Patent Publication Number: US-2022229384-A1

Title: Image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of International Application No. PCT/JP2020/029609 filed on Aug. 3, 2020, and claims priority from Japanese Patent Application No. 2020-030520 filed on Feb. 26, 2020. 
    
    
     BACKGROUND 
     Technical Field 
     The present invention relates to an image forming apparatus. 
     Related Art 
     JP-A-2003-140488 discloses an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus including an image heating device, and the image heating device. In the related art, the image forming apparatus includes a fixing device that forms a fixing nip unit by pressing a fixing roller and a pressurizing member that are rotatably disposed to each other, and fixes, by the fixing nip unit, a toner image to a transfer material while gripping and transporting the transfer material to which the toner image is transferred. The image forming apparatus includes a stop mode in which a transfer material transporting operation stop timing to the fixing device and a transfer material transporting operation stop timing of the fixing device are different. 
     JP-A-2009-139670 discloses an image forming apparatus capable of switching between a full-color mode and a black monochrome mode, and more specifically, control for improving a transfer performance in a black monochrome mode without impairing a transfer performance in a full-color mode. In the related art, in the black monochrome mode, an intermediate transfer belt is separated from a photoconductive drum on an upstream side in a state where the photosensitive drum is in contact with the intermediate transfer belt. At this time, a tension roller is raised in interlocking with a contact-separation mechanism, and a winding angle of the intermediate transfer belt with respect to the photoconductive drum is made larger than that in the full-color mode. On the other hand, in the full-color mode, the tension roller is lowered, and separated from an inner surface of the intermediate transfer belt. 
     Japanese Patent No. 5538788 discloses an image forming apparatus such as a copying machine or a printer that performs image formation by an electrophotographic method. In the related art, the image forming apparatus includes an image carrier that carries a toner image, a belt that transfers the toner image formed on the image carrier to a transfer material, and a transfer member that is separable from the belt. When the transfer member is to be separated from the belt, the transfer member is separated from the belt after the belt rotating at a first speed is changed to a second speed lower than the first speed. 
     SUMMARY 
     When an abnormality such as a jam of a recording medium is detected and an image forming apparatus is to be stopped, it may be desired to continue rotational driving of a transfer member even if the abnormality is detected and to stop the image forming apparatus after the recording medium is transported to a downstream side in order to easily remove the recording medium. 
     However, when an image holder such as an intermediate transfer belt is in contact with the transfer member, rotational driving of the image holder is also continued until the rotational driving of the transfer member is stopped, so that a load on the image holder is increased. 
     Aspects of non-limiting embodiments of the present disclosure relate to stopping, when an abnormality is detected and an image forming apparatus is to be stopped, rotational driving of an image holder at an early stage as compared with a case where the transfer member and the image holder are in contact with each other until the rotational driving of the transfer member is stopped. 
     Aspects of certain non-limiting embodiments of the present disclosure address the above advantages and/or other advantages not described above. However, aspects of the non-limiting embodiments are not required to address the advantages described above, and aspects of the non-limiting embodiments of the present disclosure may not address advantages described above. 
     According to an aspect of the present disclosure, there is provided an image forming apparatus including: a colorant image former; an image holder configured to hold a colorant image formed by the colorant image forming unit and to be rotationally driven; a transfer member configured to transfer the colorant image onto a recording medium, which is transported from an upstream side, by sandwiching the recording medium between the transfer member and the image holder, and rotationally driving the transfer member to transport the recording medium to a downstream side; and a contact-and-separation mechanism configured to relatively contact or separate the image holder and the transfer member, in which, in response to an abnormality being detected, the image forming apparatus operates in a mode in which the contact-and-separation mechanism relatively separates the image holder and the transfer member, and then rotational driving of the transfer member is stopped after rotational driving of the image holder is stopped. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Exemplary embodiment(s) of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a schematic view of an image forming apparatus according to a first exemplary embodiment; 
         FIG. 2  is a schematic view showing a state in which a secondary transfer roller of the image forming apparatus according to the first exemplary embodiment in  FIG. 1  is separated from an intermediate transfer belt; 
         FIG. 3  is a block diagram of the image forming apparatus according to the first exemplary embodiment; 
         FIG. 4  is a flowchart of an operation at the time of abnormality detection of the image forming apparatus according to the first exemplary embodiment; 
         FIG. 5  is a block diagram of an image forming apparatus according to a modification of the first exemplary embodiment; 
         FIG. 6  is a flowchart of an operation at the time of abnormality detection of the image forming apparatus according to the modification of the first exemplary embodiment; 
         FIG. 7  is a schematic view of an image forming apparatus according to a second exemplary embodiment; 
         FIG. 8  is a schematic view showing a state in which a transfer cylinder of the image forming apparatus according to the second exemplary embodiment in  FIG. 7  is separated from an intermediate transfer belt; 
         FIG. 9  is a perspective view showing a secondary transfer body and a part of a transport unit of the image forming apparatus according to the second exemplary embodiment; 
         FIG. 10  is a perspective view showing a fixing unit and a part of the transport unit of the image forming apparatus according to the second exemplary embodiment; 
         FIG. 11  is a perspective view showing a part of the transport unit of the image forming apparatus according to the second exemplary embodiment; 
         FIG. 12  is a schematic view of a non-contact heating unit in an open state of a shielding member; 
         FIG. 13  is a schematic view of the non-contact heating unit in a closed state of the shielding member; 
         FIG. 14  is a block diagram of the image forming apparatus according to the second exemplary embodiment; 
         FIG. 15  is a flowchart of an operation at the time of abnormality detection of the image forming apparatus according to the second exemplary embodiment; 
         FIG. 16  is a flowchart of an operation at the time of abnormality detection of an image forming apparatus according to a first modification of the second exemplary embodiment; 
         FIG. 17  is a flowchart of an operation at the time of abnormality detection of an image forming apparatus according to a second modification of the second exemplary embodiment; 
         FIG. 18  is a schematic view of the image forming apparatus according to the second modification of the second exemplary embodiment; and 
         FIG. 19  is a flowchart of an operation at the time of abnormality detection of the image forming apparatus according to the second modification of the second exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     First Exemplary Embodiment 
     An example of an image forming apparatus according to a first exemplary embodiment of the present invention will be described. 
     [Apparatus Configuration] 
     First, an apparatus configuration of the image forming apparatus will be described. 
     (Overall Configuration of Image Forming Apparatus) 
     An image forming apparatus  100  shown in  FIG. 1  is an example of an image forming apparatus that forms an image on a recording medium. The image forming apparatus  100  is an electrophotographic image forming apparatus that forms a toner image as an example of a colorant image on a recording medium P such as a sheet. Specifically, the image forming apparatus  100  includes an image forming unit  14 , a first transport body  11 , and a fixing device  116 . Hereinafter, a configuration of each unit of the image forming apparatus  100  will be described. 
     (Image Forming Unit) 
     The image forming unit  14  is an example of a forming unit that forms an image on a recording medium. Specifically, the image forming unit  14  has a function of forming a toner image to the recording medium P as an example of a material to be transported. More specifically, the image forming unit  14  includes toner image forming units  22  and a transfer device  117 . 
     (Toner Image Forming Unit) 
     The toner image forming unit  22  as an example of a colorant image forming unit shown in  FIGS. 1 and 2  has a function of forming a toner image. Plural toner image forming units  22  are provided to form a toner image for each color. In the present exemplary embodiment, the toner image forming units  22  are provided for four colors in total: the toner image forming unit  22 Y for yellow, the toner image forming unit  22 M for magenta, the toner image forming unit  22 C for cyan, and the toner image forming unit  22 K for black as shown in  FIG. 1 . 
     Since the toner image forming unit  22  of each color has the same configuration except for a toner to be used, on behalf of the toner image forming unit  22  of each color, each part of the toner image forming unit  22 Y is denoted by a reference numeral in  FIG. 1 . 
     Specifically, the toner image forming unit  22  of each color includes a photoconductor drum  32  (photoconductor) that rotates in one direction (for example, in a counterclockwise direction in  FIG. 1 ). Further, the toner image forming unit  22  of each color includes a charging unit  23 , an exposure device  36 , and a developing device  38 . 
