Patent Publication Number: US-9423755-B2

Title: Printing apparatus, printing system, printing method and non-transitory recording medium

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Japanese Patent Application No. 2013-266523, filed on Dec. 25, 2013, the entire disclosure of which is incorporated by reference herein. 
     FIELD 
     This application relates generally to a printing apparatus, printing system, printing method and non-transitory recording medium. 
     BACKGROUND 
     As a recording medium for an image-forming apparatus such as a printer, a copier, a facsimile machine and/or the like to form images, a roll-wound recording medium (hereafter called roll paper) in which a recording medium such as paper, film and/or the like is wound around a roll shape exists. The roll paper can be stored without needing to be cut, and thus is widely used when accomplishing large-area image formation without a break, for example in a label printer continuously printing multiple labels or seals. 
     Accompanying increases in printing quality with digital printing, even with large-area printing using roll paper, quality close to that of printed materials such as flexography, gravure printing, offset printing and/or the like is needed. Consequently, printing with white, transparent and other colors on the roll paper is demanded, in addition to the four colors of YMCK (yellow (Y), magenta (M), cyan (C) and black (K)) that can be used with typical color printers under a four-way tandem method. 
     Printers corresponding to five-way or more tandem methods are known as a method of adding white and/or other colors to the four colors of YMCK in color printers (for example, see Unexamined Japanese Patent Application Kokai Publication No. 2011-174984). 
     In addition, a method of creating the K color (black) out of YMCK by superimposing the three colors of YMC (process black) and adding another color in place of the K color is known. 
     SUMMARY 
     A printing apparatus according to a first aspect of the present disclosure comprises: 
     a printing unit that prints images on a recording medium unwound by an unwinder; 
     a first winder that winds the printed recording medium around a first winding shaft in order from a beginning edge to an ending edge of the recording medium; and 
     a second winder that rewinds the recording medium wound around the first winding shaft, and winds the rewound recording medium around a second winding shaft in order from the ending edge to the beginning edge of the recording medium. 
     A printing system according to a second aspect of the present disclosure comprises: 
     a first image-forming unit that forms a first developing agent image on a recording medium unwound by a first unwinder; 
     a first winder that winds the recording medium on which the first developing agent image was formed around a first winding shaft in order from a beginning edge to an ending edge of the recording medium; 
     a second winder that rewinds the recording medium wound around the first winding shaft, and winds the unwound recording medium around a second winding shaft in order from the ending edge to the beginning edge of the recording medium; 
     a second unwinder that unwinds the recording medium wound around the second winding shaft in order from the beginning edge to the ending edge of the recording medium; and 
     a second image-forming unit that forms a second developing agent image on a surface of the recording medium unwound by the second unwinder on which the first developing agent image was formed. 
     A printing method according to a third aspect of the present disclosure includes: 
     forming a first developing agent image on an unwound recording medium; 
     winding the recording medium on which the first developing agent image was formed around a first winding shaft, in order from a beginning edge to an ending edge of the recording medium; 
     rewinding the recording medium wound around the first winding shaft, and winding the rewound recording medium around a second winding shaft, in order from the ending edge to the beginning edge of the recording medium; 
     unwinding the recording medium wound around the second winding shaft, in order from the beginning edge to the ending edge of the recording medium; and 
     forming a second developing agent image on a surface of the unwound recording medium on which the first developing agent image was formed. 
     A non-transitory computer-readable recording medium according to a fourth aspect of the present disclosure has stored thereon a program executable by a computer, the program controlling the computer to perform functions comprising: 
     forming a first developing agent image on an unwound recording medium; 
     winding the recording medium on which the first developing agent image was formed around a first winding shaft, in order from a beginning edge to an ending edge of the recording medium; 
     rewinding the recording medium wound around the first winding shaft, and winding the rewound recording medium around a second winding shaft, in order from the ending edge to the beginning edge of the recording medium; 
     unwinding the recording medium wound around the second winding shaft, in order from the beginning edge to the ending edge of the recording medium; and 
     forming a second developing agent image on a surface of the unwound recording medium on which the first developing agent image was formed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of this application can be obtained when the following detailed description is considered in conjunction with the following drawings, in which: 
         FIG. 1  is a drawing showing the composition of a printing system according to a first exemplary embodiment of the present disclosure; 
         FIG. 2A  is side view of a winding apparatus; 
         FIG. 2B  is an oblique view of the winding apparatus; 
         FIG. 3A  is a cross-sectional view showing the internal composition of a first image-forming apparatus; 
         FIG. 3B  is a cross-sectional view showing the internal composition of a second image-forming apparatus; 
         FIG. 4  is a block diagram showing a composition relating to control of the first image-forming apparatus, the second image-forming apparatus and a terminal apparatus; 
         FIG. 5A  is a drawing showing an example of image data of a printing target; 
         FIG. 5B  is a drawing showing an example of normal color image data; 
         FIG. 5C  is a drawing showing an example of special color image data; 
         FIG. 6  is a drawing showing a state preparing for printing in the printing system; 
         FIG. 7  is a block diagram showing a composition relating to control of a first paper supply apparatus, a second paper supply apparatus and a winding apparatus; 
         FIG. 8A  is a drawing showing roll paper supplied from the first paper supply apparatus; 
         FIG. 8B  is a drawing showing roll paper after image formation by the first image-forming apparatus; 
         FIG. 9A  is a front view and a side view showing the state when the winding apparatus accomplishing a first winding; 
         FIG. 9B  is an oblique view showing the state when the winding apparatus accomplishes the first winding; 
         FIGS. 10A and 10B  are a front view and a side view showing the state when the winding apparatus accomplishes a second winding; 
         FIG. 11  is a drawing showing the state when the roll paper wound by the winding apparatus is attached to the holder of the second paper supply apparatus; 
         FIG. 12A  is a drawing showing the roll paper supplied from the second paper supply apparatus; 
         FIG. 12B  is a drawing showing the roll paper after image formation by the second image-forming apparatus; 
         FIG. 13  is a first flowchart showing the flow of processes executed in the printing system according to the first exemplary embodiment; 
         FIG. 14  is a second flowchart showing the flow of processes executed in the printing system according to the first exemplary embodiment; 
         FIG. 15  is a flowchart showing the flow of processes executed in the winding apparatus; 
         FIG. 16  is a drawing showing the composition of a printing system according to a second exemplary embodiment of the present disclosure; 
         FIG. 17  is a drawing showing the state when the second image formation is accomplished in the printing system according to the second exemplary embodiment; 
         FIG. 18  is a drawing showing the composition of a printing system according to a third exemplary embodiment of the present disclosure; and 
         FIG. 19  is a drawing showing the state when the second image formation is accomplished in the printing system according to the third exemplary embodiment; 
     
    
    
     DETAILED DESCRIPTION 
     Below, the exemplary embodiments of the present disclosure are described with reference to the drawings. Parts that are the same or corresponding in the drawings are labeled with the same reference symbols. 
