JP3497366B2 - Laser scanning motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hemispherical bearing device, and more particularly, to a rotating body for rotating a polygonal mirror for deflecting and reflecting a laser beam on an image forming plane at an extremely high speed, and a rotating body for supporting the rotating body. The rotating body supporting member formed with the fluid bearing device is made to have the same magnetic flux density and the same polarity as each other so as to minimize the frictional force between them, and the repulsive force generated cancels out the load on the rotating body. By
The present invention relates to a laser scanning motor in which a rotating body floats above a rotating body supporting means in a short time.

[0002]

2. Description of the Related Art Recently, due to the rapid development of the computer industry, drive motors required for driving various devices, such as laser printer polygon mirror drive devices, hard disk spindle motors, VCR head drive motors, etc. In addition, since more data retrieval, storage, and reproduction are executed in a short time, high precision and ultra-high speed rotation performance without shaft oscillation or vibration are required.

Therefore, along with the development of a drive motor which suppresses the oscillation of the drive motor shaft or the vibration of the shaft to stably rotate at a high speed, various forms of bearing devices which enable the rotation of the motor as described above have been studied. Development is being promoted, and as such a type of bearing device, ultra high speed,
Fluid bearing devices with high precision and excellent stability are widely used.

As the fluid bearing, a journal fluid bearing device having a journal of a shaft or a journal support member for supporting the journal, a hemispherical bearing device for simultaneously supporting a radial load and a thrust load of the shaft, and a hemispherical bearing device. The conical bearing device, which has a similar operation principle but is excellent in processing and mass productivity, is used.

The structure and operation of each of the journal fluid bearing device, the hemispherical bearing device and the conical bearing device will be described below. The journal bearing device includes a shaft having a predetermined diameter, a sleeve that is a first shaft supporting member that supports a radial load of the shaft, and an end portion of the shaft that is inserted into the sleeve to support a thrust load of the shaft. And a thrust bearing which is a second shaft support member having a spiral dynamic pressure generating groove for generating a predetermined fluid pressure so as to overcome a frictional force due to a thrust load generated by the surface contact with the shaft. There is.

Further, a large number of herringbone-shaped dynamic pressure generating grooves are formed at regular intervals on the inner surface of the sleeve which is the first shaft support member or the outer peripheral surface of the shaft facing the sleeve. The radial load of the shaft is supported by the fluid pressure generated by the fluid flowing in a certain direction by the dynamic pressure generation groove, and the friction due to the mutual contact between the shaft and the sleeve is minimized.

The journal fluid bearing device is rotated at a predetermined rotational speed while the angular velocity of the shaft is 0 (zero),
When the fluid pressure generated in the above-mentioned herringbone dynamic pressure generating groove and the spiral dynamic pressure generating groove formed in the thrust bearing becomes larger than the load of the shaft and its own weight, the sleeve and the thrust bearing maintain a gap of several μm. It rotates in a contactless state.

The journal hydrodynamic bearing device requires two dynamic pressure generating grooves, which are separately manufactured to support the radial load and the thrust load, and the two dynamic pressure generating grooves share the thrust load and the radial load, respectively. Therefore, when the magnitude of the thrust load and radial load generated on the shaft changes continuously, it is difficult to deal with the changed load size. By supporting both the thrust load and the thrust load at the same time, a hemispherical bearing device that can easily correct the thrust load and the radial load even if they are minutely changed,
A conical bearing device is used which is similar to the hemispherical bearing device but is easier and easier to process and manufacture than the hemispherical bearing device.

The hemispherical bearing device has a cylindrical dynamic pressure generating groove formed on a hemispherical surface of a hemispherical dynamic pressure generating member that divides a sphere into two parts to support a radial load and a thrust load at the same time. After the dynamic pressure generating member is brought into close contact with the hemispherical groove having the same tune as the hemispherical surface on both ends of the cylinder and the hemispherical groove on both ends of the bushing in which the shaft holes penetrating the centers of both ends of the cylinder are formed, the fixed shaft is inserted into The two dynamic pressure generating members and the bushing are connected to each other.

At this time, a spacer, which is a gap forming member, is interposed so that a gap of several μm is formed between the hemispherical groove and the dynamic pressure generating member. Further, a motor rotor is attached to the outer peripheral surface of the bushing to form a motor stator fixed to the motor rotor at a predetermined distance. Here, the motor stator and the fixed shaft are installed in a fixed lower housing.

When power is applied to the motor rotor and the motor stator and the motor stator is gradually accelerated from the time when the angular velocity is 0, the two hemispherical grooves formed in the bushing and the hemispherical dynamic pressure generating member are formed. A predetermined fluid pressure is generated in the. When the fluid pressure generated between the lower hemispherical groove and the dynamic pressure generating groove member becomes equal to the dead weight of the rotating body and the acting load, the bushing floats from the dynamic pressure generating member to simultaneously apply the radial load and the thrust load. Super fast rotation while supporting.

