JPH0753123Y2 - Rotating head drum device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a rotary head drum device used in a magnetic recording / reproducing apparatus such as a video tape recorder.

(Prior Art) A rotary head drum device, which is a main component of a video tape recorder, rotates a rotary drum, and runs a magnetic tape along the outer periphery of the rotary drum along with rotation to record and reproduce video signals. FIG. 7 shows a conventional example. As is clear from the figure, the device is required to rotate stably with respect to the fixed drum (a) without the rotary drum (b) moving up and down. Therefore, the rotary shaft of the rotary drum (b) is required. A spring force by an elastic washer (d) is biased to a bearing (e) that axially supports the shaft (c) that becomes. Fixed drum (a) and shaft (c)
Highly accurate bearings (e) are used, but the track signal recorded on the magnetic tape has a very small width of tens of microns, so the rotating drum requires extremely high precision rotation. Therefore, in addition to improving the accuracy of the bearing, a preload is applied by the spring force, and it is necessary to prevent a slight backlash in the thrust direction of the bearing. Although various shapes of the elastic washer (d) can be considered, they are basically deformable with respect to the load in the thickness direction as shown in FIGS. Further, the elastic washer (d) is required not only to apply a preload to the inner ring of the bearing (e), but also to function as a cushioning material when an impact force is applied. The elastic washer (d) is not designed with a spring constant enough to absorb a large impact force, and cannot meet the requirement. Of course, it is easy to increase the spring constant and make it an elastic washer (d) with impact resistance, but if you increase the spring constant in this way, the preload applied to the bearing will become extremely large, It interferes with the rotation of the rotating drum. Therefore, since the elastic washer (d) has an appropriate spring constant, it is formed from a thin spring material, and a preload for supporting the elastic washer (d) instead of the elastic washer (d) against impact force. It is supported by a rib (g) provided along the outer periphery of the boss (f). That is, without the rib (g), the elastic washer (d) is crushed by the impact force, and as a result, the spring function is lost, thrust backlash of the bearing occurs, and the rotation accuracy of the rotary drum cannot be maintained. However, in order to form the rib (g) on the outer circumference of the preload boss (f), a member cut into a predetermined length must be machined by cutting, which is a major problem in reducing the number of machining steps. ing.

(Object of the Invention) As described above, the conventional rotary head drum device has the above-described problems regarding the elastic washer serving as the preload member and the preload boss that supports the elastic washer. The present invention is a technology devised for the purpose of solving these problems,
A rotary head drum device incorporating an elastic washer capable of exhibiting a cushioning function as well as the application of the preload by forming the elastic washer into a peculiar shape.

(Structure of the present invention) The rotary head drum device of the present invention is basically the same as the device shown in Fig. 7, and the rotary drum is rotatably supported by the fixed drum. The boss is fixed, but there is no rib on the preload boss, and the preload is applied to the inner ring of the bearing by the elastic washer inserted on the preload boss. Here, the elastic washer is basically a kind of disc spring and has a disc shape as a whole, but forms a dowel formed of a local convex portion. The shape of the dowel is not particularly limited, and generally has a hemispherical shape or a ring shape, and is somewhat lower than the height of the elastic washer. The dowel is preferably formed at the center of the upper surface, and sometimes at the outer peripheral portion.

(Operation) As described above, the dish-shaped elastic washers forming the dowels are arranged on the preload boss to apply a preload to the inner ring of the bearing. However, the inner ring of the bearing is always pressed to one side by the preload. The rotating drum is rotated while maintaining the state. That is, when the conventional preloading function is exerted and the impact force is further applied, the elastic washer is further elastically deformed, and
The dowel contacts the upper surface of the preload boss and is supported by the dowel. Since the dowel is locally formed in a convex shape, it can support a large impact force without losing its shape. The elastic washer has a small spring constant region for applying a preload and a large spring constant region for absorbing impact force.

Hereinafter, an embodiment of a rotary head drum device according to the present invention will be described in detail with reference to the drawings.

(Embodiment) FIG. 1 is an embodiment of a rotary head drum device of the present invention, in which 1 is a rotary drum, 2 is a magnetic head, and 3
Is a disk, 4 is a rotary transformer, 5 is a shaft,
The magnetic head 2 is disposed on the rotary drum 1, the rotary transformer 4 is attached to the disk 3, and the disk 3 and the rotary drum 1 are connected to each other via a screw. The shaft 5 is fitted to the portion. Therefore, the rotary drum 1 can rotate about the shaft 5 together with the disk 3, and the shaft 5 is rotatably supported by the bearing 8 attached to the central shaft portion of the fixed drum 6, and the fixed drum 6 has the above-mentioned rotation. A fixed transformer 7 is provided at a position facing the transformer 4. A preload boss 9 is fixed to the lower end of the shaft 5 by a screw 10, and an elastic washer 11 is arranged on the preload boss 9. The spring force of the elastic washer 11 pushes the inner ring of the bearing 8 upward. It is added as force (preload). That is,
By adjusting the fastening position of the preload boss 9, the magnitude of the preload is adjusted.

