JP2000333404A - Motor and rotating polygon-mirror driver using the same motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor that can maintain perpendicularity of a fixed shaft by preventing loosening of coupling part of the fixed shaft and frame, even when a rotating body rotates at a high speed and also preventing generation of distortion at the frame which holds the fixed shaft. SOLUTION: A fixed shaft inserting hole 11 for insertion of a shaft end part 44 of the fixed shaft 44 is formed to a metal substrate 10 of a motor. The fixed shaft 44 is provided with a stepped part, that collides in contact with the upper surface side of the substrate 10 to specify the insertion depth for the fixed shaft inserting hole 11 of the fixed shaft 42 and a shaft end part 441 to be projected to the lower side from the substrate 10 through the fixed shaft insertion hole 11. This shaft end part 441 is provided with a flat spring and a push nut 12, for clamping the substrate 10 to the stepped part of the fixed shaft 44.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor and a rotary polygon mirror driving device using the motor. More specifically, the present invention relates to a structure for supporting a fixed shaft with respect to a frame in the motor.

[0002]

2. Description of the Related Art Among various motors, for example,
In the motor disclosed in JP-A-31188, a spiral dynamic pressure generating groove is formed on the outer peripheral surface of a fixed shaft or the inner peripheral surface of a rotating body (sleeve) into which the fixed shaft is inserted. A motor using a dynamic pressure bearing that allows air to flow downwards as a radial bearing is disclosed. In the dynamic pressure bearing disclosed therein, a dynamic pressure generating groove is formed in the entire area in the motor axis direction with respect to the outer peripheral surface of the fixed shaft or the inner peripheral surface of the rotating body. In addition, as the dynamic pressure bearing, among those between the fixed shaft and the rotating body, those configured to generate airflow from both sides in the motor axis direction toward the center, or from the center in the motor axis direction to both ends. There is a configuration that generates a heading airflow. Further, there may be a case where a groove penetrating in the axial direction of the motor is formed in order to impart a pressure gradient to the air pressure generated between the outer peripheral surface of the fixed shaft and the inner peripheral surface of the rotating body. When any of these dynamic pressure bearings is used, the rotating body rotates without contact with the fixed shaft.

As a method of fixing a fixed shaft in an upright posture with respect to a motor frame or the like, conventionally, a hole for inserting the fixed shaft into a frame and a shaft end of the fixed shaft is press-fitted into the hole, Alternatively, there is a method of performing crimping after inserting the shaft end of the fixed shaft into the hole.

[0004]

However, when the fixed shaft is fixed to the motor frame, in a conventional configuration using press-fitting or crimping, when the motor is used for high-speed rotation drive of the polygon mirror. In addition, fine vibrations generated by the rotation of the rotor act on the joint between the fixed shaft and the frame, and loosening and rattling are likely to occur. as a result,
The verticality of the fixed axis decreases, causing the polygon mirror to tilt.

When a fixed shaft is press-fitted and fixed in a hole formed in the frame or when the fixed shaft is crimped to the frame, the frame is distorted due to stress during the press-fitting step or crimping. There is also a problem that the verticality of the fixed axis is impaired from the beginning.

[0006] In view of the above problems, an object of the present invention is to provide:
Even when the rotating body rotates at a high speed, the joint between the fixed shaft and the frame does not loosen, and the frame holding the fixed shaft is prevented from being distorted, thereby maintaining the verticality of the fixed shaft. It is to provide a motor capable of operating the motor.

[0007]

In order to solve the above-mentioned problems, in a motor according to the present invention, a lower end is supported by a fixed shaft held by a frame and rotatably around the fixed shaft. The frame includes a fixed shaft insertion hole through which a lower end of the fixed shaft is inserted, and the fixed shaft has a stepped portion that contacts an upper surface of the frame; and the fixed shaft insertion hole. A shaft end penetrating through and projecting downward from the frame,
The shaft end is fastened to the shaft end by sandwiching a spring in a compressed state with the lower surface of the frame, thereby fixing the fixed shaft in an upright state with respect to the frame. It is characterized in that the fixture is attached.

