JP3875822B2 - Motor and rotating polygon mirror driving apparatus using the motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor and a rotary polygon mirror driving apparatus using the motor. More specifically, the present invention relates to a structure for supporting a fixed shaft for a frame in this motor.
[0002]
[Prior art]
Among various motors, for example, in the motor disclosed in Japanese Patent Application Laid-Open No. 10-31188, the dynamic pressure of the spiral is generated on the outer peripheral surface of the fixed shaft or the inner peripheral surface of the rotating body (sleeve) into which the fixed shaft is inserted. There has been disclosed a motor using a dynamic pressure bearing as a radial bearing in which a groove is formed and air is caused to flow out downward by the dynamic pressure generating groove. In the hydrodynamic bearing disclosed therein, dynamic pressure generating grooves are formed in the entire region in the motor axial direction with respect to the outer peripheral surface of the fixed shaft or the inner peripheral surface of the rotating body. In addition, as a hydrodynamic bearing, other than the fixed shaft and the rotating body, a configuration that generates an air flow from both sides in the motor axial direction to the center, or from the center to both ends in the motor axial direction. There is a configuration that generates an air flow to the front. Furthermore, a groove penetrating in the motor axial direction may be formed in order to apply 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 in a non-contact state with the fixed shaft.
[0003]
In addition, as a method of fixing the fixed shaft to the motor frame or the like in an upright posture, conventionally, a hole for inserting the fixed shaft into the frame is formed, and a shaft end portion of the fixed shaft is press-fitted into the hole, or a hole is inserted into the hole. There is a method of performing caulking after inserting the shaft end of the fixed shaft.
[0004]
[Problems to be solved by the invention]
However, when the fixed shaft is fixed to the motor frame, in the conventional configuration using press-fitting or caulking, when the motor is used for high-speed rotation driving of the polygon mirror, the slight vibration generated by the rotation of the rotor. Acts on the joint between the fixed shaft and the frame, and looseness and rattling are likely to occur. As a result, the perpendicularity of the fixed axis is lowered, and the polygon mirror is tilted.
[0005]
Also, when the fixed shaft is press-fitted and fixed in the hole formed in the frame, or when the fixed shaft is crimped to the frame, the frame is distorted by stress during the press-fitting process or crimping, and the fixed shaft There is also a problem that the verticality is lost from the beginning.
[0006]
In view of the above problems, the problem of the present invention is that even if the rotating body rotates at a high speed, the coupling portion between the fixed shaft and the frame does not loosen and the frame that holds the fixed shaft is distorted. It is an object of the present invention to provide a motor capable of preventing this and maintaining the perpendicularity of the fixed shaft.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the motor according to the present invention, in a motor having a fixed shaft whose lower end is held by a frame and a rotor that is rotatably supported around the fixed shaft. The frame includes a fixed shaft insertion hole through which a lower end side of the fixed shaft is inserted, and the fixed shaft passes through the fixed shaft insertion hole and a stepped portion that contacts the upper surface side of the frame and extends downward from the frame. A shaft end projecting, and the shaft is fixed to the shaft end so that the spring is compressed between the shaft end and the lower surface side of the frame. It is characterized in that a fastener for fixing in an upright state is attached.
[0008]
With this configuration, even if the rotor rotates at a high speed and the slight vibration caused by the rotation is transmitted to the coupling portion between the fixed shaft and the frame, a predetermined urging force is applied to the coupling portion by a spring. The perpendicularity of the fixed axis does not decrease. Also, because the fixed shaft is fixed to the frame by the biasing force of the spring, unlike the case where the 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 problem that the frame is distorted by stress during caulking can be avoided. Therefore, the perpendicularity of the fixed axis can be maintained well both initially and over time.
[0009]
  In the present invention, the spring isThe disc spring is arranged so that the shaft end portion passes through the center, and the inner peripheral side of the disc spring is in contact with the lower surface side of the frame.
[0010]
In the present invention, as the fastener, for example, a push nut attached to the shaft end portion of the fixed shaft so as to sandwich the spring between the frame and the frame can be used.
[0011]
In the present invention, as the fastener, a grip ring attached to the shaft end portion of the fixed shaft so as to sandwich the spring between the frame and the frame can be used.
[0012]
In the present invention, it is preferable that a locking groove for locking with the grip ring is formed at the shaft end portion of the fixed shaft. If comprised in this way, position shift of a grip ring can be prevented.
