Scanning optical device and image forming apparatus

Abstract

To reduce the size of a blocking member that blocks laser beam fluxes and minimize the movable range of the blocking member, thereby reducing the size of a scanning optical device while preventing a reduction in mechanical accuracy due to thermal deformation.SOLUTION: A scanning optical device comprises a blocking member 130 that has a rotation shaft 131, and a blocking wall 132 rotating around the rotation shaft 131 to be movable between a blocking state to block laser beam fluxes L1, L2 and laser beam fluxes L3, L4 incident on a reflecting surface of a rotary polygon mirror 103 and a retreat state not to block the laser beam fluxes L1, L2 and the laser beam fluxes L3, L4, the blocking wall 132 provided to be located between the rotary polygon mirror 103 and a first optical member. When seen from the rotation axis direction of the rotary polygon mirror 103, the blocking member 130 is arranged so that the rotation shaft 131 is located on a bisector E of an angle formed by an optical path of the laser beam fluxes L1, L2 and an optical path of the laser beam fluxes L3, L4.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a scanning optical device and an image forming apparatus, and more particularly to a scanning optical device used in devices such as copying machines and laser beam printers, and an image forming apparatus having the scanning optical device. [Background technology]

[0002] Some scanning optical devices used in monochrome image forming apparatuses using electrophotography have a blocking member. For example, in Patent Document 1, the blocking member waiting at a first position rotates a predetermined amount around its rotation axis and moves to a second position. When the blocking member is in the first position, it blocks the optical path of the laser beam, and when it is in the second position, it opens (does not block) the optical path of the laser beam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-160641 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the configuration of the conventional blocking member is applied to a scanning optical device of a color image forming apparatus, the rotation angle and range of motion of the blocking member required to open the optical path of the laser light beam become large, resulting in a problem that the scanning optical device that houses the blocking member becomes large.

[0005] The present invention has been made under these circumstances, and aims to realize a miniaturized scanning optical device by reducing the size and range of motion of a blocking member that blocks a laser light beam, without reducing mechanical precision due to thermal deformation, etc. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention has the following configuration.

[0007] (1) A scanning optical device comprising: a plurality of light sources; a rotating polygon mirror having a reflecting surface and a first rotation axis, and rotating around the first rotation axis to reflect and deflect each of the light beams emitted from the plurality of light sources by the reflecting surface; a first optical member that guides each of the light beams emitted from the plurality of light sources to the rotating polygon mirror; a second optical member that guides each of the light beams deflected and scanned by the rotating polygon mirror to a scanned body; and a housing that accommodates the light sources, the rotating polygon mirror, the first optical member, and the second optical member, wherein the light sources include a first light source and a second light source, and the first light source and the second light source are arranged to define a first optical path of the light beams emitted from the first light source and a second optical path of the light beams deflected and scanned by the rotating polygon mirror when viewed from a first rotation axis direction of the rotating polygon mirror. a second optical path of a light beam emitted from a second light source is arranged symmetrically with respect to a virtual plane that passes through the first rotation axis and is parallel to the first rotation axis direction, and the second rotation axis and a blocking wall that can move between a blocking state in which the first optical path and the second optical path are blocked and a retracted state in which the first optical path and the second optical path are not blocked by rotating around the second rotation axis, the blocking wall being provided so as to be positioned between the rotating polygon mirror and the first optical member, and the blocking member being arranged so that the second rotation axis is located on the bisector of the angle between the first optical path and the second optical path when viewed from the first rotation axis direction.

[0008] (2) An image forming apparatus comprising the scanning optical device described in (1) above, a plurality of image carriers which are the scanned bodies, and a developing means for developing electrostatic latent images formed on the plurality of image carriers. Effect of the Invention

