Patent Publication Number: US-8989615-B2

Title: Image forming apparatus

Description:
INCORPORATION BY REFERENCE 
     This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2012-258971 filed on Nov. 27, 2012, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to an image forming apparatus including a mechanism of blowing air to a conveyance path on which a sheet passing through a fixing device is conveyed to a sheet discharge port. 
     An image forming apparatus such as a facsimile apparatus, a copy machine, a printer, or a multifunction peripheral having functions of these apparatuses includes a fixing device. The fixing device includes a heating device, and applies heat to a print sheet when the print sheet passes through the fixing device. Thus, an image is formed on the print sheet passing through the fixing device. The print sheet passing through the fixing device is discharged onto an external tray from a sheet discharge port. 
     In the image forming apparatus of this type, the sheet heated to a high temperature is conveyed on the conveyance path, while releasing heat, but in some cases, the sheet is discharged without a heat decrease. In this case, melted toner is not completely solidified, so that the toner might be transferred onto another sheet stacked on a tray, or the discharged print sheet might be adhered to another print sheet. On the other hand, a fixing device or an image forming apparatus that cools a sheet heated to a high temperature with a cooling fan or the like is disclosed. 
     However, in this fixing device, since air is vertically blown to a front surface of a print sheet, air blown to the print sheet flows toward the fixing device, resulting in that the heating device in the fixing device might also be cooled. Moreover, the print sheet is curled up from a guide by the flow of air flown into the fixing device, which hinders the conveyance of the print sheet, and in addition to this, a problem of jam of the print sheet might arise in some cases. In an image forming apparatus having a configuration of blowing air to a print sheet discharged from a sheet discharge port, air is not flown toward the fixing device. However, toner on the print sheet passing through the fixing device might be deposited onto a guide on a conveyance path. The print sheet is made of plant fiber as a main material, so that it has a property of easily retaining water. Therefore, when the print sheet is heated to a high temperature by the fixing device, water in the print sheet evaporates, and stays on the conveyance path in some cases. In this case, in the image forming apparatus having a configuration of not blowing air to the conveyance path, dew condensation occurs on the conveyance path, resulting in that the print sheet might become wet. 
     SUMMARY 
     An image forming apparatus according to one aspect of the present disclosure includes a blowing portion and an air guide portion. The blowing portion blows air to a conveyance path of a sheet from a fixing device to a sheet discharge port. The air guide portion guides air blown from the blowing portion toward the downstream side in a sheet conveyance direction toward the sheet discharge port on the conveyance path. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description with reference where appropriate to the accompanying drawings. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing the configuration of the appearance of an image forming apparatus according to an embodiment of the present disclosure. 
         FIGS. 2A and 2B  are sectional views showing the configuration of the image forming apparatus shown in  FIG. 1 , wherein  FIG. 2A  is a schematic sectional view, and  FIG. 2B  is a detailed sectional view. 
         FIG. 3  is a block diagram showing the configuration of a control portion provided to the image forming apparatus shown in  FIG. 1 . 
         FIG. 4A  is a perspective view showing the image forming apparatus from which a top cover is removed, and  FIG. 4B  is a perspective view showing the image forming apparatus from which the top cover and a back cover are removed. 
         FIG. 5  is a perspective view of the configuration of a periphery of a blowing mechanism provided to the image forming apparatus shown in  FIG. 1 . 
         FIG. 6  is an enlarged perspective view showing the configuration of an air duct provided to the blowing mechanism shown in  FIG. 5 . 
         FIG. 7  is a partial sectional view showing the configuration of the periphery of the blowing mechanism provided to the image forming apparatus shown in  FIG. 1 . 
         FIG. 8  is a partial enlarged view showing the configuration of the periphery of the blowing mechanism provided to the image forming apparatus shown in  FIG. 1 . 
         FIG. 9  is a flowchart showing one example of the procedure of a fan drive control executed by the control portion in the image forming apparatus shown in  FIG. 1 . 
         FIG. 10  is a view showing a selection screen for a document size in a reading condition in a display screen scan mode according to the embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present disclosure will be described in detail based on the drawings. It is noted that the embodiments described below are merely embodied examples of the present disclosure, and the embodiments of the present disclosure can be modified as appropriate within a range not changing the gist of the present disclosure. 
