Patent Publication Number: US-9891572-B2

Title: Paper humidifying apparatus and image forming system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present invention claims priority under 35 U.S.C. § 119 to Japanese Application No. 2015-108214, filed May 28, 2015, the entire content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a paper humidifying apparatus and an image forming system. 
     Description of Related Art 
     In the case where a process that involves heating of paper, such as a fixing process performed in an electrophotographic image forming apparatus, is included in image forming, sheets of paper tend to curve, such as becoming wavy, as a result of uneven moisture distribution in each of the sheets of paper due to moisture evaporating from the sheets of paper when heated. 
     In the aim of solving the above problem, there is known a paper processing apparatus which includes a humidifying unit for applying moisture to sheets of paper after image forming and which corrects curves in sheets of paper by passing them through a wavy concavo-convex unit after moisture has been applied to the sheets of paper by the humidifying unit (for example, see JP 2011-90243). 
       FIG. 10  is a view showing an example configuration of a humidifying unit in a paper processing apparatus. 
     The humidifying unit  500  includes a pair of humidifying rollers  501  and  501 , water supply rollers  502  and  502  which transmit water to the humidifying rollers  501  and  501  and reservoir units  503  and  503  in which water that is to be supplied to the water supply rollers  502  and  502  is pooled, for example. Moisture is to be applied to sheets of paper P by sandwiching and conveying the sheets of paper P with the humidifying rollers  501  and  501  whose outer circumferences hold moisture. 
     However, in the above described humidifying unit  500 , there is a possibility that paper conveyance be unstable when sandwiching and conveying a sheet of paper P with the pair of humidifying rollers  501  and  501  as a result of the sheet of paper P and the humidifying rollers  501  and  501  becoming highly adhesive to each other and the sheet of paper P winding around one of the humidifying rollers  501  and  501  as shown by the dashed line in  FIG. 10 . 
     SUMMARY OF THE INVENTION 
     The present invention was made in view of the above problem, and an object of the present invention is to provide a paper humidifying apparatus and an image forming system which can stably convey sheets of paper to which moisture is applied. 
     To solve the object described above, according to one aspect of the present invention, there is provided a paper humidifying apparatus, including: humidifying rollers, forming a pair, which are pressed against each other forming a nip portion and which apply moisture to a sheet of paper when sandwiching and conveying the sheet of paper; a first drive unit which makes the humidifying rollers separate from each other or press against each other; and a controller which controls the first drive unit, wherein the controller controls the first drive unit so as to make the humidifying rollers separate from each other and receive the sheet of paper, and after a tip of the sheet of paper passes a position corresponding to the nip portion, the controller controls the first drive unit so as to make the humidifying rollers press against each other to apply moisture to the sheet of paper. 
     Preferably, the paper humidifying apparatus further includes: water supply rollers which supply moisture to outer circumferences of the humidifying rollers; water removing units which wipe off moisture on the outer circumferences of the humidifying rollers; a second drive unit which makes the water supply rollers separate from or come in contact with the humidifying rollers; and a third drive unit which makes the water removing units separate from or come in contact with the humidifying rollers, wherein before the humidifying rollers receive the sheet of paper, the controller controls the second drive unit so as to make the water supply rollers separate from the humidifying rollers and controls the third drive unit so as to make the water removing units come in contact with the humidifying rollers to wipe off the moisture on the humidifying rollers. 
     Preferably, in the paper humidifying apparatus, the controller controls the second drive unit so as to make the water supply rollers separate from the humidifying rollers and thereafter, the controller controls the first drive unit so as to make the humidifying rollers separate from each other. 
     Preferably, in the paper humidifying apparatus, after the tip of the sheet of paper passes a predetermined distance from the position corresponding to the nip portion, the controller controls the first drive unit so as to make the humidifying rollers press against each other. 
     Preferably, in the paper humidifying apparatus, the controller sets the predetermined distance on a basis of a paper condition. 
     Preferably, in the paper humidifying apparatus, the controller sets the predetermined distance so as to be longer as a basis weight, which is the paper condition, be smaller. 
     Preferably, in the paper humidifying apparatus, the water removing units do not come in contact with the humidifying rollers when the humidifying rollers are separated from each other. 
     Preferably, the paper humidifying apparatus further includes an operation unit for a user to set operation timing of the humidifying rollers. 
     According to another aspect of the present invention, there is provided an image forming system, including: an image forming unit for forming an image on a sheet of paper; and the paper humidifying apparatus for humidifying the sheet of paper on which the image is formed by the image forming unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention, and wherein: 
         FIG. 1  is a schematic view showing the overall structure of an image forming system; 
         FIG. 2  is a block diagram showing the main configuration relating to operational control of the image forming system; 
         FIG. 3  is a view showing the main configuration in a first paper processing apparatus; 
         FIG. 4  is a significant part enlarged view showing the configuration of a humidifying unit; 
         FIG. 5  is an example of a setting table which sets a paper condition that is referred to in a humidifying process; 
         FIG. 6  is a flowchart showing operation of the humidifying unit in the humidifying process; 
         FIG. 7  is a schematic view used for explaining operation of the humidifying unit in the humidifying process; 
         FIG. 8  is a schematic view used for explaining operation of the humidifying unit in the humidifying process; 
         FIG. 9  is a schematic view used for explaining operation of the humidifying unit in the humidifying process; and 
         FIG. 10  is a view used for explaining a problem in a conventional technique. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the examples shown in the drawings in any way. 