[0009] According to the present invention, it is possible to reduce the size of the blocking member that blocks the laser light beam and minimize its range of motion, thereby achieving a reduction in the size of the scanning optical device without reducing mechanical precision due to thermal deformation or the like. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view showing an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a schematic perspective view showing a scanning optical device according to an embodiment of the present invention; [Diagram 3] FIG. 1 is a schematic cross-sectional view of a main part of a scanning optical device according to an embodiment of the present invention, showing an oblique incidence optical system for a rotating polygon mirror. [Figure 4] FIG. 1 is a schematic cross-sectional view of a main part of a scanning optical device according to an embodiment of the present invention, showing an oblique incidence optical system for a rotating polygon mirror. [Diagram 5] FIG. 1 is a schematic cross-sectional view showing a scanning optical system of a scanning optical device according to an embodiment of the present invention; [Figure 6] FIG. 1 is a schematic perspective view showing a blocking member according to an embodiment of the present invention; [Figure 7] FIG. 1 is a schematic cross-sectional view showing an installation state of a scanning optical device and a blocking member according to an embodiment. [Figure 8] FIG. 1 is a schematic cross-sectional view showing an installation state of a scanning optical device and a blocking member according to an embodiment. [Figure 9] FIG. 13 is a schematic perspective view of a main part showing the operation of the blocking member of the embodiment; [Figure 10] FIG. 13 is an explanatory diagram showing the operation of the blocking member of the embodiment. [Figure 11] FIG. 13 is a schematic perspective view of a main part showing the operation of the blocking member of the embodiment; [Figure 12] FIG. 1 is an explanatory diagram showing the effects of the embodiment. [Figure 13] A diagram explaining the problems of the conventional example DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A case where a conventional blocking member used in a scanning optical device of a monochrome image forming apparatus is applied to a color image forming apparatus will be specifically described with reference to FIG. 13. For example, in a scanning optical device used in a color image forming apparatus, it is necessary to block and open the optical paths of four laser beams (Y, M, C, Bk) by a blocking member. When the configuration of a conventional blocking member used in a monochrome image forming apparatus is applied to this, the configuration is as shown in FIG. 13. The conventional blocking member 8 is arranged so as to intersect (for example, perpendicular to) the four laser beams. Here, the Y laser beam is L1, the M laser beam is L2, the C laser beam is L3, and the Bk laser beam is L4. In a typical scanning optical device of a color image forming apparatus, the four laser beams on the blocking member 8 are often arranged two by two in the vertical direction and at a certain interval in the horizontal direction.

[0012] 13, in a configuration in which the configuration of a conventional blocking member 8 is applied to a scanning optical device of a color image forming apparatus, the blocking member 8 waiting at a first position indicated by a solid line rotates a predetermined amount in the direction of arrow R about a rotation axis 8b and moves to a second position indicated by a dashed line. When the blocking member 8 is at the first position, it blocks the optical path of the laser beams L1 to L4, and when it is at the second position, it opens the optical path of the laser beams L1 to L4.

[0013] The rotation angle of the blocking member 8 configured as above is determined by the angle θ1 from the center of the rotation shaft 8b to the point where the optical path of the closest laser beam L1 is opened. The outer shape of the blocking member 8 is determined by the position of the laser beam L4 that is farthest from the center of the rotation shaft 8b of the blocking member 8 (solid line). For this reason, in the conventional blocking member 8, the amount of movement D in the up-down direction (vertical direction) increases when the blocking member 8 moves from the first position (solid line) to the second position (dotted line). This increases the movable range of the blocking member 8, and increases the size of the scanning optical device that is housed therein.

[0014] Therefore, in the present invention described below, the center of the rotation axis of the blocking member is located at the center of the multiple light beams incident on the rotating polygon mirror when viewed from the direction of the rotation axis of the rotating polygon mirror. This makes it possible to minimize the shape of the blocking member that blocks the light beams and the rotation angle of the blocking member. Below, an embodiment of the present invention will be described in detail with reference to the drawings. EXAMPLES

[0015] An image forming apparatus 1 according to an embodiment will be described with reference to FIGS.

[0016] (Image forming device overview) 1 is a schematic cross-sectional view of an image forming apparatus 1 of this embodiment, and shows a state in which a scanning optical device 2 and process cartridges PY, PM, PC, and PK are attached to the image forming apparatus 1. Note that the image forming apparatus 1 of this embodiment is a color image forming apparatus that forms a full-color image by superimposing four colors, yellow, magenta, cyan, and black.

[0017] The image forming process will be described with reference to FIG. 1. The scanning optical device 2 is disposed above the photosensitive drums 11a, 11b, 11c, and 11d, which are image carriers (and also scanned bodies) provided in the process cartridges PY, PM, PC, and PK. The scanning optical device 2 scans the laser beams L1, L2, L3, and L4 onto the photosensitive drums 11a, 11b, 11c, and 11d. The scanning optical device 2 is fixed to the frame of the image forming apparatus 1 by springs, screws, and the like (not shown). An optical box 101, which is a housing for accommodating optical components and the like to be described later, is disposed above the image forming apparatus 1 in the vertical direction. The opening of the optical box 101 is closed by a lid 102. The lid 102 is attached to the optical box 101 by screws and the like, and disposed below the image forming apparatus 1 in the vertical direction.

