JP2685605B2 - Rotating magnetic head device - Google Patents

Description

The present invention relates to the arrangement and shape of a rotary magnetic head of a helical scan VTR in which a recording head and a reproducing head are separate heads.

[Conventional technology]

The arrangement of a rotary magnetic head (hereinafter simply referred to as a head) of a VTR capable of recording high-fidelity FM voice in a conventional home VTR is as shown in FIG. In the figure, 2 is a rotary magnetic head device (hereinafter referred to as a cylinder), heads 17, 18 and 19, 20 are recording / reproducing (R / P) double azimuth heads, and heads 17 and 19 are for EP. , Heads 18 and 20 are for SP. The heads 11 and 12 are hi-fi voice recording / reproducing heads (hereinafter referred to as hi-fi heads), and the head 13 is a flying erase head. Each head is rotating at a constant speed in the direction of the arrow. Although not shown in the figure, they are arranged with a predetermined step in the rotation axis direction. In such a VTR, there may be a demand for arranging a read-only head for the purpose of monitoring a recording signal.

[Problems to be solved by the invention]

In such a case, the number of heads increases and the head arrangement becomes complicated. In such a case, the influence of the other head on the reproducing head, especially jitter caused by tape vibration at the moment when the other head starts contact with the tape during recording / reproducing or when the head leaves the tape (referred to as impact jitter) It is necessary to give full consideration to

The present invention relates to an impact jitter reduction means when a recording head and a reproducing head are different.

[Means for solving the problem]

The present invention is a rotary magnetic head device including a plurality of magnetic heads, wherein a magnetic tape is wound around an outer peripheral surface thereof at an angle of 90 degrees or more, and the plurality of magnetic heads are
The recording head for recording a predetermined signal on a magnetic tape; and a reproducing head for reproducing the predetermined signal from the magnetic tape, the head being different from the recording head, and the plurality of magnetic heads, Both the first head structure in which one head is arranged independently and the second head structure in which two heads are arranged in close proximity to each other are mixed, and the first and The second head configuration, when each is regarded as the same one head configuration, has a configuration in which, in the circumferential direction, each forms an angle of 90 degrees or less, and is arranged at substantially equal angular intervals,
The impact jitter is reduced by canceling the impact jitter generated during recording and the impact jitter generated during reproduction. The concept of the present invention will be described below with reference to FIG.

FIG. 3 shows a possible example of head arrangement. The figure shows VH
This is an arrangement example in the case of performing azimuth recording as in the S VTR and having both SP and EP recording modes. The magnetic tape 1 is guided around the guides 15 and 16 and tightly wound around the cylinder 2 by 180 °. It is assumed that each head is rotating in the direction of the arrow.
The difference between the arrangement of Fig. 3 and Fig. 2 is that the read-only double azimuth heads 3, 4 and 5, 6 are newly added, and the record-only double azimuth heads 7, 8 and 9, 10 are R / P head 1
It is arranged in place of 7,18,19,20. There are also two flying erase heads. Therefore, double azimuth reproducing heads 3, 4 and 5, 6 are arranged at the position of the flying erase head shown in Fig. 2 and its symmetrical position, and the flying erase head is placed between the recording dedicated double azimuth head and the hi-fi head. It is arranged. In the example of FIG. 3, the heads are not arranged at equal intervals in the circumferential direction, and impact jitter becomes a problem. This will be described below.

The time point shown in FIG. 3 indicates the time point when the flying erase head separates from the tape or plunges into the tape. At this point, the recording-only double azimuth heads 9 and 10 scan the tape by 30 °, and the playback-only double azimuth heads 5 and 6 scan the tape by 90 °. In other words, when recording, double azimuth head for recording 9,
When 10 scans 30 °, impact jitter is generated by the flying erase head, and this is recorded on the tape. The same applies to the recording-only double azimuth heads 7 and 8. When playing, double azimuth head for playback 5,6
When the tape scans 90 ° on the tape, jitter occurs due to the flying erase head, and the reproduced signal is subject to time axis fluctuations. The same applies to the reproduction-only double azimuth heads 3 and 4. FIG. 4 shows the head positions when the read-only double azimuth heads 5 and 6 scan the tape at 30 ° and when the record-only double azimuth heads 9 and 10 scan the tape at 90 °. As is apparent from FIG. 4, there is no head that starts contacting or leaving the tape at these points. In other words, the impact jitter that was recorded at the time of scanning the tape by 30 ° also cancels the impact jitter that was recorded at the time of playback, and the impact jitter that was recorded in the recording signal in advance so as to cancel the impact jitter that occurred at the time of scanning at 90 ° during playback. Nor.
In other words, neither the recording jitter nor the reproduction jitter appears in the reproduced signal without being canceled.

