JP2007225678A - Polygonal scanner motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polygon scanner motor having an excellent turing balance by improving a tight contact of a polygon mirror to a rotor housing. <P>SOLUTION: At least one of the outer peripheral side contact face 16a of a rotor housing 2 and the inter peripheral side contact face 5a of a polygon mirror 5 is formed in a curved shape. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polygon scanner motor that is rotated by mounting a polygon mirror on a rotor, for example.

  A polygon scanner motor that rotates a polygon mirror or the like at high speed is used in OA equipment such as a laser beam printer or a copying machine provided with a polygon mirror. As this polygon scanner motor, an outer rotor type DC brushless motor is preferably used. Specifically, the rotor has a cup-shaped rotor housing supported on a rotating shaft, and a polygon mirror is positioned and mounted on the rotor housing in the horizontal direction and the vertical direction. The polygon mirror is fixed to the mounting surface of the rotor housing by a spring or the like. The rotating shaft of the rotor is rotatably supported by the stator housing portion.

  As an example, the rotor housing and the rotating shaft are assembled through the manufacturing steps shown in FIGS. Specifically, in FIG. 6A, forging or cutting is performed on the metal material, and the outer shape of the rotor housing 51 is processed into a stepped cup shape. Next, in FIG. 6B, a shaft hole 52 is drilled in the center of the rotor housing 51, and the mounting surface on which the polygon mirror is mounted is precisely processed. That is, the outer peripheral surface 53a of the cylindrical portion 53 into which the polygon mirror is fitted and the support surface 54a of the mirror mounting portion 54 that supports the polygon mirror are cut using a cutting tool. The outer peripheral surface 53a and the support surface 54a are cut so as to be orthogonal to each other.

  Next, in FIG.6 (c), the rotating shaft 55 is inserted in the shaft hole 52 of the rotor housing 51 (for example, press fit, shrink fitting, etc.), and is fixed. In this state, the rotor housing 51 and the rotating shaft 55 are not necessarily perpendicular. In order to improve such surface tilt characteristics, it is necessary to reduce the deflection of the support surface 54a with respect to the rotating shaft 55. For this reason, the deflection process is performed in FIG. That is, the rotor housing 51 is rotated around the rotation shaft 55, and the outer peripheral surface 53a or the support surface 54a is cut as necessary using a cutting tool 56 to remove runout due to rotation.

  However, in FIG. 6E, the degree of orthogonality between the outer peripheral surface 53a of the cylindrical portion 53 and the support surface 54a of the mirror mounting portion 54 is lost (not 90 °) after the swinging process. Therefore, in FIG. 7, even if the cylindrical portion 53 of the rotor housing 51 is inserted into the center hole of the polygon mirror 57, the mirror 57 may be mounted in a tilted state without being in close contact with the support surface 54a of the mounting portion 54. . In order to avoid this, it is necessary to increase the clearance between the outer peripheral surface 53a of the cylindrical portion 53 serving as the contact surface and the inner peripheral surface 57a of the polygon mirror 57.

However, since the polygon mirror 57 rotates at a high speed, it is necessary to suppress the change in the rotation balance of the rotor as much as possible. For this reason, it is necessary to make the clearance of the fitting part of the polygon mirror 57 and the rotor housing 51 as small as possible (for example, about 10 μm). If the clearance between the fitting portions is designed to be small, galling is likely to occur between the outer peripheral surface 53a of the rotor housing 51 and the inner peripheral surface of the polygon mirror 57 depending on the assembly posture of the polygon mirror 57. Adhesiveness with the support surface 54a decreases, and the surface tilt (tilt with respect to the horizontal plane) of the polygon mirror 57 increases.
As described above, it has been difficult to simultaneously satisfy the contradicting demands of improving the surface tilt characteristics by improving the adhesion of the polygon mirror 57 to the rotor housing 51 and reducing the clearance of the fitting portion.

  The present invention has been made to solve these problems, and the object of the present invention is to simultaneously improve surface tilt characteristics and improve the clearance of the fitting portion as much as possible by improving the adhesion of the RIGON mirror to the rotor housing. The object is to provide a realized polygon scanner motor.

In order to achieve the above object, the present invention comprises the following arrangement.
A polygon mirror is mounted on the cup-shaped rotor housing with the horizontal and vertical positions aligned, and a ring-shaped magnet is provided in the rotor housing and the rotor rotates around the rotation axis, and the rotation axis is supported rotatably. In the polygon scanner motor having a stator in which the motor substrate and the stator core are assembled to the stator housing, the outer peripheral side contact surface of the rotor housing and the inner peripheral side contact surface of the polygon mirror are formed in a curved shape. Features.
Further, the outer peripheral side contact surface that fits with the polygon mirror of the rotor housing is formed in a spherical shape having the inner diameter of the polygon mirror as a diameter.
Alternatively, the inner peripheral contact surface that fits into the rotor housing of the polygon mirror is formed on an annular surface inscribed in the outer peripheral surface of the rotor housing.

