JPH09113834A - Method for fixing axis of rotary polyhedral mirror and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the eccentricity of a rotary polyhedral mirror and a motor shaft. SOLUTION: The front end of the motor shaft 2 is provided with a tapered part 2a. The motor shaft 2 is loosely fitted into the central hole 1a of the rotary polyhedral mirror 1 in the state of freely displaceably and elastically holding the motor shaft 2 in a perpendicular direction by a shaft holding unit 12 and the rotary polyhedral mirror 1 is pressed to the reference plane of a supporting plate 10b by a rotary polyhedral mirror pressing unit 14. The tapered part 2a of the motor shaft 2 is press fitted into the central hole 1a of the rotary polyhedral mirror 1 and an adhesive 3 of a photosetting type is packed therein and is cured by light.

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 axis fixing method and apparatus for fixing a rotary polygon mirror of an optical deflector used in a laser beam printer or a laser facsimile to a shaft member such as a motor shaft. It is about.

[0002]

2. Description of the Related Art A general example of an optical deflector used in an image forming apparatus such as a laser printer or a laser facsimile is shown in FIG.
It will be described based on.

A light beam L ₀ generated from the semiconductor laser unit S is linearly condensed by a cylindrical lens C and applied to a rotary polygon mirror 108. Rotating polygon mirror 108
A large part of the light beam deflected and scanned by the rotation of is irradiated onto the reflecting mirror M through the imaging lens F, and is reflected by the reflecting mirror M to reach a photosensitive member on a rotating drum (not shown). The light flux reaching the photoconductor forms an electrostatic latent image on the photoconductor by the main scanning by the rotation of the rotary polygon mirror 108 and the sub-scanning by the rotation of the rotating drum. Further, a part of the light beam deflected and scanned by the rotation of the rotary polygon mirror 108 is detected by the detection mirror B.
Is introduced into the scanning start signal generator D by.

The drive unit for rotating the rotary polygon mirror 108 is
As shown in FIG. 6, a pair of bearings 102a and 102b held by a housing 101 and a motor shaft 103 rotatably supported by these bearings are provided, and the motor shaft 103 has a flange member 104 integrated therewith. York 105a
And a rotor 105 including a driving magnet 105b
The rotor 105 forms a motor together with a stator 107 which is a driving coil on a motor substrate 106 fixed to the housing 101. The rotary polygon mirror 108 uses a spring 109 to attach the flange member 10 to the rotary polygon mirror 108.
4, the motor shaft 103 and the rotor 105 are integrally connected to each other, and the motor shaft 103 and the rotor 105 are rotated by driving the motor.

Recently, it has become necessary to rotate the rotary polygon mirror 108 at a higher speed in accordance with the increase in the speed and accuracy of the deflection scanning device, but with the increase in the rotation speed, the motor shaft 103, The dynamic imbalance due to the nonuniformity of the mass of the rotating body including the rotating polygon mirror 108 and the rotor 105 is increased, and a large vibration is generated. In order to prevent this, weights 110a and 110b made of synthetic resin or the like are adhered to the grooves of the rotor 105 and the rotary polygon mirror 108.

The inner diameter of the center hole 108a of the rotary polygon mirror 108 is about 0.05 mm larger than the outer diameter of the motor shaft 103, and the assembly of the rotary polygon mirror 108 to the rotor 105 is carried out by inserting the motor into the center hole 108a of the rotary polygon mirror. The shaft 103 is loosely fitted, the lower surface of the rotary polygon mirror 108 is brought into contact with the reference surface 104a formed on the upper surface of the flange member 104, and the pressing spring 109 is mounted.

[0007]

However, according to the above-mentioned conventional technique, as described above, the center hole of the rotary polygon mirror is loosely fitted to the motor shaft, and the rotary polygon mirror is flanged by the pressing spring. Since the rotary polygon mirror and the rotor are integrally connected by simply pressing on the reference surface of, the relative position of the rotary polygon mirror and the motor shaft is slightly decentered within the range of the above-mentioned dimensional difference. Tends to be fixed. Therefore, the motor is driven after the rotary polygon mirror is assembled to measure the dynamic imbalance caused by the eccentricity of the rotary polygon mirror with respect to the motor axis and the nonuniform mass of the rotary polygon mirror and the rotor, and eliminate these. The balance is adjusted by attaching a weight for this purpose, and it is devised to prevent whirling vibrations when the rotating polygon mirror is rotated at high speed.

