JP5235521B2 - Optical deflection apparatus, optical scanning apparatus, and image forming apparatus - Google Patents

Description

  The present invention relates to an optical deflecting device, an optical scanning device, and an image forming apparatus used in an image forming apparatus such as a laser beam printer or a laser facsimile.

  Conventionally, an optical scanning device used in an image forming apparatus such as a laser beam printer or a laser facsimile deflects and scans a laser beam with a rotating polygon mirror that rotates at high speed. The obtained scanning light is imaged on a photoconductor on a rotating drum to form an electrostatic latent image. Next, the electrostatic latent image on the photosensitive member is visualized as a toner image by a developing device, transferred to a recording medium such as a recording sheet, sent to a fixing device, and the toner on the recording medium is heated and fixed to print (print ) Is performed.

  A rotary polygon mirror is mounted on an optical deflection apparatus used for laser beam deflection scanning. Regarding the shape of the rotary polygon mirror, various proposals have been made as in the inventions described in Patent Documents 1 to 3 depending on the application.

  The rotating polygon mirror described in Patent Document 1 is provided with a plurality of annular recesses for applying balance weight in order to correct dynamic imbalance with high accuracy and high speed. Accordingly, even when the balance is corrected for the first time and re-correction is performed without entering the target balance, the balance weight is applied to the concave portions separated in the radial direction, so that overcoating can be prevented. At the same time, such measures as realizing high-accuracy and high-speed balance correction while reducing the occurrence of axial imbalance have been made.

  A concave portion is formed at the center of the upper surface of the rotary polygon mirror described in Patent Document 2. The rotary polygon mirror is held on the rotating body by the pressing member using the space of the recess. In this way, contrivances are made such as reducing the height dimension in the axial direction of the optical deflecting device and miniaturizing the optical scanning device.

  A plurality of annular grooves are provided on both the upper and lower surfaces of the rotary polygonal mirror described in Patent Document 3, and are thinned. As a result, the inertia of the rotating body is reduced, and the rise time of the apparatus is shortened.

  On the other hand, there has also been a proposal as in the invention described in Patent Document 4 in which an amorphous fluororesin film is applied to the surface of a rotating polygon mirror by a rotating wet film forming method to increase durability.

  An amorphous fluororesin film having a predetermined thickness is formed on the rotary polygon mirror described in Patent Document 4. According to such a method, an anodic oxide film is not required, a large-scale cleaning process is not required, productivity is improved, and cost is reduced.

JP-A-6-208075 JP-A-11-231248 JP 2000-292733 A JP 2002-131682 A

  However, the inventions described in Patent Documents 1 to 4 have the following problems. For example, when the coating liquid is applied to the rotary polygon mirror described in Patent Document 1 by the rotary wet film forming method described in Patent Document 4, there are the following problems.

  In general, after applying an amorphous fluororesin to a rotating polygon mirror, it is basically impossible to apply a balance weight on the amorphous fluororesin film. When the balance weight is an ultraviolet curable resin, the ultraviolet curable resin and the amorphous fluororesin film are not firmly bonded even if the balance weight is applied and cured by irradiation with ultraviolet rays. It will peel off.

  If the balance weight is peeled off from the light deflector with the balance adjusted with high precision, the balance of the rotating body will be lost, generating large vibrations and noise, and the motor bearing driven by the large swing of the rotating shaft. There is friction. In the worst case, the bearing is damaged and eventually the motor cannot be rotated, so-called shaft lock is reached, which may cause a serious failure as the image forming apparatus.

  For this purpose, a method in which the coating liquid is applied by the rotary wet film forming method of Patent Document 4 after the balance weight is applied to the grooves of the rotary polygon mirror of Patent Document 1 can be assumed. However, in this method, it is necessary to prevent the coating liquid from being immersed in the grooves of the rotary polygon mirror of Patent Document 1.

  The rotating polygon mirrors of Patent Document 1 are stacked in a skewered state as shown in FIG. 4 of Patent Document 4 and immersed in the coating solution, and then the rotating polygon mirror is taken out of the coating solution and rotated for each skewer, so-called pseudo Apply a special spin coat to the mirror surface. At this time, even if the liquid surface height and the amount of immersion are sufficiently controlled, the coating liquid enters the gap between the stacked rotary polygon mirrors as if it is a capillary phenomenon, and at least the outer groove has amorphous fluorine. A resin film will adhere.

