Light-emitting device, exposure device and image forming device

Abstract

This invention relates to a light-emitting device, an exposure device, and an image forming apparatus. A light-emitting device comprises: a light-emitting part, in which a light-emitting element emitting light in a light-emitting direction intersecting the first direction is held within a resin frame extending in one direction; a suppressing member, extending in the first direction and suppressing deformation of the frame caused by heat, and having a different coefficient of linear expansion than the frame; and a fixing part, which fixes the frame and the suppressing member at a position where the light-emitting direction overlaps with the neutral axis of the frame, the light-emitting part, or the suppressing member in the light-emitting direction, at a plurality of locations separated along the first direction or extending along the first direction.

Description

TECHNICAL FIELD

[0001] The present application relates to a light emitting device, an exposure apparatus, and an image forming apparatus. BACKGROUND

[0002] Patent Document 1 describes an exposure apparatus including a substrate having a plate-shaped main body portion extending in one direction, a plurality of light emitting elements mounted on one face of the main body portion, and a heat generating element mounted on the other face of the main body portion and generating heat in conjunction with light emitting operation of the light emitting elements; a resin frame extending in the one direction and having a through hole, and the substrate is fixed inside the through hole in such a manner that the plate thickness direction of the substrate becomes the through direction of the through hole; and a suppression member extending in the one direction and embedded in the through hole, and suppressing thermal deformation of the frame.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-001567 SUMMARY

[0004] The present application relates to a light emitting device, an exposure apparatus, and an image forming apparatus.

[0005] The light emitting device according to the first aspect includes a light emitting portion that holds a light emitting element that emits light in a light emitting direction intersecting the one direction in a frame made of resin extending in the one direction; a suppression member that extends in the one direction and suppresses deformation of the frame caused by heat, and has a linear expansion rate different from that of the frame; and a fixing portion that fixes the frame and the suppression member at a plurality of positions separated in the one direction or in a manner extending in the one direction at a position overlapping a neutral axis of the frame or the light emitting portion or a neutral axis of the suppression member in the light emitting direction.

[0006] The light emitting device according to the second aspect includes the light emitting device according to the first aspect, and the fixing portion overlaps the neutral axis of the frame or the light emitting portion in the light emitting direction.

[0007] The light emitting device according to the third aspect includes the light emitting device according to the second aspect, and the fixing portion overlaps both the neutral axis of the frame or the light emitting portion and the neutral axis of the suppression member in the light emitting direction.

[0008] The light emitting device according to the fourth aspect includes the light emitting device according to any one of the first to third aspects, and the width of the suppression member is greater than the width of the frame as viewed in the one direction.

[0009] The light emitting device according to the fifth aspect, in the light emitting device according to the fourth aspect, the suppression member has an opening portion that is open to the light emission direction, at least a portion of the frame body is disposed inside the suppression member, and the fixing portion is disposed on the side opposite to the light emission direction with respect to a rim portion of the opening portion.

[0010] The exposure device according to the sixth aspect includes the light emitting device according to any one of the first to fifth aspects, and an optical member that is fixed to the frame body to constitute the light emitting portion and exposes light emitted from the light emitting device to an exposure target.

[0011] The image forming apparatus according to the seventh aspect includes an image holding body, the exposure device according to the sixth aspect that forms an electrostatic latent image by imaging light on the charged image holding body, and a developing device that forms an image by developing the electrostatic latent image of the image holding body.

[0012] Effects of Invention

[0013] According to the light emitting device according to the first aspect, compared with a structure in which the fixing frame body and the fixing portion of the suppression member are both away from the neutral axis of the frame body or the light emitting portion or the suppression member in the up-and-down direction of the device in the light emission direction, deformation of the frame body in the light emission direction caused by heat is suppressed.

[0014] According to the light emitting device according to the second aspect, compared with a structure in which the fixing frame body and the fixing portion of the suppression member are both away from the neutral axis of the frame body or the light emitting portion or the suppression member in the up-and-down direction of the device in the light emission direction, deformation of the frame body in the light emission direction caused by heat is suppressed.

[0015] According to the light emitting device according to the third aspect, compared with a structure in which the fixing frame body and the fixing portion of the suppression member are both away from the neutral axis of the frame body or the light emitting portion or the suppression member in the up-and-down direction of the device in the light emission direction, deformation of the frame body in the light emission direction caused by heat is suppressed.

[0016] According to the light emitting device according to the fourth aspect, compared with a structure in which the width of the suppression member is smaller than the width of the frame body when viewed from a direction, flexion of the frame body is suppressed.

[0017] According to the light emitting device according to the fifth aspect, compared with a structure in which the fixing frame body and the fixing portion of the suppression member are both away from the neutral axis of the frame body or the light emitting portion or the suppression member in the up-and-down direction of the device in the light emission direction, deformation of the frame body in the light emission direction caused by heat is suppressed.

[0018] According to the exposure device according to the sixth aspect, compared with a structure in which the fixing frame body and the fixing portion of the suppression member are both away from the neutral axis of the frame body or the light emitting portion or the suppression member in the up-and-down direction of the device in the light emission direction, exposure failure is suppressed.

[0019] According to the image forming apparatus relating to the seventh aspect, compared with the structure in which the fixed frame and the fixed portion of the suppression member are away from the neutral axis of the frame or the light emitting portion or the suppression member in the up-and-down direction of the apparatus, the image forming failure is suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0020] The embodiments of the present application will be described in detail based on the following drawings.