     In the toner image forming unit  22  of each color, the charging unit  23  charges the photoconductor drum  32 . Further, the exposure device  36  exposes the photoconductor drum  32  charged by the charging unit  23  to form an electrostatic latent image on the photoconductor drum  32 . The developing device  38  develops the electrostatic latent image formed on the photoconductor drum  32  by the exposure device  36  to form a toner image. 
     (Transfer Device) 
     The transfer device  117  shown in  FIGS. 1 and 2  is a device that transfers the toner image formed by the toner image forming unit  22  to the recording medium P. The transfer device  117  includes an intermediate transfer belt  24 , primary transfer rollers  26 , a secondary transfer roller  127 , a facing roller  42 A, and a contact-and-separation mechanism  150  (hereinafter called a contact/separation mechanism  150 ). The transfer device  17  superimposes and primarily transfers the toner image of the photoconductor drum  32  of each color to the intermediate transfer belt  24  as an intermediate transfer body, and secondarily transfers the superimposed toner image to the recording medium P at a secondary transfer position T 2 . 
     (Primary Transfer Roller) 
     Each of the primary transfer rollers  26  shown in  FIGS. 1 and 2  is a roller that transfers the toner image of the photoconductor drum  32  of each color to the intermediate transfer belt  24  at a primary transfer position T 1  between the photoconductor drum  32  and the primary transfer roller  26 . In the present exemplary embodiment, the toner image formed on the photoconductor drum  32  is transferred to the intermediate transfer belt  24  at the primary transfer position T 1  by applying a primary transfer electric field between the primary transfer roller  26  and photoconductor drum  32 . 
     (Intermediate Transfer Belt) 
     The toner image is transferred from the photoconductor drum  32  of each color to an outer circumferential surface of the intermediate transfer belt  24  as an example of an image holder shown in  FIGS. 1 and 2 . Specifically, the intermediate transfer belt  24  is configured as follows. As shown in  FIG. 1 , the intermediate transfer belt  24  has an annular shape. Further, the intermediate transfer belt  24  is wound around plural rollers  42  including a driving roller  42 D and the facing roller  42 A, and a posture of the intermediate transfer belt  24  is determined. The intermediate transfer belt  24  rotates in a predetermined direction indicated by an arrow A by, for example, rotationally driving the driving roller  42 D among the plural rollers  42 . 
     (Secondary Transfer Roller and Facing Roller) 
     The secondary transfer roller  127  as an example of a transfer member shown in  FIGS. 1 and 2  has a function of transferring a toner image to the recording medium P. The secondary transfer roller  127  is rotationally driven in a direction indicated by an arrow B. 
     The secondary transfer roller  127  and the facing roller  42 A are disposed to face each other with the intermediate transfer belt  24  interposed therebetween. In the present exemplary embodiment, the secondary transfer position T 2  at which the toner image is to be transferred from the intermediate transfer belt  24  to the recording medium P is formed between the secondary transfer roller  127  and the facing roller  42 A. When a secondary transfer electric field is applied between the secondary transfer roller  127  and the facing roller  42 A, the toner image primarily transferred to the intermediate transfer belt  24  is secondarily transferred to the recording medium P at the secondary transfer position T 2 . 
     (Contact/Separation Mechanism) 
     The contact/separation mechanism  150  shown in  FIGS. 1 and 2  has a function of moving the secondary transfer roller  127 . Specifically, the contact/separation mechanism  150  moves the secondary transfer roller  127  between a contact state shown in  FIG. 1  in which the secondary transfer roller  127  is in contact with the intermediate transfer belt  24  and a separated state shown in  FIG. 2  in which the secondary transfer roller  127  is separated from the intermediate transfer belt  24 . The contact/separation mechanism  150  is provided with a cam  152  and a contact-and-separation motor  130  (hereinafter called a contact/separation motor  130 ) for rotating the cam  152 . The cam  152  is in contact with a shaft  127 A of the secondary transfer roller  127 , and the cam  152  rotates to move the secondary transfer roller  127 . In the contact/separation mechanism  150 , a rotation position of the cam  152  may be detected by an optical sensor (not shown). Accordingly, a contact state or a separation state of the secondary transfer roller  127  is monitored. 
     The contact/separation mechanism  150  is a mechanism that moves the secondary transfer roller  127  in a state of being rotationally driven. That is, even in the separated state shown in  FIG. 2  in which the secondary transfer roller  127  is separated from the intermediate transfer belt  24 , the secondary transfer roller  127  may be rotationally driven. An example is a mechanism in which a driving unit and the secondary transfer roller  127  are integrally moved. However, if the driving unit is configured to be able to rotate the secondary transfer roller  127  even in the separated state in which the secondary transfer roller  127  is separated from the intermediate transfer belt  24 , the driving unit does not necessarily need to be moved together with the secondary transfer roller  127 . 
     (Transport Device) 
     A transport device  111  shown in  FIGS. 1 and 2  has a function of transporting the recording medium P transported from an upstream side to the secondary transfer position T 2  described above. The transport device  111  includes an annular transport belt  111 B wound around a pair of rolls  111 A. 
     (Fixing Device) 
     The fixing device  116  as an example of a fixing unit shown in  FIGS. 1 and 2  has a function of fixing a toner image transferred to the recording medium P. The fixing device  116  includes a heating roller  168  and a pressurizing roller  169 . The heating roller  168  includes a heating source  168 A such as a halogen lamp. The heating roller  168  forms a fixing region T 3  in which the recording medium P is sandwiched between the heating roller  168  and the pressurizing roller  169 , and heats a toner image in a state in which the recording medium P is sandwiched between the heating roller  168  and the pressurizing roller  169  at the fixing region T 3 , and fixes the toner image to the recording medium P. 
     (Sheet Sensor) 
     A sheet sensor  102  is provided on a downstream side of the recording medium P of the fixing device  116  in a transporting direction shown in  FIGS. 1 and 2 . The sheet sensor  102  detects the recording medium P discharged from the fixing device  116 . In the present exemplary embodiment, the sheet sensor  102  uses an optical sensor capable of detecting a leading end portion and trailing end portion of the recording medium P. 
     (Drive Mechanism) 
     As shown in  FIG. 3 , the image forming apparatus  100  includes a drive mechanism  120 . The drive mechanism  120  has a function of driving various members of the image forming apparatus  100 . The drive mechanism  120  includes a photoconductor motor  122  that rotationally drives the photoconductor drum  32  of each color (see  FIGS. 1 and 2 ), an intermediate transfer motor  124  that rotationally drives the driving roller  42 D (see  FIGS. 1 and 2 ) of the intermediate transfer belt  24  (see  FIGS. 1 and 2 ), a transfer roller motor  126  that rotationally drives the secondary transfer roller  127  (see  FIGS. 1 and 2 ), a fixing motor  128  that rotationally drives the pressurizing roller  169  (see  FIGS. 1 and 2 ) of the fixing device  116  (see  FIGS. 1 and 2 ), and the contact/separation motor  130  that drives the contact/separation mechanism  150  (see  FIGS. 1 and 2 ). 
     (Abnormality Detection Device) 
     As shown in  FIG. 3 , the image forming apparatus  100  includes an abnormality detection device  99  that detects various abnormalities. The abnormality detection device  99  includes a jam sensor  98 . The jam sensor  98  is provided at plural positions of a transporting path of the recording medium P (see  FIGS. 1 and 2 ), and detects that the recording medium P (see  FIGS. 1 and 2 ) is jammed or the like and is not appropriately transported, that is, a so-called jam occurs. The abnormality detection device  99  includes an abnormality detection sensor (not shown) in addition to the jam sensor  98 . Abnormalities other than the jam are detected, for example, when a user opens a door of a body (not shown) in order to observe an inside of the image forming apparatus  100  even during printing, when a toner necessary for image formation is run out, when it is time to replace a component constituting the image forming apparatus, or when a positional deviation of the intermediate transfer belt  24  is detected. The abnormalities other than the jam are detected when an abnormality occurs in a torque of various motors, when an abnormality occurs in the contact or the separation by the optical sensor for monitoring the contact state or the separation state of the secondary transfer roller  127 , or the like. 