[0018] The photosensitive drums 11a, 11b, 11c, and 11d are charged in advance by charging rollers 12a, 12b, 12c, and 12d of the charger, and only the parts irradiated with the laser beams L1, L2, L3, and L4 lose their charge, forming an electrostatic latent image on the surface. The electrostatic latent image is turned into a toner image by developing rollers 13a, 13b, 13c, and 13d, which are developing means of the developer, and is transferred onto the intermediate transfer belt 21 in a superimposed manner by primary transfer rollers 22a, 22b, 22c, and 22d. Meanwhile, the recording paper S placed in a cassette 31 arranged below the intermediate transfer belt 21 is picked up by a pickup roller 32 in synchronization with the image forming process, and then the four-color toner image on the intermediate transfer belt 21 is transferred onto the recording paper S by a secondary transfer roller 33. Finally, the recording paper S passes through a fixing device 34 to fix the unfixed toner image, and is discharged by discharge rollers 35 and 36 to a discharge tray 37 outside the image forming apparatus 1. The image forming apparatus 1 is also provided with a front door 38 (door) that can be opened and closed, for example, when a user replaces the process cartridges PY, PM, PC, PK, etc. The front door 38 is in a closed state or an open state.

[0019] (Scanning Optical Device Overview) Next, the scanning optical device 2 of this embodiment will be described with reference to Figs. 2 to 5. Fig. 2 is a schematic perspective view showing the configuration of the scanning optical device 2. The coordinate system in this embodiment is as shown in Fig. 2. Here, the Z direction is defined as the sub-scanning direction, and the Y direction is defined as the main scanning direction. A virtual plane perpendicular (orthogonal) to the Z axis is defined as a scanning plane (second virtual plane). Fig. 3 is a cross-sectional view of the incident optical system showing the optical paths of the laser beams L1 and L2, and Fig. 4 is a cross-sectional view of the incident optical system showing the optical paths of the laser beams L1 and L3 until they reach the rotating polygon mirror 103. Fig. 5 is a cross-sectional view of the scanning optical system showing the optical paths of the laser beams L1, L2, L3, and L4 deflected and scanned by the rotating polygon mirror 103 until they reach the photosensitive drums 11a, 11b, 11c, and 11d. In the following description, the scanning optical systems corresponding to the respective colors are called Y station, M station, C station, and K station.

[0020] As shown in FIG. 2, the scanner motor 104 that rotates the rotating polygon mirror 103 is attached to an optical box 101 molded from resin or the like with screws (not shown). Next, a configuration in which laser beams L1, L2, L3, and L4 emitted from semiconductor lasers 111, which are a plurality of light sources, enter the rotating polygon mirror 103 will be described with reference to FIG. 2, FIG. 3, and FIG. 4. In this embodiment, the laser beams corresponding to the Y station, the M station, the C station, and the K station are respectively designated as L1, L2, L3, and L4. In FIG. 1 and the like, the optical paths of the laser beams L1 and L2 are designated as the first optical path, and the optical paths of the laser beams L3 and L4 are designated as the second optical path. The semiconductor laser 111 that emits the laser beams L1 and L2 is designated as the first light source, and the semiconductor laser 111 that emits the laser beams L3 and L4 is designated as the second light source.

[0021] The first light source and the second light source are arranged such that, when viewed from the rotation axis direction (first rotation axis direction) of the rotating polygon mirror 103, the first optical path and the second optical path are symmetrical with respect to a virtual plane (first virtual plane) (Ds in FIG. 4 described later) that passes through the first rotation axis and is parallel to the first rotation axis direction. Furthermore, when distinguishing between the laser beams L1 and L2, the semiconductor laser 111 that emits the laser beam L1 is referred to as a third light source, and the semiconductor laser 111 that emits the laser beam L2 is referred to as a fourth light source. Furthermore, when distinguishing between the laser beams L3 and L4, the semiconductor laser 111 that emits the laser beam L3 is referred to as a fifth light source, and the semiconductor laser 111 that emits the laser beam L4 is referred to as a sixth light source. Moreover, the optical path of the laser beam L1 is also referred to as a third optical path, the optical path of the laser beam L2 is also referred to as a fourth optical path, the optical path of the laser beam L3 is also referred to as a fifth optical path, and the optical path of the laser beam L4 is also referred to as a sixth optical path.

[0022] This embodiment is an oblique incidence scanning optical system. As shown in FIG. 3, the oblique incidence optical system is an optical system that makes the laser beams L1 and L2 obliquely incident on the deflection reflection surface of the rotating polygon mirror 103. In a specific configuration, the laser holder 112 that holds the semiconductor laser 111 is arranged vertically in the Z direction and tilted with respect to the X axis. The laser beams L1 and L2 emitted from the semiconductor laser 111 are parallel to the scanning plane and are incident on the deflection reflection surface of the rotating polygon mirror 103 at a predetermined angle θ2 with respect to a virtual plane Bs that passes through the center CZ of the deflection reflection surface of the rotating polygon mirror 103 in the Z direction.

