Patent Publication Number: US-2010124445-A1

Title: Transfer Target Object Separation Apparatus, Transferring Apparatus, Image Formation Apparatus, and Transfer Target Object Separation Control Method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 USC 119 of Japanese application no. 2008-293425, filed on Nov. 17, 2008, which is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a transfer target object separation apparatus that separates, from a transfer target object movement member, a transfer target object onto which an image developed with a liquid developer (e.g., liquid toner) has been transferred in an electro-photographic image formation apparatus that uses the liquid developer, for example, a copier, a facsimile, a printer, and the like. In addition, the invention relates to a transferring apparatus that transfers a liquid-developer image onto a transfer target object, an image formation apparatus, and a transfer target object separation control method. 
     2. Related Art 
     In a typical operation of an image formation apparatus that uses a liquid developer (e.g., liquid toner), a transferring device transfers a liquid-developer image onto a transfer target object. The transfer target object is transported while in contact with a transfer medium of the transferring device under pressure as the transfer medium moves. In addition, the transfer target object onto which the liquid-developer image has been transferred is transported while in contact with a fixation member of a transferring device under pressure as the transfer medium moves. By this means, the liquid-developer image is fixed on the transfer target object. 
     In the image transfer operation and the fixation operation described above, a transfer surface of the transfer target object, which is a surface closer to the liquid-developer image, is pressed against and thus brought into contact with a transfer target object movement member such as the transfer medium, the fixation member, and the like. When the transfer surface of the transfer target object is in contact with the transfer target object movement member under pressure, due to the nature of liquid developer, the transfer target object is apt to stick to the transfer target object movement member. For this reason, it is difficult to separate the transfer target object onto which the liquid-developer image has been transferred from the transfer target object movement member. In an effort to provide a solution to such a problem, an image formation apparatus that is provided with a transfer target object separation device has been proposed as disclosed in, for example, Japanese Patent No. 3,128,067. The transfer target object separation device disclosed in Japanese Patent No. 3,128,067 blows air toward the front edge of a transfer target object that is transported as a transfer target object movement member moves. Utilizing the air, the proposed transfer target object separation device forcibly separates the front edge part of the transfer target object from the transfer target object movement member. The air blown by the transfer target object separation device of Japanese Patent No. 3,128,067 enters a gap between the front edge of the transfer target object and the transfer target object movement member. By this means, if successful, the front edge part of the transfer target object is separated from the transfer target object movement member. 
     However, the transfer target object separation device of Japanese Patent No. 3,128,067 just blows air toward the front edge of a transfer target object during image formation operation. Therefore, it is difficult to separate the transfer target object from the transfer target object movement member without fail. In addition, air is blown onto the transfer surface of a transfer target object. For this reason, the air could affect a liquid-developer image transferred to the transfer target object. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a transfer target object separation apparatus that separates a transfer target object from a transfer target object movement member with improved reliability without affecting a liquid-developer image transferred to the transfer target object. In addition, the invention provides, as an advantage of some aspects thereof, a transferring apparatus, an image formation apparatus, and a transfer target object separation control method. 
     In order to address the above-identified problems without any limitation thereto, in a transfer target object separation apparatus, a transferring apparatus, an image formation apparatus, and a transfer target object separation control method according to an aspect of the invention, a second cylindrical rotation member that has holes sucks a second surface of a transfer target object after the transferring of an image to the transfer target object through the holes. The second surface of the transfer target object is opposite a first surface thereof. The first surface of the transfer target object is a transfer surface onto which the image is transferred. Since the second cylindrical rotation member sucks the transfer target object, it is possible to separate the transfer target object from a transfer target object movement member without fail. In this sucking operation, the second cylindrical rotation member sucks the second surface of the transfer target object that is opposite the transfer surface. Therefore, it is possible to avoid an image transferred to the transfer target object from being affected by the sucking operation. 
