Abstract:
An image forming apparatus including: a recording medium transport path along which a recording medium is transported; a pair of first rollers that are provided at an upstream side in a recording medium transporting direction with respect to the recording medium transport path and that feed the recording medium into the recording medium transport path; a pair of second rollers that are provided at a downstream side in the recording medium transporting direction with respect to the recording medium transport path and that receive the recording medium transported by the recording medium transport path; a recording medium transport stopping section that stops transporting of the recording medium on the recording medium transport path; and a path opening and closing member that opens the recording medium transport path is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2007-117281 filed Apr. 26, 2007. 
       BACKGROUND 
     Technical Field 
       [0002]    The present invention relates to an image forming apparatus, and particularly to an image forming apparatus to which is added a function such that a user may specify a cause of generation of a paper wrinkle which is one of troubles occurred when using of the image forming apparatus. 
       SUMMARY 
       [0003]    In accordance with an aspect of the invention, there is provided an image forming apparatus including: a recording medium transport path along which a recording medium is transported; a pair of first rollers that are provided at an upstream side in a recording medium transporting direction with respect to the recording medium transport path and that feed the recording medium into the recording medium transport path; a pair of second rollers that are provided at a downstream side in the recording medium transporting direction with respect to the recording medium transport path and that receive the recording medium transported by the recording medium transport path; a recording medium transport stopping section that stops transporting of the recording medium on the recording medium transport path; and a path opening and closing member that opens the recording medium transport path. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    Exemplary embodiments of the invention will be described in detail with reference to the following figures, wherein: 
           [0005]      FIG. 1  is a schematic side elevational view showing a structure of an image forming apparatus in accordance with a first exemplary embodiment of the invention; 
           [0006]      FIG. 2  is a schematic side elevational view showing a state in which a cover of the image forming apparatus in accordance with the first exemplary embodiment of the invention is opened; 
           [0007]      FIGS. 3A and 3B  are plan views showing a transport unit side of the image forming apparatus in accordance with the first exemplary embodiment of the invention, in which  FIG. 3A  is a view showing a case that a cause of a paper wrinkle exists in a registering roll side, and  FIG. 3B  is a view showing a case that the cause of the paper wrinkle exists in a heat roll side of a fixing apparatus; 
           [0008]      FIG. 4  is a schematic side elevational view showing a state in which a cover of an image forming apparatus in accordance with a second exemplary embodiment of the invention is opened; 
           [0009]      FIG. 5  is a schematic side elevational view showing a state in which a cover of an image forming apparatus in accordance with a third exemplary embodiment of the invention is opened; 
           [0010]      FIG. 6  is a schematic side elevational view showing a state in which a cover of an image forming apparatus in accordance with a fourth exemplary embodiment of the invention is opened; and 
           [0011]      FIG. 7  is a plan view showing a transport unit side of an image forming apparatus in accordance with a fifth exemplary embodiment of the invention; 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    A description will be in detail given below of exemplary embodiments of the invention shown in the accompanying drawings. In this case, in each of the drawings, elements arranged per colors yellow (Y), magenta (M), cyan (C) and black (K) may have signs “Y”, “M”, “C” and “K” attached to reference numerals. 
         [0013]    A description will be first given of an outline of an image forming apparatus  10  in accordance with the exemplary embodiments of the invention. As shown in  FIGS. 1 and 2 , the image forming apparatus  10  includes a main body frame  12  detachably accommodating image carriers (photosensitive bodies)  20  and developing units  16 , and a cover  14  which is rotatable with respect to the main body frame  12 . 
         [0014]    A carrier unit  18  provided with a transport belt  34  capable of adsorbing and transporting a recording paper P is attached to the cover  14 , and the structure is made such that the carrier unit  18  faces to the image carrier  20  or is away from the image carrier  20  by rotating the cover  14 . The recording paper P in which a jamming occurs may be removed or replace consumable supplies may be exchanged by rotating the cover  14  so as to open with respect to the main body frame  12 . 
