Patent Publication Number: US-7917050-B2

Title: Wiring structure for an electrical device and an image forming apparatus equipped with such a wiring structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to wiring structures of electrical devices, such as image forming apparatus. 
     2. Description of the Related Art 
     In the related art, electrophotographic image forming devices, such as copiers and printers, are known. In such image forming devices, multiple motors are installed, and wires for electrical wiring are routed in a complex manner for the purpose of performing, for example, an image forming process. See Japanese Unexamined Patent Application Publication No. 2007-139889 for an example. 
     To fulfill demands for color-image forming features and size reduction in image forming devices in recent years, the multiple motors and wires are installed within a small space. In such a condition, the wires routed in the vicinity of the motors can sometimes come into contact with the peripheral edges of the motors. In that case, the wires may possibly become damaged or cut. A damaged or cut wire unfavorably prevents the image forming apparatus from performing a predetermined image forming process. 
     Accordingly, it is an object of the present invention to provide a wiring structure of an electrical device, such as an image forming apparatus, that allows for easier routing of a wire while preventing the wire from being damaged as a result of coming into contact with a motor. 
     SUMMARY OF THE INVENTION 
     In order to achieve the aforementioned object, a wiring structure of an electrical device according to the present invention includes a main body frame; a cylindrical motor disposed on the main body frame and having a cylindrical surface, an end surface, and a peripheral edge between the cylindrical surface and the end surface; a wire routed near the motor and along the main body frame; and a flexible sheet member attached along the cylindrical surface of the motor so as to cover at least a part of the peripheral edge and having a shape substantially capable of maintaining the wire in a routed state. 
     In the wiring structure of the electrical device according to an embodiment of the present invention, the sheet member covers the peripheral edge of the motor so that the wire is prevented from being damaged by the peripheral edge when routing the wire or installing the motor. On the other hand, because the flexible sheet member, which itself has low rigidity, is attached along the cylindrical surface of the motor, certain rigidity is added to the sheet member. Thus, the wire can be maintained in the routed state by using the sheet member. Consequently, the wiring structure of the electrical device according to the present invention employs the flexible sheet member having low rigidity to prevent the wire from being cut and to maintain the wire in the routed state. 
     In a preferred embodiment of the present invention, it is preferable that the sheet member integrally have an attachment segment attached along the cylindrical surface of the motor, a contact-prevention segment that extends continuously from the attachment segment and covers the at least a part of the peripheral edge of the motor so as to prevent the peripheral edge and the wire from coming into contact with each other, and a regulating segment that protrudes outward from the contact-prevention segment and has a shape capable of regulating movement of the wire so as to maintain the wire in the routed state. 
     In another preferred embodiment of the present invention, the sheet member preferably includes a main body having a shape of a strip. In that case, the main body may be constituted by the attachment segment and the contact-prevention segment, and a substantially central section of the contact-prevention segment in a longitudinal direction thereof may be provided with a protrusion that protrudes outward and acts as the regulating segment. 
     In another preferred embodiment of the present invention, the regulating segment may have the same curvature as the cylindrical surface of the motor when the sheet member is attached along the cylindrical surface of the motor. 
     In another preferred embodiment of the present invention, the motor is one of a plurality of motors arranged at a certain interval in a horizontal direction with respect to the main body frame, and the sheet member is one of a plurality of sheet members attached to the corresponding motors such that the regulating segments of the sheet members are positionally arranged in the horizontal direction. 
     In another preferred embodiment of the present invention, the motor may be configured to rotate a rotating member that supplies toner contained in a toner container to a developing unit. 
     In another preferred embodiment of the present invention, the sheet member may have a thickness of 50 μm to 125 μm. Even with the sheet member formed of such a thin film, the wire still can be prevented from being cut and can be maintained in the routed state. 
     In another preferred embodiment of the present invention, the attachment segment preferably has an adhesive surface formed with double-sided tape. 
     In another preferred embodiment of the present invention, the aforementioned wiring structure is applied to an image forming apparatus. Accordingly, in the image forming apparatus, the wire can be prevented from being cut and can be maintained in the routed state. 
