Abstract:
The invention concerns an image-forming apparatus, which conduct folding processing that is suitable for a process to form an image on a sheet. The image forming apparatus includes: a first folding device and a second folding device, both of which conduct folding processing while conveying a sheet; a controller to control both of the first folding device and the second folding device; and a selector that makes it possible to select a two-folding mode or a three-folding mode; wherein the controller controls the first folding device so as to eject the sheet after folding the sheet double when the two-folding mode is selected by the selector, while the controller controls the first folding device so as to fold the sheet double, and then, further controls the second folding device so as to eject the sheet after further folding the sheet in three when the selector selects the three-folding mode.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a technology to make a document which is folded in two or in three, and in particular, to a technology to conduct folding processing that is suitable for a process to form an image on a sheet.  
           [0002]    A processing apparatus to conduct folding processing for a sheet is widely applied in the field of bookbinding, and a processing apparatus to fold a sheet or to fold relatively small number of sheets is also widely applied as one to make a sealed document for mail.  
           [0003]    Aforesaid any conventional folding processing apparatus mentioned above is a large-sized and expensive apparatus which is intended to conduct a large amount of processing at high speed.  
           [0004]    However, depending on a type of a document, there are a good many documents which are in relatively small quantity and require different handling, in addition to a large amount of unified documents. In the case of a sealed document such as a direct mail, a document wherein an individual slip carries different information such as an address and other information sometimes needs to be folded, and in that case, manual operations to group individual different document are needed before or after the documents are processed in the folding processing apparatus.  
           [0005]    As stated above, the conventional apparatus to conduct a large amount of uniform processing has a problem that overall efficiency cannot be improved.  
         SUMMARY OF THE INVENTION  
         [0006]    An object of the invention is to solve the aforesaid problem in the conventional folding processing apparatus in the case of processing documents wherein a group of documents in a small quantity is different each other, and documents wherein an individual slip is different each other, and to provide a small-sized and inexpensive finishing apparatus which can cope flexibly with various applications and can make folded documents at high overall efficiency and an image forming apparatus having therein the finishing apparatus.  
           [0007]    Accordingly, to overcome the cited shortcomings, the abovementioned object of the present invention can be attained by image-forming apparatus and finishers described as follow.  
           [0008]    (1) An image forming apparatus, comprising: a first folding device and a second folding device, both of which conduct folding processing while conveying a sheet; a controller to control both of the first folding device and the second folding device; and a selector that makes it possible to select a two-folding mode or a three-folding mode; wherein the controller controls the first folding device so as to eject the sheet after folding the sheet double when the two-folding mode is selected by the selector, while the controller controls the first folding device so as to fold the sheet double, and then, further controls the second folding device so as to eject the sheet after further folding the sheet in three when the selector selects the three-folding mode.  
           [0009]    (2) The image-forming apparatus of item  1 , wherein the first folding device comprises: a first conveyance-folding device that conveys the sheet; and a knife-shaped folding member to feed the sheet into the first conveyance-folding device in a state that a folded portion of the sheet is its forefront, and the second folding device comprises: a second conveyance-folding device that folds and conveys the sheet; and a stop guiding member to stop a leading edge of the sheet conveyed by the second conveyance-folding device.  
           [0010]    (3) The image-forming apparatus of item  2 , wherein the stop guiding member guides the sheet along a conveyance path of the sheet in a three-folding process, while the stop guiding member retreats from the conveyance path in a two-folding process.  
           [0011]    (4) The image-forming apparatus of item  1 , further comprising a binding device, wherein the binding device, the first folding device and the second folding device are successively arranged in a conveyance direction of the sheet.  
           [0012]    (5) The image-forming apparatus of item  4 , wherein the binding device comprises an intermediate stacker inclined, and the first folding device is arranged along a conveyance path that is inclined in a direction opposite to that of the intermediate stacker.  
           [0013]    (6) The image-forming apparatus of item  4 , wherein the binding device comprises an intermediate stacker inclined, and the first folding device is arranged along a conveyance path that is inclined in the same direction as that of the intermediate stacker.  
           [0014]    (7) The image-forming apparatus of item  1 , further comprising a binding device, wherein the binding device is arranged on a downstream side in a conveyance path of the sheet with respect to the first folding device.  
           [0015]    (8) The image-forming apparatus of item  1 , further comprising: a stacking member disposed on the upstream side of the first folding device to stack a plurality of sheets on it.  
           [0016]    (9) An image-forming method, comprising the steps of: forming an image on an obverse surface of a sheet; conveying the sheet on which the image is formed; folding the sheet at a first position that is about ⅔ of its total length from a leading edge of the sheet in a conveyance direction of the sheet so that the obverse surface becomes convex, in a first folding process; and folding the sheet at a second position that is about ⅓ of its total length from the leading edge of the sheet in the conveyance direction of the sheet so that the obverse surface becomes convex, in a second folding process.  
           [0017]    (10) The image-forming method of item  9 , wherein the first folding process and the second folding process are conducted for the sheet that is conveyed so that a tip of the image is positioned at the leading edge of the sheet.  
           [0018]    (11) An image-forming apparatus, comprising: an image-forming device to form an image on an obverse surface of a sheet; a first folding device to convey the sheet on which the image is formed and to fold the sheet at a first position that is about ⅔ of its total length from a leading edge of the sheet in a conveyance direction of the sheet so that the obverse surface becomes convex; and a second folding device to fold the sheet, folded by the first folding device, at a second position that is about ⅓ of its total length from the leading edge of the sheet in the conveyance direction of the sheet so that the obverse surface becomes convex.  
           [0019]    (12) The image-forming apparatus of item  11 , wherein a folding process conducted by the first folding device is only enabled, and a delivering operation of the sheet, which is folded double, is enabled.  
           [0020]    (13) The image-forming apparatus of item  11 , wherein the first folding device comprises a knife-shaped folding member.  
           [0021]    (14) The image-forming apparatus of item  11 , wherein the second folding device comprises: a conveyance-folding device to convey and fold the sheet; and a stop guiding member to stop a leading edge of the sheet conveyed by the conveyance-folding device.  
           [0022]    (15) A method for finishing a sheet on which an image is formed, wherein a first folding device folds the sheet in case of folding the sheet double, while a second folding device further folds the sheet after the first folding device folds the sheet in case of folding the sheet in three.  
           [0023]    (16) A finisher for finishing a sheet on which an image is formed, comprising: a first folding roller; a second folding roller contacting the first folding roller; a knife-shaped folding member to insert a folded portion of the sheet into a nip formed between the first folding roller and the second folding roller; a third folding roller contacting the second folding roller at a downstream side of the first folding roller in a conveyance direction of the sheet; and a stopper guide member to stop the sheet conveyed by the second folding roller; wherein a combination of the first folding roller, the second folding roller and the knife-shaped folding member folds the sheet as a first folding process, while a combination of the second folding roller, the third folding roller and the stopper guide member folds the sheet as a second folding process.  
