JPS63173015A - Rotation driving device - Google Patents

Abstract

PURPOSE:To easily and with high accuracy execute adjustment by providing a groove on the lower face part of the outside of a plane part of a rotary member, and also, the inside from the outermost diameter, and the upper face part of the inside from the outermost diameter of a sub-rotor. CONSTITUTION:On the lower face part of the outside of a plane part 51b of a rotary member 51, and also, the inside from the outermost diameter, and on the upper face part of the inside from the outermost diameter of a sub-rotor 55, grooves 57, 58 for attaching a weight for adjusting a dynamic balance, for instance, an epoxy putty, etc. are formed. These grooves 57, 58 are positioned at about the outermost diameter of a rotary assembly body 56, therefore, by only adding a weight for adjusting a dynamic balance small in quantity, dynamic balance of the rotary assembly body 56 can be adjusted with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotation drive device applied to, for example, a rotating polyhedral development deflector.

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 section 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 is deflected through a light deflector 10 and further scanned onto the photoreceptor 1 through an imaging optical system 7.

In addition, the deflection speed of the rotating polyhedral light deflector 10, 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 that uses a rotary body support device as shown in Japanese Patent Application No. 319. 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 rotary member 15 is rotatably mounted on the outer periphery 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
Dog-shaped herringbone grooves 26 and 27 are formed in the inner peripheral surface of the rotating member 15 to generate dynamic pressure in the radial direction due to the 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 2o. 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, forming 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, a large torque is required to rotate the rotating assembly 23 at high speed, and in order to generate this torque, the drive coil 21 is provided. The thickness of the stator 22 and the rotor magnet 18 in the rotational axis direction is required to a certain extent, and there is a limit to how thin the rotating polyhedral developing deflection device can be made.

Further, the magnetic flux generated by the rotor magnet 18 is transmitted to a stator 22 made of a magnetic material fixed to the motor housing 14.
Since the rotary assembly 23 passes through the inside, there is a drawback that when the rotating assembly 23 is rotated at high speed, hysteresis loss and eddy current loss are large. Furthermore, if the machining and assembly is not carried out with high precision so that the gap between the stator 22 and the rotor magnet 18 is uniform, the attraction force between the stator 22 and the rotor magnet 18 will vary, causing cogging and causing uneven rotation. .

Means for Solving the Problems In order to solve the above problems, the rotary drive device of the present invention includes:
a rotating member having a center of rotation in the vertical direction; a ring-shaped rotor magnet fixed to the rotating member and magnetized with multiple poles in the direction of the rotational axis; A sub-rotor is fixed to a member and is made of a soft magnetic material, and a fixed coil board is disposed in the gap between the rotor magnet and the sub-rotor, and a lower surface portion inside the outermost diameter of the rotating member and an outermost part of the sub-rotor are arranged. A groove for attaching a weight for adjusting dynamic balance, such as epoxy putty, is formed in the upper surface portion inside the diameter.

Effect of the Invention The present invention enables the use of thin rotor magnets, sub-rotors, and fixed coil substrates by the above-mentioned means, and since the magnetic flux from the rotor magnets flows through the sub-rotors that rotate at the same speed as the rotor magnets, hysteresis loss is reduced. There is no eddy current loss, the rotary drive device can be made thinner, and power consumption is reduced due to improved efficiency. In addition, grooves are formed on the lower surface of the flat surface of the rotating member and on the inner side of the outermost diameter, and on the upper surface of the sub-rotor on the inner side of the outermost diameter, for attaching weights such as epoxy putty for adjusting the dynamic balance. Since this groove is located almost at the outermost diameter of the rotating assembly, the dynamic balance of the rotating assembly can be adjusted with high precision just by adding a small amount of dynamic balance adjustment weight. can.

Therefore, adjustment is very easy, and productivity can be greatly improved and production costs can be reduced.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows a cross-sectional view of a rotating polyhedral light deflector using the rotational drive device of the present invention, and FIG. 2 shows an exploded view of the rotating polyhedron development light deflector using the rotational drive device of the present invention. It shows a perspective view.

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 bank yoke 54 are made larger than the outer diameter of the rotating polygon 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 51 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 plane 61a is disposed, and the base 6
1 is fixed to a housing (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 rotating assembly 56, and the flat surface 5 of the rotating member 51 is
A dynamic pressure gas bearing is configured opposite to 1b. In addition, the portion of the flat portion 51b that is not involved in the hydrodynamic gas bearing is the Nusumi 51.
c. 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 serves as the regulating member, and is fixed to the base 61 by press fitting or the like. ing. The rotary assembly 56 is rotatably fitted onto the fixed shaft 60 with a certain gap between it and the outer circumference of the fixed shaft, and a herringbone groove 62 is formed on the circumferential surface of the fixed shaft. The arrow-shaped tip faces the rotation direction of the rotating assembly 56, and constitutes a hydrodynamic gas bearing. In addition, the portions of the fixed shaft that are not involved in the dynamic pressure gas bearing are provided with a pad 60a.

