JP2008070457A - Deflection scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the variation in balance of a deflection scanner without increasing the number of components, mass production processes and cost, further by stabilizing a contact state so as not to deteriorate the deformation of a reflection face by pressurization. <P>SOLUTION: The face of a leaf spring 10 having a continuous radius of curvature is made contact to a rotating polygon mirror 43 along the radial direction of the rotating polygon mirror 43, and the face having the continuous radius of curvature is made contact to the rotating polygon mirror 43 also along the tangential direction of the rotating polygon mirror 43. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a deflection scanning device inside an optical scanning device, which is provided in an image forming apparatus such as an LBP, a copying machine, or a FAX, which has a function of forming an image by exposing a laser beam onto an image carrier. .

  The deflection scanning device provided in the optical scanning device is increasing in speed and needs to satisfy the requirements of high accuracy and low noise.

  In order to satisfy these, it is necessary to suppress the balance fluctuation of the deflection scanning device. When the balance fluctuates and deteriorates, the deflection scanning device becomes a large vibration source in the entire image forming apparatus, and the vibration noise is increased. Furthermore, since the vibration promotes the vibration of optical elements such as lenses and mirrors other than the deflection scanning device in the optical scanning device and leads to deterioration of image quality, it is indispensable to suppress the balance fluctuation surely. .

  Conventionally, there is a configuration as disclosed in Patent Document 1 as means for suppressing these balance fluctuations. This is a method of suppressing fluctuations in balance by pressing and fixing with a leaf spring when fixing the rotor boss and the rotating polygon mirror in the deflection scanning device, and applying an adhesive to the fitting portion of the rotor boss and the rotating polygon mirror. .

Moreover, in patent document 2, in order to fix a rotary polygon mirror to a hub, the presser spring which consists of a radial pressing arm part is employ | adopted. And the curved part formed in the free end of the press arm part presses the upper surface of the rotary polygon mirror by the pressure of the presser spring, and the rotary polygon mirror is fixed to the hub so as not to move.
Japanese Patent Laid-Open No. 10-10455 Japanese Utility Model Publication No. 5-52812

  However, in the above prior art, the fixing method of the rotary polygon mirror in Patent Document 1 has the following drawbacks.

  In the case of fixing using an adhesive, it is an advantageous fixing method at room temperature. However, since the adhesive tends to expand and contract when environmental changes such as temperature and humidity occur, it is pulled by deformation of the adhesive and causes balance fluctuations.

  Another drawback is the shape of the contact portion of the leaf spring. Since the rotary polygon mirror is pressed by the bending portions of the plurality of spring legs, in reality, the two ends of the foot often come into contact with each other due to the characteristics of bending. Therefore, pressure may be applied at one point only on one side of the foot due to variations in mass production. Moreover, since the contact portion is in the same direction as the machining grind on the upper surface of the rotary polygon mirror, it is easy to get caught, and the degree of catching changes depending on how the load is applied.

  When such one-piece fixing or catching on the processing grind occurs, the pressure applied to the rotary polygon mirror changes for each of the plurality of spring legs. Therefore, the position of the rotary polygon mirror is displaced or the leaf spring itself is slightly deformed due to impact due to dropping, vibration during transportation, environmental fluctuations due to temperature and humidity, and repeated driving and stopping, so that balance fluctuations are likely to occur.

  Further, in the presser spring described in Patent Document 2, the portion where the curved portion formed at the free end of the pressing arm presses the upper surface of the rotary polygon mirror is only in the radial direction with respect to the axis of the rotary polygon mirror. The shape has a curvature. For this reason, as described above, the two ends of the curved portion often come into contact with each other, and pressure may be applied at one point only on one side due to variations. Thus, even in the case of Patent Document 2, balance fluctuation is likely to occur.

  The present invention does not increase the number of parts and mass production process, does not increase the cost, and further stabilizes the contact state so as not to deteriorate the deformation of the reflecting surface due to pressure, thereby changing the balance of the deflection scanning device. It aims at suppressing.