     In the description below, an up-down direction  6  is defined with reference to the state (state in  FIG. 1 ) in which an image forming apparatus  10  is placed so as to be usable, a front-back direction  7  is defined such that the near side (front side) is front, and a right-left direction  8  is defined such that the image forming apparatus  1  is viewed from the near side (front side). 
     [Configuration of Image Forming Apparatus  10 ] 
     As shown in  FIG. 1 , the image forming apparatus  10  is a multifunction peripheral. 
     As shown in  FIGS. 1 and 2 , the image forming apparatus  10  includes an image forming portion  18  of electrophotographic type, a fixing portion  19 , a sheet feed device  15 , a blowing mechanism  60 , a control portion  90  (see  FIG. 3 ) that performs overall control for the image forming apparatus  10 , and a sheet discharge portion  21 . These components are provided inside a housing  14  forming an outer cover and an inner frame of the image forming apparatus  10 . 
     As shown in  FIG. 2 , the sheet feed device  15  is provided at the lowermost portion of the image forming apparatus  10 . The sheet feed device  15  includes a sheet feed tray  50 , a pickup roller  51 , and a sheet feed roller  52 . In the sheet feed tray  50 , print sheets on which an image is to be formed by the image forming portion  18  are stacked. The sheet feed tray  50  is supported by the housing  14 . The pickup roller  51  and the sheet feed roller  52  are provided on the front side above the sheet feed tray  50 . When an instruction to start a feeding operation of a print sheet is inputted to the image forming apparatus  10 , the pickup roller  51  is rotationally driven by a conveyance motor  56  (see  FIG. 3 ), whereby the print sheet is fed from the sheet feed tray  50 . The print sheet fed by the pickup roller  51  is conveyed downstream in the feeding direction by the sheet feed roller  52 . 
     The image forming portion  18  transfers a toner image onto a print sheet by using a print material such as a toner. Specifically, as shown in  FIG. 2 , the image forming portion  18  includes a photosensitive drum  31 , a charging portion  32 , a developing portion  33 , a transfer portion  35 , a cleaning portion  36 , and an LSU (Laser Scanning Unit)  34 . The photosensitive drum  31  is an example of a member to be scanned of the present disclosure. The LSU  34  is an example of a scanning device of the present disclosure. When an image forming operation is started, the surface of the photosensitive drum  31  is charged to have a uniform potential by the charging portion  32 . The photosensitive drum  31  from the LSU  34  is scanned with laser beam according to image data. Thus, an electrostatic latent image is formed on the photosensitive drum  31 . Thereafter, toners are deposited onto the electrostatic latent image by the developing portion  33 , whereby a toner image is developed on the photosensitive drum  31 . The toner image is transferred onto a print sheet fed from the sheet feed tray  50 , by the transfer portion  35 . The print sheet having the toner image transferred thereon is fed onto a conveyance path  27  formed from the image forming portion  18  to the fixing portion  19 , and is conveyed to the fixing portion  19  provided on the downstream side (that is, the back side) from the image forming portion  18  in the conveyance direction. 
     The fixing portion  19  fixes a toner image transferred onto a print sheet onto the print sheet by heat, and includes a heat roller  41  and a pressure roller  42 . The heat roller  41  is heated to a high temperature by the heating device such as an IH heater during a fixing operation. When a print sheet passes through the fixing portion  19 , toner is heated and melted by the fixing portion  19 . Thus, the toner image is fixed onto the print sheet, whereby an image is formed onto the print sheet. 
     A conveyance path  28  is formed on the downstream side from the fixing portion  19  in the conveyance direction. The conveyance path  28  is an example of a conveyance path of the present disclosure. The sheet discharge port  22  from which a print sheet is discharged is provided on an end of the conveyance path  28 . Specifically, the conveyance path  28  is formed from the fixing portion  19  to the sheet discharge port  22 . The print sheet having an image fixed thereon by the fixing portion  19  is conveyed to the conveyance path  28 . The conveyance path  28  is curved upward from the fixing portion  19 , and then, extends in the vertical direction. Plural sheet discharge rollers  23  that are rotated bidirectionally by a sheet discharge motor  57  (see  FIG. 3 ) are provided on the conveyance path  28 . The print sheet conveyed onto the conveyance path  28  is conveyed upward through the conveyance path  28  by the sheet discharge rollers  23  that are normally rotated by the sheet discharge motor  57 , and discharged onto the sheet discharge portion  21  provided on the top face of the image forming apparatus  10 , from the sheet discharge port  22 . 
