Patent Publication Number: US-8991987-B2

Title: Fluid ejecting apparatus and cleaning method

Description:
This application is a divisional of U.S. patent application Ser. No. 13/020,751, filed Feb. 3, 2011, which claims the priority of Japanese Patent Application Nos. 2010-024815, filed Feb. 5, 2010 and 2010-024816, filed Feb. 5, 2010, the entire disclosures of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to fluid ejecting apparatuses and cleaning methods for such fluid ejecting apparatuses. 
     2. Related Art 
     Ink jet printers have been widely known for some time as fluid ejecting apparatuses that eject a fluid onto a medium. Such printers carry out processes for printing onto a medium by ejecting ink (a fluid) from nozzles formed in a fluid ejecting head. 
     In such printers, there have been occurrences of missing dots in printed images, which are caused by attempting to eject ink in a state in which bubbles have entered into a nozzle and the nozzle thus experiences blank ejections. There are printers that execute a cleaning process in which ink is discharged along with the bubbles within the nozzle in order to suppress the occurrence of printing problems caused by missing dots (for example, see JP-A-2007-152725). 
     Such a cleaning process consumes a large amount of ink in order to discharge the bubbles, and thus in JP-A-2007-152725, the amount of ink supplied is changed depending on the severity of the printing problem. Nevertheless, a significant amount of ink is still consumed by this cleaning process, and thus the further reduction of the amount of ink consumed is still an issue. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a fluid ejecting apparatus and a cleaning method capable of discharging bubbles while suppressing the consumption of fluid. 
     A fluid ejecting apparatus according to an aspect of the invention includes: a fluid ejecting head provided with multiple nozzles that eject a fluid; a fluid supply channel that supplies the fluid to the fluid ejecting head; and a pressure application mechanism that causes the fluid to swell from the nozzles by pressurizing the fluid within the fluid supply channel, and then depressurizes the interior of the fluid supply channel while the fluid is swelling from the nozzles. 
     According to this configuration, some of the fluid is caused to swell from the nozzles by the pressure application mechanism pressurizing the fluid within the fluid supply channel, making it possible to push bubbles that have intermixed with the fluid at the swollen area out to the atmospheric side, which is outside of the nozzle openings. The pressure application mechanism depressurizes the interior of the fluid supply channel immediately after the pressurization, which then pulls the fluid that has swollen from the nozzles due to the pressurization back into the fluid ejecting head, so that the fluid is not wastefully consumed by falling from the nozzle openings or the like. Accordingly, the bubbles can be discharged while suppressing the consumption of fluid. 
     In the fluid ejecting apparatus according to another aspect of the invention, a depressurizing time for which the pressure application mechanism carries out the depressurization is longer than a pressurizing time for which the pressure application mechanism carries out the pressurization. 
     According to this configuration, by pressurizing for a short amount of time so as to ensure the bubble discharge properties while also making the depressurizing time longer than the pressurizing time, it is possible to suppress bubbles from being sucked in through the nozzle openings. 
     In the fluid ejecting apparatus according to another aspect of the invention, the pressure application mechanism carries out the pressurization by causing the volume of the fluid supply channel to decrease, and carries out the depressurization by causing the volume of the fluid supply channel to increase. 
     According to this configuration, by the pressure application mechanism reducing the volume of the fluid supply channel, an amount of fluid equivalent to the reduced volume is pushed out, thus making it possible to transmit the pressure toward the nozzles side. Because depressurization is carried out by increasing the volume of the fluid supply channel, the depressurization can be carried out immediately after the pressurization by returning the volume, which has been reduced for pressurization, to its original state. 
     In the fluid ejecting apparatus according to another aspect of the invention, the volume of the fluid supply channel caused to increase by the pressure application mechanism for the depressurization is less than the volume of the fluid supply channel caused to decrease by the pressure application mechanism for the pressurization. 
