JPH09106522A - Rotary cylinder device and recording or reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary cylinder device having superior performance and high reliability, and capable of being effectively made into high density. SOLUTION: This rotary cylinder 3 provided with a magnetic head 12 at the specified position and a fixed cylinder 2 for guiding and running a magnetic tape are coaxially arranged through a center shaft 1. A magnetic fluid bearing constituted so that a bearing part 5 is arranged so as to be engaged with the center shaft 1 by sticking the magnetic fluid on the surface of the center shaft 1 is provided. A motor part for rotationally driving the rotary cylinder 3 is mounted at the position closest to the bearing part 5 through a mounting bush 4 formed with magnetic material to magnetize the center shaft 1 by the mounting bush 4. The mounting bush 4 is molded so as to be positioned at the center of a rotor yoke of the motor part by an outsert molding using a resin material into which a magnetic body is added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording or reproducing apparatus such as a video tape recorder (VTR), and more particularly to a rotary cylinder for recording or reproducing information on a magnetic tape pulled out from a cassette. It relates to the device.

[0002]

2. Description of the Related Art Conventionally, as a rotary cylinder device used for a VTR or the like, a rotary shaft is arranged at the center and the rotary shaft is arranged at the center of the rotary shaft, as disclosed in Japanese Unexamined Patent Publication No. 56-165926. It is known that bearings are provided by two ball bearings, and a motor for driving a cylinder to rotate is directly connected to a rotary shaft. In this apparatus, a rotary cylinder is arranged at the end opposite to the rotary shaft via a ball bearing, and a magnetic head is fixed to the rotary cylinder to drive the rotary drive.

However, in recent years, along with recording or reproducing at high density and high frequency such as digital VTR, the number of revolutions of the cylinder device is increased to cope with higher density. For this reason, in the rotary cylinder device having the conventional ball bearing bearing structure as described above, there is a problem that vibration and noise increase.

Therefore, for example, JP-A-61-241519
"Hydraulic fluid bearing" described in Japanese Patent Laid-Open No. 61-
Attention has been paid to a hydrodynamic bearing such as the "rotary drum device" described in Japanese Patent No. 126624. These hydrodynamic bearings make the shaft and sleeve in a non-contact state to significantly reduce noise and vibration during high-speed rotation.The dynamic pressure generating groove between the shaft and the sleeve, or between the shaft end and thrust. Lubricating oil is retained between the bearings so that the shaft and sleeve do not come into contact with each other due to the pumping action during rotation.

[0005]

However, in this type of hydrodynamic bearing, the viscosity of the lubricating oil is a particular problem. In other words, it is necessary to reduce the power consumption in view of the downsizing of the VTR and the limited power supply capacity of the VTR integrated with the camera. Then, in order to suppress the power consumption, there is a tendency to use a material having a viscosity as low as possible. When such a low-viscosity lubricating oil is used, the lubricating oil easily leaks from the hydrodynamic bearing, flows out, or evaporates.
Therefore, the conventional rotary cylinder device has been demanded to have high reliability without such inconvenience.

In view of such circumstances, it is an object of the present invention to provide a rotary cylinder device which can effectively cope with high density and the like, exhibits excellent performance, and has high reliability.

[0007]

In the rotary cylinder device of the present invention, a rotary cylinder having a magnetic head at a predetermined position and a fixed cylinder for guiding and running a magnetic tape are coaxially arranged via a central axis. In the rotary cylinder device, a magnetic fluid bearing is formed by depositing a magnetic fluid on the surface of the central shaft and arranging a bearing portion so as to fit with the central shaft. It is mounted at a position close to the bearing portion via a mounting bush made of a material, and the central shaft is magnetized by the mounting bush.

Further, in the rotary cylinder device of the present invention, the mounting bush is outsert-molded using a resin material mixed with a magnetic material so as to be positioned at the center of the rotor yoke of the motor section. By press-fitting into the central axis, the central axis is magnetized.