[0021] Figure 1 is a side view of an exposure apparatus relating to the embodiments of the present application;

[0022] Figure 2 is a C-C cross-sectional view of Figure 1

[0023] Figure 3 is an exploded perspective view of an exposure apparatus relating to the embodiments of the present application;

[0024] Figure 4 is a front cross-sectional view of an exposure apparatus relating to the comparative example of the embodiments of the present application;

[0025] Figure 5 is a front cross-sectional view of an exposure apparatus relating to the modified example of the embodiments of the present application;

[0026] Figure 6 is a front cross-sectional view of an exposure apparatus relating to the modified example of the embodiments of the present application;

[0027] Figure 7 is a front cross-sectional view of an exposure apparatus relating to the modified example of the embodiments of the present application;

[0028] Figure 8 is a front cross-sectional view of an exposure apparatus relating to the modified example of the embodiments of the present application;

[0029] Figure 9 is a schematic front view showing the structure of an image forming apparatus relating to the embodiments of the present application.

[0030] SYMBOL EXPLANATION

[0031] 10 - image forming apparatus, 36 - photosensitive drum (one example of image holding body) (one example of exposure object), 40 - developing apparatus, 50 - exposure apparatus, 50a - light emitting apparatus, 50b - light emitting portion, 52 - lens array (one example of optical member), 60 - frame, 70 - adhesive (one example of fixed portion), 80 - suppression member, 82c - opening portion, K1 - neutral axis of frame, Y1 - neutral axis of suppression member. DETAILED DESCRIPTION

[0032] According to the image forming apparatus relating to the seventh aspect, Figures 1-9 ​An example of a light emitting device, an exposure device, and an image forming apparatus according to an embodiment of the present invention will be described.

[0033] In addition, in the following description, when the image forming apparatus 10 is viewed from the front side of the user (omitted from the drawing) standing side, the apparatus upward direction (height direction), the apparatus width direction (horizontal direction), and the apparatus depth direction (horizontal direction) are respectively denoted as the H direction, the W direction, and the D direction. Also, when it is necessary to distinguish one side and the other side of each of the apparatus upward direction, the apparatus width direction, and the apparatus depth direction, on the front view, the upper side of the image forming apparatus 10 is denoted as the +H side, the lower side is denoted as the -H side, the right side is denoted as the +W side, the left side is denoted as the -W side, the inside is denoted as the -D side, and the front side is denoted as the +D side.

[0034] (Image forming apparatus 10)

[0035] The image forming apparatus 10 according to the present embodiment is an electrophotographic image forming apparatus that forms a toner image in a sheet member P as a recording medium and performs fixing. As shown in Figure 9 The image forming apparatus 10 has a frame 10A as an apparatus main body, a housing portion 26, a conveying portion 16, and an image forming portion 20. The housing portion 26 has a function of housing the sheet member P. The conveying portion 16 has a function of conveying the sheet member P housed in the housing portion 26 to the image forming portion 20 side.

[0036] The image forming portion 20 has photosensitive drum units 18Y, 18M, 18C, 18K, a transfer unit 14, and a fixing unit 48. In addition, the "Y" at the end of the symbol indicates yellow, the "M" indicates magenta, the "C" indicates cyan, and the "K" indicates black.

[0037] The photosensitive drum units 18Y, 18M, 18C, 18K are arranged inside the frame 10A when viewed from the front of the image forming apparatus 10. The photosensitive drum units 18Y, 18M, 18C, 18K have the same structure except for the toner (omitted from the drawing) used. Therefore, the photosensitive drum unit 18K is denoted by a symbol indicating the structure of the photosensitive drum unit, and the photosensitive drum units 18Y, 18M, 18C are omitted. Also, when the photosensitive drum units 18Y, 18M, 18C, 18K are not particularly distinguished, the letter at the end of the notation is omitted.

[0038] The photosensitive body unit 18 has a photosensitive drum 36, a charging device 38, an exposure device 50, and a developing device 40. The photosensitive drum 36 is disposed so as to be rotatable in a direction in which the image forming apparatus 10 is viewed frontally, and is rotated counterclockwise from the front of the image forming apparatus 10 by a motor not shown. Also, the photosensitive drum 36 has a function of holding an electrostatic latent image on an outer circumferential surface. The photosensitive drum 36 is an example of an image holding body. The charging device 38 has a function of charging the outer circumferential surface of the photosensitive drum 36 to a predetermined potential. The exposure device 50 is disposed at a position separated from the photosensitive drum 36 by a predetermined distance. The exposure device 50 has a function of forming an electrostatic latent image by causing light to be imaged on the charged photosensitive drum 36. The developing device 40 has a function of forming a toner image by developing the electrostatic latent image formed on the photosensitive drum 36 using a developer (not shown) containing toner. Also, the exposure device 50 will be described in detail later.

[0039] Also, as shown in Figure 1 the photosensitive body unit 18 has a positioning member 90 which contacts a later-described upper surface portion 68 of the exposure device 50 and positions the exposure device 50 with respect to the photosensitive drum 36. Also, the photosensitive body unit 18 has a force applying mechanism 94 which applies a force to the exposure device 50 so that the upper surface portion 68 of the exposure device 50 is in contact with the positioning member 90.

[0040] The transfer unit 14 is configured to include an intermediate transfer belt 22, a plurality of primary transfer rollers 44, a driving roller 32, a secondary transfer roller 34, and a counter roller 46. The intermediate transfer belt 22 is a ring-shaped conveyance belt whose inner circumferential surface is supported by the primary transfer rollers 44, the driving roller 32, and the secondary transfer roller 34, and is rotated clockwise from the front of the image forming apparatus 10 by the driving roller 32.

[0041] The transfer unit 14 has a function of transferring the toner images formed by the photosensitive body units 18Y, 18M, 18C, and 18K to the sheet member P conveyed from the conveyance section 16 via the intermediate transfer belt 22 and conveying the sheet member P to the fixing unit 48.