[0013]
In the present invention, the spring and the washer may be arranged in this order between the frame and the fastener. In this case, the outer diameter of the fastener is the outer diameter of the fastener. The outer diameter of the spring is larger than the outer diameter.
[0014]
In the present invention, a dynamic pressure generating groove is formed on at least one side of the outer peripheral surface of the fixed shaft and the inner peripheral surface of the central hole of the rotating body into which the fixed shaft is inserted, A configuration in which the dynamic pressure generated by the dynamic pressure generating groove is rotatably supported around the fixed shaft can be employed.
[0015]
The motor according to the present invention is suitable for a motor for a rotary polygon mirror drive device in which a rotor on which a rotary polygon mirror is formed rotates at high speed because the perpendicularity of the fixed shaft is stable.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0017]
[Embodiment 1]
1 and 2 are a plan view and a cross-sectional view of a polygon mirror driving device using a motor to which the present invention is applied, respectively. FIG. 3 is an enlarged half-sectional view of a bearing device and a motor used in the polygon mirror driving device.
[0018]
(overall structure)
1 and 2, the polygon mirror driving device 1 of this embodiment generally includes a motor 5 configured on an iron substrate 10, that is, a plate-shaped frame, and a polygon mounted on a rotor 20 of the motor 5. It is comprised from the mirror 30, and the case 2 which covers the motor 5 and the polygon mirror 30 whole, This case 2 is a cover for dustproof and soundproofing. A connector 14 for outputting a drive signal to the drive coil 41 is mounted on the substrate 10 by solder or the like, and a control circuit for driving the polygon mirror drive device 1 is configured.
[0019]
In FIG. 3, the motor 5 includes a stator 40 including a stator core 42 and a fixed shaft 44 around which a drive coil 41 is wound, and a rotor including a center hole 21 into which the fixed shaft 44 is inserted and a rotor magnet 22 facing the stator core 42. 20 (rotary body).
[0020]
(Structure of stator)
  In the present 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 penetrates through the fixed shaft insertion hole 11 on the lower surface side of the substrate 10. Between the protruding shaft end 443 and the lower surface of the substrate 10Belleville spring 13A push nut 12 as a fastener is attached so as to compress the. When the push nut 12 is pushed into the shaft end portion 443 of the fixed shaft 44, the lower tip 12a is engaged with the shaft end portion 443, and the return is restricted. In this state, the fixed shaft 44 is fixed vertically to the substrate 10 by the push nut 12 and the disc spring 13.
[0021]
Further, in the stator 40, a core holder 43 is fixed on the substrate 10, and a thin stator core 42 is fixed in a laminated state on the outer peripheral surface of the core holder 43, and for each salient pole of the stator core 42. The drive coil 41 is wound around. Here, in the core holder 43, the core holder 43 is installed on the substrate 10 with an outer peripheral surface serving as a mounting portion of the stator core 42 and a lower end surface of the cylindrical portion 431 as a contact surface on the substrate 10. An annular fixing portion 432 is sometimes sandwiched between the fixing step portion 442 of the fixing shaft 44 and the substrate 10. Therefore, after the fixing step portion 442 of the fixing shaft 44 is pressed against the upper surface of the substrate 10 via the annular fixing portion 432 of the core holder 43 and the insertion depth of the fixing shaft 44 into the fixing shaft insertion hole 11 is determined, When the 44 is fixed to the substrate 10 via the push nut 12 and the disc spring 13 which is pressed and compressed by the push nut 12, the annular fixing portion 432 of the core holder 43 is used for fixing the fixing shaft 44. The core holder 43 is fixed on the substrate 10 by being sandwiched between the stepped portion 442 and the substrate 10.
[0022]
(Configuration of rotor)
In this embodiment, the rotor 20 includes a rotor body 25 having a center hole 21, a yoke 27 fixed to the lower surface side of the rotor body 25 so as to protrude from the rotor body 25 to the outer periphery side, and an inner periphery of the yoke 27. And a rotor magnet 22 fixed to the surface. After the rotor magnet 22 is bonded and fixed to the yoke 6, the rotor magnet 22 is fixed to the annular protrusion 251 formed on the lower end surface of the rotor body 25 by caulking. Here, the rotor body 25 may be subjected to a surface treatment such as alumite treatment or plating treatment for the purpose of improving its wear resistance and corrosion resistance. In this embodiment, when the amount of unbalance is too large when the rotor 20 is formed, the balance performance of the rotor 20 may be improved by providing a weight or the like to the annular protrusion 251.
