Abstract:
An image forming apparatus comprising: a transfer section for transferring a toner image on an image bearing member onto a transfer material; a conveyor for conveying the transfer material to a transfer position; a first guide for forming a guiding surface in said image bearing member side on a conveyance path between the transfer position and said conveyor; and a second guide for forming a guiding surface opposed to said first guide, wherein said first guide comprises a support member and a guiding member, which is supported by said support member and projected from said support member in a down stream side of a conveyance direction, said guiding member having a moving portion capable of elastically being deformed, and wherein said guiding member is formed so that a thickness of said guiding member becomes thin from an upper stream of the conveyance direction to a downstream of the conveyance direction.

Description:
[0001]    This application is based on Japanese Patent Application No. 2006-174905 filed on Jun. 26, 2006, in Japanese Patent Office, the entire content of which is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an image forming apparatus utilizing electrophotographic method. 
         [0003]    In the image forming apparatus utilizing electrophotographic method, an image on an image carrier, such as a photosensitive member or an intermediate transfer member is transferred onto a transfer material, such as a paper sheet to form the image onto the transfer material. When increasing an image forming speed or minimizing the size of the apparatus, there is a problem that in the transfer position where the image is transferred, the image quality deteriorates due to the disturbance of the image caused by the vibration of the rear edge of the transfer material. 
         [0004]    In the Japanese Patent Publications Open to Public Inspection Nos. 61-188345 and 8-76607, this problem was pointed out and the countermeasures to the problem have been proposed. 
         [0005]    Namely, in the Japanese Patent Publication Open to Public Inspection no. 61-188345, it is proposed to provide a guide plate (a sheet having elasticity, such as PET) for softly pressing the transfer material to the transfer position in the guiding section. 
         [0006]    In the Japanese Patent Publication Open to Public Inspection No. 8-76607, it has been proposed to fix a guiding member formed by an elastic body to the edges of a pair of guiding plates for guiding the transfer material to the transfer position and to bend the free edge of the guiding member with a predetermined angle. 
         [0007]    The image quality deterioration caused by the vibration of the rear edge of the transfer material will be described by using  FIG. 3 , which illustrates the transfer section of an image forming apparatus of the embodiment of the invention and  FIG. 1 , which illustrates an example of image quality deterioration. 
         [0008]    In  FIG. 3 , a registration roller  23  transfers a transfer material P to the transfer position TR formed by a transfer roller  7 A and a support roller (an earth roller  61 ), and a toner image is transferred onto the transfer material P from an intermediate transfer member  6 . 
         [0009]    Numerals  30  and  31  are a pair of guiding plates for guiding the transfer material P between the registration roller  23  and the transfer position TR, the pair of guiding plates being formed by a metal plate, which is a rigid body. 
         [0010]    When the rear edge of the transfer material P leaves from the registration roller  23 , the rear edge of the transfer material leaps up and vibrates, which causes toner scattering and transfer shifts. The toner scattering is a phenomenon that dots are formed in the non-image area as shown in  FIG. 1(   a ). The transfer-shift is the phenomenon that the image shifts as shown in  FIG. 1(   b ). It is known that the phenomenon occurs when the rigidity of the transfer material P is high in case the transfer material P is a thick paper sheet. The suppression effect of the toner scattering and the transfer shift will be obtained by suppressing the leap-up of the rear edge of the transfer material P by providing the guiding member  32  formed by the elastic body at the front edge of the upper support member  31 , namely by providing the guiding member  32  at the down stream edge of the transfer material conveyance direction, the leap up of the rear edge of the transfer material is suppressed and the suppression effect of the toner scattering and toner shift is obtained. 
         [0011]    In recent years, as a results of that the performance of the image forming apparatus has been improved, namely as a results of the diversity of utility categories for using color documents and for forming document other than the document for office use, only the countermeasures disclosed in the Japanese Patent Applications Open to Public Inspection S61-188345 and H8-76607 are not enough. Particularly, as a result of the diversity of the kinds of the transfer materials, which are used in the image forming apparatus, when the toner image is transferred onto a thick transfer material, the transfer shits and the toner scattering caused by the leap-up of the rear edge of the transfer material become problems. 