  If the groove is deepened, the capillary phenomenon is interrupted in the outer groove, so that at least the inner groove may be prevented from entering, but the outer groove cannot be used for application of the balance weight.

  In recent years, rotating polygonal mirrors have been made thinner, and if the groove is made too deep, the rigidity of the workpiece during mirror surface processing is insufficient and the flatness of the mirror surface is impaired. Further, in an image forming apparatus that is increasing in speed, the rotating polygon mirror is also rotated at a high speed. When the rotating polygon mirror is thin and rotated at a high speed, the rotating polygon mirror is deformed by a large centrifugal force generated at the time of rotation. If the groove is deepened in such a situation, the amount of surface deformation due to the centrifugal force increases.

  When the amount of surface deformation increases, there is a risk that the imaging performance on the photosensitive member and the so-called jitter performance, in which the scanning time for each scan differs for each mirror surface, may deteriorate, leading to a decrease in print quality of the image forming apparatus. is there.

  Next, for example, when the coating liquid is applied to the rotary polygon mirror described in Patent Document 2 by the rotary wet film forming method described in Patent Document 4, there are the following problems. This problem can also be said when the rotating polygon mirror described in Patent Document 1 is applied by the rotating wet film forming method described in Patent Document 4.

  When a protective film such as amorphous fluororesin is applied to the rotary polygon mirror of Patent Document 2, as shown in Patent Document 4, the rotary polygon mirror is stacked and stabbed into a skewer and immersed in a coating solution. Is done. Thereafter, the rotary polygon mirror is taken out of the coating solution and rotated for each skewer. A so-called pseudo spin coating is applied to the mirror surface, and then the rotary polygon mirror is fired in an environment of about 170 ° C.

  When trying to separate each rotating polygonal mirror from the skewer after such firing, the overlapping rotary polygonal mirrors stick to each other with a certain amount of fixing force at the abutting portion. The larger the area where the rotating polygon mirrors are in contact with each other, the greater the force required for separation, and separation is difficult. Even if a spatula is inserted and separated, if too much force is applied, the inserted spatula or other tool may be damaged, or a large force may be applied to the rotating polygon mirror itself to cause deformation and affect the mirror surface quality. There is. If it is peeled off forcibly, the mirror surface may be scratched, and the spot on the photoconductor may collapse and the imaging performance may deteriorate.

  In the rotary polygon mirror disclosed in Patent Document 2, the thickness is secured in the vicinity of the mirror surface and the work rigidity is high. However, even if the center portion is removed, the inertia as the rotating body increases as the distance from the rotation axis increases. Therefore, the inertia is not easily lowered, and the so-called rise time until the rotating body reaches a predetermined rated rotation speed does not decrease, and the time required for printing the first sheet of the image forming apparatus, the so-called FPOT (First Print Out Time). There is also the problem of lengthening.

  Next, the rotating polygonal mirror described in Patent Document 3 is formed with a large number of grooves on the front and back surfaces of the rotating polygonal mirror, and is thinned. Forming many such grooves reduces the rigidity of the workpiece during mirror surface processing, as well as deepening the grooves, and impairs the flatness of the mirror surface. In addition, the amount of surface deformation due to centrifugal force increases, and there is a possibility that the image forming performance on the photosensitive member and the above-described jitter performance are deteriorated, which may lead to a decrease in print quality of the image forming apparatus.

  Therefore, the present invention suppresses that the coating liquid enters the area surrounded by the annular convex portion between the stacked rotary polygon mirrors, and the annular concave portion suppresses separation of the balance weight due to the penetration of the coating liquid. It is an object of the present invention to provide an optical deflection device.

