JPS634408A - Rotary head assembly for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To easily keep the flatness of a head mount face and the roundness and cylindricity of the peripheral of a cylinder with prescribed accuracy by providing the head mount face at the midpoint of the cylinder in the axial direction. CONSTITUTION:The head mount face 401A is provided just at the center in the axial direction of a cylinder 402. A projection 404 formed integratedly with the head mount face 401A to mount the magnetic head is provided to place the head mount face 401A at the axial center of the cylinder. Since the contraction by cooling after the forming is equal to both sides with respect to the mount face 401A in the axial direction, the flatness of the head mount face 401A is easily selected within a prescribed accuracy, the difference alpha between the minimum radius at the center 405 and the maximum radius at both ends 406, 407 is decreased, and the roundness and the cylindricity of the peripheral face of the cylinder 402 are easily kept within a prescribed accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an improvement in a rotating cylinder of a rotating head assembly of a magnetic recording/reproducing device such as a video tape recorder (VTR).

[Conventional technology]

FIG. 4 is a vertical cross-sectional view showing a conventional rotary head assembly for a video tape recorder. In the figure, (1) shows a tape-shaped recording medium (magnetic tape), and (2) shows the tape-shaped recording medium (1) for guiding (3) is a magnetic head for recording and reproducing information on the tape-shaped recording medium (1); (4) is molded from a suitable molding material such as plastic or aluminum; , a rotating cylinder having a head mounting surface (401) and a cylindrical portion (402) provided on the outer circumference of the head mounting surface (401), the head mounting surface (401) having a magnetic head (
3) Attachment is carried out by running the tape-shaped recording medium (1) along the outer peripheral surface of the cylindrical portion (402).

(5) is a rotating shaft, and (6) is a flange fixed to the rotating shaft (5), which directly connects the rotating cylinder (4) and the rotating shaft (5). (7) is a bearing, and the rotating cylinder (4
) is rotatably supported from a fixed cylinder (2) via a bearing (7), a rotating shaft (5) and a flange (6).

Thus, when the rotating shaft (5) is rotated by the electric motor, the magnetic head (3) also rotates around the rotating shaft (5),
A tape-shaped recording medium (1) that runs while being guided by a lead groove (201) of a fixed cylinder (2) records information or reproduces already recorded information.

[Problem that the invention seeks to solve]

A rotary cylinder molded with conventional molding materials such as plastic has a normal shape when taken out from the mold, as shown in Figure 5 (a), but the head changes due to cooling after being taken out of the mold. The surface (403) of the mounting surface (401) facing the fixed cylinder (2) has contracted significantly as shown by the arrow (8), resulting in a shape as shown in FIG. 5 (B) (the amount of deformation is exaggerated). ) is deformed over time, and the head mounting surface (401) (7
There was a problem in that it was difficult to keep the degree of flatness, the roundness and cylindricity of the outer peripheral surface of the cylindrical portion (402) within predetermined accuracy.

This invention was made in order to solve the problems of the conventional ones, and it is possible to easily ensure the flatness of the head mounting surface of the rotary cylinder and the roundness and cylindricity of the outer peripheral surface of the cylindrical part to a predetermined accuracy. The object of the present invention is to provide a rotary head assembly that can be used.

[Means for solving problems]

In the rotary head assembly according to the present invention, the head mounting surface of the rotary head is provided in the axially intermediate portion of the cylindrical portion.

[For production]

In the rotary cylinder of the present invention, since the head mounting surface is provided in the middle of the cylindrical portion, the amount of shrinkage due to cooling after molding is equalized on both sides in the axial direction centering on the head mounting surface.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. FIG. 1 is a longitudinal cross-sectional view of a rotary head assembly according to an embodiment of the present invention, and is a cross-sectional view taken along line II in FIG. 2, and FIG. FIG. 4 is a bottom view of the rotary cylinder as seen, and the same parts as those of the conventional one in FIG. 4 are given the same reference numerals, and their explanation will be omitted.

