Patent Publication Number: US-9417588-B2

Title: Image forming apparatus

Description:
INCORPORATION BY REFERENCE 
     The disclosure of Japanese Patent Application No. 2014-151401 filed on Jul. 25, 2014 including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     BACKGROUND 
     The disclosure relates to an image forming apparatus. 
     In an image forming apparatus typified by a digital multifunctional peripheral or the like, an image of a document is read by an image reading unit, and then an electrostatic latent image is formed on a photoconductor provided in an image forming unit based on the read image. Then, a developing agent, such as charged toner, is supplied onto the formed electrostatic latent image to form a visible image, the visible image is transferred and fixed to paper, and then the paper is discharged to the outside of the apparatus. Paper to which a visible image is to be transferred is fed at all times into the image forming apparatus from a paper feed cassette provided in the image forming apparatus. 
     Herein, a technique of reducing occurrence of folding when conveying paper in the image forming apparatus is known heretofore. 
     According to a typical fixing device, from the viewpoint of prevention of occurrence of wrinkles and folding when fixing an envelope and fixing stability to the envelope, a recording material is passed between nips formed by pressing a pressurizing member against a fixing member to fix the same by heating and pressurizing. The fixing device allows passage and fixation of an envelope and is configured so that the pressurization power of the pressurizing member to the fixing member can be varied, and the pressurization power during the passage of the envelope is set to 45 to 60% of the pressurization power during the passage of plain paper and the fixing temperature during the passage of the envelope is higher than the fixing temperature during the passage of plain paper. 
     From the viewpoint of suppressing occurrence of folded edge, paper jamming, and the like at a turning point of a conveying path and a reversing path, a typical image forming apparatus has a fixing means which performs fixing processing to each paper P to which a toner image is transferred, a conveying path R 1  through which each paper from the fixing means passes, a pair of reversing rollers which switch back the paper P from the conveying path R 1 , a reversing path R 2  which shares a section from the pair of reversing rollers to a second turning point P 2  on the conveying path R 1  with the conveying path R 1  and through which the switched back paper P passes, and an angle controlling means which lets the following paper P which is to be switched back by the pair of reversing rollers enter at an angle less than 90° at the second turning point P 2 . 
     SUMMARY 
     An image forming apparatus according to one aspect of the disclosure has a developing unit, a fixing unit, a receiving unit, a paper setting unit, and a control unit. The developing unit forms a visible image on paper using a developing agent. The fixing unit includes a heating roller and a pressurizing roller abutting on the heating roller. The fixing unit conveys the paper on which the visible image is formed by the developing unit between the heating roller and the pressurizing roller to fix the visible image to the paper. The receiving unit receives a demand for smoothing-out of wrinkles of the paper. The paper setting unit sets paper to be subjected to smoothing-out of wrinkles. When the receiving unit receives the demand for smoothing-out of wrinkles, the control unit performs control so that the developing unit is not operated and the paper to be subjected to smoothing-out of wrinkles set in the paper setting unit is conveyed to the fixing unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view illustrating the appearance of a digital multifunctional peripheral when applying an image forming apparatus according to one embodiment of the disclosure to the digital multifunctional peripheral. 
         FIG. 2  is a block diagram illustrating the configuration of the digital multifunctional peripheral when applying the image forming apparatus according to one embodiment of the disclosure to the digital multifunctional peripheral. 
         FIG. 3  is an outside view illustrating the schematic configuration of an operation unit. 
         FIG. 4  is a view illustrating the schematic configuration of an image forming unit. 
         FIG. 5  is an exploded view illustrating the configuration of a fixing unit provided in the image forming unit. 
         FIG. 6  is a flow chart showing the contents of processing when smoothing-out wrinkles of paper to be subjected to smoothing-out of wrinkles using the image forming apparatus according to one embodiment of the disclosure. 
         FIG. 7  is a view illustrating an example of a display screen contained in the operation unit. 
         FIG. 8  is a flow chart showing the contents of processing when smoothing-out wrinkles of paper to be subjected to smoothing-out of wrinkles using an image forming apparatus according to another embodiment of the disclosure. 
