JP2015138225A - Optical scanning device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure rigidity necessary for an optical scanning device and furthermore to facilitate removal of a foreign matter from inside the optical scanning device.SOLUTION: An optical scanning device 40 includes; light sources 44 for emitting light beams L; a rotary polygon mirror 46 for deflecting the light beams such that photoreceptors 50 are scanned with the light beams from the light sources; a plurality of optical components 47, 48 for guiding the light beams to the photoreceptors; a housing 41 for holding the light sources, the rotary polygon mirror, and the plurality of optical components; a plurality of arranging surfaces 82, located inside the housing, for supporting the plurality of optical components. The plurality of arranging surfaces extend in longitudinal directions of the plurality of optical components and are tilted relative to a rotation axis X of the rotary polygon mirror, and adjacent arranging surfaces out of the plurality of arranging surfaces are tilted at angles different from each other.

Description

  The present invention relates to an optical scanning device that scans a photosensitive member with a light beam, and an image forming apparatus having the optical scanning device.

  Conventionally, an image forming apparatus using an electrophotographic system has an optical scanning device that scans a photosensitive member with a light beam. The optical scanning device emits a light beam, scans the surface of the rotating photoconductor with the light beam, and forms an electrostatic latent image on the photoconductor. The developing device develops the electrostatic latent image with a developer (toner) to form a toner image. The transfer device transfers the toner image to a recording medium. The fixing device heats and pressurizes the toner image to fix the toner image on the recording medium, and forms an image on the recording medium.

  The amount of light beam emitted from the optical scanning device is controlled according to the image density. When the amount of light fluctuates unintentionally, there arises a problem that the density of the image formed on the recording medium is “light” or “dark”. The fluctuation of the light amount of the light beam is caused by dust or fluff adhering to the optical components in the optical scanning device. If dust or fluff adheres to the optical component when assembling the optical component in the optical scanning device, the dust or flare blocks the light beam, so that the light amount of the light beam decreases and the image density varies.

  2. Description of the Related Art Conventionally, in order to prevent dust or chips from remaining in an optical scanning device, after assembling optical components in a housing of the optical scanning device, air or dust is blown onto the housing to remove dust or chips. After the air is blown (hereinafter referred to as “air blow”), a cover is attached to the housing to prevent dust or debris from entering the optical scanning device.

  However, a wall or a narrow gap may be provided inside the housing of the optical scanning device. The wall becomes an obstacle to the air flow caused by the air blow. In addition, dust or markings in a narrow gap may not be removed by air blow.

  In order to solve such a problem, it is conceivable that the bottom portion (hereinafter referred to as a base portion) of a housing to which an optical component is attached is constituted by a flat surface that does not have a wall or a narrow gap that obstructs air blow. . However, if the base of the housing is a flat plate, membrane vibration occurs in the base. The film vibration of the base vibrates the optical component and changes the irradiation position of the light beam irradiated onto the photosensitive member. Variation in the irradiation position of the light beam causes a striped image defect called pitch unevenness.

  In order to suppress film vibration of the base, there is an optical scanning device having a base in which a plurality of ribs are connected in a lattice shape. Patent Document 1 proposes an optical scanning device in which a positioning portion for positioning an optical component and a fixing portion for fixing the optical component are provided on a lattice-shaped base.

JP-A-10-2137770

  In order to increase the rigidity of the base to which the optical component is fixed, when the base is formed by a plurality of ribs connected in a lattice shape, a plurality of spaces surrounded by the plurality of ribs are formed inside the housing. In each of the plurality of spaces, a corner is formed at the boundary between the base of the housing and the rib, and at the boundary between the rib and the rib. Even if air is blown vigorously on the housing in order to remove foreign matter adhering to the optical component, foreign matter tends to remain in many corners. If an image is formed with foreign matter remaining in the optical scanning device, the foreign matter drifts into the optical scanning device and blocks the light beam, resulting in an image defect.

  SUMMARY An advantage of some aspects of the invention is that it provides an optical scanning device that easily removes foreign matters while ensuring rigidity necessary for the optical scanning device.

In order to solve the above problems, an optical scanning device according to the present invention provides:
A light source that emits a light beam;
A rotating polygon mirror that deflects the light beam so that the light beam emitted from the light source scans a photoreceptor;
A plurality of optical components for guiding the light beam to the photoreceptor;
A housing for holding the light source, the rotary polygon mirror, and the plurality of optical components;
A plurality of arrangement surfaces provided on the housing and supporting the plurality of optical components;
With
The plurality of arrangement surfaces extend in a longitudinal direction of the plurality of optical components,
The plurality of arrangement surfaces are inclined with respect to the rotation axis of the rotary polygon mirror,
Adjacent placement surfaces of the plurality of placement surfaces are inclined at different angles.

  According to the invention, it is possible to easily remove foreign matters while ensuring the rigidity necessary for the optical scanning device.

