Patent Publication Number: US-10324403-B2

Title: Image forming apparatus containing fixing member, blowing section, and hardware processor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The entire disclosure of Japanese patent Application No. 2017-039521, filed on Mar. 2, 2017, is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Technological Field 
     The present invention relates to an image forming apparatus. 
     Description of Related Art 
     In general, an electrophotographic image forming apparatus (such as a printer, a copier, or a fax machine) is configured to irradiate (expose) a charged photoconductor drum (image bearing member) with (to) laser light based on image data to form an electrostatic latent image on the surface of the photoconductor. The electrostatic latent image is then visualized by supplying toner from a developing device to the photoconductor drum on which the electrostatic latent image is formed, whereby a toner image is formed. Further, the toner image is directly or indirectly transferred to a sheet, and then heat and pressure are applied to the sheet at a fixing nip to form a toner image on the sheet. 
     In the meantime, in a non-sheet-passing region of the fixing nip within which no sheet is passed through, there is no possibility that a sheet passing through the fixing nip takes away heat, so that a problem arises in that the temperature in the non-sheet-passing region in a fixing section rises. This problem arises when sheets of a size smaller than that of a sheet having the maximum width allowing the sheet to pass through in the fixing section are passed through consecutively one by one. 
     For example, Japanese Patent Application Laid-Open No. 2012-234067 discloses a configuration in which a cooling fan is provided in order to solve this problem. In this configuration, a non-sheet-passing portion of a fixing section is cooled with the cooling fan depending on a sheet size. 
     SUMMARY 
     However, in the case of a configuration in which a fixing section is provided with a separating section for generating airflow for separating a sheet from a fixing member, there has been a problem in that an image forming apparatus is made oversize when a cooling fan for cooling a non-sheet-passing region in the fixing section is provided in the fixing section in addition to the separating section. 
     An object of the present invention is to provide an image forming apparatus in which a temperature rise in the non-sheet-passing region in the fixing section can be prevented without the image forming apparatus being made oversize in a configuration in which the image forming apparatus is provided with a separating section. 
     An image forming apparatus in which one aspect of the present invention is reflected in an attempt to at least partly achieve the above-mentioned object includes: a rotatable fixer that forms a fixing nip between the rotatable fixer and a pressurizer; a blower configured to generate airflow toward the fixing nip, the airflow being for separating a sheet from the rotatable fixer; and a hardware processor configured to perform a control of causing airflow amounts of the blower to be different in an axial direction of the rotatable fixer so that part of the airflow flowing from the blower toward a non-sheet-passing region of the fixing nip is directed toward the rotatable fixer. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention: 
         FIG. 1  schematically illustrates an entire configuration of an image forming apparatus according to an embodiment of the present invention; 
         FIG. 2  illustrates a principal part of a control system of the image forming apparatus according to the embodiment of the present invention; 
         FIG. 3  indicates temperatures at positions in the axial direction of a fixing belt heated again after a sheet of a size smaller than the maximum sheet-passing width passed through a fixing nip; 
         FIG. 4  is an enlarged view of a region around a duct portion; 
         FIG. 5  is a sectional view of a tip end of the duct portion; 
         FIG. 6  is an explanatory view of the direction of airflow flowing out of the duct portion; 
         FIG. 7  is an explanatory view of the direction of the airflow in a sheet-passing region; 
         FIG. 8  is an explanatory view of the direction of the airflow in a part corresponding to a first interval in a non-sheet-passing region; 
         FIG. 9  is an explanatory view of the direction of the airflow in an end region of the non-sheet-passing region; 
         FIG. 10  illustrates temperatures at positions in the axial direction of the fixing belt of when the direction of airflow is changed; and 
         FIG. 11  is a flowchart of an exemplary operation of airflow direction changing control in the image forming apparatus. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. 
     Hereinafter, an embodiment of the invention is described in detail based on the drawings.  FIG. 1  schematically illustrates an entire configuration of image forming apparatus  1  according to the embodiment of the present invention.  FIG. 2  illustrates a principal part of a control system of image forming apparatus  1  according to the embodiment of the present invention. 
     Image forming apparatus  1  illustrated in  FIG. 1  is a color image forming apparatus of an intermediate transfer system using electrophotographic process technology. That is, image forming apparatus  1  transfers (primary-transfers) toner images of yellow (Y), magenta (M), cyan (C), and black (K) formed on photoconductor drums  413  to intermediate transfer belt  421 , and superimposes the toner images of the four colors on one another on intermediate transfer belt  421 . Then, image forming apparatus  1  secondary-transfers the resultant image to sheet S sent out from feeding tray units  51   a  to  51   c , thereby forming an image. 
