Abstract:
An image forming apparatus includes an image forming station including a heater for heating a sheet and a discharge opening for discharging a sheet having passed through the heater, in a discharging direction; an image reading station provided above the image forming station to read image information of an original; and a duct portion provided by an upper surface of the image forming station and a lower surface of the image reading station, and a position upstream of the discharge opening with respect to the discharging direction, wherein such a portion of the lower surface of the image reading station as provides the duct portion is at a level higher toward an upstream with respect to the discharging direction.

Description:
FIELD OF THE INVENTION AND RELATED ART 
       [0001]    The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and the like. 
         [0002]    Some conventional image forming apparatuses are provided with an original reading device (original reading section), which is on the main assembly of the image forming apparatus. In the case of this type of image forming apparatus, the water vapor generated in the main assembly of the image forming apparatus is discharged through its sheet discharge opening, and/or water vapor comes out of the discharged sheets. Thus, it is possible that this water vapor will fill up the space between the main assembly and original reading device of the image forming apparatus, condense into droplets of water, on the bottom surface of the original reading device. These droplets of water possibly adhere to sheets as the sheets are discharged through the above-described space. If the original reading device is positioned as high as it is in the case of the image forming apparatus disclosed in Japanese Laid-open Patent Application 2008-281699, this condensation of water vapor is less likely to occur. 
         [0003]    However, positioning an original reading device as high as it is in the case of the image forming apparatus disclosed in Japanese Laid-open Patent Application 2008-281699 increases an image forming apparatus in size. 
       SUMMARY OF THE INVENTION 
       [0004]    Thus, the primary object of the present invention is to provide an image forming apparatus which is capable of efficiently discharging water vapor from the space between its image formation section and original reading section, and yet, is no greater in size than an image forming apparatus in accordance with the prior art. 
         [0005]    According to an aspect of the present invention, there is provided an image forming apparatus comprising an image forming station including a heating portion for heating a sheet and a discharge opening for discharging a sheet having passed through said heating portion, in a discharging direction; an image reading station provided above said image forming station to read image information of an original; and a duct portion provided by an upper surface of said image forming station and a lower surface of said image reading station, at a position upstream of said discharge opening with respect to the discharging direction, wherein such a portion of said lower surface of said image reading station as provides said duct portion is at a level higher toward an upstream with respect to the discharging direction. 
         [0006]    According to another aspect of the present invention, there is provided an image forming apparatus comprising an image forming station including a heating portion for heating a sheet and a sheet stacking portion for stacking the sheet discharged through said heating portion in a discharging direction, said sheet stacking portion being provided in an upper portion of said image forming apparatus; an image reading station provided above said image forming station to read image information of an original; and a duct portion provided by an upper surface of said image forming station and a lower surface of said image reading station, and a position upstream of said stacking portion with respect to the discharging direction, wherein such a portion of said lower surface of said image reading station as provides said duct portion is at a level higher toward an upstream with respect to the discharging direction. 
         [0007]    Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a drawing for showing the structure of the image forming apparatus in the first embodiment of the present invention. 
           [0009]      FIG. 2  is a perspective view of the image forming apparatus in the first embodiment. 
           [0010]      FIG. 3  is a perspective view of the image forming apparatus in the first embodiment when the original reading device is in its upright (open) position relative to the main assembly. 
           [0011]      FIG. 4  is a sectional view of the combination of the original reading device and main assembly of the image forming apparatus in the first embodiment, and shows the positional relationship between the original reading device and main assembly. 
           [0012]      FIG. 5  is a perspective view of the combination of the original reading device and main assembly of the image forming apparatus in the first embodiment, and shows the positional relation ship between the original reading device and main assembly when the original reading device is in its upright (open) position. 
           [0013]      FIG. 6  is a perspective view of the image forming apparatus in the first embodiment as seen from the rear side of the apparatus. 
           [0014]      FIG. 7  is a drawing for showing the water vapor discharge passage of the image forming apparatus in the first embodiment. 
