JPH10333072A - Scanner motor for driving polygon mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a windage loss generated by the rotation of a polygon mirror as much as possible. SOLUTION: A first and a second disks 41, 43 are provided on both end faces of a polygon mirror 42 in the axial direction so as to be integrally rotated with the polygon mirror 42. Relating to the first and second disks 41, 43, a tilt part 47 approaching the polygon mirror 42 as it goes to the outer peripheral part on the outer surface part opposite to the surface is provided on the side of the polygon mirror 42. When air flow generated by the rotation of disks 41, 43 is stripped off the surfaces of disks 41, 43 at the time of rotation of a rotating body 58, neighboring air is taken with it and blown off in the direction of outer periphery due to the viscosity of air. Since the stripping phenomenon of air flow is generated in the wider portion of the tilt part 47 on the outer surfaces of the disks 41, 43, air density in the vicinity of surfaces of disks 41, 43 becomes coarse, thus, air pressure around the polygon mirror 39 is lowered and air resistance i.e., the windage loss is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polygon mirror driving scanner motor for driving a polygon mirror.

[0002]

A conventional configuration of a scanner motor for driving a polygon mirror used for laser scanning of a laser beam printer using a laser beam as a light beam will be described with reference to FIGS. 6 and 7. FIG.

[0003] The housing 1 has a plurality of recesses on the upper surface side, and has a cylindrical portion 2 at the bottom at the center, and a cylindrical bearing 3 made of ceramic is inserted into the cylindrical portion 2. The bottom cover 4 is screwed to the bottom of the cylindrical portion 2. A cover 5 is screwed to the upper surface of the housing 1 so as to cover the bearing cylinder 3, and the housing 1 and the cover 5 constitute a sealed motor case 6. In the motor case 6, a wiring board 7 is screwed to an upper part of the housing 1, and a plurality of stator coils 8 are bonded and fixed to an upper surface of the wiring board 7.

A rotor 10 having a rotating shaft 9 made of, for example, stainless steel is provided inside the motor case 6. The rotating shaft 9 has two sets of upper and lower herringbone-shaped grooves 11 that constitute a part of the dynamic pressure air bearing means on the outer peripheral surface, and is rotatably inserted and supported in the bearing cylinder 3. The rotating shaft 9 and the bearing cylinder 3 constitute a dynamic pressure air bearing means using air as a gas.

A mirror mounting member 12 is mounted and fixed on the upper portion of the rotating shaft 9, and a rotor yoke 13 is bonded and fixed to a lower surface of the mirror mounting member 12. An annular rotor magnet 14 is bonded and fixed to the lower surface of the rotor yoke 13, and the rotor magnet 14 is opposed to the stator coil 8 from above with a predetermined gap in the axial direction. .

Further, a cylindrical fitting projection 12a is formed on the mirror mounting member 12, and a hexagonal polygon mirror 15 (see FIG. 7) is mounted on the outer periphery of the fitting projection 12a. I have. The polygon mirror 15 has a fitting hole 1
5a is fitted to the outer peripheral portion of the fitting protrusion 12a, and the mirror retainer 16 is mounted on the upper surface of the fitting protrusion 12a by a plurality of screws 1.
6a, it is sandwiched and fixed between the mirror retainer 16 and the mirror receiving portion 12b of the mirror mounting member 12. In the cover 5, an opening 5 a through which laser light enters and exits is formed at one location corresponding to the outer peripheral portion of the polygon mirror 15, and a glass flat plate through which laser light can enter and exit is formed in the opening 5 a. The light transmitting member 5b is formed in a shape like a letter.

A mounting member 17 is mounted and fixed below the mirror mounting member 12 so as to rotate integrally with the rotating shaft 9. The mounting member 17 penetrates through the wiring board 7 so as to surround the bearing cylinder 3 from above, and the rotating yoke 17
a is mounted below the wiring board 7 and has an annular rotor-side magnetic levitation magnet 18a.
Is attached.

The rotating yoke 17a is a yoke for converging magnetic force, and the magnetic attraction of the rotor magnet 14 always acts on the rotating yoke 17a so as to attract it. 9 is fixed via the mirror mounting member 12 or the mounting member 17, so that these distances are always kept constant without change. Therefore, the magnetic attraction of the rotor magnet 14 can be canceled in the rotor 10, and as a result, the thrust load can be reduced to only the own weight of the rotor 10.

