JPH11281908A - Motor for polygon mirror scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress vibration and noise, power consumption, and temperature rise of a motor by projecting a center part of the mirror holder, and providing each end face (upper faces) part with a balance correction space. SOLUTION: Firstly, an outer peripheral part 19 is provided with a step by projecting a center part 18 of a mirror holder, and each end face (upper face) part is provided with a balance correction space 20 so that each upper (lower) side correction plane is plane-separated. And, a rotary body is built in a motor, and a final (built-in balance) fine correction is performed. Therefore, it also becomes possible to correct a couple unbalance, and a final residual unbalance amount is reduced, and it is further possible to prevent vibrations and noises from worsening by arranging spaces for a primary (coarse) correction and a secondary (rotor single volume is dense) correction separately, recovering large unevenness arising from the corrections at these times by the final process, suppressing the movement of an irregular fluid laminar flow boundary layer removal point as far as possible, and reducing generation of vibration of a high speed rotary body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor for a high-speed rotating axial magnetic gap type polygon mirror driving scanner used for laser scanning of a laser beam printer.

[0002]

2. Description of the Related Art An axial magnetic gap type high-speed rotating dynamic air bearing motor used in a conventional polygon mirror scanner motor will be described below with reference to FIG.

FIG. 2 is a cross-sectional side view of a high-speed rotating dynamic air bearing motor.
Are inserted and fixed by bonding. A board 3 is screwed and fixed to an upper portion of the housing 1. A rotating yoke 8 is provided below the substrate 3 via a spacer I5. A plurality of stator coils 5 are bonded and fixed to the upper surface of the substrate 3. Further, a bottom cover 6 is fixed to the bottom side of the bearing bush 2 of the housing 1.

Further, a rotary shaft 7 having two sets of dynamic pressure radial bearings formed of herringbone grooves on its outer peripheral surface is inserted into the bearing bush 2 and rotatably supported. The lower disk 9 of the flange and the rotor yoke is shrink-fitted and fixed to one end side of the rotating shaft 7 so as to rotate integrally with the rotating shaft 7. A ring-shaped rotor magnet 10 is provided on the lower surface of the upper disc 9.
Are fixed, and are arranged to face the stator coil 5 with a slight gap therebetween.

On the upper side of the lower disk 9, a polygon mirror 11 is mounted, and
The screw 4 is used to secure the mirror using a screw 4 for fixing the mirror.

An axial magnetic gap of a type in which a thrust magnetic bearing received by utilizing the magnetic repulsion force of the magnetic levitation magnets I2a and 12b and a thrust sliding bearing 27 using a polyimide resin are used in combination. It is a motor.

Further, a motor sealing cover 13 for sealing the polygon mirror 11 (sealing from the outside air) is fixedly screwed to the housing 1, and a laser light entrance / exit opening is provided therein. A flat glass 16 for sealing (protection from airborne dust) is attached.

The method of correcting the balance of the rotating body of the axial magnetic gap type high-speed rotation motor used in the conventional polygon mirror scanner motor having the above-described configuration can be summarized as follows. After the secondary (rotor single precision) correction, this rotating body is incorporated into the motor, and the motor's rated rotation speed (use condition)
The third (embedded balance) precision correction is performed.

These methods will be described in more detail. First, both the primary (coarse) correction and the secondary (rotor single precision) correction of the rotor alone are performed by adjusting the built-in balance correction surface (swing) of the outer periphery of the mirror holder 14. After the two surfaces (even and evenly balanced) are corrected by the lower surface of the rotor unit 17 (spacer) on the lower surface of the magnet protection ring 24, the rotating body is incorporated into the motor, and almost At the rated rotation speed (in use), tertiary (built-in balance)
Perform precision correction.

The correction surface at this time is a built-in balance correction surface (space) 17 on the outer peripheral portion of the mirror retainer 14, which is used for the (next) (rough) correction and the secondary (rotor single precision) correction of the rotor alone. Since they are located at the same location and at one location, correction of one surface (static / unmatched) is impossible, and correction of two surfaces (even / unmatched) is impossible, and the final residual unbalance amount increases accordingly. .