Further, in the rotary cylinder device of the present invention, the mounting bush is magnetized at the same time when the drive magnet mounted on the rotor yoke is magnetized.

In the rotary cylinder device of the present invention, a spiral groove is provided on the outer peripheral portion of the mounting bush on the bearing portion side, and when the rotary cylinder rotates, the magnetic fluid flows along the groove along the bearing portion. It is designed to move to the side.

[0011]

According to the present invention, there is provided a magnetic fluid bearing in which a magnetic fluid is attached to the surface of the central shaft and a bearing portion is arranged so as to be fitted with the central shaft, that is, magnetic fluid is used as lubricating oil. The magnetic fluid is adhered and held on the surface of the central shaft to generate dynamic pressure during rotation. By arranging magnetizing magnets above and below the bearing portion, the rotary shaft is magnetized, and a small-sized dynamic pressure bearing having high reliability capable of preventing leakage of the magnetic fluid is configured.

In particular, the magnet for magnetization on the side of the motor section is constituted by a mounting bush of the motor section, and this mounting bush is outsert-molded to the rotor yoke of the motor section. As a result, the magnetic field of the drive magnet of the motor section is not affected and a highly reliable small dynamic pressure bearing can be realized. In this case, the magnetizing magnet is also used as the mounting bush to reduce the number of parts. Further, by disposing the magnetizing magnet in the bearing portion on the side opposite to the motor portion on the central axis, leakage of the magnetic fluid is prevented on both upper and lower sides, and reliability is improved. Further, by providing the spiral groove on the outer peripheral portion of the mounting bush, even if the magnetic fluid leaks, it can be drawn into the bearing portion again.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a rotary cylinder device according to the present invention will be described below with reference to FIGS. Here, first, an example of the overall configuration of a recording or reproducing apparatus including the rotary cylinder device of the present invention will be described. 1 and 2
In the recording / reproducing apparatus 100, the cylinder apparatus 1
01 is provided. The cylinder device 101 is arranged at a predetermined position on the main chassis 102, while being slidable with respect to the main chassis 102 (see double arrow in FIG. 1).
A tape reel or the like is arranged on the slide chassis 103 configured as described above. That is, in this example, the main chassis 1
02 and the slide chassis 103 are separate structures, and the tape cassette 200 mounted on the slide chassis 103 (cassette mounting member) is moved back and forth with respect to the cylinder device 101 (the states shown in FIGS. 1 and 2 correspond to each other. ) Is a configuration.

Further, the recording or reproducing apparatus 100 has a capstan 104, a capstan motor 105, a tape guide member 106 for pulling out a tape on the tape entrance side with respect to the cylinder apparatus 101, and a tape withdrawing side on the tape exit side for the cylinder apparatus 101. The tape guide member 107 and the like are provided.

As shown in FIG. 1, the tape loading operation in the recording / reproducing apparatus 100 is performed after the tape cassette 200 is mounted on the slide chassis 103, and then the tape guide members 106 and 107 are used to magnetically insert the tape cassette 200 from the opening 200a of the tape cassette 200. At the same time as the tape 201 is pulled out, the slide chassis 103 slides toward the cylinder device 101. Then, as shown in FIG.
The magnetic tape 201 is arranged in the cylinder device 101 by the tape guide members 106 and 107.
Wrapped around the circumference of. Thus, according to this recording / reproducing apparatus 100, recording / reproducing can be performed by causing the magnetic tape 201 to travel along a predetermined tape path.

Now, the detailed structure of the cylinder device 101 used in the recording or reproducing apparatus 100 according to the present invention outlined above will be described. FIG. 3 is a sectional view of the cylinder device 101 according to the first embodiment of the present invention. In the figure, 1 is a central axis formed of a magnetic material, and 2 is a fixed cylinder. Reference numeral 3 is a rotary cylinder, and the rotary cylinder 3 is fixed to the central shaft 1 by press fitting, bonding, screwing or the like. A bearing 5 is provided at the center of the fixed cylinder 2.
Is press-fitted, and the rotary cylinder 3 is inserted through the bearing 5.
Is supported on the rotation axis. The bearing 5 is made of sintered metal or brass, and a predetermined groove groove is formed on the fitting surface with the central shaft 1. Fluid pressure is generated at the time of rotation by the oil poured into the gap between the bearing 5 and the central shaft 1, whereby rigidity as a bearing is generated and a dynamic pressure bearing is obtained.

