JPS63241714A - Magnetic recording and reproducing drum - Google Patents

Abstract

PURPOSE:To eliminate the shaking of rotation, to reduce manhour, and to miniaturize a device, by forming the inner and outer peripheral parts which constitute a rotary drum integrally with pressurization, etc., and applying machining on a hole part, the outer peripheral part, and a head base plane, etc., simultaneously. CONSTITUTION:The rotary drum 1 in which the fixed shaft 3 of a fixed drum 2 is inserted in such a way that it can be turned freely consists of the inner peripheral part 1b having the hole part 11 for insertion and the outer peripheral part 1a which slides with a magnetic tape, however, they are structured integrally by the pressurization, and a thrust bearing 5 is formed at the end part of the shaft. As holding the outer periphery 12 of the inner peripheral part 1b, the machining of the hole part 11, the outer peripheral part 14, a thrust bearing mounting plane 15, and a head mounting plane 13 are performed simultaneously. Therefore, no rotational shaking of the drum 1 is generated, and the reduction of the number of working processes, the improvement of accuracy, and the miniaturization of the device can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing drum used in video tape recorders, etc. 1, and particularly to a drum structure suitable for miniaturization, high precision, and improvement in productivity. Regarding.

[Conventional technology]

Generally, a VTR device has a rotating head and performs recording and reproduction by relatively scanning a magnetic tape and the rotating head. A drum is fixed on the same axis as the rotation axis of the rotating head to maintain constant contact between the head and the tape.

It has a structure in which at least one of the rotating drums is disposed, and the magnetic tape is wound helically around the drum surface. Further, the one-rotation head is slightly protruded from the drum surface so that the rotary head and the magnetic tape come into sliding contact in an oblique direction. The rotating head is fixed to a head base, and the head base is attached to the end face of a rotating drum with screws or the like, and the one-rotation drum is attached to the rotating shaft with a disk screw or the like that is fixed by press-fitting or the like. This structure is described in 1, for example, "Japan Mechatronics (Mechatronics) ■, Applied Edition 1. p99J.

Incidentally, the recording track width of a VTR is extremely narrow (approximately 20 .mu.m), and therefore the rotary head must accurately record the recording pattern on the magnetic tape. However, the accuracy of this recording pattern depends on the whirling degree of the outer periphery of the rotating drum. That is, if the whirl becomes large, the recording pattern will be recorded deviating from the ideal straight line accordingly. Generally, the swing of this rotating drum is
A thickness of 3 to 4 μm or less is required.

Because such high precision is required, conventional methods have been to fix the disk surface to the rotating shaft by press-fitting, etc., and then insert the rotating shaft into a bearing provided on the fixed drum and machine the rotating drum mounting surface while rotating. The accuracy of the mounting surface was improved. Furthermore, when installing the 1-rotation drum, measure and adjust the amount of whirl of the rotary drum, and make sure that the whirl is 3~
When it became 4 μm or less, it was fixed with screws.

That is, conventionally, the disk and the rotating drum were processed separately with high precision and used in combination. this is,
This is because it is difficult in machining to maintain the precision of the fitting portion to within a few microns. For example, the fit tolerance between a shaft and a hole with a diameter of 30 m or less is:

The basic tolerance between h7 and H7 is ±21 μm. in this case,
A gap of up to 42 μm will occur.

In addition, tightly fitting the shaft and the disk by press-fitting or the like is also inappropriate in terms of improving precision, as this causes deformation of each part.

In this way, conventional devices combine a plurality of parts, and there is a limit to achieving high precision. For this reason, there has been no suitable way to increase the accuracy of the whirling of the drum for one rotation other than by increasing the accuracy through processing and adjustment after one assembly.

[Problem that the invention seeks to solve]

In the above conventional technology, the disk is fixed to the rotating shaft.

The disk and rotating drum are assembled into a fixed drum and machined with high precision, and then the rotating drum is further adjusted to achieve precision. There was a problem in that no consideration was given to machining the surface, and that there was a limit to the improvement of accuracy and that a large number of man-hours were required for adjustment work.

The present invention has been made in view of the above situation, and it is an object of the present invention to provide a magnetic recording and reproducing drum that can improve the accuracy of whirling, reduce the number of work steps, and realize further miniaturization.