1 is a perspective view of an optical scanning device according to a first embodiment. The perspective view of the optical scanning device which removed the cover. Sectional drawing of an optical scanning device. The fragmentary sectional view of the housing | casing by a 1st Example. The figure which shows the analysis model for analyzing the flow velocity in the housing | casing at the time of an air blow. The figure which shows the relationship between the inclination angle of a rib, and the flow velocity in a corner. The figure which shows the analysis model for analyzing the rigidity of a housing | casing. The figure which shows the relationship between the subordinate angle of an adjacent arrangement surface, and the natural frequency of the membrane vibration of a base. The figure which shows the analysis model for analyzing the flow velocity in the housing | casing at the time of an air blow. Sectional drawing of the housing | casing for demonstrating the air blow method. The fragmentary sectional view of the housing | casing by a 2nd Example. The fragmentary sectional view of the housing | casing by a 3rd Example. The fragmentary sectional view of the housing | casing by a 4th Example. The fragmentary sectional view of the housing | casing by the 5th Example. The fragmentary sectional view of the housing | casing by a 6th Example. 1 is a cross-sectional view of an image forming apparatus according to a first embodiment.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

(Image forming device)
Hereinafter, an image forming apparatus 100 according to the present invention will be described with reference to the accompanying drawings.
FIG. 16 is a cross-sectional view of the image forming apparatus 100 according to the first embodiment. The image forming apparatus 100 according to the present embodiment is a tandem type color laser printer.

  The image forming apparatus 100 includes four image forming units 10 (10Y, 10M, 10C, and 10Bk), and forms a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image, respectively. An intermediate transfer belt (intermediate transfer member) 20 is disposed on the image forming unit 10. The intermediate transfer belt 20 is an endless belt that is wound around a pair of belt conveyance rollers 21 and 22. The intermediate transfer belt 20 rotates in a direction indicated by an arrow H (hereinafter referred to as a rotation direction H).

  The four image forming units 10 are arranged below the intermediate transfer belt 20 in the order of yellow, magenta, cyan, and black along the rotation direction H. The four image forming units 10 each have a rotating electrophotographic photosensitive drum (hereinafter referred to as a photosensitive member) 50 (50Y, 50M, 50C, 50Bk) as an image carrier. Each of the image forming apparatuses 10 includes a charging roller 12, a developing device 13, a primary transfer roller 15, and a cleaning device 14 disposed around the photoconductor 50. The optical scanning device 40 is disposed below the image forming unit 10.

  The charging roller 12 (12Y, 12M, 12C, 12Bk) uniformly charges the surface of the photoreceptor 50 (50Y, 50M, 50C, 50Bk). The optical scanning device 40 exposes the surface of the uniformly charged photoreceptor 50 with laser light (hereinafter referred to as a light beam) L (LY, LM, LC, LBk) modulated according to image information of each color. Thus, an electrostatic latent image is formed. The developing units 13 (13Y, 13M, 13C, 13Bk) develop the electrostatic latent image on the photoconductor 50 with the respective color toners to form the respective color toner images. The developing device 13 uses a two-component developer in which a toner and a carrier are mixed.

  The primary transfer rollers 15 (15Y, 15M, 15C, and 15Bk) are disposed to face the photoconductor 50 with the intermediate transfer belt 20 interposed therebetween, and the primary transfer portion PT ( PTY, PTM, PTC, PTBk) are formed. By applying a predetermined transfer bias voltage to the primary transfer roller 15, a transfer electric field is formed between the photoconductor 50 and the transfer roller 15.

The four color toner images on the four photoconductors 50 are sequentially primary-transferred and superimposed on the intermediate transfer belt 20 that rotates in the rotation direction H at each primary transfer portion PT.
The toner remaining on the photoreceptor 50 after the primary transfer is removed by the cleaning device 14 (14Y, 14M, 14C, 14Bk).

  The secondary transfer roller 60 is disposed so as to face the one belt conveying roller 21 with the intermediate transfer belt 20 interposed therebetween. A secondary transfer portion ST is formed between the intermediate transfer belt 20 and the secondary transfer roller 60.

  The recording medium P is stored in a paper feed cassette 2 mounted on the lower part of the main body 1 of the image forming apparatus 100. The paper feed cassette 2 is detachably mounted from the side surface of the main body 1 to the lower portion of the main body 1. A pickup roller 24 and a paper feed roller 25 are arranged in parallel on the upper side of the paper feed cassette 2. A retard roller 26 that prevents double feeding of the recording medium P is disposed to face the paper feed roller 25. The pickup roller 24 pulls out the recording medium P stored in the paper feed cassette 2. The paper feed roller 25 and the retard roller 26 separate the recording medium P and feed them one by one.

  The conveyance path 27 of the recording medium P inside the main body 1 of the image forming apparatus 100 is provided substantially vertically along the right side surface of the main body 1. The recording medium P fed by the paper feed roller 25 is conveyed to the registration roller 29 along the sheet conveyance path 27. The registration roller 29 corrects the skew of the recording medium P and controls the timing of conveying the recording medium P to the secondary transfer unit ST.

  The secondary transfer roller 60 collectively transfers the toner images superimposed on the intermediate transfer belt 20 onto the recording medium P at the secondary transfer unit ST. The recording medium P to which the toner image has been transferred is conveyed to the fixing device 3 provided above the secondary transfer portion ST. The fixing device 3 fixes the toner image on the recording medium P by heat and pressure, and forms an image on the recording medium P. The recording medium P on which the image is formed is discharged by a discharge roller 28 to a paper discharge tray 1a provided at the top of the main body 1.