[Action]

According to the present invention, as shown in FIGS. 8 to 9, both a first head structure in which one head is arranged alone and a second head structure in which two heads are arranged in close proximity to each other are provided. In the rotary head device configured so as to coexist with each other, the first and second head configurations make an angle of 90 degrees or less with each other in the circumferential direction when they are regarded as the same one head configuration. In addition, the impact jitter generated during recording and the impact jitter generated during reproduction are canceled by adopting a configuration in which they are arranged at substantially equal angular intervals.

〔Example〕

A reference example of the present invention will be described with reference to FIGS. 1 and 5. FIG. 1 shows the head arrangement of the present invention. Figures 1 and 3
The difference between the figures is that the flying erase heads 13 and 14 are arranged close to the hi-fi heads 11 and 12. As will be described later, it is desirable that the heads 12, 13 and the heads 11, 14 have the same shape as the other double azimuth heads 3, 4, 5, 6, 7, 8, 9, 10. In the reference example of FIG. 1, the influence of impact jitter due to the flying erase head described with reference to FIG. 3 is examined. FIG. 5A shows the head position at the time when impact jitter occurs due to the flying erase head. Playback-only double azimuth heads 5, 6 tape 1
Double azimuth head for recording 9,10 when scanned by 20 °
Is the time point when the tape was scanned at 60 °. At this point, impact jitter is recorded, or the reproduced signal causes time-axis fluctuation. FIG. 5B shows the head position at the time when the reproduction-only double azimuth heads 5 and 6 are reproducing the signal recorded at the time shown in FIG. In this case, impact jitter due to the flying erase head does not occur, but instead, impact jitter occurs due to the recording-only double azimuth heads 7 and 8. Therefore, the shapes and protrusion amounts of the recording-only double azimuth heads 7 and 8 are almost the same as the shapes and protrusion amounts of the flying erase head 13 and the hi-fi head 12 which are arranged closely, and the distance between these heads (60 °) is accurate. If so, the jitter during recording and the jitter during reproduction are canceled. This cancellation need only be within an error range to some extent even if the shape, the protrusion amount, and the head interval are not exactly the same. FIG. 5 (c) shows the head position when the recording-only double azimuth heads 7 and 8 are at the time of 120 ° scanning of the tape to which the reproduction-only double azimuth heads 5 and 6 receive the impact jitter. At this point, impact jitter is generated by the read-only double azimuth heads 3 and 4, and this is recorded on the tape by the write-only double azimuth heads 7 and 8. Therefore, if the shapes and protrusions of the read-only double azimuth heads 3 and 4 are almost the same as those of the flying erase head 13 and the hi-fi head 12, and the intervals between the heads are exactly the same, the impact jitter of the read-only heads 3 and 4 during recording will be great. Is canceled by impact jitter from the flying erase head 13 and the hi-fi head 12 during reproduction. In summary, four double azimuth heads 3, 4, 5, 6, 7, 8, 9, 10 and head pairs in close proximity, 13, 1
If the shapes and protrusions of 2 and 11, 14 are almost equal, and these heads are arranged at equal intervals, all impact jitter generated by the flying erase head (or head for hi-fi) during recording and reproduction will be canceled. .
As is clear from the above description, the impact jitter due to other heads is also canceled if the above conditions are satisfied.

Flying erase head 13 arranged close to FIG.
(Or 14) and a state in which the hi-fi head 12 (or 11) is attached to the cylinder 2. The figure shows a flying erase head 13, a hi-fi head 12 and a head base 22.
Is attached to the rotary cylinder 21 constituting the cylinder 2, and FIG. 6 (a) shows the rotary cylinder.
21 is a view seen from below, and FIG. 6 (b) is a view looking at the head portion from the radial direction. As shown in the figure, these heads are arranged and have the same shape as a normal double azimuth head for recording and reproducing video signals. The difference is that these heads are not double azimuths, and usually there is a step between these heads in the direction of the rotation axis (the direction perpendicular to the paper surface in FIG. 6A).

