Patent Publication Number: US-10775736-B1

Title: Exposure apparatus and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2019-032550 filed on Feb. 26, 2019. 
     BACKGROUND 
     Technical Field 
     The present invention relates to an exposure apparatus and an image forming apparatus. 
     Related Art 
     An exposure apparatus disclosed in Patent Document 1 includes a plate-shaped main body extending in one direction; a substrate having a plurality of light emitting elements mounted on one surface of the main body; a housing extending in one direction and having a frame shape where a through hole penetrating in a plate thickness direction of the main body is formed, the through hole in which the substrate is fixed; and a U-shaped member having a U shape opened to a side of the other surface of the main body in a cross section intersecting with the one direction, the U-shaped member fitting into the through hole. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: JP-A-2018-1570 
       
    
     SUMMARY 
     When an image forming apparatus operates, a main body of the apparatus vibrates and the housing of the exposure apparatus provided in the image forming apparatus may also vibrate. 
     In the related art, in order to reduce vibration of the housing, a structure section having a weight is attached to the housing. The housing is a long member, and both end portions in a longitudinal direction of the housing are supported by a support section provided in the exposure apparatus. The longitudinal direction intersects with an exposure direction of the exposure apparatus. The structure section is attached to an intermediate portion of the housing in the longitudinal direction, and is supported only by the housing. 
     Since the structure section is supported only by the housing, when an exposure direction of the exposure apparatus with respect to an image holder is parallel to the gravity direction, the housing may bend in a gravity direction that is parallel to the exposure direction, due to gravity acting on the structure section. 
     Aspects of non-limiting embodiments of the present disclosure relate to reduce bending of the housing in the gravity direction in a configuration including a member that reduces vibration of the housing, as compared with a case where the structure section is supported only by the housing in the gravity direction. 
     Aspects of certain non-limiting embodiments of the present disclosure address the above disadvantages and/or other disadvantages not described above. However, aspects of the non-limiting embodiments are not required to address the disadvantages described above, and aspects of the non-limiting embodiments of the present disclosure may not address any of the disadvantages described above. 
     According to an aspect of the present disclosure, there is provided an exposure apparatus including: 
     a substrate that extends in a longitudinal direction intersecting with a gravity direction and has a plurality of light emitting elements emitting light toward a gravity direction; 
     a housing that extends in the longitudinal direction, to which the substrate is attached; 
     a support section that supports both end side portions of the housing in the longitudinal direction against gravity; and 
     a structure section having a weight that is attached to an intermediate portion of the housing in the longitudinal direction and supported by the support section in the gravity direction. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Exemplary embodiment(s) of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a perspective view showing an exposure apparatus according to an exemplary embodiment of the invention; 
         FIG. 2  is an exploded perspective view showing the exposure apparatus according to an exemplary embodiment of the invention; 
         FIG. 3  is a perspective view showing a vibration suppressor provided in the exposure apparatus according to an exemplary embodiment of the invention; 
         FIG. 4  is an enlarged side view showing the exposure apparatus according to an exemplary embodiment of the invention; 
         FIG. 5  is a side view showing the exposure apparatus according to an exemplary embodiment of the invention; 
         FIG. 6A  and  FIG. 6B  are sectional views showing the exposure apparatus according to an exemplary embodiment of the invention; 
         FIG. 7A ,  FIG. 7B , and  FIG. 7C  are operation diagrams showing movement of a weight provided in the exposure apparatus according to an exemplary embodiment of the invention; 
         FIG. 8  is a schematic configuration diagram showing an image forming apparatus according to an exemplary embodiment of the invention; and 
         FIG. 9  is a side view showing an exposure apparatus according to a comparative embodiment of the exemplary embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     An exposure apparatus and an image forming apparatus according to an exemplary embodiment of the invention will be described with reference to  FIGS. 1 to 9 . An arrow H shown in the drawings indicates an apparatus vertical direction that is parallel to the gravity direction, an arrow W indicates an apparatus width direction that is one horizontal direction, and an arrow D indicates an apparatus length direction that is another horizontal direction. 