     A longitudinal tandem system is adopted for image forming apparatus  1 . In the longitudinal tandem system, respective photoconductor drums  413  corresponding to the four colors of YMCK are placed in series in the travelling direction (vertical direction) of intermediate transfer belt  421 , and the toner images of the four colors are sequentially transferred to intermediate transfer belt  421  in one cycle. 
     As illustrated in  FIG. 2 , image forming apparatus  1  includes image reading section  10 , operation/display section  20 , image processing section  30 , image forming section  40 , sheet conveyance section  50 , fixing section  60 , and control section  101 . 
     Control section  101  includes central processing unit (CPU)  102 , read only memory (ROM)  103 , random access memory (RAM)  104  and the like. CPU  102  reads a program suited to processing contents out of ROM  103 , loads the program into RAM  104 , and integrally controls an operation of each block of image forming apparatus  1  in cooperation with the loaded program. At this time, CPU  101  refers to various kinds of data stored in storage section  72 . Storage section  72  is composed of, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive. 
     Control section  101  transmits and receives various data to and from an external apparatus (for example, a personal computer) connected to a communication network such as a local area network (LAN) or a wide area network (WAN), through communication section  71 . Control section  101  receives, for example, image data (input image data) transmitted from the external apparatus, and performs control to form an image on sheet S on the basis of the image data. Communication section  71  is composed of, for example, a communication control card such as a LAN card. 
     As illustrated in  FIG. 1 , image reading section  10  includes auto document feeder (ADF)  11 , document image scanning device  12  (scanner), and the like. 
     Auto document feeder  11  conveys, with a conveyance mechanism, document D placed on a document tray, to send out document D to document image scanner  12 . Auto document feeder  11  makes it possible to successively read at once images (even both sides thereof) of a large number of documents D placed on the document tray. 
     Document image scanner  12  optically scans a document conveyed from auto document feeder  11  onto a contact glass or a document placed on the contact glass, and images reflected light from the document on a light receiving surface of charge coupled device (CCD) sensor  12   a  to read the document image. Image reading section  10  generates input image data based on results read by document image scanner  12 . The input image data undergo predetermined image processing in image processing section  30 . 
     As illustrated in  FIG. 2 , operation/display section  20  includes, for example, a liquid crystal display (LCD) provided with a touch panel, and functions as display section  21  and operation section  22 . Display section  21  displays various operation screens, image conditions, operating statuses of each function, and/or the like in accordance with display control signals input from control section  101 . Operation section  22  equipped with various operation keys, such as a numeric keypad and a start key, receives various input operations by users and outputs operation signals to control section  101 . 
     Image processing section  30  includes a circuit and/or the like that performs digital image processing of input image data in accordance with default settings or user settings. For example, image processing section  30  performs tone correction based on tone correction data (tone correction table) under the control of control section  101 . Moreover, image processing section  30  performs various correction processing, such as color correction or shading correction, in addition to tone correction, and, compression processing, and the like of input image data. Image forming section  40  is controlled on the basis of the image data that has been subjected to these processes. 
     As illustrated in  FIG. 1 , image forming section  40  includes: image forming units  41 Y,  41 M,  41 C, and  41 K that form images of colored toners of a Y component, an M component, a C component, and a K component on the basis of the input image data; intermediate transfer unit  42 ; and the like. 
     Image forming units  41 Y,  41 M,  41 C, and  41 K for the Y component, the M component, the C component, and the K component have similar configurations. For convenience in illustration and description, common elements are denoted by the same reference signs and such reference signs are accompanied by Y, M, C, or K when they are to be distinguished. In  FIG. 1 , reference signs are given to only the elements of image forming unit  41 Y for the Y component, and reference signs are omitted for the elements of other image forming units  41 M,  41 C, and  41 K. 
     Image forming unit  41  includes exposing device  411 , developing device  412 , photoconductor drum  413 , charging device  414 , drum cleaning device  415  and the like. 
     Photoconductor drum  413  is an organic photoconductor including, for example, a drum-shaped metallic base including the outer peripheral surface on which a photosensitive layer made of a resin containing an organic photoconductive material is formed. 
     Control section  101  causes photoconductor drum  413  to rotate at a constant peripheral velocity by control of a driving current supplied to a driving motor (not illustrated) that causes photoconductor drum  413  to rotate. 
