Image forming apparatus

Abstract

To provide an image forming apparatus that can maintain a constant distance between a print head and an image carrier, regardless of the tilt of the print head about a swing axis caused by tilt adjuster means.SOLUTION: An image forming apparatus 100 including an image carrier (1), a long print head 3 including a board (311) and a lens array 32, and tilt adjuster means (200) that adjusts a tilt of the print head 3, further includes positioning means (300) that positions the print head 3 relative to the image carrier (1) to maintain a constant distance d between the print head 3 and the image carrier (1), regardless of the tilt of the print head 3 about a swing axis β caused by the tilt adjuster means (200).SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present disclosure relates to image forming apparatuses such as copiers, multifunction peripherals, printers, and facsimile machines. [Background technology]

[0002] A conventionally known image forming device includes an image carrier (e.g., a photosensitive drum), a long print head, and a tilt adjustment means for adjusting the tilt of the print head around a swing axis that is aligned with the optical axis direction of multiple light-emitting elements (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-84636 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional image forming apparatuses equipped with a print head tilt adjustment unit have the following disadvantages, which will be explained below with reference to Figures 20A to 20C.

[0005] 20A to 20C are plan views (top) and front views (bottom), respectively, showing an example, another example, and yet another example of the distance d (d1, d2, d3) between the photosensitive drum 1 and the print head 3 in a conventional image forming apparatus 100X equipped with a tilt adjustment device for the print head 3. In Figures 20A to 20C, the symbol FL denotes the main body frame.

[0006] 20A to 20C, in the long print head 3, a plurality of light-emitting elements 31-31 that emit light to expose a photosensitive drum 1 (an example of an image carrier) are arranged in a line along the longitudinal direction L. A lens array 32 focuses the light emitted by the plurality of light-emitting elements 31-31 onto the photosensitive drum 1.

[0007] In such a conventional image forming apparatus 100X, as shown in FIGS. 20B and 20C, skew or the like of a sheet P such as a recording paper may occur. The inclination adjusting means adjusts the inclination of the print head 3 around the swing axis β along the optical axis direction N of the plurality of light emitting elements 31 to 31 in accordance with the skew or the like of the sheet P. In this example, the swing axis β is located outside the print head 3 in the rotation axis direction X of the photosensitive drum 1.

[0008] By the way, the depth of focus of the print head 3 which is an exposure apparatus using the plurality of light emitting elements 31 to 31 and the lens array 32 is a smaller value (for example, about 0.1 mm) than the depth of focus of other types of exposure apparatuses (for example, an optical scanning apparatus which is an exposure apparatus using a light deflector and an fθ lens). For this reason, it is necessary to position the print head 3 with respect to the photosensitive drum 1 so that the distance between the photosensitive drum 1 and the print head 3 becomes constant.

[0009] However, in the conventional image forming apparatus 100X, when adjusting the inclination of the print head 3 around the swing axis β, since the print head 3 moves parallel to the linear direction T orthogonal to both the rotation axis α and the swing axis β as viewed from the rotation axis direction X of the photosensitive drum 1, the distance d (d1, d2, d3) between the photosensitive drum 1 and the print head 3 varies depending on the position of the print head 3 in the linear direction T (d1 < d2 < d3). For example, when the depth of focus is 0.1 mm, even if the focus of the lens array 32 with respect to the surface 1a of the photosensitive drum 1 is adjusted according to the configuration shown in FIG. 20A, the distance d (d2) between the photosensitive drum 1 and the print head 3 in the configuration shown in FIG. 20B moved horizontally by +1 mm (to the left in the illustrated example) becomes d1 + 0.258 mm. That is, as shown in FIGS. 20B and 20C, as the print head 3 moves in the linear direction T, the distance d (d1 < d2 < d3) between the photosensitive drum 1 and the print head 3 increases, and the focus of the image formed on the surface 1a of the photosensitive drum 1 is shifted. This becomes more prominent as the diameter (curvature) of the photosensitive drum 1 becomes smaller with the miniaturization of the image forming apparatus 100X.

[0010] Therefore, an object of the present disclosure is to provide an image forming apparatus that can maintain a constant distance between the print head and the image carrier regardless of the tilt of the print head around the swing axis caused by the tilt adjustment means. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems, the image forming apparatus according to the present disclosure is an image forming apparatus comprising: an image carrier; a long print head including a substrate having a plurality of light-emitting elements arranged in a line and a lens array that focuses light emitted by the plurality of light-emitting elements onto the image carrier; and a tilt adjustment means that adjusts the tilt of the print head around a swing axis that is along the optical axis direction of the plurality of light-emitting elements, and is characterized by comprising a positioning means that positions the print head with respect to the image carrier so as to maintain a constant distance between the print head and the image carrier, regardless of the tilt of the print head around the swing axis caused by the tilt adjustment means. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to keep the distance between the print head and the image carrier constant regardless of the tilt of the print head around the pivot axis caused by the tilt adjustment means. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing an image forming apparatus according to an embodiment of the present invention. [Figure 2] 1 is a perspective view of an example of a print head and an example of an inclination adjustment mechanism provided on a main body frame in an image forming apparatus according to an embodiment of the present invention, viewed obliquely from above on the front side. [Figure 3] 3 is a perspective view of the print head shown in FIG. 2 supported on a swinging section, as viewed obliquely from above on the front side. [Figure 4A] FIG. 2 is a perspective view of the print head as seen from diagonally above the rear side. [Figure 4B]FIG. 4B is a perspective view of the print head shown in FIG. 4A as viewed obliquely from below on the front side. [Figure 4C] FIG. 4B is an exploded perspective view of the print head shown in FIG. 4A, viewed obliquely from above on the front side. [Figure 4D] FIG. 4B is an exploded perspective view of the print head shown in FIG. 4A, viewed obliquely from below on the rear side. [Figure 5A] FIG. 2 is a cross-sectional perspective view of the print head as seen from diagonally above the front side. [Figure 5B] FIG. 2 is a cross-sectional view of a print head. [Figure 5C] FIG. 5C is a schematic diagram for easily understanding the cross-sectional view shown in FIG. 5B. [Figure 5D] 1 is a plan view showing a state in which a flexible circuit board is extended linearly in a light-emitting element substrate, a flexible circuit board, and a printed wiring board that constitute a print head. FIG. [Figure 6A] 10 is a perspective view of a swing support portion provided on the swing portion, viewed obliquely from above on the rear side. FIG. [Figure 6B] 10 is a perspective view showing a state in which a swing support portion provided on the swing portion is inserted into a through-hole in a frame on the rear side, as viewed obliquely from above on the rear side. FIG. [Figure 6C] 10 is an exploded perspective view of the swinging portion, the swing support portion, and the through-hole in the main body frame, viewed obliquely from below on the rear side. FIG. [Figure 7A] 10 is a perspective view of the tilt adjustment unit provided on the front body frame as viewed obliquely from above the front side. FIG. [Figure 7B] 10 is a perspective view of the tilt adjustment unit provided on the main body frame on the front side, as viewed obliquely from below on the rear side. FIG. [Figure 7C] FIG. 2 is an exploded perspective view of the tilt adjustment unit as viewed obliquely from above on the front side. [Figure 7D] FIG. 10 is an exploded perspective view of the tilt adjustment unit as viewed obliquely from above on the rear side. [Figure 8] FIG. 2 is a perspective view of the photosensitive unit, the print head, and the swinging portion as viewed from above on the left side. [Figure 9A] FIG. 2 is a perspective view of a positioning portion on one side of a swinging portion on which a print head is provided, as viewed obliquely from above. [Figure 9B] 9B is an exploded perspective view of the print head and the swinging portion shown in FIG. 9A, seen obliquely from above. FIG. [Figure 9C] 9B is an exploded perspective view of the print head and the swinging portion shown in FIG. 9A, seen obliquely from below. FIG. [Figure 9D] 9 is a cross-sectional perspective view of a positioning portion and a positioned portion on one side shown in FIG. 8, viewed obliquely from above. [Figure 9E] 9 is an enlarged view of a positioning portion and a positioned portion on one side of the γ1 portion shown in FIG. 8. FIG. [Figure 10A] FIG. 10 is a perspective view of the positioning portion on the other side of the swinging portion on which the print head is provided, as viewed obliquely from above. [Figure 10B] 10B is an exploded perspective view of the print head and the swinging portion shown in FIG. 10A, seen obliquely from above. FIG. [Figure 10C] 10B is an exploded perspective view of the print head and the swinging portion shown in FIG. 10A, seen obliquely from below. FIG. [Figure 10D] 9 is a perspective view of the positioning portion and the positioned portion on the other side shown in FIG. 8, viewed obliquely from below. [Figure 10E] 9 is an enlarged view of a positioning portion and a positioned portion on the other side of the γ2 portion shown in FIG. 8. [Figure 11] 10 is a cross-sectional view showing a state in which a positioning portion on one side is in contact with a positioned portion on one side. FIG. [Figure 12] FIG. 10 is a front view illustrating how the distance between the print head and the photosensitive drum is maintained constant regardless of the inclination of the print head around the swing axis. [Figure 13A] FIG. 10 is an exploded perspective view of a positioning portion and a lens holding member on one side, as viewed obliquely from below. [Figure 13B] 10 is a perspective view of a state in which one positioning portion is attached to a lens holding member, as viewed obliquely from below. FIG. [Figure 14A] FIG. 10 is a perspective view of the positioning portion on one side as viewed from above on the rear side. [Figure 14B] FIG. 10 is a perspective view of the positioning portion on one side as viewed from below on the front side. [Figure 15A]FIG. 10 is an exploded perspective view of the other side positioning portion and the lens holding member as viewed obliquely from below. [Figure 15B] 10 is a perspective view of the state in which the other positioning portion is attached to the lens holding member, as viewed obliquely from below. FIG. [Figure 16A] FIG. 10 is a perspective view of the other positioning portion as viewed from above on the rear side. [Figure 16B] FIG. 10 is a perspective view of the other positioning portion as viewed from below on the front side. [Figure 17] FIG. 10 is a side view showing another example of the positioning mechanism. [Figure 18A] FIG. 18 is a front view of the guide mechanism shown in FIG. [Figure 18B] FIG. 18 is a rear view of the guide mechanism shown in FIG. [Figure 19] This is a front view illustrating how the distance between the print head and the photosensitive drum is maintained constant regardless of the inclination of the print head around the swing axis, and how the optical axes of multiple light-emitting elements in the print head are directed toward the center of rotation of the photosensitive drum. [Figure 20A] 1A and 1B are plan and front views showing an example of the distance between a photosensitive drum and a print head in a conventional image forming apparatus equipped with a print head tilt adjustment unit. [Figure 20B] 10A and 10B are plan and front views showing another example of the distance between the photosensitive drum and the print head in a conventional image forming apparatus equipped with a print head tilt adjustment unit. [Figure 20C] 10A and 10B are plan and front views showing still another example of the distance between the photosensitive drum and the print head in a conventional image forming apparatus equipped with a print head tilt adjustment unit. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. The names and functions of the components are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0015] (Image forming device) 1 is a cross-sectional view showing an image forming apparatus 100 according to this embodiment. In the figure, the rotational axis direction of the photosensitive drum 1 is designated as X, the front side as X1, the back side as X2, the direction perpendicular to the rotational axis direction X as the left-right direction Y, the right side as Y1, the left side as Y2, and the up-down direction perpendicular to the rotational axis direction X and the left-right direction Y as Z, in the following description.