     [Image Forming System] 
       FIG. 1  is a schematic view showing the overall structure of the image forming system  1  according to the embodiment and  FIG. 2  is a block diagram showing the main configuration relating to operational control of the image forming system  1 . 
     As shown in  FIGS. 1 and 2 , the image forming system  1  includes an image forming apparatus  100 , a first paper processing apparatus  200  and a second paper processing apparatus  300 . 
     The image forming apparatus  100  is an apparatus which forms images on sheets of paper P. 
     The first paper processing apparatus  200  is a paper humidifying apparatus which performs a humidifying process to apply moisture to sheets of paper P on which images are formed by the image forming apparatus  100 . 
     The second paper processing apparatus  300  is an apparatus which performs a hole punching process, a binding process and a folding process on sheets of paper P on which images are formed by the image forming apparatus  100 . 
     In the following description, the direction in which the image forming apparatus  100 , the first paper processing apparatus  200  and the second paper processing apparatus  300  are connected is referred to as the X direction, the vertical direction is referred to as the Z direction and the direction orthogonal to the X direction and the Z direction is referred to as the Y direction. 
     [Image Forming Apparatus] 
     First, the image forming apparatus  100  will be described. 
     As shown in  FIGS. 1 and 2 , the image forming apparatus  100  includes a reader  110 , paper feeding trays  120 , a paper conveyance unit  130 , an image forming unit  140 , a fixing unit  150 , a first controller  160 , a first storage  170 , an operation display (operating unit)  180 , a communicator  190  and the like, for example. 
     The reader  110  optically reads a document and generates image data. 
     In particular, the reader  110  includes a sensor  111 , a generator, a platen  113 , an auto document feeder (ADF)  114  and the like. The sensor  111  includes an image pickup device such as a CCD (Charge-Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor to read images and output electric signals according to the read images. The generator, which is not shown in the drawings, generates image data on the basis of the electric signals output from the sensor  111 . The platen  113  includes a light transmissive plate-like member which is disposed on the side of the sensor  111  where documents are to be read, and a document can be placed on the plate-like member. The auto document feeder  114  conveys documents so as to move the documents in relation to the sensor  111 . The sensor  111  reads a document which is placed on the platen  113 . The sensor  111  also reads the documents which are conveyed by the auto document feeder  114 . 
     The paper feeding trays  120  are box-shaped members in which sheets of paper P can be contained, the trays being arranged so that their storage condition or their open condition with respect to the case of the image forming apparatus  100  can be switched. In the paper feeding trays  120 , sheets of paper P before images are formed thereon by the image forming apparatus  100  are contained. As shown in  FIG. 1 , a plurality of paper feeding trays  120  are disposed and each of the trays contains sheets of paper P of a different size. Here, the plurality of paper feeding trays  120  can also contain sheets of paper P of the same size. 
     The paper conveyance unit  130  conveys sheets of paper P between the paper feeding trays  120 , the image forming unit  140 , the fixing unit  150  and the like. 
     In particular, the paper conveyance unit  130  includes a plurality of rollers and drive units (not shown) which drive individual rollers, for example. The rollers are disposed intermittently between the paper feeding trays  120 , the image forming unit  140 , the fixing unit  150  and the like and theiraround along a predetermined paper conveyance path. The paper conveyance unit  130  pulls out the sheets of paper P which are contained in the paper feeding trays  120  one by one and conveys the sheets of paper P to the image forming unit  140 . Thereafter, the paper conveyance unit  130  conveys the sheets of paper P on which images are formed by the image forming unit  140  to the fixing unit  150  and then, outputs the sheets of paper P on which the images are fixed by the fixing unit  150  from the outlet which is formed on the side of the image forming apparatus  100  facing the first paper processing apparatus  200 . In the case where image forming is to be performed on both sides of a sheet of paper P, the paper conveyance unit  130  operates so as to reverse a sheet of paper P at the branching point  131  on the conveyance path between the fixing unit  150  and the outlet and to make the sheet of paper P return toward the image forming unit  140 . 
     The image forming unit  140  forms images on sheets of paper P. 