In order to achieve the above object, the present invention provides:
In the deflection scanning device that deflects and scans the light beam from the light source by fixing the rotary polygon mirror to the rotor portion of the drive motor and rotationally driving the drive motor,
The rotary polygon mirror is configured to be pressure-fixed to the rotor portion of the drive motor by an elastic member having a plurality of pressure portions,
The elastic member is in contact with the rotary polygon mirror at a surface having a continuous curvature in a radial direction and a tangential direction of the rotary polygon mirror.

Further, in a deflection scanning apparatus that deflects and scans a light beam from a light source by fixing a rotary polygon mirror to a rotor portion of a drive motor and rotating the drive motor.
The rotary polygon mirror is configured to be pressure-fixed to the rotor portion of the drive motor by an elastic member having a plurality of pressure portions,
The elastic member presses a concentric continuous convex portion provided on an upper surface of the rotary polygon mirror on a surface having a continuous curvature with respect to a tangential direction of the rotary polygon mirror, and the convex portion is a rotary polygon surface. It is a surface having a continuous curvature in the radial direction of the mirror.

  According to the present invention, the contact state is stabilized without increasing the number of parts and the mass production process, without increasing the cost, and without deteriorating the deformation of the reflecting surface due to pressurization. Balance fluctuation can be suppressed.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

  Hereinafter, Example 1 will be described with reference to the drawings.

  FIG. 1 is a schematic sectional view of a deflection scanning device 51 provided in an optical scanning device to which the present invention can be applied.

  A fixed sleeve 24 (part of the stator portion) made of a ceramic material is fixed to the housing 23 of the drive motor 44, and a rotary shaft 25 (part of the rotor portion) made of a ceramic material having a second permanent magnet 27 at the lower end. ) Is rotatably fitted to the fixed sleeve 24. A rotor boss 13 made of aluminum, brass, or the like is attached and fixed to the outer periphery of the rotary shaft 25 by shrink fitting or the like. Further, the rotor yoke 20 is integrated by caulking on the outer side, and a rotor magnet is formed on the inner peripheral surface of the rotor yoke 20. 16 is provided.

  Here, the rotor boss 13 has a receiving seat for the rotating polygon mirror 43 and a fitting portion into which the inner peripheral portion of the rotating polygon mirror 43 is fitted. The rotating polygon mirror 43 serves as an elastic member as the receiving seat for the rotor boss 13. The leaf spring 10 is fixed with a fixing screw 12. The rotor boss 13 and the rotating shaft 25 constitute a rotor part.

  Further, a drive motor is provided by arranging a stator including a coil 22 and a core 21 on the substrate 15 fixed on the housing 23 so as to face the rotor magnet 16 on the inner peripheral surface of the rotor yoke 20. Is configured.

  On the other hand, a first permanent magnet 26 is attached to the lower end portion of the fixed sleeve 24, and a second permanent magnet 27 is fixed to the lower end portion of the rotating shaft 25 at a position facing the first permanent magnet 26. ing. A cover 17 for forming the air reservoir 30 is attached to the lower end of the first permanent magnet 26. The first permanent magnet 26 and the second permanent magnet 27 are configured such that magnetic poles facing each other in the circumferential direction (radial direction of the shaft) perpendicular to the axial direction are different magnetic poles. As a result, the rotary shaft 25 is levitated by the magnetic force acting between the two permanent magnets and is driven to rotate without contact.

  FIG. 2 is a schematic top view of the leaf spring 10.

  In the leaf spring 10, a tip 19 as a pressurizing portion is a spherical surface having an arbitrary constant curvature, and the upper surface of the rotary polygon mirror is pressed and fixed by the spherical portion at the tip. The required total load varies depending on the weight of the object to be fixed, the impact applied, the coefficient of friction between the objects, etc., but if the number of legs is large, the required total load is dispersed and the deterioration of the reflective surface accuracy of the rotating polygon mirror is suppressed. it can. The material of the leaf spring is stainless steel for springs, and the material of the rotary polygon mirror is Al (aluminum).

  FIG. 3 is a schematic diagram showing a configuration of an optical scanning device 52 provided with the deflection scanning device 51.