     (Control Device) 
     A control device  104  shown in  FIG. 3  has a function of controlling the entire image forming apparatus  100 . A hardware configuration of the control device  104  includes a computer including a central processing unit (CPU) (not shown), a read only memory (ROM) that stores a program or the like for realizing each processing routine, a random access memory (RAM) that temporarily stores data, a memory as a storage means, a network interface, and the like. 
     The photoconductor motor  122 , the intermediate transfer motor  124 , the transfer roller motor  126 , the fixing motor  128 , and the contact/separation motor  130  constituting the drive mechanism  120  are electrically connected to the control device  104 . 
     The exposure device  36  for each color, the jam sensor  98 , and the sheet sensor  102  are electrically connected to the control device  104 . 
     [Operation at the Time of Abnormality Detection] 
     Next, an operation of the image forming apparatus  100  when the abnormality detection device  99  detects an abnormality will be described. 
       FIG. 4  is a flowchart showing an example of a flow of the operation of the image forming apparatus  100  at the time of abnormality detection executed by the CPU (not shown) of the control device  104 . A program is stored in advance in, for example, the ROM (not shown) of the control device  104 . The CPU (not shown) of the control device  104  reads the program stored in the ROM (not shown), and executes the operation of the image forming apparatus  100  at the time of abnormality detection. 
     In the present operation, when the abnormality detection device  99  detects an abnormality, the recording medium P is controlled not to be transported to the secondary transfer position T 2  in a case where the recording medium P is present on an upstream side of the secondary transfer position T 2 . 
     In step S 110 , the abnormality detection device  99  detects an abnormality, and in the present example, the jam sensor  98  detects a jam of the recording medium P. 
     In step S 112 , the contact/separation motor  130  is driven to separate the secondary transfer roller  127  from the intermediate transfer belt  24 . 
     In step S 114 , the exposure by the exposure device  36  is stopped. In step S 116 , the driving of the photoconductor motor  122  is stopped to stop the rotation of the photoconductor drum  32 . In step S 118 , the driving of the intermediate transfer motor  124  is stopped to stop the rotation of the intermediate transfer belt  24 . Step S 114 , step S 116 , and step S 118  may be performed at the same time. In particular, step S 116  and step S 118  may be performed at the same time. 
     In step S 120 , it is determined whether the sheet sensor  102  provided on a downstream side of the fixing device  116  detects the trailing end portion of the recording medium P. When the trailing end portion of the recording medium P is not detected, the process proceeds to step S 121 . When the trailing end portion of the recording medium P is detected, the process proceeds to step S 122 . 
     Here, when the abnormality detection device  99  detects an abnormality, the present operation is performed for the recording medium P on a most upstream side in a case where plural recording media P are present between the secondary transfer position T 2  and the fixing region T 3 . 
     In step S 121 , it is determined whether a predetermined set time is elapsed from the abnormality detection. When the set time is not elapsed, the process returns to step S 120 . When the set time is elapsed, the process proceeds to step S 122 . 
     In step S 122 , the driving of the transfer roller motor  126  is stopped, and the rotation of the secondary transfer roller  127  is stopped. Then, in step S 124 , the driving of the fixing motor  128  is stopped to stop the fixing device  116 . Step S 122  and step S 124  may be performed at the same time. That is, the secondary transfer roller  127  and the fixing device  116  may be stopped at the same time. 
     From another point of view, a command for stopping the driving of the intermediate transfer motor  124  may be issued after a command for driving the contact/separation motor  130  is issued, and a command for stopping the driving of the transfer roller motor  126  may be issued after the command for stopping the driving of the intermediate transfer motor  124  is issued. Accordingly, the rotation of the intermediate transfer belt  24  is stopped after the secondary transfer roller  127  is separated from the intermediate transfer belt  24 , and the rotation of the secondary transfer roller  127  is stopped after the rotation of the intermediate transfer belt  24  is stopped. Conversely, the command for stopping the driving of the transfer roller motor  126  is not issued before the command for stopping the driving of the intermediate transfer motor  124  is issued. Similarly, the command for stopping the driving of the intermediate transfer motor  124  is not issued until the command for driving the contact/separation motor  130  is issued. 
     When an abnormality is detected and the image forming apparatus  100  is to be stopped, the secondary transfer roller  127  is separated from the intermediate transfer belt  24 , so that the rotational driving of the photoconductor drum  32  and the intermediate transfer belt  24  may be stopped at an early stage, and the rotational driving of the secondary transfer roller  127  may be continuously performed. 
     By stopping the rotational driving of the photoconductor drum  32  and the intermediate transfer belt  24  at an early stage, a load on the photoconductor drum  32  and the intermediate transfer belt  24  is reduced. 
     Even after the secondary transfer roller  127  is separated from the intermediate transfer belt  24 , the driving of secondary transfer roller  127  and the fixing device  116  is continued, so that the recording medium P is transported to a downstream side of the secondary transfer position T 2 . Therefore, it is easy to remove the recording medium P. Further, after the sheet sensor  102  provided on the downstream side of the fixing device  116  detects the trailing end portion of the recording medium P, the fixing device  116  is stopped, that is, the fixing device  116  is stopped after the recording medium P is discharged from the fixing device  116 . Therefore, the recording medium P to which the toner image is fixed may be removed. 
     As described above, the rotational driving of the photoconductor drum  32  and the intermediate transfer belt  24  may be stopped at an early stage as compared with a case where the secondary transfer roller  127  and the intermediate transfer belt  24  are in contact with each other until the rotational driving of the secondary transfer roller  127  is stopped, and thus the load on the photoconductor drum  32  and the intermediate transfer belt  24  is reduced. 
     The recording medium P to which the toner image is fixed may be removed as compared with a case where the rotational driving of the fixing device  116  is stopped before the trailing end portion of the recording medium P passes through the fixing device  116 , and thus the recording medium P may be easily removed. 
     [Modification] 
     Next, a modification of the image forming apparatus according to the first exemplary embodiment will be described. Only parts different from those in the above exemplary embodiment will be described. 
     (Drive Mechanism) 
     As shown in  FIG. 5 , in an image forming apparatus  101  according to the modification, the secondary transfer roller  127  and the fixing device  116  (see  FIGS. 1 and 2 ) are rotationally driven by a single transfer fixing motor  129 . Accordingly, the rotational driving of the secondary transfer roller  127  and the fixing device  116  is stopped in interlocking with each other, that is, the rotational driving of the secondary transfer roller  127  and the fixing device  116  is stopped at the same time. 
     Also in the present modification, the contact/separation mechanism  150  is a mechanism that moves the secondary transfer roller  127  in a state of being rotationally driven. That is, even in the separated state in which the secondary transfer roller  127  is separated from the intermediate transfer belt  24 , the secondary transfer roller  127  and the fixing device  116  may be rotationally driven. 
     A drive mechanism  121  of the image forming apparatus  101  according to the modification includes the photoconductor motor  122 , the intermediate transfer motor  124 , the transfer fixing motor  129 , and the contact/separation motor  130 . 
     (Control Device) 
     The control device  104  shown in  FIG. 5  has a function of controlling the entire image forming apparatus  101 . The photoconductor motor  122 , the intermediate transfer motor  124 , the transfer fixing motor  129 , and the contact/separation motor  130  are electrically connected to the control device  104 . 
     [Operation at the Time of Abnormality Detection] 
     Next, an operation of the image forming apparatus  101  according to the modification when the abnormality detection device  99  detects an abnormality will be described. 
       FIG. 6  is a flowchart showing an example of a flow of the operation of the image forming apparatus  101  at the time of abnormality detection executed by the CPU (not shown) of the control device  104 . 
     Steps S 110  to S 118  are the same as those in the above exemplary embodiment, and thus the description thereof will be omitted. 
     In step S 120 , it is determined whether the sheet sensor  102  provided on the downstream side of the fixing device  116  detects the trailing end portion of the recording medium P. When the trailing end portion of the recording medium P is not detected, the process proceeds to step S 121 . When the trailing end portion of the recording medium P is detected, the process proceeds to step S 123 . 
     When the abnormality detection device  99  detects an abnormality, the present operation is performed for the recording medium P on a most upstream side in a case where plural recording media P are present between the secondary transfer position T 2  and the fixing region T 3 . 
     In step S 121 , it is determined whether a set time is elapsed from the abnormality detection. When the set time is not elapsed, the process returns to step S 120 . When the set time is elapsed, the process proceeds to step S 123 . 
