JPS6011869B2 - magnetic playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When recording a luminance signal (monochrome video signal) on a magnetic tape or the like, the following method can significantly increase the recording amount.

That is, as shown in FIG. 1, the rotating magnetic heads IA,
18 with corners of 180o from each other and a speed of 30
The magnetic tape 2 is rotated at a speed of approximately 1800 degrees, and the magnetic tape 2 is run obliquely along the tape inner drum 3 over an angular range of approximately 1800 degrees.

In this case, as shown in FIG. 2, the working gaps 4A and 4B of the heads IA and IB have different width directions, that is, azimuth angles, for example, 18 and 10. The brightness signal is then converted into an FM signal that occupies the high side of the recordable band, and this FM brightness signal is supplied to the heads IA and IB. Therefore, according to such a recording method, one field of the luminance signal is recorded on one magnetic track 5, as shown in FIG.
is recorded obliquely on the tape 2, and the head I
Since A and IB have different azimuth angles of 18 and 18, tracks 5A and 58 have correspondingly different azimuth angles.

Let us now consider the case where such a recording pattern is reproduced by heads IA and IB.

Then, tracks 5A and 5B are created by heads IA and IB.
The FM brightness signal is reproduced from the head I.
The azimuth angle is different between A and track 58, and the azimuth angle is different between head IB and track 5A.
Since the FM brightness signal is recorded on the high frequency side, the FM brightness signal is recorded on the high frequency side, so there is no crosstalk between tracks due to azimuth loss.
M luminance signal can be reproduced. In this way, inter-track crosstalk does not occur in the reproduced FM luminance signal, so when recording, as shown in FIG. FM so that matching tracks 5A and 5B partially overlap
Luminance signals can be recorded, and therefore the amount of recording can be significantly increased.

By the way, when performing still playback on a general two-rotary head VTR, the tape is stopped and the same magnetic track is alternately scanned by two rotary magnetic heads to obtain a still playback signal.

However, in the VTR shown in Fig. 1, when the tape 2 is stopped and the heads IA and B are scanned, the scanning locus becomes ``For example, as shown by the broken line in Fig. 3, track 5A is This becomes a trajectory 6 that almost covers the trajectory 6. When the head IA scans this trajectory 6, the azimuth angles of the head IA and the track 5A in the trajectory 6 are almost the same, so the FM luminance signal is obtained from the head IA. You can, but
When head IB scans, since the azimuth angle is different between head IB and track 5A in locus 6, the FM luminance signal cannot be obtained from head IB.
In R, even if the running of the tape 2 is stopped and the same track 5 is repeatedly scanned with heads IA and IB, still playback cannot be performed. In view of these points, the present invention attempts to enable still playback even with a VTR as shown in FIG. For this reason, in the present invention, a special rotating magnetic head is used to perform the stay reproduction. First, an example of this rotating magnetic head will be explained.

4 to 7 show an example of a special rotating magnetic head that can be used in the present invention, and this head has two operating gaps 10 and 11 indicated by thick lines, and have the same width, and
They are each inclined at an angle 28 relative to the other such that they intersect at the center 12 of their width.

And the core is the part 1 on either side of the center 12 of the gap 10.
It is divided into four parts 13 to 16 by 0A, 10B and parts 1 1A, 1 1B on both sides of the center 12 of the gap 11. Therefore, the core parts 13, 16
When considering that is one core half and the core parts 14 and 15 are the other core half, a gap 10 exists between these core halves, and the core parts 13 and 14 are one core half and the core part 15 is considered to be one core half. , 16 as the other core half, a gap 11 exists between these core halves.

Furthermore, two through holes 17 and 18 for coil winding are formed corresponding to the two gaps 10 and 11, and these through holes 17 and 1
Coils 19 and 20 are wrapped around the coil 8.

That is, as shown in FIG.
The coil 19 extends in a direction slightly oblique to the width direction including the 0 position, and the coil 19 is wound around the outer periphery of the core portions 13 and 16 through the through hole 17. The through hole 18 includes the gap 11 and extends in a direction slightly oblique to its width direction, and the coil 20 passes through the through hole turtle 8 and goes around the outer periphery of the core portions 15 and 16. It is wrapped in a bag. The positions of the through holes 17 and 18 in the depth direction of the gaps 10 and 11 are shifted from each other as shown in FIGS. 5 and 6, and the through holes are closer to the tape contact surface! A certain distance d between 8 and the through hole i7 on the rear side
is formed. Between the bonding surfaces of the core portions 13 and 14 and the bonding surfaces of the core portions 15 and 16, the portions on both sides of the tape support from the through hole 17 form a gap 10. The portion behind the through hole 17 is simply joined together with an adhesive.