  A laser beam (light beam) generated from a laser unit 41 as a light source is guided to a rotating polygon mirror 43 by a cylindrical lens 42. The laser beam reflected and deflected by the rotary polygon mirror 43 sequentially passes through the fθ lens 45 and the folding mirror 46 and finally reaches the surface of the photosensitive drum 53 to form a latent image. The fθ lens 45 is designed so that the laser beam reflected by the rotary polygon mirror 43 is condensed so as to form a spot on the photosensitive drum 53, and the scanning speed of the spot is kept constant.

  The rotary polygon mirror 43 is rotationally driven by a drive motor 44. A unit combining the rotary polygon mirror 43 and the drive motor 44 is a deflection scanning device 51. Further, a part of the deflected laser beam is reflected by the signal detection mirror 48 using a portion outside the image region, guided to the signal detection sensor 50 via the imaging lens 49, and detected, and the image writing position. Adjustments have been made. These components are accurately assembled to the optical scanning device 52.

  The main scanning is performed on the photosensitive drum 53 by the rotation of the rotary polygon mirror 43, and the sub scanning is performed by rotationally driving the photosensitive drum 53 around the axis of the cylinder.

  With the above configuration, the phenomenon and effect of the present embodiment will be described below.

FIG. 4A shows a pressurization mark when a rotary polygon mirror is pressed with a general leaf spring shape.
Reference numerals 1, 32, and 33 are pressure marks (sometimes referred to as contact portions) of three leaf spring legs. FIG. 4B is an enlarged view of the pressurization mark 31. FIG. 5A shows pressurization marks in this embodiment, and 34, 35, and 36 are pressurization marks (sometimes referred to as contact portions) of three leaf spring legs. FIG. 5B is an enlarged view of the pressurization mark 35.

  In FIG. 4 (a), as with the pressing marks 32 and 33, one spring leg usually comes into contact at two points on both ends of the bent part, whereas the contact part 31 comes into contact with one point. Can be confirmed. On the other hand, in the contact portions 34, 35, and 36 in FIG. 5A, the contact surface is a spherical surface, so that the contact can be reliably made at one point (precisely, a surface by Hertz contact).

  When the contact part 31 in FIG. 4B pressurizes, the contact part scrapes the surface while catching the processing grind on the upper surface of the rotary polygon mirror, whereas in the contact part 35 in FIG. Pressure marks remain so as to bite into a substantially circular shape.

  Furthermore, the contact state of the spherical surface part of a present Example is demonstrated using FIG.

  FIG. 6 is a schematic cross-sectional view of the leaf spring foot in the present embodiment, showing the contact state between the rotary polygon mirror and the leaf spring. FIG. 6A shows the shape just before pressurization, and FIG. 6B shows the shape after pressurization.

  First, the spherical tip contact portion (before pressurization) 60 reliably contacts the rotary polygon mirror contact portion 61 at one point. As the load increases, it begins to bite into the rotating polygonal mirror and bites while changing (sliding) the maximum pressure point (the bottom end of the contact portion) of the spherical surface. That is, the maximum pressure point moves from the spherical tip contact portion (before pressurization) 60 of the leaf spring to the spherical tip contact portion (after pressurization) 62. At this time, as the load increases, the amount of biting increases, so the contact area increases, but the contact shape remains substantially circular. That is, the point of contact with the rotary polygon mirror on the leaf spring side changes depending on the load, but the point of pressure applied to the rotary polygon mirror does not change even when the load increases, so that the pressurization mark is maintained in a substantially circular shape.

  As described above, according to the present embodiment, since the plurality of leaf spring legs and the contact portion of the rotary polygon mirror can reliably contact each other at one point, the contact shape between the rotary polygon mirror and the leaf spring is always maintained. It can be stabilized. For this reason, even if impact, vibration, environmental fluctuation, repetition of driving and stopping, and the like are applied, balance fluctuation of the deflection scanning device can be suppressed. That is, the contact state can be stabilized without increasing the number of parts and the mass production process, without increasing the cost, and without deteriorating the deformation of the reflecting surface due to pressurization, thereby suppressing the balance fluctuation of the deflection scanning device. Can do. Thereby, vibration noise and image quality deterioration of the optical scanning device can be prevented.

  In the present embodiment, the tip of the leaf spring is described as an example of a spherical surface, but it may not be an accurate spherical surface with a constant curvature.