     In particular, the image forming unit  140  includes a photoreceptor  141 , a charger  142 , an exposure unit  143 , a developing unit  144 , a transfer unit  145  and a cleaner  146 , for example. The photoreceptor  141  is disposed so that the outer circumference thereof comes in contact with a sheet of paper P which is conveyed by the paper conveyance unit  130 . The charger  142  performs a charging process on the photoreceptor  141 . The exposure unit  143  performs an exposure process according to image data on the charged photoreceptor  141 . The developing unit  144  forms a toner image according to image data and transfers (primary transfer) the toner image on to the photoreceptor  141 . The transfer unit  145  transfers (secondary transfer) the toner image which is transferred on to the photoreceptor  141  on to a sheet of paper P. The cleaner  146  removes the residual toner remaining on the photoreceptor  141 . The image forming unit  140  of the embodiment performs electrophotographic image forming with the above described configuration. However, this is just an example and is not limitative in any way. For example, the image forming unit  140  can include an inkjet or the like for performing image forming of other methods. 
     The image forming unit  140  shown in  FIG. 1  includes one developing unit  144  and performs monochromatic image forming (single color). However, this is just an example and is not limitative in any way. For example, the image forming unit  140  can include developing units  144  corresponding to cyan (C), magenta (M), yellow (Y) and black (K) and can perform color printing using combinations of these colors. 
     The fixing unit  150  fixes the image formed on a sheet of paper P by the image forming unit  140 . 
     In particular, the fixing unit  150  includes a pair of fixing rollers  151  and  151  and a heater  152 , for example. The fixing rollers  151  and  151 , which form a pair, are arranged so that the outer circumferences thereof come in contact with each other while the conveyance path of sheets of paper P passes between the rollers  151  and  151 . The heater  152  heats one roller of the pair of fixing rollers  151  and  151  that comes in contact with the side of a sheet of paper P on which an image is formed by the image forming unit  140  (the roller on the upper side in  FIG. 1 , for example). The fixing unit  150  fixes the toner image which is transferred on to a sheet of paper P by sandwiching the sheet of paper P with the pair of fixing rollers  151  and  151  which is driven to rotate and by conveying the sheet of paper P while heating the side of the sheet of paper P on which an image is formed with the roller that is heated by the heater  152 . 
     The first controller  160  integrally controls the apparatuses and units of the image forming system  1  according to instructions that are input through the operation display  180  or the communicator  190 . The first controller  160  includes a CPU (Central Processing Unit), a RAM (Random Access Memory) and the like. The CPU reads a program stored in the first storage  170  and opens the program in a work area in the RAM. In such way, the CPU carries out various processes in cooperation with programs. 
     For example, the first controller  160  makes the image forming apparatus  100  perform image forming and the like on sheets of paper P on the basis of image data obtained via the reader  110 . 
     Programs to be executed by the first controller  160  and data necessary to execute the programs are stored in the first storage  170 . 
     The operation display  180  includes a touch panel which displays various information relating to operation of the image forming system  1  and which detects various input operation performed by a user according to the displayed content, a plurality of switches for a user to perform various input operation, and the like. 
     For example, the operation display  180  is used for inputting a paper condition and the like relating to operation of the humidifying unit  230  of the first paper processing apparatus  200 . 
     With respect to the processes performed in the image forming apparatus  100 , the first paper processing apparatus  200  and the second paper processing apparatus  300 , various settings that are input by a user through the operation display  180  are to be stored in the storages (the first storage  170 , the second storage  280  and the third storage  360 ) of the individual apparatuses. 
     The communicator  190  includes a Network Interface Card (NIC) or a configuration equivalent to this, for example, and is used for carrying out communication between the image forming system  1  and other computers. When a printing job including image data is input via the communicator  190 , the first controller  160  performs image forming and the like on the basis of the printing job. 
     A sheet of paper P which is output from the image forming apparatus  100  is to be conveyed to the first paper processing apparatus  200 . 
     [First Paper Processing Apparatus] 
     Next, the first paper processing apparatus  200  will be described. 
       FIG. 3  is a view showing the main configuration of the first paper processing apparatus  200 . 
     As shown in  FIGS. 2 and 3 , the first paper processing apparatus  200  includes an introducing unit  210 , a first conveyance unit  220 , a humidifying unit  230 , a second conveyance unit  240 , a decurling unit  250 , an outlet  260 , a second controller  270  and a second storage  280 , for example. 
     In the following description, the X direction will be referred to in terms of left and right and the Z direction will be referred to in terms of up and down. The right side is the side on which the image forming apparatus  100  is arranged with respect to the first paper processing apparatus  200 . The left side is the side on which the second paper processing apparatus  300  is arranged with respect to the first paper processing apparatus  200 . The upper side is the side in the direction toward the outlet  260  in the first paper processing apparatus  200 . The lower side is the side in the direction toward the humidifying unit  230  in the first paper processing apparatus  200 . 
     The introducing unit  210  receives sheets of paper P which are output from the image forming apparatus  100  in to the first paper processing apparatus  200 . 
     The first conveyance unit  220  conveys the sheets of paper P which are received in to the first paper processing apparatus  200  by the introducing unit  210  to the humidifying unit  230  which is disposed below the introducing unit  210 . In the middle of the first conveyance unit  220 , the branching point Q 1  which is a branching point on the conveyance path for guiding sheets of paper P to the second conveyance unit  240  is arranged. 