Further, the outer periphery of the mirror retainer 14 has a large amount of unevenness due to -next (coarse) correction / secondary (rotor precision) repair and tertiary (incorporation balance) precision correction, so that the fluid (air) of the high-speed rotating body is removed. An increase in power consumption due to an increase in the kinematic viscous friction torque and an accompanying increase in motor temperature occur.
Similarly, the irregular movement of the fluid (air) laminar boundary layer peeling point due to the influence of a large amount of unevenness induces vibration of the high-speed rotating body.

[0012]

The axial magnetic gap type high-speed rotation motor used in the conventional polygon mirror scanner motor having the above-described structure has the following problems.

First, typical performances required for such a motor include (1) vibration reduction, (2) noise reduction, and (3)
Although there is a temperature rise suppression, there are many parts common to the factors in (1) vibration reduction and (2) noise reduction, and (3) suppression of temperature rise is closely related to power consumption.

An axial magnetic gap type high-speed dynamic air bearing motor used in the conventional polygon mirror scanner motor described with reference to FIG.
As mentioned above, it is difficult to reduce the final residual unbalance amount, including even and even balance, and irregular fluid (air) laminar boundary layer separation movement induces vibration of the high-speed rotating body. In some cases, the motor characteristics regarding vibration and noise are significantly deteriorated.

Further, the outer peripheral portion of the mirror retainer has a large amount of irregularities due to primary (coarse) correction, secondary (precision motor alone) correction, and tertiary (embedded balance) precise correction, and the fluid (air) ) The kinematic viscous friction torque is increased, causing a problem that power consumption is increased and the temperature rise of the motor is increased accordingly.

[0016]

According to the present invention, a rotor yoke having a rotor magnet fixed to one end of a rotating shaft, a polygon mirror provided on the rotor yoke, and the polygon mirror are connected to the rotor yoke. A polygon retainer having a rotating body having a mirror retainer fixed to the mirror retainer, wherein the mirror retainer fixes the polygon mirror and has a mirror retainer outer peripheral portion having a balance correcting portion; and a central portion of the outer periphery. And a mirror holding center having a balance correcting portion.

According to a second aspect of the present invention, there is provided the motor for a polygon mirror scanner according to the first aspect of the present invention, wherein the central portion of the mirror retainer and the outer peripheral portion of the mirror retainer have a divided structure.

According to a third aspect of the present invention, there is provided the motor for a polygon mirror scanner according to the second aspect of the present invention, wherein the central portion of the mirror retainer is formed of a material having a specific gravity greater than that of the outer periphery of the mirror retainer.

According to a fourth aspect of the present invention, the ratio of the diameter of the central portion of the mirror retainer to the outer peripheral portion of the mirror retainer is substantially inversely proportional to the specific gravity of the material being formed. 2. The motor for polygon mirror scanner according to item 2.

According to a fifth aspect of the present invention, the lower surface of the center portion of the mirror holder has a concave end surface portion, and the concave end surface portion is provided with a balance correcting portion. The motor for polygon mirror scanner described in the above.

According to the sixth aspect of the present invention, the rotating body is covered with a motor sealing cover, and the motor sealing cover is provided with a window for balance measurement. The motor for polygon mirror scanner described in the above.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention solves the two technical problems described above [(1) Reduction of vibration of high-speed rotating body, (2) Reduction of fluid (air) kinematic viscous friction torque of high-speed rotating body]. First, the center part of the mirror holder is protruded to provide a step with the outer peripheral part. At each end surface (upper surface), surface separation is performed on the upper correction surface and the lower correction surface, respectively. A balance correction space was provided so that it could be used.
Then, the rotating body is assembled into the motor, and the final (embedded balance) precision correction is performed at approximately the rated speed of the motor (in use).

Accordingly, even balance can be corrected, the final residual unbalance amount is reduced, and the space for the -order (coarse) correction and the second-order (rough single volume fine) correction is reduced. Separately, large irregularities caused by the correction that occurred at this time are covered in the final step, and thereby irregular fluid (air)
The movement of the laminar boundary layer separation point is suppressed as much as possible, and the induction of vibration of the high-speed rotating body is reduced, and the deterioration of vibration and noise can be prevented. By covering the irregularities that occur at the end of the process, the increase in the fluid (air) dynamic frictional torque of the high-speed rotating body (previously assumed to be the case) was prevented, resulting in reduced vibration and noise. can do.