         FIG. 9  is a view illustrating an example of the display screen contained in the operation unit. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the disclosure are described. First, the configuration of a digital multifunctional peripheral when applying an image forming apparatus according to one embodiment of the disclosure to the digital multifunctional peripheral is described.  FIG. 1  is a schematic view illustrating the appearance of the digital multifunctional peripheral when applying the image forming apparatus according to one embodiment of the disclosure to the digital multifunctional peripheral.  FIG. 2  is a block diagram illustrating the configuration of the digital multifunctional peripheral when applying the image forming apparatus according to one embodiment of the disclosure to the digital multifunctional peripheral. 
     Referring to  FIG. 1  and  FIG. 2 , a digital multifunctional peripheral  11  has a control unit  12 , an operation unit  13 , an image reading unit  14 , a paper setting unit  19 , an image forming unit  15 , a discharging tray  30 , a hard disk  16 , a facsimile communicating unit  17 , and a network interface unit  18  for connection with a network  25 . The control unit  12  controls the entire digital multifunctional peripheral  11 . The operation unit  13  contains a display screen  21  which displays information transmitted from the digital multifunctional peripheral  11  and input contents of a user. The operation unit  13  inputs image formation conditions, such as the number of prints, gradation, and the like and turns ON or OFF the power supply. The image reading unit  14  contains an ADF (Auto Document Feeder)  22  which automatically conveys a set document to a reading unit. The image reading unit  14  reads an image of a document. The paper setting unit  19  contains a manual paper feed tray  28  which manually sets paper and a paper feed cassette group  29  capable of storing two or more sheets of paper different in size. The paper setting unit  19  sets a paper on which an image is formed and paper to be subjected to smoothing-out of wrinkles described later. The image forming unit  15  forms an image based on a read image or image data transmitted through the network  25 . The discharging tray  30  discharges paper after forming an image on the paper by the image forming unit  15 . The hard disk  16  stores transmitted image data, input image formation conditions, and the like. The facsimile communicating unit  17  is connected to a public line  24  and performs facsimile transmission and facsimile receiving. The digital multifunctional peripheral  11  has a DRAM (Dynamic Random Access Memory) which writes or reads image data and the like but the illustration and the description thereof are omitted. The arrows in  FIG. 2  indicate the flow of control signals and data relating to control and an image. As illustrated in  FIG. 1 , in this embodiment, the paper feed cassette group  29  contains three paper feed cassettes  23   a ,  23   b , and  23   c.    
     The digital multifunctional peripheral  11  operates as a copying machine by forming an image in the image forming unit  15  using image data of a document read by the image reading unit  14 . The digital multifunctional peripheral  11  operates as a printer by forming an image in the image forming unit  15 , and then prints the image on paper using image data transmitted from computers  26   a ,  26   b , and  26   c  connected to the network  25  through the network interface unit  18 . The digital multifunctional peripheral  11  operates as a facsimile machine by forming an image in the image forming unit  15  through the DRAM using image data transmitted from the public line  24  through the facsimile communicating unit  17  and transmitting image data of a document read by the image reading unit  14  to the public line  24  through the facsimile communicating unit  17 . More specifically, the digital multifunctional peripheral  11  has a plurality of functions relating to image processing, such as a copying function, a printer function, and a facsimile function. Furthermore, the digital multifunctional peripheral  11  has a function capable of setting each function in detail. 
     An image processing system  27  containing the digital multifunctional peripheral  11  has the digital multifunctional peripheral  11  and the plurality of computers  26   a ,  26   b , and  26   c . Specifically, the image processing system  27  has the digital multifunctional peripheral  11  of the configuration described above and the plurality of computers  26   a ,  26   b , and  26   c  connected to the digital multifunctional peripheral  11  through the network  25 . In this embodiment, the plurality of computers  26   a  to  26   c  includes three computers. Each of the computers  26   a  to  26   c  can request the digital multifunctional peripheral  11  to perform printing through the network  25 . The digital multifunctional peripheral  11  and the computers  26   a  to  26   c  may be connected by wire using a LAN (Local Area Network) cable or the like or may be connected by radio. A configuration in which another digital multifunctional peripheral and a server may be connected into the network  25  may be acceptable. 