           [0015]      FIG. 8  is a drawing which shows the relationship among the duct entrance height, air flow rate through the duct, calculated with the use of thermal fluid dynamics simulation, and image forming apparatus height, in the first embodiment. 
           [0016]      FIG. 9  is a sectional view of a combination of the original reading device and main assembly of the image forming apparatus in the second embodiment of the present invention, and shows the positional relationship between the original reading device and main assembly. 
           [0017]      FIG. 10  is a sectional view of a combination of the original reading device and main assembly of the image forming apparatus in the third embodiment of the present invention, and shows the positional relationship between the original reading device and main assembly. 
           [0018]      FIG. 11  is a sectional view of a combination of the original reading device and main assembly of the image forming apparatus in the fourth embodiment of the present invention, and shows the positional relationship between the original reading device and main assembly. 
           [0019]      FIG. 12  is a sectional view of a combination of the original reading device and main assembly of the image forming apparatus in the fifth embodiment of the present invention, and shows the positional relationship between the original reading device and main assembly. 
           [0020]      FIG. 13  is a drawing which shows the relationship among the duct entrance height, air flow rate through the duct, calculated with the use of thermal fluid dynamics simulation, and image forming apparatus height, in the fifth embodiment. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment 1 
       [0021]    Hereinafter, a few of the preferred embodiments of the present invention are described with reference to appended drawings.  FIG. 1  is a drawing for showing the structure of the image forming apparatus  1000  in the first embodiment of the present invention. Referring to  FIG. 1 , the image forming apparatus  1000  in this embodiment is provided with an original reading device  100  (original reading section), which is on the top side of the main assembly  10  (image forming section) of the image forming apparatus  1000 , in terms of the vertical direction P. 
         [0022]    In the apparatus main assembly  10 , the photosensitive drums  1   a - 1   d  charged by the charge rollers  2   a - 2   d , respectively, are exposed to a beam of laser light outputted by the exposing device  3  while being modulated according to the information of the image to be formed. Thus, electrostatic latent images are formed on the photosensitive drums  1   a - 1   d , one for one. Then, the four electrostatic latent images are developed by the developing devices  4   a - 4   d  into toner images, one for one, which are different in color. Then, the four toner images, different in color, are sequentially transferred in layers (primary transfer) by the primary transfer rollers  9   a - 9   d , one for one, onto the intermediary transfer belt  5  which is suspended and kept tensioned by the suspending/tensioning members (driver roller  6 , tension roller  7 , and idler roller  8 ). 
         [0023]    Meanwhile, the sheets S in the sheet feeding/conveying tray are conveyed one by one by the sheet feeding roller  13  to the nip between the intermediary transfer belt  5  and secondary transfer roller  12 , in which the toner images are transferred onto the sheet S (secondary transfer). After the transfer of the toner images onto the sheet S, the sheet S is subjected to heat and pressure by the fixing device  14  (fixing section). Consequently, the toner images become fixed to the sheet S. After being conveyed through the fixing device  14 , the sheet S is discharged through the sheet discharge opening  16  into the delivery tray  17  (sheet accumulation surface), which is a part of the top wall of the apparatus main assembly  10 . 
         [0024]      FIG. 2  is a perspective view of the image forming apparatus  1000  in this embodiment. Referring to  FIG. 2 , the original reading device  100  is made up of a scanner  101  and an automatic original conveying section  102 . As an original is conveyed through the automatic original conveying section  102 , it is read by the scanner  101 ; the information necessary to form a copy of the original is obtained by the original reading device  100 . The information of the original obtained by the original reading device is sent to the apparatus main assembly  10 . 
