JP6198875B2 - Optical scanning device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an optical scanning apparatus that scans an object to be scanned with a light beam, and an image forming apparatus including the optical scanning apparatus.

  For example, in an electrophotographic image forming apparatus, the surface of a photoreceptor (scanned body) is uniformly charged, and then the surface of the photoreceptor is scanned with a light beam to form an electrostatic latent image on the surface of the photoreceptor. The electrostatic latent image on the surface of the photoconductor is developed with toner, a toner image is formed on the surface of the photoconductor, and the toner image is transferred from the photoconductor to a recording sheet.

  The photoconductor surface is scanned by the light beam by an optical scanning device. The optical scanning device includes a light emitting element such as a semiconductor laser that emits a light beam, a plurality of mirrors such as a polygon mirror that reflects the light beam, and a plurality of lenses such as an fθ lens that deflects the light beam. The beam is guided to the surface of the photoreceptor by optical members such as mirrors and lenses, and the surface of the photoreceptor is scanned by the light beam to form an electrostatic latent image on the surface of the photoreceptor.

  By the way, in such an optical scanning device, the direction of the surface of the optical member on which the light beam is incident, emitted, or reflected is adjusted with high accuracy, and the optical path of the light beam from the semiconductor laser to the photosensitive member surface is set. doing. However, even if the orientation of the surface of the optical member is adjusted with high accuracy, the orientation of the surface of the optical member is shifted when the main body (housing, frame, etc.) of the optical device to which the optical member is attached expands and contracts due to thermal expansion. In some cases, the incident position of the light beam on the surface of the photosensitive member is significantly shifted. For example, in a configuration in which a holding member holding an optical member is supported by being placed on the housing of the optical device and the direction of the light incident surface of the optical member is adjusted and set on the holding member, the position of the holding member may be fixed. When the housing of the optical device is thermally expanded, the position of the holding member is displaced, and the direction of the surface of the optical member is changed, thereby changing the direction of the light beam, and the incident position of the light beam on the surface of the photoconductor Was significantly out of alignment.

  For this reason, in Patent Document 1, the holding member is supported on the base so as to be displaceable by merely pressing a plurality of locations of the holding member of the optical member against the base by the respective leaf springs, and the holding member is not fixed. In this case, even if the base is thermally expanded, the holding member is not displaced following the base, the direction of the surface of the optical member is difficult to change, and the direction of the light beam is also difficult to change.

  In Patent Document 2, although the heat sink is not an optical member, the substrate bends due to thermal expansion of the heat sink. Therefore, the heat sink is attached to the substrate using spring-like screws, and the expansion and contraction of the heat sink due to thermal expansion is reduced. Absorbs with spring-like screws.

JP 2006-251517 A JP 05-321914 A

  However, in Patent Documents 1 and 2, since the optical member and the heat sink are attached using only a leaf spring and a spring-like screw, the optical member and the heat sink cannot be reliably positioned. In particular, in the case of an optical member, if the direction of the surface of the optical member is deviated, the incident position of the light beam on the surface of the photosensitive member is greatly deviated, so that it is not preferable to attach the optical member only by the leaf spring. For example, when the vibration accompanying the rotational drive of the polygon mirror or the vibration from the outside acts on the optical member, the optical member vibrates even if the optical member is pressed by a leaf spring or a spring-like screw. The direction of the surface gradually shifts.

  Therefore, the present invention has been made in view of the above-described conventional problems, and even if the apparatus main body expands or contracts due to thermal expansion or vibration acts on the optical member, the direction of the surface of the optical member is shifted. An object of the present invention is to provide an optical scanning device having no image and an image forming apparatus including the same.

An optical scanning device according to the present invention is an optical scanning device in which an optical member disposed on an optical path of a light beam from a light emitting element to a scanned object is held by a holding member, and the holding member is attached to the apparatus main body. A fastening member for fixing the fixing part of the holding member to the apparatus main body, and a first pressing member for pressing the first support part of the holding member against the apparatus main body and supporting the first support part displaceably The optical member held by the holding member is one of a plurality of optical members arranged on the optical path of the light beam, and is a mirror or a lens.

