JP2003222816A - Optical deflector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent various failures caused when the rotational speed of a rotating polygon mirror is increased. <P>SOLUTION: The outer diameter A of an upper magnet unit 22 and the outer diameter B of a lower magnet unit 24 which are provided on a rotary body 20 of the optical deflector are set substantially equal. Further, the outer diameter A of the upper magnet unit 22 of the rotary body 20 and the diameter C of an incircle of the rotating polygon mirror 23 are set substantially equal. Further, the lower magnet unit 24 is composed by covering the main body 24a of the lower magnet with a reinforcing sleeve 24b. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflector used in an image forming apparatus such as a laser printer or a digital copying machine, and more particularly to stably rotating a polygonal mirror for scanning an incident light beam at a high speed. A suitable light deflector.

[0002]

2. Description of the Related Art Conventionally, as an optical deflector used in an image forming apparatus such as a laser printer or a digital copying machine, one disclosed in Japanese Patent Laid-Open No. 5-71532 is known. Here, FIG. 11 shows a side sectional view of the optical deflector described in the above publication. The optical deflector has a cylindrical fixed shaft 101 fixedly arranged in a housing 100 provided in the main body of the image forming apparatus (not shown), and a rotating body 110 rotatably supported by the fixed shaft 101. ing. The rotating body 110 has a sleeve 111 disposed with a slight gap between the rotating body 110 and the fixed shaft 101, and the sleeve 1
11, a ring-shaped magnet 112 fixedly arranged inside the upper part of 11, a rotary polygon mirror 113 fixedly arranged outside the central part of the sleeve 111, and fixedly arranged outside the lower part of the sleeve 111 via a case 114. And a ring-shaped magnet 115. Incidentally, reference numeral 116 is the rotating body 1.
10 is a groove to which a balance weight (not shown) for correcting the eccentricity of the weight of 10 is attached.

A ring-shaped magnet 102 is fixedly disposed outside the upper part of the fixed shaft 101 so as to face a ring-shaped magnet 112 provided on the rotating body 110. A thrust magnetic bearing S that supports the rotating body 110 in the thrust direction is configured. Further, the housing 100 has a ring-shaped magnet 11 provided on the rotating body 110.
5, the coil 103 is fixedly arranged so as to face the ring magnet 115 and the coil 103.
A drive motor M for rotating the rotating body 110 is constituted by. Furthermore, of the sleeve 111 of the rotating body 110, the inner peripheral surface 111a facing the fixed shaft 101 is mirror-finished, while the inner peripheral surface 11 of the sleeve 111 is
1a, the outer peripheral surface 101a of the fixed shaft 101 is formed with a herringbone-shaped groove 104 as shown by a broken line in the figure, and is provided on the inner peripheral surface 111a of the sleeve 111 and the outer peripheral surface 101a of the fixed shaft 101. The groove 104 thus formed constitutes a radial dynamic pressure bearing R that supports the rotating body 110 in the radial direction.

In this optical deflector, when the rotating body 110 is rotated by the drive motor M, the rotating body 110 is supported by the radial dynamic pressure bearing R in a non-contact manner with respect to the fixed shaft 101 at a constant distance, and the thrust is generated. The magnetic bearing S supports the fixed shaft 101 at a constant height. This has the advantage that the height of the optical deflector can be made lower than that of the type using a dynamic pressure bearing as the thrust bearing.

[0005]

By the way, in recent image forming apparatuses, it has been required to increase the image forming speed. The speeding up of the image forming speed is achieved by speeding up the rotating speed of the rotary polygon mirror, but various problems have occurred at that time. Specifically, first, if the rotational speed of the rotary polygon mirror 113, that is, the rotational speed of the rotating body 110 is increased, there is a technical problem that the power consumption of the drive motor M increases.

When the rotating speed of the rotating body 110 is increased, the rotating body 110 easily vibrates, and the rotating polygon mirror 1
There is also a technical problem that the scanning of 13 makes it easy for the latent image formed on the image carrier (not shown) to be displaced or bleed. Incidentally, for example, Japanese Patent Application Laid-Open No. 5-172141 discloses a technique in which the thrust magnetic bearing S is disposed below the rotary polygon mirror 113, but this also cannot prevent displacement of the latent image and bleeding. .

Further, when the rotating speed of the rotating body 110 is increased, slight distortion and angular deviation of the mirror surface formed on the rotating polygon mirror 113 has a large effect, causing blurring of the latent image formed on the image carrier. There is also a technical problem that the deviation easily occurs. In this regard, for example, Japanese Patent Laid-Open No. 11-212
In Japanese Patent Laid-Open No. 017, a blank of a rotary polygon mirror (one that is not mirror-finished) is fixed to a large-diameter portion (a portion having a large diameter) of a rotary shaft, and then the outer periphery of the blank is attached with the rotary shaft. A technique for mirror-finishing the surface is described. However, the fixing strength of the rotary polygonal mirror cannot be increased simply by increasing the diameter of the rotary shaft, so that the angle deviation of the mirror surface is likely to occur during the mirror surface processing, and the above-mentioned technical problem cannot be solved. In addition, JP-A-200
In Japanese Patent Application Laid-Open No. 0-147415, a rotary sleeve made of ceramics is fixed to a blank of a rotary polygonal mirror made of an aluminum alloy by press fitting or shrink fitting, and then is made parallel to the axial direction of the bearing surface of the rotary sleeve. A technique is described in which the outer peripheral surface of the blank is mirror-finished. However, since the above-mentioned shrink fitting and press fitting are weak against heat and centrifugal force, the precision of the mirror surface is extremely deteriorated at high temperature or high speed rotation, and the above technical problem cannot be completely solved.

