Patent Publication Number: US-7583912-B2

Title: Image forming apparatus and image forming apparatus manufacturing method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2006-112184 filed Apr. 14, 2006. 
   BACKGROUND 
   The present invention relates to an image forming apparatus such as a copier, a facsimile machine or a printer, and an image forming apparatus manufacturing method. 
   TECHNICAL FIELD 
   Related Art 
   There is disclosed this type of image forming apparatus having a support member (frame) supporting an image forming unit, plural rollers, motors and the like inside an image forming apparatus main body. 
   However, in the conventional techniques, the image forming unit, the plural rollers and motors are supported with the frame, and an exterior cover is attached to the frame. Accordingly, downsizing of the image forming apparatus and cost reduction cannot be attained without difficulty. 
   SUMMARY 
   The present invention has been made so as to address the above problem, and provides and image forming apparatus in which downsizing and cost reduction are attainable and a manufacturing method of the image forming apparatus. 
   According to an aspect of the invention, an image forming apparatus includes: a pair of opposing covers; a recording part that forms an image on a sheet; a feed roller that feeds the sheet to the recording part; and a discharge roller that discharges the sheet on which the image is formed by the recording part, the recording part and at least one roller of the feed roller and the discharge roller being supported with the pair of the opposition covers. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
       FIG. 1  is a cross-sectional view schematically showing the structure of an image forming apparatus according to a first exemplary embodiment of the present invention; 
       FIG. 2  is an exploded perspective view showing the structure of the image forming apparatus according to the first exemplary embodiment of the present invention; 
       FIG. 3  is a partial cut-away cross-sectional view showing the structure of a cover in the image forming apparatus according to the first exemplary embodiment of the present invention; 
       FIG. 4A  is a partial cut-away cross-sectional view showing the structure of the cover including hollows in the image forming apparatus according to the first exemplary embodiment of the present invention; 
       FIG. 4B  is a cross-sectional view showing the structure of the cover formed with two layers in the image forming apparatus according to the first exemplary embodiment of the present invention; 
       FIG. 5  is an exploded perspective view showing a manufacturing method of the image forming apparatus according to the first exemplary embodiment of the present invention; 
       FIG. 6  is an exploded perspective view showing a manufacturing method of the image forming apparatus according to a second exemplary embodiment of the present invention; and 
       FIG. 7  is a partial cut-away cross-sectional view of an image forming apparatus in a comparative example. 
   

   DETAILED DESCRIPTION 
   Exemplary embodiments of the present invention will be described based on the drawings. 
     FIG. 1  schematically shows the structure of an image forming apparatus  10  according to a first exemplary embodiment of the present invention. The image forming apparatus  10  has covers  12 . A sheet feeder  14  is provided at its one end (left end in  FIG. 1 ) of the covers  12 , and a discharge tray  16  is provided at the other end (right end in  FIG. 1 ) of the covers  12 . Further, an image forming unit  18  is installed in the covers  12 . 
   The image forming unit  18  is an electrophotographic type unit. The image forming unit  18  has a cylindrical photoreceptor  20  used as an image holder, a charger  22  that uniformly charges the photoreceptor  20 , a light writer  24  that optically writes a latent image on the photoreceptor  20  charged with the charger  22 , a developing device  26  having a developing roller  25  to visualize the latent image on the photoreceptor  20  formed with the light writer  24  using developing material, a transfer device  28  having e.g. a transfer roller that transfers the developing material image visualized with the developing device  26  onto a sheet, a cleaner  30  having a cleaning blade  29  to remove developing material remaining on the photoreceptor  20 , and a fixing device  32  that fixes the developing material image on the sheet, transferred with the transfer device  28 , to the sheet. The light writer  24  has e.g. a scan type laser exposure device, however, an LED, a surface emission type laser or the like may be employed as the light writer  24 . 
