Abstract:
A prop is extending from the printer unit upwards. A rear end portion of an upper casing is coupled with an upper portion of the prop pivotably in a vertical direction. A transparent platen is provided on a top face of the upper casing. An image capturer is provided in the upper casing and operable to capture an image on an original disposed on the platen and to output image data. A projection is provided on a bottom face of the upper casing and is extending in a front-rear direction of the upper casing. The projection has a rear end face adapted to be supported by the prop when the upper casing is placed in a first position causing the platen to extend horizontally. The rear end face extends obliquely in a forward-downward direction.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to an image forming apparatus.  
         [0002]     As an image forming apparatus including a printer and an image scanner which can be operated independently or under control of a personal computer (PC), such as a so-called hybrid machine, there has been known such a structure that a scanner unit is mounted on a top plate of a rack, and a printer unit provided with a caster is installed below the top plate. When an original such as a bound book is to be read, a user will strongly press the original against an original table for enhancing tightness of contact between the original and the original table. For this reason, the top plate on which the scanner unit is mounted, and a connecting structure between the top plate and a prop are required to have high rigidity.  
         [0003]     By holding the scanner unit on the top plate of the rack, it is possible to secure a space above the printer unit and to eject printed sheets of paper onto an upper face of the printer unit, which will make the image forming apparatus more compact, as compared with a case where a sheet ejection tray is provided on a side face. Moreover, because the top plate on which the scanner unit is mounted is supported by the prop in a cantilevered manner, the space between the top plate and the printer unit is made open in three directions, and operability in taking out the printed sheets will be improved.  
         [0004]     However, in the structure where the rack for holding the scanner unit is a separate body from the printer unit, and the printer unit must be pulled out from underneath of the top plate of the rack on each occasion of performing maintenance, for example, removal of jammed sheets or replenishment of toner, there has been such a problem that a moving space for the printer unit must be kept around the image forming apparatus.  
       SUMMARY OF THE INVENTION  
       [0005]     It is therefore an object of the invention to provide an image forming apparatus which requires a small installation space, and has excellent operability on occasion of taking out sheets of paper and performing maintenance.  
         [0006]     In order to achieve the above object, according to the invention, there is provided an image forming apparatus, comprising:  
         [0007]     a printer unit;  
         [0008]     a prop, extending from the printer unit upwards;  
         [0009]     an upper casing, a rear end portion of which is coupled with an upper portion of the prop pivotably in a vertical direction;  
         [0010]     a transparent platen, provided on a top face of the upper casing;  
         [0011]     an image capturer, provided in the upper casing and operable to capture an image on an original disposed on the platen and to output image data; and  
         [0012]     a projection, provided on a bottom face of the upper casing and extending in a front-rear direction of the upper casing, the projection having a rear end face adapted to be supported by the prop when the upper casing is placed in a first position causing the platen to extend horizontally,  
         [0013]     wherein the rear end face extends obliquely in a forward-downward direction.  
         [0014]     With this structure, it is possible to enhance rigidity of the upper casing without supporting a front part of the upper casing. Moreover, by pivotably connecting the upper casing which contains the image capturer to the prop, it will be easy to work in an upper part of the printer unit on occasion of performing maintenance or so, and there will be no necessity of moving the printer unit for maintenance purpose. As the results, space for installation will be decreased.  
         [0015]     Preferably, a lower end face of the projection obliquely extends from a lower end of the rear end face in a forward-upward direction.  
         [0016]     Preferably, the prop has a front end face obliquely extends in a forward-downward direction, so that the rear end face of the projection comes in contact with the front end face when the upper casing is placed in the first position.  
         [0017]     Preferably, the prop has a top end face adapted to support a portion of the bottom face of the upper casing that is closer to a rear end of the upper casing than the projection, when the upper casing is placed in the first position.  
         [0018]     Preferably, the printer unit is configured to eject a printing medium from a top portion thereof. In this case, space for installation will be decreased.  
         [0019]     Preferably, the printer unit comprises: a lower casing, having an opening at a top portion thereof; a cover, coupled with the lower casing pivotably in the vertical direction and adapted to open or close the opening; and a print engine, accommodate in the lower casing so as to be exposed from the opening when the cover opens the opening, and operable to print the image data on a printing medium.  