By the way, the elastic washer 11 for applying the above preload to the bearing 8
FIG. 2 shows a specific form of the above, and it is a shape as a kind of disc spring as a whole, but a plurality of legs 12 are formed in the outer peripheral portion, and the lower ends of the legs 12 are formed. Is the preload boss 9
A seat 13 is provided for stable placement on the upper surface of the. That is, a plurality of recesses 14 are formed on the outer peripheral portion of the disc spring. On the other hand, the upper end surface 15 is large enough to contact the inner ring of the bearing 8, has a hole 16 through which the shaft 5 can pass, and a plurality of dowels 17 are formed around the hole 16. is doing. The dowel 17 has a recess formed on the upper end surface 15 side,
Since it is a convex portion on the 12 side (downward), the downward protruding height of the dowel 17 is such that it does not reach the seat 13, and the load (impact force) is applied to the upper end surface 15. When actuated, the leg 12 is spring-deformed, the upper end surface 15 is lowered, and the dowel 17 comes into contact with the upper surface of the preload boss 9. That is, the dowel
17 functions as a kind of stopper when a large impact force is applied.

FIG. 3 is an enlarged view of part A in FIG. 1, showing the upper surface 18 of the preload boss 9.
The upper end surface 15 of the elastic washer 11 placed on the inner ring contacts the inner ring of the bearing 8 and is kept in a state in which a preload is applied to the inner ring. However, the impact force acts to reduce the distance between the preload boss 9 and the bearing 8. If compressed, the state shown in FIG. 4 is obtained. That is, if the distance is compressed, the elastic washer 11 is crushed and the leg is
12 collapses and expands so that the seat 13 is the upper surface 18 of the preload boss 9.
Thus, the outer circumference 19 floats, and the dowel 17 contacts the upper surface 18. Since the dowel 17 is formed to have a locally convex shape, it has high rigidity and can withstand a certain load. Therefore, the dowel 17 is not limited to the shape shown in FIG. 2, but a hanging piece is formed along the circumference of the hole 16 as shown in FIG. 5 as an enlarged view of the AA cross section of FIG. 5 and FIG. The dowel 20 may be used, or another suitable shape can be selected.

As described above, in the rotary head drum device according to the present invention, the elastic washer is arranged on the preload boss fixed to the lower end of the shaft to apply the preload to the bearing inner ring. This is a kind of disc spring, and if the disc spring is compressed and deformed, a dowel is formed to prevent the deformation against a certain amount of deformation, and the following effects can be obtained.

(Effect) (1) By interposing an elastic washer between the preload boss and the bearing, a preload is applied to the inner ring of the bearing to eliminate backlash of the bearing, and thus, the rotary drum is pivotally supported with high accuracy. Of course, the elastic washer can be supported by dowels against a large impact force that is sometimes generated when carrying a magnetic recording / reproducing apparatus such as a video tape recorder. Although the dowel allows some elastic deformation, it has a high rigidity (large spring constant), so it can withstand a large load in the shaft direction, and the elastic washer alone preloads the bearing with a preload function. It may exhibit a shock function.

(2) Since the elastic washer itself has a dowel that restricts the amount of deformation when an impact force is applied, it is not necessary to form a rib on the outer periphery of the upper surface of the preload boss, and the number of processing steps for the preload boss can be reduced. Can be done.

[Brief description of drawings]

FIG. 1 shows a specific example of the rotary head drum device of the present invention, FIG. 2 shows an embodiment of an elastic washer, FIG. 3 shows an enlarged view of part A of FIG. 1, and FIG. When the elastic washer is deformed, FIG.
The drawing is an enlarged view taken along the line AA in FIG. 5, FIG. 7 is a conventional rotary head drum device, and FIG. 8 is a conventional elastic washer used in the device. 1 ... Rotary drum, 2 ... Magnetic head, 3 ... Disk, 4 ... Rotating transformer, 5 ... Shaft, 6 ... Fixed drum, 7 ... Fixed transformer, 8 ... Bearing, 9 ... Preload boss , 10 …… screw, 11 …… elastic washer, 12 …… leg, 13
…… Seat, 14 …… Recess, 15 …… Upper surface, 16 …… Hole, 17,20
…… Dowel, 18 …… Top surface, 19 …… Perimeter.

Claims (2)

[Scope of utility model registration request] 1. A shaft is rotatably supported by a central shaft portion of a fixed drum via a bearing, and a rotating drum and a disk, which are connected and fixed to each other, are fixed to an upper end portion of the shaft, and a lower end portion of the shaft is fixed to the shaft. Is a rotating drum device in which a preload boss is fastened and an elastic washer is arranged on the upper surface of the preload boss, and the elastic washer applies a preload to the inner ring of the bearing, and the elastic washer is a disc spring. A rotary head drum device, wherein a dowel is formed on an upper end surface of a disc-shaped spring. 2. The rotary head drum device according to claim 1, wherein a plurality of recesses are formed on the outer peripheral portion of the elastic washer, and legs having seats for contacting the upper surface of the preload boss are provided.