     In addition, since holes are formed throughout the entire circumferential surface of the second cylindrical rotation member, it is possible to hold a transfer target object by suction continuously during the sucking operation even when the second cylindrical rotation member rotates in synchronization with the movement of the transfer target object and the transfer target object movement member. Moreover, since air is continuously taken in through a suction inlet of a first cylindrical rotation member that faces a transfer target object during the sucking operation and has a small capacity, it is possible to ensure that a suction force applied to the transfer target object is large enough to separate the transfer target object from the transfer target object movement member. Therefore, the capacity of a vacuuming section that sucks air can be reduced. Furthermore, since a transfer target object is not sucked when the hole of the second cylindrical rotation member is displaced from the position of the suction inlet, it is possible to move the transfer target object onto the next transport position smoothly. 
     In addition, since the suction inlet of the first cylindrical rotation member through which the front edge part of a transfer target object is sucked also rotates when the second cylindrical rotation member rotates, it is possible to guide the front edge part of the transfer target object to the position of a transfer target object belt transportation device while securely holding the front edge part of the transfer target object by suction. Since the front edge part of the transfer target object is reliably sucked through the rotating suction inlet of the first cylindrical rotation member, it is possible to make the circumferential width of the suction inlet of the first cylindrical rotation member further smaller. By this means, the pressure loss of a transfer target object separation suction section can be reduced effectively, which makes it possible to reduce the size of the vacuuming section and achieve cost reduction. Though a minor gap exists between the outer circumferential surface of the first cylindrical rotation member and the inner circumferential surface of the second cylindrical rotation member or between the outer circumferential surface of the suction inlet and the inner circumferential surface of the second cylindrical rotation member, the gap does not have any significant influence on the pressure loss. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1A  is a diagram that partially illustrates an image formation apparatus with a transfer target object separation device according to an exemplary embodiment of the invention. 
         FIG. 1B  is an enlarged view of part IB of  FIG. 1A . 
         FIG. 2  is an enlarged transverse sectional view of a suction wheel according to an exemplary embodiment of the invention. 
         FIG. 3A  is an enlarged transverse sectional view of a nozzle of the suction wheel according to an exemplary embodiment of the invention. 
         FIG. 3B  is a plan view of the nozzle according to an exemplary embodiment of the invention. 
         FIG. 4A  is a partial plan view of the image formation apparatus according to an exemplary embodiment of the invention. 
         FIG. 4B  is a partial sectional view of the image formation apparatus according to an exemplary embodiment of the invention. 
         FIG. 5  is a partial perspective view of the transfer target object separation device according to an exemplary embodiment of the invention. 
         FIG. 6  is a diagram that schematically illustrates rotation of the nozzle according to an exemplary embodiment of the invention. 
         FIG. 7  is a partial perspective view that schematically illustrates the connection of the transfer target object separation device to a vacuum pump according to an exemplary embodiment of the invention. 
         FIG. 8A  is a diagram that schematically illustrates the sucking operation of the nozzle according to an exemplary embodiment of the invention. 
         FIG. 8B  is a diagram that schematically illustrates the sucking operation of the nozzle according to an exemplary embodiment of the invention. 
         FIG. 8C  is a diagram that schematically illustrates the sucking operation of the nozzle according to an exemplary embodiment of the invention. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     With reference to the accompanying drawings, the best mode for carrying out the present invention will now be explained in detail.  FIG. 1A  is a diagram of an image formation apparatus with a transfer target object separation device according to an exemplary embodiment of the invention.  FIG. 1B  is an enlarged view of part IB of  FIG. 1A . As illustrated in  FIG. 1A , an image formation apparatus  1  according to the present embodiment of the invention is provided with image formation units  2 Y,  2 M,  2 C, and  2 K that use a yellow (Y) liquid developer, a magenta (M) liquid developer, a cyan (C) liquid developer, and a black (K) liquid developer, respectively. Image formation units  2 Y,  2 M,  2 C, and  2 K are arranged in tandem. In the tandem image formation units  2 Y,  2 M,  2 C, and  2 K, the reference designator  2 Y denotes a yellow image formation unit. The reference designator  2 M denotes a magenta image formation unit. The reference designator  2 C denotes a cyan image formation unit. The reference designator  2 K denotes a black image formation unit. In the following description, reference letters Y, M, C, and K are attached to reference numerals of other components as suffixes to indicate respective colors in the same manner as above. 
