JP3087482B2 - Rotating polygon mirror drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary polygon mirror driving device used for laser scanning with a laser beam printer (hereinafter abbreviated as LBP) or the like.

[0002]

2. Description of the Related Art In recent years, with the spread of LBP, a rotary polygon mirror driving device has been required to be smaller, thinner, and lower in cost. Under such circumstances, for example, an aluminum or brass sleeve is fixed to an iron substrate or the like instead of a bracket such as a conventional aluminum die-casting, thereby achieving further reduction in thickness and cost. However, it is necessary to maintain high-precision performance with respect to rotation fluctuation (hereinafter referred to as jitter), noise, or surface tilt of the rotary polygon mirror.

A conventional rotary polygon mirror driving device will be described below with reference to FIG. FIG. 2 shows a configuration of a conventional rotary polygon mirror driving device. In FIG. 2, reference numeral 1 denotes a rotating shaft, and a rotor boss 5 to which the rotating polygon mirror 2, the rotor magnet 3, and the rotor yoke 4 are fixed is fixed by a method such as shrink fitting to form a rotor 13. A sleeve 10 having a thrust bearing 11 fixed to one end surface thereof is fitted and fixed to a bracket 7 having a mounting surface 7a of the rotary polygon mirror driving device and cylindrical portions 7b and 7c. A stator yoke 6 which is provided and forms a magnetic path, and a stator substrate 9 on which a stator winding 8 for urging the rotor magnet is fixed between the stator yoke 6 and the rotor magnet 3 are fixed.

Further, a spiral groove for generating a dynamic pressure is formed in the thrust bearing 11, and a herringbone groove for axially supporting the sleeve in the sleeve 10.

[0005] The operation of the rotary polygon mirror driving device constructed as described above will be described below. First, when a current is supplied to the stator winding 8, the rotor magnet 3
Generates an electromagnetic force between them, and the rotor 13 rotates. At this time, a dynamic pressure is generated by the action of the grooves provided in the thrust bearing 11 and the sleeve 10, and the rotating shaft 1 floats and the rotor 13 rotates without contact.

[0006]

However, in the above-mentioned conventional structure, when the sleeve 10 is fitted and fixed to the inner diameter of the bracket 7 or when the sleeve 10 is deformed by caulking of the thrust bearing 11, the outer diameter of the bracket cylindrical portion 7b ( Less than,
(Referred to as a bracket reference outer diameter portion) 7d.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and realizes a low-cost and low-profile rotary polygon mirror driving device without deteriorating the accuracy of the sleeve and eliminating the dimensional change of the reference outer diameter portion of the bracket. The purpose is to provide.

[0008]

In order to solve this object, a rotary polygon mirror driving device according to the present invention has a rotating shaft,
Rotor with magnet and fixed to this rotor
A rotating polygon mirror, and a rotating polygon mirror
Base plate and resin molded on this base plate
And a bracket made of
Supports a sleeve that supports the rotating shaft, and the rotating shaft also
Or one of the sleeves is provided with a dynamic pressure generating means.
The stress based on the press fit of the sleeve is applied to the elasticity of the collar.
And maintain the sleeve inner diameter accuracy
It has a configuration to be described. Alternatively,
The leave has a configuration made of an oil-impregnated metal.
Alternatively, the collar is made thin on the rotor side.
A second circle coaxial with the rotation axis on the first cylindrical portion and the base plate side.
It has a cylindrical portion, and an annular groove is formed on an end surface of the second cylindrical portion.
It has a configuration provided.

[0009]

With this configuration, when the sleeve 10 is fitted and fixed to the inner diameter of the bracket 14 or when the sleeve 10 is deformed by caulking of the thrust cover 17, a dimensional change of the bracket reference outer diameter portion 14b can be suppressed.

[0010]

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

In FIG. 1, reference numeral 1 denotes a rotating shaft having a rounded tip, a rotating polygon mirror 2, a rotor magnet 3, and a rotor yoke 4.
Are fixed by a method such as shrink-fitting to form the rotor 13.

A bracket 14 having a mounting surface 14a for the rotary polygon mirror driving device includes a rotor magnet 3 and a base plate 12 made of a magnetic material forming a magnetic path, and a collar 15 made of resin outsert molded on the base plate 12. A sleeve 10 having a herringbone groove for rotatably supporting a rotating shaft and generating a dynamic pressure;
A stator substrate 9 to which a stator winding 8 for urging the rotor magnet 3 is fixed is fixed between the rotor substrate 3 and the rotor magnet 3.

A thrust plate 16 in contact with the R portion of the rotating shaft 1 and a thrust cover 17 for holding the thrust plate 16 are fixed to one end surface of the sleeve 10. In addition, the collar 15 has a thin first wall formed on the rotor 13 side.
And a second cylindrical portion 15b coaxial with the rotating shaft 1 on the base plate 12 side, and an annular groove 15d is provided on an end surface of the second cylindrical portion 15b of the collar 15. I have.

