JPS63228408A - Rotation head drum device - Google Patents

Abstract

PURPOSE:To build in, miniaturize and thin a coreless motor into a rotation drum by supporting a rotation drum freely rotatably to a fixed shaft, fitting a stator coil to the fixed shaft, sandwiching the stator coil, executing the facing and fitting a rotor magnet and a rotor yoke to the rotation drum. CONSTITUTION:A rotor magnet 33 and a rotor yoke 42 are fitted at a rotation drum 25 so as to sandwich and face a stator coil 36 fitted horizontally to a fixed shaft 22. Consequently, the rotor yoke 42 is attracted by an attracting force P of the rotor magnet 33. here, since the rotor yoke 42 is fitted at the rotation drum 25, the attracting force P is received by the rotation drum 25 itself, and the attracting force P is not added as the load in a thrust direction to both bearings 23 and 24. Thus, a motor 30 of a structure, the so-called coreless structure, in which the attracting force P of the rotor magnet 33 is not added to both bearings 23 and 24 as an overload, can be built in the rotation drum 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary head drum device suitable for application to, for example, a video tape recorder.

[Summary of the invention]

The present invention provides a rotary head drum device in which a rotary drum having a magnetic head is rotationally driven by a motor, in which the rotary drum is rotatably supported on a fixed shaft via a bearing, and a stator coil is mounted on the fixed shaft. At the same time, by attaching the rotor magnet and rotor yoke to the rotating drum so as to face each other with the stator coil in between, the rotor magnet's attractive force is not applied to the bearing that rotatably supports the rotating drum. The mold motor can be built into the rotating drum.

[Conventional technology]

Conventionally, it has been desired that video tape recorders and the like be made smaller and thinner, and the rotary head drum device, which is one of the important components, has a great influence on this reduction in size and thinness.

A known example of this type of rotary drum device is Japanese Patent Laid-Open No. 7-198531. In this known example, a rotating shaft is rotatably supported by a lower fixed drum via a bearing, a rotating drum having a magnetic head is attached to the rotating shaft at the upper part of the lower fixed drum, and is fixed to the lower fixed drum by a support member. The upper fixed drum is installed on top of the rotating drum.

A flat motor is provided, which includes a stator coil that is horizontally attached to the lower part of the lower fixed drum, and a rotor magnet that is attached to the lower end of the rotating shaft so as to face the stator coil. This motor drives the rotary drum between the upper and lower fixed drums.

However, although a flat type motor is used in the above-mentioned known example, the motor is provided outside and below the lower fixed drum. For this reason, there is a limit to reducing the overall height of the rotating head drum device.
It was difficult to significantly reduce the size and thickness of the entire device.

Therefore, in order to significantly reduce the size and thickness of the entire rotary head drum device, the inventors of the present invention first installed a flat motor in the empty space of the rotary drum, as shown in FIG. investigated.

In the prior study example shown in FIG. 2, a fixed drum (lower drum) 2 is mounted on a drum base 1, and a fixed shaft 3 is press-fitted into this fixed drum 2. A fixed shaft 3 protruding above the fixed drum 2 has a pair of upper and lower bearings 4.
A rotary drum (upper drum) 6 is rotatably supported via the rotary drum 5, and a plurality of magnetic heads 7 are attached to the outer peripheral portion of the lower end of the rotary drum 6. A compression coil spring 8 is inserted between both outer races of both bearings 4.5, and a predetermined preload (for example, about 300 g) is applied at a fixed position. A circular recess 9 is provided in the upper part of the rotating drum 6, and a ring-shaped rotor magnet 10 is mounted on the circular recess 9 via a rotor yoke 11. Further, a stator yoke 12 is horizontally attached to the outer circumference of the upper end of the fixed shaft 3, and a stator coil 13 is provided on the lower surface of the stator yoke 12 so as to face the rotor magnet 10. Therefore, the rotor magnet 10
A flat motor 14 is configured by the rotor yoke 11, stator yoke 12, and stator coil 13,
The rotary drum 6 is rotationally driven with respect to the fixed shaft 3 by this motor 14 .

[Problem that the invention seeks to solve]

According to the prior study example of the above-mentioned rotating head drum device,
By incorporating the flat motor 14 into the rotating drum 6, the height of the entire rotating head drum device can be significantly reduced, and the entire device can be made significantly smaller and thinner.

However, the following problems occurred with this method.