     The image formation units  2 Y,  2 M,  2 C, and  2 K are provided with photosensitive members  3 Y,  3 M,  3 C, and  3 K, respectively (collectively referred to as the photosensitive member  3 ). The photosensitive member  3  is an example of a latent image carrier according to an aspect of the invention. In the illustrated example of  FIG. 1A , each of the photosensitive members  3 Y,  3 M,  3 C, and  3 K is a photosensitive drum. Each of the photosensitive members  3 Y,  3 M,  3 C, and  3 K may be an endless belt. 
     The photosensitive members  3 Y,  3 M,  3 C, and  3 K rotate in a clockwise direction indicated by an arrow α in  FIG. 1A  during operation. As in the configuration of a conventional and well-known image formation apparatus that uses liquid developers, each of the image formation units  2 Y,  2 M,  2 C, and  2 K is provided with an electrification member, a light exposure device, a liquid developing device, a photosensitive member squeezing device, a diselectrification device, and a photosensitive member cleaning device that are provided around the corresponding one of the photosensitive members  3 Y,  3 M,  3 C, and  3 K. These components are not illustrated in the drawing. The electrification member, the light exposure device, the liquid developing device, the photosensitive member squeezing device, the diselectrification device, and the photosensitive member cleaning device are arranged in the order of appearance herein around each of the photosensitive members  3 Y,  3 M,  3 C, and  3 K when viewed in the direction of the rotation thereof. An electrostatic latent image of the corresponding color is formed on each of the photosensitive members  3 Y,  3 M,  3 C, and  3 K. Then, the electrostatic latent image of each color is developed by means of a liquid developer of the corresponding color. In this way, a toner image is formed on each of the photosensitive members  3 Y,  3 M,  3 C, and  3 K. 
     As illustrated in  FIG. 1A , the image formation apparatus  1  is provided with an intermediary image transfer belt  4 , which is an endless belt. The intermediary image transfer belt  4  is an example of a transfer medium according to an aspect of the invention. The transfer medium may be embodied as an image transfer roller. In the following description, the intermediary image transfer belt  4  is taken as an example of the transfer medium. The intermediary image transfer belt  4  is stretched between a belt driving roller  5  and a driven roller  7 . Another driven roller  6  that is also in contact with the intermediary image transfer belt  4  is provided as one of a pair of driven rollers. The power of a driving motor, which is not illustrated in the drawing, is transmitted to the belt driving roller  5 . The belt driving roller  5  and one of the pair of slave rollers, the driven roller  6 , are provided in the proximity of each other with a predetermined gap therebetween along a transfer target object movement direction β. A transfer target object (i.e., transfer material)  8  such as a sheet of printing paper or the like that is fed to a secondary image transfer device  14  is transported in the transfer target object movement direction β, which is indicated by an arrow in the drawing. The secondary image transfer device  14  is an example of a second transferring section, which will be explained later. The belt driving roller  5  and the other driven roller  7  are provided with a distance therebetween in the direction of the tandem arrangement of the photosensitive members  3 Y,  3 M,  3 C, and  3 K. A tension roller  9  applies a predetermined tension to the intermediary image transfer belt  4 . The intermediary image transfer belt  4  can turn in a counterclockwise direction indicated by an arrow γ in  FIG. 1A  when the belt driving roller  5  rotates. 
     The yellow image formation unit  2 Y, the magenta image formation unit  2 M, the cyan image formation unit  2 C, and the black image formation unit  2 K are arrayed in the order of appearance herein when viewed in the direction of the rotation γ of the intermediary image transfer belt  4 . That is, in the configuration of the image formation apparatus  1  illustrated in  FIG. 1 , the yellow image formation unit  2 Y is provided as the leftmost image formation unit whereas the black image formation unit  2 K is provided as the rightmost image formation unit. However, the order of the arrangement of the image formation units  2 Y,  2 M,  2 C, and  2 K is not limited to the illustrated example and may be modified arbitrarily. 
     Primary image transfer devices  10 Y,  10 M,  10 C, and  10 K (collectively referred to as the primary image transfer device  10 ) are provided at the periphery of the photosensitive members  3 Y,  3 M,  3 C, and  3 K, respectively. The primary image transfer device  10  is an example of a first transferring section according to an aspect of the invention. Each of the primary image transfer devices  10 Y,  10 M,  10 C, and  10 K is provided between the photosensitive member squeezing device and the diselectrification device, which are not shown in the drawing. The primary image transfer devices  10 Y,  10 M,  10 C, and  10 K are provided with primary image transfer backup rollers  11 Y,  11 M,  11 C, and  11 K, respectively. The backup rollers  11 Y,  11 M,  11 C, and  11 K apply a pressing force to the intermediary image transfer belt  4 . Accordingly, the intermediary image transfer belt  4  is in contact with the photosensitive members  3 Y,  3 M,  3 C, and  3 K. 