           [0024]    (17) A finisher for finishing a sheet on which an image is formed, comprising: a first folding roller; a second folding roller contacting the first folding roller; a third folding roller; a conveyance roller contacting the third folding roller; a knife-shaped folding member to insert a folded portion of the sheet into a nip formed between the first folding roller and the second folding roller; a fourth folding roller contacting the third folding roller at a downstream side of the conveyance roller; and a stopper guide member to stop the sheet conveyed by the third folding roller and the conveyance roller, wherein a combination of the first folding roller, the second folding roller and the knife-shaped folding member folds the sheet as a first folding process, while a combination of the third folding roller, the fourth folding roller, the conveyance roller and the stopper guide member folds the sheet as a second folding process.  
           [0025]    (18) An image-forming apparatus, comprising: an image forming device to form images on both obverse and reverse surfaces of a sheet in such a manner that a directions of the images are maintained at a constant in respect to a leading edge and a trailing edge of the sheet conveyed in a conveyance path; and a finisher, comprising a folding device to convey the sheet delivered from the image forming device and to fold the sheet at first and second positions that are about ⅓ and ⅔ of its total length from a leading edge of the sheet in a conveyance direction of the sheet so that the obverse surface becomes convex.  
           [0026]    (19) The image-forming apparatus of item  18 , wherein the image forming device feeds the sheet into the finisher in such a manner that a rear end of an image comes to the leading edge of the sheet conveyed in the folding device, and the finisher comprises a reversing member to reverse the sheet in terms of leading and trailing sides of the sheet in its conveyance direction, and the folding device folds the sheet at a position which is about ⅓ of a total length of the sheet after folding the sheet at a position which is about ⅔ of the total length.  
           [0027]    (20) The image-forming apparatus of item  18 , wherein the image forming device feeds the sheet into the finisher in such a manner that the reverse surface of the sheet faces upward.  
           [0028]    (21) The image-forming apparatus of item  18 , wherein the folding device comprises a stacking member to stack a plurality of sheets on it.  
           [0029]    (22) The image-forming apparatus of item  18 , wherein the finisher comprises a binding device, and the binding device and the folding device are arranged in succession from an upstream side in a conveyance direction of the sheet fed from the image-forming device.  
           [0030]    (23) The image-forming apparatus of item  18 , wherein the finisher comprises a binding device, and the folding device and the binding device are arranged in succession from an upstream side in a conveyance direction of the sheet fed from the image-forming device.  
           [0031]    Further, to overcome the abovementioned problems, other image-forming apparatus and finishers, embodied in the present invention, will be described as follow:  
           [0032]    Structure 1  
           [0033]    An image forming apparatus having therein a first and second folding means to conduct folding processing while conveying a sheet, a selecting means to select a two-folding mode or a three-folding mode, and a control means, wherein when the two-folding mode is selected by the selecting means, the control means conducts the control to operate the first folding means to fold a sheet double to eject, while, when the three-folding mode is selected by the selecting means, the control means conducts the control to operate the first folding means to fold a sheet and to operate the second folding means to further fold to fold in three to eject.  
           [0034]    Structure 2  
           [0035]    The image forming apparatus according to Structure 1 wherein the first folding means has a first conveyance folding means that conveys a sheet and a knife-shaped folding member that feeds a sheet in the first conveyance folding means with the folded portion of the sheet being in the forefront, and the second folding means has a second conveyance folding means that folds a sheet and conveys it and a stop guiding member that bends a sheet by stopping a movement of a leading edge of the sheet conveyed by the second conveyance folding means.  
           [0036]    Structure 3  
           [0037]    The image forming apparatus according to Structure 2, wherein the stop guiding member guides a sheet along a conveyance path for a sheet in the case of three-folding processing, and the stop guiding member retreats from the conveyance path for a sheet in the case of two-folding processing.  
           [0038]    Structure 4  
           [0039]    The processing apparatus according to either one of the Structures 1-3, wherein a binding means is provided, and the binding means, the first folding means and the second folding means are arranged in succession along the conveyance path for a sheet.  
           [0040]    Structure 5  
           [0041]    The image forming apparatus according to Structure 4, wherein the binding means has an inclined intermediate stacker, and the first folding means is arranged along the conveyance path that is inclined in the direction opposite to that of the intermediate stacker.  
           [0042]    Structure 6  
           [0043]    The image forming apparatus according to Structure 4, wherein the binding means has an inclined intermediate stacker, and the first folding means is arranged along the conveyance path inclined in the same direction as in the intermediate stacker.  
           [0044]    Structure 7  
           [0045]    The image forming apparatus according to either one of Structures 1-3, wherein a binding means is provided, and the binding means is arranged at the downstream side of the first folding means in the conveyance path for a sheet.  
           [0046]    Structure 8  
           [0047]    The image forming apparatus according to either one of Structures 1-7, wherein a stacking means on which a plurality of sheets are stacked is provided at the upstream side of the folding means.  
           [0048]    Structure 9  
           [0049]    An image forming method having therein an image forming process to form an image on at least the obverse of a sheet, a first folding process to convey an image-formed sheet, and to fold the sheet at the position that is about ⅔ of the total length of the sheet from its leading edge in the conveyance direction so that the image-formed obverse may be convex, and a second folding process to fold the sheet folded in the first folding process at the position that is about ⅓ of the total length of the sheet from its leading edge in the conveyance direction so that the image-formed surface may be convex.  
           [0050]    Structure 10  
           [0051]    The image forming method according to Structure 9, wherein the first folding process and the second folding process are conducted for the sheet that is conveyed so that a tip of an image is positioned at a leading edge of the sheet.  
           [0052]    Structure 11  
           [0053]    An image forming apparatus having therein an image forming means to form an image on at least the obverse of a sheet, a first folding process to convey an image-formed sheet, and to fold the sheet at the position that is about ⅔ of the total length of the sheet from its leading edge in the conveyance direction so that the image-formed obverse may be convex, and a second folding means to fold the sheet folded in the first folding process at the position that is about ⅓ of the total length of the sheet from its leading edge in the conveyance direction so that the image-formed surface may be convex.  
           [0054]    Structure 12  
           [0055]    The image forming apparatus according to Structure 11, wherein only folding processing by the first folding means is conducted, and the sheet folded in two can be ejected.  
           [0056]    Structure 13  
           [0057]    The image forming apparatus according to Structure 11 or Structure 12, wherein the first folding means is provided with a knife-shaped folding member.  
           [0058]    Structure 14  
           [0059]    The image forming apparatus according to either one of Structure 11-Structure 13, wherein the second folding means has therein a conveyance/folding means that conveys a sheet and folds it and a stopper guide member that folds a sheet by stopping the movement of a leading edge of the sheet conveyed by the conveyance/folding means.  
           [0060]    Structure 15  
           [0061]    A sheet processing method for finishing the image-formed sheet, wherein, when folding a sheet in two, the folding is performed by a first folding means, while, when folding a sheet in three, the first folding means conducts folding and then a second folding means conducts folding.  
