JPH09167402A - Method for fitting head cylinder to chassis in magnetic recording and reproducing device and structure of chassis - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unnecessitate any additional parts of countermeasure, etc., and to reduce cost by fitting a cylinder to each receiving boss of a chassis with a screw and preventing deformation of the cylinder due to tightening of the screw. SOLUTION: If working force of deforming the cylinder 2 by tightening this crew, for example, in a VTR of a VHS system is denoted as F, while a distance between the receiving bosses 1b in two places is L=54mm, a diameter of the receiving boss 1b is D=0.6mm and reaction force to be given to the outer circumferential end of the receiving boss 1b is R, (6/2)×F=54+6R and R=(1/20)×F are established, and it is found that influence of force upon the cylinder 2 is only by one twentieth of the screw-tightening force F.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of attaching a head cylinder to a chassis in a helical scan type magnetic recording / reproducing apparatus such as a VTR equipped with a rotary magnetic head, and a structure of a chassis used directly in this method.

[0002]

2. Description of the Prior Art Generally, in a helical scan type magnetic recording / reproducing apparatus such as a VTR, a cylinder equipped with a rotating magnetic head is wound diagonally with respect to a chassis in order to run the magnetic tape obliquely. It is attached. For this reason, in a conventional VTR, a cylinder is fixed to a pedestal made of aluminum die-cast having an inclined surface which is precisely finished by machining, and this pedestal is fixed to a chassis. Further, in order to reduce the cost in the related art, there is also known one in which a receiving boss instead of the pedestal is integrally formed with the chassis. Since this receiving boss is formed by plastically deforming by drawing or bending the chassis sheet metal, it is mounted to receive and fix the cylinder as compared with the aluminum die cast machined with a milling machine etc. The accuracy of surface inclination is inferior. Therefore, simply pressing the receiving boss cannot be put to practical use, and secondary processing or the like needs to be performed, which may increase the cost. In addition, in order to compensate the inclination accuracy of the receiving boss formed by press working, a measure such as mounting a cylinder via an elastic member such as a coil spring is generally taken, but contrary to the initial cost reduction. Needless to say

A conventional cylinder mounting state will be described with reference to FIG. In the figure, 1 is a chassis, 2 is a cylinder, and 3
Is a screw, 1a is a narrowed portion, and 1b is a receiving boss. This receiving boss 1b is often provided at three locations. FIG. 1A is a plan view of the chassis 1 before mounting the cylinder 2, and FIG.
FIG. 3 is a sectional view of a main part with a cylinder 2 attached. Normally, since the cylinder 2 is cut by a precise lathe, the inclination accuracy of its mounting surface and the roundness of the tape running surface are extremely high, and it is necessary to run the magnetic tape while maintaining this accuracy. The cylinder 2 attached as described above is attached at a predetermined position of the chassis 1 and inclined at a predetermined height and at a predetermined angle, but when viewed microscopically, it is formed on the narrowed portion 1a of the chassis 1. Since it is very difficult to form the receiving boss 1b and the mounting surface of the cylinder 2 that are completely parallel to each other, the mounting surface of the cylinder 2 deforms following the surface of the receiving boss 1b in the mounted state. As a result, the circularity of the tape running portion is distorted due to the influence of the change, so that the image quality is deteriorated when the tape is actually run.

FIG. 4 shows a modeled state of the deformation of the cylinder 2. In this figure, a case where the receiving bosses 1b are provided at two positions will be described for easy understanding. In FIG. 4, the two receiving bosses 1b have a slight relative inclination toward the outside. That is, the mounting surface of the receiving boss 1b on which the cylinder 2 is mounted is such that the side farther from the center of the cylinder 2 with the cylinder 2 placed is closer to the side closer to the center. When it is formed so as to be separated from. The amount of the relative inclination varies due to the spring back generated by the press working, and even if the accuracy is increased to some extent, a few hundredths of a millimeter is surely left.

When the cylinder 2 is placed on the receiving boss 1b as shown in (a) and one screw 3 (on the left side in the drawing) is tightened as shown in (b), the above-mentioned (a) is obtained. Since the mounting surface of the receiving boss 1b and the mounting surface of the cylinder 2 placed on these receiving bosses 1b are not parallel to each other and are inclined by an angle θ1, the cylinder 2 follows the surface of the receiving boss 1b and is on the opposite side. (Right side in the drawing) is lifted. After that, when the other screw 3 is tightened, the mounting surface of the cylinder 2 is deformed by the screw 3 until it abuts on the receiving boss 1b.
Needless to say, the deformation of the mounting surface of the cylinder 2 distorts the roundness of the tape running surface, degrading the performance of the VTR.

Even if the strength around the throttle portion 1a of the chassis 1 is relatively weak, in the cylinder 2 which is usually made of aluminum alloy and the chassis 1 which is usually made by pressing an iron plate, Deformation on the 2 side is inevitable. Further, the chassis 1 is required to have strength against a change in tilt angle and impact, and is also used for mounting other mechanical elements, so that it is necessary to secure sufficient strength.

