Scanning optical device and image forming device

Abstract

To reduce deviation of a laser beam irradiation position due to a change of an attitude of a reflecting mirror.SOLUTION: A scanning optical device includes a light source, a deflector for deflecting a laser beam emitted from the light source, a reflection mirror 11 that is long in a first direction at which the laser beam deflected by the deflector is scanned by a scanned body, and has a surface 11e on which the laser beam is incident, a surface ffg on a side opposite to the surface 11e, and surfaces 11g and 11h substantially perpendicular to the surface 11e and the surface 11f, and positioning parts 50 and 60 for supporting the reflection mirror 11, wherein the positioning parts 50 and 60 have seating faces 15a, 15b and 15c for supporting the surface 11f, and position regulation parts 16a, 16b and 16c for regulating movement in a P direction that is substantially parallel to the surface 11f and is substantially perpendicular to the first direction, and the position regulation parts 16a, 16b and 16c are provided between ridge lines 11a and 11d regulated by the surface 11e and the surfaces 11g and 11h, and ridge lines 11b and 11c regulated by the surface 11f and the surfaces 11g and 11h.SELECTED DRAWING: Figure 4

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 that performs optical writing using a laser beam in an image forming apparatus such as a laser beam printer (LBP), a digital copier, or a digital facsimile (FAX). [Background technology]

[0002] Conventionally, in a scanning optical device used in a laser beam printer, a digital copier, etc., a laser beam modulated and emitted from a laser element, which is a light source, in response to an image signal is periodically deflected and scanned by an optical deflector such as a rotating polygon mirror. Then, an imaging optical element having an fθ characteristic focuses the laser beam from the optical deflector in the form of a spot on an imaging surface on a photosensitive drum. The spot on the imaging surface forms an electrostatic latent image in association with main scanning performed by the optical deflector and sub-scanning performed by the rotation of the photosensitive drum, thereby performing image recording. The optical deflector and the imaging optical element are supported by a housing, and the opening of the housing is closed by a lid.

[0003] Some scanning optical devices have a reflecting mirror for folding back the laser light so that the laser light is irradiated at a desired angle on the imaging surface on the photosensitive drum. The reflecting mirror that directs the laser light deflected by the optical deflector toward the scanned body is a long mirror with a large aspect ratio. For this reason, the reflecting mirror is often supported at both ends in the longitudinal direction and is supported and fixed by a regulating member such as a pressure spring. There are various types of regulating members as a fixing means for the reflecting mirror. For example, the regulating member described in Patent Document 1 is configured to press the reflecting mirror only in a direction perpendicular to the mirror reflecting surface in order to make the scanning optical device smaller and thinner.

[0004] When the pressure is applied to the reflecting mirror only in a direction perpendicular to the mirror reflecting surface, the position of the reflecting mirror in a direction parallel to the mirror reflecting surface is not restricted, so the reflecting mirror can move in a direction parallel to the mirror reflecting surface. As long as the laser light does not go beyond the mirror reflecting surface, the position of the laser light irradiated onto the photosensitive drum does not change even if the reflecting mirror moves in the parallel direction, and there is no effect on the print quality. For this reason, in Patent Document 1, a position regulating unit is provided to prevent the reflecting mirror from moving too much. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-120442 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional example, when the reflection mirror changes its position due to an impact during the logistics process of transporting the scanning optical device, the position restriction portion is arranged so that it may come into contact with the edge of the reflection mirror. Therefore, there is a possibility that the edge of the reflection mirror may get caught on the position restriction portion and not return to its original position. In that case, the irradiation position of the laser light irradiated onto the photosensitive drum may change due to the change in the position of the reflection mirror relative to the housing, which may lead to a decrease in printing accuracy and a decrease in image quality such as color shift.