An annular stator-side magnetic levitation magnet 18b is fixed to the housing 1 so as to surround the rotor-side magnetic levitation magnet 18a.
The configuration is such that the thrust load of the rotor 10 is received by utilizing the magnetic repulsion of the rotor-side magnetic levitation magnet 18a and the stator-side magnetic levitation magnet 18b.

In the above configuration, the rotor 10
Is rotationally driven, air is drawn into the bearing gap 19 of several μm between the inner peripheral surface of the bearing cylinder 3 and the outer peripheral surface of the rotating shaft 9 by the action of the herringbone-shaped groove 11, and high-pressure dynamic A pressure is generated, and the rotating shaft 9 is rotated in a non-contact state with the bearing cylinder 3 by the action of the dynamic pressure air bearing, and the polygon mirror 15 is also rotated integrally with the rotating shaft 9. A motor using such a dynamic pressure air bearing is suitable for high-speed rotation.

However, the following problems occur in the conventional scanner motor for driving the polygon mirror as described above. When the polygon mirror 15 is rotated at a high speed, the outer peripheral portion of the polygon mirror 15 which forms a polygon (in this case, a hexagon) collides with the surrounding air (gas) and causes turbulence of the air. The energy loss consumed for this purpose is generally called "windage loss", and most of the power consumption in the polygon mirror driving scanner motor is due to this windage loss. In addition, the windage loss increases more than the ratio as the motor speed increases, and is generally proportional to the square of the rotation speed of the motor,
It increases in proportion to the fourth power of the radius of the rotating body including the polygon mirror 15.

As a result, in a motor using a polygon mirror 15 having a high speed or a large diameter, power consumption increases substantially in proportion to the windage loss, which causes a sudden rise in motor temperature, and this temperature rise causes electronic components Of the dynamic pressure bearing, and the radial gap of the dynamic pressure bearing changes due to the difference in thermal expansion of the members, which causes the bearing to burn. This is an obstacle to speeding up and increasing the accuracy of the motor.

The present invention has been made in view of the above circumstances, and an object of the present invention is to minimize windage loss during rotation of a polygon mirror, thereby reducing power consumption and motor operation. It is an object of the present invention to provide a polygon mirror driving scanner motor capable of suppressing a rise in temperature.

[0014]

According to a first aspect of the present invention, there is provided a scanner motor for driving a polygon mirror having a polygon mirror mounted on a rotor so as to rotate integrally therewith. A disk provided at an axial end surface of the polygon mirror so as to rotate integrally with the polygon mirror in a concentric arrangement with the polygon mirror, wherein the disk is opposite to the surface on the polygon mirror side. The outer surface on the side is provided with an inclined portion approaching the polygon mirror toward the outer peripheral portion.

In the above configuration, when the rotor rotates,
The disk rotates with the polygon mirror. With the rotation of the disk, the air around the disk and the polygon mirror is blown toward the outer periphery of the disk by the centrifugal force. When the air flow generated by the rotation of the disk separates from the surface of the disk due to the centrifugal force of the disk, the nearby air is also attracted by the viscosity of the air and is blown toward the outer periphery of the disk.

At this time, the outer surface of the disk opposite to the surface on the polygon mirror side is provided with an inclined portion approaching the polygon mirror toward the outer peripheral portion.
Since the separation phenomenon of the air flow occurs in a wide portion of the inclined surface on the outer surface of the disk, the air density near the surface of the disk becomes coarse, and the air resistance, that is, the windage, is greatly reduced.

In this case, it is preferable that the inclined portion of the disk has a curved surface, a stepped shape, or a sloped shape. It is preferable that the diameter of the disk is set to be smaller than the diameter of the circumscribed circle of the polygon mirror and larger than the diameter of the inscribed circle of the polygon mirror.

Furthermore, a first cover is provided on a stationary part so as to cover the rotating body including the polygon mirror and the disk in a sealed state, and the inner surface of the first cover is substantially in contact with the outer surface of the rotating body. It is preferable that the shape is in conformity with the outer surface thereof (the invention of claim 8).

Preferably, a second cover for covering the first cover is provided outside the first cover (the invention of claim 9).

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment in which the present invention is applied to a scanner motor for driving a polygon mirror used for laser scanning of a laser beam printer using laser light as a light beam will be described with reference to FIGS. 3 will be described.