       SUMMARY OF THE INVENTION 
       [0012]    One aspect of the invention is, an image forming apparatus for forming a toner image onto a transfer material, the image forming apparatus comprising: an image bearing member; a transfer section for transferring the toner image on said image bearing member onto the transfer material; a conveyor for conveying the transfer material to a transfer position where the toner image is transferred by said transfer section; a first guide for forming a guiding surface in said image bearing member side on a conveyance path between the transfer position and said conveyor; and a second guide for forming a guiding surface opposed to said first guide, wherein said first guide comprises a support member and a guiding member, which is supported by said support member and projected from said support member in a down stream side of a conveyance direction, said guiding member having a moving portion, which is capable of elastically being deformed, and wherein said guiding member is formed so that a thickness of said guiding member becomes thin from an upper stream of the conveyance direction to a downstream of the conveyance direction. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  illustrates an example of image quality deterioration. 
           [0014]      FIG. 2  illustrates a total configuration of an image forming apparatus related to an embodiment of the present invention. 
           [0015]      FIG. 3  illustrates the second transfer section in the image forming apparatus illustrated in  FIG. 2 . 
           [0016]      FIGS. 4(   a ) to  4 ( e ) illustrates several examples of the guiding member  32 . 
           [0017]      FIGS. 5(   a ) to  5 ( f ) illustrates several examples of the guiding member  32 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The present invention will be described based on the embodiments of the present invention. However the present invention is not limited to the embodiments. In this specification, following sentences, such as “the front edge of the guiding plate” and “the rear edge of a transfer material” are used. In these cases, “the front edge” denotes the downstream side of the conveyance direction of the transfer material and the “the rear edge” denotes the upper-stream side of the conveyance direction of the transfer material. 
         [0019]      FIG. 2  illustrates a total configuration of an image forming apparatus related to an embodiment of the present invention. 
         [0020]    The image forming apparatus illustrated in  FIG. 2  is a color image forming apparatus, which is capable of forming a color image. The color image forming apparatus is configured by an image forming apparatus main body GH and an automatic document feed apparatus JG provided on the image forming apparatus main body GH. 
         [0021]    The image forming apparatus main body GH includes four image forming sections  10 Y,  10 M,  10 C and  10 K, a control section  100 , an intermediate transfer member  6  shaped like a belt, a sheet feed and conveyance section, a fixing section  24  and an operation and input section (not shown). The four image forming sections  10 Y,  10 M,  10 C and  10 K are arranged in parallel along with the moving direction of the intermediate transfer member  6  shaped like a belt, the intermediate transfer member  6  being arranged to rotate in an AA direction as shown in  FIG. 2 . The image forming apparatus main body GH is, so called, a full color image forming apparatus of a tandem system. 
         [0022]    The image forming section  10 Y for forming a yellow color image includes a charging section  2 Y, an exposing section  3 Y, a developing section  4 Y and a first cleaning section  8 Y, which are disposed around a photosensitive member  1 Y, which is an image carrier. The image forming section  10 M for forming a magenta color image includes, the same as described above, a photosensitive member  1 M, a charging section  2 M, an exposing section  3 M, a developing section  4 M and the first cleaning section  8 M. The image forming section  10 C for forming a cyan color image includes, the same as described above, a photosensitive member  1 C, a charging section  2 C, an exposing section  3 C, a developing section  4 C and the first cleaning section  8 C. The image forming section  10 K for forming a black color image includes, the same as described above, a photosensitive member  1 K, a charging section  2 K, an exposing section  3 K, a developing section  4 K and the first cleaning section  8 K. The charging section  2 Y and the exposing section  3 Y, the charging section  2 M and the exposing section  3 M, the charging section  2 C and the exposing section  3 C, and the charging section  2 K and the exposing section  3 K respectively configure electro-static latent image forming sections.  5 Y,  5 M,  5 C and  5 K denote toner containers respectively storing yellow toner, magenta toner, cyan toner and black toner. The toner is supplied correspond to the toner consumed in the developing sections  4 Y,  4 M,  4 C and  4 K from these toner containers. 