[0007] The present invention has been made under these circumstances, and has an object to reduce deviation in the irradiation position of laser light caused by changes in the attitude of a reflecting mirror. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention has the following configuration. (1) Object to be scanned is scanned with a laser beam according to the image information. A scanning optical device, comprising: a light source; a deflection unit for deflecting a laser beam emitted from the light source; and a laser beam deflected by the deflection unit. A reflecting mirror reflects the light and guides it to the object to be scanned. and, the deflection means; The above Reflective mirror of Housing to accommodate and, an elastic member that biases the reflecting mirror toward the housing; Equipped with the reflection mirror has a first surface biased by the elastic member, a second surface opposite to the first surface, a third surface that is a surface that is approximately perpendicular to the first surface and the second surface and parallel to a first direction that is a longitudinal direction of the reflection mirror and is closer to an opening of the housing, and a fourth surface opposite to the third surface, The above housing a seat surface supporting the second surface; facing the third surface, A second direction that is substantially parallel to the second surface and substantially perpendicular to the first direction the reflecting mirror in the second direction toward an opening of the housing Restrict the movement of No. 1 The regulatory department, a second restriction portion opposed to the fourth surface and configured to restrict movement of the reflection mirror in a direction opposite to the second direction; and No. 1 The restriction portion is defined by the first surface and the third surface. Reflective mirror The first edge line of the second surface and the third surface of the Reflective mirror Between the second ridge Only a part of Established a distance between the first restricting portion and the second restricting portion in the second direction is greater than a length of the reflecting mirror in the second direction. 1. A scanning optical device comprising: (2) An image forming apparatus comprising: a photosensitive drum which is the scanned body; and the scanning optical device according to (1) above which forms a latent image on the photosensitive drum. Effect of the Invention

[0009] According to the present invention, it is possible to reduce deviation in the irradiation position of the laser light caused by a change in the attitude of the reflecting mirror. [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 perspective view showing a scanning optical device according to an embodiment of the present invention; [Diagram 3] FIG. 1 is a perspective view showing a housing shape near a reflecting mirror according to an embodiment of the present invention; [Figure 4] FIG. 1 is a cross-sectional view showing a state in which a reflecting mirror of an embodiment is in a normal position. [Diagram 5] FIG. 11 is a cross-sectional view showing a state in which the attitude of the reflecting mirror in the embodiment has changed. [Figure 6] FIG. 11 is a cross-sectional view showing a state in which the attitude of the reflecting mirror in the embodiment has changed. [Figure 7] FIG. 1 is a cross-sectional view showing a reflecting mirror (in a normal position) of a conventional example for comparison with the embodiment. [Figure 8]FIG. 1 is a cross-sectional view showing a conventional reflecting mirror (whose posture changes) for comparison with the embodiment. [Figure 9] FIG. 11 is a cross-sectional view showing the positional relationship of the position restriction portion according to the embodiment; [Figure 10] FIG. 1 is a perspective view showing a housing shape near a reflecting mirror of a first modified example; and FIG. 2 is a cross-sectional view showing a state in which the reflecting mirror is in a normal position. [Figure 11] 1 is a cross-sectional view showing a state where the posture of a reflection mirror of Modification 1 has been changed, and a cross-sectional view showing a state where the reflection mirror of Modification 2 is in a normal posture; FIG. [Figure 12] FIG. 13 is a perspective view showing a housing shape near a reflecting mirror according to a third modified example; [Figure 13] FIG. 11 is a cross-sectional view showing a state in which the attitude of the reflection mirror of the third modification has been changed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings by way of examples. EXAMPLES

[0012] (Image forming device) FIG. 1 shows an example of a schematic configuration of an image forming apparatus. A laser beam printer 1100 (hereinafter referred to as printer 1100) includes a photosensitive drum 1101, a charging unit 1102, and a developing unit 1103. The photosensitive drum 1101 is an image carrier on which a latent image (hereinafter referred to as electrostatic latent image) is formed by a scanning optical device 1. The charging unit 1102 uniformly charges the photosensitive drum 1101. The developing unit 1103 forms a toner image by developing the electrostatic latent image formed on the photosensitive drum 1101 with toner. The toner image formed on the photosensitive drum (on the scanned body) is transferred by a transfer unit 1105 to a sheet P as a recording material supplied from a cassette 1104, and the unfixed toner image transferred to the sheet P is fixed by a fixing device 1106. The photosensitive drum 1101, the charging unit 1102, the developing unit 1103, and the transfer unit 1105 constitute an image forming unit (image forming means). The fixed sheet P is discharged onto a tray 1107. The printer 1100 also includes a power supply device 1108, which supplies power to a drive unit such as a motor and a control unit 1109. The control unit 1109 has a CPU (not shown) and controls the image forming operation by the image forming unit and the conveying operation of the sheet P. Note that the image forming device to which the scanning optical device 1 of the present invention can be applied is not limited to the configuration exemplified in FIG.

