JPH09318900A - Dynamic pressure air bearing type polygon scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rotate a polygon mirror in a stable state. SOLUTION: A thrust dynamic pressure air bearing 29 which supports a rotor 15 having a polygon mirror 18 is formed between one end face of the rotor 15 and the inside face of a housing 1. The rotor 15 is provided with an attachment race 23 to which true polygon mirror 18 is attached with a face orthogonal to the axis of the rotor 15. A support member 5 which forms a radial dynamic pressure air bearing 27 between itself and the peripheral surface of the rotor 15 is supported through an elastic member 6 by the housing 1. Thus, though the gap of the thrust dynamic pressure air bearing 29 is changed by the air pressure when the rotor 15 is rotated, inclination in the axial direction of the support member 5 can be corrected by the bending action of the elastic member 6 even if the perpendicularly of the support member 5 to the inside face or the housing has an error on production, and one end face of the rotor 15 and the inside face of the housing 1 between which the thrust dynamic pressure air bearing 29 is formed are kept parallel to stabilize rotation of the rotor 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure air bearing type polygon scanner.

[0002]

2. Description of the Related Art An electrophotographic recording apparatus using a polygon scanner, such as a digital copying machine, a laser facsimile, and a laser printer, is excellent in print quality, high-speed printing, low noise, etc. It is rapidly becoming popular during the period. In recent years, the printing speed has been further increased and the pixel density has been increased.
High-speed rotation of 20000 rpm is required. For this reason, in the case of a bearing that supports the rotary shaft that drives the polygon mirror, it has become difficult to satisfy the required quality in terms of bearing life and rotational noise with a ball bearing. Therefore, a dynamic pressure air bearing has been put into practical use in place of the ball bearing. Further, there are increasing demands for downsizing, cost reduction and noise reduction of the recording apparatus. A polygon scanner using a dynamic pressure air bearing is disclosed in Japanese Patent Laid-Open No. 5-272528.
Japanese Patent Laid-Open No. 6-27403 and Japanese Patent Laid-Open No. 6-27403 are known.

Japanese Unexamined Patent Publication (Kokai) No. 5-272528 discloses, on the outer peripheral surface of a fixed shaft fixedly fitted in a motor housing,
A cylindrical rotary shaft with a polygon mirror is fitted, and this rotary shaft is rotatably supported by radial dynamic pressure air bearings in the radial direction and magnetic bearings so that the thrust surface floats in the axial direction. Is listed.

In Japanese Patent Laid-Open No. 6-27403, a rotor is fitted on the outer periphery of a fixed shaft fixedly fitted to a motor casing, and the rotor is supported in the radial direction by a radial dynamic pressure air bearing, It is described that the bearing is supported by a thrust dynamic pressure air bearing by a thrust plate in the axial direction.

[0005]

As described in the above publications, when a rotating body having a polygon mirror is supported by thrust dynamic pressure air bearings, the thrust dynamic pressure air bearings face each other when the rotating body rotates. The air pressure on the bearing surface is increased, and this air pressure brings the bearing surface into a non-contact state.
However, since the fixed shaft that supports the rotating body is fixedly supported, if the perpendicularity of the fixed shaft to the bearing surface of the thrust dynamic pressure air bearing is not maintained due to manufacturing errors, the thrust dynamic pressure air bearing The bearing surfaces of will not be parallel to each other. As a result, the air pressure between the bearing surfaces becomes non-uniform in the circumferential direction of the rotating body, and vibration (vibration due to residual imbalance of the rotating body) occurs during rotation. This vibration is transmitted to the apparatus main body from a housing called a motor housing or a motor casing, which causes noise. This noise increases as the rotational speed of the rotating body increases. Also,
Since the opposite bearing surfaces of the slite dynamic pressure air bearing come into contact with each other at the time of stop, a large contact area requires a large starting torque, and sometimes a starting failure may occur.

[0006]

According to the first aspect of the present invention,
A rotary body having a polygon mirror fixed therein is rotatably supported by a radial dynamic pressure air bearing and a thrust dynamic pressure air bearing inside a housing, and a dynamic pressure air bearing is provided with a motor for driving the rotary body. Type polygon scanner, the thrust dynamic pressure air bearing is formed between one end face of the rotating body orthogonal to its axis and an inner surface of the housing facing the one end face, and the rotating body has its axis center. The support member that has a mounting surface that supports the end surface of the polygon mirror with a surface that is orthogonal to and that forms the radial dynamic pressure air bearing with the peripheral surface of the rotating body is an elastic member that is elastically bendable. And is supported by the housing via. Therefore, when the rotating body rotates, the gap between the end surface of the rotating body forming the thrust dynamic pressure air bearing and the one surface of the housing changes due to the increase of the air pressure. In this case, even if there is a manufacturing error in the verticality of the support member with respect to the inner surface of the housing, the axial tilt of the support member can be corrected by the bending action of the elastic member, so that the thrust dynamic pressure air bearing is formed. The one end surface of the rotating body and the inner surface of the housing are kept parallel to each other. Along with this, the rotation surface of the polygon mirror becomes constant.