Similarly, the joint surfaces of core parts 14 and 15 and core parts 13 and 1
The gap 11 is the part of the joint surface of the tape 6 that is closer to the tape contact surface than the through hole 18 . Therefore, as is clear from the figure, the depths of the gaps 10 and 11 are different from each other. Note that the portion on the side of the tape pairing bale side is cut off so as to have an appropriate track width, and a tape pairing support portion 21 is formed.

According to this magnetic head, during recording, the coil 19
When a current is passed through the core parts 13 and 16 act as one core half, and the core parts 14 and 15 act as the other core half, and leakage magnetic flux is mainly generated from the gap 10 between them. A recording is made.

Also, when applying current to the coil 201, the core portion 13,
14 acts as one core half, and core portions 15 and 16 act as the other core half, leakage magnetic flux is mainly generated from the gap 11 between them, and recording is performed by the gap 11. In this case, since there is a distance d between the through holes 17 and 18, the magnetic flux flows while blocking this portion. During reproduction, a current due to the magnetic flux picked up by the gap 101 flows through the coil 19, and a current due to the magnetic flux picked up by the gap 11 flows through the two coils. That is, when using the coil 19, this magnetic head works as a magnetic head with an azimuth angle of +0 and a gap 10 as an operating gap, and when using a coil 20, it works as a magnetic head with an azimuth angle of -0 and a gap 11 as an operating gap. Works as a head.

FIGS. 8 to 15 show an example of a method for manufacturing this magnetic head.

First, as shown in FIG. 8, one side of a magnetic plate 37 of an appropriate width and thickness is cut into a right-angled step shape, and the other side is cut into an oblique step shape, and the slope 35 is A groove 36 whose depth gradually changes within one stage is formed, and then, as shown in FIG. As shown in Figure 10, this magnetic material 3
Two pieces 7a are glued together with their slopes 35 abutting each other to obtain a rectangular parallelepiped-shaped magnetic body 37b.

Therefore, a through hole 36b having a rectangular cross section is formed in the magnetic body 37b and extends in a direction slightly inclined with respect to the surface direction including the position of the bonding surface 38. In addition, in the part of the mating surface 38 that should be the tape contact surface on one side of the through hole 36b, there is a gap baser 3 as shown by a thick line in the figure.
Interpose 9. Next, as shown in FIG. 11, this magnetic body 37b is cut and separated into two along a surface 40 shown by a broken line that intersects with the above-mentioned bonding surface 38 and forms a predetermined angle therewith. As shown in , a magnetic body 3 with a trapezoidal cross section
Get 7c. This magnetic body 37c has the above-mentioned joint surface 38.
There is a cut surface 38c, thus having a cut gap spacer 39c, and the above-mentioned through hole 36b is also cut to become a through hole 36c, which faces the slope 40c.
Next, as shown in FIG. 13, the slope 4 of this magnetic body 37c is
A groove 41 whose depth gradually changes at a position adjacent to the through hole 36c is formed in 0c, and then this magnetic body 37c is
As shown in FIG. 14, they are glued together with their slopes 40c facing each other to form a rectangular parallelepiped magnetic block as shown in FIG. 15.

In this case, a gap baser 42 is interposed in a portion of the joint surface that should be the tape-to-bale surface on one side of the groove 41, as shown by a thick line in the figure. In this way, each gap base 39c of each magnetic body 37c is connected to form one plane, which becomes one of the above-mentioned operating gaps 10, and each through hole 36c of each magnetic body 37c passes through, and this In addition to forming the above-mentioned one through hole 17, the gear base 42 on the joint surface of each magnetic body 37c becomes the above-mentioned other working gap 11, and each groove 41 of each magnetic body 37c passes through the other side. This becomes the through hole 18.

Therefore, after that, by cutting off the tape contacting sides to an appropriate width and polishing them to form the tape contacting portion 21 described above, and further winding the coils 19 and 20 as described above, the desired magnetic head can be obtained. is obtained.

