Abstract:
An image forming system includes an electrophotographic image forming apparatus which forms an image on a sheet of paper, and a paper coloring apparatus which is connected to the electro-photographic image forming apparatus. The paper coloring apparatus includes a coating apparatus having two coating rollers which coat colored water on both faces of the paper sheet on which the image has been formed by the electro-photographic image forming apparatus. A supply section selectively supplies one of the colored water and a colorless water onto the two coating rollers of the coating apparatus. And a controller is provided for switching between a coloring process to color the paper sheet by supplying the colored water onto the two coating rollers, and a humidifying process to humidify the paper sheet by supplying the colorless water onto the two coating rollers.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is based on Japanese Patent Application No. 2008-065481 filed with Japanese Patent Office on Mar. 14, 2008, the entire content of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a paper coloring apparatus for coloring a paper sheet on which an image is formed, and to an image forming system where an image forming apparatus and/or a book binding apparatus are connected to the paper coloring apparatus. 
     2. Description of Prior Art 
     As the paper sheets to be used in the image forming apparatus, commonly used are paper sheets of white color or colors of nearly white. 
     However, there are requirements of taking on suitable colors such as yellow, green or red for the paper sheets, in order to attain special effects. 
     To respond these requirements, it is needed to previously prepare various colored paper sheets, and to load a prescribed colored paper sheet on a prescribed sheet tray before starting the image forming operation. 
     However, to previously prepare many various colored paper sheets suitable for the requirement may cause a cost increase, as well as a heavy load for management. 
     In order to lessen these inconveniences, it has been considered to execute image formation subsequently to coloring a white paper sheet, or to color the paper sheet subsequently to the image formation. 
     As an apparatus for coloring a paper sheet, an apparatus which colors Japanese paper by inkjet system is disclosed for example in Unexamined Japanese Patent Application Publication No. H10-44388. 
     However, in utilizing the inkjet system, dissatisfaction in processing speed will be remarkable in cases where almost an entire surface of the paper sheet is to be colored, or both faces of the paper sheet are to be colored. 
     As an apparatus which coats liquid on a paper sheet after image formation, an apparatus which applies perfume onto a photographic paper sheet after development process is disclosed for example. 
     However, since applying perfume on the photographic paper does not require uniform coatings to both faces of the paper sheet, the configuration of the apparatus disclosed in Unexamined Japanese Patent Application Publication No. 2003-215772 cannot be directly adapted to an apparatus for coloring a paper sheet. 
     SUMMARY OF THE INVENTION 
     A paper coloring apparatus, reflecting one aspect of the present invention, includes a coating apparatus which coats colored water on both faces of a paper sheet on which an image has been formed by an electrophotographic image forming apparatus. 
     An image forming system reflecting another aspect of the present invention is characterized in that the above described paper coloring apparatus is connected to an electrophotographic image forming apparatus. 
     An image forming system reflecting another aspect of the present invention is characterized in that the above described paper coloring apparatus is connected with a book binding apparatus, which executes book binding to the paper sheets, the book binding apparatus being connected with the paper coloring apparatus downstream of the paper coloring apparatus in a conveyance direction of the paper sheet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a drawing to show a configuration example of an image forming system including an image forming apparatus, a paper coloring apparatus and a book binding apparatus; 
         FIG. 2  is a block diagram showing a control system of the image forming system; 
         FIG. 3  is a schematic diagram of the paper coloring apparatus; and 
         FIG. 4  is a schematic diagram of a coating apparatus. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter examples of the embodiment of the present invention will be described with reference to the drawings. 
       FIG. 1  is a drawing to show a configuration example of an image forming system including image forming apparatus A, paper coloring apparatus B and book binding apparatus C. 
     Image forming apparatus A includes an image forming section in which arranged around rotatable image carrier  1  are charging unit  2 , exposure unit  3 , developing unit  4 , transfer unit  5 A, charge neutralizing unit  5 B and cleaning unit  6 . In the image forming section, after charging unit  2  uniformly charges on a surface of image carrier  1 , a laser beam from exposure unit  3  exposes by scanning the image carrier  1  according to image data to form a latent image on image carrier  1 , and developing unit  4  develops the latent image by reversal development to form a toner image. 