According to a second aspect of the present invention, in the first aspect of the present invention, the rotating body is biased by a magnetic force in a direction in which the clearance between the thrust dynamic pressure air bearings becomes smaller. Therefore, the space for the thrust dynamic pressure air bearing can be reduced.

According to a third aspect of the present invention, in the invention according to the first or second aspect, one of the one end face of the rotating body forming the thrust dynamic pressure air bearing and the inner face of the housing facing the one end face. On the surface, minute convex portions arranged on a straight line passing through the center of the rotating body are formed. Therefore, it is possible to bring the opposing surfaces of the thrust dynamic pressure air bearing into contact with each other in a pivoted state while the vehicle is stopped.

According to a fourth aspect of the present invention, in the first, second or third aspect of the invention, the rotating body is formed in a cylindrical shape fitted to the outer periphery of the support member, and the radial dynamic pressure air bearing is rotatable. It is formed between the inner peripheral surface of the body and the outer peripheral surface of the support member. Therefore, since the area of the bearing forming surface forming the radial dynamic pressure air bearing is reduced, the bearing forming surface can be easily processed.

[0010] The invention according to claim 5 is the invention according to claims 1, 2, 3
Alternatively, in the invention described in item 4, the bearing forming surface forming the radial dynamic pressure air bearing and the thrust dynamic pressure air bearing is provided with a wear-resistant surface-treated film. Therefore, the contact resistance of the radial dynamic pressure air bearing and the thrust dynamic pressure air bearing is reduced.

[0011] The invention according to claim 6 is the invention according to claims 1, 2, and
In the invention described in 3, 4, or 5, the rotating body includes a cylindrical rotating shaft rotatably fitted to an outer peripheral surface of a supporting member, a polygon mirror fitted to an outer periphery of the rotating shaft, and the rotating body. A thrust plate having a mounting surface for receiving an end surface of the polygon mirror with a surface orthogonal to the axis of the shaft;
A cylindrical fixing member fixedly fitted to the outer periphery of the rotating shaft, and a cylindrical pressing body formed of an elastically bending material and sandwiched between the fixing member and the polygon mirror. It is formed by and. Therefore, the polygon mirror is fixed at a right angle to the axis of the rotating shaft in the state of being in contact with the mounting surface of the thrust plate by the compressive force of the pressing body.

According to a seventh aspect of the present invention, in the invention of the sixth aspect, the longitudinal elastic coefficient of the pressing body is set to be equal to or less than the longitudinal elastic coefficient of the polygon mirror. Therefore, the holding force acting on the polygon mirror from the fixing member and the thrust plate is absorbed by the elastic deformation of the pressing body.

[0013]

FIG. 1 shows a first embodiment of the present invention.
A description will be given based on FIG. In the figure, 1 is a housing. The housing 1 is formed by connecting a case 2 and a cover 3 with screws 4. A lower outer peripheral surface of a support shaft 5, which is a support member, is fitted to the center of the bottom of the case 2 via an O-ring-shaped elastic member 6. The elastic member 6 has a cross-section V formed on the outer peripheral surface of the support shaft 5 and the inner peripheral surface of a hole formed in the case 2 for inserting the support shaft 5.
Since it is held by the V-shaped annular groove, it does not fall off.