     In the image forming apparatus  10 , when an image is formed on both sides of a print sheet, the print sheet passing through the fixing portion  19  and having formed an image on one side is turned over, and is again conveyed to the fixing portion  19  from the upstream side in the conveyance direction. More specifically, the sheet discharge rollers  23  are stopped with the lead end portion of the print sheet having the image formed on one side being exposed to the outside from the sheet discharge port  22 . In this case, the print sheet is held such that the trailing end of the print sheet is nipped by the sheet discharge rollers  23 . Then, the sheet discharge rollers  23  are reversely rotated by the sheet discharge motor  57  (see  FIG. 3 ), whereby the print sheet is again conveyed on the conveyance path  28  to the fixing portion  19 . In other words, the print sheet is fed backward on the conveyance path  28 . As shown in  FIG. 2 , the image forming apparatus  10  is provided with a reverse conveyance path  29  that is branched from the conveyance path  28  and joins the upstream side of the image forming portion  18 . The print sheet fed backward on the conveyance path  28  is guided to the reverse conveyance path  29  by a flap not shown. Plural conveyance rollers  44  are mounted on the reverse conveyance path  29 , and the print sheet is again conveyed to the image forming portion  18  from the upstream side in the conveyance direction through the reverse conveyance path  29  by the conveyance rollers  44 . The print sheet reaching the image forming portion  18  passes through the image forming portion  18  and the fixing portion  19 , whereby an image is formed on the reverse side on which the image is not formed. Thereafter, the print sheet having the image formed on both sides is discharged to the sheet discharge portion  21  from the sheet discharge port  22  through the conveyance path  28  by the sheet discharge rollers  23  that are returned to have normal rotation. It is to be noted that the reverse conveyance path  29  and the conveyance rollers  44  that allow the print sheet to be reversed and conveyed toward the upstream side of the fixing portion  19  are one example of a reverse conveyance portion of the present disclosure. 
     As described above, the print sheet passing through the fixing portion  19  is heated to a high temperature by the heat roller  41 . The print sheet is cooled to some extent during the process of the conveyance through the conveyance path  28 , but in some cases, the print sheet is discharged from the sheet discharge port  22  with the melted toner being not completely solidified. In this case, the melted toner might be transferred onto another print sheet, or the discharged print sheet might be adhered to another print sheet. Since the print sheet is heated to a high temperature, moisture contained in the print sheet evaporates, and the resultant evaporation might stay on the conveyance path  28  and generate dew condensation. The evaporation staying on the conveyance path  28  might be exhausted from the sheet discharge port  22  as white steam. In order to reduce such phenomena, as shown in  FIG. 2 , the blowing mechanism  60  is provided above the fixing portion  19  in the image forming apparatus  10  according to the present embodiment. The blowing mechanism  60  includes a cooling fan  61  that takes in ambient air and blows the air to the conveyance path  28 . The cooling fan  61  is an example of a blowing portion of the present disclosure. The detail of the blowing mechanism  60  will be described later. 
     [Configuration of Control Portion  90 ] 
     The control portion  90  performs overall control of the image forming apparatus  10 . As shown in  FIG. 3 , the control portion  90  is composed of a CPU  91 , a ROM  92 , a RAM  93 , an EEPROM  94 , a motor driver  95 , and the like. The control portion  90  is electrically connected to the conveyance motor  56 , the sheet discharge motor  57 , and the cooling fan  61  via an internal bus, a signal line, or the like. In addition, the control portion  90  performs a fan drive control in accordance with a flowchart shown in  FIG. 8 . The fan drive control is a control to drive or stop the cooling fan  61  in the blowing mechanism  60 . A control program for performing the fan drive control is stored in the ROM  92 . By the control program being executed by the CPU  91 , the fan drive control is performed to control the operation of the cooling fan  61 . The control portion  90  performing the fan drive control is an example of a control portion of the present disclosure. 