     The toner image is transferred on to paper sheet S which has been fed from paper housing unit  7 A and conveyed to the transfer position, the paper sheet S carrying the transferred toner image is neutralized of the electric charge by neutralizing unit  5 B and is separated from image carrier  1 , and the paper sheet S is conveyed by conveyance unit  7 B to fixing unit  8 . 
     Meanwhile, after the toner image having been transferred onto paper sheet  1 , remaining toner on the surface is removed from the surface of image carrier  1  by cleaning unit  6 , and the image carrier  1  is prepared for the next image formation. 
     Fixing unit  8  includes heating roller  8 A provided with heater  8 C and pressure roller  8 B contacting and pressing the heating roller  8 A, and fixes the toner image on paper sheet S by pressing/heating the conveyed paper sheet carrying the toner image. 
     Paper sheet S having been processed of image fixing by the fixing unit  8  is conveyed out of the apparatus through sheet ejection roller  7 C. 
     In the case of executing the image formation on both faces of the paper sheet, paper sheet S having been heat-fixed by fixing unit  8  is branched from a usual sheet ejection path by conveyance path switching member  7 D, reversed by being switched-back at reverse conveyance unit  7 E, and sent back to the image forming section. 
     Paper sheet S having an image formed on the rear face is fixing processed by fixing unit  8 , and conveyed out of the apparatus through sheet ejection roller  7 C. 
     Paper sheet S conveyed out by sheet ejection roller  7   c  is sent into paper coloring apparatus B connected downstream in the sheet conveyance direction. 
     Paper coloring apparatus B is an apparatus for executing a coloring process and/or a humidifying process onto paper sheet S sent from image forming apparatus A connected upstream. 
     Paper coloring apparatus B of the present invention is provided with a first mode to convey paper sheet S from image forming apparatus A to book binding apparatus C without applying any process onto paper sheet S, a second mode to convey paper sheet S by applying a humidifying process, and a third mode to convey the paper sheet S by applying a coloring process. 
     Further, paper coloring apparatus B is provided with an uncurling unit to correct a curl of paper sheet S. 
     Selection from these modes and selection whether to apply uncurling or not are executed based on an instruction operation at operation display section  91  of image forming apparatus A or at operation display section  92  of paper coloring apparatus B, or based on an instruction from an external apparatus through a network. 
     Book binding apparatus C stacks the paper sheet S conveyed form paper coloring apparatus B to form a stack of paper, and makes a book by adhering a book cover on the stack of paper. 
     Book binding apparatus C of the present invention is configured with sheet conveyance section  210 , sheet ejection section  220 , book cover supply section  230 , stacked paper housing section  240 , stacked paper holding section  250 , adhesive coating section  260 , book cover adhering section  270 , book cover folding section  280 , and booklet ejection section  290 . 
     As shown in the drawing of  FIG. 1 , each of the above-described sections is arranged vertically in the apparatus. 
     In cases where the mode of not applying the book binding process is set through operation display section  91  of image forming apparatus A, the conveyance path to stacked paper housing section  240  is closed and the conveyance path to sheet ejection section  220  is opened. 
     In cases where the book binding mode is selected, paper sheet S is housed at a prescribed position in stacked paper housing section  240  and sequentially stacked to form a stack of paper having a prescribed number of sheets. 
     The stack of paper formed on stacked paper housing section  240  is sent to stacked paper holding section  250 , and in the state where stacked paper holding section  250  is rotated to be substantially vertical, the bottom side of the stacked paper is coated with adhesive by adhesive coating section  260 , to thus the stack of paper. 
     Onto the stack of paper having been bound, a book cover is supplied from book cover adhering section  270  and adhered, and the book cover is folded by the book cover folding section  280 , thus a booklet is formed. 
     The booklet formed as above is ejected by booklet erection section  290  from book binding apparatus C. 
