Patent Publication Number: US-9851678-B2

Title: Blowing device, holder for blowing device, sheet discharge device, and image forming apparatus

Description:
CROSS REFERENCE 
     This Nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2013-242344 filed in Japan on Nov. 22, 2013, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a blowing device that suctions gas from a suction inlet of a blowing portion and exhausts the gas from an exhaust outlet, to a holder that configures a part of the blowing device, to a sheet discharge device equipped with the blowing device near a sheet discharge port to a sheet discharge tray, and to an electrophotographic image forming apparatus equipped with the blowing device between a fixing portion and a sheet discharge portion. 
     An electrophotographic image forming apparatus, after heating and pressurizing at a fixing portion a sheet of paper bearing a toner image transferred to the sheet of paper, discharges the sheet of paper to a sheet discharge tray. During continuous image formation with respect to a large number of sheets of paper, the large number of sheets of paper heated at the fixing portion are stacked and stored on the sheet discharge tray, so that each of the sheets of paper is held between other upper and lower sheets of paper on the sheet discharge tray and is likely to be left in a high temperature. 
     In particular, in a so called in-body sheet discharge type image forming apparatus in which a sheet discharge tray is arranged between an image reading portion and a sheet storage portion, heat dissipation of the sheets of paper is insufficient, and, during continuous image formation, a large number of sheets of paper are stacked and stored on the sheet discharge tray while being still in a high temperature. As a result, due to addition of the weight of upper sheets of paper, a toner image is retransferred onto a sheet of paper of which the upper surface contacts the sheet of paper bearing the toner image, which causes degradation of image quality and stain of the sheet of paper. 
     In view of the foregoing, some conventional image forming apparatuses include a blowing device arranged at a discharge port to a sheet discharge tray and are configured to cool the sheets of paper discharged to the sheet discharge tray by applying air to the sheets of paper. The sheets of paper heated at the fixing portion are cooled down by blowing air before the sheets of paper are stored on the sheet discharge tray, and a large number of sheets of paper are prevented during continuous image formation from being stacked and stored on the sheet discharge tray while being still in a high temperature, which thus can prevent degradation of image quality and stain of a sheet of paper. 
     In the image forming apparatus, a reduction in size has been strongly requested, a space between the fixing portion and the sheet discharge port is narrow, and therefore a blowing device needs to be configured in a small size. Thus, for example, in a configuration disclosed in Japanese Patent Laid-Open Publication No. 2000-297783, a sirocco fan is used, the sirocco fan being equipped with a cylindrical casing; and a dish including a number of fins that are annularly raised on the peripheral edge portion of the disk. The sirocco fan, by rotation of the disk in the casing, discharges gas suctioned into the casing in the axial direction of the casing, from an exhaust outlet formed on the peripheral surface of the casing to the outside. The lengths of the casing and the fin in the axial direction are formed short and a motor that supplies a rotational force to the disk is arranged inside the fin, and a blowing device can thereby be formed small. 
     However, since such a blowing device applied to an image forming apparatus for the purpose of cooling of a sheet of paper to be discharged to a sheet discharge tray is arranged close to a high-temperature fixing portion, the blowing device itself is affected by the heat from the fixing portion, which makes the cooling of a sheet of paper insufficient and causes modification or breakage of each portion, failure of a motor, or the like. In particular, if a motor as a heat generating source as well is arranged inside a fin, an internal temperature will further easily rise during continuous use. 
     The occurrence of these problems such as rise in blowing temperature, breakage, and failure is not limited to a case in which a blowing device is applied to an image forming apparatus but a general problem in the blowing device used in a comparatively high temperature environment. 
     An object of the present invention is to provide a blowing device capable of suppressing temperature rise in the blowing device and preventing occurrence of rise in blowing temperature, breakage, and the like, by leading part of the gas exhausted from the blowing device to the inside of the blowing device. Another object of the present invention is to provide a sheet discharge device capable of sufficiently cooling a sheet of paper discharged to a sheet discharge tray by applying this blowing device, and to provide an image forming apparatus capable of thereby continuously preventing degradation of image quality or stain of a sheet of paper during continuous image formation. 
     SUMMARY OF THE INVENTION 
     A blowing device according to preferred embodiments of the present invention is equipped with a blowing portion and a holder. The blowing portion has a cylindrical body that stores a rotating body, and includes: a suction inlet arranged on a side surface perpendicular to the axial direction of the cylindrical body; and an exhaust outlet arranged on a part of the peripheral surface of the cylindrical body. The holder has a wall that faces the peripheral surface of the blowing portion with a gap between the wall and the peripheral surface, and holds the blowing portion inside. The holder includes: a suction portion that communicates with the suction inlet; and an exhaust portion that causes the exhaust outlet to communicate with the outside and the gap. 
     A holder for a blowing device according to preferred embodiments of the present invention has a wall that faces the peripheral surface of the blowing portion with a gap between the wall and the peripheral surface, holds the blowing portion inside, and includes: a suction portion that communicates with a suction inlet; and an exhaust portion that causes an exhaust outlet to communicate with the outside and the gap. 
