JPS63173014A - Rotary body supporting device - Google Patents

Abstract

PURPOSE:To thin the titled device by providing a gas bearing part for generating the dynamic pressure of gas by the rotation of a rotary body, and supporting the axial direction of a rotary member and its inclination in a state of non- contact, between a base plate and a plane part of the rotary member. CONSTITUTION:A rotary body supporting device in an optical reflector is provided with a plane part of a rotary member 51 for holding a rotary body containing a rotary polyhedron mirror 52, and a dynamic pressure gas bearing for generating the dynamic pressure by the rotation between plane parts of a base plate 61 placed so as to be opposed to its plane part and supporting the rotary member 51 in a state of non-contact. Also, in the radial direction of the rotary member 51, a control member for supporting mainly its unbalanced force, for instance, a fixed axis 60 is provided. Accordingly, by the dynamic gas bearing part, the rotary member is supported in the axial direction, and also, its inclination can be held simultaneously. In such a way, the rotary body supporting device can be thinned remarkably, and also, a rotary polyhedron mirror optical deflector which is applied this device is thinned and miniaturized, as well.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotating body support device that is applied to, for example, a rotating polyhedral developing deflector, and stably supports a rotating body that rotates with high accuracy and high speed.

Conventional technology In recent years, with the development of office equipment, there has been a demand for printer-related equipment that records and prints information to be faster, smaller, and lower in cost. Printers with high print quality and high speed are now appearing.

Generally, as shown in FIG. 3, this laser beam printer scans a pre-uniformly charged photoreceptor 1 with a laser beam from an optical scanning section 2 to form an electrostatic latent image on the photoreceptor 1. The optical scanning unit 2 shapes the laser beam 3 emitted from the semiconductor laser light source 4 into an appropriate beam shape through the beam shaping optical system 5, and converts the laser beam 3 into a rotating polygon. The light beam is deflected through a light deflector 6 and scanned onto the photoreceptor 1 through an imaging optical system 7.

In addition, the deflection speed of the rotating polyhedral light deflector 6, that is, the high speed and high precision of the optical deflector, mainly determines the high speed and high quality of the laser beam printer. It consists of

Conventionally, a rotating polyhedral developing deflector is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-23
There is a configuration in which a rotating body support device as shown in Japanese Patent No. 319 is applied. Its configuration is shown in FIG.

In FIG. 4, the rotating polyhedron light deflector 10 is composed of a rotating polyhedron 11 and a rotation drive unit 12 that rotates the rotating polyhedron 11 at high speed in a predetermined direction.

A fixed shaft 13 is fixed on the motor housing 14, and a hollow cylindrical rotating member 15 is rotatably fitted around the outer circumference of the fixed shaft 13 with a slight gap therebetween.

Further, the upper and lower ends 28 and 29 of the outer circumferential surface of the fixed shaft 13 are
Dogleg-shaped herringbones 'a26 and 27 are formed in which generate dynamic pressure in the radial direction due to relative speed with the inner circumferential surface of the rotating member 15.

On the other hand, an inner magnetic ring 17 of a magnetic bearing 16 for thrust support is attached to the lower end of the rotating member 15, and a rotor magnet 18 is fixed to the rotating member 15 near the center in the vertical direction.

Further, above the rotor magnet 18, a rotating polyhedron 11
While the lower end surface is in contact with the rotating member 15, the upper end surface is pressed and fixed by the mirror holding member 20. On the other hand, the motor housing 14 has a stator 2 provided with a drive coil 21 surrounding the outer periphery of the rotor magnet 18.
2 is fixed, rotating polyhedron 11, rotor magnet 18
The rotating assembly 23 consisting of the magnetic ring 17 and the inner magnetic ring 17 is rotatably driven by a well-known direct current brushless drive system.

Further, an outer magnetic ring 24 is similarly fixed below the motor housing 14 so as to surround the inner magnetic ring 17 with a certain gap, and the inner magnetic ring 17 and the outer magnetic ring 24 have an attractive force with each other. It constitutes a thrust support magnetic bearing 16 that is magnetized to work and supports the rotary assembly 23 in the vertical direction (direction of its own weight). Further, a sealing cover 25 is attached to the upper part of the motor housing 14, and clean air is sealed therein.

With the above configuration, when the drive coil 21 is energized, a rotating magnetic field is generated in the stator 22, and the rotating assembly 23 is rotated by the magnetic attraction force with the rotor magnet 18.