           [0062]    Structure 16  
           [0063]    A finishing apparatus having therein a first folding roller, a second folding roller that comes in contact with the first folding roller, a knife-shaped folding member that feeds the folded portion of a sheet into a gap between the first folding roller and the second folding roller, a third folding roller that comes in contact with the second folding roller at the downstream side of the first folding roller in the conveyance direction, and a stopper guide member that stops an advance of the sheet conveyed by the second folding roller, wherein, the first folding is conducted by the first folding roller, the second folding roller and the knife-shaped folding member, while, the second folding is conducted by the second folding roller, the third folding roller and the stopper guide member.  
           [0064]    Structure 17  
           [0065]    A finishing apparatus having therein a first folding roller, a second folding roller that comes in contact with the first folding roller, a third folding roller, a conveyance roller that comes in contact with the third folding roller, a knife-shaped folding member that feeds the folded portion of a sheet into a gap between the first folding roller and the second folding roller, a fourth folding roller that comes in contact with the third folding roller at the downstream side of the conveyance roller, and a stopper guide member that stops an advance of the sheet conveyed by the third folding roller and the conveyance roller, wherein, the first folding is conducted by the first folding roller, the second folding roller and the knife-shaped folding member, while, the second folding is conducted by the third folding roller, the fourth folding roller, the conveyance roller and the stopper guide member.  
           [0066]    Structure 18  
           [0067]    An image forming apparatus having therein an image forming means capable of forming images on both the obverse and the reverse of a sheet in a way that no change is made on relationship between the leading edge and the trailing edge of the conveyed sheet in terms of the image direction, and a finishing apparatus equipped with a folding means that conveys the sheet ejected from the image forming means and conducts folding of a sheet at the positions which are about ⅓ and ⅔ of the total length of the sheet from its leading edge in the conveyance direction so that the obverse of the sheet may be convex.  
           [0068]    Structure 19  
           [0069]    The image forming apparatus according to Structure 18, wherein the image forming means feeds a sheet into the finishing apparatus in a way that a rear end of an image comes to a leading edge of the sheet that is conveyed by the folding means, the finishing apparatus has a reversing means that inverts the sheet in the conveyance direction in terms of front and rear, and the folding means conducts folding at the position which is about ⅔ of the total length of the sheet and then, conducts folding at the position which is about ⅓.  
           [0070]    Structure 20  
           [0071]    The image forming apparatus according to Structure 18 or Structure 19, wherein the image forming means feeds a sheet into the finishing apparatus with the reverse of the sheet facing upward.  
           [0072]    Structure 21  
           [0073]    The image forming apparatus according to either one of Structure 18-Structure 20, wherein the folding means has a stacking means on which a plurality of sheets are stacked.  
           [0074]    Structure 22  
           [0075]    The image forming apparatus according to either one of Structure 18-Structure 21, wherein a binding means is provided, and a binding processing means and a folding means are arranged in succession from the upstream side along the conveyance path into which the sheet has been fed.  
           [0076]    Structure 23  
           [0077]    The image forming apparatus according to either one of Structure 18-Structure 21, wherein a binding means is provided, and a folding means and a binding means and are arranged in succession from the upstream side along the conveyance path into which the sheet has been fed.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0078]    Other objects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:  
         [0079]    [0079]FIG. 1 is a diagram showing the overall structure of an image forming apparatus related to Embodiment 1 of the invention;  
         [0080]    [0080]FIG. 2 is a diagram showing a flow of a sheet in a finishing apparatus related to Embodiment 1 of the invention;  
         [0081]    [0081]FIG. 3 is a front view of a folding means;  
         [0082]    [0082]FIG. 4 is a diagram showing operations of main portions of a folding means in the case of folding in three;  
         [0083]    [0083]FIG. 5 is a diagram showing relationship between sheet S and an image direction in image forming and folding processing;  
         [0084]    [0084]FIG. 6 is a diagram showing operations of main portions of a folding means in the case of folding in two;  
         [0085]    [0085]FIG. 7 is a block diagram of a control system of an image forming apparatus related to an embodiment of the invention;  
         [0086]    [0086]FIG. 8 is a diagram showing the structure of a finishing apparatus related to Embodiment 2 of the invention;  
         [0087]    [0087]FIG. 9 is a diagram showing operations of main portions of a folding means in the case of folding in three;  
         [0088]    [0088]FIG. 10 is a diagram showing operations of main portions of a folding means in the case of folding in three;  
         [0089]    [0089]FIG. 11 is a diagram showing operations of main portions of a folding means in the case of folding in two; and  
         [0090]    [0090]FIG. 12 is a diagram showing the structure of a finishing apparatus related to Embodiment 3 of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0091]    (1) Image Forming Apparatus  
         [0092]    [0092]FIG. 1 is a diagram showing the overall structure of an image forming apparatus related to an embodiment of the invention. The image forming apparatus related to an embodiment of the invention is composed of image forming apparatus main body A and finishing apparatus FS.  
         [0093]    The image forming apparatus main body A is provided with image reading section  1 , image processing section  2 , image writing section  3 , image forming section  4 , cassette sheet feeding section  5 , large capacity sheet feeding section (LCT)  6 , fixing unit  7 , sheet ejection section  8  and reverse side image forming sheet feeding section  9 .  
         [0094]    The image forming apparatus main body A further has on its top automatic document feeding device DF. On the illustrated left side of the image forming apparatus main body A representing sheet ejection section  8  side, there is connected finishing apparatus FS.  
         [0095]    Document d placed on a document stand of the automatic document feeding device DF is conveyed in the direction of an arrow, and is read by CCD image sensor  1 A of image reading section  1 .  
         [0096]    Analog signals subjected to photoelectric conversion by CCD image sensor  1 A are subjected to analog processing, A/D conversion, shading correction and image compression processing in image processing section  2 , and signals are sent to image writing section  3 .  
         [0097]    In the image writing section  3 , output from a semiconductor laser is radiated on a photoreceptor drum of image forming section  4  to form a latent image. In the image forming section  4 , there are conducted processes including charging, exposure, developing, transferring, separating and cleaning, and images are transferred onto sheet S conveyed from cassette sheet feeding section  5  or large capacity sheet ejection section  6 . The image writing section  3 , the image forming section  4  and fixing unit  7  constitute an image forming means. Sheet S carrying images is subjected to fixing by the fixing unit  7 , and is fed into finishing apparatus FS from sheet ejection section  8 . Or, sheet S that is fed into reverse side image forming sheet feeding section  9  by conveyance path switching plate  8 A with its one side subjected to image processing is subjected again to reverse side image processing in the image forming section  4 , and then, is fed into sheet finishing apparatus FS from sheet ejection section  8 .  
         [0098]    Switches to three occasions including an occasion where image-formed sheet S is ejected, as it is, to finishing apparatus FS in a single-side mode, an occasion where image-formed sheet S is ejected to finishing apparatus FS after being inverted in terms of obverse and reverse in a single-side mode, and an occasion where a sheet having images on its one side is fed into reverse side image forming sheet feeding section  9  in a two-side mode. In the two-side image forming mode, sheet S having images on its both sides is ejected with images on the reverse side facing upward, and is fed into finishing apparatus FS from image forming apparatus main body A.  
