction of each track. With a wish to put (
nsu) Daily offense 1. There will be differences between groups. However, n
'0 or a positive integer is the distance in the track extension direction between recording positions of adjacent horizontal synchronization signals on the same track. In this way, adjacent tracks Ta and Tb
Aligning the horizontal synchronization signals of the This is to avoid the same-field disturbance when the rotating magnetic head scans across a plurality of tracks, such as during still playback.

The reason why the influence of crosstalk between tracks becomes less noticeable is as follows. First, it is generally known that when the modulation frequency is p and the angular frequency changes by Δ when FM modulated with a modulation signal of level B, the FM modulation wave becomes as shown by the following equation. e=E.

Ship C (Ct + main input) dE.

COS (QCt+m$inpt) NiEQ re.

(mf) COS Ct Jugen, (mf) sinwctsi
npt + illusion 2 (mf) cos2p and oS ct 10 J3 (mf) Sjn3ptSin Ct + illusion 4 (mf
)cos4.

oS■ct 10 J5 (mf) Sjn5ptSin Ct
+,. ,,． ,} ,. , [1} However, in the above formula, mf=
It is a Bessel function of the first kind of order m related to Jm (M Kawasuko).

Now, considering the case where mf《1, Jo(mf)≠1
, J, (mf)≦, since the first Funasse're function of higher order than J2(mf) is zero, from the addition theorem, e≠E.

[Jo(mf)coswCt+J・(mf){COS(C1p)t −■S(C+p)t}]

≠E.

(C. Shoes Ct ten filial {COS~-p) C+ of t-cos
)t} ...{2'. Now, let us consider the FM demodulation process when a level A signal having a frequency p lower than a carrier wave having a level of 1 exists as shown in the frequency spectrum of FIG. 3A.

The frequency vector spectrum shown in FIG. 3A can be considered by decomposing it as shown in FIG. This figure C in FIG. 3 is similar to the frequency spectrum of the FM modulated wave expressed by the above-mentioned equation '2}. That is, in both cases (A=mf
= half) The relationship decreases. Therefore, since (ΔB), it can be seen that if the level A is constant, the larger the frequency deviation p with respect to the carrier frequency, the larger the demodulation level B becomes. When considering the reproduction operation of a VTR, the original signal reproduced from a certain track Ta by scanning is the carrier wave in FIG. 3A, and the carrier wave from the adjacent track Tb is the original signal reproduced from this track Ta.

This is a signal whose Stoke is at level A, and can be associated with the signal shown in FIG. 3A when it is FM demodulated. Furthermore, from the above considerations, it is preferable that the smaller the frequency deviation p between the main signal and the crosstalk, the smaller the noise due to the crosstalk that is FM demodulated. Since video signals have a field correlation, if the horizontal synchronization signals between adjacent tracks are aligned in the direction orthogonal to this track, the difference in the level of crosstalk from the original video signal played at the same time Therefore, the frequency deviation p can be reduced, and the influence of crosstalk can be reduced. One way to reduce the effects of crosstalk when recording at high density without providing a guard band is to
There is a method that utilizes azimuth loss by making the directions of the gaps of two rotating magnetic heads different, but it is also desirable to align the horizontal synchronization signals in this method as well.

However, there are cases where the alignment of horizontal synchronizing signals cannot be satisfied.

That is, when the magnetic tape 2 is run at a certain tape speed, the starting end of the recording position on the track Ta and the track T
The starting end of the recording position in b is the distance of 1 in the extending direction of each track. If there is a difference in spots, use magnetic tape 2.
If the speed is slowed down to 2/3, the above distance becomes IH as shown in Figure 4A, and conversely, if it is doubled,
As shown in FIG. 4B', it becomes coarse, and the alignment relationship of the horizontal synchronizing signals no longer holds true. Changing the tape speed in this way has benefits such as enabling long-term recording and playback using the same device. The tape speed can be changed by changing the rotational speed of the capstan or its rotation. Also, when changing the tape speed, especially when it is slowed down, it is desirable to narrow the effective track width, but this is not necessarily necessary if the crosstalk suppression operation is sufficient, and furthermore, the change in the track neck angle is small.・And can be ignored. Based on the above considerations, the present invention aims to guarantee the alignment of horizontal synchronizing signals between adjacent tracks even when the tape speed is changed in the same device. The corner lamps of the two rotating magnetic heads are made to be different when the magnetic head is rotated.

An embodiment of the present invention will be described below.