In the hemispherical bearing device as described above, since the dynamic pressure generating member has a hemispherical shape, it takes a long time to process the dynamic pressure generating member, and a repetitive process step is required. Therefore, in order to remove the defect, a hemispherical dynamic pressure generating member is used in a dynamic pressure generating member in which a spiral dynamic pressure generating groove is formed on a conical tapered surface having a trapezoidal cross section, and the conical dynamic pressure generating member is used. The same operation as the hemispherical bearing device can be obtained by using a conical bearing device in which the pressure generating member and the bushing, which are in an inverted shape, are face-to-face coupled.

[0013]

However, the polygonal mirror mounted on the laser scanning motor to which the conventional journal fluid bearing device, hemispherical bearing device, and conical bearing device as described above are respectively installed exerts a unique function. In order to lift the rotary member from the friction surface, the rotary member equipped with the polygonal mirror must float above the friction surface and rotate without contact. Takes a certain amount of time from when the angular velocity is 0 to rotate at a constant speed, and wears and wears due to friction during contact between the rotating body and the friction surface, resulting in shortened life and various other problems. there were.

Accordingly, the present invention has been devised to solve the above-mentioned problems, and its object is to support a rotating body supporting a polygonal mirror of a laser scanning unit and a friction surface while supporting the rotating body. Rotating performance is improved by forming a magnetic material so that the rotating body supporting members acting on each other repel each other, and canceling the load of the rotating body by the repulsive force to reduce the time when the rotating body rubs against the rotating body supporting member. It is an object of the present invention to provide a laser scanning motor in which the life of the motor is prevented from being shortened by improving

[0015]

According to a feature of the present invention for achieving the above object, an upper bearing bracket, a lower bearing bracket coupled to the upper bearing bracket and having a stator and a sleeve fixedly installed therein,
A rotor having a rotor and a polygon mirror attached to the stator, and one end of which is coupled to the center of rotation of the rotor and inserted into a sleeve to form a first dynamic pressure generating groove on the circumferential surface. A laser scanning motor including a shaft and magnetic levitation means formed between the rotary shaft and a lower bearing bracket portion facing the rotary shaft is disclosed.

Preferably, the magnetic levitation means has a first magnetic body attached to the other end of the rotary shaft and a magnetic pole identical to the first magnetic body on the lower bearing bracket portion facing the first magnetic body. A second magnetic body having a second dynamic pressure generation groove formed so as to be opposed to each other. Further, the magnetic levitation means is arranged such that the third magnetic body attached to the center of rotation of the upper portion of the rotating body and the same magnetic pole as the third magnetic body face the upper bearing bracket portion facing the third magnetic body. And a fourth magnetic body attached to the first and second magnetic bodies, and the third and fourth magnetic bodies have the same magnetic flux density.

The magnetic levitation means is attached to the rotating shaft made of a magnetic material and the lower bearing bracket portion facing the rotating shaft so that the same magnetic poles as the rotating shaft face each other, and the second dynamic pressure generating groove is formed. A second magnetic body in which is formed. According to another aspect of the present invention, there is provided a laser scanning motor including an upper bearing bracket, a lower bearing bracket fixed to a stator by being coupled to the upper bearing bracket, and a rotor having a rotor and a polygon mirror facing the stator. And a rotor is inserted into a bushing that is rotatably connected to the rotor, and a pair of conical dynamic pressure generators in which a small diameter portion is opposed to each other through a spacer and a dynamic pressure generating groove is formed on the surface. The member includes a fixed shaft to which the member is fixed, and magnetic levitation means formed between the bushing and a lower bearing bracket portion facing the bushing.

Preferably, in the magnetic levitation means, the same magnetic pole as the first magnetic body faces the first magnetic body attached to the lower side surface of the bushing and the lower bearing bracket portion facing the first magnetic body. And a second magnetic body attached so that The magnetic levitation means further includes a third magnetic body attached on the center of rotation of the upper part of the rotating body, and a fourth magnetic body attached so that the same magnetic pole as the third magnetic body faces each other. The first and second magnetic bodies and the third and fourth magnetic bodies each have the same magnetic flux density.

On the other hand, the magnetic levitation means according to the present invention includes a bushing made of a magnetic material, and a second magnetic material attached to the lower bearing bracket portion facing the bushing so that the same magnetic pole as the bushing faces. . According to another aspect of the present invention, an upper bearing bracket, a lower bearing bracket fixedly installed with the stator coupled to the upper bearing bracket, a rotor facing the stator and having a rotor and a polygon mirror mounted thereon, A pair of hemispherical dynamic pressure generating members, in which a rotating body is rotatably inserted into a bushing connected to the rotating body, arc-shaped portions are opposed to each other with a spacer interposed, and a dynamic pressure generating groove is formed on the surface. The member includes a fixed shaft to which the member is fixed, and magnetic levitation means formed between the bushing and a lower bearing bracket facing the bushing.