  FIG. 7 shows one of a plurality of leaf spring leg tip shapes, wherein FIG. 7 (a) is a schematic top view, and FIG. 7 (b) is a BB line shown in FIG. 7 (a). The schematic sectional drawing in alignment with is shown.

  The distal end portion 64 of the leaf spring 63 is in contact with a surface having an arbitrary continuous curvature with respect to the radial direction of the rotary polygon mirror, and also has an arbitrary continuous curvature with respect to the tangential direction of the rotary polygon mirror. It is the structure which is contacting in the surface which has.

  Even in the configuration as described above, similarly, the shape of the contact portion between the rotary polygon mirror and the leaf spring is always stable, so that fluctuation in balance can be suppressed.

  Example 2 will be described below. FIG. 8 is a schematic sectional view of a leaf spring in the second embodiment. The leaf spring 70 has a bent portion 72 and a tip portion 73. FIG. 9 is a schematic cross-sectional view of the leaf spring 71 from which the bent portion 72 of the leaf spring is eliminated. The functions of the respective parts (not shown) constituting the deflection scanning device are the same as those in the first embodiment, and the details are omitted.

  In this embodiment, when the load required to fix the rotary polygon mirror is large, the bending spring 72 may come into contact with the upper surface of the rotary polygon mirror by bending the leaf spring when the load is applied. There is sex. In that case, it is good to change to an arbitrary angle like the bending part 72. Along with this, the bending portion 72 is not contacted, and the free length becomes longer so that the load can be selected more freely.

  As shown in FIG. 9, the bending part 72 may be eliminated. In this case, since the number of bends is small, the accuracy can be improved and the load variation of each spring leg can be suppressed.

  In this embodiment, like the first embodiment, the contact shape between the rotary polygon mirror and the leaf spring is always stable. For this reason, even if impact, vibration, environmental fluctuation, repeated driving and stopping, etc. are applied, balance fluctuation of the deflection scanning device can be suppressed, and the bent portion 72 contacts the rotary polygon mirror even if the leaf spring is bent. There is nothing. Thereby, vibration noise and image quality deterioration of the optical scanning device can be prevented.

  Further, here, the tip of the leaf spring is described as an example of a spherical surface, but it may not be an accurate spherical surface with a constant curvature. In other words, the shape of the tip of the leaf spring is in contact with a surface having an arbitrary continuous curvature with respect to the radial direction of the rotary polygon mirror, and also with an arbitrary continuous curvature in the tangential direction of the rotary polygon mirror. The structure which is contacting in the surface which has this may be sufficient. Also in this case, since the shape of the contact portion between the rotary polygon mirror and the leaf spring is always stable, balance fluctuation can be suppressed.

  FIG. 10 is a schematic top view of the deflection scanning apparatus according to the third embodiment. 11 is a schematic cross-sectional view taken along the line CC shown in FIG. The functions of the respective parts (not shown) constituting the deflection scanning device are the same as those in the first embodiment, and the details are omitted.

  80 is a leaf spring as an elastic member, 81 is a rotary polygon mirror, 82 is a fixing screw, 83 is a rotor boss, 84 is a convex portion of the rotary polygon mirror, and 85 is a tip portion that is the tip of the plate spring 80. Here, the rotor boss 83 corresponds to the rotor boss 13 in the first embodiment, and constitutes a rotor portion together with the rotating shaft 25.

  The tip portions 85 of the eight leaf spring legs have a cylindrical surface having an arbitrary constant curvature in the tangential direction of the inner diameter of the rotary polygon mirror 81. On the other hand, on the upper surface of the rotary polygon mirror 81, there is a rotary polygon mirror convex portion 84 provided continuously in a concentric manner.

  At this time, the leaf spring 80 is configured to pressurize an arbitrary position of the continuous rotating polygonal mirror convex portion 84 by a tip portion 85 as a pressurizing portion. The rotating polygon mirror convex portion 84 is a cylindrical surface having an arbitrary constant curvature in the radial direction of the inner diameter of the rotating polygon mirror 81. That is, in this embodiment, the leaf spring and the rotary polygon mirror are in contact with each other between the cylindrical surfaces, so that they contact at one point when no load is applied.