         [0099]    On the finishing apparatus FS, there are arranged, from end to end, almost vertically from the illustrated upper portion fixed sheet ejection tray  91 , cover feeding means  40  on which covers K are placed, shift processing conveyance section  20 , a binding means composed of intermediate stacker  30  and stapler  50 , and folding means  60  (explained in detail in FIGS. 3, 4 and  5 ).  
         [0100]    On the upper portion on the right side in the illustration of the finishing apparatus FS, there is arranged entrance conveyance section  10 . On the left side of the finishing apparatus FS in the illustration, there are arranged fluctuating sheet ejection tray  92  on which end-bound and shift-processed sheets are stacked and fixed sheet ejection tray  93  on which processed sheets folded in three or folded in two are stacked.  
         [0101]    (2) Embodiment 1  
         [0102]    [0102]FIG. 2 is a diagram showing a flow of sheet S in finishing apparatus FS related to Embodiment 1 of the invention.  
         [0103]    The finishing apparatus FS is installed with its position and height adjusted so that accepting section  11  for sheet S ejected out of image forming apparatus main body A may agree, in terms of position, with sheet ejection section  8  of the image forming apparatus main body A.  
         [0104]    At the accepting section  11 , there are provided conveyance rollers  12 , and at the downstream side of the conveyance rollers  12 , there are arranged a first conveyance path ( 1 ) on the upper step, a second conveyance path ( 2 ) on the medium step, and a third conveyance paths ( 3 ) and a fourth conveyance path ( 4 ) both on the lower step.  
         [0105]    How sheet S is conveyed in the first conveyance path ( 1 )—fourth conveyance path ( 4 ) will be explained as follows.  
         [0106]    (2)—1. Simple Sheet Ejection  
         [0107]    The first conveyance path ( 1 ) is a sheet ejection path through which image-formed sheet S is ejected to be stacked in the order of ejection. In the sheet ejection mode to use the first conveyance path ( 1 ), gate G 1  opens the first conveyance path ( 1 ) to close a path to conveyance roller  18 . The image-formed sheet S ejected out of the image forming apparatus main body A is guided in the accepting section  11  to be conveyed by conveyance rollers  12 , and thereby a length of the sheet S in the direction of the conveyance is detected by entrance section sensor PS 1  for detection of entrance passage. The sheet S is guided by gate G 1  to enter the first conveyance path ( 1 ), and is conveyed by conveyance rollers  14 ,  15  and  16  to be ejected onto the fixed sheet ejection tray  91 .  
         [0108]    (2)—2. Shift Sheet Ejection  
         [0109]    The second conveyance path ( 2 ) is a conveyance path through which the image-formed sheet S is ejected onto fluctuating sheet ejection tray  92  after being subjected to grouping processing to be shifted in the conveyance transverse direction (direction perpendicular to the conveyance direction, the same shall apply hereinafter) for each prescribed number of sheets such as each number of documents, for example. In the mode to use this conveyance path, the Gate G 1  closes the first conveyance path ( 1 ) to open a path to conveyance rollers  18 , and gate G 2  opens the second conveyance path ( 2 ) to close the third conveyance path ( 3 ). The sheet S conveyed by the conveyance rollers  12  is conveyed to the second conveyance path ( 2 ), and is conveyed to shift processing section  20  by conveyance rollers  22 . Conveyance rollers  24  in the shift processing section  20  have a shift conveyance function to shift in the conveyance transverse direction directly after receiving the leading edge of the sheet S and to convey the sheet S. The sheet S which has passed the shift processing section  20  is ejected onto fluctuating sheet ejection tray  92  by sheet ejection rollers  26 .  
         [0110]    (2)—3. Binding Processing  
         [0111]    The third conveyance path ( 3 ) is a conveyance path for conducting binding processing for each prescribed number of sheets S, such as, for example, each number of documents. In the mode to use this conveyance path, the Gate G 1  closes the first conveyance path ( 1 ) to open a path to conveyance rollers  18 , and gate G 2  closes the second conveyance path ( 2 ) to open the third conveyance path ( 3 ). The sheet S is conveyed by conveyance rollers  18 ,  32  and  34  to be fed into intermediate stacker  30 . When the trailing edge of the sheet S leaves the conveyance rollers  34 , the sheet S slides down along the intermediate stacker  30  to hit movable stopper  51 , and stops. The intermediate stacker  30  serves as a stacking means on which sheets S are stacked and as a reversing means that inverts the sheet S in the conveyance direction in terms of front and rear.  
         [0112]    When sheets S in quantity of the prescribed number, for example, sheets S equivalent to the number of sheets of documents in terms of quantity are stacked on the intermediate stacker  30 , stapler  50  operates to conduct binding processing.  
         [0113]    In the binding processing mode, it is possible to append a cover, a back cover or an interleaf to a bundle of sheets S. Sheet K for a cover, a back cover or an interleaf is fed from sheet feeding means  40  and is supplied to intermediate stacker  30 . In the mode to append sheet K, when sheets K set to sheets S in quantity of the prescribed number are appended, stapler  50  operates to conduct binding processing for a bundle of sheets.  
         [0114]    The bundle of sheets thus bound are ejected onto fluctuating sheet ejection tray  92  by a conveyance belt of intermediate stacker  30  and by sheet ejection rollers  26 .  
         [0115]    (2)—4. Folding Processing  
         [0116]    The fourth conveyance path ( 4 ) is a conveyance path for ejecting image-formed sheet S to fixed sheet ejection tray  93  by folding in three or by folding in two, and the sheet S passes through the third conveyance path ( 3 ) and passes through movable stopper S located at a shunting position to be conveyed to the fourth conveyance path ( 4 ).  
         [0117]    First, processing to fold sheet S in three in the fourth conveyance path ( 4 ) will be explained in detail, referring to FIGS. 3 and 4.  
         [0118]    [0118]FIG. 3 is a front view of folding means  60 , and FIG. 4 is a diagram showing operations of main portions of the folding means  60  in the case of folding in three. the folding means  60  has therein first folding means  67  composed of folding roller R 1  representing a first folding roller constituting a first conveying/folding means, folding roller R 2  representing a second folding roller constituting a first conveying/folding means and knife-shaped folding member  661 , and second folding means  68  composed of conveyance roller R 3 , folding roller R 4  representing a third folding roller constituting a second conveying/folding means and folding roller R 5  representing a fourth folding roller constituting a second conveying/folding means. Though each of the first conveying/folding means and the second conveying/folding means is composed of folding rollers R 1 , R 2 , R 4  and R 5  respectively, it is also possible to construct these conveying/folding means with belts and rollers.  
         [0119]    In the mode to conduct processing of folding in three, sheet S is conveyed to intermediate stacker  30  through the aforesaid conveyance path. In this mode, the movable stopper  51  is in the shunting position, and sheet S passes through intermediate stacker  30  and descends to movable stopper  52 . At the stage where sheets S in quantity of the prescribed number (for example, maximum three sheets) are stacked at the position of the movable stopper  52 , the movable stopper  52  retreats, and sheets S are conveyed to conveyance belt  62  by conveyance rollers  61 .  