     (Overall Configuration) 
     As shown in  FIG. 8 , an image forming apparatus  10  according to the exemplary embodiment includes a container  14  that faces upward from a lower side in the vertical direction (a direction of the arrow H) and accommodates a sheet member P as a recording medium, a conveyer  16  that conveys the sheet member P accommodated in the container  14 , and an image forming section  20  that forms an image on the sheet member P conveyed by the conveyer  16  from the container  14  in this order. 
     [Container] 
     The container  14  includes a drawer  26  that can be drawn out from an apparatus main body  10   a  of the image forming apparatus  10  to a front side in the apparatus length direction, and the sheet member P is loaded on the drawer  26 . The drawer  26  includes a delivery roller  30  that delivers the sheet member P stacked on the drawer  26  to a conveyance path  28  constituting the conveyer  16 . 
     [Conveyer] 
     The conveyer  16  includes a plurality of conveyer rollers  32  that convey the sheet member P along the conveyance path  28  in which the sheet member P delivered from the container  14  is conveyed. 
     [Image Forming Section] 
     The image forming section  20  includes four image forming units  18 Y,  18 M,  18 C, and  18 K of yellow (Y), magenta (M), cyan (C), and black (K). In the following description, Y, M, C, and K may be omitted when Y, M, C, and K need not to be distinguished and described. 
     Each of the image forming units  18  of each color can be attached to and detached from the apparatus main body  10   a . Each of the image forming units  18  of each color includes an image holder  36 , a charging member  38  that charges a surface of the image holder  36 , and an exposure apparatus  42  that irradiates the image holder  36  with exposure light. Each of the image forming units  18  of each color includes a development device  40  that develops an electrostatic latent image on the charged image holder  36  and visualizes as a toner image, the electrostatic latent image being formed by the exposure apparatus  42  irradiating the charged image holder  36  with the exposure light. A configuration of the exposure apparatus  42  will be described in detail later. 
     The image forming section  20  includes an endless transfer belt  22  that circulates in a direction of an arrow A in  FIG. 8 , and primary transfer rollers  44  that transfers the toner image formed by the image forming units  18  of each color to the transfer belt  22 . The image forming section  20  includes a secondary transfer roller  46  that transfers the toner image transferred to the transfer belt  22  to the sheet member P carried on the conveyance path  28 , and a fixing unit  50  that heats and pressurizes the sheet member P to which the toner image is transferred and fixes the toner image to the sheet member P. 
     (Operation of Image Forming Apparatus) 
     In the image forming apparatus  10 , an image is formed as follows. 
     First, the charging member  38  of each color to which a voltage is applied uniformly negatively charges a surface of the image holder  36  of each color at a predetermined potential. Subsequently, based on image data received from the outside, the exposure apparatus  42  irradiates the surface of the charged image holder  36  of each color with exposure light to form the electrostatic latent image. 
     Accordingly, the electrostatic latent image corresponding to the data is formed on the surface of the image holder  36  of each color. The development device  40  of each color develops the electrostatic latent image and visualizes the image as a toner image. The toner image formed on the surface of the image holder  36  of each color is transferred to the transfer belt  22  by the primary transfer roller  44 . 
     Then, the sheet member P delivered from the drawer  26  to the conveyance path  28  by the delivery roller  30  is delivered to a transfer position T where the transfer belt  22  contacts with a secondary transfer roller  46 . At the transfer position T where the sheet member P is conveyed between the transfer belt  22  and the secondary transfer roller  46 , the toner image on the surface of the transfer belt  22  is transferred to the surface of the sheet member P. 
     The toner image transferred to the surface of the sheet member P is fixed on the sheet member P by the fixing unit  50 . The sheet member P on which the toner image is fixed is discharged to the outside of the apparatus main body  10   a.    
     (Main Part Configuration) 
     Next, the exposure apparatus  42  and the like will be described. 
     The exposure apparatus  42  is an LED printhead, and is disposed below the image holder  36  as shown in  FIG. 5 . 
     As shown in  FIG. 1  and  FIG. 2 , the exposure apparatus  42  includes a substrate  60  extending in the apparatus length direction (a longitudinal direction), a surface of which faces the vertical direction, and a lens array  62  disposed above the substrate  60  and extending in the apparatus length direction. The exposure apparatus  42  includes a housing  66  to which the substrate  60  and the lens array  62  are attached, and a vibration suppressor  68  attached to the housing  66 . The exposure apparatus  42  includes a support member  70  that supports the housing  66  and the vibration suppressor  68 , and a compression coil spring  78  (hereinafter, “spring  78 ”). The vibration suppressor  68  is an example of the structure section. 