[0042] The fixing unit 48 has a function of fixing the toner images transferred to the sheet member P by the transfer unit 14 to the sheet member P and discharging the sheet member P to the outside of the apparatus.

[0043] {Exposure Device 50}

[0044] Next, the exposure device 50 will be described.

[0045] As Figures 1-3As shown, the exposure apparatus 50 includes a light-emitting device 50a and a balance weight 54. The light-emitting device 50a includes a light-emitting part 50b, a suppressing member 80, and an adhesive 70. The light-emitting part 50b includes a frame 60, a light-emitting substrate 56, and a lens array 52. ​​In the description of the exposure apparatus 50, the frame 60, the light-emitting substrate 56, the lens array 52, the suppressing member 80, the adhesive 70, and the balance weight 54 will be described in that order.

[0046] [Frame 60]

[0047] like Figures 1-3 As shown, the frame 60 is a resin component extending along the depth direction of the device and having an upper surface portion 68 and a lower surface portion 60b along both the depth and width directions of the device. The frame 60 also has a side surface portion 60a along both the depth and vertical directions of the device. Figure 2 As shown, an upper recess 62 is formed in the frame 60, which is rectangularly recessed in the upper surface portion 68 of the frame 60 and has a bottom surface 62a extending along the depth direction and width direction of the device. Furthermore, a lower recess 64 is formed in the frame 60, which is rectangularly recessed in the lower surface portion 60b of the frame 60 and has a bottom surface 64a extending along the depth direction and width direction of the device. Moreover, a through hole 66 is formed in the frame 60, extending through the bottom surface 62a of the upper recess 62 and the bottom surface 64a of the lower recess 64 in the vertical direction of the device.

[0048] like Figure 1 As shown, a portion of each end of the upper surface portion 68 of the frame 60 in the device depth direction contacts the positioning member 90 of the photoreceptor unit 18. The frame 60, through the contact between the upper surface portion 68 and the positioning member 90 of the photoreceptor unit 18, positions the exposure device 50 relative to the vertical direction of the photosensitive drum 36.

[0049] Parts of both ends of the lower surface portion 60b of the frame 60 in the device depth direction contact the end portion 86 of the suppression member 80 described later. Furthermore, the lower surface portion 60b of the frame 60 is a portion that bears the force of the force-applying mechanism 94 that applies force to the frame 60 via the end portion 86 to make the upper surface portion 68 of the frame 60 contact the positioning member 90 of the photosensitive unit 18.

[0050] Figure 2 The symbol K1 shown is the neutral axis in the vertical direction of the device in the frame 60. The neutral axis K1 is defined as an imaginary surface in the frame 60 that does not produce tensile and compressive stresses caused by the bending moment around the width direction of the device imposed on the frame 60, i.e., the neutral plane, when viewed from the depth direction of the device.

[0051] [Light-emitting substrate 56]

[0052] like Figure 3As shown, the light-emitting substrate 56 includes a substrate body 56a, namely an LED array 56b.

[0053] The substrate body 56a is a rectangular plate extending along the depth direction of the device with its thickness along the vertical direction. The lengths of the substrate body 56a in both the device depth and width directions are shorter than the lengths of the lower recess 64 of the frame 60 in both the device depth and width directions, but longer than the lengths of the through hole 66 in both the device depth and width directions. Furthermore, the thickness of the substrate body 56a in the vertical direction is less than the depth of the lower recess 64 in the vertical direction. Figure 2 As shown, the substrate body 56a is in contact with the bottom surface 64a of the lower recess 64 in such a way that it covers the through hole 66 from below, and is fixed to the frame 60 by an adhesive or the like.

[0054] like Figure 3 As shown, the LED array 56b consists of a plurality of LEDs arranged in a staggered pattern on the upper surface of the substrate body 56a along the depth direction of the device and emitting light upwards. In other words, the light emission direction of the LED array 56b is upwards. That is, the light-emitting portion 50b, which includes the light-emitting substrate 56 with the LED array 56b and the frame 60, emits light upwards. Here, LED stands for Light Emitting Diode. An LED is an example of a light-emitting element. The light-emitting substrate 56 heats up as the LED array 56b emits light (irradiates).

[0055] <Lens Array 52>

[0056] like Figure 2 As shown, the lens array 52 is a cuboid component extending along the depth direction of the device. Specifically, the lens array 52 is constructed by arranging a plurality of rod-shaped lenses (cylindrical lenses) with the vertical direction of the device as the optical axis in an alternating manner along the depth direction of the device, clamping them between two plate components, and bonding them with an adhesive or the like. The length of the lens array 52 in the device depth direction is shorter than the length of the upper recess 62 of the frame 60 in the device depth direction, but longer than the length of the through hole 66 in the device depth direction. Furthermore, the height of the lens array 52 in the device vertical direction is greater than the depth of the upper recess 62 in the device vertical direction. Figure 3 and Figure 4 As shown, when viewed from the depth direction of the device, a portion of the upper surface of the lens array 52 protrudes from the upper recess 62, and the lower surface of the lens array 52 is positioned in the upper recess 62 such that it covers the through hole 66 from above. In this state, the lens array 52 is fixed to the frame 60 by an adhesive or the like. Furthermore, a sealant 58 is filled throughout the circumference of the lens array 52 in the gap between the upper recess 62 and the lens array 52.