     The wiring structure of the electrical device according to the present invention can allow for easier routing of a wire while preventing the wire from being damaged as a result of coming into contact with a motor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external perspective view of an image forming apparatus equipped with a wiring structure according to an embodiment of the present invention, as viewed at an angle from the front-left side; 
         FIG. 2  is a cross-sectional view showing the internal structure of the image forming apparatus shown in  FIG. 1 ; 
         FIG. 3  is an external view of a housing of a device body of the image forming apparatus, as viewed from the right side of the image forming apparatus; 
         FIG. 4  is an enlarged view of a portion of  FIG. 3 ; 
         FIG. 5  is an enlarged view of a portion of  FIG. 4 , illustrating the wiring structure in the vicinity of motors in this embodiment; 
         FIG. 6  illustrates one of the motors and a corresponding sheet member attached to the motor; and 
         FIG. 7  is a plan view showing the sheet member before it is attached to the motor. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of the present invention will be described below with reference to the drawings. 
       FIG. 1  is an external perspective view of an image forming apparatus equipped with a wiring structure according to an embodiment of the present invention, as viewed at an angle from the front-left side.  FIG. 2  is a cross-sectional view showing the internal structure of the image forming apparatus. This embodiment is directed to a color printer  1  as an example of the image forming apparatus. 
     The color printer  1  includes a printer body (i.e., a device body)  200  connected directly or via a local area network (LAN) to, for example, a personal computer (not shown), and a sheet feeder  130  provided below the printer body  200  and capable of storing sheets. The color printer  1  also has other components provided in general color printers, such as a control circuit that controls the operation of the color printer  1 . 
     As shown in  FIG. 2 , the printer body  200  includes toner containers  900 Y,  900 M,  900 C, and  900 K, an intermediate transfer unit  92 , an image forming unit  93 , an exposure unit  94 , a fixing unit  97 , an ejecting unit  96 , a housing (i.e., a main body frame)  90  of the printer body  200 , a top cover  911 , and a front cover  912 . 
     The image forming unit  93  has the yellow toner container  900 Y, the magenta toner container  900 M, the cyan toner container  900 C, the black toner container  900 K, and developing units  10 Y,  10 M,  10 C, and  10 K respectively disposed below the toner containers  900 Y,  900 M,  900 C, and  900 K and corresponding to the YMCK colors. 
     The image forming unit  93  is provided with photosensitive drums  17  for bearing toner images of the four respective colors. The photosensitive drums  17  may be composed of an amorphous silicon (a-Si) based material. The photosensitive drums  17  receive yellow, magenta, cyan, and black toners respectively from the corresponding toner containers  900 Y,  900 M,  900 C, and  900 K. Although the image forming unit  93  according to this embodiment is configured to form full-color images, as mentioned above, the image forming unit  93  is not limited to this example and may alternatively be configured to form monochrome images or color images other than full-color images. 
     Each photosensitive drum  17  is surrounded by, for example, a charger  16 , the developing unit  10  ( 10 Y,  10 M,  10 C, or  10 K), a transfer roller  19 , and a cleaning unit  18 . The charger  16  electrically and uniformly charges the surface of the photosensitive drum  17 . The electrically-charged surface of the photosensitive drum  17  is exposed to light by the exposure unit  94 , thereby forming an electrostatic latent image. The developing units  10 Y,  10 M,  10 C, and  10 K develop the electrostatic latent images formed on the corresponding photosensitive drums  17  by using the color toners supplied from the respective toner containers  900 Y,  900 M,  900 C, and  900 K, thereby forming visual images. Each transfer roller  19  forms a nip together with the corresponding photosensitive drum  17  with an intermediate transfer belt  921  interposed therebetween, and primarily transfers the toner image on the photosensitive drum  17  onto the intermediate transfer belt  921 . The cleaning units  18  are each configured to clean the peripheral surface of the corresponding photosensitive drum  17  after the toner image is transferred therefrom. 
     The developing units  10 Y,  10 M,  10 C, and  10 K each include a casing  20 . This casing  20  holds a two-component developer containing a magnetic carrier and toner. Inside the casing  20 , two rotatable stirring rollers  11  and  12  with their longitudinal direction as the axial direction are disposed parallel to each other near the bottom of the casing  20 . 
     A developer circulation path is set at an inner bottom surface of the casing  20 , and the stirring rollers  11  and  12  are disposed within this circulation path. A partition wall  201  stands upward from the bottom of the casing  20  and extends between the stirring rollers  11  and  12  in the axial direction thereof. This partition wall  201  is configured to partition the circulation path, such that the circulation path extends around the partition wall  201 . The two-component developer is electrically charged while being stirred in and transported through this circulation path by the stirring rollers  11  and  12 . 