In the optical scanning device according to the present invention, the first pressing member may include an elastic member having elasticity and a washer that presses the elastic member.

In the optical scanning device according to the present invention, the optical member may be supported by a screw member that changes the orientation of the surface of the optical member and a convex portion provided on the holding member.

An image forming apparatus according to the present invention includes the optical scanning device according to the present invention, forms a latent image on a scanned object by the optical scanning device, and develops the latent image on the scanned object into a visible image. The visible image is transferred from the scanned body to a sheet.

  In the present invention, the fixing member fixing part is fixed to the apparatus main body by the fastening member, and the first supporting part of the holding member is pressed against the apparatus main body by the first pressing member so as to be displaceable. Therefore, two places of the holding member are supported, and the holding member and the optical member can be stably supported. Further, since the fixing member fixing portion is fixed to the apparatus main body by the fastening member, the holding member can be reliably positioned, and even if vibration acts on the holding member and the optical member, the position of the holding member is shifted. The surface orientation of the optical member can be maintained. Further, since the first support portion of the holding member is pressed against the apparatus main body by the first pressing member so as to be displaceable, even if the apparatus main body expands and contracts due to thermal expansion, the first support portion of the holding member becomes the device. The positional relationship between the holding part of the holding member and the first support part is maintained without being displaced following the main body, and distortion of the holding member due to expansion and contraction of the apparatus main body and displacement of the fixing part can be suppressed. For this reason, the direction of the surface of the optical member held by the holding member does not change, the direction of the light beam does not change, and the incident position of the light beam on the scanned object does not shift.

1 is a cross-sectional view illustrating an image forming apparatus including an embodiment of an optical scanning device of the present invention. It is a perspective view which shows the principal part of the optical scanning apparatus in the state which removed the upper cover. 1 is a perspective view schematically showing an optical system of an optical scanning device. It is a perspective view which shows the support structure of the intermediate | middle mirror of an optical scanning device. It is a top view which shows the support structure of an intermediate | middle mirror. It is sectional drawing which follows AA of FIG. It is a perspective view which shows the holding member of an optical scanning device. It is a perspective view which shows the holding member attachment area | region vicinity of the base | substrate of the housing | casing of an optical scanning device. It is a perspective view which shows the elastic support frame of an optical scanning device. It is a perspective view which shows the side wall of an optical scanning device seeing from the back side.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a sectional view showing an image forming apparatus to which an embodiment of an optical scanning device of the present invention is applied. The image forming apparatus 1 forms a monochrome image on a recording sheet. The configuration of the image forming apparatus 1 is roughly divided into a document sheet conveying unit (ADF) 11, an image reading unit 12, a printing unit 13, a recording sheet conveying unit 14, and the like. And a sheet feeder 15 and the like.

  The original paper transport unit 11 pulls out original paper one by one from the original set tray 21 and transports it through the original transport path 22, and discharges the original paper onto the paper discharge tray 23.

  The image reading unit 12 illuminates the surface of the original paper by the light source of the first scanning unit 24 while conveying the original paper, and condenses the reflected light from the surface of the original paper by the mirrors of the first and second scanning units 24 and 25. The image is guided to the image lens 26, and an image on the surface of the original paper is formed on a CCD (Charge Coupled Device) 27 by the imaging lens 26. The CCD 27 repeatedly reads an image on the surface of the original paper in the main scanning direction, and outputs image data indicating the image on the surface of the original paper. A CIS 28 (Contact Image Sensor) illuminates the back side of the original paper while the original paper is being transported, repeatedly reads the image on the back side of the original paper in the main scanning direction, and outputs image data indicating the image on the back side of the original paper. .

  When the original paper is placed on the platen glass 29 on the upper surface of the image reading unit 12, the first and second scanning units 24 and 25 are moved while maintaining a predetermined speed relationship with each other. The light source 24 illuminates the surface of the original paper on the platen glass 29, the reflected light from the original paper surface is guided to the imaging lens 26 by the mirrors of the first and second scanning units 24, 25, and the imaging lens 26 An image on the surface of the original paper is formed on the CCD 27.