In the present invention, for example, such a magnetic head is used to perform stay reproduction, and an example thereof will be explained below.

In FIG. 16, reference numeral 51 indicates a rotating magnetic head having an azimuth angle of, for example, a working gap of 10, and 52, as explained in FIGS. A rotating magnetic head is shown, and in the head 52, a coil 52A corresponds to a working gap with an azimuth angle of +0, and a coil 52B corresponds to a working gap with an azimuth angle of -0.

These heads 51 and 52 have 18 square corners, and are rotated by a motor 53 at a frame frequency.
is passed diagonally over an angular range of approximately 18 degrees, and is transported at a constant speed. Note that 55 is a guide drum. During recording, the luminance signal is transmitted to the input terminal 61.
is supplied to the FM modulation circuit 62 and converted into an FM signal, and this FM luminance signal is supplied to the coil 51A of the head 51 through the recording amplifier 63 and the recording side contact R of the recording/reproduction changeover switch 64.
The FM brightness signal from 3 is sent to the recording/playback selector switch 6.
The signal is supplied to the switch circuit 71 through the recording side contact R of No. 5.

Further, a signal at the level "1" from the signal source 72 is supplied as a control signal to the switch circuit 71 through the recording side contact R of the recording/reproduction changeover switch 73, and the switch circuit 71 is switched to the coil 528 side as shown in the figure. . Therefore, the FM luminance signal from the recording amplifier 63 is transmitted to the head 52.
coil 528. The luminance signal from the terminal 61 is supplied to a sync separation circuit 81 to extract a vertical sync pulse, and this pulse is supplied to a flip-flop circuit 82 to form a rectangular wave signal that is inverted every field period. This signal is supplied to the phase comparator circuit 84 through the recording side contact R of the recording/reproduction changeover switch 83.

Further, for example, a pulse generating means 57 is provided on the rotating shaft 54 of the heads 51, 52, from which one pulse is taken out for each rotation of the heads 51, 52, and this pulse is supplied to the comparator circuit 84 through an amplifier 85. In this way, in the comparison circuit 84, the phases of both input signals are compared, and the comparison output is supplied to the motor 53 through the amplifier 86, and the rotational phases of the heads 51 and 52 are synchronized with the luminance signal from the terminal 61. .

Therefore, the FM brightness signals supplied to the heads 51 and 52 are
As shown in FIG. 3, one field is recorded on the tape 2 so as to form one diagonal magnetic track 5 and with a vertical blanking period at the end thereof.

At this time, since the FM brightness signal is supplied to the coil 52B in the head 52, the azimuth angle of the working gap of the head 52 is -1;
Since the azimuth angle of the working gap is 18, track 5
The azimuth angles of A and 5B are 18 and 18. At this time, a rectangular wave signal from the flip-flop circuit 82 is supplied to the magnetic head 91 through the recording amplifier 88 and the recording side contact R of the recording/reproducing switch 89, and this signal is applied to the tape 2 in the longitudinal direction. recorded as magnetic tracks. On the other hand, during normal playback, the head 9
Square wave signal (differentiated) from tape 2 by 1
is regenerated, and this signal is sent to the regeneration side contact P of the switch 89.
→ Reproduction amplifier 92 → It is supplied to the comparison circuit 84 through the reproduction side contact P of the switch 83, and thereby the heads 51, 5
2 tracking servo is performed, and the heads 51 and 52 are made to scan the tracks 5A and 5B in the same relationship as during recording.

Further, a signal at the level "1" from the signal source 72 is supplied to the switch circuit 71 as a control signal through the normal reproduction side contact N of the switch circuit 74 and further through the reproduction side contact P of the switch 73. is connected to the coil 52B side as shown in the figure, as in the case of recording. Therefore, the head 51 reproduces the FM brightness signal from the track 5A, which is supplied to one input contact of the switch circuit 101 through the reproduction side contact P of the switch 64, and the head 52 reproduces the FM brightness signal from the track 58. This passes through the switch circuit 71 and further through the playback side bush point P of the switch 65 to the switch circuit 101.
is connected to the other input contact.