         [0025]      FIG. 3  is a perspective view of a combination of the apparatus main assembly  10  and original reading device  100  when the original reading device  100  is in its upright (open) position relative to the apparatus main assembly  10 . Referring to  FIG. 3 , the original reading device  100  is attached to the apparatus main assembly  10  so that it can be pivotally moved about a pair of hinges  23   a  and  23   b . The apparatus main assembly  10  is provided with a pair of upwardly facing left and right surfaces  22   a  and  22   b , which are on the rear side of the apparatus main assembly  10 , and a pair of upwardly facing left and right surfaces  21   a  and  21   b , which are on the front side of the apparatus main assembly  10 . The pair of upwardly facing left and right surfaces  21   a  and  21   b  are the surfaces by which the original reading device  100  is supported when the original reading device  100  is in use. 
         [0026]    Further, there are provided a pair of protrusions  103   a  and  103   b , which are on the front-left and front-right sides of the apparatus main assembly  10 . When the image forming apparatus  1000  is in use, the original reading device  100  is kept in its horizontal (closed) position ( FIG. 2 ), and the protrusions  103   a  and  103   b  remain in contact with the supporting surfaces  21   a  and  21   b , respectively. In a case where the sheets discharged into the delivery tray  17  are small, or the discharge opening  16  became jammed with a sheet of paper, a user is to pivotally move the original reading device  100  into its upright (open) position. 
         [0027]    Referring to  FIG. 4 , the scanner  101  has a reading sensor  104  and a carriage  105 , which are movable in the left-right direction. The bottom side of the scanner  101  is covered with a carriage cover section  106  and a reading sensor cover section  107  of the scanner casing. The carriage covering section  106  covers the carriage track. The reading sensor covering section  107  covers the reading sensor track. The carriage  105  is on the rear end side of the apparatus main assembly  10 . Therefore, it is possible to provide a space Z between the front side of the delivery tray  17  and the front side of the reading sensor cover section  107 . The presence of this space Z makes it easier for a user to access the sheets S in the delivery tray  17 . 
         [0028]    Referring to  FIG. 5 , the upwardly facing side of the apparatus main assembly  10  is provided with a slanted surface  24 , which covers the rear-center portion of the top side of the apparatus main assembly  10 . The slanted surface  24  is between the pair of rear-top surfaces  22   a  and  22   b . It extends rearward (from downstream side to upstream side, in terms of sheet discharge direction E) from the adjacencies of the sheet discharge opening  16 , and is slanted in such a manner that its rear end is higher than its front end in terms of the vertical direction. That is, the rear end portion (downstream end in terms of sheet discharge direction E) of the slanted surface  24  is positioned higher than the front end portion (upstream end in terms of sheet discharge direction E) of the slanted surface  24 . The center portion of the carriage cover section  106  is provided with front-center surface  108   a  (first surface), which is on the front side (downstream in terms of sheet discharge direction E), and a rear-center surface (second surface)  108   b , which is on the rear side (upstream in terms of sheet discharge direction E). The front-center surface  108   a  and rear-center surface  108   b  are positioned so that they oppose the slanted surface  24 . The rear-center surface  108   b  is positioned higher than the front-center surface  108   a  in terms of the vertical direction. 
         [0029]    Referring to  FIG. 4 , a duct  200  (space) is formed by the bottom surface (front-center surface  108   a , rear-center surface  108   b ) of the original reading device  100 , and the top surface (rear-top surfaces  22   a  and  22   b , and slanted surface  24 ) of the apparatus main assembly  10 . Referring to  FIGS. 4 and 6 , the duct  200  has the front and rear openings  201  and  202 . The front opening  201  is on the front side of the apparatus main assembly  10 , and the rear opening  202  is on the rear side of the apparatus main assembly  10 . In terms of the vertical direction, the rear opening  202  of the duct  200  is positioned higher than the front opening  201  of the duct  200 . 