[0013] (scanning optical device) A scanning optical device 1 according to an embodiment to which the present invention can be applied will be described with reference to the drawings. FIG. 2 is a perspective view of the scanning optical device 1 according to the embodiment. A housing 5, which is a case, has a side surface 5a on which a laser light source unit 2, which is a light source, is attached, and a bottom surface 5b on which an optical deflector 9, which is a deflection means, is attached, and the side opposite to the bottom surface 5b is open. As shown in FIG. 2, the laser light 3 shown by the broken line emitted from the laser light source unit 2 is approximately focused by an anamorphic lens 4. Then, the laser light is limited to a predetermined beam diameter by an optical diaphragm 6 formed in the housing 5, and is irradiated onto a reflecting surface of a rotating polygon mirror 7. The rotating polygon mirror 7 is rotated by a driving circuit board 8, and deflects and scans the incident laser light 3. Here, the rotating polygon mirror 7 and the driving circuit board 8 constitute an optical deflector 9. The laser light 3 deflected by the optical deflector 9 passes through an fθ lens 10, is reflected by a reflection mirror 11, which is a long optical member, and is focused and scanned on a photosensitive drum 1101 (see FIG. 1), which is an image carrier, to form an electrostatic latent image. The long reflection mirror 11 is biased by a pressure spring 12, which is a common elastic member, at positioning portions 50 and 60, which are support portions at two locations, for example at both ends, in the longitudinal direction, and is attached and supported. The opening of the housing 5 is closed by a cover (not shown). In the following description, the longitudinal direction of the reflecting mirror 11 and the scanning direction of the laser light are defined as the first direction, that is, the X direction, the rotation axis direction of the rotating polygon mirror 7 is defined as the Z direction, and the direction approximately perpendicular to the X direction and the Z direction is defined as the Y direction.

[0014] Here, as shown in FIG. 4 and the like to be described later, the reflecting mirror 11 has four ridges 11a (first ridges line) , 11b (second edge line) , 11c (No. 4 Ridge line) , 11d (Article 3 Ridge line) The reflecting mirror 11 has a surface 11e (first surface) that is pressed by the pressing spring 12, and a surface 11f (second surface) that is supported by the housing 5 on the opposite side to the surface 11e. The reflecting mirror 11 also has a surface 11g (third surface) that is substantially perpendicular to the surfaces 11e and 11f. surface) , 11h(No. 4 sides), where face 11g is the face on the + side (upper side) in the Z direction, and face 11h is the face on the - side (lower side) in the Z direction. Ridge line 11a is a ridge line defined by faces 11e and 11g, and is the ridge line on the + side (upper side) of face 11e in the Z direction. Ridge line 11d is a ridge line defined by faces 11e and 11h, and is the ridge line on the - side (lower side) of face 11e in the Z direction. Ridge line 11b is a ridge line defined by faces 11f and 11g, and is the ridge line on the + side (upper side) of face 11f in the Z direction. Ridge line 11c is a ridge line defined by faces 11f and 11h, and is the ridge line on the - side (lower side) of face 11f in the Z direction.

[0015] (Reflector mirror installation) Next, the attachment of the reflecting mirror 11 to the housing 5 will be described. First, the shape of the vicinity of the positioning parts 50, 60 in the housing 5 will be described using the perspective views of Figs. 3(a) and (b). For the purpose of explanation, the reflecting mirror 11 and the pressing spring 12 are omitted from the illustration. The positioning part 50 of the housing 5 shown in Fig. 3(a) is provided on one end side of the reflecting mirror 11 in the X direction. The positioning part 50 side has seats 15a, 15b and position regulating parts 16a, 16b. The seat 15a, which is the first seat, is provided on the position regulating part 16a side (first regulating part side) which is the first regulating part in the P direction which is the second direction described later. The seat 15b, which is the second seat, is provided on the position regulating part 16b side (second regulating part side) which is the second regulating part in the P direction. The position regulating part 16a has a shape that protrudes toward the surface 11g of the reflecting mirror 11 in a state where it is assembled in a normal position. The position restriction portion 16b has a shape that protrudes toward the surface 11h of the reflecting mirror 11 when it is assembled in the correct position.

[0016] 3(b), the positioning portion 60 of the housing 5 is provided on the other end side of the reflecting mirror 11 in the X direction. The positioning portion 60 has a seating surface 15c, which is a third seating surface, a position restricting portion 16c (first restricting portion), and a position restricting portion 16d (second restricting portion). The position restricting portion 16c has a shape that protrudes toward a surface 11g of the reflecting mirror 11 in a state where it is assembled in a normal position. The position restricting portion 16d has a shape that protrudes toward a surface 11h of the reflecting mirror 11 in a state where it is assembled in a normal position. The seating surfaces 15a and 15b have a convex shape with respect to the base surface 14a, and the seating surface 15c has a convex shape with respect to the base surface 14b. Here, the base surfaces 14a and 14b face the surface 11f of the reflecting mirror 11, and are base surfaces on which the seating surfaces 15a, 15b, and 15c are provided. Thus, the positioning portion 50 on one side has two seating surfaces 15a, 15b, and the positioning portion 60 on the other side has one seating surface 15c.

