Abstract:
A liquid ejecting apparatus includes: a sub-tank which stores a certain volume of liquid; a liquid ejecting head which ejects the liquid supplied from the sub-tank; a sheet feeding drum which feeds an ejection target medium to be ejected with the liquid by rotation; a liquid container which stores the liquid to be supplied to the sub-tank; and a supply passage which connects the sub-tank to the liquid container so that the liquid is supplied from the liquid container to the sub-tank. The sheet feeding drum includes a liquid container receiving chamber receiving the liquid container and the liquid container receiving chamber communicates with the supply passage.

Description:
The entire disclosure of Japanese Patent Application No. 2008-047313, filed Feb. 28, 2008, is expressly incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid ejecting apparatus. 
     2. Related Art 
     In recent years, a diameter of nozzles was reduced with higher density of ink jet record. However, when cartridges storing colorant containing ink are mounted on a printer having these nozzles and the printer is not used for a long time, a color material of the ink may sink and cohere in an ink tank. When the color material of the ink sinks or coheres, a problem occurs in that a colorant concentration of the ink to be ejected from the nozzles decreases. Moreover, a problem may also occur in that ink ejection is unstable due to clogging of the sinking and cohering ink. 
     In order to solve these problems, an ink jet printing apparatus disclosed in JP-A-2001-322297 (FIGS. 5, 6, and 7, etc.) is provided with a mixing unit inside an ink tank which stores ink. By allowing the mixing unit to mix the ink stored in the ink tank, the colorant material of the ink is prevented from sinking and cohering. 
     However, in the ink jet printing apparatus disclosed in JP-A-2001-322297, a unit shaking the ink tank is provided outside the ink jet printing apparatus in order to mix the ink stored in the ink tank. Accordingly, a problem may occur in that a mechanism for mixing the ink has to be additionally provided and a space for disposing the mechanism is necessary. 
     SUMMARY 
     An advantage of some aspects of the invention is that it provides a liquid ejecting apparatus capable of ensuring stable ejection of a liquid and saving a space without providing additional motive power. 
     According to an aspect of the invention, there is provided a liquid ejecting apparatus including: a sub-tank which stores a certain volume of liquid; a liquid ejecting head which ejects the liquid supplied from the sub-tank; a sheet feeding drum which feeds an ejection target medium to be ejected with the liquid by rotation; a liquid container which stores the liquid to be supplied to the sub-tank; and a supply passage which connects the sub-tank to the liquid container so that the liquid is supplied from the liquid container to the sub-tank. The sheet feeding drum includes a liquid container receiving chamber receiving the liquid container and the liquid container receiving chamber communicates with the supply passage. 
     With such a configuration, since the liquid container is received inside the sheet feeding drum, it is not necessary to provide an additional space for disposing the liquid container. Therefore, in the liquid ejecting apparatus, a space can be saved. Since the liquid container rotates together with the sheet feeding drum, it is possible to mix the liquid in the liquid container by rotating the sheet feeding drum. In addition, it is possible to mix the liquid in the liquid container by use of the motive power used to rotate the sheet feeding drum. Accordingly, it is not necessary to additionally provide a new motive power source in order to mix the liquid in the liquid container. Moreover, the mixing process can be performed in a sheet feeding process during ejection of the liquid. Accordingly, since the ejection of the liquid is not interrupted to separately perform the mixing process, it is possible to prevent deterioration in throughput. 
     In the liquid ejecting apparatus according to this aspect of the invention, the supply passage may have a tank passage communicating from the inside of the sub-tank to the outside of the sub-tank and a main passage communicating from the liquid container receiving chamber to an outer circumferential surface of the sheet feeding drum, and the tank passage and the main passage are provided to be contacted to each other and detached from each other. 
     With such a configuration, it is possible to supply the liquid by connecting the tank passage to the main passage. Accordingly, it is possible to avoid a problem that the liquid is not smoothly supplied in a case where a supply passage is twisted due to the rotation of the sheet feeding drum. 
     In the liquid ejecting apparatus according to this aspect of the invention, the main passage may be extracted to a non-ejection area, where the liquid ejecting head does not eject the liquid toward the sheet feeding drum, in the sheet feeding drum. With such a configuration, it is possible to supply the liquid from the liquid container to the sub-tank when the liquid ejecting head does not eject the liquid. Accordingly, stable liquid supply from the liquid container to the sub-tank is possible. 