As shown in the figure, the flying erase head 13 and the hi-fi head 12 are adhered to the tip of a head base 22, and the head base 22 is fixed to the rotary cylinder 21 with screws 23. Moreover, these heads are provided with windows 24 provided on the rotary cylinder.
Located within. These heads are attached to the head base 22 and are lapped by a lapping machine, and as shown in FIG. 6A, the tips of the two heads each form an arc-shaped portion. In other words, they are integrated into one arc shape. These relationships are the same as those of the double azimuth head for recording / reproducing video signals.

FIG. 6 (b) is a view seen from the radial direction. As shown in the figure, the hi-fi head 12 is a head having an azimuth angle, and the flying erase head 13 is a head having an azimuth angle O. , And the height of the track center is also different. The example shown in the figure is an example in which a step is formed by changing the thickness of the head. As shown in the figure, if the difference in height between the track width center of the hi-fi head 12 and the track width center of the flying erase head 13 is required to be d, as shown in the figure, the difference in thickness between these heads is 2d. If the center of the head track width of each head is aligned with the center of the head thickness, the distance between the centers of these head track widths is d. Especially VHS VT
In R, the flying erase head is located higher than the other heads, so the above method of changing the head thickness is suitable. Fine adjustment of the height can be performed by providing a height adjusting screw on each head and deforming the head base, as in the case of a normal double azimuth head.

Further, as shown in FIG. 7, the hi-fi head 12 and the flying erase head 13 are arranged close to each other, but the head bases may be separate. That is, the hi-fi head 12 is bonded to the head base 25 and attached to the rotary cylinder 21 with the set screw 27. The flying erase 13 is glued to the head base 26 and the screws 28
It is attached to the rotary cylinder 21 by. In such a case, it is extremely easy to provide a step between these heads, and a spacer having an appropriate thickness may be inserted between either head base and the rotary cylinder 21.

As shown in FIGS. 6 and 7, the hi-fi head 12
The flying erase head 13 can be combined with other double azimuth heads 3, 4, 5, 6, 7, 8, 9 and 10 for video recording / reproducing to have almost the same shape.

The example in which there are two types of recording time modes, SP and EP, and the recording-only head and the reproduction-only head are double azimuth heads, has been described above. Depending on the type, even if these recording-only double azimuth heads 7, 8, 9, 10 and read-only double azimuth heads 3, 4, 5, 6 are single heads, the head tip shape is the same as the double azimuth head. The same effect of canceling impact jitter can be obtained.

Further, it is obvious that the present invention cannot be applied even when the recording-only double azimuth heads 7, 8, 9 and 10 are not recording-only but recording / reproducing heads.

An embodiment of the present invention will be described based on FIG. In this embodiment, the hi-fi heads 11 or 12 and the flying erase heads 14 or 13 are not arranged close to each other, but the reproduction-only double azimuth heads 3, 4, 5, 6 and recording-only heads 7, 8, 9, 10 and hi-fi are used. Heads 11, 12, flying erase heads 13,
As shown in the figure, 14 are arranged at equal intervals of 45 °. As described above, the single heads 11, 12, 13, 14 can also have the tip shape (curvature and protrusion amount in the scanning direction) substantially the same as those of the double azimuth heads 3, 4, 5, 6, 7, 8, 9, 10. As is apparent from the above description, even in the arrangement shown in FIG. 8, the impact jitter during recording and the impact error during reproduction can be canceled each other.

In FIG. 8, a reproduction-only double azimuth head
3,4 (or 5,6) and double azimuth head for recording 7,8
The reason why the interval of (or 9,10) is 90 ° is that the wider the interval is, the larger the effect of canceling the jitter other than the impact jitter accompanying the recording / reproducing separation is. This is for the reason described below. Of the jitter that accompanies recording / playback separation, what is particularly noticeable on the playback screen is the frequency component around 1 kHz, and in the VHS VTR, this is the waviness of vertical lines and horizontal color stripes. Jitter generated by recording / reproduction is caused by the difference in cylinder rotation phase between when a signal is recorded and when it is reproduced. This difference in rotational phase is the angular difference between the recording head and the reproducing head and is 90 ° in the arrangement of FIG. If this angle difference can be made very small, the smaller the angle difference, the better. The smaller it is, the closer to self-recording state. However, another phenomenon occurs when the size cannot be reduced for various reasons (for example, the size of the head base). In this case, the dominant phenomenon is that the jitter of a specific frequency determined by the head angle difference is canceled during recording and during reproduction. This is a phenomenon in which a jitter frequency component having the same phase at the recording head position and the reproducing head position is canceled. If the distance between the recording head and the reproducing head is 45 °, the canceled frequency component is a jitter component that changes 8 cycles per rotation and its multiple.
If the cylinder rotates at 30Hz, the cancelled component will be 240 × nHz (n; natural number). Head spacing is 90
If we say °, this will be 120 × nHz. That is, the larger the head interval, the shorter the interval of the jitter frequency components to be canceled, and more frequency components are canceled during reproduction.