         [0023]    The photosensitive members  1 Y,  1 M,  1 C and  1 K are respectively OPC photosensitive members having negatively charged particles, the OPC photosensitive members being formed as an OPC photosensitive layers on the surface of the metal drams. The photosensitive members other than the OPC photosensitive members, such as aSi photosensitive member may be used as the photosensitive members  1 Y,  1 M,  1 C and  1 K. It is also possible to use photosensitive member having positively charged particles. Encoders (not shown), which output a plus in every one rotation, are respectively provided onto the photosensitive members  1 Y,  1 M,  1 C and  1 K. The control section  100  is arranged to respectively detect the outputs to count the number of rotations of the photosensitive member  1 Y,  1 M,  1 C and  1 K. 
         [0024]    A corotron discharger and a scorotron discharger may be used as the charging sections  2 Y,  2 M,  2 C and  2 K. A wire-type discharger or a saw shaped electrode discharger may also be used as the charging sections  2 Y,  2 M,  2 C and  2 K. 
         [0025]    The exposing section  3 Y has a semiconductor laser as a light source, which exposes the photosensitive member per a dot unit by using a laser beam based on yellow image data. The same as above, the exposing section  3 M exposes the photosensitive member  1 M by using a laser beam based on magenta image data, the exposing section  3 C exposes the photosensitive member  1 C by using a laser beam based on cyan image data and the exposing section  3 K exposes the photosensitive member  1 K by using a laser beam based on black image data. A LED array or the exposing section other than the laser beam, such as a liquid crystal may be used as the exposing sections  3 Y,  3 M,  3 C and  3 K. However, it is preferable that the exposure is conducted per a dot unit. 
         [0026]    The developing sections  4 Y,  4 M,  4 C and  4 K respectively have openings against the photosensitive members  1 Y,  1 M,  1 C and  1 K and include developing image carriers  46 Y,  46 M,  46 C and  46 K. A plurality of stirring screws  47 Y,  47 M,  47 C and  47 K for supplying stirred development agent to the developing agent carriers  46 Y,  46 M,  46 C and  46 K while stirring and conveying the development agent, the stirring screws  47 Y,  47 M,  47 C and  47 K being arranged to be shaped in a cylindrical style and to be capable of rotating. The toner replenished from the toner containers  5 Y,  5 M,  5 C and  5 K is supplied to the developing agent carriers  46 Y,  46 M,  46 C and  46 K while being stirred by the stirring screws  47 Y,  47 M,  47 C and  47 K. 
         [0027]    With respect to the developing agent, either of the two ingredients developing agent including toner and carriers or one ingredient developing agent including toner but not carriers may be used. 
         [0028]    The developing sections  4 Y,  4 M,  4 C and  4 K may be a reversed development system for adhering toner onto the exposing area or a normal developing system for adhering toner to non-exposing area. The developing sections  4 Y,  4 M,  4 C and  4 K may be either a contact developing system or a non-contact developing system. As described above, the system, which has been known, may be used as the developing sections  4 Y,  4 M,  4 C and  4 K. However, the two ingredient developing agent using a reversed developing system is preferable. 
         [0029]    The cleaning sections  8 Y,  8 M,  8 C and  8 K respectively include rubber cleaning blades  88 Y,  88 M,  88 C and  88 K as the first cleaning members formed in the longitudinal direction of the photosensitive members  1 Y,  1 M,  1 C and  1 K. The surfaces of the photosensitive members  1 Y,  1 M,  1 C and  1 K are scrubbed to be cleaned up when the photosensitive members  1 Y,  1 M,  1 C and  1 K are rotated under the condition that the edges of cleaning blades  88 Y,  88 M,  88 C and  88 K contact with the surface the photosensitive members  1 Y,  1 M,  1 C and  1 K. 
         [0030]    The intermediate transfer member  6  as an image carrier is formed by an endless belt having a semiconductor characteristic having a resister value of 10 5 Ω-10 10 Ω, which is put up over a plurality of rollers including an earth roller  61 . The intermediate transfer member  6  is supported so as to be capable of rotating and moving. The intermediate transfer member  6  is rotated and moved by the signals to the driving section (not shown) of the intermediate member from the control section  100 . 
         [0031]    The images of the respective colors formed by the image forming sections  10 Y,  10 M,  10 C and  10 K are sequentially transferred onto the intermediate transfer member  6 , which is called the first transfer, and a synthesized color image is formed by applying the first transfer output, which has an opposite polarity against, onto the first transfer sections  7 Y,  7 M,  7 C and  7 K and forming a transfer electric field, under the condition that the first transfer sections  7 Y,  7 M,  7 C and  7 K are pressed and contacted with the intermediate transfer member  6 , which is rotating and moving. 