In order to solve the above-mentioned problem, the rotary polygon mirror of the present invention has a main body portion in which a plurality of reflecting surfaces are formed at a radial end portion of a rotation shaft, and the main body portion is coated with a balance weight. A rotary polygon mirror having a concave portion recessed in a rotation axis direction and rotating and deflecting and scanning a light beam with the plurality of reflection surfaces, wherein the plurality of reflection surfaces are coated with fluororesin by a rotary wet method in the mirror, the main body portion, said Ki凹 portion inner than the plurality of reflecting surfaces outside than before with respect to the radial direction of the rotating shaft, the rotating shaft direction projecting upper surface flat annular protrusion, said body a flat surface which is made form the positions corresponding to the annular protrusion of the back side of the annular projection parts are formed on the outer side than the annular projection with respect to the radial direction of the rotary shaft, the rotation axis direction Bei wall thickness and a thin walled portion than the annular projection And wherein the Rukoto.
The rotating polygon mirror manufacturing method of the present invention includes a main body portion having a plurality of reflecting surfaces formed at the radial end portion of the rotating shaft, and the main body portion includes a concave portion recessed in the rotating shaft direction. In the manufacturing method of the rotary polygon mirror that rotates and deflects and scans the light beam with the plurality of reflection surfaces, the main body portion is outside the concave portion and inside the plurality of reflection surfaces in the radial direction of the rotation axis. An annular convex portion protruding in the direction of the rotational axis and having a flat upper surface, a flat surface formed at a position corresponding to the annular convex portion on the back side of the annular convex portion of the main body portion, and a radial direction of the rotational shaft And a thin-walled portion formed on the outer side of the annular convex portion and having a thinner thickness in the rotational axis direction than the annular convex portion, and the rotary wet method in a state where the main body portion is overlapped in the rotational axis direction. After the fluororesin is applied to the plurality of reflective surfaces, Wherein the balance weight is applied to the recess.

  According to the present invention, since the annular convex portion is formed at a position farther from the rotation center than the annular concave portion on the surface of the reference thick portion, the rotary polygon mirror is immersed in the coating liquid after the balance weight is applied to the annular concave portion. In this case, the annular convex portion can prevent the coating liquid from entering the annular concave portion. In particular, since the upper surface of the annular convex portion and the back surface of the reference thick portion are formed flat, the upper surface of the annular convex portion and the rear surface of the reference thick portion are surely contacted when a plurality of rotating polygon mirrors are stacked. be able to. The area surrounded by the annular protrusion is closed. Accordingly, it is possible to prevent the coating liquid from entering the region surrounded by the annular convex portion between the rotating polygon mirrors. As a result, in the annular recess, separation of the balance weight due to the penetration of the coating liquid is suppressed.

(First embodiment)
FIG. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus 110 including an optical scanning device. As shown in FIG. 1, a laser beam L modulated based on image information is emitted from an optical box 131 and scans the surface of a photosensitive drum 132 which is a “photosensitive member” to form a latent image. This latent image is formed on the surface of the photosensitive drum 132 that is uniformly charged by the primary charger 133, visualized by the developing device 134, and the images formed on the surface of the photosensitive drum 132 are sequentially transferred. The image is formed by being transferred onto the transfer material 136 by the charging roller 135. The image formed on the transfer material 136 is heat-fixed by the fixing device 137 and then output to the outside of the apparatus by the discharge roller 138 and the like. The “image forming unit” includes the photosensitive drum 132, the primary charger 133, and the transfer charging roller 135.

  FIG. 2 is a perspective view showing the configuration of the optical scanning device 111. The collimated light extracted from the laser unit 41, which is a “light source device”, is reflected and deflected by a rotating polygon mirror (also referred to as “polygon mirror”) 3 provided in an optical deflection device (also referred to as “scanner motor unit”) 1. Scanned. Then, the collimated light sequentially passes through the Fθ lens 43 and the folding mirror 44 and finally reaches the surface of the photosensitive drum 132. The Fθ lens 43 is included in the imaging optical system. The collimated light is shaped by the Fθ lens 43 so as to be scanned as a beam that is optimally narrowed within the width of the photosensitive drum 132. At the same time, a part of the scanning beam is reflected by the BD mirror 45 and is detected by the BD sensor 46, and the writing signal for each scanning time is synchronized with the output signal from the BD sensor 46 as a reference. There is also an effect of preventing the write position deviation. In addition, in order to prevent the displacement of the beam in the sub-scanning direction (the direction perpendicular to both the optical axis direction and the beam scanning direction) on the photosensitive drum 132 due to the tilt error of the reflecting surface of the rotary polygon mirror 3, A lens 47 is used. The cylinder lens 47 compresses the beam extracted from the laser unit 41 on the reflection surface of the rotary polygon mirror 3 in the sub-scanning direction to form a line image. At the same time, the cylinder lens 47 has a configuration in which the reflecting surface of the rotary polygon mirror 3 and the surface of the photosensitive drum 132 have a conjugate relationship in the sub-scanning direction. Further, these components are assembled in an optical box 131 (not shown), and the optical box 131 is provided with a reference pin or the like, and is assembled with high accuracy so as to fall within a dimensional tolerance.