     Next, the configuration of the operation unit  13  described above is described in more detail.  FIG. 3  is an outside view illustrating the schematic configuration of the operation unit  13 . Referring to  FIG. 3 , the operation unit  13  includes a ten key  31  which inputs the numbers of 0 to 9 for inputting the number of prints and the like and inputs signs of “*” and “#”, a start key  32  which instructs the start of printing and the start of facsimile transmission, a power supply key  33  which turns ON/OFF of the power supply of the digital multifunctional peripheral  11 , a menu key  34  which instructs selection of a printer function, a copying function, and the like of the digital multifunctional peripheral  11 , a registration key  35  which instructs registration of various image formation conditions and a user, a reset key  36  which resets the contents of the instructions input by a user using the ten key  31  and the like, and the display screen  21  described above. The display screen  21  has a liquid crystal touch-panel function and allows input of image formation conditions and the like also from the display screen  21  and also allows selection of the functions and the like by pressing with a user&#39;s finger or the like. 
     Next, the configuration of the image forming unit  15  is described in more detail.  FIG. 4  is a view illustrating the schematic configuration of the image forming unit  15 . Referring to  FIG. 4 , the image forming unit  15  has a developing unit  41  which forms a visible image on paper using a developing agent, such as toner. The developing unit  41  illustrated by chain double-dashed lines in  FIG. 4  has a photoconductor  42  which forms an electrostatic latent image on the surface, a charging unit  43  which charges the surface of the photoconductor  42 , a developing portion  44  which contains a developing sleeve and a plurality of stirring rollers and supplies a developing agent, such as toner, to the surface of the photoconductor  42  on which the electrostatic latent image is formed to form a visible image with the toner, a transferring unit  45  which contains a transfer charger and a separation charger and transfers the visible image formed on the surface of the photoconductor  42  to a conveyed paper  39 , and a cleaning unit  46  which contains a static electricity eliminating roller, a cleaning blade, and the like and removes toner remaining on the surface of the photoconductor  42  after transferring the visible image to the paper  39 , residual charges, and the like. The photoconductor  42  rotates in the direction indicated by an arrow R 1  in  FIG. 4 . The image forming unit  15  forms an electrostatic latent image on the photoconductor  42  based on an image read by the image reading unit  14 . The image forming unit  15  supplies toner to the electrostatic latent image formed on the photoconductor  42  to form a visible image with the toner. The image forming unit  15  repeatedly subjects the photoconductor  42  to charging, developing, transferring, and cleaning to form a visible image on the conveyed paper  39  with toner. In order to compensate the toner consumed for the development, toner is further supplied to the developing portion  44  at all times by a toner container (not illustrated) detachably provided in the developing unit  41 . 
     The image forming unit  15  has a fixing unit  51  which fixes the visible image formed on the paper  39  by the developing unit  41  to the paper  39 .  FIG. 5  is an exploded view illustrating the structure of the fixing unit  51 . Referring to  FIG. 4  and  FIG. 5 , the fixing unit  51  contains a hollow rotatable heating roller  52  which heats paper when fixing toner to the paper and a solid rotatable pressurizing roller  54  which pressurizes paper when fixing toner to the paper. The heating roller  52  is configured from a cylindrical metal raw tube. The heating roller  52  is provided with a pair of heaters  53   a  and  53   b  therein. The heating roller  52  is heated to a predetermined temperature which is suitable for fixing by energizing the heaters  53   a  and  53   b . The temperature of the heating roller  52  is controlled by controlling the energization state to the heaters  53   a  and  53   b.    
     The pressurizing roller  54  is configured from a rubber cylindrical member having elasticity. The heating roller  52  and the pressurizing roller  54  abut on each other. Specifically, the heating roller  52  and the pressurizing roller  54  are provided in such a manner that the surface  55  of the heating roller  52  and the surface  56  of the pressurizing roller  54  contact each other. Since the heating roller  52  and the pressurizing roller  54  contact each other, a certain degree of the heat of the heating roller  52  is transmitted to the pressure roller  54 . More specifically, the heating roller  52  and the pressurizing roller  54  are set to almost the same temperature. 
     The pressurizing roller  54  is configured in such a manner as to have a crowning shape. More specifically, a central portion  57   a  in the longitudinal direction of the pressurizing roller  54  is configured in such a manner as to swell to the outer diameter side with respect to an end portion  57   b  in the longitudinal direction of the pressurizing roller  54 . A length L 1  in  FIG. 5  shows a difference between the radius in the central portion  57   a  in the longitudinal direction of the pressurizing roller  54  and the radius in the end portion  57   b  in the longitudinal direction of the pressurizing roller  54 . From the viewpoint of ease of understanding, the difference between the radii is illustrated with exaggeration in  FIG. 5 . The heating roller  52  and the pressurizing roller  54  are provided in such a manner as to abut on each other throughout the longitudinal direction. More specifically, since the pressurizing roller  54  has a crowning shape, the pressurizing roller  54  is configured to contact the heating roller  52  at higher pressure as approaching the central portion  57   a.    