Conventionally, the balance was corrected using a built-in balance measurement (dummy) cover. However, when the cover was replaced, the air flow (speed and pressure) caused by a slight difference in the shape of the cover was observed. Since the fluctuation of f) is also a cause of vibration of the rotating body, a balance measuring window is provided in the motor sealing cover to prevent the above-described vibration.

The center portion of the mirror retainer of the present invention is protruded to provide a step with the outer peripheral portion, and a balance correction space is provided at each end surface (upper surface), so that the balance can be corrected at the time of the built-in balance correction in the final process. Surface separation becomes possible,
Even imbalance can be precisely corrected by two-sided correction.

In addition, since the upper and lower correction surfaces are to be repaired from the same (upper) direction, the steps need to be formed with a projection at the center so that the work locations do not overlap. Therefore, naturally, the correction radius of the upper correction surface and the correction radius of the lower correction plate are made different. (The upper correction radius is smaller and the lower correction radius is larger.) That is, since the balance correction amount = correction radius × correction weight, when performing even unbalance correction between the upper correction surface and the lower correction surface, the upper correction surface is obtained. In this case, a small correction radius requires a small correction weight. At this time, there is a method of correcting by adding a corrected weight, and a method of shaving off the corrected weight, that is, a method of correcting it by destroying it. In the case of high-speed rotation, the added thing may come off during use, and the shaving off ( Minus) The correction method is more appropriate.

Therefore, the correction volume is made uniform by using a material having a large specific gravity for the center portion and a material having a small specific gravity for the central portion. (Small).

Further, by separately providing a correction surface at the time of primary (rough) correction / secondary (rotor single precision) correction and covering it in the final step, it is possible to perform the following (rough) correction / secondary (rotor single precision). Irregularities generated at the time of correction can prevent an increase in fluid (air) kinematic viscous friction torque of the high-speed rotating body.

Further, by providing a built-in balance measuring window in the motor sealing cover, when the cover is replaced,
Fluctuations in the air flow (speed and pressure) caused by slight differences in the shape of the cover do not induce vibration of the rotating body.

As a result, "windage loss" and "vibration" can be greatly reduced, and the power consumption of the motor can be reduced.

As a result, a rise in the temperature of the remodulator can be suppressed, the characteristics of the motor can be improved with low vibration and low noise, and the ultra-high speed rotation and long life of the motor can be realized with low power consumption.

[Embodiment] An embodiment in which the axial magnetic gap type high-speed rotating dynamic air bearing motor of the present invention is applied to a scanner motor for driving a polygon mirror will be described below with reference to FIG.

That is, the bearing bush 2 is inserted and fixed inside the housing 1. A board 3 is fixedly screwed to the upper part of the housing l. A rotating yoke 8 is provided below the substrate 3 so as to be rotationally driven by the rotating shaft 7 via a spacer 15. A plurality of stator coils 5 are bonded and fixed to the upper surface of the substrate 3.

A bottom cover 6 is fixed to the bottom side of the bearing bush 2 of the housing 1. Inside the bearing bush 2, there are formed two sets of dynamic pressure radial bearings each having a herringbone groove on the outer peripheral surface. The shaft 7 is inserted and rotatably supported. The lower disk 9 of the flange and the rotor yoke is fixed to the upper end of the rotating shaft 7 by shrink fitting, and is configured to rotate integrally with the rotating shaft 7. A ring-shaped rotor magnet 10 is adhesively fixed to the lower surface of the lower disk 9 and is arranged to face the stator coil 5 with a slight gap therebetween.

A borgon mirror 11 is mounted on the upper side of the lower disk 9 and is fixed to the lower disk 9 by screwing with a mirror holding outer peripheral portion 19.

Further, a mirror holding center part 18 is similarly fixed on this by a fastening screw 22. (It is desirable that the height of the mirror holding central portion 18 be 5 mm or more) That is, the upper surface (upper correcting surface 20) of the projected mirror pressing central portion 18 and the upper surface (lower correcting surface) of the mirror pressing outer peripheral portion I9. 21), and a balance repair space (upper correction surface 20 and lower correction surface 21) is provided at each end surface (upper surface), so that two surfaces can be corrected when the balance is incorporated in the final process. Can accurately correct even imbalance.