[0017] Next, the state in which the reflecting mirror 11 is assembled in the housing 5 in the correct position is shown in cross-sectional views of Figures 4(a) and (b) as viewed from the longitudinal direction (main scanning direction). Figure 4(a) shows a cross-sectional view of the positioning unit 50 side, and Figure 4(b) shows a cross-sectional view of the positioning unit 60 side. For the sake of the following explanation, the direction that is approximately parallel to the imaginary plane formed by the seating surfaces 15a, 15b, and 15c and approximately parallel to the arrangement direction of the seating surfaces 15a and 15b is defined as the P direction. Also, the direction approximately perpendicular to the P direction is defined as the third direction, the Q direction, the direction in which the laser light is scanned by the optical deflector 9 (main scanning direction) is defined as the S axis (X direction), and the direction perpendicular to the S axis is defined as the Z direction.

[0018] The reflecting mirror 11 is pressed by the pressing spring 12 to come into contact with the seats 15a, 15b, and 15c, determining the installation angle, and the reflected laser light is focused and scanned at a predetermined position on the photosensitive drum 1101. In other words, the irradiation position of the scanning optical device 1 on the photosensitive drum 1101 is guaranteed.

[0019] In this embodiment, the angle of the reflecting mirror 11 is determined by abutting the three surfaces, 15a, 15b, and 15c, in order to further stabilize the initial angle of the reflecting mirror 11 around the S-axis. Specifically, of the three surfaces, 15a, 15b, and 15c, the angle around the S-axis is determined by the surfaces 15a and 15b. Therefore, the angle of the reflecting mirror 11 around the S-axis is determined without being affected by the relative positions of the surfaces 15a and 15b and the surface 15c, which are arranged on both sides of the long reflecting mirror 11, and a stable initial angle can be realized.

[0020] Position restriction portions 16a, 16b, 16c, and 16d are disposed above and below the reflecting mirror 11 in the direction P. The width Wa of the position restriction portions 16a and 16b and the width Wb of the position restriction portions 16c and 16d are both wider (larger) than the width Wm of the reflecting mirror 11 (Wa>Wm, Wb>Wm). For this reason, when the reflecting mirror 11 is attached to the positioning portions 50 and 60 in the correct position, the surface 11g of the reflecting mirror 11 does not abut against the position restriction portions 16a and 16c, and the surface 11h of the mirror 11 does not abut against the position restriction portions 16b and 16d.

[0021] Here, width Wa is the distance in the P direction between position restricting portion 16a and position restricting portion 16b, and width Wb is the distance in the P direction between position restricting portion 16c and position restricting portion 16d. Furthermore, width Wm is the length of reflecting mirror 11 in the P direction. Furthermore, since the load F of pressing spring 12 is applied only in the Q direction, reflecting mirror 11 is movable in the P direction. Note that pressing spring 12 has pressing portion 12a, and the load F is generated when pressing portion 12a abuts against and presses surface 11e of reflecting mirror 11.

[0022] Eliminating the constraint on the reflecting mirror 11 in the P direction makes it easier to assemble the reflecting mirror 11 to the housing 5. Furthermore, since there is no need to create a shape for the pressure spring 12 that presses in the P direction, there are advantages such as simplifying the pressure spring 12 and reducing costs. As for the quality of the scanning optical device 1, even if the reflecting mirror 11 moves in the P direction, as long as it is in contact with the seating surfaces 15a, 15b, and 15c, the installation angle of the reflecting mirror 11 does not change, and the irradiation position of the laser light on the photosensitive drum 1101 is not affected.

[0023] (Impact of shocks applied to optical scanning devices during logistics, etc.) The position restriction portions 16a and 16c are disposed inside the ridge lines 11a and 11b of the reflecting mirror 11 in the direction Q. Moreover, the position restriction portions 16b and 16d are disposed inside the ridge lines 11c and 11d of the reflecting mirror 11 in the direction Q. This makes it possible to prevent the attitude of the reflecting mirror 11 from changing due to the influence of an impact applied to the image forming apparatus during a logistics process or the like.