The housing 1 is provided with a substrate 9 having a plurality of coils 7 and Hall elements 8 for position detection on the lower surface thereof, sandwiched between the case 2 and the cover 3. On the upper surface of the substrate 9, there is provided a rotor yoke 12 to which a plurality of rotor magnets 11 facing the coils 7 are fixed by means such as press fitting or adhesion. That is, the motor 13 is formed by the substrate 9, the coil 7, the hall element 8, the rotor magnet 11, the rotor yoke 12, and the like. The motor 13 is an axial gap type coreless brushless motor. As the rotor magnet 11, a plastic-molded ferrite magnet is used. A groove (not shown) for correcting balance is formed on the inner peripheral side of the rotor magnet 11, and a weight (not shown) is added at an unbalanced position to correct the balance. The rotor yoke 12 is formed of a ferromagnetic material such as stainless steel or iron steel to form a magnetic circuit of the rotor magnet 11, and holds the outer diameter portion of the rotor magnet 11, so that the rotor magnet 11 with low mechanical strength is Prevents mechanical destruction due to centrifugal stress. In order to drive such a motor 13, a part of the substrate 9 has a slit 10 between the case 2 and the cover 3.
From the external circuit, and the projected end portion of the connector 1 receives a drive voltage and a rotation speed command from an external circuit.
4 are connected.

A rotating body 15 is rotatably fitted on the support shaft 5. The rotating body 15 includes a cylindrical rotating shaft 16 fitted to the outer peripheral surface of the support shaft 5, and a disk-shaped thrust plate 1 fitted to the outer peripheral surface of the rotating shaft 16.
7, a polygon mirror 18, a pressing body 19 made of an elastically bendable material, the rotor yoke 12 as a fixing member for pressing the pressing body 19 against the polygon mirror 18, and the like.

The thrust plate 17 has an annular projection 20 formed on the lower surface fitted to the inner peripheral surface of the rotary shaft 16, and rotates a plastically deformable caulking portion 21 formed on the outside of the projection 20. After being fitted to the outer peripheral surface of the shaft 16, the caulking portion 21 is caulked to be fixedly fitted to the rotating shaft 16. On the lower surface of the thrust plate 17, a mounting surface 23 on which the end surface 22 of the polygon mirror 18 pressed by the pressing body 19 abuts is formed so as to be perpendicular to the axis of the rotary shaft 16. The polygon mirror 18 is made of an aluminum alloy, and has a plurality of reflecting surfaces 24 formed with a hole fitted to the rotating shaft 16 and the end surface 22 as a processing reference. The rotor yoke 12 is fixedly fitted to a taper portion formed on the rotary shaft 16 by press fitting or caulking.

Therefore, the pressing body 19 is compressed by the rotor yoke 12 as a fixing member to press the polygon mirror 18, and the end surface 22 of the polygon mirror 18 is brought into pressure contact with the mounting surface 23 of the thrust plate 17. In this case, in order to prevent the deformation of the polygon mirror 18, the pressing body 19 is made of the same material as the material of the polygon mirror 18 (aluminum alloy in this example) or less. As a material having a longitudinal elastic modulus lower than that of the aluminum alloy, since the temperature of the rotating body 15 is around 70 to 80 ° C., rubber or resin having high thermal stability such as silicon rubber or fluororesin is used. Polygon mirror 18
A glass window 25 facing the reflecting surface 24 of the is formed in the cover 3.

A shallow groove 26 is formed on the outer peripheral surface of the support shaft 5 so as to be inclined with respect to its axis. The outer peripheral surface of the support shaft 5 and the inner peripheral surface of the rotary shaft 16 in which the groove 26 is formed are formed. A radial dynamic pressure air bearing 27 is formed between and. The support shaft 5 and the rotary shaft 16 are made of aluminum alloy, stainless steel, or the like. When the aluminum alloy is used, the outer circumference of the support shaft 5 is prevented in order to prevent wear due to contact at the time of stop and start. A wear-resistant surface-treated film is formed on the surface and the inner peripheral surface of the rotating shaft 16. This surface-treated film is formed by, for example, electroless composite nickel plating, abrasion-resistant resin or ceramic coating.

On the inner surface of the cover 3 at a portion facing the one end surface of the rotating body 15 (the upper surface of the thrust plate 17),
As shown in FIG. 2, a plurality of grooves 28 are spirally formed on a radius centered on the axis of the rotary shaft 16. And
A thrust dynamic pressure air bearing 29 is provided between the inner surface of the cover 3 in which these grooves 28 are formed and the upper surface of the thrust plate 17.
Are formed. The groove 28 is formed directly on the inner surface of the cover 3, or a sheet having the groove 28 is formed on the cover 3
It may be fixed to the inner surface of the sheet by adhesion or screws. In any case, a minute convex portion 30 is formed at the center of the region where the groove 28 is formed (coincident with the straight line passing through the center of the rotating shaft 16). The thrust plate 17 is formed of aluminum alloy, resin, or the like, but a wear-resistant surface-treated film is formed to prevent wear due to contact at the time of stop and start. This surface-treated film is formed, for example, by electroless composite nickel plating, abrasion-resistant resin or ceramic coating. Further, magnets 31 and 32 are embedded in the upper end surface of the support shaft 5 and the lower surface of the thrust plate 17 so as to face each other with the same polarity. Therefore, the rotating body 15 is urged by the repulsive force of the magnets 31 and 32 in the direction in which the gap between the thrust dynamic pressure air bearings 29 becomes smaller.