With this configuration, even if the rotor rotates at a high speed and the minute vibration caused by the rotation is transmitted to the joint between the fixed shaft and the frame, a predetermined urging force is applied to the joint by a spring. Therefore, the verticality of the fixed axis does not decrease. Also, since the fixed shaft is fixed to the frame by the urging force of the spring, unlike the case where the fixed shaft is press-fitted and fixed in the hole formed in the frame, or the case where the fixed shaft is crimped to the frame, the press-fitting process or The problem that the frame is distorted by the stress at the time of caulking can be avoided. Therefore, the verticality of the fixed axis can be maintained well both initially and over time.

In the present invention, the spring is, for example, a disc spring or the like.

In the present invention, as the fastener, for example, a push nut attached to the shaft end of the fixed shaft so as to sandwich the spring between the frame and the frame can be used.

In the present invention, a grip ring attached to the shaft end of the fixed shaft so as to sandwich the spring between the frame and the frame may be used as the fastener.

In the present invention, it is preferable that a locking groove for locking with the grip ring is formed at the shaft end of the fixed shaft. With this configuration, it is possible to prevent the grip ring from being displaced.

In the present invention, the spring and the washer may be arranged between the frame and the fastener in this order. In this case, the outer diameter of the washer is determined by the size of the fastener. The outer diameter is larger than the outer diameter of the spring.

In the present invention, a dynamic pressure generating groove is formed on at least one of an outer peripheral surface of the fixed shaft and an inner peripheral surface of a center hole of the rotating body into which the fixed shaft is inserted. The body may be configured to be rotatably supported around the fixed axis by dynamic pressure generated by the dynamic pressure generating groove.

The motor according to the present invention is suitable for a motor for a rotary polygon mirror driving device in which the rotor on which the rotary polygon mirror is formed rotates at high speed because the verticality of the fixed shaft is stable.

[0016]

Embodiments of the present invention will be described with reference to the drawings.

[First Embodiment] FIGS. 1 and 2 are a plan view and a sectional view, respectively, of a polygon mirror driving apparatus using a motor to which the present invention is applied. FIG. 3 is an enlarged half sectional view showing a bearing device and a motor used in the polygon mirror driving device.

(Overall Configuration) Referring to FIGS. 1 and 2, a polygon mirror driving device 1 of the present embodiment generally includes a motor 5 formed on an iron substrate 10, that is, a plate-like frame, and a rotor of the motor 5. A polygon mirror 30 mounted on the motor 20, a motor 5 and a polygon mirror 3
And a case 2 that covers the entirety of the housing. The case 2 is a dustproof and soundproof cover. On the substrate 10,
While the connector 14 for outputting a drive signal to the drive coil 41 is mounted by solder or the like,
A control circuit for driving the polygon mirror driving device 1 is configured.

In FIG. 3, a motor 5 includes a stator 40 having a stator core 42 around which a drive coil 41 is wound and a fixed shaft 44, a center hole 21 into which the fixed shaft 44 is inserted, and a rotor magnet 22 facing the stator core 42. And a rotor 20 (rotating body) including the above.

(Structure of Stator) In this embodiment, in the stator 40, the base end side of the fixed shaft 44 is fitted into the fixed shaft insertion hole 11 formed in the iron substrate 10, and the fixed shaft insertion hole 11 is penetrated. A push nut 12 as a fastener is attached to a protruding shaft end 443 on the lower surface side of the substrate 10 so as to compress the disc spring 134 between the shaft end 443 and the lower surface of the substrate 10. When the push nut 12 is pushed into the shaft end 443 of the fixed shaft 44, the lower tip 12a engages with the shaft end 443, and the return thereof is regulated. In this state, the fixed shaft 4
4 is in a state of being fixed vertically to the substrate 10 by the push nut 12 and the disc spring 13.

In the stator 40, a core holder 43 is fixed on the substrate 10, and a thin stator core 42 is fixed on the outer peripheral surface of the core holder 43 in a stacked state. The drive coil 41 is wound around the pole. Here, as for the core holder 43, the core holder 43 is installed on the substrate 10 with the outer peripheral surface serving as a mounting portion of the stator core 42 and the lower end surface of the cylindrical portion 431 as a contact surface on the substrate 10. Sometimes the fixed step portion 4 of the fixed shaft 44
An annular fixing portion 432 sandwiched between the substrate 42 and the substrate 10 is provided. Therefore, the fixing step portion 44 of the fixed shaft 44
2 is pressed against the upper surface of the substrate 10 via the annular fixing portion 432 of the core holder 43 so that the fixed shaft insertion hole 11 of the fixed shaft 44 is formed.
After determining the insertion depth with respect to the
0, and when fixed via the push nut 12 and the disc spring 13 which is pressed and compressed by the push nut 12, the annular fixing portion 43 of the core holder 43.
2 is sandwiched between the fixing step portion 442 of the fixed shaft 44 and the substrate 10 so that the core holder 43
Fixed on top.