[0023]
A pedestal 26 for mounting the polygon mirror 30 is formed on the outer peripheral side of the rotor body 25, and the polygon mirror 30 placed on the pedestal 26 is attached to the pedestal 26 by a ring-shaped mirror pressing member 50. It is pressed and fixed. In this mirror pressing member 50, the cylindrical portion 250 of the rotor main body 25 is passed through the central hole 501, and in this state, the outer peripheral surface of the cylindrical portion 250 while the plurality of claw portions 502 protruding inside the central hole 501 are elastically deformed. The mirror pressing member 50 is fixed with respect to the rotor body 25 by engaging with the engaging groove 255 formed on the rotor body 25. Here, the polygon mirror 30 is in a state where the cylindrical portion 256 of the rotor body 25 is passed through the center hole 300, and excessive force is applied when the cylindrical portion 256 of the rotor body 25 is passed through the center hole 300 of the polygon mirror 30. A predetermined clearance is secured between the center hole 300 and the cylindrical portion 256 of the rotor body 25 so that the polygon mirror 30 is not deformed by being applied to the polygon mirror 30. Accordingly, 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 mounted separately from the polygon mirror 30). Yes. Therefore, the polygon mirror 30 is positioned and fixed by the frictional force with the upper surface of the pedestal portion 26.
[0024]
For this reason, when the rotor 20 rotates, the magnitude between 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 size of the rotor 20 and the outer diameter size of the polygon mirror 30 is small. Therefore, these members swell independently by centrifugal force, and the degree thereof is different. As a result, the polygon mirror 30 may be displaced on the pedestal portion 26 of the rotor 20 while the motor 5 is repeatedly started and stopped. On the other hand, the mirror pressing member 50 is completely fixed to the fixed shaft 44 and is not deformed by centrifugal force. Therefore, in this embodiment, the frictional force generated between the mirror pressing member 50 and the polygon mirror 30 is made larger than the frictional force generated between the polygon mirror 30 and the pedestal portion 26 of the rotor 20. . For example, the alumite treatment, plating treatment, nitriding treatment, and coating treatment are applied to at least the pedestal portion 26 of the rotor 20 on the surface of the rotor 20, and the gap is generated between the polygon mirror 30 and the pedestal portion 26 of the rotor 20. The frictional force is reduced. On the other hand, the mirror pressing member 50 is made of aluminum like the polygon mirror 30, and the frictional force generated between the mirror pressing member 50 and the polygon mirror 30 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. Therefore, the polygon mirror 30 is displaced on the pedestal portion 26 of the rotor 20, and the polygon mirror 30 is moved. The problem of vibration does not occur. Even if the mirror pressing member 50 and the polygon mirror 30 are fixed with an adhesive, the position of the polygon mirror 30 on the pedestal portion 26 of the rotor 20 can be prevented from being displaced.
[0025]
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 has an annular shape as a whole, but two point-symmetrical positions sandwiching the center hole 501 through which the cylindrical portion 250 passes have a shape in which the outer peripheral side is linearly cut. The planned cutting portion 506 has a width dimension that is about ½ that of other portions. 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 engaging groove 255 of the rotor body 25 even if the polygon mirror 30 may be removed. Therefore, in this embodiment, a narrow cutting scheduled portion 506 is formed in advance in the mirror pressing member 50, and the mirror pressing member 50 has a spring 505 between the polygon mirror 30 and the mirror pressing member 50. Since it floats from the upper end surface of the polygon mirror 30, the mirror pressing member 50 can be easily cut by inserting a nipper (not shown) into the scheduled cutting portion 506. Therefore, since the mirror pressing member 50 can be easily removed from the rotor body 25, the polygon mirror 30 can be removed without being damaged.
[0026]
(Configuration of thrust bearing of bearing device)
In the motor 5 configured as described above, the rotor 20 is supported on the fixed shaft 44 by a bearing device including a thrust bearing 8, a radial bearing 7, and an air damper 9 described below.