However, even if the balance adjustment as described above is performed, if the materials of the rotary polygon mirror and the motor shaft are different, the relative position of the rotary polygon mirror and the motor shaft changes due to the temperature change after assembly, A dynamic imbalance that differs from the initial balance adjustment occurs. That is, since the motor shaft is mounted in an eccentric state with respect to the center hole of the rotary polygon mirror, for example, when the linear expansion coefficient of the rotary polygon mirror is larger than the linear expansion coefficient of the motor shaft, the environmental temperature has dropped. At times, the inner diameter of the central hole of the rotary polygon mirror is reduced more than the outer diameter of the motor shaft, which causes a force to move the motor shaft toward the central axis of the rotary polygon mirror. As a result, the amount of eccentricity of the motor shaft with respect to the rotary polygon mirror is reduced, and dynamic imbalance that is different from that at the initial adjustment balance occurs and the rotary polygon mirror vibrates.

This tendency becomes more remarkable as the difference in linear expansion coefficient between the rotary polygon mirror and the motor shaft becomes larger. For example, a combination of a ceramic motor shaft and an aluminum rotary polygon mirror, or a stainless motor shaft and plastic. A significant dynamic imbalance occurs in a combination of rotary polygon mirrors manufactured by the manufacturer, which is a major obstacle to speeding up the optical deflecting device.

In addition, the squareness between the reference plane of the flange member supporting the rotary polygon mirror and the motor shaft is strictly controlled so that the rotary polygon mirror is not fixed by being inclined with respect to the motor shaft. It is necessary to avoid an increase in processing cost.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and it is highly accurate and robust without decentering the rotary polygon mirror with respect to a shaft member such as a motor shaft. An object of the present invention is to provide a shaft fixing method and device for a rotary polygon mirror that can be directly assembled.

[0012]

In order to achieve the above object, in the method of fixing the axis of a rotary polygon mirror of the present invention, the shaft member is provided with a tapered portion having the same diameter locally as the central hole of the rotary polygon mirror. The taper portion of the shaft member is inserted into the center hole of the rotary polygon mirror while the rotary polygon mirror is held so as to be displaceable in the radial direction.

It is preferable to insert the taper portion of the shaft member into the central hole of the rotary polygon mirror and then fill the space between the two with an adhesive.

The adhesive is preferably a photocurable adhesive.

The shaft fixing method of the present invention comprises a support means for elastically displaceably holding a shaft member having a taper portion having the same diameter locally as the center hole of the rotary polygon mirror along a predetermined axis. It is characterized in that it has a reference surface intersecting the axis at a predetermined angle, and a pressing means for pressing the rotary polygon mirror on the reference surface.

A light irradiation device for irradiating light for curing the adhesive filled in the central hole of the rotary polygon mirror may be provided.

[0017]

When the rotary polygon mirror is assembled to a shaft member such as a motor shaft, the shaft member is inserted into the central hole of the rotary polygon mirror, and the rotary polygon mirror is pressed against a reference surface thereunder, thereby tapering the shaft member. A predetermined portion of the section is engaged with the inner surface of the central hole of the rotary polygon mirror. In this step, the rotary polygon mirror is only pressed against the reference surface, so that it can be displaced in the radial direction.If the center hole of the rotary polygon mirror is eccentric with respect to the shaft member, it will follow the taper portion of the shaft member. Since the rotary polygon mirror is displaced in the radial direction, the eccentricity is automatically eliminated, and the shaft member and the rotary polygon mirror can be fixed without eccentricity.

If the shaft member is inserted into the central hole of the rotary polygon mirror and then the adhesive is filled, the rotary polygon mirror and the shaft member can be firmly fixed.