First, in FIG. 1 showing the entire structure, a housing 21 is formed of, for example, aluminum, has three concave portions 21a to 21c on an upper surface side, and has a cylindrical portion 22 at a central bottom portion. And is fixed to a predetermined portion. Inside the cylindrical portion 22, a cylindrical ceramic bearing tube 23 is adhesively fixed so as to be in an upright state. A bottom cover 24 is attached to the bottom of the cylindrical portion 22 with screws 25.

A wiring board 26 is mounted and fixed to the upper recess 21a of the housing 21 by screws 27, and a plurality of stator coils 28 are bonded and fixed on the upper surface of the wiring board 26 in an annular arrangement. Also, the housing 21
An annular stator-side magnetic levitation magnet 29 is fixed to the lower concave portion 21c, and an annular yoke 30 is fixed to the upper surface of the magnet.

The bearing tube 23 is provided with a rotor 31.
Are rotatably inserted. Rotary shaft 32
Is formed of, for example, stainless steel, and two sets of upper and lower herringbone-shaped grooves 33 and 34 constituting a part of the dynamic pressure air bearing means are formed on the outer peripheral surface. A few μm between the inner peripheral surface of the bearing cylinder 23 and the outer peripheral surface of the rotating shaft 32.
The bearing cylinder 23 and the rotating shaft 32 form a hydrodynamic air bearing means 35 which uses air as a gas.
Is composed.

A rotor yoke 36 also serving as a mirror mounting member is mounted and fixed above the rotating shaft 32. An annular rotor magnet 37 is bonded and fixed to the lower surface of the rotor yoke 36.
Are opposed to the stator coil 28 from above with a predetermined gap in the axial direction.

A first disk 41 is fixedly mounted on the outer periphery of the rotor yoke 36 by, for example, shrink fitting.
A polygon mirror 42 (see FIG. 2) having a rectangular shape is mounted. A second disk 43 is attached to the first disk 41 with screws 44 so as to press the polygon mirror 42 from above, and the polygon mirror 42 is connected to the first and second disks 41 and 43. It is sandwiched between and fixed.

Accordingly, in this case, the first and second end faces of the polygon mirror 42 in the axial direction (vertical direction in FIG. 1) are provided.
Are provided so as to rotate integrally with the polygon mirror 42 in a concentric arrangement with the polygon mirror 42. Here, the first and second disks 41, 4
3 have the same diameter R1 as shown in FIG.
Shows the diameter R1 of the second disk 43), which is smaller than the diameter A1 of the circumscribed circle 45 of the polygon mirror 42,
In addition, the diameter is set to be larger than the diameter A2 of the inscribed circle 46 of the polygon mirror 42 (A1>R1> A).
2). In this case, the first and second disks 41, 4
3, and the polygon mirror 42 are formed of aluminum.

The outer surfaces of the first and second disks 41 and 43 opposite to the surface on the polygon mirror 42 side (the lower surface of the first disk 41 and the upper surface of the second disk 43). And an inclined portion 47 which approaches the polygon mirror 42 toward the outer peripheral portion. This inclined part 4
7 is formed in a concave curved surface shape.

A through hole 48 penetrating in the axial direction is formed in a portion where the first disk 41 and the first disk 41 overlap, and a through hole 49 penetrating in the axial direction also in the rotor yoke 36. Is formed. An annular auxiliary plate 50 surrounding the stator coil 28 is fixed by screws 51 on the upper surface of the housing 21 which is a stationary portion facing the inclined portion 47 on the lower surface side of the first disk 41 in the axial direction. I have. The auxiliary board 50 is formed in a shape larger than the outer shape of the polygon mirror 42, has a smooth upper surface, and is set to be substantially flush with the upper surface of the stator coil 28.

At the lower part of the rotor yoke 36, the mounting member 5
5 is provided so as to rotate integrally with the rotation shaft 32.
The mounting member 55 penetrates the hole of the wiring board 26 so as to cover the bearing cylinder 23 from above, and the rotating yoke 56 is positioned below the rotor magnet 37 below the lower part thereof so as to be parallel to the rotor magnet 37. And a ring-shaped magnet for magnetic levitation 5 on the rotor side
7 is attached.