The present invention has been made to solve the above technical problems, and its purpose is to:
It is intended to prevent various problems that occur when the rotational speed of the rotary polygon mirror is increased.

[0009]

Based on the above object, the inventors of the present invention have made earnest studies, and as a result, in order to reduce the power consumption of the drive motor, it is most efficient to reduce the motor loss. The inventors have found that it is effective to reduce wind loss, which accounts for 80% of the motor loss, and have devised the present invention. Therefore, the optical deflector of the present invention is
A fixed shaft fixedly arranged at the base, a magnetic member for a thrust magnetic bearing, a rotary polygon mirror having a plurality of mirror surfaces formed on its outer peripheral surface, a magnet member for a drive motor, and these magnetic members, a rotary polygon mirror, and a magnet. A rotating body that is rotatably supported by a fixed shaft and includes a sleeve to which a member is attached, and a coil that is fixedly arranged at the base so as to face the magnet member of the rotating body and that constitutes a drive motor for the rotating body together with the magnet member. A member and a bearing component member that is fixedly disposed on the base portion or the fixed shaft to face the magnetic member of the rotating body and that constitutes a thrust magnetic bearing together with the magnetic member. The outer diameter and the outer diameter are set to be substantially the same. Here, when the outer diameter of the magnet member in the rotating body is A and the outer diameter of the magnetic member is B, it is preferable to have a relationship of 0.8 ≦ A / B ≦ 1.1. According to such an optical deflector, since the outer diameter of the magnet member and the outer diameter of the magnetic member are set to be substantially the same, the air resistance during rotation of the rotating body can be reduced.

The optical deflector of the present invention includes a fixed shaft fixedly mounted on the base, a magnetic member for a thrust magnetic bearing, a rotary polygon mirror having a plurality of mirror surfaces formed on its outer peripheral surface, and a drive motor. A magnet member, a magnetic member, a rotary polygon mirror, and a sleeve to which the magnet member is attached, and a rotor that is rotatably supported by a fixed shaft and a magnet member of the rotor that is fixed to the base. A coil member that constitutes a drive motor for the rotating body together with the magnet member, and a bearing component member that is fixedly disposed on the base or the fixed shaft so as to face the magnetic member of the rotating body and that constitutes a thrust magnetic bearing together with the magnetic member. The outer diameter of the magnet member in the rotating body and the diameter of the inscribed circle of the rotary polygon mirror are set to be substantially the same. Here, when the outer diameter of the magnet member in the rotating body is A and the diameter of the inscribed circle of the rotating polygon mirror is C, it is preferable to have a relationship of 0.8 ≦ A / C ≦ 1.1. . According to such an optical deflector, since the outer diameter of the magnet member and the diameter of the inscribed circle of the rotary polygon mirror are set to be substantially the same, the air resistance during rotation of the rotating body can be reduced.

Further, the optical deflector of the present invention includes a fixed shaft fixedly arranged at the base, a magnetic member for a thrust magnetic bearing, a rotary polygon mirror having a plurality of mirror surfaces formed on its outer peripheral surface, and a drive motor. A magnet member, a magnetic member, a rotary polygon mirror, and a sleeve to which the magnet member is attached, and a rotor that is rotatably supported by a fixed shaft and a magnet member of the rotor that is fixed to the base. A coil member that constitutes a drive motor for the rotating body together with the magnet member, and a bearing component member that is fixedly disposed on the base or the fixed shaft so as to face the magnetic member of the rotating body and that constitutes a thrust magnetic bearing together with the magnetic member. The outer diameter of the magnet member in the rotating body and the outer diameter of the magnetic member are set to be substantially the same, and the outer diameter of the magnet member in the rotating body and the diameter of the inscribed circle of the rotating polygon mirror are substantially the same. It is characterized in being configured. Here, when the outer diameter of the magnet member in the rotating body is A, the outer diameter of the magnetic member is B, and the diameter of the inscribed circle of the rotating polygon mirror is C, 0.8 ≦ A / B ≦ 1 And the relationship of 0.8 ≦ A / C ≦ 1.1 is preferable. According to such an optical deflector, the outer diameter of the magnet member, the outer diameter of the magnetic member,
Also, since the diameter of the inscribed circle of the rotary polygon mirror is set to be substantially the same, the air resistance during rotation of the rotating body can be further reduced.