     In step S 123 , the driving of the transfer fixing motor  129  is stopped to stop the secondary transfer roller  127  and the fixing device  116 . 
     From another point of view, a command for stopping the driving of the transfer fixing motor  129  may be issued after a command for stopping the driving of the intermediate transfer motor  124  is issued. Accordingly, the rotation of the secondary transfer roller  127  and the fixing device  116  is stopped after the rotation of the intermediate transfer belt  24  is stopped. Conversely, the command for stopping the driving of the transfer fixing motor  129  is not issued before the command for stopping the driving of the intermediate transfer motor  124  is issued. 
     The rotational driving of the photoconductor drum  32  and the intermediate transfer belt  24  may be stopped at an early stage as compared with a case where the secondary transfer roller  127  and the intermediate transfer belt  24  are in contact with each other until the rotational driving of the secondary transfer roller  127  is stopped, and thus a load on the photoconductor drum  32  and the intermediate transfer belt  24  is reduced. 
     The recording medium P to which the toner image is fixed may be removed as compared with a case where the rotational driving of the secondary transfer roller  127  is stopped after the rotational driving of the fixing device  116  is stopped. 
     The recording medium P to which the toner image is fixed may be removed as compared with a case where the rotational driving of the secondary transfer roller  127  and the fixing device  116  is stopped before the trailing end portion of the recording medium P passes through the fixing device  116 . 
     Second Exemplary Embodiment 
     Next, an example of an image forming apparatus according to a second exemplary embodiment of the present invention will be described. The same members as those in the first exemplary embodiment are denoted by the same reference numerals, and the redundant description thereof will be omitted or simplified. 
     [Apparatus Configuration] 
     First, an apparatus configuration of the image forming apparatus will be described. 
     (Overall Configuration of Image Forming Apparatus) 
     The image forming apparatus  200  shown in  FIGS. 7 and 8  is an electrophotographic image forming apparatus that forms a toner image as an example of a colorant image on the recording medium P such as a sheet. More specifically, the image forming apparatus  200  includes the image forming unit  14 , the first transport body  11 , a second transport body  12 , and a fixing device  16 . Hereinafter, a configuration of each unit of the image forming apparatus  200  will be described. 
     (Image Forming Unit) 
     The image forming unit  14  is an example of a forming unit that forms an image on a recording medium, and includes the toner image forming units  22  and a transfer device  17 . 
     (Toner Image Forming Unit) 
     The toner image forming unit  22  as an example of a colorant image forming device has the same configuration as that in the first exemplary embodiment, and thus the description thereof will be omitted. 
     (Transfer Device) 
     The transfer device  17  shown in  FIGS. 7 and 8  primarily transfers a toner image of each color of the photoconductor drum  32  of each color to the intermediate transfer belt  24  as the intermediate transfer body, and secondarily transfers the superimposed toner image to the recording medium P at the secondary transfer position T 2 . The transfer device  17  includes the intermediate transfer belt  24 , the primary transfer rollers  26 , a secondary transfer body  27 , the facing roller  42 A, and a contact-and-separation mechanism  250  (hereinafter called a contact/separation mechanism  250 ). 
     (Primary Transfer Roller) 
     The primary transfer roller  26  has the same configuration as that in the first exemplary embodiment, and thus the description thereof will be omitted. 
     (Intermediate Transfer Belt) 
     The intermediate transfer belt  24  as the example of the image holder has the same configuration as that in the first exemplary embodiment, and thus the description thereof will be omitted. However, the driving roller  42 D is provided with a tensioner spring  254 . 
     (Secondary Transfer Body and Facing Roller) 
     The secondary transfer body  27  shown in  FIGS. 7 and 8  has a function of transferring a toner image to the recording medium P. As shown in  FIG. 9 , the secondary transfer body  27  includes a transfer cylinder  28  and a pair of sprockets  29 . The secondary transfer body  27  is rotationally driven in the direction indicated by the arrow B. 
     As shown in  FIGS. 7 and 8 , the transfer cylinder  28  and the facing roller  42 A are disposed to face each other with the intermediate transfer belt  24  interposed therebetween. In the present exemplary embodiment, the secondary transfer position T 2  at which the toner image is to be transferred from the intermediate transfer belt  24  to the recording medium P is formed between the transfer cylinder  28  and the facing roller  42 A. When a secondary transfer electric field is applied between the transfer cylinder  28  and the facing roller  42 A, the toner image primarily transferred to the intermediate transfer belt  24  is secondarily transferred to the recording medium P at the secondary transfer position T 2 . 
     As shown in  FIG. 9 , each recess  28 D, in which grippers  54  and an attachment member  55  of a transport unit  15  to be described later are accommodated, is formed on an outer circumference of the transfer cylinder  28 . 
     The pair of sprockets  29  are disposed on both axial end sides of the transfer cylinder  28 , and a pair of chains  52  to be described later are wound around the sprockets  29 , respectively. The pair of sprockets  29  are disposed coaxially with the transfer cylinder  28  and rotate integrally with the transfer cylinder  28 . 
     (First Transport Body and Second Transport Body) 
     The first transport body  11  shown in  FIGS. 7 and 8  is a transport body that transports the recording medium P to the transport unit  15  to be described later. Specifically, the first transport body  11  has a function of transporting the recording medium P and transferring the recording medium P to the grippers  54  of the transport unit  15  to be described later. More specifically, the first transport body  11  includes an annular transport belt  11 B wound around a pair of rollers  11 A. 
     The second transport body  12  is a transporting body that transports the recording medium P transported from the transport unit  15  to be described later. Specifically, the second transport body  12  has a function of receiving the recording medium P that is released from holding by the grippers  54  of the transport unit  15  to be described later, and transporting the recording medium P. More specifically, the second transport body  12  includes an annular transport belt  12 B wound around a pair of rollers  12 A. 
     (Fixing Device) 
     The fixing device  16  shown in  FIGS. 7 and 8  has a function of heating the recording medium P to which the toner image is transferred, and fixing the toner image to the recording medium P. The fixing device  16  is also an example of a transport device that transports the recording medium P. 
     Specifically, the fixing device  16  is a device that fixes the toner image, which is transferred to the recording medium P by the transfer cylinder  28 , to the recording medium P. More specifically, the fixing device  16  includes a fixing unit  90 , a non-contact heating unit  70 , an air blowing unit  80 , and the transport unit  15 . 
     (Fixing Unit) 
     The fixing unit  90  includes a heating roller  68  and a pressurizing body  67 . 
     As shown in  FIG. 10 , the pressurizing body  67  includes a fixing cylinder  69  and a pair of sprockets  19 . The pressurizing body  67  is rotationally driven in a direction indicated by an arrow E. 
     The fixing cylinder  69  functioning as a pressurizing roller has a function of pressurizing the recording medium P with the recording medium P (see  FIGS. 7 and 8 ) sandwiched between the fixing cylinder  69  and the heating roller  68 . Further, each recess  69 D, in which the grippers  54  and the attachment member  55  as an example of a holding unit of the transport unit  15  are accommodated, is formed on an outer circumference of the fixing cylinder  69 . 
     As shown in  FIG. 10 , the pair of sprockets  19  are disposed on both axial end sides of the fixing cylinder  69 , and the pair of chains  52  to be described later are wound around the sprockets  19 , respectively. The pair of sprockets  19  are disposed coaxially with the fixing cylinder  69 , and rotate integrally with the fixing cylinder  69 . 
     The heating roller  68  has a function of fixing an image formed on the recording medium P with the recording medium P sandwiched between the heating roller  68  and the fixing cylinder  69 . Specifically, the heating roller  68  includes a heating source  68 B such as a halogen lamp therein. The heating roller  68  has the fixing region T 3  in which the recording medium P is sandwiched between the heating roller  68  and the fixing cylinder  69 . The heating roller  68  heats and pressurizes the toner image in a state in which the recording medium P is sandwiched between the heating roller  68  and the fixing cylinder  69  in the fixing region T 3 , and fixes the toner image to the recording medium P. 
