JPS62114102A - Magnetic recording device - Google Patents

Abstract

PURPOSE:To obtain a sharp picture by setting the relative position between an erasure head and a recording head with respect to a tape taking the fringe magnetic flux of the erasure head into account so as to eliminate a part of a recording pattern on the tape from being erased. CONSTITUTION:Heads 10, A, B are arranged that a track width direction end P in the foward direction of tape running of a magnetic material having a larger saturated magnetic flux density traces the tape running backward position from the end Q in the tape running direction forward side of a recording pattern by recording heads A, B when a magnetic material opposed to the erasure head 10 via a nonmagnetic tape is of a different kind and the track width and P' of the magnetic material closed most to the tape running front side traces it when the magnetic material is of the same kind. Thus, the head 10 erases the recording by two tracks whiles being placed backward from the front end Q in the tape running direction 13 on the track recorded by the head A but gives no effect to the backward side in the tape running direction on the recorded track.

Description

[Detailed Description of the Invention] B) Field of Commercial Use The present invention relates to a magnetic recording device such as a VTR (video tape recorder), and more specifically, to smooth tape editing such as splicing and insert recording. Helical scan type "/T" equipped with a rotating erasing head for
This invention relates to magnetic recording devices such as R.

(01) Conventional technology In order to smoothly perform insert recording during splicing in helical scan type VTRs, the rotary erasing head is scanned just before the recording head scans the tape to repeat erasing and recording one screen at a time. In order to achieve a high recording density (: a rotary erase head compatible with an 8mm VTR using a high coercive force metal tape has a saturation magnetic flux density as shown in Figure 3). 5
A saturation magnetic flux density of 1 [1
, one with a sendust film of about 0OOG has been proposed (
Magnaiios MAG-20, P, 869-87
1°1984). Here, the gap length is about 3 μm, and the sendust film thickness is about 3 μm. As shown in FIG. 6, such a magnetic head includes a pair of ferrite core halves (1) (21), a sendust film (3) formed by sputtering on the opposing surfaces of one of the ferrite core halves (2), Consisting of a non-magnetic film (5) forming a gap (4), glass (6), and a coil (not shown) wound through a hole (7) and a notch (81 (9)) be done.

When such an erasing head OQ is installed together with cylinder a10: recording head IAIIBI as shown in Figure @8, conventionally A head + Al and B head (B
Install it at a 90° position in the middle of the IH. In this case, in the vertical direction of the one rotating body, as shown in FIG.

In this way, the recording head tAl (Bl) is installed at a position of 1800 in the circumferential direction of the cylinder aυ, and the RC double-rotation erasing head OI is attached at a position of 900 in the scanning direction forward of the A head (4). When the magnetic tape 13 is wound twice around the cylinder system in a spiral pattern and the tape 03 is run from diagonally upward to diagonally downward near the tape scanning direction, A, the front side of the gap between the two heads in the tape running direction ( If the relative heights of the ends of the tracks in the track width direction (lower side) to the cylinder rotating surfaces 42 are matched, recording patterns by both heads A and 1 can be alternated on the tape 03 at a track pitch determined by the tape running speed. Here, the track width direction end on the front side (lower side) in the tape running direction of the gap (4) of erase head a is aligned with the track width direction end on the front side in the tape running direction of the gap between heads A and H. Since the cylinder is placed at a height on the rear side (upper side) in the tape running direction by % track pitch from the relative height to the cylinder rotating surface (111), the principle position is as shown in Fig. 10 (A, with one head Erasing one screen at a time: erasing two tracks to be recorded → recording with A head → recording with B head.

The record should be repeated. In addition, arrow 41 in Figure 10
3 indicates the tape running direction, arrow 14 indicates the head scanning direction, and 9 (15A) indicates the track recorded by head A, (
15B) is the track recorded by head B, (15A')
indicates the track to be erased by the erase head (LI) and subsequently recorded by the A head.

(C) Problems to be Solved by the Invention However, the gap length of the erase head is about 3/1 m, which is about 10 times larger than that of the recording head, and the edges of the sendust and ferrite on both sides of the gap in the track width direction are not always aligned. Disturbance of erase magnetic flux generated from the gap near the ends in the track width direction (fringing effect) cannot be ignored, and the effective track width of the erase head is limited to the area where the magnetic materials on both sides of the gap are always facing each other. Considering the width (T) (see Figure 7), the relative position with the recording head is theoretically arranged as shown in Figure 9. Then, the tape is scanned just before the erasing head, and the recording pattern y ( 15B) is erased by the fringing magnetic flux of the erase head. This can be seen from Figure 11. In FIG. 11, the erasing head is operated immediately after the erasing head ζ: The head scans the tape. On the other hand, with the B head, which scans the tape just before the erase head, almost the same recording and replay output can be obtained regardless of whether the erase head is activated. Based on the measured data, it is shown that this phenomenon appears as a significant decrease. When the recording pattern on the tape was coated with ferromagnetic colloid and observed when the erasing head was desired to be operated, it was confirmed that a part of the recording track by the B head was erased. If this is the case, you can't hope for a clean spliced shot or an insert.