The operation of the rotary polygon mirror driving device configured as described above will be described. First, when a current is supplied to the stator winding 8, an electromagnetic force is generated between the stator winding 8 and the rotor magnet 3, and the rotor 13 rotates. At this time, a dynamic pressure is generated by the action of the groove provided in the sleeve 10, and the rotor 13 rotates without the rotating shaft 1 contacting in the radial direction.

On the other hand, the rigidity of the collar 15 into which the sleeve 10 is press-fitted and fixed is, for example, approximately 1/4 to 1/8 of aluminum in the case of PPS or the like, so that the rigidity of the sleeve 10 is lost. The change in inner diameter can be suppressed to about 1/20 to 1/40 of the press-in allowance (press-in allowance is 20
If it is μm, it will be only about 0.5 μm due to a change in diameter.)

The sleeve 10 is generally made by processing a copper-based material. Therefore, the linear expansion coefficient of the collar 15 is set between the sleeve 10 and the base plate 11 to maintain the above accuracy over a wide temperature range. Yes, but color 15
Is a resin, which is made possible by controlling the amount of glass fiber contained therein.

As described above, according to the present embodiment, the rotating shaft 1
And a rotor 13 having a rotor magnet 3 and a rotary polygon mirror 2 fixed to the rotor 13. The base plate 12 is provided to face the rotor magnet 3, and is made of a resin outsert on the base plate 12. By providing a sleeve 10 which is fitted and fixed and supports the rotary shaft 1 on a bracket 14 comprising a collar 15 which is a bearing holding portion, the sleeve 10 has excellent rotational accuracy and mechanical accuracy. When the thrust plate 16 is
Can be provided in which the dimensional change of the bracket reference outer diameter portion 14b is suppressed by the deformation of the sleeve 10 due to the caulking of the thrust cover 17 for holding the polygon mirror.

Although the sleeve 10 is a fluid bearing in the embodiment, it goes without saying that the effect is the same even when the sleeve 10 is an oil-containing metal.

[0019]

As described above, the present invention comprises a rotor having a rotating shaft having a rounded end and a magnet, and a rotary polygon mirror fixed to the rotor, and a base provided to face the rotor magnet. A sleeve which is fitted and fixed to a bracket made of a plate and a collar which is a bearing holding portion made of resin inserted into the base plate and which supports the rotary shaft; and an R-shaped tip portion of the rotary shaft fixed to the sleeve and fixed to the sleeve. Providing the abutting thrust plate allows the following: (1) Even if there is a warp in the base plate, the collar is formed based on the warp, so that an absolute inclination can be ensured. (2) The collar is made of resin, the rigidity is lower than that of the metal sleeve, and the coefficient of linear expansion is close to that of the sleeve. In particular, the effect is remarkable when the sleeve has a large change in inner diameter, such as a fluid sleeve, which greatly affects loss and rigidity. (3) The color can be formed without the need for man-hours such as caulking, and the cost can be reduced. (4) When the sleeve is fitted and fixed to the inner diameter of the bracket or when the sleeve is deformed due to caulking of the thrust cover, the dimensional change of the bracket reference outer diameter portion can be suppressed. Thus, an excellent rotary polygon mirror driving device can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rotary polygon mirror driving device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional rotary polygon mirror driving device.

[Explanation of symbols]

 Reference Signs List 1 rotating shaft 2 rotating polygon mirror 3 rotor magnet 10 sleeve 11 thrust bearing 12 base plate 7, 14 bracket 7d, 14b reference outer diameter portion of bracket 15 collar 15b second cylindrical portion of color 15c first cylindrical portion of color 15d Groove 16 Thrust plate 17 Thrust cover

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuyoshi Kano 1006 Kazuma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-60-4617 (JP, A) (58) Investigated Field (Int.Cl. ⁷ , DB name) G02B 26/10

Claims (3)

(57) [Claims] 1. A rotor having a rotating shaft and having a rotor magnet, a rotating polygon mirror fixed to the rotor, a base plate provided to face the rotor magnet, and
Beauty, and a bracket formed of a resin molded collar on the base plate, pivotally supporting the rotary shaft inside the collar
To support the rotating shaft or sleeve.
Either one of them is provided with a dynamic pressure generating means, and the sleeve is press-fitted.
The collar-based stress is absorbed by the elasticity of the collar,
A rotary polygon mirror drive device characterized by maintaining the inner diameter accuracy of the leave . 2. The sleeve according to claim 1, wherein the sleeve is made of an oil-impregnated metal.
The rotating polygon mirror driving device as described in the above. 3. The collar has a thin wall on the rotor side.
The first cylindrical portion and the second cylindrical portion coaxial with the rotation axis on the base plate side.
And an annular groove is provided on an end surface of the second cylindrical portion.
The rotary polygon mirror driving device according to claim 1, wherein