     (Transport Unit) 
     The transport unit  15  shown in  FIGS. 7 and 8  has a function of transporting the recording medium P in a transport direction X (the direction indicated by the arrow A). Specifically, the transport unit  15  has a function of transporting the recording medium P from the secondary transfer position T 2  to the fixing region T 3  between the heating roller  68  and the fixing cylinder  69 . The transport direction X is a leftward direction in  FIG. 1 . Specifically, the transport direction X is a horizontal direction. Therefore, the transport unit  15  is a transport mechanism that transports the recording medium P in the horizontal direction. 
     More specifically, as shown in  FIGS. 9 and 10 , the transport unit  15  includes the pair of chains  52  and the grippers  54 . The gripper  54  is the example of the holding unit that holds the recording medium P. The pair of chains  52  are an example of a rotation member to which the holding unit is attached and which transports the recording medium P by rotating itself. In  FIGS. 7 and 8 , the chains  52  and the grippers  54  are shown in a simplified manner. 
     As shown in  FIGS. 7 and 8 , the pair of chains  52  are formed in an annular shape. As shown in  FIGS. 9 and 10 , the pair of chains  52  are disposed at an interval in an apparatus depth direction D. Each of the pair of chains  52  is wound around the pair of sprockets  29  (see  FIG. 9 ) of the secondary transfer body  27  and the pair of sprockets  19  (see  FIG. 10 ) of the pressurizing body  67 . By rotating the secondary transfer body  27  including the pair of sprockets  29  and the pressurizing body  67  including the pair of sprockets  19 , the chains  52  rotate in a rotation direction C (see  FIGS. 7, 8, and 9 ). Accordingly, the transfer cylinder  28  of the secondary transfer body  27  and the fixing cylinder  69  of the pressurizing body  67  are rotationally driven in interlocking with each other, and the rotational driving thereof is stopped in interlocking with each other. 
     As shown in  FIGS. 9 and 10 , the attachment member  55  to which the grippers  54  are attached is extended along the apparatus depth direction D across the pair of chains  52 . Plural attachment members  55  are fixed to the pair of chains  52  at predetermined intervals along the rotation direction C of the chains  52 . 
     Plural grippers  54  are attached to the attachment member  55  at predetermined intervals along the apparatus depth direction D. In other words, the grippers  54  are attached to the chains  52  via the attachment member  55 . The gripper  54  has a function of holding a leading end portion of the recording medium P. 
     As shown in  FIG. 11 , the gripper  54  includes a claw  54 A and a claw base  54 B. The claw  54 A and the claw base  54 B are disposed on an upstream side of the gripper  54  in the transport direction. That is, the claw  54 A and the claw base  54 B constitute a portion of the gripper  54  on the upstream side in the transport direction. The claw  54 A and the claw base  54 B are an example of a holding portion that holds the recording medium P. 
     The gripper  54  is configured to hold the recording medium P by sandwiching the leading end portion of the recording medium P between the claw  54 A and the claw base  54 B. In other words, the gripper  54  may be a gripping unit that grips the recording medium P in a thickness direction. The leading end portion of the recording medium P is a downstream end portion of the recording medium P in the transport direction X. 
     More specifically, the gripper  54  holds the leading end portion of the recording medium P outside an image region of the recording medium P. The image region of the recording medium P is a region to which the toner image is transferred in the recording medium P. In the gripper  54 , for example, the claw  54 A is pressed against the claw base  54 B by a spring or the like, and the claw  54 A is opened and closed with respect to the claw base  54 B by an action of a cam or the like. 
     Further, a width of each of the grippers  54  along the apparatus depth direction D is narrower than a width of the recording medium P. Therefore, the gripper  54  holds a part of the recording medium P in the apparatus depth direction D. 
     In the transport unit  15 , the leading end portion of the recording medium P sent from the first transport body  11  is held by the gripper  54  as shown in  FIG. 11 . 
     As shown in  FIGS. 7 and 8 , in the transport unit  15 , the chains  52  rotate in the rotation direction C in a state in which the gripper  54  holds the leading end portion of the recording medium P, so that the gripper  54  is moved to transport the recording medium P. The recording medium P passes through the secondary transfer position T 2  together with the gripper  54  while being held by the gripper  54 . At a portion where the chain  52  is wound around the sprocket  29 , the gripper  54  moves integrally with the transfer cylinder  28  in the rotation direction B of the transfer cylinder  28  in a state where the gripper  54  is accommodated in the recess  28 D of the transfer cylinder  28 . 
     After the recording medium P is caused to pass through the secondary transfer position T 2 , the recording medium P is further caused to pass through the fixing region T 3  together with the gripper  54  while the recording medium P is held by the gripper  54 . At a portion where the chain  52  is wound around the sprocket  19 , the gripper  54  moves integrally with the fixing cylinder  69  in the rotation direction E of the fixing cylinder  69  in a state where the gripper  54  is accommodated in the recess  69 D of the fixing cylinder  69 . When the recording medium P passes through the fixing region T 3 , the holding of the recording medium P by the gripper  54  is released. 
     (Non-Contact Heating Unit) 
     The non-contact heating unit  70  shown in  FIGS. 7 and 8  has a function of heating the recording medium P transported by the transport unit  15  in a non-contact manner. The non-contact heating unit  70  preheats an unfixed toner image formed on a surface of the recording medium P in the non-contact manner. Specifically, the non-contact heating unit  70  includes heaters  72 , a reflection plate  73 , and a shielding mechanism  202 . 
     The heater  72  is a heating member that heats the recording medium P in a non-contact manner with respect to the recording medium P transported in the transport direction X by the transport unit  15 . 
     Plural heaters  72  are arranged at intervals along the transport direction X. The heater  72  includes a cylindrical infrared heater having a length in the apparatus depth direction D. The heater  72  generates heat by a filament (not shown) provided therein, and heats the recording medium P by the radiant heat of the filament. In the present exemplary embodiment, four heaters  72  are provided, but the number of heaters  72  is not limited to four 
     The reflection plate  73  has a function of reflecting infrared rays from the heater  72  to a lower side of the device, that is, a side of the recording medium P transported by the transport unit  15 . Specifically, the reflection plate  73  has a box shape in which an opening  73 A is formed at the lower side of the device. The reflection plate  73  is formed using a metal plate such as an aluminum plate. 
     (Air Blowing Unit) 
     The air blowing unit  80  shown in  FIGS. 7 and 8  is disposed on a side opposite to the non-contact heating unit  70  with respect to the recording medium P, that is, on a lower side of the non-contact heating unit  70 , and faces the non-contact heating unit  70  in a vertical direction Z. 
     Specifically, the air blowing unit  80  has a function of blowing air to a lower surface of the recording medium P transported by the transport unit  15 . More specifically, the air blowing unit  80  has a function of floating the recording medium P by blowing air to the recording medium P to maintain a non-contact state with respect to the recording medium P, such that the recording medium P is transported by the transport unit  15  in a state where the air blowing unit  80  is in the non-contact state with respect to a back surface opposite to the surface of the recording medium P on which an unfixed image is formed. 
     The air blowing unit  80  includes plural air blowers  84  arranged along the transport direction X. The plural air blowers  84  send air upward, and blow the air against the lower surface of the recording medium P to float the recording medium P. As an example, an axial air blower that blows air in an axial direction is used as the air blower  84 . As the air blower  84 , a centrifugal air blower that blows air in a centrifugal direction such as a multi-blade air blower may be used. 
     (Transfer Fixing Drive Mechanism) 
     A transfer fixing drive mechanism  205  shown in  FIGS. 7 and 8  is a mechanism that rotationally drives the transfer cylinder  28  of the secondary transfer body  27  and the fixing cylinder  69  of the fixing unit  90  in interlocking with each other. 
     (Shielding Mechanism) 
     As shown in  FIGS. 12 and 13 , the shielding mechanism  202  shown in  FIGS. 7 and 8  includes a plate-shaped shielding member  212  having a size that covers and shields the opening  73 A of the reflection plate  73  of the non-contact heating unit  70 . The shielding member  212  constitutes a single shielding portion. Both side portions of the shielding member  212  are movably supported by a rail  209  extending along the transport direction of the recording medium P. 
     As shown in  FIG. 12 , when the shielding member  212  moves to an upstream side U in a medium transport direction along the rail  209 , the shielding member  212  is in an open state in which the opening  73 A of the reflection plate  73  of the non-contact heating unit  70  is opened. Accordingly, heat is allowed to be released downward from the non-contact heating unit  70 . 
