JPH1114928A - Polygon mirror scanner motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polygon mirror scanner motor of high print precision used for polarization scanning by preventing the flatness of a polygon mirror from becoming worse owing to the flawing of the outer peripheral part of a rotor boss before the polygon mirror is fixed. SOLUTION: The rotor boss 6 which comes into contact with the polygon mirror 4 is provided with a step part 12 which is a step lowered below the polygon mirror 4 and does not contact the polygon mirror 4 at the outer peripheral part and then deterioration in the flatness of the polygon mirror having been fixed can be suppressed even if a shock is applied from the outer circumferential direction of the rotor boss 6 to flaw the rotor boss 6 in its outer peripheral direction before the polygon mirror 4 is fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polygon mirror scanner motor used in laser beam scanning in a laser beam printer, a laser copying machine, or the like.

[0002]

2. Description of the Related Art In recent years, a polygon mirror scanner motor (hereinafter simply referred to as a motor) for rotating a polygon mirror in a laser beam printer or the like has a flatness of a surface on which a polygon mirror of a rotor boss is fixed in terms of high precision printing. Is strictly required. Conventionally, as such a motor, a motor described in JP-A-7-175003 is known.

[0003] A conventional motor will be described below. FIG. 2 is a sectional view of a conventional motor. In FIG. 2, a rotating shaft 1 is rotatably supported by an inner diameter hole of a bearing 3 fixed to a substrate 2, and a rotor boss 6 having an outer peripheral edge 5 in contact with a polygon mirror 4 is fixed. The polygon mirror 4 and the mirror holding plate 7 are fixed to the upper part of the rotor boss 6 by a grip ring 8. A cup-shaped rotor frame 9 drawn by a die is fixed to a lower portion of the rotor boss 6, and a rotor magnet 10 is fixed to an inner periphery of the rotor frame 9. The rotor frame 9 is made of a thin iron plate that can be drawn with high precision.
Uses a rubber magnet. A stator coil 11 is disposed on the substrate 2 at a position facing the rotor magnet 10.

A plurality of mirror-finished mirrors are formed on the side surface of the polygon mirror 4. The flatness of the mirror surface is maintained at a high accuracy of a fraction of μm or less in order to accurately scan the polarization of the light beam.

[0005] Regarding the motor configured as described above,
The operation will be described below. First, a current flows through the stator coil 11 to generate a driving force between the stator coil 11 and the rotor magnet 10, and the polygon mirror 4 starts rotating and performs polarization scanning.

[0006]

In this motor, the flatness of the surface of the rotor boss 6 to which the polygon mirror 4 is fixed is strictly required from the viewpoint of high precision printing. However, in the conventional structure, when an impact is applied from the outer peripheral direction of the rotor boss 6 before the polygon mirror 4 is fixed, a scratch is generated on the polygon mirror fixing surface side in the outer peripheral direction of the rotor boss 6, and the polygon mirror fixing surface is damaged. Had worsened due to scratches.

Therefore, the present invention solves the above-mentioned conventional problems, and a shock is generated on the polygon mirror fixing surface side in the outer peripheral direction of the rotor boss due to an impact from the outer peripheral direction of the rotor boss before fixing the polygon mirror. Another object is to prevent the flatness of the polygon mirror fixing surface of the rotor boss from being deteriorated.

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention has a step on the fixing surface side of the polygon mirror in the outer peripheral direction of the rotor boss, the step not locally contacting the polygon mirror.

Thus, before the polygon mirror is fixed, an impact is applied from the outer peripheral direction of the rotor boss,
Even if scratches occur in the outer peripheral direction of the rotor boss, a step that does not contact the polygon mirror is locally provided on the polygon mirror fixing surface side, eliminating the problem of deterioration in flatness of the polygon mirror fixing surface of the rotor boss. can do.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be embodied in the form described in the claims, and comprises a rotating shaft, a rotor boss fixed to the outer periphery of the rotating shaft, a polygon mirror fixed to the rotor boss, A rotor magnet that constitutes a circuit, and a rotor frame that holds the rotor magnet and is fixed to the rotor boss, wherein a step that does not locally contact the polygon mirror is provided on the polygon mirror fixing surface of the rotor boss. Therefore, even if a shock is applied from the outer peripheral direction of the rotor boss in a stage before fixing the polygon mirror and a scratch is generated in the outer peripheral direction of the rotor boss, the step portion which does not locally contact the polygon mirror with respect to the polygon mirror fixing surface. Is provided, the deterioration of the flatness of the polygon mirror fixing surface of the rotor boss can be suppressed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a rotating shaft 1 is rotatably supported by an inner diameter hole of a bearing 3 fixed to a substrate 2, and is one step lower than a surface contacting the polygon mirror 4 to contact the polygon mirror 4. The rotor boss 6 having the step portion 12 not to be fixed is fixed. The polygon mirror 4 and the mirror holding plate 7 are fixed to the upper part of the rotor boss 6 by screws. A rotor frame 9 is fixed to a lower portion of the rotor boss 6, and a rotor magnet 10 is fixed to an inner periphery of the rotor frame 9. The stator coil 11 is disposed on the substrate 2 at a position facing the rotor magnet 10. On the fixed surface of the rotor boss 6 that is in contact with the polygon mirror 4, a step portion 12 that is one step lower than the fixed surface of the polygon mirror 4 and that is not in contact with the polygon mirror 4 is locally provided, and before the polygon mirror 4 is fixed, Therefore, even if an impact is applied from the outer peripheral direction of the rotor boss 6 and a scratch is generated in the outer peripheral direction of the rotor boss 6, the scratch is lowered by one step with respect to the polygon mirror fixing surface and does not directly contact the polygon mirror. Therefore, the flatness of the polygon mirror fixing surface of the rotor boss does not deteriorate.

[0013]

As is apparent from the above description, according to the invention described in the claims, a shock is applied from the outer peripheral direction of the rotor boss before the polygon mirror is fixed, and a flaw is generated in the outer peripheral direction of the rotor boss. However, the surface on which the scratch occurs is a stepped surface that is locally one step lower than the polygon mirror fixing surface and does not contact the polygon mirror, so that the flatness of the polygon mirror fixing surface of the rotor boss is deteriorated. There is no.

Therefore, an advantageous effect that a highly accurate flatness of the polygon mirror after the polygon mirror is fixed can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a motor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional motor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 rotating shaft 2 substrate 3 bearing 4 polygon mirror 5 edge 6 rotor boss 7 mirror holding plate 8 grip ring 9 rotor frame 10 rotor magnet 11 stator coil 12 step

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsuyoshi Kano 1006 Kadoma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A rotating shaft, a rotor boss fixed to an outer periphery of the rotating shaft, a polygon mirror fixed to the rotor boss, a rotor magnet forming a magnetic circuit, and a rotor magnet that holds the rotor magnet and is attached to the rotor boss. A polygon scanner motor comprising: a cup-shaped rotor frame to be fixed; and a stepped portion which is not locally in contact with the polygon mirror at an outer peripheral portion of a surface of the rotor boss on which the polygon mirror is fixed.