[Means for solving problems]

The present invention is characterized in that the upper end face of a fixed shaft erected at the center of the fixed drum has a flat surface perpendicular to its axis, and the rotary drum that is rotatably fitted into the fixed shaft has a hole for fitting. an outer circumferential portion that slides on the magnetic tape, and a thrust bearing plate attached to the upper surface of the inner circumferential portion, and the inner circumferential portion and the outer circumferential portion are fixed and integrated. 6 [Function] The rotating drum is inserted into a fixed shaft to directly rotate the rotating drum, and a magnetic head is attached to the periphery of the rotating drum, and the outer circumference of the rotating drum is machined. It can be controlled by accuracy. The upper end surface of the fixed shaft is carefully formed into a perpendicular plane, and the single-rotating drum is constructed with a thrust bearing plate to which the rotating drum's thrust bearing can be attached, improving ease of production and assembly. It consists of an inner circumferential part with a hole for use, an outer circumferential part with a magnetic head, etc., and the inner circumferential part and the outer circumferential part are integrally fixed, so there is no need to assemble them, and assembly errors and The machining error of each of these parts can significantly reduce the whirling error on the outer circumference of the rotating drum. The thrust bearing plate is simply attached to the upper surface of the inner circumference with screws, etc., so it does not have a negative effect on swing.

〔Example〕

Hereinafter, the magnetic recording and reproducing drum of the present invention will be explained using Examples.
This will be explained with reference to FIGS. 2 and 3. FIG. 1 is a sectional view of the embodiment. In the figure, 1 is a rotating drum, 2 is a fixed drum, 3 is a fixed shaft, 7 is a helad base, 8 is a rotating head, 9a, 9b are non-contact signal transmission mechanisms, 4a, 4b are radial dynamic pressure bearing grooves, 5 1 is a thrust dynamic pressure bearing, 6 is a thrust bearing plate, 10a is a stator of the drive motor, 10b is a rotor of the same motor, 13 is a helad base mounting surface, 14 is an outer peripheral surface of the rotating drum 1, 11 is a bearing hole for inserting a fixed shaft Department,
6 is a thrust bearing plate, 15 is a thrust bearing plate mounting surface, and 16 is a non-contact signal transmission mechanism mounting surface.

The magnetic recording/reproducing drum of this embodiment is a magnetic recording drum.

A rotary head 81 that performs reproduction; a rotary drum 19 that rotates integrally with the rotary head 8; a drive motor 10 that rotationally drives the rotary head 8; Non-contact signal transmission mechanisms 9a and 9b that contactlessly transmit signals to and from the fixed drum 22 rotating head 8 from the fixed drum 2 side, which supports the motor 10a and the fixed shaft 3.
It's getting better.

A rotary head 8 is fixed to the rotary drum 1 via a helad base 7, and a magnetic tape (not shown) is attached to the outer peripheral surface 14.
The zero-rotation head 8, which rotates while being wrapped around the tape, protrudes slightly outward from the outer circumferential surface 14 and has a structure that makes it easy to contact the tape. The magnetic tape is also wound around the outer peripheral surface of the fixed driver 2 at the same time. Also.

A non-contact signal transmission mechanism 9b is fixed to the rotating drum 1, a hole 11 for supporting radial load is provided in the center of the drum, and a thrust bearing plate 6 is attached to one end of the hole 11. . The fixed shaft 3 is fixed to the fixed drum 2 by press fitting or the like.

V-shaped grooves 4a and 4b are provided on the outer periphery of the fixed shaft. The depth of the groove is several microns to several tens of microns. Further, a spiral groove having a depth of several microns to several tens of microns is also provided on the surface of the thrust bearing plate 6 facing the fixed shaft 3 (not shown).
This groove is formed by several grooves that are directed outward from the center of the rotating drum 2 and curved in the direction of rotation of the drum, and serve as a thrust bearing 5. A viscous fluid is sealed between the hole 11 and the fixed shaft 3 as a lubricant.

When the rotating drum 1 starts to rotate by the drive motor, the viscous fluid flows along the grooves 4a, 4b and the groove of the thrust bearing 5 as the drum 1 rotates, so that it gathers at the center of the figure 7 and the center of the thrust bearing 5. Therefore, pressure is generated within the bearing portion, and the rotating drum 1 floats from the fixed shaft 3 and rotates without contact.

The hole 11 and the fixed shaft 3 have a radial gap of several microns to several microns, but when the rotating drum is rotating, the position of the rotating drum relative to the fixed drum is stable under a constant condition. However, when the rotating drum stops rotating, play occurs by the radius gap, and the positions of the rotating drum and the fixed drum are not constant.