         [0032]    The first transfer sections  7 Y,  7 M,  7 C and  7 K are basically released by a press release sections  71 Y,  71 M,  71 C and  71 K except when the image is formed, and the first transfer sections  7 Y,  7 M,  7 C and  7 K are away from the intermediate transfer member  6 . The first transfer sections  7 Y,  7 M,  7 C and  7 K are pressed to the intermediate transfer member  6  by the press release sections  71 Y,  71 M,  71 C and  71 K before the toner image, into which an image has been formed, reaches to an intermediate transfer position. The selection of press or release is changed and controlled by the output from the control section  100  to the press release sections  71 Y,  71 M,  71 C and  71 K. 
         [0033]    The first transfer outputs are respectively supplied to the first transfer sections  7 Y,  7 M,  7 C and  7 K from the first transfer output applying sections (not shown), which are respectively power sources. With respect to the control method of the first transfer outputs, which are inputted to the first transfer sections, there are two methods, (1) a constant current method for setting a predetermined target current value and controlling the transfer current to be the target current value and (2) a constant voltage method for setting a predetermined target voltage value and controlling the transfer voltage to the target voltage value. In (1), the current value becomes the first transfer output and in (2) the voltage value becomes the first transfer value. In this embodiment, the constant current method of (1) has been reduced to practice and the current value is set as the first transfer output. The control section  100  controls the first transfer outputs, which are the current values, and the input timings to the first transfer sections  7 Y,  7 M,  7 C and  7 K by the signals to the first transfer output applying section. When forming an image in a normal situation, the first transfer output is set at 30 μA so that the transfer rate becomes 100%. 
         [0034]    With respect to the first transfer section, a semiconductor roller having the resister value of 10 5 Ω-10 10 Ω is preferably used. 
         [0035]    Respective color toners remaining on the surfaces of the photosensitive members  1 Y,  1 M,  1 C and  1 K after having conducted the first transfer onto the intermediate transfer member  6  are cleaned by the cleaning blades  88 Y,  88 M,  88 C and  88 K, which are the first cleaning members. 
         [0036]    The transfer material P stored in a paper sheet feeding cassette  20  of a sheet feed and conveyance section is conveyed to the second transfer section  7 A via paper sheet feeding rollers  22 A,  22 B,  22 C,  22 D and the registration roller  23  after the transfer material P is fed by a paper sheet feeding section  21  of the sheet feed and conveyance section. The color image is secondary transferred onto the transfer material P at once. A fixing section  24  conducts a fixing process of the color image onto the transfer material P, to which the color image has been transferred. The transfer material P is nipped by an eject rollers  25  and placed onto an eject tray  26  provided the outside of the apparatus. 
         [0037]    On the other hand, after transferring the color image onto the transfer material P by the transfer section  7 A, the intermediate transfer member  6 , from which the transfer material P is separated, is cleaned up by the second cleaning section  8 A having a rubber cleaning blade  89 A, which is the second cleaning member formed along the width direction of the intermediate transfer member  6 . 
         [0038]      FIG. 3  illustrates the second transfer section in the image forming apparatus illustrated in  FIG. 2 . 
         [0039]    The transfer material P is conveyed by the registration roller  23  as a conveyor to the transfer position TR formed by the second transfer section  7 A structured by the transfer roller, to which the transfer voltage is applied, and the earth roller  61 . Then the toner image is transferred onto the transfer material P from the intermediate transfer member  6 . The intermediate transfer member  6  and the transfer roller  7 A form transfer nip at the transfer position TR. A sheet is nipped and conveyed by the intermediate transfer member  6  and the transfer roller  7 A and the toner image is transferred on the sheet. 
         [0040]    Numerals  30  and  31  structure a pair of guiding section between the registration roller  23  and the transfer position TR, which is structured by a metal sheet. Numeral  30  denotes a guiding plate for guiding the transfer material. Numeral  31  denotes a support member for supporting the guiding member  32 . In the example illustrated in  FIG. 3 , numeral  31  also has a function as a guiding plate for guiding the transfer material P. 
         [0041]    Numerals  33  and  34  denote guiding plates for forming the conveyance path in the upper stream of the support member  31 , the guiding path being structured by a metal plate. 