[0057] The lens array 52 is configured such that each LED of the LED array 56b is positioned opposite each rod-shaped lens of the lens array 52 at a predetermined position. Furthermore, the lens array 52 is configured such that when the upper surface 68 of the frame 60 contacts the positioning member 90 of the photoreceptor unit 18, the upper surface of the lens array 52 is positioned opposite the photosensitive drum 36. Thus, the exposure apparatus 50 can image (expose) light emitted from the LED array 56b and transmitted through the lens array 52 at a predetermined target position on the surface of the photosensitive drum 36. The lens array 52 is an example of an optical component. The photosensitive drum 36 is an example of an exposure object. The exposure apparatus 50 has the function of forming an electrostatic latent image on the photosensitive drum 36 by imagerizing light emitted from the LED array 56b onto the charged photosensitive drum 36.

[0058] <Suppression Component 80>

[0059] like Figure 3 As shown, the suppressing component 80 is a component formed of a metal plate and extending along the depth direction of the device. The linear expansion rate of the suppressing component 80 is greater than that of the frame 60. That is, the linear expansion rate of the suppressing component 80 is different from that of the frame 60. Figures 1-3 As shown, the suppressing member 80 is fixed to the frame 60 by covering the lower recess 64 of the frame 60 from below. The suppressing member 80 has a main body portion 82, a bent portion 84, and an end portion 86.

[0060] like Figures 2-3 As shown, the main body 82 is a portion having a U-shaped cross-section that opens upwards when viewed from the depth direction of the device and extends along the depth direction of the device. The pair of sidewalls and the bottom of the U-shaped cross-section of the main body 82 are referred to as sidewall 82a and bottom 82b, respectively. Furthermore, the portion clamped by the upper edges of the two sidewalls 82a is referred to as opening 82c. Figure 1 and Figure 2 As shown, the suppressing member 80 is configured such that the bottom 82b of the main body 82 is away from the lower surface of the frame 60, and a pair of sidewalls 82a clamp the side surface 60a of the frame 60. That is, the width of the suppressing member 80 as viewed from the width direction of the device is greater than the width of the frame 60. In other words, a portion of the frame 60 is disposed inside the suppressing member 80. Furthermore, the suppressing member 80 is configured such that the edge of the opening 82c (the upper edge of the sidewall 82a) is located above the central axis K1 of the frame 60. Alternatively, the entire frame 60 may be disposed inside the suppressing member 80.

[0061] like Figure 1 and Figure 2As shown, a plurality of through-holes 82d that penetrate the side walls 82a in the plate thickness direction and are arranged in the device depth direction are formed in the side walls 82a at positions that overlap the neutral axis K1 of the frame 60 and the neutral axis Y1 (details will be described later) of the suppression member 80 in the device up-down direction. The suppression member 80 is fixed to the frame 60 by the adhesive 70 (details will be described later) that is injected into the through-holes 82d of the pair of side walls 82a that hold the side surface portion 60a of the frame 60 and solidified.

[0062] The bent portions 84 are portions that are arranged at both ends in the device depth direction of the bottom portion 82b and have an L-shaped cross section that extends in the device up-down direction and the device depth direction as viewed in the device width direction, and are rectangular as viewed in the device depth direction. The bent portions 84 have leg portions 84a that stand in the device up-down direction and bottom portions 84b that extend in the device depth direction from lower ends of the leg portions 84a. The bottom portions 84b of the bent portions 84 are connected to the bottom portion 82b of the main body portion 82. In other words, the two bent portions 84 are arranged so as to hold the main body portion 82 in the device depth direction. Also, the leg portions 84a of the bent portions 84 are distanced from the lower surface of the frame 60.

[0063] The end portions 86 are portions that are rectangular as viewed in the device up-down direction and are formed so as to expand toward the side opposite to the main body portion 82 in a direction that is in the device depth direction and the device width direction from upper ends of the leg portions 84a. The suppression member 80 is fixed to the frame 60 in a state in which the upper surfaces of the end portions 86 are in contact with the lower surface portion 60b of the frame 60. Also, the end portions 86 overlap the respective upper surface portions 68 of the frame 60 in the device up-down direction as viewed in the device width direction.

[0064] The suppression member 80 is fixed to the frame 60 in such a manner that the main body portion 82 holds the side surface portion 60a of the frame 60, and has a function of making it difficult for the frame 60 that extends in the device depth direction to bend in the device up-down direction compared to the frame 60 alone. That is, the suppression member 80 has a function of suppressing deformation of the frame 60.

[0065] Figure 2 The symbol Y1 shown is the neutral axis in the device up-down direction of the suppression member 80. The neutral axis Y1 defines an imaginary line that is an imaginary plane in the suppression member 80 in which tensile stress and compressive stress caused by a bending moment around the device width direction imparted to the suppression member 80 does not occur.

[0066] <Adhesive 70>

[0067] Adhesive 70 is injected into a plurality of through holes 82d formed along the depth direction of the device on the sidewall 82a of the suppressing member 80. In this embodiment, the adhesive 70 fixes the frame 60 and the suppressing member 80 by being injected into the plurality of through holes 82d and cured. That is, in this embodiment, the adhesive 70 fixes the frame 60 and the suppressing member 80 in a plurality of portions separated along the depth direction of the device. The adhesive 70 is an example of a fixing part. Furthermore, in this embodiment, the adhesive 70 overlaps with both the central axis K1 of the frame 60 and the central axis Y1 of the suppressing member 80 in the vertical direction of the device. In other words, in this embodiment, the adhesive 70 is disposed below the edge of the opening 82c of the suppressing member 80. That is, in this embodiment, the adhesive 70 is disposed on the side opposite to the light emission direction of the light-emitting substrate 56 relative to the edge of the opening 82c of the suppressing member 80.

[0068] like Figure 1 and Figure 2 As shown, the balance weight 54 is a cuboid extending along the depth direction of the device and fixed to the bottom 82b of the suppression member 80 on the side opposite to the frame 60. The balance weight 54, by being installed in the exposure device 50, reduces the inherent vibration frequency of the exposure device 50 compared to a case where the balance weight 54 is not installed. This causes the inherent vibration frequency of the exposure device 50 to deviate from the frequency of vibrations generated inside the image forming apparatus 10.