     [Substrate] 
     As shown in  FIG. 2 , the substrate  60  includes a plate-shaped main body  64  and a plurality of light emitting elements  72  mounted on an upper surface  64   a  of the main body  64 . The main body  64  is a print wiring substrate, surfaces of which face the vertical directions, and has a rectangular shape extending in the apparatus length direction when viewed from above. The light emitting elements  72  are light emitting diodes (LEDs), and are disposed in a zigzag form in which two arrays of the light emitting elements  72  alternate in the apparatus length direction (D) on the upper surface  64   a  of the main body  64 , the arrays extending in the apparatus length direction. The plurality of light emitting elements  72  emit light in the vertical direction (gravity direction). 
     [Lens Array] 
     As shown in  FIG. 2 , the lens array  62  has a rectangular parallelepiped shape extending in the apparatus length direction. The cross-sectional shape of the lens array  62  orthogonal to the apparatus length direction is a rectangular shape extending in the apparatus vertical direction (see  FIG. 6A ). In the lens array  62 , a plurality of rod lenses  82  are disposed in the zigzag form in which two arrays of the rod lenses  82  alternate in the apparatus length direction, the arrays extending in the apparatus length direction. Each of the rod lenses  82  extends in the vertical direction and transmits light emitted from each of the light emitting elements  72  to form an image on the image holder  36  (see  FIG. 5 ). 
     In this way, an exposure direction of the exposure apparatus  42  to the image holder  36  is parallel to the vertical direction (gravity direction). 
     [Housing] 
     The housing  66  is formed of a liquid crystal polymer, which is a resin material, and extends in the apparatus length direction as shown in  FIG. 2 . A through hole  84  that penetrates the housing  66  in the apparatus vertical direction and extends in the apparatus length direction is formed. As described above, the housing  66  has a frame shape. 
       FIG. 6A  is a cross-section taken along the line VIA-VIA in  FIG. 5 , and  FIG. 6B  is a cross-section taken along the line VIB-VIB in  FIG. 5 . As shown in  FIGS. 6A and 6B , a shape of the housing  66  in a cross section orthogonal to the apparatus length direction is symmetrical with respect to a line J extending in the apparatus vertical direction through a center of gravity G in the cross section of the housing  66 . In a portion where the through hole  84  is formed in the housing  66 , as shown in  FIG. 6A , a pair of wall portions  66   a  extending in the apparatus vertical direction are formed with the through hole  84  sandwiched therebetween. 
     The lens array  62  is fixed to an upper end portion of the through hole  84  formed in the housing  66  by an adhesive (UV curable adhesive) (not shown). A gap between the housing  66  and the lens array  62  is filled with a sealant  88  over an entire periphery of the lens array  62 . This prevents dust or the like from penetrating into an interior of the housing  66  through a gap between the housing  66  and the lens array  62 . 
     In the housing  66 , a step portion  84   a  is formed over an entire circumference of the through hole  84  so as to widen an opening on a lower end portion of the through hole  84 . An end portion of the substrate  60  is fixed on the step portion  84   a  using an adhesive (not shown) so that the light emitting elements  72  faces the lens array  62  in the vertical direction. This prevents dust or the like from penetrating into the interior of the housing  66  through a gap between the step portion  84   a  and the substrate  60 . 
     As shown in  FIGS. 2 and 6B , a planar upper surface portion  66   b  facing upward and a planar lower surface portion  66   c  facing downward are formed at both end portions in the apparatus length direction in which the through hole  84  is not formed in the housing  66 . The apparatus main body  10   a  includes a pair of reference frames  130  that contact the upper surface portion  66   b  in the vertical direction. 
     [Support Member  70 , Spring  781   
     The support member  70  is formed by bending a trimmed sheet metal, and extends in the apparatus length direction (D) as shown in  FIG. 2 . As shown in  FIG. 6A , the support member  70  has a U-shape opening upward in the cross section orthogonal to the apparatus length direction (D). The support member  70  is an example of a support section. 