Preferably, in the magnetic levitation means, the same magnetic pole as the first magnetic body faces the first magnetic body attached to the lower side surface of the bushing, and the lower bearing bracket portion facing the first magnetic body. And a second magnetic body attached so that Further, the magnetic levitation means is configured such that the third magnetic body attached to the center of rotation of the upper portion of the rotating body and the same magnetic pole as the third magnetic body face the upper bearing bracket portion facing the third magnetic body. And a fourth magnetic body attached to the first magnetic body, the third magnetic body and the fourth magnetic body having the same magnetic flux density.

The above-mentioned magnetic levitation means includes a bushing made of a magnetic material, and a second magnetic material attached to a lower bearing bracket portion facing the bushing so that the same magnetic pole as the bushing faces.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Figure 1
FIG. 3 is a sectional view showing a laser scanning motor to which a journal bearing device according to the present invention is applied. As shown in the drawing, a bushing portion 25 supporting the shaft 30 is provided on the inner surface of the sleeve 20 having a through hole into which the shaft 30 is inserted.
Of the shaft 30 facing the bushing portion 25 and the bushing portion 25, the first movement of the herringbone shape for generating fluid pressure for rotating the bushing portion 25 and the shaft 30 in a non-contact manner on either side. The pressure generator 35 is formed.

When the groove area and the number of the first dynamic pressure generating portions 35 are determined according to the weight and load applied to the shaft 30, the sleeve 20 into which the shaft 30 is inserted is fastened to the lower bearing bracket 70. The upper bearing bracket 75 is fixed to the lower bearing bracket 70 by being fixed by a screw or the like. Meanwhile, the sleeve 20
A thrust bearing 50 having a herringbone or spiral-shaped second dynamic pressure generating portion 50a for supporting the thrust load of the shaft 30 and levitating the shaft 30 is fixed to the bottom surface of the through hole by a fastening screw or the like. Supports one end of the shaft 30.

Further, a hub 60 is press-fitted onto the shaft 30 in order to rotate the shaft 30 at a predetermined number of revolutions, and the rotor 60 and the polygon mirror for deflecting the laser beam to the photosensitive drum, which is an image forming surface, are fitted to the hub 60. 10 are installed. The sleeve 2
The thrust bearing 50 attached to the bottom surface of the through hole of No. 0 and having the second dynamic pressure generating portion 50a is formed of the first permanent magnet 100 having a predetermined magnetic flux density.
Shaft 3 in contact with thrust bearing 50 which is 00
A second permanent magnet 150 having the same magnetic flux density as the first permanent magnet 100 and a predetermined thickness equal to the diameter of the shaft 30 is attached and formed at the end portion of 0.

Here, the entire shaft 30 is replaced by the second permanent magnet 150.
And the second dynamic pressure generating portion 5 facing the shaft 30.
It is also possible to attach the thrust bearing 50 formed with 0a. Also in this case, the second permanent magnet 150 and the first permanent magnet 100 need to be designed to have the same magnetic flux density. The operation of the journal bearing device using the magnetic material according to the present invention constructed as described above will be described with reference to the accompanying drawings.

First, when power is applied to the rotor 80 and the stator 85 and the rotor 80 starts rotating at a predetermined rotation speed,
First permanent magnet 10 formed on thrust bearing 50
0 and the repulsive force of the second permanent magnet 150 formed on the shaft 30 and the dynamic pressure generated by the spiral-shaped second dynamic pressure generating portion 50a of the thrust bearing 50, the shaft 30 is separated from the thrust bearing 50 by a predetermined distance. It rotates at high speed in the state of being kept.

Here, the repulsive force and dynamic pressure of the first permanent magnet 100 and the second permanent magnet 150 cause the polygonal mirror 10, which is a rotating body,
When the total load of the shaft 30, the hub 60, and the rotor 80 becomes larger, a predetermined gap is always maintained between the shaft 30 and the thrust bearing 50. On the other hand, when the repulsive force becomes smaller than the total load of the rotating body, the shaft 30 is always in contact with the thrust bearing 50 when the shaft 30 does not rotate. However, the total load of the rotating body including the shaft 30 does not rotate. It becomes the load excluding the force offset by the repulsive force in the total load of the body. Therefore, in the state where the total load of the rotating body is reduced in this way, the shaft 30 can be levitated from the thrust bearing 50 even with a low fluid pressure generated from an initial low rotation speed. In this way, the shaft 30 always forms a predetermined space with the thrust bearing 50 depending on the magnitude of the repulsive force between the first permanent magnet 100 and the second permanent magnet 150.