   The constituent elements of the image forming unit  18 , i.e., the photoreceptor  20 , the charger  22 , the light writer  24 , the developing device  26 , the transfer device  28 , the cleaner  30  and the fixing device  32 , are integrated as a recording part  34 , and accurately positioned with each other. Note that as the temperature of the fixing device  32  becomes high, the fixing device  32  may be provided outside the recording part  34 . Further, an upper surface  34   a  of the recording part  34  is openable. Upon occurrence of paper jam, the upper surface  34   a  is opened, thereby a jammed sheet can be removed. Further, a user can open the upper surface  34   a  of the recording part  34  and exchange each respective functional element (e.g., the developing device  26 ) with a new one. 
   The sheet feeder  14 , having a feed tray  36  used as a sheet container and a feed roller  38  to convey a top sheet contained in the feed tray  36 , feeds sheets stacked on the feed tray  36  to the above-described recording part  34 . 
   A sheet supply path  42  is provided approximately horizontally around a central portion of the image forming apparatus  10 . The feed roller  38 , the recording part  34  and discharge roller  40  to discharge a sheet where an image is formed, are provided on the sheet supply path  42 . 
   In the image forming apparatus  10  having the above structure, the photoreceptor  20  is uniformly charged with the charger  22 , and light from the light writer  24  based on an image signal is emitted on the charged photoreceptor  20  and a latent image is formed on the photoreceptor  20 . The latent image is developed with the developing device  26  using developing material and a developing material image is formed. On the other hand, a sheet contained in the feed tray  36  is fed with the feed roller  38 , and guided to a position between the transfer device  28  and the photoreceptor  20 . When the sheet has been guided to the position between the transfer device  28  and the photoreceptor  20 , the developing material image on the photoreceptor  20  is transferred with the transfer device  28  onto the sheet. The sheet holding the transferred developing material image is passed through the fixing device  32  and discharged with the discharge roller  40  onto the discharge tray  16 . Accordingly, the sheets on the feed tray  36  are sequentially sent through an I-shaped (straight) path to the discharge tray  16 . 
   Next, the detailed structure of the image forming apparatus  10  will be described based on  FIGS. 2 ,  3  and  FIGS. 4A and 4B . 
   The image forming apparatus  10  has a pair of opposing covers  12   a  and  12   b , an upper cover  44  and a rear surface cover  46 . 
   The upper cover  44  having a rounded L-shaped corner is provided so as to cover an upper surface and a front surface (right end portion in  FIG. 1 ) of the image forming apparatus  10 . A sheet discharge port  44   a  is provided at a right end of the upper cover  44 . The rear surface cover  46  having a plate shape is provided on a rear surface (left end portion in  FIG. 1 ) of the image forming apparatus  10 . A sheet supply port  46   a  is provided around an upper end of the rear surface cover  46 . 
   The feed roller  38  has a first rotation shaft  48  to support a first roller  39   a , a second roller  39   b  and a third roller  39   c . A supply gear  50  is fixed to one end of the first rotation shaft  48 . The feed roller  38  is provided around the sheet supply port  46   a . The discharge roller  40  has a second rotation shaft  52  to support a first roller  41   a , a second roller  41   b  and a third roller  41   c . A discharge gear  54  is fixed to one end of the second rotation shaft  52 . The discharge roller  40  is provided around the sheet discharge port  44   a . Further, a plate-shaped sheet guide  56  to guide a sheet being conveyed is provided above the second rotation shaft  52 . The sheet guide  56  has three through holes  58 . The through holes  58  are formed in positions corresponding to the first roller  41   a , the second roller  41   b  and the third roller  41   c  of the discharge roller  40 , and the first roller  41   a , the second roller  41   b  and the third roller  41   c  are projected from an upper surface of the sheet guide  56 . 