     The liquid ejecting apparatus according to this aspect of the invention may further include: a supply head which is disposed at a location where the main passage is extracted; an ink sucking head which is disposed at a location where the tank passage is extracted; a sheet feeding drum driving unit which rotates the sheet feeding drum in a direction in which the supply head and the ink sucking head are faced with each other; a first pump which sends the liquid stored in the liquid container to the sub-tank; a first pump driving unit which drives the first pump; and an actuator driving unit which moves up and down the supply head. When the liquid ejecting head does not eject the liquid, the supply head and the ink sucking head are faced with each other by rotating the sheet feeding tank by drive of the sheet feeding drum driving unit, the main passage and the tank passage are connected to each other by moving up the supply head by drive of the actuator driving unit and bringing the supply head into contact with the ink sucking head, and the liquid stored in the liquid container is sent to the sub-tank by driving the first pump by drive of the first pump driving unit. 
     With such a configuration, it is possible to ensure a communication state between the sub-tank and the liquid container by a simple process and easily supply the liquid. In addition, since the liquid supply is possible when the liquid ejecting head does not eject the liquid, the liquid can be supplied from the liquid container to the sub-tank in a stable state. 
     The liquid ejecting apparatus according to this aspect of the invention may further include a cap which comes in contact with a plate member of the liquid ejecting head. The cap moves up by drive of the actuator driving unit. In addition, when the main passage is connected to the tank passage, the actuator driving unit simultaneously moves up the cap, so that the cap seals the plate member. With such a configuration, it is possible to cap the plate member when the liquid is supplied from the liquid container to the sub-tank. 
     The liquid ejecting apparatus according to this aspect of the invention may further include: a second pump which applies negative pressure to an airtight space formed when the cap seals the plate member; a second pump driving unit which drives the second pump; a carriage driving unit which reciprocates the liquid ejecting head in a direction perpendicular to a feeding direction of the ejection target medium; and a wiper which comes in contact with the plate member to wipe the liquid attached to the plate member. The actuator driving unit, the second pump driving unit, and the carriage driving unit are controlled by a cleaning controller. In addition, the cleaning controller sends the liquid stored in the liquid container to the sub-tank by driving the first pump, simultaneously applies the negative pressure to the airtight space by allowing the second pump driving unit to drive the second pump, moves up the wiper by driving the actuator driving unit, and moves the liquid ejecting head toward the wiper by driving the carriage driving unit to bring the wiper into contact with the plate member. With such a configuration, it is possible to clean the plate member when the liquid is supplied from the liquid container to the sub-tank. 
     According to the liquid ejecting apparatus according to this aspect of the invention, it is possible to save a space and ensure the stable liquid ejection without providing an additional motive power. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a perspective view illustrating the overall configuration of an ink jet printing apparatus as a liquid ejecting apparatus according to an embodiment of the invention. 
         FIGS. 2A and 2B  are schematic sectional views when the inner structure of a sheet feeding drum and a carriage in  FIG. 1  is viewed from a side of a frame.  FIG. 2A  is a diagram illustrating a configuration before cartridges and a sub-tank are connected and  FIG. 2B  is a diagram illustrating a configuration where the cartridges and the sub-tank are connected to each other. 
         FIG. 3  is a diagram illustrating a control system of the ink jet printing apparatus in detail according to the embodiment of the invention. 
         FIG. 4  is a flowchart illustrating a process performed by an ink supply control unit. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, an ink jet printing apparatus  10  as a liquid ejecting apparatus will be described with reference to the drawings according to an embodiment of the invention. In the following description, in  FIGS. 1 ,  2 A, and  2 B, an arrow X 1  direction and an arrow X 2  direction present a left direction and a right direction, respectively. An arrow Y 1  direction and an arrow Y 2  direction which are perpendicular to the X 1  direction and X 2  direction in a horizontal direction represent a front direction and a rear direction, respectively. An arrow Z 1  direction and an arrow Z 2  direction which are perpendicular an XY plane represent an up direction and a down direction, respectively. 