     As shown in  FIG. 2  and  FIG. 6A , the support member  70  includes a pair of side plates  74  whose surface faces the apparatus width direction (W), and a bottom plate  76  whose surface faces the vertical direction (H). The bottom plate  76  has a rectangular shape extending in the apparatus length direction (H) when viewed from above, and a rectangular through hole  76   a  extending in the apparatus width direction (W) is formed in an intermediate portion of the bottom plate  76  in the apparatus length direction (H). The support member  70  is supported from below by a frame member (not shown) provided on the apparatus main body  10   a.    
     As shown in  FIG. 2  and  FIG. 6B , four springs  78  are disposed in a compressed state between the lower surface portion  66   c  of the housing  66  and an upper surface  76   b  of the bottom plate  76  of the support member  70 . Specifically, two springs  78  are disposed at both end portions of the housing  66  respectively, and are arranged in the apparatus length direction (D). 
     In this configuration, the support member  70  supports portions on both end sides of the housing  66  in the vertical direction (gravity direction) via the springs  78 . As shown in  FIG. 5 , the upper surface portions  66   b  of the housing  66  are pressed against the reference frames  130  by urging forces of the springs  78  so that a position of the housing  66  in the vertical direction is determined. Accordingly, a relative position between the support member  70  and the housing  66  in the vertical direction varies. 
     [Vibration Suppressor  68 ] 
     The vibration suppressor  68  is a dynamic vibration absorber or a dynamic damper. As shown in  FIG. 1  and  FIG. 2 , the vibration suppressor  68  is attached to an intermediate portion of the housing  66  in the apparatus length direction (D) and supported by the support member  70  in the vertical direction (gravity direction). Here, the “intermediate portion of the housing  66  in the apparatus length direction” is a portion defined in a range of 30 to 70 from one end of the housing  66  when a length of the housing  66  in the apparatus length direction is 100. 
     That is, in the exemplary embodiment, when the length of the housing  66  in the apparatus length direction is 100, the vibration suppressor  68  is attached to a portion defined in a range of 30 to 70 from one end of the housing  66 . Here, in view of reducing vibration occurred on the housing  66 , it is better if the vibration suppressor  68  is attached to a mid-portion defined in a range of 40 to 60 from one end of the housing  66 , and it is particularly good if the vibration suppressor  68  is attached to a central portion defined in a range of 45 to 55 from one end of the housing  66 . 
     As shown in  FIG. 1 , the vibration suppressor  68  extends in the apparatus length direction, and is disposed below the housing  66  and above the bottom plate  76  of the support member  70 . As shown in  FIG. 3 , the vibration suppressor  68  includes a weight  102  extending in the apparatus length direction, and a pair of elastic portions  104  sandwiching the weight  102  in the apparatus length direction (D) and capable of elastically deforming in the apparatus width direction (W). The vibration suppressor  68  includes an attachment section  108  to which the weight  102  is attached via the elastic portion  104  and a holding portion  120  having a pair of sheet springs  124  that sandwich the housing  66  therebetween in the apparatus width direction (W). 
     —Weight  102 , Elastic Portion  104 — 
     The weight  102  is formed of a metal material and has a cylindrical shape extending in the apparatus length direction (D), as shown in  FIG. 3 . The pair of elastic portions  104  are formed of a rubber material and disposed so as to sandwich the weight  102  therebetween in the apparatus length direction (D). The elastic portions  104  have a cylindrical shape extending in the apparatus length direction (D), and the weight  102  is fixed to one ends of the elastic portions  104  by a fixing material (not shown). 
     —Attachment Section  108 — 
     The attachment section  108  is formed by bending a trimmed sheet metal, and extends in the apparatus length direction as shown in  FIG. 3 . The attachment section  108  includes: a pair of clamping plates  110  disposed so that the plate surface faces the apparatus length direction (D) and the weight  102  and the pair of elastic portions  104  are sandwiched therebetween in the apparatus length direction; and a coupling plate  112  that couples the pair of clamping plates  110 , a surface of which facing the vertical direction. The attachment section  108  includes an L-shaped plate  114  connected to one clamping plate  110  and a flat plate  118  connected to the other clamping plate  110 . 
     The pair of clamping plates  110  are separated in the apparatus length direction, and as described above, sandwich the weight  102  and the pair of elastic portions  104  in the apparatus length direction (D). The pair of clamping plates  110  has a rectangular shape having a pair of edges extending in the vertical direction (H) and a pair of edges extending in the apparatus width direction (W) when viewed from the apparatus length direction (D). A lower end edge  110   a  of the clamping plate  110  is configured to contact with the upper surface  76   b  of the bottom plate  76  of the support member  70  (see  FIG. 1 ). 