The rotating yoke 56 is a yoke for converging the magnetic field, and the magnetic attraction of the rotor magnet 37 always acts on the rotating yoke 56 to attract it. Since they are fixed to the rotor 32 via the rotor yoke 36 or the mounting member 55, these distances are always kept constant without change. Therefore, the magnetic attraction force of the rotor magnet 37 can be offset in the rotor 31, and as a result, the thrust load is reduced by the rotor 31, the polygon mirror 42,
The weight of the rotating body 58 including the first and second disks 41 and 43 can be reduced to only its own weight.

A predetermined gap is formed between the inner surface of the mounting member 55 and the outer surface of the bearing cylinder 23. The rotor-side magnetic levitation magnet 57 is arranged inside the stator-side magnetic levitation magnet 29, and the outer peripheral surface of the rotor-side magnetic levitation magnet 57 and the stator-side magnetic levitation magnet 29 A predetermined gap is also formed between the inner peripheral surface and the inner peripheral surface.

The rotor-side magnetic levitation magnet 57 and the stator-side magnetic levitation magnet 29 each have an N
The magnetic pole is magnetized so that the lower part becomes an S pole, and receives the thrust load of the rotating body 58 by using the magnetic repulsive force of the rotor side magnetic levitation magnet 57 and the stator side magnetic levitation magnet 29. It has a configuration. Each of the rotor-side magnetic levitation magnet 57 and the stator-side magnetic levitation magnet 29 has an upper S pole, and a lower N pole.
It is also possible to magnetize to be a pole.

A first cover 61 is provided on the upper surface side of the housing 21, which is a stationary part, so as to cover the polygon mirror 42 and the rotating body 58 including the first and second disks 41 and 43 from above. With the first cover 6
A second cover 62 is provided so as to cover 1 from the outside. In this case, the first and second covers 61, 62
Are both made of aluminum and are entirely colored black. The second cover 62 is fixed to the housing 21 with screws 63, and the second cover 62 and the housing 2
The first cover 61 is interposed between the first cover 61 and the first cover 61.

Between the first cover 61 and the second cover 62, a contact portion 64 in which these are adhered to each other, and an air layer 65.
And form. The lower surface of the first cover 61 is in close contact with the upper surface of the auxiliary panel 50, and the cylindrical portion 61 a provided on the upper surface is sealed by the second cover 62, and covers the rotating body 58 in a sealed state. ing. The inner surface of the first cover 61 has a shape substantially along the outer surface of the rotating body 58,
And it is formed so as to be in a state close to the outer surface thereof.

In the second cover 62, a glass plate 66 is mounted on a portion corresponding to the cylindrical portion 61a, and a stopper member 67 is provided on a lower surface of the glass plate 66. A thrust slide bearing 68 is provided on the inner surface of the bottom cover 24. At both upper and lower ends of the rotating shaft 32,
Protrusions 69, 69 having a diameter of about 1 mm are provided,
These projections 69, 69 are received by the thrust slide bearing 68 and the stopper member 67. The thrust slide bearing 68 and the stopper member 67 are both formed of a slide bearing material, for example, a polyimide resin or a polyacetal resin. In this case, the axial movement range (vertical movement range) of the rotating shaft 32 and thus the rotating body 58 is determined by the thrust slide bearing 68 and the stopper member 67.
Is regulated to be 0.05 to 0.1 mm.

In the first cover 61, a beam entrance window 71 through which laser light enters and exits is provided at one position on the outer peripheral portion corresponding to the outer surface of the polygon mirror 42. The beam access window 71 is provided with the first cover 6.
1 and a translucent member 73 made of a flat glass plate and attached to cover the opening 72 from outside.

In the first cover 61, on the inner surface on both sides in the circumferential direction of the opening 72, an intersection 74 between the circumferential edge 72 a of the opening 72 and the inner surface of the light transmitting member 73 is formed.
A groove 75 is formed so as to smoothly connect between the first cover 61 and the inner peripheral surface 61b.

The second cover 62 has a beam access window 71.
A beam entrance 76 formed of an opening is formed at a portion corresponding to the air gap 65.
Is in communication with In the upper part of the second cover 62 away from the beam entrance 76, a communication port 77 for communicating the air layer 65 with the outside is formed. In addition, the first and second
The heat radiation fins 78, 79 are integrally formed on the upper surfaces of the covers 61, 62, respectively.