The image data output from the CCD 27 and the CIS 28 is subjected to various image processing by a control circuit such as a microcomputer and then output to the printing unit 13.

Next, the printing unit 13 records a document indicated by the image data on a sheet, and includes a photosensitive drum 31, a charging device 32, an optical scanning device 33, a developing device 34, a transfer device 35, a cleaning device 36, And a fixing device 37 and the like.

  The photosensitive drum 31 rotates in one direction. After the surface is cleaned by the cleaning device 36, the surface is uniformly charged by the charging device 32. The optical scanning device 33 inputs image data, modulates a light beam (laser light) in accordance with the image data, irradiates the photosensitive drum 31 with this light beam, and electrostatic latent image on the surface of the photosensitive drum 31. Form an image. The developing device 34 supplies toner to the surface of the photosensitive drum 31 to develop the electrostatic latent image, and forms a toner image on the surface of the photosensitive drum 31. The transfer device 35 transfers the toner image on the surface of the photosensitive drum 31 onto the recording paper conveyed by the recording paper conveyance unit 14. The fixing device 37 heats and pressurizes the recording paper to fix the toner image on the recording paper. Thereafter, the recording paper is further conveyed to the paper discharge tray 38 and discharged.

  The recording paper conveyance unit 14 includes a plurality of conveyance rollers 41 for conveying the recording paper, a registration roller 42, a conveyance path 43, a paper discharge roller 46, and the like. After the leading end of the sheet is brought into contact with the registration roller 42 and aligned, the recording sheet is conveyed to the transfer device 35 of the printing unit 13, and the recording sheet is further conveyed to the sheet discharge tray 38 by the sheet discharge roller 46.

  The paper feed unit 15 includes a plurality of paper feed trays 51. Each paper feed tray 51 is a tray for accumulating recording paper, and the recording paper is pulled out one by one by a pickup roller 52 and sent out to the conveyance path 43 of the recording paper conveyance unit 14.

  Next, the configuration of the optical scanning device 33 according to the present embodiment will be described in detail with reference to FIGS. FIG. 2 is a perspective view showing a main part of the optical scanning device 33 with the upper lid removed. FIG. 3 is a perspective view schematically showing an optical system of the optical scanning device 33. In FIG. 3, the optical system is shown as viewed from the back side of FIG.

  As shown in FIG. 2, the housing 53 of the optical scanning device 33 is made of synthetic resin, and includes a semiconductor laser 101, a polygon mirror 102, a collimator lens 103, a concave lens 104, a cylindrical lens 105, and an intermediate. A mirror 106, a first fθ lens 107, a second fθ lens 108, an output folding mirror 109, and the like are disposed.

  As shown in FIG. 3, in the optical scanning device 33, the light beam BM emitted from the semiconductor laser 101 is guided to the reflection surface of the polygon mirror 102 that is rotationally driven in the direction of the arrow by a mirror, a lens or the like, and the light beam BM is emitted. The light beam BM is reflected and deflected by the reflecting surface of the polygon mirror 102, and the reflected light beam BM is guided to the photosensitive drum 31 by a mirror or a lens. The surface of the photosensitive drum 31 is moved in the main scanning direction Y by the light beam BM. Repeated scanning.

  In the optical path from the semiconductor laser 101 to the polygon mirror 102, optical members such as a collimator lens 103, a concave lens 104, a cylindrical lens 105, and an intermediate mirror 106 are arranged in the order from the semiconductor laser 101 to the polygon mirror 102.

  The collimator lens 103 converts the light beam BM emitted from the semiconductor laser 101 into parallel light. The concave lens 104 diffuses the light beam BM once converted into parallel light. The cylindrical lens 105 converges the light beam BM again in the sub-scanning direction X, and emits the light beam BM as diffuse light as it is in the main scanning direction Y orthogonal to the sub-scanning direction X. The intermediate mirror 106 reflects the light beam BM from the cylindrical lens 105 and makes it incident on the polygon mirror 102. As a result, in the main scanning direction, the irradiation region of the light beam BM on one reflecting surface of the polygon mirror 102 is slightly larger than the one reflecting surface (referred to as overfilled).