     The two-component developer circulates within the casing  20  while being stirred by the stirring rollers  11  and  12 . The two-component developer becomes electrically charged, and the two-component developer on the stirring roller  11  is transported upward by being attracted towards a magnetic roller  14  disposed thereabove. The two-component developer attracted to the magnetic roller  14  forms a magnetic brush (not shown) thereon. The layer thickness of the magnetic brush is controlled by a doctor blade  13 , and a potential difference between the magnetic roller  14  and a developing roller  15  causes a toner layer to be formed on the developing roller  15 . Then, an electrostatic latent image on the photosensitive drum  17  is developed by the toner layer on the developing roller  15 . 
     The exposure unit  94  includes various optical elements, such as a light source, a polygonal mirror, a reflecting mirror, and a deflecting mirror, and emits light based on image data to the peripheral surface of each of the photosensitive drums  17  provided in the image forming unit  93  so as to form an electrostatic latent image. 
     The intermediate transfer unit  92  includes the intermediate transfer belt  921 , a driving roller  922 , and a driven roller  923 . The toner images from the multiple photosensitive drums  17  are primarily transferred onto the intermediate transfer belt  921  in a superimposed fashion. A secondary transfer roller  980  included in a secondary transfer section  98  and disposed facing the driving roller  922  secondarily transfers the superimposed toner image onto a sheet fed from the sheet feeder  130 . The driving roller  922  and the driven roller  923  rotationally drive the intermediate transfer belt  921 . The driving roller  922  and the driven roller  923  are rotatably supported by a casing (not shown). 
     The fixing unit  97  is configured to perform a fixing process on the toner image secondarily transferred onto the sheet, and includes a fixing roller having a built-in heat source and a pressure roller that forms a fixation nip together with the fixing roller. The sheet having undergone the fixing process is conveyed toward the ejecting unit  96  provided at the top of the printer body  200 . 
     The ejecting unit  96  ejects the sheet conveyed from the fixing unit  97  onto the top cover  911  serving as an output tray. 
     The sheet feeder  130  includes a sheet cassette detachably fitted to the housing  90  of the printer body  200  and a sheet conveying path for conveying sheets stored in the sheet cassette towards the image forming unit  93 . In the sheet feeder  130 , the sheets are fed one by one to the sheet conveying path by driving, for example, a pickup roller provided in the sheet feeder  130  so that each sheet can be delivered to the image forming unit  93 . 
       FIG. 3  is an external view of a portion of the housing  90  of the printer body  200  accommodating the intermediate transfer unit  92 , the image forming unit  93 , the exposure unit  94 , the fixing unit  97  and the like, as viewed from the right side of the color printer  1 . The housing (i.e., the main body frame)  90  also accommodates a plurality of drivers  170  (four drivers  170  in  FIG. 3 ) for driving the respective photosensitive drums  17 , and a plurality of motors  30  (four motors  30  in  FIG. 3 ) serving as driving sources for a predetermined image forming process. The motors  30  are DC motors. In this embodiment, the motors  30  are configured to rotate rotating members (not shown), such as stirring members and supply screws, disposed inside the toner containers  900 Y,  900 M,  900 C, and  900 K so as to supply toners to the corresponding developing units  10 Y,  10 M,  10 C, and  10 K. Accordingly, the motors  30  are disposed adjacent to the corresponding toner containers  900 Y,  900 M,  900 C, and  900 K, and the spaces surrounding the motors  30  are extremely small. 
       FIG. 4  is an enlarged view of a portion of  FIG. 3 , showing the motors  30  and their surrounding area. As shown in  FIG. 4 , a wire  50  is routed in the vicinity of the motors  30 . In detail, the wire  50  is routed by being guided by guide segments  52  along a wall surface of the housing  90  so as to extend beside the motor  30  located adjacent to the toner container  900 Y, the motor  30  located adjacent to the toner container  900 M, the motor  30  located adjacent to the toner container  900 C, and the motor  30  located adjacent to the toner container  900 K. In this manner, the motors  30  and the wire  50  are packed within a small space surrounding the toner containers  900 Y,  900 M,  900 C, and  900 K. With this arrangement, the color-image forming feature and size reduction can both be achieved in the color printer  1 . However, when installing the motors  30  in the housing  90  or routing the wire  50  along the housing  90 , the wire  50  easily tends to come into contact with peripheral edges  33  of the motors  30 . This can sometimes cause the wire  50  to become cut or broken. Therefore, in the color printer  1 , it is preferable that the wire  50  can be routed readily as well as be prevented from being cut even if the wire  50  and the motors  30  are to be packed within a small space. In light of this, in this embodiment, a sheet member is attached to each of the motors  30  so as to facilitate the routing of the wire  50  as well as to prevent the wire  50  from being cut. Sheet members  40  will be described in detail below. For the sake of convenience, the sheet members  40  attached to the motors  30  are not shown in  FIG. 4 . 
