JPS63227287A - Video signal reproducing device - Google Patents

Abstract

PURPOSE:To prevent bar noise from being generated at the time of reproduction at variable speed without using a double azimuth head, by providing at least one of auxiliary heads of a single chip head in the neighborhood of a pair of main heads by providing stages. CONSTITUTION:A pair of main heads 16a and 16b with different gap double azimuth mutually arranged so as to be placed at a position symmetrically to the central axis 0 of the drum 6 of a rotary head to reproduce a video signal from an inclined track by the rotary head are provided. The auxiliary head 17a and/or 17b having a prescribed gap azimuth arranged adjacently to at least either the main heads, and arranged at a prescribed allocation angle position thetax from the central axis O of the drum 6 and also arranged by providing the stage Dx by a time corresponding to the allocation angle from the main head on one side are provided, And a tape 1 is wound on the drum 6 additionally by a prescribed allocation angle, and an output in which the main heads 16a and 16b and the auxiliary head 17a and/or 17b are switched in one field can be taken out at the time of reproduction at the variable speed. In such a way, it is possible to obtain a reproduced image without bar noise at the time of reproduction at the variable speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a video signal reproducing device, and more particularly to a video signal reproducing device capable of obtaining a video screen free of bar noise during variable speed reproduction.

[Summary of the invention]

The present invention provides a video signal reproducing apparatus in which at least one field of video signals is recorded on each one mft%) rack on a tape, and the video signal is reproduced from the tilted track by a rotary head. a pair of main heads with mutually different gap azimuths, which are disposed at symmetrical positions with respect to the drum center axis of the rotary head for reproducing video signals; and at least one of the pair of main heads. an auxiliary head having a predetermined gap azimuth disposed adjacently at a predetermined angular position from the central axis of the drum and stepped from one main bed by a time corresponding to the arranging angle; An extra layer of tape is wrapped around the drum by the amount of the assigned angle, and the output from the main head and auxiliary head are switched within one field during variable-speed playback to remove bar noise during variable-speed playback. .

[Conventional technology]

Traditionally, in video tape recorders (VTRs), normal playback, in which a rotary head sequentially scans the inclined track on which the video signal is recorded to reproduce the video signal, is different from the tape running speed during recording. There is variable speed playback, in which a rotating head traverses a plurality of slanted tracks on a tape running at a high speed.

FIG. 6A shows the scanning trajectory of the rotary head on an inclined track on the tape when the tape running speed is six times that during recording. To explain about FIG. 6A, there are 18 tapes with different gap azimuths on the tape (1).
Inclined track ^11 Bt + A2 + B when recorded with a pair of rotations divided by 0° angle Rad Ha, Hb
2...Ae+BG is shown. tape! 1
During variable speed playback when 1 is running at 6x speed, the head H
δ has six inclined tracks At, B1. A2. B2. A
ll Bl is scanned diagonally across, and the head Hb also has six inclined tracks A41 B11 Al51
8! 1, AG, Bl; is scanned diagonally across. Normally, one field of video signals is recorded on one track, but in 6x variable speed playback, six pI4I4
The video signals of Sitrac At 21 A 3, B41 BS, and B6 are taken out. As shown in Figure 6B, the horizontal axis represents time and the vertical axis represents the video playback output level.
R obtained from Herad Ha and Hb when played at double speed
Considering the envelope of F (No. 6 (reproduction high frequency output signal)), in head Ha, trunk At due to the azimuth angle
, A2, A3 portions, and the head Hb extracts the RF multiplied signal only from track B4. B.S.

The RF multiplied signal is extracted from only the 86 portion, and the RF multiplied signal envelope shown in FIG. 6B is obtained. As is clear from FIG. 6B, head Ha is used to record tracks B, B2. Bi, recording track A4 + As * A on head Hb
At a position crossing G, the RF multiplied signal output level becomes small, and bar noise is generated at this part during reproduction. 6th
Figures C and D show bar noise (2
It shows the timing at which a) to (2c) and (3a) to (3c) occur.

When such bar noise is generated on the screen of a cathode ray tube,
As shown in Figures A and B, in the N field obtained with head Ha, there are two bar noises (2a) in the screen (4),
(2b) will appear, and there will be one bar noise (2c) below the screen (out of season).Furthermore, in the N+1 field obtained with head Hb, two bar noises (2c) will appear at a position shifted from the N field mentioned above. 3b).

(3c) appears, and there is one bar noise (3a) above and outside the screen (4).