FIG. 2 is a cross-sectional view showing a modification of the embodiment of the present invention. A third permanent magnet 200 having the same diameter as the shaft 30 is attached to the upper end of the shaft 30 into which the polygonal mirror 10 is inserted. The upper bearing bracket 75 is installed at a position spaced apart from the third permanent magnet 200 by a predetermined distance.
A second permanent magnet 150 is formed on the other end of the shaft 30 on which the permanent magnet 250 is formed and the third permanent magnet 200 is formed, that is, on the shaft 30 that is in contact with the thrust bearing 50. The thrust bearing 50 facing the permanent magnet 150 is magnetized by the first permanent magnet 100.

The third permanent magnet 200 and the fourth permanent magnet 2
Reference numeral 50 denotes a gap adjusting permanent magnet for adjusting the gap between the shaft 30 and the thrust bearing 50 generated by the first permanent magnet 100 and the second permanent magnet 150. Here, the first, second, third and fourth permanent magnets all have the same magnetic flux density, and the second permanent magnet 150 and the first permanent magnet 100 among them have a force that repels the shaft 30 upward. , Axis 30
Since the combined force of the dynamic pressure generated in proportion to the rotation of the shaft acts, the shaft 30 is actually applied with the force in the opposite direction of gravity, and the shaft 30 and the thrust bearing 50 are separated by the third and fourth permanent magnets. The gap between them is adjusted.

FIG. 3 is a sectional view showing a laser scanning motor to which the hemispherical bearing device according to the present invention is applied. As shown in the figure, the laser scanning motor to which the hemispherical bearing device is applied is a polygonal polygonal mirror 210 that deflects a laser beam to a photosensitive drum (not shown) that is an image forming surface, and the polygonal mirror 210 with minimum friction. Hemispherical bearing device 220, 230, 235, 240 for super-high speed rotation
A rotor 215 and a stator 255, which are rotational force generating devices that are coupled to the hemispherical bearing device to generate rotational force, a lower bearing bracket 270, and an upper bearing bracket 275.

A through hole having a predetermined diameter is formed in the polygon mirror 210, and a hub 260 is coupled to the through hole.
The hub 260 has two cylinders 260 with two different diameters.
A second cylinder having a large diameter on the other side is formed so that the through hole of the polygonal mirror 210 is inserted into the first cylinder 260a having a small diameter of the two cylinders in which a and 260b are joined. A concave groove 260c having a predetermined diameter and a predetermined depth from the end is formed at the end of the 260b.

On the other hand, a bushing 240 is coupled to the second cylinder 260b, and the bushing 240 has a cylindrical shape having a predetermined height, and its diameter is slightly larger than that of the concave groove 260c so that it can be pushed into the concave groove 260c. have. A shaft hole, which is a through hole having a predetermined diameter, is formed through the centers of both ends of the bushing 240, and the shaft hole is formed to have a diameter slightly larger than that of the shaft 220 fixed to the lower bearing bracket 270. To be done.

The both ends of the bushing 240 have a hemispherical shape in which a sphere is bisected, and a spiral dynamic pressure generating groove is formed on the hemispherical surface of the bushing 240. Hemispherical grooves 230a, 230 having the same tune
b are formed to face each other. At this time, when the hemispherical grooves 230a and 230b formed in the bushing 240 and the dynamic pressure generating members 230 and 235 pushed into the shaft 220 are tightly coupled and fixed to the hemispherical grooves 230a and 230b of the bushing 240, the bushing 240 A gap for forming a fluid pressure is not formed between the dynamic pressure generating members 230 and 235 and the function of the fluid bearing is lost.

Therefore, a proper gap is required between the bushing 240 and the dynamic pressure generating members 230 and 235, and the through hole of the bushing 240 has a ring shape having a precise height and a predetermined inner diameter and outer diameter. Spacer 240a
Is inserted to maintain a predetermined gap between the dynamic pressure generating members 230, 235 and the bushing 240. That is, a pair of dynamic pressure generating members 230 and 235 and the hemispherical groove 2 that comes into surface contact with the dynamic pressure generating members 230 and 235.
The lower dynamic pressure generating member 230 and the lower hemispherical groove 230a are completely in contact with each other by the action of gravity in the portions 30a and 230b, and the upper dynamic pressure generating member 235 is the upper hemispherical groove 230.
A state in which a gap of several μm is formed with b.

