JPH09127453A - Polygon mirror driving device and its assembling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an excellent plane tilt precision with a low cost by resolving the degradation of plane tilt and planeness as a problem for the use of an inexpensive glass mirror in the driving device used in an LBP. SOLUTION: This driving device is provided with a rotor unit 13 and a stator unit 14 which is provided with a bearing 15 axially supporting a revolving shaft 1, and the rotor unit 13 is provided with a polygon mirror 2 like a thin plate which has two faces facing each other or one face as a reflection face, and a columnar rotor boss 5 to which the polygon mirror 2 is fixed, and a revolving shaft 1 fixed to the center of the rotor boss 5. The rotor boss 5 has a plane part 5a in one end face, and only one end face of the polygon mirror 2 is directly fixed to the plane part 5a by adhesion, and the bearing 15 consists of a fluid bearing to have a constitution capable of plane tilt adjustment.

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 in a laser beam printer (hereinafter abbreviated as LBP).

[0002]

2. Description of the Related Art In recent years, with the spread of LBP, a rotary polygon mirror driving device is required to be smaller and thinner and to have a lower cost. Under such circumstances, prism-shaped polygon mirrors made of shavings such as aluminum are mainly used for rotary polygon mirrors. A structure in which a reflective film is formed and fixed to the rotor has been considered. However, in the method of fixing the groove to the rotor by fixing it (Japanese Patent Laid-Open No. 4-44004), or by fixing the surface facing the reflecting surface to the rotor, the accuracy of the reflecting surface with respect to the rotation axis is However, in order to maintain the flatness of the glass, the precision required for machining the fixed rotor portion is very high, and there is a problem that the cost is increased.

A conventional polygon mirror driving device will be described below with reference to FIG. FIG. 3 shows the configuration of a conventional polygon mirror driving device. Reference numeral 1 denotes a rotor unit 6 in which a rotor boss 12 to which a polygon mirror 2, a rotor magnet 3 and a rotor yoke 4 are fixed by a rotary shaft is fixed by a method such as shrink fitting. Are configured.

A fixing groove 7 is provided on the upper surface 12a of the rotor boss 12, and the polygon mirror 2 is fitted and fixed in the fixing groove 7.

In the polygon mirror driving device configured as described above, the stator unit 16 of the polygon mirror 2 is
Perpendicularity to the mounting surface 16a (hereinafter referred to as "surface tilt")
In order to obtain the above, the fitting surface 7a or 7b of the fixed groove 7 needs to be finished with a precision of submicron with respect to the inner diameter 12b to which the rotating shaft 1 is fixed. Ball bearing 1
7 must be fitted with high precision.

Further, the fixing of the polygon mirror 2 needs to sufficiently hold the rotational force at a higher speed.

[0007]

However, in the above-mentioned conventional configuration, the rotor boss 12 has the fixing groove 7 with high precision in order to obtain the surface inclination of the polygon mirror 2, so that the cost is high, or the strength and the surface inclination at the high speed rotation are included. In order to obtain accuracy, the polygon mirror 2 and the fixed groove 7 may be assembled with an accuracy close to press fitting, but the polygon mirror 2 causes stress distortion and sufficient flatness cannot be obtained, and the fixed groove 7 is used to suppress distortion. If a clearance is provided on the fitting surface of the polygon mirror 2, it is not possible to easily obtain a predetermined surface tilt accuracy. Alternatively, since the surface tilt component due to the gap between the ball bearing 17 and the rotary shaft 1 remains, even if the squareness of the polygon mirror 2 with respect to the rotary shaft 1 is set in the state of the rotor unit 6, sufficient tilt cannot be obtained (for example, (Even if the backlash is 1 μm and the shaft span is 10 mm, the face tilt will occur for 40 arcsec.)
There were various problems such as.

The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide an inexpensive polygon mirror driving device while fixing the glass mirror with low distortion and maintaining the accuracy of surface tilt.