         [0020]     With this structure, the user can make use of a large space above the printer unit in a state where the upper casing and cover have been lifted, and workability for maintenance such as removal of the jammed sheets or exchange of the toner will be improved. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]     In the accompanying drawings:  
         [0022]      FIG. 1  is a side view showing a state that a printer unit in a hybrid machine according to a first embodiment of the invention is opened;  
         [0023]      FIG. 2  is a perspective view of the hybrid machine of  FIG. 1 ;  
         [0024]      FIG. 3  is a schematic view of a scanner unit in the hybrid machine of  FIG. 1 ;  
         [0025]      FIG. 4  is a side view showing a state that the scanner unit in the hybrid of  FIG. 1  is opened;  
         [0026]      FIG. 5  is a schematic section view of the printer unit of  FIG. 1 ;  
         [0027]      FIG. 6  is a perspective view showing a state that the inside of the printer unit in the hybrid machine of  FIG. 1  is opened;  
         [0028]      FIG. 7  is a side view showing a state that the scanner unit in the hybrid machine of  FIG. 1  is closed;  
         [0029]      FIG. 8  is a front view showing the state shown in  FIG. 7 ;  
         [0030]      FIG. 9  is a section view of a scanner casing in the hybrid machine of  FIG. 1 ;  
         [0031]      FIGS. 10A and 10B  are schematic views for explaining disadvantages in the conventional structure;  
         [0032]      FIG. 11A  is a schematic view of a scanner unit according to a second embodiment of the invention;  
         [0033]      FIG. 11B  is a schematic view showing a modified example of the scanner unit of  FIG. 11A ;  
         [0034]      FIG. 12  is a schematic view of a hybrid machine according to a third embodiment of the invention; and  
         [0035]      FIG. 13  is a schematic view of a hybrid machine according to a fourth embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0036]     Embodiments of the invention will be described below in detail with reference to the accompanying drawings.  
         [0037]      FIG. 2  is a perspective view showing an external appearance of a hybrid machine  1  as an image forming apparatus according to a first embodiment of the invention. The hybrid machine  1  includes a scanner unit  12  for reading an original, an ASF (Automatic Sheet Feeding) unit  24 , a printer unit  11  for printing an image which has been read, and props  13 . The scanner unit  12  is pivotably connected to upper parts of the props  13 . The props  13  are fixed to an upper part of the printer unit  11  so as to tiltably support the scanner unit  12 . It is to be noted that the props  13  need not be fixed to the printer unit  11 , but may be independently provided on an installation plane of the hybrid machine  1 .  
         [0038]      FIG. 3  is a schematic view showing an interior structure of the scanner unit  12 . A box-shaped scanner casing  20  as an upper casing is open in its upper part, and connected to the props  13  so as to pivot by hinges, which are not shown. An original table  22  is a transparent glass plate which covers the opening formed in the upper part of the scanner casing  20 , and is fixed to the scanner casing  20 . An original M is placed on a table face of the original table  22 .  
         [0039]     A box-shaped carriage  30  is contained inside the scanner casing  20 . The carriage  30  is slidably held by a rod-shaped carriage guide  32  which is fixed to the scanner casing  20 . The carriage  30  is locked to a belt  44  which is driven by a motor  42 . The carriage  30  reciprocally moves in an axial direction of the carriage guide  32  with circulation of the belt  44 .  
         [0040]     Inside the carriage  30 , there are contained a scanning circuit board  34  equipped with a linear image sensor, a lens  36 , a mirror  38 , and a light source  40 . The light source  40  illuminates the original near a scanning line, and the mirror  38  and the lens  36  form an image of reflective light of the illuminated original M on the scanning line, on a light receiving face of the scanning circuit board  34 . The linear image sensor is mounted on the scanning circuit board  34  in such a manner that light receiving elements of respective colors, red, green and blue are rectilinearly arranged. The linear image sensor outputs electric signals corresponding to degree of light of the optical image which has been formed on the light receiving face. The electric signals outputted from the linear image sensor is converted to digital image data in an analogue front end section and a digital image processing section, which are not shown. The above described carriage  30 , carriage guide  32 , motor  42 , belt  44 , scanning circuit board  34 , lens  36 , mirror  38  and light source  40  constitute an image capturer.  
         [0041]     The ASF unit  24  is pivotably connected to the scanner casing  20  so as to make the table face of the original table  22  free, as shown in  FIG. 4 . The ASF unit  24  conveys the original which has been placed on a sheet supporting plate  26 , from an inlet  28  to the table face of the original table  22 .  
         [0042]      FIG. 5  is a schematic view showing an interior structure of the printer unit  11 . A printer casing  70  as a lower casing contains a printing section of various printing systems such as a laser system, an inkjet system and so on. A structure of the printing section will be described hereunder referring to the printing section of color laser system, as an example. An exposing device  52  irradiates laser to a photosensitive body  50  which has been electrified with electrostatic latent images of respective colors, such as cyan (C), magenta (M), yellow (Y), black (K), thereby to form the electrostatic latent images. A developing device  56  develops the electrostatic latent images formed on the photosensitive body  50  as toner images, by using toners of different colors which are supplied from toner cartridges  54 C,  54 M,  54 Y,  54 K of the respective colors mounted on the printer unit  11 . A primary transfer unit  60  transfers the toner images of the respective colors which have been developed on the photosensitive body  50  to a transfer belt  58  thereby to form a color toner image. A conveying unit  64  conveys sheets of paper from a sheet cassette  68 . A secondary transfer unit  62  transfers the color toner image formed on the transfer belt  58  to the sheet of paper which has been conveyed. A fuser unit  66  fuses the transferred color toner image with the sheet of paper, and ejects it from an outlet  69 . The structure of the printing section contained in the printer casing  70  has been described above.  