     As shown in  FIG. 13 , when the shielding member  212  moves to a downstream side L in the medium transport direction along the rail  209 , the shielding member  212  is in a closed state in which the opening  73 A of the reflection plate  73  of the non-contact heating unit  70  is closed. Accordingly, the heat released downward from the non-contact heating unit  70  is shielded. 
     One end of a coil spring  210  is fixed to an end surface  209 A of the rail  209  on the upstream side U in the medium transport direction, and the other end of the coil spring  210  is attached to an end portion of the shielding member  212  on the upstream side U in the medium transport direction. Accordingly, the shielding member  212  is pulled toward the upstream side U in the medium transport direction by the coil spring  210 . Therefore, a force is constantly applied to the shielding member  212  so as to be in the closed state in which the non-contact heating unit  70  is closed. 
     (Opening/Closing Mechanism) 
     As shown in  FIGS. 12 and 13 , an opening-and-closing mechanism  215  (hereinafter called opening/closing mechanism  215 ) is provided on the downstream side L of the non-contact heating unit  70  in the medium transport direction. The opening/closing mechanism  215  includes a winding-up roller  214  that winds up a wire  213  extending from the downstream side L of the shielding member  212  in the medium transport direction so as to be able to be drawn out, and an opening-and-closing motor  206  (hereinafter called an opening/closing motor  206 ) that rotates the winding-up roller  214  in a winding-up direction. Further, the opening/closing mechanism  215  includes an electromagnetic clutch  218  that connects and disconnects the opening/closing motor  206  and a rotation mechanism of the winding-up roller  214 . 
     The opening/closing motor  216  receives power and rotates the winding-up roller  214  in the winding-up direction, so as to drive the shielding member  212  to the downstream side L in the medium transport direction to form the open state in which the non-contact heating unit  70  is opened. The opening/closing motor  206  prevents unexpected rotation of the winding-up roller  214  by an idle torque of the opening/closing motor  206 . 
     While the electromagnetic clutch  218  receives power and is turned on, the electromagnetic clutch  218  connects the opening/closing motor  206  to the rotation mechanism of the winding-up roller  214 , and the rotation of the winding-up roller  214  is regulated by the idle torque of the opening/closing motor  206 . 
     When the power is cut off and the electromagnetic clutch  218  is turned off, the electromagnetic clutch  218  releases the connection between the opening/closing motor  206  and the rotation mechanism of the winding-up roller  214 . Therefore, when the power supply is cut off due to a power failure or the like and the electromagnetic clutch  218  is turned off, the winding-up roller  214  is rotatable, and the shielding member  82  moves to the upstream side U in the medium transport direction by the coil spring  210  to form the closed state in which the non-contact heating unit  70  is closed. 
     (Contact/Separation Mechanism) 
     The contact/separation mechanism  250  shown in  FIGS. 7 and 8  has a function of moving the facing roller  42 A. Specifically, the contact/separation mechanism  250  moves the facing roller  42 A between a contact state in which the intermediate transfer belt  24  wound around the facing roller  42 A shown in  FIG. 7  is in contact with the transfer cylinder  28  and a separated state in which the intermediate transfer belt  24  is separated from the transfer cylinder  28  shown in  FIG. 8 . The contact/separation mechanism  250  is provided with a cam  252  and a contact-and-separation motor  230  (hereinafter called a contact/separation motor  230 ) for rotating the cam  252 . The cam  252  is in contact with a shaft  43  of the secondary transfer roller  127 , and the cam  252  rotates to move the facing roller  42 A. The contact/separation mechanism  250  is provided with an optical sensor (not shown) so as to detect a rotation position of the cam  252 . Accordingly, a contact state or a separation state of the facing roller  42 A is monitored. 
     As the facing roller  42 A moves, the tensioner spring  254  expands or contracts. Accordingly, when the facing roller  42 A is separated, a tension of the intermediate transfer belt  24  is prevented from decreasing. When the facing roller  42 A is separated, the intermediate transfer belt  24  is separated from the transfer cylinder  28  by the tension of the tensioner spring  254 . 
     (Sheet Sensor) 
     The sheet sensor  102  is provided on the downstream side of the recording medium P of the fixing device  16  in the transport direction and on the upstream side of the second transport body  12  in the transport direction shown in  FIGS. 7 and 8 . The sheet sensor  102  detects the recording medium P discharged from the fixing device  16 . 
     (Transfer Cylinder Position Detection Mechanism) 
     A transfer cylinder position detection mechanism  270  shown in  FIG. 9  is a mechanism that detects a rotation position of the transfer cylinder  28 . In the present exemplary embodiment, the transfer cylinder position detection mechanism  270  includes a patch  272  and a transfer cylinder optical sensor  274 . The patch  272  is attached to an axial end portion of the transfer cylinder  28 . The rotation position of the transfer cylinder  28  is detected by reading a position of the patch  272  by the transfer cylinder optical sensor  274 . 
     In the present exemplary embodiment, the transfer cylinder position detection mechanism  270  detects a state in which the gripper  54  is located in a range H 1  where the chain  52  is wound around the transfer cylinder  28 . 
     A range H 2  is a range in which the gripper  54  is located in a range where the chain  52  is not wound around the transfer cylinder  28 , and the gripper  54  is located between the upper and lower chains  52 . 
     (Fixing Cylinder Position Detection Mechanism) 
     A fixing cylinder position detection mechanism  271  shown in  FIG. 10  is a mechanism that detects a rotation position of the fixing cylinder  69 . In the present exemplary embodiment, the fixing cylinder position detection mechanism  271  includes a patch  273  and a fixing cylinder optical sensor  275 . The patch  273  is attached to an axial end portion of the fixing cylinder  69 . The rotation position of the fixing cylinder  69  is detected by reading a position of the patch  273  by the fixing cylinder optical sensor  275 . 
     In the present exemplary embodiment, the fixing cylinder position detection mechanism  271  detects a state in which the gripper  54  is located in a range H 3  excluding the fixing region T 3  of the fixing unit  90  in a range in which the chain  52  is wound around the fixing cylinder  69 . 
     A range H 4  is a range including a region where the chain  52  is not wound around the fixing cylinder  69  and the fixing region T 3 . That is, the range H 4  is a region including a range in which the gripper  54  is located between the upper and lower chains  52  and the fixing region T 3 . 
     (Drive Mechanism) 
     As shown in  FIG. 14 , the image forming apparatus  200  includes a drive mechanism  220 . The drive mechanism  220  has a function of driving various members of the image forming apparatus  200 . The drive mechanism  220  includes the photoconductor motor  122 , the intermediate transfer motor  124 , a transfer fixing motor  207  that rotationally drives the transfer fixing drive mechanism  205  (see  FIGS. 7 and 8 ), the contact-and-separation motor  230  that drives the contact-and-separation mechanism  250  (see  FIGS. 7 and 8 ), and the opening-and-closing motor  206  of the opening-and-closing mechanism  215  (see  FIGS. 12 and 13 ). 
     (Abnormality Detection Device) 
     The abnormality detection device  99  shown in  FIG. 14  is the same as that in the first exemplary embodiment, and thus the description thereof will be omitted. 
     (Control Device) 
     A control device  204  shown in  FIG. 14  has a function of controlling the entire image forming apparatus  200 . A hardware configuration of the control device  204  includes a computer including a central processing unit (CPU) (not shown), a read only memory (ROM) that stores a program or the like for realizing each processing routine, a random access memory (RAM) that temporarily stores data, a memory as a storage means, a network interface, and the like. 
     The photoconductor motor  122 , the intermediate transfer motor  124 , the transfer fixing motor  207 , the contact/separation motor  230 , and the opening/closing motor  206  constituting the drive mechanism  220  are electrically connected to the control device  204 . 
     The exposure device  36  for each color, the jam sensor  98 , the sheet sensor  102 , the transfer cylinder optical sensor  274 , and the fixing cylinder optical sensor  275  are electrically connected to the control device  204 . 
     [Operation at the Time of Abnormality Detection] 
     Next, an operation of the image forming apparatus  200  when the abnormality detection device  99  detects an abnormality will be described. 
