JP2645526B2 - Fluid bearing type optical deflector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a configuration of a fluid bearing type optical deflector used for an optical scanning system of an image processing apparatus such as a laser printer.

(Prior Art) Conventionally, this type of hydrodynamic bearing type optical deflector comprises a fixed shaft, a rotating member, a rotating member driving means, and a dynamic pressure generating mechanism, as shown in FIG.

Cylindrical portion 15 formed upright at the center of cup-shaped case 15
A set of symmetrical first dynamic pressure generating grooves 22 is engraved on the outer circumference of the inner diameter of a, and a fixed shaft 7 having a cylindrical first thrust magnet 26 fixed to the upper end face is inserted and fixed. I do.

A substrate on which a laminated core 13 around which a magnet wire 14 is wound is protruded outside the cylindrical portion 15a of the case 15, and a Hall element 17 and a lead wire 19 are fixed to the laminated core 13 via a support post 16. Secure 18

A second thrust magnet 27 facing the first thrust magnet 26 fixed to the upper end surface of the fixed shaft 7 and an upper lid;
25 is fixed to the fixed shaft 7
Insert into.

A ring-shaped hub 23 is fixed to the outer periphery of the sleeve 1. The ring-shaped hub 23 is fixed to a cup-shaped movable rotor yoke (hereinafter simply referred to as a rotor yoke) 11 in which the magnet 12 facing the outer diameter of the laminated core 13 and the Hall element 17 is fixed to the inner peripheral surface. And this hub
The rotating polygon mirror 9 and the mirror holding plate 8 are fixed to the upper surface of the bolt 23 in order with bolts 10.

By energizing the magnet wire 14, the wire 14
Are excited, and the rotor yoke 11 rotates in a predetermined direction by the torque generated by the cooperative action with the magnet 12, so that the rotating polygon mirror 9 is moved in the predetermined direction together with the hub 23 connected to the yoke and the sleeve 1 fixed to the hub 23. It rotates and scans light incident on the mirror surface in a predetermined direction. At this time, the sleeve 1 is mainly floated by the reaction between the thrust magnets 26 and 27 and the fluid collides with a set of dynamic pressure generating grooves 22 formed on the fixed shaft 7 while the sleeve 1 floats. The rotating device performs smooth and quick rotation in a non-contact state with the fixed shaft 7. As described above, light reflected on the mirror surface of the rotating polygon mirror 9 rotating in a predetermined direction can be scanned in a predetermined direction.

(Problems to be Solved by the Invention) However, in the configuration of the conventional optical deflector, a bearing mechanism of a rotating member including the sleeve 1, the hub 23, the rotating polygon mirror 9, and the rotor yoke 11 is provided on the outer periphery of the fixed shaft 7. Since the first dynamic pressure generating groove 22 is provided in the dynamic pressure generating portion of the first dynamic pressure generating groove 22 and the magnetic repulsion portion between the first and second thrust magnets 26 and 27, the dynamic force of the first dynamic pressure generating groove 22 Although the radial direction operation of the rotating member is supported by the pressure generating section with relatively high rigidity, the first
The axial support of the rotating member, which is suppressed by the magnetic repulsive force between the first and second thrust magnets 26 and 27 and the pivotal motion of the rotating member with respect to the axis perpendicular to the axis, has a lower rigidity than that of the dynamic pressure generating portion, and is sufficient. The movement is not suppressed, and therefore, the movement of the optical scanning rotary polygon mirror 9 forming the rotating member in a direction other than the rotation direction cannot be sufficiently suppressed, and there is a problem that the optical deflector impairs the optical scanning accuracy. Was.

An object of the present invention is to solve the above-mentioned problems.

(Means for Solving the Problems) In the present invention, in order to solve the above problems, a hydrodynamic bearing type optical deflector having the following configuration is provided.

That is, the cylindrical portion formed upright at the center of the case 15
15a, and a fixed shaft 7 having a base fitted and fixed to the cylindrical portion 15a.
A pair of dynamic pressure generating grooves 22 engraved on the outer periphery of the fixed shaft 7 vertically symmetrically, and the sleeve 1 rotatably supported by the fixed shaft 7 via a dynamic pressure generating portion formed by the dynamic pressure generating grooves 22. A fluid bearing type optical deflection system comprising: a rotating polygon mirror 9 fixed to the outer peripheral position of the sleeve 1 via a hub 23 attached to the sleeve 1; and a rotating member driving means fixed to the sleeve 1 via the hub 23. In the vessel, the rotating polygon mirror 9 is
It is fixed to the sleeve 1 at the outer peripheral position corresponding to the center position of the pattern of the pair of dynamic pressure generating grooves 22 engraved on the fixed shaft 7, and the lower end of the sleeve 1 and the cylindrical A fluid bearing in which a thrust bearing 2 formed by a dynamic pressure generating groove and a ring-shaped washer 20 having elasticity capable of deforming in accordance with a deviation of a right angle of the thrust bearing 2 are interposed between the upper end of the portion 15a. Type optical deflector.