     Each of the backup rollers  11 Y,  11 M,  11 C, and  11 K is charged with a polarity that is opposite to the electrification polarity of toner particles. As a result, a toner image that is formed on each of the photosensitive members  3 Y,  3 M,  3 C, and  3 K is transferred onto the intermediary image transfer belt  4 . Each toner image is transferred onto the intermediary image transfer belt  4  as follows. A yellow (Y) toner image is transferred onto the intermediary image transfer belt  4  first. Next, a magenta (M) toner image is transferred onto the intermediary image transfer belt  4 . The magenta toner image is laid over the yellow toner image for color superposition. Thereafter, a cyan (C) toner image is transferred onto the intermediary image transfer belt  4 . The cyan toner image is laid over the superposed yellow-and-magenta toner image for color superposition. Subsequently, a black (K) toner image is transferred onto the intermediary image transfer belt  4 . The black toner image is laid over the superposed toner image for further superposition. In this way, a full color toner image is formed on the intermediary image transfer belt  4 . 
     Intermediary image transfer belt squeezing devices  12 Y,  12 M,  12 C, and  12 K are provided in the neighborhood of the primary image transfer devices  10 Y,  10 M,  10 C, and  10 K, respectively. The intermediary image transfer belt squeezing devices  12 Y,  12 M,  12 C, and  12 K are provided at downstream positions viewed from the primary image transfer devices  10 Y,  10 M,  10 C, and  10 K in the direction of the rotation γ of the intermediary image transfer belt  4 . Accordingly, the intermediary image transfer belt squeezing devices  12 Y,  12 M,  12 C, and  12 K are arranged closer to the secondary image transfer device  14 . The intermediary image transfer belt squeezing devices  12 Y,  12 M,  12 C, and  12 K are provided with intermediary image transfer belt squeezing rollers  13 Y,  13 M,  13 C, and  13 K, respectively. Each of the intermediary image transfer belt squeezing rollers  13 Y,  13 M,  13 C, and  13 K recovers carrier liquid of the corresponding color that remains on the intermediary image transfer belt  4 . 
     The secondary image transfer device  14  is provided at the belt-driving-roller ( 5 ) side of the intermediary image transfer belt  4 . The secondary image transfer device  14  is provided with an image transfer roller  15  that is indirectly in contact with the belt driving roller  5 . In particular, the image transfer roller  15  is in contact with a part of the intermediary image transfer belt  4  that is curved along and in contact with the belt driving roller  5 . The transfer target object  8  moves in the transfer target object movement direction β while being pinched at a transfer nip between the image transfer roller  15  and the intermediary image transfer belt  4 . In the process of the movement of the transfer target object  8 , a toner image (i.e., liquid-developer image) formed on the intermediary image transfer belt  4  is transferred onto the transfer target object  8 . Having the functions explained above, the intermediary image transfer belt  4  is an example of a transfer target object movement member and a liquid developer image carrier according to an aspect of the invention. 
     The image formation apparatus  1  according to the present embodiment of the invention is provided with a transfer target object storage device and a pair of resist rollers, as in the configuration of a conventional image formation apparatus that performs secondary image transfer. The transfer target object  8  such as sheets of paper or the like is stored in the transfer target object storage device. The transfer target object storage device is provided at an upstream position viewed from the secondary image transfer device  14  along the direction of the transportation of the transfer target object  8 . The pair of resist rollers feeds the transfer target object  8  picked up and transported from the transfer target object storage device to the secondary image transfer device  14 . The transfer target object storage device and the pair of resist rollers are not illustrated in the drawing. In addition, the image formation apparatus  1  is provided with a fixation device and a transfer target object ejection tray at a downstream side viewed from the secondary image transfer device  14  along the direction of the transportation of the transfer target object  8 . A transfer target object belt transportation device  16  is partially illustrated in  FIG. 1A . The transfer target object belt transportation device  16  transports the transfer target object  8  from the secondary image transfer device  14  to the fixation device. 