     The conveyance motor  56  supplies a driving force that rotationally drives the pickup roller  51 , the sheet feed roller  52 , and the conveyance rollers  44 . As shown in  FIG. 3 , the conveyance motor  56  is connected to the motor driver  95  of the control portion  90 , and drive-controlled by the motor driver  95 . The sheet discharge motor  57  supplies a driving force that rotationally drives the sheet discharge rollers  23 . The sheet discharge motor  57  is connected to the motor driver  95  of the control portion  90 . 
     [Configuration of Blowing Mechanism  60 ] 
     Next, the configuration of the blowing mechanism  60  will be described in detail with reference to  FIGS. 4 to 8 . As shown in  FIG. 4 , the blowing mechanism  60  is mounted on the back side of the image forming apparatus  10 . The blowing mechanism  60  includes the above-mentioned cooling fan  61  and an air duct  66 . The air duct  66  is an example of a branch portion of the present disclosure. In the present embodiment, a sirocco fan (multi-blade fan) is employed as the cooling fan  61 . 
     As shown in  FIG. 7 , the blowing mechanism  60  is arranged above the fixing portion  19  on the back side of the image forming apparatus  10 . A frame  46  extending in the lateral direction is provided between the blowing mechanism  60  and the fixing portion  19 . The frame  46  has a function as a partition wall that separates the blowing mechanism  60  and the fixing portion  19 , and prevents air warmed by the fixing portion  19  from being flown into the blowing mechanism  60 . As shown in  FIG. 5 , the cooling fan  61  of the blowing mechanism  60  is fixed to the frame  46 . Specifically, the cooling fan  61  is fixed to the frame  46  such that the rotational shaft of the cooling fan  61  extends in the vertical direction and a blowing outlet  63  of the cooling fan  61  faces the conveyance path  28 . An air intake port  64  of the cooling fan  61  is arranged on the top surface. 
     As shown in  FIG. 7 , the sheet discharge portion  21  is provided just above the intake port  64  of the cooling fan  61 . The sheet discharge portion  21  serves as a part of a cover that covers the top surface of the image forming apparatus  10 , and the sheet discharge portion  21  and the cooling fan  61  are separated by a support plate  21 A that supports a print sheet at the sheet discharge portion  21 . The LSU  34  is arranged on the back surface of the support plate  21 A with a slight gap  69 . The gap  69  formed between the LSU  34  and the support plate  21 A is widened in the widthwise direction (the right-left direction  8 ) orthogonal to the conveyance direction on the conveyance path  28 , and reaches up to both side faces of the image forming apparatus  10  in the right-left direction  8 . An intake path  70  (see an arrow of a broken line in  FIG. 7 ) of the cooling fan  61  is formed in the gap  69 . In other words, the intake path  70  is formed around the LSU  34 . Specifically, both ends or either one of the ends of the gap  69  in the right-left direction  8  communicate with a through-hole, not shown, formed on the side face of the image forming apparatus  10 , and outside air can be taken into the gap  69  through the through-hole. The gap  69  is widened to the intake port  64  of the cooling fan  61  along the back surface of the support plate  21 A. When the cooling fan  61  is driven, air around the intake port  64  is sucked by the cooling fan  61 , so that the periphery of the intake port  64  has a negative pressure state. With this, outside air is flown into the gap  69  through the through-hole. As a result, the intake path  70  from the through-hole through the periphery of the LSU  34  to the intake port  64  of the cooling fan  61  is formed in the gap  69 . The intake path  70  formed as described above is an example of an intake path of the present disclosure. Since the intake path  70  is formed around the LSU  34  as described above, the ambient air heated to a high temperature by heat generated from a polygon motor provided in the LSU  34  can be circulated by fresh air. Accordingly, not only a print sheet but also the LSU  34  can be cooled. 