     When viewed from the apparatus length direction (D), the weight  102  and the pair of elastic portions  104  are disposed in a region of the clamping plate  110 . The surfaces  110   b  of the clamping plates  110  fix the other ends of the elastic portions  104  with a fixing material (not shown) respectively, the surfaces  110   b  facing to the other ends of the elastic portions  104 . 
     The coupling plate  112  is disposed above the weight  102  and the pair of elastic portions  104 , and has a rectangular shape extending in the apparatus length direction (D) when viewed from the vertical direction (H). Both end edges  112   a  of the coupling plate  112  in the apparatus length direction are connected with upper end edges  110   c  of the pair of clamping plates  110  respectively. 
     The flat plate  118  is connected to the lower end edge  110   a  of the clamping plate  110  on a back side (right side in  FIG. 4 ) in the apparatus length direction (D), and the plate surface faces the vertical direction (H). The flat plate  118  extends from the lower end edge  110   a  of the clamping plate  110  on the back side toward the back side in the apparatus length direction (D). A lower surface  118   a  of the flat plate  118  is configured to contact with the upper surface  76   b  of the bottom plate  76  of the support member  70 , as shown in  FIG. 4 . 
     As shown in  FIG. 3 , an L-shaped plate  114  is connected to the lower end edge  110   a  of the clamping plate  110  on a front side (left side in  FIG. 4 ) in the apparatus length direction (D). Specifically, the L-shaped plate  114  extends downward from a center portion of the lower end edge  110   a  of the clamping plate  110  on the front side in the apparatus length direction (D), and has a base portion  114   a  whose surface faces the apparatus length direction (D) and a tip portion  114   b  extending from the lower end edge of the base portion  114   a  to the front side in the apparatus length direction (D), of which a surface faces the vertical direction (H). 
     A length of the L-shaped plate  114  in the apparatus width direction (W) is shorter than a length in the apparatus width direction (W) of the through hole  76   a  (see  FIG. 1 ) of the bottom plate  76  of the support member  70 . As shown in  FIG. 1  and  FIG. 4 , a part of the L-shaped plate  114  protrudes to a lower region of the bottom plate  76  from the through hole  76   a  of the bottom plate  76 . A part of the tip portion  114   b  of the L-shaped plate  114  faces a lower surface  76   c  facing the lower region of the bottom plate  76  in the vertical direction (H). 
     In this configuration, when the vibration suppressor  68  rises upward with respect to the support member  70 , the tip portion  114   b  of the L-shaped plate  114  comes into contact with the bottom plate  76 . This prevents the vibration suppressor  68  from dropping out of (moving from) the support member  70 . In this way, the L-shaped plate  114  functions as a locking unit that prevents the vibration suppressor  68  from dropping out of the support member  70 . 
     As described above, the lower surface  118   a  of the attachment section  108  faces to and contacts with the upper surface  76   b  of the bottom plate  76  of the support member  70 . A length of the L-shaped plate  114  in the apparatus width direction (W) is shorter than the length of the through hole  76   a  of the bottom plate  76  of the support member  70  in the apparatus width direction (W). Therefore, the vibration suppressor  68  is movable with respect to the support member  70  in the apparatus width direction (W) in a predetermined range. The apparatus width direction (W) is one of intersection directions intersecting with the gravity direction. 
     —Holding Portion  120 — 
     As shown in  FIG. 3 , the holding portion  120  is formed of a trimmed spring steel sheet, and is disposed on the coupling plate  112  of the attachment section  108  in an intermediate region of the coupling plate  112  in the apparatus length direction. 
     The holding portion  120  has a U shape opening upward when viewed from the apparatus length direction (D), and includes a bottom plate  122  that contacts the coupling plate  112 , and a pair of sheet springs  124  erected from both end edges of the bottom plate  122  in the apparatus width direction (W) and sandwiching the housing  66  therebetween (see  FIG. 6A ) in the apparatus width direction (W). 