     Charging device  414  is an electrostatic charger, for example, and evenly and negatively charges the surface of photoconductor drum  413  having photoconductivity by generating corona discharge. 
     Exposing device  411  is composed of, for example, a semiconductor laser, and configured to irradiate photoconductor drum  413  with laser light corresponding to the image of each color component. As a result, electrostatic latent images of respective color components are formed in an imaging area irradiated with laser light on the surface of photoconductor drum  413  because of potential differences from a background region. 
     Developing device  412  is a developing device of a two-component counter-rotation type, and attaches developing agents of respective color components to the surface of photoconductor drums  413 , and visualizes the electrostatic latent image to form a toner image. 
     A direct-current developing bias of the polarity identical to the charge polarity of charging device  414 , or a developing bias in which a direct current voltage of the polarity identical to the charge polarity of charging device  414  is superposed on an alternating current voltage is applied to developing device  412 , for example. As a result, reversal development in which toner adheres to the electrostatic latent image formed by exposing device  411  is effected. 
     Drum cleaning device  415  includes a platelike drum cleaning blade made of an elastic body and is brought into contact with the surface of photoconductor drum  413 , and removes transfer residual toner that remains on the surface of photoconductor drum  413  without transferred to intermediate transfer belt  421 . 
     Intermediate transfer unit  42  includes intermediate transfer belt  421 , primary transfer roller  422 , a plurality of support rollers  423 , secondary transfer roller  424 , belt cleaning device  426 , and the like. 
     Intermediate transfer belt  421  is composed of an endless belt, and is wound under tension around the plurality of support rollers  423  under in a loop form. At least one of the plurality of support rollers  423  is composed of a driving roller, and the others are each composed of a driven roller. For example, it is preferable that roller  423 A disposed on the downstream side in the belt travelling direction relative to primary transfer roller  422  for the K component be a driving roller. This makes it easier to keep constant the travelling speed of the belt in a primary transfer part. Intermediate transfer belt  421  travels in direction of arrow A at a constant speed by rotation of a driving roller  423 A. 
     Intermediate transfer belt  421  is a conductive and elastic belt and includes at its surface a high-resistance layer. Intermediate transfer belt  421  is driven into rotation with the control signal from control section  101 . 
     Primary transfer rollers  422  are disposed on the inner peripheral surface side of intermediate transfer belt  421  to face photoconductor drums  413  of respective color components. Primary transfer rollers  422  are brought into pressure contact with photoconductor drums  413  with intermediate transfer belt  421  therebetween, whereby a primary transfer nip for transferring a toner image from photoconductor drums  413  to intermediate transfer belt  421  is formed. 
     Secondary transfer roller  424  is disposed to face backup roller  423 B disposed on the downstream side in the belt travelling direction relative to driving roller  423 A, at a position on the outer peripheral surface side of intermediate transfer belt  421 . Secondary transfer roller  424  is brought into pressure contact with backup roller  423 B with intermediate transfer belt  421  therebetween, whereby a secondary transfer nip for transferring a toner image from intermediate transfer belt  421  to sheet S is formed. 
     When intermediate transfer belt  421  passes through the primary transfer nip, the toner images on photoconductor drums  413  are sequentially primary-transferred to intermediate transfer belt  421 . To be more specific, a primary transfer bias is applied to primary transfer rollers  422 , and an electric charge of the polarity opposite to the polarity of the toner is applied to the rear surface side, that is, a side of intermediate transfer belt  421  that makes contact with primary transfer rollers  422  whereby the toner image is electrostatically transferred to intermediate transfer belt  421 . 
     Thereafter, when sheet S passes through the secondary transfer nip, the toner image on intermediate transfer belt  421  is secondary-transferred to sheet S. To be more specific, a secondary transfer bias is applied to secondary transfer roller  424 , and an electric charge of the polarity opposite to the polarity of the toner is applied to the rear surface side of sheet S, that is, a side of sheet S that makes contact with secondary transfer roller  424  whereby the toner image is electrostatically transferred to sheet S. Sheet S to which the toner image has been transferred is conveyed towards fixing section  60 . 
     Belt cleaning device  426  removes transfer residual toner which remains on the surface of intermediate transfer belt  421  after a secondary transfer. 
     Fixing section  60  includes upper fixing section  60 A having a fixing-surface-side member disposed on a fixing surface side of sheet S, that is, on a side of the surface of sheet S on which a toner image is formed, lower fixing section  60 B having a rear-surface-side supporting member disposed on the rear surface side of sheet S, that is, on a side of the surface of sheet S opposite to the fixing surface, a heating source, and the like. The rear-surface-side supporting member is brought into pressure contact with the fixing-surface-side member, whereby a fixing nip for conveying sheet S in a tightly sandwiching manner is formed. 