     First Exemplary Embodiment 
       FIG. 1  shows the composition of a printing system according to a first exemplary embodiment. The printing system  100  comprises a normal color printing system  10   a  comprising a paper supply apparatus  1   a  and an image-forming apparatus  2   a , a special color printing system  10   b  comprising a paper supply apparatus  1   b  and an image-forming apparatus  2   b , and a winding apparatus  9 . The printing system  100  prints in multiple colors on roll paper  3  that is a roll-wound recording medium, by using the normal color printing system  10   a  and the special color printing system  10   b.    
     The paper supply apparatus  1   a  provided in the normal color printing system  10   a  supplies the roll paper  3  to the image-forming apparatus  2   a . The paper supply apparatus  1   a  continuously unwinds the roll paper  3  in which paper is wound in a rolled sate around a prescribed winding core (paper tube) and conveys the roll paper  3  to the image-forming apparatus  2   a  along a prescribed conveyance path. Specifically, the paper supply apparatus  1   a  comprises a slide table  7   a , a holder  8   a , an incline detection sensor  11   a , a side guide  12   a , a paired conveyor roller  13   a , an auto cutter  14   a , a mark sensor  15   a , a paired feed roller  16   a  and a feed sensor  17   a.    
     The holder  8   a  functions as a first holder and holds the roll paper  3  prior to an image being formed by the image-forming apparatus  2   a . The holder  8   a  comprises a rotatable rotation shaft that holds the roll paper  3  via the winding core at the winding center of the roll paper  3 , and a support table that supports the rotation shaft, and supports the roll paper  3  so that rotation is possible. 
     An unrepresented motor for causing the rotation shaft to rotate is mounted in the holder  8   a . The holder  8   a  functions as an unwinder that unwinds the roll paper  3  held by causing the rotation shaft to rotate an indicated number of rotations per unit time (the number of times rotated per unit time) under driving by the motor. 
     In addition, an unrepresented powder brake is attached to the rotation shaft of the holder  8   a . The powder brake applies a brake to rotation of the rotation shaft so that the tension applied to the roll paper conveyed by being unwound from the holder  8   a  is kept constant. Through the function of the powder brake, the roll paper  3  unwound from the holder  8   a  is conveyed stably without slackening. 
     The slide table  7   a  is provided with a slide bearing on both sides and causes the holder  8   a  to slide in the direction of the rotation shaft (the sideways direction of the roll paper  3 ). When the slide table  7   a  detects an incline of the roll paper  3  conveyed inside the paper supply apparatus  1   a , drive force is obtained through an actuator and causes the holder  8   a  to move in a direction to negate the detected incline. 
     The incline detection sensor  11   a  detects inclines of the roll paper  3  conveyed inside the paper supply apparatus  1   a . Specifically, the incline detection sensor  11   a  comprises multiple sets of light-emitting elements and light-receiving elements positioned so that interposed in between is the end of the roll paper  3  in the sideways direction. The incline detection sensor  11   a  determines the position deviation of the end of the roll paper  3  in the sideways direction without contacting the roll paper  3 , by determining whether or not light emitted from the light-emitting elements is received by the light-receiving elements without being blocked, for each of the multiple sets. 
     The paired conveyor roller  13   a  sandwiches and conveys the roll paper  3  unwound from the holder  8   a  and conveyed via the following roller and the side guide  12   a , and supplies the roll paper  3  to the paired feed roller  16   a . The paired feed roller  16   a  sandwiches and conveys the roll paper  3  supplied from the paired conveyor roller  13   a , and supplies the roll paper  3  to the image-forming apparatus  2   a.    
     The auto cutter  14   a  cuts the roll paper  3  as necessary. The auto cutter  14   a  cuts the final end (back edge) of the roll paper  3  for example when roll paper  3  of a length necessary for image formation in the image-forming apparatus  2   a  has finished being conveyed. 
     The mark sensor  15   a  detects an original mark recorded on the surface of the roll paper and used by the image-forming apparatus  2   a  as a position reference for forming images. Specifics of the original mark are described below. 
     The feed sensor  17   a  detects the beginning edge (front edge) of the roll paper  3  fed to the image-forming apparatus  2   a  from the paired feed roller  16   a . Specifically, the feed sensor  17   a  comprises a light-emitting element and a light-receiving element, and determines that the beginning edge of the roll paper  3  has been detected when light emitted from the light-emitting element is blocked by the beginning edge of the roll paper  3  and is not detected by the light-receiving element. When the feed sensor  17   a  detects the beginning edge of the roll paper  3 , the image-forming apparatus  2   a  starts driving of the various types of roller pairs and causes the roll paper  3  fed to the inside to be conveyed. 
     The paper supply apparatus  1   b  with which the special color printing system  10   b  is equipped supplies roll paper  3  to the image-forming apparatus  2   b  as a recording medium for image formation. Specifically, the paper supply apparatus  1   b  comprises a slide table  7   b , a holder  8   b , an incline detection sensor  11   b , a slide guide  12   b , a paired conveyor roller  13   b , an auto cutter  14   b , a mark sensor  15   b , a paired feed roller  16   b  and a feed sensor  17   b . The holder  8   b  functions as a second holder and holds the roll paper  3  after an image is formed by the first image-forming apparatus  2   a  and the paper is wound by a winder  97 . The paper supply apparatus  1   b  has the same composition as the above-described paper supply apparatus  1   a , so detailed explanation of the various constituent elements comprising the paper supply apparatus  1   b  is omitted. 
     A winding apparatus  9  comprises a first winding shaft  91 , a second winding shaft  92  and a guide roller  93 . The winding apparatus  9  functions as a rewinder, and winds and holds the roll paper  3  ejected from the image-forming apparatus  2   a  and conveyed via the guide roller  93  around the first winding shaft  91 . In addition, the winding apparatus  9  unwinds the roll paper  3  wound around the first winding shaft  91 , and again winds the roll paper  3  around the second winding shaft  92 . 
     More specifically, as shown in  FIG. 2A  and  FIG. 2B , the first winding shaft  91 , the second winding shaft  92  and the guide roller  93  are positioned on a side surface  94  so that the respective shaft directions are perpendicular to the common side surface  94  in the winding apparatus  9 . Because the first winding shaft  91  and the second winding shaft  92  are positioned on the common side surface  94 , it is possible for the first winding shaft  91  to unwind the wound roll paper  3  and for the second winding shaft  92  to smoothly wind the roll paper  3  again. In addition, the winding apparatus  9  is provided on the bottom with wheels for moving and can be mounted on either the normal color printing system  10   a  or and the special color printing system  10   b.    
     Unrepresented motors are provided in the first winding shaft  91  and the second winding shaft  92 , and wind the roll paper  3  by rotating at a number of rotations per unit time specified through driving by the motors. In addition, the first winding shaft  91  is provided with a clutch mechanism for interrupting the transfer of drive power from the motor when excessively large torque is applied. Through this, the roll paper  3  that is being wound is prevented from being pulled excessively tight so that the precision of image formation declines. 