As a result, a relative speed is generated between the rotating member 15 and the fixed shaft 13, and air flows into the gap between the herringbone grooves 26 and 27 at the upper and lower ends of the fixed shaft 13, generating air pressure in the radial direction, creating a so-called dynamic pressure gas bearing. The rotating assembly 23 rotates at high speed with extremely low frictional resistance and stability in a non-contact state. Therefore, the rotating polygon 11 is also rotated at a high speed, and accordingly, the laser beam is deflected at a high speed within the optical scanning section. At this time, since the accuracy of the trajectory of the deflected laser beam is determined by the inclination and deformation of each mirror surface of the rotating polygon 11 during rotation, the inclination (dynamic surface tilt) of each mirror surface of the rotating polygon 11, that is, the optical deflector Considerably high specifications are required in terms of stability and rotation accuracy during high-speed rotation.

Problems to be Solved by the Invention However, in the above configuration, the rotating member 15
is supported in the radial direction by two dynamic pressure gas bearings 28 and 29 provided at the upper and lower ends of the fixed shaft 13, and the thrust magnetic bearing 16 holds the load only in the thrust direction. The above-mentioned fixed shaft 13 supports the tilt due to gyro moment etc. that occurs during high-speed rotation.
This is done by a gas bearing on top.

Therefore, the load capacity, stability, and accuracy of rotating members during high-speed rotation, such as run-out and tilt accuracy, are determined by the bearing spacing between the gas bearings 28 and 29 at the upper and lower ends of the fixed shaft 13 and the bearing specifications, such as the herringbone groove 26. and the gas spring constant of the bearing, which is determined by the depth of the groove 27, the number of grooves, or the gap between the rotating member 15 and the fixed shaft 13.

In particular, the bearing spacing of the gas bearing section on the fixed shaft has a great influence on the stability and accuracy, and a sufficiently long bearing spacing is required.

However, in order to make this rotating polyhedral light deflector stable under high-speed rotation and to make it thinner, it is necessary to shorten the bearing spacing in the above configuration. This has had problems in that stability and inclination accuracy are lowered, and the printing quality as a laser beam printer is also deteriorated.

In particular, the need for the reduction in size and thickness becomes apparent when the rotating polyhedral light deflector 6 is incorporated into the optical scanning section unit 2. That is, in the optical scanning unit 2, the optical units other than the optical deflector 6, such as the beam shaping optical system 5 and the imaging optical system 7, which are mainly composed of lens groups, are thinned to a thickness close to the spot diameter formed by the laser beam 3. However, the optical deflector 6 requires the above-mentioned structure including the rotating polygon 11, and the optical scanning unit 2
When the unit 2 is assembled into the unit 2 as shown in FIG.
Only the optical deflector 2 protrudes from the frame.

For this reason, when this optical scanning section 2 is incorporated into the main body of a laser beam printer, there is a problem that the space occupied by the optical scanning section 2 in the entire main body becomes large and the main body itself becomes large.

Means for Solving the Problems In order to solve the above problems, the rotating body support device of the present invention includes a rotating body, and a rotating body including the rotating body and having a flat portion formed on an end face in the direction of the rotation center. a base pedestal having a member and a regulating member disposed opposite to the flat surface of the rotating member and regulating the radial direction of the rotating member on the rotation center; This configuration includes a gas bearing section that generates gas dynamic pressure when the rotating member rotates and maintains the axial direction and inclination of the rotating member in a non-contact state.

Function The present invention has the above-described configuration, and instead of the conventional hydrodynamic gas bearings at two locations on the circumferential surface of the stationary shaft having the tilting accuracy and stability that occur when the rotating body rotates at high speed, The hydrodynamic gas bearing provided on the flat surface of the rotating body supports the rotating body in the axial direction and maintains its tilt accuracy and stability, while the radial direction of the rotating body mainly supports the rotation body. By regulating a small load such as a balancing force with a regulating member, the rotating body support device can be made significantly thinner, and the rotating polyhedral developing deflector to which this device is applied can also be made thinner and smaller.

In addition, by expanding the gas bearing part on the flat surface of the rotating body and installing it integrally with the above-mentioned regulating member, the load capacity is increased, and the permissible accuracy of the bearing is increased, making processing, assembly, adjustment, etc. easier. It is something.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a rotating polyhedron developing/deflecting device using the rotary drive device of the present invention, and FIG. 2 is an exploded perspective view of the rotating polyhedron developing/deflecting device using the rotary drive device of the present invention. The figure is shown below.

In FIG. 1, reference numeral 51 is a rotating member having a flange-like shape and having a center of rotation in the vertical direction, and a rotating polyhedron 52
is in contact with the upper surface 51a of the flange portion and fixed by adhesive or other means. Reference numeral 53 denotes a ring-shaped rotor magnet, which is bonded to a back yoke 54 made of a soft magnetic material and magnetized with multiple poles in the direction of the rotation axis.
4 is in contact with the upper surface of the rotating polyhedron 52 and is fixed by means of adhesive or the like. Further, the diameters of the flange portion of the rotating member 51 and the back yoke 54 are made larger than the outer diameter of the rotating polyhedron 52. In other words, the rotating polygon 52 is sandwiched between the flange portion of the rotating member 51 having a larger diameter and the back yoke 54. A sub-rotor 55 is made of a soft magnetic material, is arranged with a certain gap in the axial direction from the rotor magnet 53 so that the magnetic flux from the rotor magnet flows, and is fixed to the rotating member 52 by adhesive or other means. ing. That is, the rotating member 51, the rotating polygon 52, the rotor magnet 53, the back yoke 54, and the sub-rotor 55 are fixed to each other and constitute a rotating assembly 56.