[0023] 4, the laser holder 112 is arranged on the left and right in the X direction (left and right direction) and tilted with respect to the Y axis. The laser beams L1 and L3 emitted from the semiconductor laser 111 are incident on the deflection reflection surface of the rotating polygon mirror 103 at a predetermined angle θ3 with respect to a virtual plane Ds that is perpendicular to the scanning plane and passes through the center Cr (first rotation axis) of the rotating polygon mirror 103. After the position of the laser holder 112 is adjusted in the X, Y, and Z directions by a tool (not shown), it is fixed to the optical box 101 by, for example, a UV adhesive.

[0024] Next, as shown in Fig. 3, the laser beams L1 and L2 emitted from the semiconductor laser 111 are made into approximately parallel or convergent light in the main scanning direction by the anamorphic lens 113, which is an integrally molded collimator lens and a cylindrical lens, and are made into convergent light in the sub-scanning direction. After that, the beam width of the laser beams L1 and L2 is limited by the sub-scanning aperture stop 114a and the main-scanning aperture stop 115a, and the beams are imaged in the form of a focal line having a certain width in the main scanning direction on the deflection reflection surface of the rotating polygon mirror 103. By making the beams obliquely incident on the deflection reflection surface of the rotating polygon mirror 103, the laser beams L1 and L2 are reflected by the rotating polygon mirror 103 and then separated into upper and lower optical paths. Note that the laser beams L3 and L4 corresponding to the laser beams L1 and L2 have the same configuration as above, and are made into approximately parallel or convergent light in the main scanning direction by the anamorphic lens 113, and are made into convergent light in the sub-scanning direction. Thereafter, the widths of the laser beams L3 and L4 are limited by the sub-scanning aperture stop 114b and the main-scanning aperture stop 115b. The anamorphic lens 113, the sub-scanning aperture stop 114a, and the main-scanning aperture stop 115a are included in a first optical member.

[0025] Next, the scanning optical system of this embodiment will be described with reference to Figures 2 and 5. First, the optical paths of the laser beams L1 and L2 will be described. The laser beams L1 and L2 reflected by the rotating polygon mirror 103 are incident on a first imaging lens 116, which is a common first imaging means. Of the laser beams L1 and L2 emitted from the first imaging lens 116, the upper laser beam L2 in the Z direction is reflected by a first reflecting mirror 117. Thereafter, after passing through a second imaging lens 119a, it is reflected by a second reflecting mirror 118 and reaches the photosensitive drum 11b.

[0026] Of the laser beams L1 and L2 emitted from the first imaging lens 116, the lower laser beam L1 in the Z direction passes under the first reflecting mirror 117. Thereafter, it passes through the second imaging lens 119b, is reflected by the third reflecting mirror 120, and reaches the photosensitive drum 11a. The first imaging lens 116 is shared by the laser beams L1 and L2, and the second imaging lenses 119a and 119b are provided with separate lenses for the laser beams L1 and L2, respectively.

[0027] Next, the optical paths of the laser beams L3 and L4 will be described. The laser beams L3 and L4 reflected by the rotary polygon mirror 103 are incident on the first imaging lens 116, which is a common first imaging means. The lower laser beam L3 in the Z direction of the laser beams L3 and L4 emitted from the first imaging lens 116 is reflected by the fourth reflecting mirror 121. After that, it passes through the second imaging lens 119a, and is reflected by the fifth reflecting mirror 122 to reach the photosensitive drum 11c. The upper laser beam L4 in the Z direction of the laser beams L1 and L2 emitted from the first imaging lens 116 passes over the fourth reflecting mirror 121. After that, it passes through the second imaging lens 119b, is reflected by the sixth reflecting mirror 123, and reaches the photosensitive drum 11d.

[0028] The first imaging lens 116 is shared by the laser beams L3 and L4, and the second imaging lenses 119a and 119b are provided with separate lenses for the laser beams L3 and L4. Each imaging lens is fixed to the optical box 101 with a UV adhesive, and each reflecting mirror is fixed with a biasing member (not shown). The above-mentioned multiple imaging lenses and multiple reflecting mirrors are included in the second optical member.

[0029] 2, a beam detector (hereinafter, referred to as BD) 125 is mounted on a control board 124. In this embodiment, the laser light beam L4 is reflected by the rotating polygon mirror 103, deflected and scanned, and enters the BD 125. At this time, images of each color are written based on a signal (BD signal) output from the BD 125.