     The bottom plate  122  has a rectangular shape extending in the apparatus length direction (D) when viewed from above. Surfaces of the bottom plate  122  face the vertical direction (H). A pair of edges of the bottom plate  122  in the apparatus width direction (W) extending in the apparatus length direction (D) overlap with a pair of edges of the coupling plate  112  extending in the apparatus length direction (D) when viewed from above. The bottom plate  122  is fixed to an upper surface  112   b  of the coupling plate  112  using a fixing material (not shown). 
     The pair of sheet springs  124  are erected from both end edges in the apparatus width direction (W) of the bottom plate  122 . The sheet springs  124  are separated with each other in the apparatus width direction (W). The sheet springs  124  have rectangular shapes extending in the apparatus length direction (D) when viewed from the apparatus width direction (W). The sheet springs  124  are bent, and as shown in  FIG. 6A , ridges  124   a  are formed on the sheet springs  124  when viewed from the apparatus length direction (D). Each ridge  124   a  protrudes toward the other sheet spring  124  facing each other. 
     The protruding portion  124   a  formed on each sheet spring  124  is in contact with the wall portion  66   a  of the housing  66 , and each sheet spring  124  elastically bends, so that the pair of sheet springs  124  sandwich the intermediate portion of the housing  66  in the apparatus length direction in the apparatus width direction. In other words, a distance between the pair of protruding portions  124   a  not sandwiching the housing  66  is smaller than a thickness of the housing  66  in the apparatus width direction. In this way, the vitration suppressor  68  is attached to the intermediate portion of the housing  66 . 
     Here, the bottom plate  122  of the holding portion  120  and the housing  66  are separated in the vertical direction. A vertical position of the housing  66  is determined by a position of the reference frame  130 , and a vertical position of the vibration suppressor  68  is determined by a position of the bottom plate  76  of the support member  70 . Therefore, the vertical position of the housing  66  and the vertical position of the vibration suppressor  68  vary independently. Therefore, by adjusting the position of the housing  66  sandwiched by the pair of sheet springs  124 , relative variation between the housing  66  and the vibration suppressor  68  is absorbed. In this way, the vibration suppressor  68  is attached to the housing  66  so that the position of the vibration suppressor  68  in the gravity direction with respect to the housing  66  can be adjusted. Since a space is formed between the bottom plate  122  and the housing  66 , the support member  70  functions as an absorber that absorbs the relative variation between the housing  66  and the vibration suppressor  68 . 
     The vibration suppressor  68  is attached to the housing  66  by the pair of sheet springs  124  sandwiching the housing  66  in the apparatus width direction (W). Accordingly, the vibration suppressor  68  moves in the apparatus width direction (W) with respect to the support member  70  so that bending amounts of the sheet springs  124  with respect to the housing  66  are the same. The center of gravity of the vibration suppressor  68  and the center of gravity of the housing  66  are in the same position in the apparatus width direction (W). That is, the pair of sheet springs  124  function as position adjusting sections that adjust the position of the vibration suppressor  68  in the apparatus width direction (W) to the position of the housing  66  in the apparatus width direction (W). 
       FIGS. 7A, 7B, and 7C  are plan views of the vibration suppressor  68 . In this configuration, when vibration in the apparatus width direction (W) is transmitted to the housing  66  along with image forming operation of the image forming apparatus  10 , as shown in  FIGS. 7A, 7B, and 7C , the weight  102  vibrates in the apparatus width direction while the elastic portion  104  of the vibration suppressor  68  is deformed. Accordingly, the vibration of the housing  66  is reduced. 
     (Operation of Main Part Configuration) 
     Next, operation of the main part configuration will be described in comparison with the exposure apparatus  542  according to a comparative embodiment. First, concerning a configuration of the exposure apparatus  542 , portions different from the exposure apparatus  42  will be mainly described. 
     [Configuration of Exposure Apparatus  542 ] 
     As shown in  FIG. 9 , the exposure apparatus  542  includes the substrate  60 , the lens array  62 , the housing  66 , the support member  70 , and the spring  78 . The exposure apparatus  542  includes a vibration suppressor  568  attached to the housing  66 . 
     The vibration suppressor  568  is a mass damper and is attached to an intermediate portion of the housing  66  in the apparatus length direction (D), and is separated from the bottom plate  76  of the support member  70  in the vertical direction. (H) In other words, the vibration suppressor  568  is supported only by the housing  66  in the gravity direction. 