     The air duct  66  is to send air, which is blown from the blowing outlet  63  of the cooling fan  61 , to the conveyance path  28 , and is provided between the blowing outlet  63  and the conveyance path  28 . In the present embodiment, the air duct  66  is formed integral with the frame  46 . The air duct  66  allows the air blown from the blowing outlet  63  of the cooling fan  61  to branch into two in the widthwise direction (i.e., in the right-left direction  8 ) orthogonal to the conveyance direction. In detail, as shown in  FIG. 6 , the air duct  66  includes a first duct  66 A that sends air blown from the cooling fan  61  toward the conveyance path  28  in the obliquely left direction, and a second duct  66 B that sends the air toward the conveyance path  28  in the obliquely right direction. A branch point of the first duct  66 A and the second duct  66 B is set on the center of the blowing outlet  63 . With this structure, the air blown from the blowing outlet  63  is sent as being equally distributed to the first duct  66 A and the second duct  66 B respectively. Thus, air can be sent to the entire area in the widthwise direction of a print sheet passing through the conveyance path  28 . Consequently, the entire area of the print sheet in the widthwise direction can be cooled. In addition, evaporation in the entire area of the conveyance path  28  in the widthwise direction can be exhausted. It is to be noted that the present embodiment discloses the air duct  66  that is branched into two in the right-left direction  8 . However, the number of branches is not limited to two, and an air duct  66  that is branched into three or more can also be used. 
     As shown in  FIGS. 7 and 8 , an air guide  62  inclined obliquely upward is provided on the air duct  66 . Specifically, the air guide  62  is provided to each of the first duct  66 A and the second duct  66 B. The air guide  62  is an example of an air guide portion of the present disclosure. The air guide  62  guides the air blown from the blowing outlet  63  of the cooling fan  61  toward the downstream side in the conveyance direction of the print sheet on the conveyance path  28 . The air guide  66  is provided on a back end portion of the air duct  66  (the first duct  66 A and the second duct  66 B). The air guide  62  is inclined obliquely upward to the rear from the end portion of a lower surface of the air duct  66 . With this structure, the airflow of the air blown from the blowing outlet  63  of the cooling fan  61  is deflected obliquely upward by the air guide  62 . Specifically, the air is blown obliquely upward from an outlet of the air duct  66  along an arrow shown in  FIG. 8 . 
     [Fan Drive Control] 
     A procedure of the fan drive control executed by the control portion  90  during an image formation will be described below with reference to the flowchart in  FIG. 9 . S 11 , S 12 , . . . , in  FIG. 9  represent the numbers of steps in the processing procedure. The fan drive control is executed by the control portion  90  in accordance with the procedure, whereby the cooling fan  61  can be driven or stopped. 
     When the image forming apparatus  10  does not perform the image forming operation, the cooling fan  61  is stopped. When an instruction signal for starting the image forming operation is inputted to the image forming apparatus  10  (S 11 ), the control portion  90  drives the cooling fan  61  (S 12 ). As a result, air is blown from the cooling fan  61  toward the conveyance path  28 . The cooling fan  61  may be driven simultaneous with the timing when the instruction of the image formation is inputted. Alternatively, if a sheet sensor for sensing a position of a print sheet is provided on the conveyance path  27 , for example, the cooling fan  61  may be driven when the sheet sensor senses an arrival of a print sheet at the fixing portion  19 . 
     The control portion  90  determines whether or not the image forming instruction indicates an instruction of a duplex printing (S 13 ). When determining that the instruction indicates the duplex printing, the control portion  90  determines whether or not the print sheet passing through the fixing portion  19  is reversed and conveyed (S 14 ), and when determining that the print sheet is reversed and conveyed, the control portion  90  stops the cooling fan  61  (S 15 ). It is to be noted that the control portion  90  can determine that the print sheet is reversed and conveyed when, for example, an instruction of an inverse rotation of the sheet discharge motor  57  is inputted. In the case where the sheet sensor is provided on the reverse conveyance path  29 , the control portion  90  can determine that a print sheet is reversed and conveyed when the sheet sensor senses the print sheet. 
     When determining that the image forming instruction indicates simplex printing in step S 13 , the control portion  90  determines whether or not the print sheet is discharged to the sheet discharge portion  21  (S 16 ). When determining that the print sheet is discharged to the sheet discharge portion  21 , the control portion  90  stops the cooling fan  61  (S 15 ). It is to be noted that, when the instruction of driving the sheet discharge motor  57  is lost, the control portion  90  can determine that the image forming operation is ended with the print sheet being discharged onto the sheet discharge portion  21 , for example. 