         [0043]      FIGS. 1 and 6  are a side view and a perspective view respectively showing a hybrid machine  1  in a state where the scanner unit  12  and a printer cover  72  are fully opened. An opening  74  is formed in an upper part of the printer casing  70 . The printer cover  72  is pivotably connected to the printer casing  70  so that the opening  74  of the printer casing  70  can be covered in a fully closed state of the printer cover  72 . When a front end part of the scanner unit  12  is lifted, an upper part of the printer unit  11  is opened, and therefore, it is possible to extensively pivot the printer cover  72  in an opening direction. Then, the printing section (omitted in  FIG. 6 ) is exposed from the opening  74 , and the upper part of the printer unit  11  is extensively opened. Therefore, it is easy to insert a hand or a tool into the printer casing  70 , which facilitates maintenance of the printing section.  
         [0044]     A control panel  14  is fixed to the upper part of the printer casing  70 . The control panel  14  is provided with buttons for various operations, LCDs and so on, and receives various orders from the user, such as setting of copying conditions.  
         [0045]      FIG. 7  is a side view of the hybrid machine  1 .  FIG. 8  is a front view of the hybrid machine  1 . For the purpose of enhancing rigidity of the scanner casing  20 , the scanner casing  20  is provided with projections  80 ,  81  at two positions on its bottom face. Side walls  83  of both the projections  80 ,  81  are in a shape of triangular plate, extending in parallel to each other from a front end to a back end of the scanner casing  20  and at a right angle with respect to a plane  90  including a table face of the original table  22 . Therefore, lower end walls  82 ,  85  in front parts of the projections  80 ,  81  are inclined downward in a direction from a front face to a back face of the hybrid machine  1 . In other words, a space between the scanner casing  20  and the printer unit  11  is larger in the front face side of the image forming apparatus, and thus, operability has been improved. Although the projections  80 ,  81  are provided at the two positions on the bottom face of the scanner casing  20  in this embodiment, the scanner casing may be provided with the projection at only one position or at more than three positions.  
         [0046]     Back end walls  84 ,  79  (See  FIG. 6 ) of the projections  80 ,  81  are butted against front end faces  86  of the props  13 , and the bottom face of the scanner casing  20  in an area backward of the projections  80 ,  81  is butted against upper end faces  87  of the props  13 , whereby the scanner unit  12  is held in such a manner that the plane  90  including the table face of the original table  22  may be horizontally kept.  
         [0047]     When a vertically downward force is applied to the original table  22 , the side walls  83  of the projections  80 ,  81  prevent the bottom of the scanner casing  20  from being flexed with the force, because the side walls are plate-shaped in parallel with an axis of direction of the force. Moreover, when a force for pressing down the front end part of the scanner casing  20  is exerted in a state where the back end part of the scanner casing  20  is connected to the props  13  by the hinges, stresses acting on the side walls  83  of the projections  80 ,  81  become larger in a backward direction. Due to the triangular shape of the side walls  83  which is broader in the backward direction, the stresses caused by the force for pressing down the front end part of the scanner casing  20  are made uniform.  
         [0048]     The back end walls  84  of the projections  80 ,  81  including the side walls  83  are supported by the front end faces  86  of the props  13 . The back end wall  84  of the projection  80  is plate-shaped extending downward in a direction away from a rotation center line of the scanner casing  20 , in a state where the plane  90  including the table face of the original table  22  is horizontally kept. Specifically, the plate-shaped back end wall  84  is inclined downward from the back side to the front side of the hybrid machine  1 . When the force for pressing down the front end part of the scanner casing  20  is exerted in a state where the back end part of the scanner casing  20  is connected to the props  13  by the hinges, the bottom of the scanner casing  20  is likely to be flexed in such a manner that the front end part of the bottom of the scanner casing  20  may approach the props  13 . On this occasion, the force for pressing down the front end part of the scanner casing  20  is exerted on the scanner casing  20 , as compression stresses on the side walls  83  of the projections  80 ,  81  in a longitudinal direction thereof, because the back end walls  84  of the projections  80 ,  81  are abutted against the front end faces  86  of the props  13 . Because the side walls  83  of the plate-shaped projections  80 ,  81  are in parallel with an axis of the longitudinal direction, the scanner casing  20  is prevented from being flexed with the force for pressing down the front end part of the scanner casing  20 , in such a manner that the front end part of the bottom of the scanner casing  20  may approach the props  13 .  