In order to form a high-quality image on the recording medium P, it is preferable to reproduce the position of the electrostatic latent image formed on the photoconductor 50 by the optical scanning device 40 with high accuracy. Further, it is preferable that the light amount of the light beam for forming the electrostatic latent image is constantly controlled to a desired value.
Hereinafter, the optical scanning device 40 will be described.

(Optical scanning device)
FIG. 1 is a perspective view of an optical scanning device 40 according to the first embodiment. FIG. 2 is a perspective view of the optical scanning device 40 with the cover 42 removed. FIG. 3 is a cross-sectional view of the optical scanning device 40.

  The optical scanning device 40 is shared by all the image forming units 10. The optical scanning device 40 emits four light beams LY, LM, LC, and LBk to the respective photoreceptors 50Y, 50M, 50C, and 50Bk of the four image forming units 10Y, 10M, 10C, and 10Bk. The optical scanning device 40 includes an optical box (hereinafter referred to as a casing) 41, a cover 42, four semiconductor lasers (hereinafter referred to as light sources) 44, an anamocollimator lens (not shown), a rotary polygon mirror 46, a motor 46a, An imaging lens 47 and a mirror 48 are provided.

  The housing 41 accommodates a plurality of imaging lenses 47 and a plurality of mirrors 48 as optical components that guide the plurality of light beams L to the plurality of photoreceptors 50. The cover 42 is disposed so as to cover the housing 41. The housing 41 is sealed with a cover 42 and a dustproof glass 43. The cover 42 is provided with a plurality of openings through which the plurality of light beams L pass. The plurality of openings are closed by a plurality of dustproof glasses 43 (43Y, 43M, 43C, 43Bk).

  The light source 44 and the anamocollimator lens are held by two laser holders (light source holding members) 45 (45R, 45L). The laser holder 45 is attached to the side wall of the housing 41. The laser holder 45L holds the light sources 44Y and 44M side by side. The laser holder 45L holds one anamorphic collimator lens for a set of light sources 44Y and 44M. Similarly, the laser holder 45R holds the light sources 44C and 44Bk arranged vertically. The laser holder 45R holds one anamorphic collimator lens for a set of light sources 44C and 44Bk. The light sources 44Y and 44M and the light sources 44Bk and 44C are arranged symmetrically with respect to the rotation axis X of the rotary polygon mirror 46. The light sources 44Y and 44Bk and the light sources 44M and 44C are arranged symmetrically with respect to a line perpendicular to the rotation axis X.

  The four light sources 44 (44Y, 44M, 44C, 44Bk) emit light beams L (LY, LM, LC, LBk) modulated according to the image information of the respective colors. The anamocollimator lens converts the light beam L emitted from the light source 44 into parallel light, and collects the parallel light linearly on the reflecting surface of the rotary polygon mirror 46. The rotary polygon mirror 46 is rotated by a motor 46a. The rotating polygon mirror (deflector) 46 deflects the light beam L in order to scan the photosensitive member 50 with the light beam L in the axial direction (main scanning direction) of the photosensitive member 50.

  The light beam L deflected by the rotary polygon mirror 46 is guided along respective predetermined paths by an imaging lens 47 and a mirror 48 as optical components provided in the optical scanning device 40. The light beam L exposes the photoconductor 50 of the image forming unit 10 through a dustproof glass 43 disposed in an opening provided in the upper part of the optical scanning device 40. The imaging lens 47 is designed to focus the light beam L to form a light spot on the photoconductor 50 and scan the light spot at a constant speed. The light beam L that has passed through the imaging lens 47 is guided to the photoreceptor 50 by the mirror 48 and scans on the photoreceptor 50, whereby an electrostatic latent image is formed on the surface of the photoreceptor 50.

  The imaging lens 47 as an optical component is arranged on the right side of the rotation axis X with the first imaging lens 47aL and the second imaging lens 47bL arranged on the left side of the rotation axis X of the rotary polygon mirror 46 in FIG. A first imaging lens 47aR and a second imaging lens 47bR. The mirror 48 as an optical component includes a yellow mirror 48Y, a magenta first mirror 48M1, a second mirror 48M2, a third mirror 48M3, a cyan first mirror 48C1, a second mirror 48C2, a third mirror 48C3, And a mirror 48Bk for black.

  The light beam LY emitted from the yellow light source 44Y passes through the anamorphic collimator lens and is deflected by the reflecting surface of the rotary polygon mirror 46. The light beam LY passes through the first imaging lens 47aL and the second imaging lens 47bL, is reflected by the mirror 48Y, passes through the dust-proof glass 43Y, and exposes the yellow photoreceptor 50Y.

  The light beam LM emitted from the magenta light source 44M passes through the anamorphic collimator lens and is deflected by the reflecting surface of the rotary polygon mirror 46. The light beam LM passes through the first imaging lens 47aL and the second imaging lens 47bL, is reflected by the first mirror 48M1, the second mirror 48M2, and the third mirror 48M3, and passes through the dust-proof glass 43M. The magenta photoreceptor 50M is exposed.