         [0120]    A path inclined in the direction opposite to that for the intermediate stacker  30  is formed by conveyance belt  62  arranged to be inclined, first guide plate  63  that faces the conveyance belt  62  and by paired second guide plates  64 . On the second guide plates  64 , there is provided stopper  65  which can be adjusted in terms of position in the feeding direction for sheet S. Further, there is arranged knife-shaped folding member  661  having folding tip portion  661 A, between the first guide plate  63  and the second guide plates  64 . The folding member  661  is fixed on U-shaped connecting member  676 . The connecting member  676  is guided to advance straight by guide bar  675  that is fit with the connecting member  676 . Gear  673  is engaged with worm gear  672  that is driven by motor  671 , and link  674  converts the rotational motion of the gear  673  into the linear motion. Under the driving mechanism as stated above, the folding member  661  is driven by the motor  671  to conduct the reciprocating motion shown with arrows in dotted and solid lines in FIG. 3.  
         [0121]    In the moving direction of the folding tip portion  661 A, there are arranged folding roller R 1  and folding roller R 2  each being covered with a material such as rubber having high friction resistance so that they face each other. Both ends of the folding roller R 1  are supported by a pair of supporting plates  640  supported on supporting shaft  644  that is supported on the finishing apparatus FS. Both ends of the folding roller R 2  are supported by a pair of supporting plates  645  supported on supporting shaft  648  that is supported on the finishing apparatus FS. By virtue of springs  643  and  647  provided respectively on the supporting plate  640  and the supporting plate  645 , the folding roller R 1  and the folding roller R 2  are in pressure contact with each other.  
         [0122]    Further, for receiving sheets S folded by the folding roller R 1  and the folding roller R 2  and for folding the sheets S, there are arranged folding roller R 4 , folding roller R 5  and conveyance roller R 3  each being covered with a material such as rubber having high friction resistance. Among them, the folding roller R 4  is supported directly on the finishing apparatus FS. The folding roller R 4  is a driving roller which is driven by an unillustrated driving source to convey sheet S. The conveyance roller R 3  arranged to face the folding roller R 4  is supported, on its both ends, by a pair of supporting plates  649  supported by supporting shaft  652  that is supported on the finishing apparatus FS, and the conveyance roller R 3  is brought into pressure contact with the folding roller R 4  by sprint  651 . Thus, the sheet S is conveyed while it is regulated in the fixed direction, and it is folded firmly so that the stiffness of the sheet S is improved and conveyance thereof is secured.  
         [0123]    Further, stop guide plate  655 A that is positioned inside supporting plates  649  and  650  and guides fold section SA to stop it temporarily is provided in the finishing apparatus FS.  
         [0124]    In addition, the folding roller R 5  that comes in contact with the folding roller R 4  is supported, on its both ends, by a pair of supporting plates  653  supported by supporting shaft  655  that is supported on the finishing apparatus FS, and the folding roller R 5  is provided so that it is brought into contact with the folding roller R 4  by spring  656 , thus, the second folding means  68  is formed by the second sheet folding rollers R 4  and R 5 .  
         [0125]    Each of the numerals  658  and  659  is a detecting member which detects that sheet S has passed through the first guide plate  63  and the second guide plate  64 , and the numeral  657  is a sheet ejection guide plate which guides sheet S folded by folding rollers R 4  and R 5  and ejected to the outside of the apparatus.  
         [0126]    A folding process will be explained, referring to FIG. 4. Each of FIG. 4( a ) and FIG. 4( b ) shows a first folding process to fold with a first folding means  67 , and FIG. 4( c ) shows a second folding process to fold with a second folding means  68 .  
         [0127]    In the process of folding in three, sheet S is conveyed first between the first guide plate  63  and the conveyance belt  631 , and then, is conveyed into the second guide plate  64 . Then, the leading edge of the sheet S hits stopper  65  adjusted in terms of position with a size of the sheet S, and the sheet S stops. Next, motor  671  shown in FIG. 3 rotates to drive gear  673  to rotate, so that folding member  661  is moved in the direction of an arrow in solid lines in FIG. 3 and FIG. 4( a ), and a fold is made by the folding tip portion  661 A at the prescribed position of the sheet S.  
         [0128]    As shown in FIG. 4, sheet S is folded by the folding tip portion  661 A and fold section SA is formed while folding rollers R 1  and R 2  are rotating respectively in the directions of arrows of solid lines. As shown in FIG. 4( b ), therefore, the fold section SA is conveyed through the clearance between the folding roller R 1  and the folding roller R 2 , while the folding member  661  is moved by motor  761  in the direction of an arrow of a dotted line to return to the initial position.  
         [0129]    Next, as shown in FIG. 4( c ), the fold section SA is conveyed by conveyance roller R 4  and conveyance roller R 3  rotating respectively in the directions of arrows of solid lines until it is stopped by stop guide member  655 A. Under the state that the fold section SA is prevented from advancing by the stop guide member  655 A, when the folding roller R 4  further rotates in the direction shown with a solid line, an unfolded portion of the sheet S is conveyed by the folding roller R 4  to be interposed between folding rollers R 5  and R 4 , thus, the sheet S is folded to form fold section SB.  
         [0130]    Thus, the sheet S folded in three having the fold section SA formed by the folding rollers R 1  and R 2  and the fold section SB formed by the folding rollers R 4  and R 5  passes through sheet ejection guide plate  657  to be ejected onto fixed sheet ejection tray  93 .  
         [0131]    As explained above, the sheet S is folded in three at the folding means  60 , and is ejected onto the fixed sheet ejection tray  93 . It is ordinary that the folding in three is applied on a document for a sealed letter. In the embodiment explained above, it is possible to conduct folding processing with a small-sized finishing apparatus capable of being installed on image forming apparatus main body A. In the case of a postal sealed document, therefore, it is possible to prepare a document in a form suitable for a sealed letter, while recording information that is different for each document such as an address on the document.  
         [0132]    [0132]FIG. 5 shows relationship of a direction between sheet S and an image in image forming and folding processing. In FIG. 5, obverse S 1  and reverse S 2  both of sheet S are separated in the illustration, and a visible image is shown with solid lines, while an image which is invisible because it is on the reverse side is shown with dotted lines.  
         [0133]    From sheet ejection section  8  of the image forming apparatus main body A, there is conducted sheet ejection for sheet S shown with an arrow wherein image G 2  on the reverse is on the upper side and image G 1  on the obverse is on the lower side as shown in FIG. 5( a ), and the upper portion of the image represents a trailing edge of the sheet S in its conveyance direction.  
         [0134]    Sheet S having an obverse, a reverse and a direction of an image shown in FIG. 5( a ) is prepared in the image forming apparatus main body A under the following control for writing of the image.  