In such a structure, when the motor 13 is driven, the rotating body 15 rotates. When the rotation speed of the rotating body 15 increases, the air pressure in the gap of the radial dynamic pressure air bearing 27 increases due to the effect of the groove 26, and the increasing air pressure displaces the rotating body 15 downward against the repulsive force of the magnets 31, 32. However, since a gap is created in the thrust dynamic pressure air bearing 29, the rotating body 15 rotates in a non-contact state with the cover 3.

In this case, the inner surface of the housing 1 (the cover 3
Even if there is a manufacturing error in the perpendicularity of the support shaft 5 with respect to the surface on which the groove 28 is formed), the axial tilt of the support shaft 5 can be corrected by the bending action of the elastic member 6.
One end surface of the rotor 15 (the upper surface of the thrust plate 17) forming the thrust dynamic pressure air bearing 29 and the inner surface of the housing 1 (the lower surface of the cover 3) are maintained in parallel. Along with this, the rotation surface of the polygon mirror 18 becomes constant. That is, the air pressure generated in the gap between the thrust dynamic pressure air bearings 29 becomes uniform with no pressure difference in the circumferential direction, and the surface wobbling of the polygon mirror 18 is prevented. Even if some vibration occurs in the rotating body 15, the vibration is transmitted to the support shaft 5 but can be absorbed by the elastic member 6. This allows
It is possible to accurately write an image on an image carrier (not shown).

The rotating body 15 is composed of magnets 31, 32.
Since the thrust dynamic pressure air bearing 29 is urged by the repulsive force (magnetic force) in the direction in which the gap of the thrust dynamic pressure air bearing 29 becomes smaller, the space of the thrust dynamic pressure air bearing 29 can be reduced.

As described above, the upper surface of the rotating body 15 and the inner surface of the cover 3 are kept in a non-contact state by the air pressure generated in the gap of the thrust dynamic pressure air bearing 29 during the rotation, and contact with each other at the stop time, but the thrust is generated. Any one of the one end surface of the rotating body 15 forming the dynamic pressure air bearing 29 and the inner surface of the housing 1 facing the one end surface, in this example, the housing 1
Since the minute convex portion 30 arranged on a straight line passing through the center of the rotating body 15 is formed on the inner surface of the cover 3, it can be contacted in a pivoted state. As a result, it is possible to reduce the rotational resistance when the rotary drive is stopped or when the rotary drive is started. Therefore, at the time of start-up, the rotating body 15 can be easily rotated with a small driving force.

Further, the rotating body 15 is formed in a cylindrical shape fitted to the outer periphery of the supporting member (supporting shaft 5), and the radial dynamic pressure air bearing 27 is formed on the inner peripheral surface of the rotating body 15 (rotating shaft 16). And the outer peripheral surface of the support member (support shaft 5), the area of the bearing forming surface forming the radial dynamic pressure air bearing 27 can be reduced. Therefore, the precision of the bearing forming surface is required, but the machining area is small, and therefore the machining becomes easy.

Further, since the bearing forming surface forming the radial dynamic pressure air bearing 27 and the thrust dynamic pressure air bearing 29 is formed with a wear-resistant surface treatment film, the radial dynamic pressure air bearing 27 and the thrust dynamic pressure bearing surface are formed. The contact resistance of the air bearing 29 can be reduced, and the reliability of the radial dynamic pressure air bearing 27 and the thrust dynamic pressure air bearing 29 can be improved over a long period of time.

Further, the rotating body 15 is a cylindrical rotating shaft 1 rotatably fitted to the outer peripheral surface of a supporting member (supporting shaft 5).
6, a polygon mirror 18 fitted to the outer circumference of the rotary shaft 16, and a thrust plate 17 having a mounting surface 23 for receiving an end face 22 of the polygon mirror 18 with a surface orthogonal to the axis of the rotary shaft 16. Cylindrical fixing member (rotor yoke 12) fixedly fitted to the outer periphery of the rotating shaft 16.
And a cylindrical pressing member 19 which is made of an elastically flexible material and is sandwiched between the fixed member (rotor yoke 12) and the polygon mirror 18, the polygon mirror 18 is pressed by the pressing member 19. With the compression force of 19 abutting the mounting surface 23 of the thrust plate 17,
It can be fixed at right angles to the axis of the rotary shaft 16. Therefore, the polygon mirror 1 with respect to the rotating shaft 16
8 can be assembled accurately and easily without using screws or the like.