     The image-forming apparatus  2   a  with which the normal color printing system  10   a  is equipped is placed on top of the paper supply apparatus  1   a  and functions as a first image-forming unit that forms (transfers and fixes) a first developing agent image through developing agent in the four colors of YMCK (yellow (Y), magenta (M), cyan (C) and black (K)) based on image data of the printing target, and forms the first developing agent image on the roll paper  3  supplied from the paper supply apparatus  1   a . The image-forming apparatus  2   b  with which the special color printing system  10   b  is equipped is placed on top of the paper supply apparatus  1   b  and functions as a second image-forming unit that forms a second developing agent image through developing agent of special colors not included in the four colors of YMCK and forms the second developing agent image on the roll paper  3  supplied from the paper supply apparatus  1   b.    
     The internal compositions of the image-forming apparatus  2   a  and the image-forming apparatus  2   b  is described with reference to  FIG. 3A  and  FIG. 3B . Below, the image-forming apparatus  2   a  and the image-forming apparatus  2   b  are described by taking as an example a secondary transfer-type tandem color printer of electronic photo format. In addition, the explanation below takes as an example a case in which toner is used as the developing agent. 
     As shown in  FIG. 3A , the image-forming apparatus  2   a  comprises an image-forming unit  20   a , an intermediate transfer belt unit  30   a  and a fuser apparatus  40   a.    
     The image-forming apparatus  20   a  is provided with a composition in which four Image-forming parts  21   y ,  21   m ,  21   c  and  21   k  are arranged linearly. The Image-forming parts  21   y ,  21   m  and  21   c  form color images through color toner of yellow (Y), magenta (M) and cyan (C), which are the three primary colors of subtractive mixture colors. On the other hand, the Image-forming part  21   k  forms monochrome images of black (K) toner used primarily in text and dark parts of images, and or the like. 
     Each of the Image-forming parts  21  comprises a photosensitive drum  22  at the bottom. This photosensitive drum  22  comprises an organic photoconductive material, for example, on a cylinder surface. Near the photosensitive drum  22 , a cleaner  23 , a charged roller  24 , an optical writing head  25  and a developing roller  27  of a developer  26  are positioned as though surrounding the cylinder surface. 
     The developer  26  stores toner of yellow (Y), magenta (M), cyan (C) and black (K) in a toner container positioned on top, in the center is provided with a toner replenishing mechanism to the bottom, and on the bottom is provided with the developing roller  27 . The developer  26  is further equipped with a toner stirrer inside, a toner supply roller for supplying toner to the developing roller  27 , and a doctor blade for regulating the toner layer on the developing roller  27  to a constant thickness. 
     Reference symbols are appended to only the composition of the Image-forming part  21   y  for yellow (Y) in  FIG. 3A  and  FIG. 3B , but each of the Image-forming parts  21  ( 21   y ,  21   m ,  21   c ,  21   k ,  21   w   1 ,  21   w   2 ,  21   s   1  and  21   s   2 ) have the same composition excepting for the color of the toner stored in the toner container. 
     The intermedia transfer belt unit  30   a  comprises an endless transfer belt  31  extending in a flat loop shape substantially in the center of the image-forming apparatus  2   a ; a driving roller  32  over which the transfer belt  31  is passed, the driving roller  32  causing the transfer belt  31  to circulate and move in a counter-clockwise direction; and a following roller  33 . The transfer belt  31  conveys the toner image transferred (primary transfer) directly to the belt surface to the transfer position so that toner image on the belt surface can transfer (secondary transfer) to the roll paper  3 . 
     The intermediate transfer belt unit  30   a  is provided with four primary transfer rollers  34  corresponding to the four Image-forming parts  21   y ,  21   m ,  21   c ,  21   k , within the loop of the transfer belt  31 . The primary transfer rollers  34  comprise conductive foam sponges for pressing against the bottom cylinder surface of the photosensitive drum  22  via the transfer belt  31 , and rotate with a specified rotation period and cause the transfer belt  31  to abut the photosensitive drum  22  and separate from the photosensitive drum  22 . 
     A paired standby conveyor roller  35  receives the roll paper  3  supplied from the paper supply apparatus  1  via a feed opening for expansion paper supply, and conveys the roll paper  3  received to a secondary transfer roller  36 . The secondary transfer roller  36  is positioned so as to press against the following roller  33  via the transfer belt  31 , and forms a secondary transfer unit that makes a secondary transfer to the roll paper  3  of the toner image transferred to the belt surface of the transfer belt  31 . 
     The fuser apparatus  40   a  comprises a heating roller  42  into which a heater  41  is built, and a pressure roller  43  that presses against the heating roller  42 . The fixing apparatus  40   a  heats and presses on, thereby fixing, the unfixed toner on the roll paper  3  after secondary transfer. 
     In addition, on the downstream side of the fuser apparatus  40   a , a paper discharge roller pair  44  is positioned for discharging the roll paper  3  from the image-forming apparatus  2   a  after toner fixing. The roll paper  3  that has passed through the paper discharge roller pair  44  is discharged from the image-forming apparatus  2   a  and is wound by the winding apparatus  9 . 
     As shown in  FIG. 3B , the image-forming apparatus  2   b  comprises an image-forming unit  20   b , an intermediate transfer belt unit  30   b  and a fuser apparatus  40   b . The image-forming apparatus  2   b  has the same composition as the image-forming apparatus  2   a  with the exception of the color of toner stored in the four Image-forming parts  21   w   1 ,  21   w   2 ,  21   s   1  and  21   s   2  in the image-forming unit  20   b . Consequently, detailed description of the other constituent elements comprising the image-forming apparatus  2   b  is omitted. 
     The image-forming unit  20   b  is provided with a composition in which four Image-forming parts  21   w   1 ,  21   w   2 ,  21   s   1  and  21   s   2  that form images using toner of colors not including the four colors of YMCK are arranged linearly. By using toner of special colors, it is possible to express colors that cannot be expressed by the four colors of YMCK and it is possible to increase the quality of printed materials. 
     Specifically, the Image-forming parts  21   w   1  and  21   w   2  both comprise toner containers containing white (W) toner and form images with white toner. That is to say, the image-forming apparatus  2   b  forms white toner images respectively with the two Image-forming parts  21   w   1  and  21   w   2 , and forms white images by superimposing the two white toner images on the transfer belt  31 . By superimposing two white toner images, it is possible to express images with white of sufficient depth without the base colors becoming transparent, even when for example images are formed in areas where base colors such as black or red are deep. 
     On the other hand, the Image-forming parts  21   s   1  and  21   s   2  respectively comprise toner containers containing toner of special colors other than white and form images through the special-colored toner. As special colors other than white, gold, silver, transparent (invisible) colors that emit light when irradiated with ultraviolet rays and special colors for providing fluorescent light or gloss, and/or the like, can be cited. The Image-forming parts  21   s   1  and  21   s   2  form images through toner of at least one or more of these colors. 