     According to this configuration, when bubbles are discharged from the nozzles through pressurization, an equivalent air gap is produced within the nozzles; however, the volume of the fluid supply channel increased for depressurization is lower than the volume of the fluid supply channel reduced for pressurization, making it possible to suppress the occurrence of empty nozzles caused by the air gaps. 
     In a fluid ejecting apparatus according to another aspect of the invention, multiple fluid ejecting heads are provided, and the apparatus further includes a fluid holding chamber that holds the fluid supplied via the fluid supply channel and supplies the held fluid to the multiple fluid ejecting heads. 
     According to this configuration, the meniscuses of the nozzles can be unified by adjusting the backpressure of the nozzles in the fluid holding chamber. The pressure application mechanism is provided upstream from the fluid holding chamber in the fluid flow channel, and thus increasing the number of fluid ejecting heads does not complicate the configuration. 
     In the fluid ejecting apparatus according to another aspect of the invention, the pressurizing time for which the pressure application mechanism carries out the pressurization is between 0.025 seconds and 0.5 seconds. 
     According to this configuration, the pressurizing time for which the pressure application mechanism carries out pressurization is between 0.025 and 0.5 seconds, and is thus extremely short; accordingly, it is possible to dislodge bubbles that have adhered to the inner walls of the nozzles and discharge those bubbles. 
     A cleaning method according to another aspect of the invention is a cleaning method for a fluid ejecting apparatus, the apparatus including a fluid ejecting head provided with multiple nozzles that eject a fluid and a fluid supply channel that supplies the fluid to the fluid ejecting head, and the method including: pressurizing the fluid to swell from the nozzles by pressurizing the fluid within the fluid supply channel; and after the pressurization, depressurizing the interior of the fluid supply channel while the fluid is swelling from the nozzles. 
     According to this configuration, the same effects as those of the aforementioned fluid ejecting apparatus can be achieved. 
     A fluid ejecting apparatus according to another aspect of the invention includes: a fluid ejecting head provided with multiple nozzles that eject a fluid; a fluid supply channel that supplies the fluid to the fluid ejecting head; an on-off valve provided in the fluid supply channel; and a pressure application mechanism that pressurizes the fluid to swell from the nozzles by pressurizing the fluid within the fluid supply channel downstream from the closed on-off valve. 
     According to this configuration, some of the fluid is pressurized to swell from the nozzles by the pressure application mechanism pressurizing the fluid within the fluid supply channel, making it possible to push bubbles that have intermixed with the fluid at the swollen area out to the atmospheric side, which is outside of the nozzle openings. Because the on-off valve is closed at this time, fluid is not supplied to nozzles from the fluid supply channel that is upstream therefrom. Accordingly, bubbles can be discharged from the nozzles while suppressing the consumption of fluid. 
     In the fluid ejecting apparatus according to another aspect of the invention, the pressure application mechanism depressurizes the interior of the fluid supply channel in a state in which the on-off valve is closed and the fluid is swelling from the nozzles due to the pressurization. 
     According to this configuration, because the pressure application mechanism depressurizes the interior of the fluid supply channel after pressurization while maintaining the closed state of the on-off valve, fluid that is swelling from the nozzles can be pulled back into the fluid ejecting head without being consumed wastefully due to dripping down from the nozzle openings and so on. Accordingly, the meniscuses of the nozzles can be suppressed from breaking, and the consumption of fluid can be suppressed as well. The pressure can be increased by the amount of fluid that is pulled back due to the depressurization, thus making it possible to improve the bubble discharge properties. 
     In a fluid ejecting apparatus according to another aspect of the invention, multiple fluid supply channels are provided and the same number of pressure application mechanisms as the fluid supply channels is provided. 
     According to this configuration, multiple pressure application mechanisms are provided in accordance with the number of fluid supply channels that are installed, thus making it possible to discharge bubbles for each of the fluid supply channels. 
     A cleaning method according to another aspect of the invention is a cleaning method for a fluid ejecting apparatus, the apparatus including a fluid ejecting head provided with multiple nozzles that eject a fluid, a fluid supply channel that supplies the fluid to the fluid ejecting head, and an on-off valve provided in the fluid supply channel, and the method including: closing the on-off valve; and after closing the on-off valve, pressurizing the fluid to swell from the nozzles by pressurizing the fluid within the fluid supply channel downstream from the on-off valve. 