The zero-rotation drum 1 shown in FIG. 2 is a cross-sectional view of the rotating drum 1. The zero-rotation drum 1 is composed of an outer peripheral part 1a that slides on the tape and an inner peripheral part 1b that slides on the fixed shaft 3. The outer circumferential portion 1a is made of AQ material or the like that has low friction with the tape. The inner peripheral part 1b is
Lead bronze castings, brass, etc., which are commonly used as bearing materials, are used. The outer circumferential portion 1a and the inner circumferential portion 1b are fixed together by press fitting, shrink fitting, forging, etc., and have an integral structure. The magnetic recording and reproducing drum has a rotation accuracy of 3 to 4 on the outer periphery.
Accuracy of less than μm is required.

Furthermore, with a rotating drum using hydrodynamic bearings, only when rotating,
Since the position and attitude relative to the fixed drum are determined, it is difficult to adjust the amount of swing of the outer peripheral portion of the rotating drum in a stopped state. Therefore, the outer periphery 12 of the hole 11 is chucked, and in this state, the outer periphery 12 of the hole 11. Thrust bearing plate mounting surface 15. The head base mounting surface 13 is machined. This allows the coaxial bearing between the hole portion 11 and the outer peripheral portion 14 and the perpendicularity between the six portions 11 and the thrust bearing plate mounting surface 15 to be machined with high precision. Conventionally, the outer circumferential portion 1a and the inner circumferential portion 1b were separate members, and the necessary accuracy was achieved by adjustment, but by making them an integral structure as in the first proposal, it is possible to improve the accuracy to the level of machining. Can be done. Also, for joining the outer peripheral part 1a and the inner peripheral part 1b.

Since the conventionally used screws and the like are no longer necessary, the rotary drum can be made thinner, which is also effective in reducing the size of the drum as a whole. Incidentally, if the rotating drum 1 is made of a single material as shown in FIG. 3, productivity will be further improved.

In this way, the magnetic recording/reproducing drum of this embodiment is constructed.

By adopting a structure in which the rotating drum outer circumference 14 and the bearing parts 11 and 15 can be machined with the same chuck, the machining accuracy is significantly improved compared to the past, and the accuracy of swinging is also improved, so no adjustment work is required. Therefore, the number of man-hours can be significantly reduced.

〔Effect of the invention〕

According to the present invention, since the outer peripheral surface of the drum and the bearing portion can be processed simultaneously, there are effects of improving accuracy, reducing assembly man-hours, and making the drum thinner.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the magnetic recording/reproducing drum of the present invention, and FIG. 2 is a longitudinal sectional view of the rotating drum. FIG. 3 is a longitudinal sectional view of a rotating drum according to another embodiment. DESCRIPTION OF SYMBOLS 1... Rotating drum, 2... Fixed drum, 3... Fixed shaft, 4... Bearing groove, 5... Thrust bearing, 6...
- Thrust bearing plate, 7... Head base, 8... Head, 9a. 9b... non-contact signal transmission mechanism, 10a, 10b...
・Drive motor, 11... Hole, 13... Head base mounting surface, 14... Outer circumferential surface, 15... Thrust bearing plate mount 1 Figure 2 Figure 3 Figure 12''

Claims (1)

[Scope of Claims] 1. A fixed drum, a fixed shaft erected at the center of the fixed drum, a rotating drum rotatably fitted into the fixed shaft and placed opposite the fixed drum, and a rotating A magnetic recording/reproducing drum having a magnetic head installed on the periphery of the drum, a signal transmitting section consisting of a transmitter/receiver provided on opposing surfaces of the stationary drum and the rotating drum, respectively, and a driving section for the rotating drum. , the fixed shaft has a flat surface perpendicular to its axis on its upper end surface, and the rotating drum has an inner peripheral part having a hole for fitting the fixed shaft, and an outer peripheral part that slides on the magnetic tape. and a thrust bearing plate attached to the upper surface of the inner peripheral portion so that the thrust bearing portion facing the upper end surface of the fixed shaft has a surface perpendicular to the axis of the hole for shaft insertion. Further, a magnetic recording/reproducing drum characterized in that the boundary portion between the inner circumferential portion and the outer circumferential portion is fixed by shrink fitting, press fitting, forging, etc. to form an integral structure.