[0027]
First, between the rotor 20 and the stator 40, the magnetic force acting between the magnet 81 disposed at the upper end portion of the fixed shaft 44 and the magnet 82 disposed at the upper end portion of the rotor 20, and the stator core 42 and the rotor. A thrust bearing 8 in which the stator 40 supports the rotor 20 in the thrust direction is configured by using a magnetic force acting between the magnet 22 and the magnet 22. That is, the rotor magnet 22 magnetically attracts the stator core 42, and a pair of magnets 81 and 82 fixed to the rotor 20 and the stator 40 face each other with different poles, and the fixed shaft 44 is a motor. An attempt is made to hold the rotor 20 at a predetermined position in the direction of the axis L. Thus, since the thrust bearing 8 is configured using the magnetic force acting at these two locations, the positioning accuracy in the motor axis L direction is high. Further, since the resonance point in the motor axis L direction is high, more stable high-speed rotation is possible.
[0028]
(Configuration of bearing device dynamic pressure bearing / radial bearing)
In addition, between the rotor 20 and the stator 40, the stator 40 uses the dynamic pressure generated in the gap formed between the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the rotor 20 to cause the stator 40 to move the rotor 20. A radial bearing 7 is configured to be supported in the radial direction. Here, the outer peripheral surface of the fixed shaft 44 is subjected to a surface treatment in order to improve the wear resistance and seizure resistance. Such a surface treatment is performed by, for example, a polyamideimide disclosed in JP-A-7-279966. Resin coating.
[0029]
In the fixed shaft 44, a dynamic pressure such as a herringbone or a spiral groove is generated on the surface of the polyamideimide resin coating layer in a counterclockwise direction when viewed from the shaft tip (direction indicated by an arrow CCW in FIG. 1). The groove 441 is formed by a method such as cutting. Therefore, 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 connected to the outer peripheral surface 440 of the fixed shaft 44 and the inner periphery of the center hole 21 of the rotor body 25. Only a downward air flow is generated between the surfaces. Therefore, while the motor 5 is stopped, the rotor 20 that is slightly lifted by the thrust bearing 8 becomes slightly depressed when the rotation starts, 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 be rotated at a high speed.
[0030]
Further, in this embodiment, the lower end side corresponding to the downstream side of the air flow in the outer peripheral surface 440 of the fixed shaft 44 located in the center hole 21 of the rotor 20 corresponds to about ¼ of the total length of the fixed shaft 44. As shown in FIG. 2, the dynamic pressure generating groove 441 is not formed as the pressure increasing portion 450 for increasing the air pressure of the air flow supplied from the dynamic pressure generating portion 71. For this reason, in the radial bearing 7 as a dynamic pressure bearing, dynamic pressure rigidity (dynamic pressure) is high.
[0031]
(Configuration of bearing device air damper)
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 a small-diameter portion 447 formed on the upper end side of the large-diameter portion 446. Therefore, a stepped portion 448 is formed between the large diameter portion 446 and the small diameter portion 447 on the outer peripheral surface 440 of the fixed shaft 44. Here, the boundary portion 449 between the large-diameter portion 446 and the small-diameter portion 447 is further etched and recessed. Therefore, even if the rotor 20 is displaced downward, the rotor 20 does not hit the boundary portion 449 between the large diameter portion 446 and the small diameter portion 447. Since such a shape can be formed by processing the outer peripheral surface 440 of the fixed shaft 44 with the same processing machine, the coaxiality is high in any part of the fixed shaft 44.
[0032]
On the other hand, a large-diameter portion 216 is formed at the central portion in the axial direction on the inner peripheral surface of the center hole 21 of the rotor 20, and a small-diameter portion 217 is formed at the upper end side of the large-diameter portion 216. ing. For this reason, a stepped portion 218 is formed between the large diameter portion 216 and the small diameter portion 217 on the inner peripheral surface of the center hole 21 of the rotor 20. Here, the boundary portion 219 between the large-diameter portion 216 and the small-diameter portion 217 is further etched and recessed. Further, the corner 444 of the large diameter portion 216 is chamfered on the fixed shaft 44. Therefore, even if the rotor 20 is displaced downward, the corner 444 of the fixed shaft 44 does not hit the boundary portion 219 between the large diameter portion 216 and the small diameter portion 217. 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.