  The light beam LC emitted from the cyan light source 44 </ b> C passes through the anamorphic collimator lens and is deflected by the reflecting surface of the rotary polygon mirror 46. The light beam LC passes through the first imaging lens 47aR and the second imaging lens 47bR, is reflected by the first mirror 48C1, the second mirror 48C2, and the third mirror 48C3, and passes through the dust-proof glass 43C. The cyan photoreceptor 50C is exposed.

  The light beam LBk emitted from the black light source 44Bk passes through the anamorphic collimator lens and is deflected by the reflecting surface of the rotary polygon mirror 46. The light beam LBk passes through the first imaging lens 47aR and the second imaging lens 47bR, is reflected by the mirror 48Bk, passes through the dust-proof glass 43Bk, and exposes the black photoreceptor 50Bk.

(Casing)
As shown in FIG. 3, the housing 41 has a side wall 80 and a bottom (hereinafter referred to as a base) 81. FIG. 4 is a partial cross-sectional view of the housing 41 according to the first embodiment. FIG. 4 shows the base 81 to which the mirror 48Y and the mirror 48M1 are attached. The base 81 has a plurality of arrangement surfaces 82 on which a plurality of optical components (48, 47) are arranged. Each of the plurality of arrangement surfaces 82 is provided with a pair of support portions 83 that support both ends of the corresponding optical component (48, 47) among the plurality of optical components (48, 47).

  The base 81 is provided with an arrangement surface 82Y (82Y1, 82Y2) to which the mirror 48Y is attached. The mirror 48Y is arranged along the arrangement surface 82Y1. The arrangement surface 82Y1 faces the back surface 48Yb opposite to the reflection surface 48Ya of the mirror 48Y. The arrangement surface 82Y1 is a plane that continuously extends in the longitudinal direction of the mirror 48Y. The arrangement surface 82Y1 is provided with a pair of support portions 83Y1 that support both ends of the mirror 48Y. The pair of support portions 83Y1 contacts the back surface 48Yb of the mirror 48Y to position the mirror 48Y. A gap is formed between the arrangement surface 82Y1 and the mirror 48Y.

  The mirror 48Y is arranged along the arrangement surface 82Y2. The arrangement surface 82Y2 faces the side surface 48Yc of the mirror 48Y. The arrangement surface 82Y2 is a plane that continuously extends in the longitudinal direction of the mirror 48Y. The arrangement surface 82Y2 is provided with a pair of support portions 83Y2 that support both ends of the mirror 48Y. The pair of support portions 83Y2 contacts the side surface 48Yc of the mirror 48Y to position the mirror 48Y. A gap is formed between the arrangement surface 82Y2 and the mirror 48Y.

  The base 81 is provided with an arrangement surface 82M (82M1, 82M2) to which the first mirror 48M1 is attached. The first mirror 48M1 is arranged along the arrangement surface 82M1. The arrangement surface 82M1 faces the back surface 48M1b opposite to the reflection surface 48M1a of the first mirror 48M1. The arrangement surface 82M1 is a plane that continuously extends in the longitudinal direction of the mirror 48M1. The arrangement surface 82M1 is provided with a pair of support portions 83M1 that support both ends of the mirror 48M1. The pair of support portions 83M1 contacts the back surface 48M1b of the first mirror 48M1 to position the first mirror 48M1. A gap is formed between the arrangement surface 82M1 and the first mirror 48M1.

  The first mirror 48M1 is arranged along the arrangement surface 82M2. The arrangement surface 82M2 faces the side surface 48M1c of the first mirror 48M1. The arrangement surface 82M2 is a plane that extends continuously in the longitudinal direction of the first mirror 48M1. The arrangement surface 82M2 is provided with a pair of support portions 83M2 that support both end portions of the first mirror 48M1. The pair of support portions 83M2 contacts the side surface 48M1c of the first mirror 48M1 to position the first mirror 48M1. A gap is formed between the arrangement surface 82M2 and the first mirror 48M1.

The arrangement surfaces 82Y and 82M of the adjacent mirrors 48Y and 48M1 are arranged in parallel to each other.
The base 81 has a planar connection portion 84 that connects the arrangement surface 82Y2 and the arrangement surface 82M1 of the adjacent mirror 48Y and the first mirror 48M1. The connecting portion 84 extends continuously in the longitudinal direction of the arrangement surface 82Y2 and the arrangement surface 82M1.

<Inclination angle of placement surface>
The arrangement surfaces 82Y1, 82Y2, 82M1, and 82M2 are arranged so that the foreign surfaces (dust or debris) are effectively removed by air blowing from the direction Z parallel to the rotational axis X of the rotary polygon mirror 46. Leaning against. The inclination angles αY1, αY2, αM1, and αM2 of the arrangement surfaces 82Y1, 82Y2, 82M1, and 82M2 with respect to the plane S perpendicular to the rotation axis X of the rotary polygon mirror 46 are preferably greater than 0 ° and not greater than 66 °. The reason is obtained from the analysis results described below.