Further, by setting the longitudinal elastic modulus of the pressing body 19 to be equal to or less than the longitudinal elastic coefficient of the polygon mirror 18, the holding force acting on the polygon mirror 18 from the rotor yoke 12 and the thrust plate 17 is pressed. The polygonal mirror 18 can be prevented from being deformed by being absorbed by the bending action of the polygon mirror 18. Thereby, the irradiation position of the light from the polygon mirror 18 can be made uniform.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those described in FIGS. 1 and 2 will be described using the same reference numerals. In the present embodiment, the support shaft 5 has a pedestal 33 at the lower end. In this example, the lower end of the support shaft 5 is fixedly fitted to the pedestal 33 by shrink fitting or press fitting. This pedestal 33 and case 2
Grooves having a V-shaped cross-section located outside the support shaft 5 are formed on the lower surface of the support shaft 5, O-ring-shaped elastic members 6 are fitted into these grooves, and the pedestal 33 is formed by a plurality of screws 34 to form the case 2
Attached to. Therefore, similarly to the previous embodiment, the tilting of the shaft center of the support shaft 5 can be corrected by the bending action of the elastic member 6.

Further, the motor 35 according to the present embodiment.
On the outer periphery of the support shaft 5, a plurality of stator cores 36 fixed to the case 2, coils 37 wound around these stator cores 36, fixed to the inner peripheral surface of the rotor yoke 12, and arranged to face the outer peripheral surface of the stator core 36. And a radial gap side brushless motor including a plurality of rotor magnets 11. Other configurations and operations are the same as those in the previous embodiment, and therefore description thereof will be omitted.

[0030]

According to the invention described in claim 1, the thrust dynamic pressure air bearing is formed between one end face of the rotor which is orthogonal to the axis of the rotor and the inner surface of the housing which faces the one end face. Has a mounting surface for supporting the end surface of the polygon mirror with a surface orthogonal to its axis, and the support member forming the radial dynamic pressure air bearing with the peripheral surface of the rotating body is elastic and flexible. Since it is supported by the housing via the member, when the rotating body rotates, the gap between the end surface of the rotating body forming the thrust dynamic pressure air bearing and one surface of the housing changes due to the increase in air pressure. Even if there is a manufacturing error in the verticality of the support member with respect to the inner surface of the housing, the tilting of the support member in the axial direction can be corrected by the bending action of the elastic member, so that the thrust dynamic pressure air bearing is rotated. An inner surface of one end surface and the housing can be maintained parallel. Along with this, the polygon mirror can be rotated in a stable state without surface wobbling within a certain rotation surface, and therefore, an image can be accurately written on the image carrier.

According to a second aspect of the present invention, in the first aspect of the present invention, since the rotating body is biased by a magnetic force in a direction in which the clearance of the thrust dynamic pressure air bearing becomes smaller, the thrust dynamic pressure air bearing The space can be reduced.

According to a third aspect of the invention, in the invention of the first or second aspect, one of the one end face of the rotating body forming the thrust dynamic pressure air bearing and the inner face of the housing facing the one end face. Since the surface is formed with a minute convex portion arranged on a straight line passing through the center of the rotating body, the opposing surface of the thrust dynamic pressure air bearing can be brought into contact with each other in a pivotal state during a stop. . Therefore, the rotating body can be easily started with a small driving force.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, the rotating body is formed in a tubular shape fitted to the outer periphery of the support member, and the radial dynamic pressure air bearing is rotatable. Since it is formed between the inner peripheral surface of the body and the outer peripheral surface of the supporting member, the area of the bearing forming surface forming the radial dynamic pressure air bearing can be reduced. Therefore, the precision of the bearing forming surface is required, but the machining area is small, and therefore the machining becomes easy.

The invention according to claim 5 is the invention as claimed in claims 1, 2, and 3.
Or, in the invention described in 4, the bearing forming surface forming the radial dynamic pressure air bearing and the thrust dynamic pressure air bearing is formed with a wear-resistant surface-treated film, so that the radial dynamic pressure air bearing and the thrust dynamic pressure air bearing are formed. The contact resistance of the bearing can be reduced. Therefore, the reliability of the radial dynamic pressure air bearing and the thrust dynamic pressure air bearing can be improved over a long period of time.