[0033]
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 slightly smaller than the large diameter portion 446 and the small diameter portion 447 formed on the outer peripheral surface of the fixed shaft 44. It is formed larger by about 20 μm. Therefore, in a state where the fixed shaft 44 is inserted into the center hole 21 of the rotor 20, the large diameter portions 446 and 216 are in the radial direction between the outer peripheral surface of the fixed shaft 44 and the inner peripheral surface of the center hole 21 of the rotor 20. In the overlapping region, an annular gap 70 for generating dynamic pressure having a gap dimension slightly wider than 10 μm is formed. Further, in the region where the small diameter portions 447 and 217 overlap in the radial direction 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, there is a gap dimension constituting the air damper 9 described later. An air damper annular gap 91 (communication portion) of about 10 μm is formed. Further, 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. An air damper annular air chamber 92 (communication portion) is formed by a slightly larger annular space defined by the step portion 448 and the step portion 218 of the center hole 21 of the rotor 20.
[0034]
Therefore, in this embodiment, the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the center hole 21 are arranged between the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the center hole 21 along the motor axis L direction. An annular gap 70 for generating dynamic pressure (dynamic pressure generating portion 71), an air damper annular air chamber 92 communicating with the annular gap 70, and the air damper annular air chamber 92 and the outside Are formed in this order, and the air damper 9 for the rotor 20 is configured by the air damper annular air chamber 92 and the air damper annular gap 91.
[0035]
(Operation and effect of this form)
In the motor 5 configured as described above, when the rotor 20 rotates counterclockwise as viewed from above, an annular gap 70 for generating dynamic pressure between the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the rotor 20 The dynamic pressure generating portion 71 in which the dynamic pressure generating groove 441 is formed uses the air damper annular gap 91 and the air damper annular air chamber 92 as a communication portion with the outside, and draws air from the outside, generate. The dynamic pressure generated by the air flow brings the stator 40 and the rotor 20 into a non-contact state in the radial direction. At this time, since the pressure increasing portion 450 in which the dynamic pressure generating groove 441 is not formed is formed on the lower end side of the outer peripheral surface 440 of the fixed shaft 44, the air flow supplied from the dynamic pressure generating portion is The air pressure is increased by the booster 450. Therefore, in the motor of the present embodiment, the dynamic pressure rigidity (dynamic pressure) is high in place of using the dynamic pressure bearing as the radial bearing 7. Therefore, the rotational stability of the rotor 2 is high.
[0036]
Further, while the motor 5 is stopped, the rotor 20 that is slightly floating upward is held down at a position where the thrust bearing 8 is magnetically balanced by sinking slightly downward when rotation starts. In this state, since the stator 40 and the rotor 20 are completely in a non-contact state, the rotor 20 can be rotated at a high speed. Further, since the stator 40 and the rotor 20 are completely in a non-contact state, there is no wear and the life of the motor 5 can be extended.
[0037]
However, since the thrust bearing 8 using magnetic force has a relatively small rigidity, 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 is subjected to disturbance in the motor axis L direction in the air damper 9 including the air damper annular air chamber 92 and the air damper annular gap 91, the air damper The air in the annular air chamber 92 is discharged to the outside through the narrow annular gap 91 for the air damper, or the air enters the annular air chamber 92 for the air damper from the outside through the annular gap 91 for the air damper. When such exhaust and intake air are generated, the air damper annular gap 91 generates friction with air. As a result, vibration energy in the vertical direction of the rotor 20 is absorbed, so that vibration is suppressed.
[0038]
Further, in the case of the air damper 9 configured in the motor 5 of the present embodiment, an air damper ring is formed depending 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 dimension of the gap 91 and the length dimension in the motor 5 axis direction can be arbitrarily designed. Therefore, it is possible to configure the motor 5 with the built-in air damper 8 that can freely set the attenuation factor in the vertical vibration of the rotor 20 without performing complicated and laborious processing and with a small number of parts.
[0039]
Further, when a dynamic pressure bearing is used as the radial bearing 7, wear powder tends to be generated at the time of starting or stopping, but in this embodiment, the wear powder is promoted to drop due to gravity. Since the air flow generated in the dynamic pressure generating portion 71 is set to be supplied downward, such wear powder is directed downward from between the fixed shaft 44 and the central hole 21 of the rotor body 25. It is forcibly pumped and released to the outside. Accordingly, it is possible to avoid the problem that the abrasion powder stays between the fixed shaft 44 and the central hole 21 of the rotor body 25 and causes seizure.
