JPH06162459A - Rotary cylinder device - Google Patents

Abstract

PURPOSE:To make smaller the difference of a bearing wearing loss in a fluid bearing, which is caused by the difference of temp. and the number of revolution. CONSTITUTION:The fluid bearing is constituted of a shaft 2, a thrust plate 4, a sleeve 4 and a lubricant 5. Electric power generated by a frequency generator 11 is converted into heat by a heating element 14. Controllers 15 and 16 control the connection of the frequency generator 11 to the heating element 14 by the signals of both temp. sensor 12 and a rotation number detecting device 13. Thus, an effect for reducing the bearing wearing loss is specifically large. Electric power generated by the frequency generator 11 only when temp. is low and the number of rotation is high is converted into heat by the heating element 14 so that the temp. of the lubricant 5 is made to increase and the bearing wearing loss is reduced. Then, the bearing wearing loss owing to the difference the temp. and the number of rotation, that is, the difference of motor load current, is reduced. Therefore, the power consumption of VTR is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary cylinder device for recording / reproducing using a magnetic head such as a VTR, and more particularly to reduction of bearing friction loss of a fluid bearing used as a bearing.

[0002]

2. Description of the Related Art In recent years, digital VTRs and VTRs for high-definition televisions (for example, high-definition televisions) whose image quality has been remarkably improved as compared with the current television system, high-density recording, high-rate recording / reproducing The demand for equipment has increased. In an apparatus for recording / reproducing information on / from a magnetic tape by such a rotary magnetic head, how to improve the recording density in order to record a large amount of information in a limited space of the magnetic tape is an issue. ing. One of the countermeasures is to narrow the tracks recorded on the magnetic tape. Further, since the frequency band of the signal to be recorded is widened and the recording wavelength is shortened, it is necessary to increase the rotation speed of the rotary cylinder. However, when the track is narrowed, there arises a problem that the magnetic head cannot accurately trace the track at the time of reproducing the signal, and the rotation noise of the bearing becomes loud due to the rotation of the rotary cylinder. Therefore, a fluid bearing, which has a higher rotational accuracy than the ball bearing and produces less rotational noise, is used as a bearing in a rotary cylinder device.

An example of a conventional rotary cylinder device using a fluid bearing will be described below with reference to the drawings.
(FIG. 6) is a vertical cross-sectional view of the rotary cylinder device, and (FIG. 7) is a diagram showing the relationship between temperature, rotation speed, and motor load current.

Reference numeral 1 denotes a fixed cylinder for guiding a magnetic tape (not shown), 2 denotes a herringbone type groove 2c, which is processed by etching or the like at two locations on the upper and lower outer peripheral surfaces 2a in the axial direction, and an upper end surface 2b. Is a fixed shaft that is press-fitted and fixed in the center of the fixed drum 1. Reference numeral 3 denotes a sleeve, which is rotatable coaxially with the fixed shaft 2 and has a bearing surface 3a facing the herringbone type groove 2c on its inner peripheral surface and is held by a disk 6. A thrust plate 4 has a spiral groove 4b on a lower end surface 4a, is fixed to the upper end surface 3b of the sleeve 3 with a screw, and faces the upper end surface 2b of the fixed shaft 2. 5 is a herringbone type groove 2
c, a minute gap between the bearing surface 3a, and the upper end surface 2 of the fixed shaft 2.
It is a lubricant that intervenes in a minute gap between the groove b and the spiral groove 4b. Reference numeral 7 denotes a rotary cylinder which is coaxially fitted to the disk 6 and screwed thereto, and 8 denotes a magnetic head which is screwed and fixed to the rotary cylinder 7. Reference numerals 9a and 9b are rotary transformers for transmitting signals in a non-contact manner, and 10 is a motor including a magnet 10a fixed to the disk 6 and a coil 10b fixed to the fixed cylinder 1.

The operation of the rotary magnetic head device constructed as above will be described below.