(Structure of Rotor) In this embodiment, the rotor 20 has a rotor main body 25 having a center hole 21 and a rotor main body 2 extending from the rotor main body 25 to the outer peripheral side.
5, a yoke 27 fixed to the lower surface side of the
And a rotor magnet 22 fixed to the inner peripheral surface of the rotor. The rotor magnet 22 is adhesively fixed to the yoke 6 and then caulked and fixed to an annular projection 251 formed on the lower end surface of the rotor body 25. Here, the rotor body 25 is provided for the purpose of improving its wear resistance and corrosion resistance.
Surface treatment such as alumite treatment or plating treatment may be applied. Further, in this embodiment, when the unbalance amount is too large at the time when the rotor 20 is formed, the balance performance of the rotor 20 may be improved by giving a weight or the like to the annular protrusion 251.

A pedestal portion 26 on which a polygon mirror 30 is mounted is formed on the outer peripheral side of the rotor main body 25. The polygon mirror 30 mounted on the pedestal portion 26 is pedestal by a ring-shaped mirror pressing member 50. It is pressed and fixed to the part 26. This mirror pressing member 50 is
The cylindrical portion 250 of the rotor body 25 is passed through the central hole 501, and in this state, the plurality of claw portions 502 projecting inside the central hole 501 are elastically deformed, and the engagement grooves formed on the outer peripheral surface of the cylindrical portion 250. By engaging with 255, the mirror pressing member 50 is fixed to the rotor main body 25. Here, the polygon mirror 30 has its center hole 3
00, the cylindrical portion 256 of the rotor main body 25 is passed through, and when the cylindrical portion 256 of the rotor main body 25 passes through the central hole 300 of the polygon mirror 30, an excessive force is applied to the polygon mirror 30 to cause the polygon mirror 30 to move. The center hole 300 and the cylindrical portion 25 of the rotor body 25 are not deformed.
6, a predetermined clearance is secured. Therefore, the mirror pressing member 50 elastically presses and fixes the polygon mirror 30 toward the pedestal portion 26 by a spring 505 formed on itself (or a spring 505 separately mounted between the polygon mirror 30). I have. Therefore, the polygon mirror 30 is positioned and fixed by the frictional force with the upper surface of the base 26.

For this reason, when the rotor 20 rotates, the centrifugal force received by the rotor 20 and the centrifugal force received by the polygon mirror 30 due to the difference between the outer diameter of the rotor 20 and the outer diameter of the polygon mirror 30 are different. Since there is a difference between them, these members swell independently of each other due to centrifugal force, and the degree differs. As a result, the polygon mirror 30 may be displaced on the pedestal portion 26 of the rotor 20 while the motor 5 repeatedly starts and stops. On the other hand, the mirror pressing member 50 is completely fixed to the fixed shaft 44 and does not deform due to centrifugal force. Therefore, in this embodiment, the mirror pressing member 50
The friction force generated between the polygon mirror 30 and the polygon mirror 30 is made larger than the friction force generated between the polygon mirror 30 and the pedestal portion 26 of the rotor 20. For example, an alumite process, a plating process, a nitriding process, and a coating process are performed on at least the pedestal portion 26 of the rotor 20 on the surface of the rotor 20, and the polygon mirror 30 is formed.
The frictional force generated between the rotor 20 and the pedestal 26 of the rotor 20 is reduced. On the other hand, the mirror pressing member 50
As with the polygon mirror 30, the mirror pressing member 50 and the polygon mirror 3 are made of aluminum.
The frictional force generated between 0 and 0 is increased. Therefore,
Even if the motor 5 is repeatedly started and stopped, the polygon mirror 30 is always positioned by the mirror pressing member 50, so that the polygon mirror 30 is displaced on the pedestal portion 26 of the rotor 20 and the polygon mirror 30 vibrates. Does not occur. Even if the mirror pressing member 50 and the polygon mirror 30 are fixed with an adhesive, the displacement of the polygon mirror 30 on the pedestal portion 26 of the rotor 20 can be prevented.