   The recording part  34  has a metal chassis  35 . The above-described photoreceptor  20 , the charger  22 , the light writer  24 , the developing device  26 , the transfer device  28 , the cleaner  30  and the fixing device  32  are supported with the chassis  35 . In this manner, as the respective constituent elements of the image forming unit  18  are supported with the chassis  35  of the recording part  34 , the positional accuracy of the respective constituent elements, which needs to be high, can be maintained. Respectively four engagement holes  34   b  are formed in both side surfaces of the recording part  34 , and engaged with recording unit support studs  62   d  of the first cover  12   a  and the second cover  12   b  to be described later. Further, a sheet supply port  34   c  (shown in  FIG. 1 ) is formed in a rear surface of the recording part  34  (left side surface in  FIG. 2 ), and a sheet discharge port  34   d  (shown in  FIGS. 1 and 2 ) is formed in a front surface of the recording part  34  (right side surface in  FIG. 2 ). Accordingly, a sheet fed into the recording part  34  via the sheet supply port  34   c  is discharged via the sheet discharge port  34   d  to the outside of the recording part  34 . As driving necessary for the recording part  34 , a driving unit may be provided inside the recording part  34 , or the driving may be transmitted from a first or second motor to be described later. 
   The cover  12 , which is made of e.g. resin, has a first cover  12   a  and a second cover  12   b . The first cover  12   a  and the second cover  12   b  are provided in a pair in opposing positions. Further, a support member  60  as a support unit is integrally formed with the cover  12  on an inner wall surface of the cover  12 . The support member  60  has plural column-shaped studs  62  and plural cylindrical-shaped bearings  64  projected toward inside of the covers  12 . 
   The studs  62  include guide support studs  62   a , first motor support studs  62   b , second motor support studs  62   c , recording unit support studs  62   d , a first intermediate gear stud  62   e  (not shown) and a second intermediate gear stud  62   f  (shown in  FIG. 3 ). Further, the bearings  64  include feed roller bearings  64   a , discharge roller bearings  64   b , feed tray bearings  64   c  and discharge tray bearings  64   d . In the present exemplary embodiment, the bearings  64  are integrally formed with the cover  12 , however, ball bearings or the like may be fixed to the cover. 
   The guide support studs  62   a  are provided in respectively two positions on the first cover  12   a  and the second cover  12   b . The guide support studs  62   a  are engaged with respectively two engagement holes  56   a  formed in the both side surfaces of the sheet guide  56 , to support the sheet guide  56 . The first motor support studs  62   d  are provided in e.g. four positions on the first cover  12   a  to support the first motor  66  as a driving unit to drive the feed roller  38 . Further, the second motor support studs  62   c  are provided in e.g. four positions on the first cover  12   a  to support the second motor  68  as a driving unit to drive the discharge roller  40 . 
   The recording unit support studs  62   d  are provided in respectively four positions on the first cover  12   a  and the second cover  12   b . The recording unit support studs  62   d  are engaged with respectively four engagement holes  34   b  formed in the both side surfaces of the recording part  34 , to support the recording part  34 . The first intermediate gear stud  62   e  (not shown) is provided on the first cover  12   a  to rotatably support a first intermediate gear  70  to be described later. Further, as also shown in  FIG. 3 , the second intermediate gear stud  62   f  is provided on the first cover  12   a  to rotatably support a second intermediate gear  72  to be described later. 
   The feed roller bearings  64   a  are provided in respectively one position on the first cover  12   a  and the second cover  12   b . The feed roller bearings  64   a  are rotatably engaged with both ends of the first rotation shaft  48 , to support the feed roller  38 . The discharge roller bearings  64   b  are provided in respectively one position on the first cover  12   a  and the second cover  12   b . The discharge roller bearings  64   b  are rotatably engaged with both ends of the second rotation shaft  52 , to support the discharge roller  40 . 
   The feed tray bearings  64   c  are provided in respectively one position on the first cover  12   a  and the second cover  12   b . The feed tray bearings  64   c  are rotatably engaged with a support shaft  36   a  formed on both side surfaces of the feed tray  36 , to support the feed tray  36 . The discharge tray bearings  64   d  are provided in respectively one position on the first cover  12   a  and the second cover  12   b . The discharge tray bearings  64   d  are rotatably engaged with a support shaft  16   a  formed on both side surfaces of the discharge tray  16 , to support the discharge tray  16 . 