  FIG. 5 is a diagram showing an analysis model 70 for analyzing the flow velocity in the housing 41 during air blowing. FIG. 5A is a diagram showing an analysis model 70 (hereinafter referred to as a box 70) of the casing 41. FIG. The box 70 has a base portion 70a and a rib 73 surrounding the base portion 70a.

  A steady wind with a flow velocity of 10 m / sec was flowed from the direction Z parallel to the rotation axis X of the rotary polygon mirror 46 to the entire surface of the base portion 70a of the box 70 to analyze the air flow. FIG.5 (b) is a contour figure which shows an analysis result. As shown in FIG. 5 (b), the air flow follows the flow path indicated by the arrow 72. The air flow from above the box 70 collides with the base 70 a of the box 70. The collided air flows along the base 70 a of the box 70. The air collides with the rib 73, flows along the rib 73, and goes out of the box 70.

  The surface of the rib 73 corresponds to the arrangement surface 82Y1 and the arrangement surface 82M1. The base 70 a corresponds to a plane S perpendicular to the rotation axis X of the rotary polygon mirror 46. The surface of the rib 73 is inclined at an inclination angle α with respect to the base portion 70a. That is, the inclination angle α corresponds to the inclination angles αY1, αY2, αM1, and αM2 of the arrangement surfaces 82Y1, 82Y2, 82M1, and 82M2 with respect to the plane S perpendicular to the rotation axis X of the rotary polygon mirror 46.

  The air flow velocity in the vicinity of the corner 71 (FIG. 5B) between the base 70a and the rib 73 was measured by changing the inclination angle α of the rib 73 with respect to the base 70a. FIG. 6 is a diagram showing the relationship between the inclination angle α of the rib 73 and the flow velocity at the corner 71. In FIG. 6, the horizontal axis indicates the inclination angle α of the rib 73, and the vertical axis indicates the air flow velocity in the vicinity of the corner 71. The gradient of the flow velocity with respect to the inclination angle α changes significantly when the inclination angle α is 66 °. That is, when the inclination angle α of the rib 73 is 66 ° or less, the flow velocity of air at the corner 71 is large. Therefore, when the inclination angle α of the rib 73 is 66 ° or less, the air flow also spreads to the corner portion 71, and foreign matters can be efficiently removed.

  Therefore, it is desirable that the inclination angles αY1, αY2, αM1, and αM2 of the arrangement surfaces 82Y1, 82Y2, 82M1, and 82M2 with respect to the plane S perpendicular to the rotation axis X of the rotary polygon mirror 46 be greater than 0 ° and not greater than 66 °. .

  In the present embodiment, the connecting portion 84 that connects the adjacent placement surface 82Y2 and the placement surface 82M1 is parallel to the plane S perpendicular to the rotation axis X of the rotary polygon mirror 46. However, the connection part 84 may have an inclined surface. Similarly to the arrangement surface, the inclined surface of the connecting portion 84 desirably has an inclination angle with respect to the plane S perpendicular to the rotation axis X of the rotary polygon mirror 46 greater than 0 ° and less than 66 °.

<An angle formed by adjacent arrangement surfaces>
As shown in FIG. 4, the arrangement surface 82Y2 and the arrangement surface 82M1 of the adjacent mirrors 48Y and 48M1 are inclined at different angles. In order to ensure the necessary rigidity for the casing 41, the minor angle θ among the angles formed by the arrangement surfaces 82Y2 and 82M1 of the adjacent mirrors 48Y and 48M1 is preferably greater than 0 ° and not more than 126 °. The reason is obtained from the analysis results described below.

  FIG. 7 is a diagram showing an analysis model 170 for analyzing the rigidity of the housing 41. FIG. 7A is a diagram showing an analysis model 170 (hereinafter referred to as a box 170) of the housing 41. FIG. The box 170 includes a base 171, a side wall 173 that surrounds the base 171, and a protrusion 174 provided on the base 171. FIG. 7B is a schematic cross-sectional view of the box 170 taken along line VIIB-VIIB in FIG. The protrusion 174 is provided at the center of the box 170. The protruding portion 174 has arrangement surfaces 172 on both sides.

  Adjacent placement surfaces 172 of the protrusions 174 correspond to the placement surfaces 82Y2 and 82M1 of the adjacent mirrors 48Y and 48M1, respectively. The inferior angle θ formed by the adjacent arrangement surfaces 172 corresponds to the inferior angle θ formed by the arrangement surface 82Y2 and the arrangement surface 82M1.

  The vibration analysis of the box 170 was performed. The natural frequency of the membrane vibration of the base portion 171 was measured by changing the minor angle θ formed by the adjacent arrangement surfaces 172 of the protrusions 174. FIG. 8 is a diagram showing the relationship between the recessive angle θ of the adjacent arrangement surface 172 and the natural frequency of the membrane vibration of the base 171. In FIG. 8, the horizontal axis indicates an inferior angle θ formed by adjacent arrangement surfaces 172, and the vertical axis indicates the natural frequency of the membrane vibration of the base 171. The inclination of the natural frequency with respect to the minor angle θ changes significantly when the degree of inferior θ is 126 °. Specifically, the natural frequency is large when the recess angle θ is 126 ° or less. When the minor angle θ is greater than 126 °, the natural frequency is significantly reduced. Therefore, the rigidity of the box 170 can be ensured when the minor angle θ formed by the adjacent arrangement surfaces 172 is 126 ° or less.

