JPH03219206A - Air bearing type optical deflector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an air magnetic bearing type optical deflector that is used in an optical writing device of a laser printer or a digital copying machine and deflects a signal modulated into light. .

[Conventional technology]

A rotating mirror type optical deflector using a polygon mirror can obtain a large deflection angle, and is therefore widely used in optical writing devices such as laser printers and digital copying machines.

Since the deflection speed of this type of optical deflector depends on the rotation speed,
To obtain high resolution, tens of thousands of revolutions, for example 30,000
It is necessary to rotate the polygon mirror at a high rotation speed of rpm. Bearings that achieve such high rotational speeds are required to have low bearing friction, and generally air-magnetic bearings are used.

Japanese Patent Publication No. 53-6854 discloses a dynamic pneumatic radial bearing that supports a rotating shaft with a polygon mirror fixed to the upper part in the radial direction using dynamic air pressure, and a dynamic air radial bearing that is provided at the lower part of the rotating shaft.
A rotating mirror optical deflector is disclosed that includes a repulsive magnetic thrust bearing that levitates and supports a rotating shaft in the axial direction by the magnetic repulsive force of a permanent magnet.

The rotating mirror optical deflector according to this disclosure has a problem in that the repulsion magnetic thrust bearing is a simple repulsion type bearing provided at the lower part of the rotating shaft, and therefore the rigidity is weak. In addition, the configuration of the repulsive magnetic thrust bearing requires special parts such as holters and damper parts, which increases the cost due to the large number of parts.The repulsive magnetic thrust bearing also occupies a large space, making the entire device larger. There is a problem with doing so.

In order to solve some of these problems, the applicant has developed an air magnetic bearing type optical deflector in which a repulsive magnetic thrust bearing is provided between the upper part of the rotating body, the inner surface of the upper wall of the case, and the upper part of the fixed shaft. It was proposed as Application No. 62-92048.

FIG. 15 is a sectional view showing the configuration of a conventional air magnetic bearing type optical deflector according to this proposal. In the optical deflector according to the existing proposal, the lower end of the fixed shaft 17 is press-fitted into the pedestal 20, and the upper herringbone groove 17 is formed on the circumferential surface of the fixed shaft 17 in the axial direction.
In addition, a lower herringbone groove 17b is formed on the circumferential surface of the lower portion in the axial direction. A holder 18 is fixed to the upper end surface of the fixed shaft 17, and a first magnet 19 is further attached to the holder 18. Fixed axis 1
A cylindrical rotating shaft (body) 11 is loosely fitted on the outside of the rotating shaft 7, and a rotor magnet 16 is fixed to the lower part of the rotating shaft 11. A magnet holder 12 is placed on the top of the rotating shaft 11.
is fixed, and a second magnet 13 is fixed to this magnet holder 12. Further, a fine hole 12a for damping vertical vibration is formed on the upper surface of the holder 12.

A flange IIF is integrally formed approximately at the center of the rotating shaft 11, and a polygon mirror I5 is mounted on the flange IIF, and further fixed to the rotating shaft 11 by a mirror holder 14.

On the other hand, a frame 21 is fixed to the pedestal 20 so as to surround the polygon mirror 15, and the open surface of the frame 21 is covered with a cover 22. A third magnet 23 is located on the inner wall of the cover 22 at a position facing the second magnet 13.
is fixed.

Further, a stator yoke 25 is fixed to the frame 21 at a position facing the rotor magnet 16.

Here, an inner rotor type motor is constructed with the rotor magnet 16 fixed to the rotating shaft 11, the stator yoke (slot core) 25 fixed to the frame 21, and the coil part 24 as main components. By switching the excitation, the polygon mirror 15 rotates together with the rotation shaft 11. In addition, a third magnet 23,
The magnetic poles of the opposing surfaces of the second magnet foot 13 and the first magnet 19 have the same polarity, and these magnets 13, 19.23 form a thrust magnetic bearing, and the first and third Due to the repulsive force that the second magnet 13 receives from the magnetic eyes 923, the rotating shaft 11 is suspended and supported in the axial direction. The fixed shaft 17, in which the upper herringbone groove 17a and the lower herringbone 117b are formed, and the rotating shaft 11, which rotates in close opposition to the fixed shaft 17, dynamically increases air pressure and rotates with dynamic air pressure. A dynamic air radial bearing is configured to support the shaft 11 in the radial direction.