       FIG. 4  is a significant part enlarged view showing the configuration of the humidifying unit  230 . 
     The humidifying unit  230  is for applying moisture to sheets of paper P which are conveyed by the first conveyance unit  220 . The humidifying unit  230 , for example, includes a pair of humidifying rollers  231  and  231  which forms a nip portion by being pressed against each other, water supply rollers  232  and  232  which transmit water to the humidifying rollers  231  and  231 , water removing rollers  233  and  233  which remove excess water on the water supply rollers  232  and  232 , reservoir units  234  and  234  in which water that is to be transmitted to the water supply rollers  232  and  232  is pooled, a tank  235  in which water is stored, a sensor  236  which is disposed on the upper stream side of the humidifying rollers  231  and  231 , blades  237  and  237  which remove excess water on the humidifying rollers  231  and  231  and the like. 
     The humidifying rollers  231  and  231  that form a pair are two long rollers which extend in the width direction (Y direction) of a sheet of paper P. In a state where the humidifying rollers  231  and  231  are made to press against each other, they are driven by the driving motor so as to rotate, and they sandwich and convey a sheet of paper. Here, it is controlled so that the rotation speed of the pair of humidifying rollers  231  and  231  (conveyance speed of a sheet of paper) be constant. 
     The pair of humidifying rollers  231  and  231  are made so that moisture can be held at the outer circumferences thereof. In particular, the humidifying rollers  231  and  231  are made of hydrophilic rubber or the like that can hold moisture. For example, acrylonitrile butadiene rubber (NBR) can be preferably used. 
     When the humidifying rollers  231  and  231 , which form a pair, rotate while a sheet of paper P being sandwiched therebetween in a state where the humidifying rollers  231  and  231  are holding moisture, the sheet of paper P can be humidified as being conveyed to the downstream side. If the humidifying rollers  231  and  231 , which form a pair, rotate while a sheet of paper P being sandwiched therebetween in a state where the humidifying rollers  231  and  231  do not hold moisture, they function as regular conveying rollers which convey the sheet of paper P to the downstream side. 
     In the embodiment, the humidifying rollers  231  and  231 , which form a pair, move in the X direction so that they press against each other or separate from each other by being driven by the humidifying roller drive unit (first drive unit)  231   a  (see  FIG. 2 ). 
     The humidifying roller drive unit  231   a  includes a stepping motor and a gear, for example, and the humidifying rollers  231  and  231  are driven to move by the gear engaging with the rotation of the stepping motor, for example. Other than such method, a technique where the humidifying rollers  231  and  231  are driven to move along a rail by the rotation or winding of a belt, a technique where the humidifying rollers  231  and  231  are driven to move by the alteration in oil pressure or the like can be preferably selected. 
     The humidifying rollers  231  and  231  are provided with water supply rollers  232  and  232 , respectively. Each water supply roller  232  rotates in a state where it is in contact with the outer circumference of its corresponding humidifying roller  231  and in the state where it touches the water pooled in its corresponding reservoir unit  234  to hold moisture at the outer circumference thereof and to transmit moisture to its corresponding humidifying roller  231 . 
     The water supply rollers  232  and  232  are driven by the water supply roller drive unit (the second drive unit)  232   a  (see  FIG. 2 ) to move in the X direction so as to come in contact with or separate from their corresponding humidifying rollers  231  and  231 . 
     The water supply roller drive unit  232   a  includes a stepping motor and a gear, for example, and the water supply rollers  232  and  232  are driven to move by the gear engaging with the rotation of the stepping motor, for example. Other than such method, a technique where the water supply rollers  232  and  232  are driven to move along a rail by the rotation or winding of a belt, a technique where the water supply rollers  232  and  232  are driven to move by the alteration in oil pressure or the like can be preferably selected. 
     Each of the water removing rollers  233  and  233  is disposed at a position where it can come in contact with the outer circumference of its corresponding water supply roller  232 . Each of the water removing rollers  233  and  233  wipes the outer circumference of its corresponding water supply roller  232  when the water supply roller  232  rotates, and thereby the water removing roller  233  can wipe off excess water held at the outer circumference of its corresponding water supplying water  232 . In such way, the amount of moisture held at the outer circumferences of the water supply rollers  232  and  232  can be adjusted and preferred amount of moisture can be supplied to the humidifying rollers  231  and  231  by the water supply rollers  232  and  232 . 
     The reservoir units  234  and  234  have arc shaped bottoms so as to be in conformity with the outer circumference shape of the water supply rollers  232  and  232 , and water is pooled in the arc shaped bottoms. Each water supply roller  232  is arranged so that its outer circumference be lower than the surface of the water pooled in its corresponding reservoir unit  234  but does not come in contact with the arced bottom surface of the reservoir unit  234 . In such way, the outer circumference of each water supply roller  232  soaks the water pooled in its corresponding reservoir unit  234  as the water supply roller  232  rotates. The reservoir units  234  are connected to the tank  235  below by the conveyance path  234   a.    
