Optical scanning apparatus and image forming apparatus

Abstract

To provide an optical scanning device that can block stray light reflected by an fθ lens. [Solution] The optical scanning device comprises a light-emitting element 81 that emits light rays, a polygon mirror 85 that reflects light rays, an fθ lens 86 into which light rays are incident, a reflective mirror 87 that guides light rays to the object to be scanned, a light ray detection unit that detects the emitted light rays, a first light-shielding unit 46 that blocks light rays incident on the fθ lens 86, and a second light-shielding unit 47 that blocks light rays reflected by the fθ lens 86. The fθ lens 86 has a scanning area, a static elimination area, and a detection area through which light rays detected by the light ray detection unit pass. The first light-shielding unit 46 is provided facing the boundary between the static elimination area and the detection area. The second light-shielding unit 47 is provided at a position opposite to the first light-shielding unit 46.

Description

Technical Field

[0001] The present disclosure relates to an optical scanning device and an image forming device in which irradiated light rays scan a scanned object.

Background Art

[0002] Conventionally, in an image forming device using an electrophotographic process technology, an optical scanning device that scans light (light rays) on a photoreceptor is used. In the optical scanning device, while scanning the light by reflecting it with a rotating polygon mirror (rotating multifaceted mirror), the light is irradiated onto a scanning lens (fθ lens). For such optical components, a method has been proposed for efficiently blocking reflected light generated in parts not related to the image while ensuring the light in parts related to image formation (see, for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] A conventional optical scanning device includes a scanning mirror having a plurality of reflecting surfaces that deflect and reflect a first light beam emitted from a laser light source, an fθ lens that forms an image of a second light beam deflected and reflected by the reflecting surface of the scanning mirror on an image plane, and a light shielding member for blocking a third light beam reflected by a reflecting surface adjacent to the reflecting surface from which the second light beam is deflected and reflected, and the light shielding member serves as a positioning means for the fθ lens.

[0005] Incidentally, image forming apparatuses perform processes such as static elimination by irradiating a photoreceptor with light rays and detecting scanning timing by receiving light rays, and there are light rays that are not involved in image formation. Furthermore, conventional optical scanning apparatuses have the problem that light-shielding members are placed at both ends of the fθ lens, so it is not possible to allow light rays that are not involved in image formation to enter the fθ lens.

[0006] Conventional optical scanning devices include a light source, a deflection means for deflecting and scanning a light beam from the light source, a scanning optical system for imaging the deflected and scanned light beam onto the surface to be scanned, a photodetector for detecting a synchronization signal to determine the timing for starting scanning onto the surface to be scanned, and a synchronization optical system for focusing the light beam onto the photodetector. Scanning light directed toward the surface to be scanned passes through the scanning light region of the scanning optical element, while synchronization light directed toward the synchronization optical system passes outside the scanning light region.

[0007] Optical components such as lenses have smooth surfaces (no roughness or unevenness) to avoid obstructing transmitted light, which can lead to stray light being reflected. Conventional optical scanning devices do not take stray light countermeasures into consideration, resulting in the problem that stray light reflected by lenses cannot be blocked.

[0008] This disclosure is made to solve the above-mentioned problems and aims to provide an optical scanning apparatus and an image forming apparatus that can block stray light reflected by an fθ lens. [Means for solving the problem]

[0009] The optical scanning apparatus according to this disclosure is an optical scanning apparatus in which an irradiated light ray scans an object to be scanned, comprising: a light source that emits a light ray; a rotating polyhedron mirror that reflects the light ray emitted from the light source; an fθ lens into which the light ray reflected by the rotating polyhedron mirror is incident; a reflective mirror that guides the light ray emitted from the fθ lens to the object to be scanned; a light ray detection unit that detects the light ray emitted from the fθ lens; a first light shielding unit that blocks the light ray incident on the fθ lens; and a second light shielding unit that blocks the light ray reflected by the fθ lens. The fθ lens comprises a scanning region through which a scanning ray for scanning an object to be scanned passes, a static elimination region including the scanning region through which a static elimination ray for eliminating static electricity from the object to be scanned passes, and a detection region located on both ends of the static elimination region through which a detection ray detected by the light detection unit passes. The first light-shielding portion is provided facing the boundary between the static elimination region and the detection region, and the second light-shielding portion is provided between the rotating polyhedron and the fθ lens, at a position opposite to the first light-shielding portion.