  FIG. 3 is a cross-sectional view of the optical deflection apparatus 1 including the rotary polygon mirror 3 according to the first embodiment of the present invention. As shown in FIG. 3, the light deflection apparatus 1 includes a rotating polygon mirror 3 that reflects a light beam 2 from a light source (not shown) to a scanning lens (not shown). Further, the optical deflecting device 1 includes a rotating polygon mirror 3 and a flange 4 that rotates integrally with the rotating polygon mirror 3, a spring 5 that presses and fixes the rotating polygon mirror 3 to the flange 4, and the spring 5 and the flange 4 are fastened. And a screw 6 for the purpose. Further, the optical deflecting device 1 includes a rotating shaft 7 that is integrally coupled to the flange 4 by press-fitting or the like and extends along the rotation center P, a rotor frame 8 that is integrally coupled to the flange 4 by caulking or the like, and a driving coil 9. The stator 10 which consists of these. In addition, the optical deflection apparatus 1 includes a fluid bearing 12 that holds the rotating shaft 7, and a circuit board 13 that is integrally coupled with the stator 10 and the fluid bearing 12. In such an optical deflecting device 1, a driving current is supplied from the driving circuit 14 and the stator 10 is excited, whereby the rotating shaft 7, the rotor frame 8, the flange 4, the rotating polygon mirror 3, the spring 5, A “rotating body” having screws 6 rotates. Among them, the “rotating member” is configured by including the rotating shaft 7, the rotor frame 8, the flange 4, the spring 5, and the screw 6, and the “rotating member” and the rotating polygon mirror 3 rotate integrally. Note that the “rotating member” and the members constituting the “rotating body” may not include all of the above-described members, but may include only a part thereof.

FIG. 4 is a perspective view of the rotary polygon mirror 3. As shown in FIG. 4, the rotary polygon mirror 3 includes a reference thickness portion 3 a (main body portion) formed with a predetermined thickness. On the surface of the rotary polygon mirror 3, an annular concave portion 15 and an annular concave portion 16 for correcting balance are formed. The annular recess 15 is an inner recess, and the annular recess 16 is an outer recess. The annular recess 15 and the annular recess 16 are formed with a thickness thinner than the reference thickness portion 3a.

  The balance correction for reducing the vibration of the “rotating body” including the rotating polygon mirror 3 and the rotor frame 8 is performed as follows. A dynamic imbalance (unbalance) generated by rotating the “rotor” is measured by a measuring instrument. Next, based on the measured unbalance, in the rotary polygon mirror 3, a balance weight 17 made of ultraviolet curable resin is applied to the annular recess 15, and a balance weight 18 made of UV curable resin is applied to the annular recess 16. By providing the balance weights 17 and 18, the balance of the mass of the “rotating body” is corrected. Balance weights 17 and balance weights 18 having different specific gravities are used to finely and roughly adjust the balance.

  Further, on the surface of the reference thick portion 3a of the rotary polygon mirror 3, an annular and convex annular convex portion 19 for correcting the balance is formed. The annular convex portion 19 is formed at a position farther from the rotational center P of the “rotating portion” than the annular concave portion 15 and the annular concave portion 16. That is, the annular convex portion 19 is formed on the outer peripheral side of the annular concave portion 16. The upper surface 20 of the annular convex part 19 is formed flat. Further, the upper surface 20 of the annular convex portion 19 is formed as the highest uppermost surface on the surface of the rotary polygon mirror 3.

  FIG. 5 is a diagram for explaining a rotating wet film forming method of the rotating polygon mirror 3. As shown in FIG. 5, an amorphous fluororesin film is applied to the reflecting surface 21 of the rotating polygon mirror 3 by a rotating wet film forming method for protecting the reflecting surface. The rotary polygon mirrors 3 are stacked and skewered on the skewer 22, and the plurality of rotary polygon mirrors 3 are immersed in the amorphous fluororesin coating solution 23 and then withdrawn from the coating solution 23. Thereafter, the plurality of rotary polygon mirrors 3 are rotated together with the skewer, so-called pseudo spin coating is applied to the reflection surface 21, and finally baked in an environment of about 170 ° C.