     A sheet discharge device and an image forming apparatus according to preferred embodiments of the present invention include the blowing device with any of the above described configurations, the blowing device being arranged so that the exhaust portion is exposed at a sheet discharge port for discharging a sheet of paper to a sheet discharge tray. 
     The foregoing and other features and attendant advantages of the present invention, will become more apparent from the reading or the following detailed description of the invention in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an image forming apparatus equipped with a blowing device according to a preferred embodiment of the present invention. 
         FIG. 2A  is an external view showing a blowing device as viewed from an upper side according to a first preferred embodiment of the present invention, and  FIG. 2B  is an external view showing the blowing device as viewed from a lower side. 
         FIG. 3  is a sectional side elevational view of the blowing device. 
         FIG. 4  is a bottom view of the blowing device. 
         FIG. 5  is a bottom view of a blowing device according to a second preferred embodiment of the present invention. 
         FIG. 6  is a bottom view of a blowing device according to a third preferred embodiment of the present invention. 
         FIG. 7  is a bottom view of a blowing device according to a fourth preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, a blowing device according to preferred embodiments of the present invention, and an image forming apparatus incorporating the blowing device will be described with reference to the attached drawings. 
     As shown an  FIG. 1 , an image forming apparatus  100  incorporating a blowing device  10  according to preferred embodiments of the present invention is configured to form a polychrome or monochrome image on a sheet of paper by electrophotographic image formation. The image forming apparatus  100  is equipped with a document reading portion  110 , a paper supply portion  120 , an image forming portion  130 , and a sheet discharge tray  140 , and, after forming an image on one side or both sides of a sheet of paper in the image forming portion  130 , the sheet of paper being supplied from the paper supply portion  120 , discharges the sheet of paper to the sheet discharge tray  140 . 
     The image forming portion  130  is equipped with a transfer portion  131  that transfers a toner image onto a sheet of paper, and a fixing portion  132  that heats and pressurizes the sheet of paper that has passed the transfer portion  131 . The sheet of paper is heated in the fixing portion  132 , and is discharged to the sheet discharge tray  140  in a state in which the toner image is fixed onto the surface of the sheet of paper. 
     The sheet discharge tray  140  is arranged vertically between the document reading portion  110  and the image forming portion  130  and forms a so called in-body sheet discharge portion. The sheet of paper discharged to the in-body sheet discharge portion after being heated in the fixing portion  132  is inferior in heat dissipation as compared with a case in which a sheet of paper is discharged to a sheet discharge portion exposed to the side face of a device. During continuous image formation, a large number of sheets of paper that are still not cooled down sufficiently are stacked and stored on the sheet discharge tray  140 , so that a toner image on a sheet of paper positioned in the middle is retransferred onto other sheets of paper that contact the upper side of the sheet of paper, which is likely to cause degradation of image quality and stain of the sheet of paper. 
     Therefore, the image forming apparatus  100  includes the blowing device  10  being arranged close to a sheet discharge port  141  above the sheet discharge tray  140  and exhausting air. 
     As shown in  FIG. 2A  and  FIG. 2B , a blowing device  10  according to a first preferred embodiment of the present invention includes a blowing portion  1  and a holder  2 . The blowing portion  1 , as an example, is formed of a sirocco fan, and includes: a suction inlet  12  arranged on a side surface perpendicular to the axial direction of a casing  11  as a cylindrical body according to the present invention; and also an exhaust outlet  14  arranged on a part of the peripheral surface  13  of the cylindrical body. 
     The holder  2  for a blowing device includes four walls  21 A to  21 D that face the peripheral surface  13  of the casing  11  with a gap  20  between the walls and the peripheral surface and holds the blowing portion  1  inside. The holder  2  includes: a suction portion  22  that communicates with the suction inlet  12 ; and an exhaust portion  23  that causes the exhaust outlet  14  to communicate with the outside and the gap  20 . The blowing portion  1  is fixed to the holder  2  by a screw  8  engaged from the side of the bottom face of the holder  2 , the bottom face being open to the outside. 
     As shown in  FIG. 3 , the blowing portion  1  includes a cylindrical casing  11 ; and a disk  16  (that is equivalent to a rotating body of the present invention) having a number of fins  15  that are annularly raised on the peripheral edge portion of the disk, and, by rotation of the disk  16  in the casing  11 , discharges outside air suctioned from the suction inlet  12  into the casing  11  in the axial direction of the casing  11 , from the exhaust outlet  14  formed on the peripheral surface of the casing  11  to the outside. It is to be noted that the casing  11 , in the central portion inside, stores a motor  17  for supplying a rotational force to the disk. The motor  17  receives supply of power via a cable  18 . 
     When the disk of the blowing portion  1  is rotated, the outside air is suctioned from the suction portion  22  of the holder  2  into the blowing portion  1  by way of the suction inlet  12  of the blowing portion  1 , and is then exhausted from the exhaust outlet  14  of the blowing portion  1 . The air discharged from the exhaust outlet  14  is exhausted toward the sheet discharge tray  140  mainly by way of the exhaust portion  23  of the holder  2 . The sheet of paper that has passed the fixing portion  132  is cooled down by the air exhausted from the exhaust portion  23  of the holder  2  while being discharged toward the sheet discharge tray  140 . 