     According to this configuration, the same effects as those of the aforementioned fluid ejecting apparatus can be achieved. 
    
    
     
       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 schematic front view illustrating the overall configuration of an ink jet printer according to a first embodiment. 
         FIG. 2  is a bottom view illustrating the configuration of a line head. 
         FIG. 3  is a cross-sectional view illustrating the overall configuration of the interior of a fluid ejecting head. 
         FIG. 4  is a cross-sectional view illustrating the overall configuration of a capping mechanism. 
         FIG. 5  is a cross-sectional view illustrating the overall configuration of a wiping unit. 
         FIGS. 6A and 6B  are cross-sectional views illustrating the configuration and effects of a pressure application mechanism, where  FIG. 6A  illustrates a state prior to pressurization and  FIG. 6B  illustrates a state during pressurization. 
         FIGS. 7A ,  7 B,  7 C, and  7 D are cross-sectional views illustrating non-ink-supply cleaning, where  FIG. 7A  illustrates a state prior to pressurization,  FIG. 7B  illustrates a state during pressurization,  FIG. 7C  illustrates a state during depressurization, and  FIG. 7D  illustrates a state when the apparatus is at rest. 
         FIG. 8  is a graph illustrating a relationship between pressurizing time and depressurizing time. 
         FIG. 9  is a chart illustrating a flow channel condition 1 in an ink jet printer according to the first embodiment. 
         FIG. 10A  is a chart illustrating a pressurized ink amount range under the flow channel condition 1, and  FIG. 10B  is a chart illustrating pressurizing time and depressurizing time ranges under the flow channel condition 1. 
         FIG. 11  is a schematic front view illustrating the overall configuration of an ink jet printer according to a second embodiment. 
         FIGS. 12A and 12B  are cross-sectional views illustrating the configuration and effects of a differential pressure regulating valve, where  FIG. 12A  illustrates a closed state and  FIG. 12B  illustrates an open state. 
         FIG. 13A  is a chart illustrating a pressurized ink amount range under a flow channel condition 2 in an ink jet printer according to the second embodiment, and  FIG. 13B  is a chart illustrating pressurizing time and depressurizing time ranges under the flow channel condition 2. 
         FIG. 14  is a cross-sectional view illustrating a variation on the configuration of a pressure application mechanism. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First Embodiment 
     Hereinafter, a first embodiment, in which the invention is embodied as an ink jet printer (called simply a “printer” hereinafter) serving as a type of fluid ejecting apparatus, will be described with reference to  FIGS. 1 through 10 . Note that the terms “depth direction”, “horizontal direction”, and “vertical direction” as used in the descriptions hereinafter refer respectively to the depth direction, horizontal direction, and vertical direction indicated by the arrows in the drawings. 
     As shown in  FIG. 1 , a printer  11  includes a transport unit  12  that transports paper P serving as a medium, a line head  13  that executes a printing process on the paper P, an ink supply unit  14  that supplies ink serving as a fluid to the line head  13 , and a maintenance unit  15 . 
     The transport unit  12  includes a pair of paper feed rollers  16 , an endless transport belt  17 , a driving roller  18 , a slave roller  19 , a driving motor  20  connected to the driving roller  18 , and a pair of discharge rollers  21 . The transport belt  17  is wrapped upon the driving roller  18  and the slave roller  19 , and moves cyclically when the driving roller  18  rotates in the clockwise direction in  FIG. 1  due to the driving of the driving motor  20 . The paper feed rollers  16 , transport belt  17 , and discharge rollers  21  transport the paper P along a transport direction X. Multiple transport belts  17  (for example, two) are provided so as to support at least both ends of the paper P in a width direction Y (the depth direction), and the maintenance unit  15  is disposed between the transport belts  17  that are arranged in the depth direction. 