     As illustrated in  FIG. 1A , the secondary image transfer device  14  includes a transfer target object separation device  17  adjacent to the exit end of the transfer nip. As illustrated in  FIGS. 1B ,  2 , and  3 A in detail, the transfer target object separation device  17  is provided with a suction wheel  18  and a suction wheel support lever  19 . The suction wheel  18 , which is a vacuum wheel, is provided opposite to the driven roller  6 . The suction wheel  18  can be brought into contact with the intermediary image transfer belt  4  and distanced from the intermediary image transfer belt  4 . The suction wheel support lever  19  supports the suction wheel  18 . The suction wheel support lever  19  is provided on a device body  1   a . The suction wheel  18  and the suction wheel support lever  19  constitute an example of a transfer target object separation suction section according to an aspect of the invention. 
     The transfer target object separation device  17  further includes a cylindrical shaft  20  that is provided on the device body  1   a  as a rotatable shaft. The shaft  20  is an example of a first cylindrical rotation member according to an aspect of the invention. Partition walls  21  and  22  are provided on the shaft  20 . A concavity  23  is formed between a part of the partition wall  21  and an opposite part of the partition wall  22 . In addition, a suction port  24  is formed between another part of the partition wall  21  and an opposite part of the partition wall  22 . The cylindrical shaft  20  has an inner hole  20   a . The suction port  24  is formed as a communication port between the concavity  23  and the inner hole  20   a  of the shaft  20 . Because of this structure, the concavity  23  is always in communication with the inner hole  20   a  of the shaft  20  through the suction port  24 . The partition walls  21  and  22 , which have the concavity  23  and the suction port  24 , make up a nozzle  25 . The nozzle  25  takes the outside air into the inner hole  20   a  of the shaft  20 . 
     As illustrated in  FIGS. 1B ,  2 , and  3 A, the suction wheel  18  is provided on the shaft  20  rotatably. The suction wheel  18  is provided with a suction wheel outer cylinder  26 , which is rotatable and has an elongated cylindrical shape. The suction wheel outer cylinder  26  is an example of a second cylindrical rotation member according to an aspect of the invention. There is a small clearance between the outer circumferential surface of the suction wheel outer cylinder  26  and the intermediary image transfer belt  4 . 
     The nozzle  25  has an outer arc-shaped surface that has an outer diameter that is substantially the same as the inner diameter of the suction wheel outer cylinder  26 . The circumferential width W of the concavity  23  of the nozzle  25  having an arc is small. In the illustrated structure, the circumferential width W of the concavity  23  is slightly larger than the diameter of each through hole  27  of the suction wheel outer cylinder  26 . As illustrated in  FIG. 3B , the nozzle  25  has an elongated shape and extends in the axial direction of the shaft  20 . Three nozzles  25  are aligned in the axial direction of the shaft  20 . The structure of the nozzle  25  (and the number of the nozzles  25 ) is not limited to the illustrated example. For example, a single nozzle  25  that is longer than the illustrated nozzle  25  may be provided. Or, the number of the nozzles  25  may be two, or four or more. 
     As illustrated in  FIGS. 1 ,  4 A,  4 B, and  5 , a shaft driving motor  28  provided on the device body  1   a  supplies power for rotating the shaft  20 . The shaft driving motor  28  has a rotary shaft  28   a  that is indirectly connected to a gear  20   b , which is provided on the shaft  20  as a circumferential gear. A power transmission gear mechanism  29  is provided between the rotary shaft  28   a  of the shaft driving motor  28  and the gear  20   b  of the shaft  20 . When the shaft driving motor  28  rotates, the power of the shaft driving motor  28  is transmitted to the gear  20   b  through the power transmission gear mechanism  29  with speed reduction at the power transmission gear mechanism  29 . The shaft  20  turns under the driving power of the shaft driving motor  28 . The nozzle  25  turns together with the shaft  20 . 