Bushing 240 formed as described above
In addition to the rotor 215 and the stator 255, a ring-shaped first permanent magnet 300 that diverges a predetermined magnetic flux is attached to the outer peripheral surface of the. In addition, the lower bearing bracket 270, which is spaced a predetermined distance from the first permanent magnet 300 formed on the outer peripheral surface of the bushing 240, has the second permanent magnet 350 having the same shape and the same magnetic flux density as the first permanent magnet 300.
Are formed, the first permanent magnet 300 and the second permanent magnet 35 are formed.
0 has the same polarity and is opposite to each other.

Preferably, the first permanent magnet 300 and the lower bearing bracket 27 formed on the bushing 240.
After manufacturing the second permanent magnet 350 formed to 0 separately,
This may be attached to the bushing 240 and the lower bearing bracket 270, or the bushing 240 itself may be formed on one first permanent magnet 300 to form a lower bearing bracket 270 formed at a predetermined distance from the bushing 240. The second permanent magnet 350 is attached.

The operation of the laser scanning motor to which the hemispherical bearing device of the present invention configured as described above is applied will be described with reference to the accompanying drawings. First, the first permanent magnet 300 corresponding to the magnetic flux density of the first permanent magnet 300 formed on the outer peripheral surface of the bushing 240 and the second permanent magnet 350 formed on the lower bearing bracket 270.
Then, repulsive force due to the same polarity is generated in the second permanent magnet 350.

Here, the second permanent magnet 350 is in a fixed state, and the first permanent magnet 300 is vertically movable in the same direction as the moving direction of the bushing 240, so that the first permanent magnet is movable. Magnet 300 and second permanent magnet 350
The repulsive force generated by the force acts in the opposite direction to the weight of the bushing 240 and the load in the direction of gravity generated by the rotor 250 and the polygon mirror 210.

Therefore, the load in the direction of gravity described above is the first
The repulsive force of the permanent magnet 300 and the repulsive force of the second permanent magnet 350 are offset each other, and the load in the direction of gravity is reduced by the offset amount. In this way, when power is applied to the rotor 215 and the stator 255 and the rotor 215 starts rotating with the load of the bushing 240 reduced, the dynamic pressure generating member 2
A predetermined fluid pressure is applied between the hemispherical dynamic pressure generating members 230 and 235 and the hemispherical grooves 230a and 230b by flowing a predetermined fluid into a spiral dynamic pressure generating groove (not shown) formed in each of the grooves 30 and 235. Is generated.

At this time, the magnitude of the fluid pressure generated between the dynamic pressure generating members 230, 235 and the hemispherical grooves 230a, 230b increases in proportion to the rotation speed of the bushing 240,
When the fluid pressure generated between the lower dynamic pressure generating member 230 and the lower hemispherical groove 230a becomes larger than the weight of the bushing 240, the hemispherical groove 230b of the bushing 240 is separated from the dynamic pressure generating member 230 by a predetermined distance. To maintain.

Here, the time until the bushing 240 floats above the dynamic pressure generating member 230 is defined as the floating time.
When the number of rotations is the same, the floating time is the same as the bushing 2
In proportion to the magnitude of the load applied to 40, the bushing 24
When the load applied to 0 is constant, it is inversely proportional to the rotational acceleration. That is, the weight of the bushing 240 is increased or the rotational acceleration of the bushing 240 is decreased to extend the floating time, and the weight of the bushing 240 is decreased or the rotation of the bushing 240 is decreased to reduce the floating time. Increase acceleration.

According to the present invention, the dynamic pressure generating members 230, 2
35 and the hemispherical grooves 230a and 230b, the magnitude of the fluid pressure is constant (assuming that the maximum rotation speed is constant), but the bushing 240 is generated by the repulsive force generated by the first permanent magnet 300 and the second permanent magnet 350. The load applied to the lower part of the hemispherical bearing device is one of the core parts of the laser scanning motor due to the abrasion of the lower dynamic pressure generating member 230 and the lower hemispherical groove 230b due to the reduced flying time. It is possible to prevent shortening of the life of the laser scanning motor due to shortening of the life.

FIG. 4 is a sectional view showing another embodiment of FIG. As shown in the figure, the hemispherical bearing device using the magnetic material according to the present invention forms the third permanent magnet 400 inside the first cylinder 260a having a small diameter in the hub 260 of FIG. The fourth permanent magnet 450 is installed at a position separated from 400 by a predetermined distance. The fourth permanent magnet 450 is fixedly supported by the upper bearing bracket 275, and the fourth permanent magnet 450 is fixedly supported by the lower bearing bracket 270.
A permanent magnet 350 is formed and a first permanent magnet 300 is formed on the bushing 240 spaced apart from the lower bearing bracket 270 by a predetermined distance to adjust the load applied to the bushing 240 of the hemispherical bearing device.