In this embodiment, the mirror pressing member 50
Has a ring shape having a predetermined width as shown in FIG. The mirror pressing member 50 is generally annular, but has a central hole 50 through which the cylindrical portion 250 passes.
The two points symmetrical with respect to 1 have a shape in which the outer peripheral side is linearly cut, and this part is a cut scheduled part 506 whose width dimension is about 程度 narrower than other parts. . That is, after the polygon mirror 30 is pressed and fixed on the rotor 20 by the mirror pressing member 50, the mirror pressing member 50 is fitted in the engagement groove 255 of the rotor main body 25 even when the polygon mirror 30 is desired to be removed. Therefore, in the present embodiment, a narrow cutting portion 506 is formed in advance on the mirror pressing member 50, and the mirror pressing member 50 has a spring 505 between the mirror pressing member 50 and the polygon mirror 30. The part to be cut 5
If a nipper (not shown) is inserted into 06, the mirror pressing member 50 can be easily cut.
Therefore, since the mirror pressing member 50 can be easily removed from the rotor body 25, the polygon mirror 30 can be removed without damaging it.

(Structure of Thrust Bearing of Bearing Device) In the motor 5 thus configured, the rotor 20 is supported on the fixed shaft 44 by the bearing device including the thrust bearing 8, the radial bearing 7, and the air damper 9 described below. Have been.

First, between the rotor 20 and the stator 40, the magnetic force acting between the magnet 81 disposed at the upper end of the fixed shaft 44 and the magnet 82 disposed at the upper end of the rotor 20, and the stator core 42 and rotor magnet 2
A thrust bearing 8 in which the stator 40 supports the rotor 20 in the thrust direction by using a magnetic force acting between the thrust bearing 8 and the thrust bearing 8. That is, the rotor magnet 22 magnetically attracts the stator core 42 and the rotor 20
And a pair of magnets 81 fixed to the side of the stator 40,
82 are opposed to each other with different poles, and the fixed shaft 44 is
An attempt is made to hold the rotor 20 at a predetermined position in the direction of the motor axis L. As described above, the thrust bearing 8 is configured by using the magnetic force acting at these two locations.
High positioning accuracy in the motor axis L direction. Also,
Since the resonance point in the direction of the motor axis L is high, more stable high-speed rotation is possible.

(Structure of Dynamic Pressure Bearing / Radial Bearing of Bearing Device) Also, a gap formed between the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the rotor 20 between the rotor 20 and the stator 40. Using the dynamic pressure generated in the stator 40
Radial bearing 7 for supporting the rotor 20 in the radial direction
Is configured. Here, on the outer peripheral surface of the fixed shaft 44,
A surface treatment is applied to improve abrasion resistance and seizure resistance.
No. 9966, and a resin coating of polyamideimide.

On the fixed shaft 44, the surface of the polyamide-imide resin coating layer has a counterclockwise direction as viewed from the shaft tip (the direction indicated by the arrow CCW in FIG. 1).
In addition, a dynamic pressure generating groove 441 such as a herringbone or a spiral groove is formed by a method such as cutting. Accordingly, when the rotor 20 rotates counterclockwise as viewed from above, the dynamic pressure generating portion 71 in which the dynamic pressure generating groove 441 is formed is moved by the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral portion of the center hole 21 of the rotor main body 25. Only a downward airflow is generated between the surfaces. Therefore, when the motor 5 is stopped, the rotor 20 that has been slightly floating due to the thrust bearing 8 becomes slightly sinked when it starts rotating, and is held at a magnetically balanced position in the thrust bearing 8. Is done. In this state, since the stator 40 and the rotor 20 are not in contact with each other, the rotor 20 can rotate at a high speed.

In this embodiment, the center hole 2
1 of the outer peripheral surface 440 of the fixed shaft 44, the lower end corresponding to the downstream of the airflow is about 1% of the entire length of the fixed shaft 44.
As shown in FIG. 2, the portion corresponding to / 4 does not have the dynamic pressure generation groove 441 as the pressure increasing portion 450 for increasing the air pressure of the air flow supplied from the dynamic pressure generating portion 71. Therefore, in the radial bearing 7 as the dynamic pressure bearing, the dynamic pressure rigidity (dynamic pressure) is high.