Then, the pulse from the amplifier 85 is supplied to the set terminal S of the flip-flop circuit 97, and the “rotary shaft 54
Another pulse generating means 58 is provided, from which a pulse with a phase delayed by 1'2 cycles than the pulse from the pulse generating means 57 is taken out for each rotation of the heads 51, 52, and this pulse is supplied to the reset terminal R of the flip-flop circuit 97 through the amplifier 96.

Therefore, from the flip-flop circuit 97, the head 51,
A rectangular wave signal that is synchronized with the rotation of 52 and inverted every one field period is extracted. And this square wave signal is
The signal is supplied to the switch circuit 101 as its control signal, and therefore, the playback signal of the head 51 and the playback signal of the head 52 are taken out from the switch circuit 101 alternately for one field period, that is, continuously as a whole. . This signal is transmitted to the reproducing amplifier 102 and the limiter 1.
03 to the FM demodulation circuit 104 where the original luminance signal is demodulated and taken out to the output terminal 105. Also, when playing stills, press the stills playback button 7.
Operate 8.

Then, the transport of the tape 60 is stopped by a stop mechanism (not shown), and the tape 2 is moved to a position where the heads 51 and 52 repeatedly scan the track 5A, as shown by the broken line trajectory 6 in FIG. Stop. Furthermore, at this time, the detection circuit 75 detects that the button 78 has been operated, and the detection signal causes the switch circuit 74 to switch to the contact S on the still playback side, contrary to the diagram. A signal at the "0" level is taken out, and this signal is supplied to the switch circuit 71 as its control signal through the reproduction side contact P of the switch 73.

Therefore, contrary to the diagram, the switch circuit 71 is connected to the coil 52A.
When the head 52 is switched to the side, the head 52 works as a head whose working gap has an azimuth angle of 18, and at this time, the heads 51 and 52 are switched to the track 5 as described above.
A is being scanned repeatedly.

Therefore, the FM brightness signal of the track 5A is alternately and repeatedly taken out from the heads 51 and 52.
→V is supplied to the demodulation circuit 104 through the limiter 103. Therefore, at the terminal 105, a luminance signal for still reproduction is obtained. Thus, according to the present invention, as shown in FIG.
, 58 have different azimuth angles, still reproduction can be performed by repeatedly scanning one of the tracks 5A.

In the above description, during still playback, the head 51
, 52 stop to scan the track 5A, but if the head 51 stops to scan either of the tracks 5A or 5B, the head 51 is configured to be the same as the head 52, and the head It is determined which track is being scanned based on the rectangular wave signal reproduced from the tape 2 by the head 91, and the heads 51, 5 are set so that the azimuth angle corresponds to that track based on the determination signal.
All you have to do is switch the azimuth angle of 2.

In addition, when performing slow playback, the running of the tape 2 is delayed, and the head 51 is configured similarly to the head 52, and the playback output level corresponding to each azimuth angle is detected, and the playback signal of the maximum output is detected. Just switch and take it out. Further, instead of the tape 2, a magnetic recording medium such as a magnetic card or a magnetic sheet may be used.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams for explaining the present invention, and Figures 4 to 3 are diagrams for explaining the present invention.
FIG. 7 is a diagram showing an example of a magnetic head that can be used in the present invention, FIGS. 8 to 15 are diagrams showing an example of its manufacturing method, and FIG.
The figure is a system diagram of an example of the present invention. 62 is an FM modulation circuit, and 104 is an FM demodulation circuit. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16

Claims (1)

[Claims] 1. A reproducing apparatus which reproduces a video signal from a magnetic recording medium in which the video signal is magnetically recorded with the azimuth angles of adjacent magnetic tracks being different from each other, which has at least two magnetic heads; One magnetic head has a first working gap with an azimuth angle corresponding to the azimuth angle of at least one of the adjacent magnetic tracks, and the second magnetic head has a first working gap with an azimuth angle corresponding to an azimuth angle of at least one of the adjacent magnetic tracks. The first magnetic head has first and second working gaps of azimuth angle corresponding to the other azimuth angle, and during normal playback, the first working gap of the first magnetic head and the second working gap of the second magnetic head
The video signal is reproduced from the magnetic track by the working gap of the magnetic track, and during still playback, the video signal is reproduced from the magnetic track by the first working gap of the first magnetic head and the first working gap of the second magnetic head. A magnetic playback device that allows video signals to be played repeatedly.