FIG. 5 shows rotary magnetic heads 3a and 3b arranged at an angular interval of 180 degrees, which are used when running the magnetic tape 2 at a first tape speed (normal tape speed), and one rotary magnetic head 3b. A separate rotating magnetic head 3c is provided at an angle y with respect to the corner lamp. This angle is determined by the distance 6 between the respective gaps of the rotating magnetic heads 3b and 3c on the magnetic tape 2 that is forced onto the circumferential surface of the guide drum 1 (6=(n+season)).
H). With this configuration, when the magnetic tape 2 is running at the first tape speed,
The rotating magnetic heads 3a and 3b are alternately placed on the magnetic tape 2 so that, as shown in FIG. 1. Differences in spots occur to align horizontal synchronizing signals between adjacent tracks.

Next, while the magnetic tape 2 is running at a second tape speed that is 2/3 of the first tape speed, the rotating magnetic head 3
When a video signal is recorded using a and 3c, a track pattern as shown in FIG. 6 is obtained. In Figure 6,
Track Ta is driven by a rotating magnetic head 3a,
Track Tc is formed by a rotating magnetic head 3c.
If the deviation y of the rotating magnetic head 3c with respect to the rotating magnetic head 3b is set to (6=0, square),
When moving from truck Ta to truck Tc, the difference between the female end of both trucks is 1.9 days, and when moving from truck Tc to truck Ta, the difference between the female end of both trucks is 0.9 days.
Therefore, the average value is IH. Therefore, horizontal synchronization signals can be aligned between adjacent tracks. Further, as shown in FIG. 7A, the two rotating magnetic heads 3a and 3b used at the first tape speed and the corner between the two rotating magnetic heads 3a and 3b used at the second tape speed, i.e., (180o x y). The two rotating magnetic heads 3c and 3d may be provided with the same rotation center.

In this case, it is not necessary to arrange each set of two rotating magnetic heads adjacent to each other at an approximately 90° angle as shown in the figure, but any suitable angle may be used. In addition, when the diameter of the guide drum 1 is about 7 mm, the diameter 6 is very small, such as about 600 microns, so as shown in FIG. and the respective cores 4a and 4b
A composite head having an integral structure that forms two gap shafts and a bag with an interval of 6 mm may be applied to the rotary magnetic heads 3b and 3c shown in FIG. Furthermore, in the above embodiment, a rotary magnetic head used at the second tape speed is used, which is different from the rotary magnetic heads 3a and 3b used at the first tape speed. As shown, one rotating magnetic head 3b
The video signal may be recorded on the magnetic tape running at the second tape speed by rotating the magnetic tape by 6 relative to the position when recording at the first tape speed.

As a means for moving the position of the rotary magnetic head in this manner, a means can be used in which the rotary magnetic head is supported by a piezoelectric element and an electric field is applied to the piezoelectric element to cause the head to be displaced. As is clear from the above, according to the present invention, in a video signal recording device in which horizontal synchronizing signals between adjacent tracks are aligned at a first tape speed, Even when changing to a tape speed of 2, horizontal synchronization signals can be guaranteed to be aligned, and when the rotating magnetic head scans across multiple tracks during playback, there will be no synchronization disturbance, and there will be no influence from crosstalk from adjacent tracks. The advantage is that long-term recording is possible without deterioration of playback image quality.

It is also conceivable to use a delay line or the like to delay the recording video signal and align the horizontal synchronizing signals, but there are problems with the delay line or the like, such as insufficient coverage. On the other hand,
In the present invention, since the position of the rotating magnetic head is changed, there is an advantage that it is not affected by the characteristics of the delay line.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a rotary two-head type VTR to which the present invention can be applied, FIG. 2 is a diagram showing its track pattern, and FIGS. 3 and 4 are frequency spectrum and A schematic diagram of a track pattern, FIG. 5 is a configuration diagram of an example of the present invention, FIG. 6 is a schematic diagram of a track pattern used for explanation thereof, and FIGS. 7 and 8 are respective diagrams of other examples of the present invention. FIG. 2 is a configuration diagram of an example. 1 is a guide drum, 2 is a magnetic tape, and 3a to 3d are rotating magnetic heads. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1 Two rotating magnetic heads arranged at a first angular interval record video signals on a magnetic tape running at a first tape speed to form tracks sequentially, and adjacent tracks are are arranged so that the horizontal synchronizing signals are aligned, and when the magnetic tape is running at a second tape speed different from the first tape speed, the first
A video signal recording device configured to record video signals while maintaining the alignment of the horizontal synchronizing signals using two rotating magnetic heads arranged at a second angular interval different from the angular interval.