A smooth plane part 51b is formed on the lower end surface of the flange part of the rotating member 51, and facing the plane part 51b,
A base 61 having a smooth flat surface 61a is arranged, and the base 61 is fixed to a casing (not shown). Further, a spiral groove 63 is formed on the flat surface 61a of the base 61 so that its centripetal direction coincides with the rotating direction of the rotary assembly 56, and faces the flat surface 51b of the rotary member 51 to apply dynamic pressure. It constitutes a gas bearing. Also, plan view 51
The portions not involved in the dynamic pressure gas bearing shown in b are coated with a mat 51c. Further, 61b is a pressure regulating hole that communicates with the outside from this hollow hole 51c.

A regulating member for regulating the movement of the rotating assembly 56 in the radial direction is disposed in the center of the base 61. In this embodiment, the fixed shaft 60 is the regulating member, and a press-fit ring is attached to the base 61. Fixed. Further, the rotary assembly 56 is connected to the fixed shaft 60 through a certain gap from the outer circumference of the fixed shaft.
is rotatably fitted on the outside, and a belling bone groove 62 is formed at one place on the circumferential surface of the fixed shaft, and the arrow-shaped tip is connected to the rotating assembly 5.
6, and constitutes a dynamic pressure gas bearing.

Also, the parts that are not involved in the dynamic pressure gas bearing of the fixed shaft are Nusumi 6
0a is applied.

Furthermore, grooves 57 and 58 are formed on the outer circumference of the lower flat part 51b of the rotating member 51 and on the outer circumference of the upper part of the sub-rotor 55 for attaching weights for adjusting dynamic balance. The dynamic balance can be adjusted with high precision under the same conditions.

Further, in FIG. 2, reference numeral 65 denotes fixed coil substrates 65a and 65b which are fixed to the motor frame 64 with screws 71 and can be divided into two pieces, and a plurality of flat coils 66 are attached to the motor frame 64.
, a rotor magnet position detection sensor 67, and two printed circuit boards 68a. In this embodiment, the flexible printed circuit board is the printed circuit board 68a.
, 68b. The plurality of flat coils 66 and the rotor magnet position detection sensor 67 are mounted on a printed circuit board 68a.
and 68b, and is further molded with resin 70. Therefore, the fixed coil substrate 65 can be divided into two parts and arranged in the gap between the rotor magnet 53 and the sub-rotor 55 after adjusting the dynamic balance of the rotating assembly 56.

In the rotating polyhedron development deflection device configured as described above, by energizing the fixed coil board 65, rotational torque is generated in the magnetic flux in the air gap between the rotor magnet 53 and the sub-rotor 55, and the rotating assembly 56 rotates at high speed. However, a spiral groove 63 is formed in the gap between the opposing plane part 51b of the rotating member 51 and the plane part 61a of the base 61, and a herringbone groove 6 is formed in the gap between the rotating member 51 and the fixed shaft 60.
2, air flows in and generates air pressure, and the rotating assembly 56 is supported without contact with the base 61 and the fixed shaft 60, with extremely low frictional resistance and stability, low loss and high performance. Rotate with precision.

As described above, according to this embodiment, the rotating body support device in the optical deflector is disposed opposite to the plane part of the rotating member 51 that holds the rotating body including the rotating polygon 52. A dynamic pressure gas bearing is provided between the flat surface of the base 61 to generate dynamic pressure by rotation and support the rotating member 51 in a non-contact state, and furthermore, the unbalanced force is mainly applied in the radial direction of the rotating member 51. In this embodiment, since the fixed shaft 60 is provided, the dynamic pressure gas bearing section can support the rotating member 51 in the axial direction and maintain its inclination at the same time. can.

Moreover, the area occupied by the gas bearing section developed on the flat surface of the base 61 and the rotating member 51 can be arbitrarily set up to the size of the flat surface 51b allowed in the optical deflector main body.

Further, in the radial direction of the rotating member 51, it is sufficient to maintain only the load mainly due to the unbalanced force, and a regulating means having a gas bearing portion at about one location is sufficient.

Therefore, in this embodiment, the rotor support device can be made significantly thinner than the conventional structure in which the inclination accuracy and stability that occur when the rotary member 51 rotates at high speed are borne by gas bearings on the circumferential surface of the fixed shaft at two locations. In addition to being measurable, the rotating polyhedral light deflector to which this device is applied also becomes thinner and smaller.