     Next, referring to  FIG. 4 , the composition relating to control of the image-forming apparatus  2   a  and the image-forming apparatus  2   b  is described. The image-forming apparatus  2   a  and the image-forming apparatus  2   b  are connected to each other by a terminal apparatus  60  and a network such as a LAN (Local Area Network) and/or the like or a USB (Universal Serial Bus). 
     The image-forming apparatus  2   a  comprises a CPU (Central Processing Unit)  50   a , a LAN communicator  51   a , a USB communicator  52   a , a panel controller  53   a , an operation panel  54   a , a command analyzer  55   a , a memory apparatus controller  56   a , a memory apparatus  57   a  and a print controller  58   a.    
     The CPU  50   a  is connected to the various components of the image-forming apparatus  2   a  via a system bus that is a transmission route for transmitting commands and data, and controls the actions of the various components of the image-forming apparatus  2   a . The CPU  50   a , while using an unrepresented ROM (Read Only Memory) and RAM (Random Access Memory) as work memories, reads out various types of programs such as system software and/or the like stored in the ROM and the memory apparatus  57   a  and executes appropriately. 
     The LAN communicator  51   a  and the USB communicator  52   a  communicate with external equipment including the terminal apparatus  60 , the paper supply apparatus  1   a  and the winding apparatus  9  via the LAN and USB, respectively. 
     The panel controller  53   a  is connected to the operation panel  54   a  comprising for example a display panel such as an LCD (Liquid Crystal Display) and/or the like and an input apparatus including various types of operation buttons. The panel controller  53   a , under control of the CPU  50   a , displays images and text and/or the like on the operation panel  54   a  and receives operations from a user input into the operation panel  54   a.    
     The command analyzer  55   a , under control of the CPU  50   a , analyzes commands included in print data sent from the terminal apparatus  60  and converts the print data into bitmap image data. The command analyzer  55   a  develops the converted bitmap image data in a memory area corresponding to frame memory for each color of toner with which the image-forming apparatus  2   a  is equipped. The image data developed in the frame memory is output to the print controller  58   a.    
     The memory apparatus  57   a  is non-volatile memory such as an EEPROM (Electrically Erasable Programmable ROM), HDD (Hard Disk Drive) and/or the like. The memory apparatus controller  56   a , under control of the CPU  50   a , controls writing of data to the memory apparatus  57   a  and reading of data stored in the memory apparatus  57   a.    
     The print controller  58   a , under control of the CPU  50   a , controls the printing mechanism including the image-forming unit  20   a , the intermediate transfer belt unit  30   a  and the fuser apparatus  40   a , and accomplishes a printing process in accordance with image data generated by the command analyzer  55   a.    
     The image-forming apparatus  2   b  comprises a CPU  50   b , a LAN communicator  51   b , a USB communicator  52   b , a panel controller  53   b , an operation panel  54   b , a command analyzer  55   b , a memory apparatus controller  56   b , a memory apparatus  57   b  and a printing controller  58   b . The image-forming apparatus  2   b  has a composition relating to control the same as the image-forming apparatus  2   a , so detailed description is omitted. 
     The terminal apparatus  60  is for example an information processing apparatus such as a PC (Personal Computer) and/or the like, and is connected to the two image-forming apparatuses  2   a  and  2   b  via the LAN and the USB. The terminal apparatus  60  comprises a controller  61 , a communicator  62 , an operation unit  63 , a display unit  64  and a memory unit  65 . 
     The controller  61  comprises for example a CPU and RAM and/or the like that functions as a main memory of the CPU. The controller  61  is connected to each component of the terminal apparatus  60  via a system bus that is a transmission route for transmitting commands and data, and controls the terminal apparatus  60  as a whole. 
     The communicator  62 , under control of the controller  61 , communicates with the two image-forming apparatuses  2   a  and  2   b  via the USB or the LAN. 
     The operation unit  63  comprises an input apparatus such as a mouse, keyboard and/or the like. The operation unit  63  receives operations from a user. For example, the operation unit  63  supplies to the controller  61  a signal for setting print conditions or a signal for executing printing. 
     The display unit  64  comprises for example a display device such as a CRT (Cathode Ray Tube), an LCD and/or the like. The display unit  64  displays on a screen images based on image data supplied from the controller  61 . 
     The memory unit  65  comprises for example a memory apparatus such as an HDD, ROM, flash memory and/or the like. The memory unit  65  stores programs and data the controller  61  uses for executing various types of processes, including printer drivers for printing in multiple colors using the two image-forming apparatuses  2   a  and  2   b.    
     As shown in  FIG. 5A  as an example, the description is for a case in which image data  70  of multiple labels with the various labels comprising the figures of a square, a circle and a triangle are printed to the roll paper  3  from the terminal apparatus  60  using the printing system  100 . 
     When a user operates the operation unit  63  and accomplishes a print command for image data  70  of a printing target via a prescribed application, the controller  61  generates image data for the normal color printing system  10   a  and image data for the special color printing system  10   b  in accordance with the printer driver stored in the memory unit  65 . 
     To explain more specifically, the controller  61  extracts image data that should be output with black (K) toner from the image data  70  of the printing target as image data for the normal color printing system  10   a , and generates normal color image data  71  for example as shown in  FIG. 5B . When color printing is commanded, the controller  61  further generates the image data that should be output with toner of the colors YMC as image data for the normal color printing system  10   a.    
     In addition, the controller  61  extracts image data that should be output with special colors of toner from the image data  70  of the printing target, as image data for the special color printing system  10   b , and generates special color image data  73  for example as shown in  FIG. 5C . When printing using multiple types of special colors is commanded, the controller  61  generates the multiple items of image data commanded as image data for the special color printing system  10   b.    
     The controller  61  sends first print data including the generated normal color image data  71  and print conditions to the image-forming apparatus  2   a  via the communicator  62 . In addition, the controller  61  sends second print data including the generated special color image data  73  and print conditions to the image-forming apparatus  2   b  via the communicator  62 . The print conditions are setting conditions relating to image formation such as resolution and gradation value, and other printing setting conditions such as the size and type of roll paper  3  and printing range. 
     When the first and second print data are sent, the printing process in the printing system  100  starts. Prior to the start of printing, the user attaches the roll paper  3  prior to printing with a beginning edge  77  anchored by anchor-tape  74  to the holder  8   a  of the paper supply apparatus  1   a , for example as shown in  FIG. 6 . Furthermore, the user causes the winding apparatus  9  to move and mounts such on the normal color printing system  10   a , and makes preparations for winding the roll paper  3  the image-forming apparatus  2   a  discharges. 