  Therefore, in order to ensure the necessary rigidity for the casing 41, the minor angle θ formed by the arrangement surface 82Y2 and the arrangement surface 82M1 of the adjacent mirrors 48Y and 48M1 is preferably greater than 0 ° and 126 ° or less.

<Relationship between distance from rotating polygon mirror and distance from photoconductor>
In the present embodiment, the mirror 48 (48Y, 48M1, 48C1, 48Bk) installed on the arrangement surface 82 (82Y, 82M, 82C, 82Bk) is the photosensitive member 50 (50Y, 50M) as the distance from the rotary polygon mirror 46 increases. , 50C, 50Bk). The greater the distance from the rotary polygon mirror 46 to the placement surface 82, the smaller the distance from the photoreceptor 50 to the placement surface 82. Specifically, in the arrangement surface 82Y where the distance to the rotary polygon mirror 46 is larger than the arrangement surface 82M, the distance to the photoconductor 50Y is smaller than the distance between the arrangement surface 82M and the photoconductor 50M.

  With this configuration, when air is blown inside the housing 41, the arrangement surface 82 does not become a barrier against the air flow, so that foreign matters can be efficiently removed. The reason is obtained from the analysis results described below.

  FIG. 9 is a diagram illustrating an analysis model for analyzing the flow velocity in the housing during air blowing. FIG. 9 is farther from the analysis model 270 (FIG. 9A) of the housing 41 when the distance from the mirror 48 to the photosensitive member 50 is closer as the position of the mirror 48 is farther from the rotary polygon mirror 46. This is a comparison with the analysis model 370 (FIG. 9B).

  FIG. 9A is a diagram showing an analysis model 270 (hereinafter referred to as a box 270) of the housing 41. FIG. The box 270 includes a base 271, a side wall 272 surrounding the base 271, and arrangement surfaces 273 and 274 provided on the base 271. The placement surfaces 273 and 274 correspond to the placement surfaces 82Y and 82M of the housing 41. The arrangement surface 273 is farther from the rotary polygon mirror 46 than the arrangement surface 274, but the distance to the photoconductor 50Y is shorter than the distance between the arrangement surface 274 and the photoconductor 50M.

  A steady wind with a flow velocity of 10 m / sec was flowed from the direction Z parallel to the rotation axis X of the rotary polygon mirror 46 to the entire surface of the base 271 of the box 270 to analyze the air flow. FIG. 9C is a contour diagram showing the analysis results. As shown in FIG. 9C, the air flow follows the flow path indicated by the arrow 90. The air flow from above the box 270 collides with the base 271. The collided air flows along the base 271. The air flows along the placement surface 274, further flows along the placement surface 273, and exits the box 270.

  FIG. 9B is a diagram showing an analysis model 370 (hereinafter referred to as a box 370) of the housing 41. The box 370 includes a base 371, a side wall 372 that surrounds the base 371, and arrangement surfaces 373 and 374 provided on the base 371. The arrangement surface 373 is farther from the rotary polygon mirror 46 than the arrangement surface 374, and the distance to the photoconductor 50Y is longer than the distance between the arrangement surface 374 and the photoconductor 50M.

  A steady air flow of 10 m / sec was flowed from the direction Z parallel to the rotation axis X of the rotary polygon mirror 46 to the entire surface of the base 371 of the box 370 to analyze the air flow. FIG. 9D is a contour diagram showing the analysis results. As shown in FIG. 9D, the air flow follows the first flow path indicated by the arrow 91a and the second flow path indicated by the arrow 91b. The air flow that follows the first flow path 91 a collides with the base 371 from above the box 370. The collided air flows along the base 371, collides with the arrangement surface 374, and moves upward. The air flow that follows the second flow path 91 b collides with the base 371 from above the box 370. The collided air flows along the base 371, collides with the arrangement surface 373, travels upward, and exits the box 370. As described above, when the distance of the mirror 48 becomes farther from the rotary polygon mirror 46 and the distance to the photoconductor 50 becomes shorter (FIG. 9A), one channel 90 is held (FIG. 9C). )), When it is far away (FIG. 9B), it has two channels 91a and 91b (FIG. 9D). A large number of flow paths with respect to a flow from one direction means that there is an obstacle to the flow. Therefore, as the position of the mirror 48 is further away from the rotary polygon mirror 46, when the distance from the mirror 48 to the photoconductor 50 is closer, the foreign matter inside the housing 41 is more effectively removed by air blow than when the distance is longer. Can be removed efficiently.

  Therefore, the arrangement surface 82 that supports the mirror 48 is arranged such that the distance to the photoconductor 50 becomes shorter as the distance from the rotary polygon mirror 46 increases.