[0030] (Blocking member configuration) Next, the configuration of the blocking member 130 in this embodiment will be described. First, the role of the blocking member 130 will be described. The blocking member 130 in this embodiment is provided so that a blocking wall 132, which will be described later, is located between the rotating polygon mirror 103 and the first optical member. The blocking member 130 has a rotation axis 131, which is a second rotation axis, and a blocking wall 132 that can move between a blocking state and a retracted state by rotating around the rotation axis 131. Here, the blocking state is a state in which the blocking wall 132 blocks the first optical path and the second optical path incident on the reflecting surface of the rotating polygon mirror 103. In addition, the retracted state is a state in which the blocking wall 132 does not block the first optical path and the second optical path incident on the reflecting surface of the rotating polygon mirror 103. The blocking member 130 in this embodiment is characterized in that the rotation axis 131 is located on the bisector of the angle between the first optical path and the second optical path when viewed from the rotation axis direction (Z direction) of the rotating polygon mirror 103.

[0031] Blocking member 130 has a V-shaped blocking wall 132 at one end of rotating shaft 131, and a restricting wall 134 at the other end of rotating shaft 131. Rotating shaft 131 is provided at a bent portion of the V-shape so as to be perpendicular to blocking wall 132 and to be perpendicular to restricting wall 134. Meanwhile, optical box 101 has an abutting portion (101a in FIG. 9 described later) that abuts against restricting wall 134 when blocking member 130 is in the blocking state.

[0032] If the laser beams L1, L2, L3, and L4 emitted from the semiconductor laser 111 directly hit the human body, there is a risk of, for example, damage to the eyes. Therefore, for example, when the user opens the front door 38 to replace the process cartridges PY, PM, PC, and PK, a measure is required to prevent the laser beams L1, L2, L3, and L4 from leaking out of the scanning optical device 2. Therefore, in this embodiment, when the front door 38 is closed, that is, during image formation, the optical paths of the laser beams L1, L2, L3, and L4 from the semiconductor laser 111 to the rotating polygon mirror 103 are opened (not blocked). On the other hand, when the front door 38 is opened, a configuration is adopted in which the blocking member 130 blocks the optical paths of the laser beams L1, L2, L3, and L4 from the semiconductor laser 111 to the rotating polygon mirror 103.

[0033] Fig. 6 shows a schematic perspective view of blocking member 130 in this embodiment. As shown in Fig. 6(a) and (b), blocking member 130 is composed of a rotating shaft 131, a blocking wall 132, a rotating boss 133, a restricting wall 134, and a positioning protrusion 135. Blocking wall 132 is provided at one end of rotating shaft 131, and rotating boss 133, restricting wall 134, and positioning protrusion 135 are provided at the other end of rotating shaft 131.

[0034] A top view of blocking member 130 in this embodiment installed in optical box 101 is shown in Fig. 7, and a cross-sectional view is shown in Fig. 8. First, center CL of rotation axis 131 of blocking member 130 is disposed below (below) rotating polygon mirror 103 in the Z direction as shown in Fig. 8. Center CL of rotation axis 131 of blocking member 130 is disposed on bisector E of laser beams L1, L2 and laser beams L3, L4 incident on rotating polygon mirror 103 from semiconductor laser 111 in the X direction as shown in Fig. 7.

[0035] (Positional regulation of blocking member) Next, the positional restriction of the blocking member 130 with respect to the scanning optical device 2 will be described. As shown in FIG. 7, in the X direction, the rotation shaft 131 is restricted by a first restricting wall 136 and a second restricting wall 137 provided on the optical box 101. More specifically, the first restricting walls 136 are two walls arranged in the X direction, and restrict the movement in the X direction by sandwiching the rotation shaft 131 between the two walls on the blocking wall 132 side (blocking wall side). The second restricting walls 137 are two walls arranged in the X direction, and restrict the movement in the X direction by sandwiching the rotation shaft 131 between the two walls on the restricting wall 134 side (restricting wall side). In the Y direction, the blocking wall 132 and the restricting wall 134 sandwich the first restricting wall 136 and the second restricting wall 137 described above, thereby restricting the movement in the Y direction.

[0036] The optical box 101 is provided with a third restricting wall 138 and a fourth restricting wall 139. The lid 102 is provided with a fifth restricting wall 140 disposed at a position opposite to the third restricting wall 138 and a sixth restricting wall 141 disposed at a position opposite to the fourth restricting wall 139. As shown in FIG. 8, in the Z direction, the blocking wall 132 side of the rotating shaft 131 is restricted by the third restricting wall 138 and the fifth restricting wall 140, and the blocking wall 134 side of the rotating shaft 131 is restricted by the fourth restricting wall 139 and the sixth restricting wall 141. In addition, each restricting portion has a clearance in the X, Y, and Z directions so that the blocking member 130 can operate smoothly. In addition, the blocking wall 132 is disposed between the rotating polygon mirror 103 and the main scanning aperture stops 115a and 115b.

