JPH0320901Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a rotary head cylinder installed in a video tape recorder (VTR) or the like.

(Prior Art) In general, a rotating head cylinder scans a magnetic tape hung on the outer circumferential surface of the cylinder using a magnetic head that rotates along the outer circumferential surface of the cylinder. For example, as shown in FIG. A rotary head cylinder is used. Lower cylinder 1 on chassis 6
0 is fixed, an upper cylinder 1 is provided above the lower cylinder, and a shaft 11 protruding downward from the center of the upper cylinder is supported by a bearing provided at the center of the lower cylinder.

A magnetic head 4 is provided protruding from the upper cylinder 1 and faces a slit between the upper cylinder 1 and the lower cylinder. Further, a fly hole 3 is screwed to the center of the inner surface of the upper cylinder, and a rotating part 21 of the rotary transformer 2 is adhesively fixed to the lower end surface of the fly hole. is fixed to the lower cylinder 10 facing the rotating part 21. The magnetic head 4 rotates at high speed by driving a shaft 11 by a motor provided outside the cylinder. At this time, if the center of gravity of the rotating body consisting of the upper cylinder, flyhole, etc. is eccentric from the center of the cylinder, the rotation will be unbalanced and vibrations will occur.

Conventionally, in response to this, a balance hole 30 was opened in the fly hole 3 as shown in FIG. 5 to perform balance adjustment. The position and magnitude of the unbalanced load on the rotating body can be easily discovered using a balancing machine.

(Problem to be Solved) However, in the conventional balance adjustment, there was a problem in that it took time and effort to drill the balance holes at appropriate positions on the flywheel.

Therefore, in Japanese Utility Model Application Publication No. 58-163025, a balance mounting land made of copper foil is provided on a printed wiring board placed on a rotating body, and the dynamic balance of the rotating body is achieved by welding solder to the land. A rotating head drum is disclosed.

However, in the rotating head drum, it is necessary to heap up the solder and make it adhere to the surface of the copper foil, and since there is no wall surface to restrain the molten solder on the surface of the copper foil from the surroundings, variations in the temperature of the molten solder, etc. Therefore, the degree of heaping and therefore the amount of solder is not constant, making accurate balance adjustment difficult.

Further, Japanese Patent Application Laid-open No. 195320/1983 discloses a method for balancing the weight by drilling tap holes at equal intervals on the same radius of a rotating drum and screwing a drill into the tap holes.

However, this method has the problem of complicating the manufacturing process because it requires drilling tap holes in the rotating drum and screwing in the tap holes.

The purpose of the present invention is to provide a rotary head cylinder that allows accurate balance adjustment by a simple method, and whose balance adjustment structure can be formed without significantly changing the conventional rotary head cylinder manufacturing process. That's true.

(Means for Solving the Problems) The rotating head cylinder according to the present invention supports a rotating body including a magnetic head 4 on the central axis of a stationary body fixed on a chassis 6 so as to be rotatable. , a rotary transformer 2 is interposed between a rotating body and a stationary body in opposing parts.

A disk-shaped printed circuit board 5 for electrically connecting the magnetic head 4 and the rotary transformer 2 is fixed to the rotating body in a plane perpendicular to the rotation axis. The printed circuit board 5 is formed by forming an insulating film 55 on the surface of a disc-shaped insulating base 53 with a conductive metal film 54 interposed therebetween. A hole 50 of a predetermined shape is provided at a location to expose the metal film 54, and a plurality of weight attachment portions are formed by the hole 50. The dynamic balance of the rotating body can be adjusted by welding solder to the weight attachment portions at appropriate positions among the weight attachment portions.

(Operation) When the rotating body is unbalanced, the dynamic balance of the rotating body is adjusted by melting solder to one or more weight attachment parts on the opposite side of the position where the unbalanced load exists.

At this time, the amount of molten solder in the hole 50 is accurately defined by the area and depth of the bottom surface of the hole 50.

The metal film 54 of the printed circuit board 5 is formed into a conductive pattern of an electric circuit to be interposed between the magnetic head 4 and the rotary transformer 2 through a process such as etching, similar to the conventional rotary head cylinder. be done.

(Effects of the invention) According to the rotary head cylinder according to the present invention, the balance adjustment structure of the rotor is configured using the printed circuit board 5, which is a component of the rotary head cylinder itself, and the printed circuit board 5 is mounted as a balance weight. Since the solder used for wiring connections is used, there is no need to make major changes to the conventional rotary head cylinder manufacturing process.

Also, when installing the balance weight, use the insulating film 55.
It is only a very simple operation of filling the holes 50 with solder, and since the amount of solder can be precisely defined as described above, highly accurate balance adjustment is possible.