[0024] The effect of this embodiment will be described with reference to Figures 5(a), (b) and 6(a) and (b). Figure 5 is a cross-sectional view seen from the longitudinal direction (main scanning direction) showing an example of the attitude of the reflecting mirror 11 when an impact is applied. Figures 5(a) and 6(a) show cross-sectional views of the positioning unit 50 side, and Figures 5(b) and 6(b) show cross-sectional views of the positioning unit 60 side.

[0025] (Case 1: Posture shift due to impact) 5(a) and (b) show a case where the posture of the reflecting mirror 11 changes in the Z+ direction and in the clockwise direction of the S axis (dotted arrow in the figure) due to the application of an impact. The reflecting mirror 11 floats off the seat surface 15a and comes into contact with the position restricting parts 16a and 16c. However, the ridges 11a and 11b of the reflecting mirror 11 do not come into contact with either of the position restricting parts 16a and 16c, and the position restricting parts 16a and 16c come into contact with the inner surfaces 11g of the ridges 11a and 11b. In this case, the only obstacle to the movement of the reflecting mirror 11 in the Q direction due to the load F of the pressing spring 12 is the frictional force between the reflecting mirror 11 and the position restricting parts 16a and 16c. Therefore, the load F of the pressing spring 12 can easily return the reflecting mirror 11 from the state shown in FIG. 5(a) and (b) to the normal posture shown in FIG. 4(a) and (b).

[0026] (Case 2: Posture shift due to impact) 6(a) and (b) show a case where the posture of the reflecting mirror 11 changes in the Z-direction and in the counterclockwise direction of the S-axis (dotted arrow in the figure) due to the application of an impact. The reflecting mirror 11 floats off the seat surface 15b and comes into contact with the position restricting parts 16b and 16d. However, the ridges 11c and 11d of the reflecting mirror 11 do not come into contact with either the position restricting parts 16b or 16d, and the position restricting parts 16b and 16d come into contact with the inner surfaces 11h of the ridges 11c and 11d. In this case, the only obstacle to the movement of the reflecting mirror 11 in the Q direction due to the load F of the pressing spring 12 is the frictional force between the reflecting mirror 11 and the position restricting parts 16b and 16d. Therefore, the load F of the pressing spring 12 can easily return the reflecting mirror 11 from the state shown in FIG. 6(a) and (b) to the normal posture shown in FIG. 4(a) and (b). In this way, when an impact is applied to the scanning optical device 1, the posture of the reflecting mirror 11 changes temporarily, but the load F of the pressure spring 12 allows the reflecting mirror 11 to easily return to the normal posture, and thus no fluctuation in the irradiation position occurs.

[0027] (Comparison with conventional examples) On the other hand, unlike this embodiment, when the position regulating portion is also disposed outside the ridges 11b and 11c of the reflecting mirror 11 in the Q direction as in the conventional configuration, the change in the posture of the reflecting mirror 11 when an impact is applied is shown in Figs. 7(a), (b) and 8. Figs. 7(a) and (b) show a state in which the reflecting mirror 11 is in a normal posture, and Fig. 8 shows a cross-sectional view seen from the positioning portion 150 side when an impact is applied and the reflecting mirror 11 moves in the Z+ direction and in the clockwise direction of the S axis. The reflecting mirror 11 and the pressing spring 12 are the same as those in this embodiment. However, since the shape of the housing 105 is different from that of this embodiment, the positioning portion is also different accordingly.

[0028] The positioning unit 150 shown in FIG. 7(a) corresponds to the positioning unit 50 of this embodiment. In the normal position, the reflecting mirror 11 abuts against the seating surfaces 115a and 115b, and the position restricting units 116a and 116b are arranged above and below the reflecting mirror 11 in the P direction. In the normal position, the position restricting units 116a and 116b do not abut against the surfaces 11g and 11h of the mirror 11, respectively. The positioning unit 160 shown in FIG. 7(b) corresponds to the positioning unit 60 of this embodiment. In the normal position, the reflecting mirror 11 abuts against the seating surface 115c, and the position restricting units 116c and 116d are arranged above and below the reflecting mirror 11 in the P direction. In the normal position, the position restricting units 116c and 116d do not abut against the surfaces 11g and 11h of the mirror 11, respectively.