<Air blow>
In the present embodiment, air blowing is performed on the entire surface of the base portion 81 of the housing 41. However, an air blow may be applied to a part of the housing 41. FIG. 10 is a cross-sectional view of the housing 41 for explaining the air blowing method. FIG. 10A is a diagram showing a state where an air blow is applied to a part of the housing 41. 10B, the air blow may be applied to the base 81 while the air blow is moved in the direction indicated by the arrow 74 along the base 81 of the housing 41. In both cases shown in FIG. 10A and FIG. 10B, the same effects as in the present embodiment are obtained.

  The second embodiment will be described below with reference to FIG. In the second embodiment, the configurations of the image forming apparatus and the optical scanning apparatus are the same as those in the first embodiment, and thus description thereof is omitted. Hereinafter, the housing 241 according to the second embodiment will be described.

  FIG. 11 is a partial cross-sectional view of the housing 241 according to the second embodiment. In the second embodiment, the same components as those of the casing 41 according to the first embodiment shown in FIG. As shown in FIG. 11, the adjacent placement surface 82Y2 and the placement surface 82M1 are connected by a connecting portion 284. The connection part 284 has a ridgeline. The connecting portion 284 extends continuously in the longitudinal direction of the arrangement surface 82Y2 and the arrangement surface 82M1.

  Also in the second embodiment, as in the first embodiment, there is an effect that it is easy to remove foreign matter in the housing 241 by air blowing.

  The third embodiment will be described below with reference to FIG. In the third embodiment, the configurations of the image forming apparatus and the optical scanning apparatus are the same as those in the first embodiment, and thus description thereof is omitted. Hereinafter, the housing 341 according to the third embodiment will be described.

  FIG. 12 is a partial cross-sectional view of the housing 341 according to the third embodiment. In the third embodiment, the same components as those of the housing 41 according to the first embodiment shown in FIG. As shown in FIG. 12, the adjacent placement surface 82Y2 and the placement surface 82M1 are connected by a connecting portion 384. The connection part 384 has a curved surface. The angle of the tangent of the curved surface with respect to the plane S perpendicular to the rotation axis X of the rotary polygon mirror 46 is preferably 0 ° or greater and 66 ° or less. The connecting portion 384 extends continuously in the longitudinal direction of the placement surface 82Y2 and the placement surface 82M1.

  Also in the third embodiment, as in the first embodiment, there is an effect that it is easy to remove foreign matter in the housing 341 by air blowing.

  The fourth embodiment will be described below with reference to FIG. In the fourth embodiment, the configurations of the image forming apparatus and the optical scanning apparatus are the same as those in the first embodiment, and thus description thereof is omitted. Hereinafter, the housing 441 according to the fourth embodiment will be described.

  FIG. 13 is a partial cross-sectional view of the housing 441 according to the fourth embodiment. In the fourth embodiment, the same components as those of the casing 41 according to the first embodiment shown in FIG. As shown in FIG. 13, the adjacent arrangement surface 82Y2 and the arrangement surface 82M1 are connected by a connecting portion 484. Connection portion 484 has a plurality of flat portions. Specifically, the connection portion 484 has two plane portions 484a and 484b. The two flat portions 484a and 484b have different inclination angles. The inclination angles of the two plane portions 484a and 484b with respect to the plane S perpendicular to the rotation axis X of the rotary polygon mirror 46 are preferably 0 ° or greater and 66 ° or less. The connecting portion 484 extends continuously in the longitudinal direction of the arrangement surface 82Y2 and the arrangement surface 82M1.

  In the fourth embodiment, as in the first embodiment, there is an effect that it is easy to remove foreign matter in the housing 441 by air blowing. The same effect can be obtained even if the connecting portion 484 has three or more plane portions. That is, the connection part which connects the adjacent arrangement | positioning surfaces may contain the 1 or 2 or more plane part.

  The fifth embodiment will be described below with reference to FIG. In the fifth embodiment, the configuration of the image forming apparatus and the optical scanning device is the same as that of the first embodiment, and thus the description thereof is omitted. Hereinafter, the housing 541 according to the fifth embodiment will be described.

  FIG. 14 is a partial cross-sectional view of the housing 541 according to the fifth embodiment. In the fifth embodiment, the same components as those of the housing 41 according to the first embodiment shown in FIG. As shown in FIG. 14, the adjacent placement surface 82 </ b> Y <b> 2 and the placement surface 82 </ b> M <b> 1 are connected by a connection portion 584. The connecting portion 584 has a plurality of curved surface portions. Specifically, the connection portion 584 has two curved surface portions 584a and 584b. The angle of the tangent of the two curved surface portions 584a and 584b with respect to the plane S perpendicular to the rotation axis X of the rotary polygon mirror 46 is preferably 0 ° or more and 66 ° or less. The connecting portion 584 extends continuously in the longitudinal direction of the arrangement surface 82Y2 and the arrangement surface 82M1.

  In the fifth embodiment, as in the first embodiment, there is an effect that it is easy to remove foreign matter in the housing 541 by air blowing. Even if the connecting portion 584 has three or more curved portions, the same effect can be obtained. That is, the connection part which connects the adjacent arrangement | positioning surfaces may contain the 1 or 2 or more curved surface part.

  The sixth embodiment will be described below with reference to FIG. In the sixth embodiment, the configurations of the image forming apparatus and the optical scanning apparatus are the same as those in the first embodiment, and thus the description thereof is omitted. Hereinafter, the housing 641 according to the sixth embodiment will be described.