[0010] In the optical scanning apparatus according to this disclosure, the light-receiving surface of the second light-shielding portion may be configured to be inclined with respect to the incident surface of the fθ lens.

[0011] In the optical scanning apparatus according to this disclosure, the light-receiving surface of the second light-shielding section may be configured to be inclined with respect to the irradiation section that is irradiated by the light rays reflected by itself.

[0012] In the optical scanning apparatus according to this disclosure, the distance between the second light-shielding portion and the fθ lens may be shorter than the distance between the second light-shielding portion and the rotating polyhedron mirror.

[0013] The image forming apparatus according to this disclosure is characterized by comprising an optical scanning apparatus according to this disclosure. [Effects of the Invention]

[0014] According to this disclosure, by providing a first light-shielding portion, unintended light rays can be prevented from entering the fθ lens, while by providing a second light-shielding portion, stray light reflected by the fθ lens can be blocked. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic cross-sectional view showing the configuration of an image forming apparatus according to an embodiment of the present disclosure. [Figure 2] This is an external perspective view showing an optical scanning device as viewed from above. [Figure 3] This is an external perspective view showing a lower housing with an upper housing removed. [Figure 4] This is a top view showing a lower housing with an upper housing removed. [Figure 5] This is an enlarged perspective view showing the vicinity of a first shielding portion and a second shielding portion enlarged. [Figure 6] This is an explanatory top view showing the optical path of a light beam in an optical scanning device. [Figure 7] This is a schematic cross-sectional view showing an fθ lens and the vicinity of a second shielding portion enlarged.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, an image forming apparatus according to an embodiment of the present disclosure will be described with reference to the drawings.

[0017] FIG. 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus according to an embodiment of the present disclosure.

[0018] The image forming apparatus 100 is a multifunction device having a copying function, a scanner function, a facsimile function, and a printer function, and can transmit an image of a document read by an image reading device 130 to the outside, or form an image of a document read by the image reading device 130 or an image received from the outside in color or monochrome on a recording medium such as paper.

[0019] Above the image reading device 130, a document conveyance device 110 that is supported so as to be openable and closable is provided. The document conveyance device 110 conveys one or a plurality of documents one by one in order. The image reading device 130 reads a document placed on the document placement table 131 by scanning the scanning optical system, or reads a document conveyed by the document conveyance device 110 to generate image data.

[0020] The image forming apparatus 100 is provided with a fixing device, a photosensitive drum 2 (an example of a scanned object), a charger 3, a developing device 4, a drum cleaning device 5, an intermediate transfer belt device 7, a secondary transfer roller 11, an optical scanning device 12, a paper feeding unit 18, and the like.

[0021] In the image forming apparatus 100, image data corresponding to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y), or a monochrome image using a single color (for example, black) is handled. The image forming apparatus 100 is provided with four photosensitive drums 2, chargers 3, developing devices 4, and drum cleaning devices 5 for forming four types of toner images, each of which is associated with black, cyan, magenta, and yellow, and four image stations Pa, Pb, Pc, and Pd are configured.

[0022] The charger 3 uniformly charges the surface of the photosensitive drum 2 to a predetermined potential. The optical scanning device 12 exposes the surface of the photosensitive drum 2 to form an electrostatic latent image. The developing device 4 develops the electrostatic latent image on the surface of the photosensitive drum 2 to form a toner image on the surface of the photosensitive drum 2. The drum cleaning device 5 removes and collects the residual toner on the surface of the photosensitive drum 2. By the above-described series of operations, toner images of each color are formed on the surface of each photosensitive drum 2.

[0023] The intermediate transfer belt device 7 comprises intermediate transfer rollers 6, an endless intermediate transfer belt 71, an intermediate transfer drive roller 72, an intermediate transfer driven roller 73, and a cleaning device 9. Four intermediate transfer rollers 6 are provided inside the intermediate transfer belt 71 to form four different toner images corresponding to each color. The intermediate transfer rollers 6 transfer the toner images of each color formed on the surface of the photoreceptor drum 2 to the circulating intermediate transfer belt 71.

[0024] The intermediate transfer belt 71 is stretched over the intermediate transfer drive roller 72 and the intermediate transfer driven roller 73. In the image forming apparatus 100, the toner images of each color formed on the surface of each photoreceptor drum 2 are sequentially transferred and superimposed to form a color toner image on the surface of the intermediate transfer belt 71. The cleaning device 9 removes and collects waste toner that remains on the surface of the intermediate transfer belt 71 without being transferred to the paper.