Generally, a dynamic balance tester (balancer)
It is said that the minimum distance between two surfaces that can separate the corrected surface is 5 mm. If the distance is less than 5 mm, the accuracy of the surface separation of the dynamic balance tester (balancer) decreases, and eventually, even correction of even imbalance is required. It becomes difficult to do.

In addition, since both the upper correction surface 20 and the lower correction surface 21 perform the correction work from the same (upper) direction, the step method in which the center portion is protruded is necessary so that the work locations do not overlap. Therefore, naturally, the upper correction surface 20
And the correction radius of the lower correction surface 21 is different. (The upper correction radius is smaller and the lower correction radius is larger.) Since the balance correction amount is [balance correction amount = correction radius × correction weight], even unbalance correction is performed between the upper correction surface 20 and the lower correction surface 21. In this case, the upper correction surface 20 requires a large amount of correction weight due to the small correction radius. At this time, there are a method of bonding and correcting a weight member corresponding to the correction weight (positive balance) and a method of scraping and correcting a component material corresponding to the correction weight (minus balance). The weight member may be scattered during use, and a shaving (minus balance) correction method is more appropriate.

Therefore, the mirror holding part is divided into a projected central part and an outer peripheral part. A material having a large specific gravity (brass / specific gravity 8.5) is used for the mirror holding central part 18 and the mirror holding outer peripheral part 19 is used. By using a material having a low specific gravity (aluminum / specific gravity 2.7), the part material corresponding to the correction weight on the upper correction surface 20 on the upper surface of the mirror holding center portion 18 having a small correction radius is scraped and corrected.

A counterbore is provided on a joint surface (lower side) of the mirror pressing center portion 18 with the mirror pressing outer peripheral portion I9, and a rotor unit upper correction surface 25 is provided on this surface.

Further, the thrust load is received by a combination of a thrust magnetic bearing, which is received by utilizing the magnetic repulsion force of the magnetic levitation magnets I2a, 12b, and a slide bearing, which is a thrust slide bearing 27 made of a polyimide resin. is there.

A magnet support ring 24 made of brass is provided on the outer periphery of the magnetic levitation magnet 12a, and a rotor unit lower correction surface 26 is provided on a lower end surface thereof.

The primary (concrete) correction and the secondary (precise rotor) correction of the balance are performed using the upper rotor fixing surface 25 and the lower rotor correction surface 26 (in this case, the mirror holding center 18 is The tightening screw 22 is removed, removed from the rotating shaft, and reassembled after the correction). Therefore, in the final process, this is covered, and a large amount of correction occurs during the primary (rough) correction and the secondary (rotor single precision) correction. Asperities no longer appear on the surface of the rotating body, it is possible to prevent the fluid (air) kinematic viscous friction torque of the high-speed rotating body from increasing (conventionally, as a matter of course).

In addition, at this time, the screw head of the projecting mirror fixing tightening screw 4 is also covered at the same time, and it is possible to prevent an increase in the kinematic viscous friction torque by this amount (a conventional result). .

Thereafter, the built-in balance correction in the final step is performed at approximately the rated (used) rotation speed of the motor. This correction can be performed by correcting the even surface imbalance by two-plane correction by setting the corrected surface distance of the two planes to 5 mm or more, and after the primary (coarse) correction of the rotor unit balance and after the secondary (precision rotor) correction However, the correction amount is small, the large unevenness due to the correction is small, and the increase in the kinematic viscous friction torque can be minimized.

In the prior art, the built-in balance in the final step was corrected with a dummy cover dedicated to balance measurement.
3, the air flow (speed and pressure) caused by a slight difference in the cover shape when the cover is replaced
Does not induce vibration of the rotating body.

As a result, "windage loss" and "vibration" can be significantly reduced, and the power consumption of the motor can be reduced.

As a result, it is possible to suppress the rise in the temperature of the motor, to improve the characteristics of the motor with low vibration and low noise, and to realize the ultra-high speed rotation and the long life of the motor with low power consumption.

The thrust load is received by a combination of a thrust magnetic bearing received by utilizing magnetic repulsion force of the magnetic levitation magnets 12a and 12b and a slide bearing by a thrust slide bearing 27 made of polyimide resin. Thus, by making one end of the shaft lightly contact with the sliding bearing, the vertical movement of the shaft is restricted, and the life of the thrust bearing can be extended while ensuring low vibration and high accuracy.

