JPH0411317A - Rotary magnetic head mechanism - Google Patents

Abstract

PURPOSE:To allow the working of the edge of a notched part with high accuracy and to decrease the man-hours for the working by providing a magnetic head in the notched part formed on an outer peripheral surface for guiding a magnetic tape and forming a recessed part of a curvilinear shape over the entire circumference of the edge formed of the notched part and the outer peripheral surface of a rotary drum. CONSTITUTION:The working of the edge (window edge) 7c formed of the rectangular notched part (window part) 7b notched on the outer peripheral surface 7a of the rotary drum 7 and the outer peripheral surface 7a is executed as well in the processing of working the notched part 7b by forming the recessed part 30 of the curvilinear shape over the entire part of the edge 7c by forming the above-mentioned edge 7c to an obtuse angle viewed in section. The magnetic head 8 is disposed in the notched part 7b. The working of the edge by machining for working the notched part 7b is possible in this way without executing buffing, by which the working accuracy is improved and the man-hours for working are decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotating magnetic head mechanism used in an information recording/reproducing device such as a video tape recorder (VTR) or a digital audio tape recorder (DAT), in particular,
This relates to the shape of the notch in the magnetic head fixing part.

[Conventional technology]

Generally, in a rotating magnetic head mechanism used in an information recording/reproducing device such as a VTR, a motor rotor and a rotating drum (a rotating drum to which a magnetic head is attached) are fixed to a rotating shaft. A general mechanism in which a rotary shaft and a rotary shaft rotate integrally is known.

FIG. 17 is a longitudinal cross-sectional view showing the intra-film rotating magnetic head mechanism. In the figure, reference numeral 1 denotes a motor board, and this motor board 1 is fixed to a non-rotating fixed drum 2. A bearing 4 is interposed in the inner center hole 3 of the fixed drum 2, and the rotary shaft 5 is attached to the fixed drum 2 via the bearing 4. Furthermore, a motor 6 for rotationally driving this rotating shaft 5 is provided at the lower part of the motor board 1.

A rotating drum 7 is attached to the upper tip of the rotating shaft 5, and a pair of magnetic head supporting members 9 having a magnetic head 8 are fixed to the lower surface of the rotating drum 7 with screws 10. The magnetic head 8 is arranged in a notch 7b called a "window" formed in the outer circumferential surface 7a of the rotating drum that guides the magnetic tape 13, and rotates integrally with the rotating drum 7 via a support member 9. It has become. Further, an adjusting screw 11 for adjusting the position of the magnetic head 8 is screwed into the rotating drum 7.

A rotary transformer 12 is interposed between the fixed drum 2 and the rotating drum 7.
2 receives the information signal read from the magnetic tape 13 by the magnetic head 8 via the lead wire 14 and transmits it to the fixed drum 2 side, or transmits the signal from the fixed drum 2 to the lead wire 1.
4 to the magnetic head 8. Further, the rotary transformer 12 includes a disk-shaped rotor 16 which is adhesively fixed to the lower part of the rotating drum 7 and has concentric coils 15a and 15b interposed therebetween, and a disk-shaped rotor 16 which is adhesively fixed to the fixed drum 2 and has a coil 15a, 15b and a disc-shaped stator 18 with concentric coils 17a and 17b interposed therebetween, each facing the other.

The lead wire 14 of the rotor 16 is connected to the round portion of the magnetic head support member 9 by means such as soldering, so that signals can be exchanged between the magnetic head 8 and the rotor 16. .

In the rotating magnetic head mechanism configured as described above, the rotating shaft 5 is rotated by the rotational driving force of the motor 6. In addition, the stator 1 of the rotary transformer 12
8 is fixed to the fixed drum 2 and therefore does not rotate, but the rotor 16 rotates together with the rotating drum 7. Therefore, the information signal from the magnetic tape 13 is transferred to the rotating drum 7.
The information is transmitted to the magnetic head 8 and the magnetic head support member 9, which rotate together with the magnetic head, and is further transmitted to the rotary transformer 1 via the wire 14 from the round portion of the magnetic head support member 9.
Sent to 2.