  Next, in the optical path from the polygon mirror 102 to the photosensitive drum 31, optical members such as the first fθ lens 107, the second fθ lens 108, and the output folding mirror 109 are arranged in the order from the polygon mirror 102 to the photosensitive drum 31. Is arranged.

  The first fθ lens 107 converts the light beam BM reflected by the polygon mirror 102 in the sub-scanning direction X into parallel light, and converts the parallel light beam BM reflected by the polygon mirror 102 in the main scanning direction Y into the photosensitive drum. The light is condensed and emitted so as to have a predetermined beam diameter on the surface of 31. The first fθ lens 107 moves the light beam BM deflected at a constant angular velocity in the main scanning direction Y by the constant angular velocity movement of the polygon mirror 102 on the main scanning line on the photosensitive drum 31 at a constant linear velocity. Convert.

  The second fθ lens 108 condenses the light beam BM, which has been collimated by the first fθ lens 107 in the sub-scanning direction X, on the photosensitive drum 31 so as to have a predetermined beam diameter, and the first fθ in the main scanning direction Y. The light beam BM that has been converged by the lens 107 is directly incident on the photosensitive drum 31.

  The exit folding mirror 109 reflects the light beam BM transmitted through the second fθ lens 108 and causes the light beam BM to enter the photosensitive drum 31 through the slit 53 b (shown in FIG. 2) of the base 53 a of the housing 53. As a result, a spot of the light beam BM is formed on the surface of the photosensitive drum 31, and the surface of the photosensitive drum 31 is main-scanned by the light beam BM.

  The light beam BM reflected by the polygon mirror 102 is reflected by the detection mirror 111 and enters the BD sensor 112 immediately before the main scanning of the photosensitive drum 31 by the light beam BM is started. The BD sensor 112 receives the light beam BM at a timing immediately before the main scanning of the photosensitive drum 31 is started, and outputs a BD signal indicating the timing immediately before the main scanning is started. The start timing of the main scanning of the photosensitive drum 31 by the light beam BM is determined according to the BD signal, and the modulation of the light beam BM according to the image data is started.

   As described above, in the optical scanning device 33, the light beam BM is reflected and deflected by the reflecting surface of the polygon mirror 102, enters the photosensitive drum 31, and the surface of the photosensitive drum 31 is repeatedly main-scanned by the light beam BM. The On the other hand, since the photosensitive drum 31 is rotationally driven, the two-dimensional surface (circumferential surface) of the photosensitive drum 31 is scanned by the light beam BM, and an electrostatic latent image is formed on the surface of the photosensitive drum 31. .

  By the way, in such an optical scanning device 33, the direction of the entrance surface or exit surface of each of the lenses 103 to 105, 107, and 108 and the reflection surface of the mirrors 102, 106, and 109 is adjusted with high precision, so that the semiconductor laser 101 The optical path of the light beam BM to the surface of the photosensitive drum 31 is set.

  However, even if the direction of the surface of the lens or mirror is adjusted with high accuracy, the expansion / contraction of the casing 53 due to thermal expansion, the vibration of the motor that rotationally drives the polygon mirror 102, and the various motors of the image forming apparatus 1 are assumed. If the direction of the surface of the lens or mirror attached to the casing 53 is deviated due to the cause, the incident position of the light beam on the surface of the photosensitive drum 31 is greatly shifted. In particular, with respect to the intermediate mirror 106, if the direction of the reflection surface of the intermediate mirror 106 changes even slightly, the incident position with respect to the reflection surface of the polygon mirror 102 is greatly shifted, and the optical path from the polygon mirror 102 to the photosensitive drum 31 is also greatly increased. As a result, the incident position of the light beam BM on the surface of the photosensitive drum 31 is significantly shifted.

  Therefore, in the optical scanning device 33 according to the present embodiment, even if the housing 53 expands or contracts due to thermal expansion, vibrations of a motor that rotates the polygon mirror 102 and various motors of the image forming apparatus 1 act on the intermediate mirror 106. Even so, the intermediate mirror 106 is supported on the base 53a of the housing 53 so that the direction of the reflecting surface of the intermediate mirror 106 does not change.