     The vibration suppressor  568  includes a cylindrical weight  602  extending in the apparatus length direction, and an attachment section  608  to which the weight  602  is attached. The attachment section  608  includes clamping portions  608   a  that sandwich the weight  602  in the apparatus length direction, and clamping portions  608   b  that sandwich the housing  66  in the apparatus width direction (W). In this way, the vibration suppressor  568  is attached to the housing  66 . 
     In this configuration, a natural vibration frequency of the housing  66  to which the vibration suppressor  568  is attached deviates from a vibration frequency transmitted to the housing  66  along with the image forming operation of the image forming apparatus  10 . Accordingly, the vibration of the housing  66  is reduced. 
     [Operation of Exposure Apparatuses  42  and  542 ] 
     Next, operation of the exposure apparatuses  42  and  542  will be described. 
     When the image forming operation of the image forming apparatus  10  shown in  FIG. 8  is started, and a surface of the image holder  36  is charged, the exposure apparatuses  42  and  542  cause the light emitting element  72  to emit light to irradiate the surface of the image holder  36  with exposure light (see  FIG. 6A ). 
     Here, vibration of a driving member in the apparatus main body  10   a  caused by the image forming operation is transmitted to the housing  66  of the exposure apparatus  42 . As described above, both end portions of the housing  66  in the apparatus length direction (D) are supported by the springs  78  and the reference frames  130 . As shown in  FIG. 6A , the lens array  62  has a rectangular shape extending in the apparatus vertical direction (H) in a cross section orthogonal to the apparatus length direction (D), and the housing  66  has the pair of wall portions  66   a  extending in the apparatus vertical direction (H). Therefore, bending rigidity of the housing  66  in the vertical direction (D) is higher than bending rigidity of the housing  66  in the apparatus width direction (W), to which the lens array  62  is attached. Accordingly, the housing  66  is easy to vibrate in the apparatus width direction (W), to which the lens array  62  is attached (see an arrow F in  FIG. 1 ). 
     Therefore, when resonance occurs between the natural vibration of the housing  66  and the vibration transmitted to the housing  66  along with the image forming operation, the housing  66  vibrates significantly. 
     In the exposure apparatus  542 , a vibration suppressor  568  is attached to the housing  66 . Therefore, as described above, the natural vibration frequency of the housing  66  with the vibration suppressor  568  attached deviates from the vibration frequency transmitted to the housing  66  along with the image forming operation. Accordingly, vibration of the housing  66  of the exposure apparatus  542  is reduced. 
     However, in the exposure apparatus  542 , the vibration suppressor  568  is separated from the bottom plate  76  of the support member  70  in the vertical direction. Therefore, the housing  66  of the exposure apparatus  542  may bend in the gravity direction due to gravity acting on the vibration suppressor  568 . In other words, the housing  66  of the exposure apparatus  542  may bend in the exposure direction (gravity direction). Specifically, the housing  66  bends in the vertical direction (exposure direction) such that the intermediate portion of the housing  66  shifts downward with respect to the both end portions in the apparatus length direction (D). In this way, the bending of the housing  66  in the exposure direction increases an error of imaging in which light emitted from the light emitting element  72  and transmitted through the rod lens  82  is imaged on the image holder  36 . Therefore, a quality of an electrostatic latent image formed by exposure of the exposure apparatus  542  on the image holder  36  decreases. 
     In contrast, in the exposure apparatus  42 , the vibration suppressor  68  is attached to the housing  66 . Therefore, as described above, when vibration in the apparatus width direction is transmitted to the housing  66  along with image forming operation of the image forming apparatus  10 , as shown in  FIGS. 7A, 7B, and 7C , the weight  102  vibrates in the apparatus width direction while the elastic portion  104  of the vibration suppressor  68  is deformed. Accordingly, vibration of the housing  66  of the exposure apparatus  42  is reduced. 
     Here, the vibration suppressor  68  is supported by the support member  70  in the vertical direction (gravity direction). Therefore, bending of the housing  66  in the exposure direction (gravity direction) due to the gravity acting on the vibration suppressor  68  is reduced. 
     CONCLUSION 
     As described above, in the configuration including a member that reduces vibration of the housing  66 , bending of the housing  66  in the gravity direction (exposure direction) in the exposure apparatus  42  is reduced compared with the exposure apparatus  542 . 