FIG. 18 is an enlarged view of a conventional mounting notch for the magnetic head 8. As shown in the figure, a rectangular notch (magnetic head mounting window) 7b is formed on the outer circumferential surface 7a of the rotating drum 7. A magnetic head 8 is disposed within this notch 7b. The magnetic tape 13 (FIG. 17) is helically wound around the rotating drum 7, and the magnetic head 8 slightly protruding from the outer peripheral surface 7a of the rotating drum 7 comes into contact with the magnetic tape 13. At this time, the magnetic tape 13 is attached to the edge (
Since it also comes into contact with the magnetic head mounting window edge portion 7c, the magnetic tape 13 is scratched by this edge portion 7C, which damages the magnetic tape 13 and causes the head to become clogged. In order to prevent this, conventionally, the edge 7C has been polished to a smooth curved shape by puffing or the like (the shaded area in FIG. 18 indicates the polished area).

[Problem to be solved by the invention]

In order to give the notch edge 7c a smooth curved shape, the inside of the membrane is polished by puffing.

This puff processing uses a soft material such as leather or felt as the abrasive material, so there is a large variation in the shape and surface roughness of the polished surface, making it difficult to ensure the accuracy of the notch 7b, and the polishing process The problem was that the work itself required skill. In addition, since puff processing uses chromium oxide or the like as an abrasive, there were also problems in terms of preventing pollution.

Furthermore, even if the edges of the notch are machined using other methods, separate machine tools are required for machining the notch and the edge, which increases the number of machining steps. In addition to the above-mentioned problems, methods such as applying pressing force to the edges of the notch also have problems such as deterioration of accuracy in parts other than the pressed part (Japanese Patent Application Laid-Open No. 62-1626
4, Japanese Patent Publication No. 58-58737).

The present invention has been made to solve such problems, and an object of the present invention is to provide a rotating magnetic head mechanism that can process the edge of a notch with high precision and reduce the number of processing steps.

[Means to solve the problem]

A rotating magnetic head mechanism according to the present invention includes a magnetic head provided in a notch formed in an outer circumferential surface for guiding a magnetic tape, and a rotating drum that rotates integrally with the magnetic head. A curved recess is formed over the entire circumference of the edge formed by the notch and the outer peripheral surface of the rotating drum.

Further, the curved surfaces of the recessed portions may not have a common center of curvature.

Furthermore, the curved surfaces of the recessed portions may have a common center of curvature.

[Effect]

In the present invention, when forming the notch in which the magnetic head is placed on the outer peripheral surface of the rotating drum that guides the magnetic tape,
First, a notch is formed by cutting the outer circumferential surface into a predetermined shape using a machine tool or the like. Thereafter, the tool of the machine tool is replaced while the rotary drum, which is the workpiece, is fixed to the machine tool, and a curved recess is formed around the entire edge of the notch. As a result, once the rotary drum is set on the machine tool, both the notch machining and the edge machining can be performed successively, and there is no need to align the rotary drum in each machining process.

〔Example〕

Hereinafter, the first embodiment of the present invention will be described in the 11th! This will be explained based on FIGS. 1 to 6. As shown in FIG. 1, the present invention includes:
The outer peripheral surface 7a of the rotating drum 7 can be
The edge (window edge portion) 7c formed by the rectangular notch # (window) 7b and the outer peripheral surface 7a is formed at an obtuse angle when viewed in cross section, and the edge 7c extends over the entire circumference. A curved recess 3o is formed, and the edge 7c is also machined in the process of machining the notch 7b.

In this figure, the shape of the recess 3o is formed into a curved long groove. - When forming the notch 7b in the membrane, it is manufactured by milling using an end mill or the like, but in this embodiment, a ball end mill is used to process the edge 7c. That is, by moving a ball end mill having a hemispherical processing part with a relatively small diameter (small radius) at the tip as shown by arrow B, curved recesses 30 are successively formed over the entire circumference of the edge.

However, the curved surfaces of the recessed portions 30 do not have a common center of curvature.

2 to 5 show the case where the magnetic head 8 is disposed inside the notch 7b, and FIGS. 4 and 5 show the magnetic tape 1.
3 is in contact with the magnetic head 8. FIG. 6 is an enlarged view of part ■ in FIG. tape 13
can move smoothly along the edge 7c of the notch 7b, and the same effect as puffing can be obtained against tape damage. In addition, the edge 7 is machined without puffing.
Since C can be processed, processing can be performed with high processing accuracy, variations can be prevented from occurring for each workpiece (rotary drum 7), and the rotating drum 7 can be made into a stable product. Further, since the notch portion 7b can be processed and the edge portion 7C can be processed in the same process, the number of man-hours can be reduced compared to the conventional technique in which puffing has to be performed in a separate process.