  FIG. 6 is a cross-sectional view showing the configuration of the rotary polygon mirror 3 stacked and skewered. As shown in FIG. 6, a flat flat surface 3 c is formed on the back surface of the reference thick portion 3 a of the rotary polygon mirror 3. The flat surface 3c may be formed at least at the same distance as the distance from the rotation center P of the “rotating part” to the annular convex part 19. Here, the term “flat surface” refers to a surface having a smooth or almost smooth surface regardless of the presence or absence of mirror finish. In the present embodiment, the upper surface 20 of the annular convex portion 19 is a substantially smooth flat surface that is not mirror-finished, and the flat surface 3c formed on the back surface of the reference thick portion 3a is mirror-finished. It is a smooth surface.

  The plurality of rotary polygon mirrors 3 are stacked with the annular convex portion 19 facing upward. Since each rotary polygon mirror 3 has a hole 3b formed in the center, skewers 22 are inserted into the plurality of holes 3b. A predetermined pressure is applied to the plurality of rotary polygon mirrors 3 from one end side and the other end side of the skewer 22, and the region surrounded by the annular convex portion 19 is blocked between the rotary polygon mirrors 3. The

  FIG. 7 is an enlarged cross-sectional view of a portion A in FIG. As shown in FIG. 7, the contact portion 24 between the rotary polygon mirrors 3 stacked during the film formation is similar to the so-called capillary phenomenon even if the liquid surface height and the immersion amount of the coating liquid 23 are sufficiently controlled. The coating liquid 23 may enter. The application state of the application liquid 23 is indicated by a thick line in the figure. Further, the penetration path of the coating liquid 23 is indicated by an arrow B.

  When the plurality of rotary polygon mirrors 3 fixed to the skewer 22 are immersed in the coating liquid 23, the coating liquid 23 that is directed between the rotary polygon mirrors 3 is blocked by the annular convex portion 19. Further, even if the coating liquid 23 tries to enter beyond the annular convex portion 19, the coating liquid 23 stagnates at the crest portion 25 of the annular convex portion 19 due to the surface tension of the coating liquid 23 itself. Therefore, the coating liquid 23 does not reach the annular recess 16. That is, there is no possibility of applying the balance weight 18 on the amorphous fluororesin film that has entered the annular recesses 16 and 15 by mistake. For this reason, the balance weight 18 after UV curing is not peeled off during the rotation of the rotary polygon mirror 3, and the generation of vibration and noise associated with the balance loss of the mass of the “rotor” is suppressed.

Further, the rotary polygon mirror 3 is formed with an outer edge side portion 40 (thin wall portion) which is a “thin wall portion” thinner than the annular convex portion 19 at a position farther from the annular convex portion 19 when viewed from the rotation center P. Is done. That is, the outer edge side portion 40 on the radially outer side of the rotary polygon mirror 3 is formed as a thin portion lower than the upper surface 20 of the annular convex portion 19. Therefore, in comparison with the case of using the rotary polygon mirror of the conventional example (for example, the above-mentioned Patent Documents 1 to 3), the penetration by the liquid splash when the rotary polygon mirror 3 is immersed in the coating liquid 23 is easy. And it is definitely avoided. Accordingly, the yield is improved, and the management item values of the film forming process such as the liquid level of the coating liquid 23 are alleviated, so that the manufacturing cost can be reduced.

  Further, the annular convex portion 19 also contributes to increasing the rigidity of the rotary polygon mirror 3. The reason is considered as follows. When the rotating polygonal mirror having low rigidity is held by the processing machine, the rotating polygonal mirror is deformed (warped). When cutting is performed in a deformed state, even if the reflecting surface is finished with high accuracy, if the holding of the processing machine is released, the deformation of the rotating polygon mirror will return to its original shape, and the flatness of the reflecting surface will be reduced. Getting worse. However, since the rigidity is enhanced when the annular convex portion 19 is formed on the rotary polygon mirror 3 as in this embodiment, the flatness of the reflecting surface 21 due to insufficient rigidity when the reflecting surface 21 is cut. There is no deterioration.