     The pressurizing roller  54  rotates in the direction indicated by an arrow R 2  in  FIG. 4 . The heating roller  52  rotates in a direction opposite to the rotation direction of the pressurizing roller  54 . By the rotation of the heating roller  52  and the pressurizing roller  54 , paper is conveyed from the upstream side to the downstream side. During the conveyance, the visible image formed on the paper is fixed by the heating roller  52  and the pressurizing roller  54 . The direction where the paper  39  is conveyed is roughly illustrated by the arrow D 1  in  FIG. 4 . The conveyance direction of the paper  39  is the direction from the front surface to the back surface in  FIG. 5 . Herein, since the pressurizing roller  54  has the crowning shape configured in such a manner that the central portion  57   a  swells as described above, the paper  39  is conveyed in such a manner as to be pulled in the direction indicated by the arrows in  FIG. 5 , i.e., from the center toward the end portion of the paper  39 . Thus, when passing the paper  39  through the fixing unit  51 , wrinkles of the paper  39  can be smoothed-out and the generation of wrinkles of the paper  39  can be suppressed. 
     In the image forming unit  15 , a conveying belt  47  provided between the developing unit  41  and the fixing unit  51  and a plurality of paper feeding rollers  48   a ,  48   b ,  48   c ,  48   d , and  48   e  are provided. For example, the paper  39  set to the manual paper feed tray  28  is conveyed through paper conveying paths  49   a ,  49   b ,  49   c , and  49   d  by the paper feeding rollers  48   a  to  48   e  to be discharged to the discharging tray  30 . The paper  39  set in each of the paper feed cassettes  23   a  to  23   c  is conveyed through the paper conveying paths  49   b  to  49   d  by the paper feeding rollers  48   b  to  48   e  to be discharged to the discharging tray  30 . 
     Herein, the image forming unit  15  contained in the digital multifunctional peripheral  11  has a spraying unit  61  as a liquid spraying unit which sprays liquid to the paper to be subjected to smoothing-out of wrinkles. The spraying unit  61  illustrated by the alternate long and short dash lines in  FIG. 4  has a tank portion  63  which stores water  62  as liquid therein, a spraying section  64  which sprays the water  62  to be supplied from the tank portion  63  in the form of mist to the paper  39 , a pipe portion  65  which supplies the water  62  to the spraying section  64  from the tank portion  63 , and a guide unit  66  which guides the water  62  to be sprayed from the spraying section  64  not to spread to the developing unit  41  and the fixing unit  51  side. A spraying unit  61  is provided between the developing unit  41  and the fixing unit  51  in the conveyance direction D 1  of the paper  39 . The spraying unit  61  is provided above the conveying belt  47  and can spray the water  62  in the form of mist to the surface of the paper  39  to be conveyed on the conveying belt  47 . 
     Next, a case where wrinkles of the paper to be subjected to smoothing-out of wrinkles are smoothed-out using the digital multifunctional peripheral  11  according to one embodiment of the disclosure is described.  FIG. 6  is a flow chart showing the contents of processing when smoothing-out wrinkles of the paper to be subjected to smoothing-out of wrinkles. Referring to  FIG. 6 , etc., first, a user sets the paper to be subjected to smoothing-out of wrinkles to the manual paper feed tray  28 . Then, the digital multifunctional peripheral  11  detects that the paper is set to the manual paper feed tray  28  (In  FIG. 6 , Step S 11 , “Step” is omitted below.). Next, the digital multifunctional peripheral  11  displays an inquiry screen which inquires whether or not the paper  39  set to the manual paper feed tray  28  is to be subjected to smoothing-out of wrinkles and whether or not the spraying unit  61  is to be operated on the display screen  21  of the operation unit  13  (S 12 ). 
