JP2008102186A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and quickly carry out skew adjustment of a mirror member without increasing a cost in an image forming apparatus using an electrophotographic system. <P>SOLUTION: After mounting a housing 50 of a laser scan unit on a frame or the like of an apparatus main body, a positioning screw 54 is rotated from the outside of the housing 50 (that is, from the upside of the apparatus main body). This allows a mirror angle adjusting member 52 to advance or retreat, and each contact point of the mirror member 38 with a mirror contact portion 52a and with a mirror pressing portion 53b is moved to adjust the angle of the mirror member 38 with respect to the housing 50. Thus, skew adjustment of the mirror member 38 can be quickly carried out while the housing 50 is mounted on the frame or the like. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a laser scan unit that forms a latent image by irradiating a surface of a photosensitive drum with a laser beam while scanning.

  In an image forming apparatus using electrophotographic technology such as a laser beam printer, it is necessary to emit a laser beam from a laser scan unit at an accurate angle with respect to a photosensitive drum in order to form an appropriate image. The laser beam is reflected by a mirror member provided in the laser scan unit and emitted from the laser scan unit. For this reason, the laser scan unit is provided with a mirror angle adjustment mechanism for adjusting the angle of the mirror member.

For example, Patent Document 1 discloses an image forming apparatus configured such that the angle of a mirror member can be adjusted by a feed screw and an elastic member. Patent Document 2 discloses an image forming apparatus including a mirror adjustment unit provided with an optical box, a mirror adjustment unit, a support side spring, a movable side spring, a plurality of screws, and the like. Patent Document 3 discloses an image forming apparatus in which an angle of a mirror member can be adjusted by an elastic member and a screw arranged with the mirror member interposed therebetween.
JP 2004-109658 A JP 2003-287700 A JP 2001-100135 A

  By the way, the components constituting the optical system of the laser beam printer have a dimensional error within a tolerance range for each component, and when the error of each component is accumulated, the angle of the laser beam is changed. There is a case where it becomes difficult to form an image normally. Therefore, it is desirable that the mounting angle of the mirror member in the laser scan unit can be adjusted after the laser scan unit is mounted on the apparatus main body. In general, the laser beam emitting portion is provided so that the laser beam is emitted from the back side of the laser scan unit. The laser beam emitting portion is disposed toward the photosensitive drum (usually, the photosensitive drum is disposed substantially at the center of the apparatus, so the laser beam emitting portion is disposed toward the inside of the apparatus. Therefore, in particular, at the manufacturing site of the image forming apparatus, there is a demand for a configuration in which the angle of the mirror member can be adjusted from the back side opposite to the laser beam emitting portion on the bottom surface of the housing of the laser scan unit. ing.

  However, in any of the image forming apparatuses having the mirror angle adjusting mechanism described in any of the above-mentioned patent documents, after mounting the laser scan unit on the apparatus main body, the laser scan unit is not detached from the apparatus main body, Since the angle of the member cannot be adjusted, a process for attaching and detaching the laser scan unit is separately required, resulting in deterioration of productivity.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can easily and quickly adjust a skew of a mirror member without increasing the cost.