(Configuration of Air Damper of Bearing Device) In the motor 5 configured as described above, the fixed shaft 44 has a large-diameter portion 446 formed at the center in the axial direction, and the upper end is larger than the large-diameter portion 446. A small diameter portion 447 is formed on the side. For this reason, the outer peripheral surface 440 of the fixed shaft 44
In, a step portion 448 is formed between the large diameter portion 446 and the small diameter portion 447. Here, a boundary portion 449 between the large-diameter portion 446 and the small-diameter portion 447 is further deeply cut and dented. Therefore, even if the rotor 20 shifts downward, the boundary portion 449 between the large diameter portion 446 and the small diameter portion 447.
Is not hit by the rotor 20. Such a shape
Since the outer peripheral surface 440 of the fixed shaft 44 can be formed by processing with the same processing machine,
The coaxiality is high in any of the parts.

On the other hand, the inner peripheral surface of the center hole 21 of the rotor 20 also has a large diameter portion 2 at a central portion in the axial direction.
A small diameter portion 217 is formed on the upper end side of the large diameter portion 216. Therefore, on the inner peripheral surface of the center hole 21 of the rotor 20, the large diameter portion 216 and the small diameter portion 2
A step part 218 is formed between the step part 218 and the step 17. Here, a boundary portion 219 between the large diameter portion 216 and the small diameter portion 217
Is cut further to the bottom and dented. In addition, fixed shaft 4
At 4, the corner 444 of the large diameter portion 216 is chamfered. Therefore, even if the rotor 20 is displaced downward, the fixed shaft 44 is attached to the boundary portion 219 between the large diameter portion 216 and the small diameter portion 217.
Corner 444 does not hit. Such a shape can also be formed by processing the inner peripheral surface of the center hole 21 with the same processing machine, so that the coaxiality is high in any part of the center hole 21.

Here, the large diameter portion 216 and the small diameter portion 217 formed on the inner peripheral surface of the center hole 21 of the rotor 20 are:
The large-diameter portion 446 and the small-diameter portion 447 formed on the outer peripheral surface of the fixed shaft 44 are formed to be slightly larger by about 20 μm. Therefore, when the fixed shaft 44 is inserted into the center hole 21 of the rotor 20, the large-diameter portion 44 is formed between the outer peripheral surface of the fixed shaft 44 and the inner peripheral surface of the center hole 21 of the rotor 20.
An annular gap 70 for generating dynamic pressure is formed in a region where the gaps 6 and 216 overlap in the radial direction and the gap dimension is slightly wider than 10 μm. Further, a small diameter portion 44 is formed between the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the center hole 21 of the rotor 20.
In a region where the elements 7 and 217 overlap each other in the radial direction, a gap dimension of an air damper 9 described later is about 10 μm.
Is formed in the annular gap 91 (communication portion) for the air damper. Furthermore, in this embodiment, the small diameter portion 447 of the outer peripheral surface 440 of the fixed shaft 44 and the large diameter portion 447 of the inner peripheral surface of the center hole 21 of the rotor 20 partially overlap in the radial direction. Step portion 448 and rotor 20
The annular air chamber 9 for the air damper is formed by a slightly larger annular space defined by the stepped portion 218 of the center hole 21 of the air damper.
2 (communication part) is formed.

Therefore, in this embodiment, the motor axis L is provided between the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the center hole 21.
Along the direction, the outer peripheral surface 440 of the fixed shaft 44 and the center hole 21
An annular gap 70 (dynamic pressure generating section 71) for generating dynamic pressure between the inner peripheral surfaces of the air gap, an annular air chamber 92 for an air damper communicating with the annular gap 70, and an annular air for the air damper An annular gap 91 for the air damper for communicating the chamber 92 with the outside is formed in this order, and the annular air chamber 92 for the air damper and the annular gap 91 for the air damper constitute the air damper 9 for the rotor 20.