(b) Means for solving the problem When the magnetic materials facing each other across the non-magnetic gap that constitute the erasing head are different kinds of magnetic materials, the end of the track width direction on the front side of the tape when the magnetic material has a large saturation magnetic flux density (P) is
In addition, when the magnetic materials facing each other across a non-magnetic gap are of the same kind of magnetism, the edge in the track width direction of the magnetic material located furthest forward of tape travel (Pl is the recording head C which scans the tape immediately after the erasing head) A configuration in which an erasing head and a recording head are arranged so as to trace a position on the front side in the tape running direction of the recording track pattern on the tape (Q beam) in the track width direction.

(e) Operation The toothpick erase head OI shown in Fig. 3 is then moved to the human head tA.
l is located at the front end in the tape running direction tIl of the track (15A') to be recorded (positioned behind QI and erases two tracks, but at this time, the front end (p) of the erasing head OI in the tape running direction The front end of the track (15A') in the tape running direction (Q
) side is erased, but it does not substantially affect the rear end side of the previously recorded track (15B) in the tape running direction. In order to clarify the syringing effect, each dimension near the gap of the erasing head shown in FIG. 7 and 8. The relationship between T, Dl, D2, and the erase track width 9c) on the tape was investigated.

The erase track width on the tape is 1.

■ The signal is recorded with both A and B heads (signal is 4.8MH 1,750K) without operating the erasing head and running the Geergin tape normally (signal is 4.8MH 1,750K) IS.

100KHz sine wave mixing).

(2) The erasing head is operated for one rotation of the cylinder while the tape on which the signal is recorded is in still playback mode (the erasing current is a sine wave of 6.5 MH 1,300 mAp-p).

■ Apply ferromagnetic colloid to the tape and measure the width of the recorded signal disappearing.

Figure 6 (i) shows a typical example in which the above-mentioned measurements were carried out using several tens of erasing heads ζ each having slightly different dimensions as shown in Figure 6. Magnetic material (1
) (3) are facing each other (T beam, so the width on the side of the sendust film (3) of the saturation magnetic flux density (the edge of the sendust film (3) and the edge of the sendust film (3), which has a strong correlation with the town) (1 ) is within the range of at least -1 to +4 μm, the erase track width (Xi is
) is approximately 3 μm larger than the width (8).

In this way, the effective erase track width of the rotary erase head with the structure shown in FIGS. 6 and 7 is determined by the dimension in the track width direction of the magnetic material having a large saturation magnetic flux density on one side of the gap of the head, and the erase magnetic flux It was found that the effective fringing magnetic flux of the head leaks about 15 μm from the track width direction end IP+ near the gap of the magnetic material having a high saturation magnetic flux density to the outside in the track width direction, that is, about the length of the H gear. .

Therefore, in the present invention, regarding the relative positions of the rotary erasing head and the recording head with respect to the tape, by considering the fringing magnetic flux of the erasing head, the saturation magnetic flux density on one side of the gap of the erasing head having the structure as shown in Figures 6 and 7 is obtained. Track width direction end I on the front side in the tape running direction of a large magnetic material
P+ is a recording head that scans on the tape immediately after the erasing head (- traces the trick width direction end on the front side in the tape running direction of the recording pattern by P+ (trace at least the rear side in the tape running direction with respect to the track width direction from QI) Do it like this.

FIG. 1 shows such a preferred embodiment of the invention, where the step (Z) is chosen to be Z=k#) 10% of the rack pitch (the gap length of the erase head).

Figure 2 shows the difference in height. Same as IA9 diagram Z = 3
A) Although the rack pitch is selected, the circumferential position of the Vsy dummy U is (900-θ) ahead of the A head.
Point C, where the erase head CLI is provided, has two features. And θ is.

It is. In FIGS. 1 and 2, the same parts as in FIGS. 8 and 9 are designated by the same reference numerals. If the cases of FIGS. 1 and 2 are represented by a track pattern, as shown in FIG. 3, the erasing head signal will be immediately followed by the front end of the track (15A') to be recorded by the A head in the tape running direction 0 [
When erasing two tracks located behind Q) ((15A) and the track to the left of it, although not shown), at this time, an image generated near the front end IPI of the erase head fi [in the tape running direction] is erased. The front end (QI side) of the track (15A) in the tape running direction is erased by the fringing magnetic flux, but the rear end (in the tape running direction) of the track (15B) recorded by the previous (2B head) is substantially erased. There is no effect.The dimension in the track width direction of the magnetic material with a high saturation magnetic flux density on one side of the gap of the erase head should be made smaller than twice the track pitch by the amount of the fringing effect (approximately the gap length). Insert recording is even better if you take spliced shots.