  Furthermore, due to the increased rigidity of the rotary polygon mirror 3 due to the formation of the annular convex portion 19, the flatness of the reflecting surface 21 due to the centrifugal force generated when the rotary polygon mirror 3 rotates at high speed is suppressed. Therefore, the imaging performance and jitter performance on the photosensitive drum 132 in the image forming apparatus 110 are improved, and a high-quality image can be provided.

  Further, the rotary polygon mirror 3 includes an annular convex portion 19 on the side of the rotation center P of the rotation shaft 7 with respect to the reflection surface 21. The outer edge side portion 40 is formed thinner than the upper surface 20 of the annular convex portion 19. Therefore, the inertia is suppressed to be small as compared with a configuration in which the outer edge side portion 40 of the rotary polygon mirror is not formed thin but formed thick (for example, the configuration of Patent Document 2 described above). As a result, the rise time of the “rotor” is shortened, and the starting current and the steady current are reduced. In addition, a high-performance image forming apparatus with low power consumption and short FPOT (First Print Out Time) is provided.

(Second Embodiment)
FIG. 8 is a perspective view of the rotary polygon mirror 30 according to the second embodiment of the present invention. FIG. 9 is a cross-sectional view illustrating a configuration of the rotary polygon mirror 30 that is stacked and skewered. 10 is an enlarged cross-sectional view of a portion C in FIG. The rotating polygon mirror 30 of the second embodiment is different from the rotating polygon mirror 3 of the first embodiment in that the rotating polygon mirror 30 has an annular convex portion 31 formed on the outer peripheral side of the annular concave portion 15 and the annular concave portion 16. The uppermost surface of the annular convex portion 31 is that a concave annular groove 32 is formed in the circumferential direction in a sectional view. The annular groove 32 is formed shallow. In the configuration of the rotary polygon mirror 30 of the second embodiment, the same members as those in the configuration of the rotary polygon mirror 3 of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  As shown in FIG. 9, a plurality of rotary polygon mirrors 30 are stacked, and skewers 22 are inserted into the holes 3b. As in the case of the first embodiment, the rotary polygon mirror 30 applies the coating liquid 23 made of amorphous fluororesin to the reflecting surface. Thereafter, the rotary polygon mirror 30 is fired in an appropriate environment at 170 ° C.

  As shown in FIG. 10, the coating solution 23 enters the annular convex portion 31 with a minute amount by the so-called capillary phenomenon as described above. Therefore, the rotary polygon mirrors 30 after firing are slightly fixed to each other at the annular convex portion 31. The application state of the coating liquid 23 is indicated by a thick line in FIG. The infiltration path of the coating liquid 23 is indicated by an arrow D in FIG.

  According to such a configuration, the same effect as the rotary polygon mirror 3 of the first embodiment can be obtained. In addition, since the annular groove 32 is formed on the upper surface of the annular convex portion 31, the contact area between the adjacent rotary polygon mirrors 30 is made as small as possible, so that the rotary polygon mirror 3 of the first embodiment can be reduced. Compared to the case, the rotary polygon mirrors 30 can be easily detached. That is, it is not necessary to prepare a large tool for removing the rotary polygon mirror 30, and the manufacturing cost and the apparatus cost are reduced. Further, since it is not necessary to remove with a large force, the rotary polygon mirror 30 is not deformed, and there is no possibility that the reflecting surface 34 is damaged. Therefore, a high-quality image having excellent imaging performance and jitter performance is provided.

  In addition, the coating liquid 23 that has entered the contact portion 35 is secured in the annular groove 32 slightly. Therefore, infiltration of the coating liquid 23 into the central portion 36 of the rotary polygon mirror 30, and further to the annular recess 15 and the annular recess 16 is more effectively suppressed than in the case of the rotary polygon mirror 3 of the first embodiment, and the balance weight. A highly reliable optical deflecting device without separation of 17 and 18 is provided.