The number of bar noises generated in this way differs depending on the multiple of the steady running speed of the tape during variable speed playback, but in order to remove such bar noises, conventionally, negative and positive signals as shown in Figure 8 have been used. Double azimuth rotating heads (5a) and (5b) consisting of heads Ha (Ha') and Hb' (Hb) with gap azimuth are prepared, and four heads are arranged around the circumference of the drum (6) as shown in Fig. 9. These double azimuth rotating heads (5a) arranged in a configuration
, (5b) are switched within one field to narrow the width of bar noise generated during variable speed reproduction. This will be explained by taking as an example the case of 6x variable speed playback shown in FIG. 6A.For example, track A1. When crossing the trunks Bl, B2, B3 recorded with A2, Ay and positive azimuth, the negative azimuth track A1°A2. A
3 is a track Bl reproduced with a negative azimuth head Ha and recorded with a positive azimuth.

In the 821B3 portion, the output is switched to the output of the head Hb' having a positive azimuth for reproduction. or,
When the head Hb of the double azimuth head (5b) with a positive azimuth crosses tracks A4, As, and Ac recorded with a negative azimuth and tracks B4, Bs, and B@ recorded with a positive azimuth, a positive azimuth occurs. Tracks B4, Bs, B recorded in
In the section s, the head Hb with a positive azimuth plays back, and track A4 recorded with a negative azimuth.
+As*As is reproduced by switching to the output of the head Ha' having a negative azimuth, thereby obtaining the RF multiplied signal envelope shown in FIG. 6E. Incidentally, FIG. 6F shows the switching timing signal (4). If we use a 4-rad configuration like this, the bar noise (2a), (2b),
(2c).

Variable speed regeneration can be performed without producing (3a), (3b), and (3c).

Further, as shown in Fig. 1θ, one double azimuth rotating head (5a) having plus and minus azimuth heads Wb' and Ha,
5a) A head Ha with a negative azimuth and a rotating head with an opposite positive azimuth) The drum device configured and the first
It is also known to use a digital memory (field memory) shown in FIG. 1 to remove bar noise during variable speed playback.

FIG. 11 shows a system diagram of a digital memory.

The head Ha * Hb + Hb' is connected to the input terminal T1.
The video signal output is input, and the video signal is output to the output terminal T2. When the switching means (7) switches the movable contact piece a to the fixed contact C side, it becomes the normal forwarding state, and when it switches the movable contact piece a to the fixed contact side, it enters the variable speed regeneration state. Input terminal T
1 is digitally converted in an A/D conversion circuit (8) and stored in a memory (10) via a memory controller (9). The memory (10) is a digital memory that can store one field's worth of video signals.

The stored digital data read from the memory (10) is sent to the D/A conversion circuit (1) via the memory controller (9).
1) is converted to analog and low II! i pass filter (LP
F) (12) and is output to the output terminal T2 via the fixed contact of the switching means (7).

With the drum device shown in Fig. 10, the tape (1
) is 6x speed, the output of the head Ha is constant while the double azimuth head (5a) having a negative gap azimuth crosses the track A 1 + A 21 A 3 recorded with a negative recording azimuth. is taken out as it is, and the head Hb with a positive azimuth is a track Bl with a positive azimuth head.
, B2, and B3, the output of Hb is taken out from Hb, and these RF multiplied signals are switched to generate Hb as shown in Fig. 6E.
Hb' + Ha + Hb' . . . The envelope signal (13) is obtained, and the drum (6) where the double azimuth radius (5a) is in contact with the tape (1) is obtained.
In the half cycle of , the head Ha.

, Hb' is written in the memory (lO) of Fig. 11. Next, the RF multiplied signal outputted by Hb' is written into the memory (lO) of Fig. 11. In the half cycle of 6), the RF/i signal is taken out only when it crosses the trunks B4, Bs, and Bs recorded with positive azimuth, as shown in Fig. 6B, so as shown in Fig. 6, 3a, Bar noise occurs in the parts indicated by 3b and 3c.Therefore, as shown in FIG. As shown by the arrow, the head Ha in FIG. 9 mentioned earlier is read out.
It is possible to perform variable speed reproduction without generating bar noise by performing field skipping in place of the RFM signal obtained in '.

Furthermore, two rotating drums Ha are arranged symmetrically with respect to the center axis of the drum at an angle of 180° and have mutually different gap azimuths.
, Hb, and a bar noise interpolation method at even multiple speeds using a digital memory shown in FIG. 11 is also known. In this case, the RF multiplied signal 1 without bar noise
Since it is obtained alternately for each field, this is stored in memory (10
) and read it out twice each time, a noiseless 2x speed reproduced image can be obtained.