         [0030]      FIG. 7  is a drawing which shows the water vapor discharge passage of the image forming apparatus  1000  in this embodiment. Referring to  FIG. 7 , the sheet S is discharged from the sheet discharge opening  16  in the direction indicated by an arrow mark E. Further, as the sheet S is heated by the fixing device  14 , the moisture in the sheet S evaporates. The resultant water vapor is discharged out of the fixing device  14  through the sheet discharge opening  16 . By the way, even after sheets S are discharged from the apparatus main assembly  10  in a manner to be layered in the delivery tray  17 , the moisture in the sheets S is made to evaporate, by the heat remaining in the sheets S. 
         [0031]    As the moisture in the sheets S evaporates, the resultant water vapor fills the discharge area X which is between the delivery tray  17  and the bottom surface (carriage cover section  106 , reading sensor cover section  107 ) of the original reading device  100 . As the water vapor fills up the discharge area X, a part of the water vapor disperses frontward (downstream, in terms of sheet discharge direction E) of the apparatus main assembly  10  and is discharged out of the apparatus main assembly  10  (direction indicated by arrow mark A). 
         [0032]    In terms of the vertical direction, the fixing device  14  is positioned lower than the slanted surface  24 . Thus, the heat from the fixing device  14  rises (in direction indicated by an arrow mark D), and warms the slanted surface  24 . Thus, the air in the duct  200  is warmed by the heat from the fixing device  14  through the slanted surface  24 . As the air in the duct  200  is warmed, it reduces in density, and therefore, rises. As a result, the air moves from the front opening  201  of the duct  200 , which is on the upstream side of the sheet discharge opening  16  and delivery tray  17  in terms of the sheet discharging direction E, to the rear opening  202  of the duct  200 . Thus, the water vapor in the discharge area X is drawn by this movement of the air, into the duct  200  through the front opening  201  of the duct  200 , and is discharged out of the apparatus main assembly  10  through the rear opening  202  of the duct  200  (direction indicated by arrow mark B). 
         [0033]      FIG. 8  is a drawing for showing the relationship among the duct entrance height C (height of front opening  201  of duct  200 ), amount by which air flows into the duct  200 , which was calculated by thermal fluid dynamics simulation, and product height (height of image forming apparatus  1000 ). As is evident from  FIG. 8 , by setting the duct entrance height C to a value in a range of 5-15 mm, it is possible to reduce the product in height, while ensuring that air flows into the duct  200  by a sufficient amount. 
         [0034]    By structuring the image forming apparatus  1000  as described above, not only is it possible to highly efficiently discharge the water vapor, from the front side of the apparatus main assembly  10  (direction indicated by arrow mark A), but also, from the rear side of the apparatus main assembly  10  (direction indicated by arrow mark B). Thus, it is possible to highly efficiently discharge the water vapor in the space between the original reading device  100  and main assembly  10  of the image forming apparatus  1000 , from the image forming apparatus  1000 , and therefore, to prevent the water vapor from condensing on the bottom surface of the original reading device  100 , without increasing the image forming apparatus  1000  in size, and also, altering the image forming apparatus  1000  in frontal appearance. By the way, in this embodiment, natural convection is utilized to discharge the water vapor. However, the water vapor may be forcefully discharged with the use of a fan. 
       Embodiment 2 
       [0035]    Next, the image forming apparatus  1000  in the second embodiment is described with reference to the appended drawings. The components, parts thereof, etc., of the image forming apparatus in this embodiment, which are the same in description as the counterparts in the first embodiment are given the same referential codes as those given to the counterparts, and are not described.  FIG. 9  is a sectional view of a combination of the original reading device and main assembly of the image forming apparatus in this embodiment. It shows the positional relationship between the original reading device and apparatus main assembly. 
         [0036]    Referring to  FIG. 9 , the image forming apparatus in this embodiment is provided with a front-center surface  24   a  (third surface) and a rear-center surface  24   b  (fourth surface), which replace the slanted surface  24  in the first embodiment. The front-center surface  24   a  and rear-center surface  24   b  make up the center portion of the rear portion of the top surface of the apparatus main assembly  10 . That is, the front-center surface  24   a  and rear-center surface  24   b  are sandwiched by the left and right end portions  22   a  and  22   b  of the rear portion of the top surface of the apparatus main assembly  10 . 