Reference numeral 6 is a leak preventing metal formed of sintered metal for preventing oil leak. The gap of the leak preventive metal 6 is coarser than the gap of the bearing 5,
When dynamic pressure is generated, sufficient oil can be supplied to the dynamic pressure generator. On the other hand, when stopped, it has a mechanism that sucks in and retains excess oil. Also, 7 is the upper and lower bearings 5.
A spacer placed between the bearings and sets the spacing of the bearings 5.

Reference numeral 8 is a thrust bearing that receives a load in the thrust direction. As the material of the thrust bearing 8, it is preferable to use steel or SUS material having high hardness by quenching or nitriding to increase the surface hardness. An end surface (lower end portion) of the central shaft 1 opposite to the mounting portion of the rotary cylinder 3 is formed as a projecting curved surface (a spherical surface is preferable) so as to make point contact with the thrust bearing 8. It is designed to reduce loss.

A magnetic head 12 is fixed to the rotary cylinder 3 via a head base 11 by a screw 13 so as to be arranged at a predetermined height position. Reference numeral 14 is a bending screw for adjusting the mutual heights of the plurality of magnetic heads 12. 9 and 10 are a magnetic head 12 and a lead wire 1.
These are rotary transformers for exchanging signals with the signal processing board connected to 9, and are coaxially arranged on the rotating side (rotating cylinder 3) and the fixed side (fixed cylinder 2), respectively.

The motor unit for driving the rotary cylinder 3 is arranged below the fixed cylinder 2, that is, 1
Reference numeral 7 denotes a disk-shaped and multi-pole magnetized drive magnet, and a rotor yoke 18 is fixed to the central shaft 1 via a mounting bush 4 by press fitting or adhesion. The drive coil 16 faces the drive magnet 17 and
A plurality of them are arranged on the 5 at predetermined positions. Reference numeral 20 is a wiring board of the motor, and the drive magnet 17 is rotated by supplying an electric current to the drive coil 16 at a predetermined timing, and the rotary cylinder 3 is rotationally driven.

Here, the mounting bush 4 is a plastic magnet molded (so-called outsert molding) from a resin mixed with ferrite powder which is a magnetic material,
When the drive magnet 17 is magnetized in multiple poles, it is magnetized and magnetized at the same time. The central shaft 1 is magnetized by press-fitting the mounting bush 4 into the central shaft 1. As a result, the magnetic fluid in which the magnet particles are dispersed is used as the oil flowing into the bearing 5, so that the magnetic fluid is always distributed on the surface of the central shaft 1.

Further, as shown in FIG. 4, a spiral groove 4a is formed on the outer peripheral portion of the mounting bush 4 on the bearing 5 side. By forming such a groove 4a,
Even if the magnetic fluid oozes out due to temperature expansion or the like, the magnetic fluid that oozes out can be returned to the inside of the bearing 5 along the groove 4a by the rotation of the mounting bush 4.

In the cylinder device 101 according to the present embodiment, the central axis 1 is magnetized by the mounting bush 4 arranged in the vicinity of the bearing 5, so that the original function of the hydrodynamic bearing using magnetic fluid is effectively exhibited. After that, the ability to retain the magnetic fluid can be improved and the leakage can be surely prevented. Further, the spiral groove 4a of the mounting bush 4 can also effectively prevent the magnetic fluid from leaking out of the device. Further, since the rotor yoke 18 is arranged so as to shield the magnetic field of the drive magnet 17 via the mounting bush 4, the magnetic fluid, which is lubricating oil, is not affected.