FIG. 5 is a sectional view showing the structure of a laser scanning motor to which the conical bearing device according to the present invention is applied, and FIG. 6 is a sectional view showing the bushing, the shaft into which the bushing is inserted, and the conical dynamic pressure generating member portion. Fig. 7 and Fig. 5
FIG. 3 is a cross-sectional view showing a hub portion of FIG. As shown in the figure, a laser scanning motor to which a conical bearing device is applied rotates a polygon mirror 510 that reflects a laser beam to a photosensitive drum (not shown), which is an image forming surface, and a polygon mirror 510 at an extremely high speed with minimum friction. A conical bearing device for
A rotor 650 and a stator 555, which are rotational force generators that are coupled with the conical bearing device to generate a rotational force.
And a lower bearing bracket 570 and an upper bearing bracket 575 so that the above components can be seated.

A through hole having a predetermined diameter is formed in the polygon mirror 510, and the polygon mirror 51 is inserted in the through hole of the polygon mirror 510.
A hub 560 that locks the 0 is coupled. The hub 56
0 is two cylinders 560a, 5 having two different diameters.
A second cylinder 56 having a large diameter on the other side is formed by inserting a through hole formed in the polygonal mirror 510 into the outer peripheral surface of a first cylinder 560a having a smaller diameter of the two cylinders 60b.
A groove 560c having a predetermined diameter and a predetermined depth is formed in the groove 0b, and a bushing 540, which is a kind of conical bearing device, is coupled to the groove 560c.

As shown in FIGS. 6 and 7, the bushing 540 has a cylindrical shape having a predetermined height, and its diameter is slightly larger than the concave groove 560c of the hub 560, and the hub 560 has a larger diameter.
Can be tucked into. In addition, a through hole having a predetermined diameter is formed at the center of rotation of the bushing 540, and the through hole has a diameter slightly larger than that of the shaft 500 fixed to the lower bearing bracket 570, and both ends of the bushing 540 have a predetermined height. The conical grooves 530a and 530b are formed such that the ends having a ladder-like cross section having a small area face each other.

Conical grooves 530a, 530 having such a shape
The conical grooves 530a, 53
0b and the conical dynamic pressure generating members 530 and 535 require a proper gap to generate a predetermined fluid pressure. Therefore, the through hole of the bushing 540 has a ring having a precisely processed height. -Shaped spacer 540a is inserted to form conical dynamic pressure generating members 530 and 535 and conical groove 530.
A predetermined gap is maintained between a and 530b.

Here, the conical dynamic pressure generating member 530,
535 will be described with reference to FIG. The conical dynamic pressure generating members 530 and 535 have the same shape as the conical grooves 530a and 530b of the bushing 540 described above, that is, the conical shape has a ladder-shaped cross section in which the upper part of the cone is cut to a predetermined length. The spiral dynamic pressure generating grooves 5 are formed at predetermined intervals on the tapered surfaces of the conical dynamic pressure generating members 530 and 535.
37, the conical dynamic pressure generating member 53 is formed.
Through holes 0, 535 are formed through the centers of rotation of both ends, and the fixed shaft 500 is coupled to the through holes by a push fit method.

On the other hand, a ring-shaped first permanent magnet 700 is attached to the lower end portion of the outer peripheral surface of the bushing 540, and the lower bearing bracket 570 separated from the first permanent magnet 700 by a predetermined distance has a first permanent magnet. The second permanent magnet 750 formed facing the 700 is formed.
The first permanent magnet 700 and the second permanent magnet 750 are formed so that all of the same polarities face each other, and the first permanent magnet 700 and the second permanent magnet 750 generate mutual magnetic repulsion force. The magnitude of the magnetic repulsive force is generally first.
It is inversely proportional to twice the gap between the permanent magnet 700 and the second permanent magnet 750.

Here, instead of the first permanent magnet 700 attached to the lower end of the bushing 540, the bushing 540 is used.
Lower bearing bracket 57 by magnetizing itself partially
It does not matter if a repulsive force is generated with the two permanent magnets 750 formed in zero. In addition, the gap formed by the first permanent magnet 700 and the second permanent magnet 750 is the first permanent magnet 700 and the second permanent magnet 750.
The conical dynamic pressure generating members 530 and 535 of the bushing and the conical groove 5 are determined by the magnetic flux density of the permanent magnet 750 and correspond to the gap formed by the magnetic flux density.
Since the gap between 30a and 530b (see FIG. 6, t1 and t2) is variable, the first permanent magnet 700 and the second permanent magnet 75
When 0 is adjusted by the magnetic repulsive force, the dynamic pressure is generated in the spiral dynamic pressure generating groove 537 formed in the conical surface of the conical dynamic pressure generating members 530 and 535, and the bushing is generated. 540 is a conical groove 530a, 53
0b rotates at ultra-high speed in a flat state in which a predetermined gap is maintained from the conical dynamic pressure generating members 530 and 535.