Further, the present inventor has found that it is effective to devise the structure of the thrust bearing in order to reduce the vibration of the rotating body, and has devised the present invention. Therefore, the optical deflector of the present invention comprises a fixed shaft fixedly arranged at the base, a magnetic member for a thrust magnetic bearing, a rotary polygonal mirror having a plurality of mirror surfaces formed on the outer peripheral surface thereof, and a drive motor in order from the top. A rotating body that is rotatably supported by a fixed shaft, and is fixedly arranged at the base portion so as to face the magnet member of the rotating body. A coil member, a bearing component member that is fixedly disposed on a base or a fixed shaft so as to face the magnetic member of the rotating body, and forms a thrust magnetic bearing together with the magnetic member, and a core member around which the coil member is wound. A second bearing constituting member that constitutes a second thrust magnetic bearing together with the magnet member, and the rotating body is
It is characterized in that it is arranged such that its center of gravity is between the thrust magnetic bearing and the second thrust magnetic bearing. According to such an optical deflector, the rotor is rotatably supported by the plurality of thrust magnetic bearings, and the center of gravity of the rotor exists between the plurality of thrust magnetic bearings. Can be suppressed.

Further, the present inventor has found that it is effective to firmly fix the rotary polygon mirror to the rotating body in order to reduce the distortion and angular deviation of the mirror surface formed on the rotary polygon mirror. Then, the present invention was devised. That is, the optical deflector of the present invention comprises a fixed shaft fixedly arranged at the base, a magnetic member for a thrust magnetic bearing, a rotary polygon mirror having a plurality of mirror surfaces formed on its outer peripheral surface, a magnet member for a drive motor, And a rotating member rotatably supported by the fixed shaft, which includes a sleeve to which the magnetic member, the rotary polygon mirror, and the magnet member are attached, and fixedly arranged on the base portion so as to face the magnet member of the rotating member. And a coil member that constitutes a drive motor for the rotating body together with the magnet member, and is fixedly disposed on the base portion or the fixed shaft so as to face the magnetic member of the rotating body, and a thrust magnetic bearing together with the magnetic member. And a bearing component member constituting the
A plastic magnet is used as the magnet member or the magnetic member, and the rotary polygon mirror is provided with a fitting portion for fitting with the plastic magnet. According to such an optical deflector, since the rotary polygon mirror is fixed to the rotating body by inserting the plastic magnet into the fitting portion of the rotary polygon mirror, even when a centrifugal force is applied to the rotary polygon mirror. It is possible to suppress the eccentricity of the rotary polygon mirror and the distortion and angular displacement of the latent image due to the eccentricity.

Further, the above-mentioned optical deflector can be provided with a reinforcing member arranged along the outer peripheral surface of the magnet member. According to such an optical deflector, even when a centrifugal force is applied to the magnet member, the reinforcing member can suppress the eccentricity of the magnet member and the resulting vibration. Further, it is possible to prevent cracks due to deformation of the magnet member.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments shown in the accompanying drawings. First Embodiment FIG. 1 shows a side sectional view of an optical deflector according to a first embodiment to which the present invention is applied, and FIGS. 2 (a) to 2 (c)
Are IIa-IIa, IIb-IIb, IIc-IIc of FIG. 1, respectively.
The line sectional view is shown. In the present embodiment, the optical deflector has a cylindrical fixed shaft 10 fixed to a motor housing (base) 1 by a screw 2, and a rotating body 20 rotatably supported by the fixed shaft 10. ing. Here, the rotating body 20 has a cylindrical sleeve 21 arranged with a slight gap between the rotating body 20 and the fixed shaft 10, and a ring-shaped upper magnet unit (magnetic member fixedly arranged on the upper side of the sleeve 21). ) 22, this upper magnet unit 22
Of the rotary polygonal mirror 23 that is fixedly disposed on the lower side of the sleeve 21 outside the central portion of the sleeve 21, and the lower magnet unit 24 that is fixedly disposed on the lower side of the sleeve 21 below the rotary polygonal mirror 23 ( Magnet member).

The upper magnet unit 22 is
It has an upper magnet main body 22a made of a plastic magnet formed by injection molding, and a ring-shaped groove 22b provided on the upper surface of the upper magnet main body 22a. The ring-shaped groove 22b is a balance weight (made of an adhesive) for correcting the eccentricity of the rotating body 20.
It is for attaching. The lower portion of the upper magnet unit 22 is formed so as to be in close contact with the upper side surface of the rotary polygon mirror 23 during injection molding.

The lower magnet unit 24 also includes a lower magnet body 24a made of a plastic magnet formed by injection molding, and a reinforcing sleeve 24b provided so as to cover the outer peripheral surface of the lower magnet body 24a. The reinforcing sleeve 24b is made of aluminum, but resin or metal may be used. Further, a cutout portion 24c for mounting a balance weight for correcting the eccentricity of the rotating body 20 is also provided on the lower side of the lower magnet body 24a. The upper portion of the lower magnet unit 24 is formed so as to be in close contact with the lower side surface of the rotary polygon mirror 23 during injection molding.