That is, in the example of the prior study, the stator yoke 12 is attracted by the attractive force P of the rotor magnet 10 attached to the rotating drum 6. However, since this stator yoke 12 is attached to the fixed shaft 3, the entire rotating drum 6 is pulled upward (in the direction of arrow a) by the suction force P. Therefore, the suction force P is directly applied to both bearings 4.5 as a load F in the thrust direction.

In this case, the attractive force P of the rotor magnet 10 is, for example, 600 g to 800 g, which greatly exceeds the optimum value of about 300 g for the preload by the compression coil spring 8, resulting in a large excess load F on both bearings 4.5. Therefore, there is a problem in that the accuracy and life of both bearings 4.5 are significantly deteriorated, and it has been difficult to realize this prior study example.

Therefore, the present invention has a structure in which the attraction force of the rotor magnet is not applied to the bearing that rotatably supports the rotating drum, and allows a flat motor to be built into the rotating drum.

[Means for solving problems]

The present invention provides a rotating drum that has a magnetic head and is rotatably supported on a fixed shaft via a bearing, a stator coil that is horizontally attached to the fixed shaft, and a rotary drum that faces the stator coil with the stator coil in between. The rotary drum is provided with a rotor magnet and a rotor yoke attached to the rotary drum, and the rotary drum is rotationally driven by a motor comprising the stator coil, rotor magnet, and rotor yoke.

[Effect]

According to the present invention, the rotor magnet and rotor yoke are attached to the rotating drum so as to face each other across the stator coil attached to the fixed shaft, so the attraction force of the rotor magnet pulls the rotor yoke, and this attraction The force is absorbed by the rotating drum itself, and the suction force is not applied to the bearing as a load in the thrust direction. Therefore, a flat type motor having a so-called coreless structure, which prevents the attraction force of the rotor magnet from being applied to the bearing as an excessive load, can be built into the rotating drum.

〔Example〕

An embodiment in which the present invention is applied to a rotary head drum device of a video tape recorder will be described below with reference to FIG.

First, a cylindrical fixed drum (lower drum) 21 is mounted on a drum base 20 such as a chassis, and a fixed shaft 22 is vertically press-fitted into the center of the fixed drum 21.

The fixed shaft 22 projects above the fixed drum 21, and a cylindrical rotating drum (upper drum) 25 is rotatably supported on the fixed shaft 22 via a pair of upper and lower bearings 23,24.

A plurality of magnetic heads (video heads) 26 are attached to the outer periphery of the lower end of the rotating drum 25.

Note that both bearings 23 and 240 and both balls are engaged in an annular groove 27 formed on the circumferential surface of the fixed shaft 22. Further, a compression coil spring 28 is inserted between both outer races of both bearings 23 and 24, and a predetermined preload (for example, about 300 g) is applied at a fixed position.

Next, a motor 30 for rotating the rotary drum 25 with respect to the fixed shaft 22 is built into the rotary drum 25 . That is, a circular recess 32 is provided in the upper part of the rotating drum 25 except for a cylindrical part 31 on the outer periphery. A magnet case 34 made of a magnetic material and having a ring-shaped rotor magnet 33 fixed to its upper surface is attached onto the circular recess 32 with screws 35. A stator coil 36 is arranged horizontally opposite the rotor magnet 33. This stator coil 36 is a thin disk-shaped printed circuit board on which a plurality of coils are formed, and a holder 38 is attached to a boss 37 that is press-fitted to the outer circumference of the upper end of the fixed shaft 22.
It is attached by screws 39 via. Furthermore, 40
is a terminal pin to which a cord for supplying current to the stator coil 36 is connected. Also magnet case 34
A shield case 41 is provided outside the stator coil 36 to prevent the influence of leakage magnetic flux on the magnetic head 26. A ring-shaped rotor yoke 42 made of a magnetic material is attached to the rotating drum 25 so as to face the stator coil 36 .

Here, a notch 43 is provided in an annular shape inside the upper end of the cylindrical portion 31 of the rotating drum 25, and by fitting the outer peripheral portion 42a of the rotor yoke 42 into the notch 43, the rotor yoke 42 is attached to the rotating drum 25. is maintained. Therefore, the stator coil 36 and the rotor magnet 33
A flat type motor 30 is constituted by the rotor yoke 42 and the rotor yoke 42, and the rotary drum 25 is rotationally driven with respect to the fixed shaft 22 by the motor 30.