     In the exposure apparatus  42 , the vibration suppressor  68  is attached to the housing  66  since the pair of sheet springs  124  sandwich the housing  66 . In other words, by adjusting the position of the housing  66  sandwiched by the pair of sheet springs  124 , relative variation between the housing  66  and the vibration suppressor  68  is absorbed. Therefore, relative positional variation between the vibration suppressor  68  and the housing  66  in the gravity direction is absorbed such that a relative positional relationship between the vibration suppressor and the housing does not change compared with the case where the vibration suppressor is attached to the housing. 
     In the exposure apparatus  42 , the pair of sheet springs  124  formed on the holding portion  120  sandwich the housing  66  in the apparatus width direction, so that the vibration suppressor  68  is attached to the housing  66 . The attachment section  108  is movable with respect to the support member  70  in the apparatus width direction (W) in a predetermined range. Therefore, deviation between the center of gravity of the vibration suppressor  68  and the center of gravity of the housing  66  in the apparatus width direction is prevented compared with the case where the vibration suppressor is attached to the housing such that a relative positional relationship between the vibration suppressor and the housing does not change. 
     In the exposure apparatus  42 , the weight  102  extends in the apparatus length direction, and the attachment section  108  extends in the apparatus length direction and sandwiches the pair of elastic portions  104  and the weight  102  in the apparatus length direction. The lower end edges  110   a  of the pair of clamping plates  110  formed on both end sides of the attachment section  108  contact the upper surface  76   b  formed on the bottom plate  76  of the support member  70  from above in the gravity direction, so that the vibration suppressor  68  is supported by the support member  70 . Accordingly, posture of the vibration suppressor  68  is stabilized compared with a case where the attachment section is in contact with the support member in the gravity direction only at an intermediate portion of the attachment section in the device length direction. 
     In the exposure apparatus  42 , a lower surface  118   a  formed on a back side portion of the attachment section  108  in the apparatus length direction and an upper surface  76   b  formed on the bottom plate  76  of the support member  70  are in face contact. Therefore, compared with a case where both end portions of the attachment section in the apparatus length direction are in point contact with the upper surface of the bottom plate, the posture of the vibration suppressor  68  is stabilized. 
     The image forming apparatus  10  includes the exposure apparatus  42 . Therefore, as compared with the case where the exposure apparatus  542  is included, quality degradation of the electrostatic latent image formed on the image holder  36  is prevented, and quality degradation of an output image is prevented. 
     While the present invention has been described in detail with respect to specific exemplary embodiments, it will be apparent to those skilled in the art that various other embodiments may be used within the scope of the present invention. For example, in the above exemplary embodiment, the exposure apparatus  42  includes the vibration suppressor  68  which is a dynamic vibration absorber to reduce vibration occurring in the housing  66 , but exposure apparatus  42  may include the mass damper to reduce the vibration occurring in the housing. 
     In the above exemplary embodiment, the lower surface  118   a  of the attachment section  108  formed on the back side portion (right side in  FIG. 4 ) in the apparatus length direction (D) is configured to contact with the upper surface  76   b  of the bottom plate  76  of the support member  70 , but portions on both end sides of the attachment section  108  in the apparatus length direction (D) may have surfaces configured to contact with the upper surface  76   b  of the bottom plate  76 . In this case, compared with a case where only one end side portion in the apparatus length direction (D) is configured to contact with the upper surface  76   b  of the bottom plate  76 , the attitude of the vibration suppressor is stabilized. 
     In the above exemplary embodiments, in the vibration suppressor  68 , the pair of sheet springs  124  of the holding portion  120  sandwich the housing  66  in the apparatus width direction (W), so that the vibration suppressor  68  is attached to the housing  66 . The vibration suppressor  68  may be attached to the housing  66  using a fixing material or the like. The vibration suppressor  68  may be supported by the support member  70 . 
     In the above exemplary embodiments, the support member  70  may be formed integrally, or the support member  70  may be divided into a portion that supports the housing  66  and a portion that supports the vibration suppressor  68 . 
     In the above exemplary embodiments, the vibration suppressor  68  may be supported by the support member  70  from below, or the vibration suppressor  68  may be supported from above by a hanging string or the like. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.