         [0042]    Numeral  32  denotes the guiding member, the base of which is fixed onto the front edge of the support member  31  structured by an elastic sheet of resin, such as PE (Polyethylene) and PET (Polyethylene Terephthalate), or rubber. The guiding member  32  is preferably a conductive material or a material, which has been processed not to be frictionally charged. 
         [0043]    The support member  31  and the guiding member  32  structure the first guiding section forming a guiding surface in the intermediate transfer member  6  side (an image carrier side) on the conveyance path located between the registration roller  23  and the transfer position TR. The guiding plate  30  structures the second guiding section forming the guiding surface opposed to the first guiding section. 
         [0044]    As described above, the guiding member  32  structured by an elastic body suppresses toner scattering and transfer shift. However, this suppression effect is not uniform across the various kinds of transfer material P. It has become clear that there is a case that the image deterioration cannot be prevented by simply providing the guiding member  32  when the transfer material P having a high rigidity. 
         [0045]    For example, when conducting transfer by using a paper sheet having a basis weight of 350 gsm by using the guiding member  32  capable of preventing the image deterioration for a paper sheet having basis weight of 200 gsm, since the rigidity of the guiding member becomes insufficient and the vibration cannot be relieved, toner scattering and transfer shift occur. 
         [0046]    When using the guiding member  32  capable of preventing the image deterioration against the paper sheet having a basis weight of 350 gsm, since the rigidity of the guiding member is excessive, the rear edge of the transfer material vibrates, and toner scattering and transfer shifts occur. 
         [0047]    When the image carrier is a belt, the vibration of the rear edge of the transfer material transmits to the image carrier and the image quality further deteriorates. 
         [0048]    Particularly, when the intermediate transfer member is an image carrier, since the intermediate transfer member is conductive, the charges of toner image leak via the intermediate transfer member and the absorbent force of the intermediate transfer member to the toner image becomes low. Thus, the toner image becomes easy to move on the intermediate transfer member and the image quality easily deteriorates. 
         [0049]    In this embodiment, providing the guiding member  32  as described below has solved these problems. 
         [0050]      FIGS. 4(   a ) to  4 ( e ) illustrate several examples of the guiding member  32 . 
         [0051]      FIG. 4(   a ) illustrates the structure of the guiding member  32 , which is structured by layering two elastic sheets  321  and  322  so that the thickness decreases along from the upper stream toward the downstream of the conveyance direction of the transfer material. 
         [0052]    The bases  321 B and  322 B of the elastic sheets  321  and  322  are attached onto the support member  31  by an adhesion and the front edge portions  321 A and  322 A structure a moving section, which are not regulated by the support member  31 . The length L 1  of the moving portion  321  A of the elastic sheet  321 , which is a far side from the image carrier, is formed so as to be longer than the length L 2  of the elastic sheet  322 . Based on this structure, when the outside force caused by the leap of the transfer material P is received, the nearer to the front edge of the guiding member  32 , the more deformed the guiding member  32  is, and the shock is relieved. 
         [0053]    The length of L 1  of the moving section  321 A is preferably set at 4-6 mm and the length L 2  of the moving section  322 A is set at 2-5 mm. 
         [0054]    When using the elastic sheet having a uniform thickness as the guiding member  32 , and selecting the thickness of the guiding member  32  based on a firm transfer material, the shock relief action of the guiding member  32  becomes insufficient, the vibration of the rear edge of the transfer material occurs, and toner scattering and transfer shits occur. When selecting the thickness of the guiding member  32  based on a weak-knead transfer material in case conveying the firm transfer material, the guiding member  32  is largely deformed and toner scattering and transfer shifts occur due to the shock of the deformation. 
         [0055]    In the image forming, in which various kinds of transfer materials having various kinds of stiffness or firmness are used, satisfactory transformation becomes possible by setting the thickness of the guiding member  32  so that thickness becomes thinner toward the front end (downstream of the conveyance direction) from the base (upper stream of the conveyance direction) of the guiding member  32 . 
         [0056]    The stiffness or firmness of the transfer material P mainly depends of the rigidity of the transfer material P. However, the stiffness or firmness of the transfer material P also depends on the size of the transfer material P. Namely, even though the transfer material has the same rigidity, the transfer material having a large size and a wide width has a firm characteristic in the stiffness or firmness. 