(Operation / Effect of this Embodiment) In the motor 5 configured as described above, when the rotor 20 rotates counterclockwise as viewed from above, the outer peripheral surface 440 of the fixed shaft 44 and the rotor 2
In the annular gap 70 for generating dynamic pressure between the inner peripheral surface of the outer ring 0 and the dynamic pressure generating section 71 in which the dynamic pressure generating groove 441 is formed, the annular gap 91 for the air damper and the annular air chamber 92 for the air damper are externally mounted. And a downward airflow while drawing in air from the outside. The dynamic pressure generated by this air flow is generated between the stator 40 and the rotor 20.
And in a non-contact state in the radial direction. At this time, a dynamic pressure generating groove 441 is formed at the lower end of the outer peripheral surface 440 of the fixed shaft 44.
Is formed, the air pressure of the airflow supplied from the dynamic pressure generating unit is increased by the boosting unit 450. Therefore, in the motor of this embodiment, dynamic pressure rigidity (dynamic pressure) is high instead of using a dynamic pressure bearing as the radial bearing 7. Therefore, the rotation stability of the rotor 2 is high.

Further, while the motor 5 is stopped, the rotor 20 which has slightly floated upward when it starts rotating, sinks slightly downward and is held at a position where magnetic balance is maintained in the thrust bearing 8. In this state, the stator 40
And the rotor 20 are in a completely non-contact state, so that the rotor 20 can rotate at a high speed. Further, since the stator 40 and the rotor 20 are completely out of contact with each other, there is no wear and the like, and the life of the motor 5 can be extended.

However, the thrust bearing 8 utilizing magnetic force is
Since the rigidity is relatively small, the rotor 20 vibrates in the vertical direction due to an external force or the like. However, in the motor 5 of the present embodiment, even when the motor 5 vibrates up and down due to disturbance in the direction of the motor axis L in the air damper 9 including the annular air chamber 92 for air damper and the annular gap 91 for air damper, The air in the annular air chamber 92 is discharged to the outside through the narrow gap 91 for the air damper, or the air gap 92 for the air damper is discharged.
Air from outside passes through the annular air chamber 92 for the air damper.
Get inside. When such exhaust and intake occur, the annular gap 91 for the air damper generates friction with air. As a result, the vibration energy in the vertical direction of the rotor 20 is absorbed, so that the vibration is suppressed.

In the case of the air damper 9 configured in the motor 5 of the present embodiment, the air damper 9 depends on the shape of the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the center hole 21 of the rotor 20. The gap size of the annular gap 91 for the damper and the length dimension in the axial direction of the motor 5 can be arbitrarily designed. Therefore, the motor 5 with the built-in air damper 8 that can freely set the damping rate in the vertical vibration of the rotor 20 can be configured with a small number of parts without performing complicated and troublesome processing.

When a hydrodynamic bearing is used as the radial bearing 7, abrasion powder tends to be generated at the time of starting or stopping. In this embodiment, the abrasion powder is promoted to fall by gravity. The air flow generated by the dynamic pressure generating section 71 is set so as to be supplied downward, so that such abrasion powder is removed from the fixed shaft 44 and the rotor body 25.
Is forcibly pumped downward from between the center hole 21 of
Released outside. Therefore, the fixed shaft 44 and the rotor body 2
The problem that abrasion powder stays with the center hole 21 of 5 and causes seizure can be avoided.

Furthermore, the fixed shaft 44 is vertically fixed to the substrate 10 via the push nut 12 and the disc spring 13 while being inserted into the fixed shaft insertion hole of the substrate 10. For this reason, when the rotor 2 rotates at a high speed, even if the minute vibration caused by this rotation is transmitted to the joint between the fixed shaft 44 and the substrate 10, a predetermined biasing force is applied to the joint by the disc spring 13. Therefore, the verticality of the fixed shaft 44 can be always maintained. Further, since the fixed shaft 44 is fixed to the substrate 10 by the urging force of the disc spring 13, the fixed shaft 44
Is fixed by press-fitting into a hole formed in the substrate 10, or when the fixed shaft 44 is crimped to the substrate 10,
The problem that the substrate 10 is distorted due to the stress during the press-fitting step or the caulking can be avoided. Therefore, the verticality of the fixed shaft 44 can be maintained well both initially and over time.

[Second Embodiment] FIG. 4 is an enlarged sectional view showing a fixed portion of a fixed shaft to a frame in a motor for a polygon mirror driving device according to a second embodiment of the present invention. FIGS. 5A, 5B, and 5C are a plan view of a disc spring, a plan view of a washer, and a plan view of a fastener used for fixing a fixed shaft to a substrate (frame) in the motor according to the present embodiment, respectively. FIG. The motor according to the present embodiment has the same basic configuration as the motor according to the first embodiment, and differs only in the configuration of a fixed portion of the fixed shaft to the substrate. Attached and explained,
Description is omitted.