     Overall Configuration 
       FIG. 1  is a perspective diagram illustrating the overall configuration of the ink jet printing apparatus  10  as the liquid ejecting apparatus.  FIGS. 2A and 2B  are schematic sectional views when the inner structure of a sheet feeding drum  30  and a carriage  20  is viewed from the side of a frame  13 .  FIG. 2A  is a diagram illustrating a configuration before cartridges  40  and a sub-tank  39  are connected and  FIG. 2B  is a diagram illustrating a configuration where the cartridges  40  and the sub-tank  39  are connected to each other. Constituent elements of the liquid ejecting apparatus according to this embodiment are broadly classified into a print head driving system including a print head and various members supporting the drive of the print head and a control system including members that control operations of the print head and the various members. 
     As shown in  FIG. 1 , the ink jet printing apparatus  10  is provided with frames  11 ,  12 , and  13  surrounding three rear, left, and right directions. A driving pulley  14  and a driven pulley  15  are provided at a location on a slight left side from the right end of the frame  11  on a rear side of a case and at a location on a slight right side from the left end of the frame  11 , respectively. An endless belt  16  is suspended on both the pulleys  14  and  15 . On the front side of the case, a guide member  17  is suspended between the left frame  12  and the right frame  13 . A carriage  20  is connected to slide along the guide member  17 . A connection member (not shown) disposed on the rear side of the carriage  20  is fixed between a predetermined location of the endless belt  16 . A rotation shaft of the driving pulley  14  is connected to a shaft of a motor  23  perforated from the rear of the frame  11  to the front thereof. Therefore, when the driving pulley  14  is rotated forward or backward by the motor  23 , the carriage  20  reciprocates in right and left directions along the guide member  17 . 
     The sheet feeding drum  30  is disposed below the carriage  20 . The sheet feeding drum  30  is disposed between the left frame  12  and the right frame  13  and shaft-supported by both the frames  12  and  13  so as to rotate. A rotation driving motor  32  is embedded in the left frame  12  and a rotation shaft  32   a  protrudes from the left frame  12  in the right direction. Gear grooves are formed on the outer circumferential surface of the rotation shaft  32   a . As the rotation driving motor  32 , a stepping motor can be used, for example. The sheet feeding drum  30  can be positioned at a predetermined angle by pulses given to the rotation driving motor  32 . A left end of the sheet feeding drum  30  is configured as a driven portion  34  in which gear grooves are formed on the outer circumferential surface. An intermediate gear  36  is disposed between the rotation shaft  32   a  and the driven portion  34 . The intermediate gear  36  is mounted so as to rotate on the left frame  13 . The gear grooves of the rotation shaft  32   a  and the intermediate gear  36  engage with each other, and the gear grooves of the driven portion  34  and the intermediate gear  36  engage with each other. With such a configuration, when the rotation shaft  32   a  rotates by drive of the driving motor  32 , the motive power is transferred to the driven portion  34  through the intermediate gear  36 . In this way, when the motive power of the driving motor  32  is transferred to the driven portion  34 , the sheet feeding drum  30  rotates. Alternatively, by forming the driven portion  34  so that the diameter is smaller than the outer diameter of the sheet feeding drum  30 , the rotation shaft  32   a  and the driven portion  34  may be connected by plural gear-teeth wheels. 
     A counter roller (not shown) opposed to the sheet feeding drum  30  is disposed above the sheet feeding drum  30 . The counter roller is pressurized toward the sheet feeding drum  30 . When the sheet feeding drum  30  is rotatably driven, the counter roller also rotates. Therefore, a sheet  38  inserted on the sheet feeding drum  30  is interposed between the sheet feeding drum  30  and the counter roller to be fed toward the front side. Ink is ejected on the sheet  38  being fed on the sheet feeding drum  30  from a print head  70  described below to form an image of ink dots. 