In the figure, (4A) is a rotating cylinder corresponding to (4) of the conventional one, (401A) is a head mounting surface corresponding to (401), and the head mounting surface (401A) is a rotary cylinder corresponding to (4) of the conventional one.
) is provided exactly at the axial center of the cylindrical portion (402) as shown. (404) is a protrusion formed integrally with the head mounting surface (401A) to attach the magnetic head (3), and the head mounting surface (401A) is connected to the cylindrical portion (
402) was provided because it was located at the axially intermediate portion of the shaft.

Figure 3 shows the state in which the rotary cylinder (4A) with such a configuration is taken out of the mold when molded with plastic etc.
Figure 3 (b) shows the state after cooling. As is clear from this figure, the head mounting surface (401
By providing A) exactly at the axial center of the cylindrical portion (402), the amount of shrinkage due to cooling after molding is equal on both sides of the head mounting surface (401A) in the axial direction, so that the head mounting surface (401A) 401A) can be easily kept within a predetermined accuracy. Also, since the distance between the center (405) with the largest amount of contraction and both ends (406) and (407) in one direction that are farthest from it is half that of the conventional one, the center (405) + The difference (α) between the minimum radius and the maximum radius at both ends (406) and (407) is smaller than in the conventional one, and the roundness and cylindricity of the outer peripheral surface of the cylindrical portion (402) are also within the predetermined accuracy. It can be easily accommodated. Incidentally, the difference between the minimum radius and the maximum radius in the conventional one is shown by (b) in FIG. 5 (b).

In the above embodiment, the head mounting surface (401A) is located exactly at the axial center of the cylindrical portion (402).
Although this is the most preferable, both ends (406)
, (407), that is, the intermediate portion, the above-mentioned effect can be obtained to a greater or lesser degree. In reality, the closer it is to the center, the more preferable it is, and it is preferable to locate it exactly in the center including the center and its adjacent areas.

〔Effect of the invention〕

As described above), in this invention, the head mounting surface is provided at the axially intermediate portion of the cylindrical portion, so that the flatness of the head mounting surface and the roundness and cylindricity of the outer circumferential surface of the cylindrical portion can be easily adjusted to a predetermined accuracy. It has the effect of being able to contain a lot of things.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, showing a cross section taken along line 111-I in FIG. 2, and FIG. The bottom view of the cylinder and FIG. 3 are longitudinal sectional views of the rotary cylinder in this invention,
Figure 3 (a) shows the state when taken out from the mold.
B) is a diagram showing the state after cooling, FIG. 4 is a vertical cross-sectional view of a conventional rotary head assembly, FIG. Figure 5 (a) shows the state when taken out from the mold, and Figure 5 (b) shows the state after cooling. In the figure, (1) is a tape-shaped recording medium, (2) is a fixed cylinder, (3) is a magnetic head, (4A) is a rotating cylinder, (401A) is a head mounting surface, and (402) is a cylindrical portion. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Patent Attorney Masuo Oiwa 1--=

Claims (2)

[Claims] (1) A fixed cylinder that guides a tape-shaped recording medium, and a rotating cylinder that is rotatably supported from the fixed cylinder via a bearing and molded with a molding material, and the rotating cylinder records information on the tape-shaped recording medium. In a rotary head assembly for a magnetic recording/reproducing device, which has a head mounting surface on which a magnetic head to be reproduced is mounted and a cylindrical portion provided on the outer periphery of the head mounting surface, the head mounting surface is connected to an axially intermediate portion of the cylindrical portion. A rotary head assembly for a magnetic recording/reproducing device, characterized in that the rotary head assembly is provided in a magnetic recording/reproducing device. (2) Rotation of the magnetic recording and reproducing device according to claim 1, wherein the head mounting surface is provided at the axial center of the cylindrical portion, and the cylindrical portion has the same dimensions on both sides in the axial direction with the head mounting surface as the center. head assembly.