By thus directly fixing the rotary polygon mirror and the shaft member with high coaxiality and firmly, the rotary polygon mirror is free from whirling vibrations even if the environmental temperature changes. It is possible to realize a simple optical deflector.

If the adhesive is a photo-curable adhesive, the adhesive can be cured in an extremely short time only by irradiating light.

Support means for elastically displacing a shaft member having a taper portion having the same diameter locally as the central hole of the rotary polygonal mirror along a predetermined axis, and a predetermined angle to the shaft. If a shaft fixing device having a reference surface intersecting with the reference surface and a pressing means for pressing the rotary polygonal mirror on the reference surface is used, the rotary polygonal mirror can be simply mounted by covering the shaft member with the rotary polygonal mirror and pressing the rotary polygonal mirror on the reference surface. Since the assembly of the shaft member is completed and troubles such as damage to the shaft member can be avoided in this process, it can greatly contribute to simplification of the assembly process of the optical deflector and the like.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 illustrates a method for fixing the axis of a rotary polygon mirror according to an embodiment. As shown in FIG. 1A, a rotary polygon mirror 1 and a motor shaft 2 as a shaft member are integrally formed. At the time of coupling, a tapered portion 2a having the same diameter as the central hole 1a of the rotary polygon mirror 1 is provided at the tip of the motor shaft 2, and the tapered portion 2a of the motor shaft 2 is fitted into the central hole 1a of the rotary polygon mirror 1. And then engage a predetermined portion 2b of the taper portion 2a of the motor shaft 2 with the inner surface 1b thereof, and then perform UV-curing bonding between the central hole 1a of the rotary polygon mirror 1 and the taper portion 2a of the motor shaft 2. A photo-curable adhesive 3 such as an agent is filled and cured.

When inserting the taper portion 2a of the motor shaft 2 into the center hole 1a of the rotary polygon mirror 1, the motor shaft 2 is held vertically and the center hole 1 of the rotary polygon mirror 1 is inserted into the taper portion 2a.
a is inserted and the lower surface 1c of the rotary polygon mirror 1 is pressed against a horizontal reference surface. The motor shaft 2 is supported so as to be elastically movable in the vertical direction, and a predetermined portion 2b of the tapered portion 2a thereof is supported.
Engages with the inner surface 1b of the central hole 1a of the rotary polygon mirror 1, and then descends together with the rotary polygon mirror 1. Then, the adhesive 3 is filled between the central hole 1a of the rotary polygon mirror 1 and the tapered portion 2a of the motor shaft 2 to bond the rotary polygon mirror 1 and the motor shaft 2 together. Since the motor shaft 2 is held vertically and the rotary polygon mirror 1 is pressed against the horizontal reference surface in a state of being displaceable in the radial direction, the eccentricity of the motor shaft 2 with respect to the central hole 1a of the rotary polygon mirror 1 is performed in this step. Is automatically solved, and there is no inconvenience that the rotary polygon mirror 1 is inclined and fixed with respect to the motor shaft 2.

A shaft fixing device for fixing the rotary polygon mirror 1 such as a rotary polygon mirror to the motor shaft 2 by such a shaft fixing method is provided on a support body 10 as shown in FIG. 1 (b). A vertical slide guide 11, a shaft holding unit 12 that is a support means that is vertically movable along the slide guide 11, a horizontal block 12a of the shaft holding unit 12, and a fixed block 10a of the support body 10. The spring 13 provided between the support member 10, the support plate 10b provided on the upper surface of the support body 10, and a pressing means for pressing the rotary polygon mirror 1 on a horizontal reference surface formed on the upper surface of the support plate 10b. The rotary polygon mirror pressing unit 14 is provided, and the spring 13 is
The entire shaft holding unit 12 is biased upward to a predetermined height. The shaft holding unit 12 is a V block 12 that vertically holds the motor shaft 2 placed on a horizontal block 12a.
2b and a holding device 12c, the holding device 12c is shown in FIG.
As shown in FIG. 5, a holding member 12e configured to hold the motor shaft 2 between the horizontal cylinder 12d and the V-shaped groove of the V block 12b that moves horizontally by the horizontal cylinder 12d is provided.