       FIG. 7  is a view illustrating an example of the display screen  21  of the operation unit  13  in this case. Referring to  FIG. 7 , the display screen  21  of the operation unit  13  displays an inquiry message  58   a  of “Select wrinkle stretching-out function?”, a selection key  59   a  of “Select”, and a selection key  59   b  of “Not select” and an inquiry message  58   b  of “Operate spraying unit?”, a selection key  59   c  of “Operate”, and a selection key  59   d  of “Not operate”. By pressing each of the selection keys  59   a  to  59   d , the selection of the functions can be achieved. Herein, the operation unit  13  operates as a receiving unit which receives a demand for smoothing-out of wrinkles of paper. 
     Herein, a user presses the selection key  59   a  of “Select” about the wrinkle smoothing-out function and presses the selection key  59   c  of “Operate” about the spraying unit  61 . When the digital multifunctional peripheral  11  detects the pressing of the selection key  59   a  of “Select” (YES in S 13 ), the digital multifunctional peripheral  11  stops the operation of the developing unit  41  (S 14 ). Then, the plurality of paper feeding rollers  48   a  to  48   c  are rotated at an appropriate timing to convey the paper  39  to be subjected to smoothing-out of wrinkles from the manual paper feed tray  28  into the digital multifunctional peripheral  11 , specifically, into the paper conveying paths  49   a  and  49   b  provided in the digital multifunctional peripheral  11  (S 15 ). 
     Then, the operation of the spraying unit  61  is selected (YES in S 16 ), and therefore the spraying unit  61  is operated at timing when the paper  39  to be subjected to smoothing-out of wrinkles is conveyed to the conveying belt  47  (S 17 ). Specifically, the water  62  is sprayed in the form of mist to the paper  39  to be subjected to smoothing-out of wrinkles by the spraying section  64  provided in the spraying unit  61 . In this case, the paper  39  may be stopped once on the conveying belt  47 , and then the water  62  may be sprayed to the paper  39  or the conveyance rate of the paper  39  may be reduced instead of stopping the paper  39 , and then the water  62  may be sprayed to the paper  39 . 
     Thereafter, the paper  39  to be subjected to smoothing-out of wrinkles is conveyed to the fixing unit  51  (S 18 ). Specifically, the paper is conveyed between the heating roller  52  heated to a predetermined temperature by the heaters  53   a  and  53   b  and the pressurizing roller  54 . Then, wrinkles of the paper  39  to be subjected to smoothing-out of wrinkles are smoothed-out by the heating roller  52  and the pressurizing roller  54 . Thereafter, the plurality of paper feeding rollers  48   d  and  48   e  are rotated at an appropriate timing to discharge the paper  39  to be subjected to smoothing-out of wrinkles through the paper conveying paths  49   c  and  49   d  to the outside  30  of the apparatus, i.e., the discharging tray (S 19 ). 
     On the other hand, when the wrinkle smoothing-out function is not selected (NO in S 13 ), it is judged that image formation on paper set to the usual manual paper feed tray  28  is selected, and then the developing unit  41  is operated to form an image on the paper (S 20 ). Thereafter, the paper on which the image is formed is discharged to the fixing unit  51  (S 18 ), the image is fixed to the paper  39 , and then the paper is discharged (S 19 ). When the selection key  59   d  of “Not operate” is pressed and the operation of the spraying unit  61  is not selected (NO in S 16 ), the paper  39  to be subjected to smoothing-out of wrinkles is conveyed to the fixing unit  51  without operating the spraying unit  61  (S 18 ). Thereafter, wrinkles of the paper  39  to be subjected to smoothing-out of wrinkles are smoothed-out by the fixing unit  51 , and then the paper  39  is discharged (S 19 ). 
     When the digital multifunctional peripheral  11  of such a configuration receives the demand for smoothing-out of wrinkles of the paper  39 , the digital multifunctional peripheral  11  does not operate the developing unit  41  and conveys the paper  39  to be subjected to smoothing-out of wrinkles set to the manual paper feed tray  28  to the fixing unit  51 . Then, when the paper  39  to be subjected to smoothing-out of wrinkles is conveyed between the heating roller  52  and the pressurizing roller  54 , the wrinkles of the paper  39  are smoothed-out by the heating roller  52  and the pressurizing roller  54 . In this case, since the developing unit  41  is not operated, an image is not formed on the paper  39 . Therefore, the digital multifunctional peripheral  11  of such a configuration can efficiently reduce the wrinkles of the paper  39 . 
     In this case, since the spraying unit  61  as a liquid spraying unit which sprays the water  62  to the paper  39  to be subjected to smoothing-out of wrinkles is provided, the water  62  is sprayed to the paper  39  to be subjected to smoothing-out of wrinkles when smoothing-out the wrinkles of the paper  39 , and then the wrinkles of the paper  39  can be efficiently reduced. 