         [0015]    The developing unit  16  is provided with the roll-shaped image carrier  20  on which a latent image is formed, an charging roll  22  uniformly charging a surface of the image carrier  20 , a developing roll  26  selectively transferring a toner to the latent image formed on the image carrier  20  so as to make visible, and a cleaning member  28  coming into sliding contact with the image carrier  20  after the toner image is transferred and cleaning the toner remaining on the image carrier  20 . 
         [0016]    The image carrier  20  includes a photosensitive layer on a surface (a peripheral surface), the surface (the peripheral surface) is exposed by a laser beam (an image light) irradiated from an optical box  24  after the surface (the peripheral surface) is uniformly charged by the charging roll  22 , and an electrostatic latent image (an image) is formed on the basis of decreasing of an electric potential of the exposed portion. In this case, the charging roll  22  is brought into contact with the image carrier  20 , an electric voltage is applied therebetween, and discharging occurs within a small gap near the contact portion, thereby the charging roll  22  substantially uniformly charges the surface (the peripheral surface) of the image carrier  20 . 
         [0017]    The optical box  24  makes the laser beam, on the basis of an image data, scan on the surface (the peripheral surface) of the image carrier  20 , and forms an electrostatic latent image on the basis of the image data on the surface (the peripheral surface) of the image carrier  20 . In this case, as the optical box  24 , there may be considered another system in which light emitting devices such as LED are arranged so as to be turned on or off on the basis of the image data, in addition to the system of scanning the laser beam. 
         [0018]    The developing roll  26  is arranged so as to come close to and face to the image carrier  20 , and is structured such that a developing bias voltage is applied between the developing roll  26  and the image carrier  20 . Accordingly, a developing bias electric field is formed between the developing roll  26  and the image carrier  20 , and the toner having an electric charge is transferred to the exposed portion on the image carrier  20  so as to form a visible image. 
         [0019]    On the other hand, the carrier unit  18  is provided with a transport belt  34  which is supported in a tensional manner to at least a drive roll  30  and a driven roll  32 , and a surface of the transport belt  34  is charged, at the same time when a recording paper P is fed onto the transport belt  34 , by an electrostatic adsorption roll  35  provided near the driven roll  32 . Accordingly, the recording paper P is adsorbed in an electrostatic manner to the transport belt  34 , and is transported in accordance with a rotating movement of the transport belt  34 . In this case, the electrostatic adsorption roll  35  may be provided if necessary. 
         [0020]    Further, plural (four corresponding to each colors mentioned below) transfer rolls  36  are arranged at predetermined positions between the drive roll  30  and the driven roll  32 , in an inner surface side of the transport belt  34  so as to be spaced at a predetermined intervals therebetween. 
         [0021]    The transfer roll  36  is structured such as to face to the image carrier  20  while the transfer roll  36  and the image carrier  20  sandwich the transport belt  34  at a time when the cover  14  is closed. The transfer roll  36  transfers a toner image (an unfixed image) which is on the surface of the image carrier  20  onto the recording paper P adsorbed and transported onto the transport belt  34  so as to pass through, by forming a transfer electric field between the image carrier  20  and the transfer roll  36 . 
         [0022]    The developing units  16  are arranged in a vertical direction, for example, in the order of the yellow (Y), the magenta (M), the cyan (C) and the black (K) in such a manner that a full color printing may be carried out, and a fixing device  38  is arranged in a downstream side (an upper portion of the main body frame  12 ) in a transporting direction of the recording paper P (hereinafter, refer to as “transporting direction”), and a far side of the main body frame  12  than a transfer surface of the image carrier  20 . 
         [0023]    The fixing device  38  is provided with an substantially box-shaped casing  39 , and a heat roll  40  and a pressure roll  42  in which peripheral surfaces are faced to each other and pressure contacted (nipped) at a predetermined pressure are accommodated within the casing  39 . The toner image is fixed on the recording paper P by sandwiching the recording paper P by the heat roll  40  and the pressure roll  42  and heating and pressurizing the unfixed toner image transformed onto the recording paper P. 