     In the driving operation explained above, the shaft driving motor  28  causes the shaft  20  to turn in a reciprocating manner at a predetermined angle. For example, the shaft  20  reciprocates at an angle of approximately 30°. As a specific example, as illustrated in  FIG. 6 , the concavity  23  of the nozzle  25  turns in a reciprocating manner to change its position between a standby position δ, which is an initial position, a suction position ε, which is shifted from the standby position δ in the direction of rotation by a first predetermined angle θ 1  (e.g., approx. 15°), and a suction release position ζ, which is shifted from the suction position ε in the direction of rotation by a second predetermined angle θ 2  (e.g., approx. 15°). 
     An outer cylinder driving motor  30  provided on the device body  1   a  supplies power for rotating the suction wheel outer cylinder  26 . The outer cylinder driving motor  30  has a rotary shaft (not shown) that is indirectly connected to a gear  26   a , which is provided on the suction wheel outer cylinder  26  as a circumferential gear. A power transmission gear mechanism  31  is provided between the rotary shaft of the outer cylinder driving motor  30  and the gear  26   a  of the suction wheel outer cylinder  26 . When the outer cylinder driving motor  30  rotates, the power of the outer cylinder driving motor  30  is transmitted to the gear  26   a  through the power transmission gear mechanism  31  with speed reduction at the power transmission gear mechanism  31 . The suction wheel outer cylinder  26  turns under the driving power of the outer cylinder driving motor  30 . Therefore, the shaft  20  and the suction wheel outer cylinder  26  can rotate independently of each other. The outer cylinder driving motor  30  drives the suction wheel outer cylinder  26  to turn the suction wheel outer cylinder  26  in a reciprocating manner at the process speed of the image formation apparatus  1  without any restriction on an angle of rotation. Specifically, the circumferential velocity of the suction wheel outer cylinder  26  is the same as the circumferential velocity of the intermediary image transfer belt  4 . 
     As illustrated in  FIG. 4B , one end of the shaft  20  is closed whereas the other end thereof is open. As illustrated in  FIG. 7 , the open end of the shaft  20  is connected to a hose  33  via a coupling  32 . The hose  33  is connected to an air intake port  34   a  of a vacuum pump  34 . The vacuum pump  34  is an example of a vacuuming section according to an aspect of the invention. The vacuum pump  34  evacuates air from the inner hole  20   a  of the shaft  20  and then exhausts the vacuumed air from an air outlet port  34   b . Since the coupling  32  is provided between the shaft  20  and the hose  33 , the hose  33  does not get twisted when the shaft  20  turns. The coupling  32  enables the shaft  20  and the hose  33  to be securely connected to each other while keeping the connection airtight. 
     Next, the operation of the sucking of the front edge part of the transfer target object  8  by the nozzle  25  is explained below. The sucking operation described below is an example of a transfer target object separation control method according to an aspect of the invention. As illustrated in  FIG. 8A , the transfer target object  8  is transported from the right to the left when the concavity  23  of the nozzle  25  is set at the standby position δ (a standby position step). Next, the shaft driving motor  28  starts to rotate when the front edge of the transfer target object  8  moving in the transport direction arrives at a predetermined position that is in front of a pinch position at which the transfer target object  8  will be pinched between the intermediary image transfer belt  4  and the suction wheel outer cylinder  26 . Driven by the shaft driving motor  28 , the shaft  20  starts to rotate together with the nozzle  25 . At the same time, the outer cylinder driving motor  30  operates to turn the suction wheel outer cylinder  26  (a second cylindrical rotation member rotation step). During the operation explained above, slow-up control is performed to synchronize the rotation of the shaft  20 , the nozzle  25 , and the suction wheel outer cylinder  26  with the transport speed of the transfer target object  8 . 
     As illustrated in  FIG. 8B , the nozzle  25  arrives at the suction position ε when the front edge of the transfer target object  8  arrives at a separation start position after having been pinched between the intermediary image transfer belt  4  and the suction wheel outer cylinder  26  (a suction position step). The separation start position is a position at which the front edge of the transfer target object  8  starts to be separated from the intermediary image transfer belt  4 . When the nozzle  25  arrives at the suction position ε, the nozzle  25  starts to suck the front edge part of the transfer target object  8  (a transfer target object suction step). The position at which the suction wheel outer cylinder  26  comes opposite to the intermediary image transfer belt  4 , which is the position at which the suction wheel outer cylinder  26  and the intermediary image transfer belt  4  come closest to each other, is located slightly closer to the transfer target object belt transportation device  16  (which is the left side in  FIG. 8B ) in comparison with the position at which the intermediary image transfer belt  4  is in contact with the driven roller  6 . For this reason, as explained above, the suction wheel  18  can suck the front edge part of the transfer target object  8  effectively. 