     In a state in which printing preparations are thus concluded, when the first and second print data are sent from the terminal apparatus  60 , the paper supply apparatuses  1   a  and  1   b  and the winding apparatus  9  are driven and printing starts. The composition relating to control of the paper supply apparatuses  1   a  and  1   b  and the winding apparatus  9  is described with reference to  FIG. 7 . 
     A controller  81   a  with which the paper supply apparatus  1   a  is equipped controls the actions of the paper supply apparatus  1   a  as a whole through the functions of an unrepresented CPU, RAM, ROM and/or the like. Specifically, the controller  81   a  functions as an unwinder  82   a , conveyor  83   a  and detector  84   a.    
     The unwinder  82   a  functions as a first unwinder and unwinds the roll paper  3  held by the holder  8   a . That is to say, when a paper supply request is received from the image-forming apparatus  2   a  that has received the first print data, the unwinder  82   a  causes the rotation shaft of the holder  8   a  to rotate and unwinds the roll paper  3  installed on the holder  8   a  in order from the beginning edge  77 . The conveyor  83   a  causes the paired conveyor roller  13   a  and the paired feed roller  16   a  to be driven and successively conveys to the image-forming apparatus  2   a  the roll paper  3  unwound by the unwinder  82   a.    
     An original mark  75  is recorded in advance on the roll paper  3 . The original mark  75  functions as a reference mark that is a position reference when the image-forming apparatus  2   a  forms images on the roll paper  3 . The detector  84   a  functions as a first detector and detects by means of the mark sensor  15   a  the original mark  75  recorded on the roll paper  3  conveyed by the conveyor  83   a  after being unwound by the unwinder  82   a.    
     For example, as shown in  FIG. 8A , the original mark  75  is recorded at fixed intervals at multiple positions from the beginning edge  77  to a ending edge  78  of the roll paper  3 . The intervals are set to a length corresponding to the pitch of the labels in the image data  70  to be output, so that the image-forming apparatus  2   a  can adjust the position of image formation for each label. To facilitate understanding,  FIG. 8A  shows a state with the entirety of the roll paper  3  unwound and spread out. In addition, an arrow indicates the conveyance direction of the roll paper  3 . The same is true in below-described  FIG. 8B ,  FIG. 12A  and  FIG. 12B . 
     The image-forming apparatus  2   a  forms (develops) a first toner image of toner in the four colors of YMCK and forms (transfers, and fixes) the first toner image on the roll paper  3  conveyed by the conveyor  83   a , based on the normal color image data  71  sent from the terminal apparatus  60 . At this time, the image-forming apparatus  2   a  forms the first toner image on the roll paper  3  with the original mark  75  detected by the detector  84   a  as the position reference, so that the region in which the first toner image is formed does not shift up-and-down or left-and-right. As a result, an output image for multiple labels for example as shown in  FIG. 8B  is output to the roll paper  3 . The roll paper  3  on which the first toner image is recorded is fixed by the fuser apparatus  40   a  and is discharged to the winding apparatus  9 . 
     Returning to the explanation of  FIG. 7 , a controller  95  with which the winding apparatus  9  is equipped controls the actions of the winding apparatus  9  as a whole through the functions of an unrepresented CPU, RAM, ROM and/or the like. 
     A winder  96  functions as a first winder and winds the first roll paper  3  on which the image-forming apparatus  2   a  printed (developed, transferred and fixed) the first toner image based on the normal color image data  71  around the first winding shaft  91  in order from the beginning edge  77  to the ending edge  78  of the roll paper  3 . For example as shown in  FIG. 9A  and  FIG. 9B , the winder  96 , upon receiving a winding request for the roll paper  3  from the image-forming apparatus  2   a , causes the first winding shaft  91  to rotate and starts winding the roll paper  3  discharged from the image-forming apparatus in order from the beginning edge  77  to the ending edge  78 . 
     When the first winding concludes, the roll paper  3  is in a state wound with the beginning edge  77  on the inside and the ending edge  78  on the outside, and is held on the first winding shaft  91 . From this state, the user anchors the ending edge  78  of the roll paper  3  to the second winding shaft  92  as shown in  FIG. 10A , and prepares for the second winding (re-winding). At this time, for the paper tube mounted on the second winding shaft  92 , it is possible to reuse the paper tube used by the holder  8   a  of the paper supply apparatus  1   a  in the normal color printing system  10   a.    
     When preparation for the second winding concludes, the winder  97  starts re-winding the roll paper  3  by causing the second winding shaft  92  to rotate. That is to say, the winder  97  functions as a second winder, rewinds the roll paper  3  that the winder  96  wound around the winding shaft  91 , and winds the rewound roll paper  3  around the second winding shaft  92  in order from the ending edge  78  to the beginning edge  77  of the roll paper  3 . 
     During winding to the second winding shaft  92 , the first winding shaft  91  follows the roll paper  3  unwound by rotational driving of the second winding shaft  92 , and rotates in the opposite direction (the direction of the arrow in  FIG. 10A ) from the direction during winding to the first winding shaft  91  (the direction of the arrow in  FIG. 9A ). Consequently, the first winding shaft  91  is provided for example with a one-directional clutch, and is comprised so as to rotate in a first direction upon receiving driving power of the motor during the first winding and spins upon receiving torque in the opposite direction from the first direction when receiving driving power of the second winding shaft  92  during the second winding. 
     When the second winding concludes as shown in  FIG. 10B , the roll paper  3  is held on the second winding shaft  92  in a state wound with the beginning edge  77  on the outside and the ending edge  78  on the inside. The beginning edge  77  of the roll paper  3  that has finished winding is temporarily anchored by anchor-tape  74 . 
     When winding by the winding apparatus  9  ends, as shown in  FIG. 11  the user removes the roll paper  3  from the second winding shaft  92  in order to accomplish additional printing with special colors, and mounts the roll paper  3  on the holder  8   b  of the paper supply apparatus  1   b  of the special color printing system  10   b . Furthermore, the user causes the winding apparatus  9  to move and mounts such on the special color printing system  10   b , and prepares for winding of the roll paper  3  to be discharged by the image-forming apparatus  2   b . The roll paper that has finished being wound by the winding apparatus  9  is in a state wound with the beginning edge  77  to the outside and the ending edge  78  on the inside, the same as prior to the start of printing, so mounting on the paper supply apparatus  1   b  of the special color printing system  10   b  in the same direction as the roll paper  3  mounted on the paper supply apparatus  1   a  of the normal color printing system  10   a  is possible. 
     Returning to  FIG. 7 , the composition relating to control of the special color printing system  10   b  is described. The controller  81   b  with which the paper supply apparatus  1   b  is equipped controls the actions of the paper supply apparatus  1   b  as a whole through the functions of an unrepresented CPU, RAM, ROM and/or the like. Specifically, the controller  81   b  functions as an unwinder  82   b , a conveyor  83   b  and a detector  84   b.    