[0040]
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 a slight vibration due to this rotation is transmitted to the coupling portion between the fixed shaft 44 and the substrate 10, a predetermined urging force is applied to the coupling portion by the disc spring 13. Therefore, the perpendicularity of the fixed shaft 44 can always be maintained. Further, since the fixed shaft 44 is fixed to the substrate 10 by the biasing force of the disc spring 13, when the fixed shaft 44 is press-fitted and fixed in a hole formed in the substrate 10, or when the fixed shaft 44 is crimped to the substrate 10. Unlike the above, the problem that the substrate 10 is distorted by the stress during the press-fitting process or the caulking can be avoided. Therefore, the perpendicularity of the fixed shaft 44 can be maintained well both initially and over time.
[0041]
[Embodiment 2]
FIG. 4 is an enlarged cross-sectional view showing a fixed portion of the fixed shaft to the frame in the motor for the polygon mirror driving device according to the second embodiment of the present invention. 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, respectively, used for fixing the fixed shaft to the substrate (frame) in the motor of this embodiment. FIG. The basic configuration of the motor of this embodiment is the same as that of the motor according to Embodiment 1, and only the configuration of the fixed portion of the fixed shaft to the substrate is different. The description will be omitted and the description will be omitted.
[0042]
As shown in FIG. 4, the polygon mirror driving device of the present embodiment is also fixed to the fixed shaft 44 in the fixed shaft insertion hole 11 formed in the iron substrate 10 (plate-shaped frame) in the stator 40 as in the first embodiment. The disc spring 134 is compressed between the bottom surface of the substrate 10 and the shaft end portion 443 that passes through the fixed shaft insertion hole 11 and protrudes to the bottom surface side of the substrate 10. A grip ring 19 as a fastener is attached. A washer 18 is disposed between the disc spring 134 and the grip ring 19, and the washer 18 has a larger outer diameter than the disc spring 134, as shown in FIGS. Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.
[0043]
As shown in FIG. 5C, the grip ring 19 includes a ring portion 190 having a substantially C-shaped planar shape, and a notch 197 for passing through a shaft having a shape in which a part of the ring portion 190 is notched. A pair of engaging claws 192 and 193 extending outwardly from both ends of the ring portion 190 are formed.
[0044]
Therefore, the grip ring 19 includes a circular shaft hole 191 having a smaller diameter than a locking groove 445 (see FIG. 4) formed in the shaft end portion 443 of the fixed shaft, and a notch 197 communicating with the shaft hole 191. There are formed two substantially semicircular recesses 195 and 196 for hooking a key-shaped jig (not shown) when unfolding.
[0045]
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.
[0046]
In order to fasten the grip ring 19 configured in this way to the shaft end 441 of the fixed shaft 44, first, a jig (not shown) is hooked on the inside of the engaging claws 192 and 193 (recesses 195 and 196). The notch 197 is widened, and the grip ring 19 is pushed from the shaft end to the position of the locking groove 445 with respect to the shaft end portion 443 of the fixed shaft 44 in this state. During this time, the grip ring 19 is pushed toward the substrate 10 while deforming the disc spring 134 via the washer 18. Then, when the jig is removed from the engaging claws 192 and 1 when the grip ring 19 enters the locking groove 445, the grip ring 18 has the spring end of the ring portion 191 so that the shaft end portion 443 of the fixed shaft 44 is fixed. It is fastened by the locking groove 445 and is not displaced.
[0047]
Thus, in this embodiment, the fixed shaft 44 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, even if the slight vibration caused by this rotation is transmitted to the coupling portion between the fixed shaft 44 and the substrate 10, the biasing force of the disc spring 13 is applied to this coupling portion. The perpendicularity of the fixed shaft 44 can always be maintained. Further, since the fixed shaft 44 is fixed to the substrate 10 by the grip ring 19, unlike the case where the fixed shaft 44 is press-fitted and fixed in 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 process or caulking can be avoided. Therefore, the perpendicularity of the fixed shaft 44 can be maintained well both initially and over time.
[0048]
[Other forms]
In the above embodiment, large diameter portions 446 and 216 for forming the dynamic pressure generating portion 71 and an air damper annular gap 91 are formed on the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the center hole 21. However, contrary to such a configuration, dynamic pressure is generated on the outer peripheral surface 440 of the fixed shaft 44 and the inner peripheral surface of the center hole 21. The structure in which the small diameter part for forming a part and the large diameter part for forming the annular gap for air dampers may be formed, respectively. Even in such a configuration, the step portion between the small diameter portion and the large diameter portion formed on the outer peripheral surface 440 of the fixed shaft 44, and the small diameter portion and the large diameter portion formed on the inner peripheral surface of the center hole, By facing the step portion, an annular air chamber for an air damper can be formed in this portion.