[0009]

In order to achieve this object, a polygon mirror driving device of the present invention has a thin plate-shaped polygon mirror whose opposite two or one surfaces are reflecting surfaces, and the polygon mirror is fixed. A cylindrical rotor boss,
A rotor unit having a rotating shaft fixed to the center of the rotor boss; and a stator unit having a bearing that axially supports the rotating shaft, the rotor boss having a flat surface on one end surface, and the flat surface on the flat surface. Only one end surface of the polygon mirror is directly adhered and fixed, and the bearing is constituted by a fluid bearing so that the surface tilt can be adjusted.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention comprises a thin plate-shaped polygon mirror having two or two opposing surfaces as reflecting surfaces, and a cylindrical rotor boss to which the polygon mirror is fixed. In a configuration including a rotor unit having a rotating shaft fixed to the center of the rotor boss, and a stator unit having a bearing that supports the rotating shaft, one end surface of the rotor boss has a flat surface portion, and the flat surface portion. In the polygon mirror driving device in which only one end surface of the polygon mirror is directly bonded and fixed, and the bearing is a fluid bearing. With this configuration, only one end surface of the polygon mirror is bonded, so that the distortion during bonding is released. It is possible to obtain the precision of the surface tilt without impairing the flatness of the polygon mirror. Furthermore, by using a fluid bearing as the bearing, when the rotating shaft rotates, the rotating shaft is levitated and held by the dynamic pressure of the fluid, so there is no surface tilt component that occurs in the fluid bearing, and the surface tilt accuracy obtained with the rotor unit remains unchanged. Since it can be maintained, it is possible to obtain an excellent accuracy of face-down.

A second aspect of the present invention is the polygon mirror driving device according to the first aspect, wherein the polygon mirror has a reflection film formed on one surface or two opposite surfaces of thin glass transparent glass. By using a thin plate-shaped transparent glass, which can easily achieve high accuracy, compared with the conventional prism-shaped polygon mirror made of shaving aluminum or the like, it is possible to obtain excellent tilt accuracy at low cost.

The invention according to claim 3 is the polygon mirror driving device according to claim 2, which is adhered only by a UV effect type adhesive, whereby a special structural member for fixing the polygon mirror is not required. Adhesion is possible in a short time.

According to a fourth aspect of the present invention, there is provided a polygon mirror driving device in which bonding is performed only at a central portion of one end surface of the polygon mirror. With this configuration, distortion at the time of bonding can be further reduced, It is possible to obtain the tilt error without impairing the flatness of the polygon mirror.

According to a fifth aspect of the invention, a thin plate-shaped polygon mirror having two or two opposing surfaces as reflecting surfaces, and a cylindrical rotor boss to which the polygon mirror is fixed,
A rotor unit having a rotating shaft fixed to the center of the rotor boss and a stator unit having a bearing for supporting the rotating shaft are provided, and one end surface of the rotor boss has a flat surface portion, and the polygon portion is provided on the flat surface portion. In a configuration in which only one end surface of the mirror is directly adhered and fixed, when adhering the polygon mirror, the surfaces other than the one end surface are mechanically made movable, and after adjusting the tilt of the reflection surface with respect to the rotation axis, the adhesion is performed. This is a method for assembling a polygon mirror drive device that is cured and fixed to a rotor unit. When fixing a polygon mirror by this method, it can be adjusted so that it is at a right angle to the rotation axis, and it is fixed to the rotation axis. After adjusting the tilt of the reflecting surface, the adhesive is hardened to ensure a certain surface tilt regardless of the accuracy of the rotor boss, and the shape and processing of the rotor boss can be simplified. Of the cost can be reduced Hakare a.

According to a sixth aspect of the present invention, there is provided an assembly method for a polygon mirror driving device according to the fifth aspect, wherein the polygon mirror is fixed to the rotor unit and then assembled into the stator unit. Since the mirror can be fixed, the influence of the face tilt component generated by the minute gap between the rotary shaft and the bearing can be eliminated, so that the face tilt accuracy can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) In FIG. 1, reference numeral 1 denotes a rotary shaft, and a rotor boss 5 to which a polygon mirror 2, a rotor magnet 3 and a rotor yoke 4 are fixed is fixed by shrink fitting or the like to form a rotor unit 13. A stator unit 14 has a mounting surface 14a and a fluid bearing 15, and the fluid bearing 15 has the rotating shaft 1 rotatably fitted therein.

The upper surface 5a of the rotor boss 5 is a flat surface, and one end surface 2a of the polygon mirror 2 is bonded and fixed to the flat surface portion 5a.

In the polygon mirror driving device configured as described above, the rotary shaft 1 is fixed by the fixing jig 8 in order to obtain a squareness (hereinafter referred to as a plane tilt) with respect to the mounting surface 14a of the polygon mirror 2, and an image is obtained. While the sensor 9 measures the surface inclination, the actuator 10 finely moves the one end surface 2b of the polygon mirror, and when a predetermined surface inclination is obtained, the adhesive 11 applied in advance is cured by UV or heat, and the rotor unit 13 is formed. After that, the rotor unit 13 is fitted into the fluid bearing 15 that supports the rotating shaft of the stator unit 14. Since the fluid bearing 15 floats and holds the rotating shaft 1 when the rotating shaft 1 rotates, there is no surface tilt component generated in the fluid bearing 15, and the rotor unit 13
It is possible to maintain the precision of the trouble obtained in step 3.