         [0057]      FIG. 4(   b ), the same as  FIG. 4(   a ), illustrates an example of the guiding member  32  having a structure, in which two elastic sheets are layered. In this example, the length L 2  of moving section of the elastic sheet  322 , which is located in the near side to the image carrier, is arranged to be longer than the length of L 1  of the moving section of the elastic sheet  321 , which is located in a far side of the image carrier. 
         [0058]      FIG. 4(   c ) illustrates an example, in which the guiding member  32  is adhered onto the surface opposite to the surface facing to the image carrier of the support member  31 . 
         [0059]      FIG. 4(   d ) illustrates an example, in which the elastic sheets  321  and  322  are adhered onto both surfaces of the support member  31  to form the guiding member  32 . In this example, the length of the moving section  322 A of the elastic sheet  322 , which is located in the near side to the image carrier is arranged to be loner than the length of the moving section  321 A of the elastic sheet  321 , which is located in the opposite side. 
         [0060]      FIG. 4(   e ), the same as the  FIG. 4(   d ), illustrates an example, in which the elastic sheets  321  and  322  are adhered onto both sides of the support member  31 . The respective lengths of the moving sections  321 A and  322 B are opposite to the example shown in  FIG. 4(   d ). 
         [0061]      FIGS. 5(   a ) and  5 ( b ) illustrate examples, in which the front edge of the support member  31  is formed to be thinner so that the front edges of the elastic sheets  321  and  322  come to closer toward the front edges of the elastic sheets  321  and  322 . 
         [0062]      FIG. 5(   c ) illustrates an example of the guiding member  32  structured by a plurality of elastic sheets  321  and  322  formed of different materials. In  FIG. 5(   c ), the moving section  321 A is structured by a short elastic sheet  321  of PET, and the moving section  322 A is structured by a long elastic sheet  322  of PE. In the example shown in  FIG. 5(   c ), it is preferable that a low rigidity material is used to form a longer elastic sheet  322  and a high rigidity material is used to form a shorter elastic sheet  321 . Based on these examples, it becomes possible to improve the vibration suppression effect for various kinds of transfer material. 
         [0063]      FIG. 5(   d ) illustrates an example of the guiding member structured by a plurality of elastic sheets  321  and  322  having different thickness. In this case, the same as the example shown in  FIG. 5(   c ), the same vibration suppression effect can be obtained. When setting the thickness of the shorter elastic sheet  321  thicker, the rigidity of the elastic sheet  322  also becomes higher and a satisfactory vibration suppression effect can be obtained. 
         [0064]      FIGS. 5(   e ) and  5 ( f ) illustrate examples of the guiding member  32 , in which the thickness is shaped thinner toward the front edge of the guiding member  32 .  FIG. 5(   e ) illustrates an example, in which the guiding member  32  is adhered onto the surface of the support member  31 , which is located in a near side to the image carrier.  FIG. 5(   f ) illustrates an example, in which the guiding member  32  is adhered onto the surface of the support member  31 , which is located in a far side to the image carrier. 
         [0065]    Within the examples shown in  FIGS. 4(   a ) to  4 ( e ) and  5 ( a ) to  5 ( f ), in the examples shown in  FIGS. 4(   a ),  4 ( b ),  5 ( c ),  5 ( d ) and  5 ( e ), the support member  31  and the guiding member  32  form the guiding surface of first guiding section. In  FIGS. 4(   c ),  4 ( d ),  4 ( e ),  5 ( a ),  5 ( b ) and  5 ( f ), the support member does not form the guiding surface and only the guiding member  32  forms the guiding surface of the first guiding section. 
         [0066]    An image forming experimental results, in which a black image formation has been continuously conducted under the condition that the conveyance speed of the transfer media including four kinds of transfer media having different paper sheet thicknesses (basis weights) is set at 220 mm/sec, will be shown in Table 1. 
         [0067]    In Table 1, relative example 1 shows the results obtained when the PET sheet having uniform thickness of 50 μm is used as the guiding member; relative example 2 shows the results obtained when the PET sheet having uniform thickness of 100 μm is used as the guiding member; and the embodiment shows results obtained when PET sheets having thickness of 50 μm are layered, the front edges of the PET sheets being shifted each other so that the lengths of moving sections become respectively 5 mm and 3.5 mm to form the guiding member and adhered to the support member. The length of the moving section in the relative examples 1 and 2 is set at 5 mm. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Relative 
                 Relative 
                   