[0016] Image data handled in the image forming apparatus main body 101 of the image forming apparatus 100 corresponds to a color image using each of the colors black (K), cyan (C), magenta (M), and yellow (Y), or a monochrome image using a single color (e.g., black). For this reason, four photosensitive drums 1 (an example of an image carrier), four chargers 2, four print heads 3, four developing devices 4, four primary transfer devices 5, and four drum cleaning devices 6 are provided to form four types of toner images corresponding to each color, and four image stations Pa, Pb, Pc, and Pd are configured corresponding to black, cyan, magenta, and yellow, respectively.

[0017] In each of the image stations Pa, Pb, Pc, and Pd, the chargers 2 uniformly charge the surfaces of the photosensitive drums 1, which are driven to rotate in a predetermined rotation direction R, to a predetermined potential. The print heads 3 expose the surfaces of the photosensitive drums 1 to light, forming electrostatic latent images on the surfaces 1a of the photosensitive drums 1. The developing devices 4 develop the electrostatic latent images on the surfaces 1a of the photosensitive drums 1 to form toner images on the surfaces 1a of the photosensitive drums 1. This results in toner images of each color being formed on the surfaces 1a of the photosensitive drums 1. The drum cleaning devices 6 remove and collect residual toner from the surfaces of the photosensitive drums 1. The primary transfer devices 5 sequentially transfer the toner images of each color from the surfaces of the photosensitive drums 1 to the intermediate transfer belt 23, which is rotated by a drive roller 21 and a driven roller 22 of the belt drive device 20, superimposing the toner images onto the intermediate transfer belt 23, forming color toner images on the intermediate transfer belt 23. The belt cleaning device 7 removes and collects residual toner from the intermediate transfer belt 23 .

[0018] A transfer nip portion TN is formed between the intermediate transfer belt 23 and a transfer roller 81 of the secondary transfer device 8, and the transfer roller 81 of the secondary transfer device 8 sandwiches a sheet P, such as a recording paper, transported through the sheet transport path 11 in the transfer nip portion TN and transports it together with the intermediate transfer belt 23, while transferring the color toner image on the surface of the intermediate transfer belt 23 onto the sheet P. The fixing device 9 sandwiches the sheet P between a fixing member (fixing belt 91 in this example) and a pressure member (pressure roller 92 in this example), and heats and presses the sheet P, fixing the color toner image on the sheet P.

[0019] The sheet P is drawn out of the paper feed cassette 13 by the pickup roller 12, transported through the sheet transport path 11, passed through the secondary transfer device 8 and the fixing device 9, and then transported to the discharge tray 15 via the discharge roller 14. The sheet transport path 11 is provided with a registration roller 16 and the like. The registration roller 16 temporarily stops the sheet P, aligns the leading edge of the sheet P, and then starts transporting the sheet P in accordance with the timing of the transfer of the toner image at the transfer nip portion TN between the intermediate transfer belt 23 and the transfer roller 81.

[0020] [About this embodiment] FIG. 2 is a perspective view of an example of print heads 3-3 and an example of tilt adjustment mechanism 200 in image forming apparatus 100 according to this embodiment, as viewed obliquely from above the front side X1, when the print heads 3-3 and an example of tilt adjustment mechanism 200 are mounted on a main frame FL (FL1-FL3). FIG. 3 is a perspective view of the print head 3 shown in FIG. 2 supported by a swinging portion 210, as viewed obliquely from above the front side X1. FIG. 4A is a perspective view of the print head 3 shown in FIG. 4A, as viewed obliquely from above the rear side X2. FIG. 4B is a perspective view of the print head 3 shown in FIG. 4A, as viewed obliquely from below the front side X1. FIGS. 4C and 4D are exploded perspective views of the print head 3 shown in FIG. 4A, as viewed obliquely from above the front side X1 and from below the rear side X2, respectively.

[0021] Fig. 5A is a cross-sectional perspective view of print head 3 viewed obliquely from above on the front side. Fig. 5B is a cross-sectional view of print head 3. Fig. 5C is a schematic diagram that clearly shows the cross-sectional view shown in Fig. 5B. Fig. 5D is a plan view showing the light-emitting element substrate 311, flexible circuit board 312a, and printed wiring board 312b that make up print head 3, with flexible circuit board 312a extended linearly.

[0022] Since the print heads 3-3 and the swinging units 210-210 have the same configuration, they are shown in a single diagram in FIGS. 3 to 5D, and in the following description, the print heads 3-3 will simply be referred to as the print heads 3 and the swinging unit 210.

[0023] In the following description, the plurality of light-emitting elements 31-31 in the print heads 3-3 will be described as organic light-emitting diodes (OLEDs: Organic Light-Emitting Diodes, hereinafter simply referred to as OLEDs). Note that the light-emitting elements 31-31 are not limited to OLEDs and may be inorganic light-emitting diodes (LEDs) or nano-scale light-emitting diodes (LEDs) that are smaller than a micrometer.

[0024] The image forming apparatus 100 according to this embodiment includes a photosensitive drum 1, a long print head 3, and an inclination adjustment mechanism 200 (an example of an inclination adjustment unit) (see FIG. 2). The print head 3 includes a light-emitting element substrate 311 (an example of a substrate) and a lens array 32. The light-emitting element substrate 311 has a plurality of light-emitting elements 31-31 (see FIGS. 5B to 5D). The light-emitting elements 31-31 emit light for exposing the surface 1a of the photosensitive drum 1. The light-emitting elements 31-31 are arranged in a line in the longitudinal direction L of the print head 3. In this example, the light-emitting element substrate 311 is a film-like substrate (flexible OLED panel) on which OLED elements (31-31) are mounted. This configuration allows the print head 3 to be made smaller and less expensive.

[0025] The lens array 32 extends in the longitudinal direction L and focuses light emitted by the light-emitting elements 31 onto the surface 1a of the photosensitive drum 1. The lens array 32 is disposed opposite the light-emitting elements 31. The tilt adjustment mechanism 200 adjusts the tilt of the print head 3 around a swing axis β (see FIG. 3) along the optical axis direction N of the multiple light-emitting elements 31. More specifically, the tilt adjustment mechanism 200 swings one side L1 of the print head 3 in the longitudinal direction L around the swing axis β on the other side L2, thereby adjusting the exposure position of the light-emitting elements 31 with respect to the surface 1a of the photosensitive drum 1. In this example, the swing axis β is located outside the print head 3 in the rotation axis direction X.