[Problem that the invention seeks to solve]

As mentioned above, in order to remove bar noise during variable speed playback,
As shown in FIGS. 9 and 10, when double azimuth rotating heads (5a) and (5b) are used, powder and dust from the magnetic tape is removed by the leading head Ha or )(b) from the rear head Hb' or Ha'. This not only causes problems such as clogs that can get into the gap between the drums and cause clogging, but also has the drawback of being extremely difficult to manufacture.Furthermore, when using a two-head drum device and digital memory, variable-speed playback can be performed at even multiple speeds. In addition, there was a drawback that a skew problem occurred due to unevenness of the H arrangement (horizontal synchronization signal arrangement) due to jitter.

The present invention has been made in view of the above-mentioned drawbacks, and its object is to provide a video signal reproducing apparatus that does not generate bar noise during variable speed reproduction without using a double azimuth head.

[Means for Solving the Problems] The video signal reproducing device of the present invention has at least one field of video signal recorded on each diagonal track on the tape,
This p! ! The central axis O of the drum (6) of the rotary head is used to reproduce the video signal by the oblique toshitrack rotary head.
A pair of main heads (16a) with mutually different gap azimuths are arranged so as to be symmetrical with respect to each other.
16b), this main head (16a), (1
6b), at a predetermined allocation angle position θ from the center axis 0 of the drum (6), and with a step Dx from one main head for a time corresponding to this allocation angle. It has an auxiliary head (17a) or/and (17b) arranged with a predetermined gap azimuth, and an auxiliary head (17a) or/and (17b) having a predetermined gap azimuth. Head (16a)
, (16b) and the auxiliary head (17a) or/and (17b) are switched within one field to take out the output.

[Effect]

According to the video signal reproducing device of the present invention, at least one auxiliary head of 7-chip single head is provided with a step near a pair of main heads, so that variable speed reproduction can be performed without bar noise without using a double azimuth head. An image is obtained.

〔Example〕

An embodiment of the video signal reproducing apparatus of the present invention will be described in detail below with reference to the drawings.

In the present invention, a case will be described in which variable speed playback is performed using a tape with a pattern recorded in accordance with the 8 mm video standard.

The recording pattern of an 8mm video tape is as shown in Figure 3, with adjacent trunks (15a) and (15b).

(15c), (15d)... are recorded at different azimuths, and each p7! ! A PCM signal obtained by time-compressing a stereo audio signal is recorded at the beginning of the diagonal tracks (15a) to (15e). For this purpose, the tape wrapping angle on tape (1) is 221°,
Of this, 36° is used for PCM recording and reproduction. An FM monaural audio signal and a tracking pilot signal are superimposed on the 185° portion of the video signal recording portion. Note that a tracking pilot signal is also recorded in a superimposed manner on the PCM signal recording portion.

Since no video signal is recorded in the above-mentioned PCM signal recording portion, there is no need to consider the PCM recording area since it has nothing to do with the occurrence of bar noise during variable speed playback. Based on these points, the video signal reproducing apparatus of the present invention will be explained below with reference to FIGS. 1 to 5.

Fig. 1 is a plan view of a drum showing the head arrangement according to an embodiment of the present invention, Fig. 2 is a front arrangement view of the head showing the head installation state, and Fig. 3 is a diagram of the head arrangement on the track of tape (1). , FIG. 4 is a diagram showing H alignment, and FIG. 5 is a diagram showing timing. In FIG. 1, there is a main rotary head (recording/reproducing rotary head) (16a) consisting of seven single chips with different gap azimuths,
(16b) are arranged symmetrically with respect to the central axis 0 of the drum (6) so that the angle division is 180''.Furthermore, this main head (16a) or (16b) and the central axis 0 of the drum (6) are arranged symmetrically. At a close position between the line connecting and a predetermined angle θX%I!,
RF multiplied signal main head (1
6a).

(16b) and a reproduction-only auxiliary head (17
a) and, if necessary, an auxiliary head (17b) for reproduction only.
to be placed.

The auxiliary heads (17a), (17b) are composed of a single head chip, and the gap azimuth is selected to be the opposite or the same azimuth as that of the adjacent main heads (16a), (16b), as shown in FIG.

Furthermore, the angle θ between the auxiliary heads (17a), (17b) and the main head (lea), (16b)
Auxiliary heads (17a), (
17b) as shown in Figure 2, and there is a step D between them.
x and mounted on a rotating drum.