When a current flows through the motor coil 10b and the rotating portion including the sleeve 3 rotates, the radial action of the radial bearing formed by the herringbone type groove 2c, the bearing surface 3a and the lubricant 5 causes the centripetal force of the rotating portion. Is maintained. Further, by the pumping action of the thrust bearing constituted by the thrust groove 4b, the upper end surface 2b of the fixed shaft 2 and the lubricant 5, a stable floating position of the rotating portion is obtained and normal rotation is maintained.

[0007]

However, the following problems occur in the above configuration. That is, in the rotary cylinder device as described above, as shown in (FIG. 7), when the temperature becomes low near 0 ° C., the viscosity of the lubricant 5 becomes extremely large as compared with that near 20 ° C., so that the bearing friction loss during rotation becomes large. Grows larger. As a result, the motor load current flowing through the motor also increases. As a countermeasure against this, it is possible to use a lubricant having a low viscosity for rotation, but at that time, the bearing rigidity becomes low at a high temperature such as 60 ° C., and normal rotation cannot be obtained.

Further, in recent years, in order to record signals in different frequency bands with one VTR, a rotary cylinder device having a plurality of rotation speeds has been required. Since the bearing friction loss increases in proportion to the rotation speed, it increases further when the rotation speed is high. For example, the rotation speed is 36
The bearing friction loss at 00 rpm is 1800 rpm.
1800 rpm because it is twice as large as when m
There is a very large difference between 60 ° C. and 0 ° C. at 3600 rpm. Also, in order to maintain the bearing rigidity, the specifications of the bearing are usually determined based on the low speed rotation.Therefore, if the specifications of the bearing are decided according to the high rotation speed to reduce the friction loss of the bearing, on the contrary, at the low speed rotation, The bearing rigidity becomes low and normal rotation cannot be obtained. Therefore, there is a problem that a large difference occurs in bearing friction loss due to a difference in temperature and the number of revolutions, resulting in an increase in power consumption of the VTR.

In view of the above problems, the present invention is to provide a rotary cylinder device using a fluid bearing in which a large difference in bearing friction loss does not occur even if the temperature and the rotational speed change.

[0010]

In order to solve the above-mentioned problems, a rotary cylinder device according to a first aspect of the present invention includes a fixed cylinder for guiding a magnetic tape, a shaft, a sleeve, and an end surface of the sleeve which is in contact with the end surface of the shaft. A thrust plate fixed to
A spiral groove provided on either the shaft end surface or the abutment surface of the thrust plate, and a herringbone groove provided on either the inner peripheral surface of the sleeve or the outer peripheral surface of the shaft, and a fluid bearing made of a lubricant. , A rotary cylinder that is equipped with a magnetic head and is rotated by a motor through a fluid bearing about a shaft with respect to a fixed cylinder,
A frequency generator that generates electric power by rotating a rotating cylinder, a heating element that converts the electric power generated by the frequency generator into heat, a current value detection unit that detects temperature, and a frequency generator based on the signal of the temperature detection unit. And a control means for controlling connection with the heating element.

The rotary cylinder device according to the second aspect of the invention comprises a fixed cylinder for guiding the magnetic tape, a shaft, a sleeve, a thrust plate abutting against the end face of the shaft and fixed to the end face of the sleeve, a shaft end face or thrust. The spiral groove provided on either one of the contact surfaces of the plate and the herringbone type groove provided on either the inner peripheral surface of the sleeve or the outer peripheral surface of the shaft and the fluid bearing made of a lubricant, and the magnetic head A rotating cylinder that is mounted and is rotated by a motor through a fluid bearing around a shaft at multiple rotations with respect to a fixed cylinder, a frequency generator that generates electric power by rotation of the rotating cylinder, and a frequency generator. A heating element for converting electric power into heat, a rotation speed detecting means for detecting the rotation speed of the motor, and a frequency generator by a signal from the rotation speed detecting means. It is obtained by a configuration and control means for controlling the connection between the thermal element.