In the present embodiment, the rotary polygon mirror 23
Is made of, for example, an aluminum alloy and has a plurality of mirror surfaces (six surfaces in this embodiment) on the outer periphery (see FIG. 2B). Is provided with a notch 23a that is processed into a tapered shape. Here, the mirror surface height of the rotary polygon mirror 23 is 5.0 mm, and the inclination angle of the notch 23a is about 50 degrees. After the rotary polygon mirror 23 is shrink-fitted to the sleeve 21,
The upper magnet main body 22a and the lower magnet main body 24a, which are injection-molded, are brought into close contact with each other to be fixed to the rotating body 20. The upper magnet body 22a and the lower magnet body 24a are also in close contact with the notch 23a of the rotary polygon mirror 23.

On top of the fixed shaft 10, the rotary body 20
Of the ring-shaped magnet 11 (bearing component) so as to face the upper magnet unit 22 with a slight gap.
Are fixedly arranged, and these ring-shaped magnets 11
The upper magnet unit 22 constitutes a thrust magnetic bearing S that supports the rotating body 20 in the thrust direction. As a method of forming the thrust magnetic bearing S, there is a combination of magnets as in the present embodiment or a combination of a magnet and a magnetic material such as metal, and either method may be adopted. Further, in the present embodiment, the upper magnet unit 2 of the rotating body 20.
Although the ring-shaped magnet 11 is arranged inside 2,
The ring-shaped magnet 11 may be arranged outside the upper magnet unit 22.

On the other hand, a ring-shaped coil 4 is fixedly disposed on the motor substrate 3 provided on the motor housing 1 so as to face the lower magnet unit 24 of the rotating body 20. The lower magnet unit 24 constitutes a drive motor M that rotates the rotating body 20. The position of the coil 4 is not limited to the lower part of the lower magnet unit 24, but may be the side part.

Of the sleeve 21 of the rotary body 20,
The inner peripheral surface 21a facing the fixed shaft 10 is mirror-finished, while the outer peripheral surface 10a of the fixed shaft 10 facing the inner peripheral surface 21a of the sleeve 21 has a herringbone shape by etching or the like. The groove 10b is formed.
The inner peripheral surface 21a of the sleeve 21 and the groove 10b provided on the outer peripheral surface 10a of the fixed shaft 10 constitute a radial dynamic pressure bearing R for bearing the rotating body 20 in the radial direction. As a method of configuring the radial dynamic pressure bearing R, in addition to those described above, for example, the sleeve 21
There is also one in which a herringbone-shaped groove is provided on the inner peripheral surface 21a of the above and the outer peripheral surface 10a of the fixed shaft 10 is mirror-finished, and either one may be adopted. Further, it may be a so-called journal type in which neither groove is provided.

In the present embodiment, the diameter C of the inscribed circle of the rotary polygon mirror 23 shown in FIG. 2B is, for example, 30 mm, and the outer diameter B of the upper magnet unit 22 shown in FIG. Lower magnet unit 24 shown in 2 (c)
The outer diameter A is also set to 30 mm.

Next, the operation of the optical deflector according to this embodiment will be described. When the coil 4 is energized by the start of the image forming operation, the rotating body 20 is rotated by the action of the magnetic force acting between the coil 4 and the lower magnet unit 24 of the rotating body 20. At this time, the rotating body 20 is supported by the radial dynamic pressure bearing R in a non-contact manner with respect to the fixed shaft 10 in the radial direction, and is supported by the thrust magnetic bearing S in a non-contact manner with respect to the fixed shaft 10 in the thrust direction. And
The rotating polygon mirror 23 of the rotating body 20 deflects and scans incident light (not shown) while rotating.

Here, in the present embodiment, the outer diameter A of the lower magnet unit 24 and the upper magnet unit 22 are set.
Since the outer diameter B and the diameter C of the inscribed circle of the rotary polygon mirror 23 are set to the same diameter, it is possible to reduce the frictional resistance with the air when the rotating body 20 rotates, that is, windage loss, As a result, the power consumption of the drive motor M can be reduced.

FIG. 3 shows the ratio of the outer diameter A of the lower magnet unit 24 to the outer diameter B of the upper magnet unit 22,
It shows the relationship with windage torque. As shown in the figure, when the outer diameter A of the lower magnet unit 24 and the outer diameter B of the upper magnet unit 22 are significantly different, the frictional resistance with the air during rotation increases, and the windage torque increases, while 0 In the range of 0.8 ≦ A / B ≦ 1.1,
Wind loss torque can be kept low, especially 0.92 ≦
It is understood that the windage loss torque can be further suppressed in the range of A / B ≦ 1.08.

Further, FIG. 4 shows the lower magnet unit 2
4 shows the relationship between the windage torque and the ratio of the outer diameter A of No. 4 to the diameter C of the inscribed circle of the rotary polygon mirror 23. From the figure, when the outer diameter A of the lower magnet unit 24 and the diameter C of the inscribed circle of the rotary polygon mirror 23 are significantly different, the frictional resistance with the air during rotation increases, and the windage torque increases. On the other hand, in the range of 0.8 ≦ A / C ≦ 1.1, the windage loss torque can be suppressed to a low level, and in particular, 0.9
It is understood that the windage loss torque can be further suppressed in the range of 2 ≦ A / C ≦ 0.96.

The size of the rotary polygon mirror 23 may be appropriately selected, but if the rotary polygon mirror 23 is large, the upper magnet unit 22 and the lower magnet unit 24 must also be large.
The diameter C of the inscribed circle of the rotary polygon mirror 23 is preferably 35 mm or less, because there is a concern that the size of the optical deflector and the main body of the optical deflector become large.