         [0037]    The front-center surface  24   a  is on the front side (downstream in terms of sheet discharge direction E), and the rear-center surface  24   b  is on the rear side (upstream in terms of sheet discharge direction E). The front-center surface  24   a  and rear-center surface  24   b  are positioned so that they directly face the front-center surface  108   a  and rear-center surface  108   b . In terms of the vertical direction, the rear-center surface  24   b  is positioned higher than the front-center surface  24   a . The duct  200  is made up of front-center surface  24   a , rear-center surface  24   b , front-center surface  108   a , rear-center surface  108   b , top-rear surface  22   a , and top-rear surface  22   b.    
         [0038]    The above-described structural arrangement in this embodiment can also position the rear opening of the duct  200  higher than the front opening  201  of the duct  200 , like the structural arrangement in the first embodiment. Thus, it is possible to enable the water vapor discharge passage to discharge the water vapor from the apparatus main assembly  10  not only from the front side of the apparatus (direction indicated by arrow mark A), but also, from the rear side of the apparatus main assembly (direction indicated by arrow mark B). Therefore, it is possible to highly efficiently discharge the water vapor from the space between the original reading device  100  and main assembly  10  of the image forming apparatus  1000 , and therefore, to prevent the water vapor from condensing on the bottom surface of the original reading device  100 , without increasing the image forming apparatus  1000  in size, and also, altering the apparatus main assembly  10  in frontal appearance. 
       Embodiment 3 
       [0039]    Next, the image forming apparatus in the third embodiment of the present invention is described with reference to the appended drawings. The components, portions thereof, etc., of the image forming apparatus in this embodiment, which are the same in description as the counterparts in the first embodiment are given the same referential codes as those given to the counterparts, and are not described here.  FIG. 10  is a sectional view of the original reading device  100  and main assembly  10  of the image forming apparatus in this embodiment, and shows the positional relationship between the original reading device  100  and apparatus main assembly  10 . 
         [0040]    Referring to  FIG. 10 , the image forming apparatus in this embodiment is provided with a slanted surface  108 , which replaces the rear-center surfaces  108   a  and  108   b  in the first embodiment. The slanted surface  108  is positioned below the center portion of the carriage cover section  106 , and is sandwiched between the rear-top surfaces  22   a  and  22   b . Further, the slanted surface  108  is positioned so that it directly faces the slanted surface  24 . It is slanted so that its front portion, which is in the adjacencies of the sheet discharge opening  16  is positioned lower, in terms of the vertical direction, than its rear portion (upstream portion in terms of sheet discharge direction E). The duct  200  is made up of the slanted surface  24 , slanted surface  108 , rear-top surface  22   a , and rear-top surface  22   b.    
         [0041]    The above-described structural arrangement in this embodiment can also position the rear opening of the duct  200  higher, in terms of the vertical direction, than the front opening  201  of the duct  200 , like the structural arrangement in the first embodiment. Thus, it is possible to structure the water vapor discharge passage so that the water vapor is discharged not only from the front side of the apparatus main assembly  10  (direction indicated by arrow mark A), but also, from the rear side of the apparatus main assembly  10  (direction indicated by arrow mark B). Therefore, it is possible to highly efficiently discharge the water vapor from the space between the main assembly and original reading device  100  of the image forming apparatus  1000 , and therefore, to prevent the water vapor from condensing on the bottom surface of the original reading device  100 , without increasing the image forming apparatus  1000  in size, and also, altering in appearance the front side of the image forming apparatus  1000 . 
       Embodiment 4 
       [0042]    Next, the image forming apparatus in the fourth embodiment of the present invention is described with reference to the appended drawings. The components, portions thereof, etc., of the image forming apparatus in this embodiment, which are the same in description as the counterparts in the first to third embodiments, are given the same referential codes as those given to the counterparts, one for one, and are not described here.  FIG. 11  is a sectional view of the combination of the apparatus main assembly  10  and original reading device  100  of the image forming apparatus in the fourth embodiment, and shows the positional relationship between the original reading device  100  and apparatus main assembly  10 . 