[0012]

In the first and second aspects of the invention, as described above, the effect of reducing bearing friction loss is great, the electric power generated by the frequency generator is converted into heat by the heating element only when the temperature is low and the rotation speed is high. By increasing the temperature of the lubricant to reduce the bearing friction loss, it is possible to reduce the bearing friction loss due to the difference between the temperature and the rotation speed, that is, the difference in the motor load current.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The rotary cylinder device of the first and second inventions will be described below in order with reference to the following drawings.

(FIG. 1) shows the first aspect of the first and second inventions.
2 is a vertical cross-sectional view of a rotary cylinder device according to the first embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of the rotary cylinder device according to the second embodiment of the first and second inventions, and FIG. FIG. 4 is a longitudinal sectional view of a rotary cylinder device according to a third embodiment of the invention, FIG. 4 is a diagram showing a relationship between temperature and motor load current of the rotary cylinder device of the first invention, and FIG. It is a figure which shows the relationship of the temperature of the rotary cylinder apparatus of 2nd invention, a rotation speed, and a motor load current.

First, the first invention will be described. Reference numeral 1 is a fixed drum which guides a magnetic tape (not shown), holds a sleeve 3 at the center, and has a bearing surface 3a and a bottom surface 3b at two positions above and below the inner peripheral surface. 2 is fixed to the disk 6 coaxially and is rotatable coaxially with the bearing surface 1a of the fixed drum 1,
It is a rotating shaft having a herringbone type groove 2c facing the bearing surface 3a and a lower end surface 2b on the outer peripheral surface. Reference numeral 4 is a thrust plate having a spiral groove 4b on the upper end surface 4a thereof, fixed to the lower end surface 3b of the sleeve 3 with a screw, and opposed to the lower end surface 2b of the rotary shaft 2. A lubricant 5 is present in a minute gap between the herringbone type groove 2c and the bearing surface 3a and a minute gap between the lower end surface 2b of the rotary shaft 2 and the spiral groove 4b. 7 is a rotary cylinder which is coaxially fitted to the disk 6 and screwed, and 8 is a rotary cylinder 7.
It is a magnetic head fixed with screws. Reference numerals 9a and 9b are rotary transformers for transmitting signals in a non-contact manner, and 10 is a motor including a magnet 10a fixed to the disk 6 and a coil 10b fixed to the fixed cylinder 1. 1
Reference numeral 1a is a power generation magnet provided on the rotating disk 6, and 11b is a power generation coil provided on the fixed cylinder 1, which constitutes the frequency generator 11. A temperature sensor 12 detects the temperature of the thermistor. 14
Is a heating element, such as a nichrome wire, which is connected to the power-generating coil 11 and generates heat when an electric current is applied, and is installed on the thrust plate 4 so that the heat can be easily transferred to the lubricant 5. Reference numeral 15 is a control device for controlling the connection between the frequency generator 11 and the heating element 14 by the signal of the temperature sensor 12.

The operation of the rotary cylinder device configured as described above will be described with reference to the drawings.

When an electric current flows through the motor coil 10b and the rotating portion rotates, the centripetality of the rotating portion is maintained by the pumping action of the radial bearing composed of the herringbone type groove 2a, the bearing surface 3a and the lubricant 5. . Further, due to the pumping action of the thrust bearing constituted by the thrust groove 4b, the lower end surface 2b of the rotating shaft 2 and the lubricant 5, a stable floating position of the rotating portion is obtained and normal rotation is maintained. Further, the rotation of the rotating portion causes the frequency generator 11 to generate electric power. Although the generated electric power causes heat to be generated from the heating element 14, the control device 15 connects to the frequency generator 11 based on the signal from the temperature sensor 12 only when the temperature is low. Therefore, at a low temperature where the bearing friction loss rapidly decreases with a slight temperature rise, the heating element 14
The temperature of the thrust plate 4 and the temperature of the lubricant 5 are also increased by the heat of, so that the viscosity of the lubricant is reduced. However, since the control device 15 does not generate heat in the heating element 14 at high temperature, the viscosity of the lubricant 5 does not decrease, and the problem that the bearing rigidity becomes weak and stable rotation does not occur. Therefore, as shown by the solid line in (FIG. 4), the bearing friction loss at a low temperature, that is, the motor load current, which is particularly large, is effectively improved, and the difference due to temperature can be reduced.

