JPS59210519A - Composite magnetic head - Google Patents

Abstract

PURPOSE:To obtain an approximately even contact of tape between the tape input and output heads without adjusting inclination, by forming the tape rubbing surface into an arc shape with its center shifted toward the tape output side head. CONSTITUTION:An arc shape is obtained for tape rubbing surfaces 1b and 2b respectively centering on a point 11 which has about 90mum eccentricity toward a tape output side head 2 from the center line 3 of a magnetic head. As a result, an optimum tape contact is secured without giving any adjustment of inclination when the magnetic head is attached to a rotary head drum. Thus it is possible to obtain the stable head output even with a comparatively low level of tape tension.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a composite magnetic nod for a VTR using two Herad chips.

〔background〕

The following will explain the conventional composite magnetic head using all the drawings.

FIG. 1 is a side view showing an example of a conventional composite magnetic field, and FIG. 2 is a sectional view taken along the line A--A in FIG. 1.

Referring to these figures, 1 is the lead to the tape entry side, 1a is the end face, 1b is the tape sliding face, and 2 is the lead to the tape exit side.
lid, 2a is its end surface, 2b is its tape sliding surface, 4,
5 is a gear lug, and 6 is a single head mounting plate to which the lead 1.2 is fixed.

In the conventional composite magnetic head, as shown in Fig. 1.2, the center of the arc shape of the tape sliding surfaces 1b and 2b is located between two
It was located on the center line 6 of the intermediate gap of the throat 1.2. In such a composite magnetic head, as shown in FIG. 6, when the magnetic head is mounted so that the radius of the outer circumferential arc of the rotating rad tram 10 overlaps with the center line 3, the actual tooth contact surface is , as shown by reference numeral 7.8 (see FIG. 1).

That is, the tape contact length a+ between the tape entry side lead 1 and the tape ti3 side head 2 with respect to the cylinder rotation direction DK.
b is shorter than a because the tape output head 2 is located downstream of the tape in the cylinder rotation direction DK. For this reason, the ratio b/a is so small that it cannot satisfy the range of allowable values, and as a result, there is a problem in that good head output cannot be obtained. Moreover, such a phenomenon becomes more noticeable as the tape tension becomes lower.

Therefore, in the past, Xiaomi developed a system that solved these problems and enabled the composite magnetic head attached to the rotary head drum 10 to obtain good head output even under low tape tension, that is, to achieve optimal tape contact. The entire magnetic head is tilted in the same direction as the cylindrical rotation direction of the magnetic tape 9 (towards the tape input side) so that In addition",
Here, optimal tape contact refers to a state in which the magnetic tape 9 is evenly in contact with the gap 4.5 between the two heads 1 and 2.

In other words, in the conventional composite magnetic head, the head is rotated in the direction of rotation of the rotating heel drum 10 using a predetermined head set screw (not shown) that serves as the rotational axis of the head. As a fulcrum, it was necessary to adjust the tilt angle to a predetermined angle.

However, since such adjustment requires high precision, the work is time-consuming, and this has been a major drawback in soils where workability is being sought.

〔the purpose〕

An object of the present invention is to eliminate the drawbacks of the prior art as described above, and to achieve an optimal point-to-point contact without adjusting the inclination when a magnetic head is attached to a rotating head drum. To provide a composite magnetic head capable of obtaining stable head output even under low conditions.

〔overview〕

The feature of the present invention is that the tape sliding surface of the composite magnetic head has an arcuate shape whose center is moved toward the output side head from the conventional arcuate shape whose center is on the center line of the gap between the two heads. The point is that the optimal tape contact is not obtained by rotating the helical lid as in the past, but is made as a shape, and the above-mentioned optimal tape contact is fully realized.

〔Example〕

The composite magnetic head of the present invention will be described below with reference to the drawings.

FIG. 4 is a side view showing an embodiment of the composite magnetic lead of the present invention, and FIG. 5 is a sectional view taken along the line B--B in FIG. 4. In these figures, the same reference numerals as in FIGS. 1 to 3 indicate the same parts and all equivalent parts.

As is clear from FIG. 5, the magnetic head of this embodiment has the following features:
The arcuate shapes of the tape sliding surfaces 1b, 2b of the heads 1, 2 are not symmetrical with respect to the center line 3. This is because the magnetic lead of the present invention differs from the conventional magnetic heli 5- in that the center 1 of the arc shape of the tape sliding surface 1b + 2b is
1. This is because the tape was moved from above the center line 3 to the tape exit side and to the Rad 2 direction.

Here, the tape sliding surface 'b+ of the composite magnetic head of the present invention is
A method for determining the arc shape of 2b will be explained.

According to the experimental results of the present inventors, the cheese contact length ratio ( b/a) and
Exit head output I for the maximum value (Emax) of the head output of Qi-Two exit head 2 (output 140 head output)
The characteristic curve representing the relationship with the ratio %j of EI is as shown by the symbol X in FIG.

According to the experimental results of the present inventors, the tape contact length ratio (b/a) - peak side head protrusion (% characteristic curve) at 12gr, where the tape tension was further lowered, is as shown by the symbol Y in the figure. The following explanation will be based on the characteristic curve X.

Normally, a reduction of about 5% is allowed as the output head output. Therefore, as is clear from Figure 6,
The tape contact length ratio at the exit side helide output of 95% or more (
b7a) falls within the range of 110.7 to 1/1.2.