     The unwinder  82   b  functions as a second unwinder, causes the rotation shaft of the holder  8   b  to rotate and unwinds the roll paper  3  attached to the holder  8   b  in order from the beginning edge  77  to the ending edge  78  of the roll paper  3 . The conveyor  83   b  drives the paired conveyor roller  13   b  and the paired feed roller  16   b  and/or the like and successively conveys the roll paper  3  unwound by the unwinder  82   b  to the image-forming apparatus  2   b . Specifically, as shown in  FIG. 12A , the conveyor  83   b  conveys the roll paper  3  on which toner images in the normal colors (the four colors of YMCK) were formed with the beginning edge  77  in the lead. 
     The detector  84   b  functions as a second detector and detects, through the mark sensor  15   b , the original mark  75  recorded on the roll paper  3  unwound by the unwinder  82   b  and conveyed by the conveyor  83   b.    
     The image-forming apparatus  2   b  forms a second toner image through toner of special colors not included in YMCK, based on the special color image data  73  sent from the terminal apparatus  60 . To explain specifically, the image-forming apparatus  2   b  forms two white toner images by means of the two Image-forming parts  21   w   1  and  21   w   2  that form images through white toner, and forms toner images in other special colors by means of the Image-forming parts  21   s   1  and  21   s   2  that form images through other special colors. Furthermore, by superimposing the two white toner images formed and the other special color toner images, a second toner image is formed. Furthermore, the second toner image is formed at the region (surface) in which the first toner image of the roll paper  3  conveyed by the conveyor  83   b  was formed. 
     At this time, the image-forming apparatus  2   b  forms the second toner image on the roll paper with the original mark  75  detected by the detector  84   b  as a position reference so that the region where the second toner image is formed does not shift to the front or back, or to the left or right. As a result, output images of multiple labels that reproduced the image data  70  of the printing target are output to the roll paper  3 , as shown in  FIG. 12B . The roll paper  3  on which the second toner image is formed is fixed by the fuser apparatus  40   b  and discharged to the winding apparatus  9 . 
     In the winding apparatus  9 , the winder  96  winds the roll paper  3  discharged from the image-forming apparatus  2   b  around the first winding shaft  91  in order from the beginning edge  77  to the ending edge  78 . Furthermore, the winder  97  unwinds the roll paper  3  wound around the first winding shaft  91  and winds the roll paper  3  around the second winding shaft  92  in order from the ending edge  78  to the beginning edge  77 . As a result, the roll paper  3  on which the desired multi-color ink printing was done obtains a wound state with the beginning edge  77  on the outside and the ending edge  78  on the inside, the same as prior to the start of printing. 
     The flow of multi-color printing processes in the above kind of printing system  100  is explained with reference to the flowcharts shown in  FIGS. 13-15 . 
     The multi-color printing processes of the printing system  100  start in a state in which the roll paper  3  prior to printing is attached to the paper supply apparatus  1   a  in the normal color printing system  10   a  and the winding apparatus  9  is mounted, that is to say in a state in which printing preparations have concluded. 
     In the terminal apparatus  60 , the controller  61 , upon receiving a print command from the user via the operation unit  63  for example (step S 1 ), starts the process in the flowchart shown in  FIG. 13 . 
     When the print command is received, the controller  61  generates first print data in accordance with the print command and sends the generated first print data to the image-forming apparatus  2   a  of the normal color printing system  10   a  (step S 2 ). The first print data includes image data that should be output with the four colors of YMCK in the image data  70  of the printing target, and print conditions, as in the normal color image data  71  shown in  FIG. 5B  for example. 
     Along with generating and sending the first print data, the controller  61  generates second print data in accordance with the print command and sends the generated second print data to the image-forming apparatus  2   b  of the special color printing system  10   b  (step S 3 ). The second print data includes image data that should be output in special colors other than YMCK in the image data  70  of the printing target, and print conditions, as in the special color image data  73  shown in  FIG. 5C  for example. 
     In the normal color printing system  10   a , the image-forming apparatus  2   a  receives the first print data sent from the terminal apparatus  60  via the LAN communicator  51   a  or the USB communicator  52   a  (step S 11 ). In the special color printing system  10   b , the image-forming apparatus  2   b  receives the second print data sent from the terminal apparatus  60  via the LAN communicator  51   b  or the USB communicator  52   b  (step S 21 ). Subsequent processes are explained with reference to the flowchart shown in  FIG. 14 . 
     In the normal color printing system  10   a , upon receiving the first print data from the terminal apparatus  60 , the image-forming apparatus  2   a  sends a paper supply request to the paper supply apparatus  1   a , sends a winding request to the winding apparatus  9 , and begins unwinding, conveying and winding the roll paper  3  (step S 12 ). In the paper supply apparatus  1   a  that has received the paper supply request, the unwinder  82   a  unwinds the roll paper  3  held by the holder  8   a  in order from the beginning edge  77  to the ending edge  78  and supplies the roll paper  3  to the image-forming apparatus  2   a  via conveyance by the conveyor  83   a.    
     When winding and conveying of the roll paper  3  begins, the detector  84   a  detects the original mark  75  recorded in advance on the roll paper  3  that is conveyed (step S 13 ). Then, the image-forming apparatus  2   a  accomplishes image formation with normal colors (YMCK) on the conveyed roll paper  3  with the position of the detected original mark  75  as a reference (step S 14 ). 
     While forming images in this manner, the image-forming apparatus  2   a  determines whether or not the commanded image formation has finished (step S 15 ). When the commanded image formation has not finished (step S 15 : No), the process returns to step S 13 . That is to say, the normal color printing system  10   a  repeats the processes of steps S 13 -S 14  and continues image formation until the commanded image formation concludes. 
     When the commanded image formation finishes (step S 15 : Yes), the image formation apparatus  2   a  sends a paper supply stop request to the paper supply apparatus  1   a , sends a winding stop request to the winding apparatus  9  and causes unwinding, conveyance and winding of the roll paper  3  to stop (step S 16 ). Then, printing in the normal color printing system  10   a  finishes. 
     The winding process of the winding apparatus  9  is described with reference to the flowchart shown in  FIG. 15 . In the winding apparatus  9 , when a winding request is received from the image-forming apparatus  2   a  (step S 31 ), the winder  96  causes the first winding shaft  91  to rotate and winds the roll paper  3  on which the image-forming apparatus  2   a  accomplished image formation with the first toner in normal colors (YMCK) onto the first winding shaft  91  in order from the beginning edge  77  to the ending edge  78  (step S 32 ). 
     During winding to the first winding shaft  91 , the winder  96  determines whether or not winding has finished (step S 33 ) and until winding finishes (step S 33 : No), successively winds the roll paper  3  discharged from the image-forming apparatus  2   a  around the first winding shaft  91 . When a winding stop request is received from the image-forming apparatus  2   a , the winder  96  halts rotation of the first winding shaft  91  and finishes winding (step S 33 : Yes). 