     The carriage  20  includes a print head  70  (see  FIG. 3 ) forming an image, a sub-tank  39  temporarily storing ink, an ink sucking head  72  (see  FIGS. 2A and 2B ) sending ink to be received on a side of the sheet feeding drum  30  to the sub-tank  39 . The print head  70  and the ink sucking head  72  are both provided to protrude downward from the carriage  20  (see  FIG. 3 ). The ink sucking head  72  is provided to be adjacent on the right side of the print head  70 , for example. The print head  70  includes a nozzle plate provided with a series of nozzle openings, piezoelectric elements expanded and contracted in accordance with discharge and charge, cavities interposed between the nozzle plate and the piezoelectric elements. The sub-tank  39  has a total of eight ink chambers (not shown) in this embodiment. The ink chambers respectively stores ink of eight colors such as black, cyan, magenta, yellow, gray, light cyan, light magenta, and light gray. As shown in  FIGS. 2A and 2B , the ink sucking head  72  is provided with tank passages  73  communicating with the sub-tank  39 . A total of eight tank passages  73  are provided to communicate with the ink chambers of the sub-tank  39 , respectively, (in  FIGS. 2A and 2B , just three tank passages  73  are illustrated). 
     Cartridges  40  respectively storing the colors described above are disposed inside the sheet feeding drum  30 . In a non-print area on the right side of the sheet feeding drum  30 , the cartridges  40  are detachably mounted in a central direction from eight locations oriented in a circumferential direction of the outer circumference of the sheet feeding drum  30  (see  FIGS. 2A and 2B  and the like). At a location (hereinafter, the location is referred to as “an ink supply position”) on the right side of the cartridges  40  in the sheet feeding drum  30 , there is provided a connection unit  42  which is connected to the carriage  20  when the ink of the cartridges  40  is set to the sub-tank  39 . The connection unit  42  includes a cap  43  sealing the print head  70  and a supply head  44  supplying the ink to the ink sucking head  72 . The supply head  44  is provided to protrude upward from the sheet feeding drum  30  on the right side of the cap  43 . The cap  43  and the supply head  44  are provided to be opposed to the print head  70  and the ink sucking head  72 , respectively, in a state where the carriage  20  is located at the ink supply position. As described below, when the carriage  20  moves up to the ink supply position, the carriage  20  moves downward by a moving mechanism or the like (not shown), so that the cartridges  40  are connected to the sub-tank  39 . Specifically, when the carriage  20  moves up to the ink supply position and then moved downward, the print head  70  is connected to the cap  43  and the ink sucking head  72  is simultaneously connected to the supply head  44 . 
     As shown in  FIGS. 2A and 2B , in the non-print area on the right side of the sheet feeding drum  30 , a total of eight cartridge receiving chambers  47  individually receiving the cartridges  40  are provided in the circumferential direction of the sheet feeding drum  30 . Since the cartridge receiving chambers  47  are present between the center of the sheet feeding drum  30  and the outer circumferential surface, the cartridge receiving chambers  47  are provided at every predetermined pitch in the circumferential direction. An ink supply needle  47   b  protruding in an opening direction is supplied in a bottom portion  47   a  of each of the cartridge receiving chambers  47 . The ink supply needle  47   b  communicates with a central portion  30   a  located at the center of the sheet feeding drum  30 . Main passages  49  allowing the supply of ink to the supply head  44  are formed between the communicating portion and the supply head  44 . A total of eight main passages  49  are formed to allow the ink supply needles  47   b  to communicate with the supply head  44  (in  FIGS. 2A and 2B , just three main passages  49  are illustrated). 
     The cartridges  40  of respective colors received in the sub-tank  39  are received in the cartridge receiving chambers  47 , respectively. As shown in  FIG. 2A , when each of the cartridges  40  is received in the each of the cartridge receiving chambers  47 , an ink supply needle  47   b  is inserted into an ink introduction port  40   a  of each of the cartridges  40 . Accordingly, the ink in each of the cartridges  40  can be supplied to the main passage  49  through the ink supply needle  47   b.    
     As shown in  FIGS. 2A and 2B , the opening end of the supply head  44  is provided with eight nozzle portions  44   a  protruding upward (in  FIGS. 2A and 2B , just three nozzle portions  44   a  are illustrated). In addition, each of the main passages  49  communicates with each of the nozzle portions  44   a . Accordingly, as shown in  FIG. 2B , when the carriage  20  moves downward and the ink sucking head  72  is pushed by the supply head  44 , the nozzle portions  44   a  are inserted into concave portions  72   a  of the ink sucking head  72 . In this way, by inserting the nozzle portions  44   a  into the concave portions  72   a , connection between the ink sucking head  72  and the supply head  44  is make and the main passages  49  communicate with the tank passages  73 . 