  FIG. 15 is a partial cross-sectional view of the housing 641 according to the sixth embodiment. In the sixth embodiment, the same components as those of the housing 41 according to the first embodiment shown in FIG. As shown in FIG. 15, the adjacent arrangement surface 82 </ b> Y <b> 2 and the arrangement surface 82 </ b> M <b> 1 are connected by a connection portion 684. The connecting portion 684 has a curved surface portion 684a and a flat surface portion 684b. The angle of the tangent of the curved surface portion 684a with respect to the plane S perpendicular to the rotation axis X of the rotary polygon mirror 46 is preferably 0 ° or more and 66 ° or less. The inclination angle of the plane portion 684b with respect to the plane S perpendicular to the rotation axis X of the rotary polygon mirror 46 is preferably 0 ° or greater and 66 ° or less. The connecting portion 684 extends continuously in the longitudinal direction of the arrangement surface 82Y2 and the arrangement surface 82M1.

  In the sixth embodiment, as in the first embodiment, there is an effect that foreign matter in the housing 641 can be easily removed by air blowing. Further, the same effect can be obtained even when the connecting portion 684 has a plurality of curved surface portions and one flat surface portion, a single curved surface portion and a plurality of flat surface portions, or a plurality of curved surface portions and a plurality of flat surface portions.

  In the above embodiment, an optical scanning device has been described in which a plurality of light beams emitted from a plurality of light sources are deflected by a single rotating polygon mirror to scan a plurality of photosensitive members. However, the same effect can be obtained even if the present invention is applied to an optical scanning device that scans a single photosensitive member with a light beam from a single light source. Further, in the above embodiment, the optical scanning device having the mirror arrangement surface is shown. However, the present invention may be applied to an arrangement surface that supports another optical component such as a lens. The same effect as the above embodiment can be obtained.

40... Optical scanning devices 41, 241, 341, 441, 541, 641... Casing 44 (44Y, 44M, 44C, 44Bk)... Light source L (LY, LM, LC, LBk). Light beam 46... Rotating polygon mirror 47 (47aL, 47aR, 47bL, 47bR)... Imaging lens (optical component)
48 (48Y, 48M1, 48M2, 48M3, 48C1, 48C2, 48C3, 48Bk) ... mirror (optical component)
50 (50Y, 50M, 50C, 50Bk) ... photoreceptor 82 (82Y (82Y1, 82Y2), 82M (82M1, 82M2), 82C, 82Bk) ... arrangement plane X ... rotation axis

Claims (12)

An optical scanning device,
A light source that emits a light beam;
A rotating polygon mirror that deflects the light beam so that the light beam emitted from the light source scans a photoreceptor;
A plurality of optical components for guiding the light beam to the photoreceptor;
A housing for holding the light source, the rotating polygon mirror, and the plurality of optical components;
A plurality of arrangement surfaces provided on the housing and supporting the plurality of optical components;
With
The plurality of arrangement surfaces extend in a longitudinal direction of the plurality of optical components,
The plurality of arrangement surfaces are inclined with respect to the rotation axis of the rotary polygon mirror,
An adjacent scanning surface among the plurality of mounting surfaces is inclined at different angles.   The optical scanning device according to claim 1, wherein the plurality of arrangement surfaces are flat surfaces.   The pair of support portions that support both end portions of the corresponding optical component among the plurality of optical components is provided on each of the plurality of arrangement surfaces. Optical scanning device.   4. The optical scanning device according to claim 1, wherein an inferior angle formed by the adjacent arrangement surfaces is greater than 0 ° and equal to or less than 126 °. 5.   The optical scanning device according to claim 1, wherein an inclination angle of the plurality of arrangement surfaces with respect to a plane perpendicular to the rotation axis is greater than 0 ° and equal to or less than 66 °.   6. The housing according to claim 1, wherein the plurality of arrangement surfaces are provided in the housing such that a distance to the photoconductor becomes shorter as the distance from the rotary polygon mirror increases. The optical scanning device described.   7. The optical scanning device according to claim 1, wherein the connection portion that connects the adjacent arrangement surfaces includes one or two or more plane portions.   The optical scanning device according to claim 7, wherein an inclination angle of the plane portion with respect to a plane perpendicular to the rotation axis is 0 ° to 66 °.   9. The optical scanning device according to claim 1, wherein the connection portion that connects the adjacent arrangement surfaces includes one or two or more curved surface portions.   10. The optical scanning device according to claim 9, wherein an angle of a tangent of the curved surface portion with respect to a plane perpendicular to the rotation axis is not less than 0 ° and not more than 66 °.   The optical scanning device according to claim 1, wherein the connection portion that connects between the adjacent arrangement surfaces is a ridge line. A photoreceptor,
The optical scanning device according to claim 1, wherein the photosensitive member is scanned with a light beam to form an electrostatic latent image on the photosensitive member.
A developing device for developing the electrostatic latent image with toner into a toner image;
A transfer device for transferring the toner image to a recording medium;
A fixing device for fixing the toner image on the recording medium;
An image forming apparatus.