     The tank  235  is a container in which water is stored. Water in the tank  235  is sent out to the reservoir units  234  and  234  through the outlet path  234   a  by the operation of a pump (not shown in the drawings). In such way, the amount of water to be pooled in each of the reservoir units  234  and  234  can be maintained at a preferred amount. 
     Each of the blades  237  and  237  are disposed below its corresponding humidifying roller  231  (on the upper stream side in the sheet conveyance direction) so as to face the nip portion formed by the humidifying rollers  231  and  231 . The blades  237  and  237 , which form a pair, are plate-like members, their lengths in the Y direction being approximately the same or longer than the length of the humidifying rollers  231  and  231 . 
     The blades  237  and  237  are arranged diagonally in a state where the upper ends thereof are close to each other so that the space between the upper ends is smaller than the space between the lower ends. 
     The blades  237  and  237  can rotate in the directions shown by the double pointed arrows A in  FIG. 4  with the lower ends thereof being the rotary shafts by being driven by the blade drive unit (the third drive unit)  237   a.    
     Therefore, in the state where the blades  237  and  237  are horizontal, they are apart from the humidifying rollers  231  and  231 , and as they become vertical, their upper ends come in contact with the humidifying rollers  231  and  231 . 
     When each of the blades  237  and  237  is at an angle being in contact with its corresponding humidifying roller  231 , that is, when the blades  237  and  237  be in the state where the upper ends thereof come in contact with the outer circumferences of the humidifying rollers  231  and  231 , the blades  237  and  237  function as the water removing units which wipe off the moisture on the outer circumferences of the humidifying rollers  231  and  231 . 
     A blade drive unit  237   a  includes a stepping motor, for example, and the rotary shafts which are the lower ends of the blades  237  and  237  are made to rotate by the rotation of the stepping motor, for example. Here, the blade drive unit  237   a  is not limited to have the above configuration as long as the blades  237  and  237  are made to rotate. 
     The sensor  236  is disposed at a predetermined position on the upper stream side in the conveyance direction of sheets of paper P further upper than the nip portion formed by the humidifying rollers  231  and  231 . The sensor  236  determines whether a sheet of paper P is conveyed to the predetermined position and outputs a detection signal to the second controller  270 . 
     In the embodiment, the humidifying process is performed on the basis of a paper condition in the above described humidifying unit  230  under the control of the second controller  270 . Details of the humidifying process will be described later. 
     Returning to  FIG. 3 , the second conveyance unit  240  conveys a sheet of paper P which is introduced in to the first paper processing apparatus  200  through the introducing unit  210  to the lower stream side of the humidifying unit  230  without conveying the sheet of paper P through the humidifying unit  230 . That is, the second conveyance unit  240  conveys a sheet of paper P, which was branched toward the second conveyance unit  240  without branching toward the humidifying unit  230  at the branching point Q 1  in the first conveyance unit  220 , to the meeting point Q 2  arranged on the down stream side of the humidifying unit  230 . 
     The decurling unit  250  is a mechanism for correcting curling of a sheet of paper P while conveying the sheet of paper P. The decurling unit  250  includes a first decurling unit  10 , a second decurling unit  20  and a third decurling unit  30 . 
     The first decurling unit  10  and the second decurling unit  20  are for correcting large curling of a sheet of paper P. The first decurling unit  10  conveys a sheet of paper P which is conveyed from below to the right direction, and the second decurling unit  20  conveys the sheet of paper P, which is conveyed from the right side, upward. 
     The third decurling unit  30  is for correcting small curling of a sheet of paper P. In the third decurling unit  30 , sandwiching force is applied to a sheet of paper P from both the left and right sides while conveying the sheet of paper P upward from below. 
     An outlet  260  includes a curved conveyance unit which receives a sheet of paper P which is conveyed from the third decurling unit  30  of the decurling unit  250 , conveys the sheet of paper P downward from above and conveys the sheet of paper P to the left direction. The outlet  260  conveys a sheet of paper P to the second paper processing apparatus  300  via the curved conveyance unit. 
     As described above, in the first paper processing apparatus  200 , curved conveyance paths are formed inside the apparatus between the introducing unit  210  and the outlet  260 . The curving directions of the curved conveyance paths are not in one direction in order to prevent a sheet of paper P from curling in one direction. 
     The second controller  270  integrally controls the units in the first paper processing apparatus  200 . The second controller  270  includes a CPU, a RAM and the like. The CPU reads a program stored in the second storage  280 , opens the program in a work area in the RAM. In such way, the CPU executes various processes in cooperation with programs. 
     For example, the second controller  270  carries out the humidifying process on a sheet of paper P on the basis of a pre-set paper condition. 
     In the second storage  280 , programs which are to be carried out by the second controller  270  and data necessary for carrying out the programs are stored. 
     For example, a paper condition for controlling the operation of the humidifying unit  230  of the first paper processing apparatus  200  is stored in the second storage  280 . If a user operates the operation display  180  and sets a paper condition for controlling the operation of the humidifying unit  230 , the set paper condition is to be stored in the second storage  280 . 