     At the fixing nip, toner-image fixer  60  applies heat and pressure to sheet S on which a toner image has been secondary-transferred and which has been conveyed to the fixing nip, so as to fix the toner image on sheet S. Fixing section  60  is disposed as a unit in fixing device F. 
     Upper fixing section  60 A includes endless fixing belt  61 , heating roller  62  and fixing roller  63 , which serve as the fixing-surface-side member. Fixing belt  61  is wound around heating roller  62  and fixing roller  63  under tension. Fixing belt  61  corresponds to a “fixer” of the present invention. 
     Lower fixing section  60 B includes pressurizing roller  64  that is the rear-surface-side supporting member. Together with fixing belt  61 , pressurizing roller  64  forms a fixing nip for conveying sheet S in a tightly sandwiching manner. Pressurizing roller  64  corresponds to a “pressurizer” of the present invention. 
     In addition, separating section  200  having a function of separating sheet S from fixing belt  61  is provided in fixing section  60  on the downstream side. Separating section  200  includes blowing section  210  and duct portion  220 . 
     Blowing section  210  is a fan configured to generate airflow for separating sheet S from fixing belt  61 . Duct portion  220  is a duct for directing, toward the fixing nip, the airflow generated by blowing section  210 . 
     Sheet conveyance section  50  includes sheet feeder  51 , sheet ejection section  52 , conveyance path section  53  and the like. Three sheet feeding tray units  51   a  to  51   c , which constitute sheet feeding section  51 , store sheets S classified based on basis weight, size, or the like (standard paper, special paper) in accordance with predetermined types. Conveying path section  53  includes a plurality of conveying roller pairs including registration roller pairs  53   a . The registration roller section in which registration roller pairs  53   a  are provided corrects skew and deviation of sheet S. 
     Sheets S stored in sheet feeding tray units  51   a  to  51   c  are sent out one by one from the top one and conveyed to image forming section  40  through conveying path section  53 . In image forming section  40 , the toner image on intermediate transfer belt  421  is secondary-transferred to one side of sheet S at one time, and a fixing process is performed in fixing section  60 . Sheet S on which an image has been formed is ejected out of the image forming apparatus by sheet ejection section  52  including sheet ejection rollers  52   a.    
     In the meantime, in a non-sheet-passing region of the fixing nip within which sheet S is not passed through, there is no possibility that sheet S passing through the fixing nip takes away heat, so that a problem arises in that the temperature in the non-sheet-passing region in fixing section  60  rises to a temperature higher than required for fixation, as illustrated in  FIG. 3 . This problem arises when sheets S of a size smaller than that of sheet S having the maximum width allowing sheet S to pass through fixing section  60  are passed through consecutively one by one. An axial position along the abscissa in  FIG. 3 , in which the central portion of fixing belt  61  is expressed by 0, indicates a position shift amount with respect to the central portion. 
       FIG. 3  illustrates a state in which the temperature in the non-sheet-passing region rises when sheet S of a smaller size (for example, A4S having a sheet-passing width of 210 mm) than the maximum sheet width passes through the fixing nip. In addition,  FIG. 3  indicates the fall in temperature on the outside of the non-sheet-passing region. This fall is because less heat is distributed to the end portion of heat source in heating roller  62  inside fixing belt  61 . 
     Such a temperature rise in the non-sheet-passing region of fixing belt  61  to a temperature higher than required for fixation may cause deterioration of members in fixing section  60 . 
     Accordingly, in the embodiment of the present invention, control section  101  controls to cause airflow amounts of blowing section  210  to be different in the axial direction of fixing belt  61  so that part of the airflow flowing from blowing section  210  toward the non-sheet-passing region of the fixing nip is directed toward fixing belt  61 . Specifically, control section  101  is configured to change, in a range of the non-sheet-passing region at fixing belt  61 , the direction of airflow flowing from duct portion  220  such that the airflow is directed toward fixing belt  61 , when sheet S of a size smaller than the maximum sheet width for fixing section  60  passes through the fixing nip. 
     This makes it possible to prevent an excessive rise in temperature of fixing belt  61  in the non-sheet-passing region. Hereinafter, the detailed configuration of duct portion  220  and the control of duct portion  220  according to the embodiment are described. 