         [0024]    Although an illustration is omitted, gears are provided in the heat roll  40  and the pressure roll  42 . When a driving force is transmitted to a drive gear arranged in an outer side of the casing  39  from a main motor  50  which drives a drive system, provided within the image forming apparatus  10 , the driving force is transmitted to the gears of the heat roll  40  and the pressure roll  42  from the drive gear, and the heat roll  40  and the pressure roll  42  are driven. 
         [0025]    A support portion  60  supporting the fixing device  38  is arranged within the image forming apparatus  10 . A mounting surface  60 A on which a bottom surface of the substantially box-shaped casing  39  constructing the fixing device  38  is mounted is formed in the support portion  60 , and the fixing device  38  is detachable with respect to the support portion  60 . In other words, the fixing device  38  is attached to the image forming apparatus  10  via the support portion  60 , and is structured such that the fixing device  38  stays within the image forming apparatus  10  and is exposed from the image forming apparatus  10 , at a time of opening the cover  14 . 
         [0026]    The recording paper P on which the toner image is fixed by being heated and pressurized by the fixing device  38  (the heat roll  40  and the pressure roll  42 ) is discharged onto a paper discharge tray  44  by a paper discharge roller  43 . Further, the surface (the peripheral surface) of the image carrier  20  after finishing the transfer of the toner image to the recording paper P is cleaned by the cleaning member  28 , then, waiting for the next image forming process. 
         [0027]    Further, a detachable paper cassette  46  is provided in a lower portion of the main body frame  12 . The paper cassette  46  may be drawn out in an inverse direction to a direction in which the recording paper P is fed, and the recording paper P can be supplied appropriately therein. 
         [0028]    The paper cassette  46  is provided with a sensor  52  detecting presence or not of the recording paper P, and a sensor  54  detecting a size of the recording paper P. The sensors  52  and  54  are both connected to a control unit  56 , and in a case that the recording paper P is not accommodated within the paper cassette  46  or in a case that the recording paper P accommodated within the paper cassette  46  is different from a size which a user designates by a control panel  58  or the like, the control panel  58  notifies the user of it. 
         [0029]    Further, a pair of paper feeding rollers  48  feeding the recording paper P from an inner side of the paper cassette  46  are provided in a downstream side end portion in a transporting direction of the paper cassette  46 , and the recording paper P fed from the pair of paper feeding rollers  48  is fed to an adsorption transport surface of the transport belt  34  at a predetermined timing by registering rolls  49 , and is transported to a transfer position of the toner image of each of the colors. 
         [0030]    Further, the images formed on the image carrier  20  are transferred to the recording paper P one by one by the transfer rolls  36 , and the recording paper P is fed in the fixing device  38 . At this time, a path, which is constructed by the transport belt  34  and the image carrier  20  and along which the recording paper P is transported, forms a paper transport path. The structure is made such that when the cover  14  is opened, the carrier unit  18  is moved together with the cover  14 , and the paper transport path is opened. 
         [0031]    A sensor  62  is provided at a position in a downstream side in the transporting direction than a position in which the registering rolls  49  are provided in the paper transport path. The sensor  62  is connected to the control unit  56 , and it is determined, on the basis of an elapsed time after a leading end of the recording paper P is detected by the sensor  62  that the leading end of the recording paper P enters into a nip portion between the heat roll  40  and the pressure roll  42  of the fixing device  38 . 
         [0032]    The registering rolls  49  are structured such that a driving force is transmitted from a main motor  50  provided within the image forming apparatus  10  in the same manner as the heat roll  40  and the pressure roll  42 . Accordingly, when the driving of the main motor  50  is stopped, the rotational drive of the registering rolls  49  is stopped together with the heat roll  40  and the pressure roll  42 . 
         [0033]    In the image forming apparatus  10  having the structure mentioned above in which a device check operation is operatable, in a case that the paper wrinkle is generated in the recording paper P discharged from the image forming apparatus  10 , the user carries out a paper wrinkle determination Mode A from the control panel  58  of the image forming apparatus  10  or a user interface screen of a personal computer. Accordingly, the paper wrinkle determination Mode A is executed in the image forming apparatus  10 . 