     [Operation and Effect of Embodiment] 
     Since the blowing mechanism  60  is provided to the image forming apparatus  10  as described above, air blown from the cooling fan  61  is sent to the conveyance path  28  through the air duct  66 . The air guide  62  is provided to the air duct  66 , whereby air flown into the conveyance path  28  from the air duct  66  is guided obliquely upward by the air guide  62  as indicated by the arrow in  FIG. 8 . As a result, a print sheet heated to a high temperature by the fixing portion  19  can efficiently be cooled. Since air is sent toward the sheet discharge port  22 , there is no chance that the fixing portion  19  is cooled by blowing air. The evaporation generated from a print sheet due to an application of heat from the fixing portion  19  is forcibly exhausted from the sheet discharge port  22  by the air blown from the cooling fan  61 , which prevents not only the stay of the evaporation on the conveyance path  28  but also the occurrence of dew condensation caused by the evaporation. The evaporation is forced to be quickly exhausted, which prevents the evaporation from appearing as white steam from the sheet discharge port  22 . Although the embodiment described above discloses the air guide  62  mounted on the air duct  66 , the air guide  62  may be mounted on the blowing outlet  63  of the cooling fan  61 . 
     The image forming apparatus  10  has the conveyance path  28  extending in the vertical direction, so that evaporation is easy to stay on the conveyance path  28 . However, the image forming apparatus  10  thus configured includes the blowing mechanism  60 , whereby cooling of a print sheet and exhaust of steam can smoothly be performed. 
     When the operation of forming an image on both sides of a print sheet is performed, the cooling fan  61  is driven only when the image is formed on one side, and during the operation of forming the image on the other side, the cooling fan  61  is stopped. This is because moisture is eliminated from the print sheet that has passed through the fixing portion  19  during the simplex printing, and further, because the heating temperature (control temperature) by the heat roller  41  in the fixing portion  19  is set low. Because of these reasons, it is unnecessary to execute the cooling by the cooling fan  61  and to exhaust evaporation. In this case, the cooling fan  61  is stopped during the operation of forming an image on the other side, whereby electric power consumption can be reduced. 
     [Other Embodiment] 
     The embodiment described above discloses the air duct  66  formed integral with the frame  46 . However, as shown in  FIG. 10 , an embodiment in which a deflection plate  76  that is supported to be swingable to the frame  46  (see  FIG. 8 ) is provided instead of the air duct  66  can be employed. The deflection plate  76  changes the direction of the air blown from the cooling fan  61  to the right or left direction, and it can swing in the widthwise direction (right-left direction  8 ) orthogonal to the conveyance direction of the conveyance path  28  about a swing shaft  77  vertical to the frame  46 . The air guide  62  is not mounted to the deflection plate  76 . Therefore, in this case, the air guide  62  is provided on the blowing outlet  63  of the cooling fan  61 . 
     In such configuration, when the swing orientation of the deflection plate  76  is deflected to set the deflection plate  76  on any position, the blowing range of the air blown from the cooling fan  61  can optionally be changed. As one example of an orientation changing portion of the present disclosure, an operation lever is provided to the image forming apparatus  10 , and a drive transmission mechanism that swings the deflection plate  76  at an angle according to an operation amount of the operation lever is coupled to the swing shaft  77 . With this configuration, the orientation of the deflection plate  76  can be changed to change the position of the deflection plate  76  to any position without allowing the inside of the image forming apparatus  10  to be open. Accordingly, when a print sheet is conveyed, air can be sent to a range according to the size of the print sheet in the widthwise direction by swinging the deflection plate  76 , for example. 
     In the case where the image forming apparatus  10  includes a drive source such as a motor coupled to the drive transmission mechanism or a sensing portion for sensing a size of a print sheet on which an image is to be formed, it is conceivable that the control portion  90  drives the motor to change the position of the deflection plate  76  in order to generate the blowing range according to the size of the print sheet. In this case, when a print sheet having a large size in the widthwise direction is conveyed, the blowing range can automatically be increased, and when a print sheet having a small size in the widthwise direction is conveyed, the blowing range can automatically be decreased. It is to be noted that, in this case, the drive source, the sensing portion, and the control portion  90  are an example of the orientation changing portion of the present disclosure. 
     It is to be understood that the embodiments herein are illustrative and not restrictive, since the scope of the disclosure is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.