JP2008089947A - Apparatus for driving rotating polygon mirror - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce wind whistle of an elastic member, to eliminate the galling of the elastic member, when assembled and to improve the reliability of structure for pressurizing and fixing a polygon mirror mounted on a rotor member by using the rotor member, the elastic member and a holding member. <P>SOLUTION: A slit is provided in the inner circumference of the elastic member (spring) 109, a substantially cylindrical shape, extending in the direction substantially vertical to the face of the polygon mirror is provided on the outer circumference, a flange part 113 is configured by bending the cylindrical front end part in the outer circumferential direction so that the part which is made contact with the face of the polygon mirror has a substantially arc shape; further, if the length of the open part of the holding member (stop ring) 110, having a nearly C-shaped cross section is L1 and the minimum value of the with of the inner circumferential side tooth of the elastic member is L2, the relation L2>L1 is satisfied. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotary polygon mirror driving device used for laser scanning of a laser beam printer or the like.

  Conventionally, when a polygonal mirror is attached to a rotor, if a distortion or the like occurs on the mirror surface of the polygonal mirror, the rotating polygon mirror driving device naturally deteriorates its optical characteristics. Even if there is no specular distortion immediately after mounting on the rotor, if the specular distortion occurs due to environmental changes such as temperature, the optical characteristics will be similarly deteriorated.

  Therefore, various fixing methods that make it difficult for the mirror distortion to occur have been proposed. As one means for releasing the generated stress that causes specular distortion, a method of releasing or absorbing stress by pressing using an elastic member such as a spring has been proposed. is there. In general, these elastic members often use leaf springs and the like that are relatively easy to punch with a mold, and most of them are on the inside to facilitate fitting of the elastic members to the rotor. A fitting hole with the rotor is provided, and the outer shape of the elastic member in contact with the polygon mirror plane is a protruding shape with a slit, and the height direction of the protruding portion is finely adjusted to achieve a predetermined uniform load characteristic. ing. However, in the above configuration, in addition to the wind noise of the polygon mirror when the polygon mirror rotates, wind noise is likely to be generated at the protrusions on the outer periphery of the elastic member. In particular, as high-speed printing and colorization of sets such as laser beam printers have progressed in recent years, rotating polygon mirror drive devices have become necessary to rotate at higher speeds, and wind noise from elastic members has become conspicuous. . Thus, as a method for reducing wind noise of the elastic member, a shape in which the slit is disposed inside the elastic member and partially cut is proposed (for example, see Patent Document 1).

  FIG. 2 shows a first structural example of a conventional rotary polygon mirror driving device. FIG. 2A is a longitudinal sectional view thereof, and FIG. 2B is a plan view of a spring having slits arranged on the outer peripheral side. The front view of is shown in (c).

  In FIG. 2, a pair of ball bearings 5 and 7 are fixed coaxially at a distance in the hollow portion 3 of the housing 1. A support piece 9 is provided on the outer periphery of the housing, and a circuit board 11 is fixed to the support piece 9. A plurality of drive coils 13 are arranged on the circuit board 11. The ball bearings 5 and 7 are supported by a cylindrical shaft 15, and a mirror base 17 is formed on the upper end side of the cylindrical shaft 15. The outer periphery of the mirror base 17 faces the drive coil 13. A drive magnet 19 is provided, and a rotating mirror 21 is further placed. A presser plate 23 is placed so as to cover the rotating mirror 21 and is screwed to the upper end of the cylindrical shaft 15 with a screw 25. Further, a screw 29 is screwed into the lower end of the cylindrical shaft 15 via a washer 27 so that the cylindrical shaft 15 does not move upward. The presser plate 23 is cut into a semicircular arc shape at a plurality of locations around the metal disc to provide a void 33, a presser piece 31 is provided, and the presser piece 31 is bent downward. The rotary mirror 21 is elastically pressed by the tip of the piece 31.

  In such a rotating polygon mirror driving device, the cylindrical shaft 15, the mirror base 17, the rotating mirror 21, the pressing plate 23, and the like are integrated by a driving force generated between the driving coil 13 and the drive magnet 19 by switching the energization of the driving coil 13. Rotate to scan.

  FIG. 3 shows a second example of a conventional rotary polygon mirror driving device. FIG. 3A is a plan view of a spring having a slit disposed on the inner peripheral side, and FIG. 3B is a front view of the spring at that time. ).