         [0034]    When the paper wrinkle determination Mode A is executed, presence or not and the size of the recording paper P within the paper cassette  46  are detected by the sensors  52  and  54  provided in the paper cassette  46 . 
         [0035]    In a case that the recording paper P is not accommodated within the paper cassette  46 , or the size of the accommodated recording paper P is not a maximum size (in this case, the maximum size is to A4 (length 297 mm, width 210 mm) or a letter size (length 279 nm, width 216 mm)), a message “set A4 or letter size paper to cassette” is displayed on the control panel  58 . 
         [0036]    Since the image forming apparatus  10  described here is of a compact size used in a personal residence, and the maximum size of the used recording paper P is A4 or letter size, a distance between the registering rolls  49  and the fixing device  38  is set to a dimension in a vertical (longitudinal) direction of the A4 paper or a size in a vertical (longitudinal) direction of the letter size paper. 
         [0037]    In a case it is detected that the recording paper P is accommodated within the paper cassette  46  and the accommodated recording paper P is the maximum size, the main motor  50  is driven in accordance with a signal from the control unit  56 . Further, one recording paper P is picked up from the paper cassette  46  by the pair of paper feeding rollers  48 , and is fed in the paper transport path by the registering rolls  49 . 
         [0038]    At this time, in the paper wrinkle determination Mode A, an actual printing motion is carried out, and a voltage is applied to the transfer roll  36 , however, since an electrostatic latent image of a white date (a data corresponding to a margin (a blank space)) (blank data) is formed on the surface of the image carrier  20 , the image is not actually transferred on the recording paper P from the image carrier  20 . 
         [0039]    Further, the driving of the main motor  50  is stopped at a time when the leading end of the recording paper P (the downstream side end portion in the transporting direction of the recording paper P) is nipped by the heat roll  40  and the pressure roll  42 . Accordingly, the recording paper P stops on the paper transport path in a state in which the leading end is nipped by the heat roll  40  and the pressure roll  42  and a rear end (an upstream side end portion in the transporting direction of the recording paper P) is nipped by the registering rolls  49 . 
         [0040]    When the recording paper P stops on the paper transport path, a message that the cover  14  can be opened and closed is displayed on the control panel  58 . In this case, if the user opens the cover  14 , a state of the recording paper P on the opened paper transport path is confirmed by the user. 
         [0041]    At this time, since the recording paper P enters into the nip portion of the heat roll  40  and the pressure roll  42  of the fixing device  38  only at the leading end thereof if the paper wrinkle is generated in the recording paper P as shown in  FIG. 3A , it may be specified that the cause of the paper wrinkle generation exists in the registering rolls  49  (at the image forming apparatus  10  side) such as that the registering rolls  49  are not arranged at the normal position or the like. 
         [0042]    Further, since the recording paper P passes through the registering rolls  49  approximately over a whole region thereof except for the rear end thereof, if the paper wrinkle is not generated in the recording paper P as shown in  FIG. 3B , it may be specified that the cause of the paper wrinkle generation does not exist in the registering rolls  49 , rather, exists in the fixing device  38  such as that the heat roll  40  through which the recording paper P passes in the subsequent process is not arranged at the normal position. 
         [0043]    If the cause of the paper wrinkle generation exists in the registering rolls  49  (at the image forming apparatus  10  side), the user may send the image forming apparatus  10  main body to the manufacturer or the store, and if the cause exists in the fixing device  38  side, the user may send only the fixing device  38 , by detaching it from the image forming apparatus  10  main body, to the manufacturer or the store. 
         [0044]    Accordingly, it is not necessary to send for repair the image forming apparatus  10  main body, which is not necessary to be repaired, for example, in spite of the cause of the paper wrinkle generation existing in the fixing device  38  side. 