     Since a total of eight first electromagnetic valves  51  are provided in the middle of the main passages  49  (in  FIGS. 2A and 2B , just three first electromagnetic valves  51  are illustrating), the first electromagnetic valves  51  respectively open and close the main passages  49 . In addition, a first sucking pump  52  (see  FIG. 3 ) applying negative pressure to the inside of the cartridges  40  is disposed in the central portion  30   a  in which the main passages  49  gather. Since a total of eight second electromagnetic valves  53  are respectively provided in the middle of the main passages  73  (in  FIGS. 2A and 2B , just three second electromagnetic valves  53  are illustrated), each of the second electromagnetic valves  53  open and close each of the tank passages  73 . 
     When the carriage  20  moves up to the ink supply position and the print head  70  and the ink sucking head  72  are connected to the cap  43  and the supply head  44 , respectively, the first electromagnetic valves  51  and the second electromagnetic valves  54  disposed in correspondence with the respective ink to be supplied open valves. In addition, the first sucking pump  52  generates negative pressure in the cartridges  40  disposed in correspondence with the ink to be supplied. Then, the ink is sucked into the cartridges  40  and reaches the supply head  44  through the ink supply needles  47   b  and the main passages  49 , respectively. When the ink sucking head  72  and the supply head  44  are connected to each other, the tank passages  73  and the main passages  49  are in a connection state. Accordingly, the ink reaching the supply head  44  flows from the main passages  49  to the tank passages  73  of the ink sucking head  72  and the sub-tank  39  through the tank passages  73 . 
     When the ink sucking head  72  and the supply head  44  are connected to each other, the print head  70  comes in contact with the cap  43 . In addition, a wiper (not shown) is disposed on the left side of the cap  43 . The cap  43  and the wiper function as performing a cleaning process. In this embodiment, the cleaning process can be performed at the time of ink supply. The cleaning process is performed in the following order. When the carriage  20  moves up to the ink supply position and the carriage  20  moves toward the connection unit  42  by the moving mechanism (not shown), as described above, the print head  70  is opposed to the cap  43 . Then, when the cap  43  moves up by a spring mechanism or the like (not shown), the nozzle plate  74  (see  FIG. 3 ) is sealed by the cap  43 . Subsequently, by operating the second sucking pump  55  (see  FIG. 3 ), negative pressure is applied to an airtight space formed when the nozzle plate  74  is sealed by the cap  43 . In this way, the ink in the cavities of the print head  70  is sucked together with bubbles mixed in the capacities and absorbed by a waste liquid absorber  75  (see  FIG. 3 ). When the ink is completely sucked, the negative pressure is released and the cap  43  is moved down. In addition, by moving up the wiper to the height at which the wiper touches with the nozzle plate  74 , the carriage  20  is moved from the ink supply position in the left direction. At this time, when the wiper wipes the nozzle plate  74 , meniscus of the ink is cleaned. Then, the cleaning process ends. In the wiping, the carriage  20  can be moved from the ink supply position in the left direction, since the connection between the ink sucking head  72  and the supply head  44  are released. 
     Configuration of Control Units 
       FIG. 3  is a diagram illustrating the control system of the ink jet printing apparatus  10  in detail. As shown in  FIG. 3 , the control system of the ink jet printing apparatus  10  includes a first pump driving unit  80  which drives the first sucking pump  52 , a second pump driving unit  81  which drives the second sucking pump  55  mounted separately from the first sucking pump  52 , a sheet feeding drum driving unit  82  which drive the rotation driving motor  32 , a carriage driving unit  83  which drives the motor  23 , a first electromagnetic valve driving unit  84  which opens and closes the valves by driving the first electromagnetic valve  51 , a second electromagnetic valve driving unit  85  which opens and closes the valves by driving the second electromagnetic valve  53 , an actuator driving unit  87  which drives an actuator  86 , a head driving unit  88  which drives the print head  70 , an image print control unit  90 , an ink supply control unit  91 , and a cleaning control unit  92 . These control units may be configured by a hardware logic such as customized ASIC (Application Specific Integrated Circuit) or by a software logic by a CPU, a RAM, and a program executed on the RAM. 