Figure 2 shows the main heads (16a), (16b) and the auxiliary head (16b) arranged in the side gap of the drum (6).
17a) and (17b) in the height direction, from the lower edge reference line (18) of the main head (16a) and (16b) to the auxiliary head (17a).
), (17b) lower edge reference line (19)
There is a step up to the top. Furthermore, the above-mentioned main head (1
The length Lx on the circumference of the drum (6) between the centers of 6a) (or (16b)) and the auxiliary head (17a) (or (17b)) Since the diameter is 40 m, it can be calculated from the following equation.

Note that θX is the main and auxiliary head (16a) as described above.
), (16b) and (17a), (
17b).

θX Lx-40π ・・・・・・(1) Tape (1) is placed on a drum equipped with a head arranged as described above for approximately 220 mm.
The main head (16a) or (16b) and the auxiliary head (17) for that track on the tape wound over
The positional relationship of a) (or (17b)) is shown in FIG. That is, in FIG. 3, the main head (16a)
, (16b) versus the auxiliary head (17a),
If the gap azimuths of (17b) are the same, the above-mentioned length Lx is an integer n (n-1,
2, 3...) times. That is, it is sufficient to satisfy Lx-nH-=(2).

Also, the main heads (16a) and (16b) at this time
) for the auxiliary heads (17a), (17b
) are the tracks (15a) and (15b
)......If the pitch between them is 'rp, then Dx - (2-m+ 1) Tp +++++・*(3
) (however, m=1.2.3...).

Furthermore, if the gap azimuth of the auxiliary heads (17a) and (17b) is different from that of the main heads (16a) and (16b), the length Lx should be n times the IH in accordance with the adjacent H alignment on the tape pattern. Select a value that adds a fraction α for each recording method, and Lx = nH
+α...It is sufficient if (4) is satisfied.

Also, the main head (16a), (16
auxiliary head (17a), (17
The difference in level from track (15a > , (15
If the pitch between b)... is 'rp, it is necessary to select D x -2mT p --------(51).

If you select the positions of the main heads (16a), (16b) and auxiliary heads (17a), (17b) in this way, they will be separated by the length Lx! ! Since a DK is attached to synchronize the time, even if the tracks played back are different on both heads, they are synchronized in time.For example, in Figure 3, the main head (16a) plays back the PCM recording area (20). The timing of entering the video signal recording area (21) and the timing of the auxiliary head (17a) entering the video signal recording area (21) can be matched. (2) to (5) above
The conditions for selecting the formula will be described in more detail with reference to the H alignment diagrams shown in FIGS. 4A, B, and C.

H alignment of 8mm video tape recorder is NTS
In C method, IH, LP (long time) in SP (standard) mode
mode is 0.5H. Also, in the PAL system, 28. It is IH in LP mode. Figure 4 A is N
This shows H alignment in the LP mode of the TSC method. In Figure 4A, the track for one field (15a
) and an adjacent track (15b) recorded with the opposite azimuth.
Although there is a difference of 0.5H, the adjacent H alignment is achieved. If the gap azimuth between the main head (16a) and the auxiliary head (17a) is reversed, Lx will be Lx xnH + α if the above formula (4) is selected, but if α-0 is considered (
2) is equal to LX-nH in the equation, and the value of Lx is If(,
2H.

This is the stage at this time! ! D x is (5)
The Dx value of the equation becomes 2 m T p . Main head (16a) and auxiliary head (17a')
have the same gap azimuth, Lx is 1, H, 2H, . becomes.

Figure 4B shows H alignment in the SP mode of the NTSC system, and shows the track for the first one field (15
There is a difference of 0.5H between a) and the adjacent track (15b), and the adjacent H alignment is not achieved.

If the gap azimuth between the main head (16a) and the auxiliary head (17a) is opposite, Lx satisfies equation (4)2
Take the value of H+ 0.5H-3,5H and step! ! D x satisfies equation (5). When the main head (16a) and the auxiliary head (17a') have the same gear azimuth, L
x satisfies formula (2), Lx-nH=IH, 2H-...
..., and Dx is placed at a position that satisfies equation (3).

FIG. 4C shows the H alignment of the Beta ■ method, in which the first and second . 2nd and 3rd゜3rd and 4th
．． Fourth and fifth... tracks (15a) to (
Although there is a difference of 0.25H between each track, H alignment is achieved between the first track and the fifth track. In this case, the first track (15a) on which the main head (16a) is arranged
The second track (15b) and the fourth track (15b) adjacent to
15d) If an auxiliary head (17a) having a gap azimuth opposite to that of the main head (16a) is disposed on the main head (16a), the length becomes longer, and x satisfies Lx=nH+α in equation (4), but the second
At the track (15b) position, it is 2H+0.25H, and at the fourth track (15d), it is 2H+0.5H, and the difference in level satisfies Dx=2mTp.