The invention according to claim 6 is based on claims 1, 2, and
In the invention described in 3, 4, or 5, the rotating body includes a cylindrical rotating shaft rotatably fitted to an outer peripheral surface of a supporting member, a polygon mirror fitted to an outer periphery of the rotating shaft, and the rotating body. A thrust plate having a mounting surface for receiving an end surface of the polygon mirror with a surface orthogonal to the axis of the shaft;
A cylindrical fixing member fixedly fitted to the outer periphery of the rotating shaft, and a cylindrical pressing body formed of an elastically bending material and sandwiched between the fixing member and the polygon mirror. Therefore, the polygon mirror can be fixed at right angles to the axis of the rotary shaft in the state where the polygon mirror is brought into contact with the mounting surface of the thrust plate by the compressive force of the pressing body. Therefore, the polygon mirror can be assembled accurately with respect to the rotation axis and easily without using screws or the like.

According to the invention of claim 7, in the invention of claim 6, the longitudinal elastic modulus of the pressing body is set equal to or less than that of the polygon mirror.
The deformation of the polygon mirror can be prevented by elastically deforming the pressing body. Thereby, the irradiation position of the light from the polygon mirror can be made uniform.

[Brief description of drawings]

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

FIG. 2 is a bottom view showing the inner surface side of the cover of the thrust dynamic pressure air bearing.

FIG. 3 is a longitudinal sectional side view showing a second embodiment of the present invention.

[Explanation of symbols]

 1 Housing 5 Supporting Member 6 Elastic Member 12 Fixing Member 13 Motor 15 Rotating Body 16 Rotating Shaft 17 Thrust Plate 18 Polygon Mirror 19 Pressing Body 23 Mounting Surface 27 Radial Dynamic Pressure Air Bearing 29 Thrust Dynamic Pressure Air Bearing 30 Convex 35 Motor

Claims (7)

[Claims] 1. A rotary body, to which a polygon mirror is fixed, is rotatably supported by a radial dynamic pressure air bearing and a thrust dynamic pressure air bearing inside a housing, and a motor for driving the rotary body is provided. In the dynamic pressure air bearing type polygon scanner, the thrust dynamic pressure air bearing is formed between one end surface of the rotating body orthogonal to its axis and an inner surface of the housing facing the one end surface, The body has a mounting surface for supporting the end surface of the polygon mirror with a surface orthogonal to its axis, and the support member forming the radial dynamic pressure air bearing with the peripheral surface of the rotating body is elastically bent. A dynamic pressure air bearing type polygon scanner, which is supported by the housing through a flexible elastic member. 2. The dynamic pressure air bearing type polygon scanner according to claim 1, wherein the rotating body is biased by a magnetic force in a direction in which a gap between the thrust dynamic pressure air bearings becomes smaller. 3. A straight line passing through the center of the rotating body is disposed on one of the one end surface of the rotating body forming the thrust dynamic pressure air bearing and the inner surface of the housing facing the one end surface. The dynamic pressure air bearing type polygon scanner according to claim 1 or 2, wherein minute convex portions are formed. 4. The rotating body is formed in a cylindrical shape fitted to the outer periphery of the support member, and the radial dynamic pressure air bearing is formed between the inner peripheral surface of the rotary body and the outer peripheral surface of the support member. The dynamic pressure air bearing type polygon scanner according to claim 1, 2, or 3. 5. A wear-resistant surface-treated film is formed on a bearing forming surface forming the radial dynamic pressure air bearing and the thrust dynamic pressure air bearing.
Alternatively, the dynamic pressure air bearing type polygon scanner according to item 4. 6. The rotating body includes a cylindrical rotating shaft rotatably fitted to an outer peripheral surface of a supporting member, a polygon mirror fitted to an outer periphery of the rotating shaft, and an axis center of the rotating shaft. A thrust plate having a mounting surface for receiving the end surface of the polygon mirror having an orthogonal surface, a cylindrical fixing member fixedly fitted to the outer periphery of the rotating shaft, and formed of an elastically bending material. 6. The dynamic pressure air bearing type according to claim 1, wherein the fixed pressure member is formed by a cylindrical pressing body held between the fixing member and the polygon mirror. Polygon scanner. 7. The dynamic pressure air bearing type polygon scanner according to claim 6, wherein the longitudinal coefficient of the pressing body is equal to or less than the longitudinal elastic coefficient of the polygon mirror.