   The first intermediate gear  70  is provided on the first cover  12   a  to be connected to the first motor  66  and the supply gear  50 . Further, as also shown in  FIG. 3 , the second intermediate gear  72  is provided on the first cover  12   a  to be connected to the second motor  68  and the discharge gear  54 . 
   Further, a control board (not shown) to control a power source, motors and the like is attached on an inner wall of the second cover  12   b.    
   In this manner, in the image forming apparatus  10  of the present invention, the recording part  34 , the feed roller  38  and the discharge roller  40  are supported with the pair of opposing covers  12   a  and  12   b.    
   As shown in  FIG. 4A , plural hollows  74  are formed inside the covers  12   a  and  12   b . The hollows  74  are formed by blow molding, gas injection or the like, around vibration sources such as the first motor  66 , the second motor  68 , the first intermediate gear  70  and the second intermediate gear  72 . 
   In this manner, as the hollows  74  are provided inside the covers  12   a  and  12   b , the cross-sectional area of the covers  12   a  and  12   b  is increased, and the rigidity of the covers  12   a  and  12   b  can be improved. Further, as the hollows  74  are provided inside the covers  12   a  and  12   b , noise and vibration transmitted from the vibration sources can be suppressed. 
   Note that it may be arranged such that the covers  12   a  and  12   b  have double-layer structure and vibration isolating material or the like is provided between an inner member and an outer member. 
   Further, as shown in  FIG. 4B , the covers  12   a  and  12   b  are formed with two layers, a side surface cover main body  76  as an inner member and a decorative cover  78  as an outer member. The above-described support member  60  having the studs  62  and the bearings  64  is formed on the side surface main body  76 , and the decorative cover  78  is provided on the outside of the side surface cover main body  76 . 
   In this manner, the covers  12   a  and  12   b  have a double-layer structure including the side surface cover main body  76  and the decorative cover  78 . Even if a sunk spot occurred upon formation of the side surface cover main body  76 , the sunk spot portion can be hidden from the user&#39;s eyes. 
   Note that the “sunk spot” means a dent formed upon injection molding of resin. When the heated resin is cooled and hardened, the volume becomes short due to contraction of the resin, and a dent is formed in a finally hardened portion. 
   Next, an image forming apparatus  100  in a comparative example, compared with the image forming apparatus  10  of the present invention, will be described based on  FIG. 7 . 
   As shown in  FIG. 7 , the image forming apparatus  100  of this comparative example has a pair of opposing side frames  102 . A rotation shaft  106 , to which a motor  104  and a gear  105  are fixed, a recording unit (not shown) and the like are supported with the side frames  102 . Further, a cover  108  is attached to the outside of the side frames  102 . 
   In comparison with the image forming apparatus  100  of the comparative example, in the image forming apparatus  10  of the present invention, the recording part  34 , the feed roller  38 , the discharge roller  40  and the like are supported with the pair of covers  12   a  and  12   b . Accordingly, the side frames in the comparative example can be omitted, thus downsizing of the image forming apparatus  10  in a widthwise direction and cost reduction can be attained. 
   Next, a manufacturing method of the image forming apparatus  10  will be described based on  FIG. 5 . 
   An assembly jig  80  has a bottom plate  80   a  and two side plates  80   b  provided upright in a vertical direction from the bottom plate  80   a . The side plates  80   b  have, e.g. three step members  81  in predetermined positions. 
   As a first process of manufacture of the image forming apparatus  10 , the recording part  34  is placed to be engaged with the first step member  81   a  of the assembly jig  80 , then the feed roller  38  is placed to be engaged with the second step member  81   b  of the assembly jig  80 , and the discharge roller  40  is placed to be engaged with the third step member  81   c  of the assembly jig  80 . Thus the recording part  34 , the feed roller  38  and the discharge roller  40  are positioned with respect to the assembly jig  80 . 
   As a second process, the first cover  12   a  and the second cover  12   b  are attached from the both sides of the recording part  34 , the feed roller  38  and the discharge roller  40  positioned with respect to the assembly jig  80 . That is, the first cover  12   a  and the second cover  12   b  are moved in an arrow A direction in  FIG. 5 , then the engagement holes  34   b  of the recording part  34  are engaged with the recording part support studs  62   d , the first rotation shaft  48  is engaged with the feed roller bearings  64   a , and the second rotation shaft  52  is engaged with the discharge roller bearings  64   b.    