[0069] {Positioning component 90}

[0070] The positioning members 90 are components disposed on a frame (not shown) of the image forming apparatus 10 and positioned above the upper surface portion 68 of the frame 60. Each positioning member 90 has a contact surface 92 located at a predetermined position in the vertical direction relative to the photosensitive drum 36 and facing downwards. The positioning members 90 function to position the exposure apparatus 50 relative to the photosensitive drum 36 in the vertical direction by bringing the upper surface portion 68 of the frame 60 into contact with the contact surface 92.

[0071] {Force-Applying Mechanism 94}

[0072] The force-applying mechanism 94 is, for example, a mechanism comprising a compression spring, disposed on a frame (not shown) of the image forming apparatus 10 and positioned below the ends 86 of each suppressing member 80, applying upward force to the ends 86. The force-applying mechanism 94 has a contact surface 96 that contacts the lower surface of each end 86. The force-applying mechanism 94 applies upward force to the ends 86 by contacting them with the ends 86 of the suppressing members 80 fixed to the frame 60, and applies force to the lower surface portion 60b of the frame 60 via the ends 86, causing the upper surface portion 68 to contact the contact surface 92 of the positioning member 90. In other words, the ends 86 of the suppressing members 80 are clamped between the lower surface portion 60b of the frame 60 and the force-applying mechanism 94.

[0073] (Functions and Effects)

[0074] Next, the operation and effects of the implementation method will be explained. In addition, in this explanation, when describing a comparison method with the implementation method, when using the same components as the image forming apparatus 10 of the implementation method, the symbols and names of the components will be used directly for explanation.

[0075] The light-emitting device 50a of the embodiment has a structure in which the adhesive 70 fixes the frame 60 and the suppression member 80 at a position where it overlaps with the neutral axis K1 of the frame 60 or the neutral axis Y1 of the suppression member 80 in the vertical direction of the device. The light-emitting device 50a of the comparative embodiment is compared with the light-emitting device 150a of the comparative method shown below.

[0076] like Figure 4 As shown, the comparative light-emitting device 150a includes a suppression member 180 and an adhesive 170, replacing the suppression member 80 and adhesive 70 in the light-emitting device 50a of the embodiment. The suppression member 180 is configured such that the upper end of the side wall 182a of the main body 182 (the edge of the opening 182c) is located lower than the central axis K1 of the frame 60. The comparative suppression member 180 is fixed to the frame 60 by adhesive 170 applied and cured at the upper edge of the opening 182c of the suppression member 180 and the side surface 60a of the frame 60 in a manner extending along the depth direction of the device. That is, the comparative adhesive 170 fixes the frame 60 and the suppression member 180 at a position that is far away from the central axis K1 of the frame 60 and the central axis YH of the suppression member 80 in both the vertical and horizontal directions of the device. Apart from the above aspects, the comparative light-emitting device 150a has the same structure as the light-emitting device 50a of the embodiment.

[0077] The frame 60 and the suppression member 180 of the comparative light emitting device 150a are thermally deformed due to heat accompanying light emission of the light emitting device 150a. In particular, the frame 60 and the suppression member 180 extending in the device depth direction are thermally deformed in a manner to expand in the device depth direction. At this time, the linear expansion rate of the suppression member 180 is different from that of the frame 60, and thus the deformation amounts in the device depth direction due to thermal deformation are different from each other. Specifically, the deformation amount of the suppression member 180 whose linear expansion rate is larger than that of the frame 60 is larger than that of the frame 60. If the deformation amounts in the device depth direction of the frame 60 and the suppression member 180 due to thermal deformation are different from each other, the frame 60 and the suppression member 180 fixed by the adhesive 170 are respectively subjected to stress around the adhesive 170 due to the difference in the deformation amounts.

[0078] In the comparative example, the adhesive 170 is away from the neutral axis K1 of the frame 60 in the device up-down direction. Therefore, in the frame 60, stress (tensile force transmitted from the suppression member 180 via the adhesive 170) generated around the adhesive 170 acts on the frame 60 to cause the lower side thereof to be convexly bent around the device width direction. Also, the adhesive 170 is away from the neutral axis YH of the suppression member 180 in the device up-down direction. Therefore, in the suppression member 180, stress (restraining force transmitted from the frame 60 via the adhesive 170) generated around the adhesive 170 acts on the suppression member 180 to cause the lower side thereof to be convexly bent around the device width direction. In this way, the frame 60 extending in the device depth direction and fixed to the suppression member 180 by the adhesive 170 is thermally deformed in the device up-down direction due to heat accompanying light emission of the light emitting device 150a.

[0079] On the other hand, the light emitting device 50a of the embodiment has a structure in which the adhesive 70 fixes the frame 60 and the suppression member 80 at a position where the neutral axis K1 of the frame 60 in the device up-down direction overlaps in the device up-down direction. Therefore, the frame 60 of the embodiment is less likely to be bent due to stress generated around the adhesive 70 than the frame 60 of the comparative example. Also, the light emitting device 50a of the embodiment has a structure in which the adhesive 70 fixes the frame 60 and the suppression member 80 at a position where the neutral axis Y1 of the suppression member 80 in the device up-down direction overlaps in the device up-down direction. Therefore, the suppression member 80 of the embodiment is less likely to be bent due to stress generated around the adhesive 70 than the suppression member 180 of the comparative example. Thus, the light emitting device 50a of the embodiment is less likely to be deformed in the device up-down direction of the frame 60 due to heat than the structure in which the adhesive fixing the frame and the suppression member is away from the neutral axis of the frame or the suppression member in the device up-down direction.