In the case where the main head (16a) and the auxiliary head (17a') are at the same gap azimuth, considering L, the fifth trunk (15e) matches the H alignment with the first track (15a) at the 3H position. However, the H alignment is not correct on the third track (15d), so the fifth track
Truck, 9th truck.

13th Trunk... It is necessary to select a location.

For Dx, in the formula (2m' + 1)Tp, m
It is necessary to select '-2, 4, 6-...

In this way, if the length Lx and step length DK corresponding to the predetermined angle θK of the auxiliary heads (17a) and (17b) are appropriately selected for the main heads (16a) and (16b), the main head (16a) , (16b
) and the auxiliary heads (17a), (17b) are temporally synchronized even if the tracks are played back, so the main heads (16a), (16b)
and auxiliary head (17a).

By switching and using the RF output of (17b), an output with field correlation can be obtained.

Considering the drum configuration shown in FIG. 1, if the video playback device has a digital memory (10) as described in FIG. 11, the main head (16a).

(16b) and the auxiliary head (17a) are arranged on the drum (6), and the RF multiplied signal written in the digital memory is read out in the next half cycle in the same way as explained in Fig. 1O and Fig. 11. A reproduced image without bar noise can be obtained. or,
In a video signal reproducing device without memory (10), the ninth
The main head (16a), (
16b) and auxiliary head (17a), (17
b) A four-head configuration may be used.

Figure 5 shows the timing during high-speed reproduction when a pair of main heads (16a), (16b) and one auxiliary head (17a) are used in the drum arrangement shown in Figure 1. The waveform (23) in Figure A shows the RF switching signal. Take out the double signal 24),
In the next half cycle, the main head (16a) comes into contact with the tape (1) and moves from the negative azimuth track (15a) (see Figure 3) to R of the video signal recording area (21) as shown in Figure 5C.
During the same period when the F-multiple signal 25) is being extracted, the auxiliary head (17a) is delayed from the RF-multiply signal 25) by length Lx and with a step difference Dx from the PCM signal recording area (20) to the video signal recording area (21). ), in the video signal recording area (21), a different recording track (1
5d) (see FIG. 3) to reproduce the RF multiplied signal 26). This playback output is stored in the digital memory (1
0) to skip the field.

As described above, the present invention provides a video signal reproducing apparatus that can eliminate bar noise during variable speed reproduction without using a head such as a double azimuth head, which is expensive, causes a clog problem, and is difficult to manufacture. 4 (Effects of the Invention) The present invention creates a clog by providing at least one auxiliary head of a single-chip head with a step near a pair of main heads, and also enables speed change without using a double azimuth head which is difficult to manufacture. A video signal reproducing device capable of effectively removing bar noise during reproduction can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the head arrangement on the drum of an embodiment of the video signal reproducing device of the present invention, FIG. 882 is a front view schematically showing the head arrangement on the drum, and FIG. 1
Figure 4 is an explanatory diagram of H alignment, Figure 5 is an explanatory diagram of timing, and Figure 6 is a head trajectory and RF signal during variable speed reproduction of a conventional video signal reproducing device. Waveform diagram, Figure 7 is a screen view of the cathode ray tube surface showing bar noise, Figure 8 is a plane and front view of a double azimuth herad, Figures 9 and 10 are conventional head arrangement diagrams on a drum, Figure 11 is a diagram of the head arrangement on a conventional drum. The figure is a system diagram of a conventional digital memory. (6) is a drum, (16a) and (16b) are main heads, (17a) and (17b) are auxiliary paddles, Dx is a step, θX is a layout angle, and Lx is a length.

Claims (1)

[Scope of Claims] A video signal reproducing device in which at least one field of video signals is recorded on each inclined track on a tape, and the video signal is reproduced from the inclined tracks by a rotary head, comprising: a pair of main heads having mutually different gap azimuths and arranged symmetrically with respect to the drum center axis of the rotary head for reproducing video signals from the inclined track; and at least one of the pair of main heads. at a predetermined angular position from the center axis of the drum near the main head of the drum, and
and an auxiliary head having a predetermined gap azimuth arranged with a step from the one main head by a time corresponding to the allocation angle, and extra tape is wound around the drum by the predetermined allocation angle. A video signal reproducing apparatus characterized in that bar noise during variable speed reproduction is removed by extracting an output obtained by switching the main head and the auxiliary head within one field during variable speed reproduction.