Next, a jlE2 embodiment of the present invention will be described based on FIGS. 7 to 9. This embodiment is also a case in which the curved surfaces of the recessed portions 40 do not have a common center of curvature, similar to the first embodiment. In this embodiment, the edge 7C of the notch 7b is machined by a ball end mill having a relatively small diameter spherical part with a radius R of 1.0 to 2.0. That is, the shaded areas shown in FIGS. 7 and 8 are polished. The recesses 40a on both the left and right sides of FIG. 7 are machined by moving the tool in the vertical direction in the figure, and the recesses 40b on the upper side of the figure are machined as a whole by one-dimensional movement of the tool by lowering it in a direction perpendicular to the plane of the paper. It is formed into a spherical shape, and the edge portion 41 on the outer peripheral surface of the drum is shaped like an arc. As a result, each edge portion of the recessed portion 40 forms an obtuse angle θ toward the inside of the cutout portion. The size of this obtuse angle θ is preferably in the range of 100° to 170°, especially 13
It is preferably around 5 degrees, and the window width W is 3.0 to 5.
Q++m+, window height H is optimally 1.0 to 2.5 mm.

FIG. 9 is a diagram showing how the magnetic tape 13 is sucked into the notch 7b. This suction phenomenon occurs because the rotating drum 7 rotates at high speed, so the magnetic head 8 and the magnetic tape 13 are sucked into the notch 7b.
When they come into contact with each other, a particularly large negative pressure acts on the downstream side of the magnetic head due to the principle of fluid dynamics, and this negative pressure causes a phenomenon in which the magnetic tape 13 is pushed into the notch 7b as shown by the arrow. It is presumed that this is because this occurs. Even if the magnetic tape 13 is drawn into the notch 7b due to such a suction phenomenon, since the recessed portion 40 is formed at the edge 7C in the present invention, the contact occurs only after the notch 7b starts to contact the magnetic tape 40. Good tape touch until the end.

In addition, the influence of suction due to rear negative pressure in the rotational direction at the window notch 7b requires a much smaller contact angle between the magnetic tape 13 and the rotating drum 7 than in the conventional notch, and a more uniform air film effect can be obtained. As a result, damage to the magnetic tape 13 is considerably reduced, and peeling of the magnetic powder is also reduced. Therefore, adhesion of magnetic powder to the drum surface, magnetic head, and magnetic tape can be reduced. For these reasons, more stable recording and reproducing characteristics than ever before can be obtained, and the characteristics are less likely to deteriorate.

Next, a third embodiment of the present invention will be described with reference to FIGS. 10 to 14. This embodiment shows a case where the curved surfaces of the recessed portions 50 have a common center of curvature. For example, in this embodiment, the edge 7c of the notch 7b is machined by a ball end mill having a relatively large spherical part with a radius R of 2.0 to 3.5. That is, the shaded areas shown in FIGS. 11 and 12 are polished. When performing this processing, the recessed portion 50 can be simultaneously formed by moving the ball end mill one-dimensionally downward in a direction perpendicular to the paper plane of FIG. 11, and the processing can be completed in an extremely short time. In this embodiment, a spherical tool is used, so the center of curvature of the recessed portion 50 is one center point, but if the tool is, for example, a spheroidal shape, the center of curvature becomes the center line. This embodiment is preferably used when the machining accuracy of the recessed portion 50 may be slightly rougher than in the first and second embodiments. In this case, the dimensions of the window width W and height H are preferably the same as in the second embodiment.

Measure 15 Figure (a) shows data obtained by optometric measurement, which measured the general state of tape deformation when the drum head (notch) of the rotating drum is in contact with the magnetic tape 13, and the arrow C in the figure indicates The moving direction of the rotating drum 7 is shown. FIG. 15(b) is an explanatory diagram showing the measurement direction of FIG. 15(a), in which the magnetic tape 13 is sucked into the notch 7b and deformed.