  According to the rotary polygon mirrors 3 and 30 of the first and second embodiments described above, the annular convex portion 19 is formed at a position farther from the rotational center P than the annular concave portions 15 and 16 on the surface of the reference thick portion 3a. . Therefore, when the rotary polygon mirrors 3 and 30 are immersed in the coating solution 23 after the balance weights 17 and 18 are applied to the annular recesses 15 and 16, the coating solution 23 enters the annular recesses 15 and 16. The annular protrusion 19 can prevent this from happening. In particular, since a flat flat surface 3c is formed on the upper surface 20 of the annular convex portion 19 and the back surface of the reference thick portion 3a, the upper surface 20 of the annular convex portion 19 is obtained when a plurality of rotating polygon mirrors 3 and 30 are stacked. And the flat surface 3c of the back surface of the reference | standard thickness part 3a can contact reliably. The area surrounded by the annular projection 19 is closed. Therefore, the coating liquid 23 is prevented from entering the region surrounded by the annular convex portion 19 between the rotary polygon mirrors 3 and 30. As a result, in the annular recesses 15 and 16, peeling of the balance weights 17 and 18 due to the intrusion of the coating liquid 23 is suppressed. Further, since peeling of the balance weights 17 and 18 is suppressed, the rotary polygon mirrors 3 and 30 are easily processed and formed.

  The annular convex portions 19 and 31 of the adjacent one of the rotary polygon mirrors 3 and 30 are immersed in the coating solution 23 while being in contact with the flat surface 3c on the back surface of the reference thick portion 3a of the other rotary polygon mirror 3 and 30 (lamination). When the film is formed and fired, the bonding portion is limited to the contact portions 24 and 35 of the annular convex portions 19 and 31. As a result, when separating from the skewer 22, the rotary polygon mirrors 3 and 30 are easily separated.

  For these reasons, the image forming apparatus 110 can perform high-quality and high-speed printing, and the rotary polygon mirrors 3 and 30 can be easily processed and formed, thereby reducing the manufacturing cost and the apparatus cost.

  Furthermore, since the annular convex portions 19 and 31 are formed, sufficient rigidity is ensured for the rotary polygon mirrors 3 and 30. As a result, surface deformation during high-speed rotation can be suppressed.

  Since the outer edge side portion 40 having a smaller thickness than the annular projections 19 and 31 is formed at a position farther from the annular projections 19 and 31 when viewed from the rotation center P, the mass of the rotary polygon mirrors 3 and 30 is Reduced. As a result, the centrifugal force is reduced when the rotary polygon mirrors 3 and 30 rotate. At the same time, since the mass is reduced, noise, vibration, steady current, rise time and jitter are reduced when the rotary polygon mirrors 3 and 30 are rotated, and the imaging performance is improved, which is high performance and inexpensive. An optical deflecting device is provided. In particular, the rise time of the device is minimized by the shape that results in the minimum inertia.

  Since the upper surfaces 20 and 31a of the annular convex portions 19 and 31 are the highest on the surfaces of the rotary polygon mirrors 3 and 30, when the plurality of rotary polygon mirrors 3 and 30 are stacked, the annular convex portion 19 is not stacked. It is possible to reliably contact the flat surface 3c on the back surface of the other rotary polygon mirrors 3 and 30 that are rarely adjacent to each other. The upper surface 31a is shown in FIG.

  In the rotary polygon mirror 30 of the second embodiment described above, a concave annular groove 32 in the circumferential direction is formed in the circumferential direction on the upper surface 31a which is the uppermost surface of the annular convex portion 31. Therefore, when the plurality of rotary polygon mirrors 30 are removed after being stacked and immersed in the coating solution 23, the contact area of the contact portion 35 between the rotary polygon mirrors 30 is narrowed. It is done. As a result, the rotary polygon mirrors 30 are easily peeled off. Further, as shown in FIG. 10, the contact portion 35 is divided into two forks in a cross-sectional view. Therefore, if the contact portion 35 having the same width is provided, the intrusion of the coating liquid 23 is more effective when the annular protrusion 31 is formed wider and the annular groove 32 is provided on the upper surface of the annular protrusion 31. It is suppressed.

  In addition, this invention is not limited to the structure of the above-mentioned 1st Embodiment and 2nd Embodiment, The number and shape of the annular recessed parts 15 and 16 are not ask | required. The shape of the annular groove 32 may be any shape and may not be annular. The number and shape of the annular protrusions 19 and 31 are not limited as long as they are outside the annular recess 16. Needless to say, any number of reflecting surfaces 21 and 34 may be used.