[0080] Further, the light emitting device 50a of the embodiment has a structure in which the adhesive 70 overlaps the neutral axis K1 of the frame 60 in the device up-down direction. Therefore, the light emitting device 50a of the embodiment suppresses the deformation of the frame 60 in the device up-down direction caused by heat, as compared with a structure in which the adhesive fixing the frame and the suppression member overlaps only the neutral axis Y1 of the suppression member 80 in the device up-down direction.

[0081] Further, the light emitting device 50a of the embodiment has a structure in which the adhesive 70 overlaps both the neutral axis K1 of the frame 60 in the device up-down direction or the neutral axis of the light emitting portion 50b and the neutral axis Y1 of the suppression member. Therefore, the light emitting device 50a of the embodiment suppresses the deformation of the frame 60 in the device up-down direction caused by heat, as compared with a structure in which the adhesive fixing the frame and the suppression member overlaps only the neutral axis of the frame in the device up-down direction.

[0082] Further, the light emitting device 50a of the embodiment has a structure in which the width of the suppression member 80 is larger than the width of the frame 60 when viewed in the device depth direction. If the width of the suppression member 80 in the device depth direction is large, the function of the suppression member 80 suppressing the deformation of the frame 60 is improved. Therefore, the light emitting device 50a of the embodiment suppresses the flexure of the frame 60, as compared with a structure in which the width of the suppression member is smaller than the width of the frame 60 when viewed in the device depth direction.

[0083] Further, the light emitting device 50a of the embodiment has a structure in which the adhesive 70 is disposed on the lower side with respect to the edge portion of the opening portion 82c of the suppression member 80. That is, the light emitting device 50a of the embodiment has a structure in which the separation distance of the suppression member 80 with respect to the device up-down direction of the neutral axis Y1 is small, as compared with a structure in which the adhesive is disposed only on the upper side with respect to the edge portion of the opening portion 82c of the suppression member 80. Therefore, the light emitting device 50a of the embodiment suppresses the deformation of the frame 60 in the device up-down direction caused by heat, as compared with a structure in which the adhesive is disposed only on the edge portion of the opening portion 82c of the suppression member 80.

[0084] Further, the exposure device 50 provided with the light emitting device 50a of the embodiment suppresses exposure defects, as compared with a structure in which the adhesive fixing the frame and the suppression member is away from the neutral axis of the frame or the suppression member in the device up-down direction.

[0085] Further, the image forming device 10 provided with the exposure device 50 of the embodiment suppresses image forming defects, as compared with a structure in which the adhesive fixing the frame and the suppression member is away from the neutral axis of the frame or the suppression member in the device up-down direction.

[0086] While the specific embodiments of the present application have been described above, the present application is not limited to the above-described embodiments, and various modifications, changes, and improvements can be made within the scope of the technical idea of the present application.

[0087] For example, the light emitting device 50a of the embodiment is configured such that the adhesive 70 overlaps the neutral axis K1 of the frame 60 in the device up-down direction. However, the adhesive 70 in the embodiment can also have a configuration in which the adhesive 70 overlaps the neutral axis of the light emitting portion 50b including the frame 60, the light emitting substrate 56, and the lens array 52 in the device up-down direction instead of the neutral axis K1 of the frame 60. The neutral axis of the light emitting portion 50b in the device up-down direction defines an imaginary line of a neutral surface, which is an imaginary plane in which tensile stress and compressive stress caused by a bending moment around the device width direction imparted to the light emitting portion 50b do not occur in the light emitting portion 50b, when viewed in the device depth direction. The light emitting device having this configuration functions in the same manner as the light emitting device 50a of the embodiment. That is, the light emitting device having this configuration suppresses the deformation of the frame in the device up-down direction caused by heat, compared to a configuration in which the adhesive of the fixed frame and the suppression member overlaps the neutral axis of the frame or the light emitting portion or the neutral axis of the suppression member in the device up-down direction. In addition, in the present application, the combination of the frame 60 and the light emitting substrate 56 can also be interpreted as an example of the light emitting portion.

[0088] Also, the light emitting device 50a of the embodiment is configured such that the adhesive 70 overlaps both the neutral axis K1 of the frame 60 in the device up-down direction and the neutral axis Y1 of the suppression member 80 in the device up-down direction. However, the light emitting device according to the present application can also be a configuration in which the adhesive of the fixed frame and the suppression member overlaps only either one of the neutral axis of the frame or the light emitting portion or the neutral axis of the suppression member in the device up-down direction. As a specific example, an example of the light emitting device according to the present application, that is, a light emitting device 450a is shown below.

[0089] As Figure 5As shown, the light-emitting device 450a includes a suppressing member 480 and an adhesive 470, replacing the suppressing member 80 and adhesive 70 of the light-emitting device 50a of the embodiment. The neutral axis Y4 of the suppressing member 480 in the vertical direction is located lower than the neutral axis Y1 of the suppressing member 80 of the embodiment. The suppressing member 480 has a through hole 482d at a position where it overlaps with the neutral axis Y4 of the suppressing member 480 in the vertical direction, replacing the through hole 82d of the suppressing member 80. The adhesive 470 fixes the frame 60 and the suppressing member 480 by being injected into the through hole 482d of the suppressing member 480 and curing. That is, the adhesive 470 overlaps with the neutral axis Y4 of the suppressing member 480 in the vertical direction. The adhesive 470 is an example of a fixing part. Apart from the above aspects, the light-emitting device 450a is provided with the same structure as the light-emitting device 50a of the embodiment.