Furthermore, a balance sling R for balancing the rotating body is attached to the lower part of the rotor magnet 16 (the mirror holder 14 also has a similar function). Note that reference numeral H in the figure represents a Hall element for detecting the rotation of the rotor magnet 16.

FIG. 16 is a sectional view showing the support structure of the pedestal and frame body in FIG. Fitting stepped portion 2
The inner circumferential surface of the fitting hole 21a of the frame body 21 is in contact with the outer circumferential surface of the frame 21.

Further, in this conventional air-magnetic bearing type optical deflector, a method is adopted in which the polygon mirror 15 is positioned by the outer circumferential surface of the hollow rotating shaft 11 which has been finished with high accuracy, and is locked by the flange 11F.

Incidentally, the outer circumferential surface of the hollow rotating shaft 11 that rotates the polygon mirror 15 at an ultra-high speed needs to be highly precisely coaxial with the inner circumferential surface, and is therefore ground in accordance with the inner diameter standard. This is to reduce variations in the radial direction of each surface of the polygon mirror 15, and to provide an initial hand balance that allows balance correction.

According to this conventional air-magnetic bearing type optical deflector, the repulsive magnetic thrust bearing has a structure in which the second magnet 13 receives repulsive forces from the third magnet 23 and the first magnet 19, respectively, so that it has a strong rigidity and a polygonal shape. mirror 1
5 can be stably rotated at a high rotational speed of 30,000 rpm as described above.

On the other hand, in the conventional hollow rotating shaft 11 in which such a flange lla is formed at an intermediate position, the grinding process is performed by fixing the rotating shaft - grinding, removing the rotating shaft, changing the direction, fixing the rotating shaft - due to the structure of the processing machine. It went through a process like grinding-completion.

[Problem to be solved by the invention]

As described above, according to the air magnetic bearing type deflector proposed by the present applicant, the problem that the rigidity of the simple repulsion type bearing of the rotating mirror optical deflector disclosed in Japanese Patent Publication No. 53-6854 is weak is solved. is resolved.

However, in the previously proposed air-magnetic bearing type deflector, the thrust bearing placed at the upper end of the rotating shaft is long in the axial direction and has a large number of parts, so no particular consideration has been given to miniaturization and cost reduction. It wasn't.

Furthermore, when the above-mentioned grinding process is performed, it is necessary to attach and detach the rotating shaft 11 from the processing machine during the grinding process of the hollow rotating shaft 11, which takes processing time including setup. It was also pointed out that it was difficult to achieve coaxiality between the left and right sides of the flange.

Furthermore, blank processing to form the flange portion took time, and there were many unnecessary parts that turned into chips.

In addition, since the polygon mirror 15 is mounted in the middle of the hollow rotating shaft 11, there is a lot of wasted upper space, which has delayed the ability to respond to miniaturization.

The present invention was made in view of the current state of optical deflectors, and its first purpose is to create an air bearing that can shorten the axial length, downsize the entire device, and reduce the number of parts. An object of the present invention is to provide a type optical deflector.

A second object of the present invention is to provide an air bearing type optical deflector whose hollow rotating shaft can be formed into a shape that can be machined to reduce processing costs.

[Means to solve the problem]

The first and second purposes are to provide space between a fixed shaft, a rotating shaft in which a hollow part is formed to be extrapolated to the fixed shaft, and the tip of the fixed shaft and the opposite end of the hollow part. a radial air bearing formed between the inner circumferential surface of the hollow part and the outer circumferential surface of the fixed shaft; a polygon mirror fixed to the rotating shaft; In an air bearing type optical deflector, the polygon mirror is fixed to the rotation shaft, and the air bearing type optical deflector includes a drive means for rotationally driving a rotation shaft, and the rotation shaft is rotationally driven via the drive means to deflect light irradiated onto the polygon mirror. This is achieved by forming a flange and setting the upper end of the supporting means on the fixed shaft side to be lower than the upper end surface of the polygon mirror.