Below the housing 21, a circuit board 81 having a drive circuit (not shown) is arranged. The circuit board 81 is attached and fixed to the housing 21 with screws 83 via spacers 82. This circuit board 8
The first circuit and the circuit on the wiring board 26 are electrically connected via a connector 84.

In the above configuration, when the rotor 31 is driven to rotate, air is drawn into the bearing gap between the bearing cylinder 23 and the rotary shaft 32 by the action of the herringbone-shaped grooves 33, 34, and high pressure is applied. The rotating shaft 32 is rotated in a non-contact state with the bearing cylinder 23 by the action of the dynamic pressure air bearing. The polygon mirror 42 and the first and second disks 41 and 43 are also rotated integrally with the rotation shaft 32.

Here, with the rotation of the first and second disks 41 and 43, the air around the first and second disks 41 and 43 and the polygon mirror 42 is separated by the centrifugal force into the first and second disks 41 and 43. Of the discs 41 and 43 in the outer peripheral direction.
When the airflow generated by the rotation of the first and second disks 41 and 43 separates from the surfaces of the first and second disks 41 and 43 due to the centrifugal force of the first and second disks 41 and 43. The nearby air is also attracted by the viscosity of the air and is blown toward the outer circumference of the first and second disks 41 and 43.

At this time, the first and second disks 41, 43
And an inclined surface 47 having a concave curved surface approaching the polygon mirror 42 toward the outer peripheral portion is provided on an outer surface portion opposite to the surface on the polygon mirror 42 side, so that the air flow separation phenomenon occurs. Are the first and second disks 4
The first and second disks 41, 43 are formed on the outer surface of the first and second disks 41, 43, because the outer surfaces of the first and second disks 41, 43 are generated in a wide portion of the inclined portion 47.
The air density near the surface becomes coarse, and as a result, the air pressure around the polygon mirror 39 decreases, and the air resistance due to turbulence caused by the outer peripheral portion of the polygon mirror 39 colliding with the surrounding air decreases. In other words, energy loss and windage loss to be consumed can be reduced.
Power consumption can be reduced, vibration and noise can be reduced, and motor characteristics can be improved.

The diameter R1 of the first and second disks 41 and 44 is determined by the diameter A of the circumscribed circle 45 of the polygon mirror 42.
1 and larger than the diameter A2 of the inscribed circle 46, the polygon mirror 42
In a portion corresponding to each of the reflection surfaces 42a (see FIGS. 2 and 3), a part of the first and second disks 41 and 43 is formed to protrude outward. As a result, the number of mirror surfaces increases in a simulated manner and approaches a circle, so that windage loss can be further reduced.

Since an auxiliary plate 50 whose upper surface is processed into a smooth flat surface is provided on the upper surface of the housing 21 corresponding to the lower surface of the first disk 41, the polygon mirror 42 is provided.
As a result, the irregularities that may cause turbulence of the air flow during the rotation of the rotor are reduced as much as possible, so that the air resistance and the windage loss can be further reduced.

The auxiliary plate 50 has an annular shape surrounding the stator coil 8 and is set to be larger than the outer shape of the polygon mirror 42, and the upper surface is set to be substantially flush with the upper surface of the stator coil 8. Therefore, it is more effective in reducing windage.

On the upper surface side of the housing 21, the rotating body 58 including the polygon mirror 42 and the first and second disks 41 and 43 is covered by a first cover 61 in a hermetically sealed state. Has a shape substantially along the outer surface of the rotating body 58 and is configured to be close to the outer surface, so that an extra space is not formed around the rotating body 58 as much as possible. As a result, it is possible to prevent the occurrence of turbulent airflow around the rotating body 58 as much as possible, and to further reduce windage loss.

In this case, the first disk 41 and the second disk 4
Since the through holes 48 and 49 penetrating in the axial direction are formed in the portion where the 3 overlaps and the rotor yoke 36, the pressure difference between the upper side and the lower side in the first cover 61 can be eliminated.

On the other hand, at the time of rotation of the motor, the temperature around the rotating shaft 32 and the bearing cylinder 23 rises, and this heat is transmitted to the first cover 61, and the first cover 61 becomes high temperature. The heat of the first cover 61 is also transmitted to the second cover 62. With the first cover 61 and the second cover 62, the heat radiation area is greatly increased, and the heat radiation effect is promoted by the temperature difference from the external air, the temperature rise can be suppressed as much as possible, and the bearing performance decreases. Can be prevented. In addition, since the first and second covers 61 and 62 are provided with the radiation fins 78 and 79, the radiation area is further increased, and the radiation effect is promoted.