The rotary polygon mirror pressing unit 14 has an elevating member 14b for holding a pair of pressing springs 14a and a vertical cylinder 14c for vertically reciprocating the elevating member 14b. The elevating member 14b is driven by the vertical cylinder 14c. It is lowered to press the pressing spring 14a against the rotary polygon mirror 1, and is elastically pressed down to press against the reference surface of the support plate 10b.

Above the rotary polygon mirror pressing unit 14,
A light irradiation device 15 including a condenser lens 15a and an optical fiber 15b connecting the condenser lens 15a to a light source (not shown) is provided.

First, the vertical cylinder 14c of the rotary polygon mirror pressing unit 14 is reversely driven to raise the elevating member 14b and the pressing spring 14a so as to stand by at a predetermined inoperative position. The taper portion 2a of the motor shaft 2 is directed upward, the lower end of the motor shaft 2 is brought into contact with the horizontal block 12a of the shaft holding unit 12, and the motor shaft 2 is rotated vertically while being clamped between the V block 12b and the pressing device 12c. The polygon mirror 1 is engaged with the upper end of the motor shaft 2. That is, the center hole 1 of the rotary polygon mirror 1
The taper portion 2a of the motor shaft 2 is inserted into a and the lower end of the center hole 1a of the rotary polygon mirror 1 is locked near a predetermined portion 2b of the taper portion 2a of the motor shaft 2. At this time, the urging force of the spring 13 or the height of the fixed block 10a of the support body 10 is adjusted in advance so that the bottom surface 1c of the rotary polygon mirror 1 slightly floats above the reference surface of the support plate 10b.

Subsequently, the vertical cylinder 14c of the rotary polygon mirror pressing unit 14 is driven to lower the pressing spring 14a together with the elevating member 14b, and the pressing spring 14a elastically presses down the rotary polygon mirror 1 to support the supporting plate 10b. Press on the reference surface. In this process, the shaft holding unit 12 holding the motor shaft 2 moves along the slide guide 11 with the spring 13
The eccentricity of the rotary polygon mirror 1 and the motor shaft 2 is eliminated and the squareness is corrected during this time. That is, the inner surface 1b of the central hole 1a of the rotary polygon mirror 1 is properly engaged with the predetermined portion 2b of the tapered portion 2a of the motor shaft 2.

Next, a photocurable adhesive 3 is filled between the center hole 1a of the rotary polygon mirror 1 and the motor shaft 2, and light is irradiated from the light irradiation device 15 to the photocurable adhesive 3. Cure.

FIG. 4 is a flow chart showing the above steps, in which the motor shaft 2 is attached to the shaft holding unit 1 in step S1.
2 and supplies the motor shaft 2 to the V block 12 by driving the horizontal cylinder 12d of the shaft holding unit 12 in step S2.
It is sandwiched between b and the pressing member 12e (vertical positioning), the rotary polygon mirror 1 is attached to the upper end of the motor shaft 2 in step S3, the descent of the rotary polygon mirror pressing unit 14 is started in step S4, and in step S5. Rotating polygon mirror pressing unit 14
As the motor shaft 2 and the shaft holding unit 12 holding it are lowered, the rotary polygon mirror 1 is pressed against the reference surface of the support plate 1b in step S6, and the photo-curing adhesive 3 is filled in in step S7. In step S8, the photocurable adhesive 3 is irradiated with light to be cured.