In FIG. 3, a pair of slits 55 is formed around the insertion hole 53 of the presser plate 54, the gap 55 is cut and raised to form a cut and raised portion 57, and the cut and raised portion 57 is similarly screwed. Similarly, a mirror base or the like (not shown) is held and fixed by pressing it with an or the like (not shown).
Japanese Utility Model Publication No. 6-4729 (2nd page, Fig. 4-8)

  However, in the above-described conventional configuration, wind noise is likely to be generated at the protrusions on the outer periphery of the elastic member in addition to the wind noise of the polygon mirror when the polygon mirror rotates. In particular, as high-speed printing and colorization of sets such as laser beam printers have progressed in recent years, rotating polygon mirror drive devices have become necessary to rotate at higher speeds. Wind noise from elastic members can no longer be ignored. In recent years, in order to save energy by reducing the windage loss of the polygonal mirror, the outer diameter of the polygonal mirror is often set to be small, and accordingly the wind noise of the polygonal mirror has been reduced, and the protrusion shape on the outer periphery of the elastic member There is a problem that it is necessary to reduce wind noise generated in the part.

  As one means for reducing wind noise of the elastic member, there is a method of eliminating the protrusion shape on the outer periphery of the elastic member configured by providing the slit and arranging the slit on the inner periphery of the elastic member. Due to the structure, it is difficult to assemble the elastic member, and if the centering of the elastic member is extremely shifted especially when the elastic member is inserted, there is a possibility that the tooth-shaped part formed by the arrangement of the rotor and the slit inside the elastic member may bite. End up. In particular, when the amount of compression in the vertical direction from the natural length of the elastic member to the mounting height is large, the tip of the inner peripheral tooth-shaped portion is not only compressed and moved in the vertical direction, but is also compressed and moved in the direction of the rotation center. It becomes easier to bite. Therefore, the natural length is initially short, and the degree of compression is set to be small, and the design flexibility such as size is restricted. In addition, by raising and lowering the tooth-shaped part between the inner peripheral slits, the load force in the vertical direction can be somewhat reduced if it is obtained other than the aforementioned raised part, but the shape is protruding, Pursuing high-speed rotation is not preferable from the viewpoint of noise generation.

  In addition, when a part such as a washer having a relatively large outer diameter is used in combination with a holding member such as a screw used for fixing the elastic member such as the spring, the inner diameter of the elastic member having the inner peripheral tooth-shaped portion can be increased. Although it is possible to reduce the galling between the inner peripheral tooth shape portion of the elastic member and the shaft, it is necessary to process a screw hole on the tip of the shaft, and the rotational force that must be applied when screwing is used, such as a ball bearing. In order not to damage the bearing, not only the thrust direction but also the rotor must not be moved in the rotational direction. This also causes problems in terms of quality such as abnormal sounds in the parts.

If such a method is used in which a retaining ring such as a C-type retaining ring or a grip-type retaining ring is fitted and fixed to a shaft or the like instead of a screw, an external force is applied in the rotational direction of the rotor when the elastic member is attached. This eliminates the need to worry about and makes it easier to automate equipment, leading to superior quality and cost. However, since the retaining ring is not connected over the entire circumference, and there is always a part that is open and interrupted after being attached, generally a washer or the like is often used together. In addition, with the recent demand for high-speed rotation of rotary polygon mirror drive devices, it is also necessary to reduce load loss and heat generation during rotation, in order to reduce loss by reducing the peripheral speed of the bearing part. In addition, the diameter of the shaft has been reduced. As the diameter of the shaft progresses, the retaining force of the retaining ring naturally decreases, so as the diameter decreases, a retaining groove is provided on the outer periphery of the shaft, etc., to improve the retaining ring retention strength. become. At that time, there is an increased risk of galling between the aforementioned groove and the inner peripheral tooth shape portion of the elastic portion.

  The present invention solves such a conventional problem, and an object thereof is to provide a rotating polygon mirror driving device that can reduce wind noise during high-speed rotation and is easy to assemble and has excellent reliability. .

  In order to solve the above-mentioned problems, the present invention has a substantially dish shape in which the elastic member such as a spring has a hole in the center portion, and has at least two slits on the inner peripheral hole side, and further on the outer peripheral side. Is a portion that contacts the polygon mirror and has a substantially cylindrical shape extending in a direction substantially perpendicular to the plane of the polygon mirror, and further, a distal end portion of the outer peripheral cylindrical shape is bent in the outer peripheral direction to form a collar portion. The portion in contact with the polygon mirror plane of the portion is formed in a substantially arc shape, and the polygon mirror is fixed by pressing the inner periphery of the elastic member in the polygon mirror plane direction with a holding member. The holding member has a substantially C-shaped cross section, and is fitted and fixed in a groove provided in the rotor member. The length of the substantially C-shaped opening at that time is L1, and the inside of the elastic member When the minimum value of the inner peripheral side tooth width constituted by the circumferential slit is L2, L2> L1.