In addition, by increasing the bearing area of the flat part, the surface pressure can be reduced even when the rotating member 51 is loaded in the direction of its own weight, which is a unique feature of hydrodynamic gas bearings. There is less possibility of damage such as seizure due to wear or rotation failure.

Furthermore, since the spiral groove 63, which is a part of the hydrodynamic gas bearing, is formed on the base 1000-sided surface 61a, press working, resin molding, etc. It is suitable for the integral molding method, which is highly suitable for mass production.

Further, a regulating means for regulating the unbalanced force of the rotating body in the radial direction of the rotating body by sufficiently counting the amount of unbalance;
In this embodiment, the fixed shaft 60! y) The permissible accuracy for the bearing specifications of the gas bearing section is large, and the gas bearing section with a large load capacity and the above-mentioned regulating means are integrated and assembled on the flat surface of the base pedestal 61, making it easy to process. , assembly becomes easier and productivity is improved.

Although the above embodiment is a rotating body support device that supports a rotating body having a rotating polygon, the present invention is not limited thereto and can be applied to any rotating body.

In addition, in the above-mentioned embodiment, the regulating member is a fixed shaft and a dynamic pressure gas bearing is configured thereon, but the present invention is not limited to this and can be applied as long as there is a sliding bearing.

Effects of the Invention As described above, the present invention includes a rotating body, a rotating member including the rotating body and having a flat portion formed on an end face in the direction of the center of rotation, and a rotating member opposite to the flat portion of the rotating member. the base pedestal, and a regulating member disposed in the direction of the rotation center to restrict radial movement of the rotating member; the gas movement between the base pedestal and the flat surface of the rotating member during rotation of the rotating body; The structure includes a gas bearing section that generates pressure and maintains the axial direction and inclination of the rotating member in a non-contact state, compared to the conventional structure with three dynamic pressure gas bearing sections provided on the circumferential surface of a fixed shaft. In contrast, the rotating body support device can be made significantly thinner while guaranteeing tilt accuracy and stability during high-speed rotation of the rotating body, and the rotating polyhedral optical deflector to which this device is applied can also be made thinner and smaller. It has excellent effects.

In addition, the gas bearing part and the means for regulating the radial direction of the rotating body are integrally provided on the flat part of the base, and the bearing part of this flat part mainly has the function of maintaining the load and accuracy of the rotating body. The permissible accuracy around the fixed shaft, which is a regulating member, is increased, making processing and assembly of the device easier, and productivity is greatly increased. Furthermore, since the gas bearing section is developed on the flat surface, the load capacity of the bearing can be increased, and stable and highly accurate rotation can be obtained with less damage to the bearing surface.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional side view of a rotating polyhedral continuous optical deflector to which the rotating body support device of the present invention is applied, FIG. 2 is an exploded perspective view of the rotating polyhedral continuous optical deflector according to the present embodiment, and FIG. FIG. 4 is a perspective view of an optical scanning device to which a conventional rotating polyhedral continuous light deflector is applied, and FIG. 4 is a configuration diagram of a rotating polyhedral continuous light deflector to which a conventional rotating body support device is applied. 51... Rotating member, 51b... Rotating member plane part, 52... Rotating polyhedron embodiment, 53...
... Rotor magnet, 56 ... Rotating assembly, 60
...Regulation member, 61 ...Base stand, 6
1b...Pressure adjustment hole, 63...Spiral winding. Name of agent: Patent attorney Toshio Nakao and 1 other person 1s2 figure l-Hideko body 2, - advance 1f IO-time Le face body Wamitsu j4 #J device n--ro change face body figure 3 II-time Side surface embodiment 13 - fixed shaft 15 - concave k @ 7 o 16 - slanut magnetic bearing 18 - rotor magnet 23 - [i1 rotation assembly 21, . 71---Herringpole Shin 28.7? -One dynamic pressure gas bearing Figure 4

Claims (2)

[Claims] (1) a rotating body, a rotating member having the rotating body and formed with a flat part on an end face in the direction of the rotation center; a base disposed opposite to the flat part of the rotating member; and a regulating member disposed in the center direction to regulate the movement of the rotating member in the radial direction, the rotation of the rotating member generates gas dynamic pressure between the base table and the flat surface of the rotating member, and the axis of the rotating member is adjusted. A rotating body support device comprising a gas bearing portion that supports the direction and inclination thereof in a non-contact manner. (2) The regulating member is a fixed shaft provided on the base, and there is a certain gap between the circumferential surface of the fixed shaft and the inner circumferential surface of the rotating member, forming a hydrodynamic gas bearing at one location. A rotating body support device according to claim (1).