As described above, according to this embodiment, when the polygon mirror 2 is fixed, the polygon mirror 2 can be adjusted and fixed so as to be perpendicular to the rotary shaft 1, and only the one end face 2a of the polygon mirror 2 can be fixed. Since the adhesive is adhered, the distortion at the time of adhesion is released, the precision of the surface inclination can be obtained without impairing the flatness of the polygon mirror, and an excellent polygon mirror driving device can be provided. At this time, if the adhesive 11 is provided only at the center of the one end face 2a of the polygon mirror 2, the distortion of the polygon mirror 2 can be further reduced.

Although the bearing is the fluid bearing 15 in the embodiment, it is needless to say that the effects of the present invention are not impaired even if another bearing is used.

[0021]

As described above, according to the present invention, a thin plate-shaped polygon mirror 2 having two or two opposing surfaces as reflecting surfaces and a cylindrical rotor boss 5 to which the polygon mirror 2 is fixed.
A rotor unit 13 having a rotary shaft 1 fixed to the center of the rotor boss 5 and a stator unit 14 having a fluid bearing 15 for supporting the rotary shaft 1; and a flat portion on one end surface 5a of the rotor boss 5. By directly adhering and fixing only one end surface 2a of the polygon mirror 2 to the flat surface portion, (1) an inexpensive polygon mirror 2 can be used, and a predetermined surface tilt regardless of the accuracy of the rotor boss 5. Therefore, the shape and processing of the rotor boss 5 can be simplified and the cost can be reduced. (2) It is possible to minimize the deterioration of the flatness of the polygon mirror 2. (3) The configuration does not require a member for fixing the polygon mirror 2. (4) Since there is no face tilt component generated in the fluid bearing 15,
Adjust the polygon mirror 2 with the rotor unit 13
Adhesion is possible, the process is simplified, and highly accurate trouble can be obtained. It is possible to realize an excellent polygon mirror driving device.

[Brief description of the drawings]

FIG. 1A is a partial top view of a polygon mirror driving device according to an embodiment of the present invention, and FIG.

FIG. 2 is a conceptual diagram of an assembly device of a polygon mirror driving device according to an embodiment of the present invention.

FIG. 3A is a partial top view of a conventional polygon mirror driving device, and FIG.

[Explanation of symbols]

 1 Rotation axis 2 Polygon mirror 3 Rotor magnet 4 Rotor yoke 5,12 Rotor boss 6,13 Rotor unit 7 Fixing groove 11 Adhesive 14,16 Stator unit 14a, 16a Device mounting surface 15 Fluid bearing 17 Ball bearing

Claims (6)

[Claims] 1. A rotor having a thin plate-shaped polygon mirror having opposing two or one surfaces as reflecting surfaces, a cylindrical rotor boss to which the polygon mirror is fixed, and a rotating shaft fixed to the center of the rotor boss. In a configuration including a unit and a stator unit having a bearing that supports the rotating shaft, one end surface of the rotor boss has a flat surface portion, and only one end surface of the polygon mirror is directly bonded and fixed to the flat surface portion, A polygon mirror drive device in which the bearing is a fluid bearing. 2. A polygonal mirror made of thin plate-shaped transparent glass.
The polygon mirror driving device according to claim 1, wherein a reflecting film is formed on one surface or two surfaces facing each other. 3. The polygon mirror driving device according to claim 2, wherein the polygon mirror driving device is adhered only by a UV effect adhesive. 4. A polygon mirror driving device in which bonding is performed only at the center of one end surface of the polygon mirror. 5. A rotor unit having a thin plate-shaped polygon mirror having two or two opposing surfaces as reflecting surfaces, a cylindrical rotor boss to which the polygon mirror is fixed, and a rotating shaft fixed to the center of the rotor boss. And a stator unit having a bearing that axially supports the rotation shaft, one end surface of the rotor boss has a flat surface portion, and only one end surface of the polygon mirror is directly bonded and fixed to the flat surface portion, When bonding the polygon mirror, a surface other than the one end surface is mechanically made movable, the tilt of the reflection surface with respect to the rotation axis is adjusted, and then adhesive curing is performed to fix the polygon mirror driving device to the rotor unit. . 6. The method for assembling a polygon mirror driving device according to claim 5, wherein the polygon mirror is fixed to the rotor unit and then assembled into the stator unit.