  The invention according to claim 1 of the present invention is not provided with slits on the outer periphery of the elastic member that is particularly prone to generate wind noise, and has no bulge that is a cause of wind noise generation, and has a smooth shape. Generation of wind noise at the outer periphery can be suppressed. Furthermore, since the tooth-shaped portion between the inner peripheral slits is not cut or raised on the inner peripheral side, it is possible to reduce noise on the inner peripheral side, and it is possible to realize further higher speed.

  Further, by adjusting the height of the substantially cylindrical portion on the outer periphery, the height obtained by subtracting the height of the cylindrical portion from the natural length of the elastic member can be set low, and the vertical portion at the subtracted height portion can be set. It is also possible to set so that the amount of compression in the direction is reduced, and it is also possible to reduce the amount of movement in the direction of the rotation center of the tip of the tooth-shaped portion that occurs as the inner peripheral tooth-shaped portion is compressed in the vertical direction. Further, it is possible to suppress the occurrence of galling at the fitting insertion portion such as the shaft of the inner peripheral tooth shape portion. In addition, when dealing with objects of various heights, it is possible to produce an elastic member having substantially the same load characteristics by adjusting the height of the cylindrical portion.

  In addition, the outer circumferential cylindrical tip of the elastic member is bent in the outer circumferential direction to form a collar, and the part of the collar that contacts the polygon mirror plane is formed in a substantially arc shape, so that burrs and the like are temporarily formed in the cylindrical opening. Even if it occurs, the elastic member does not get into the polygon mirror plane. It should be noted that the force applied to the spring from above is part of the force that pushes the spring cylindrical opening outward as a whole only when it is installed, and the spring opening is evenly spread outward. The inner periphery center itself can be incorporated without moving when the spring is assembled, and can be prevented from galling with the groove portion of the shaft.

  The length of the substantially C-shaped opening when the holding member fixed to the rotor member is cylindrical and the C-shaped holding member is attached to the rotor member is L1, and the inner circumference of the elastic member When the minimum value of the inner peripheral side tooth width constituted by the side slits is L2, by setting L2> L1, the inner peripheral tooth portion of the elastic member passes through the substantially C-shaped opening of the holding member. It has the effect that the attachment failure can be eliminated.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 shows an embodiment of the present invention. FIG. 1A is a longitudinal sectional view, FIG. 1B is a plan view of a spring, and FIG. 1C is a plan view of a retaining ring.

  In FIG. 1, a ball bearing 102 and a ball bearing 103 are mounted on the inner periphery of a housing 101 having a circuit board 114. Further, a core 104 with windings is attached to the outer peripheral portion of the housing 101. A magnet 106 attached to the frame 105 is disposed at a position facing the outer periphery of the core 104. The shaft 107 is inserted into the ball bearing 102 and the ball bearing 103 and is rotatably supported. Further, the frame 105 is attached to the output side of the shaft 107. Further, a polygon mirror 108 is inserted into the frame 105. Further, a spring 109 is inserted from above the polygonal mirror 108, and a retaining ring 110 having a substantially C-shaped cross section is attached to the groove 115 of the shaft 107, so that the spring 109 is compressed and held so that the polygonal mirror does not move. is doing. A tooth-shaped portion 112 is formed by providing a slit 111 on the inner periphery of the spring 109. The length of the substantially C-shaped opening of the retaining ring 110 is L1, and the tooth of the tooth-shaped portion 112 is formed. When the minimum value of the width is L2, L2> L1 is set. Further, the outer peripheral cylindrical tip portion of the spring 109 is bent in the outer peripheral direction, and a collar portion 113 having a substantially arcuate portion in contact with the polygon mirror 108 is provided.

  With the above configuration, the polygon mirror 108 rotates at high speed by the driving force generated between the core 104 and the magnet 106, and scanning is performed. At this time, since the spring 109 does not have a partial protrusion shape on the outer peripheral side, there is no major wind noise caused by air entrainment on the outer peripheral side, and the tooth-shaped portion 112 is also cut on the inner peripheral side. Since no partial protrusion is formed without raising, it is possible to reduce the internal wind noise.

  Further, when the spring is assembled, even if burrs or the like occur at the tip of the spring opening, the polygonal mirror plane is received by the substantially arc-shaped portion, so that the spring does not enter the polygon mirror plane. In addition, the force applied to the spring from above is a force that causes a part of the spring cylindrical opening to be pushed outward as a whole only at the time of installation, and the spring opening is evenly spread outward. The inner periphery center itself can be incorporated without moving when the spring is assembled, and can be prevented from galling with the groove portion of the shaft.