[0025] The secondary transfer roller 11 grips the paper that has been transported through the paper transport path 21 in the transfer nip between it and the intermediate transfer belt 71 and transports it. As the paper passes through the transfer nip, the toner image on the surface of the intermediate transfer belt 71 is transferred to the paper and it is then transported to the fuser.

[0026] The fixing device includes a fixing roller 31 and a pressure roller 32 that rotate around an axis. The fixing device inserts the paper on which the toner image has been transferred into the nip between the fixing roller 31 and the pressure roller 32, heats and pressurizes it, and fixes the toner image to the paper.

[0027] The paper feeding unit 18 is equipped with a paper feeding cassette for loading recording media (paper) used for image formation and is located below the optical scanning device 12. The paper is pulled out of the paper feeding unit 18 by the pickup roller 16 and transported to the paper transport path 21. The paper transported to the paper transport path 21 passes through the secondary transfer roller 11 and the fuser device and is discharged to the output tray 19 by the discharge roller 17.

[0028] The paper transport path 21 includes a registration roller 14 and an output roller 17. The registration roller 14 transports the paper at a speed equal to the process speed at which the image is formed on the paper. The registration roller 14 is located between the paper feed section 18 and the secondary transfer roller 11, and adjusts the timing of paper transport so that the toner image is transferred to the paper by the secondary transfer roller 11. For example, the registration roller 14 holds the transported paper and waits (stops temporarily), then starts transporting the paper at a constant speed in synchronization with the secondary transfer roller 11.

[0029] When image formation is to be performed on the back side of the paper as well as the front side, the paper transport direction is changed by the discharge roller 17 and the paper is transported to the inversion transport path 22. In the inversion transport path 22, the paper is guided to the registration roller 14 with its front and back sides reversed by the inversion transport roller 15. The image forming apparatus 100 forms an image on the back side of the paper guided to the registration roller 14 in the same way as the front side and discharges it to the output tray 19.

[0030] A manual feed tray 150 is mounted on the front of the image forming apparatus 100 so as to be openable and closable, and an opening / closing door 160 is mounted on the rear of the image forming apparatus 100 so as to be openable and closable. Paper loaded in the open manual feed tray 150 is supplied to the manual feed transport path 23 near the front. The manual feed transport path 23 merges with the paper transport path 21 near the rear just before the registration roller 14, and the paper is transported to the registration roller 14 by the manual feed transport roller 13 located in the manual feed transport path 23. When the opening / closing door 160 is opened, the reversing transport path 22 is exposed, and jammed paper can be collected. The paper feeding section 18 is located below the manual feed transport path 23 and is configured to be able to be pulled out from the front.

[0031] Figure 2 is an external perspective view showing the optical scanning device as seen from above.

[0032] The optical scanning device 12 according to the embodiment of this disclosure has a housing composed of a lower housing 40 with an open top and an upper housing 50 that covers the top of the lower housing 40. The housing of the optical scanning device 12 is a thin, roughly rectangular parallelepiped. For the purposes of explanation below, the shorter side of the housing of the optical scanning device 12 when viewed from above may be referred to as the width direction X, the longer side when viewed from above may be referred to as the length direction Y, and the direction in which the top surface and bottom surface face each other may be referred to as the height direction Z.

[0033] The upper housing 50 is made of an opaque material almost entirely, with a portion of its top surface open. An ejection window 51 made of a transparent material is provided to cover the opening. The ejection window 51 is a long rectangle extending along the width direction X, and its length in the longitudinal direction is such that its end reaches the outer edge of the upper housing 50. The ejection window 51 is provided in four locations corresponding to the four photosensitive drums 2, and is spaced apart in the length direction Y.

[0034] The lower housing 40 is a container for housing optical components, and side walls are provided along the outer circumference of the bottom surface (bottom surface 45) of the lower housing 40. The side walls of the lower housing 40 are such that the first side wall 41 and the second side wall 42 face each other in the width direction X, and the third side wall 43 and the fourth side wall 44 face each other in the length direction Y.

[0035] A light source substrate 61, on which multiple light-emitting elements 81 (an example of a light source, see Figure 3) are mounted, is attached to the first side wall 41. In addition, a detection substrate 62 (an example of a light ray detection unit) on which a light-receiving element is mounted is attached to each of the third side wall 43 and the fourth side wall 44.