     As illustrated in  FIGS. 4 and 5 , a plurality of openings  221  for directing the airflow from blowing section  210  toward the fixing nip are formed in the tip end of duct portion  220 . In addition, duct portion  220  is provided with a plurality of ribs  222  and opening and closing members  223 . 
     The plurality of openings  221  are provided in duct portion  220  in such a manner as to be aligned in the width direction (left-right direction in  FIG. 5 ) of sheet S. The plurality of openings  221  are formed such that all intervals between two adjacent openings  221  are equal to each other. 
     The plurality of ribs  222  are disposed at positions corresponding to both edges of openings  221  in the width direction. Two ribs  222  disposed at positions of both edges of each opening  221  define an airflow path for the airflow to flow out of openings  221 . 
     Opening and closing members  223  are each formed to have a width substantially the same as that of the airflow path defined by two ribs  222 , and are each configured to be able to open and close the airflow path. In  FIG. 4 , opening and closing member  223  is disposed at a position for opening the airflow path. Note that, opening and closing members  223  move with a well-known moving mechanism. 
     When opening and closing member  223  moves in the direction indicated by the arrow, the airflow path is closed. This closure causes the airflow (indicated by the arrows) flowing toward openings  221  not to enter the airflow path as illustrated in  FIG. 5 , so that the airflow does not flow out of some of openings  221  closed by opening and closing members  223 . 
     Further, control section  101  controls opening and closing members  223  so that first opening  221 A through which airflow flows out and second opening  221 B through which airflow does not flow out are alternately aligned. First opening  221 A corresponds to an “airflow opening” of the present invention. 
     By this control, a first interval is made larger than a second interval as illustrated in  FIG. 6 , the first interval being defined between two first openings  221 A with second opening  221 B therebetween in the non-sheet-passing region, the second interval being defined between two first openings  221 A in the sheet-passing region. 
     In other words, control section  101  is configured to make the first interval larger than the second interval, the first interval being defined between first openings  221 A adjacent to each other in the non-sheet-passing region, the second interval being defined between first openings  221 A adjacent to each other in the sheet-passing region. This causes airflow W in the first interval to flow upward in the figure, that is, toward fixing belt  61 . 
     Specifically, airflow W flowing out of first opening  221 A flows while spreading from first opening  221 A. No airflow W flows out between two first openings  221 A, so that the pressure loss is smaller in this region than in a region downward with respect to first openings  221 A. 
     Thus, when streams of airflow W flowing out of two first openings  221 A impinge on each other, both of the impinged streams of airflow W turn back on the side in which the pressure loss is smaller, so that a phenomenon in which streams of airflow W are directed upward occurs. 
     In the meanwhile, in the sheet-passing region, intervals between first openings  221 A are the second interval, so that a space into which streams of airflow flowing out of first openings  221 A turn back is narrow as illustrated in  FIG. 6 . Accordingly, as illustrated in  FIG. 7 , a large amount of airflow W flows between sheet S and fixing belt  61  at the fixing nip and this airflow W flows along with sheet S, whereas only a very small amount of airflow W flows toward the fixing belt  61 . Therefore, in a case of a configuration in which the same amount of airflow W flows in the non-sheet-passing region as in the sheet-passing region, there is a risk that the temperature of the end of fixing belt  61  rises excessively. 
     In the embodiment of the present invention, as illustrated in  FIGS. 6 and 8 , an interval between two first openings  221 A is the first interval in the non-sheet-passing region, so that a larger space into which airflow W flowing out of first openings  221 A turns back is secured in contrast to the sheet-passing region. Accordingly, a large amount of airflow W turns back upward, so that that the non-sheet-passing region of fixing belt  61  can be cooled effectively, and it is thus possible to prevent an excessive temperature rise in the non-sheet-passing region of fixing belt  61 . 
     In addition, in the embodiment of the present invention, three openings from the edge of duct portion  220  are first openings  221 A even in the non-sheet-passing region as illustrated in  FIG. 6 , and are not closed by opening and closing members  223 . As illustrated in  FIG. 9 , only a very small amount of airflow W flows toward fixing belt  61  in this region. The reason for this is that less heat is distributed to the end portion of heat source in heating roller  62  (see  FIG. 3 ), and an excessive fall in temperature of the end of fixing belt  61  is caused when airflow W is directed more toward fixing belt  61 . 
     This setting of openings as described above makes it possible to equalize all temperature states at positions in the axial direction of fixing belt  61  so as to achieve temperature states approximate to that required for fixation in the embodiment of the present invention, as illustrated in  FIG. 10 . 