         [0049]     The props  13  have the front end faces  86  which support the back end walls  84  of the projections  80 ,  81 . The front end faces  86  are faces which are inclined with respect to a vertical direction at a same angle as the back end walls  84  of the projections  80 ,  81 . As shown in  FIG. 9 , the projections  80 ,  81  are hollow, and the lower end walls  82 ,  85  and the back end walls  84  are reinforced from inside by reinforcing members  88  which are formed of sheet metal. Each of the reinforcing members  88  has a flat plate part  89  which is parallel to the side walls  83  of the projections  80 ,  81 . The flat plate part  89  of the reinforcing member  88  prevents flexure of the scanner casing  20  as well as the side walls  83  of the projections  80 ,  81 . It is to be noted that the projections  80 ,  81  may be made solid, and the reinforcing member  88  may be omitted.  
         [0050]     According to the hybrid machine  1  in this embodiment, the scanner casing  20  is tiltably connected to the props  13 , and structural units (the projections  80 ,  81 ) for preventing flexure of the scanner casing  20  are integrally provided on the scanner casing  20 . As the results, on occasion of performing maintenance of the interior of the printer casing  70 , workability can be improved. For example, by providing a cantilever beam  131  on the prop  13  as shown in  FIG. 10A , it is also possible to prevent flexure of the scanner casing  20 . However, when the user lifts the front end part of the scanner casing  20 , as shown in  FIG. 10B , to perform maintenance work of the interior of the printer casing  70 , the cantilever beam  131  remains near the printer casing  70  and would be an obstacle for the work.  
         [0051]     As described above, according to the first embodiment of the invention, the scanner casing  20  is provided with the projections  80 ,  81  on the bottom face thereof, and the back end walls  84  of the projections  80 ,  81  are supported by the front end walls  86  of the props  13 . In this manner, it is possible to enhance the rigidity of the scanner casing  20 , and to prevent flexure of the scanner casing when the original is read. Moreover, because the scanner casing  20  is pivotably connected to the props  13 , and the opening is formed in the upper part of the printer casing  70 , the space above the printer unit  11  can be widely used to perform maintenance of the printing section. As the results, there is no necessity of moving the printer unit  11  for the purpose of maintenance, and therefore, the space for installation can be minimized. Further, because the printer unit  11  ejects the sheets of paper to the upper part of the printer casing  70 , the installation space can be minimized.  
         [0052]      FIGS. 11A and 11B  are front views and side views of the scanner unit  12  and the ASF unit  24  of the hybrid machine  1 , as an image forming apparatus according to a second embodiment of the invention. As shown in  FIG. 11A , the projection  80  for preventing flexure of the scanner casing  20  is a piece of projection which covers almost all part of the bottom of the scanner casing  20 . The side walls  83  of the projection  80  are in a shape of a triangular plate, extending in parallel with each other from the front end to the back end of the scanner casing  20  and at a right angle with respect to the plane  90  including the table face of the original table  22 . Therefore, the lower end wall  82  in a front part of the projection  80  has a flat face inclined downwardly in a direction from the front face to the back face of the hybrid machine  1 . Moreover, the lower end wall  82  in the front part of the projection  80  may be formed with a curved face having an upward convex shape, as shown in  FIG. 11B .  
         [0053]      FIG. 12  is a schematic side view of the hybrid machine  1 , as an image forming apparatus according to a third embodiment of the invention. The back end wall  84  of the projection  80  provided on the bottom face of the scanner casing  20  is inclined downwardly in a forward direction from a position near a hinge  95  which connects the scanner casing  20  to the prop  13 , in a horizontal state of the original table  22 . Because the back end wall  84  of the projection  80  is abutted against the front end face  86  of the prop  13 , the scanner unit  12  is supported in such a manner that the plane  90  including the table face of the original table  22  may be horizontally kept.  
         [0054]      FIG. 13  is a schematic side view of the hybrid machine  1 , as an image forming apparatus according to a fourth embodiment of the invention. The scanner casing  20  is pivotably connected to the prop  13  at an upper position of its back face  96 . The back end wall  84  of the projection  80  is abutted against an end face  86  of the prop  13 . A part of the bottom face of the scanner casing  20  backward of the projection  80  is abutted against an end face  87  of the prop  13 . The back face  96  of the scanner casing  20  is abutted against an end face  97  of the prop  13 . The scanner unit  12  is supported in such a manner that the plane  90  including the table face of the original table  22  may be horizontally kept.  
         [0055]     Although the hybrid machines have been described, by way of illustration, as the image forming apparatus in the above described embodiments of the invention, it is also possible to apply the invention to a copying machine. Moreover, although the structure in which microphotograph system is employed as the image capturer has been described by way of illustration, it is also possible to employ a contact type image sensor to compose the image capturer.