  The contact state of a present Example is demonstrated using FIG.

  FIG. 12 is a schematic perspective view of the rotary polygonal mirror 81 cut along the CC section shown in FIG.

  When pressure is applied at the distal end portion 85 of the leaf spring, a plurality of pressure marks 86 are formed on the rotating polygon mirror convex portion 84. If the curvatures of the rotary polygon mirror convex portion 84 and the leaf spring tip portion 85 are the same, the pressurization trace is substantially circular, and if different, the pressurization trace is substantially elliptical. In either case, when the pressure is applied, the tip end portion 85 of the leaf spring bites in such a manner that the pressure mark area increases due to variations in the load, but the shape does not change. That is, the shape of the contact portion is stable, and there is no need to consider the degree of catching. Further, since the rotating polygon mirror convex portion 84 is a thick portion, it is advantageous for surface deformation of the reflecting surface of the rotating polygon mirror due to pressurization.

  As described above, according to the present embodiment, since the contact shape between the rotary polygon mirror and the leaf spring is always stable, even if impact, vibration, environmental fluctuation, repeated driving and stopping, etc. are applied, the deflection scanning device Balance fluctuation can be suppressed. That is, the contact state can be stabilized without increasing the number of parts and the mass production process, without increasing the cost, and without deteriorating the deformation of the reflecting surface due to pressurization, thereby suppressing the balance fluctuation of the deflection scanning device. Can do. Thereby, vibration noise and image quality deterioration of the optical scanning device can be prevented.

  Further, the shape of the rotating polygon mirror convex portion 84 and the tip of the leaf spring need not be a cylindrical surface with a constant curvature, and the same effect can be obtained as long as the surface has a continuous curvature.

2 is a cross-sectional view of a deflection scanning device and a leaf spring in Embodiment 1. FIG. 3 is a top view of a leaf spring in Embodiment 1. FIG. 1 is a configuration diagram illustrating an optical scanning device in Embodiment 1. FIG. It is a figure which shows the pressurization trace of the rotary polygon mirror and leaf | plate spring in a comparative example. It is a figure which shows the pressurization trace of the rotary polygon mirror and leaf | plate spring in Example 1. FIG. In Example 1, it is the figure which showed the contact state of a rotary polygon mirror and a leaf | plate spring. It is the figure which showed another form of the spring in Example 1. FIG. 6 is a cross-sectional view of a leaf spring in Example 2. FIG. It is the figure which showed another form of the leaf | plate spring in Example 2. FIG. 6 is a top view of a deflection scanning device and a leaf spring in Embodiment 3. FIG. It is sectional drawing of the deflection | deviation scanning apparatus and leaf | plate spring in Example 3. 6 is a perspective view of a rotary polygon mirror in Embodiment 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Leaf spring 19 Tip part 13 Rotor boss 41 Laser unit 43 Rotating polygon mirror 44 Drive motor 51 Deflection scanning device

Claims (3)

In the deflection scanning device that deflects and scans the light beam from the light source by fixing the rotary polygon mirror to the rotor portion of the drive motor and rotationally driving the drive motor,
The rotary polygon mirror is configured to be pressure-fixed to the rotor portion of the drive motor by an elastic member having a plurality of pressure portions,
The deflection scanning apparatus according to claim 1, wherein the elastic member is in contact with the rotary polygon mirror at a surface having a continuous curvature in a radial direction and a tangential direction of the rotary polygon mirror.   The deflection scanning apparatus according to claim 1, wherein the elastic member has a spherical shape at the tips of a plurality of pressurizing portions in contact with the rotary polygon mirror. In the deflection scanning device that deflects and scans the light beam from the light source by fixing the rotary polygon mirror to the rotor portion of the drive motor and rotationally driving the drive motor,
The rotary polygon mirror is configured to be pressure-fixed to the rotor portion of the drive motor by an elastic member having a plurality of pressure portions,
The elastic member presses a concentric continuous convex portion provided on an upper surface of the rotary polygon mirror on a surface having a continuous curvature with respect to a tangential direction of the rotary polygon mirror, and the convex portion is a rotary polygon surface. A deflection scanning device characterized by being a surface having a curvature continuous in a radial direction of a mirror.

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