[0036] Next, the internal structure of the lower housing 40 will be explained with reference to Figures 3 and 4.

[0037] Figure 3 is an external perspective view showing the lower housing with the upper housing removed, and Figure 4 is an external top view showing the lower housing with the upper housing removed.

[0038] The lower housing 40 is fitted with optical components such as a light-emitting element 81, a collimator lens 82, an induction mirror 83, a cylindrical lens 84, a polygon mirror 85 (an example of a rotating polyhedron mirror), an fθ lens 86, a reflection mirror 87, a detection mirror 88, and a detection substrate 62. The optical scanning device 12 has an optical scanning system in which the light-emitting element 81, collimator lens 82, induction mirror 83, cylindrical lens 84, polygon mirror 85, fθ lens 86, and reflection mirror 87 are arranged in order from upstream to downstream in the direction of propagation of the light ray emitted from the light-emitting element 81.

[0039] There are four light-emitting elements 81, one for each of the four photoreceptor drums 2, and the light emitted from each light-emitting element 81 irradiates the corresponding photoreceptor drum 2.

[0040] There are four collimator lenses 82, corresponding to the four light-emitting elements 81, and they are positioned in the optical path of the light rays emitted from the light-emitting elements 81. The collimator lenses 82 make the incident light rays into parallel light before emitting them.

[0041] The induction mirror 83 guides the light rays emitted from the light-emitting elements 81 toward the polygon mirror 85. The structure to guide which of the four light rays corresponding to the light-emitting elements 81 is to be selected as appropriate, and the number of induction mirrors 83 can be changed as appropriate depending on the arrangement of the light-emitting elements 81.

[0042] The cylindrical lens 84 focuses light rays onto the scanning surface of the polygon mirror 85. The polygon mirror 85 is positioned approximately in the center of the lower housing 40 when viewed from above, has multiple scanning surfaces, and is rotationally driven by a motor.

[0043] The fθ lens 86 focuses the light rays deflected by the polygon mirror 85 onto the surface of the photoreceptor drum 2. In this embodiment, the system is configured to include two fθ lenses 86, which are arranged symmetrically with respect to the polygon mirror 85 in the length direction Y. In this embodiment, the polygon mirror 85 directs the light rays emitted from any two of the four light-emitting elements 81 toward the fθ lens 86 located on the third side wall 43, and the light rays emitted from the remaining two light-emitting elements 81 toward the fθ lens 86 located on the fourth side wall 44.

[0044] The reflective mirror 87 reflects the light rays emitted from the fθ lens 86 and guides them toward the corresponding emission window 51. The position and number of reflective mirrors 87 should be set appropriately so as not to interfere with the light rays' paths.

[0045] The detection mirror 88 reflects the light rays emitted from the fθ lens 86 and guides them toward the corresponding detection substrate 62. In this embodiment, the optical path of the light rays is set so that they travel from the fθ lens 86 to the detection substrate 62 via the detection mirror 88, but the embodiment is not limited to this, and the optical path may be set so that the light rays travel directly toward the detection substrate 62 after being emitted from the fθ lens 86. The optical paths of the light rays toward the reflection mirror 87 and the light rays toward the detection mirror 88 will be explained later with reference to Figure 6.

[0046] The light-receiving element on the detection board 62 outputs a signal indicating that it has received a light ray, and based on this signal, the timing before the start of the main scan is determined.

[0047] The bottom surface 45 of the housing is provided with a first light-shielding portion 46 and a second light-shielding portion 47 that protrude upward from the surrounding area. The first light-shielding portion 46 is positioned facing the incident surface of the fθ lens 86, and the second light-shielding portion 47 is positioned between the polygon mirror 85 and the fθ lens 86, opposite to the first light-shielding portion 46.

[0048] Figure 5 is an enlarged perspective view showing the vicinity of the first and second shielding sections. Note that in Figure 5, for the sake of readability, some components such as the reflective mirror 87 are shown removed from the lower housing 40.

[0049] The fθ lens 86 is a member that extends long in the width direction X (see, for example, Figure 4), and the first light-shielding portion 46 is provided at a position facing the vicinity of the end of the fθ lens 86 in the width direction X. The first light-shielding portion 46 is cylindrical in shape and extends upward from the bottom surface 45 of the housing, and the height of its upper end is lower than the upper end of the fθ lens 86.