Further, on the lower surface portion outside the flat portion 51b of the rotating member 51 and inside the outermost diameter, and on the upper surface portion inside the outermost diameter of the sub-rotor 55, there are grooves for attaching weights for adjusting dynamic balance, such as epoxy putty, etc. 57 and 58 are formed, and since this groove is located almost at the outermost diameter of the rotating assembly 56, the dynamic balance of the rotating assembly 56 can be adjusted by simply adding a small amount of weight for adjusting the dynamic balance. It can be adjusted to the degree of accumulation.

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 53a and 68b. 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 polyhedral light deflector configured as described above, by energizing the fixed coil substrate 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. and the rotating member 5
Air flows into the gap between the flat part 51b of the base 61 and the flat part 61a of the base 61 by the function of the spiral groove 63, and by the function of the herringbone groove 62 into the gap between the rotating member 51 and the fixed shaft 60. Air pressure is generated, and the rotating assembly 56 is supported in a non-contact state with the base 61 and the fixed shaft 60, and rotates with extremely low frictional resistance and stability, low loss, and high accuracy.

Effects of the Invention As explained above, the present invention includes a rotor magnet magnetized in the direction of the rotation axis, a sub-rotor arranged with a certain gap between the rotor magnet and the rotation axis direction, and a fixed coil in the gap between the rotor magnet and the sub-rotor. Because the substrate is arranged, thin rotor magnets, sub-rotors, and fixed coil substrates can be used, and the magnetic flux from the rotor magnets flows through the sub-rotor, which is fixed to the rotating assembly and rotates at the same speed as the rotor magnets. Therefore, there is no hysteresis loss or eddy current loss, and the overall thickness of the rotating polyhedral developing deflector can be reduced.
Improved efficiency reduces power consumption. In addition, grooves are provided on the lower surface of the flat surface of the rotating member, on the inner side of the outermost diameter, and on the upper surface of the sub-rotor, on the inner side of the outermost diameter, for attaching weights, such as epoxy putty, for adjusting the dynamic balance. Since this groove is located almost at the outermost diameter of the rotating assembly, the dynamic balance of the rotating assembly can be adjusted with high precision by simply adding a small amount of dynamic balance adjustment weight. Can be done. Therefore, the rotary polyhedron developing deflector according to this embodiment adjusts the dynamic balance of each component before assembling the rotary assembly, or by self-driving after the rotary assembly is assembled into the rotary polyhedron developing deflector. The work of adjusting the balance is no longer necessary, and only the work of adjusting the dynamic balance is done with the rotating assembly assembled, making the adjustment extremely easy and accurate, greatly improving productivity and reducing production costs. It is possible to reduce the In this embodiment, a hydrodynamic air bearing is used as the bearing, but the same effect of the invention can be obtained even if a well-known rolling bearing or sliding bearing is used.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a rotating polyhedron developing light deflector to which the rotational drive device of the present invention is applied, and FIG. 2 is an exploded perspective view of the rotating polyhedron developing light deflector to which the rotational drive device of the present invention is applied.
FIG. 3 is a perspective view of an optical deflection device to which a conventional rotating polyhedral developing deflector is applied, and FIG. 4 is a longitudinal cross-sectional view of a rotating polyhedral developing deflector to which a conventional rotary drive device is applied. 51...Rotating member, 52...Rotating polyhedron, 53...Rotor magnet, 55...
Sub rotor, 56...Rotating assembly, 57...
...Groove, 58...Groove, 60...Fixed shaft, 61...Base, 62...Herringbone groove, 63...・Spiral groove, 65...
...Fixed coil board. Name of agent Patent attorney Toshio Nakao Haka1 person12 Figure
65-1 note y21 cane 3rd
figure

Claims (1)

[Claims] a rotating member having a rotation center in the direction normal to the base and a flat surface facing the top surface of the base; a rotor magnet, a sub-rotor that is arranged with a certain gap in the axial direction from the rotor magnet, is fixed to the rotating member, and is made of a soft magnetic material; and a fixing member that is arranged in the gap between the rotor magnet and the sub-rotor. A rotary drive device comprising a coil substrate and having grooves on a lower surface portion outside the plane portion of the rotating member and inside the outermost diameter, and on an upper surface portion inside the outermost diameter of the sub-rotor. .