         [0045]    In the present exemplary embodiment, the description is given of the structure in which whether or not the leading end of the recording paper P reaches the fixing device  38  is detected by counting an elapsed time after detecting the leading end of the recording paper P fed out from the paper cassette  46  by means of the sensor  62  provided near the registering rolls  49  of the paper transport path. However, the structure may be made such as to detect whether or not the leading end of the recording paper P in the transporting direction reaches the registering rolls  49  or the fixing device  38  by counting an elapsed time after the recording paper P is fed out from the paper cassette  46  by means of the pair of paper feeding rollers  48 . 
         [0046]    Further, in the present exemplary embodiment, the structure is made such as to stop the transport of the recording paper P by stopping driving of the main motor  50  at a time when the leading end of the recording paper P is nipped by the fixing device  38  and the rear end thereof is nipped by the registering rolls  49 . However, it is not always necessary to set the state in which the recording paper P is nipped by the fixing device  38  and the registering rolls  49 , for example, the structure may be made such as to stop the transport of the recording paper P at a time when the leading end of the recording paper P is nipped by the pair of transport rollers which is located before the fixing device  38  and the rear end thereof is nipped by the paper feeding rollers  48 . As mentioned above, the timing for stopping the transport of the recording paper P is not limited to the structure mentioned above. 
         [0047]    Next, a description will be given of an image forming apparatus in accordance with a second exemplary embodiment of the invention. In this case, the same reference numerals as the first exemplary embodiment are attached to the same structures as the first exemplary embodiment, and a description thereof will be omitted. 
         [0048]    The image forming apparatus in accordance with the second exemplary embodiment is provided with a paper wrinkle Mode B as is different form the image forming apparatus  10  in accordance with the first exemplary embodiment. Further, if the paper wrinkle determination Mode B is executed, presence or not and the size of the recording paper P within the paper cassette  46  are detected by the sensors  52  and  54  provided in the paper cassette  46 . 
         [0049]    In a case that the recording paper P having a predetermined size (in this case, the predetermined size is set to A4) is not accommodated within the paper cassette  46 , a message “paper within cassette is not maximum paper size” is displayed on the control panel  58 . 
         [0050]    In this case, if the user selects “No”, the paper wrinkle determination Mode B is finished, and if the user selects “Yes”, the main motor  50  is driven on the basis of a signal from the control unit  56 . Then, one recording paper P is picked up from the paper cassette  46  by the pair of paper feeding rollers  48  so as to be fed in the paper transport path by the registering rolls  49 . 
         [0051]    Further, as shown in  FIG. 4 , the driving of the main motor  50  is stopped at a time when the leading end of the recording paper P is nipped by the heat roll  40  and the pressure roll  42 . In this case, since the size (smaller than A4) of the recording paper P is smaller than the distance between the registering rolls  49  and the fixing device  38 , the recording paper P stops in a state in which the rear end of the recording paper P has already passed through the registering rolls  49  and has not nipped by the registering rolls  49 . 
         [0052]    If the recording paper P stops on the paper transport path, a message that the cover  14  can be opened and closed is displayed on the control panel  58 . In this case, if the user opens the cover  14 , the state of the recording paper P on the opened paper transport path is confirmed by the user. 
         [0053]    At this time, since the recording paper P enters into the nip portion of the heat roll  40  and the pressure roll  42  of the fixing device  38  only at the leading end thereof, if the paper wrinkle is generated in the recording paper P, it may be specified that the cause of the paper wrinkle generation exists in the registering rolls  49  (at the image forming apparatus  10  side) such as that the registering rolls  49  are not arranged at the normal position or the like. 
         [0054]    Further, since the recording paper P passes through the registering rolls  49  approximately over a whole region thereof, if the paper wrinkle is not generated in the recording paper P, it may be specified that the cause of the paper wrinkle generation does not exist in the registering rolls  49 , rather, exists in the fixing device  38  such as that the heat roll  40  through which the recording paper P passes in the subsequent process is not arranged at the normal position. 
         [0055]    Next, a description will be given of an image forming apparatus in accordance with a third exemplary embodiment of the invention. In this case, the same reference numerals as the first exemplary embodiment are attached to the same structures as the first exemplary embodiment and the second exemplary embodiment, and a description thereof will be omitted. 