Regarding the erasing head, as shown in Fig. 7, the facing widths of the ferrite material (11 and the sendust film (3) are different from each other) as well as those shown in Fig. 84 (the gap (4) part as shown in 11). The width of the sendust side and the ferrite side are equal, the width is not symmetrical on both sides as shown in Figure 4 (ml), and the width of ferrite (1) as shown in Figure 4 (0).
The present invention is also effective for those without track processing on the side. Further, in the above-mentioned erasing head, the vicinity of the gap is constructed of different types of magnetic materials such that the ferrite (1) and the sendust film (3) face each other with a non-magnetic gap (4) in between.

The present invention can be applied not only to such an erasing head but also to a magnetic head in which magnetic materials of the same type face each other, and similar effects can be obtained. still.

In that case, instead of (P) above: the end of the magnetic material near the gap in the track width direction that is closest to the front in the tape running direction (the end of the magnetic material in the tape running direction must be attached to the head scanning surface at a height Consider the above figure 1 or g! as a standard.
&2 Title: Layout similar to the example shown: All you need to do is.

(g) Effects of the Invention According to the present invention E, even when erasing and recording one screen at a time in V'l'R etc., one of the recording patterns of the tape by the recording head that scanned the tape immediately before the erasing head will not change. This prevents the parts from being erased by the fringing magnetic flux of the erase head.

The reproduction outputs of the two heads with different azimuths are made equal, and a clear image can be obtained. Therefore, the insert operation will be better in continuous shooting.

[Brief explanation of drawings]

FIG. 1 is an illustrative view of a magnetic recording device embodying the present invention, and FIG. 2 is an illustrative plan view of another embodiment. @Figure 5 is a track pattern diagram for explaining them. FIG. 4 is a diagram showing an example of an erasing head used in the present invention. FIG. 5 is an explanatory diagram of FIGS. 1 and 2. Figure 6 is a perspective view of a magnetic head actually used in an embodiment of the present invention. The seventh factor is a diagram showing a portion near the gap. 'N&8 is an illustrative plan view of a conventional device, and FIG. 9 is an illustrative view thereof. FIGS. 10 and 11 are explanatory diagrams of conventional examples thereof. (1) ...Fuequito core half (ferrite material),
+3)... Sendust film, (4)... Gap,
fi [...Erasing head. ttU...Cylinder, a3...Magnetic tape, (15
A)...Recording track pattern, (Al...A head (recording head), B...B spatula)"C note & head).

Claims (4)

[Claims] (1) In a helical scan magnetic recording device in which a rotating body is equipped with a recording head and an erasing head, the erasing head has a gap-near structure in which magnetic materials with different saturation magnetic flux densities are arranged between non-magnetic materials. The track width direction end (P) on the front side of the tape running side of the magnetic material having a high saturation magnetic flux density among the magnetic materials is a recording track pattern on the tape by a recording head that scans the tape immediately after the erasing head. A magnetic recording device characterized in that the recording head and the erasing head are arranged so as to trace a position on the rear side in the tape running direction in the track width direction than the front end (Q) in the tape running direction. (2) The recording head and the erasing head are arranged so that the P traces a position away from the Q in the track width direction on the rear side in the tape running direction by 1/2 x (the rotation and the gap length of the erasing head). A magnetic recording device according to claim 1, characterized in that: (3) The erasing head is located at a position on the rotating body that has a step difference of 1/2 track pitch rearward with respect to the recording head, and at a position advanced by an angle of (90°-θ) with respect to the recording head. The θ is θ=180°×{1/2×(erase head gap length)
}/track pitch. The magnetic recording device according to claim 1, wherein the magnetic recording device has a track pitch of: }/track pitch. (4) In a helical scan magnetic recording device in which a rotating body is equipped with a recording head and an erasing head, the erasing head has a gap-near structure in which a magnetic material having an equal saturation magnetic flux density is placed between a non-magnetic material. The end (P') in the track width direction of the magnetic material located furthest forward in tape travel among the magnetic materials forms the recording track pattern on the tape by the recording head that scans the tape immediately after the erasing head. A magnetic recording device characterized in that the recording head and the erasing head are arranged so as to trace a position on the rear side in the tape running direction in the track width direction from the front end (Q) in the tape running direction.