         [0043]    Referring to  FIG. 11 , the image forming apparatus in this embodiment is provided with front-center surfaces  24   a  and  24   b , which are similar to the front-center surfaces  24   a  and  24   b  in the first embodiment, instead of the slanted surface  24  in the first embodiment. Further, it is provided with a slanted surface  108 , which is similar to the slanted surface  108  in the third embodiment, instead of the surfaces similar to the front-center surfaces  108   a  and  108   b  in the first embodiment. The duct  200  is made up of the front-center surfaces  24   a , rear-center surface  24   b , slanted surface  108 , rear-top surface  22   a , and rear top surface  22   b.    
         [0044]    The structural arrangement in this embodiment described above can also position the rear opening  202  of the duct  200  higher, in terms of the vertical direction, than the front opening  201  of the duct  200 . Therefore, not only is it possible to structure the water vapor discharge passage so that the water vapor is discharged from the front side of the apparatus main assembly  10  (direction indicated by arrow mark A), but also, from the rear side of the apparatus main assembly  10  (direction indicated by arrow mark B). Therefore, it is possible to highly efficiently discharge the water vapor from the space between the apparatus main assembly  10  and original reading device  100  of the image forming apparatus  1000 , and therefore, to prevent the water vapor from condensing on the bottom surface of the original reading device  100 , without increasing the image forming apparatus  1000  in size, and altering the image forming apparatus  1000  in frontal appearance. 
       Embodiment 5 
       [0045]    Next, the image forming apparatus in the fifth embodiment of the present invention is described with reference to the appended drawings. The components, portions thereof, etc., of the image forming apparatus in this embodiment, which are the same in description as the counterparts in the first to third embodiments are given the same referential codes as those given to the counterparts, one for one, and are not described here.  FIG. 12  is a sectional view of the combination of the original reading device  100  and apparatus main assembly  10  of the image forming apparatus in this embodiment, and shows the positional relationship between the original reading device  100  and apparatus main assembly  10 . 
         [0046]    Referring to  FIG. 12 , the image forming apparatus in this embodiment is provided with a horizontal surface  24   c , unlike the image forming apparatus in the first embodiment, which is provided with slanted surface  24 . The duct  200  is made up of the horizontal surface  24   c , front-center surface  108   a , rear-center surface  108   b , rear-top surface  22   a , and rear-top surface  22   b.    
         [0047]      FIG. 13  is a drawing which shows the relationship among the duct entrance height C (height of front entrance  201  of duct  200 ), volume (amount) by which air flows into the duct  200 , and which is calculated through thermal fluid dynamics simulation, and product height (height of image forming apparatus  1000 ). As is evident from  FIG. 13 , by setting the duct entrance height C to a value in a range of 10-20 mm, it is possible to reduce the apparatus in height, while ensuring that air flows into the duct  200  by a sufficient amount. 
         [0048]    The structural arrangement in this embodiment described above can also structure the water vapor discharge passage so that the water vapor is discharged from the front side of the apparatus main assembly  10  (direction indicated by arrow mark A), but also, from the rear side of the apparatus main assembly  10  (direction indicated by arrow mark B). Therefore, it is possible to highly efficiently discharge the water vapor from the space between the apparatus main assembly  10  and original reading device  100  of the image forming apparatus  1000 , and therefore, to prevent the water vapor from condensing on the bottom surface of the original reading device  100 , without increasing the image forming apparatus  1000  in size, and altering the image forming apparatus  1000  in frontal appearance. 
         [0049]    While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
         [0050]    This application claims priority from Japanese Patent Application No. 012427/2014 filed Jan. 27, 2014, which is hereby incorporated by reference.