By the way, in order to keep this tape contact length ratio b/a' (H) within the range of 110.7 to 171.2 using a conventional magnetic head (head of a commonly used size), - Obtained by rotating the other end face using the end face of the tape (more precisely, the intersection of the tape sliding surface and the end face) as a fulcrum.

That is, 1, for example, can be obtained by rotating the end surface 2a at the same time using the intersection of the tape sliding surface 1b and the end surface 1a as a fulcrum.

Now, to express this inclination, the above-mentioned tape sliding surface 1b
As the point where the end face 2af and the end face 1a intersect, if the end face 2af is rotated counterclockwise, it will be 'z +-1, and if it is rotated clockwise, it will be 'z' (ll-(-+-1), When the machining accuracy of the sliding surface 1 b + 2 b is extremely important, according to experiments by the inventors, the difference H between the ends 'ilt [1a and 2a] needs to be -20 to -50 μm. there were.

Therefore, in such a magnetic head, compared to conventional magnetism,
rad is 1 while the difference H was O, and the difference H'i
In order to obtain a magnetic field of -20 to -50 μm, it must be determined which position should be placed at the center 11 of the arc shape of the tape sliding surfaces 1b and 2b. Must be. This will be explained below using the sound of the seventh figure.

This FIG. 7 is a simplified representation of FIG. 5, and the same reference numerals as in FIG. 5 indicate the same parts.

It is assumed that the radius R1 of the arc shape of the tape sliding surfaces 1t) and 2t+ and the intermediate Ils angle θ0 between the tape sliding surfaces 1b and 2b are determined. Also, the angle θ4. θ2 is defined by a line passing through the center 11 and intersecting the center line 3, and the outer ends 1fi', 2 of the tape sliding surfaces 1b and 2b, respectively.
This is the angle formed by the line connecting b' and the center 11.

As is clear from FIG. 7, the following formula produces mature beans.

H=ノR2-a,'-J R2b+'θ,+00+0
2-π Rcosθ1:al Rcosθ2:bl Therefore, from the above four equations, al and b+ can be determined. That is, here, H'1-20 to -50μ
m, enter specific values in R and 00, a+ and bl
can be found using specific values.

If al and bl are determined in this way, the position of the center 11 for forming the arc shape of the tape sliding surfaces 1b and 2b of the magnetic helad in this embodiment can be visually identified. .

In the magnetic head of this embodiment shown in FIG.

In other words, the magnetism of this example shown in FIG.
The arc shape of the tape sliding surfaces 1b and 2b? To obtain the cheese exit head from the center line 3 of the magnetic head 200,000 to
It is sufficient to form the shape with the center 11 at a point eccentric by about 0 μm.

The above description has been made for the case where the processing accuracy of the tape sliding surfaces 1b and 2b is extremely high, as described above.

That is, the tape contact length formula ratio (b/a) 2110.
In order to keep it within the range of 7 to 171.2, the difference Hf-20
This was the case when the thickness was set to -50 μm. If this is illustrated graphically, the range in which optimal tape contact can be achieved at a tension of 15gr is within the shaded range shown in FIG.

However, on the tape sliding surface ' b + 2 b,
There are variations in the processing accuracy. That is, the arc shape of the tape sliding surface 'b+2b is not a complete arc of a predetermined radius a, but the radius R changes from large to small depending on the area. Curves P and Q in FIG. 8 are all experimentally determined and shown; curve P shows the case where the radius R is the minimum, and curve Q shows the case where the radius R is the maximum.

Therefore, the tape contact length ratio (b/a) is 1
The difference H between the end faces 1a and 2a, which falls within the range of 107 to 1/1.2, is not necessarily within the range of -20 to -50 μm in practice. In other words, in Figure 88, it is approximately -20 ~
It falls within the range of -35 μm.

〔effect〕

As is clear from the above explanation, according to the present invention, since the tape sliding surface is formed by an arcuate shape whose center is shifted toward the tape exit head, it is possible to prevent rotation and rad drum movement as in the conventional case. When installing the magnetic head assembly, there is an effect that the tape contact sound on the input side and output side of the tape can be made almost even without adjusting the inclination.

Therefore, according to the present invention, not only can the working time be shortened, that is, work efficiency can be improved, but also the full head output can be obtained stably even in a state where the tape tension is relatively low.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of a conventional composite magnetic head, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a plan view showing an example of the state of contact between the magnetic head and magnetic tape. , FIG. 4 is a side view showing one embodiment of the composite magnetic head of the present invention, and FIG.
The figure is a cross-sectional view taken along the line B-B of Figure 4, Figure 6 is a characteristic diagram showing the relationship between tape contact length ratio (b/a') and outlet output (6), and Figure 7 is Figure 5. Fig. 8 is an explanatory diagram to explain how the center of the arc shape of the tape sliding surface changes.
FIG. 3 is a characteristic diagram showing the relationship between H1 and tape contact length ratio (b/a). DESCRIPTION OF SYMBOLS 1...Tape entry side head, 1b, 2b...Tape sliding surface, 2...Tape Itl side head, 6...Center line, 6...Head mounting plate. Representative Patent Attorney Akira Takahashi Figure 1 Figure 4 Figure 8 Off view

Claims (1)

[Claims] (1) A pair of heads consisting of a tapered extension head and a tape ejection head are arranged on the head/lid mounting plate with a predetermined gap so as to form the centerline sound. In the above, the sliding surface of the chi 1 of the pair of heads is
A point that is eccentric from the center line in the direction of the tape exit helide by the planned length? Composite magnetic throat characterized by being formed in a circular arc shape at the center.