In step S9, the rotary polygon mirror pressing unit 1
4, the horizontal cylinder 12d of the shaft holding unit 12 is reversely driven in step S10 to release the vertical positioning of the motor shaft 2, and in step S11 the rotary polygon mirror 1 with the motor shaft 2 fixed thereto is taken out. According to the present embodiment, which ends in step S12, the center hole of the rotary polygon mirror has the same diameter as the predetermined portion of the tapered portion of the motor shaft, and in the step of engaging the two, the squareness of the rotary polygon mirror and the motor shaft is increased. It is fixed by fixing the rotating polygon mirror and the motor shaft to each other without eccentricity and inclination, and then filling them with a photo-curing adhesive to cure them and bonding the rotating polygon mirror and the motor shaft. Therefore, the work of assembling the rotary polygon mirror to the motor shaft is simple, parts such as a presser spring for assembly are not required, and there is no danger of the motor shaft being eccentrically assembled to the rotary polygon mirror. And mo It has a number of advantages of ensuring a high squareness between the axes of the data. Further, if an ultraviolet curable adhesive is used as the photocurable adhesive, the adhesive can be cured in an extremely short time, so that there is also an advantage that the axis fixing cycle time of the rotary polygon mirror can be significantly shortened.

By fixing the rotary polygon mirror and the motor shaft by such shaft fixing, it is possible to greatly contribute to the high performance and the low cost of the optical deflector. As shown in FIG. 3, instead of providing a relatively long tapered portion at the tip of the motor shaft and inserting the entire tapered portion into the center hole of the rotary polygon mirror as in the present embodiment. , Motor shaft 22
The short taper portion 22a is provided only in the portion that engages with the lower end of the center hole 21a of the rotary polygon mirror 21, and the remaining tip portion 22b is formed in a tubular body having a smaller diameter than the center hole 21a of the rotary polygon mirror 21. You can also

In any case, in order to prevent the trouble that the end of the center hole of the rotary polygon mirror is chipped when the motor shaft is mounted and to facilitate the filling of the photocurable adhesive, the rotary polygon It is desirable to chamfer both the upper and lower ends of the center hole of the mirror.

[0035]

Since the present invention is configured as described above, it has the following effects.

The rotary polygon mirror can be mounted directly with high accuracy and firmly without eccentricity with respect to the motor shaft or the like. This greatly contributes to high performance of the optical deflector and simplification of the assembly process.

[Brief description of the drawings]

FIG. 1 is a view for explaining a shaft fixing method for a rotary polygon mirror and an apparatus therefor according to an embodiment, wherein (a) is a schematic cross-sectional view showing a rotary polygon mirror and a motor shaft fixed by the shaft according to this embodiment;
(B) is a schematic elevational view showing a shaft fixing device of a rotary polygon mirror.

FIG. 2 is a schematic plan view showing the device of FIG. 1 (b).

FIG. 3 is a schematic cross-sectional view showing a rotary polygon mirror and a motor shaft whose shafts are fixed according to a modification.

FIG. 4 is a flowchart showing a shaft fixing method according to the present embodiment.

FIG. 5 is a perspective view showing a general optical deflector.

FIG. 6 is a schematic cross-sectional view of a drive unit of a rotary polygon mirror showing a shaft fixing method according to a conventional example.

[Explanation of symbols]

 1, 21 rotary polygon mirror 1a, 21a center hole 2,22 motor shaft 2a, 22a taper part 3 adhesive 10 support 10b support plate 11 slide guide 12 axis holding unit 12b V block 13 spring 14 rotary polygon mirror pressing unit 15 optical Irradiation device

Claims (5)

[Claims] 1. A shaft member is provided with a taper portion having the same diameter as that of a central hole of a rotary polygon mirror, and the rotary member is held radially displaceably in the shaft member. A method for fixing an axis of a rotary polygon mirror, wherein a taper portion is inserted into the center hole of the rotary polygon mirror. 2. The shaft fixing method for a rotary polygon mirror according to claim 1, wherein a taper portion of the shaft member is inserted into a central hole of the rotary polygon mirror, and an adhesive is filled between the two. 3. The shaft fixing method for a rotary polygon mirror according to claim 2, wherein the adhesive is a photo-curing adhesive. 4. A support means for elastically displacing a shaft member having a taper portion having the same diameter locally as the central hole of the rotary polygonal mirror along a predetermined axis, and a predetermined angle to the shaft. A shaft fixing device having a reference surface that intersects with each other and a pressing unit that presses the rotary polygon mirror on the reference surface. 5. A shaft fixing device according to claim 4, further comprising a light irradiating device for irradiating light for curing the adhesive filled in the central hole of the rotary polygon mirror.