       FIG. 5  is an example of a setting table T 1  which sets a paper condition. 
     In  FIG. 5 , basis weight of sheets of paper P and lengths of parts where moisture is not to be applied at the tip ends of sheets of paper P corresponding to the basis weight are set as the paper condition. 
     In particular, if the basis weight of a sheet of paper P is 50 to 60 g/m2, the length of the part at the tip end of the sheet of paper P where moisture is not to be applied is 10 mm. If the basis weight of a sheet of paper P is 61 to 70 g/m2, the length of the part at the tip end of the sheet of paper P where moisture is not to be applied is 5 mm. If the basis weight of a sheet of paper P is 71 g/m2 or greater, the length of the part at the tip end of the sheet of paper P where moisture is not to be applied is 0 mm (humidifying of the sheet of paper P starts from the very tip). 
     The setting shown in  FIG. 5  is just an example and the setting can be changed as needed. A user can change the numbers set in the setting table T 1  by operating the operation display  180 . If the numbers set in the setting table T 1  are changed, the operation timing of the pair of humidifying rollers  231  and  231  are changed in accordance with the setting change, and further, the operation timing of the water supplying rollers  232  and  232  and the blades  237  and  237  is also changed accordingly. 
     It is needless to say that the configuration may be such that allows a user to operate the operation display  180  to preferably change the operation timing of the water supplying rollers  232  and  232  and the blades  237  and  237 . 
     Further, any one of type, thickness and the like of sheets of paper P or any combination thereof can be used as the paper condition other than basis weight. 
     Here, the humidifying process performed in the humidifying unit  230  of the first paper processing apparatus  200  will be described. 
       FIG. 6  is a flowchart showing operation of the humidifying process that is performed in the humidifying unit  230 . 
       FIGS. 7 to 9  are schematic views showing different states of the humidifying unit  230  during the humidifying process. 
     As premises for the process, the humidifying rollers  231  and  231 , which form a pair, are made to press against each other, and one humidifying roller  231  and its corresponding water supply roller  232  are made to press against each other and the other humidifying roller  231  and its corresponding water supply roller  232  are made to press against each other. A sheet of paper P is expected to be conveyed upward from below at a predetermined constant conveyance speed. 
     First, the second controller  270  obtains a paper condition (the basis weight of a sheet of paper P) included in job information (step S 11 ). 
     Next, the second controller  270  makes the water supply roller driving unit  232   a  drive the water supply rollers  232  and  232  so as to separate from the humidifying rollers  231  and  231  and makes the blade drive unit  237   a  drive the blades  237  and  237  so as to rotate in the direction approximating the vertical state in order to make the blades  237  and  237  come in contact with their corresponding humidifying rollers  231  and  231  (see  FIG. 7 , step S 12 ). 
     In such way, moisture supply to the humidifying rollers  231  and  231  from the water supply rollers  232  and  232  is cut off and the upper ends of the blades  237  and  237  are to be in contact with the outer circumferences of the humidifying rollers  231  and  231 . Thus, moisture on the outer circumferences of the humidifying rollers  231  and  231  is wiped off and removed. 
     Next, after a predetermined time elapses, the second controller  270  makes the humidifying roller drive unit  231   a  drive the humidifying rollers  231  and  231  so as to release their pressing against each other (the humidifying rollers  231  and  231  are made to separate from each other) (see  FIG. 8 , step S 13 ). 
     Since the blades  237  and  237  are arranged diagonally, the humidifying rollers  231  and  231  and their corresponding blades  237  and  237  are to be in a state where they are not in contact with each other as a result of releasing of the pressing against each other of the humidifying rollers  231  and  231 . In such way, the humidifying rollers  231  and  231  can be prevented from wearing out due to being in contact with the blades  237  and  237 . 
     According to the embodiment, it is controlled so as to first separate the water supply rollers  232  and  232  from their corresponding humidifying rollers  231  and  231  in step S 12  and then, release the pressing against each other of the humidifying rollers  231  and  231  in step S 13 . In such way, water can be prevented from dripping when separating the humidifying rollers  231  and  231  from each other since operation timing is different for individual rollers. 
     Next, the second controller  270  refers to the setting table T 1  stored in the second storage  280  and sets the length of the part at the tip end of a sheet of paper P where water is not to be applied on the basis of the paper condition (the basis weight of a sheet of paper P) obtained in step S 11  (step S 14 ). 
     Here, the second controller  270  calculates the time needed until the humidifying rollers  231  and  231  are to be made to press against each other again after the tip end of a sheet of paper P passes the sensor  236  on the basis of the length which is set by referring to the setting table T 1  and the predetermined sheet conveyance speed. 