As shown in FIG. 4, similarly to the first embodiment, the polygon mirror driving device of this embodiment also has a stator 40 in which a fixed shaft insertion hole 11 formed in an iron substrate 10 (plate-shaped frame) is formed. The base end side of the fixed shaft 44 is fitted, and the shaft end portion 443 that penetrates through the fixed shaft insertion hole 11 and projects to the lower surface side of the substrate 10 is mounted on the substrate 10.
A grip ring 19 as a fastener for compressing the disc spring 134 is attached to the lower surface of the disk. Disc spring 13
The washer 18 is arranged between the grip ring 4 and the grip ring 19, and the washer 18 has a larger outer diameter than the disc spring 134 as shown in FIGS. 5A and 5B. Other configurations are the same as those of the first embodiment, and therefore, description thereof will be omitted.

As shown in FIG. 5C, the grip ring 19 has a ring portion 190 having a substantially C-shaped planar shape.
And a notch 197 for passing through the shaft in which a part of the ring portion 190 is cut off, and a pair of engaging claws 192 and 193 extending outward from both ends of the ring portion 190 while being curved. I have.

For this reason, the grip ring 19 has a circular shaft hole 191 smaller in diameter than the locking groove 445 (see FIG. 4) formed in the shaft end 443 of the fixed shaft, and the shaft hole 1.
The two substantially semicircular recesses 19 which catch a key-like jig (not shown) when the notch 197 leading to 91 is expanded.
5, 196 are formed.

Here, as can be seen from FIGS. 5B and 5C, the washer 18 not only has a larger outer diameter than the disc spring 134 but also has a larger outer diameter than the grip ring 19.

In order to fix the grip ring 19 configured as described above to the shaft end 441 of the fixed shaft 44, first, a jig (not shown) is inserted inside the engaging claws 192 and 193 (the concave portion 19).
5, 196), the notch 197 is widened, and in this state, the grip ring 19 is pushed into the shaft end 443 of the fixed shaft 44 from the shaft end to the position of the locking groove 445. Meanwhile, the grip ring 19 is connected to the disc spring 1 via the washer 18.
While being deformed, it is pushed toward the substrate 10.
When the jig is removed from the engagement claws 192 and 1 when the grip ring 19 enters the locking groove 445, the grip ring 18 is fixed by the spring property of the ring portion 191.
4 is stopped by the locking groove 445 of the shaft end 443, and there is no displacement.

As described above, in this embodiment, the fixed shaft 44
It is vertically fixed to the substrate 10 via the grip ring 18 and the disc spring 13 while being inserted into the fixed shaft insertion hole 11 of the substrate 10. Therefore, when the rotor 2 rotates at a high speed, fine vibrations caused by the rotation are generated by the fixed shaft 44 and the substrate 1.
Even when the force is transmitted to the connecting portion with zero, the urging force of the disc spring 13 is applied to this connecting portion, so that the verticality of the fixed shaft 44 can be always maintained. Also, since the fixed shaft 44 is fixed to the substrate 10 by the grip ring 19, the fixed shaft 4
4 is press-fitted into a hole formed in the substrate 10, or the fixed shaft 44 is crimped to the substrate 10, unlike the case in which the substrate 10
Can be avoided. Therefore, the verticality of the fixed shaft 44 can be maintained well both initially and over time.

[Other Embodiments] In the above embodiment, the large-diameter portions 446, 2, and 2 for forming the dynamic pressure generating portion 71 are provided on the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the center hole 21.
16 and small-diameter portions 447 and 217 for forming the annular gap 91 for the air damper, respectively. Contrary to such a configuration, the outer peripheral surface 440 of the fixed shaft 44 and the center hole are formed. A small diameter portion for forming a dynamic pressure generating portion and a large diameter portion for forming an annular gap for an air damper may be formed on the inner peripheral surface of the inner portion 21. Even in such a configuration, the fixed shaft 4
The stepped portion between the small-diameter portion and the large-diameter portion formed on the outer peripheral surface 440 and the stepped portion between the small-diameter portion and the large-diameter portion formed on the inner peripheral surface of the center hole face each other. In this portion, an annular air chamber for an air damper can be formed.