     When winding to the first winding shaft  91  concludes, the user prepares for the second winding (re-winding) by anchoring the ending edge  78  of the roll paper  3  wound on the first winding shaft  91  to the second winding shaft  92 , as shown in  FIG. 10A . When preparation for re-winding is completed, the user commands re-winding via an unrepresented operation unit with which the winding apparatus  9  is equipped. 
     When a re-winding command is received (step S 34 ), the winder  97  causes the second winding shaft  92  to rotate and winds the roll paper  3  unwound from the first winding shaft  91  to the second winding shaft  92  in order from the ending edge  78  to the beginning edge  77  (step S 35 ). 
     During winding to the second winding shaft  92 , the winder  97  determines whether or not re-winding has finished (step S 36 ), and until re-winding finishes (step S 36 : No), successively winds the roll paper  3  unwound from the first winding shaft  91  around the second winding shaft  92 . When winding of the roll paper  3  to the beginning edge  77  ends, the winder  97  halts rotation of the second winding shaft  92 , and finishes re-winding (step S 36 : Yes). Then, the winding process in the winding apparatus  9  finishes. 
     Returning to the explanation of the flowchart shown in  FIG. 14 , when printing in the normal color printing system  10   a  and winding by the winding apparatus  9  conclude, the roll paper  3  wound by the winding apparatus  9  is removed from the second winding shaft  92  as shown in  FIG. 11  and attached to the paper supply apparatus  1   b  of the special color printing system  10   b . In addition, the winding apparatus  9  is mounted on the special color printing system  10   b . When this kind of printing preparation is completed, the user inputs a command for printing with special colors via an operation panel  54   b  of the image-forming apparatus  2   b , for example, and printing in the special color printing system  10   b  begins. 
     That is to say, during printing by the normal color printing system  10   a  and winding by the winding apparatus  9 , the image-forming apparatus  2   b  that has received the second print data from the terminal apparatus  90  in the special color printing system  10   b  determines whether or not the start of printing has been commanded (step S 22 ), and while the start of printing has not been commanded (step S 22 : No), waits. 
     When the start of printing is commanded (step S 22 : Yes), the image-forming apparatus  2   b  sends a paper supply request to the paper supply apparatus  1   b , sends a winding request to the winding apparatus  9  and starts unwinding, conveying and winding of the roll paper  3  (step S 23 ). In the paper supply apparatus  1   b  that has received the paper supply request, the unwinder  82   b  unwinds the roll paper  3  held on the holder  8   b  in order from the beginning edge  77  to the ending edge  78 , and supplies the roll paper  3  to the image-forming apparatus  2   b  via conveyance by the conveyor  83   b.    
     When winding and conveying of the roll paper  3  begins, the detector  84   b  detects the original mark  75  recorded on the conveyed roll paper  3  (step S 24 ). Then, the image-forming apparatus  2   b  accomplishes image formation with special colors on the conveyed roll paper  3  with the position of the detected original mark  75  as a reference (step S 25 ). In the winding apparatus  9  that has received a winding request, the winder  96  successively winds the roll paper  3  on which images have been formed. 
     During this kind of image formation the image-forming apparatus  2   b  determines whether or not the commanded image formation has finished (step S 26 ), and when the commanded image formation has not finished (step S 26 : No), the process returns to step S 24 . That is to say, the special color printing system repeats the processes of steps S 24 -S 25  and continues image formation until the commanded image formation concludes, 
     When the commanded image formation finishes (step S 26 : Yes), the image-forming apparatus  2   b  sends a paper supply stop request to the paper supply apparatus  1   b , sends a winding stop request to the winding apparatus  9  and stops unwinding, conveying and winding of the roll paper  3  (step S 27 ). Then, printing in the special color printing system  10   b  and the printing system  100  concludes. 
     As described above, the printing system  100  according to the first exemplary embodiment realizes multi-color printing with toner in a maximum of eight colors by successively forming images using the two image-forming apparatuses  2   a  and  2   b  corresponding to four-color color printing. Because printing with other colors of developing agents in addition to the typical four colors of YMCK is possible, it is possible to form white toner images with two layers superimposed by the two Image-forming parts  21   w   1  and  21   w   2  forming images with white toner, for example, and it is possible to obtain a sufficient degree of white color even when a white toner image is formed in a deep base area. In addition, because it is fine to prepare two image-forming apparatuses corresponding to four-color color printing having the same hardware composition, it is not necessary to prepare a large special apparatus corresponding to color printing with five or more colors. 
     In addition, the printing system  100  according to the first exemplary embodiment, after image formation in the first image-forming apparatus  2   a , forms an image with the second image-forming apparatus  2   b  on the roll paper  3  on which fixing by the fuser apparatus  40   a  has already been completed. Consequently, the layer depth of the developing agent to be fixed by the fuser apparatus does not become too thick and it is possible to prevent deterioration of fixing precision. 
     Furthermore, in the winding apparatus  9 , after the first winding shaft  91  has wound the roll paper  3  on which an image was formed by the image-forming apparatus  2   a , the second winding shaft  92  rewinds and again winds the roll paper  3  wound around the first winding shaft  91 . As a result, the two image-forming apparatuses  2   a  and  2   b  both form images on the roll paper  3  unwound in order from the beginning edge  77 , so image formation is possible with the same original mark  75  recorded on the roll paper  3  as a position reference. In addition, in the second image formation, a complex process such as causing the image to reverse up and down or left and right is unnecessary while forming the special color print data  73 , so it is possible to realize multi-color printing using the two image-forming apparatuses  2   a  and  2   b  with a simple composition. 
     Second Exemplary Embodiment 
     Below, a printing system according to a second exemplary embodiment of the present disclosure is described. 
       FIG. 16  shows the composition of a printing system according to the second exemplary embodiment. A printing system  101  comprises an image-forming apparatus  2   a  for forming images using developing agent in the four colors of YMCK, an image-forming apparatus  2   b  for forming images using developing agent in special colors other than YMCK, a paper supply apparatus  1   a  and a winding apparatus  9 . That is to say, the printing system  100  according to the above-described first exemplary embodiment was provided with two paper supply apparatuses  1   a  and  1   b . In contrast, the printing system  101  according to the second exemplary embodiment is not provided with a second paper supply apparatus  1   b.    
     During the first image formation with normal colors (the four colors of YMCK), as shown in  FIG. 16  the image-forming apparatus  2   a  that functions as the first image-forming unit is placed on top of the paper supply apparatus  1   a . Furthermore, the paper supply apparatus  1   a  and the image-forming apparatus  2   a  constitute a system equivalent to the normal color printing system  10   a  in the first exemplary embodiment. 
     On the other hand, during the second image formation with special colors (white, and/or the like), as shown in  FIG. 17  the image-forming apparatus  2   b  that functions as the second image-forming unit is placed on top of the paper supply apparatus  1   a  in place of the image-forming apparatus  2   a . Furthermore, the paper supply apparatus  1   a  and the image-forming apparatus  2   b  constitute a system equivalent to the special color printing system  10   b  in the first exemplary embodiment. 