It is sectional drawing which shows the structure of an image forming apparatus provided with an optical scanning device. It is a perspective view which shows the structure of an optical scanning device. It is sectional drawing of an optical deflection apparatus provided with the rotary polygon mirror which concerns on 1st Embodiment of this invention. It is a perspective view of a rotary polygon mirror. It is a figure explaining the rotary wet film-forming method of a rotary polygon mirror. It is sectional drawing at the time of stacking | stacking a rotation polygon mirror. It is an expanded sectional view of the A section of FIG. It is a perspective view of the rotary polygon mirror which concerns on 2nd Embodiment of this invention. It is sectional drawing at the time of stacking | stacking a rotation polygon mirror. It is an expanded sectional view of the C section of FIG.

Explanation of symbols

2 ... Light beam 3, 30 ... Rotating polygon mirror (rotating body)
3a ··· Reference thickness part 4 ··· Flange (rotating member) (rotating body)
5 ... Spring (Rotating member) (Rotating body)
6 ... Screw (Rotating member) (Rotating body)
8 ... Rotor frame (rotating member) (rotating body)
9... Driving coil 10... Stator 15 and 16. Annular recesses 17 and 18. Balance weights 19 and 31. Annular projections 20 and 31 a... Upper surface 32. .... Outer peripheral part

Claims (8)

A main body having a plurality of reflecting surfaces formed at a radial end portion of the rotation shaft, the main body including a recess recessed in the rotation shaft direction to which a balance weight is applied, and rotating to rotate the plurality of the plurality of reflection surfaces. a rotating polygon mirror for deflecting and scanning the light beam by the reflecting surface, in the rotary polygon mirror fluororesin is applied to the plurality of reflection surfaces by rotating a wet method,
The main body is
Before Ki凹 portion inner than the plurality of reflecting surfaces on the outside than the projecting upper surface to the rotation axis direction flat annular protrusion with respect to the radial direction of said rotary shaft,
A flat surface made form at a position corresponding to the annular protrusion of the back side of the annular convex portion of the main body portion,
Formed on the outer side of the annular projection with respect to the radial direction of the rotation axis, and a thin wall portion whose thickness in the rotation axis direction is thinner than the annular projection;
A rotating polygonal mirror characterized by comprising: The rotary polygon mirror according to claim 1, wherein the annular convex portion and the concave portion are formed at positions separated from each other with respect to a radial direction of the rotating shaft. The rotary polygon mirror according to claim 1, wherein the concave portion is formed in an annular shape around the rotation axis. On the upper surface of the annular projection, any of claims 1 to 3 annular groove around the rotary shaft I concave in the axial direction than the flat portion, characterized in Tei Rukoto made form the rotary polygon mirror according to an item or. The said fluororesin is apply | coated to the said reflective surface by the said rotary wet method in the state which accumulated the said main-body part in the said rotating shaft direction. Rotating polygon mirror. 6. An optical deflection apparatus comprising: the rotary polygon mirror according to claim 1; and a driving unit that rotates the rotary polygon mirror. An image is formed on a transfer material by forming a latent image by irradiating the photosensitive member with a light beam deflected and scanned by the optical deflection device. An image forming apparatus. A main body portion having a plurality of reflecting surfaces formed at radial ends of the rotating shaft, the main body portion including a concave portion recessed in the rotating shaft direction, and rotating to transmit a light beam on the plurality of reflecting surfaces. In a method of manufacturing a rotary polygon mirror that performs deflection scanning,
The main body includes an annular protrusion that protrudes in the direction of the rotation axis and has a flat upper surface and protrudes inward of the plurality of reflecting surfaces outside the recess with respect to the radial direction of the rotation axis, and the annular protrusion of the main body. A flat surface formed at a position corresponding to the annular convex part on the back side of the part, and formed on the outer side of the annular convex part with respect to the radial direction of the rotary shaft, and the thickness in the rotational axis direction is the annular convex part And a thinner thin part,
A method of manufacturing a rotary polygon mirror, wherein a fluororesin is applied to the plurality of reflective surfaces by a rotary wet method in a state where the main body portion is overlapped in the rotation axis direction, and then a balance weight is applied to the concave portion. .