[0090] Furthermore, in the embodiment, the light-emitting device 50a is configured such that the adhesive 70 is injected into the through hole 82d formed in the suppressing member 80. However, the adhesive for the fixing frame and the suppressing member according to the present invention is not limited to being injected into the through hole formed in the suppressing member, as long as it overlaps with the neutral axis of the frame or the light-emitting part or the neutral axis of the suppressing member in the vertical direction of the device. As a specific example, an example of the light-emitting device according to the present invention, namely the light-emitting device 250a and the light-emitting device 350a, is shown below.

[0091] like Figure 6 As shown, the light-emitting device 250a includes a suppressing member 280 and an adhesive 270, replacing the suppressing member 80 and adhesive 70 of the light-emitting device 50a in the embodiment. The neutral axis Y2 of the suppressing member 280 in the vertical direction is located lower than the neutral axis Y1 of the suppressing member 80 in the embodiment. Furthermore, the upper edge of the opening 282c of the main body 282 of the suppressing member 280 is located higher than the neutral axis Y2 of the suppressing member 280 and lower than the neutral axis K1 of the frame 60. Also, no through hole 82d is formed in the suppressing member 280. The adhesive 270 is applied and cured to the upper edge of the opening 282c of the suppressing member 280 and the side surface 60a of the frame 60 in a manner that overlaps with the neutral axis K1 of the frame 60 in the vertical direction, thereby fixing the frame 60 and the suppressing member 280. The adhesive 270 is an example of a fixing part. Apart from the above aspects, the light-emitting device 250a is configured with the same structure as the light-emitting device 50a in the embodiment.

[0092] And, as Figure 7As shown, the light emitting device 350a is provided with the suppression member 380 and the adhesive 370 in place of the suppression member 280 and the adhesive 270 of the light emitting device 250a. The upper edge of the opening portion 382c of the main body portion 382 of the suppression member 380 is inclined in a manner that expands upward from the inner wall side toward the outer wall side of the suppression member. Thereby, a gap is formed between the upper edge of the opening portion 382c of the suppression member 380 and the side surface portion 60a of the frame 60. The suppression member 380 is configured so that the gap formed between the upper edge of the opening portion 382c and the side surface portion 60a of the frame 60 overlaps the neutral axis K1 of the frame 60 in the device up-down direction. The adhesive 370 fixes the frame 60 and the suppression member 380 by being applied and cured in the gap formed between the upper edge of the opening portion 382c of the suppression member 380 and the side surface portion 60a of the frame 60 in a manner that extends in the device depth direction. That is, the adhesive 370 overlaps the neutral axis K1 of the frame 60 in the device up-down direction in the device up-down direction. The adhesive 370 is an example of a fixing portion. As for the above aspects, the light emitting device 350a is configured in the same manner as the light emitting device 250a.

[0093] Also, the light emitting device 50a of the embodiment is configured so that the width of the suppression member 80 viewed from the device depth direction is larger than the frame 60. However, the suppression member according to the present application can have a width smaller than the frame viewed from the device depth direction as long as the adhesive that fixes the frame and the suppression member overlaps the neutral axis of the frame or the light emitting portion in the device up-down direction or the neutral axis of the suppression member in the device up-down direction. As a specific example, a light emitting device according to the present application, i.e., a light emitting device 550a, is shown below.

[0094] As shown in FIG. 27, the light emitting device 550a is provided with the suppression member 580 and the adhesive 570 in place of the suppression member 480 and the adhesive 470 of the light emitting device 450a. The upper edge of the opening portion 582c of the main body portion 582 of the suppression member 580 is inclined in a manner that expands upward from the inner wall side toward the outer wall side of the suppression member. Thereby, a gap is formed between the upper edge of the opening portion 582c of the suppression member 580 and the side surface portion 60a of the frame 60. The suppression member 580 is configured so that the gap formed between the upper edge of the opening portion 582c and the side surface portion 60a of the frame 60 overlaps the neutral axis K1 of the frame 60 in the device up-down direction. The adhesive 570 fixes the frame 60 and the suppression member 580 by being applied and cured in the gap formed between the upper edge of the opening portion 582c of the suppression member 580 and the side surface portion 60a of the frame 60 in a manner that extends in the device depth direction. That is, the adhesive 570 overlaps the neutral axis K1 of the frame 60 in the device up-down direction in the device up-down direction. The adhesive 570 is an example of a fixing portion. As for the above aspects, the light emitting device 550a is configured in the same manner as the light emitting device 450a. Figure 8As shown, the light emitting device 550a is provided with a frame 560, a suppression member 580, and an adhesive 570, instead of the frame 60, the suppression member 80, and the adhesive 70 of the light emitting device 50a of the embodiment. A plurality of through-holes 560c of a side surface portion 560a that penetrates the side of the lower recess 564 in the device width direction are formed in the frame 560 in the device depth direction. The neutral axis K5 of the frame 560 in the device up-down direction is located at a position higher than the through-holes 560c. The suppression member 580 has a size smaller in width as viewed in the device depth direction than the frame 560 and is capable of being fitted in the lower recess 564. The suppression member 580 is arranged so that the neutral axis Y5 in the device up-down direction overlaps the through-holes 560c of the frame 560, and contacts the side surface portion 560a of the lower recess 64 side of the frame 560 in a sandwiched manner. That is, the neutral axis Y5 of the suppression member 580 is located at a position lower than the neutral axis K5 of the frame 560. Also, the suppression member 580 does not have portions corresponding to the bent portion 84 and the end portion 86 of the suppression member 80 in the embodiment. The adhesive 570 fixes the frame 560 and the suppression member 580 by being injected into the through-holes 560c of the frame 560 and being cured. That is, the adhesive 570 overlaps the neutral axis Y5 of the suppression member 580 in the device up-down direction. The adhesive 570 is an example of a fixing portion. As for the above aspects, the light emitting device 550a is provided with the same structure as the light emitting device 50a.