As shown in FIGS. 6 and 7, the effect of canceling the impact jitter is very large when the adjacent head tips form a part of one substantially arcuate shape and the curvature is almost equal to that of the other heads. However, even if the tip shapes of these heads are independent arc shapes, they have a canceling effect unless they are regarded as being close to each other and not regarded as two consecutive impacts.

FIG. 9 shows another embodiment of the present invention. This embodiment is the third
The recording heads 7, 8 or 9, 10 and the reproducing heads 3, 4 or 5, 6 in the example shown in the middle and the head for hi-fi.
Dummy heads 30, 31, 32, 33 having tip shapes and protrusions that are almost the same as those of the other heads are arranged exactly in the middle of 11 or 12 and the read-only heads 3, 4 or 5, 6, respectively, and the dummy heads 30, 31, 32, 33 are arranged as a whole. The heads are arranged at regular intervals in the circumferential direction at intervals of 30 °. By using the dummy head in this way, you can expand the selection range of each head interval,
Furthermore, it is possible to cancel all impact jitters during recording and reproduction. Dummy heads 30, 31, 3
Since 2,33 does not require precise posture adjustment, it is possible to directly bond the head chip directly to the rotary cylinder 21, for example, and the cost increase by adding a dummy head can be extremely small.

〔The invention's effect〕

According to the present invention, in the rotary head device in which both the first head structure in which one head is arranged alone and the second head structure in which two heads are arranged in close proximity to each other are mixed, When the first and second head configurations are regarded as the same one head configuration, the respective configurations make an angle of 90 degrees or more with each other in the circumferential direction and are arranged at substantially equal angular intervals. As a result, it is possible to obtain a high-quality image with little image jitter when reproducing with a head different from the recording head.

[Brief description of the drawings]

FIG. 1 is a diagram showing a head arrangement in a cylinder of a reference example of the present invention, FIG. 2 is a diagram showing a head arrangement in a cylinder of a conventional VTR, and FIG. 3 is an example of possible head arrangement. FIGS. 4 and 5 are views showing head positions at different cylinder rotation phases in the head arrangement of FIG. 3, and FIG. 5 is a view showing head positions at different cylinder rotation phases in the arrangement of FIG. , FIG. 6 is a view showing a hi-fi head and a flying erase head arranged close to each other, FIG.
FIG. 8 is a view showing another reference example of FIG. 6, FIG. 8 is a view showing a head arrangement of an embodiment of the present invention, and FIG. 9 is a view showing another embodiment of the present invention. 1 ... Magnetic tape 2 ... Cylinder 3, 5 ...... EP playback-only head 4, 6 ...... SP playback-only head 7, 9 …… EP recording-only head 8, 10 …… SP recording-only head 11 , 12 …… Hi-fi head 13,14 …… Flying erase head 22 …… Head base

Claims (2)

(57) [Claims] 1. A rotary magnetic head device comprising a plurality of magnetic heads, wherein a magnetic tape is wound around an outer peripheral surface of the magnetic tape at an angle of 90 degrees or more, and the plurality of magnetic heads are arranged on the magnetic tape in a predetermined manner. And a reproducing head which is different from the recording head and reproduces the predetermined signal from a magnetic tape, and one of the plurality of magnetic heads is a head. The first and second heads are configured so that both the first head configuration, which is disposed independently, and the second head configuration, in which two heads are disposed in close proximity to each other, are mixed. The configuration is the same for each one
When regarded as one head configuration, a rotary magnetic head device characterized in that they are arranged at an angle of 90 degrees or less with each other in the circumferential direction and are arranged at substantially equal angular intervals. 2. The rotary magnetic head device according to claim 1, wherein each of the plurality of magnetic heads includes a dummy head that is not used for recording, reproducing or erasing a signal.