In this case, the supporting means includes a first magnet attached directly to the distal end surface of the fixed shaft, a second magnet attached to the hollow part of the rotating body opposite to the first magnet, and a second magnet attached opposite to the second magnet. and a third magnet attached to the casing side that covers the polygon mirror, so that the magnetic poles that generate magnetic repulsion are opposed to each other.

The support means can also be constituted by a dynamic pressure thrust air bearing provided at the upper end of the fixed shaft.

Furthermore, the supporting means may be configured to obtain a levitation force from the upward dynamic pressure airflow generated by the rotation of the rotating shaft, and to support the rotating shaft in a state separated from the fixed shaft.

The above first object can also be achieved by integrally forming the flange in the first means on the tip of the rotating shaft, and also by fixing the polygon mirror in the first means to the tip of the rotating shaft. be done.

[For production]

According to the above means, the flange portion that locks the polygon mirror fixed to the hollow rotating shaft is formed at the tip (upper end) of the hollow rotating shaft, or is attached to the polygon mirror provided at the tip of the hollow rotating shaft. Then it is formed into one piece. In any case, this flange will be formed at the tip of the hollow rotary shaft, and in the process of machining the hollow rotary shaft, if a part of the rotary shaft is set in the processing machine, it will be necessary to remove it and set up again. This eliminates the need for efficient processing, and since the upper end of the support means is lower than the upper end surface of the polygon mirror, there is no wasted space above.

〔Example〕

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

1 to 3 are partially cross-sectional explanatory views showing the configurations of first to third embodiments of the present invention, respectively, and FIG.
5 and 5 are explanatory diagrams of the main parts of FIG. 1 and FIG. 2, respectively. In the following description, the same reference numerals are given to the same configurations as those of the above-mentioned conventional example, and the description will be omitted as appropriate.

As shown in FIG. 1, in the first embodiment, a flange 11F is formed at the upper end of a rotating shaft 11A that is loosely fitted into a fixed shaft 17A, and a polygon mirror 1 is formed on the lower surface of this flange IIF.
5 are fixed to the rotating shaft 11A by bolts 26 with the holders 31 in contact with the upper surface of the flange IIF.

The second magnet 13 is fixed to the holder 31, and a fine hole 32 for vertical vibration damping is formed at the center of the holder 31. Further, as shown in FIG. 4, the fixed shaft 17
A recess 40 is formed in the upper end surface of A, and a first
A magnet 19 is embedded and fixed.

A flange 41 is integrally formed on the upper part of the frame 21A fixed to the pedestal 20, a cap-shaped cover 22A is fixed to the flange 41, and a third cap is attached to the inner wall of the cover 22A.
A magnet 23 is attached.

FIG. 6 is a sectional view showing the structure of the pedestal part of the first embodiment, and the first embodiment has a fixed shaft 17 as shown in FIG.
The upper surface of the pedestal 20 of A is made flat, and the frame 2 is placed around this area.
Although the lower surface of the frame 1A has an m-shaped structure, a shallow fitting hole 21b is provided in the lower surface of the frame 21A, as shown in FIG. It is formed. The inner diameter of the fitting hole 21b is set between the outer diameter of the pedestal 20 and the entire upper surface of the fitting hole 21b is in contact with the upper surface of the pedestal 20. Further, the side part of the fitting hole 21b is connected to the fitting part 20 which is the circumferential surface of the pedestal 20.
It is in contact with the upper edge of d.

FIGS. 7 and 8 are cross-sectional views showing other structural examples of the pedestal, and the pedestal can also have such a structure in the first embodiment.

In FIG. 7, a groove-shaped fitting part 20e is provided at the upper edge of the fitting part 20d at the depth of the fitting hole 21b and within a range of 0 to 1 fl in the radial direction.

In addition, in FIG. 8, the fitting hole 21 is different from the fitting part 20a.
With the exception of the portion in contact with the inner periphery of b, O to 1 fl of the lower portion is removed in the radial direction to form a fitting portion 20f.

With such a configuration, the pedestal 20 and the frame 21
It becomes possible to further ensure the fitting of A.

The configuration of other parts of the first embodiment is the same as the conventional air magnetic bearing type optical deflector already explained in FIGS. 15 and 16.

In the first embodiment, the first magnet 19 is attached to the fixed shaft 1
Since it is directly embedded and fixed in the recess 40 of 7A,
A separate holder for the first magnet 19 is not required, and the number of parts can be reduced. In addition, since conventional air magnetic bearing type optical deflectors are attached to a rotating shaft that rotates at high speed, the parts tolerances required for this holder are strict, and tapping is required to connect to the rotating shaft, which reduces manufacturing costs. There was a problem. However, in this first embodiment, the number of parts is reduced and the holder machining work that leads to the above-mentioned cost is unnecessary, so that the overall manufacturing cost can be reduced.

Furthermore, since the separate holder for the first magnet 19 is omitted and the holder 31 for the second magnet 13 is also made thinner, the length in the axial direction is also shortened, and the overall size can be reduced.

Further, according to the first embodiment, since the upper surface of the pedestal 20 can be made flat, there is no need for sawing from a round bar as in the past, and the base 20 can be manufactured by simply slicing a round bar material. As a result, manufacturing becomes easier and costs can be reduced.

In the second embodiment, as shown in FIGS. 2 and 5, a convex portion 45 is integrally formed on the upper end surface of the fixed shaft 17B, and a first magnet 19 is fixed to the outer periphery of this convex portion 45. It is something. Further, in the second embodiment, a ring-shaped frame 43 is fixed to the flange 41B of the frame 21B, and this frame 43
A cover 22B is fixed to the frame 43 so as to cover the open surface of the cover 22B, and a third magnet 23 is attached to the inner wall of the cover 22B.

The rotating shaft 11B loosely fitted to the fixed shaft 17B is
A polygon mirror 15 is fixed to the upper surface of a flange IIG slightly longer than B and formed at the tip thereof, and is also fixed to the rotating shaft 11B with a bolt 26 via a holder 33. The second magnet 13 is fixed to this holder 33.

In the second embodiment, the outer diameter of the convex portion 45 can be machined more easily than the inner diameter of the recess 40 in the first embodiment, and manufacturing costs can be reduced compared to the first embodiment.

The structure and effects of other parts of the second embodiment are similar to those of the first embodiment already explained using FIG.

In the third embodiment, as shown in FIG. 3, a recess 46 is formed on the upper surface of the fixed shaft 17C, and the first magnet 19 is fixed to the bottom surface of this recess 46, and the second magnet 13 is fixed. The holder 34 has a cylindrical portion 34 inserted into the recess 46.
It is equipped with a. In addition, the cover 22C has a third
A cylindrical portion 48 is formed to which the magnet 23 is fixed.

In the third embodiment, a thrust bearing consisting of the third magnet 23, the second magnet 13, and the first magnet 19 is provided in the recess 46 of the fixed shaft 17C, and This shortens the distance between the two and achieves miniaturization.

The configuration and effects of other parts of the third embodiment are the same as those of the second embodiment described using FIG. 2.

Generally, in the optical writing devices of laser printers and digital copiers to which this type of optical deflector is applied, the space above the polygon mirror is narrow, and the length from the top surface of the polygon mirror to the top surface of the device is short. desired.

As mentioned above, in the first to third embodiments, the length in the axial direction is shortened, but the upper surface position y2 of the polygon mirror 15 and the lower surface position y of the lower thrust magnet 19
The distances from 1 are 11, 12, and 13, respectively, and there is a relationship of gl<7!2<, i+3 between them.

FIG. 9 is an explanatory diagram showing the configuration of a fourth embodiment of the present invention, in which a flange 11F that also serves as a magnet holder is attached to a rotating shaft 1.
It is formed at the tip (upper end) of 1A. The polygon mirror 15 is held and fixed between the flange IIF and the mirror holder 14.

FIG. 10 is an explanatory diagram showing the configuration of a fifth embodiment of the present invention. In this embodiment, a polygon mirror 15 is placed on the upper surface of a flange IIF formed at the tip of a rotating shaft 11A, and further, The polygon mirror 15 is pressed and held from above by a mirror presser 14 whose inner cylindrical portion 14a is positioned by fitting into the inner peripheral portion of the rotating shaft 11A. Specifically, the polygon mirror 15 is fixed by inserting the screw 27 through the mirror holder 14 and the polygon mirror 15 and screwing it into the flange IIF.

In the embodiment shown in FIG. 10, the inner diameter of the hollow rotating shaft 11A and the inner diameter of the polygon mirror 15 are equal, but even if they are different, the shape of the inner cylinder portion 14a of the mirror holder 14 may be changed. I can deal with it.

Furthermore, this mirror holder 14 holds the magnet 13 and also functions as a magnet holder. Also, in the center of the mirror holder 14, there is a fine hole 28 for an orifice.
is formed to give the thrust bearing a damping characteristic.

The configuration of other parts of these fourth and fifth embodiments is as follows:
This is the same as the first embodiment already explained using FIG.

In any case, by forming the flange IIF at the tip of the hollow rotating shaft 11A, there is no need to attach or detach it to the processing machine during blank cutting or grinding to ensure coaxiality. , the machining process can be shortened to fixing the rotating shaft - cutting/grinding - completion, resulting in lower machining costs.

In addition, the method of forming the shape can be forged, and as a result, the amount of blank cutting can be reduced, processing time can be shortened, and material waste can be reduced, resulting in lower processing costs.

Further, since the locking position of the polygon mirror 15 can be made higher, it can be used even in a place where the upper space is smaller.

Furthermore, when the mirror holder 14 is press-fitted into the polygon mirror 15 and the inner circumference of the rotating shaft 11A and fixed, the polygon mirror 15 can be positioned and locked more accurately and easily.

In addition, if the mirror holder 14 also has the function of a magnet holder and the orifice microhole 28 is formed,
It is possible to reduce costs, improve assembly efficiency, and improve magnet positioning accuracy.

FIG. 11 is an explanatory diagram showing the configuration of the sixth embodiment of the present invention,
FIG. 12 is an explanatory view of the upper end surface of the fixed shaft in FIG. 11.

In the sixth embodiment shown in these figures, the repulsive force generating means forming the axial air bearing is not a magnet but an air dynamic pressure at the tip of the fixed shaft. A thrust air bearing is configured.

In this embodiment, a polygon mirror 15 is mounted on the upper surface of a flange 11F formed at the tip of the rotation shaft 11A, and
The polygon mirror 15 is positioned coaxially with the axis of the rotating shaft and is held and locked from above by a mirror holder I4 which is positioned by fitting the inner cylindrical part 14a into the inner peripheral part of the polygon mirror 1A. Specifically, the polygon mirror 15 is locked and fixed by screwing the screw 27 across the mirror holder 14, the polygon mirror 15, and the flange 11F. This mirror holder 14 is formed with a balance correction groove 14b for correcting the unbalance of the rotating body.

Further, a rotor magnet 16 is fitted in the center of the rotating shaft 11A, and a balance ring R in which a balance correction groove Ra is formed is mounted below the rotor magnet 16. In this way, the polygon mirror 15, mirror holder 14, rotor magnet 16, balance ring R
The rotary shaft 11A to which the rotary shaft 11A and the like are attached constitutes a rotary body M of the dynamic pressure air bearing type polygon scanner. In order to reduce vibrations during rotation due to unbalance, this rotating body M has its balance corrected to an unbalance amount of several mg or less using upper and lower balance correcting grooves 14b and Ra.

The motor section is of a type called an inner rotor type, and is composed of a rotor magnet 16, a stator yoke 25, a coil section 25c, a Hall element H, etc., and the rotating body M of the polygon scanner is rotated by switching the excitation. There is.

In the sixth embodiment, the lower end portion of the fixed shaft 17A to which the rotating shaft 11A is fitted is firmly fixed to the base 20 by press-fitting, shrink-fitting, or the like. The fixed shaft 1
A herringbone groove 17a is provided on the outer peripheral surface of 7A to form a radial bearing.

Two pairs of upper and lower portions 17b are formed.

Furthermore, a spiral groove 17c for forming a thrust bearing is formed on the upper end surface of the fixed shaft 17A, as shown in FIG. 12. The radial bearing supports the rotating body M in the radial direction, and the thrust bearing supports the rotating body M in the axial direction.

When the rotating body M starts rotating, the pressure in the gap between the rotating shaft 17A and the fixed shaft 17A increases, forming a radial dynamic pressure air bearing, and the pressure in the gap between the upper end surface of the fixed shaft 17A and the lower end surface of the mirror holder 14 increases. This serves as a dynamic pressure thrust air bearing and supports the rotating body M in a non-contact manner in the radial and axial directions.

FIG. 13 is an explanatory view showing the configuration of the seventh embodiment of the present invention, in which the lower end of the fixed shaft 17A into which the rotating shaft 11A is loosely fitted is fixed to the base 20 by press-fitting, shrink-fitting, etc. It is firmly fixed in a way. Further, a herringbone groove 17 for forming a radial bearing is provided on the circumferential surface of the fixed shaft 17A.
a and 17b are formed. The lower end of the mirror holder 14 constituting the rotating body M is formed into a spherical shape, and when stopped, this spherical surface contacts and is supported by the upper end surface of the fixed shaft 17A.

Here, when the rotating body M starts rotating, the rotating shaft 11
The pressure in the gap between A and the fixed shaft 17A increases, a radial dynamic pressure air bearing is formed, and the rotating body M is supported in the radial direction without contact. At the same time, the upper ring bone grooves 17a, 17b
As a result, an upward dynamic pressure airflow is generated, and the rotating body M is also floated in the axial direction and supported in a non-contact manner. The structure and operation of other parts of this seventh embodiment are the same as those of the sixth embodiment already explained in FIG. 11.

FIG. 14 is an explanatory diagram showing the configuration of the eighth embodiment of the present invention, in which the lower end of the fixed shaft 17A into which the rotating shaft 11A is loosely fitted is fixed to the base 20 by press-fitting, shrink-fitting, etc. It is firmly fixed in a way. Further, a herringbone groove 17 for forming a radial bearing is provided on the circumferential surface of the fixed shaft 17A.
a and 17b are formed. A ball B is disposed at the upper end of the fixed shaft 17A, and contacts and supports the rotating body M when stopped.

Therefore, when the rotating body M starts rotating, the pressure in the gap between the rotating shaft 11A and the fixed shaft 17A increases, forming a radial dynamic pressure air bearing, supporting the rotating body M in the radial direction without contact, and moving upward. The rotating body M is also floated in the axial direction by the upwardly pressurized air flow generated by the ring bone grooves 17a and 17b, and is supported in a non-contact manner.

In the sixth to eighth embodiments described above, the rotating shaft 1
Since the flange IIF is formed at the tip of 1A, there is no need to attach or detach it to the processing machine midway, and processing costs can be reduced. Further, since the polygon mirror 15 can be positioned coaxially with the rotation axis by the mirror holder 14, variations in the reflective surface of the polygon mirror 15 can be kept to an extremely small level.

〔Effect of the invention〕

As is clear from the above description, the present invention configured as described above has the following effects.

That is, according to the invention according to claim 1, the flange for fixing the polygon mirror to the rotating shaft is integrally formed, and the upper end of the supporting means on the fixed shaft side is set to be lower than the upper end surface of the polygon mirror. For example, when machining a rotary shaft, machining becomes easier because it eliminates the trouble of attaching and replacing.

In addition, since the upper end of the supporting means on the fixed shaft side is lower than the upper end surface of the polygon mirror, it is possible to minimize wasted space on the upper side of the polygon mirror, resulting in miniaturization. can be achieved.

The supporting means is composed of first to third magnets, and
According to the invention as claimed in claim 2, the magnet is attached directly to the tip surface of the fixed shaft, the second magnet is attached to the hollow part of the rotating body, and the third magnet is attached to the casing side.
Since the first magnet is directly attached to the end surface of the fixed shaft, there is no need for a holder for the lower thrust magnet that requires precision machining, and manufacturing costs can be reduced by reducing the number of parts.

The invention according to claim 3, wherein the support means is constituted by a dynamic pressure thrust bearing provided at the upper end of the fixed shaft, and the invention according to claim 4, wherein the support means is constituted so as to obtain airflow from an increased dynamic pressure generated by rotation of the rotating shaft. According to the above, since there is no need to attach tall parts to the upper end surface of the fixed shaft, it is possible to minimize the wasted space on the upper side of the polygon mirror, making it possible to reduce the size. can.

Claim 5, wherein the flange is integrally formed at the tip of the rotating shaft.
According to the described invention, since the flange is integrally formed at the tip, press processing is possible, blank processing can be easily completed, and there is no need to change the attachment once the workpiece is set up during processing. Improved processing efficiency. , it is possible to reduce costs.

According to the invention as set forth in claim 6, in which the polygon mirror is fixed to the tip of the rotating shaft, it is possible to minimize the wasted space above the polygon mirror, and it is possible to achieve miniaturization.

[Brief explanation of drawings]

FIGS. 1 to 14 are diagrams for explaining the present invention in detail,
1, 2, and 3 are explanatory diagrams showing the configurations of the first to third embodiments of the present invention, respectively, and FIGS. 4 and 5 are respectively FIGS. 1 and 2. FIG. 6 is a sectional view showing the structure of the pedestal part in FIGS. 1 to 3, FIGS. 7 and 8 are sectional views showing other structural examples of the pedestal part, and FIG. 9 is a sectional view showing the structure of the pedestal part in FIGS. and FIG. 10 are explanatory diagrams showing the configurations of the fourth and fifth embodiments of the present invention, respectively, FIG. 11 is an explanatory diagram showing the configuration of the sixth embodiment of the present invention, and FIG. 12 is an explanatory diagram showing the configurations of the sixth embodiment of the present invention. FIG. 11 is an explanatory diagram of the upper end surface of the fixed shaft, FIGS. 13 and 14 are explanatory diagrams showing the configurations of the seventh and eighth embodiments of the present invention, respectively, and FIG. FIG. 16 is a cross-sectional view showing the structure of a magnetic bearing type optical deflector, and FIG. 16 is a cross-sectional view showing the support structure of the pedestal and frame shown in FIG. 15. 11A, IIB...Rotating shaft, IIF, IIG・
...Flange, 13...Second magnet, 15...Polygon mirror 16...
・Rotor magnet, 17A, 17B, 17C...
... Fixed shaft, 17a ... Upper ringbone groove, 17b ... Lower ringbone groove, 19 ...
...First magnet, 20...Pedestal, 2
1A, 21B...Frame body, 22A, 22B. 22C...Cover, 23...Third magnet, 25...Stator yoke, 31...
...Holder, 32...Minor hole, 33.34
...Holder, 34a...Cylindrical part, 40
・・・・・・Recess, 41B・・・Flange, 43
・・・・・・Frame. View ~ \ To Figure 9 Figure 5 L--1-m = To \ Figure Figure Figure 10

Claims (6)

[Claims] (1) A rotating shaft is provided between a fixed shaft, a rotating shaft formed with a hollow part that is inserted into the fixed shaft, and the tip of the fixed shaft and the opposite end of the hollow part. A support means for supporting in the axial direction, a radial air bearing formed between the inner peripheral surface of the hollow part and the outer peripheral surface of the fixed shaft, a polygon mirror fixed to the rotating shaft, and a drive for rotationally driving the rotating shaft. An air bearing type optical deflector comprising means for rotationally driving a rotating shaft via the driving means to deflect light irradiated onto the polygon mirror, the air bearing type optical deflector comprising: a flange for fixing the polygon mirror to the rotating shaft; An air bearing type optical deflector, characterized in that the upper end of the supporting means on the fixed shaft side is set to be lower than the upper end surface of the polygon mirror. (2) The supporting means includes a first magnet attached directly to the tip end face of the fixed shaft, a second magnet attached to the hollow part of the rotating body opposite to the first magnet, and a second magnet. and a third magnet attached to the casing side facing the polygon mirror and covering the polygon mirror.
2. The air bearing type optical deflector according to claim 1, wherein these magnets are provided such that magnetic poles that generate magnetic repulsion are opposed to each other. (3) The air bearing type optical deflector according to claim 1, wherein the supporting means is a dynamic pressure thrust air bearing provided at the upper end of the fixed shaft. (4) Claim 1 characterized in that the support means consists of a levitation support means that obtains levitation force from the rising dynamic pressure airflow generated by the rotation of the rotating shaft and supports the rotating shaft in a state separated from the fixed shaft. The air bearing type optical deflector described above. (5) The air bearing type optical deflector according to claim 1, wherein the flange is integrally formed at the tip of the rotating shaft. (6) The air bearing type optical deflector according to claim 1, wherein the polygon mirror is fixed to the tip of the rotating shaft.