Next, the rotary cylinder device of the second invention will be described. The same reference numerals are given to those described in the first invention, and the description thereof will be omitted.

Reference numeral 16 is a control device for controlling the connection between the frequency generator 11 and the heating element 14 by a signal from the rotation speed detection device 13.

When an electric current flows through the motor coil 10b and the rotating part rotates, the centripetal property of the rotating part is maintained by the pumping action of the radial bearing composed of the herringbone type groove 2a, the bearing surface 3a and the lubricant 5. . Further, due to the pumping action of the thrust bearing constituted by the thrust groove 4b, the lower end surface 2b of the rotating shaft 2 and the lubricant 5, a stable floating position of the rotating portion is obtained and normal rotation is maintained. Further, the rotation of the rotating portion causes the frequency generator 11 to generate electric power. The generated electric power causes heat to be generated from the heating element 14, but the control device 16 connects to the frequency generator 11 only when the rotation speed of the motor 10 is high. Therefore, at the time of high speed rotation in which the bearing friction loss sharply decreases with a slight temperature rise, the temperature of the thrust plate 4 and the lubricant 5 also rises due to the heat of the heating element 14, so the viscosity of the lubricant decreases. However, when the rotation speed is low, the control device 16 does not generate heat in the heating element 14, so that the viscosity of the lubricant 5 does not decrease, and the bearing rigidity becomes low at low speed rotation, and stable rotation does not occur. No problem occurs. Therefore, as shown by the solid line in (FIG. 5), the bearing friction loss at the time of particularly high speed rotation, that is, the motor load current is effectively improved, so that the difference due to the rotational speed can be reduced.

In the second embodiment of the first and second inventions, the heating element 14 is provided in the sleeve 3 instead of the thrust plate 4, and the heating element 14 is lubricated as in the first embodiment. Since it can be installed near 5, it is efficient.

In the third embodiment of the first and second inventions, the rotation system of the hydrodynamic bearing is fixed to the shaft as in the conventional embodiment. However, in the place where the temperature of the lubricant 5 rises. Heating element 1
If 4 is installed, the same effect as in the first and second embodiments can be obtained.

In this embodiment, the heating element 14 is provided with a nichrome wire, but any other material may be used as long as it generates heat. In addition, the power generation magnet 11a
Although it is newly provided, there is no problem even if it is also used as the motor magnet 10a.

[0024]

As described above, according to the first aspect of the invention, the fixed cylinder for guiding the magnetic tape, the shaft, the sleeve, the thrust plate abutting against the end surface of the shaft and fixed to the end surface of the sleeve, the shaft end surface or A spiral groove provided on one of the contact surfaces of the thrust plate and a herringbone groove provided on one of the inner peripheral surface of the sleeve or the outer peripheral surface of the shaft and a fluid bearing made of a lubricant,
A rotating cylinder that has a magnetic head and is rotated by a motor around a shaft through a fluid bearing with respect to a fixed cylinder, a frequency generator that generates electric power by the rotation of the rotating cylinder, and an electric power generated by the frequency generator. Bearing friction loss is reduced by providing a heating element that converts into heat, a temperature detecting means that detects the temperature, and a control means that controls the connection between the frequency generator and the heating element by the signal of the temperature detecting means. The effect is particularly large, and the temperature of the lubricant can be raised by the heat of the heating element only when the temperature is particularly low, and the difference in bearing friction loss due to the temperature becomes small.