In the present embodiment, the rotary polygon mirror 23
Since the cutouts 23a are provided on both side surfaces of the mirror side end of the
Compared with the mode in which the cutout portion 23a is not provided, surface tilt due to temperature change or centrifugal force change is less likely to occur. Further, since the upper magnet main body 22a and the lower magnet main body 24a made of the plastic magnet are brought into close contact with each other up to the cutout portion 23a of the rotary polygon mirror 23, that is, the portion having the recess (fitting portion), the rotary polygon mirror 23 and the upper magnet main body 22 are attached.
The a and the lower magnet body 24a are in a fitted state. As a result, the rotary polygon mirror 23 is more firmly fixed to the rotating body 20, and eccentricity due to centrifugal force and fluctuations associated therewith are also suppressed.

In the present embodiment, the lower magnet unit 24 is constructed by covering the outer peripheral surface of the lower magnet body 24a with the reinforcing sleeve 24b.
The eccentricity due to the centrifugal force applied to the lower magnet body 24a and the resulting fluctuations are also suppressed. It is also possible to prevent cracking due to deformation of the lower magnet body 24a.

Second Embodiment FIG. 5 shows a rotating body 20 used in an optical deflector according to a second embodiment to which the present invention is applied. FIG. 5A shows the rotating body 20 side. Partial sectional view, FIG. 5 (b) is V of FIG. 5 (a)
It is a b-Vb sectional view. Here, the rotating body 20 according to the present embodiment is substantially the same as that described in the first embodiment, except that the upper magnet body 22a and the lower magnet body 24a are connected by the communicating magnet 25. . In the present embodiment, the first embodiment
The same reference numerals are given to the same components, and detailed description thereof will be omitted.

In the present embodiment, the inner diameter of the opening provided in the rotary polygon mirror 23 is set to be sufficiently larger than the outer diameter of the sleeve 21. As a result, the rotary polygon mirror 2
A gap (through hole) is formed between the sleeve 3 and the sleeve 21, and at this portion, the communicating magnet 25 integrated with the upper magnet body 22a and the lower magnet body 24a is formed.
Is formed, and the upper part, the lower part and the back part of the rotary polygon mirror 23 are fixed by a plastic magnet.
Further, similarly to the first embodiment, tapered notches 23a are provided on both side surfaces of the mirror-side end of the rotary polygon mirror 23, and the plastic magnet is brought into close contact with this portion. .

Next, a method for manufacturing the rotating body 20 according to the present embodiment will be described with reference to FIGS. First, a mold 30 as shown in FIG. 6A is prepared, and the mold 21, the sleeve 21, the blank of the rotary polygon mirror 23 (the outer peripheral surface of which is not mirror-finished), and the reinforcing sleeve 24b. set. In the set state, the sleeve 21 is inserted into the opening provided in the blank of the rotary polygon mirror 23.
Has been inserted. At this time, the sleeve 21, the blank of the rotary polygon mirror 23, and the reinforcing sleeve 24b are
Each of them is positioned at a predetermined position in the mold 30.

Next, as shown in FIG. 6B, the plastic magnet 40 which is heated and melted is injected and injected into the mold 30. At this time, the sleeve 21 and the rotary polygon mirror 2
Since there is a gap between the blank and the blank of No. 3, the melted plastic magnet 40 comes into close contact with the upper side surface, the lower side surface, and the back surface of the blank of the sleeve 21 and the rotary polygon mirror 23. The reinforcing sleeve 24b also comes into close contact with the plastic magnet 40. Here, as the plastic magnet 40, for example, a nylon resin of a plastic serving as a base containing magnet powder made of ferrite is used.

After the plastic magnet 40 injected into the mold 30 is cooled and solidified, the mold 30 is removed.
As a result, as shown in FIG. 6C, the basic unit of the rotating body 20 is completed.

Next, the plastic magnet 40 of the basic unit of the rotating body 20 is magnetized. Specifically, the upper side and the lower side of the blank of the rotary polygon mirror 23 are magnetized respectively, and the upper magnet body 22a of the upper magnet unit 22 and the lower portion of the lower magnet unit 24 are magnetized as shown in FIG. 6 (d). The magnet body 24a is formed. Further, the plastic magnet 40 provided on the back surface of the blank of the rotary polygon mirror 23 is not magnetized but becomes the communication magnet 25.