     Thereafter, the suction wheel outer cylinder  26  rotates while the suction wheel  18  continues to suck the front edge part of the transfer target object  8 . The nozzle  25  also further rotates at the same speed as the rotation speed of the suction wheel outer cylinder  26  in overrun (a rotation step). Because of the overrun rotation of the nozzle  25 , the suction wheel  18  can continue to securely hold the front edge part of the transfer target object  8  by suction. Then, when the nozzle  25  arrives at the suction release position ζ as illustrated in  FIG. 8   c , the rotation of the shaft  20  and the nozzle  25  is stopped (a first cylindrical rotation member rotation stop step). On the other hand, the rotation of the suction wheel outer cylinder  26  continues. As a result, since the front edge part of the transfer target object  8  is displaced from the position of the concavity  23  of the nozzle  25 , the holding of the front edge part of the transfer target object  8  by suction is released. Accordingly, the rotation of the suction wheel outer cylinder  26  is stopped (a second cylindrical rotation member rotation stop step). As the transfer target object  8  continues to be transported, the front edge part of the transfer target object  8  comes off from the suction wheel  18 . The transfer target object  8  that has come off from the suction wheel  18  is transported to the transfer target object belt transportation device  16  and sucked by the transfer target object belt transportation device  16 . On the other hand, the shaft  20  and the nozzle  25  that stopped at the suction release position ζ are moved in the reverse rotation direction to be set at the standby position δ again. 
     The image formation apparatus  1  according to the present embodiment of the invention, which is provided with the transfer target object separation device  17  that has the structure explained above, offers the following advantages. The suction wheel outer cylinder  26  of the suction wheel  18  sucks a second surface of the transfer target object  8  after the transferring of an image to the transfer target object  8 . The second surface of the transfer target object  8  is a surface that is opposite a first surface thereof. The first surface of the transfer target object  8  is a transfer surface onto which the image is transferred. Since the suction wheel outer cylinder  26  sucks the transfer target object  8 , it is possible to separate the transfer target object  8  from the intermediary image transfer belt  4  without fail. In this sucking operation, the suction wheel outer cylinder  26  sucks the second surface of the transfer target object  8  that is the reverse side opposite the transfer surface. Therefore, it is possible to avoid a liquid-developer image transferred to the transfer target object  8  from being affected by the sucking operation. 
     In addition, since a predetermined number of through holes  27  is formed throughout the entire circumferential surface of the suction wheel outer cylinder  26 , it is possible to continuously hold the transfer target object  8  by suction during the sucking operation even when the suction wheel outer cylinder  26  rotates in synchronization with the movement of the transfer target object  8  and the intermediary image transfer belt  4 . Moreover, since air is continuously taken in through the concavity  23  that faces the transfer target object  8  during the sucking operation and has a small capacity and through the suction port  24 , it is possible to ensure that a suction force applied to the transfer target object  8  is large enough to separate the transfer target object  8  from the intermediary image transfer belt  4 . Therefore, the capacity of the vacuuming apparatus can be reduced. Furthermore, since the holding of the transfer target object  8  by suction is released when the hole of the suction wheel outer cylinder  26  is displaced from the position of the concavity  23 , and thus from the suction port  24 , it is possible to move the transfer target object  8  onto the next transport position smoothly. 
     In addition, since the nozzle  25  through which the front edge part of the transfer target object  8  is sucked also rotates when the suction wheel outer cylinder  26  rotates, it is possible to guide the front edge part of the transfer target object  8  to the position of the transfer target object belt transportation device  16  while securely holding the front edge part of the transfer target object  8  by suction. Since the front edge part of the transfer target object  8  is reliably sucked through the rotating nozzle  25 , it is possible to make the circumferential width W of the concavity  23  of the nozzle  25  further smaller (than that of the circumferential width of the concavity  23  of the foregoing example). By this means, the pressure loss of the suction wheel  18  can be reduced effectively, which makes it possible to reduce the size of the vacuum pump  34  and achieve cost reduction. Though a minor gap exists between the outer circumferential surface of the shaft  20  and the inner circumferential surface of the suction wheel  18  or between the outer circumferential surface of the nozzle  25  and the inner circumferential surface of the suction wheel  18 , the gap does not have any significant influence on the pressure loss. Needless to say, however, it is preferable to make these gaps smaller as much as possible in order to reduce the pressure loss. 