       FIG. 15  is a flowchart showing an example of a flow of the operation of the image forming apparatus  200  at the time of abnormality detection executed by the CPU (not shown) of the control device  204 . A program is stored in advance in, for example, the ROM (not shown) of the control device  204 . The CPU (not shown) of the control device  204  reads the program stored in the ROM (not shown), and executes the operation of the image forming apparatus  200  at the time of abnormality detection. 
     In the present operation, when the abnormality detection device  99  detects an abnormality, the recording medium P is controlled not to be transported to the secondary transfer position T 2  in a case where the recording medium P is present on an upstream side of the secondary transfer position T 2 . 
     In step S 210 , the abnormality detection device  99  detects an abnormality. In the present exemplary embodiment, the jam sensor  98  detects a jam of the recording medium P. 
     In step S 212 , the heating of the heater  72  of the non-contact heating unit  70  is stopped. In step S 214 , the opening/closing motor  206  of the opening/closing mechanism  215  is driven to move and close the shielding member  212 . Step S 212  and step S 214  may be performed at the same time. 
     In step S 216 , the contact/separation motor  230  is driven to separate the facing roller  42 A from the intermediate transfer belt  24 . Accordingly, the intermediate transfer belt  24  is separated from the transfer cylinder  28  by the tension of the tensioner spring  254 . 
     In step S 218 , the exposure by the exposure device  36  is stopped. In step S 220 , the driving of the photoconductor motor  122  is stopped to stop the rotation of the photoconductor drum  32 . In step S 222 , the driving of the intermediate transfer motor  124  is stopped to stop the rotation of the intermediate transfer belt  24 . Step S 218 , step S 220 , and step S 222  may be performed at the same time. In particular, step S 220  and step S 222  may be performed at the same time. 
     In step S 224 , it is determined whether the sheet sensor  102  provided on a downstream side of the fixing device  16  detects the trailing end portion of the recording medium P. When the trailing end portion of the recording medium P is not detected, the process proceeds to step S 225 . When the trailing end portion of the recording medium P is detected, the process proceeds to step S 226 . 
     When the abnormality detection device  99  detects an abnormality, the present operation is performed for the recording medium P on a most upstream side in a case where plural recording media P are present between the secondary transfer position T 2  and the fixing region T 3 . 
     In step S 225 , it is determined whether a set time is elapsed from the abnormality detection. When the set time is not elapsed, the process returns to step S 224 . When the set time is elapsed, the process proceeds to step S 226 . 
     In step S 226 , the driving of the transfer fixing motor  207  is stopped such that the gripper  54  of the transfer cylinder  28  is located in the range H 1 . In step S 228 , the air blowers  84  of the air blowing unit  80  are stopped. Step S 226  and step S 228  may be performed at the same time. 
     From another point of view, a command for stopping the driving of the intermediate transfer motor  124  may be issued after a command for driving the contact/separation motor  230  is issued, and a command for stopping the driving of the transfer fixing motor  207  may be issued after the command for stopping the driving of the intermediate transfer motor  124  is issued. Accordingly, the rotation of the intermediate transfer belt  24  is stopped after the transfer cylinder  28  is separated from the intermediate transfer belt  24 , and the rotation of the transfer cylinder  28  and the fixing cylinder  69  is stopped after the rotation of the intermediate transfer belt  24  is stopped. Conversely, the command for stopping the driving of the transfer fixing motor  207  is not issued until the command for stopping the driving of the intermediate transfer motor  124  is issued. Similarly, the command for stopping the driving of the intermediate transfer motor  124  is not issued until the command for driving the contact/separation motor  230  is issued. 
     When an abnormality is detected and the image forming apparatus  200  is to be stopped, the transfer cylinder  28  is separated from the intermediate transfer belt  24 , so that the rotational driving of the photoconductor drum  32  and the intermediate transfer belt  24  may be stopped at an early stage, and the rotational driving of the transfer cylinder  28  and the fixing cylinder  69  may be continuously performed. 
     By stopping the rotational driving of the photoconductor drum  32  and the intermediate transfer belt  24  at an early stage, a load on the photoconductor drum  32  and the intermediate transfer belt  24  is reduced. 
     Even after the transfer cylinder  28  is separated from the intermediate transfer belt  24 , the rotational driving of the transfer cylinder  28  and the fixing cylinder  69  is continued, so that the recording medium P is transported to a downstream side of the secondary transfer position T 2 . Therefore, it is easy to remove the recording medium P. Further, after the sheet sensor  102  provided on a downstream side of the fixing unit  90  detects the trailing end portion of the recording medium P, that is, after the recording medium P is discharged from the fixing unit  90 , the transfer cylinder  28  and the fixing cylinder  69  are stopped. Therefore, the recording medium P to which the toner image is fixed may be removed. 
     As described above, the rotational driving of the photoconductor drum  32  and the intermediate transfer belt  24  may be stopped at an early stage as compared with a case where the transfer cylinder  28  and the intermediate transfer belt  24  are in contact with each other until the rotational driving of the transfer cylinder  28  and the fixing cylinder  69  is stopped. Accordingly, the load on the photoconductor drum  32  and the intermediate transfer belt  24  is reduced. 
     The recording medium P to which the toner image is fixed may be removed as compared with a case where the rotational driving of the transfer cylinder  28  and the fixing cylinder  69  is stopped before the trailing end portion of the recording medium P passes through the fixing unit  90 . 
     The trailing end portion of the recording medium P passes through the fixing unit  90 , and the leading end portion of the recording medium P is not held by the gripper  54 . Therefore, it is easy to remove the recording medium P as compared with a case where the rotational driving of the transfer cylinder  28  and the fixing cylinder  69  is stopped in a state where the leading end portion of the recording medium P is held by the gripper  54 . 
     The rotational driving of the transfer cylinder  28  and the fixing cylinder  69  may be stopped in a state where the holding of the leading end portion of the recording medium P by the gripper  54  is released without directly detecting that the holding of the leading end portion of the recording medium P by the gripper  54  is released. 
     The transfer cylinder  28  is stopped such that the gripper  54  is located in the range H 1 . Therefore, the access to the gripper  54  of the transfer cylinder  28  is better as compared with a case where the transfer cylinder  28  is stopped such that the gripper  54  is located in the range H 2  between the upper and lower chains  52 . 
     The rotational driving of the transfer cylinder  28  and the fixing cylinder  69  is stopped after the trailing end portion of the recording medium P passes through the fixing unit  90 , that is, after the recording medium P passes through the heating region where the recording medium P faces the non-contact heating unit  70 . Therefore, the heat received by the recording medium P from the non-contact heating unit  70  may be reduced as compared with a case where the rotational driving is stopped before the recording medium P passes through the heating region facing the non-contact heating unit  70 . 
     The blowing of the air blowers  84  of the air blowing unit  80  is stopped after the trailing end portion of the recording medium P passes through the fixing unit  90 , that is, after the recording medium P passes through the heating region where the recording medium P faces the non-contact heating unit  70 . Therefore, the heating of the recording medium P by the non-contact heating unit  70  may be prevented as compared with a case where the blowing of the air blowers  84  of the air blowing unit  80  is stopped before the trailing end portion of the recording medium P passes through the heating region. 
     [First Modification] 
     Next, a first modification of the image forming apparatus according to the second exemplary embodiment will be described. Only parts different from those in the above exemplary embodiment will be described. In the present modification, only an operation at the time of abnormality detection is different, and the configuration of the image forming apparatus  200  is the same. 
     [Operation at the Time of Abnormality Detection] 
     An operation of the image forming apparatus  200  according to the present modification when the abnormality detection device  99  detects an abnormality will be described. 
       FIG. 16  is a flowchart showing an example of a flow of the operation of the image forming apparatus  200  at the time of abnormality detection executed by the CPU (not shown) of the control device  204 . 
     Steps S 210  to S 225  are the same as those in the above exemplary embodiment, and thus the description thereof will be omitted. 
     In step S 227 , the driving of the transfer fixing motor  207  is stopped such that the gripper  54  of the fixing cylinder  69  is located in the range H 3 . Then, in step S 228 , the air blowers  84  of the air blowing unit  80  are stopped. Step S 227  and step S 228  may be performed at the same time. 