[0049]
【The invention's effect】
As described above, in the present invention, when the rotor rotates at a high speed, even if a slight vibration due to the rotation is transmitted to the coupling portion between the fixed shaft and the frame, the urging force of the spring is applied to the coupling portion. Therefore, the perpendicularity of the fixed axis does not decrease. Also, since the fixed shaft is fixed to the frame by a fastener, it is different from the case where the 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 problem that the frame is distorted by the stress of time can be avoided. Therefore, the perpendicularity 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 apparatus using a motor to which the present invention is applied.
FIG. 2 is a cross-sectional view of the polygon mirror driving device shown in FIG.
3 is a half cross-sectional view showing an enlarged structure of a fixed shaft and a rotor in the polygon mirror driving device shown in FIG. 1;
4 is an enlarged cross-sectional view showing a fixed portion of a fixed shaft to a frame in a motor for a polygon mirror driving apparatus according to Embodiment 2 of the present invention. FIG.
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. It is a top view of a tool
[Explanation of symbols]
1 Polygon mirror drive device
2 cases
5 Motor
8 Thrust bearing
9 Air damper
10 Substrate
11 Fixed shaft insertion hole
12 Push nut (fastener)
13 Disc spring
14 Connector
18 Washer
19 Grip ring (fastener)
20 Rotor (Rotating body)
21 Center hole of rotor
22 Rotor magnet
25 Rotor body
26 pedestal
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 dynamic pressure generation
71 Dynamic pressure generator
81, 82 magnet
91 Annular gap for air damper
92 Annular air chamber for air damper
216 Large diameter part of the center hole of the rotor
217 Small diameter part of the center hole of the rotor
218 Stepped part of the center hole of the rotor
440 Outer peripheral surface of fixed shaft
441 Dynamic pressure generating groove
442 Step for fixing
443 Shaft end of fixed shaft
445 Locking groove
446 Large diameter part of fixed shaft
447 Small diameter part of fixed shaft
448 Stepped part of fixed shaft
450 Booster
505 Spring for fixing polygon mirror
506 Cut scheduled part of mirror pressing member

Claims (7)

In a motor having a fixed shaft whose lower end is held by a frame, and a rotor supported by the fixed shaft so as to be rotatable around the fixed shaft,
The frame includes a fixed shaft insertion hole through which a lower end side of the fixed shaft is inserted,
The fixed shaft includes a stepped portion that contacts the upper surface side of the frame, and a shaft end portion that protrudes downward from the frame through the fixed shaft insertion hole,
The shaft end portion is fixed to the shaft end portion so that the spring is compressed between the lower surface side of the frame and fixed to the shaft end portion so that the fixed shaft is fixed upright with respect to the frame. The tool is attached ,
The said spring is a disc spring arrange | positioned so that the said shaft edge part may penetrate the center, The inner peripheral side of the said disc spring is contact | abutting with the lower surface side of the said frame, The motor characterized by the above-mentioned. The motor according to claim 1, wherein the fastener is a push nut attached to the shaft end portion of the fixed shaft so as to sandwich the disc spring between the frame and the frame. 2. The motor according to claim 1, wherein the fastener is a grip ring attached to the shaft end portion of the fixed shaft so as to sandwich the disc spring between the frame and the frame. 4. The motor according to claim 3, wherein a locking groove for locking with the grip ring is formed at the shaft end portion of the fixed shaft. In any one of Claims 1 thru | or 4, the said disc spring and a washer are arrange | positioned in this order between the said flame | frame and the said fastener,
The outer diameter of the washer is larger than the outer diameter of the fastener and the outer diameter of the disc spring. 6. The dynamic pressure generating groove according to claim 1, wherein a dynamic pressure generating groove is formed on at least one side 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 motor is characterized in that the rotating body is rotatably supported around the fixed shaft by a dynamic pressure generated by the dynamic pressure generating groove. 7. A rotary polygon mirror drive apparatus using a motor as defined in claim 1, wherein a rotary polygon mirror is formed on the rotor side.

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