     The structure/configuration of the image formation apparatus  1  according to the present embodiment of the invention is not limited to the foregoing example. It may be modified in various ways. For example, a filter may be provided inside the open end of the shaft  20  to trap toner particles (solid content) of a liquid developer and liquid carrier (oil) of the liquid developer that are entrained with air when the air is taken in by the vacuum pump  34 . The filter prevents the toner particles (solid content) and the liquid carrier (oil) from taken into the vacuuming apparatus. Thus, it is possible to avoid the vacuuming apparatus from being stained due to the infiltration of the toner particles and the liquid carrier. 
     The suction wheel outer cylinder  26  may be provided as a movable member that can be brought into contact with the intermediary image transfer belt  4  and distanced from the intermediary image transfer belt  4 . Specifically, the suction wheel outer cylinder  26  may be set in contact with the intermediary image transfer belt  4  during the transportation of the transfer target object  8  only. In such a structure, the suction wheel outer cylinder  26  is set away from the intermediary image transfer belt  4  when the transfer target object  8  is not being transported. With such a structure, it is possible to prevent foreign substances such as remaining toner, dust, or the like that are attached to the intermediary image transfer belt  4  from moving onto the outer circumferential surface of the suction wheel outer cylinder  26 . Thus, it is possible to avoid the transfer target object  8  from becoming stained during the sucking of the transfer target object  8 . 
     As another modification example, a cleaning member that is in contact with the outer circumferential surface of the suction wheel outer cylinder  26  may be provided. The cleaning member automatically removes foreign substances that are attached to the outer circumferential surface of the suction wheel outer cylinder  26  during the rotation of the suction wheel outer cylinder  26 . Therefore, it is possible to ensure a reliable sucking operation that is free from the staining of the transfer target object  8  for a long time period. 
     As still another modification example, the image formation apparatus  1  may not be provided with the intermediary image transfer belt  4 . For example, the invention is applicable to a modified image formation apparatus that transfers a toner image that is formed with the use of a liquid developer on each of the photosensitive members  3 Y,  3 M,  3 C, and  3 K, which is an example of a latent image carrier, directly onto the transfer target object  8  without the intermediary transfer thereof onto the intermediary image transfer belt  4 . In such a modified image formation apparatus, a transfer target object separation device separates a transfer target object from the latent image carriers. Therefore, in this modified structure, the latent image carrier functions as the transfer target object movement member and the liquid developer image carrier according to an aspect of the invention. In addition, in the modified image formation apparatus, a set of backup rollers that applies pressure to a transfer target object so that the transfer target object is in contact with the latent image carriers (which corresponds to the aforementioned backup rollers  11 Y,  11 M,  11 C, and  11 K) is an example of a transferring member according to an aspect of the invention. The invention may be applied to a four-cycle image formation apparatus. The invention may be applied to a single-color image formation apparatus that uses a liquid developer of a single color. 
     A transfer target object separation apparatus according to an aspect of the invention is not limited to a device that is used for the separation of a transfer target object ejected from a transfer nip. For example, the transfer target object separation apparatus may be used for separating, from a fixation member, a transfer target object that is ejected from a fixation nip of a fixation apparatus. An example of the fixation member from which the transfer target object is separated is a fixation roller. The modified transfer target object separation apparatus is provided at a downstream neighboring position viewed from the exit end of the fixation nip. That is, the invention can be applied to various transfer target object separation apparatuses for separating a transfer target object from a transfer target object transport device and various image formation apparatuses provided with such an transfer target object separation apparatus, which may be modified, altered, changed, adapted, and/or improved within a range not departing from the gist and/or spirit of the invention apprehended by a person skilled in the art from explicit and implicit description made herein. Such a modification, alteration, change, adaptation, and/or improvement is also encompassed in the scope of the appended claims.