If the polygon scanner motor described above is used, at least one of the outer peripheral contact surface of the rotor housing and the inner peripheral contact surface of the polygon mirror is formed in a curved shape, so that the clearance between the fitting portion of the rotor housing and the polygon mirror is reduced. Can be designed as small as possible. That is, when the polygon mirror is assembled, the SR (sphere) surface (rotor side) and the cylindrical surface (mirror side) or the SR surface (mirror side), or the cylindrical surface (rotor side) and the annular surface (mirror side) are lined up. Contact. For this reason, even if the clearance of the fitting portion is designed to be as small as possible, the degree of freedom of the polygon mirror assembly posture is high, so that the mirror can be assembled to the housing with good adhesion without causing galling on the contact surface. . Therefore, the adhesion of the polygon mirror to the rotor housing is improved, so that the surface tilt characteristic is improved, and the assembling property can be improved.
In particular, if the outer peripheral contact surface that fits into the polygon mirror of the rotor housing is formed in a spherical shape with the inner diameter of the polygon mirror as the diameter, the adhesion of the polygon mirror to the rotor housing is improved, so the surface tilt characteristics are improved. In addition, the assemblability is improved and the rotor housing side can be easily processed without special processing on the polygon mirror side.
Further, if the inner peripheral contact surface that fits into the rotor housing of the polygon mirror is formed on an annular surface that is inscribed in the outer peripheral surface of the rotor housing, the adhesion of the polygon mirror to the rotor housing is also improved. The tilting characteristics are improved and the assembly is improved.

  The best mode of a polygon scanner motor according to the present invention will be described below with reference to the accompanying drawings. The polygon scanner motor of the present embodiment includes a rotor on which a polygon mirror is mounted in a cup-shaped rotor housing with its position aligned in the horizontal and vertical directions, and a motor substrate and a stator core on a stator housing that rotatably supports the rotating shaft of the rotor. An outer rotor type DC brushless motor having a stator to which is assembled is suitably used.

A schematic configuration of the polygon mirror motor will be described with reference to FIGS. 1 and 2.
In FIG. 2, a cup-shaped rotor housing 2 is used for the rotor 1. A shaft hole 3 is bored in the rotor housing 2, and a rotating shaft 4 is integrally fixed to the shaft hole 3 by press fitting or shrink fitting.

  In FIG. 1, a polygon mirror 5 is mounted on the upper surface of the rotor housing 2 and is pressed against the upper surface of the rotor housing 2 by a pressing spring 6. The holding spring 6 is fixed by a C-type retaining ring 7 that is fitted into a cylindrical portion that is formed upright around the shaft hole 3. In FIG. 2, a ring-shaped magnet 8 is fixed to the inner peripheral surface of the rotor housing 2. The magnet 8 is magnetized alternately with N and S poles in the circumferential direction.

  In FIG. 2, the stator 9 has a rotating shaft 4 coaxially incorporated in a stator housing 10 via a dynamic pressure bearing 11. The stator housing 10 is formed by continuously forming cylindrical portions having different outer diameters, a stator core 12 is fitted into the small diameter portion via an adhesive, and a motor substrate (printed circuit board) 13 is disposed at the large diameter portion. It is fixed. A thrust receiver 14 is fitted into the stator housing 10 using a hole diameter step from the motor substrate 13 side. The thrust receiver 14 receives the shaft end (lower end) of the rotating shaft 4 and defines the shaft end position.

  The stator core 12 is provided with radially provided stator magnetic pole portions, and stator coils 15 for, for example, three phases are wound around each stator magnetic pole portion. As the stator core 12, for example, a laminated core in which silicon steel plates punched by a press are laminated is used.

  The motor board 13 is caulked to the stator housing 10 in a direction orthogonal to the rotation shaft 4. The motor substrate 13 is mounted with electronic components constituting a motor drive circuit, and a magnetic pole sensor (for example, a Hall sensor) is provided on the same substrate so as to face the end surface of the magnet 8. The magnetic pole sensor detects the magnetic pole position of the rotor 1 from the leakage magnetic flux of the magnet 8. In accordance with the rotational position of the rotor 1 detected by the magnetic pole sensor, the motor drive circuit switches the energization to the stator coil 15 in a direction for energizing the rotation of the rotor 1.