     Moreover, there are portions corresponding to second openings  221 B at two places in the non-sheet-passing region. It is desirable that a portion of fixing belt  61  having the maximum temperature be included in a range of portions corresponding to these two second openings  221 B (i.e. in a range of portions corresponding to two first intervals) when sheet S passes through the fixing nip. In this way, the airflow can be positively directed toward fixing belt  61  to the portion for which temperature reduction is desired. 
     In the meantime, the range of the non-sheet-passing region is changed depending on the width of sheet S. According to the embodiment of the present invention, control section  101  changes the range where the direction of airflow is changed, depending on the width of sheet S which passes through the fixing nip. For example, when the range of the non-sheet-passing region is extended, the range where the first interval is formed is extended accordingly, and in contrast, when the range of the non-sheet-passing region is made narrow, the range where the first interval is formed is made narrow accordingly. In this way, it is possible to perform a suitable airflow direction changing control according to the width of sheet S. 
     An exemplary operation of airflow direction changing control in image forming apparatus  1  configured as described above is described.  FIG. 11  is a flowchart of an exemplary operation of airflow direction changing control in image forming apparatus  1 . The processing in  FIG. 11  is executed when the execution instruction of a print job is input. 
     Note that, image forming apparatus  1  is configured to activate blowing section  210  when image forming apparatus  1  receives the execution instruction of a print job, and is configured to stop blowing section  210  after the print job is completed. In addition, all the intervals between openings in the non-sheet-passing region can be set to be the second interval at the start of the print job, for example. 
     As illustrated in  FIG. 11 , control section  101  determines whether or not sheet S is a small size sheet (step S 101 ). When the determination result indicates that sheet S is a small size sheet (step S 101 , YES), control section  101  sets a part of the intervals between openings in the non-sheet-passing region to be the first interval (step S 102 ). Note that, in step S 102 , when the part of the intervals between openings in the non-sheet-passing region is already the first interval, control section  101  does not change the intervals between openings in the non-sheet-passing region. 
     In contrast, when the determination result indicates that sheet S is not a small size sheet (step S 101 , NO), control section  101  sets all the intervals between openings in the non-sheet-passing region to be the second interval (step S 103 ). Note that, in step S 103 , when all the intervals between openings in the non-sheet-passing region are already the second interval, control section  101  does not change the intervals between openings in the non-sheet-passing region. 
     After step S 102  or step S 103 , control section  101  determines whether or not the print job has been completed (step S 104 ). When the determination result indicates that the print job has not been completed (step S 104 , NO), the processing returns to step S 101 . In contrast, when the print job has been completed (step S 104 , YES), the present control is ended. 
     According to the embodiment of the present invention configured as described above, the temperature in the non-sheet-passing region in fixing section  60  is cooled by utilizing the airflow from separating section  200 . Therefore, it is not necessary to provide a cooling fan separately, and thus, a temperature rise in the non-sheet-passing region in fixing section  60  can be prevented without image forming apparatus  1  being made oversize. 
     In addition, in the embodiment of the present invention, an interval between two first openings  221 A are extended, so that it is possible for the airflow to easily turn back into a region of such an interval. Thus, in comparison with a configuration in which an interval between two first openings  221 A is not extended, the airflow can be directed more toward fixing belt  61 , and a temperature rise in the non-sheet-passing region of fixing belt  61  can be prevented more effectively. 
     Note that, although the airflow paths in communication with openings  221  of duct portion  220  are closed in order for the airflow not to flow out of openings  221  in the above-mentioned embodiment, the present invention is not limited to this embodiment. For example, openings  221  of duct portion  220  may be closed directly. Openings facing toward fixing belt  61  may be formed separately in the tip end of duct portion  220 , and such openings may be configured to open. In addition, the path of the airflow flowing out of duct portion  220  may be configured to be changeable. 
     In addition, although fixing belt  61  wound around heating roller  62  and fixing roller  63  under tension is illustrated as the fixing member in the above-mentioned embodiment, the present invention is not limited to this embodiment. In a configuration in which fixing belt  61  is not provided, a fixing roller may be used as a fixing member. 
     In addition, the aforementioned embodiments merely describe examples of implementations for practicing the present invention, and should not be construed as limiting the technical scope of the present invention. That is, the present invention can be embodied in various forms without departing from the spirit, scope, or principal features of the present invention. 
     Although embodiments of the present invention have been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and not limitation, the scope of the present invention should be interpreted by terms of the appended claims.