[0095] Also, the light emitting device 50a of the embodiment is provided with a structure in which the suppression member 80 has a U-shaped cross section that opens upward as viewed in the device depth direction. However, the suppression member according to the present invention is not limited to a structure having a U-shaped cross section, as long as the adhesive that fixes the frame and the suppression member overlaps the neutral axis of the frame or the light emitting portion in the device up-down direction or the neutral axis of the suppression member in the device up-down direction. For example, the suppression member 580 in the above-described light emitting device 550a can have a hollow closed cross section formed of a bent sheet or a solid cross section, as long as the neutral axis of the suppression member 580 overlaps the through-holes 560c of the frame 560.

[0096] Also, the light emitting device 50a of the embodiment is provided with a structure in which the adhesive 70 is arranged below the opening portion 82c of the suppression member 80. However, the adhesive that fixes the frame and the suppression member according to the present invention can be arranged at a position higher than the upper edge of the opening portion of the suppression member having a U-shaped cross section that opens upward as viewed in the device depth direction, as in the above-described light emitting device 250a. Also, the adhesive that fixes the frame and the suppression member according to the present invention can be arranged so as to overlap the upper edge of the opening portion of the suppression member having a U-shaped cross section that opens upward as viewed in the device depth direction in the device up-down direction, as in the above-described light emitting device 350a.

[0097] Further, the light emitting device 50a of the embodiment is configured to have a structure in which the suppression member 80 has the bent portion 84 and the end portion 86. However, like the suppression member 580 of the light emitting device 550a described above, the suppression member according to the present application can also be configured not to have a portion corresponding to the bent portion 84 and the end portion 86 of the suppression member 80 in the embodiment. That is, the frame according to the present application can also be configured not to receive the force based on the pressing mechanism 94 directly via the suppression member 80.

[0098] Further, the light emitting device 50a of the embodiment is configured to have a structure in which the suppression member 80 covers the lower side recessed portion 64 of the frame 60 from below. However, the suppression member according to the present application can also be a member shorter than the lower side recessed portion 64 of the frame 60 in the device depth direction.

[0099] Further, the light emitting device 50a of the embodiment is configured to have a structure in which the suppression member 80 has the bent portion 84 and the end portion 86. However, like the suppression member 580 of the light emitting device 550a described above, the suppression member according to the present application can also be configured not to have a portion corresponding to the bent portion 84 and the end portion 86 of the suppression member 80 in the embodiment. That is, the frame according to the present application can also be configured not to receive the force based on the pressing mechanism 94 directly via the suppression member 80.

[0100] Further, the light emitting device 50a of the embodiment is configured to have a structure in which the suppression member 80 has the bent portion 84 and the end portion 86. However, like the suppression member 580 of the light emitting device 550a described above, the suppression member according to the present application can also be configured not to have a portion corresponding to the bent portion 84 and the end portion 86 of the suppression member 80 in the embodiment. That is, the frame according to the present application can also be configured not to receive the force based on the pressing mechanism 94 directly via the suppression member 80.

[0101] Further, the light emitting device 50a of the embodiment is configured to have a structure in which the suppression member 80 has the bent portion 84 and the end portion 86. However, like the suppression member 580 of the light emitting device 550a described above, the suppression member according to the present application can also be configured not to have a portion corresponding to the bent portion 84 and the end portion 86 of the suppression member 80 in the embodiment. That is, the frame according to the present application can also be configured not to receive the force based on the pressing mechanism 94 directly via the suppression member 80.

[0102] The above-described embodiments of the present application are provided for the purpose of illustration and explanation. In addition, the embodiments of the present application do not comprehensively and exhaustively include the present application, and do not limit the present application to the disclosed modes. It is obvious to those skilled in the art to which the present application pertains that various modifications and changes are self-evident. The present embodiments are selected and described in order to most easily explain the principles of the present application and its application. Thus, other skilled persons in the art can understand the present application through various modified examples assumed to be optimized for specific uses of various embodiments. The scope of the present application is defined by the above claims and equivalents thereof.

Claims

1. A light emitting device comprising: a light emitting portion in which a light emitting element that emits light in a light emitting direction intersecting a horizontal direction is held in a frame made of resin that extends in the horizontal direction; a suppression member that extends in the horizontal direction and suppresses deformation of the frame caused by heat, and has a linear expansion rate different from that of the frame; and a fixing portion that fixes the frame and the suppression member at a plurality of positions separated in the horizontal direction or in a manner extending in the horizontal direction at a position overlapping a neutral axis of the frame in the light emitting direction or a neutral axis of the suppression member in the light emitting direction.

2. The light emitting device according to claim 1, wherein the fixing portion overlaps both the neutral axis of the frame and the neutral axis of the suppression member in the light emitting direction.

3. The light emitting device according to claim 1 or 2, wherein a width of the suppression member is larger than a width of the frame as viewed in the horizontal direction.

4. The light emitting device according to claim 3, wherein the suppression member has an opening portion that is open to the light emitting direction, at least a portion of the frame is disposed inside the suppression member, and the fixing portion is disposed on a side opposite to the light emitting direction with respect to a rim portion of the opening portion.

5. An exposure device comprising: the light emitting device according to any one of claims 1 to 4; and an optical member fixed to the frame to constitute the light emitting portion, and exposing light emitted from the light emitting device to an exposure object.

6. An image forming apparatus comprising: an image holding body; the exposure device according to claim 5, which forms an electrostatic latent image by imaging light on the charged image holding body; and a developing device which develops the electrostatic latent image of the image holding body to form an image. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Images