As described above, when the bushing 540 starts to rotate by the motor stator 550, the bushing 540 is rotated.
Which is formed on the wall and exerts force in the direction opposite to the direction of gravity.
The magnetic repulsive force, which is inversely proportional to twice the gap between the permanent magnet 700 and the second permanent magnet 750, is inversely proportional to the gap between the conical dynamic pressure generating members 530 and 535 and the conical grooves 530a and 530b. As the fluid pressure is additionally generated by the dynamic pressure generation groove, the bushing 54
0 drastically decreases the time for which the dynamic pressure generating members 530 and 535 having the conical shape are floated, and the conical grooves 530a and 530b of the bushing 540 have the dynamic pressure generating members 530 and 530 having the conical shape.
It is possible to prevent the conical bearing device from being damaged due to abrasion caused by contact with the 535, and to extend the life of the laser scanning motor.

FIG. 8 is a sectional view showing another modification of FIG. In the embodiment shown in FIG. 5, a pair of permanent magnets, that is, a first permanent magnet 700 and a second permanent magnet 750, are provided in the bushing 5 respectively.
It is formed on the outer peripheral surface of 40 and the lower bearing bracket 570 to reduce the friction generated when the conical bearing device is started / stopped by using the magnetic repulsive force of the first permanent magnet 700 and the second permanent magnet 750.

On the other hand, in the embodiment of FIG. 8, the third permanent magnet is attached to the upper support bracket 575 formed at a position separated from the third permanent magnet 800 formed at the upper end of the upper portion of the hub 560 by a predetermined distance. A fourth permanent magnet 850 having the same structure as 800 is formed to maintain a predetermined gap between the third permanent magnet 800 and the fourth permanent magnet 850, and the first permanent magnet 70
0 and the second permanent magnet 750 adjust the magnetic flux densities of the third permanent magnet 800 and the fourth permanent magnet 850 with respect to the force to float the bushing 540 in the opposite direction of gravity, and adjust the magnetic flux density of the bushing 540 to the conical groove 530a. The distance between 530b and the conical dynamic pressure generating members 530 and 535 can be adjusted.

[0054]

As described above, according to the present invention, a magnetic material is attached to the lower end of the rotary shaft so that a magnetic repulsive force is generated, or the rotary shaft itself is made of a magnetic material, and the thrust bearing is manufactured. Is formed of a magnetic material, and the magnetic materials on both sides face each other with the same polarity, so that the friction between the rotating shaft and the thrust bearing can be reduced when the rotating shaft is started or stopped.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a laser scanning motor to which a journal bearing device according to the present invention is applied.

FIG. 2 is a sectional view showing another embodiment of FIG.

FIG. 3 is a sectional view showing a laser scanning motor to which a hemispherical bearing device according to the present invention is applied.

FIG. 4 is a sectional view showing another embodiment of FIG.

FIG. 5 is a sectional view showing a laser scanning motor to which a conical bearing device according to the present invention is applied.

FIG. 6 is a cross-sectional view showing a bushing and a shaft and a conical dynamic pressure generating member portion into which the bushing is inserted in FIG. 5;

7 is a cross-sectional view showing the hub portion of FIG.

FIG. 8 is a sectional view showing another embodiment of FIG.

[Explanation of symbols]

10, 210, 510 polygon mirror 20 sleeve 25 Bushing section 30,220,500 axes 230a, 230b hemispherical groove 35 First Dynamic Pressure Generation Section 240,540 bushings 50 thrust bearing 50a Second dynamic pressure generator 60, 260, 560 hub 60a, 260a, 560a First cylinder 60b, 260b, 560b Second cylinder 60c, 260c, 560c concave groove 70,270,570 Lower bearing bracket 75,275,575 Upper Bearing Bracket 80,215,650 rotor 85,255,555 Stator 100,300,700 1st permanent magnet 150,350,750 Second permanent magnet 200, 400, 800 Third permanent magnet 230, 235, 530, 535 Dynamic pressure generating member 240a, 540a spacer 250,450,850 4th permanent magnet 537 Dynamic pressure generation groove

Claims (6)