  In FIG. 3, the rotor housing 2 is formed in a stepped cup shape by, for example, cutting a metal material. A cylindrical portion 16 protruding from the central portion of the rotor housing 2 and a mirror mounting portion 17 are formed around the cylindrical portion 16 in a direction substantially orthogonal to the cylindrical portion 16. By inserting the cylindrical portion 16 into the center hole 18 of the polygon mirror 5, the polygon mirror 5 is supported in close contact with the mirror mounting portion 17. The cylindrical portion 16 is not necessarily formed in the rotor housing 2, and the polygon mirror 5 is assembled by providing a fitting portion such as a concavo-convex portion, a ring-shaped or arc-shaped protrusion on the outer periphery of the housing, for example. May be.

  In the present invention, at least one of the outer peripheral side contact surface of the rotor housing 2 and the inner peripheral side contact surface of the polygon mirror 5 is formed in a curved shape. Specifically, in FIG. 4 in which the portion A of FIG. 1 is enlarged, the outer peripheral side contact surface 16a of the cylindrical portion 16 protruding from the rotor housing 2 has a spherical shape whose diameter is the hole diameter (inner diameter) R of the polygon mirror 5. Is formed. When the polygon mirror 5 is assembled, the SR surface (outer peripheral contact surface 16a) and the cylindrical surface (inner peripheral contact surface 5a) are in line contact. For this reason, even if the clearance of the fitting portion is designed to be as small as possible, the degree of freedom of the assembly posture of the polygon mirror 5 is high, so that the polygon mirror 5 adheres to the rotor housing 2 without causing galling on the contact surface. Can be assembled well. Therefore, since the adhesion of the polygon mirror 5 to the rotor housing 2 is improved, the surface tilt characteristic is improved, and the assembling property can be improved. In addition, there is an advantage that cutting on the rotor housing 2 side can be easily performed without performing special processing on the polygon mirror 5 side.

  Alternatively, in FIG. 5 in which the portion A of FIG. 2 is enlarged, the inner peripheral contact surface 5a of the polygon mirror may be formed on an annular surface inscribed in a spherical surface having the inner diameter of the polygon mirror as a diameter. Even with this configuration, even if the assembly posture of the polygon mirror 5 is tilted, the inner peripheral contact surface 5a is an annular surface, and therefore no galling occurs with the opposing outer peripheral contact surface 16a.

  Furthermore, both the outer peripheral side contact surface 16a of the rotor housing 2 and the inner peripheral side contact surface 5a of the polygon mirror 5 may be formed in curved surfaces. That is, you may have both the outer peripheral side contact surface 16a (SR surface) of FIG. 4, and the inner peripheral side contact surface 5a (annular surface) of FIG. However, since the area of the contact surface is extremely small and the center position of the contact surface is liable to shift, it is necessary to adjust the height from the mirror mounting portion 17 in order to ensure the positioning of the polygon mirror 5 in the horizontal direction.

It is a top view of a polygon scanner motor. It is a half sectional view of a polygon scanner motor. It is explanatory drawing of a polygon mirror and a rotor housing. It is an enlarged view of the contact surface of a polygon mirror and a rotor housing. It is an enlarged view of the contact surface of a polygon mirror and a rotor housing. It is explanatory drawing of the manufacturing process of a rotor housing. It is the elements on larger scale which show the malfunction of the assembly | attachment state to the rotor housing of a polygon mirror.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotor 2 Rotor housing 3 Shaft hole 4 Rotating shaft 5 Polygon mirror 5a Inner peripheral side contact surface 6 Retaining spring 7 Retaining ring 8 Magnet 9 Stator 10 Stator housing 11 Dynamic pressure bearing 12 Stator core 13 Motor substrate 14 Thrust receiver 15 Stator coil 16 Cylinder Part 16a Outer peripheral contact surface 17 Mirror mounting part 18 Center hole

Claims (3)

A polygon mirror is mounted on the cup-shaped rotor housing with the horizontal and vertical positions aligned, and a rotor that rotates around the rotation axis with a ring-shaped magnet installed in the rotor housing is supported rotatably. In a polygon scanner motor having a stator in which a motor substrate and a stator core are assembled to a stator housing,
A polygon scanner motor characterized in that at least one of the outer peripheral side contact surface of the rotor housing and the inner peripheral side contact surface of the polygon mirror is formed in a curved shape.   2. The polygon scanner motor according to claim 1, wherein the outer peripheral side contact surface that fits into the polygon mirror of the rotor housing is formed in a spherical shape having the inner diameter of the polygon mirror as a diameter.   2. The polygon scanner motor according to claim 1, wherein the inner peripheral side contact surface that fits into the rotor housing of the polygon mirror is formed on an annular surface that is inscribed in the outer peripheral surface of the rotor housing.

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