[0037] As described above, the optical box 101 has the first restriction wall 136 and the second restriction wall 137 that restrict the rotation shaft 131 in the X direction. The blocking member 130 restricts movement in the scanning direction by sandwiching the first restriction wall 136 and the second restriction wall 137 between the blocking wall 132 and the restriction wall 134. The optical box 101 has the third restriction wall 138 and the fourth restriction wall 139. The lid 102 has the fifth restriction wall 140 that restricts movement of the blocking wall 132 in the Z direction together with the third restriction wall 138, and the sixth restriction wall 141 that restricts movement of the restriction wall 134 in the Z direction together with the fourth restriction wall 139.

[0038] (Shut-off member operation) Next, the operation of the blocking member 130 in this embodiment will be described with reference to Figs. 9 to 11. The front door 38 is in an open state to allow access to the inside of the image forming apparatus 1, and is in a closed state when image formation is performed. The blocking member 130 is in a blocking state when the front door 38 is in an open state, and is in a retracted state when the front door 38 is in a closed state. The restricting wall 134 has a rotating boss 133. The image forming apparatus 1 is provided with a moving member 142 (see Fig. 10) that moves the rotating boss 133 in conjunction with the front door 38 to rotate the blocking member 130 around the rotating shaft 131.

[0039] Fig. 9 is a diagram showing the positional relationship between the blocking member 130, the laser beams L1, L2, L3, and L4, and the rotating polygon mirror 103 when the scanning optical device 2 is installed in the image forming apparatus 1 and the front door 38 is open. Fig. 10 is a diagram showing the operation of the blocking member 130 when the front door 38 changes from the state shown in Fig. 9 to a state where it is closed. Fig. 11 is a diagram showing the positional relationship between the blocking member 130, the laser beams L1, L2, L3, and L4, and the rotating polygon mirror 103 when the scanning optical device 2 is installed in the image forming apparatus 1 and the front door 38 is closed, that is, during image formation.

[0040] First, as shown in Fig. 9, when the front door 38 is open, the optical paths of the laser beams L1, L2, L3, and L4 from the semiconductor laser 111 to the rotating polygon mirror 103 are blocked by the blocking wall 132 so that the laser beams L1, L2, L3, and L4 do not leak out of the scanning optical device 2. At this time, the blocking member 130 maintains its posture by abutting the positioning protrusion 135 with the abutment portion 101a which is a part of the optical box 101. When the front door 38 is closed from the state shown in Fig. 9, the moving member 142 provided on the image forming apparatus 1 moves in the direction of the arrow A in conjunction with the operation of the front door 38, and the abutment surface 143 provided on the moving member 142 abuts against the rotating boss 133, as shown in Fig. 10.

[0041] In addition, the abutment surface 143 is inclined with respect to the Z direction. The reason for the inclination is that by applying a force in the Z direction to the rotating boss 133, the rotating boss 133 is rotated in the direction of arrow B around the center CL of the rotating shaft 131. In addition, when the rotating boss 133 rotates in the direction of arrow B, the blocking wall 132 rotates in the direction of arrow C. By the time the front door 38 is closed, the rotating boss 133 rotates a predetermined amount and reaches the state shown in FIG.

[0042] In Fig. 11, the optical paths of the laser beams L1, L2, L3, and L4 from the semiconductor laser 111 to the rotating polygon mirror 103 are opened, making it possible to form an image. In this embodiment, as shown in Fig. 11, the laser beams L1 and L2 pass above the blocking wall 132, and the laser beams L3 and L4 pass below the blocking wall 132. In this manner, when the blocking member 130 is in the retracted state, the third optical path and the fourth optical path are above the blocking wall 132 in the direction of the rotation axis of the rotating polygon mirror 103, and the fifth optical path and the sixth optical path are below the blocking wall 132 in the direction of the rotation axis of the rotating polygon mirror 103. The blocking wall 132 is V-shaped, and the rotation axis 131 is located at the bent portion of the V, so that the above can be realized by rotation.

[0043] (distance d1, d2, d3, d4) As described above, in the scanning optical device 2 of the color image forming apparatus 1, the optical paths of the four laser beams L1, L2, L3, and L4 must be blocked and opened by the blocking member 130. In this embodiment, as shown in Fig. 7, the center CL of the rotation shaft 131 of the blocking member 130 is disposed on the bisector E of the laser beams L1, L2 and the laser beams L3 and L4 incident on the rotating polygon mirror 103 from the semiconductor laser 111 in the X direction. Therefore, as shown in Fig. 9, the distances d1, d2, d3, and d4 from the center CL of the rotation shaft 131 to the laser beams L1, L2, L3, and L4 can be made substantially the same.