By the way, when the two screws 3 and 3 are alternately tightened little by little, as shown in FIG.
It is avoided that the opposite side (right side in the drawing) is lifted up following the surface of the receiving boss 1b (left side in the drawing), and the deformation of the cylinder 2 can be suppressed.
However, when producing a VTR, it is common to use a power tool such as an electric screwdriver or an air screwdriver to tighten the screws, and it is not practical to tighten the screws little by little like a manual screwdriver. Absent. Even if the two screws 3 and 3 are tightened at the same time, the deformation of the cylinder 2 can be suppressed. However, from a microscopic point of view, it is extremely difficult to tighten at exactly the same time, which is also impractical.

As a method of suppressing the deformation of the cylinder 2 as described above, a method of subjecting the press-formed receiving boss 1b to a secondary processing or a method of tightening a mounting screw so that the mounting surface of the cylinder 2 does not come into close contact with the receiving boss 1b. As described above, the method of attaching via the elastic member such as the coil spring is also implemented.

[0009]

As described above, in the conventional magnetic recording / reproducing apparatus such as the VTR, when the head cylinder is attached to the receiving boss formed integrally with the chassis, the cylinder is often deformed. In view of the above, the present invention suppresses the deformation of the cylinder due to the variation in the accuracy of the inclination of the mounting surface of the receiving boss even if the receiving boss is formed integrally with the chassis by pressing as described above, and is There is no need to add countermeasure parts,
It is an object of the present invention to provide a method of mounting a head cylinder on a chassis in a magnetic recording / reproducing apparatus and a structure of a chassis used in this method, which is truly cost-effective.

[0010]

In order to solve the above problems and achieve the above object, a method of mounting a head cylinder on a chassis in a magnetic recording / reproducing apparatus of the present invention is a cylinder equipped with a rotating magnetic head. A method of mounting the cylinder to a chassis in a magnetic recording / reproducing apparatus such as a VTR in which a magnetic tape is wound diagonally and running, wherein the chassis is mounted on the chassis at an outer peripheral edge of the cylinder. It has a plurality of receiving bosses formed integrally along the inner side, and in order to support the cylinder in an inclined state with respect to the chassis by these receiving bosses, the cylinders are sequentially applied to the plurality of receiving bosses of the chassis. In the one that is screwed with a power tool, the mounting surface for mounting the cylinder of the receiving boss as the chassis is Prepare a cylinder formed such that the side closer to the center of the cylinder is farther from the mounting surface of the cylinder than the side farther from the center when the cylinder is placed. As described above, the cylinder is screwed.

Further, the structure of the chassis in the magnetic recording / reproducing apparatus of the present invention is the structure of the chassis in the magnetic recording / reproducing apparatus such as a VTR in which a magnetic tape is obliquely wound around a cylinder equipped with a rotating magnetic head for running. The chassis has a plurality of receiving bosses integrally formed along the inside of the outer peripheral edge of the cylinder attached to the chassis. In a state in which the cylinder is supported in an inclined state, the mounting surface of the receiving boss to which the cylinder is mounted has a side closer to the center of the cylinder in a state in which the cylinder is placed as compared with a side farther from the center. It is characterized in that it is formed apart from the mounting surface of the cylinder.

[0012]

In the present invention configured as described above, when the cylinder is mounted on the receiving boss and one screw is tightened, the mounting surface of the receiving boss and the mounting surface of the cylinder mounted on the receiving boss are separated. Even if the cylinder is not parallel and tries to follow the surface of the receiving boss, the side opposite to this receiving boss of the cylinder hits another receiving boss and the cylinder does not adhere to the mounting surface of the receiving boss when screwed. Deformation is suppressed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows an embodiment of the present invention. In this figure, three receiving bosses 1b on a narrowed portion 1a of a chassis 1 are set so as to be inclined at a slight angle in the central direction (arrow direction) of the inclined surface. ing. That is, the chassis 1 has a plurality of receiving bosses 1b integrally formed along the inside of the outer peripheral edge of the cylinder 2 attached to the chassis. The cylinder 2 is supported in an inclined state with respect to 1. And the receiving boss 1
The mounting surface of b on which the cylinder 2 is mounted is formed such that the side closer to the center of the cylinder 2 in the mounted state is farther from the mounting surface of the cylinder 2 than the side farther from the center. There is. With the cylinder 2 placed on the receiving boss 1b as described above, the receiving boss 1b
As for the amount of angle between the mounting surface of the cylinder 2 and the mounting surface of the cylinder 2, the side closer to the center of the cylinder 2 with the cylinder 2 placed as described above is in spite of variations in springback during press working. The distance from the mounting surface of the cylinder 2 is sufficient as compared with the side farther from the center, and a step of about several hundredths of a millimeter may be provided.