Further, an air layer 65 is formed between the first cover 61 and the second cover 62, and the air having a high temperature in the air layer 65 communicates with the upper communication port 77.
From the outside, and the low-temperature outside air flows into the air layer 65 from the beam inlet / outlet 76, thereby promoting the convection of the hot air in the second cover 62. The heat radiation effect can be further enhanced. In addition, by coloring the first and second covers 61 and 62 black, the heat dissipation can be further enhanced.

In the first cover 61, the inner surface of the beam entrance window 71 on both sides in the circumferential direction of the opening 72 is formed between the inner peripheral edge 72 a of the opening 72 and the inner surface of the light transmitting member 73. Intersection 74 and inner peripheral surface 6 of first cover 61
Since the groove 75 is formed to smoothly connect the polygon mirror 1a to the outer peripheral portion of the polygon mirror 42, there is no unevenness that generates turbulence, and windage loss can be further reduced.

The axial movement range of the rotating shaft 32 and thus the rotating body 58 is regulated by the thrust sliding bearing 68 and the stopper member 67 so as to be 0.05 to 0.1 mm. At times, the rotating body 58 can be prevented from hitting the first cover 61, the stator coil 8 and the like and being damaged, and the rotating body 58 can be protected. Further, when the motor is used, it can be used as it is, so that it is not necessary to remove the member for protection.

FIG. 4 shows a second embodiment of the present invention. The second embodiment differs from the first embodiment in the following points. That is, the first and second disks 41,
The inclined portions 91 of 43 are each formed in a step shape so as to approach the polygon mirror 42 toward the outer peripheral portion.

FIG. 5 shows a third embodiment of the present invention. The third embodiment differs from the first embodiment in the following points. That is, the first and second disks 41, 4
The three inclined portions 92 are each formed in an inclined shape so as to approach the polygon mirror 42 toward the outer peripheral portion.

In the second and third embodiments, the same operation and effect as in the first embodiment can be obtained.

The present invention is not limited to the above embodiments, but can be modified or expanded as follows. The first and second disks 41 and 43 do not need to be arranged on both end surfaces in the axial direction of the polygon mirror 42, but may be arranged on at least one of them.

[0056]

According to the first to fourth aspects of the present invention, when the polygon mirror and the disk are rotated, the separation phenomenon of the air flow occurs on a wide inclined portion on the outer surface of the disk. , The air density becomes coarse, and air resistance, that is, windage loss can be reduced as much as possible. As a result, power consumption can be reduced, motor characteristics can be improved, and higher speed and higher precision of the motor can be accommodated.

According to the fifth aspect of the invention, the number of mirror surfaces of the polygon mirror is increased in a pseudo manner, and the polygon mirror approaches a circle, so that windage loss can be further reduced. According to the sixth and seventh aspects of the present invention, irregularities that may cause a turbulent air flow when the polygon mirror is rotated can be reduced as much as possible, and the air resistance and the windage loss can be further reduced.

According to the eighth aspect of the present invention, it is possible to minimize the occurrence of turbulent airflow around the rotating body, and to further reduce windage loss. According to the ninth and tenth aspects of the present invention, the heat radiation area can be increased, the heat radiation effect can be promoted, and the overall temperature rise can be suppressed as much as possible.

According to the eleventh aspect, convection of air between the first cover and the second cover can be promoted, and the heat radiation effect can be further enhanced. According to the twelfth aspect of the present invention, the heat dissipation area can be further increased by the heat dissipation fins, and the heat dissipation effect can be further enhanced.

According to the thirteenth aspect, the first and the second
By making the entire surface or a part of the cover black, the heat radiation can be further improved. Claim 14
According to the invention described above, on the inner surface of the first cover, there is no irregularity that generates a turbulent flow at a portion corresponding to the outer peripheral portion of the polygon mirror, and the windage loss can be further reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional plan view of a main part.

FIG. 3 is a partially enlarged cross-sectional plan view of a main part.

FIG. 4 is a longitudinal sectional front view of a main part showing a second embodiment of the present invention.

FIG. 5 is a view corresponding to FIG. 4, showing a third embodiment of the present invention.