[0044] More specifically, the distances d1 to d4 are the following distances when the blocking member 130 is in a blocking state. The distance d1 is a first distance from a position where the third optical path of the light beam (laser beam L1) emitted from the third light source intersects with the blocking wall 132 to the rotation axis 131. The distance d2 is a second distance from a position where the fourth optical path of the light beam (laser beam L2) emitted from the fourth light source intersects with the blocking wall 132 to the rotation axis 131. The distance d3 is a third distance from a position where the fifth optical path of the light beam (laser beam L3) emitted from the fifth light source intersects with the blocking wall 132 to the rotation axis 131. The distance d4 is a fourth distance from a position where the sixth optical path of the light beam (laser beam L4) emitted from the sixth light source intersects with the blocking wall 132 to the rotation axis 131. At this time, in this embodiment, the distances d1, d2, d3, and d4 are the same distance. Therefore, the optical paths of the opposing laser beams L1 and L4, and L2 and L3 can be blocked and opened at approximately the same rotation angle. Therefore, the rotation angle of the blocking member 130 is small.

[0045] In this embodiment, the rotation angle of the blocking member 130 required to reliably block and open the optical paths of the four laser beams L1, L2, L3, and L4 can be set to, for example, 25°, taking into consideration the tolerances of each part and installation errors. In addition, in a configuration in which the center CL of the rotation axis 131 of the blocking member 130 is not located on the bisector E of the laser beams L1, L2 and the laser beams L3, L4 incident on the rotating polygon mirror 103 from the semiconductor laser 111 in the X direction, the following setting is required. That is, to achieve the same performance as this embodiment, the rotation angle θ1 shown in FIG. 13 needs to be set to 40°.

[0046] Fig. 12 is a diagram comparing the configuration of this embodiment after the blocking member 130 has rotated with the conventional blocking member 8 of Fig. 13. Comparing these two configurations as shown in Fig. 12, when the blocking member 130 is rotated, the following can be achieved. That is, when the optical paths of the laser beams L1, L2, L3, and L4 from the semiconductor laser 111 to the rotating polygon mirror 103 are open, the movable range of the blocking member 130 can be reduced in height by about 21 mm (D') in the Z direction. Note that even if the center CL of the rotation axis 131 of the blocking member 130 is slightly shifted in the X direction from the bisector E of the laser beams L1, L2 and the laser beams L3 and L4 incident on the rotating polygon mirror 103 from the semiconductor laser 111, the same effect can be obtained.

[0047] As described above, the center CL of the rotation axis 131 of the blocking member 130 of the scanning optical device 2 of the color image forming apparatus 1 is arranged in the X direction on the bisector E of the laser light beams L1, L2 and the laser light beams L3, L4 incident on the rotating polygon mirror 103 from the semiconductor laser 111. This makes it possible to reduce the rotation angle of the blocking member 130. Therefore, the movable range of the blocking member 130 can be reduced in the height direction, thereby realizing the miniaturization of the scanning optical device 2 and the image forming apparatus 1.

[0048] In this embodiment, the distances d1, d2, d3, and d4 from the center CL of the rotation axis 131 of the blocking member 130 to the laser beams L1, L2, L3, and L4 are substantially the same, so that it is possible to minimize the shape of the blocking wall 132. Therefore, the volume of the components of the scanning optical device 2, such as the blocking member 130 as well as the optical box 101 that houses the blocking member 130, is reduced, leading to cost reduction in terms of material costs.

[0049] In addition, since the shape of the blocking wall 132 can be minimized, thermal deformation of the blocking wall 132 can be suppressed. Specifically, for example, the thermal deformation of the blocking wall 132 occurs after storage in a high-temperature environment such as 60° C. or due to heat generated by the driving IC accompanying high-speed rotation of the scanner motor 104. In other words, the contribution of thermal deformation of the blocking member 130, which is one of the items to be considered when setting the required rotation angle of the blocking member 130 for blocking and opening the optical path of the laser light beams L1, L2, L3, and L4, can be reduced. Therefore, for example, the degree of freedom in designing the configuration of the blocking member 130 can be increased, such as by relaxing the individual component tolerance of the blocking member 130.

[0050] As described above, according to the embodiment, it is possible to reduce the size of the blocking member that blocks the laser light beam and minimize its range of motion, thereby achieving miniaturization of the scanning optical device without reducing mechanical precision due to thermal deformation or the like. [Explanation of symbols]

[0051] 2. Scanning optical device 101 Optical box 103 Rotating polygonal mirror 111 Semiconductor laser 130 Blocking member 131 Rotational axis 132 Barrier