       FIG. 5  is an enlarged view of a portion of  FIG. 4 , illustrating a wiring structure in the vicinity of the motors  30  in this embodiment.  FIG. 6  illustrates one of the motors  30  and the corresponding sheet member  40  attached to the motor  30 .  FIG. 7  is a plan view showing the sheet member  40  before it is attached to the motor  30 . Each motor  30  is a cylindrical motor having a cylindrical surface  32 , two end surfaces  34 , and peripheral edges  33  between the cylindrical surface  32  and the end surfaces  34 . On the other hand, the sheet member  40  attached to the motor  30  is a flexible sheet member having a thickness of 50 μm to 125 μm and is attached along the cylindrical surface  32  of the motor  30  so as to cover at least a part of one peripheral edge  33 . The sheet member  40  has a shape substantially capable of maintaining the wire  50  in the routed state. 
     In detail, the sheet member  40  includes a rectangular or strip-like main body  40   a . The main body  40   a  has an attachment segment  41  having an adhesive surface and attachable to the cylindrical surface  32  of the motor  30  with the adhesive surface, and a contact-prevention segment  42  set to cover at least a part of the peripheral edge  33  of the motor  30  when the attachment segment  41  is attached along the cylindrical surface  32 . The adhesive surface of the attachment segment  41  is formed with, for example, double-sided tape. 
     Since the attachment segment  41  is attached along the cylindrical surface  32  of the motor  30 , the attachment segment  41  substantially has the same curvature as the cylindrical surface  32 . Therefore, when the attachment segment  41  is attached to the cylindrical surface  32 , the contact-prevention segment  42  integrated with the attachment segment  41  also substantially has the same curvature as the cylindrical surface  32 . Moreover, in the state where the attachment segment  41  is attached to the cylindrical surface  32 , the contact-prevention segment  42  is set to have a height H from the proximate end surface  34  of the motor  30 . The contact-prevention segment  42  does not have an adhesive surface. 
     Since the contact-prevention segment  42  of the sheet member  40  covers the proximate peripheral edge  33  of the motor  30 , the wire  50  is prevented from coming into contact with the peripheral edge  33  when routing the wire  50  or installing the motor  30 . As a result, the wire  50  can be prevented from being damaged by the peripheral edge  33 . 
     The sheet member  40  also has a protrusion  43  that protrudes in a direction away from the attachment segment  41  from a substantially central section of the contact-prevention segment  42  in the longitudinal direction thereof. The protrusion  43  also substantially has the same curvature as the cylindrical surface  32  of the motor  30  when the attachment segment  41  is attached to the cylindrical surface  32 . Since the sheet member  40  is flexible, the protrusion  43  can be bent towards the end surface  34  of the motor  30 , as shown with arrow in  FIG. 6 . When routing the wire  50 , the wire  50  is pressed against the protrusion  43  to bend the protrusion  43  inward from the outside of the motor  30  in the radial direction thereof, namely, from the opposite side of the wall surface of the housing  90 , so that the wire  50  can be positioned along the wall surface of the housing  90  as well as above the motor  30 . After routing the wire  50 , the protrusion  43  returns to its original position. Consequently, the wire  50  is routed while being maintained on the protrusion  43 . 
     The wire  50  is routed linearly since the protrusions  43  of the sheet members  40  attached to the motors  30  are arranged in the horizontal direction. 
     The wire  50  sometimes receives an external force that tries to displace the wire  50  from its predetermined routing position. In that case, the external force is applied to the protrusions  43  via the wire  50 . However, since each of the protrusions  43  is bent along the cylindrical surface  32  of the corresponding motor  30  so as to substantially have the same curvature as the cylindrical surface  32 , the protrusions  43  have sufficient rigidity against the external force. In consequence, the protrusions  43  can regulate the movement of the wire  50  so as to maintain the wire  50  in the routed state. Therefore, the protrusions  43  act as regulating segments that are capable of maintaining the wire  50  in the routed state. Although the regulating segments substantially have a trapezoidal shape in the drawings, the shape thereof is not limited so long as the regulating segments are capable of maintaining the wire  50  in the routed state. 
     As is apparent from the above description, the wiring structure of the color printer  1  according to this embodiment employs the flexible sheet members  40  having low rigidity to prevent the wire  50  from being cut and to maintain the wire  50  in the routed state.