     The fixing cylinder  69  is stopped such that the gripper  54  is located in the range H 3 . Therefore, the access to the gripper  54  of the fixing cylinder  69  is better as compared with a case where the fixing cylinder  69  is stopped such that the gripper  54  is located in the range H 4  between the upper and lower chains  52  or the range of the fixing region T 3 . 
     [Second Modification] 
     Next, a second modification of the image forming apparatus according to the second exemplary embodiment will be described. Only parts different from those in the above exemplary embodiment will be described. In the present modification, only an operation at the time of abnormality detection is different, and the configuration of the image forming apparatus  200  is the same. 
     [Operation at the Time of Abnormality Detection] 
     An operation of the image forming apparatus  200  according to the modification when the abnormality detection device  99  detects an abnormality will be described. 
       FIG. 17  is a flowchart showing an example of a flow of the operation of the image forming apparatus  200  at the time of abnormality detection executed by the CPU (not shown) of the control device  204 . 
     Steps S 210  to S 222  are the same as those in the above exemplary embodiment, and thus the description thereof will be omitted. 
     In step S 223 , it is determined whether the sheet sensor  102  provided on the downstream side of the fixing device  16  detects the leading end portion of the recording medium P. When the leading end portion of the recording medium P is not detected, the process proceeds to step S 225 . When the leading end portion of the recording medium P is detected, the process proceeds to step S 230 . 
     When the abnormality detection device  99  detects an abnormality, the present operation is performed for the recording medium P on a most upstream side in a case where plural recording media P are present between the secondary transfer position T 2  and the fixing region T 3 . 
     In step S 225 , it is determined whether a set time is elapsed from the abnormality detection. When the set time is not elapsed, the process returns to step S 223 . When the set time is elapsed, the process proceeds to step S 230 . 
     In step S 230 , the driving of the transfer fixing motor  207  is stopped. Then, in step S 232 , the air blowers  84  of the air blowing unit  80  are stopped. Step S 230  and step S 232  may be performed at the same time. 
     The rotational driving of the photoconductor drum  32  and the intermediate transfer belt  24  may be stopped at an early stage as compared with the case where the transfer cylinder  28  and the intermediate transfer belt  24  are in contact with each other until the rotational driving of the transfer cylinder  28  and the fixing cylinder  69  is stopped, and thus a load on the photoconductor drum  32  and the intermediate transfer belt  24  is reduced. 
     As for the recording medium P, the leading end portion of the recording medium P passes through the fixing unit  90 , and the leading end portion of the recording medium P is not held by the gripper  54 . Therefore, it is easy to remove the recording medium P as compared the case where the rotational driving of the transfer cylinder  28  and the fixing cylinder  69  is stopped in a state where the leading end portion of the recording medium P is held by the gripper  54 . 
     The rotational driving of the transfer cylinder  28  and the fixing cylinder  69  may be stopped in the state where the holding of the leading end portion of the recording medium P by the gripper  54  is released without directly detecting that the holding of the leading end portion of the recording medium P by the gripper  54  is released. 
     The rotational driving of the transfer cylinder  28  and the fixing cylinder  69  is stopped after the leading end portion of the recording medium P passes through the fixing unit  90 , that is, after the recording medium P passes through the heating region facing the non-contact heating unit  70 . Therefore, the heat received by the recording medium P from the non-contact heating unit  70  may be reduced as compared with a case of the rotational driving is stopped before the recording medium P passes through the heating region facing the non-contact heating unit  70 . 
     The blowing of the air blowers  84  of the air blowing unit  80  is stopped after the leading end portion of the recording medium P passes through the fixing unit  90 , that is, after the recording medium P passes through the heating region facing the non-contact heating unit  70 . Therefore, the heating of the recording medium P by the non-contact heating unit  70  may be prevented as compared with a case where the blowing of the air blowers  84  of the air blowing unit  80  is stopped before the trailing end portion of the recording medium P passes through the heating region. 
     [Third Modification] 
     Next, a third modification of the image forming apparatus according to the second exemplary embodiment will be described. Only parts different from those in the above exemplary embodiment will be described. 
     (Sheet Sensor) 
     In an image forming apparatus  201  according to the third modification shown in  FIG. 18 , the sheet sensor  102  is provided on the upstream side of the recording medium P of the fixing device  16  in the transport direction and on the downstream side of the non-contact heating unit  70  in the transport direction. The sheet sensor  102  detects the recording medium P that is passed through the heating region of the non-contact heating unit  70 . 
     [Operation at the Time of Abnormality Detection] 
     An operation of the image forming apparatus  201  according to the present modification when the abnormality detection device  99  detects an abnormality will be described. 
       FIG. 19  is a flowchart showing an example of a flow of the operation of the image forming apparatus  201  at the time of abnormality detection executed by the CPU (not shown) of the control device  204 . 
     Steps S 210  to S 222  are the same as those in the above exemplary embodiment, and thus the description thereof will be omitted. 
     In step S 324 , it is determined whether the sheet sensor  102  provided on the upstream side of the fixing device  16  detects the trailing end portion of the recording medium P. When the trailing end portion of the recording medium P is not detected, the process proceeds to step S 325 . When the trailing end portion of the recording medium P is detected, the process proceeds to step S 326 . 
     When the abnormality detection device  99  detects an abnormality, the present operation is performed for the recording medium P on a most upstream side in a case where plural recording media P are present between the secondary transfer position T 2  and the fixing region T 3 . 
     In step S 325 , it is determined whether a set time is elapsed from the abnormality detection. When the set time is not elapsed, the process returns to step S 324 . When the set time is elapsed, the process proceeds to step S 326 . 
     In step S 326 , the driving of the transfer fixing motor  207  is stopped. Then, in step S 328 , the air blowers  84  of the air blowing unit  80  are stopped. Step S 326  and step S 328  may be performed at the same time. 
     The rotational driving of the photoconductor drum  32  and the intermediate transfer belt  24  may be stopped at an early stage as compared with the case where the transfer cylinder  28  and the intermediate transfer belt  24  are in contact with each other until the rotational driving of the transfer cylinder  28  and the fixing cylinder  69  is stopped, and thus a load on the photoconductor drum  32  and the intermediate transfer belt  24  is reduced. 
     As for the recording medium P, the rotational driving of the transfer cylinder  28  and the fixing cylinder  69  is stopped after the trailing end portion of the recording medium P passes through the non-contact heating unit  70 . Therefore, the heat received by the recording medium P from the non-contact heating unit  70  may be reduced as compared with the case of the rotational driving is stopped before the recording medium P passes through the heating region facing the non-contact heating unit  70 . 
     As for the recording medium P, the blowing of the air blowers  84  of the air blowing unit  80  is stopped after the trailing end portion of the recording medium P passes through the heating region facing the non-contact heating unit  70 . Therefore, the heating of the recording medium P by the non-contact heating unit  70  may be prevented as compared with the case where the blowing of the air blowers  84  of the air blowing unit  80  is stopped before the trailing end portion of the recording medium P passes through the heating region. 
     &lt;Others&gt; 
     The present invention is not limited to the above exemplary embodiments. 
     For example, in the above exemplary embodiments, the image forming apparatus is configured to transfer the toner image held by the intermediate transfer belt  24  as the example of the image holder and the intermediate transfer body to the recording medium P, but the present invention is not limited thereto. The image forming apparatus may be configured to transfer the toner image held by the photoconductor as an example of the image holder to the recording medium. 
     For example, in the above exemplary embodiments, when the abnormality detection device  99  detects an abnormality, the recording medium P is controlled not to be transported to the secondary transfer position T 2  in the case where the recording medium P is present on the upstream side of the secondary transfer position T 2 , but the present invention is not limited thereto. The recording medium P on the upstream side of the secondary transfer position T 2  may be transported, and the secondary transfer roller  127  and the intermediate transfer belt  24  may be relatively separated from each other after the trailing end of the recording medium P passes through the secondary transfer position T 2 . 
     The configuration of the image forming apparatus is not limited to the configuration of the above exemplary embodiments, and various configurations may be adopted. For example, an ink may be used as a colorant, and an inkjet method may be used as the colorant image forming unit. Further, it is needless to say that the present invention may be implemented in various forms within a range not departing from the gist of the present invention. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.