A second invention is directed to a fixed cylinder for guiding the magnetic tape, a shaft, a sleeve, a thrust plate abutting against the end face of the shaft and fixed to the end face of the sleeve, and abutting of the shaft end face or the thrust plate. A spiral groove provided on either one of the surfaces, a herringbone groove provided on either the inner peripheral surface of the sleeve or the outer peripheral surface of the shaft, and a fluid bearing composed of a lubricant, and a fluid bearing equipped with a magnetic head. A rotating cylinder that is rotated around a shaft by a motor through a motor at multiple rotation speeds, a frequency generator that generates electric power by rotating the rotating cylinder, and the electric power generated by the frequency generator to heat. A heating element for conversion, and a rotation speed detection means for detecting the rotation speed,
Since the control means for controlling the connection between the frequency generator and the heating element is provided by the signal of the rotation speed detecting means, the effect of reducing the bearing friction loss is particularly large, and the heating element of the heating element is reduced only when the rotation speed of the motor is high. The temperature of the lubricant can be raised by the heat, and the bearing friction loss due to the rotational speed, that is, the difference in the motor load current is reduced. Therefore, the power consumption of the VTR can be suppressed even if the temperature or the rotation speed changes.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a rotary cylinder device according to a first embodiment of the first and second inventions.

FIG. 2 is a vertical sectional view of a rotary cylinder device according to a second embodiment of the first and second inventions.

FIG. 3 is a vertical sectional view of a rotary cylinder device according to a third embodiment of the first and second inventions.

FIG. 4 is a diagram showing the relationship between temperature and motor load current in the rotary cylinder device of the first invention.

FIG. 5 is a diagram showing a relationship among temperature, rotation speed, and motor load current in the rotary cylinder device of the second invention.

FIG. 6 is a vertical sectional view of a conventional rotary cylinder device.

FIG. 7 is a diagram showing the relationship between temperature, rotation speed, and motor load current in a conventional rotary cylinder device.

[Explanation of symbols]

 1 Fixed Cylinder 2 Axis 3 Sleeve 3a Herringbone Groove 4 Thrust Plate 4b Spiral Groove 5 Lubricant 7 Rotating Cylinder 11 Frequency Generator 11a Power Generation Magnet 11b Power Generation Coil 12 Temperature Sensor 13 Rotation Detecting Device 14 Heating Element 15, 16 Control device

Claims (6)

[Claims] 1. A fixed cylinder for guiding a magnetic tape, a shaft, a sleeve, a thrust plate abutting against an end face of the shaft and fixed to an end face of the sleeve, and a shaft end face or a contact face of the thrust plate. A spiral groove provided on either one side and a herringbone type groove provided on either the inner peripheral surface of the sleeve or the outer peripheral surface of the shaft and a fluid bearing made of a lubricant, and a magnetic head mounted on the fluid. A rotary cylinder that is rotated about the shaft by a motor via a bearing with respect to the fixed cylinder, a frequency generator that generates electric power by rotation of the rotary cylinder, and the electric power generated by the frequency generator to heat. A heating element to be converted, a temperature detecting means for detecting a temperature, and a contact between the frequency generator and the heating element according to a signal from the temperature detecting means. Rotary cylinder device being characterized in that a control means for controlling. 2. The rotary cylinder device according to claim 1, wherein the frequency generator and the heating element are connected only when the temperature is low. 3. A fixed cylinder for guiding a magnetic tape, a shaft, a sleeve, a thrust plate which is in contact with an end face of the shaft and is fixed to an end face of the sleeve, and a contact face of the shaft end face or the thrust plate. A spiral groove provided on either one side and a herringbone type groove provided on either the inner peripheral surface of the sleeve or the outer peripheral surface of the shaft and a fluid bearing made of a lubricant, and a magnetic head mounted on the fluid. A rotating cylinder that is rotated by a motor through a bearing around the rotating shaft at a plurality of rotation speeds with respect to the fixed cylinder, a frequency generator that generates electric power by rotation of the rotating cylinder, and the frequency generator. A heating element for converting the generated electric power into heat, a rotation speed detecting means for detecting the rotation speed of the motor, and a signal from the rotation speed detecting means. Rotary cylinder device being characterized in that a control means for controlling the connection between the heating element and the frequency generator. 4. The rotary cylinder device according to claim 3, wherein the frequency generator and the heating element are connected only when the rotational speed of the motor is high. 5. The rotary cylinder device according to claim 1, wherein the heating element is provided on the sleeve. 6. The rotary cylinder device according to claim 1, wherein the heating element is provided on the thrust plate.