Then, the outer peripheral surface of the blank of the rotary polygon mirror 23 fixed to the sleeve 21 by the upper magnet body 22a, the lower magnet body 24a, and the communicating magnet 25 (plastic magnet 40) is mirror-finished. At this time, since the blank of the rotary polygon mirror 23 is firmly fixed by the plastic magnet 40, mirror surface processing can be performed parallel to the axial direction of the sleeve 21, and the mirror surface is not tilted during mirror surface processing. Can be prevented. In addition, the rotary polygon mirror 2 with respect to the sleeve 21.
3 is not attached by shrink fitting, but is attached by adhering the plastic magnet 40 tightly, so that the rotary polygon mirror 23 is firmly fixed, and even when in a high temperature environment or during high speed rotation The accuracy can be maintained with high accuracy and the deterioration of rotational vibration can be prevented. Further, a plastic magnet 40 (upper magnet body 22a, lower magnet body 24a, and a communicating magnet 25 formed integrally with these) is provided in a gap (through hole) provided between the sleeve 21 and the rotary polygon mirror 23. , The rotary polygon mirror 23 and the upper magnet main body 22a, the lower magnet main body 24a, and the communicating magnet 25 are fitted together. As a result, the rotary polygon mirror 23 is more firmly fixed to the rotating body 20, and eccentricity due to centrifugal force and fluctuations associated therewith are also suppressed.

FIG. 7 (a) shows that the rotating body 20 according to the present embodiment is attached to the optical deflector described in the first embodiment.
It shows the relationship between the ambient temperature (25 ° C., 70 ° C.) and the face tumble value and vibration value when rotated at a rotation speed of 30,000 rpm. On the other hand, FIG. 7B shows ambient temperatures (25 ° C. and 70 ° C.) when the conventionally used rotating body 20 is attached to the optical deflector described in the first embodiment and rotated at a rotation speed of 30000 rpm. It shows the relationship between the tumble value and the vibration value. Here, as the rotating body 20 which has been conventionally used, the rotary polygon mirror 23 is attached to the sleeve 21.
Is attached by shrink fitting, and an upper magnet unit 22 and a lower magnet unit 24 made of a sintered magnet are attached by an adhesive, respectively.

In the conventional optical deflector using the rotating body 20,
While the value of the surface tilt value at 25 ° C. is 41 (sec), the optical deflector using the rotating body 20 of the present embodiment obtains a highly accurate mirror surface of 9.5 (sec). Be understood. Further, in the conventional optical deflector using the rotating body 20, the increment of the face tilt value when the temperature rises from 25 ° C. to 70 ° C. is 307 (sec), whereas the rotating body of the present embodiment. In the optical deflector using 20, the increment is 8 (sec)
It is understood that is very small, that is, stable regardless of temperature. Further, regarding the vibration value, the optical deflector using the conventional rotating body 20 has a temperature of 25 ° C.
The increase in vibration value when the temperature rises from 0 to 70 ° C is 0.
While it is 60 (μm), the rotating body 2 of the present embodiment
It is understood that in the optical deflector using 0, the increment is as small as 0.02 (μm), that is, it is stable regardless of temperature.

This is because the plastic magnet 40 extends to the notch 23a of the rotary polygon mirror 23, that is, the recessed portion.
It is considered that this is because the mirror surface of the rotary polygon mirror 23 is stabilized against a temperature change by closely contacting.

Further, FIG. 8A shows a distribution (histogram) of the surface tilt accuracy of the rotating body 20 manufactured by the manufacturing method according to the present embodiment, and FIG. The distribution (histogram) of the surface tilt accuracy of the rotating body 20 manufactured by the manufacturing method is shown. In the rotating body 20 manufactured by the conventional manufacturing method, the variation of the surface tilt is large and the average value of the surface tilt is also high, whereas in the rotating body 20 manufactured by the manufacturing method according to the present embodiment, It is understood that the variation of the troubles is small and the average value of the troubles is suppressed to a low level.

In the present embodiment, the communicating magnet 25 is formed between the rotary polygon mirror 23 and the sleeve 21 over the entire peripheral surface, but the present invention is not limited to this and, for example, FIG. a) and IXb- in FIG. 9 (a)
As shown in FIG. 9B which is a sectional view taken along line IXb, the sleeve 2
1 and the rotary polygon mirror 23 are arranged in close contact with each other, a plurality of openings with equal pitches are provided on the side surface of the rotary polygon mirror 23, and a plastic magnet 40 is injected therein to form a communicating magnet 25. You may do it. In such a type, for example, the sleeve 21 and the rotary polygon mirror 23 can be firmly fixed by shrink fitting and then firmly fixed by the injection-molded plastic magnet 40.

Further, a plurality of openings (recesses) of equal pitch which are not communicated with the side portions of the rotary polygon mirror 23 are provided, and the plastic magnet 40 is injected into the openings (recesses) so that the upper magnet main body 22a or the lower magnet main body 24a is inserted. Even if it is formed, the rotary polygon mirror 23 can be firmly fixed. Then, in this case, by injecting the plastic magnet 40 into the plurality of openings,
The rotary polygon mirror 23 and the upper magnet main body 22a and the lower magnet main body 24a can be fitted together. As a result, the rotary polygon mirror 23 is more firmly fixed to the rotating body 20, and eccentricity due to centrifugal force and fluctuations associated therewith are also suppressed.

—Third Embodiment— FIG. 10 is a side sectional view of an optical deflector according to a third embodiment of the present invention. Here, the optical deflector according to the present embodiment is substantially the same as that described in the first embodiment, except that in addition to the thrust magnetic bearing S, a second thrust magnetic bearing S2 is provided below the optical deflector. The point is different. In this embodiment, the same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted. In the present embodiment, the coil 4 that constitutes the drive motor M together with the lower magnet unit 24 of the rotating body 20 is fixedly arranged on the outer side surface of the lower magnet unit 24 and wound around the core 5 made of, for example, a silicon steel plate. It is like this.