[0029] In this embodiment, as shown in Fig. 4(a) and (b), the position restricting portions 16a, 16b, 16c, and 16d are disposed inside the ridges 11a and 11b of the reflecting mirror 11 and inside the ridges 11c and 11d of the reflecting mirror 11 in the Q direction. On the other hand, in Fig. 7(a), (b), and Fig. 8, the position restricting portions 116a, 116b, 116c, and 116d are disposed outside the ridges 11b and 11c of the reflecting mirror 11 in the Q direction. In this configuration, when the reflecting mirror 11 moves as shown in Fig. 8, the reflecting mirror 11 comes into contact with the position restricting portion 116a at the ridges 11b. In this case, when the reflecting mirror 11 moves in the Q direction due to the load F of the pressing spring 12, the ridges 11b get caught by the position restricting portion 116a, and the position is maintained and does not return to the original position. This causes a change (deviation) in the installation angle of the reflecting mirror 11, in other words, a change from the normal position, which causes a fluctuation in the irradiation position.

[0030] 8 shows the state of the positioning unit 150 side when an impact is applied that moves the reflecting mirror 11 in the positive Z direction and in the clockwise direction of the S axis (dotted arrow in the figure) as shown in FIG. 5(a). As with the positioning unit 150 side, a similar change in posture can occur on the positioning unit 160 side. Depending on the direction of the change in posture of the reflecting mirror 11 due to the impact, other edges (11a, 11c, 11d) of the reflecting mirror 11 may get caught on the position restriction units (116a, 116b, 116c, 116d), causing a change in the installation angle of the reflecting mirror 11.

[0031] (Optimal position of position regulation part) Next, the optimal position of the position restricting portion in this embodiment will be described with reference to FIG. 9. FIG. 9 is a cross-sectional view seen from the positioning portion 60 side, and shows the positions of the position restricting portions 16c and 16d with respect to the ridges 11a, 11b, 11c, and 11d of the reflecting mirror 11. In this embodiment, on the positioning portion 60 side that receives the reflecting mirror 11 at one point on the seating surface 15c, the seating surface 15c has a convex shape with respect to the base surface 14b in the Q direction, so there is space above and below in the P direction, and the reflecting mirror 11 may move during a logistics process or the like. For this reason, it is desirable to arrange the reflecting mirror 11 so that the ridges 11a, 11b, 11c, and 11d do not hit the position restricting portions 16c and 16d even if the reflecting mirror 11 moves by that amount.

[0032] The symbols in the figure will be explained. Distance a is the distance in the P direction between seating surface 15c and position restriction portion 16c. Distance b is the distance in the P direction between seating surface 15c and position restriction portion 16d. Protrusion amount c is the protrusion amount in the Q direction of seating surface 15c relative to base surface 14b. When the width, which is the length in the P direction of reflection mirror 11, is width d, distance L1 in the Q direction from position restriction portion 16c to edge line 11a is: L1 ≧ c × b / (db) The distance L2 in the Q direction from the position restriction portion 16c to the ridge line 11b is L2 ≧ c × b / (db) The distance L3 in the Q direction from the position restriction portion 16d to the ridge line 11c is L3 ≧ c × a / (da) The distance L4 in the Q direction from the position restriction portion 16d to the ridge line 11d is L4 ≧ c × a / (da) It is desirable to do so.

[0033] To give a specific numerical example, when distance a = 5 mm, distance b = 5.7 mm, protrusion amount c = 0.15 mm, and width d = 10 mm, it is desirable that distance L1 and distance L2 be 0.20 mm or more, and distance L3 and distance L4 be 0.15 mm or more.

[0034] (Description of Modifications) (Variation 1) Next, a first modified example of this embodiment is shown in Figures 10(a) and (b). Figure 10(a) is a perspective view of the housing 5 near the positioning portion 60, and Figure 10(b) is a cross-sectional view seen from the positioning portion 60 side. A backup surface 17a, which is a first protrusion, and a backup surface 17b, which is a second protrusion, are provided above and below the seating surface 15c in the P direction. The backup surface 17a is provided near the seating surface 15c in the P direction, and the backup surface 17b is provided on the opposite side of the seating surface 15c to the backup surface 17a in the P direction. This makes it possible to restrict the change in posture of the reflecting mirror 11 within a certain range during the logistics process, etc.

[0035] The protrusion amount of the backup surfaces 17a and 17b in the Q direction is smaller than the protrusion amount of the seat surface 15c in the Q direction. Even if the backup surfaces 17a and 17b are not present, the same restriction effect can be achieved by lowering (reducing) the convex amount (the above-mentioned protrusion amount c) of the seat surface 15c relative to the base surface 14b. However, by limiting the surface, it becomes easier to correct the mold during molding, it becomes easier to achieve positional accuracy, and it is possible to minimize the position g of the backup surface in the Q direction relative to the seat surface 15c.