[0050] The second light-shielding portion 47 faces the first light-shielding portion 46 in the longitudinal direction Y, and is positioned slightly closer to the center than the first light-shielding portion 46. As shown in Figure 4, the distance between the second light-shielding portion 47 and the fθ lens 86 is shorter than the distance between the second light-shielding portion 47 and the polygon mirror 85. In other words, the second light-shielding portion 47 is located between the polygon mirror 85 and the fθ lens 86, and is positioned closer to the fθ lens 86. The second light-shielding portion 47 is a projection that rises upward from the bottom surface 45 of the housing, and has an inclined surface on the fθ lens 86 side. Furthermore, the second light-shielding portion 47 is positioned so as not to obstruct the light rays traveling from the polygon mirror 85 to the fθ lens 86. The angle of the inclined surface of the second light-shielding portion 47 will be explained later with reference to Figure 7.

[0051] Figure 6 is an explanatory top view showing the optical path of a light ray in an optical scanning device. Note that, for the sake of clarity, only some of the optical components in the optical scanning device 12 are shown in Figure 6. Furthermore, in Figure 6, the first light-shielding section 46 and the second light-shielding section 47, which interfere with the light ray, are extracted and schematically shown from the lower housing 40.

[0052] Figure 6 shows the optical paths of light rays emitted from the two light-emitting elements 81 and scanned toward the third side wall 43 by the polygon mirror 85, along with the corresponding optical components. Note that the optical components located on the fourth side wall 44 are arranged in substantially the same manner as those on the third side wall 43, and the corresponding light rays follow substantially the same optical paths; therefore, their explanation is omitted. Furthermore, for explanatory purposes, the terminology used for the light rays may be changed as appropriate depending on which part of the optical path they correspond to.

[0053] As described above, the incident light ray NL emitted from the light-emitting element 81 passes through the collimator lens 82, the induction mirror 83, and the cylindrical lens 84 before entering the scanning surface of the polygon mirror 85. The incident light ray NL is then reflected by the polygon mirror 85, which rotates in the direction of arrow R, and scanned in a fan-shaped pattern.

[0054] In the fθ lens 86, multiple regions are defined for the incident position of light rays in the main scanning direction (corresponding to the width direction X in this embodiment) scanned by the polygon mirror 85. Specifically, for the fθ lens 86, the central part in the width direction X is defined as the scanning region 86a, a static elimination region 86b is provided outside the scanning region 86a, and a detection region 86c is provided further outside the static elimination region 86b. In other words, the central part in the width direction X is defined as the scanning region 86a, both ends in the width direction X are defined as detection regions 86c, and a static elimination region 86b is provided between the scanning region 86a and the detection region 86c.

[0055] The scanning ray SL that passes through the scanning area 86a is guided by the reflective mirror 87 and irradiates the corresponding photoreceptor drum 2 to scan it, contributing to image formation. The static elimination ray ZL that passes through the static elimination area 86b is guided by the reflective mirror 87 and irradiates the corresponding photoreceptor drum 2, contributing to static elimination of the photoreceptor drum 2. During static elimination, the photoreceptor drum 2 is irradiated by light rays that pass through both the scanning area 86a and the static elimination area 86b, and the static elimination area 86b includes the scanning area 86a. In other words, the light rays irradiate the photoreceptor drum 2 such that the area scanned during static elimination is wider than the area scanned during image formation. In Figure 6, for the sake of clarity, the static elimination area 86b is shown with the overlapping portion with the scanning area 86a omitted.

[0056] The detection ray KL that has passed through the detection area 86c is guided to the detection mirror 88 and received by the light-receiving element of the detection substrate 62.

[0057] In the fθ lens 86, the portion through which light rays heading towards the reflection mirror 87 pass and the portion through which light rays heading towards the detection mirror 88 pass are formed integrally. Therefore, at the joint between the two, the incident surface is bent, and light rays could be guided in an unintended direction. In contrast, in this embodiment, a first light-shielding portion 46 is provided facing the boundary between the static elimination region 86b and the detection region 86c, preventing light rays from entering unintended locations.

[0058] Next, the relationship between the stray light reflected by the fθ lens 86 and the second light-shielding section 47 will be explained with reference to Figure 7.

[0059] Figure 7 is a schematic cross-sectional view showing an enlarged view of the fθ lens and the vicinity of the second shielding portion. In Figure 7, for the sake of readability, only the essential parts are extracted and shown schematically, and hatching has been omitted.