  Next, the support structure for the intermediate mirror 106 will be described in detail. 4 and 5 are a perspective view and a plan view showing a support structure of the intermediate mirror 106. FIG. 6 is a cross-sectional view taken along the line AA in FIG. As shown in FIGS. 4 and 5, a holding member 121 is attached to the base 53 a of the housing 53, an elastic support frame 122 is fixed on the holding member 121, and the intermediate mirror 106 is supported by the elastic support frame 122. ing. Note that the virtual straight line D shown in FIG. 5 is a line substantially parallel to the reflecting surface of the intermediate mirror 106 when viewed from the vertical direction with respect to the base 53a.

  FIG. 7 is a perspective view showing the holding member 121. As shown in FIG. 7, the holding member 121 is a metal plate bent in an L shape, and includes a bottom plate 121a and a standing plate 121b. The bottom plate 121a is formed with a fixing hole 121c, a long guide hole 121d, a screw hole 121e, two rectangular holes 121f, and four protrusions 121g. Further, the standing plate 121b is formed with two screw holes 121h arranged on a rectangular diagonal line of the standing plate 121b, and a convex portion 121i disposed above one screw hole 121h.

FIG. 8 is a perspective view showing the vicinity of the region of the base 53a to which the holding member 121 is attached. As shown in FIG. 8, the base 53a is provided with a low boss 53c and a high boss 53d, and spacer ribs 53e and 53f are formed around the low boss 53c and the high boss 53d, respectively. A character-shaped frame portion 53g and spacer-like ribs 53h are formed. A straight line connecting the low boss 53c and the high boss 53d is substantially parallel to the virtual straight line D (the reflection surface of the intermediate mirror 106), and the upper surfaces of the spacer-like ribs 53e, 53f, 53h are the same height.

  Further, a side wall 53i is erected at one end of the base 53a, and two columnar protrusions 53j protrude from the base 53a near the side wall 53i. Further, two adjustment holes 53k are formed in the side wall 53i.

  As shown in FIGS. 4 to 5, the low boss 53c and the high boss 53d of the base 53a are inserted into the fixing holes 121c and the long guide holes 121d of the bottom plate 121a of the holding member 121, and the columnar protrusions 53j of the base 53a are inserted into the bottom plate 121a. The bottom plate 121a is positioned, and the bottom plate 121a is stably placed on the upper surfaces of the spacer-like ribs 53e, 53f, and 53h.

  The inner diameter of the fixing hole 121c of the bottom plate 121a of the holding member 121 is slightly larger than the outer diameter of the lower boss 53c of the base 53a, and the lower boss 53c is inserted into the fixing hole 121c of the bottom plate 121a without rattling. Further, the height of the low boss 53c from the upper surface of the spacer-like rib 53e is substantially the same as the thickness of the bottom plate 121a, and the bottom plate 121a is sandwiched between the screw 123 screwed into the low boss 53c and the spacer-like rib 53e. Tightened. Thereby, the part of the fixing hole 121c of the bottom plate 121a is fixed on the spacer-like rib 53e.

  Further, the short diameter of the long guide hole 121d of the bottom plate 121a of the holding member 121 is slightly larger than the outer diameter of the high boss 53d of the base 53a, and the long diameter of the long guide hole 121d is sufficiently larger than the outer diameter of the boss 53d. And extends in a direction substantially parallel to the virtual straight line D (the reflection surface of the intermediate mirror 106). In the direction orthogonal to the imaginary straight line D, the high boss 53d is sandwiched without rattling on the short diameter side of the long guide hole 121d of the bottom plate 121a, and in the direction parallel to the imaginary straight line D, the length of the bottom plate 121a is long. The part of the shape guide hole 121d can be displaced. The coil spring 124 is inserted into the high boss 53d, the washer 126 is passed through the screw 125, the screw 125 is screwed into the high boss 53d, and the coil spring 124 is shortened and sandwiched between the bottom plate 121a and the washer 126. 121a is pressed against and supported by the spacer-like rib 53f. As a result, on the spacer-like rib 53f, the portion of the long guide hole 121d of the bottom plate 121a is fixed in a direction orthogonal to the virtual straight line D with respect to the base 53a and is supported so as to be displaceable in a direction parallel to the virtual straight line D. Is done.

  Further, one end 121j of the bottom plate 121a of the holding member 121 is disposed slightly apart from the frame portion 53g of the base 53a, the bottom plate 121a is placed on the spacer-like rib 53h, and one end of the leaf spring 127 is fitted inside the frame portion 53g. The other end of the leaf spring 127 is placed on the one end 121j of the bottom plate 121a, and the screw 128 is screwed into the frame 53g through the hole of the leaf spring 127 and tightened to deform the leaf spring 127, and the leaf spring 127 is attached. One end 121j of the bottom plate 121a is pressed against and supported by the spacer-shaped rib 53h by the force. Thereby, on the spacer-like rib 53h, one end 121j of the bottom plate 121a is supported so as to be displaceable in any direction of 360 ° around the axis of the screw 128 with respect to the base 53a.

  Accordingly, the portion of the fixing hole 121c of the bottom plate 121a of the holding member 121 is fixed to the base 53a, and the portion of the long guide hole 121d of the bottom plate 121a is fixed to the base 53a in a direction orthogonal to the virtual straight line D and the virtual straight line D is supported to be displaceable in a direction parallel to D, and one end 121j of the bottom plate 121a is supported to be displaceable in any direction of 360 ° with respect to the base 53a. The bosses 53c and 53d and the frame portion 53g are at the positions of the vertices of the isosceles triangle, and the line segment connecting the bosses 53c and 53d corresponds to the base of the isosceles triangle. For this reason, the bottom plate 121a of the holding member 121 is supported at three locations, and the holding member 121 and the intermediate mirror 106 are stably supported. Further, the pressing force by which the bottom plate 121a is pressed against the spacer-shaped rib 53f by the coil spring 124 is made smaller than the pressing force by which the bottom plate 121a is pressed by the spacer-shaped rib 53h by the plate spring 127, and the end 121j of the bottom plate 121a is moved by the plate spring 127. It is supported more stably, and the portion of the long guide hole 121d of the bottom plate 121a is supported by the coil spring 124 so as to be easily moved.

  FIG. 9 is a perspective view showing the elastic support frame 122 with the intermediate mirror 106 removed. As shown in FIG. 9, the elastic support frame 122 is formed by punching a thin metal plate and bending it. The bottom plate 122a, the column portion 122b bent at the center of one end of the bottom plate 122a, and bent at the upper end of the column portion 122b. Each of the holding claw portions 122d is bent at both ends of the presser portion 122c and the bottom plate 122a. A circular hole 122e and an elongated hole 122f are formed in the bottom plate 122a.

  As shown in FIGS. 4 to 6, the circular holes 122 e and the elongated holes 122 f of the bottom plate 122 a of the elastic support frame 122 are fitted into the protrusions 121 g of the bottom plate 121 a of the holding member 121, and screws 131 are inserted into the bottom plate 122 a of the elastic support frame 122. The elastic support frame 122 is positioned and fixed on the bottom plate 121a of the holding member 121 by being screwed into the screw holes 121e of the bottom plate 121a of the holding member 121 through the perforations (not shown).

  The intermediate mirror 106 is inserted and sandwiched between the column portion 122b of the elastic support frame 122 and each gripping claw portion 122d. At the same time, the lower end of the intermediate mirror 106 is placed on the projections 121g of the bottom plate 121a of the holding member 121, and the upper end of the intermediate mirror 106 is pressed by the pressing portion 122c of the elastic support frame 122 to hold the upper and lower sides of the intermediate mirror 106. ing. Further, the intermediate mirror 106 is disposed between the columnar protrusions 53j.

  Further, as shown in FIG. 5, the back surface of the intermediate mirror 106 is brought into contact with the convex portion 121 i of the standing plate 121 b of the holding member 121, and the worm screw 132 is inserted into each screw hole 121 h of the standing plate 121 b of the holding member 121. And the tip of each bug screw 132 is brought into contact with the back surface of the intermediate mirror 106, and the back surface of the intermediate mirror 106 is supported at three points by the convex portion 121i and the tip of each bug screw 132. The direction is set.

  Here, since the elastic support frame 122 has elasticity and play is provided between the intermediate mirror 106 and each columnar protrusion 53j, the elastic support frame 122 is elastically deformed, and the direction of the reflecting surface of the intermediate mirror 106 is changed. It is possible to change. Specifically, as shown in FIG. 10, each worm screw 132 is rotated by a screwdriver through each adjustment hole 53 k on the side wall 53 i of the housing 53 to change the protruding length of the tip of each worm screw 132. The extrusion length of the back surface of the intermediate mirror 106 by the tip of 132 is changed. As a result, the back surface of the intermediate mirror 106 rotates in any direction around the contact position of the convex portion 121i of the standing plate 121b, and the reflection surface of the intermediate mirror 106 swings up and down, changing the direction of the reflection surface. . For example, when the protruding length of the tip of the worm screw 132 screwed into the screw hole 121h below the convex portion 121i of the standing plate 121b is changed, the back surface of the intermediate mirror 106 is generally vertically moved around the contact position of the convex portion 121i. Rotating in the direction, the reflecting surface of the intermediate mirror 106 is roughly undulated. Further, when the projecting length of the tip of the bug screw 132 screwed into the screw hole 121h in the lateral direction of the convex portion 121i of the standing plate 121b is changed, the back surface of the intermediate mirror 106 is generally centered on the contact position of the convex portion 121i. By rotating in the left-right direction, the reflecting surface of the intermediate mirror 106 is generally turned.

  By adjusting the direction of the reflecting surface of the intermediate mirror 106 in this way, an optical path from the intermediate mirror 106 to the photosensitive drum 31 via the polygon mirror 102 is appropriately set, and the light beam BM on the surface of the photosensitive drum 31 is set. Set the incident position.

  On the other hand, the casing 53 and the base 53a are made of synthetic resin, and the holding member 121 is made of metal. Generally, since the thermal expansion coefficient of the synthetic resin is much larger than that of the metal, the base 53a is held by thermal expansion. It expands and contracts larger than the member 121. In addition, vibrations of a motor that rotates the polygon mirror 102 and various motors of the image forming apparatus 1 are transmitted to the holding member 121 and the intermediate mirror 106 through the base 53a. Therefore, there is a cause of the orientation of the reflection surface of the intermediate mirror 106 being deviated.

  However, in the optical scanning device 33 of the present embodiment, since the portion of the fixing hole 121c of the holding member 121 is fixed to the base 53a by the screw 123, even if the vibrations of various motors are transmitted to the holding member 121 through the base 53a. The position of the holding member 121 is not displaced, and the orientation of the reflecting surface of the intermediate mirror 106 can be maintained. A portion of the long guide hole 121d of the bottom plate 121a is fixed to the base 53a in a direction orthogonal to the virtual straight line D and supported so as to be displaceable in a direction parallel to the virtual straight line D, and one end 121j of the bottom plate 121a is supported by the base Since the base 53a is expanded and contracted due to thermal expansion, the long guide hole 121d of the bottom plate 121a and the one end 121j of the bottom plate 121a follow the base 53a. Thus, the positional relationship between the long guide hole 121d and the one end 121j with respect to the fixing hole 121c of the bottom plate 121a is maintained, the holding member 121 is not distorted, and the displacement of the fixing hole 121c is suppressed. The orientation of the reflecting surface of the intermediate mirror 106 can be maintained. That is, even if the vibrations of various motors are transmitted to the holding member 121 through the base 53a or the base 53a expands or contracts due to thermal expansion, the direction of the reflecting surface of the intermediate mirror 106 held by the holding member 121 changes. In addition, the direction of the light beam BM does not change, and the incident position of the light beam on the surface of the photosensitive drum 31 does not shift.

  Further, since the portion of the long guide hole 121d of the bottom plate 121a is supported so as to be displaceable in a direction parallel to the virtual straight line D with respect to the base 53a, the displacement of the long guide hole 121d with respect to the base 53a causes the intermediate mirror 106 to move. The force in the direction of rotating the reflecting surface does not act on the holding member 121, and the orientation of the reflecting surface of the intermediate mirror 106 is kept constant.