     Functions of the control units will be described in detail. The image print control unit  90  forms an image according to image record data on the sheet  38  by controlling the sheet feeding drum driving unit  82 , the carriage driving unit  83 , and the head driving unit  88 . A process performed by the image print control unit  90  will be described in detail. The image print control unit  90  converts the image record data into raster data, when the image record data generated by a printer drive  94  of a host computer  93  is supplied to the image print control unit  90 . Subsequently, addresses and concentration of pixels constituting the raster data are specified. In addition, a control signal for forming dots to the addresses of the pixels with the concentration is supplied to the carriage driving unit  83  and the head driving unit  88 . 
     The image print control unit  90  calculates an amount of consumption ink on the basis of the raster data generated by the image print control unit  90 . Specifically, whenever the image record data is converted into the raster data, an amount of consumption ink corresponding to one page of the raster data is calculated by counting the on-dot number of the raster data and multiplying the counted on-dot number by an amount of consumption ink per one dot. In addition, the image print control unit  90  supplies a signal indicating the calculated amount of consumption ink to the ink supply control unit  91 . 
     The ink supply control unit  91  is a module which intermittently supplies ink from the cartridges  40  to the sub-tank  39 . A memory of the ink supply control unit  91  has an area for storing remaining ink Vs of the sub-tank  39  and an area for storing remaining ink Vm of each of the cartridges  40 . In addition, the ink supply control unit  91  subtracts the amount of consumption ink from the remaining ink Vs, whenever the signal indicating the amount of consumption ink is supplied from the image print control unit  90 . When the remaining ink Vs is less than a threshold value, a routine of supplying the ink of the cartridges  40  to the sub-tank  39  and subtracting the supply amount from the remaining ink Vm is repeatedly performed by controlling the first pump driving unit  80 , the second pump driving unit  81 , the sheet feeding drum driving unit  82 , the carriage driving unit  83 , the first electromagnetic valve driving unit  84 , the second electromagnetic valve driving unit  85 , and the actuator driving unit  87 . 
     The cleaning control unit  92  is a module which performs the cleaning process. The cleaning control unit  92  simultaneously controls the cleaning process to start, when the ink is supplied by control of the ink supply control unit  91 . The cleaning control unit  92  sequentially supplies the carriage driving unit  83 , the actuator driving unit  87 , and the second pump driving unit  81  with control signals for a series of processes of moving up the cap  43 , applying the negative pressure, releasing the negative pressure state, moving down the cap  43 , moving up the wiper, and moving the carriage  20  to the outside of a home position, which are described above. 
     Process Flow of Ink Supply Control Unit 
     Processes performed by the ink supply control unit  91  are described in detail with reference to  FIG. 4 .  FIG. 4  is a flowchart illustrating the processes performed by the ink supply control unit  91 . A series of processes illustrated in  FIG. 4  are performed, when the signal indicating the amount of consumption ink is supplied from the image print control unit  90  (S 100 : Yes). The ink supply control unit  91  receiving the signal indicating the amount of consumption ink stored in the memory of the ink supply control unit  91  updates the remaining ink Vs into a new value obtained by reducing the remaining ink Vs by the amount of consumption ink indicated by the signal (S 110 ). Subsequently, the ink supply control unit  91  determines whether the updated remaining ink Vs is less than a lower limit value Vsmin (S 120 ). The lower limit value Vsmin of the remaining ink refers to a lower limit value of the capacity of the sub-tank  39  with which ink droplets can be ejected without supply of ink and is set to a value of remaining ink in which bubbles do not enter the cavities of the print head  70 . 
     When the ink supply control unit  91  determines that the remaining ink Vs is not less than the lower limit value Vsmin (S 120 : No), the process returns to S 100  and the ink supply control unit  91  waits a new signal. Alternatively, when the ink supply control unit  91  determines that the remaining ink Vs is less than the lower limit value Vsmin (S 120 : Yes), the ink supply control unit  91  specifies an ink supply amount Vl to be supplied to the sub-tank  39  (S 130 ). The ink supply amount Vl refers to an amount of ink necessary for filling the sub-tank  39  and is calculated from a relation (difference) between the lower limit value Vsmin of the above-described remaining ink and an amount of ink necessary for fully filling the sub-tank  39 . 