     Book binding apparatus C is such an apparatus that is described in Unexamined Japanese Patent Application Publication No. 2004-209869. 
       FIG. 2  is a block diagram showing a control system of the image forming system. 
     Each of controller CA of image forming apparatus A, controller CB of paper coloring apparatus B, and controller CC of book binding apparatus C is a computer system including a CPU, a memory, a computing unit, an I/O port, a communication interface, and a drive circuit, etc. 
     Control by each of the controllers mentioned above is performed by executing the prescribed program stored in memory MA, MB, or MC provided in the respective controller. 
     Further, the controllers are connected with each other through communication section TR, and are capable of communicating with each other. 
     In  FIG. 2 , blocks of features not directly related to the present invention are omitted from the description. 
       FIG. 3  is a schematic diagram of paper coloring apparatus B. 
     Paper coloring apparatus B of the present invention is able, in addition to performing the coloring process to color paper sheet S sent from image forming apparatus A, to perform a humidifying process for removing the curl of paper sheet S. 
     Paper sheet S sent from image forming apparatus A enters into paper coloring apparatus B from the direction of arrow mark “a”, and goes through either of sheet conveyance paths H 1 , H 3 , and H 4  or conveyance paths H 1 , H 2 , H 4 , and sent away to book binding apparatus C disposed in the direction of arrow “b”. 
     Sheet conveyance path H 1  is a path which takes paper sheet S sent from image forming apparatus A into paper coloring apparatus B, and conveyance path H 4  is for sending paper sheet S out of the apparatus. 
     The above mentioned sheet conveyance paths H 1 , H 3 , H 4  are the paths which are used in cases where the coloring process or the humidifying process is not applied to paper sheet S, and the above mentioned sheet conveyance paths H 1 , H 2 , H 4  are the paths which are used in cases where the coloring process or the humidifying process is applied to paper sheet S. 
     In each sheet conveyance path, sheet conveyance means such as a plurality of guide members (not illustrated) and conveyance rollers are disposed, and paper sheet S is guided by the guide means to proceed along the prescribed sheet conveyance path. 
     At an entrance port and an ejection port for paper sheet S, sheet detection sensors D 1  and D 2  are provided respectively to detect a leading edge and a trailing edge of paper sheet S. 
     Detection signals of the sheet detection sensors are sent to controller CB, and based on the detection signals controller CB calculates the position of paper sheet S in the sheet conveyance paths. 
     Conveyance rollers R 11 , R 12 , and R 13  which are disposed in sheet conveyance path H 1  as the conveyance means are variable speed rollers and their rotation speed are controlled by controller CB. 
     Similarly, conveyance rollers R 41 , R 42 , and R 43  are disposed in conveyance path H 4 , and their rotation speed are controlled by controller CB based on the detection signals sent from sheet detection sensor D 2 . 
     The above mentioned controller CB controls the rotation speed of each conveyance roller based on the position information of paper sheet S obtained on the basis of the detection signals from sheet detection sensors D 1  and D 2 , and based on mode information indicating the process mode sent from controller CA of image forming apparatus A. 
     As described above, by providing the conveying speed varying means to vary the conveying speed of paper sheet S, in sheet conveyance path H 1  for taking-in paper sheet S, or in conveyance path H 4  for sending paper sheet S having been applied the prescribed process out of the apparatus, problems regarding the sheet conveyance, which are caused by the difference of conveying speed among speeds in image forming apparatus A, paper coloring apparatus B, and book binding apparatus C, can be prevented. 
     Sheet conveyance path H 2  is a path to be selected in cases where paper sheet S is applied a coloring process by coating apparatus  130  provided in the conveyance path. 
     Below conveyance path H 2 , arranged are tank T 1  for storing coloring liquid as coating liquid, tank T 2  for storing water to be used for humidifying, and waste liquid tank T 3  for storing waste liquid. 
     Waste liquid tank T 3  accepts liquid mixture formed in the course of changing the coating liquid from the coloring liquid to colorless water, or changing from the water to the coloring liquid. 
     The coloring liquid stored in tank T 1  is sent by pump P into coating apparatus  100  through switching valve X 1 , and overflowed coloring liquid is returned into tank T 1  through switching valve X 2  to be repeatedly used. 
     Similarly, the water stored in tank T 2  is sent by pump P into coating apparatus  100  through switching valve X 1 , and overflowed water is returned into tank T 2  through switching valve X 2  to be repeatedly used. 
     Above coating apparatus  100 , uncurling unit  200  to correct the curl of paper sheet S is provided, which is a publicly known technical means to correct the curl of paper sheet S. 
     As described above, the selection whether to apply uncurling or not are executed based on an instruction operation at operation display section  91  of image forming apparatus A or at operation display section  92  of paper coloring apparatus B, or based on an instruction from an external apparatus through a network. 
       FIG. 4  is a schematic diagram of coating apparatus  100 . 
     Coating apparatus  100  executes the coating of coloring liquid or colorless water on both faces of paper sheet S while vertically conveying paper sheet S, by two coating rollers arranged to be opposed with each other. 
     As shown in  FIG. 4 , coating apparatus  100  includes a plurality of members symmetrically arranged being centered by the sheet conveyance path. 
     Coating apparatus  100  is configured including: coating liquid storage section  101  provided with coating liquid saucers  111  and  112  to contain a certain amount of coating liquid; supply rollers  121  and  122 , each portion of whose circumference surfaces being immersed in the liquid in coating liquid saucers  111  and  112 ; control rollers  131  and  132  adjacent to respective circumferences of supply rollers  121  and  122 ; and coating rollers  141  and  142  arranged to be opposed with each other and to contact respectively with supply rollers  121  and  122 . 
     Coating liquid saucers  111  and  112  store a certain amount of coloring liquid or water sent from tank T 1  or T 2  by pump P, and the coloring liquid or the water overflowed from the saucers flows-out to a prescribed portion of coating liquid storage section  101 . 
     The coloring liquid or the water flowed-out is returned to tank T 1  or tank T 2 , as explained above, and is reused. 
     Supply rollers  121  and  122  rotate in a state such that each has a portion of a circumferential surface thereof immersed in the liquid in coating liquid saucers  111  and  112 . Supply rollers  121  and  122  are made including a solid gum member for example NBR (nitrile-butadiene rubber). 
     Control rollers  131  and  132  are arranged to keep a prescribed gap respectively from supply rollers  121  and  122 , or to press with a prescribed pressing force respectively to supply rollers  121  and  122 . 
     By control rollers  131  and  132 , an amount of coating liquid, attached by dipping, on the circumference of supply rollers  121  and  122  is controlled to be constant. 
     The coating liquid on the circumference of supply rollers  121  and  122  is transferred onto coating rollers  141  and  142 , and subsequently transferred onto paper sheet S from coating rollers  141  and  142 . 
     Meanwhile, since the colored water or the colorless water as the coating liquid hardly adheres to a hydrophobic toner image on paper sheet S, the toner image itself is not colored. 
     As shown in  FIG. 4 , since paper sheet S is conveyed upward from below, formation of liquid puddle between each of coating rollers  141 - 142  and paper sheet S is prevented, and as the result, uneven coating is reduced. 
     Further, since each of coating rollers  141  and  142  has the same diameter, it is easy to apply he same amount of coating on each of both faces of paper sheet S, and conveyance of paper sheet S is stabilized. 
     As described above, the image forming system is realized which executes the coloring process or the humidifying process to paper sheet S on which an image has been formed by image forming apparatus A, and binds the processed paper sheet S to form a book. 
     Each apparatus composing the above described image forming system can be combined and operated to sequentially execute the prescribed processes, or otherwise, can be separated to each apparatus and is separately operated to execute the prescribed processes by batch processing. 
     Further, another configuration is possible where the paper coloring apparatus is arranged in the image forming apparatus or in the book binding apparatus. 
     According to the present invention, a paper coloring apparatus is realized which colors an image formed paper sheet at high speed.