(Operation) In the present invention, first, the sleeve 1, the rotating polygon mirror 9,
When the rotating member such as the buff 23 is rotated by the torque generated by the rotating member driving means, a portion of the first dynamic pressure generating groove 22 formed on the fixed shaft 7 and a second groove formed on the upper end surface of the thrust bearing 21 are formed. In the second dynamic pressure generating groove, a dynamic pressure is generated by the flow of the fluid, and functions as a fluid bearing. Therefore, the rotary polygon mirror 9 moves in the radial direction by the dynamic pressure generated by the first dynamic pressure generating groove 22 of the fixed shaft 7 and in the axial direction and the swing direction by the dynamic pressure generated by the second dynamic pressure generating groove on the upper surface of the thrust bearing 2. Are supported with high rigidity, and smooth rotation is performed, so that the light beam incident on the mirror surface can be scanned in a predetermined direction.

Secondly, the axial position of the dynamic pressure generating portion by the first dynamic pressure generating groove 22 of the fixed shaft 7 substantially coincides with the fixed position of the sleeve 1 of the rotary polygon mirror 9, and particularly the diameter of the rotary polygon mirror 9. Direction movement is suppressed with high rigidity.

Third, since it is easy to machine the coaxiality of the inner and outer diameters of the sleeve 1 satisfactorily, it is possible to suppress the radial deflection of the rotary polygon mirror 9 directly fitted to the outer diameter of the sleeve 1. It is possible.

Fourth, even if a deviation in the perpendicularity between the fixed shaft 7 and the inner diameter of the sleeve 1 and between the thrust bearing 2 and the lower end face of the sleeve 1 is caused, the deformation of the washer 20 having elasticity follows the deformation.
Since the lower end surface of the sleeve 1 and the thrust bearing 2 are maintained in parallel to face each other, good dynamic pressure is generated, and the axial and oscillating motions of the rotary member including the rotary polygon mirror 9 and the like are stabilized. Is measured.

(Embodiment) An embodiment of a hydrodynamic bearing type optical deflector according to the present invention will be described below with reference to the accompanying drawings.

The hydrodynamic bearing type optical deflector of the present embodiment has a fixed shaft, a rotating member,
It has a rotating member driving means and a dynamic pressure generating mechanism.

Cylindrical part formed upright at the center of cup-shaped case 15
A set of first dynamic pressure generating grooves 22 symmetrical to the outer circumference
A fixed shaft 7 made of ceramics, stainless steel, or the like, having a groove formed therein is fixed thereto, and a second dynamic pressure generating groove (not shown) is formed on the upper end surface of the cylindrical portion 15a so as to face the sleeve 1 which will be described later. And a ring-shaped thrust bearing made of ceramic, stainless steel, or the like.

Further, a ring-shaped washer 20 having elasticity is interposed between the cylindrical portion 15a and the thrust bearing 2. Case 15
At the outer diameter of the cylindrical portion 15a, a laminated core 13 around which a magnet wire 14 is wound is protruded, and a substrate 18 to which a Hall element 17 and a lead wire 19 are fixed is fixed to the laminated core 13 via a support post 16. .

A hollow cylinder made of ceramics, stainless steel or the like having an upper lid 21 fixed to the upper end surface thereof so as to face the first dynamic pressure generating groove 22 on the outer periphery of the fixed shaft 7 and the second dynamic pressure generating groove of the thrust bearing 2. The sleeve 1 is rotatably fitted to the fixed shaft 7. Therefore, unlike the conventional example, the magnet groups 26 and 27 provided on the fixed shaft 7 and the upper lid 25 are omitted, so that the axial dimension can be made compact accordingly.

A ring-shaped hub 23 is fixed to the outer periphery of the sleeve 1 with a magnet 12 facing the outer diameter of the laminated core 13 and the Hall element 17 and a cup-shaped rotor yoke 11 having the magnet 12 fixed inside. The rotary polygon mirror 9 and the mirror holding plate 8 are sequentially fixed with bolts 10.

With the above configuration, the sleeve 1, the upper cover 21, the bolt 10, the mirror holding plate 8, the rotating polygon mirror 9, the hub 2
3, the rotating member consisting of the rotor yoke 11, the rotor yoke 11, the magnet 12, the laminated core 12, the magnet wire
When rotated by the torque generated by energizing the magnet wire 14 of the rotating member driving means consisting of 14,
In the first dynamic pressure generating groove 22 of the fixed shaft 7 and in the second dynamic pressure generating groove on the upper end surface of the thrust bearing 2, a dynamic pressure is generated by the flow of air to function as a fluid bearing. Therefore, the rotary polygon mirror 9 is moved in the radial direction by the dynamic pressure generated by the first dynamic pressure generating groove 22 of the fixed shaft 7 and in the axial direction by the dynamic pressure generated by the second dynamic pressure generating groove (not shown) on the upper end surface of the thrust bearing 2. The swinging direction is rotated with high precision in a non-contact state while being supported with high rigidity, and scans the light beam incident on the mirror surface.