     As shown in  FIG. 4 , the holder  2  of the blowing device  10  may be equipped with a branch portion  4  in the exhaust portion  23 . The branch portion  4  is composed of an inclined surface that extends from an edge portion of exhaust portion  23  and faces a part of the exhaust outlet  14  of the blowing portion  1 , and leads part of air exhausted from the exhaust outlet  14  to the gap  20  through the opening  21 . The air led to the gap  20  passes through the inside of the gap  20  while contacting the peripheral surface of the casing  11 . This makes it possible to cool the blowing portion  1  down through the peripheral surface of the casing  11 . The holder  2  has a bottom face that is open outward, which allows air that reaches the end of the gap  20  to be emitted from below to the outside of the blowing device  10 . 
     The blowing device  10 , because being arranged above the fixing portion  140  in the image forming apparatus  100 , is affected by the heat generated in the fixing portion  140 . During continuous image formation, the temperature of the blowing portion  1  may rise in combination with heat generation of the motor  17  and may cause modification and breakage of each portion, and a failure of the motor. 
     The air exhausted from the blowing portion  1  cools the blowing portion  1  itself down, which can reduce the temperature rise of the blowing portion  1 , prevent occurrence of breakage or a failure, and reliably continue cooling sheets of paper by the blowing device  10  even during continuous image formation. 
     It should be noted that two branch portions  4  are arranged across the exhaust outlet  14  so as to lead the part of the air exhausted from the exhaust outlet  14 , from the opposite sides of the casing  11  into the gap  20 . 
     As shown in  FIG. 5 , a blowing device  101  according to a second preferred embodiment of the present invention may include a flow path  5  in which air flows along the periphery of a blowing portion  1 , in a gap  20 . Other configurations are the same as the configuration of the blowing device  10 . The flow path  5  may be equipped with a plurality of openings  51  on a part of the wall on the side of the blowing portion  1 . With this configuration, the part of the air exhausted from the exhaust outlet  14  can be reliably led to the periphery of the casing  11 . In addition, the openings  51  are formed in a portion in the blowing portion  1 , required to be especially cooled down, which can thereby improve the cooling property of the blowing portion  1 . 
     As shown in  FIG. 6 , a blowing device  102  according to a third preferred embodiment of the present invention may include a flow path  5  of which the opposite ends are open to an exhaust outlet  14 . Other configurations are the same as the configuration of the blowing device  101 . The part of air exhausted from the exhaust outlet  14  can be reliably led from the opposite sides of the casing  11  into the gap  20 . 
     It is to be noted that in the blowing devices  101  and  102 , the flow path  5  can be formed of a closed cross sectional shaped pipe that is closed except an end portion of the flow path on the side of the exhaust outlet  14  and the openings  51 . Moreover, a part or the whole of the upper face and the bottom face may be open outward. 
     As shown in  FIG. 7 , a blowing device  103  according to a fourth preferred embodiment of the present invention may include a blowing portion  1  formed with a first exhaust outlet  14 A that communicates only with an exhaust portion  23  of a holder  2 , and a second exhaust outlet  14 B that communicates only with a gap  20 . Other configurations are the same as the configuration of the blowing device  10 . 
     Air exhausted from the first exhaust outlet  14 A can reliably cool down a sheet of paper discharged to the sheet discharge tray  140 , and air exhausted from the second exhaust outlet  14 B can reliably cool the blowing portion  1  down. It should be noted that the opening area of the first exhaust outlet  14 A and the second exhaust outlet  14 B can be appropriately determined based on the ratio of the amount of air required for cooling of a sheet of paper to the amount of air required for cooling of the blowing portion  1 . 
     In addition, as other preferred embodiments, a branch portion  4  of the blowing device  10  may be configured to make it possible to selectively open and close between an exhaust outlet  14  and a gap  20 , and, only when the blowing portion  1  needs to be cooled down, the part of air exhausted from the exhaust outlet  14  may be led to the gap  20 . Furthermore, the amount of air to be led to the gap  20  may be able to be adjusted. 
     It is to be noted that, while, in the above preferred embodiments, cases in which the present invention is applied to the image forming apparatus  100  are described, the present invention is characterized in that a blowing portion is configured to cool itself down by using part of air exhausted from the blowing portion and can be similarly applied to a blowing device that is used in a situation in which the temperature rise of the blowing portion causes a problem. Moreover, the blowing portion  1  is not limited to a blowing portion configured with a sirocco fan. Furthermore, for example, the present invention can be similarly applied to a sheet discharge device such as a post-processing device, which is selectively fitted on an image forming apparatus. Additionally, the present invention can be also similarly applied to gas other than air. 
     The foregoing preferred embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the following claims, not by the foregoing preferred embodiments. Further, the scope of the present invention is intended to include the scopes of the claims and all possible changes and modifications within the senses and scopes of equivalents.