[0026] <Print head> As shown in Figures 5A to 5D, the print head 3 further includes a driving member 312, a lens holding member 313, a fixing member 314 (base member), and a main body member 315. The driving member 312 drives the light emitting elements 31-31. The lens holding member 313 holds the lens array 32. The fixing member 314 fixes the lens holding member 313 while fixing the light emitting element substrate 311. The main body member 315 holds the driving member 312, the lens holding member 313, and the fixing member 314.

[0027] In this example, the driving member 312 includes a flexible circuit board 312a, a printed wiring board 312b (PWB: Printed Wiring Board), a driving circuit element 312c, and a protective member 312d. One end of the flexible circuit board 312a is connected to one end of the light-emitting element substrate 311, and the other end is connected to one end of the printed wiring board 312b. The flexible circuit board 312a is a flexible circuit board (COF: Chip on Film) in which a driving circuit element 312c (driver IC) that drives the OLED elements (31-31) on the light-emitting element substrate 311 is mounted on a film. The printed wiring board 312b connected to the flexible circuit board 312a has an input terminal 312b1 (see FIG. 5C) and is connected to a connector CN (see FIG. 5C) via the input terminal 312b1. The protective member 312d protects exposed portions of the light-emitting element substrate 311 and the flexible circuit board 312a. The connector CN is connected to an image processing device (not shown) provided in the image forming apparatus main body 101. In Fig. 5C, the light emitting elements 31-31 are depicted as if they are provided protruding from the outer surface of the light emitting element substrate 311 (a panel which is an example of a substrate), but this is for the purpose of making the light emitting elements 31-31 easier to understand, and in reality, as shown in Fig. 5B, they are provided inside (by vapor deposition, for example) so as not to protrude from the outer surface of the panel (311).

[0028] The lens holding member 313 is a frame-shaped member that surrounds the outer peripheral surfaces 32a-32a of the lens array 32 (see FIGS. 4C and 4D) along the optical axis direction N. Here, the optical axis direction N is a direction (thickness direction) perpendicular to both the longitudinal direction L and the width direction M of the print head 3. The lens array 32 is inserted into the inner surface 313a of the frame-shaped lens holding member 313. At least a portion of the outer peripheral surfaces 32a-32a (in this example, the side surfaces 32a1, 32a1 along the longitudinal direction L) of the lens array 32 is held by the lens holding member 313, and at least some locations (in this example, multiple locations) are bonded with an adhesive (e.g., an ultraviolet-curing adhesive). In addition, the periphery of the joint between the lens array 32 and the lens holding member 313 is sealed with a caulking agent (caulking resin). This effectively prevents foreign matter such as dust from entering the lens holding member 313 through the joint between the lens array 32 and the lens holding member 313.

[0029] The fixing member 314 is formed in a rectangular parallelepiped shape. A back surface 313c of the light-emitting element substrate 311 (a panel on which the light-emitting elements 31 are provided) opposite the light-emitting elements 31 is adhered to a surface 314a of the fixing member 314 on the photosensitive drum 1 side (one side N1) in the optical axis direction N with an adhesive member E (e.g., double-sided adhesive tape) (see FIG. 5C ). A back surface 313c of the lens holding member 313 is fixed to a substrate surface 311a of the light-emitting element substrate 311 (a panel on which the light-emitting elements 31 are provided) opposite the fixing member 314. The periphery of the joint between the lens holding member 313 and the light-emitting element substrate 311 (a panel on which the light-emitting elements 31 are provided) is sealed with a caulking agent (caulking resin). This effectively prevents foreign matter such as dust from entering the lens holding member 313 through the joint between the lens holding member 313 and the light-emitting element substrate 311 (a panel on which the light-emitting elements 31 are provided).

[0030] The relative positions (positions in the longitudinal direction L, width direction M, and optical axis direction N) of the plurality of light emitting elements 31 to 31 and the lens array 32 are adjusted in advance in the production process using a jig or the like.

[0031] The main body member 315 has an arrangement portion 315a, a bent portion 315b, and a substrate guide portion 315c. The arrangement portion 315a, the bent portion 315b, and the substrate holding portion 315d are integrally formed.

[0032] The placement portion 315a places the fixed member 314 of the print head 3. The placement portion 315a has a placement surface 315a1 on which the fixed member 314 is placed so that the back surface 314b of the fixed member 314 on the swing portion 210 side comes into contact. This allows the fixed member 314 to be reliably placed on the placement surface 315a1 of the placement portion 315a. The placement surface 315a1 of the placement portion 315a has a plurality (two) positioning protrusions or recesses (positioning protrusions 315a2, 315a2 in this example) (see FIG. 4C). The back surface 314b of the fixed member 314 has positioning recesses or protrusions (positioning recesses 314c, 314c in this example) (see FIG. 4D) that correspond to the plurality (two) positioning protrusions or recesses (315a2, 315a2). This allows the fixed member 314 to be reliably positioned relative to the main body member 315. The arrangement portion 315a is provided with a plurality of (two) holding portions 315a3 (see FIGS. 4C, 4D, and 5B). The arrangement portion 315a and the holding portions 315a3 (315a3) are integrally formed. The holding portions 315a3 (315a3) detachably hold the fixing member 314 to the arrangement portion 315a. The holding portions 315a3 (315a3) restrict movement of the fixing member 314 toward the light emitting elements 31-31 (one side N1) in the optical axis direction N. The holding portions 315a3 (315a3) have locking portions 315a31 (see FIG. 5B) that lock the surface 314a of the fixing member 314.

[0033] Bent portion 315b is bent at an acute angle (for example, 60 degrees or less, about 50 degrees in this example) with respect to arrangement portion 315a. Printed wiring board 312b is fixed to surface 315b1 (inner surface) of bent portion 315b facing arrangement portion 315a. Input terminal 312b1 is provided at the entrance end of space SP between arrangement portion 315a and bent portion 315b of printed wiring board 312b, and connector CN is connected to it so that it faces toward space SP.

[0034] The substrate guide portion 315c has a curved portion 315c1 that folds the flexible circuit board 312a connected to the light-emitting element substrate 311 toward the space SP. The curved portion 315c1 is curved so as to fold back at an angle of 180 degrees or more between the light-emitting element substrate 311 and the flexible circuit board 312a. A portion of the light-emitting element substrate 311 facing the flexible circuit board 312a and a portion of the flexible circuit board 312a facing the light-emitting element substrate 311 are bonded to the curved portion 315c1 with an adhesive member E. This allows the curved portion 315c1 to reliably fold back the flexible circuit board 312a into the space SP. The protective member 312d faces the light-emitting element substrate 311 and the flexible circuit board 312a at portions corresponding to the curved portion 315c1, and is curved along the curved portion 315c1. 4C and 4D, the protective member 312d is fastened to a fastening portion 315e (female screw) of the main body member 315 on one side L1 in the longitudinal direction L by inserting a fastening member SC1 (male screw) through a through hole 312e1 of the holder 312e and a through hole 312d1 of the protective member 312d. This allows the end of the protective member 312d on one side L1 in the longitudinal direction L to be fixed to the main body member 315.

[0035] Furthermore, the protective member 312d is fastened to the fastening portion 315e of the main body member 315 by inserting the fastening member SC1 through the through hole 312d1 of the protective member 312d on the other side L2 in the longitudinal direction L. This allows the end of the protective member 312d on the other side L2 in the longitudinal direction L to be fixed to the main body member 315. Furthermore, the printed wiring board 312b is positioned such that the positioning hole 312b2 of the printed wiring board 312b is matched with the positioning protrusion 315b2 of the bending portion 315b on the other side L2 in the longitudinal direction L. In this state, the printed wiring board 312b is fastened to the fastening portion 312e2 (female screw) of the holder 312e on one side L1 in the longitudinal direction L by inserting the fastening member SC2 through the through hole 315b3 of the bending portion 315b and the through recess 312b3 of the printed wiring board 312b. This allows the protective member 312d to be held in a state where it is positioned at the bent portion 315b.

[0036] An end portion of the flexible circuit board 312a provided in the space SP on the side of the printed wiring board 312b is folded back at the corner between the placement portion 315a and the bent portion 315b and connected to the printed wiring board 312b.

[0037] The drive circuit element 312c is provided on the flexible circuit board 312a on the side of the arrangement portion 315a. A recess 315a5 is provided on a surface 315a4 (inner surface) of the arrangement portion 315a facing the bent portion 315b to prevent interference with the drive circuit element 312c on the flexible circuit board 312a.

[0038] Furthermore, the main body member 315 is provided with a pair of side plate portions 315f, 315g (see FIGS. 4C and 4D) that close both ends in the longitudinal direction L of the space SP.

[0039] <Tilt adjustment mechanism> Next, an example of the tilt adjustment mechanism 200 will be described below with reference to FIGS. 6A to 7. FIG.

[0040] FIG. 6A is a perspective view of the swing support member 220 provided on the swing unit 210, viewed obliquely from above the rear side X2. FIG. 6B is a perspective view of the swing support member 220 provided on the swing unit 210 inserted into the through-hole FL2a in the main body frame FL2 on the rear side X2, viewed obliquely from above the rear side X2. FIG. 6C is an exploded perspective view of the swing unit 210, the swing support member 220, and the through-hole FL2a in the main body frame FL2, viewed obliquely from below the rear side X2. FIGS. 7A and 7B are perspective views of the tilt adjustment member 230 provided on the main body frame FL1 on the front side X1, viewed obliquely from above the front side X1 and from below the rear side X2, respectively. FIGS. 7C and 7D are exploded perspective views of the tilt adjustment member 230, viewed obliquely from above the front side X1 and from above the rear side X2, respectively.

[0041] The tilt adjustment mechanism 200 includes a swing unit 210, a swing support unit 220 (see FIGS. 6A and 6B), and a tilt adjustment unit 230 (see FIGS. 7A to 6D). The swing unit 210 is provided with a print head 3. The swing unit 210 is swingable about a swing axis β by the swing support unit 220 provided on a swing unit main body 211, and the tilt about the swing axis β is adjusted by the tilt adjustment unit 230. The swing support unit 220 is fixed to an end of the swing unit main body 211 on the other side L2 (in this example, the rear side X2) in the longitudinal direction L. A main body frame FL (in this example, the main body frame FL2 on the rear side X2) (see FIG. 6B) of the image forming apparatus main body 101 (see FIG. 1) supports the swing unit main body 211 so that it can swing about the swing axis β (see FIG. 6A).

[0042] In this example, the main body frames FL1 and FL2 are supported at their centers in the rotational axis direction X by a main body frame FL3 that extends along the rotational axis direction X and the left-right direction Y. The swinging portion 210 is placed on the main body frame FL3. As shown in FIGS. 6A and 6B, the swinging support portion 220 is a plate-shaped member that extends in the optical axis direction N. The swinging support portion 220 is provided with a protruding portion 221 that protrudes toward the other side L2 and extends in the optical axis direction N. The main body frame FL2 on the back side X2 is provided with a through-hole FL2a through which the protruding portion 221 is inserted.

[0043] 6C, the through hole FL2a supports the swinging of the swing support part 220 around the swing axis β by point contact at one or more (three in this example) points. Specifically, one or more protrusions FL2a1 to FL2a3 are provided on the edge of at least one side (both sides in this example) in the width direction M of the through hole FL2a. In this example, two protrusions FL2a1 and FL2a2 are provided at an interval in the vertical direction Z on the edge of one side M1 of the through hole FL2a in the width direction M. Furthermore, one protrusion FL2a3 is provided at the edge of the other side M2 ​​of the through hole FL2a in the width direction M, between (specifically, at the center) the two protrusions FL2a1 and FL2a2 on one side M1 provided in the vertical direction Z. The dimension g1 of the through hole FL2a in the width direction M (the dimension between the protrusions FL2a1, FL2a2 on one side H1 and the protrusion FL2a3 on the other side in the width direction H) is larger than the dimension g2 of the protrusion 221 in the width direction M by a predetermined dimension to the extent that the oscillating portion main body 211 can be oscillated. This allows the oscillating portion main body 211 to oscillate around the oscillation axis β.

[0044] The swing support part 220 is provided with a plurality of (two) positioning holes 220a and a through hole 220b. Positioning protrusions 211a (see FIG. 6C) and a fastening part 211b (female screw) (see FIG. 6C) are provided on a back surface 211e of the swing part main body 211 opposite the print head 3. The positioning protrusions 211a are inserted into the plurality of positioning holes 220a of the swing support part 220. The fastening part 211b is fastened by inserting a fastening member SC3 (male screw) (see FIG. 6C) into the through hole 220b of the swing support part 220. This allows the swing support part 220 to be fixed in a positioned state to the swing part main body 211.

[0045] As shown in FIGS. 7A to 7D , the tilt adjustment unit 230 includes a connecting member 231, a moving member 232, a biasing member 233, and an adjustment member 234. The connecting member 231 connects the swinging unit main body 211 of the swinging unit 210 to the moving member 232. The moving member 232 is provided so as to be movable to one side M1 (left side Y1) and the other side M2 ​​(right side Y2) in the width direction M with respect to the front main body frame FL1 of the image forming apparatus main body 101. The biasing member 233 biases the moving member 232 toward the other side M2 ​​in the width direction M (in this example, the upstream side in the rotation direction R of the photosensitive drum 1 (see FIG. 1)) with respect to the front main body frame FL1. The adjustment member 234 presses the moving member 232 toward the one side M1 in the width direction M (in this example, the downstream side in the rotation direction R of the photosensitive drum 1) with respect to the front main body frame FL1 so as to adjust its position.

[0046] More specifically, the connecting member 231 is formed by stamping out and bending a metal plate, and has a main body 2311, and a first fixed portion 231a and a second fixed portion 231b connected to the main body 2311. The first fixed portion 231a is fixed to the swinging portion main body 211 of the swinging portion 210. The second fixed portion 231b is fixed to the moving member 232.

[0047] The first fixing portion 231a is provided with a plurality of (two) positioning holes 231a1 and a through-hole 231a2. Protrusions 211c (see FIG. 7B) and a fastening portion 211d (female screw) (see FIG. 7B) are provided on a back surface 211e of the swinging portion main body 211 opposite the print head 3. The protrusions 211c are inserted into the plurality of positioning holes 231a1 and 231a1 of the first fixing portion 231a. The fastening portion 211d is fastened by inserting a fastening member SC4 (male screw) (see FIG. 7B) into the through-hole 231a2 of the first fixing portion 231a. This allows the connecting member 231 to be fixed in a positioned state to the swinging portion 210.

[0048] The second fixing portion 231b is provided with a plurality of (two) positioning holes 231b1, 231b1, a through hole 231b2, and a long through hole 231b3. The moving member 232 is provided with positioning protrusions 232a, 232a, a fastened portion 232b (female screw) (see FIGS. 7B and 7D), and a long through hole 232c (see FIGS. 7B and 7D). The positioning protrusions 232a, 232a are inserted into the plurality of positioning holes 231b1, 231b1 of the second fixing portion 231b. The fastened portion 232b is fastened by inserting a fastening member SC5 (male screw) (see FIG. 7B) through the through hole 231b2 of the second fixing portion 231b. This allows the connecting member 231 to be fixed in a positioned state to the moving member 232. The long through-hole 231b3 and the long through-hole 232c are provided in the second fixed portion 231b and the moving member 232, respectively, so that the long through-hole 231b3 and the long through-hole 232c are aligned with each other.

[0049] Furthermore, a first guide portion 232d (see FIGS. 7B, 7C, and 7D) that is T-shaped in cross section when viewed from the width direction M is provided on the side of the moving member 232 opposite the positioning protrusions 232a, 232a. A first sliding portion FL1a (see FIGS. 7C and 7D) is provided on the front-side main body frame FL1. The first sliding portion FL1a is a slit portion that extends along the width direction M, and the first guide portion 232d is inserted from the other side M2 ​​to the one side M1 in the width direction M. This allows the moving member 232 to be movable in the width direction M. A rod-shaped (cylindrical) second guide portion 232e (see FIGS. 7A, 7C, and 7D) that extends along the width direction M is provided on the end of the one side M1 in the width direction M of the moving member 232. A second sliding portion FL1b1 is provided on the first frame portion FL1b that extends along the rotation axis direction X and the up-down direction Z of the front-side main body frame FL1. The second sliding portion FL1b1 is a through hole along the width direction M, and the second guide portion 232e is inserted through the second sliding portion FL1b1. The biasing member 233 is a coil spring, and is inserted through the second guide portion 232e between the first frame portion FL1b and the moving member 232.

[0050] A fastening portion FL1c1 (female screw) is provided on the second frame portion FL1c of the front-side main frame FL1 along the rotation axis direction X and the up-down direction Z. The adjustment member 234 is an adjustable fastening portion (headless male screw, so-called insect screw) along the width direction M. The fastening portion FL1c1 is fastened to the adjustment member 234. As a result, while the adjustment member 234 is biased toward the other side M2 ​​in the width direction M by the biasing member 233, an operator can rotate the adjustment member 234 with a tool such as a screwdriver to move the adjustment member 234 toward one side M1 or the other side M2 ​​in the width direction M, thereby adjusting the tilt of the print head 3 fixed to the moving member 232 about the oscillation axis β.

[0051] The front-side main body frame FL1 is provided with a fastening portion FL1d (female screw) (see FIGS. 7C and 7D). The fastening portion FL1d is fastened by a fastening member SC6 (male screw) (see FIGS. 7C and 7D) that is inserted through the elongated through-hole 231b3 of the second fixed portion 231b and the elongated through-hole 232c of the moving member 232. This allows the print head 3 to be fixed to the front-side main body frame FL1 after adjusting the tilt of the print head 3 about the swing axis β.

[0052] <Positioning mechanism> Next, an example of the positioning mechanism 300 will be described below with reference to FIGS.

[0053] FIG. 8 is a perspective view of the photosensitive unit 400, print head 3, and swinging unit 210, viewed from above on the left side. FIG. 9A is a perspective view of the positioning portion 301a on one side L1 of the swinging unit 210, on which the print head 3 is provided, viewed from diagonally above. FIGS. 9B and 9C are exploded perspective views of the print head 3 and swinging unit 210 shown in FIG. 9A, viewed from diagonally above and diagonally below, respectively. Note that the connecting member 231, moving member 232, and adjustment member 234 are omitted from FIGS. 9B and 9C. FIG. 9D is a cross-sectional perspective view of the positioning portion 301a and the positioned portion 302a on one side L1 shown in FIG. 8, viewed from diagonally above. FIG. 9E is an enlarged view of the positioning portion 301a and the positioned portion 302a on one side L1 of the γ1 portion shown in FIG. 8.

[0054] FIG. 10A is a perspective view of the positioning portion 301b on the other side L2 of the swinging portion 210 on which the print head 3 is provided, viewed from diagonally above. FIGS. 10B and 10C are exploded perspective views of the print head 3 and swinging portion 210 shown in FIG. 10A, viewed from diagonally above and diagonally below, respectively. Note that the swing support portion 220 is omitted from FIGS. 10B and 10C. FIG. 10D is a perspective view of the positioning portion 301b and the positioned portion 302b on the other side L2 shown in FIG. 8, viewed from diagonally below. FIG. 10E is an enlarged view of the positioning portion 301b and the positioned portion 302b on the other side L2 of the γ2 portion shown in FIG. 8.

[0055] Fig. 11 is a cross-sectional view showing the state in which the positioning portion 301a on one side L1 is in contact with the positioned portion 302b on one side L1. Fig. 12 is a front view illustrating how the distance d between the print head 3 and the photosensitive drum 1 is maintained constant regardless of the inclination of the print head 3 around the swing axis β.

[0056] Image forming apparatus 100 further includes a positioning mechanism 300 (an example of a positioning means). Positioning mechanism 300 positions print head 3 relative to photosensitive drum 1 so as to maintain a constant distance d (focal length) between print head 3 and photosensitive drum 1, regardless of the tilt of print head 3 around swing axis β caused by tilt adjustment mechanism 200. Here, "maintaining a constant distance d" not only refers to maintaining a constant focal length of print head 3, but also includes maintaining a constant focal length of print head 3 within an allowable range (depth of focus) (for example, ±0.1 mm).

[0057] 12, in image forming apparatus 100 according to this embodiment, when adjusting the tilt of print head 3 around swing axis β, print head 3 moves along the circumferential direction S of photosensitive drum 1, so the distance d (d1, d2, d3) between photosensitive drum 1 and print head 3 can be kept constant (d1 = d2 = d3) depending on the position of print head 3 in the circumferential direction S. This becomes more effective as the diameter (curvature) of photosensitive drum 1 becomes smaller as image forming apparatus 100 becomes more compact.

[0058] As described above, according to this embodiment, the positioning mechanism 300 can maintain a constant distance d between the print head 3 and the photosensitive drum 1 regardless of the tilt of the print head 3 around the swing axis β caused by the tilt adjustment mechanism 200. This makes it possible to maintain a constant distance d between the print head 3 and the photosensitive drum 1 regardless of the tilt of the print head 3 around the swing axis β caused by the tilt adjustment mechanism 200.

[0059] [First embodiment] In this embodiment, the positioning mechanism 300 includes positioning portions 301 (301a, 301b) and positioned portions 302 (302a, 302b). The positioning portions 301 (301a, 301b) are provided on the print head 3 and determine the position of the print head 3 relative to the photosensitive drum 1. The positioned portions 302 (302a, 302b) are provided on a main body member (in this example, a housing 401 of the photosensitive drum 1 (see FIG. 8)) that is a member on the main body side of the image forming apparatus 100 and abut against the positioning portions 301 (301a, 301b). The positioned portion 302 (in this example, the positioned portion 302a on one side L1) has an arc-shaped portion 3021 that is concentric with the rotation center (rotation axis α) of the photosensitive drum 1 and is larger than the radius r1 of the photosensitive drum 1 (see FIG. 9D). Specifically, the positioned portion 302 (302a) has an arc-shaped portion 3021 formed along an imaginary arc δ whose arc center is concentric with the rotation center (α) of the photosensitive drum 1 and whose arc radius r2 (see FIG. 9D) is larger than the radius r1 of the photosensitive drum 1. That is, the arc-shaped portion 3021 has an arc radius r2 (r1 + r3) obtained by adding a predetermined distance r3 (see FIG. 9D) to the radius r1 of the photosensitive drum. The arc-shaped portion 3021 has a contact surface 3021a that comes into contact with the positioning portion 301 (301a).

[0060] With this configuration, even when the print head 3 is swung around the swing axis β by the tilt adjustment mechanism 200, the positioning portions 301 (301a, 301b) abut against the abutment surfaces 3021a (see FIGS. 9D and 9E) of the arc-shaped portions 3021 of the positioned portions 302, thereby positioning the print head 3 so as to maintain a constant distance d between the print head 3 and the photosensitive drum 1. Furthermore, by abutting the positioning portions 301 (301a, 301b) against the positioned portions 302 (302a, 302b), a configuration can be easily realized in which the distance d (see FIG. 12) between the print head 3 and the photosensitive drum 1 is maintained constant.

[0061] <First embodiment-1> In this embodiment, the print head 3 includes a lens holding member 313 and a fixing member 314 (see FIGS. 5B, 5C, etc.). The lens holding member 313 holds the lens array 32. The fixing member 314 fixes the light emitting element substrate 311 or the panel. The positioning portions 301 (301a, 301b) are provided on the lens holding member 313.

[0062] In this configuration, by providing positioning portions 301 (301a, 301b) on lens holding member 313 that holds lens array 32, it is possible to accurately determine the position of print head 3 equipped with lens array 32 relative to photosensitive drum 1. Moreover, there is no need to prepare a separate member for providing positioning portions 301 (301a, 301b), which allows image forming apparatus 100 to be made smaller and at lower costs.

[0063] <First embodiment-2> In this embodiment, the positioning mechanism 300 further includes biasing members 316 (316a, 316b) that bias the positioning portions 301 (301a, 301b) toward the main body side member (in this example, the housing 401 of the photosensitive drum 1). The positioned portions 302 (302a, 302b) are biased by the biasing members 316 (316a, 316b) to abut against the positioning portions 301 (301a, 301b). Here, the multiple holding portions 315a3, 315a3 of the lens holding member 313 provided with the positioning portions 301 (301a, 301b) have the effect of restricting excessive movement of the fixing member 314 toward the main body side member (401) by the biasing members 316 (316a, 316b).

[0064] In this configuration, the biasing member 316 (316a, 316b) can reliably bring the positioning portion 301 (301a, 301b) into contact with the positioned portion 302 (302a, 302b), thereby stably maintaining the distance d between the print head 3 and the photosensitive drum 1.

[0065] In this example, the positioning portion 301 is a pair of positioning portions 301a, 301b provided on both sides of the print head 3 in the longitudinal direction L. The positioned portion 302 is a pair of positioned portions 302a, 302b corresponding to the pair of positioning portions 301a, 301b, respectively. The pair of positioning portions 301a, 301b are provided on both ends in the longitudinal direction L (outside the lens array 32) on a surface 313b of the lens holding member 313 facing the lens array 32. The urging member 316 is a pair of urging members 316a, 316b.

[0066] The positioning mechanism 300 further includes a pair of elevating members 317a, 317b. The pair of elevating members 317a, 317b are provided at both ends (outside the print head 3) in the longitudinal direction L of the swinging unit main body 211 so as to be movable in the optical axis direction N. The print head 3 is provided so as to be movable in the optical axis direction N relative to the pair of elevating members 317a, 317b. The print head 3 is urged toward the photosensitive drum 1 by a pair of urging members 316a, 316b arranged between the pair of elevating members 317a, 317b, with movement of the print head 3 to one side N1 in the optical axis direction N restricted by restricting portions 317a1, 317b1.

[0067] More specifically, insertion protrusions (317c, 317d), (317c, 317d) are provided on a surface 317g of the pair of lifting members 317a, 317b facing the swinging unit 210. The insertion protrusions (317c, 317d), (317c, 317d) extend toward the print head 3 (one side N1) in the optical axis direction N. The back surface 314b of the fixed member 314 is provided with insertion recesses (314d, 314e), (314d, 314e) (see FIGS. 9C and 10C) into which the insertion protrusions (317c, 317d), (317c, 317d) are inserted, respectively. This allows the print head 3 to be restricted in the longitudinal direction L and width direction M relative to the pair of elevating members 317a, 317b, while allowing the print head 3 to move freely in the optical axis direction N relative to the pair of elevating members 317a, 317b. The pair of urging members 316a, 316b are coil springs, and are inserted into insertion protrusions 317c, 317c on one side M1 between the fixed member 314 and the pair of elevating members 317a, 317b. This allows the print head 3 to be urged toward the photosensitive drum 1 relative to the pair of elevating members 317a, 317b.

[0068] The pair of lifting members 317a, 317b are provided with restricting portions 317a1, 317b1. The pair of lifting members 317a, 317b and the restricting portions 317a1, 317b1 are integrally formed. The restricting portions 317a1, 317b1 detachably restrict movement of the fixed member 314 of the print head 3 to one side N1 in the optical axis direction N. The restricting portions 317a1, 317b1 have locking portions 317a11, 317b11 that lock the surface 314a of the fixed member 314.

[0069] However, since the photosensitive drum 1 and the print head 3 are close to each other, when an operator replaces the photosensitive drum 1, the photosensitive drum 1 may come into contact with the print head 3 when inserting or removing the photosensitive drum 1 in the direction of the rotation axis X relative to the image forming apparatus main body 101.

[0070] In this regard, the positioning mechanism 300 further includes an actuating member 318 that raises and lowers the pair of lifting members 317a, 317b. The actuating member 318 is movable in the longitudinal direction L relative to the swinging portion main body 211, and raises and lowers the pair of lifting members 317a, 317b by movement in the longitudinal direction L.

[0071] More specifically, insertion protrusions (211g, 211g), (211g, 211g) are provided upright on both ends in the longitudinal direction L of the surface 211f of the swinging unit main body 211 on the print head 3 side. The insertion protrusions (211g, 211g), (211g, 211g) extend toward one side N1 in the optical axis direction N. The pair of lifting members 317a, 317b have insertion recesses (317f, 317f), (317f, 317f) (see FIGS. 9C and 10C) that insert the insertion protrusions (211g, 211g), (211g, 211g), respectively, on their back surfaces 317e on the swinging unit 210 side. This allows the pair of lifting members 317a, 317b to be restricted in the longitudinal direction L and width direction M relative to the oscillating portion main body 211, while allowing the pair of lifting members 317a, 317b to be freely movable in the optical axis direction N relative to the oscillating portion main body 211.

[0072] The actuating member 318 is provided between the pair of lifting members 317a, 317b and the surface 211f of the swinging unit main body 211. The actuating member 318 is provided with multiple (two) inclined surfaces 318a, 318a and top surfaces 318b, 318b. The inclined surfaces 318a, 318a are inclined so as to slide against the pair of lifting members 317a, 317b as the actuating member 318 moves toward or away from the photosensitive drum 1 as it moves toward or away from the photosensitive drum 1 in the longitudinal direction L. The pair of lifting members 317a, 317b are also provided with inclined surfaces 317h, 317h (see FIGS. 9B and 10B). The inclined surfaces 317h, 317h are provided at locations corresponding to the inclined surfaces 318a, 318a of the operating member 318 of the pair of lifting members 317a, 317b, and are inclined along the inclined surfaces 318a, 318a.

[0073] In the configuration described above, when an operator moves the operating member 318 from the first position where the pair of lifting members 317a, 317b are farthest from the photosensitive drum 1 to the other side L2 in the longitudinal direction L, the inclined surfaces 318a, 318a slide against the inclined surfaces 317h, 317h of the pair of lifting members 317a, 317b. At this time, the biasing forces of the biasing members 316a, 316b act on the pair of lifting members 317a, 317b, causing the pair of lifting members 317a, 317b to approach (rise) the photosensitive drum 1. When the operating member 318 further moves toward the other side L2 in the longitudinal direction L and the top surfaces 318b, 318b come into contact with the back surfaces 317e of the pair of lifting members 317a, 317b, the pair of lifting members 317a, 317b are maintained at the second position where they are closest to the photosensitive drum 1. As a result, the print head 3 approaches the photosensitive drum 1 at a predetermined distance d, and an image can be formed.

[0074] On the other hand, when the operator moves the actuating member 318 from the second position toward one side L1 in the longitudinal direction L, the top surfaces 318b of the actuating member 318 move away from the back surfaces 317e of the pair of actuating members 317a and 317b, and the inclined surfaces 318a slide against the inclined surfaces 317h of the pair of actuating members 317a and 317b. At this time, the biasing forces of the biasing members 316a and 316b acting on the pair of actuating members 317a and 317b are released, and the pair of actuating members 317a and 317b move away from (descend from) the photosensitive drum 1. When the actuating member 318 moves further toward the one side L1 in the longitudinal direction L, the pair of actuating members 317a and 317b return to the first position. This makes it possible to prevent the photosensitive drum 1 from coming into contact with the print head 3 when an operator replaces the photosensitive drum 1 .

[0075] <First embodiment-3> In this embodiment, the positioning portion 301a on one side L1 (front side X1 in this example) of the pair of positioning portions 301a, 301b has a convex portion 301a1 extending in the longitudinal direction L. Of the pair of positioned portions 302a, 302b, the positioned portion 302a on one side L1 corresponding to the positioning portion 301a on one side L1 has an arc-shaped portion 3021. The arc-shaped portion 3021 has an abutment surface 3021a that abuts against the convex portion 301a1 of the positioning portion 301a on one side L1. In this example, the convex portion 301a1 has a mountain-like shape in cross section as seen from the rotation axis direction X.

[0076] In this configuration, the convex portion 301a1 that abuts against the arc-shaped portion 3021 extends in the longitudinal direction L, so that the convex portion 301a1 can be brought into abutment against the arc-shaped portion 3021 stably and reliably.

[0077] <First embodiment-4> In this embodiment, the positioning portion 301b on the other side L2 (rear side X2 in this example) of the pair of positioning portions 301a, 301b has a swing shaft 301b1 centered on a swing axis β (see FIGS. 3 and 6A). The print head 3 is rotatable around the swing shaft 301b1. The positioned portion 302b on the other side L2 of the pair of positioned portions 302a, 302b, which corresponds to the positioning portion 301b on the other side L2, has a recessed portion 302b1 (groove portion) (see FIGS. 10D and 10E) extending in the longitudinal direction L. The recessed portion 302b1 engages with the swing shaft 301b1 of the positioning portion 301b on the other side L2.

[0078] In this configuration, the concave portion 302b1 in the positioned portion 302b on the other side L2 engages with the swing shaft 301b1 in the positioning portion 301b on the other side L2, allowing for some leeway in the attachment position of the print head 3 to the main body side member (401) in the longitudinal direction L. Even if the print head 3 deviates slightly in the longitudinal direction L from the reference position relative to the main body side member (401) within an allowable range, the deviation of the image in the longitudinal direction L can ultimately be corrected in image processing.

[0079] Furthermore, the positioning portion 301 is a pair of positioning portions 301a, 301b provided on both sides of the print head 3 in the longitudinal direction L. The positioned portion 302 is a pair of positioned portions 302a, 302b corresponding to the pair of positioning portions 301a, 301b, respectively. This allows the pair of positioning portions 301a, 301b to be more reliably abutted against the positioned portions 302a, 302b by the biasing members 316a, 316b, and thereby makes it possible to more stably maintain the distance d between the print head 3 and the photosensitive drum 1 constant.

[0080] <First embodiment-5> Fig. 13A is an exploded perspective view of the positioning portion 301a on one side L1 and the lens holding member 313, viewed obliquely from below. Fig. 13B is a perspective view of the positioning portion 301a on one side L1 attached to the lens holding member 313, viewed obliquely from below. Fig. 14A is a perspective view of the positioning portion 301a on one side L1, viewed from above on the rear side X2. Fig. 14B is a perspective view of the positioning portion 301a on one side L1, viewed from below on the front side X1.

[0081] Fig. 15A is an exploded perspective view of the positioning portion 301b on the other side L2 and the lens holding member 313, viewed obliquely from below. Fig. 15B is a perspective view of the positioning portion 301b on the other side L2 attached to the lens holding member 313, viewed obliquely from below. Fig. 16A is a perspective view of the positioning portion 301b on the other side L2, viewed from above on the rear side X2. Fig. 16B is a perspective view of the positioning portion 301b on the other side L2, viewed from below on the front side X1.

[0082] In this embodiment, the positioning units 301 (301a, 301b) are detachably provided on the lens holding member 313 of the print head 3. The positioning units 301 (301a, 301b) are provided with anti-slip units 3011 for preventing the positioning units 301 (301a, 301b) from slipping out of the lens holding member 313.

[0083] In this configuration, the positioning portions 301 (301a, 301b) are detachably provided on the lens holding member 313, which improves the workability of attaching and detaching the positioning portions 301 (301a, 301b) to and from the lens holding member 313. In addition, by providing the positioning portions 301 (301a, 301b) with the slip-out prevention portions 3011, it is possible to effectively prevent the positioning portions 301 (301a, 301b) from easily coming off the lens holding member 313.

[0084] In this example, the positioning portions 301 (301a, 301b) can be attached and detached by moving them in the longitudinal direction L relative to the lens holding member 313. The lens holding member 313 is provided with a through-hole penetrating in the optical axis direction N (thickness direction) or a recess (through-hole 3131 in this example) recessed in the optical axis direction N. The slip-out prevention portion 3011 in the positioning portions 301 (301a, 301b) has a protrusion 3011a that protrudes toward the lens holding member 313 in the optical axis direction N (the other side N2). The protrusion 3011a is fitted into the through-hole or recess (through-hole 3131) in the lens holding member 313.

[0085] In this configuration, the positioning units 301 (301a, 301b) can be attached and detached by moving them in the longitudinal direction L relative to the lens holding member 313, which makes it easy to attach and detach the positioning units 301 (301a, 301b) from the lens holding member 313 in the longitudinal direction L. Furthermore, by providing the positioning units 301 (301a, 301b) with protrusions 3011a and providing the lens holding member 313 with a through-hole or recess (through-hole 3131), it is possible to easily realize a configuration that prevents the positioning units 301 (301a, 301b) from coming off the lens holding member 313.

[0086] More specifically, the positioning portion 301 (301a, 301b) has a rod-shaped portion 3012 extending in the optical axis direction N, and a pair of flat plate portions 3013, 3014 provided at both ends of the rod-shaped portion 3012 in the optical axis direction N. A convex portion 301a1 is provided on the positioning portion 301a on one side L1 in the longitudinal direction L, opposite the rod-shaped portion 3012 of the flat plate portion 3013 on one side N1 in the optical axis direction N. A swing shaft 301b1 is provided on the positioning portion 301b on the other side L2 in the longitudinal direction L, opposite the rod-shaped portion 3012 of the flat plate portion 3013 on one side N1 in the optical axis direction N. The sizes h1 and h2 (see FIGS. 13A and 15A) of the flat portions 3013 and 3014 in the width direction M in the optical axis direction N are larger than the size h3 (see FIGS. 13A and 15A) of the rod-shaped portion 3012 in the width direction M (h1>h3, h2>h3).

[0087] The positioned portion 302 (302a, 302b) has a first insertion portion 3132 through which the rod-shaped portion 3012 is inserted in the longitudinal direction L, and a second insertion portion 3133 through which the flat plate portion 3014 on the other side N2 is inserted in the longitudinal direction L. A size h4 in the width direction M of the second insertion portion 3133 (see FIGS. 13A and 15A) is larger than a size h2 in the width direction M of the flat plate portion 3014 on the other side N2 by a predetermined size to allow smooth insertion of the flat plate portion 3014 on the other side N2 (h4>h2). A size h5 in the width direction M of the first insertion portion 3132 (see FIGS. 13A and 15A) is larger than a size h3 in the width direction M of the rod-shaped portion 3012 by a predetermined size to allow smooth insertion of the rod-shaped portion 3012 (h5>h3). Also, the size h4 of the second insertion portion 3133 in the width direction M is larger than the size h5 of the first insertion portion 3132 in the width direction M (h4>h5).

[0088] In this way, by moving the positioning portion 301 (301a, 301b) in the longitudinal direction L relative to the lens holding member 313 and fitting the protrusion 3011a into the through hole 3131, it is possible to effectively prevent the positioning portion 301 (301a, 301b) from coming off the lens holding member 313.

[0089] [Second embodiment] Fig. 17 is a side view showing another example of the positioning mechanism 300. Figs. 18A and 18B are front and rear views, respectively, of the guide mechanism 330 shown in Fig. 17. Note that the tilt adjustment unit 230 is not shown in Figs. 17 to 18B. Fig. 19 is a front view illustrating how the distance d between the print head 3 and the photosensitive drum 1 is maintained constant and the optical axes of the multiple light-emitting elements 31 in the print head 3 are directed toward the center of rotation (α) of the photosensitive drum 1, regardless of the tilt of the print head 3 around the swing axis β.

[0090] The second embodiment is similar to the first embodiment except that the swing support portion 220 in the first embodiment is removed and a guide mechanism 330 is provided, and the same components are given the same reference numerals and their description will be omitted.

[0091] In the image forming apparatus 100 according to the first embodiment, as the print head 3 tilts around the swing axis β, the optical axes of the plurality of light-emitting elements 31-31 in the print head 3 move in parallel. Furthermore, since the surface 1a of the photosensitive drum 1 is curved, depending on the position on the surface 1a of the photosensitive drum 1 of the light emitted by the plurality of light-emitting elements 31-31, the beam spot on the surface 1a of the photosensitive drum 1 may not have the desired shape (preferably a circular shape), which will result in a deterioration in image quality.

[0092] In this regard, in this embodiment, the positioning mechanism 300 positions the print head 3 with respect to the photosensitive drum 1 so that the optical axes of the multiple light-emitting elements 31-31 in the print head 3 are directed toward the center of rotation (α) of the photosensitive drum 1, regardless of the tilt of the print head 3 around the swing axis β by the tilt adjustment mechanism 200. Here, the phrase "the optical axes of the multiple light-emitting elements 31-31 are directed toward the center of rotation (α) of the photosensitive drum 1" is a concept that includes not only the case where the optical axes of the light-emitting elements 31-31 pass through the center of rotation (α) of the photosensitive drum 1, but also the case where the beam spot irradiated on the surface 1a of the photosensitive drum 1 has an acceptable shape (a shape that can maintain image quality).

[0093] In this configuration, regardless of the inclination of the print head 3 around the swing axis β, the optical axes of the multiple light-emitting elements 31-31 point toward the center of rotation (α) of the photosensitive drum 1, so that regardless of the position of the light emitted by the multiple light-emitting elements 31-31 on the surface 1a of the photosensitive drum 1, the beam spot on the surface 1a of the photosensitive drum 1 can be made into the desired shape (preferably circular), thereby effectively preventing degradation of image quality.

[0094] <Second embodiment-1> In this embodiment, the positioning mechanism 300 includes a guide mechanism 330 (an example of a guide means). When the tilt adjustment mechanism 200 tilts the print head 3 about the swing axis β, the guide mechanism 330 maintains the distance d between the print head 3 and the photosensitive drum 1, and guides the print head 3 along the imaginary arc δ so that an imaginary straight line φ (see FIG. 18A ) along the substrate surface 311a of the light-emitting element substrate 311 becomes a tangent to the imaginary arc δ whose center is concentric with the rotation center (α) of the photosensitive drum 1 and whose arc radius r2 (r1+r3) is larger than the radius r1 of the photosensitive drum 1.

[0095] In this configuration, by using a guide mechanism 330 that guides the print head 3 along the virtual arc δ, it is possible to easily realize a configuration in which the optical axes of the multiple light-emitting elements 31-31 in the print head 3 are directed toward the center of rotation (α) of the photosensitive drum 1.

[0096] <Second embodiment-2> In this embodiment, guide mechanism 330 includes print head guide 331 and print head rotation unit 332. Print head guide 331 guides one side L1 in the longitudinal direction L of print head 3 along an imaginary arc δ relative to image forming apparatus main body 101. Print head rotation unit 332 allows the other side L2 in the longitudinal direction L of print head 3 to rotate (be rotatable) relative to image forming apparatus main body 101 about a rotation axis λ (see FIG. 18B) along the longitudinal direction L.

[0097] In this configuration, the print head 3, which is rotatable about the rotation axis λ on the other side L2 in the longitudinal direction L by the print head rotation part 332, can be guided along the imaginary arc δ on one side L1 in the longitudinal direction L by the print head guide part 331. This allows the print head 3 to move stably along the imaginary arc δ.

[0098] More specifically, the print head guide 331 includes a guide member 3311 and a guided member 3312. The guide member 3311 is fixed to an end portion on one side L1 in the longitudinal direction L of the print head 3 (in this example, the back surface 211e of the swinging portion main body 211) by a fastening member (male screw) (not shown) or the like.

[0099] The guide member 3311 is formed by stamping and bending a metal plate, and has a guide member main body 3311a and a bent portion 3311b. The guide member main body 3311a is fixed to the print head 3 and extends from the print head 3 to one side L1 in the longitudinal direction L. The bent portion 3311b is bent from the tip of the guide member main body 3311a in the up-down direction Z (downward in this example). The bent portion 3311b is provided with an arc-shaped through-hole 3311c (see FIG. 18A) formed along an imaginary arc δ. The image forming apparatus main body 101 (in this example, the main body frame FL1 on the front side X1) is provided with a guided member 3312 that is inserted through the arc-shaped through-hole 3311c.

[0100] The guided member 3312 is a cylindrical member provided in the image forming apparatus main body 101. In this example, the guided member 3312 is fixed (in this example, crimped and fixed by caulking using plastic deformation of metal) to the main body frame FL1 on the front side X1 so that the axial direction of the guided member 3312 is aligned with the rotational axis direction X of the photosensitive drum 1. The guided member 3312 protrudes from the main body frame FL1 toward the front side X1. A bent portion 3311b of the guiding member 3311 causes the guided member 3312 to pass through the arc-shaped through-hole 3311c at a position closer to the front side X1 than the main body frame FL1. Note that the guided member 3312 has a circular shape in cross section as viewed from the axial direction, but may be formed into a shape that follows the arc-shaped through-hole 3311c.

[0101] The print head rotating part 332 includes a support member 3321 and an axis member 3322. The support member 3321 is fixed to an end portion on the other side L2 in the longitudinal direction L of the print head 3 (in this example, the back surface 211e of the swinging part main body 211) by a fastening member (male screw) (not shown) or the like.

[0102] The support member 3321 is formed by stamping and bending a metal plate, and has a support member main body 3321a and a bent portion 3321b. The support member main body 3321a is fixed to the print head 3 and extends from the print head 3 to the other side L2 in the longitudinal direction L. The bent portion 3321b is bent from the tip of the support member main body 3321a in the up-down direction Z (downward in this example). A circular through-hole FL2b (see FIG. 17) that penetrates in a circular shape is provided in the image forming apparatus main body 101 (in this example, the main body frame FL2 on the rear side X2). A shaft member 3322 that is inserted into the circular through-hole FL2b is provided in the bent portion 3321b.

[0103] The shaft member 3322 is a columnar member provided at the bent portion 3321b, and in this example, the shaft member 3322 is fixed (in this example, crimped and fixed by caulking) to the main body frame FL2 so that the axial direction of the shaft member 3322 is aligned with the rotational axis direction X of the photosensitive drum 1. The bent portion 3321b of the support member 3321 is located closer to the front side X1 (inner side) than the main body frame FL2. The shaft member 3322 is inserted into a circular through-hole FL2b in the main body frame FL2 and protrudes from the main body frame FL2 to the rear side X2.

[0104] In the configuration described above, the guide mechanism 330 can direct the optical axes of the multiple light-emitting elements 31-31 in the print head 3 toward the rotation center (α) of the photosensitive drum 1 regardless of the inclination of the print head 3 around the swing axis β.

[0105] [Third embodiment] In the present embodiment, in the first and second embodiments, the main body side member is a casing (in this example, housing 401 of photosensitive drum 1) (see FIG. 8) that supports photosensitive drum 1 rotatably around rotation axis α of photosensitive drum 1. Positioned portions 302 (302a, 302b) are provided integrally with casing (401). In other words, it is casing (401) that is provided integrally with positioned portions 302 (302a, 302b).

[0106] In this configuration, the positioned portions 302 (302a, 302b) are integrally provided on the housing (401) of the photosensitive drum 1, so there is no need to prepare a separate member for providing the positioned portions 302 (302a, 302b), thereby enabling the image forming apparatus 100 to be made smaller and at lower costs.

[0107] Specifically, the positioned portions 302 (302a, 302b) are integrally formed with housings 401 (see FIG. 8) on both outer sides in the rotational axis direction X of the photosensitive drum 1 in the photosensitive unit 400. The housing of the photosensitive drum 1 may be provided in the image forming apparatus main body 101.

[0108] The present disclosure is not limited to the above-described embodiments, but can be implemented in various other forms. Therefore, the embodiments are merely examples in all respects and should not be interpreted as being limiting. The scope of the present disclosure is defined by the claims and is not bound by the text of the specification. Furthermore, all modifications and variations within the equivalent scope of the claims are within the scope of the present disclosure. [Explanation of symbols]

[0109] 1. Photosensitive drum (an example of an image carrier) 1a surface 100 Image forming device 101 Image forming apparatus main body 200 Tilt adjustment mechanism (an example of tilt adjustment means) 210 Swinging part 211 Swinging unit body 220 Swing support part 221 Protrusion 230 Tilt adjustment unit 231 Connecting members 232 Moving parts 233 biasing member 234 Adjustment member 3 print head 300 Positioning mechanism (an example of a positioning means) 301 Positioning part 301a Positioning part on one side 301b Positioning part on the other side 3011 Fall-out prevention part 3011a Protrusion 302 Positioned part 302a Positioned part on one side 302b Positioned part on the other side 3021 Arc-shaped part 3021a Contact surface 302b1 Concave part 31-31 Multiple light-emitting elements 311 Light emitting element substrate (an example of a substrate) 311a Board surface 313 Lens holding member 314 Fixing member 315 Main body member 316 biasing member 316a One side biasing member 316b Other side biasing member 32 Lens Array 330 Guidance mechanism 331 Print head guide 332 Print head rotating part 400 Photoconductor unit 401 Photosensitive drum housing (an example of a housing) FL main frame L Longitudinal direction M Width direction N Optical axis direction R Rotation direction S circumferential direction X rotation axis direction Y left / right direction Z vertical direction d distance r1 Radius of the photosensitive drum r2 Radius of the virtual arc r3 specified distance α rotation axis β Swing axis δ Virtual arc φ Imaginary line λ Rotation axis

Claims

1. an image carrier; a long print head including a substrate having a plurality of light-emitting elements arranged in a line and a lens array that focuses light emitted by the plurality of light-emitting elements onto the image carrier; tilt adjustment means for adjusting the tilt of the print head around a swing axis along the optical axis of the plurality of light-emitting elements; An image forming apparatus comprising: an image forming apparatus comprising: a positioning means for positioning the print head relative to the image carrier so as to maintain a constant distance between the print head and the image carrier, regardless of the tilt of the print head about the swing axis caused by the tilt adjustment means.

2. 2. The image forming apparatus according to claim 1, The positioning means is a positioning unit provided on the print head to determine the position of the print head relative to the image carrier; a positioned portion provided on a main body side member that is a member on the main body side of the image forming apparatus and abutting against the positioning portion; Equipped with an image forming apparatus characterized in that the positioned portion has an arc-shaped portion that is concentric with the rotation center of the image carrier and is larger than the radius of the image carrier, and the arc-shaped portion has an abutment surface that abuts against the positioning portion.

3. 3. The image forming apparatus according to claim 2, the print head includes a lens holding member that holds the lens array and a fixing member that fixes the substrate or panel; The image forming apparatus, wherein the positioning portion is provided on the lens holding member.

4. 3. The image forming apparatus according to claim 2, the positioning means further includes a biasing member that biases the positioning portion toward the main body side member, The image forming apparatus according to claim 1, wherein the positioned portion is biased by the biasing member to come into contact with the positioning portion.

5. 5. The image forming apparatus according to claim 4, the positioning portions are a pair of positioning portions provided on both sides of the print head in the longitudinal direction, the positioned portions are a pair of positioned portions respectively corresponding to the pair of positioning portions, one of the pair of positioning portions has a convex portion extending in the longitudinal direction, An image forming apparatus characterized in that one of the pair of positioned portions corresponding to the positioning portion on one side has the arc-shaped portion, and the abutment surface of the arc-shaped portion abuts against the convex portion of the positioning portion on one side.

6. 5. The image forming apparatus according to claim 4, the positioning portions are a pair of positioning portions provided on both sides of the print head in the longitudinal direction, the positioned portions are a pair of positioned portions respectively corresponding to the pair of positioning portions, the other of the pair of positioning units has a swing shaft centered on the swing axis line, and the print head is rotatable around the swing shaft; An image forming apparatus characterized in that the other positioned portion of the pair of positioned portions corresponding to the other positioning portion has a concave portion extending in the longitudinal direction, and the concave portion engages with the swing shaft in the other positioning portion.

7. 4. The image forming apparatus according to claim 3, the positioning portion is detachably provided on the lens holding member of the print head, The image forming apparatus according to claim 1, wherein the positioning portion is provided with a fall-off prevention portion for preventing the lens from falling off the lens holding member.

8. 8. The image forming apparatus according to claim 7, the positioning portion is detachable from the lens holding member in the longitudinal direction of the print head, the lens holding member is provided with a through-hole penetrating in the optical axis direction or a recess recessed in the optical axis direction, An image forming apparatus characterized in that the anti-slip portion in the positioning portion has a protrusion that protrudes toward the lens holding member in the optical axis direction, and the protrusion is engaged with the through hole or the recess in the lens holding member.

9. 3. The image forming apparatus according to claim 2, the main body side member is a housing that supports the image carrier rotatably around a rotation axis of the image carrier, The image forming apparatus is characterized in that the positioned portion is provided integrally with the housing.

10. 2. The image forming apparatus according to claim 1, wherein the positioning device positions the print head relative to the image carrier so that the optical axes of the plurality of light-emitting elements in the print head are directed toward the center of rotation of the image carrier, regardless of the tilt of the print head around the swing axis caused by the tilt adjustment device.

11. 11. The image forming apparatus according to claim 10, and a guide means for guiding the print head along the imaginary arc so that, when the print head is tilted around the swing axis by the tilt adjustment means, a virtual straight line along the substrate surface of the substrate becomes a tangent to the imaginary arc whose center is concentric with the center of rotation of the image carrier and whose radius is larger than the radius of the image carrier, while maintaining the distance between the print head and the image carrier.

12. 12. The image forming apparatus according to claim 11, the guiding means comprises: a print head guide portion that guides one side of the print head in the longitudinal direction relative to the image forming device body along the imaginary arc; and a print head rotation portion that allows the other side of the print head in the longitudinal direction to rotate about a rotation axis along the longitudinal direction relative to the image forming device body.

13. 2. The image forming apparatus according to claim 1, The image forming apparatus is characterized in that the substrate is a film-like substrate provided with an organic EL diode element.

Images