     Next, the second controller  270  determines whether the time has reached the timing to make the humidifying rollers  231  and  231  press against each other since the tip end of a sheet of paper P passed the sensor  236 , that is, whether the tip end of a sheet of paper P has passed a predetermined distance from the position corresponding to the nip portion formed by the humidifying rollers  231  and  231  (step S 15 ). If the time has not yet reached the timing to make the humidifying rollers  231  and  231  press against each other (step S 15 : No), the process of step S 15  is to be repeated. 
     If it is determined that the time has reached the timing to make the humidifying rollers  231  and  231  press against each other (step S 15 : Yes), the second controller  270  makes the humidifying roller drive unit  231   a  drive the humidifying rollers  231  and  231  so as to press against each other, makes the water supply roller drive unit  232   a  drive the water supply rollers  232  and  232  so as to be in contact with the humidifying rollers  231  and  231 , makes the blade drive unit  237   a  drive the blades  237  and  237  so as to rotate in the direction approximating the horizontal state to separate the blades  237  and  237  from the humidifying rollers  231  and  231  (see  FIG. 9 , step S 16 ) and ends the process. 
     In such way, moisture is supplied to the humidifying rollers  231  and  231  by the water supply rollers  232  and  232  and this initiates supplying of moisture to a sheet of paper P by the humidifying rollers  231  and  231 . 
     At this time, since the blades  237  and  237  are made to rotate in the direction approximating the horizontal state, the blades  237  and  237  do not come in contact with their corresponding humidifying rollers  231  and  231 , and moisture supply to a sheet of paper P by the humidifying rollers  231  and  231  will no be blocked. 
     By the above described humidifying process, a sheet of paper P is to be in a state where moisture is applied thereto except for the tip end part thereof and is to be conveyed to the down stream side of the humidifying unit  230 . 
     [Second Paper Processing Apparatus] 
     Returning to  FIG. 1 , the second paper processing apparatus  300  includes a first conveyance path  310 , a second conveyance path  320 , a switching member  330 , paper output trays  340 A and  340 B, a third controller  350  and a third storage  360 , for example. 
     The first conveyance path  310  is also called the straight path and includes a plurality of rollers and drive units (not shown) which drive individual rollers, for example. The first conveyance path  310  conveys sheets of paper P. 
     A hole punch unit  311  which punches holes in sheets of paper P is arranged on the first conveyance path  310 , for example. 
     The second conveyance path  320  is also called the stack path and, similarly to the first conveyance path  310 , includes a plurality of rollers and drive units (not shown) which drive individual rollers, for example. The second conveyance path  320  conveys sheets of paper P. 
     On the second conveyance path  320 , a stacker  321  where sheets of paper P are to be temporarily stacked, an aligning member  322  which aligns the width of the sheets of paper P stacked on the stacker  321 , a binding unit  323  which binds the sheets of paper P stacked on the stacker  321  with needles and a folding unit  324  which folds the sheets of paper P stacked on the stacker  321  are arranged, for example. 
     The switching member  330  guides the conveying direction of sheets of paper P, switching the conveying path of sheets of paper P between the first conveyance path  310  and the second conveyance path  320 . 
     The sheets of paper P which are output from the first conveyance path  310  are to be stacked on the paper output tray  340 A. The sheets of paper P which are output from the second conveyance path  320  are to be stacked on the paper output tray  340 B. 
     The third controller  350  integrally controls the units in the second paper processing apparatus  300 . The third controller  350  includes a CPU, a RAM and the like. The CPU reads a program which is stored in the third storage  360 , opens the program in a work area in the RAM. In such way, the third controller  350  executes various processes in cooperation with programs. 
     For example, the third controller  350  controls so as to carry out paper processes of the second paper processing apparatus  300  on sheets of paper P according to preset setting conditions. 
     In the third storage  360 , programs to be executed by the third controller  350  and data necessary to execute the programs are stored. 
     For example, setting conditions and the like relating to paper processes to be carried out in the second paper processing apparatus  300  are stored in the third storage  360 . 
     Configuration of the second paper processing apparatus  300  is not limited to the above described configuration. Other than the above described configuration, the second paper processing apparatus  300  may include a structure for performing paper processing such as cutting, for example. 
     As described above, according to the embodiment, the present invention includes the humidifying rollers  231  and  231 , forming a pair, which form a nip portion by being pressed against each other and apply moisture to a sheet of paper P when sandwiching and conveying the sheet of paper P, a humidifying roller drive unit  231   a  which drives the humidifying rollers  231  and  231  to make them separate from each other or press against each other, and the second controller  270  which controls the humidifying roller drive unit  231   a . The second controller  270  controls the humidifying roller drive unit  231   a  so as to make the humidifying rollers  231  and  231  separate from each other and, in such state, to receive a sheet of paper P. After the tip of the sheet of paper P passes the position corresponding to the nip portion, the second controller  270  controls the humidifying roller drive unit  231   a  so as to make the humidifying rollers  231  and  231  press against each other to applying moisture to the sheet of paper P. 
     In such way, a sheet of paper P can be prevented from winding around one of the humidifying rollers  231  and  231  since moisture is not applied to the tip end of the sheet of paper P. Further, the tip of a sheet of paper P can be prevented from being damaged, such as the tip being turned or folded. 