FIG. 5 shows a cylinder device 101 according to the present invention.
2 shows a second embodiment of the present invention. In FIG. 5, the same members as those in the first embodiment are designated by the same reference numerals. In the second embodiment, the magnet 21 for magnetizing is further added between the rotary cylinder 3 and the upper end of the hydrodynamic bearing portion, that is, the upper portion of the leak prevention metal 6 on the upper side. Other configurations are substantially the same as those in the first embodiment.

According to the second embodiment, the mounting bush 4 and the magnetizing magnet 21 are used together,
The magnetization distribution with respect to the central axis 1 can be made uniform, and the bearing rigidity balance can be improved. Further, by arranging the magnetizing magnet 21 and the mounting bush 4 on both upper and lower sides of the bearing portion, it is possible to reliably prevent leakage or seepage of the magnetic fluid above and below the bearing portion.
Therefore, even when the cylinder device 101 is turned upside down and left for a long time, there is no fear of leakage of the magnetic fluid, and high reliability can be realized.

[0026]

As described above, according to the present invention, a magnetic fluid is used as an oil for generating a dynamic pressure in a device of this type having a hydrodynamic bearing, and a magnet for magnetizing a central axis is used as a motor. Since it is configured with the mounting bush of, a low-cost and highly reliable small dynamic fluid bearing can be realized. In addition, the mounting bush is formed of a plastic magnet, and a spiral groove is provided on the outer periphery of the mounting bush, so that not only leakage of magnetic fluid is prevented but also magnetic fluid that has leaked temporarily is drawn into the bearing portion again. It has advantages such as being able to.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of the overall configuration of a recording or reproducing device equipped with a rotary cylinder device of the present invention.

FIG. 2 is a plan view showing an example of the overall configuration of a recording or reproducing apparatus equipped with the rotary drum device of the present invention.

FIG. 3 is a sectional view of the rotary cylinder device according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration example of a mounting bush of a motor unit according to the rotary cylinder device of the present invention.

FIG. 5 is a sectional view of a rotating cylinder device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 center axis 2 fixed cylinder 3 rotating cylinder 4 mounting bush 5 bearing 6 leakproof metal 7 spacer 8 thrust bearing 9,10 rotary transformer 11 head base 12 magnetic head 14 bending coil 16 drive coil 17 drive magnet 18 rotor yoke 20 wiring board 21 Magnet for magnetization

Claims (5)

[Claims] 1. A rotary cylinder provided with a magnetic head at a predetermined position and a fixed cylinder for guiding and running a magnetic tape,
A rotary cylinder device that is coaxially arranged via a central axis, wherein a magnetic fluid is attached to the surface of the central axis, and a magnetic fluid bearing is provided in which a bearing portion is arranged so as to fit with the central axis. The rotary cylinder is characterized in that the rotation driving motor part of the rotary cylinder is mounted at a position close to the bearing part via a mounting bush formed of a magnetic material, and the central axis is magnetized by the mounting bush. apparatus. 2. The mounting bush is outsert-molded using a resin material mixed with a magnetic material so as to be positioned at the center of a rotor yoke of the motor section, and the mounting bush is press-fitted into the central shaft, The rotary cylinder device according to claim 1, wherein the central axis is magnetized. 3. The rotary cylinder device according to claim 2, wherein the mounting bush is magnetized at the same time when the drive magnet mounted on the rotor yoke is magnetized. 4. A spiral groove is provided in an outer peripheral portion of the mounting bush on the bearing portion side, and when the rotary cylinder rotates,
The rotating cylinder device according to claim 1, wherein the magnetic fluid moves along the groove toward the bearing portion. 5. A rotary cylinder device according to any one of claims 1 to 4, which has a head for recording or reproducing information on a magnetic tape, and a cassette for accommodating the magnetic tape. A cassette mounting member that supports the cassette so that the cassette can move forward and backward with respect to the rotary cylinder device; and a tape guide member that pulls out the magnetic tape from the cassette and causes the magnetic tape to run along a predetermined tape path, A recording or reproducing apparatus comprising: