JP3901270B2 - Dynamic pressure air bearing type optical deflector - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a hydrodynamic air bearing type optical deflector used in various apparatuses that perform printing or reading by optical scanning, and more particularly to a hydrodynamic air bearing type optical deflector in which a hydrodynamic axis is used exclusively in a direction other than vertical. .
[0002]
[Prior art]
FIG. 12 is a longitudinal sectional view of a conventional hydrodynamic air bearing type optical deflector. Reference numeral 6 denotes a dynamic pressure sleeve, one end of which is supported in a cantilever manner by the case 1 via a flange 8, and a dynamic pressure shaft 7 is inserted with a radial gap C on the inner periphery thereof. Two axial bearings 9 and 9 fixed to the dynamic pressure shaft 7 with axial gaps S1 and S2 therebetween are provided on both end faces of the dynamic pressure sleeve 6, and these constitute a dynamic pressure air bearing portion. Has been. A flange 8 is fixed to one end portion of the case 1, a stator core 2 around which an inner peripheral surface is wound with a magnet wire 3, a connection board 13 on which a hall element 12 for switching current is mounted, and the like. Is fixed, and the cover 14 is fixed to the other end portion, thereby forming a stator. A magnet holding member 5 is fixed to the outer periphery of one axial bearing 9, and a rotor magnet 4 is fixed to a position of the magnet holding member 5 facing the stator core 2. A mirror holding member 10 is fixed to the outer periphery of the other axial bearing 9, and a rotating mirror 11 (hereinafter simply referred to as “rotating mirror”) using a single-sided mirror or a polygonal mirror is mounted on the mirror holding member 10. Yes. Furthermore, a balance correction member 15 is fixed to the end of the dynamic pressure shaft 7 on the side where the rotary mirror 11 is not mounted, and a rotor is constituted by these members.
[0003]
[Problems to be solved by the invention]
However, in the conventional dynamic pressure air bearing type optical deflector, there is no particular problem when the dynamic pressure shaft is used exclusively in the vertical direction. However, the dynamic pressure shaft is exclusively used for reasons of the configuration of the optical scanning system. When used in a direction other than vertical, particularly when used in the horizontal direction, in a state where no dynamic pressure is generated at the time of start / stop and when dynamic pressure is not generated at the time of acceleration / deceleration of the motor, The weight on the rotating member side acts on the lower side in the direction of gravity of the dynamic pressure air bearing portion, resulting in a contact surface pressure between the dynamic pressure shaft 7 and the dynamic pressure sleeve 6, especially when the weight on the rotating member side is large. The sliding due to the surface pressure has a problem of starting failure due to a large starting friction torque and deterioration of repeated starting / stopping life.
[0004]
The present invention has been made in order to eliminate these drawbacks in view of the above-described conventional drawbacks. Even when the dynamic pressure shaft is used exclusively in a direction other than vertical, the dynamic pressure shaft and the dynamic pressure sleeve are provided. It is intended to obtain a dynamic pressure air bearing type optical deflector having a low starting friction torque and a long starting / stopping service life.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention comprises a hydrodynamic air bearing portion comprising a hydrodynamic shaft and a hydrodynamic sleeve that are rotatably fitted to each other via a hydrodynamic bearing by a herringbone groove or other dynamic pressure generating portion. Rotating in the dynamic pressure air bearing type optical deflector that supports the rotary mirror and other rotating members rotatably through this dynamic pressure air bearing portion, and uses the dynamic pressure shaft exclusively in directions other than vertical, especially in the horizontal direction. A plurality of cores made of a substantially ring-shaped ferromagnetic material provided in the axial direction on the member side, and a radial direction provided on the fixed member side facing the respective cores and positioned above the cores. Dynamic pressure air bearing type light polarization by providing a magnetic correction means that acts in a direction to relieve gravity applied to the rotating mirror and other rotating members, comprising a plurality of radial magnets with possible adjustment functions Constitute a.
[0006]
[Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0007]
FIG. 1 is a longitudinal sectional view of a hydrodynamic air bearing type optical deflector according to a first embodiment considered by the inventors, and FIG. 2 is a sectional view taken along the line II-II in FIG. FIG. 3 is a diagram for explaining the operation of the magnetic correction means.
[0008]
Reference numeral 6 denotes a dynamic pressure sleeve, one end of which is supported in a cantilever manner by the case 1 via a flange 8, and a dynamic pressure shaft 7 is inserted with a radial gap C on the inner periphery thereof. Two axial bearings 9 and 9 fixed to the dynamic pressure shaft 7 with axial gaps S1 and S2 are provided at both end faces of the dynamic pressure sleeve, and these constitute a dynamic pressure air bearing portion. ing. A flange 8 is fixed to one end portion of the case 1, a stator core 2 around which an inner peripheral surface is wound with a magnet wire 3, a connection board 13 on which a hall element 12 for switching current is mounted, and the like. Is fixed, and the cover 14 is fixed to the other end portion, thereby forming a stator. (Hereinafter, the non-rotating part such as the dynamic pressure sleeve 6 of the dynamic pressure air bearing part and the stator are referred to as “fixed member side”.)
A magnet holding member 5 is fixed to the outer periphery of one axial bearing 9, and a rotor magnet 4 is fixed to a position of the magnet holding member 5 facing the stator core 2. A mirror holding member 10 is fixed to the outer periphery of the other axial bearing 9, and a rotating mirror 11 is mounted on the mirror holding member 10. Furthermore, a balance correction member 15 is fixed to the end of the dynamic pressure shaft 7 on the side where the rotary mirror 11 is not mounted, and a rotor is constituted by these members. (Hereinafter, the rotating part such as the dynamic pressure shaft 7 of the dynamic pressure air bearing part and the rotor are referred to as “rotating member side”.)
The stator core 2 that is the fixed member is decentered downward by a predetermined amount with respect to CL that is the rotation center axis of the rotating member, thereby constituting magnetic correction means.
[0009]
This magnetic correction means will be described in detail with reference to FIG. 3. The magnetic attractive force F acting on the rotor magnet 4 has a distribution of the contour H, and as a sum, a magnetic attractive force opposite to the gravity direction G is generated. Since the weight on the rotating member side such as the dynamic pressure shaft 7, the rotating mirror 11, and the rotor magnet 4 is subtracted by this magnetic attraction force, the contact surface between the dynamic pressure shaft 7 and the dynamic pressure sleeve 6 at the time of start and stop The pressure can be reduced, problems at the time of starting and stopping can be eliminated, and the life of the dynamic pressure air bearing portion can be improved.
[0010]
Although the case where the dynamic pressure sleeve 6 is the fixed member side and the dynamic pressure shaft 7 is the rotating member side has been described, the rotor magnet 4 is fixed to the dynamic pressure sleeve 6 to be the rotating member side, and the dynamic pressure shaft 7 is the case 1. As a matter of course, the fixed member side can be configured in the same manner, and the axial bearings 9 and 9 can be changed to known magnetic thrust bearings. The flange 8, the magnet holding member 5, and the mirror holding are optional. It goes without saying that the components such as the member 10 can be arbitrarily used as necessary.
[0011]
Next, different embodiments considered by the inventors will be described in detail with reference to FIGS. In the description of the different embodiments considered by the inventor, the same reference numerals are given to the same requirements as those of the first embodiment considered by the inventor, and the detailed description is omitted.
[0012]
4 is a longitudinal sectional view of a hydrodynamic air bearing type optical deflector according to a second embodiment considered by the inventor, and FIG. 5 is a VV sectional view of FIG. FIG. 8 is a diagram for explaining the operation of the magnetic correction means. Reference numeral 18 denotes a core made of a ring-shaped ferromagnetic material, which is fixed to the end of the magnet holding member 5. By fixing the radial magnet 16 magnetized in the thickness direction to the case 1 facing the core 18 and located above the core 18 with a predetermined interval, Magnetic correction means is configured.
[0013]
This magnetic correction means will be described in detail with reference to FIG. 8. A magnetic attractive force F of the radial magnet 16 is generated in the core 18 in the direction opposite to the gravity direction G, and the magnet holding the core 18 is held. Since the weight on the rotating member side such as the dynamic pressure shaft 7, the rotating mirror 11, and the rotor magnet 4 is subtracted by this magnetic attractive force via the member 5, the dynamic pressure of the first embodiment considered by the inventor is considered. Similar to the air bearing type optical deflector, the contact surface pressure between the dynamic pressure shaft 7 and the dynamic pressure sleeve 6 at the time of starting and stopping can be reduced, and problems at the time of starting and stopping can be eliminated. The service life of the dynamic pressure air bearing portion can be improved.
[0014]
It should be noted that either the dynamic pressure sleeve 6 or the dynamic pressure shaft 7 may be on the rotating member side, and that the components such as the flange 8 can be arbitrarily changed as necessary in the first embodiment considered by the inventor. It is the same as the form.
[0015]
Although not shown, the radial magnet 16 is formed in a ring shape and is magnetized in the radial direction, and the outer periphery of the core 18 and the radial magnet are placed on the case 1 on the fixing member side at a position facing the core 18. The same effect can be obtained even if the gap is fixed so that the distance from the inner circumference is narrower on the upper side and wider on the lower side.
[0016]
Further, instead of the core 18 made of a ferromagnetic material, a ring-shaped magnet magnetized in the radial direction is fixed to the rotating member side such as the magnet holding member 5 so that the magnetic pole on the surface facing this is different. A radial magnet (not shown) magnetized in the thickness direction as shown in FIG. Even if it is fixed to the fixed member so that a magnetic attractive force is generated in the opposite direction, the radial magnet that is magnetized so that the magnetic pole on the surface facing the ring magnet is the same polarity is The same effect can be obtained even if it is fixed to the fixing member side so that a magnetic repulsive force is generated.
[0017]
In addition, as shown in FIG. 6, both sides of the radial magnet 16 are sandwiched between two yokes 17 made of a ferromagnetic material, so that the magnetic attraction force or the magnetic repulsion force can be efficiently obtained, and the core 18 or the illustrated figure is shown. It can act on the ring-shaped magnet.
[0018]
Further, in the dynamic pressure air bearing optical polarizer of the second embodiment considered by the inventor, the core 18 has a laminated structure of a plurality of silicon steel plates or a sintered structure of a ferromagnetic material. During the rated rotation of the optical polarizer, eddy current loss that occurs secondary by the magnetic correction means can be reduced.
[0019]
Next, the dynamic pressure air bearing type optical deflector according to the first embodiment of the present invention will be described in detail with reference to FIGS. In the description of the first embodiment of the present invention, the same reference numerals are given to the same requirements as those of the first and second embodiments considered by the inventor, and the detailed description is omitted. .
[0020]
FIG. 9 is a longitudinal sectional view of the dynamic pressure air bearing type optical deflector according to the first embodiment of the present invention, and FIG. 10 is a sectional view taken along line XX of FIG. FIG. 11 is a diagram for explaining the operation of a plurality of magnetic correction means. Cores 18 and 18 made of a ring-shaped ferromagnetic material are fixed to the end portions of the mirror holding member 10 and the magnet holding member 5, respectively, as in the second embodiment considered by the inventor. The radial magnets 16 magnetized in the thickness direction are respectively provided on the flange 8 and the cover 14 which are opposed to the cores 18 and 18 and located on the fixing member side above the cores 18 and 18. A dynamic pressure air bearing type optical deflector is provided with a plurality of magnetic correction means and an adjustment mechanism that can be adjusted in the radial direction. Is configured.
[0021]
The operation of providing a plurality of magnetic correction means and providing an adjustment mechanism that can be adjusted in the radial direction will be described in detail with reference to FIG. 11. A radial magnet 16 facing each of the cores 18 and 18 is described below. 16, magnetic attraction forces F1 and F2 opposite to the gravity direction G act on the rotating member side, and the own weight W generated at the center of gravity COG on the rotating member side such as the rotating mirror 11 and the dynamic pressure shaft 7 is The gaps GAP between the radial magnets 16 and 16 and the cores 18 and 18 can be respectively adjusted by the long holes of the radial magnets 16 and 16 and subtracted by the magnetic attractive forces F1 and F2, and L1 × F1 = By adopting L2 × F2, the moment M is also eliminated, and the contact surface pressure generated between the dynamic pressure shaft 7 and the dynamic pressure sleeve 6 at the time of starting and stopping can be reduced. The same effects as those of the first and second embodiments can be obtained. Even when the dynamic pressure shaft 7 is used obliquely, optimum conditions can be set by appropriately adjusting each GAP.
[0022]
The present invention is not limited to this embodiment, and it goes without saying that it can be combined with known techniques.
[0023]
【The invention's effect】
As described above in detail, according to the structure of the dynamic pressure air bearing type optical polarizer according to the present invention, the motion generated by the weight of the rotating member at the time of starting and stopping or in a state where the generation of dynamic pressure is insufficient. The contact surface pressure of the compressed air bearing can be reduced by the eccentricity of the stator core or the magnetic attraction force or magnetic repulsion force of another member, reducing the starting friction torque at the start / stop and reducing the starting failure. In addition, it is possible to improve the repeated life of starting and stopping.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a hydrodynamic air bearing type optical polarizer of a first embodiment considered by the inventor.
2 is a cross-sectional view taken along the line II-II in FIG.
FIG. 3 is a diagram for explaining the operation of the magnetic correction means of the first embodiment considered by the inventor.
FIG. 4 is a longitudinal sectional view of a hydrodynamic air bearing type optical polarizer of a second embodiment considered by the inventor.
5 is a cross-sectional view taken along line VV in FIG.
FIG. 6 is a longitudinal sectional view of a dynamic pressure air bearing type optical polarizer showing a configuration example of another magnetic correction means of the second embodiment considered by the inventor.
FIG. 7 is a longitudinal sectional view showing the periphery of a dynamic pressure bearing portion of a dynamic pressure air bearing type optical polarizer, showing a configuration example of another magnetic correction unit of the second embodiment considered by the inventor.
FIG. 8 is a diagram for explaining the operation of the magnetic correction means of the second embodiment considered by the inventor.
FIG. 9 is a longitudinal sectional view of a dynamic pressure air bearing type optical polarizer according to the first embodiment of the present invention.
10 is a sectional view taken along line XX in FIG.
FIG. 11 is a diagram for explaining the operation of the magnetic correction unit according to the first embodiment of the present invention.
FIG. 12 is a longitudinal sectional view of a conventional hydrodynamic air bearing type optical polarizer.
[Explanation of symbols]
1: Case, 2: Stator core,
4: Rotor magnet, 5: Magnet holding member,
6: Dynamic pressure sleeve, 7: Dynamic pressure shaft,
8: Flange, 9: Axial bearing,
10: Mirror holding member, 11: Rotating mirror,
12: Hall element 13: Substrate for connection
14: Cover, 15: Balance correction member,
16: radial magnet, 17: yoke,
18: Core, 19: Screw,
C: radial gap, S1, S2: axial gap,
CL: rotation center axis, G: direction of gravity,
F1, F2: magnetic attractive force, COG: center of gravity,
GAP: gap.

Claims (1)

A dynamic pressure air bearing portion comprising a dynamic pressure shaft and a dynamic pressure sleeve, which are rotatably fitted to each other via a dynamic pressure bearing by a herringbone groove and other dynamic pressure generating portions, is rotated via this dynamic pressure air bearing portion. In a hydrodynamic air bearing type optical deflector that supports a mirror and other rotating members in a rotatable manner, and uses a dynamic pressure shaft exclusively in a direction other than vertical, particularly in a horizontal direction, a substantially ring provided in the axial direction on the rotating member side A plurality of radial magnets having a plurality of cores made of a ferromagnetic material and an adjustment function that can be adjusted in the radial direction, provided on the fixing member side facing each of the cores and positioned above the cores A dynamic pressure air bearing type optical polarizer comprising a magnetic correction means that acts in a direction to relieve gravity applied to a rotating mirror or other rotating member side .

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