     Thus, a sheet of paper P to which moisture is applied can be conveyed stably. 
     Moreover, according to the embodiment, the present invention includes the water supply rollers  232  and  232  which supply moisture to the outer circumferences of the humidifying rollers  231  and  231 , the blades  237  and  237  which wipe off the moisture on the outer circumferences of the humidifying rollers  231  and  231 , the water supply roller drive unit  232   a  which drives the water supply rollers  232  and  232  so as to separate from or come in contact with their corresponding humidifying rollers  231  and  231 , and the blade drive unit  237   a  which drives the blades  237  and  237  so as to separate from or come in contact with the humidifying rollers  231  and  231 . Before the humidifying rollers  231  and  231  receive a sheet of paper P, the second controller  270  controls the water supply roller drive unit  232   a  so as to make the water supply rollers  232  and  232  separate from their corresponding humidifying rollers  231  and  231  and controls the blade drive unit  237   a  so as to make the blades  237  and  237  come in contact with their corresponding humidifying rollers  231  and  231  to wipe off the moisture on the humidifying rollers  231  and  231 . 
     In such way, moisture supply to the humidifying rollers  231  and  231  from the water supply rollers  231  and  231  is cut off and the blades  237  and  237  are in a state where the upper edges thereof are in contact with the outer circumferences of their corresponding humidifying rollers  231  and  231 . Thus, the moisture held on the outer circumferences of the humidifying rollers  231  and  231  is wiped off and removed. 
     Therefore, conveyance malfunction due to the tip of a sheet of paper P coming in contact with the humidifying rollers  231  and  231  which are in a state where they are separated from each other but holding moisture can be prevented. 
     Moreover, according to the embodiment, the second controller  270  controls the water supply roller drive unit  232   a  so as to make the water supply rollers  232  and  232  separate from their corresponding humidifying rollers  231  and  231 . Thereafter, the second controller  270  controls the humidifying roller drive unit  231   a  so as to make the humidifying rollers  231  and  231  separate from each other. 
     In such way, water can be prevented from dripping when separating the humidifying rollers  231  and  231  from each other. 
     Furthermore, according to the embodiment, after the tip of a sheet of paper P passes a predetermined distance from the position corresponding to the nip portion, the second controller  270  controls the humidifying roller drive unit  231   a  so as to make the humidifying rollers  231  and  231  press against each other. 
     In such way, an appropriate amount of moisture can be applied to a sheet of paper P. 
     Moreover, according to the embodiment, the second controller  270  sets the predetermined distance on the basis of the paper condition. In particular, the second controller  270  sets the predetermined distance so as to be longer as the basis weight, which is the paper condition, be smaller. 
     Thus, the humidifying rollers  231  and  231  can be made to press against each other at an appropriate timing according to the paper condition. In particular, the smaller the basis weight, the later the timing for making the humidifying rollers  231  and  231  press against each other. 
     In such way, a sheet of paper P can be reliably prevented from being wrapped around one of the humidifying rollers  231  and  231 . 
     Furthermore, according to the embodiment, the blades  237  and  237  do not come in contact with their corresponding humidifying rollers  231  and  231  when the humidifying rollers  231  and  231  are separated from each other. 
     In such way, the humidifying rollers  231  and  231  can be prevented from being worn out. 
     Moreover, according to the embodiment, the present invention includes the operation display  180  for a user to operate on and set the operation timing of the humidifying rollers  231  and  231 . 
     In such way, a user can change the operation timing of the humidifying rollers  231  and  231  as he/she wishes. 
     In the embodiment, as an example of water removing units, the blades  237  and  237  which are disposed below their corresponding humidifying rollers  231  and  231  are described. However, the shape and disposing position of the water removing units are not limited to the above configuration as long as moisture can be removed from the humidifying rollers  231  and  231 . 
     Further, in the embodiment, an example where the blades  237  and  237  be in a state where they are not in contact with their corresponding humidifying rollers  231  and  231  as a result of the humidifying rollers  231  and  231 , which are pressed against each other, separate from each other is described in step S 13 . Alternatively, the blade drive unit  237   a  can control the blades  237  and  237  so as to rotate at the timing when the humidifying rollers  231  and  231  separate from each other so that the blades  237  and  237  be in a state where they do not come in contact with their corresponding humidifying rollers  231  and  231 . 
     Furthermore, in the embodiment, an example where each of the image forming apparatus  100 , the first paper processing apparatus  200  and the second paper processing apparatus  300  includes the controller which controls what is carried out inside the apparatus and performs communication with other apparatuses is described. Alternatively, there can be provided only one controller for integrally controlling the entire image forming system  1 . 
     Moreover, in the embodiment, an example where each of the image forming apparatus  100 , the first paper processing apparatus  200  and the second paper processing apparatus  300  includes the storage in which settings and the like of the apparatus are stored is described. Alternatively, there can be provided only one storage in which settings of the entire image forming system  1  are to be stored.