     That is to say, the paper supply apparatus  1   a  in the second exemplary embodiment functions as both of the two paper supply apparatuses  1   a  and  1   b  in the first exemplary embodiment. For example, the holder  8   a  provided in the paper supply apparatus  1   a  holds the roll paper  3  prior to images being formed by the image-forming apparatus  2   a  functioning as the first image-forming unit, and also functions as a holder that further holds the roll paper  3  after image formation by the image-forming apparatus  2   a  and winding by the winder  97 . The unwinder  82   a  functions as a first unwinder that unwinds the roll paper  3  held by the holder  8   a  and supplies the roll paper  3  to the image-forming apparatus  1   a , and functions as a second unwinder that unwinds the roll paper  3  held by the holder  8   a  and supplies the roll paper  3  to the image-forming apparatus  1   b . The detector  84   a  functions as a first detector and a second detector for detecting the original mark  75  recorded in advance on the roll paper  3 . 
     Through this kind of composition, it is possible for the printing system  101  according to the second exemplary embodiment to execute the same high-quality, multi-color printing with fewer constituent elements than the printing system  100  according to the first exemplary embodiment. 
     Third Exemplary Embodiment 
     Below, a printing system according to a third exemplary embodiment of the present disclosure is described. 
       FIG. 18  shows the composition of a printing system according to a third exemplary embodiment. The printing system  102  comprises an image-forming apparatus  2   a  for forming images using developing agent in the four colors of YMCK, an image-forming unit  20   b  for forming images using developing agent in special colors other than YMCK, an intermediate transfer belt unit  30   b , a paper supply apparatus  1   a  and a winding apparatus  9 . That is to say, the printing system  101  according to the above-described second exemplary embodiment was provided with two image-forming apparatuses  2   a  and  2   b . In contrast, the printing system  102  according to the third exemplary embodiment is not provided with the second image-forming apparatus  2   b.    
     During the first image formation with normal colors (the four colors of YMCK), as shown in  FIG. 18  the image-forming apparatus  2   a  comprising the intermediate transfer belt unit  30   a  and the image-forming unit  20   a  including the Image-forming parts  21   y ,  21   m ,  21   c  and  21   k  for the four colors of YMCK functions as the first image-forming unit. 
     On the other hand, during the second image formation with special colors (white and/or the like), as shown in  FIG. 19  the image-forming unit  20   a  and the intermediate transfer belt unit  30   a  inside the image-forming unit  2   a  are respectively replaced by the image-forming unit  20   b  including Image-forming parts  21   w   1 ,  21   w   2 ,  21   s   1  and  21   s   2  for special colors and the intermediate transfer belt unit  30   b . Furthermore, the image-forming apparatus  2   a  comprising the image-forming unit  20   b  and the intermediate transfer belt unit  30   b  functions as the second image-forming unit. 
     That is to say, with the printing system  102  according to the third exemplary embodiment, one image-forming apparatus  2   a  removably houses constituent elements including image-forming units  21 , and functions as both the first image-forming unit and the second image-forming unit. As a result, it is possible for the printing system  102  according to the third exemplary embodiment to execute the same high-quality, multi-color printing with fewer constituent elements than the printing system  101  according to the second exemplary embodiment. 
     (Variations) 
     The exemplary embodiments of the present disclosure were described above, but the above-described exemplary embodiments are intended to be illustrative and not limiting. That is to say, the exemplary embodiments of the present disclosure have various applications, and all variations should be included within the scope of the present disclosure. 
     For example, in the above-described exemplary embodiments, the image-forming apparatus  1   a  functioning as the first image-forming unit formed images using developing agent in normal colors (the four colors of YMCK) and the image-forming apparatus  1   b  functioning as the second image-forming unit formed images using developing agent in special colors (colors other than YMCK, including white). However, the combinations of colors of developing agent in the first image-forming unit and the second image-forming unit are not limited thereby, as any combination would be fine. 
     In addition, in the above-described exemplary embodiments, an original mark  75  was recorded in advance as a reference mark on the roll paper  3 . However, in the printing system according to the present disclosure, if it is possible to form the first toner image on the roll paper  3  using another positioning reference, it is possible to use roll paper  3  in which the original mark  75  is not recorded. 
     When the original mark  75  is not recorded in advance on the roll paper  3 , in the normal color printing system  10   a  the image-forming apparatus  2   a  records a reference mark when executing the first image formation on the roll paper  3  unwound by the unwinder  82   a . To explain more specifically, the image-forming apparatus  2   a  records a reference mark at constant intervals at multiple positions including near the beginning edge  77  (for example, at the front end of the region where the first developing agent image is formed) of the roll paper  3 . Furthermore, in the succeeding special color printing system  10   b , the detector  84   b  detects the reference mark recorded on the roll paper  3  and the image-forming apparatus  2   b  executes the second image formation with the reference mark as a position reference. Through this, poisoning in second image formation is easy even when no original mark  75  is recorded in advance on the roll paper  3 . 
     In addition, in the above-described exemplary embodiments, the printing systems  100 ,  101  and  102  executed multi-color printing on the roll paper  3 . However, the printing system according to the present disclosure is not limited to a paper medium, that is to say the roll paper  3 , and may execute multi-color printing on a roll-wound recording medium of another material, such as a film recording medium and/or the like. 
     While it is naturally possible to provide a composition for realizing the functions according to the present disclosure as a printing system prepared in advance, it is also possible through application of programs to cause an existing information processing apparatus and/or the like to function as the printing system according to the present disclosure. That is to say, it is possible for a program for realizing the functional composition of the printing systems  100 ,  101  and  102  illustrated by the above-described exemplary embodiments to be executed by a CPU and/or the like controlling an existing information processing apparatus and/or the like and through this to cause the apparatus to function as the printing system according to the present disclosure. In addition, it is possible for the printing method according to the present disclosure to be executed using the printing system. 
     In addition, the method of applying this kind of program is arbitrary. The program can be stored on a computer-readable non-transitory recording medium such as a flexible disk, CD (Compact Disc)-ROM, DVD (Digital Versatile Disc)-ROM, memory card and/or the like. Furthermore, it is possible to overlay the program on carrier waves and to apply such via a communications medium such as the Internet and/or the like. For example, it would be fine to post and distribute the program via a BBS (Bulletin Board System) on a communication network. Furthermore, it would be fine to have a composition such that the above-described processes can be executed by activating this program and similarly executing other application programs under control of the OS (Operating System). 
     Modifications and variations can be made without departing from broader spirit and scope of the present disclosure. It should be noted that the above embodiments are meant only to be illustrative of those embodiments and are not intended to be limiting the scope of the present disclosure. Accordingly, the scope of the present disclosure should not be determined by the embodiments illustrated, but by the appended claims. It is therefore the intention that the present disclosure be interpreted to include various modifications that are made within the scope of the claims and their equivalents.