FIGS. 16(a) and 16(b) are diagrams showing experimental data by optometric measurement when the edge of the notch was processed by the conventional method and the present invention, respectively, where the vertical axis represents pressure and the horizontal axis represents magnetic tape. The position (angle) of each is shown. Conventionally, as shown in FIG. 16(a), the magnetic tape is strongly sucked by the notch (E in the figure), and the head negative pressure influence angle α due to this phenomenon is large (the angle α is 63mm).
6°). On the other hand, in the present invention in which the window edge part is subjected to ball end milling, as shown in FIG. 16(b), the suction phenomenon is weak (F in the figure), and the head negative pressure Angle α is small (angle α is 35.8°)
. Note that G in the figure indicates the apex of the head.

Incidentally, in the first to third embodiments described above, the shape of the notch is rectangular, but the shape of the notch may be any shape such as circular, elliptical, polygonal, etc.

In addition, the curved surface of the recess is not limited to a spherical surface,
It may be an ellipse of revolution, a paraboloid of revolution, or any other shape.

Note that the same reference numerals in each figure indicate the same or corresponding parts.

〔Effect of the invention〕

The rotating magnetic head mechanism of claim IM has a curved depression formed around the entire circumference of the edge of the notch, so that the edge is not puffed and is processed using a machine tool for machining the notch. can be processed, improving processing accuracy and reducing the number of processing steps.

In addition to the above-mentioned effects, the rotating magnetic head mechanism according to the second aspect of the present invention allows processing to be performed by moving the tool along the edge, so that processing accuracy can be further improved.

In addition to the effects of claim 1, the rotating magnetic head mechanism according to claim 3 can process the edge in one step by simply lowering the tool from above the notch, thereby significantly reducing machining time and effort. .

[Brief explanation of drawings]

1 to 6 are diagrams showing a first embodiment of the rotating magnetic head mechanism according to the present invention, FIG. 1 is an enlarged perspective view of a notch in which the magnetic head is attached, and FIG. 2 is a notch of the rotating head. Fig. 3 is a front view of the notch, Fig. 4 is a plan view of I in Fig. 2.
5 is a sectional view taken along the line ■-v in FIG. 2, FIG. 6 is an enlarged view of the section ■ in FIG. 5, and FIGS. 7 and 8 are respectively a plan view and a front view of the notch, and FIG. 9 is a diagram showing the IX in FIG. 7.
-IX sectional views, FIGS. 10 to 14 are the third embodiment of the present invention.
10 is an enlarged perspective view of the notch, FIGS. 11 and 12 are a plan view and a front view of the notch, respectively.
Fig. 13 is a sectional view taken along the line Xl-Xl in Figure 1, Fig. 14 is a sectional view taken along the line Xff-XIV in Fig. 11, and Fig.
Figure (a) is a data diagram of optometric measurement, Figure (b)
) is an explanatory diagram showing the measurement direction of the measurement, FIG. 16(a,
) and (b) are diagrams showing optometric measurement data according to the conventional method and the present invention, respectively. FIG. 17 is a longitudinal cross-sectional view showing the overall structure of the rotary magnetic head mechanism according to the conventional method and the present invention, and FIG. 18 is a diagram showing the conventional optical measurement data. FIG. 3 is an enlarged plan view of the magnetic head mounting section. 7... Rotating drum, 7a... Outer peripheral surface, 7b... Notch, 7c... Edge, 8... Magnetic head, 13... Magnetic tape, 30.40.50... depression. I-rv Figure Figure Figure 6 Figure 12 Figure 13 Figure 14 Figure 17 Figure 18

Claims (1)

[Scope of Claims] 1. In a rotating magnetic head mechanism having a magnetic head provided in a notch formed in an outer circumferential surface for guiding a magnetic tape and a rotating drum that rotates integrally with the magnetic head, the notch A rotating magnetic head mechanism characterized in that a curved recess is formed over the entire circumference of the edge formed by the outer peripheral surface of the rotating drum. 2. The rotating magnetic head mechanism according to claim 1, wherein the curved surfaces of the recessed portions do not have a common center of curvature. 3. The rotary magnetic head mechanism according to claim 1, wherein the curved surfaces of the recessed portions have a common center of curvature.