The invention according to claim 1
A photoreceptor drum having a photoreceptor coated on the surface;
Charging means for uniformly charging the surface of the photosensitive drum;
Exposure means for forming a latent image by irradiating the surface of the photoconductor while scanning with a laser beam;
Developing means for forming a toner image by attaching toner to a portion of the surface of the photoreceptor where a latent image is formed;
A toner image formed on the surface of the photosensitive drum is recorded at a predetermined transfer position downstream of the developing unit in the rotational direction of the photosensitive drum so as to face the surface of the photosensitive drum. Transfer means for transferring onto paper,
Fixing means for fixing the toner image on the recording paper by applying predetermined heat and pressure to the recording paper on which the toner image has been transferred,
The exposure means includes a laser diode that emits a laser beam, a collimator lens that collimates the laser beam emitted from the laser diode, and a cylinder that focuses the laser beam collimated by the collimator lens only in the main scanning direction. A lens, a polygon mirror that reflects the laser beam focused only in the main scanning direction by the cylinder lens so as to scan in the main scanning direction, an fθ lens that transmits the laser beam reflected by the polygon mirror, and the fθ A mirror member that reflects the laser beam transmitted through the lens toward the surface of the photosensitive drum, a box-shaped housing made of a resin molded product in which these components are incorporated, and an attachment angle of the mirror member to the housing is adjusted. Mirror angle adjustment mechanism In the image forming apparatus to
The mirror angle adjustment mechanism is attached to the housing so that a part of the mirror angle adjustment mechanism is exposed to the outside of the housing behind the mirror member, and abuts against the rear end of the mirror member to attach the mirror member to the housing. A mirror angle adjusting member for adjusting the angle; biasing means for biasing the mirror member toward the mirror angle adjusting member; and a positioning screw for positioning the mirror angle adjusting member on the housing;
The urging means has a base end portion mounted on the housing by a spring mounting screw outside the housing, and at the tip end portion the mirror member is in a direction parallel to the optical axis of the fθ lens and the fθ. It has a mirror pressing part that presses in the opposite direction to the lens,
The housing has an insertion hole through which the front end side of the biasing means is inserted into the housing, and the mirror angle adjustment member is advanced in a direction parallel to the optical axis of the fθ lens. The apparatus main body in an inverted posture with a guide projection for guiding the mirror angle adjusting member and a screw insertion portion for inserting the positioning screw on the back side of the bottom surface when the mirror angle adjustment member is retracted, with the top and bottom reversed. Mounted on
The mirror angle adjustment member is formed by bending a metal plate-like member, and includes a mirror contact portion that contacts the mirror member, a groove portion that engages with the guide protrusion, and the positioning screw. A screw threaded portion to be threaded;
After the housing is mounted on the apparatus main body, the positioning screw is rotated to move the mirror angle adjustment member forward or backward in a direction parallel to the optical axis of the fθ lens. The contact portion and the contact portion with the mirror pressing portion move, thereby enabling the skew adjustment of the mirror member, and fixing the mirror member to the housing so as to be at an optimum angle with respect to the photosensitive drum. It is possible.

The invention according to claim 2
A photoreceptor drum having a photoreceptor coated on the surface;
An image forming apparatus comprising: an exposure unit configured to form a latent image by irradiating the surface of the photoconductor with a laser beam;
The exposure means transmits a laser diode that emits a laser beam, a polygon mirror that reflects the laser beam emitted from the laser diode so as to scan in the main scanning direction, and a laser beam reflected by the polygon mirror. An fθ lens, a mirror member that reflects the laser beam transmitted through the fθ lens toward the surface of the photosensitive drum, a housing in which these components are incorporated, and a mirror angle adjustment member that adjusts the angle of the mirror member Biasing means for biasing the mirror member toward the mirror angle adjustment member, and a positioning screw for positioning the mirror angle adjustment member on the housing,
The mirror angle adjusting member has a mirror abutting portion that abuts on the mirror member and a screw threaded portion into which the positioning screw is threaded.
By rotating the positioning screw to advance or retract the mirror angle adjustment member in a direction parallel to the optical axis of the fθ lens, the contact portion between the mirror member and the mirror contact portion and the mirror pressing portion is Each of them moves, thereby making it possible to adjust the skew of the mirror member.

The invention according to claim 3 is the image forming apparatus according to claim 2,
The housing has a screw insertion portion for inserting the positioning screw on the back side of the bottom surface, and is mounted on the apparatus main body in an inverted posture with the top and bottom reversed.
After the housing is mounted on the apparatus main body, the mirror member can be fixed to the housing at an optimum angle with respect to the photosensitive drum by rotating the positioning screw.

  According to the first aspect of the present invention, the contact portion between the back surface of the mirror member and the mirror contact portion moves by moving the mirror angle adjustment member back and forth. As a result, the skew adjustment of the mirror member can be performed easily and quickly. In addition, since the screw insertion portion into which the positioning screw is screwed is provided in the mirror angle adjusting member, the operator can move the mirror angle adjusting member forward or backward by simply rotating the positioning screw. The work can be performed quickly and the productivity of the image forming apparatus can be improved. Furthermore, since the housing of the exposure means has a screw insertion portion for inserting a positioning screw on the back surface side of the bottom surface, after the housing is mounted on the apparatus main body in an inverted posture, the housing is opened from the back surface side of the housing. The positioning screw can be rotated. Thereby, the skew adjustment of the mirror member can be efficiently performed with fewer steps. Further, the engagement of the guide protrusion formed on the housing and the groove portion of the mirror angle adjusting member makes it possible to easily move the mirror angle adjusting member along the groove portion. Thereby, the skew adjustment of the mirror member is further facilitated. Further, since the mirror angle adjusting member and the urging means are formed by bending a metal plate-like member, the above effects can be obtained without increasing the cost of the image forming apparatus.