[0036] In addition, the backup surfaces 17a and 17b are disposed inside the ridges 11b and 11c of the reflecting mirror 11 in the P direction. Therefore, even if the reflecting mirror 11 changes its posture during a logistics process or the like, the ridges 11b and 11c do not come into contact with the backup surfaces 17a and 17b as shown in FIG. 11(a). Here, FIG. 11(a) shows the state of the positioning unit 60 side when an impact is applied to the reflecting mirror 11 so that it moves in the Z plus direction and in the clockwise direction of the S axis (dotted arrow in the figure) as shown in FIG. 5(a). Furthermore, in FIG. 11(a), the backup surface 17b comes into contact with the surface 11f, restricting the posture change of the reflecting mirror 11 to within a certain range. This also prevents the ridge 11c of the reflecting mirror 11 from coming into contact with the base surface 14b. This prevents the ridges 11b and 11c from coming into contact with and getting caught on the base surface 14b or the backup surfaces 17a and 17b, thereby preventing the change in the attitude of the reflecting mirror 11 from being maintained. The same applies when an impact is applied that moves the reflecting mirror 11 in the positive Z direction and in the counterclockwise direction around the S axis (not shown). The other configurations are the same as those in the above-mentioned embodiment, and the same reference numerals will be used and the description will be omitted.

[0037] (Variation 2) Next, a second modified example of this embodiment is shown in a cross-sectional view near the positioning portion 60 in FIG. 11(b). In this embodiment, the position regulating portions 16a, 16b, 16c, and 16d are molded integrally with the housing 5, but this is not limited thereto. As shown in FIG. 11(b), a part of the position regulating portions may be provided as a separate member such as a cover 13 that is a cover member that covers the opening of the housing 5. FIG. 11(b) shows the positioning portion 60. The position regulating portion 26c located on the Z direction + side (upper side) is provided on the cover 13 and is not provided integrally with the housing 5. On the other hand, the position regulating portion 16d located on the Z direction - side (lower side) is molded integrally with the housing 5 as in the above-mentioned embodiment. Although not shown in FIG. 11(b), the position regulating portion 50 side is also similarly provided with a position regulating portion (not shown) on the Z direction + side (upper side) on the cover 13, and a position regulating portion (16b in FIG. 4, etc.) on the Z direction - side (lower side) on the housing 5. The other configurations are similar to those of the above-described embodiment, and the same reference numerals are used and the description thereof is omitted.

[0038] (Variation 3) Next, a third modified example of this embodiment is shown in Figs. 12(a), (b) and 13. In the above-described embodiment, the reflecting mirror 11 has three seating surfaces, 15a, 15b and 15c. In the third modified example, the reflecting mirror 11 may have seating surfaces 15e and 15f that have surfaces extending in the short-side direction (direction P) of the reflecting mirror 11, as shown in the perspective views of the housing 5 in Figs. 12(a) and (b). The seating surfaces 15e and 15d abut against the surface 11f of the reflecting mirror 11 in the normal position. The length of the surfaces of the seating surfaces 15e and 15d that extend in the direction P is shorter than the length of the reflecting mirror 11 in the direction P.

[0039] FIG. 13, like FIG. 5(a), shows the state of the positioning unit 60 side when an impact is applied that moves the reflecting mirror 11 in the Z plus direction and in the clockwise direction of the S axis (dotted arrow in the figure). Since the seat surface 15f extends in the short direction of the reflecting mirror 11, as shown in the cross-sectional view of the vicinity of the positioning unit 60 in FIG. 13, it is possible to restrict the reflecting mirror 11 from moving toward the seat surface side from the normal posture in the Q direction when an impact is applied. This can suppress the change in posture of the reflecting mirror 11. The same is true when an impact is applied that moves the reflecting mirror 11 in the Z minus direction and in the counterclockwise direction. The same is also true for the positioning unit 50 side. The other configurations are the same as those of the above-mentioned embodiment, and the same reference numerals are used and the description is omitted. In this way, there are some differences in the way the reflecting mirror 11 moves when an impact is applied in each of the modified examples 1 to 3. However, the movement in which the ridges 11a, 11b, 11c, and 11d of the reflecting mirror 11 do not come into contact with the position restriction portions 16a, 16b, 16c, and 16d is the same, and therefore the effects achieved by the modified examples 1 to 3 described above are the same as those achieved by the embodiment. In this embodiment, the cross-sectional shape of the reflecting mirror 11 when viewed from the longitudinal direction (main scanning direction) is rectangular, but this is not limited to this. For example, the effect of the invention will not change even if the cross-sectional shape is a trapezoid or a polygon with chamfered edges.