[0060] As described above, the light rays scanned by the polygon mirror 85 (first ray LB1) enter the fθ lens 86, and most of them pass through the fθ lens 86 (corresponding to the second ray LB2) and illuminate the corresponding area. However, some of the light rays (third ray LB3) that are illuminated near the boundary between the static elimination area 86b and the detection area 86c are reflected from the incident surface of the fθ lens 86 and illuminate the polygon mirror 85 side. A second light-shielding section 47 is provided between the polygon mirror 85 and the fθ lens 86, and the third ray LB3 is reflected by the second light-shielding section 47. In this way, by providing the second light-shielding section 47, stray light reflected by the fθ lens 86 can be blocked.

[0061] The light-receiving surface of the second light-shielding section 47 is inclined upward with respect to the incident surface of the fθ lens 86, and reflects the third ray LB3 toward the upper housing 50. In this way, the second light-shielding section 47 reflects stray light so that it does not come toward the fθ lens 86, thus effectively blocking stray light. Furthermore, the light-receiving surface of the second light-shielding section 47 is inclined with respect to the illumination section TR toward which the fourth ray LB4, which it has reflected, is irradiated. In other words, the angle between the fourth ray LB4 and the illumination section TR (incident angle ω) is not a right angle, so that the stray light reflected by the second light-shielding section 47 does not return to the second light-shielding section 47 by following its original path, thus effectively blocking stray light. The second light-shielding section 47 is located close to the fθ lens 86, so it can deal with stray light before it diffuses significantly, allowing for efficient blocking of stray light.

[0062] The light-receiving surface of the second light-shielding section 47 only needs to be able to determine the direction in which stray light is directed to some extent, and may be roughened to reduce the intensity of the stray light.

[0063] Furthermore, the embodiments disclosed herein are illustrative in all respects and do not constitute a limiting interpretation. Accordingly, the technical scope of this disclosure is not to be interpreted solely by the embodiments described above, but is defined based on the claims. This includes all modifications within the meaning and scope of equivalents to the claims. [Explanation of symbols]

[0064] 2. Photosensitive drum (an example of a scanned object) 12 Optical scanning device 40 Lower cabinet 46 First light-shielding section 47. Second light-shielding section 50 Upper cabinet 62 Detection substrate (an example of a light detection unit) 81 Light-emitting element (an example of a light source) 82 Collimator Lens 83 Induction Mirror 84 Cylindrical Lens 85 Polygon Mirror (An example of a rotating polyhedron mirror) 86 fθ lens 87 Reflective mirror 88 Detection Mirrors 100 Image forming apparatus

Claims

1. An optical scanning device in which the emitted light beam scans the object to be scanned, A light source that emits light rays, A rotating polyhedron mirror that reflects light rays emitted from the aforementioned light source, The light ray reflected by the aforementioned rotating polyhedron mirror enters an fθ lens, A reflective mirror that guides the light rays emitted from the fθ lens to the object to be scanned, A light ray detection unit that detects the light ray emitted from the fθ lens, A first light-shielding portion that blocks light rays incident on the fθ lens, It comprises a second light-shielding portion that blocks the light rays reflected by the fθ lens, The aforementioned fθ lens is The scanning region through which the scanning ray that scans the object being scanned passes, A static elimination region including the scanning region, through which a static elimination light ray passes for eliminating static electricity from the object being scanned, It has detection regions located at both ends of the static elimination region, through which the detection light detected by the light detection unit passes, The first light-shielding portion is provided facing the boundary between the static elimination region and the detection region, The second light-shielding portion is located between the rotating polyhedron mirror and the fθ lens, and is positioned opposite the first light-shielding portion. An optical scanning device characterized by the following.

2. An optical scanning apparatus according to claim 1, The light-receiving surface of the second light-shielding portion is inclined with respect to the incident surface of the fθ lens. An optical scanning device characterized by the following.

3. An optical scanning apparatus according to claim 1, The light-receiving surface of the second light-shielding section is inclined with respect to the irradiating section onto which the light rays reflected by itself are projected. An optical scanning device characterized by the following.

4. An optical scanning apparatus according to claim 1, The distance between the second light-shielding portion and the fθ lens is shorter than the distance between the second light-shielding portion and the rotating polyhedron mirror. An optical scanning device characterized by the following.

5. An image forming apparatus comprising the optical scanning device described in claim 1.

Images