     Moreover, in this case, since the spraying unit  61  is provided between the developing unit  41  and the fixing unit  51  in the paper conveying paths  49   a  to  49   d  of the paper  39  to be subjected to smoothing-out of wrinkles, the water  62  can be sprayed to the paper  39  to be subjected to smoothing-out of wrinkles at more appropriate timing. 
     Moreover, the digital multifunctional peripheral  11  is configured to inquire whether or not the spraying unit  61  is to be operated in this case. Therefore, by detecting the pressing of the selection key  59   d  of “Not operate” when a user does not want the spraying of the water  62  or the like in the case of smoothing-out wrinkles of paper containing an image formed with an aqueous ink and the like, for example, the water  62  is not sprayed. 
     In the embodiment described above, the digital multifunctional peripheral  11  is configured to inquire a user about whether nor not the spraying unit  61  is operated but the configuration is not limited thereto and the digital multifunctional peripheral  11  may be configured so that when the control unit  12  receives a demand for smoothing-out of wrinkles, liquid may be sprayed to the paper  39  to be subjected to smoothing-out of wrinkles. Thus, the liquid can be sprayed to the paper  39  without separately setting the spraying unit  61  to spray the liquid to the paper  39 , so that the wrinkles of the paper  39  can be more efficiently reduced. 
     In the embodiment described above, the digital multifunctional peripheral  11  may be configured so that the image of the paper  39  to be subjected to smoothing-out of wrinkles is read by the image reading unit  14 , and then the read image result may be utilized for smoothing-out wrinkles.  FIG. 8  is a flow chart showing the flow of the processing in this case. Referring to  FIG. 8 , etc., the image of the paper  39  to be subjected to smoothing-out of wrinkles is first read (S 21 ). In this case, the image of the paper  39  may be automatically read using the ADF22 described above or the paper  39  to be subjected to smoothing-out of wrinkles may be placed on a placement table provided in the image reading unit  14 , and then the image of the paper  39  may be read by scanning. The read image data are stored in the hard disk  16  (S 22 ). 
     Thereafter, when the paper  39  to be subjected to smoothing-out of wrinkles set to the manual paper feed tray  28  is detected (S 23 ), an inquiry screen is displayed in the same manner as in the case shown in  FIG. 6  (S 24 ). 
       FIG. 9  is a view illustrating an example of the display screen of the operation unit  13  in this case. Referring to  FIG. 9 , on the display screen  21  of the operation unit  13 , the inquiry message  58   a  of “Select wrinkle smoothing-out function”, the selection key  59   a  of “Select”, and the selection key  59   b  of “Not select” and an inquiry message  58   c  of “Utilize read image”, a selection key  59   e  of “Utilize”, and a selection key  59   f  of “Not utilize” are displayed. By the pressing of each of the selection keys  59   a  to  59   f , the selection of the functions can be achieved. 
     Herein, a user presses the selection key  59   a  of “Select” about the wrinkle smoothing-out function and presses the selection key  59   e  of “Utilize” about the read image. When the digital multifunctional peripheral  11  detects the pressing of the selection key  59   a  of “Select” (YES in S 25 ), the digital multifunctional peripheral  11  stops the operation of the developing unit  41 (S 26 ). Then, the paper  39  to be subjected to smoothing-out of wrinkles is conveyed into the digital multifunctional peripheral  11  from the manual paper feed tray  28  (S 27 ). 
     Next, since the control unit  12  detects that the selection key  59   e  of “Utilize” is pressed about the read image on the inquiry screen, the control unit  12  judges whether or not the spraying unit  61  is to be operated from the read image (S 28 ). More specifically, for example, the control unit  12  recognizes a black shadow portion formed under the influence of wrinkles from the read image stored in the hard disk  16  about the paper  39  to be subjected to smoothing-out of wrinkles. Then, the control unit  12  judges whether or not the spraying unit  61  is to be operated based on whether or not the shade degree of the black shadow portion exceeds the predetermined threshold value. 
     When the control unit  12  judges that the spraying unit is operated (YES in S 28 ), the spraying unit  61  is operated (S 29 ). More specifically, the water  62  is sprayed from the spraying section  64  in the form of mist to the paper  39  to be subjected to smoothing-out of wrinkles. 