In the present embodiment, the core 5 and the lower magnet unit 24 constitute the second thrust magnetic bearing S2 for bearing the rotor 20 in the thrust direction. Further, reference numeral G in the drawing indicates the center of gravity of the rotating body 20, and in the present embodiment, the thrust magnetic bearing S and the second thrust magnetic bearing S2 are arranged vertically with the center of gravity G interposed therebetween. It has become.

Next, the operation of the optical deflector according to this embodiment will be described. When the coil 4 is energized by the start of the image forming operation, the rotating body 20 is rotated by the action of the magnetic force acting between the coil 4 and the lower magnet unit 24 of the rotating body 20. At this time, the rotary body 20 is supported by the radial dynamic pressure bearing R in a non-contact manner with respect to the fixed shaft 10 in the radial direction, and the thrust magnetic bearing S and the second thrust magnetic bearing S2 thrust the rotary body 20 against the fixed shaft 10. It is supported in a non-contact manner. Then, the rotary polygon mirror 23 of the rotary body 20 deflects and scans incident light (not shown) while rotating.

Here, in this embodiment, since the rotor 20 is supported in the thrust direction by the two thrust magnetic bearings S and S2, it is possible to suppress the vibration of the rotor 20 in the vertical direction. Further, since the center of gravity G of the rotating body 20 is between the two thrust magnetic bearings S and S2, it is possible to suppress vibration due to swinging of the rotating body 20.

[0047]

As described above, according to the present invention,
It is possible to prevent various problems that occur when increasing the rotation speed of the rotary polygon mirror.

[Brief description of drawings]

FIG. 1 is a side sectional view of an optical deflector according to a first embodiment.

2 (a), (b), and (c) are IIa-II of FIG. 1, respectively.
It is a sectional view taken along line a, IIb-IIb, and IIc-IIc.

FIG. 3 is a graph showing the relationship between the windage torque and the ratio of the outer diameter A of the lower magnet unit to the outer diameter B of the upper magnet unit.

FIG. 4 is a graph showing the relationship between the windage torque and the ratio of the outer diameter A of the lower magnet unit to the diameter C of the inscribed circle of the rotary polygon mirror.

FIG. 5 is a rotary body according to a second embodiment, where (a) is a side sectional view of the rotary body, and (b) is a Vb-Vb sectional view of (a).

6 (a) to 6 (d) show a method of manufacturing the rotating body according to the second embodiment in the order of steps.

FIG. 7A is a rotary body according to the second embodiment, and FIG.
Attaches a conventional rotating body to the optical deflector, and
It is a chart showing the relationship between the ambient temperature and the face tilt value and the vibration value when rotated at 00 rpm.

FIG. 8 (a) shows the manufacturing method according to the second embodiment.
(B) is a graph showing a distribution of surface tilt values of a rotating body manufactured by a conventional manufacturing method.

FIG. 9 shows a rotating body according to a modified example of the second embodiment,
(A) is a side sectional view of the rotating body, (b) is (a) IXb-IX
It is a b line sectional view.

FIG. 10 is a side sectional view of an optical deflector according to a third embodiment.

FIG. 11 is a side sectional view of a conventional optical deflector.

[Explanation of symbols]

1 ... Motor housing, 4 ... Coil, 5 ... Core, 10 ...
Fixed shaft, 11 ... Ring magnet, 20 ... Rotating body, 2
1 ... Sleeve, 22 ... Upper magnet unit, 22a
... upper magnet body, 23 ... rotating polygon mirror, 23a ... notch, 24 ... lower magnet unit, 24a ... lower magnet body, 24b ... reinforcing sleeve, 25 ... communicating magnet, 30 ... mold, 40 ... plastic magnet,
G ... Center of gravity of rotating body, M ... Drive motor, R ... Radial dynamic pressure bearing, S ... Thrust magnetic bearing, S2 ... Second thrust magnetic bearing

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI theme code (reference) H02K 7/08 H02K 7/09 7/09 7/14 C 7/14 21/16 M 21/16 21 / 24 M 21/24 B41J 3/00 D (72) Inventor Masashi Watanabe 1900 Ifunacho, Suzuka City, Mie Prefecture F Term (reference) within Suzuka Fuji Zerox Co., Ltd. (reference) 2C362 BA04 BA10 BA12 2H045 AA14 AA24 AA28 AA46 5H607 BB01 BB07 BB13 BB14 BB25 CC01 CC05 CC09 DD02 DD05 DD14 DD17 FF01 GG01 GG02 GG09 GG12 GG19 5H621 BB06 GA02 GA16 HH03 JK08 JK15 JK19 5H622 CA01 CA05 DD04 PP18

Claims (9)