         [0056]    The image forming apparatus in accordance with the third exemplary embodiment is provided with a paper wrinkle Mode C. Further, if the paper wrinkle Mode C is executed, the driving of the main motor  50  is stopped at a time just before the rear end of the recording paper P is released from the registering rolls  49 , as shown in  FIG. 5 . 
         [0057]    In this case, since the size of the recording paper P is smaller than the distance between the registering rolls  49  and the fixing device  38 , the recording paper P stops in a state in which the leading end of the recording paper P does not enter into the fixing device  38 . 
         [0058]    If the recording paper P stops on the paper transport path, a message that the cover  14  can be opened and closed is displayed on the control panel  58 . In this case, when the user opens the cover  14 , the recording paper P is exposed in a state in which the rear end is nipped by the registering rolls  49  and the other portion of the recording paper P is adsorbed to the adsorption transport surface of the transport belt  34 . Further, the state of the exposed recording paper P is confirmed by the user. 
         [0059]    At this time, since the recording paper P does not enter into the nip portion of the heat roll  40  and the pressure roll  42  of the fixing device  38 , if the paper wrinkle is generated in the recording paper P, it may be specified that the cause of the paper wrinkle generation exists in the registering rolls  49  (at the image forming apparatus  10  side) such as that the registering rolls  49  are not arranged at the normal position or the like. 
         [0060]    Further, since the recording paper P passes through the registering rolls  49  approximately over a whole region, if the paper wrinkle is not generated in the recording paper P, it may be specified that the cause of the paper wrinkle generation does not exist in the registering rolls  49 , rather, exists in the fixing device  38  such as that the heat roll  40  through which the recording paper P passes in the subsequent process is not arranged at the normal position. 
         [0061]    Next, a description will be given of an image forming apparatus in accordance with a fourth exemplary embodiment of the invention. In this case, the same reference numerals as the first exemplary embodiment are attached to the same structures as the first exemplary embodiment, and a description thereof will be omitted. 
         [0062]    The image forming apparatus in accordance with the fourth exemplary embodiment is provided with a paper wrinkle Mode D. Further, if the paper wrinkle determination Mode D is executed, the driving of the main motor  50  is stopped at a time which is before the leading end of the recording paper P enters into the nip portion of the heat roll  40  and the pressure roll  42  and when the rear end of the recording paper P nipped and transported by the registering rolls  49  is released from the registering rolls  49 , as shown in  FIG. 6 . In other words, the transport of the recording paper P is stopped between the fixing device  38  and the registering rolls  49 , in a state in which the leading end is not nipped by the heat roll  40  and the pressure roll  42  and the rear end of the recording paper P is not nipped by the registering rolls  49 . 
         [0063]    If the recording paper P stops on the paper transport path, a message that the cover  14  can be opened and closed is displayed on the control panel  58 . In this case, when the user opens the cover  14 , the recording paper P is exposed in a state in which the recording paper P is adsorbed to the adsorption surface of the transport belt  34  which is moved integrally with the cover  14 . Further, the state of the exposed recording paper P is confirmed by the user. 
         [0064]    At this time, since the recording paper P does not charge into the nip portion of the heat roll  40  and the pressure roll  42  of the fixing device  38 , if the paper wrinkle is generated in the recording paper P, it may be specified that the cause of the paper wrinkle generation exists in the registering rolls  49  (at the image forming apparatus  10  side) such as that the registering rolls  49  are not arranged at the normal position or the like. 
         [0065]    Further, since the recording paper P passes through the registering rolls  49  over a whole region, if the paper wrinkle is not generated in the recording paper P, it may be specified that the cause of the paper wrinkle generation does not exist in the registering rolls  49 , rather, exists in the fixing device  38  such as that the heat roll  40  through which the recording paper P passes in the subsequent process is not arranged at the normal position. 
         [0066]    Next, a description will be given of an image forming apparatus in accordance with a fifth exemplary embodiment of the invention. In this case, the same reference numerals as the first exemplary embodiment are attached to the same structures as the first exemplary embodiment, and a description thereof will be omitted. 