     The ink supply control unit  91  specifying the ink supply amount Vl compares the ink supply amount Vl to the remaining ink Vm of the cartridge  40  stored in the memory of the ink supply control unit  91  (S 140 ). That is, in Step S 140 , it is determined whether ink more than the ink supply amount Vl remains in the cartridge  40 . In Step S 140 , when the ink supply control unit  91  determines that the remaining ink Vm is less than the ink supply amount Vl (S 140 : Yes), the ink supply control unit  91  supplies a message prompting exchange of the cartridge  40  to the host computer  93  (S 150 ). 
     Alternatively, when the ink supply control unit  91  determines that the remaining ink Vm is more than the ink supply amount Vl (S 140 : No), the ink supply control unit  91  supplies the sheet feeding drum driving unit  82  with a control signal for rotating the sheet feeding drum  30  so that the supply head  44  and the print head  70  are opposed to each other (S 160 ). The sheet feeding drum driving unit  82  receiving the control signal drives the rotation driving motor  32  to rotate the sheet feeding drum  30  so that the supply head  44  is opposed to the print head  70 . Subsequently, the ink supply control unit  91  supplies a control signal for moving the carriage  20  to the ink supply position to the carriage driving unit  83  (S 170 ). Subsequently, the carriage driving unit  83  moves the carriage  20  up to the ink supply position by driving the motor  23 . 
     Subsequently, the ink supply control unit  91  supplies a control signal for moving up the supply head  44  to the actuator driving unit  87  (S 180 ). The actuator driving unit  87  receiving the control signal moves up the supply head  44 . Then, the ink sucking head  72  and the supply head  44  are connected to each other in an airtight manner. 
     The ink sucking head  72  and the supply head  44  are connected to each other and ink supply control unit  91  supplies the first electromagnetic valve driving unit  84  and the second electromagnetic valve driving unit  85  with a control signal for opening the first electromagnetic valve  51  and the second electromagnetic valve  53  corresponding to each ink (S 190 ). Then, the first electromagnetic valve driving unit  84  and the second electromagnetic valve driving unit  85  open the first electromagnetic valve  51  and the second electromagnetic valve  53 , respectively. In this way, each of the cartridges  40  and the sub-tank  39  communicate with each other. 
     Subsequently, the ink supply control unit  91  supplies a control signal for driving the first sucking pump  52  to the first pump driving unit  80  (S 200 ). Then, the first pump driving unit  80  allows generating the negative pressure in each of the cartridges  40  by driving the first sucking pump  52 . In this way, the ink is supplied from each of the cartridges  40  to the sub-tank  39 . 
     The ink supply control unit  91  waits a predetermined ink supply time. When the predetermined ink supply time elapse (S 210 : Yes), the ink supply control unit  91  stops the drive of the first sucking pump  52  (S 220 ). The predetermined ink supply time refers to time necessary for refilling the sub-tank  39 , where amount of ink is leas than the lower limit value Vsmin, with the ink. The predetermined ink supply time is calculated from the ink supply amount per time unit which is supplied from each of the cartridges  40  to the sub-tank  39 , the lower limit value Vsmin, and the capacity of the sub-tank  39 . 
     Subsequently, the ink supply control unit  91  supplies a control signal for closing the first electromagnetic valve  51  and the second electromagnetic valve  53  to the first electromagnetic valve driving unit  84  and the second electromagnetic valve driving unit  85 , respectively (S 230 ). Then, the first electromagnetic valve driving unit  84  and the second electromagnetic valve driving unit  85  close the first electromagnetic valve  51  and the second electromagnetic valve  53 , respectively. In this way, the communication state between each of the cartridges  40  and the sub-tank  39  is released. 
     Subsequently, the ink supply control unit  91  supplies a control signal for moving down the supply head  44  to the actuator driving unit  87  (S 240 ). Then, the actuator driving unit  87  moves down the supply head  44 . In this way, the connection between the sub-tank  39  and the carriage  20  is released by separating the ink sucking head  72  and the supply head  44  from each other. 