(57) [Claims] 1. An upper bearing bracket, a lower bearing bracket coupled to the upper bearing bracket and fixedly installing a stator and a sleeve, a rotor having a rotor and a polygon mirror facing the stator, A rotary shaft having one end coupled to the center of rotation of the rotary body and inserted into the sleeve to form a first dynamic pressure generating groove on a circumferential surface; and the rotary shaft and the lower bearing facing the rotary shaft. A magnetic levitation means formed between a bracket portion and the magnetic levitation means, the magnetic levitation means including a first magnetic body attached to the other end of the rotation shaft, and the lower bearing bracket facing the first magnetic body. A second magnetic body having a second dynamic pressure generating groove formed by adhering the same magnetic pole as the first magnetic body so as to face each other, the magnetic levitation means The third magnetic body attached to the center of rotation of the upper portion of the rotating body, and the third magnetic body on the upper bearing bracket portion facing the third magnetic body.
A magnetic body and a fourth magnetic body attached so that the same magnetic poles face each other, wherein the first and second magnetic bodies and the third and fourth magnetic bodies each have the same magnetic flux density. Characteristic laser scanning motor. 2. An upper bearing bracket, a lower bearing bracket having a stator and a sleeve fixedly connected to the upper bearing bracket, a rotor having a rotor and a polygon mirror facing the stator, A rotary shaft having one end coupled to the center of rotation of the rotary body and inserted into the sleeve to form a first dynamic pressure generating groove on a circumferential surface; and the rotary shaft and the lower bearing facing the rotary shaft. A magnetic levitation means formed between the bracket portion and the magnetic levitation means, wherein the magnetic levitation means is a rotating shaft made of a magnetic material, and the lower bearing bracket portion facing the rotating shaft,
A laser scanning motor comprising: a second magnetic body having a second dynamic pressure generating groove formed by adhering the same magnetic pole as the rotating shaft so as to face each other. 3. An upper bearing bracket, a lower bearing bracket on which a stator is fixedly installed in combination with the upper bearing bracket, a rotor having a rotor and a polygon mirror facing the stator, and the rotor. Is rotatably inserted into a bushing connected to the rotating body, the small diameter portions are opposed to each other via a spacer, and a pair of cones having dynamic pressure generating grooves formed on the surface are fixed. And a magnetic levitation means formed between the bushing and the lower bearing bracket portion facing the bushing, the magnetic levitation means including a first magnetic body attached to a lower side surface of the bushing. A second magnetic pole that is attached to the lower bearing bracket portion facing the first magnetic body so as to face the same magnetic pole as the first magnetic body. The magnetic levitation means further includes a third magnetic body attached to a center of rotation of an upper portion of the rotating body, and the upper bearing bracket portion facing the third magnetic body, the magnetic levitation means including: Three
A magnetic body and a fourth magnetic body attached so that the same magnetic poles face each other, wherein the first and second magnetic bodies and the third and fourth magnetic bodies each have the same magnetic flux density. Characteristic laser scanning motor. 4. An upper bearing bracket, a lower bearing bracket to which the stator is fixedly installed by being coupled to the upper bearing bracket, a rotor having a rotor and a polygon mirror facing the stator, and the rotor. Is rotatably inserted into a bushing connected to the rotating body, the small diameter portions are opposed to each other via a spacer, and a pair of cones having dynamic pressure generating grooves formed on the surface are fixed. And a magnetic levitation means formed between the bushing and the lower bearing bracket portion facing the bushing, the magnetic levitation means comprising a magnetic bushing and the lower portion facing the bushing. The bearing bracket portion may include a second magnetic body attached such that the same magnetic pole as the bushing faces each other. Laser scanning motor according to. 5. An upper bearing bracket, a lower bearing bracket on which a stator is fixedly installed in combination with the upper bearing bracket, a rotor having a rotor and a polygon mirror facing the stator, and the rotor. Is rotatably inserted into a bushing that is coupled to the rotating body, the arc portions are opposed to each other with a spacer interposed, and a pair of hemispheres having dynamic pressure generating grooves formed on the surface are fixed shafts. When, seen including a magnetic levitation means formed between said lower bearing bracket portion opposed to said bushing and said bushing, said magnetic levitation means, attached to the lower side surface of the bushing
The attached first magnetic body and the upper bearing bracket facing the first magnetic body.
So that the same magnetic pole as the first magnetic body faces
And a second magnetic body attached to the magnetic levitation means.
A third magnetic body attached to the center and a pair of the third magnetic body
The upper bearing bracket portion facing the third
A fourth magnet attached such that the same magnetic poles as the magnetic body face each other.
A first magnetic body, a third magnetic body, and a third magnetic body.
Laser scanning motors characterized in that each magnetic material has the same magnetic flux density . 6. A top bearing bracket, the stator is a solid bound to the upper bearing bracket
The lower bearing bracket, which is fixedly installed, and the rotor and polygon mirror facing the stator are mounted.
Rotating body and a bushing in which the rotating body is rotatably coupled to the rotating body.
Inserted in the ring, the arc-shaped parts
Opposing, a pair of hemispheres with dynamic pressure generating grooves formed on the surface
The fixed fixed shaft, the bushing, and the lower base facing the bushing.
Magnetic levitation hand formed between the arranging bracket part
The magnetic levitation means includes a step and a magnetic bushing;
The lower bearing bracket facing the bushing
Make sure that the same magnetic pole as the bushing faces the part
A laser including an attached second magnetic body
Scanning motor.