Claims

1. A first light source that emits a first luminous beam, A second light source emitting a second luminous beam, A rotating polyhedron that reflects and deflects the first and second luminous beams, wherein, when viewed in the direction of the axis of rotation of the rotating polyhedron, the rotating polyhedron reflects the second luminous beam in the direction opposite to the direction in which the first luminous beam is reflected, A first lens through which the first light beam deflected by the rotating multifaceted mirror passes, A second lens through which the second light beam deflected by the rotating polyhedron mirror passes, wherein, when viewed in the axial direction of the rotation axis of the rotating polyhedron mirror, the second lens is located on the opposite side of the rotating polyhedron mirror from the side on which the first lens is located, A blocking member having a blocking wall that blocks the first optical path of the first light beam from the first light source toward the rotating polyhedron mirror and the second optical path of the second light beam from the second light source toward the rotating polyhedron mirror, wherein the blocking member is rotatable about a pivot axis and moves to a blocking position that blocks the first optical path and the second optical path, and to a retracted position that opens the first optical path and the second optical path, In a scanning optical apparatus having, The scanning optical apparatus is characterized in that the pivot axis of the blocking member is located between the first optical path and the second optical path when viewed in the axial direction of the rotation axis of the rotating polyhedron mirror, and the axis of the pivot axis of the blocking member extends in a direction intersecting the optical axis of the first lens.

2. The scanning optical apparatus according to Claim 1, characterized in that the blocking member is positioned such that, when viewed in the axial direction of the rotation axis of the rotating polyhedron, the rotation axis of the blocking member is aligned with the bisector of the angle between the first optical path and the second optical path.

3. The scanning optical apparatus according to Claim 1, wherein the scanning optical apparatus has a first optical member having a lens that makes the light beam a focusing light and an aperture diaphragm that limits the width of the light beam, and the blocking wall of the blocking member to which the first light beam and the second light beam strike is positioned between the optical member of the first optical member that is closest to the rotating polyhedron mirror and the rotating polyhedron mirror.

4. The scanning optical apparatus according to claim 1, characterized in that the pivot axis of the blocking member is positioned below the rotating polyhedron in the vertical direction.

5. The scanning optical device has a housing that houses the rotating polyhedron mirror, the first lens and the second lens, The blocking member has a blocking wall at one end of the pivot axis of the blocking member, and a restricting wall at the other end of the pivot axis of the blocking member, The scanning optical apparatus according to claim 1, characterized in that the housing has a contact portion that contacts the restricting wall when the blocking member is in the blocking position.

6. When viewed in the axial direction of the pivot axis of the blocking member, the blocking wall is V-shaped, The scanning optical apparatus according to claim 1, characterized in that the pivot axis of the blocking member is provided perpendicular to the blocking wall at the V-shaped bend.

7. The scanning optical apparatus according to Claim 1, characterized in that the distance from the position where the first luminous beam intersects the blocking wall to the pivot axis of the blocking member when the blocking member is in the blocking position is the same as the distance from the position where the second luminous beam intersects the blocking wall to the pivot axis of the blocking member.

8. The scanning optical apparatus according to claim 7, characterized in that when the blocking member is in the retracted position, the first optical path passes above the blocking wall in the vertical direction, and the second optical path passes below the blocking wall in the vertical direction.

9. The scanning optical apparatus according to claim 5, characterized in that the housing has a first restricting wall and a second restricting wall that restrict the movement of the blocking member in the axial direction of the pivot axis of the blocking member.

10. The scanning optical apparatus according to claim 9, characterized in that the blocking member restricts the movement of the pivot axis of the blocking member in the axial direction by sandwiching the first restricting wall and the second restricting wall between the blocking wall and the restricting wall of the blocking member.

11. The scanning optical device has a housing that houses the rotating polyhedron mirror, the first lens, and the second lens, The housing is equipped with a lid that closes the opening, The scanning optical apparatus according to claim 1, characterized in that the cover restricts the vertical movement of the blocking member.

12. A scanning optical apparatus according to claim 1, Multiple image carriers, A developing means for developing electrostatic latent images formed on multiple image carriers with toner, An image forming apparatus characterized by comprising:

13. The image forming apparatus is provided with a door that is open to allow access to the inside of the image forming apparatus and is closed when image forming is performed. The image forming apparatus according to claim 12, characterized in that the blocking member is in the blocking position when the door is in the open state and in the retracted position when the door is in the closed state.

14. The scanning optical apparatus according to claim 5, Multiple image carriers, A developing means for developing electrostatic latent images formed on multiple image carriers with toner, An image forming apparatus characterized by comprising:

15. The aforementioned restricting wall has a boss portion, The image forming apparatus comprises a door that is open to allow access to the inside of the image forming apparatus and closed when image forming is performed, and a movable member that moves in conjunction with the opening and closing of the door. The moving member rotates the blocking member by moving the boss portion. The image forming apparatus according to claim 14, characterized in that the blocking member is in the blocking position when the door is in the open state and in the retracted position when the door is in the closed state.

Images