FIG. 6 is a diagram corresponding to FIG. 1 showing a conventional configuration.

FIG. 7 is a plan view of a polygon mirror part.

[Explanation of symbols]

21 is a housing (stationary part), 28 is a stator coil, 31 is a rotor, 32 is a rotating shaft, 41 is a first disk (disk), 42 is a polygon mirror, 43 is a second disk (disk), and 45 is a circumscribed circle. A circle, 46 is an inscribed circle, 50 is an auxiliary plate, 58 is a rotating body, 61 is a first cover, 61b is an inner peripheral surface, 62 is a second cover, 64 is a contact portion, 65 is an air layer, 71 is A beam entrance window, 72 is an opening, 72a is an edge, 73 is a translucent member, 74 is an intersection, 75 is a groove, 76 is a beam entrance, 77 is a communication port, 78 and 79 are radiation fins, and 91 and 92 are radiation fins. It is a slope.

Claims (14)

[Claims] 1. A polygon mirror driving scanner motor having a polygon mirror mounted on a rotor so as to rotate integrally with the rotor, wherein a polygon mirror is concentrically disposed on an axial end surface of the polygon mirror. A disk provided so as to rotate integrally with the polygon mirror, and an inclined surface approaching the polygon mirror toward the outer peripheral portion is provided on an outer surface of the disk opposite to the surface on the polygon mirror side. A scanner motor for driving a polygon mirror. 2. The scanner motor for driving a polygon mirror according to claim 1, wherein the inclined portion of the disk has a curved surface. 3. The scanner motor for driving a polygon mirror according to claim 1, wherein the inclined portion of the disk has a stepped shape. 4. The scanner motor for driving a polygon mirror according to claim 1, wherein the inclined portion of the disk has an inclined surface. 5. The disk according to claim 1, wherein a diameter of the disk is set to be smaller than a diameter of a circumscribed circle of the polygon mirror and larger than a diameter of an inscribed circle of the polygon mirror. A scanner motor for driving a polygon mirror according to any one of the above. 6. A disk is provided on both axial end surfaces of a polygon mirror, and a surface on a side facing the disk forms a flat surface on a stationary portion axially facing the outer surface of the disk on the stationary portion side. The scanner motor for driving a polygon mirror according to any one of claims 1 to 5, further comprising an auxiliary board. 7. The auxiliary plate has an annular shape surrounding the stator coil, and a surface of the auxiliary plate facing the disk is formed by:
7. The scanner motor for driving a polygon mirror according to claim 6, wherein the scanner motor is set to be substantially flush with a surface of the stator coil facing the disk. 8. A first unit attached to a stationary part so as to cover a rotating body including a polygon mirror and a disk in a sealed state.
The cover according to any one of claims 1 to 7, wherein an inner surface of the first cover has a shape substantially along an outer surface of the rotating body and is close to the outer surface. Scanner motor for driving polygon mirror. 9. The polygon mirror driving scanner motor according to claim 8, further comprising a second cover outside said first cover to cover said first cover. 10. The polygon mirror drive according to claim 9, wherein an air gap is formed between the first cover and the second cover, and a contact portion where the first cover and the second cover are brought into close contact with each other. Scanner motor. 11. The first cover has a beam entrance window for allowing a light beam to enter and exit the polygon mirror, and the second cover has an opening at a portion corresponding to the beam entrance window. 11. The polygon mirror driving device according to claim 10, wherein a beam entrance and exit are provided, and a communication port communicating with the outside is provided at a portion distant from the beam entrance and exit, and the beam entrance and the communication port are communicated with an air layer. Scanner motor. 12. The polygon mirror driving scanner motor according to claim 9, wherein a radiation fin is provided on the first cover and the second cover. 13. The scanner motor for driving a polygon mirror according to claim 9, wherein the entire surface or a part of the first cover and the second cover is black. 14. The first cover has a beam entrance window through which a light beam enters and exits the polygon mirror,
The beam entrance / exit window includes an opening formed in the first cover, and a plate-shaped light transmitting member mounted so as to cover the opening from the outside. A groove is formed on the inner surface on both sides in the circumferential direction of the opening to smoothly connect the intersection of the circumferential edge of the opening and the inner surface of the light transmitting member and the inner circumferential surface of the first cover. 9. The scanner motor for driving a polygon mirror according to claim 8, wherein: