Exposure head

Abstract

To inhibit deterioration of optical performance caused due to displacement of a substrate with respect to a housing.SOLUTION: An exposure head 4 includes: a first adhesive 77a which bonds a housing 54 and a substrate 50 to each other, is hardened at a first rate, and has a first elastic modulus after hardening; and a second adhesive 77c which bonds the housing 54 and the substrate 50 to each other, is hardened at a second rate, and has a second elastic modulus after hardening. The second rate is higher than the first rate, and the first elastic modulus is higher than the second elastic modulus.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an exposure head that exposes an image carrier. [Background technology]

[0002] Conventional electrophotographic image forming apparatuses form an electrostatic latent image by selectively exposing a photoreceptor to light, and then develop the electrostatic latent image with toner to form an image. An example of an exposure device for such an image forming apparatus is an LED exposure device using an LED array. The LED exposure device generally comprises a printed circuit board on which light-emitting chips are arranged, a lens array, and a housing to which the printed circuit board and lens array are bonded and fixed with an adhesive after they are positioned.

[0003] Patent Document 1 discloses an exposure device in which the position of the printed circuit board is adjusted in the longitudinal and width directions perpendicular to the optical axis of the light emitted from the light-emitting chip, and the printed circuit board is brought into contact with the housing, and then the printed circuit board and the housing are bonded and fixed together using an adhesive made of a photocurable resin. In the exposure device described above, the light-emitting chip generates heat as it emits light, causing the temperature of the entire exposure device to rise. If the housing and the printed circuit board have different linear expansion coefficients, a difference in the expansion coefficients between the housing and the printed circuit board will occur as the temperature rises, and there is a risk that the printed circuit board bonded to the housing will peel off. For this reason, it is desirable for the printed circuit board to be firmly bonded to the housing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-049713 Summary of the Invention [Problem to be solved by the invention]

[0005] However, some adhesives used to bond the printed circuit board to the housing take a long time to harden, which can lead to a risk of the printed circuit board shifting position relative to the housing during the hardening process, resulting in a deterioration in the optical performance of the exposure device.

[0006] An object of the present invention is to provide an exposure head that can suppress a decrease in optical performance caused by misalignment of the substrate relative to the housing. [Means for solving the problem]

[0007] The exposure head of the present invention is an exposure head that exposes a photosensitive body, and comprises: a light-emitting chip arranged in the direction of the rotation axis of the photosensitive body and having a plurality of light-emitting units that emit light to expose the photosensitive body; a substrate on which the light-emitting chip is mounted; a lens that focuses the light emitted by the light-emitting chip onto the surface of the photosensitive body; a housing that holds the substrate and the lens; a first adhesive that bonds the housing and the substrate, the first adhesive curing at a first speed and having a first elastic modulus after curing; and a second adhesive that bonds the housing and the substrate, the second adhesive curing at a second speed and having a second elastic modulus after curing, wherein the second speed is faster than the first speed and the first elastic modulus is higher than the second elastic modulus. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress a deterioration in optical performance caused by a misalignment of the substrate relative to the housing. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view of an image forming apparatus according to an embodiment of the present invention; [Figure 2] 2 is a schematic diagram illustrating a state in which an exposure head of the image forming apparatus according to the embodiment of the present invention is in proximity to a photosensitive drum. [Figure 3] 2 is a schematic diagram illustrating a state in which an exposure head of the image forming apparatus according to the embodiment of the present invention is separated from a photosensitive drum. FIG. [Figure 4] 1 is a perspective view of an image forming apparatus according to an embodiment of the present invention with a front cover open; [Figure 5] 2 is an enlarged perspective view of the image forming apparatus according to the embodiment of the present invention with an inner door open; FIG. [Figure 6] 2 is an enlarged perspective view of the image forming apparatus according to the embodiment of the present invention, with the drum unit pulled out. FIG. [Figure 7] 2 is an enlarged perspective view of the image forming apparatus according to the embodiment of the present invention, with a developing unit pulled out. FIG. [Figure 8] 1 is a perspective view of an image forming apparatus according to an embodiment of the present invention, with an inner door of the cartridge tray closed; [Figure 9] 1 is a perspective view of an image forming apparatus according to an embodiment of the present invention, with an inner door of a cartridge tray opened. [Figure 10] 1 is a cross-sectional view of an exposure head according to an embodiment of the present invention. [Figure 11] 1 is a perspective view of an exposure head according to an embodiment of the present invention, as viewed from above; [Figure 12] FIG. 2 is a perspective view of the exposure head according to the embodiment of the present invention, as seen from below. [Figure 13] 2 is a schematic diagram of a substrate and a lens array of an exposure head according to an embodiment of the present invention. [Figure 14] 2 is a perspective view of the substrate of the exposure head according to the embodiment of the present invention, seen from the side on which LEDs are mounted. FIG. [Figure 15] 1 is a perspective view of an exposure head circuit board according to an embodiment of the present invention, seen from the side on which a connector is mounted. [Figure 16] 1 is a perspective view of a substrate of an exposure head according to an embodiment of the present invention, when the substrate is assembled into a housing, as viewed from the side on which LEDs are mounted on the substrate. [Figure 17] 1 is a perspective view of a substrate of an exposure head according to an embodiment of the present invention, the substrate being assembled into a housing, as viewed from the side on which a connector is mounted on the substrate; [Figure 18]1 is a perspective view of a state in which a substrate and a lens array of an exposure head according to an embodiment of the present invention are assembled into a housing. [Figure 19] 1 is a perspective view of a cartridge tray of an image forming apparatus according to an embodiment of the present invention. [Figure 20] 3 is a bottom view of the cartridge tray and the lift duct of the image forming apparatus according to the embodiment of the present invention. FIG. [Figure 21] 20 is a cross-sectional view taken along the line XX in FIG. 19, showing a state in which the exposure head according to the embodiment of the present invention is located at the exposure position. [Figure 22] 20 is a cross-sectional view taken along the line XX in FIG. 19, showing a state in which the exposure head according to the embodiment of the present invention is located at a retracted position. [Figure 23] 20 is a cross-sectional view taken along the line YY in FIG. 19, showing the exposure head according to the embodiment of the present invention positioned at the exposure position. [Figure 24] 20 is a cross-sectional view taken along the line YY in FIG. 19, showing the exposure head according to the embodiment of the present invention in a state where it is positioned at a retracted position. [Figure 25] 1 is a cross-sectional view of a portion of an image forming apparatus according to an embodiment of the present invention. [Figure 26] 1 is a perspective view of an exposure head, a lifting duct, and a rotating arm according to an embodiment of the present invention. [Figure 27] 1 is a side view of an image forming apparatus according to an embodiment of the present invention, with an inner door of the development stay closed; [Figure 28] 1 is a side view of an image forming apparatus according to an embodiment of the present invention, with an inner door of the development stay open. [Figure 29] 20 is a cross-sectional view taken along the line XX in FIG. 19. [Figure 30] 2 is a cross-sectional view of an exposure head, a photosensitive drum, and a rotating arm according to the embodiment of the present invention. FIG. [Figure 31] 3 is a cross-sectional perspective view showing the positioning of the front side of the exposure head and the photosensitive drum according to the embodiment of the present invention. FIG. [Figure 32] FIG. 2 is a cross-sectional perspective view showing the positioning of the exposure head and the photosensitive drum on the rear side according to the embodiment of the present invention. [Figure 33]FIG. 2 is a perspective view of the exposure head according to the embodiment of the present invention, seen from the right side, in a state where the exposure head is removed from the lifting duct. [Figure 34] 1 is a cross-sectional view of an exposure head according to an embodiment of the present invention in a state where it is removed from a lifting duct. [Figure 35] FIG. 2 is a perspective view of the exposure head according to the embodiment of the present invention, seen from the left side, in a state where the exposure head is removed from the lifting duct. [Figure 36] FIG. 2 is a perspective view of the exposure head according to the embodiment of the present invention, as seen from the right side, in a state where the exposure head is placed on a lifting duct. [Figure 37] 1 is a cross-sectional view of a cross section taken along a plane perpendicular to the front-rear direction in a state in which an exposure head according to an embodiment of the present invention is placed on a lifting duct. [Figure 38] FIG. 2 is a perspective view of the exposure head according to the embodiment of the present invention, as seen from the left side, in a state where the exposure head is placed on a lifting duct. [Figure 39] 1 is a cross-sectional view of a cross section taken along a plane perpendicular to the left-right direction in a state in which an exposure head according to an embodiment of the present invention is placed on a lifting duct. [Figure 40] 1 is a partial cross-sectional view of an exposure head according to an embodiment of the present invention placed on a lifting duct. [Figure 41] 1 is a perspective view of an exposure head according to an embodiment of the present invention, as seen from the right side, in a state where the exposure head is attached to a lifting duct. [Figure 42] 1 is a perspective view of an exposure head according to an embodiment of the present invention attached to a lifting duct, as viewed from the left side. [Figure 43] FIG. 30 is a WW cross-sectional view of FIG. 29. [Figure 44] 1 is an enlarged cross-sectional view of a portion of an image forming apparatus according to an embodiment of the present invention. [Figure 45] FIG. 10 is a bottom view of the exposure head according to the embodiment of the present invention before a third adhesive is applied. [Figure 46] FIG. 10 is a perspective view of the exposure head according to the embodiment of the present invention before a third adhesive is applied. [Figure 47] FIG. 10 is a plan view of the exposure head according to the embodiment of the present invention before a sixth adhesive is applied. [Figure 48] FIG. 10 is a perspective view of the exposure head according to the embodiment of the present invention before a sixth adhesive is applied. [Figure 49] FIG. 10 is a bottom view of the exposure head according to the embodiment of the present invention after a third adhesive has been applied. [Figure 50] FIG. 10 is a perspective view of the exposure head according to the embodiment of the present invention after a third adhesive has been applied. [Figure 51] FIG. 10 is a plan view of the exposure head according to the embodiment of the present invention after a sixth adhesive has been applied. [Figure 52] FIG. 10 is a perspective view of the exposure head according to the embodiment of the present invention after a sixth adhesive has been applied. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings.

[0011] <Configuration of image forming device> The configuration of an image forming apparatus 100 according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 9, 23, 24, and 30. FIG.

[0012] Here, the front direction is written as F, the rear direction as B, the right direction as R, the left direction as L, the up direction as U, and the down direction as D. Furthermore, the front side is the near side or front side, and the rear side is the far side or back side. Furthermore, the direction perpendicular to the front-rear and left-right directions and pointing vertically upward is called the up direction, and the direction perpendicular to the front-rear and left-right directions and pointing vertically downward is called the down direction.

[0013] The axial direction of the photosensitive drum 2 and the longitudinal direction of the exposure head 4 are the front-to-rear direction. One end side in the axial direction of the photosensitive drums 2Y, 2M, 2C, and 2K is the front side, and the other end side in the axial direction of the photosensitive drums 2Y, 2M, 2C, and 2K is the rear side.

[0014] Here, the image forming apparatus 100 is exemplified as a so-called tandem color multifunction peripheral (MFP) equipped with multiple photosensitive drums 2Y, 2M, 2C, and 2K each equipped with a reading device. The image forming apparatus 100 may also be a copying machine without a reading device, a color image forming apparatus equipped with a single photosensitive drum, or an image forming apparatus that forms monochrome images. The image forming apparatus 100 may also be a single-color monochrome printer or a full-color printer with five or more colors using special color toners. In this case, the image forming apparatus 100 may be configured to include exposure heads 4 corresponding to the number of colors.

[0015] Specifically, image forming apparatus 100 has image forming units 1Y, 1M, 1C, and 1K, primary transfer rollers 6Y, 6M, 6C, and 6K, an intermediate transfer belt 9, a feed unit 11, a secondary transfer roller 16, and a fuser 19. Image forming apparatus 100 also has a discharge roller 20, a discharge tray 21, toner bottles 22Y, 22M, 22C, and 22K, cartridge trays 30Y, 30M, 30C, and 30K, a rotating arm 65, and an elevation duct 69.

[0016] Furthermore, the image forming apparatus 100 has an apparatus main body 100a, a front cover 101, and inner doors 102Y, 102M, 102C, and 102K. Note that Y (yellow), M (magenta), C (cyan), and K (black) indicate toner colors. In the following description, the same reference numerals with suffixes Y, M, C, and K will be used collectively and only the reference numerals will be used, as necessary.

[0017] Image forming unit 1Y forms a yellow toner image. Image forming unit 1M forms a magenta toner image. Image forming unit 1C forms a cyan toner image. Image forming unit 1K forms a black toner image. Image forming unit 1 includes an exposure head 4, a drum unit 23, and a developing unit 24.

[0018] The exposure head 4 has an elongated shape (longitudinal shape) extending along the axial direction of the photosensitive drum 2. The exposure head 4 exposes the photosensitive drum 2 of the drum unit 23 from below, a so-called "bottom exposure method." The exposure head 4 exposes the photosensitive drum 2 charged by the charging roller 3 of the drum unit 23, thereby forming an electrostatic latent image on the photosensitive drum 2. The exposure head 4 is an LED (Light Emitting Diode, hereinafter referred to as LED) exposure head.

[0019] The drum unit 23 is a cartridge that is replaced by a user or an operator such as a maintenance technician. The drum unit 23 deteriorates with repeated image formation processes, and is therefore in the form of a unit that can be replaced or detached for maintenance. The drum unit 23 is a drum cartridge that includes an integrally formed photosensitive drum 2, a charging roller 3, and a cleaning device (not shown). Note that the drum unit 23 may not include the charging roller 3 or the cleaning device.

[0020] The drum unit 23 is provided with drum bearings 26 that support both axial ends of the photosensitive drum 2 (see FIG. 30). The drum bearings 26 are provided with concave engaging portions 26F and 26B at positions facing positioning pins 45F and 45B (described later) of the exposure head 4. The engaging portions 26F and 26B engage with the positioning pins 45F and 45B. The edges of the engaging portions 26F and 26B are sloped so that they do not ride up onto the edges of the concave shape when engaging with the positioning pins 45F and 45B.

[0021] The photosensitive drum 2 as an image carrier is rotatably supported by a frame of the drum unit 23. The photosensitive drum 2 is an example of a photosensitive member, and may be a photosensitive belt.

[0022] The charging roller 3 charges the photosensitive drum 2 .

[0023] The developing unit 24 deteriorates with repeated image forming processes, and is therefore in the form of a unit that can be replaced or detached for maintenance. The developing unit 24 develops the electrostatic latent image formed on the photosensitive drum 2 by the exposure head 4 with toner to form a toner image on the photosensitive drum 2. The developing unit 24 includes a developing sleeve 5 and a screw 7. The developing unit 24 is a cartridge in which the developing sleeve 5 and the screw 7 are integrated, and is removed from the main body of the image forming apparatus 100 and replaced by an operator.

[0024] The developing sleeve 5 carries the developer supplied by the screw 7 .

[0025] The screw 7 agitates the developer and supplies the developer to the developing sleeve 5 .

[0026] The primary transfer roller 6 sequentially transfers the toner images formed on the photosensitive drum 2 by the developing unit 24 onto the intermediate transfer belt 9 in the primary transfer process.

[0027] The intermediate transfer belt 9 is disposed above the image forming unit 1. The toner image formed on the photosensitive drum 2 is primarily transferred onto the intermediate transfer belt 9 by the primary transfer roller 6. The intermediate transfer belt 9 transports the primarily transferred toner image to the secondary transfer roller 16.

[0028] The feeding unit 11 feeds recording paper to the secondary transfer roller 16. The feeding unit 11 includes a sheet cassette 12a, a sheet cassette 12b, a feeding roller 13a, a feeding roller 13b, and a registration roller 15.

[0029] The sheet cassette 12a is disposed below the image forming unit 1. The sheet cassette 12a accommodates a stack of recording paper P.

[0030] The sheet cassette 12b is disposed below the image forming unit 1. The sheet cassette 12b accommodates a stack of recording paper P.

[0031] The feeding roller 13a feeds the recording paper P stored in the sheet cassette 12a to the registration roller 15 one by one.

[0032] The feeding roller 13b feeds the recording paper P stored in the sheet cassette 12b to the registration roller 15 one by one.

[0033] The registration rollers 15 transport the recording paper P fed by the feed roller 13a or the feed roller 13b to the secondary transfer portion T2 at a predetermined timing.

[0034] The secondary transfer roller 16 secondarily transfers the toner image that has been primarily transferred onto the intermediate transfer belt 9 by the primary transfer roller 6 onto the recording paper P that has been transported from the feed unit 11. The secondary transfer roller 16 transports the recording paper P onto which the toner image has been secondarily transferred to the fixing device 19.

[0035] The fixing device 19 applies heat and pressure to the recording paper P onto which the toner image has been secondarily transferred and which is being transported by the secondary transfer roller 16, thereby fixing the toner image to the recording paper P. The fixing device 19 transports the recording paper P onto which the toner image has been fixed to the discharge rollers 20.

[0036] The discharge rollers 20 discharge the recording paper P conveyed by the fixing unit 19 onto a discharge tray 21 .

[0037] The discharge tray 21 is disposed above the toner bottle 22. On the discharge tray 21, the recording paper P discharged by the discharge roller 20 is stacked.

[0038] Toner bottle 22 is a unit that can be detached from image forming apparatus 100 and is disposed above intermediate transfer belt 9. Toner bottle 22 contains replenishment toner. Each toner bottle 22 replenishes an appropriate amount of toner to each developing unit 24 at an appropriate time via a toner replenishment mechanism (not shown).

[0039] The cartridge tray 30 supports the drum unit 23 and the developing unit 24. The cartridge tray 30 is movable while being guided in the axial direction of the photosensitive drum 2. The cartridge tray 30 rotatably supports a rotation shaft 102a of the inner door 102. The configuration of the cartridge tray 30 will be described in detail later. The cartridge tray 30 is not limited to being provided for each image forming unit 1.

[0040] The rotating arms 65 support both longitudinal ends of the lifting duct 69 from below.

[0041] The lifting duct 69 is movably provided between a developer support member 301 and a drum support member 302 (described later) of the cartridge tray 30, and detachably supports the exposure head 4. The lifting duct 69 is movable together with the exposure head 4 in a direction perpendicular to the axial direction of the photosensitive drum 2 by a rotating arm 65. As the rotating arm 65 rotates, the lifting duct 69 moves to an exposure position shown in FIG. 23 where the photosensitive drum 2 is exposed, and to a retracted position shown in FIG. 24 where the lifting duct 69 is retracted from the exposure position.

[0042] The lift duct 69 has a longitudinal shape extending in the axial direction (front-rear direction) of the photosensitive drum 2, similar to the exposure head 4. The lift duct 69 has upper and lower openings at the center in the longitudinal direction. The lift duct 69, together with the cartridge tray 30, forms an opening 64 that communicates with an opening of a duct unit (not shown) that blows air taken in from outside the image forming apparatus 100 through the lift duct 69 against the substrate 50 of the exposure head 4. The configuration of the lift duct 69 will be described in detail later.

[0043] The apparatus main body 100a constitutes the housing of the image forming apparatus 100.

[0044] The front cover 101 is provided on the front side of the apparatus main body 100a and constitutes the exterior of the front side of the image forming apparatus 100. The front cover 101 is provided rotatably with respect to the apparatus main body 100a by a hinge (not shown). The front cover 101 is provided forward of the inner door 102 in the axial direction of the photosensitive drum 2. When the front cover 101 is closed as shown in FIG. 1 , it entirely covers the multiple inner doors 102 lined up in the left-right direction.

[0045] The inner door 102 is provided on the front side of the cartridge tray 30 by a hinge (not shown) so as to be rotatable relative to the cartridge tray 30. The inner door 102 covers the front sides of the drum unit 23 and the developing unit 24. The inner door 102 is a necessary member for protecting each unit and for making it difficult for the photosensitive drum 2 to be exposed to light outside the image forming process.

[0046] The inner door 102 includes a rotation shaft 102a and a link engagement portion 102b.

[0047] The rotation shaft 102 a is the center of rotation when the inner door 102 rotates relative to the cartridge tray 30 .

[0048] When the inner door 102 is closed, the link engaging portion 102b is provided below the rotation shaft 102a in a direction perpendicular to the axial direction of the photosensitive drum 2. The link engaging portion 102b engages with the development stay link 34.

[0049] <Exposure head configuration> The configuration of the exposure head 4 according to the embodiment of the present invention will be described in detail with reference to FIGS. 10 to 18, 38 and 40. FIG.

[0050] The exposure head 4 includes a positioning pin 45B, a positioning pin 45F, a substrate 50, a lens array 52, an LED chip 53, a housing 54, a housing support member 55, and an FFC connector 57.

[0051] The positioning pin 45B is a conductive member having electrical conductivity, and is crimped to the housing 54 to be electrically connected to the housing 54. The positioning pin 45B is provided rearward of the lens array 52 in the longitudinal direction of the housing 54, and protrudes on both sides from the housing 54 in a direction parallel to the optical axis direction of the lens array 52.

[0052] The positioning pin 45B abuts against the drum bearing 26 of the drum unit 23 in the movement direction of the lift duct 69 from the retracted position to the exposure position, thereby providing a gap between the lens array 52 and the photosensitive drum 2. When the exposure head 4 slides in the direction of arrow B in Figure 38, the lower end of the positioning pin 45B auxiliary fits into the auxiliary fitting portion 30i of the cartridge tray 30.

[0053] 38, the positioning pin 45B comes into contact with a conductive member 251 (described later) of the cartridge tray 30, thereby earthing the exposure head 4 and the image forming apparatus 100. Note that the positioning pin 45B is not limited to being crimped and attached to the housing 54, and may also be welded to the housing 54.

[0054] The positioning pin 45F is a conductive member having electrical conductivity, and is crimped to the housing 54 to be electrically connected to the housing 54. The positioning pin 45F is provided in front of the lens array 52 in the longitudinal direction of the housing 54, and protrudes on both sides from the housing 54 in a direction parallel to the optical axis direction of the lens array 52.

[0055] The positioning pin 45F abuts against the drum bearing 26 of the drum unit 23 in the movement direction of the lift duct 69 from the retracted position to the exposure position, thereby providing a gap between the lens array 52 and the photosensitive drum 2. When the exposure head 4 slides in the direction of arrow B in Figure 38, the lower end of the positioning pin 45F auxiliary fits into the auxiliary fitting portion 30h of the cartridge tray 30.

[0056] 38, the positioning pin 45F comes into contact with the conductive member 251 of the cartridge tray 30, as shown in Figure 40, thereby earthing the exposure head 4 and the image forming apparatus 100. Note that the positioning pin 45F is not limited to being crimped and attached to the housing 54, and may also be welded to the housing 54.

[0057] The substrate 50 has an elongated shape. LED chips 53 are mounted and arranged on the front surface, which serves as a first surface, of the substrate 50. Electrical components such as an FFC connector 57 are mounted on the rear surface, which serves as a second surface, of the substrate 50. The substrate 50 is adhered to the housing 54 at multiple locations in the longitudinal direction with a third adhesive 59a (described later) or the like while spaced apart from the housing 54. Wiring (not shown) for supplying signals to the LED chips 53 is provided on the substrate 50. Here, the longitudinal direction of the substrate 50 is the same as the axial direction and the front-rear direction of the photosensitive drum 2. The lateral direction of the substrate 50 is perpendicular to the longitudinal direction of the substrate 50 and is the same as the left-right direction.

[0058] The lens array 52 has an elongated shape and focuses light emitted from LEDs 51 (described later) of the LED chip 53 onto the surface of the photosensitive drum 2. The lens array 52 includes lenses 521 arranged in two rows along the arrangement direction of the LEDs 51. The lens array 52 is a lens assembly including a plurality of lenses 521.

[0059] The position of the lens array 52 is adjusted so that the distance between the light-emitting surface of the LED 51 and the light incident surface 52b of the lens 521 is approximately equal to the distance between the light exit surface 52a of the lens 521 and the surface of the photosensitive drum 2. The lens array 52 is bonded to the substrate 50 at multiple locations in the longitudinal direction of the lens array 52 with a sixth adhesive 59b (described later) or the like, while being spaced apart from the housing 54. Here, the longitudinal direction of the lens array 52 is the same as the longitudinal direction of the exposure head 4.

[0060] The lenses 521 are cylindrical glass rod lenses, and include a light incident surface 52b onto which light emitted from the LEDs 51 enters and a light exit surface 52a from which the light incident from the light incident surface 52b exits (see FIG. 10 ), and focus the incident light on the surface of the photosensitive drum 2. The material of the lenses 521 is not limited to glass, but may be plastic. The shape of the lenses 521 is also not limited to a cylindrical shape, but may be a polygonal prism, such as a hexagonal prism. As shown in FIG. 13( e), the lenses 521 in one of the two rows are in contact with two adjacent lenses 521 in the arrangement direction of the lenses 521 in the other of the two rows.

[0061] The LED chip 53 as a light-emitting chip includes a plurality of LEDs 51 as light-emitting portions that emit light, and is mounted on the surface of the substrate 50. The configuration of the LED chip 53 will be described in detail later.

[0062] The housing 54 is a metal member formed by pressing a plated zinc-plated steel sheet or a cold-rolled steel sheet into a U-shaped cross section. The housing 54 holds the substrate 50 and the lens array 52. ​​Details of the configuration of the housing 54 and the bonding and sealing mechanisms between the housing 54, the substrate 50, and the lens array 52 will be described later.

[0063] The housing support member 55 is a longitudinal member extending in the axial direction of the photosensitive drum 2, and supports the housing 54 along the longitudinal direction. The housing support member 55 is formed so that its cross section is U-shaped. The configuration of the housing support member 55 will be described in detail later.

[0064] An FFC connector 57 serving as a connector is mounted on the back surface of the substrate 50 opposite the front surface, with its longitudinal direction aligned with the longitudinal direction of the substrate 50. The FFC connector 57 is provided on one end (front side) of the substrate 50. One longitudinal end of a flexible flat cable 58 is connected to the FFC connector 57.

[0065] In the above configuration, the other longitudinal end of the flexible flat cable 58 connected to the FFC connector 57 is connected to a connector and a control unit mounted on a substrate (not shown in any figure) provided in the image forming apparatus 100. The LED chip 53 is driven by a control signal (drive signal) input from the above control unit and connector of the image forming apparatus 100 via the cable, the FFC connector 57, and the wiring of the substrate 50.

[0066] Further, the exposure head 4 is movable in the optical axis direction substantially along the optical axis Z (see Fig. 13(e)) of the lens 521 by a retraction mechanism of a rotation arm 65 and a lift duct 69, which will be described later. The optical axis Z of the lens 521 here means a line connecting the center of the light emitting surface of the lens 521 and the focal point of the lens 521. Also, since the lens array 52 is an aggregate of lenses 521 having a plurality of lenses 521, the optical axis Z is the optical axis of any one of the plurality of lenses 521.

[0067] Further, the plurality of lenses 521 may be slightly inclined with respect to each other strictly. This inclination is due to the tolerance during assembly. However, the optical axes Z of the plurality of lenses 521 shall be regarded as being in the same direction without considering the deviation of the above tolerance level.

[0068] In the exposure head 4, the semiconductor LED, i.e., the LED 51, is used as the light source, but it is not limited to this, and an OLED (Organic Light Emitting Diode) may be used as the light source. The OLED is also called organic EL (Organic Electro-Luminescence) and is a current-driven light emitting element. Further, the OLEDs are arranged linearly along the main scanning direction, which is the axial direction of the photosensitive drum 2, on, for example, a TFT (Thin Film Transister) substrate, and are electrically connected in parallel by a power supply wiring provided along the main scanning direction.

[0069] <Configuration of LED Chip> The configuration of the LED chip 53 of the exposure head 4 according to the embodiment of the present invention will be described in detail with reference to FIG.

[0070] The LED chip 53 includes a plurality of LEDs 51, and a plurality of LEDs are arranged on one surface of the substrate 50. The number of LED chips 53 is 29 in this example. The LEDs 51 are preferably organic EL (Electro Luminescence) in order to save power.

[0071] Each of the LED chips 53-1 to 53-29 has 516 LEDs 51 arranged in a row along the longitudinal direction. The center-to-center distance k2 between adjacent LEDs 53 in the longitudinal direction of the LED chip 53 corresponds to the resolution of the image forming apparatus 100. The longitudinal direction of the LED chip 53 is the same as the longitudinal direction of the exposure head 4.

[0072] For example, if the resolution of the image forming apparatus 100 is 1200 dpi, the center-to-center distance k2 is 21.16 μm, and the exposure range of the exposure head 4 is approximately 314 mm. In this case, the photosensitive layer of the photosensitive drum 2 is formed with a width of 314 mm or more. Furthermore, since the length of the long side of A4-size recording paper S and the length of the short side of A3-size recording paper S are 297 mm, the exposure head 4 has an exposure range that allows images to be formed on both A4-size recording paper S and A3-size recording paper S.

[0073] The LED chips 53-1 to 53-29 are arranged in two rows along the rotational axis direction of the photosensitive drum 2. Specifically, the odd-numbered LED chips 53-1, 53-3, ..., 53-29 counting from the left are mounted on the substrate 50 in a row along the longitudinal direction. Furthermore, the even-numbered LED chips 53-2, 53-4, ..., 53-28 counting from the left are mounted on the substrate 50 in a row along the longitudinal direction.

[0074] The LED chips 53-2, 53-4, ..., 53-28 are arranged in a row different from the LED chips 53-1, 53-3, ..., 53-29. The center-to-center distance k1 between the LEDs 51 at one end in the arrangement direction of the odd-numbered LED chips 53-1, ..., 53-29 and the LEDs 51 at the other end in the arrangement direction of the even-numbered LED chips 53-2, ..., 53-28 is the same as the center-to-center distance k2.

[0075] <Case configuration> The configuration of the housing 54 of the exposure head 4 according to the embodiment of the present invention will be described in detail with reference to FIGS.

[0076] The housing 54 includes a first opening 54a, a second opening 54b, a flat surface 54U, an extending portion 54R, and an extending portion 54L.

[0077] The first opening 54a is provided in the flat portion 54U. The lens array 52 is inserted through the first opening 54a.

[0078] The second opening 54b is provided at a position facing the flat portion 54U and between the extending portions 54L and 54R.

[0079] The flat surface portion 54U faces the photosensitive drum 2 in the direction of the optical axis Z of the lenses 521 of the lens array 52. ​​The flat surface portion 54U is not limited to a flat surface, and may be a slightly curved surface.

[0080] The extension portion 54R extends in a direction away from the photosensitive drum 2 from one end side in the widthwise direction of the flat portion 54U.

[0081] The extending portion 54L extends from the other end side of the flat portion 54U in the short side direction in a direction away from the photosensitive drum 2. The extending portion 54L faces the extending portion 54R.

[0082] <Configuration of the housing support member> The configuration of the housing support member 55 of the exposure head 4 according to the embodiment of the present invention will be described in detail with reference to FIGS. 10, 12, and 21 to 26. FIG.

[0083] The housing support member 55 includes a left side wall 55L, a right side wall 55R, a bottom surface portion 55D, an opening 55a, an engaging claw 55b, and an engaging claw 55c.

[0084] The left side wall 55L is provided at one end of the short side of the bottom surface portion 55D, between the housing 54 and the developing unit 24 along the longitudinal direction of the housing support member 55 so as to separate the housing 54 and the developing unit 24 (see Figure 21).

[0085] The right side wall 55R faces the left side wall 55L. The right side wall 55R is provided on the other end side of the bottom surface portion 55D in the short direction, between the housing 54 and the drum unit 23, along the longitudinal direction of the housing support member 55, so as to separate the housing 54 and the drum unit 23 (see FIG. 21).

[0086] The bottom surface portion 55D connects the left side wall 55L and the right side wall 55R, and faces the flat surface portion 54U of the housing 54 (see FIG. 10). The bottom surface portion 55D faces the back surface of the substrate 50, opposite the front surface on which the LEDs 51 are mounted. The bottom surface portion 55D faces the upper surface portion 69U of the lifting duct 69. The bottom surface portion 55D includes a first bottom surface portion 55D1 and a second bottom surface portion 55D2 (see FIG. 12).

[0087] The first bottom surface portion 55D1 is provided between the frontmost opening 55a and the central opening 55a between the frontmost opening 55a and the rearmost opening 55a.

[0088] The second bottom surface portion 55D2 is provided between the rearmost opening 55a and the central opening 55a.

[0089] A plurality of openings 55a are provided in the bottom surface 55D along the longitudinal direction of the housing support member 55.

[0090] The engaging claw 55b is elastically deformable and is provided on the first bottom surface portion 55D1. The engaging claw 55b protrudes toward the lifting duct 69, and the tip of the engaging claw 55b in the protruding direction is further bent in the axial direction of the photosensitive drum 2, which is perpendicular to the protruding direction, and extends toward the rear side, forming a substantially L-shape. The engaging claw 55b engages with the lifting duct 69 by snap fitting. The engaging claw 55b has a recess 55f recessed into the tip side in the extending direction.

[0091] The engaging claw 55c is elastically deformable and is provided on the second bottom surface portion 55D2. The engaging claw 55c protrudes toward the lifting duct 69, and the tip of the engaging claw 55c in the protruding direction is further bent in the axial direction of the photosensitive drum 2, which is perpendicular to the protruding direction, and extended rearward to form a substantially L-shape. The engaging claw 55c engages with the lifting duct 69 by snap-fitting.

[0092] <Configuration of the lift duct> The configuration of the lift duct 69 of the image forming apparatus 100 according to the embodiment of the present invention will be described in detail with reference to FIGS. 19 to 26 and 33. FIG.

[0093] The lifting duct 69 has an opening 69a, an upper surface 69U, a duct left wall 69L, a duct right wall 69R, a duct front wall 69F, a duct rear wall 69B, an engagement hole 69b, an engagement hole 69c, a first engagement portion 69d, a second engagement portion 69e, and a protrusion 69f.

[0094] A plurality of openings 69a are provided in the upper surface portion 69U along the longitudinal direction of the lifting duct 69, which is the axial direction of the photosensitive drum 2 (see FIG. 33). The openings 69a are provided at positions facing the plurality of openings 55a provided in the bottom surface portion 55D of the housing support member 55, and are in communication with the openings 55a.

[0095] The top surface 69U faces the bottom surface 55D of the housing support member 55 and detachably supports the exposure head 4. The top surface 69U is surrounded by a duct left wall 69L, a duct right wall 69R, a duct front wall 69F, and a duct rear wall 69B.

[0096] The duct left wall 69L is provided at one end of the upper surface portion 69U in the short direction and is provided at a position facing the developing unit 24. The duct left wall 69L is provided along the longitudinal direction of the lift-up duct 69 and connects the duct front wall 69F and the duct rear wall 69B. The duct left wall 69L has a first inclined surface 69L1 that is inclined in a direction away from the duct right wall 69R toward the movement direction of the lift-up duct 69 from the exposure position to the retracted position. The first inclined surface 69L1 is provided at a position facing the developer support member 301 of the duct left wall 69L and is inclined at an angle θ2 with respect to the movement direction of the lift-up duct 69 from the retracted position to the exposure position (the direction of arrow G shown in FIG. 21).

[0097] The duct right wall 69R is provided at the other end in the short direction of the upper surface portion 69U and faces the duct left wall 69L. The duct right wall 69R is provided at a position facing the drum unit 23 and is provided along the longitudinal direction of the lift-up duct 69, connecting the duct front wall 69F and the duct rear wall 69B. The duct right wall 69R has a second inclined surface 69R1 that is inclined in a direction away from the duct left wall 69L in the movement direction of the lift-up duct 69 from the exposure position to the retracted position.

[0098] The second inclined surface 69R1 is provided at a position opposite the drum support member 302 on the duct right wall 69R, and is inclined at an angle θ1 with respect to the movement direction of the lifting duct 69 from the retracted position toward the exposure position (the direction of arrow G shown in Figure 21).

[0099] The duct front wall 69F is provided at one longitudinal end of the upper surface portion 69U. The duct front wall 69F protrudes further toward the tip side than the duct left wall 69L and the duct right wall 69R in the movement direction of the lifting duct 69 from the exposure position to the retracted position.

[0100] The duct rear wall 69B is provided at the other longitudinal end of the upper surface portion 69U. The duct rear wall 69B faces the duct front wall 69F. The duct rear wall 69B protrudes further toward the tip side than the duct left wall 69L and the duct right wall 69R in the movement direction of the lifting duct 69 from the exposure position to the retracted position.

[0101] The engagement hole 69b is provided in the upper surface portion 69U between an opening 69a provided at one end (front side) of the upper surface portion 69U in the longitudinal direction and an opening 69a adjacent to this opening 69a in the longitudinal direction of the upper surface portion 69U. The engagement hole 69b engages with the engagement claw 55b of the housing support member 55 by snap-fitting.

[0102] The engagement hole 69c is provided in the upper surface portion 69U between the opening 69a at the other end (rear side) in the longitudinal direction and the opening 69a adjacent to this opening 69a. The engagement hole 69c engages with the engagement claw 55c of the housing support member 55 by snap-fitting.

[0103] The first engaging portion 69d is provided at one end of the lifting duct 69 in the longitudinal direction and is engageable with the pivot arm 65. The first engaging portion 69d is provided outside the duct front wall 69F in the longitudinal direction. The first engaging portion 69d is provided further outside the FFC connector 57, which is located outside the duct front wall 69F in the longitudinal direction.

[0104] The second engagement portion 69e is provided on the other end side in the longitudinal direction of the lifting duct 69, and is engageable with the rotating arm 65. The second engagement portion 69e is provided on the outer side of the duct rear wall 69B in the longitudinal direction.

[0105] The convex portion 69f is provided at a position corresponding to the position of the concave portion 55f when the exposure head 4 has moved to the sliding operation completion position (mounting completion position) relative to the lifting duct 69. The convex portion 69f engages with the concave portion 55f when the exposure head 4 is positioned at the sliding operation completion position.

[0106] The lift duct 69 having the above-described configuration has an upper surface portion 69U, a duct left wall 69L, a duct right wall 69R, a duct front wall 69F, and a duct rear wall 69B that are integrally formed, and has openings at the top and bottom.

[0107] The lifting duct 69 has no openings at positions facing the developing unit 24 and the drum unit 23, and is formed in a hollow shape with openings at the top and bottom.

[0108] Furthermore, the duct front wall 69F and duct rear wall 69B of the lifting duct 69, together with the developer guide portion 301a of the developer support member 301 and the drum guide portion 302a of the drum support member 302, form an opening 64 (see FIG. 20). The lifting duct 69 forms a duct (closed space) that allows air from a duct unit (not shown) to circulate through the opening 64 and the opening 69a toward the rear surface of the substrate 50, while preventing the air from leaking toward the adjacent developing unit 24 or drum unit 23. This makes it possible to reduce toner scattering inside the apparatus main body 100a.

[0109] The lifting duct 69 is movably disposed between a first developing guide portion 301a and a first drum guide portion 302a of the cartridge tray 30, which will be described later.

[0110] 19, where the first engagement portion 69d is provided, is located outside the duct region La in FIG. 19, which is the duct wall surrounding the opening 69a, which is the duct wall including the duct left wall 69L, the duct right wall 69R, the duct front wall 69F, and the duct rear wall 69B. The region Lm in FIG. 20, where the second engagement portion 69e is provided, is located outside the duct region La. That is, the duct region La is located between the region Lm in FIG. 19, where the first engagement portion 69d is provided, and the region Lm in FIG. 20, where the second engagement portion 69e is provided.

[0111] The region Lc in FIG. 19 where the FFC connector 57 is provided is located outside the duct region La in FIG. 19 which forms a duct with the opening 69a surrounded by a duct wall, and is located between the duct region La and the region Lm in FIG. 19 where the first engagement portion 69d is provided. The duct region La includes most of the board 50 on which the LEDs 51 are mounted. Therefore, by blowing airflow into the duct region La, the exposure head 4 can be sufficiently cooled. The region Lc is the mounting portion for the FFC connector 57 of the signal line which transmits the drive signal to the board 50 on which the LEDs 51 are mounted. Although the region Lc does not have an opening forming a duct, as described above, the duct region La is configured to provide necessary and sufficient cooling.

[0112] Air taken in from outside the image forming apparatus 100 by a duct unit (not shown) passes through the lifting duct 69 and is blown onto the rear surface of the board 50 from the opening 55a of the housing support member 55. The air blown onto the rear surface of the board 50 from the opening 55a of the housing support member 55 is exhausted to the outside of the image forming apparatus 100 by the duct unit through the lifting duct 69.

[0113] <Cartridge tray configuration> The configuration of cartridge tray 30 of image forming apparatus 100 according to the embodiment of the present invention will be described in detail with reference to FIGS. 7 to 9, 19 to 24, and 40. FIG.

[0114] The cartridge tray 30 includes a development stay 31 , a conductive member 251 , a development support member 301 , and a drum support member 302 .

[0115] The developing stay 31 is provided on the developing bottom surface portion 301c of the developing support member 301 so as to be movable in the axial direction of the photosensitive drum 2. The developing stay 31 has an elongated shape (longitudinal shape) extending in the axial direction of the photosensitive drum 2. The configuration of the developing stay 31 will be described in detail later.

[0116] The conductive member 251 is a thin metal plate that elastically deforms when it comes into contact with the positioning pins 45F and 45B of the exposure head 4, thereby providing sufficient contact pressure to the positioning pins 45F and 45B (see FIG. 40). The conductive member 251 is electrically connected to the metal frame of the image forming apparatus 100 via a harness and a circuit board on which resistors and capacitors for noise removal are mounted, both of which are not shown.

[0117] The developing device supporting member 301 is a longitudinal member extending in the axial direction of the photosensitive drum 2, and supports the developing unit 24. A rotating arm 65 is rotatably provided on the developing device supporting member 301. The upper surface of the developing device supporting member 301, together with the bottom surface of the developing unit 24, forms a duct, which is a closed space.

[0118] The developing device support member 301 includes a first developing device guide portion 301a, a second developing device guide portion 301b, and a developing device bottom surface portion 301c. The first developing device guide portion 301a, the second developing device guide portion 301b, and the developing device bottom surface portion 301c are integrally formed.

[0119] The first developing guide portion 301a is provided on one end side of the developing bottom surface portion 301c in the short direction of the cartridge tray 30, and is provided between the lifting / lowering duct 69 and the developing unit 24 to separate the lifting / lowering duct 69 and the developing unit 24. The first developing guide portion 301a guides the movement of the developing unit 24 in the axial direction of the photosensitive drum 2 when the developing unit 24 is inserted or removed from the front side of the apparatus main body 100a along the axial direction of the photosensitive drum 2. The first developing guide portion 301a includes an opposing portion 301d and a partition portion 301e.

[0120] The facing portion 301d faces the first inclined surface 69L1 of the lifting duct 69, and is inclined in the same manner as the first inclined surface 69L1.

[0121] The partition wall 301e is provided closer to the tip side than the opposing portion 301d in the movement direction of the lift duct 69 from the retracted position to the exposure position. The partition wall 301e is provided between the exposure head 4 and the developing unit 24 so as to separate the exposure head 4 located at the exposure position shown in Figure 21 from the developing unit 24. The partition wall 301e is provided at the upper end of the first developing guide portion 301a.

[0122] The second developing guide portion 301b faces the first developing guide portion 301a. The second developing guide portion 301b is provided on the other end side of the developing bottom surface portion 301c in the short direction of the cartridge tray 30. The second developing guide portion 301b guides the movement of the developing unit 24 in the axial direction of the photosensitive drum 2 when the developing unit 24 is inserted or removed from the front side of the apparatus main body 100a along the axial direction of the photosensitive drum 2.

[0123] The developing bottom surface portion 301c connects the first developing guide portion 301a and the second developing guide portion 301b. The developing bottom surface portion 301c faces the bottom surface portion 24D of the developing unit 24 across a space, and is provided along the longitudinal direction of the cartridge tray 30.

[0124] The drum support member 302 is a longitudinal member extending in the axial direction of the photosensitive drum 2, and supports the drum unit 23. The drum support member 302 includes a first drum guide portion 302a, a second drum guide portion 302b, and a drum bottom portion 302c. The first drum guide portion 302a, the second drum guide portion 302b, and the drum bottom portion 302c are integrally formed.

[0125] The first drum guide portion 302a is provided on one end side of the drum bottom surface portion 302c in the shorter direction of the cartridge tray 30, and is provided between the lifting / lowering duct 69 and the drum unit 23 to separate the lifting / lowering duct 69 and the drum unit 23. The first drum guide portion 302a abuts against the drum unit 23 to guide movement of the drum unit 23 in the axial direction of the photosensitive drum 2 when the drum unit 23 is inserted or removed from the front side of the apparatus main body 100a along the axial direction of the photosensitive drum 2. The first drum guide portion 302a has a facing portion 302d that faces the second inclined surface 69R1 of the lifting / lowering duct 69. The facing portion 302d is inclined in the same manner as the second inclined surface 69R1 of the lifting / lowering duct 69.

[0126] The second drum guide portion 302b is provided on the other end of the drum bottom surface portion 302c in the short direction of the cartridge tray 30, and faces the first drum guide portion 302a. The second drum guide portion 302b abuts against the drum unit 23, and guides the movement of the drum unit 23 in the longitudinal direction when the drum unit 23 is inserted into or removed from the front side of the apparatus main body 100a along the longitudinal direction.

[0127] The drum bottom surface 302c connects the first drum guide portion 302a and the second drum guide portion 302b. The drum bottom surface 302c faces the bottom surface 23D of the drum unit 23 and is provided along the longitudinal direction of the cartridge tray 30.

[0128] In the cartridge tray 30 having the above-described configuration, the first developing guide portion 301a and the first drum guide portion 302a function as guide members that guide the movement of the lifting duct 69.

[0129] In addition, the cartridge tray 30, together with the lifting duct 69 arranged between the first development guide portion 301a and the first drum guide portion 302a, forms a duct with a closed space communicating with the opening 55a of the exposure head 4.

[0130] <Developing stay configuration> The configuration of the developing stay 31 of the image forming apparatus 100 according to the embodiment of the present invention will be described in detail with reference to FIGS.

[0131] The developing stay 31 includes a developing pressure piece 32, a developing pressure piece 33, a developing stay link 34, an arm retraction member 68F, and an arm retraction member 68B.

[0132] The developing pressure piece 32 is provided at a position facing the developing unit 24, and is fixed to one end (front side) of the developing stay 31 in the longitudinal direction.

[0133] The developing pressure piece 33 is provided at a position facing the developing unit 24, and is fixed to the other end (rear side) of the developing stay 31 in the longitudinal direction.

[0134] The development stay link 34 is provided on one end side of the development stay 31 in the longitudinal direction, and engages with a link engaging portion 102 b of an inner door 102 pivotally supported by the cartridge tray 30 .

[0135] The arm retraction member 68F is provided at one end of the developing stay 31 in the longitudinal direction, on the surface opposite to the surface of the developing stay 31 where the developing pressure piece 32 is provided. The arm retraction member 68F slides back and forth in conjunction with the opening and closing movement of the inner door 102, thereby rotating the rotating arm 65.

[0136] The arm retraction member 68B is provided at the other longitudinal end of the developing stay 31, on the surface of the developing stay 31 opposite to the surface on which the developing pressure piece 33 is provided. The arm retraction member 68B slides back and forth in conjunction with the opening and closing movement of the inner door 102, thereby rotating the rotating arm 65.

[0137] <Configuration of the adhesion and sealing mechanism between the housing, substrate, and lens array> The structure of the adhesion and sealing mechanism between the housing 54, the substrate 50 and the lens array 52 of the exposure head 4 according to the embodiment of the present invention will be described in detail with reference to FIGS. 45 to 52. FIG.

[0138] Both ends in the short direction of the substrate 50 inserted and positioned in the second opening 54b of the housing 54 are bonded and temporarily fixed to the extending portions 54L and 54R of the housing 54 with a second adhesive 77c. The second adhesive 77c is an acrylic photocurable resin that has the property of being able to cure in a short time at room temperature and that cures when exposed to UV light.

[0139] The second adhesive 77c is preferably arranged at positions that are approximately symmetrical in the short-side direction with respect to the center of the short-side direction of the substrate 50, and is also preferably arranged at approximately equal intervals in the longitudinal direction of the substrate 50. Furthermore, the number of bonding locations in the longitudinal direction of the second adhesive 77c is preferably three or more in order to correct warping of the substrate 50, and eight locations is exemplified here.

[0140] Furthermore, the positions where the second adhesive 77c is provided at both longitudinal ends of the substrate 50 are desirably outside the image forming area in order to effectively correct warping of the substrate 50 within the image forming area. The image forming area corresponds to the area where the LED chips 53 are mounted in the longitudinal direction of the exposure head 4. Outside the image forming area in the longitudinal direction of the exposure head 4, light emitted from the LED chips 53 does not reach the photosensitive drum 2, and therefore an electrostatic latent image is not formed on the photosensitive drum 2. Furthermore, the second adhesive 77c is arranged in a position that does not overlap in the vertical direction with the FFC connector 57 mounted on the substrate 50 when viewed in the lateral direction of the substrate 50.

[0141] Furthermore, the second adhesive 77c is disposed near one end (other end) in the longitudinal direction of the FFC connector 57 (see FIG. 46). The second adhesive 77c is spaced apart from the FFC connector 57.

[0142] Furthermore, the side surface of the lens array 52 inserted and positioned in the first opening 54a of the housing 54 is bonded and temporarily fixed to the flat surface portion 54U of the housing 54 with a fifth adhesive 77d. As the fifth adhesive 77d, an acrylic photocurable resin that has the property of being able to cure in a short time at room temperature and that cures when exposed to UV light is used.

[0143] The fifth adhesive 77d is preferably arranged at positions that are approximately symmetrical in the short-side direction with respect to the center of the short-side direction of the lens array 52, and is also preferably arranged at approximately equal intervals in the longitudinal direction of the lens array 52. ​​The number of bonding locations of the fifth adhesive 77d in the longitudinal direction of the lens array 52 is preferably three or more in order to correct warping of the lens array 52, and nine locations are exemplified here. Furthermore, the positions at which the fifth adhesive 77d is provided at both ends in the longitudinal direction of the lens array 52 are preferably outside the image formation area in order to effectively correct warping of the lens array 52 within the image formation area.

[0144] The LED chips 53 of the exposure head 4 used in this embodiment increase in temperature as they emit light during image formation. The temperature increase in the LED chips 53 propagates throughout the exposure head 4, causing the temperatures of the substrate 50 and the housing 54 to increase. When the temperature of the exposure head 4 increases, the dimensions of each component of the exposure head 4 change according to their linear expansion coefficients. In particular, when the housing 54 is made of metal and the substrate 50 is made of resin, which results in a large difference in the linear expansion coefficients between the housing 54 and the substrate 50, a large difference in the dimensional changes that occur with temperature increase occurs. In this case, the adhesive strength that bonds the housing 54 and the substrate 50 cannot withstand the dimensional difference, and there is a risk that the housing 54 and the substrate 50 will peel off. For this reason, the housing 54 and the substrate 50 require strong adhesive strength that can withstand the dimensional differences between the components due to thermal expansion.

[0145] Furthermore, depending on the properties of the adhesive that bonds the housing 54 and the substrate 50, there is a risk that thermal expansion will occur as the temperature rises.

[0146] The linear expansion coefficient of the acrylic photocurable resin used for the second adhesive 77c and the fifth adhesive 77d is generally several hundred ppm / °C. Therefore, heat generated by the LED chip 53 may be transmitted to the second adhesive 77c and the fifth adhesive 77d, causing thermal expansion.

[0147] Furthermore, the application amounts of the second adhesive 77c and the fifth adhesive 77d are not uniform across the areas where the second adhesive 77c and the fifth adhesive 77d are applied. Therefore, the dimensions of the second adhesive 77c and the fifth adhesive 77d vary after heating depending on the application amounts. As a result, the position of the substrate relative to the housing 54 changes, causing the optical axis of the LED chip 53 to shift, which could prevent a predetermined amount of light from reaching the photosensitive drum 2. The curing speed of the fifth adhesive 77d corresponds to the fourth speed, and the elastic modulus of the fifth adhesive 77d after curing corresponds to the fourth elastic modulus.

[0148] Therefore, the housing 54, the substrate 50 and the lens array 52 are temporarily fixed with an acrylic photocurable resin, and then permanently fixed with a thermosetting resin having a higher elastic modulus and a lower linear expansion coefficient.

[0149] Specifically, in the temporarily fixed substrate 50 and housing 54, both ends of the shorter side of the underside of the substrate 50 and the extensions 54L and 54R of the housing 54 are bonded and permanently fixed with a first adhesive 77a. The first adhesive 77a is an epoxy-based thermosetting resin having a post-curing elastic modulus of several tens of GPa, a glass transition point of around 100°C, and a linear expansion coefficient of several tens of ppm / °C in the range of the actual operating temperature. The first adhesive 77a, which is a thermosetting resin, has the property of curing by applying heat after application. Here, thermosetting resins have a superior post-curing elastic modulus compared to photo-curable adhesives.

[0150] The first adhesive 77a used in this embodiment is cured by heating in an oven at 100°C for several hours. In this embodiment, the substrate 50 is positioned at a predetermined position relative to the housing 54, and then fixed using an adhesive. However, if it takes time to bond the housing 54 and the substrate 50, there is a risk that the position of the substrate 50 relative to the housing 54 will deviate from the predetermined value before the adhesive completely hardens.

[0151] In contrast, in the present embodiment, the substrate 50 is first bonded to the housing 54 using the second adhesive 77c, which is a photocurable adhesive with an excellent curing speed. After the photocurable adhesive has cured, the first adhesive 77a, which is a thermosetting resin, is applied to permanently fix the substrate 50 to the housing 54. The second adhesive 77c cures faster than the first adhesive 77a. This makes it possible to reliably determine the position of the substrate 50 relative to the housing 54, and reduces the risk of the substrate 50 being misaligned relative to the housing 54 even if it takes time for the applied thermosetting resin to cure.

[0152] Furthermore, the modulus of elasticity of the first adhesive 77a after hardening is higher than the modulus of elasticity of the second adhesive 77c after hardening. As a result, even if thermal expansion occurs due to a rise in temperature, the risk of the position of the substrate 50 relative to the housing 54 changing can be reduced.

[0153] The first adhesive 77a hardens by being heated in an oven at 100°C for several hours. It is desirable that the first adhesive 77a evenly distributes the stress generated between the substrate 50 and the housing 54 in the longitudinal direction of the exposure head 4. For this reason, it is desirable that the first adhesives 77a are arranged at positions that are approximately symmetrical in the short-side direction with respect to the center of the short-side direction of the substrate 50, and are arranged at approximately equal intervals in the long-side direction of the substrate 50.

[0154] Furthermore, the number of bonding locations in the longitudinal direction of the first adhesive 77a is preferably three or more in order to permanently correct warpage of the substrate 50, and seven locations is shown here as an example. Furthermore, the bonding locations in the longitudinal direction of the first adhesive 77a are preferably between adjacent pieces of the second adhesive 77c in the longitudinal direction. In other words, the bonding locations in the longitudinal direction of the second adhesive 77c are preferably between adjacent pieces of the first adhesive 77a in the longitudinal direction.

[0155] Furthermore, the first adhesive 77a is disposed at a position that does not overlap with the FFC connector 57 mounted on the back surface of the substrate 50 when viewed in the short-side direction of the substrate 50, and is disposed near the other end (one end) of the FFC connector 57 in the longitudinal direction (see FIG. 46). The first adhesive 77a is spaced apart from the FFC connector 57.

[0156] In addition, in order to reduce the influence of the second adhesive 77c, which has a large amount of thermal deformation when heated, the first adhesive 77a may be arranged a few millimeters closer to the second adhesive 77c in the longitudinal direction than at equal intervals.

[0157] Furthermore, although first adhesive 77a is disposed more inward than second adhesive 77c in the longitudinal direction, this is not a limitation, and first adhesive 77a may be disposed more outward than second adhesive 77c in the longitudinal direction. Note that the hardening speed of first adhesive 77a corresponds to the first speed, and the elastic modulus of first adhesive 77a after hardening corresponds to the first elastic modulus. Furthermore, the hardening speed of second adhesive 77c corresponds to the second speed, and the elastic modulus of second adhesive 77c after hardening corresponds to the second elastic modulus.

[0158] In the temporarily fixed lens array 52 and housing 54, the flat surface portion 54U and the side surface of the lens array 52 are bonded and permanently fixed with a fourth adhesive 77b. The fourth adhesive 77b is an epoxy-based thermosetting resin having a modulus of elasticity after hardening of several tens of GPa, a glass transition point of around 100°C, and a linear expansion coefficient of several tens of ppm / °C in the range of the actual usage temperature. The hardening speed of the fourth adhesive 77b corresponds to the third speed, and the modulus of elasticity of the fourth adhesive 77b after hardening corresponds to the third modulus of elasticity.

[0159] The fourth adhesive 77b is preferably arranged at positions that are approximately symmetrical in the short-side direction with respect to the center of the short-side direction of the lens array 52, and is also preferably arranged at approximately equal intervals in the longitudinal direction. The number of bonding locations of the fourth adhesive 77b in the long-side direction is preferably three or more in order to permanently correct the warpage of the lens array 52, and eight locations is exemplified here. In addition, the fixing locations of the fourth adhesive 77b in the long-side direction are exemplified here as being between adjacent fifth adhesives 77d in the long-side direction.

[0160] Furthermore, the fourth adhesive 77b may be disposed at a plurality of locations between adjacent fifth adhesives 77d in the longitudinal direction. Furthermore, in order to reduce the influence of the fifth adhesive 77d, which has a large amount of thermal deformation when heated, the fourth adhesives 77b do not necessarily need to be disposed at strictly equal intervals in the longitudinal direction, but may be disposed close to the fifth adhesive 77d. In this case, it is more preferable that the fourth adhesives 77b be disposed so as to sandwich the fifth adhesive 77d from both sides in the longitudinal direction.

[0161] Although the fourth adhesive 77b is disposed inside the fifth adhesive 77d in the longitudinal direction, the fourth adhesive 77b is not limited to this, and may be disposed outside the fifth adhesive 77d in the longitudinal direction.

[0162] The fourth adhesive 77b is provided at a position included in a cross section obtained by cutting the substrate 50 and the FFC connector 57 mounted on the substrate 50 along a plane (a plane parallel to the left-right (LR) direction and the up-down (DU) direction) perpendicular to the longitudinal direction (front-back (FB) direction) (see FIG. 48). That is, the fourth adhesive 77b is provided at a position overlapping in the up-down direction with the FFC connector 57 mounted on the substrate 50 when viewed from the short side direction of the substrate 50.

[0163] In the fixed substrate 50 and housing 54, the extensions 54L and 54R of the housing 54 and both ends of the shorter side of the underside of the substrate 50 are bonded and fixed and sealed with a third adhesive 59a. The third adhesive 59a is applied so as to cover the first adhesive 77a and the second adhesive 77c. A silicone moisture-curing resin, which has a lower viscosity than acrylic photo-curing resins and epoxy thermosetting resins, is used as the third adhesive 59a.

[0164] The third adhesive 59a is not limited to being applied so as to cover the first adhesive 77a and the second adhesive 77c, but may be applied at least between adjacent first adhesives 77a in the longitudinal direction of the substrate 50. Alternatively, the third adhesive 59a may be applied so as to cover at least a portion of each of the first adhesive 77a and the second adhesive 77c, or may be applied so as to cover a portion of either the first adhesive 77a or the second adhesive 77c.

[0165] In the finally fixed lens array 52 and housing 54, a sixth adhesive 59b is used to bond, fix, and seal the flat surface 54U of the housing 54 and the side surface of the lens array 52. ​​The sixth adhesive 59b is applied so as to cover the fourth adhesive 77b and the fifth adhesive 77d. A silicone moisture-curing resin, which has a lower viscosity than acrylic photo-curing resins and epoxy thermosetting resins, is used as the sixth adhesive 59b.

[0166] The sixth adhesive 59b is not limited to being applied so as to cover the fourth adhesive 77b and the fifth adhesive 77d, but may be applied at least between adjacent fourth adhesives 77b in the longitudinal direction of the substrate 50. Alternatively, the sixth adhesive 59b may be applied so as to cover at least a portion of each of the fourth adhesive 77b and the fifth adhesive 77d, or may be applied so as to cover a portion of either the fourth adhesive 77b or the fifth adhesive 77d.

[0167] <Operation of image forming device> The operation of image forming apparatus 100 according to the embodiment of the present invention will be described in detail with reference to FIGS.

[0168] The image forming apparatus 100 starts operation and executes an image forming process when image data is input from a reading device or an external host computer (not shown).

[0169] First, the charging roller 3 charges the surface of the photosensitive drum 2 .

[0170] Next, the exposure head 4 exposes the surface of the photosensitive drum 2 that has been charged by the charging roller 3. As a result, an electrostatic latent image is formed on the photosensitive drum 2.

[0171] Next, the developing unit 24 develops the electrostatic latent image formed on the photosensitive drum 2 with toner. Inside the developing unit 24, the toner is circulated and transported at high speed by the screw 7. The rotation speed of the screw 7 is relatively very high compared to the rotation speeds of the developing sleeve 5 and the photosensitive drum 2. Therefore, the screw 7 can coat the developing sleeve 5 evenly and without unevenness.

[0172] Next, the yellow toner image developed on the surface of photosensitive drum 2Y is transferred onto the intermediate transfer belt 9 by primary transfer roller 6Y. The magenta toner image developed on the surface of photosensitive drum 2M is transferred onto the intermediate transfer belt 9 by primary transfer roller 6M. The cyan toner image developed on the surface of photosensitive drum 2C is transferred onto the intermediate transfer belt 9 by primary transfer roller 6C. The black toner image developed on the surface of photosensitive drum 2K is transferred onto the intermediate transfer belt 9 by primary transfer roller 6K. These toner images are transferred onto the intermediate transfer belt 9 so as to be superimposed on each other.

[0173] The toner images of each color transferred onto the intermediate transfer belt 9 are transported by the intermediate transfer belt 9 to the secondary transfer portion T2.

[0174] The toner images conveyed to the secondary transfer portion T2 are secondarily transferred all at once by the secondary transfer roller 16 onto the recording paper P conveyed from the feeding portion 11 via the registration roller 15.

[0175] The recording paper P onto which the toner image has been secondarily transferred is transported to a fixing device 19.

[0176] The toner image is fixed onto the recording paper P conveyed to the fixing device 19 by heat and pressure in the fixing process in the fixing device 19 .

[0177] The recording paper P that has been subjected to the fixing process by the fixing unit 19 is discharged onto a discharge tray 21 by a discharge roller 20.

[0178] <Replacing the drum unit and developing unit> The operation of replacing drum unit 23 and developing unit 24 of image forming apparatus 100 according to the embodiment of the present invention will be described in detail with reference to FIGS. 4 to 9, 21 to 24, 27 and 28.

[0179] When replacing the drum unit 23 and the developing unit 24, first the exposure head 4 and the developing unit 24 are retracted and separated from the photosensitive drum 2. At this time, the exposure head 4 and the developing unit 24 are retracted from the photosensitive drum 2 by a retraction mechanism including the development stay 31, the rotary arm 65, and the lifting duct 69.

[0180] Each of the drum unit 23 and the developing unit 24 is inserted into or removed from the front side of the image forming apparatus 100, and is attached to a predetermined position (attachment position) in the apparatus main body 100a.

[0181] Specifically, when an operator replaces the drum unit 23 and the developing unit 24, the operator opens the front cover 101 as shown in Fig. 4, and then opens the inner door 102 as shown in Fig. 5. At this time, as the inner door 102 rotates, the link engagement portion 102b of the inner door 102 moves on a circular locus with the rotation center being the rotation shaft 102a and the radius being the distance between the rotation shaft 102a and the link engagement portion 102b.

[0182] As a result, the development stay link 34 engaged with the link engagement portion 102b slides rearward in the direction of arrow B. The development pressure piece 32 and the development pressure piece 33 also slide rearward in the direction of arrow B.

[0183] The developing pressure piece 32 and the developing pressure piece 33 slide backward in the direction of arrow B in Figure 28, thereby moving from a position where they hold the developing unit 24 to a position where they release the holding of the developing unit 24. In addition, the developing stay 31 releases its engagement with the rotating arm 65.

[0184] When the developer pressure piece 32 and the developer pressure piece 33 move to a position where they release the hold of the developer unit 24, the developer unit 24 moves downward, in the direction of arrow D in FIG. 28, due to its own weight along the slopes of the developer pressure piece 32 and the developer pressure piece 33. As a result, the developer sleeve 5 of the developer unit 24 moves in a direction away from the photosensitive drum 2 of the drum unit 23 and is separated from the photosensitive drum 2.

[0185] Then, after removing the drum unit 23 or developing unit 24 from the apparatus main body 100a, a new drum unit 23 or developing unit 24 is inserted into the apparatus main body 100a, and the inner door 102 and front cover 101 are closed, thereby completing the replacement work.

[0186] 27, the developing stay 31 slides forward in the direction of arrow F in conjunction with the closing of the inner door 102. At this time, the developing unit 24 moves upward in the direction of arrow U along the slopes of the developing pressure pieces 32 and 33 of the developing stay 31. The developing stay 31 also engages with the pivot arm 65.

[0187] As a result, the developing sleeve 5 of the developing unit 24 moves in a direction approaching the photosensitive drum 2 of the drum unit 23.

[0188] In this way, the developing stay 31 slides in the direction of arrow B or the direction of arrow F in conjunction with the opening and closing movement of the inner door 102. In addition, the developing unit 24 moves away from or closer to the photosensitive drum 2 in accordance with the sliding movement of the developing stay 31.

[0189] The developing stay 31 slides back and forth to move the developing unit 24 between the developing position shown in Figure 21 where the developing sleeve 5 is close to the photosensitive drum 2 and the separated position shown in Figure 22 where the developing sleeve 5 is separated from the photosensitive drum 2.

[0190] <Installation of exposure head> The mounting operation of the exposure head 4 according to the embodiment of the present invention will be described in detail with reference to FIGS. 33 to 35, 38, and 41 to 43.

[0191] The exposure head 4 is mounted with the drum unit 23 and the developing unit 24 removed from the image forming apparatus 100, as shown in Figure 34. The exposure head 4 is configured so that it can be manually moved from the retracted position to the exposure position when the photosensitive drum 2 is removed. Therefore, the exposure head 4 is mounted after it has been manually moved to the exposure position. Furthermore, the exposure head 4 is mounted with the FFC 58 connected to the apparatus main body 100a already connected to the FFC connector 57 of the exposure head 4, as shown in Figure 34.

[0192] First, the engaging claws 55b and 55c of the housing support member 55 are engaged with the engaging holes 69b and 69c of the lifting duct 69, thereby integrating the housing support member 55 and the lifting duct 69 together.

[0193] 23 relative to the lifting duct 69, the engagement claws 55b and 55c of the exposure head 4 are dropped into the engagement holes 69b and 69c of the lifting duct 69. At the same time, the lower end of the positioning pin 45F of the exposure head 4 is dropped into the auxiliary fitting portion 30h of the cartridge tray 30 with a gap therebetween.

[0194] Next, as shown in FIG. 38, the exposure head 4 is slid in the direction of arrow B relative to the lifting duct 69, so that the engaging claws 55b and 55c are engaged with the engaging holes 69b and 69c.

[0195] Specifically, just before the sliding operation of the exposure head 4 is completed, the tip of the engagement claw 55b interferes with the convex portion 69f and elastically deforms. As a result, the sliding operation force of the exposure head 4 temporarily increases compared to the operating force just before the interference. Thereafter, the concave portion 55f of the engagement claw 55b reaches the convex portion 69f and the concave portion 55f and the convex portion 69f engage with each other. As a result, the sliding operation force of the exposure head 4 decreases. This sudden increase and decrease in the sliding operation force of the exposure head 4 provides a clicking sensation, and this clicking sensation indicates that the sliding operation of the exposure head 4 has been completed.

[0196] 41 to 43, the exposure head 4 is attached to the lifting duct 69 and becomes one with the lifting duct 69. The above-described attachment operation of the exposure head 4 makes it possible to easily attach the exposure head 4 with an inexpensive configuration.

[0197] Furthermore, by sliding the exposure head 4, the positioning pin 45F can be electrically connected to the conductive member 251, thereby connecting the exposure head 4 to earth. This allows the exposure head 4 to be connected to earth or the like by a simple operation of sliding alone, and also makes it possible to obtain stable earthing characteristics by suppressing the generation of radiation noise such as electromagnetic waves.

[0198] <Exposure head positioning method> A method for positioning the exposure head 4 according to the embodiment of the present invention will be described in detail with reference to FIGS.

[0199] 29 does not show the drum unit 23 and the developing unit 24, and shows only the exposure head 4, the lifting duct 69, and the cartridge tray 30. Also, although Figures 30 and 31 show a cross section of the front drum bearing 26, the rear drum bearing 26 has a similar shape.

[0200] The positioning pins 45B and 45F are provided on the housing 54 to ensure with high precision the distance between the surface of the photosensitive drum 2 and the light exit surface of the lens array 52 of the exposure head 4. The positioning pins 45F and 45B are also provided on the housing 54 to fix the angle of the exposure head 4.

[0201] The diameter of the tip of the positioning pins 45F and 45B in the direction facing the drum bearing 26, and the width of the engaging portions 26F and 26B of the drum bearing 26 are machined with high precision. This allows for highly accurate positioning in the direction perpendicular to the optical axis direction of the exposure head 4 and the direction perpendicular to the axial direction of the photosensitive drum 2. The positioning pins 45F and 45B do not contact the drum bearing 26 in the axial direction of the photosensitive drum 2, and are positioned by a positioning member (not shown).

[0202] 30, the pressing position where the engagement boss 66 presses the lift-up duct 69, the contact position between the positioning pins 45F and 45B and the engagement portions 26F and 26B, and the center position of the photosensitive drum 2 are arranged on approximately the same straight line. With this arrangement, the exposure head 4 is pressed toward the center of the photosensitive drum 2, so no unnecessary rotational moment is applied to the lift-up duct 69. Therefore, it is possible to eliminate a component in the pressing force that presses the exposure head 4 that promotes tilting of the exposure head 4 with respect to the photosensitive drum 2, thereby improving the positioning accuracy and the stability of repeated attachment and detachment operations.

[0203] 31 and 32, the lower end peripheral surfaces of the positioning pins 45F and 45B are fitted into the auxiliary fitting portions 30h and 30i of the cartridge tray 30. This makes it possible to improve positioning accuracy and achieve stable repeated attachment and detachment operations even when a slight rotational moment occurs due to the weight, surface roughness, or dimensional error of the parts.

[0204] <Exposure head manufacturing method> A method for manufacturing the exposure head 4 according to the embodiment of the present invention will be described in detail with reference to FIGS. 10 to 12 and 14 to 18. FIG.

[0205] First, the substrate 50 is inserted through the second opening 54b of the housing 54.

[0206] Next, in a state where the substrate 50 is spaced apart from the extending portions 54L and 54R, the substrate 50 and the extending portions 54L and 54R are fixed together with a first adhesive 77a and a second adhesive 77c. At this time, the position of the substrate 50 in the focal direction is adjusted with a jig (not shown).

[0207] In addition, with the lens array 52 inserted into the first opening 54a and with the lens array 52 spaced apart from the flat surface 54U, the lens array 52 and the flat surface 54U are fixed together with a fourth adhesive 77b and a fifth adhesive 77d. At this time, the position and tilt of the lens array 52 in the focal direction are adjusted with a jig (not shown) so that the distance in the focal direction between the lens array 52 and all of the LED chips 53 mounted on the substrate 50 becomes a predetermined value.

[0208] After the substrate 50 is positioned and fixed to the housing 54, the gaps between the substrate 50 and the extensions 54L and 54R are sealed with a third adhesive 59a, thereby preventing the LEDs 51 from being contaminated by external toner or dust.

[0209] Furthermore, after the lens array 52 is positioned and fixed to the housing 54, the gap between the lens array 52 and the flat surface portion 54U is sealed with the sixth adhesive 59b. This reduces the possibility that dust such as toner will flow in through the gap between the lens array 52 and the flat surface portion 54U and block the light emitted from the LEDs 51.

[0210] In the exposure head 4 manufactured by the above manufacturing method, the substrate 50 and the lens array 52 are held by the housing 54, so that the LEDs 51 and the lens incident surface 506b face each other. As a result, light emitted from the LEDs 51 is incident on the lens incident surface 506b and then emitted from the lens exit surface 506a towards the photosensitive drum 2.

[0211] Here, light emitted from the multiple LEDs 51 can pass through one and the same lens. Also, light emitted from one LED 51 can pass through multiple lenses because it travels radially. That is, the light emitted from the multiple LEDs 51 passes through some of the multiple lenses 521 of the lens array 52 to expose the photosensitive drum 2.

[0212] <Effects of the image forming apparatus and the exposure head> The effects of the configurations of the image forming apparatus 100 and the exposure head 4 according to the embodiment of the present invention will be described in detail below.

[0213] In the above-described bonding and sealing mechanism between the housing 54, the substrate 50, and the lens array 52, a second adhesive 77c, which is a photocurable resin that can be hardened in a short time even at room temperature, is used when temporarily fixing the housing 54 and the substrate 50. Furthermore, a fifth adhesive 77d, which is a photocurable resin that can be hardened in a short time even at room temperature, is used when temporarily fixing the housing 54 and the lens array 52. ​​This makes it possible to shorten the time required to hold each component, such as the housing 54, the substrate 50, and the lens array 52, with a tool or the like when fixing the substrate 50 and the lens array 52 to the housing 54 while keeping them apart.

[0214] Furthermore, a first adhesive 77a, which is a thermosetting resin, is used when finally fixing the housing 54 and the substrate 50. Furthermore, a fourth adhesive 77b, which is a thermosetting resin, is used when finally fixing the housing 54 and the lens array 52. ​​This makes it possible to improve the positional accuracy when fixing the substrate 50 and the lens array 52 to the housing 54 in a spaced-apart state or after fixing, and it is possible to give the exposure head 4 high rigidity and improve its strength against temperature changes.

[0215] Furthermore, by providing the first adhesive 77a, the fourth adhesive 77b, the second adhesive 77c, and the fifth adhesive 77d at equal intervals along the longitudinal direction, the housing 54, the substrate 50, and the lens array 52 can be fixed in a stable state.

[0216] In addition, the first adhesive 77a, the fourth adhesive 77b, the second adhesive 77c, and the fifth adhesive 77d are provided at positions symmetrical in the short-side direction with respect to the center of the short-side direction of the substrate 50. This allows the housing 54, the substrate 50, and the lens array 52 to be fixed in a stable state.

[0217] Here, various electrical components such as a driving IC, resistors, capacitors, thermistors, and FFC connector 57 are mounted on the underside of substrate 50. Thermosetting resins and photocurable resins shrink when cured, and thermally expand or contract when the temperature changes after curing. If such thermosetting resins or photocurable resins adhere to electrical components, they may generate stress or distortion in the electrical components, damaging them or deforming substrate 50 and deteriorating imaging characteristics.

[0218] Therefore, by shifting the positions of the first adhesive 77a and the second adhesive 77c in the longitudinal direction from strictly equal intervals depending on the position where the electrical components are mounted on the substrate 50, damage to the electrical components and deterioration of imaging characteristics can be prevented.

[0219] Specifically, by positioning the first adhesive 77a and the second adhesive 77c in the longitudinal direction in a range that does not overlap with the electrical components when viewed from the short side of the substrate 50, damage to the electrical components and deterioration of imaging characteristics can be prevented.

[0220] Furthermore, when inserting or removing the FFC 58 into or from the FFC connector 57, the exposure head 4 may be deformed or damaged due to the resistance to insertion or removal of the FFC 58 or due to the grip of the housing 54, which may result in a deterioration in imaging characteristics. Therefore, by arranging a first adhesive 77a near one end of the FFC connector 57 in the longitudinal direction and a second adhesive 77c near the other end of the FFC connector 57 in the longitudinal direction, the load generated by gripping the housing 54 can be supported by the housing 54.

[0221] Here, if only the first adhesive 77a is placed near both longitudinal ends of the FFC connector 57, the longitudinal pitch of the second adhesive 77c will increase, which may reduce rigidity during temporary fixation. Therefore, it is desirable to place the first adhesive 77a near one longitudinal end of the FFC connector 57 and the second adhesive 77c near the other longitudinal end of the FFC connector 57. Furthermore, it is desirable to set the distance between the first adhesive 77a and the FFC connector 57 and the distance between the second adhesive 77c and the FFC connector 57 within a range of 2 to 10 mm.

[0222] In the present embodiment, the first adhesive 77a is disposed near the front end of the FFC connector 57, and the second adhesive 77c is disposed near the rear end of the FFC connector 57. However, this is not limiting, and the second adhesive 77c may be disposed near the front end of the FFC connector 57, and the first adhesive 77a may be disposed near the rear end of the FFC connector 57.

[0223] Furthermore, the fourth adhesive 77b that finally fixes the housing 54 and the lens array 52 is disposed in at least one position that overlaps with the FFC connector 57 in the vertical direction as viewed from the short-side direction of the substrate 50. This makes it possible to suppress deformation of the housing 54 when gripping both ends in the short-side direction of the portion of the housing 54 where the FFC connector 57 is mounted on the substrate 50 when inserting or removing the FFC 58 into or from the FFC connector 57.

[0224] Furthermore, by using a low-viscosity moisture-curing resin as the third adhesive 59a, the third adhesive 59a can be made to conform to the shapes of the first adhesive 77a and the second adhesive 77c. This allows the third adhesive 59a to penetrate into the gap between the extension 54L of the housing 54 and the substrate 50, and the gap between the extension 54R of the housing 54 and the substrate 50, thereby reliably sealing the gaps.

[0225] Similarly, by using a low-viscosity moisture-curing resin as the sixth adhesive 59b, the sixth adhesive 59b can be made to conform to the shapes of the fourth adhesive 77b and the fifth adhesive 77d. This allows the sixth adhesive 59b to enter the gap between the extension 54L of the housing 54 and the lens array 52, and the gap between the extension 54R of the housing 54 and the lens array 52, thereby reliably sealing the gaps.

[0226] Furthermore, by using moisture-curing resin as the third adhesive 59a and the sixth adhesive 59b, the third adhesive 59a and the sixth adhesive 59b can be easily cured in a normal temperature and humidity environment without using any special device for curing.

[0227] In this embodiment, first adhesives 77a made of a thermosetting resin are used to fix the substrate 50 and the housing 54 in a spaced-apart state at multiple locations in the longitudinal direction of the substrate 50. Also, a third adhesive 59a of a different type from the first adhesive 77a is used to fix the substrate 50 and the housing 54 in a spaced-apart state at least between adjacent first adhesives 77a in the longitudinal direction of the substrate 50. This makes it possible to obtain good imaging characteristics and high rigidity.

[0228] In this embodiment, fourth adhesive 77b made of a thermosetting resin is used to fix lens array 52 and housing 54 in a spaced-apart state at multiple locations in the longitudinal direction of lens array 52. ​​Also, sixth adhesive 59b of a different type to fourth adhesive 77b is used to fix lens array 52 and housing 54 in a spaced-apart state at least between adjacent fourth adhesives 77b in the longitudinal direction of substrate 50. This makes it possible to obtain good imaging characteristics and high rigidity.

[0229] According to this embodiment, the housing 54 and the substrate 50 are fixed together using a first adhesive 77a made of a thermosetting resin and a third adhesive 59a of a different type than the first adhesive 77a, thereby making it possible to make the exposure head 4 highly rigid.

[0230] According to this embodiment, the housing 54 and the lens array 52 are fixed together using a fourth adhesive 77b made of a thermosetting resin and a sixth adhesive 59b of a different type from the fourth adhesive 77b, thereby making it possible to make the exposure head 4 highly rigid.

[0231] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit and scope of the present invention.

[0232] Specifically, in the above embodiment, a bottom exposure method in which the photosensitive drum 2 is exposed from below is used, but this is not limiting, and a top exposure method in which the photosensitive drum 2 is exposed from above may also be used.

[0233] Furthermore, in the above embodiment, an intermediate transfer method using the intermediate transfer belt 9 is used, but this is not limiting, and a direct transfer method in which the image is transferred directly from the photosensitive drum 2 to the recording paper P may also be used.

[0234] Furthermore, in the above embodiment, the positions of the housing 54 and the substrate 50, and the positions of the housing 54 and the lens array 52 are adjusted, but this is not limiting. The substrate 50 may be positioned by abutting it against the housing 54, and only the positions of the housing 54 and the lens array 52 may be adjusted. Alternatively, the lens array 52 may be positioned by abutting it against the housing 54, and only the positions of the housing 54 and the substrate 50 may be adjusted. In the case of a configuration in which the lens array 52 is positioned by abutting it against the housing 54, a low elastic modulus of the adhesive may be acceptable in some cases, and therefore a thermosetting resin may be used only to fix the substrate 50 or the lens array 52, the positions of which are adjusted relative to the housing 54.

[0235] Furthermore, in the above embodiment, the substrate 50 is fixed to the housing 54 using only the first adhesive 77a, the third adhesive 59a, and the second adhesive 77c. However, this is not limiting, and the heat sink or reinforcing member of the substrate assembly unitized by fixing an elongated heat sink or reinforcing member to the housing 54 may be fixed using the first adhesive 77a, the second adhesive 77c, and the third adhesive 59a. In this case, the heat sink or reinforcing member is made of aluminum, iron, resin, or the like.

[0236] In addition, in the above embodiment, moisture-curing resin is used as the third adhesive 59a and the sixth adhesive 59b, but this is not limited to this, and a type of resin other than a moisture-curing resin and a thermosetting resin other than the moisture-curing resin may be used as the third adhesive 59a and the sixth adhesive 59b.

[0237] Furthermore, in the above embodiment, the housing 54 is fixed in a spaced-apart state from both the substrate 50 and the housing 54, but this is not limited to this, and the housing 54 may be fixed in a spaced-apart state from only one of the substrate 50 and the housing 54. [Explanation of symbols]

[0238] 1 Image forming unit 2 Photosensitive drum 3 Charging roller 4 Exposure head 5 Developing sleeve 50 boards 51 LED 52 Lens Array 53 LED chips 54 Case 57 FFC Connector 59a The Third Adhesive 59b The Sixth Adhesive 77a First Adhesive 77b The Fourth Glue 77c Second Adhesive 77d The Fifth Glue 100 Image forming device 101a Device body

Claims

1. An exposure head that exposes a photosensitive member, a light-emitting chip arranged in a rotational axis direction of the photosensitive member and having a plurality of light-emitting portions that emit light to expose the photosensitive member; a substrate on which the light emitting chip is mounted; a lens that focuses the light emitted from the light-emitting chip onto the surface of the photosensitive member; a housing for holding the substrate and the lens; a first adhesive that bonds the housing and the substrate, the first adhesive curing at a first speed and having a first modulus of elasticity after curing; a second adhesive that bonds the housing and the substrate, the second adhesive curing at a second rate and having a second modulus of elasticity after curing; Equipped with the second speed is greater than the first speed, and the first modulus of elasticity is greater than the second modulus of elasticity; An exposure head characterized by:

2. The first adhesive is It has the property of hardening when heat is applied.

2. The exposure head according to claim 1.

3. The second adhesive is 3. The exposure head according to claim 2, wherein the exposure head has a property of being hardened by irradiation with light.

4. The exposure head includes: a third adhesive provided along the longitudinal direction of the substrate to seal between the substrate and the housing; 2. The exposure head according to claim 1.

5. The exposure head includes: a fourth adhesive that bonds the housing and the lens, the fourth adhesive curing at a third speed and having a third modulus of elasticity after curing; a fifth adhesive that bonds the housing and the lens, the fifth adhesive curing at a fourth speed and having a fourth modulus of elasticity after curing; The exposure head according to claim 4 , further comprising:

6. the fourth speed is greater than the third speed, and the third modulus of elasticity is greater than the fourth modulus of elasticity; 6. The exposure head according to claim 5.

7. The first adhesive is The substrate and the housing are bonded to each other at a plurality of locations that are different in position in the longitudinal direction of the housing.

2. The exposure head according to claim 1.

8. The second adhesive is The adhesive is applied between adjacent first adhesives in the longitudinal direction.

8. The exposure head according to claim 7.

9. The second adhesive is The substrate and the housing are bonded to each other at a plurality of locations that are different in position in the longitudinal direction.

9. The exposure head according to claim 8.

10. The first adhesive is The second adhesive is applied between adjacent ones of the second adhesive in the longitudinal direction.

10. The exposure head according to claim 9.

11. The plurality of light-emitting units include: It is an organic EL, 2. The exposure head according to claim 1.

Images