               
               
                   
                   
                 example 1 
                 example 2 
                 Embodiment 
               
               
                   
                 Paper sheet 
                 One sheet 
                 One sheet 
                 Two sheets of 
               
               
                   
                 thickness 
                 of PET 
                 of PET 
                 PET 
               
               
                   
                 Basis 
                 Thickness 
                 Thickness 
                 Thickness 
               
               
                   
                 weight (gms) 
                 50 μm 
                 100 μm 
                 50 μm 
               
               
                   
                   
               
             
             
               
                   
                 200 
                 A 
                 C 
                 A 
               
               
                   
                 256 
                 B 
                 C 
                 A 
               
               
                   
                 300 
                 C 
                 B 
                 A 
               
               
                   
                 350 
                 C 
                 A 
                 A 
               
               
                   
                   
               
             
          
         
       
     
         [0068]    In Table 1, “A” denotes that a satisfactory image is formed; “B” denotes that a little toner scattering has been observed; and “C” denotes that notable toner scattering has been observed. 
         [0069]    According to the results shown in Table 1, it is clear that in the relative examples where a guiding member having a uniform thickness is used, in case of relative example 1, when the basis weight is relatively low and a transfer material has a relatively low rigidity, image deterioration does not occur. However, when the basis weight is relatively high and the transfer material has a relatively high rigidity, the image deterioration occurs. 
         [0070]    In case of relative example 2 where a guiding plate having a high rigidity is used, when the basis weight is relatively high and a transfer material has relatively high rigidity, image deterioration does not occur. However, when the basis weight is relatively low and the transfer material has a relatively low rigidity, the image deterioration occurs. 
         [0071]    On the contrary, in the embodiment, satisfactory image has been formed for all kinds of paper sheets. 
         [0072]    As described above, according to the embodiment, even when transferring a toner image onto transfer materials having largely different variations in firmness, toner scattering and transfer shifts can be sufficiently suppresses and a high quality image can be steadily formed.