  In particular, in the optical scanning device 33 of the present embodiment, in the main scanning direction, an overfilling is applied in which the irradiation area of the light beam BM on one reflecting surface of the polygon mirror 102 is made larger than the one reflecting surface. It is necessary to maintain the position of the optical path of the light beam BM with high accuracy, and it is meaningful to maintain the orientation of the reflecting surface of the intermediate mirror 106 without being affected by the thermal expansion of the base 53a.

  Further, the pressing force by the coil spring 124 is made smaller than the pressing force by the leaf spring 127, and the portion of the long guide hole 121d of the bottom plate 121a is supported by the coil spring 124 in a state where it can be moved more easily. The stretchable length of 53a can be easily released in a direction parallel to the reflecting surface of the intermediate mirror 106, and the distortion of the holding member 121 and the displacement of the fixing hole 121c can be more effectively prevented.

  Further, the bosses 53c and 53d and the frame portion 53g are at the positions of the vertices of the isosceles triangle, the line segment connecting the bosses 53c and 53d corresponds to the base of the isosceles triangle, and between the bosses 53c and 53d. Since the intermediate mirror 106 is disposed, the optical path of the light beam BM incident and reflected on the intermediate mirror 106 passes above the frame portion 53g, but the leaf spring 127 fixed to the frame portion 53g. Accordingly, the one end 121j of the bottom plate 121a is pressed, and the height of the leaf spring 127 is low, so that the leaf spring 127 does not block the optical path of the light beam BM.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. It is understood.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Document paper conveyance part (ADF)
12 Image reading unit 13 Printing unit 14 Recording paper transport unit 15 Paper feeding unit 31 Photosensitive drum (scanned body)
32 Charging device 33 Optical scanning device 34 Developing device 35 Transfer device 36 Cleaning device 37 Fixing device 53 Case (device main body)
101 Semiconductor Laser 102 Polygon Mirror 103 Collimator Lens 104 Concave Lens 105 Cylindrical Lens 106 Intermediate Mirror (Optical Member)
107 First fθ lens 108 Second fθ lens 109 Output folding mirror 121 Holding member 121c Fixing hole (fixed part)
121d Long guide hole (first support part, guide part)
121j One end (second support part)
122 Elastic support frame (elastic support member)
123 Screw (fastening member)
125, 128, 131 Screw 124 Coil spring (first pressing member)
126 Washer 127 Leaf spring (second pressing member)
132 Bug screw (screw member)

Claims (5)

An optical scanning device in which an optical member disposed on an optical path of a light beam from a light emitting element to a scanned object is held by a holding member, and the holding member is attached to an apparatus main body,
A fastening member for fixing the fixing portion of the holding member to the apparatus main body;
A first pressing member that presses the first support part of the holding member against the apparatus main body and supports the first support part in a displaceable manner;
The optical member held by the holding member is one of a plurality of optical members arranged on the optical path of the light beam, and is a mirror or a lens . Two screw members, and the holding member Supported by the provided convex part,
The two screw members are arranged at a position on a diagonal diagonal with respect to the surface of the optical member, and the convex portions are arranged at different corners from the two screw members,
The optical scanning device according to claim 1, wherein the optical member changes the direction of the surface in a different direction by changing a protruding length of the two screw members . The optical scanning device according to claim 1,
The optical scanner according to claim 1, wherein the first pressing member includes an elastic member having elasticity and a washer that presses the elastic member. The optical scanning device according to claim 1 or 2,
The holding member is provided with a hole opened in a surface facing the apparatus main body,
The apparatus main body is provided with a columnar protrusion provided at a position facing the hole,
The columnar protrusion is inserted through the hole to position the holding member.
An optical scanning device characterized by the above. An optical scanning device according to any one of claims 1 to 3, wherein
The apparatus body is provided with an adjustment hole that opens to face the screw member.
An optical scanning device characterized by the above. A light scanning device according to claim 1 is provided, a latent image is formed on a scanned object by the light scanning device, and the latent image on the scanned material is a visible image. An image forming apparatus that develops the visible image and transfers the visible image from the scanned body onto a sheet.

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