         [0135]    When a mode of folding in three is set on selection button Md (shown in FIG. 7) representing a selecting means provided on an operating section of an image forming apparatus, there are established image forming conditions exemplifying, for example, that a longer side of a sheet in a prescribed size such as an A 4  size needs to be in the conveyance direction. Then, in image forming on the obverse, writing is started from the upper portion of the image. In image forming on the reverse to be conducted following the image forming on the obverse, writing is started from the lower portion of the image, resulting in image forming wherein an upper portion of an image on the reverse is formed on the trailing edge of sheet S. In this way, the sheet S shown in FIG. 5( a ) is prepared.  
         [0136]    Incidentally, when forming an image on a single side in the mode of folding in three, writing is started from an upper portion of the image, and the upper portion of the image is formed on the leading edge of sheet S to be conveyed. Then, the sheet S is inverted in terms of obverse and reverse and is ejected at sheet ejection section  8 , to be fed into finishing apparatus FS.  
         [0137]    In the finishing apparatus FS, switchback conveyance is conducted as shown with an arrow on intermediate stacker  30 , resulting in inversion of a sheet in terms of a leading edge and a trailing edge, and in the conveyance wherein an upper portion of an image comes to a leading edge of the sheet to be conveyed, and then, the sheet is fed into folding means  60  (FIG. 5( b )).  
         [0138]    In the first folding process, there is conducted folding processing to form fold section SA at the position that is about ⅓ of the total length of the sheet S from its trailing edge so that obverse S 1  may be convex as shown in FIG. 5( c ). Finally, there is conducted folding processing to form fold section SB at the position that is about ⅓ of the total length of the sheet S from its leading edge so that obverse S 1  may be convex in the second folding process shown in FIG. 5( d ) . Thus, there is finished a folded document wherein the leading edge portion of image G 1  on obverse S 1  comes to the outermost portion of the folded sheet S, thereby, indexes and titles of a document can be looked at a glance.  
         [0139]    Next, operations of folding means  60  in the case of two-folding processing will be explained, referring to FIG.  6 . FIG. 6 is a diagram showing operations of main portions of folding means  60  in the case of folding in two.  
         [0140]    In the two-folding processing, stop guide plate  655 A is rotated counterclockwise (shown with arrows in FIG. 6( b )) around shaft  655 B representing a rotating center to be changed from the state shown in FIG. 4( c ) to the state shown in FIG. 6( b ) wherein a sheet accepting portion on the lower end of the stop guide plate  655 A is retreated from the sheet conveyance path.  
         [0141]    As shown in FIG. 3, sheet S conveyed to the folding means  60  is subjected to folding by folding tip portion  661 A so that fold section SC may be formed, and the fold section SC is fed into the space between folding rollers R 1  and E 2 .  
         [0142]    The folding rollers R 1  and R 2  convey the fold section SC, and the fold section SC thus conveyed is guided by guide plate  655 D as shown in FIG. 6( b ) to be ejected onto fixed sheet ejection tray  93 .  
         [0143]    Though the foregoing is explanation of folding processing for only one sheet S, it is also possible to collect a plurality of sheets S by stopper  52 , and to conduct folding in three or folding in two for the collected sheets S.  
         [0144]    [0144]FIG. 7 is a block diagram of a control system of an image forming apparatus wherein a mode of folding in two and a mode of folding in three can be used after selected. On the operation panel (not shown) of the image forming apparatus, there is provided mode selection button Md representing a selecting means to select the aforesaid mode for folding a sheet in two or the mode for folding a sheet in three. When the mode for folding in two is selected by the mode selection button Md, control means Mc controls so that the first folding means Fd 1  only is operated and a sheet is folded in two as stated above. When the mode for folding in three is selected by the mode selection button Md, the control means Mc controls so that the first folding means Fd 1  is operated and a sheet is folded as stated above, and then, the second folding means Fd 2  is operated and the sheet is folded.  
         [0145]    In the embodiment explained above, knife-shaped folding member  661  is used as the first folding means, and stop guide member  655 A is used as the second folding means. However, any one of these knife-shaped folding member  661  and stop guide member  655 A can be used optionally for either one of the first folding means and the second folding means.  
         [0146]    (3) Embodiment 2  
         [0147]    [0147]FIG. 8 is a diagram showing the structure of finishing apparatus FS which is related to Embodiment 2 of the invention and is connected with image forming apparatus main body A in FIG. 1.  
         [0148]    A position and a height are adjusted for installation so that accepting section  11  for sheet S ejected out of image forming apparatus main body A may agree, in terms of position, with sheet ejection section  8  of the image forming apparatus main body A.  
         [0149]    Paired rollers  12 A are provided at an entrance of the accepting section  11 , and a conveyance path for sheet S connected at the downstream side in the sheet conveyance direction is composed of first conveyance path ( 1 ) which is for sheet ejection mainly for the upper deck, second conveyance path ( 2 ) for the medium deck and third conveyance path ( 3 ) for the lower deck, so that sheet S is fed to either one of the conveyance paths through switching gate G 3 .  
         [0150]    (3)—1. Simple Sheet Ejection  
         [0151]    The image-formed sheet S ejected out of image forming apparatus main body A is guided into accepting section  11 , and passes through paired rollers  12 A and perforating means PA to be conveyed. Switching gate G 3  is positioned at the lower portion, and the sheet S is guided by the upper surface of the switching gate G 3  to be fed into the first path ( 1 ) and is ejected onto fixed sheet ejection tray  91  located on the upper portion of the apparatus to be stacked successively. When making holes on sheet S, perforating means PA is operated.  
         [0152]    The fixed sheet ejection tray  91  stated above is constructed so that a maximum of about 200 sheets S can be stacked.  
         [0153]    (3)—2. Shift Processing  
         [0154]    In this conveyance mode, switching gate G 3  goes up to guide sheet S so that the sheet S may pass through the space between two guide members constituting the switching gate G 3  as shown with solid lines in FIG. 8. The image-formed sheet S ejected out of the image forming apparatus main body A is conveyed by paired rollers  12 A, then passes through the switching gate G 3 , and is conveyed by paired rollers  24 . The sheet S thus conveyed is ejected by ejection roller  26  onto fluctuating sheet ejection tray  92  located outside the apparatus to be stacked in succession. Shift processing section  20  conducts shift processing to change the position of sheet ejection for sheet S in the conveyance transverse direction, at an interval of the prescribed number of sheets.  
         [0155]    This fluctuating sheet ejection tray  92  is constructed to descend gradually in the direction shown with a one-dot-chain line, when ejecting a large number of sheets S, and it can take in a maximum of about 3000 sheets S (A 4 , B 5 ).  
         [0156]    (3)—3. Binding Processing  
         [0157]    In the course of binding processing, switching gate G 3  is on the uppermost position, and sheet S is guided by the bottom surface of the switching gate G 3  to advance to the third conveyance path ( 3 ).  
         [0158]    In the third conveyance path ( 3 ), sheet S which has passed through path  31  is conveyed by paired rollers  34  to move to the upper portion of intermediate stacker  30  that is arranged to be inclined. After the trailing edge of the sheet S has passed the paired rollers  34 , the sheet S released from the paired conveyance rollers  34  falls along the surface of the intermediate stacker  30  until it hits movable stopper  51  provided on stapler  50  to stop.  