     Thereafter, the paper  39  is conveyed to the fixing unit  51  (S 30 ), wrinkles are smoothed-out, and then the paper is discharged (S 31 ) in the same manner as in the case shown in  FIG. 6 . On the other hand, when the control unit  12  judges that the spraying unit  61  is not operated in S 28  (NO in S 28 ), the paper  39  is conveyed to the fixing unit  51  without operating the spraying unit  61  (S 30 ), wrinkles are smoothed-out, and then the paper is discharged (S 31 ). When the wrinkle smoothing-out function is not selected (NO in S 25 ), the developing unit is operated to form an image on paper (S 32 ), the paper  39  is conveyed to the fixing unit  51  for fixing (S 30 ), and then the paper is discharged (S 31 ). 
     According to such a configuration, since the image reading unit  14  which reads the image of the paper to be subjected to smoothing-out of wrinkles is provided, the position, size, and range where wrinkles are present in the paper  39  to be subjected to smoothing-out of wrinkles can be grasped before smoothing-out wrinkles by the fixing unit  51 , and thus smoothing-out of wrinkles more corresponding to the state of the wrinkles can be achieved, so that the wrinkles of the paper  39  can be more efficiently reduced. 
     In this case, since the control unit  12  judges whether or not the water  62  is to be sprayed to the paper to be subjected to smoothing-out of wrinkles by the spraying unit  61  as a liquid spraying unit from the image read by the image reading unit, more appropriate smoothing-out of wrinkles according to the state of the wrinkles can be achieved. 
     In the embodiment described above, when the receiving unit receives a demand for smoothing-out of wrinkles, the control unit may perform control to change at least one of the number of rotations of the heating roller, the number of rotations of the pressurizing roller, the temperature of the heating roller, the temperature of the pressurizing roller, and the conveyance rate of the paper to be subjected to smoothing-out of wrinkles. Thus, the wrinkles of the paper  39  can be more efficiently reduced according to the material of the paper  39  or the wrinkle state. 
     In the embodiment described above, the spraying unit is configured to spray water in the form of mist. However, the configuration is not limited thereto and the spraying unit may be configured to spray another kind of liquid other than water. Moreover, the spraying unit may be configured to spray liquid to paper with a certain degree of force without being limited to the configuration of spraying liquid in the form of mist. 
     In the embodiment described above, the spraying unit is provided between the developing unit and the fixing unit in the paper conveyance direction. However, the configuration is not limited thereto and the spraying unit may be provided before the developing unit, for example, without being limited to the configuration. It is a matter of course that a plurality of spraying units may be provided. 
     In the embodiment, paper set to the manual paper feed tray is subjected to smoothing-out of wrinkles. However, the configuration is not limited thereto and a configuration may be acceptable in which paper set to the paper feed cassette provided in the paper feed cassette group is subjected to smoothing-out of wrinkles. 
     The following configuration may also be acceptable. More specifically, the control unit  12  which is included in the digital multifunctional peripheral  11  has a folding frequency detecting unit  67  which detects the frequency in which paper is folded from an image read by the image reading unit  14 . Then, the control unit may be configured to perform control to change the temperatures of the heating roller and the pressurizing roller according to the folding frequency of paper detected by the folding frequency detecting unit. Thus, wrinkles of folded paper can be appropriately smoothed-out. In this case, specifically, when the image reading unit reads that paper has one wrinkle, the frequency in which the paper is folded is detected to be 1 time. Then, the temperatures of the heating roller and the pressurizing roller are slightly increased, and then the wrinkle of the paper is smoothed-out. When the image reading unit reads that paper has three wrinkles or when the image reading unit reads that wrinkles of paper are formed in the shape of a cross, the frequency in which the paper is folded is detected to be 2 times. Then, the temperatures of the heating roller and the pressurizing roller are increased to a temperature higher than the temperature when the folding frequency is 1 time described above, and then the wrinkles of the paper are smoothed-out. Such a configuration may be acceptable. 
     The embodiments and Examples disclosed in this specification are examples in all the respects and are not limited in any aspect. The scope of the disclosure is defined by not the description above but the claims and any alternation which comes within the meaning of the scope of the claims is to be embraced within the scope of the claims. 
     The image forming apparatus according to the disclosure is particularly effectively utilized when efficient smoothing-out of wrinkles is required.