[0049]

As described above, according to the present invention, when the rotor rotates at a high speed, even if the minute vibration caused by the rotation is transmitted to the connecting portion between the fixed shaft and the frame, the connecting portion is provided with the spring. Since the force is applied, the verticality of the fixed axis does not decrease. In addition, since the fixed shaft is fixed to the frame by fasteners, unlike the case where the fixed shaft is press-fitted into the hole formed in the frame or the case where the fixed shaft is crimped to the frame, during the press-fitting process or when caulking. The problem that distortion occurs in the frame due to stress at the time can be avoided. Therefore, the verticality of the fixed axis can be maintained well both initially and over time.

[Brief description of the drawings]

FIG. 1 is a plan view of a polygon mirror driving device using a motor to which the present invention is applied.

FIG. 2 is a sectional view of the polygon mirror driving device shown in FIG.

FIG. 3 is an enlarged half sectional view showing a structure of a fixed shaft and a rotor in the polygon mirror driving device shown in FIG. 1;

FIG. 4 is an enlarged sectional view showing a fixed portion of a fixed shaft to a frame in a motor for a polygon mirror driving device according to a second embodiment of the present invention.

5 (A), (B), and (C) are a plan view of a disc spring, a plan view of a washer, and a clasp used to fix a fixed shaft to a substrate (frame) in the motor shown in FIG. 4, respectively. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polygon mirror drive device 2 Case 5 Motor 8 Thrust bearing 9 Air damper 10 Substrate 11 Fixed shaft insertion hole 12 Push nut (clamp) 13 Disc spring 14 Connector 18 Washer 19 Grip ring (clamp) 20 Rotor (rotating body) 21 Center hole of rotor 22 Rotor magnet 25 Rotor main body 26 Pedestal part 30 Polygon mirror 40 Stator 41 Drive coil 42 Stator core 44 Fixed shaft 43 Core holder 50 Mirror pressing member 70 Annular gap for generating dynamic pressure 71 Dynamic pressure generating part 81, 82 Magnet 91 Annular gap for air damper 92 Annular air chamber for air damper 216 Large diameter portion of center hole of rotor 217 Small diameter portion of center hole of rotor 218 Step portion of center hole of rotor 440 Outer peripheral surface of fixed shaft 441 Dynamic pressure generating groove 442 Step for fixing 443 shaft end 445 engaging groove 446 cut portion of the fixed shaft of the large-diameter portion 447 spring 506 mirror pressing member of the fixed shaft of the small-diameter portion 448 fixed shaft of the stepped portion 450 booster 505 a polygon mirror for fixing the fixed shaft

Claims (8)

[Claims] 1. A motor having a fixed shaft whose lower end is held by a frame and a rotor rotatably supported on the fixed shaft around the fixed shaft, wherein the frame has a lower end side of the fixed shaft. Along with a fixed shaft insertion hole to be inserted, the fixed shaft includes a step portion abutting on the upper surface side of the frame, and a shaft end portion penetrating the fixed shaft insertion hole and protruding downward from the frame, The shaft end is fastened to the shaft end by sandwiching a spring in a compressed state with the lower surface of the frame, thereby fixing the fixed shaft in an upright state with respect to the frame. A motor characterized by a mounting. 2. The motor according to claim 1, wherein the spring is a disc spring. 3. The motor according to claim 1, wherein the fastener is a push nut attached to the shaft end of the fixed shaft so as to sandwich the spring between the frame and the frame. . 4. The motor according to claim 1, wherein the fastener is a grip ring attached to the shaft end of the fixed shaft such that the spring is sandwiched between the frame and the frame. . 5. The motor according to claim 4, wherein a locking groove for locking with the grip ring is formed at the shaft end of the fixed shaft. 6. The method according to claim 1, wherein
The spring and the washer are arranged in this order between the frame and the fastener, and an outer diameter of the washer is larger than an outer diameter of the fastener and an outer diameter of the spring. Motor to do. 7. The method according to claim 1, wherein
A dynamic pressure generating groove is formed on at least one of an outer peripheral surface of the fixed shaft and an inner peripheral surface of a center hole of the rotating body into which the fixed shaft is inserted. A motor which is rotatably supported around the fixed axis by dynamic pressure generated by a groove. 8. A rotary polygon mirror driving device using the motor defined in any one of claims 1 to 7, wherein a rotary polygon mirror is formed on a side of the rotor. Drive.