         [0067]    The image forming apparatus in accordance with the fifth exemplary embodiment is provided with a paper wrinkle Mode E. Further, as shown in  FIG. 7 , a line  64  is provided near one end portion of the transport belt  34  in parallel to the end portion of the transport belt  34  (the transporting direction of the recording paper P). The line  64  is provided so as to be positioned in an outer side than the end portion of the maximum paper size, and is drawn in a white color with respect to the black colored transport belt  34 . 
         [0068]    If the paper wrinkle Mode E is executed, the driving of the main motor  50  is stopped at a time just before the leading end of the recording paper P enters into the fixing device  38  and in a state in which the rear end of the recording paper P is nipped by the registering rolls  49 , and a message that the cover  14  can be opened and closed is displayed on the control panel  58 . 
         [0069]    In this state, when the user opens the cover  14 , the recording paper P is exposed in a state in which recording paper P is adsorbed by the adsorption transport surface of the transport belt  34 , because the leading end of the recording paper P is not nipped by the heat roll  40  and the pressure roll  42  of the fixing device  38 . Further, the state of the exposed recording paper P is confirmed by the user. 
         [0070]    At this time, if the paper wrinkle is generated in the recording paper P, it may be specified that the cause of the paper wrinkle generation exists in the registering rolls  49  (at the image forming apparatus  10  side) such as that the registering rolls  49  are not arranged at the normal position or the like. 
         [0071]    Further, since the recording paper P passes through the registering rolls  49  approximately over a whole region, if the paper wrinkle is not generated in the recording paper P, it may be specified that the cause of the paper wrinkle generation does not exist in the registering rolls  49 , rather, exists in the fixing device  38  such as that the heat roll  40  through which the recording paper P passes in the subsequent process is not arranged at the normal position. 
         [0072]    However, if the recording paper P is loosened or placed bent with respect to the transporting direction at a time point before entering into the fixing device  38 , there is a case that the paper wrinkle is generated in the recording paper P entering into the fixing device  38 . 
         [0073]    Accordingly, the user checks not only whether or not the paper wrinkle is generated in the exposed recording paper P by the cover  14  being opened, but also whether or not the line  64  provided in the transport belt  34  is in parallel to the end portion of the exposed recording paper P by the cover  14  being opened. 
         [0074]    In other words, the user checks whether or not a distance M between the leading end portion (the end portion positioned in the driving roll  30  side in the downstream side end portion in the transporting direction) of the recording paper P and the line  64 , and a distance N between the rear end portion (the end portion positioned in the driven roll  32  side in the upstream side end portion in the transporting direction) and the line  64  exist within a predetermined range (2 mm in the present exemplary embodiment). 
         [0075]    If the paper wrinkle is not generated in the recording paper P, and the distances M and N both exist within the predetermined range, at a time of opening the cover  14  to observe the exposed recording paper P, it may be specified that the cause of the paper wrinkle generation exists in the fixing device  38 . 
         [0076]    Further, in a case that at least one of the distances M and N does not exist within the predetermined range, it may be specified that the cause of the paper wrinkle generation exists in the registering rolls  49  (at the image forming apparatus  10  side) such as that the registering rolls  49  or the pair of paper feeding rollers  48  are not arranged at the normal position. 
         [0077]    In this case, in the present exemplary embodiment, the description is given of the structure in which the line  64  is provided near one end portion of the transport belt  34 , however, the lines  64  may be provided in the end portions in both sides of the transport belt  34 . 
         [0078]    Further, in a case that the distance between the registering rolls  49  and the fixing device  38  is larger than the size in the vertical direction of the used recording paper P, the transport of the recording paper P is stopped between the fixing device  38  and the registering rolls  49 . Accordingly, since the recording paper P is exposed in the state in which the recording paper P is adsorbed to the adsorption surface of the transport belt  34  which is moved integrally with the cover  14 , at a time of opening the cover  14 , it is easy to check the distance between the end portion of the recording paper P and the line.