         [0159]    When appending a cover to sheet S, cover K is supplied to intermediate stacker  30  from cover feeding means  40 .  
         [0160]    When a bundle of sheets S in quantity of prescribed number or a bundle of sheets S and cover K are stacked on intermediate stacker  30 , stapling means  50  conducts binding processing to staple a staple. A bundle of bound sheets S is conveyed by a conveyance device of intermediate stacker  30  to be ejected onto fluctuating sheet ejection tray  92 .  
         [0161]    (3)—4. Folding Processing  
         [0162]    In the present embodiment, folding means  70  is arranged to parallel the third conveyance path ( 3 ) that is inclined to be the same as intermediate stacker  3  constituting a binding means.  
         [0163]    The folding means  70  that conducts folding in three or folding in two has first folding means  77  composed of folding roller R 1  representing a first folding roller that constitutes a first conveyance and folding means, folding roller R 2  representing a second folding roller that constitutes a first conveyance and folding means, and of knife-shaped folding member  761 , and second folding means  78  composed of folding roller R 2  representing a second folding roller that constitutes a second conveyance and folding means, folding roller R 6  representing a third folding roller that constitutes a second conveyance and folding means, and of stop guide member  755 A.  
         [0164]    First guide plate  73  and second guide plate  74  are provided respectively under movable stoppers  51  and  511  which make sheet S on intermediate stacker  30  to fall downward and the intermediate stacker  30 , and on the second guide plate  74 , there is provided stopper  75  that can adjust a position to the feeding direction for sheet S. Further, on the first guide plate  73  and second guide plate  74 , there is arranged knife-shaped folding member  761  having folding tip portion  761 A, and on the folding member  761 , there is provided a driving mechanism that is the same as that in FIG. 3 to move the folding member  761  in the directions of the solid line arrow and in the directions of the dotted line arrow.  
         [0165]    In the moving direction of the folding member  761 , there are arranged folding roller R 1  and folding roller R 2  each being covered with a material such as rubber having high friction resistance so that they face each other. Both ends of the folding roller R 1  are supported by a pair of supporting plates  740  supported on supporting shaft  744  that is supported on the finishing apparatus FS. Both ends of the folding roller R 2  are supported by a pair of supporting plates  745  supported on supporting shaft  748  that is supported on the finishing apparatus FS. By virtue of springs  743  and  747  provided respectively on the supporting plate  740  and the supporting plate  748 , the folding roller R 1  and the folding roller R 2  are in pressure contact with each others and first folding means  77  is composed of the folding member  761 , the first folding roller R 1  and of the second folding roller R 2 .  
         [0166]    In addition, second folding means  78  is formed by the folding roller R 2  and folding roller R 6  which is in pressure contact with the folding roller R 2 . The folding roller R 6  is supported by supporting plates  745  and  746 , and is constituted to be brought into pressure contact with the folding roller R 2  each other by a spring.  
         [0167]    Further, stop guide plate  755 A constituted solidly by two plates is provided on finishing apparatus FS so that the stop guide plate  755 A is positioned inside supporting plates  749  and  750  to stop the folded sheet S temporarily. Conveyance switching member  755 E is further provided under the stop guide plate  755 A to guide sheet S into the stop guide plate  755 A or to guide sheet A to be ejected directly. The numeral  757  represents a sheet ejection guide plate that guides the folded and ejected sheet S 1  to the outside of the apparatus.  
         [0168]    Each of FIGS.  9 ( a ) and  9 ( b ) shows operations of the first folding means  77  in the first folding process, and each of FIGS.  10 ( a ) and  10 ( b ) shows operations of the second folding means  78  in the second folding process.  
         [0169]    First, in FIG. 9, sheet S is fed to the first guide plate  73  and to the second guide plate  74 . Then, the sheet S stops with its leading edge hitting stopper  75  that is positionally adjusted to the size of the sheet S, as shown in FIG. 9( a ).  
         [0170]    Next, as shown in FIG. 9( b ), folding tip portion  761 A inserts fold section SA formed on the sheet S into the space between the folding roller R 1  and the folding roller R 2 . In this case, the folding rollers R 1  and R 2  are rotating in the directions respectively of their solid line arrows, and they nip the sheet S between them while forming the fold section SA. At this moment, the conveyance switching member  755 E is suspended at the position where the stop guide plate  755 A is opened.  
         [0171]    Next, as shown in FIG. 10( a ), the sheet S whose fold section SA is formed between the folding rollers R 1  and P 2  is conveyed in the direction of a solid line arrow, while, folding member  761  moves as shown with a dotted line to return to the starting position. Then, the sheet S is conveyed until the fold section SA is retarded in the guide plate  755 A.  
         [0172]    Next, as shown in FIG. 10( b ), the folding rollers R 1  and R 2  further rotate, and thereby, fold section SD of the sheet S is conveyed to second folding means  78  that is formed by the folding roller R 2  having the greater friction resistance and by folding roller R 6 , thus, fold section SA and fold section SB are formed, and sheet S folded in three whose leading edge and trailing edge are folded passes through the second folding means  78 . The sheet S folded in three by the folding rollers R 2  and R 6  is ejected to sheet ejection guide plate  757 .  
         [0173]    Next, operations of folding means  70  for folding sheet S in two will be explained as follows, referring to FIG. 11 which is a diagram showing main operations of the folding means  70  for folding in two.  
         [0174]    In the same way as in the occasion of folding in three, folding member  761  inserts sheet S into the space between the folding rollers R 1  and R 2  to form fold section SC. The folding rollers R 1  and R 2  rotate as shown by solid line arrows in FIG. 10 to convey fold section SC. In the folding processing to fold in two, conveyance switching member  755 E rotates counterclockwise as shown with an arrow to shut an entrance of stop guide plate  755 A. By virtue of this, the fold section SC does not enter the stop guide plate  755 A and is guided to be ejected to the outside.  
         [0175]    (4) Embodiment 3  
         [0176]    [0176]FIG. 12 is a diagram showing the structure of finishing apparatus FS related to the embodiment of the invention.  
         [0177]    This finishing apparatus FS is of the structure that is mostly the same as that of finishing apparatus FS shown in FIG. 8.  
         [0178]    In the present embodiment, folding means  80  is arranged over a binding means. The folding means  80  has first folding means  87  composed of folding roller R 1  representing a first folding roller that constitutes a first conveyance and folding means, folding roller R 2  representing a second folding roller that constitutes a first conveyance and folding means, and of knife-shaped folding member  861 , and second folding means  88  composed of folding roller R 2  representing a second folding roller that constitutes a second conveyance and folding means, folding roller R 6  representing a third folding roller that constitutes a second conveyance and folding means, and of stop guide member  855 A.  
         [0179]    The finishing apparatus FS in FIG. 12 is connected with image forming apparatus main body A so that it may agree with sheet ejection section  8  of the image forming apparatus main body A in FIG. 1.  