The present invention is not limited to the above embodiment, and it is needless to say that the same operation can be obtained by variously combining the components described in the above embodiment.

[0051]

As described above, according to the present invention, in the motor for the high-speed rotating polygon mirror mirror, the center portion of the mirror holding member for holding the polygon mirror is protruded to provide a step with the outer peripheral portion. When the built-in balance correction was performed at almost the rated (used) speed of the motor,
By setting the correction surface distance between the two surfaces to be 5 mm or more, the even imbalance can be precisely corrected by the two surface correction, thereby significantly reducing the vibration of the motor.

In the final step, large irregularities caused by corrections made at the time of the primary (coarse) correction and the secondary (rotor precision) correction of the balance are covered in the final step, and do not appear on the surface of the rotating body. It was possible to prevent an increase in the fluid (air) kinematic viscous friction torque (which is a conventional phenomenon), and as a result, it was possible to reduce the fluid (air) kinematic viscous friction torque of the high-speed rotating body.

At the same time, the protruding screw head of the mirror fixing screw is also covered at the same time, so that an increase in the kinematic viscous friction torque by that amount can be prevented. This reduced windage loss and reduced power consumption and motor temperature rise.

As described above, since "vibration" and "windage loss" were greatly reduced, the power consumption of the motor was greatly reduced, the temperature of the motor was suppressed from rising, and the vibration and noise were reduced. Improved motor characteristics. Furthermore, ultra-high-speed rotation of the motor has become possible.

[Brief description of the drawings]

FIG. 1 is a side view partially showing a scanner motor for driving a polygon mirror according to an embodiment of the present invention in a longitudinal section.

FIG. 2 is a side view in which a conventional polygon mirror driving scanner motor is partially longitudinally sectioned.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Bearing bush, 3 ... Board, 4 ... Mirror fixing screw, 5 ... Stator coil, 6 ... Bottom cover, 7 ... Rotating shaft, 8 ... Rotating yoke, 9 ... Lower disc, 10
... rotor magnet, 1 l polygon mirror, 12 ... magnetic levitation magnet, 13 ... motor sealing cover, 14 ...
Mirror press, I5 ... spacer, l6 ... flat glass, l
7: Built-in balance correction surface, 18: Mirror holding center portion, 19: Mirror holding outer peripheral portion, 20: Built-in balance upper correction surface, 21: Built-in balance lower correction surface, 2
2 ... fastening screw, 23 ... built-in balance measuring window, 24
... Magnet protection ring, 25 ... Rotary upper surface of rotor alone, 26 ... Rotary lower surface of rotor alone, 27 ... Thrust slide bearing

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02B 7/182 H02K 5/24 Z 7/198 7/08 A H02K 5/24 7/09 7/08 15/16 A 7 / 09 21/24 M 15/16 G02B 7/18 Z 21/24 B

Claims (6)

[Claims] 1. A rotating body having a rotor yoke having a rotor magnet fixed to one end of a rotating shaft, a polygon mirror provided on the rotor yoke, and a mirror holder for fixing the polygon mirror to the rotor yoke. In the motor for a polygon mirror mirror having the mirror press, the mirror press fixes the polygon mirror and has a mirror press outer peripheral portion having a balance correcting portion, and a mirror provided so as to protrude at a center portion of the outer peripheral portion and having a balance correcting portion. A polygon mirror canner motor, comprising: a holding center. 2. The polygon mirror scanner motor according to claim 1, wherein the mirror holding center portion and the mirror holding outer peripheral portion have a divided structure. 3. The polygon mirror scanner motor according to claim 2, wherein said mirror holding center portion is formed of a material having a specific gravity greater than that of said mirror holding outer peripheral portion. 4. The polygon mirror scanner according to claim 2, wherein a ratio of a diameter of the mirror holding center portion to a diameter of the mirror holding outer peripheral portion is substantially inversely proportional to a specific gravity of a material formed. motor. 5. The motor for a polygon mirror scanner according to claim 2, wherein a concave end surface is formed on a lower surface of said mirror holding center portion, and a balance correcting portion is provided on said concave end surface portion. . 6. A motor for a polygon mirror scanner according to claim 1, wherein said rotating body is covered with a motor sealing cover, and said motor sealing cover is provided with a window for balance measurement. .