     Subsequently, the ink supply control unit  91  updates the remaining ink Vs stored in the memory of the ink supply control unit  91  into a value such as the capacity of the sub-tank  39  and simultaneously updates the remaining ink Vm into a value obtained by reducing the remaining ink Vm by an amount of ink supplied from each of the cartridges  40  to the sub-tank  39  (S 250 ). Next, the process returns to Step S 100 . That is, the remaining ink Vs is reset to an initial value. Whenever a signal indicating the amount of consumption ink is supplied from the image print control unit  90 , the subsequent processes are repeatedly performed. 
     Advantages of the Invention 
     In the ink jet printing apparatus  10  having the above-described configuration, it is not necessary to provide an additional space for disposing the cartridges  40 , since the cartridges  40  are received inside the sheet feeding drum  30 . Accordingly, it is possible to save a space in the ink jet printing apparatus  10 . 
     In the ink jet printing apparatus  10 , the cartridges  40  rotate together with the sheet feeding drum  30 . Accordingly, by rotating the sheet feeding drum  30 , the ink of the cartridges  40  can be mixed. The ink of the cartridges  40  can be mixed by use of the motive power of the rotation driving motor  32  rotating the sheet feeding drum  30 . Accordingly, it is not necessary to additionally provide a new motive power in order to mix the ink of the cartridges  40 . In addition, since an ink mixing process can be performed in a sheet feeding process, the ink is mixed separately from the printing process. Therefore, since the printing process is not interrupted, it is possible to prevent deterioration in throughput. 
     In the ink jet printing apparatus  10 , the ink is configured to be supplied through the main passages  49  and the tank passages  73  by moving the carriage  20  up to the ink supply position, moving up the supply head  44 , and connecting the ink sucking head  72  of the sub-tank  39  to the supply head  44  of the cartridges  40 . Accordingly, it is possible to stably supply the ink from the cartridges  40  to the sub-tank  39 , compared to a case where the cartridges  40  and the sub-tank  39  are connected to each other through a tube or the like. 
     In the ink jet printing apparatus  10 , supply nozzles are provided in the non-print area of the sheet feeding drum  30 . With such a configuration, the supply of ink from the cartridges  40  to the sub-tank  39  is performed when the ink is not ejected. Accordingly, it is possible to stably supply the ink from the cartridges  40  to the sub-tank  39 . 
     Modified Example of the Invention 
     Hereinafter, the embodiment of the invention has been described. The invention is not limited to the embodiment described above, but may be modified in various forms. 
     In embodiment described above, the cartridges  40  are configured to be mounted in the central direction from the outside of a diameter direction of the sheet feeding drum  30 . However, the configuration in which the cartridges  40  are received is not limited to this configuration. For example, the cartridges  40  may be mounted toward the right surface of the sheet feeding drum  30  from the right side of the sheet feeding drum  30 . 
     In embodiment described above, the eight kinds of cartridge  40  received in the sheet feeding drum  30  are used, but seven kinds of a cartridge may be used, and nine or more kinds of a cartridge may be used. 
     In embodiment described above, the first sucking pump  52  is used in order to send the ink from the cartridges  40  to the sub-tank  39 . However, as a configuration for sending the ink, there may be used the configuration in which the cartridge receiving chambers  47  inside the ink from the cartridges  40  are pressurized and ink packs provided inside the cartridge receiving chambers  47  are compressed, instead of the configuration in which the ink of the cartridges  40  is sucked by the negative pressure. 
     In embodiment described above, the location on the right side of a movable range of the carriage  20  is configured as the ink supply position, but a location on the left side of a movable range of the carriage  20  may be configured as the ink supply position. 
     In embodiment described above, the electromagnetic valves  51  and  53  are provided in both sides of the sub-tank  39  and the cartridges  40 , but may be provided only one of both the sides. 
     In embodiment described above, the ink jet printing apparatus  10  has been described as the liquid ejecting apparatus. The liquid ejecting apparatus is not limited to the ink jet printing apparatus  10 , but may be applied to a copier machine having a copy function, for example. In addition, another example of the liquid ejecting apparatus includes an apparatus which ejects a liquid and is used to manufacture a liquid crystal display, an EL display, and the like. The liquid may not be a liquid other than ink. For example, a color material or an electrode material is used as a liquid in an apparatus which eject a liquid used in a liquid crystal display and an EL display.