Further, in FIG. 1, with respect to a pattern of a symmetric set of first dynamic pressure generating grooves 22 provided on the outer periphery of the fixed shaft 7, the rotary polygonal mirror 9 is positioned in the axial direction and the first dynamic pressure generating grooves are arranged. The mirror holding plate 8 and the bolt 10 are fitted and fixed to the hub 23 so as to face the central portion of the pattern 22. Therefore, in this configuration, the axial position of the dynamic pressure generating portion by the first dynamic pressure generating groove 22 of the fixed shaft 7 substantially coincides with the fixed position of the rotating polygon mirror 9, and particularly, the radial movement of the rotating polygon mirror 9. With high rigidity.

Also, in FIG. 1, the rotary polygon mirror 9 is fitted and fixed directly on the outer periphery of the cylindrical sleeve 1, and this configuration facilitates machining of the coaxiality of the inner and outer diameters of the sleeve 1. In the same manner, it is possible to suppress the fluctuation in the radial assembly accuracy of the rotary polygon mirror 9 directly fitted to the outer diameter of the first mirror.

Further, the ring-shaped washer 20 interposed between the upper end surface of the cylindrical portion 15a of the cup-shaped case 15 and the thrust bearing 2 is made of, for example, an elastic member such as silicon rubber or a member having gel-like viscoelasticity. be able to. With this configuration, even if a deviation between the inner diameter of the sleeve 1 and the perpendicularity between the fixed shaft 7 and the lower end surface of the sleeve 1 and the thrust bearing 2 occurs, the sleeve 1 is deformed in accordance with the deformation of the washer 20 formed of the elastic member. The lower end face and the thrust bearing 2 are held so as to be able to face each other in parallel, a good dynamic pressure generating function is performed, and this helps to stably maintain the movement of the rotating member including the rotating polygon mirror 9 and the like in the axial and swing directions.

(Effects of the Invention) In the present invention, the rotating polygon mirror has a radial direction, an axial direction,
Since both swinging directions can be supported with high rigidity by the action of fluid dynamic pressure, unevenness in scanning speed and blur in the perpendicular direction in optical scanning of the rotating polygon mirror can be reduced, and the axial direction can be reduced compared to the conventional example. Dimensions can be made more compact.

Furthermore, since the generation of dynamic pressure in the axial direction is stable, abnormal wear due to uneven contact between the thrust bearing and the sleeve is prevented, and there is an effect that a long-life thrust dynamic pressure bearing mechanism can be obtained. .

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of a hydrodynamic bearing type optical deflector according to the present invention. FIG. 2 is a sectional view of a conventional hydrodynamic bearing type optical deflector. 1 ... sleeve, 2 ... thrust bearing, 7 ... fixed shaft,
8 ... mirror holding plate, 9 ... rotating polygon mirror, 11 ... rotor yoke (rotating member driving means), 12 ... magnet, 13 ...
Laminated core, 14 ... magnet wire, 15 ... case, 15
a ... Cylindrical part, 20 ... Ring washer, 21 ... Top cover, 22 ... Dynamic pressure generating groove, 23 ... Hub

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuya Hoshi 110-1 Shinkushita Nitta, Iruma City, Saitama Prefecture Inside the Iruma Office of Kopal Electronics Co., Ltd. (72) Inventor Hiroyuki Kaji Shinkumo Nitta, Iruma City, Saitama Prefecture 110-1 Referee Katsutoshi Ishii Referee Akira Watanuki Referee Ichiro Kotani Referee JP-A-63-176814 (JP, A) JP-A 63-271313 (JP, JP) A) JP-A-1-247821 (JP, A)

Claims (1)

(57) [Claims] 1. A cylindrical portion formed upright at a center portion of a case, a fixed shaft having a base fitted and fixed to the cylindrical portion, and a pair of dynamic pressure generators engraved on the outer periphery of the fixed shaft in a vertically symmetric manner. A groove, a sleeve rotatably supported on the fixed shaft via a dynamic pressure generating portion formed by the dynamic pressure generating groove, a rotary polygon mirror fixed to an outer peripheral position of the sleeve via a hub attached to the sleeve, and In a fluid bearing type optical deflector comprising a rotating member driving means fixed to the sleeve via a hub, the rotating polygon mirror corresponds to a central position of a pattern of a pair of dynamic pressure generating grooves engraved on the fixed shaft. A thrust bearing formed by a dynamic pressure generating groove, between a lower end of the sleeve and an upper end of the cylindrical portion, and a right angle of the thrust bearing. If it's against the gap Fluid bearing optical deflector, characterized in that interposed a ring-shaped washer having elasticity may deform.