According to the rotary head drum device configured as described above, the stator coil 3 is horizontally attached to the fixed shaft 22.
Since the rotor magnet 33 and the rotor yoke 42 are attached to the rotating drum 25 so as to face each other with 6 in between, the rotor yoke 42 is attracted by the attraction force P of the rotor magnet 33. Here, since the rotor yoke 42 is attached to the rotating drum 25, the suction force P is not received by the rotary drum 25 itself, and the suction force P is not applied to both bearings 23, 24 as a load in the thrust direction. Therefore, the motor 3 has a structure in which the attractive force P of the rotor magnet 33 is not applied as an excessive load to both bearings 23, 24, a so-called coreless structure.
0 can be built into the rotating drum 25.

By the way, in order for the rotor yoke 42 to receive the attractive force of the rotor magnet 33, a structure is required that allows the rotor yoke 42 to be mechanically held securely on the rotating drum 25 and rotated together with the rotating drum 25. Therefore, problems arise due to an increase in the number of parts and a deterioration of the space factor due to special holding parts. However, according to this embodiment, a notch 43 is provided inside the upper end of the cylindrical portion 31 of the rotating drum 25, and the rotor yoke 4 is inserted into the notch 43.
Since the outer peripheral portions 42a of the stator yoke 42 are fitted together, the rotor yoke 42 is pulled toward the rotor magnet 33 by the attractive force P of the rotor magnet 33, and the attractive force P also acts to prevent the stator yoke 42 from rotating. Therefore, since the rotor yoke 42 is simply fitted into the notch 43, its shape can be simplified, and
rotor yoke 4 without the need for any special retaining parts.
2 is securely held on the rotating drum 25, and the rotating drum 2
It can be rotated together with 5.

Further, since the rotor magnet 33 and the rotor yoke 42 are rotated together, there is less loss of magnetic flux compared to the stator yoke type as in the previous study example, and the efficiency of the motor 30 can be improved.

Although one embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and various effective changes can be made based on the technical idea of the present invention.

For example, in the embodiment, the rotor yoke and rotor magnet are arranged above and below the stator coil, but it is also possible to arrange these in the opposite way. Further, in the embodiment, a drum structure including a lower fixed drum and an upper rotating drum is shown, but a structure in which a rotating drum is provided between the upper and lower fixed drums may also be used.

Note that the present invention is not limited to the rotary head drum device of a video tape recorder, but is applicable to rotary head drum devices of various recording and reproducing devices and information processing devices, such as digital audio recorders.

〔Effect of the invention〕

The present invention includes a rotating drum that is rotatably supported on a fixed shaft via a bearing, a stator coil mounted on the fixed shaft, and a rotor magnet and rotor yoke mounted on the rotating drum so as to face each other with the stator coil in between. Therefore, a so-called flat coreless brushless morph, which has a structure in which the attraction force of the rotor magnet is not applied as an excessive load to the bearing that rotatably supports the rotating drum, can be built into the rotating drum. Therefore, while significantly improving the precision and life of the bearing, the height of the entire rotating head drum device can be significantly reduced, making it possible to significantly reduce the size and thickness of the entire device. It is possible to significantly reduce the size and thickness of the video tape recorder used.

Moreover, according to the present invention, the rotor yoke can be attached to the rotating drum using the attraction force of the rotor magnet, so if the rotor yoke is fitted into the notch of the rotating drum as in the embodiment, special It is possible to significantly reduce the number of parts and improve the space factor without requiring any holding parts.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment in which the present invention is applied to a rad drum device for rotating a video tape recorder. FIG. 2 is a longitudinal cross-sectional view of an example of a prior study of a rotary head drum device studied in the course of the present invention. In addition, in the symbols used in the drawings, 21・-・−・−・−・・−・−Fixed drum 22・・−
・・−−−1−−−−−−−Fixed shaft 23−−−−−−・
・・−・−・・・・・・Bearing 24−・−・−−
m-------1- Bearing 25------
・・−・−・−・Rotating drum 26・−・・−・−・−・
・−・Magnetic head 30−・−・−・−−−−−−−−
---Motor 31------------------------ than than 1 than more cylindrical portion 32-------------111 circular recessed portion 33--
−・・−−−−1−−−−−・−・Rotor magnet 3
4--・----------・-- Magnet case 36------------- Stator coil 42--・・・・・−・・・Rotor yoke 42a・・・・・・・・・・・Outer peripheral part 43−・・・・・・・・・・・・・Notch part It is.

Claims (1)

[Claims] A rotating drum that has a magnetic head and is rotatably supported by a fixed shaft via a bearing, a stator coil that is horizontally attached to the fixed shaft, and the rotating drum that faces each other with the stator coil in between. A rotary head drum device comprising a rotor magnet and a rotor yoke attached to the rotor, and configured to rotationally drive the rotary drum by a motor made up of the stator coil, rotor magnet, and rotor yoke.