   As a third process, the sheet guide  56 , the feed tray  36  and the discharge tray  16  (shown in  FIG. 2 ) are engaged with the guide support studs  62   a , the feed tray bearings  64   c  and the discharge tray bearings  64   d . Then the upper cover  44  and the rear surface cover  46  (shown in  FIG. 2 ) are fixed to the first cover  12   a  and the second cover  12   b . Next, the assembly jig  80  is removed from the image forming apparatus  10 . 
   Note that the sheet guide  56 , the feed tray  36 , the discharge tray  16 , the upper cover  44  and the rear surface cover  46  may be held with the assembly jig  80 . 
   In this manner, by use of the assembly jig  80 , the respective parts including the recording part  34 , the feed roller  38  and the discharge roller  40  are positioned with respect to the assembly jig  80 . Accordingly, the manufacture of the image forming apparatus  10  can be facilitated. 
   Note that in the present exemplary embodiment, the respective functional elements of the recording part  34  are integrated, however, it may be arranged such that the respective functional elements, as units, are directly supported with the covers  12   a  and  12   b.    
   Next, a second exemplary embodiment of the present invention will be described based on  FIG. 6 . 
   The image forming apparatus  10  of the present exemplary embodiment has the pair of opposing covers  12   a  and  12   b , an upper surface cover  82 , a front surface cover  84  and the rear surface cover  46 . Further, a sheet cassette  86  is removably provided at a lower end of the covers  12   a  and  12   b.    
   The upper surface cover  82  is provided at an upper end of the image forming apparatus  10 , and is provided with a sheet discharge port  82   a  and a sheet discharge part  82   b . The front surface cover  84  is provided on the front surface (right end in  FIG. 6 ) of the image forming apparatus  10 , and plural conveyance rollers  88  are provided on the inner wall surface of the front surface cover  84 . The sheet cassette  86  has a sheet container  86   a  on which plural sheets are stacked, and has a grip member  86   b  on its front surface (right end in  FIG. 6 ). Further, a convex member  90  is provided on both side surfaces of the sheet cassette  86  such that the convex members  90  are slidably engaged with rails  92  provided around the lower end of the pair of covers  12   a  and  12   b.    
   In this manner, in the image forming apparatus  10  of the present exemplary embodiment, the sheet cassette  86  is supported with the pair of opposing covers  12   a  and  12   b.    
   Further, the feed roller  38 , having the first rotation shaft  48  to support the first roller  39   a , the second roller  39   b  and the third roller  39   c , is provided in a position corresponding to the conveyance rollers  88  on the front surface cover  84 . Further, a sheet guide  56  with a predetermined curvature is provided around the first rotation shaft  48 . The sheet guide  56  is provided with e.g., three through holes  58 . The through holes  58  are formed in positions corresponding to the first roller  39   a , the second roller  39   b  and the third roller  39   c , and the first roller  39   a , the second roller  39   b  and the third roller  39   c  are projected from the surface of the sheet guide  56 . The discharge roller  40 , having the second rotation shaft  52  to support the first roller  41   a , the second roller  41   b  and the third roller  41   c , is provided around the sheet discharge port  82   a  of the upper surface cover  82 . 
   The sheet contained in the sheet container  86   a  of the sheet cassette  86  is fed with the feed roller  38  to the recording part  34 , then an image is formed with the recording part  34  on the sheet, and the sheet is discharged with the discharge roller  40  to the discharge unit  82   b . Accordingly, the sheets in the sheet cassette  86  are sequentially passed through an S-shaped path and discharged to the discharge unit  82   b.    
   Note that the sheet cassette  86  of the present exemplary embodiment may be an electrical cassette provided with a control board and the like. 
   As described above, the present invention is applicable to an image forming apparatus having a cover. 
   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.