Next, in order to facilitate understanding of the relationship between the receiving boss 1b and the mounting surface of the cylinder 2 when tightening the screws in FIG. 2, a case where the receiving boss 1b is at two positions will be modeled and described. . As shown in FIG. 2A, the mounting surface of the receiving boss 1b on which the cylinder 2 is mounted is such that the cylinder 2 is mounted on the receiving boss 1b as shown in FIG.
The side closer to the center of the cylinder is formed so as to be farther from the mounting surface of the cylinder 2 than the side farther from the center. In this mounted state, the mounting surface of the cylinder 2 and the mounting surface of the receiving boss 1b are formed. The angle formed is θ2.

In this state, one screw 3 (left side in the drawing)
2B is tightened as shown in FIG. 2B, the receiving boss 1b tries to come into close contact with the mounting surface of the cylinder 2 due to the tightening force of the screw 3. However, the outer peripheral ends of both receiving bosses 1b first contact the mounting surface of the cylinder 2. Abut. The force generated in the direction of the cylinder 2 by the subsequent screw tightening is the distance L1 from the outer peripheral end of the receiving boss 1b on the screwed side to the center of the screw 3.
And the distance L2 from the outer peripheral end of the receiving boss 1b (on the right side in the drawing) on the side not screwed to the center of the screw 3, the receiving boss 1b of the cylinder 2 is received.
The force in the direction of closely contacting (on the right side) is drastically reduced, and as a result, a gap remains between the inner peripheral side of the receiving boss 1b and the mounting surface of the cylinder 2.

Taking a VHS type VTR as an example, the force acting to deform the cylinder 2 by tightening this screw is F, and the distance between the two receiving bosses 1b is L = 54 mm.
Diameter of receiving boss 1b is D = φ6 mm, receiving boss 1b
If the reaction force applied to the outer peripheral edge of is R, then (6/2) × F = (54 + 6) R R = (1/20) × F, and only 1/20 of the force F due to screw tightening is applied to the cylinder. It turns out that it does not affect 2.

Actually, screws are respectively fastened to the three receiving bosses 1b, but it goes without saying that the above modeling example is applied. Further, as can be understood from the description of the embodiment, the diameter of the receiving boss 1b is made as small as possible, and the distance between the receiving bosses 1b is made as large as possible, so that the deformation of the cylinder 2 due to the screw tightening is further suppressed. To be In the embodiment described above, the receiving boss 1b is inclined at a slight angle with respect to the throttle portion 1a. Even if set, the same effect can be obtained.

[0018]

Since the present invention is configured as described above, the deformation of the cylinder is suppressed when the screw is mounted to mount the cylinder on the chassis integrally formed with the receiving boss of the cylinder, and the tape running of this cylinder is suppressed. The roundness of the surface can be maintained with high accuracy, and the cost can be truly reduced.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention,
(A) is a plan view of the chassis before the cylinder is attached, and (b) is a vertical sectional front view with the cylinder attached.

2A and 2B are model views showing an embodiment of the present invention, in which FIG. 2A is a state in which a cylinder is mounted on a chassis, and FIG. 2B is a state in which the cylinder on the chassis is fixed with one screw. FIG.

3A and 3B are views showing a conventional example, in which FIG. 3A is a plan view of a chassis before a cylinder is attached, and FIG. 3B is a vertical sectional front view with a cylinder attached.

FIG. 4 is a modeled view of a conventional example, in which (a)
Shows the cylinder mounted on the chassis, (b) shows the cylinder fixed on the chassis with one screw,
(C) is a vertical cross-sectional front view of a state in which the cylinder on the chassis is fixed with both screws.

[Explanation of symbols]

 1 chassis 1a throttle part 1b receiving boss 2 cylinder 3 screw

Claims (2)

[Claims] 1. A method of mounting the cylinder to a chassis in a magnetic recording / reproducing apparatus such as a VTR in which a magnetic tape is obliquely wound around a cylinder equipped with a rotary magnetic head for running, and the chassis is the chassis. A plurality of receiving bosses integrally formed along the inner side of the outer peripheral edge of the cylinder attached to the cylinder, the supporting bosses supporting the cylinder in an inclined state with respect to the chassis. , Wherein the cylinder is sequentially screwed to a plurality of receiving bosses of the chassis with a power tool, and the mounting surface of the receiving boss to which the cylinder is attached is a state in which the cylinder is placed. The side closer to the center of the cylinder is formed farther from the mounting surface of the cylinder than the side farther from the center. Was prepared, the head cylinder mounting method of the cylinder as described above to receive the boss of the chassis to the chassis of the magnetic recording and reproducing apparatus, characterized in that the set screw. 2. A structure of a chassis in a magnetic recording / reproducing apparatus such as a VTR in which a magnetic tape is obliquely wound around a cylinder equipped with a rotating magnetic head and is run, wherein the chassis is attached to the chassis. In the one having a plurality of receiving bosses integrally formed along the inside of the outer peripheral edge of the cylinder, and supporting the cylinder in an inclined state with respect to the chassis by these receiving bosses, The mounting surface of the receiving boss on which the cylinder is mounted is formed so that the side closer to the center of the cylinder in the mounted state is farther from the mounting surface of the cylinder than the side farther from the center. The structure of the chassis in the characteristic magnetic recording and reproducing device.