  According to invention of Claim 2, the contact part of the back surface of a mirror member and a mirror contact part moves by moving a mirror angle adjustment member back and forth. As a result, the skew adjustment of the mirror member can be performed easily and quickly. In addition, since the screw insertion portion into which the positioning screw is screwed is provided in the mirror angle adjusting member, the operator can move the mirror angle adjusting member forward or backward by simply rotating the positioning screw. The work can be performed quickly and the productivity of the image forming apparatus can be improved.

  According to the invention of claim 3, since the housing of the exposure means has the screw insertion portion for inserting the positioning screw on the back side of the bottom surface, the housing is mounted on the apparatus main body in the inverted posture. The positioning screw can be rotated from the back side of the housing. Thereby, the skew adjustment of the mirror member can be efficiently performed with fewer steps.

  An image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 shows a laser beam printer 1 which is a configuration example of an image forming apparatus. A laser beam printer 1 includes a photosensitive drum 2, a cleaner 3, a charger 3, a charger (charging means) 4, a laser scanning unit (exposure means) 5, a developing brush (developing means) 6, and a transfer roller. (Transfer means) 7, a fixing roller (fixing means) 8 disposed downstream of the transfer roller 7 in the conveying direction of the recording paper P, and a paper feed tray (recording paper holding means) loaded with the recording paper P 9, a paper discharge unit 10 on which the printed recording paper P is deposited, a recording paper transport mechanism 11 that transports the recording paper P loaded in the paper feed tray 9 to the position of the photosensitive drum 2, and a housing that houses each of the above parts. It is comprised by the body 14 grade | etc.,.

  The cleaner 3 removes toner and paper dust before one stroke (one rotation) adhering to the surface of the photosensitive drum 2 and cleans the drum surface. The charger 4 uniformly charges the surface of the photosensitive drum 2 cleaned by the cleaner 3. The laser scan unit 5 forms a latent image by irradiating the surface of the photosensitive drum 2 charged by the charger 4 while scanning the laser beam L. The developing brush 6 is attached to a toner cartridge 15 filled with toner, and forms a toner image by attaching toner to a portion of the surface of the photosensitive drum 2 where a latent image is formed. The transfer roller 7 is provided so as to oppose the surface of the photosensitive drum 2, and charges the surface of the recording paper P while pressing the recording paper P against the surface of the photosensitive drum 2. The formed toner image is transferred onto the recording paper P. The recording paper P on which the image is formed on the surface by the transfer roller 7 is conveyed to the fixing roller 8. The fixing roller 8 fixes the toner by applying heat and pressure while sandwiching the recording paper P together with the pressing roller 16 disposed opposite to the fixing roller 8. Heat for fixing the toner is supplied from a heater (for example, a halogen lamp) built in the fixing roller 8. The recording paper transport mechanism 11 has a pick roller 21 that sends out the recording paper P loaded in the paper feed tray 9. The pick roller 21 is rotatably supported by the frame member 23 via the rotation shaft 22. An opening is provided on the back side of the housing 14 in order to remove the recording paper jammed around the recording paper transport mechanism 11, and an opening / closing cover 24 is attached to the opening.

  FIG. 2 shows the configuration of the laser scan unit 5. The laser scan unit 5 includes a laser diode 31 that emits a laser beam, a first circuit board 32 that applies a driving voltage to the laser diode 31, and a collimator lens 33 that collimates the laser beam emitted from the laser diode 31. A slit 34 that narrows the laser beam that has been collimated by the collimator lens 33 and narrows it, a cylinder lens 35 that focuses the laser beam that has passed through the slit 34 only in the main scanning direction, and a beam that has been focused by the cylinder lens 35 A polygon mirror 36 that reflects the laser beam so as to scan in the main scanning direction, an fθ lens 37 that transmits the laser beam reflected by the polygon mirror 36, and a laser beam that passes through the fθ lens 37 is the surface of the photosensitive drum 2. Mirror member reflecting toward 38, a second circuit board 40 on which a drive motor (drive means) 39 for rotationally driving the polygon mirror 36 is mounted, a box-shaped housing 50 in which these components are incorporated, and a housing for the mirror member 38 And a mirror angle adjusting mechanism 51 for adjusting the mounting angle with respect to 50. The laser scanning unit 5 is mounted on the frame of the laser beam printer 1 in an inverted posture with the top and bottom reversed from the state shown in FIG. 2 (see FIG. 1). Accordingly, the housing 50 mounted on the frame has the back surface side of the bottom surface 50a in FIG. 2 oriented upward. In FIG. 2, the mirror angle adjusting mechanism 51 is provided at one end of the mirror member 38, but may be configured to be provided at both ends.

  3 and 4 show the configuration of the mirror angle adjustment mechanism 51. FIG. FIG. 4 shows the mirror angle adjustment mechanism 51 viewed from the back side of the housing 50. The mirror angle adjustment mechanism 51 includes a mirror angle adjustment member 52 that comes into contact with the rear end of the mirror member 38, and a spring member (biasing means) 53 that biases the mirror member 38 toward the mirror angle adjustment member 52. , A positioning screw 54 for positioning the mirror angle adjusting member 52 in the housing 50, a temporary fixing screw 55 for temporarily fixing the positioned mirror angle adjusting member 52 to the housing 50, and a spring member 53 in the housing 50. And a spring mounting screw 56 for mounting and fixing to the head. The mirror angle adjusting member 52, the positioning screw 54, the temporary fixing screw 55, and the spring mounting screw 56 are mounted from the back side of the bottom surface 50 a of the housing 50.

  The bottom surface 50a of the housing 50 is formed with an insertion hole 50b through which the spring member 53 is inserted from the back surface side to the front surface side. Further, on the rear surface side of the bottom surface 50 a, guide protrusions 50 c and 50 d for guiding the mirror angle adjusting member 52 in the optical axis direction of the fθ lens 37, a screw insertion portion 50 e through which the positioning screw 54 is inserted, and a spring member 53. A positioning projection 50f is formed so as to protrude substantially vertically from the bottom surface 50a. A screw hole (not shown) for inserting the positioning screw 54 is formed in the screw insertion portion 50e in parallel with the bottom surface 50a.

The mirror angle adjustment member 52 is formed by bending a metal plate-like member, and includes a mirror contact portion 52a that is in contact with the mirror member 38, and groove portions 52c and 52d in which the guide protrusions 50c and 50d are engaged. The screwing portion 52e into which the positioning screw 54 is screwed is provided.
The mirror contact portion 52 a is formed by folding back the tip end portion of the mirror angle adjusting member 52 that is bent along the side surface of the housing 50. Thus, since the mirror contact portion 52a is formed by folding the tip end portion of the mirror angle adjustment member 52, even if the angle of the mirror member 38 varies due to adjustment, the mirror member 38 and the mirror contact portion 52a. The contact area can be secured to such an extent that the mirror member 38 is not damaged. The screw threaded portion 52e is erected substantially vertically so as to face the screw insertion portion 50e of the housing 50 in parallel, and a female screw for threading the positioning screw 54 is formed. Therefore, when the positioning screw 54 is tightened while being brought into contact with the screw insertion portion 50e, the mirror angle adjusting member 52 is retracted in the direction of the arrow X. On the other hand, when the positioning screw 54 is loosened, the mirror angle adjusting member 52 is advanced in the arrow Y direction.

  The spring member 53 is formed by bending a metal plate-like member that is thinner than the mirror angle adjusting member 52, and the tip 53a is inserted from the insertion hole 50b to the surface side of the housing 50. The spring 50 is mounted on the bottom surface 50 a of the housing 50 by a spring mounting screw 56. A mirror pressing portion 53b that abuts the mirror member 38 on the tip 53a of the spring member 53 and presses the mirror member 38 in the direction of the optical axis of the fθ lens 37 and opposite to the fθ lens 37; In order to prevent the mirror member 38 from falling, a flange 53c that engages with the bottom surface of the mirror member 38 is formed. Further, a groove 53f that engages with the positioning projection 50f is formed on the opposite side of the tip 53a across a screw hole (not shown) through which the spring mounting screw 56 is inserted.

  When the mirror angle adjusting member 52 is moved forward or backward with the rotation of the positioning screw 54, the contact portion between the mirror member 38 and the mirror contact portion 52a and the mirror pressing portion 53b, that is, one end side of the mirror member 38 ( The side on which the mirror angle adjusting member 52 is provided moves. Thereby, the mirror member 38 rotates about the other end side as an axis. Further, as shown in FIG. 3, the mirror pressing is performed so that the contact portion between the mirror member 38 and the mirror pressing portion 53b is located above the contact portion between the mirror member 38 and the mirror contact portion 52a. Since the portion 53b and the mirror contact portion 52a are provided, a clockwise moment in the figure is generated in the mirror member 38 by the biasing force of the spring member 53. Accordingly, when the mirror angle adjusting member 52 is moved forward or backward with the rotation of the positioning screw 54, the mirror member 38 rotates clockwise or counterclockwise in FIG. Is adjusted. Then, after the mirror member 38 is adjusted to a desired angle, the temporary fixing screw 55 is fastened, and an adhesive is dropped and cured on the engaging portions of the guide protrusions 50c and 50d and the grooves 52c and 52d. By doing so, the mirror member 38 is fixed to the housing 50. The fastening of the mirror angle adjusting member 52 and the temporary fixing screw 55 and the dripping of the adhesive can all be performed from the back side of the housing 50. Therefore, after mounting the housing 50 on the frame or the like of the apparatus main body, the skew adjustment of the mirror member 38 can be performed from the outside of the housing 50 (that is, from above the apparatus main body).

  As described above, according to the present invention, by moving the mirror angle adjusting member 52 forward and backward, the contact portions between the mirror member 38 and the mirror contact portion 52a and the mirror pressing portion 53b move. Thereby, the skew adjustment of the mirror member 38 can be performed easily and quickly. In addition, the mirror angle adjusting member 52 is provided with a screw threaded portion 52e in which a female screw corresponding to the positioning screw 54 is formed, so that the operator can move the mirror angle adjusting member 52 forward and backward simply by rotating the positioning screw 54. Therefore, the adjustment operation can be performed quickly and the productivity of the laser beam printer can be improved. Furthermore, since the housing 50 of the laser scan unit 5 has a screw insertion portion 50e for inserting the positioning screw 54 on the back surface side of the bottom surface 50a, after the housing 50 is mounted on the frame, The positioning screw 54 can be rotated from the back side. Thereby, the skew adjustment of the mirror member 38 can be efficiently performed with fewer steps. Further, by engaging the guide protrusions 50c and 50d formed on the housing 50 with the grooves 52c and 52d of the mirror angle adjusting member 52, the mirror angle adjusting member 52 can be easily moved along the grooves 52c and 52d. Is possible. Thereby, the skew adjustment of the mirror member 38 is further facilitated. Further, since the mirror angle adjusting member 52 and the spring member 53 are formed by bending a metal plate-like member, these members can be manufactured at low cost, and the above-described effects can be obtained without increasing the cost. be able to.

  The present invention is not limited to the configuration of the above embodiment, and various modifications are possible. At least, the positioning screw 54 is rotated so that the mirror angle adjusting member 52 is parallel to the optical axis of the fθ lens 37. It is only necessary that the angle of the mirror member 38 can be adjusted by moving forward or backward. Further, the mirror angle adjusting member 52 is not limited to one constituted by sheet metal, and may be constituted by resin molding, for example.

1 is a cross-sectional view illustrating a configuration of a laser beam printer that is a configuration example of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a perspective view illustrating a configuration of a laser scan unit in the printer. The sectional side view which shows a mirror angle adjustment mechanism. The perspective view which shows the same mechanism from the back surface side of a housing.

Explanation of symbols

5 Laser scan unit 37 fθ lens 38 Mirror member 50 Housing 51 Mirror angle adjustment mechanism 52 Mirror angle adjustment member 53 Spring member (biasing means)
54 Positioning screw

Claims (3)

A photoreceptor drum having a photoreceptor coated on the surface;
Charging means for uniformly charging the surface of the photosensitive drum;
Exposure means for forming a latent image by irradiating the surface of the photoconductor while scanning with a laser beam;
Developing means for forming a toner image by attaching toner to a portion of the surface of the photoreceptor where a latent image is formed;
A toner image formed on the surface of the photosensitive drum is recorded at a predetermined transfer position downstream of the developing unit in the rotational direction of the photosensitive drum so as to face the surface of the photosensitive drum. Transfer means for transferring onto paper,
Fixing means for fixing the toner image on the recording paper by applying predetermined heat and pressure to the recording paper on which the toner image has been transferred,
The exposure means includes a laser diode that emits a laser beam, a collimator lens that collimates the laser beam emitted from the laser diode, and a cylinder that focuses the laser beam collimated by the collimator lens only in the main scanning direction. A lens, a polygon mirror that reflects the laser beam focused only in the main scanning direction by the cylinder lens so as to scan in the main scanning direction, an fθ lens that transmits the laser beam reflected by the polygon mirror, and the fθ A mirror member that reflects the laser beam transmitted through the lens toward the surface of the photosensitive drum, a box-shaped housing made of a resin molded product in which these components are incorporated, and an attachment angle of the mirror member to the housing is adjusted. Mirror angle adjustment mechanism In the image forming apparatus to
The mirror angle adjustment mechanism is attached to the housing so that a part of the mirror angle adjustment mechanism is exposed to the outside of the housing behind the mirror member, and abuts against the rear end of the mirror member to attach the mirror member to the housing. A mirror angle adjusting member for adjusting the angle; biasing means for biasing the mirror member toward the mirror angle adjusting member; and a positioning screw for positioning the mirror angle adjusting member on the housing;
The urging means has a base end portion mounted on the housing by a spring mounting screw outside the housing, and at the tip end portion the mirror member is in a direction parallel to the optical axis of the fθ lens and the fθ. It has a mirror pressing part that presses in the opposite direction to the lens,
The housing has an insertion hole through which the front end side of the biasing means is inserted into the housing, and the mirror angle adjustment member is advanced in a direction parallel to the optical axis of the fθ lens. The apparatus main body in an inverted posture with a guide projection for guiding the mirror angle adjusting member and a screw insertion portion for inserting the positioning screw on the back side of the bottom surface when the mirror angle adjustment member is retracted, with the top and bottom reversed. Mounted on
The mirror angle adjustment member is formed by bending a metal plate-like member, and includes a mirror contact portion that contacts the mirror member, a groove portion that engages with the guide protrusion, and the positioning screw. A screw threaded portion to be threaded;
After the housing is mounted on the apparatus main body, the positioning screw is rotated to move the mirror angle adjustment member forward or backward in a direction parallel to the optical axis of the fθ lens. The contact portion and the contact portion with the mirror pressing portion move, thereby enabling the skew adjustment of the mirror member, and fixing the mirror member to the housing so as to be at an optimum angle with respect to the photosensitive drum. An image forming apparatus characterized by being made possible. A photoreceptor drum having a photoreceptor coated on the surface;
An image forming apparatus comprising: an exposure unit configured to form a latent image by irradiating the surface of the photoconductor with a laser beam;
The exposure means transmits a laser diode that emits a laser beam, a polygon mirror that reflects the laser beam emitted from the laser diode so as to scan in the main scanning direction, and a laser beam reflected by the polygon mirror. An fθ lens, a mirror member that reflects the laser beam transmitted through the fθ lens toward the surface of the photosensitive drum, a housing in which these components are incorporated, and a mirror angle adjustment member that adjusts the angle of the mirror member Biasing means for biasing the mirror member toward the mirror angle adjustment member, and a positioning screw for positioning the mirror angle adjustment member on the housing,
The mirror angle adjusting member has a mirror abutting portion that abuts on the mirror member and a screw threaded portion into which the positioning screw is threaded.
By rotating the positioning screw to advance or retract the mirror angle adjustment member in a direction parallel to the optical axis of the fθ lens, the contact portion between the mirror member and the mirror contact portion and the mirror pressing portion is An image forming apparatus, wherein each of the image forming apparatuses is moved to thereby adjust the skew of the mirror member. The housing has a screw insertion portion for inserting the positioning screw on the back side of the bottom surface, and is mounted on the apparatus main body in an inverted posture with the top and bottom reversed.
After the housing is mounted on the apparatus main body, the mirror member can be fixed to the housing at an optimum angle with respect to the photosensitive drum by rotating the positioning screw. The image forming apparatus according to claim 2.

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