         [0180]    On an entrance of accepting section  11 , there are provided perforating means PA and conveyance roller  12 B, and a conveyance path for sheet S connected at the downstream side in the sheet conveyance direction is composed mainly of first conveyance path ( 1 ) that is mainly for sheets on the upper deck, second conveyance path ( 2 ) for the medium deck and third conveyance path ( 3 ) for the lower deck.  
         [0181]    (4)—1. Simple Sheet Ejection  
         [0182]    Image-formed sheet S ejected out of image forming apparatus main body A is guided into accepting section  11 , and it passes through conveyance roller  12 B and perforating means PA to be conveyed. The sheet S is guided by switching gate G 4  to enter the conveyance path ( 1 ), and is ejected onto fixed sheet ejection tray  91  positioned at the upper portion of the apparatus to be stacked in succession. When making holes on sheet S, perforating means PA is operated.  
         [0183]    The fixed sheet ejection tray  91  can take in a maximum of about 200 sheets S which can be taken out easily from the upper portion of finishing apparatus FS.  
         [0184]    (4)—2. Binding Processing  
         [0185]    Sheet S which has been subjected to image forming processing in image forming apparatus main body A and has been fed to accepting section  11  of finishing apparatus FS passes through conveyance roller  12 B, and then, is guided downward by gate G 4  that is switched to the upper position, to enter the second conveyance path ( 2 ).  
         [0186]    In the second conveyance path ( 2 ), the sheet S is conveyed by paired rollers  34  to be fed out upward, and thereby, the sheet S goes up along intermediate stacker  30  arranged obliquely. After the trailing edge of the sheet S in its advancement direction has passed the paired rollers  34 , the sheet S is released to fall along the intermediate stacker  30  until it hits movable stopper  51  provided on stapling means (binding means)  50  to be stopped.  
         [0187]    When appending cover K to sheets S in intermediate stacker  30 , the cover K is supplied to the intermediate stacker  30  from cover supplying means  40 .  
         [0188]    When prescribed number of sheets S or cover K and sheets S are stacked on intermediate stacker  30 , stapler  50  conducts stapling processing at the prescribed position on the sheets S. A bundle of bound sheets is ejected onto fixed sheet ejection tray  93  located at the lower portion through sheet ejection path  858 .  
         [0189]    (4)—3. Folding Processing  
         [0190]    Folding means  80  is arranged at the upper portion of a binding means, in the present embodiment.  
         [0191]    The folding means  80  conducting folding in three or folding in two has first folding means  87  composed of folding roller R 1  representing a first folding roller that constitutes a first conveyance and folding means, folding roller R 2  representing a second folding roller that constitutes a first conveyance and folding means, and of knife-shaped folding member  861 , and second folding means  88  composed of folding roller R 2  representing a second folding roller that constitutes a second conveyance and folding means, folding roller R 6  representing a third folding roller that constitutes a second conveyance and folding means, and of stop guide member  855 A.  
         [0192]    To guide sheet S in the upper position of intermediate stacker  30 , first guide plate  83  and second guide plate  84  are provided almost vertically on the upper portion of the intermediate stacker  30 . On the second guide plate  84 , there is provided stopper  85  which can adjust a position to the direction of feeding sheet S. In addition, folding member  861  having thereon folding tip portion  861 A is arranged between the first guide plate  83  and the second guide plate  84 , and a driving mechanism which is the same as that in FIG. 3 is provided on the folding member  861  to make it to conduct the reciprocation motion.  
         [0193]    In the moving direction of the aforesaid folding member  861 , there are arranged folding roller R 1  and folding roller R 2  each being covered with a material such as rubber having high friction resistance so that they face each other. Both ends of the folding roller R 1  are supported by a pair of supporting plates  840  supported on supporting shaft  844  that is supported on the finishing apparatus FS. Both ends of the folding roller R 2  are supported by a pair of supporting plates  845  supported on supporting shaft  848  that is supported on the finishing apparatus FS. By virtue of springs  843  and  847  provided respectively on the supporting plate  840  and the supporting plate  845 , the folding roller R 1  and the folding roller R 2  are provided to be in pressure contact with each other, and first folding means  87  is formed.  
         [0194]    In addition, folding roller R 6  that receives sheet S folded by folding rollers R 1  and R 2  and is covered by a material having high friction resistance such as rubber for folding sheet S is arranged to face and to be in contact with folding roller R 2 , and thus second folding means  88  is formed The folding roller R 6  is supported by supporting plates  845  and  846 , and is constituted to be brought into pressure contact with the folding roller R 2  by a spring.  
         [0195]    Further, stop guide plate  755 A constituted solidly by two plates is provided on finishing apparatus FS so that the stop guide plate  755 A is positioned inside supporting plates  749  and  750  to stop the folded sheet S temporarily. Conveyance switching member  755 E is further provided under the stop guide plate  755 A to guide sheet S into the stop guide plate  755 A or to guide sheet A to be ejected directly. The numeral  757  represents a sheet ejection guide plate that guides the folded and ejected sheet S 1  to the outside of the apparatus.  
         [0196]    In the same way as in the folding means  70  shown in FIG. 8, processing for folding in three is conducted in the first folding means  87  and the second folding means  88 , and processing for folding in two is conducted in the first folding means  87 .  
         [0197]    According to the present invention, the following effects can be attained.  
         [0198]    It becomes possible for an image forming apparatus equipped with a finishing apparatus having a folding function to be small in size and to have functions of folding in two and of folding in three, because a folding means can be made small.  
         [0199]    Further, it becomes possible to realize an image forming apparatus equipped with a small-sized finishing apparatus wherein a function of folding in two and a function of folding in three can be used selectively in case of need.  
         [0200]    Still further, it becomes possible to realize a small-sized image forming apparatus provided with a folding function having functions of binding, folding in two and folding in three.  
         [0201]    Still further, it becomes possible to realize a small-sized image forming apparatus which can fold a bundle of a plurality of sheets in two or in three.  
         [0202]    Still further, it becomes possible for a small-sized processing apparatus to conduct folding in two and folding in three.  
         [0203]    Still further, according to the present invention, it is possible that an image is formed on a sheet, and there is conducted efficiently the folding wherein a small-sized folding means in which a folding means is arranged in a conveyance path for an image-formed sheet is used, and a portion of a document which is looked exceedingly, namely, an upper portion of the image on the obverse appears on the outermost side of the folded document.  
         [0204]    Still further, it becomes possible to fold a document in two.  
         [0205]    Still further, it becomes possible to incorporate a small-sized means for folding processing in a finishing apparatus.  
         [0206]    Still further, according to the present invention, it is possible that two-sided image forming is conducted, and a document folded in three is made in the form wherein information to be looked exceedingly is recorded on the position that is easiest to see.  
         [0207]    Still further, it becomes possible to realize a small-sized image forming apparatus having functions to fold in three and to bind.  
         [0208]    Disclosed embodiment can be varied by a skilled person without departing from the spirit and scope of the invention.