[0040] As described above, according to the embodiment, it is possible to reduce deviation in the irradiation position of the laser light caused by a change in the attitude of the reflecting mirror. [Explanation of symbols]

[0041] 11 Reflective mirror 11a, 11b, 11c, 11d Ridgeline 15a, 15b, 15c Seat 16a, 16b, 16c, 16d Position regulation part 50 Positioning part 60 Positioning part

Claims

1. A scanning optical device that scans a scanned object with a laser beam corresponding to image information, A light source; A deflection means for deflecting the laser light emitted from the light source; a reflecting mirror that reflects the laser light deflected by the deflecting means and guides it to a scanned body; a housing for accommodating the deflection means and the reflecting mirror; an elastic member that biases the reflecting mirror toward the housing; Equipped with the reflection mirror has a first surface biased by the elastic member, a second surface opposite to the first surface, a third surface that is a surface that is approximately perpendicular to the first surface and the second surface and parallel to a first direction that is a longitudinal direction of the reflection mirror and is closer to an opening of the housing, and a fourth surface opposite to the third surface, the housing includes a seat surface supporting the second surface, a first restricting portion facing the third surface and restricting movement of the reflection mirror in a second direction that is substantially parallel to the second surface and substantially perpendicular to the first direction, the second direction being toward an opening of the housing, and a second restricting portion facing the fourth surface and restricting movement of the reflection mirror in a direction opposite to the second direction; having the first restricting portion is provided to face only a portion between a first ridge line of the reflecting mirror defined by the first surface and the third surface and a second ridge line of the reflecting mirror defined by the second surface and the third surface, a distance between the first and second restricting portions in the second direction being greater than a length of the reflecting mirror in the second direction;

2. 2. The scanning optical device according to claim 1, wherein the seating surface is provided at two locations on one end side of the reflecting mirror in the first direction and at one location on the other end side of the reflecting mirror.

3. A base surface on which the seat surface is provided, a direction in which the seat surface faces the second surface from the base surface; a ridge line defined by the first surface and the fourth surface is referred to as a third ridge line; a ridge line defined by the second surface and the fourth surface is referred to as a fourth ridge line; a is a distance between the seat surface and the first restriction portion in the second direction; The distance between the seat surface and the second restriction portion in the second direction is b, a protrusion amount of the seat surface from the base surface toward the second surface, c; The width of the reflecting mirror in the second direction is d. When A distance L1 from the first restriction portion to the first ridge line in the third direction is L1≧c×b / (d−b) A distance L2 in the third direction from the first restriction portion to the second ridge line is L2≧c×b / (d−b) A distance L3 from the second restriction portion to the fourth ridge line in the third direction is L3≧c×a / (da) A distance L4 in the third direction from the second restriction portion to the third ridge line is L4≧c×a / (da) 3. The scanning optical device according to claim 2, wherein

4. the housing has a first protruding portion provided near the seating surface in the second direction, and a second protruding portion provided on an opposite side to the first protruding portion across the seating surface in the second direction, The scanning optical device according to claim 3, characterized in that the first protrusion and the second protrusion are provided between the second ridge line and the fourth ridge line, and the amount of protrusion in the third direction is smaller than the amount of protrusion of the seat surface in the third direction.

5. the seat surface is provided on one end side of the reflection mirror in the first direction, The seating surface has a surface extending in the second direction, 3. The scanning optical device according to claim 2, wherein a length of the surface of the seating surface extending in the second direction is smaller than a length of the reflecting mirror in the second direction.

6. the seat surface is provided on the other end side of the reflection mirror in the first direction, The seating surface has a surface extending in the second direction, 6. The scanning optical device according to claim 5, wherein a length of the surface of the seating surface extending in the second direction is smaller than a length of the reflecting mirror in the second direction.

7. The housing has a side to which the light source is attached and a bottom surface to which the deflection means is attached, and the opening is on the side opposite to the bottom surface, A cover member for covering the opening is provided, 7. The scanning optical device according to claim 1, wherein the first restricting portion is provided on the cover member.

8. A photosensitive drum which is the scanned body; 8. The scanning optical device according to claim 1, which forms a latent image on the photosensitive drum; An image forming apparatus comprising:

Images