[Claims] 1. A fixed shaft fixedly disposed on a base, a magnetic member for a thrust magnetic bearing, a rotary polygon mirror having a plurality of mirror surfaces formed on its outer peripheral surface, a magnet member for a drive motor, and these magnetic members. A rotary polygonal mirror, a rotary body that includes a sleeve to which a magnet member is attached, and is rotatably supported by the fixed shaft; and a magnet member that is fixedly disposed on the base portion so as to face the magnet member of the rotary body. And a coil member that constitutes a drive motor for the rotating body, and a bearing component member that is fixedly disposed on the base portion or the fixed shaft so as to face the magnetic member of the rotating body and that constitutes a thrust magnetic bearing together with the magnetic member. And an outer diameter of the magnet member and an outer diameter of the magnetic member in the rotating body are set to be substantially the same. 2. When the outer diameter of the magnet member in the rotating body is A and the outer diameter of the magnetic member is B, the relationship of 0.8 ≦ A / B ≦ 1.1 is satisfied. The optical deflector according to claim 1, which is characterized in that. 3. A fixed shaft fixedly arranged on the base, a magnetic member for a thrust magnetic bearing, a rotary polygon mirror having a plurality of mirror surfaces formed on its outer peripheral surface, a magnet member for a drive motor, and these magnetic members, A rotary polygonal mirror, a rotary body that includes a sleeve to which a magnet member is attached, and is rotatably supported by the fixed shaft; and a magnet member that is fixedly disposed on the base portion so as to face the magnet member of the rotary body. And a coil member that constitutes a drive motor for the rotating body, and a bearing component member that is fixedly disposed on the base portion or the fixed shaft so as to face the magnetic member of the rotating body and that constitutes a thrust magnetic bearing together with the magnetic member. And an outer diameter of the magnet member in the rotating body and a diameter of an inscribed circle of the rotary polygon mirror are set to be substantially the same. 4. When the outer diameter of the magnet member of the rotating body is A and the diameter of the inscribed circle of the rotating polygon mirror is C, the following relationship is satisfied: 0.8 ≦ A / C ≦ 1.1 The optical deflector according to claim 3, wherein: 5. A fixed shaft fixedly disposed on the base, a magnetic member for a thrust magnetic bearing, a rotary polygon mirror having a plurality of mirror surfaces on its outer peripheral surface, a magnet member for a drive motor, and these magnetic members, A rotary polygonal mirror, a rotary body that includes a sleeve to which a magnet member is attached, and is rotatably supported by the fixed shaft; and a magnet member that is fixedly disposed on the base portion so as to face the magnet member of the rotary body. And a coil member that constitutes a drive motor for the rotating body, and a bearing component member that is fixedly disposed on the base portion or the fixed shaft so as to face the magnetic member of the rotating body and that constitutes a thrust magnetic bearing together with the magnetic member. The outer diameter of the magnet member in the rotating body and the outer diameter of the magnetic member are set to be substantially the same, and the magnet portion in the rotating body. Optical deflector, characterized in that the outer diameter and the diameter of the inscribed circle of the rotating polygon mirror is set to be substantially the same. 6. When the outer diameter of the magnet member in the rotating body is A, the outer diameter of the magnetic member is B, and the diameter of the inscribed circle of the rotating polygon mirror is C, 0.8 ≦ A / B The optical deflector according to claim 5, wherein the optical deflector has a relationship of ≦ 1.1 and 0.8 ≦ A / C ≦ 1.1. 7. A fixed shaft fixedly arranged on a base, a magnetic member for a thrust magnetic bearing, a rotary polygonal mirror having a plurality of mirror surfaces formed on an outer peripheral surface thereof, and a magnet member for a drive motor in order from the top. A rotating body that includes a mounted sleeve and is rotatably supported by the fixed shaft; and a fixed motor that is fixedly disposed on the base portion so as to face the magnet member of the rotating body and that magnet member together with the magnet member. A coil member that constitutes a rotating member, a bearing component member that is fixedly disposed on the base portion or the fixed shaft so as to face the magnetic member of the rotating body, and forms a thrust magnetic bearing together with the magnetic member, and the coil member is wound. A second bearing constituting member that is a core member that is rotated and that constitutes a second thrust magnetic bearing together with the magnet member; and the center of gravity of the rotating body is the thrust. Optical deflector, characterized in that it is arranged so as to be between the magnetic bearing and the second thrust magnetic bearing. 8. A fixed shaft fixedly arranged on a base, a magnetic member for a thrust magnetic bearing, a rotary polygon mirror having a plurality of mirror surfaces formed on its outer peripheral surface, a magnet member for a drive motor, and these magnetic members, A rotary polygonal mirror, a rotary body that includes a sleeve to which a magnet member is attached, and is rotatably supported by the fixed shaft; and a magnet member that is fixedly disposed on the base portion so as to face the magnet member of the rotary body. And a coil member that constitutes a drive motor for the rotating body, and a bearing component member that is fixedly disposed on the base portion or the fixed shaft so as to face the magnetic member of the rotating body and that constitutes a thrust magnetic bearing together with the magnetic member. And a plastic magnet is used as the magnet member or the magnetic member, and the plastic magnet is used as the rotary polygon mirror. Optical deflector, characterized in that is provided with a fitting portion to fit fit. 9. The optical deflector according to claim 1, further comprising a reinforcing member arranged along an outer peripheral surface of the magnet member. vessel.