  In addition, since L2> L1, the tooth-shaped portion of the spring does not pass through the opening portion of the retaining ring, so that the mounting failure can be prevented and as a general means for preventing this, It is possible to eliminate parts such as a washer interposed between the spring and the retaining ring.

  Furthermore, by adjusting the height of the cylindrical portion of the spring of this shape, the height obtained by subtracting the height of the cylindrical portion from the natural length of the spring can be set low. It is also possible to set so that the amount of compression in the vertical direction of the tooth is reduced, and the amount of movement in the direction of the center of rotation of the tooth shape portion tip that occurs as the inner peripheral tooth shape portion is compressed in the vertical direction can also be reduced. And the occurrence of galling between the tooth-shaped portion and the shaft and shaft groove portion can be further suppressed. In addition, since the load characteristics in the vertical direction of the spring of this shape are determined at locations excluding the cylindrical portion and the collar portion, the height of the cylindrical portion can be set even when dealing with various heights. By adjusting, it becomes possible to produce springs having almost the same load characteristics.

  In the above description, an example of the structure of the outer rotor type with a circumferentially opposed core has been shown, but there are no particular restrictions on the inner rotor type, the surface facing type, the coreless type, and the like, which can be similarly implemented.

  Further, in addition to the ball bearing, a hydrodynamic fluid bearing, a hydrodynamic air bearing, a magnetic bearing, or the like can be used.

  There are no particular restrictions on the driving method, size, number of rotations, number of faces of the polygon mirror, and the like.

  In addition, there are no restrictions on the materials and materials constituting the other parts, and they may be modified or changed as appropriate. Needless to say, various modifications can be made without departing from the scope of the invention.

  The rotating polygon mirror driving device according to the present invention can suppress the generation of wind noise at the outer peripheral portion of the elastic member. Furthermore, it is possible to reduce noise on the inner circumference side, to achieve higher speed, to suppress the occurrence of galling at the fitting insertion part such as the shaft of the inner peripheral tooth shape part during assembly, Even when dealing with objects of various heights, by adjusting the height of the cylindrical part, it is possible to produce elastic members with almost the same load characteristics, and with a substantially arc-shaped collar part The elastic member does not get into the polygon mirror plane, and the elastic member opening extends evenly to the outside, and the elastic member inner periphery center itself can be installed without shifting, further preventing galling. It is possible to eliminate the mounting failure caused by the inner peripheral tooth portion of the elastic member passing through the substantially C-shaped opening of the holding member, and for laser scanning such as a laser beam printer. It is useful as a rotary polygon mirror drive device or the like to be use.

(A) Longitudinal sectional view showing a rotary polygon mirror driving device according to Embodiment 1 of the present invention, (b) Plan view of a spring in Embodiment 1 of the present invention, (c) Stop in Embodiment 1 of the present invention Top view of the ring (A) Longitudinal sectional view showing a rotary polygon mirror driving device according to the first conventional structure example, (b) Plan view of a spring in the first conventional structure example, (c) Spring in the first conventional structure example Front view of (A) The top view of the spring in the 2nd conventional structural example, (b) The front view of the spring in the 2nd conventional structural example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Housing 3 Housing hollow part 5, 7, 102, 103 Ball bearing 9 Pointing piece 11, 114 Circuit board 13 Coil 17 Mirror base 23, 54 Holding plate 25, 29 Screw 27 Washer 31 Holding piece 33 Space 53 Insertion hole 55, 111 Slit 57 Cut and raised part 104 Core 105 Frame 19, 106 Magnet 15, 107 Shaft 21, 108 Polyhedral mirror 109 Spring 110 Retaining ring 112 Tooth shape part 113 Brim part 115 Groove part L1 Opening part length L2 Minimum tooth width

Claims (1)

A rotor member to which the polygon mirror is attached, a stator member that rotatably supports the rotor, a holding member fixed to the rotor member, and an elastic member is disposed between the holding member and the polygon mirror, and the polygon mirror is elastic In the configuration in which the elastic member is pressed and fixed, the elastic member has a substantially dish shape having a hole in the center portion, and is provided with at least two slits on the inner peripheral hole side, and further on the polygon mirror on the outer peripheral side. It has a substantially cylindrical shape that is a contact portion and extends in a direction substantially perpendicular to the polyhedral mirror plane, and further, the outer circumferential cylindrical tip is bent in the outer circumferential direction to form a collar portion, and the multiple faces of the collar portion The portion in contact with the mirror plane has a substantially arc shape, and the holding member has a substantially C-shaped cross section and is fitted and fixed in a groove provided in the rotor member. C L2> L1, where L1 is an opening length of the shape, and L2 is a minimum value of the inner peripheral side tooth width formed by arranging slits on the inner peripheral side of the elastic member. Rotating polygon mirror drive device.

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