(Example) Hereinafter, the present invention will be described in detail based on the illustrated example.

FIG. 1 shows a rotary head cylinder according to the present invention, in which a magnetic head 4 is protruded from an upper cylinder 1 and a shaft 11 fixed at the center of the upper cylinder is driven to rotate, similar to the conventional rotary head cylinder described above. By doing so, the magnetic head 4 is rotated.

FIG. 2 shows the rotating part 21 of the rotary transformer 2,
A flywheel 3 fixed to the rotating part is shown.
A printed circuit board 5 punched into an annular shape is attached concentrically to the back surface of the rotary transformer rotating section 21.

Incidentally, in the conventional rotary head cylinder, a rectangular printed circuit board 52 is used as shown in FIG. has been done. The tip of a conductive wire 71 drawn from the magnetic head 4 is soldered to the printed circuit board 52 as shown in FIG. 1 during the cylinder assembly stage.

The cross-sectional structure of the soldered portion of the printed circuit board 5 of this embodiment shown in FIG. 2 is completely the same as that of the conventional printed circuit board, and as shown in FIG.
A thin copper film 54 is formed in a predetermined pattern on the upper surface by a method such as photoetching.
The tip of the conductive wire 7 is soldered to the surface of the conductive wire 7.

In the printed circuit board 5 of this embodiment, the soldered portion 56 is used to perform the original function of the printed circuit board, and the other portion is used as a balance disk for mounting a balance weight.

FIG. 3 shows a cross-sectional structure of the weight mounting portion of the printed circuit board 5 which becomes the balance disk. insulation base
A copper thin film 54 is formed entirely on the upper surface of the copper film 53, and an insulating film 55 is further coated on the surface of the copper thin film 54. As shown in FIG. 2, the insulating film 55 has circular holes 50 repeatedly formed at the same pitch on the circumference, and the copper thin film 54 is formed through the holes.
is exposed to form the balance weight mounting part.

The reason why the weight attachment portion is formed on the surface of the copper thin film 54 is because solder is used as the balance weight, and solder does not adhere to the rotary transformer body. Therefore, the metal film may be formed using aluminum or the like instead of copper.

To balance the rotary head cylinder of this embodiment, after assembling the cylinder, use a balancing machine to detect the size and position of the unbalanced load, and then adjust the balance weight on the opposite side of the position where the unbalanced load exists. Weld an appropriate amount of solder to one location on the mounting part or several locations near it.
At this time, since the solder is applied only to the exposed portion of the copper thin film 54, the amount of solder fused can be easily controlled by keeping the exposed area the same. Furthermore, by adjusting the exposed area of the weight attachment portion, the weight of one balance weight can be changed arbitrarily.

In the present invention, the printed circuit board is also used as a balance disk, and the cross-sectional structure of the weight attachment part shown in FIG. 3 is almost the same as the cross-sectional structure of the conductive wire soldering part shown in FIG. The weight attachment part and the conductor soldering part can be manufactured at the same time in the same process. Furthermore, since solder as a balance weight is often used in the VTR manufacturing process, it can be implemented without major changes to the conventional process.

The present invention is of course not limited to the rotary head cylinder of the type shown in FIG. 1, but can of course be applied to various types of rotary head cylinders.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the rotating head cylinder according to the present invention, Figure 2 is a perspective view of the rotary transformer rotating part and flywheel equipped with the balance disk according to the present invention, and Figure 3 is a balance weight installation. 4 is a sectional view of a printed circuit board to which conductive wires are soldered. FIG.
Figure 2 shows a perspective view of the main unit. 1... Upper cylinder, 10... Lower cylinder,
2...rotary transformer, 3...flywheel
4...Magnetic head, 5...Printed circuit board, 5
1...Solder.

Claims (1)

[Scope of utility model registration request] A rotating body equipped with a magnetic head 4 is rotatably supported on the central axis of a stationary body fixed on a chassis 6, and a rotary transformer 2 is interposed between the rotating body and the stationary body. In the rotating head cylinder,
A disk-shaped printed circuit board 5 that electrically connects the magnetic head 4 and the rotary transformer 2 is fixed to the rotating body in a plane orthogonal to the rotation axis. An insulating film 55 is formed on the surface of an insulating base 53 via a conductive metal film 54, and the insulating film 55 exposes the metal film 54 at multiple locations around the rotation axis. By forming a plurality of weight attachment portions with the holes 50 and melting solder to the weight attachment portions at appropriate positions among the weight attachment portions, the rotating body can be fixed. A rotary head cylinder characterized in that the dynamic balance of the cylinder can be adjusted.