     The line head  13  includes a base unit  23  and fluid ejecting heads  24  supported by the base unit  23 . As shown in  FIG. 2 , the fluid ejecting heads  24  are arranged in a staggered pattern so as to form two rows of lines that extend along the width direction Y of the paper P. The first row, located upstream in the transport direction X (that is, on the left side), is configured of four fluid ejecting heads  24  arranged along the width direction Y, whereas the second row, located downstream in the transport direction X (that is, on the right side), is configured of four fluid ejecting heads  24  arranged along the width direction Y. 
     Each fluid ejecting head  24  is provided with multiple nozzles  25  for ejecting ink. Two nozzle rows N that extend along the width direction Y are formed in a nozzle formation surface  24   a , located on the bottom surface (base surface) of the fluid ejecting head  24 , by nozzle openings  25   a  of the multiple nozzles  25 . As shown in the enlarged area of  FIG. 2 , the nozzle openings  25   a  are disposed in a staggered manner so that the intervals at which the two nozzle rows N are disposed along the width direction Y are shifted by ½ pixel. The first and second rows of fluid ejecting heads  24  are arranged so that, when projected in the transport direction X, at least one nozzle  25  at the respective ends of the rows overlap, or so that the nozzles  25  at the respective ends of the rows are continuous with a space equivalent to the nozzle pitch provided therebetween. 
     Accordingly, the printer  11  is capable of printing across the maximum paper width range even with the line head  13  remaining in a fixed state. In this embodiment, a single fluid ejecting head  24  corresponds to 1.1 inches of paper, and thus eight fluid ejecting heads  24  cover the horizontal width of A4 (297 mm×210 mm) paper (that is, approximately 8.3 inches). A single nozzle row N is configured of 330 nozzles  25 . Accordingly, a single line head  13  has 8 (the number of fluid ejecting heads  24  in the width direction Y)×2 (the number of nozzle rows N)×330 (the number of nozzles  25  of which each nozzle row N is configured), or 5,280 nozzles  25 . 
     In the case where four-color printing using, for example, cyan (C), magenta (M), yellow (Y), and black (K) is to be carried out, one pair of the line heads  13  and the ink supply unit  14  is provided for each of the colors (however, for the sake of simplicity,  FIGS. 1 and 2  show only one of each). A printing process can be carried out at a resolution of 600 dpi by superimposing ink droplets of the four colors from the four line heads  13  onto the transported paper P. 
     As shown in  FIG. 1 , the ink supply unit  14  includes an ink cartridge  26  that holds ink, an ink supply tube  27  that configures a fluid supply channel for supplying the ink from the ink cartridge  26  to the fluid ejecting head  24 , and a pressure pump  28  that pressure-transfers the ink. The ink cartridge  26  is mounted in a cartridge holder (not shown) in a removable state and is connected to the ink supply tube  27 . A pressure application mechanism  29  is provided partway along the ink supply tube  27 . 
     A common ink chamber  30 , which temporarily holds the ink supplied from the ink cartridge  26  via the ink supply tube  27 , is provided in the base unit  23  of the line head  13 . Multiple branch channels  31 , corresponding to respective fluid ejecting heads  24 , are connected to the common ink chamber  30 . The ink held within the common ink chamber  30  is supplied to multiple fluid ejecting heads  24  via the branch channels  31 . 
     As shown in  FIG. 3 , each fluid ejecting head  24  includes a flow channel formation member  32 , a vibrating plate  33 , a flow channel formation member  34 , and a nozzle plate  35 , all stacked in the vertical direction. The branch channel  31  that communicates with the common ink chamber  30 , a reservoir  36 , and a holding chamber  37  are formed in the flow channel formation member  32 . A communication hole  38  is provided in the vibrating plate  33  in a location that corresponds with the reservoir  36 . A cavity  39  that communicates with the reservoir  36  via the communication hole  38  is formed in the flow channel formation member  34 . 
     A piezoelectric element  40  is provided on the upper surface side of the vibrating plate  33  in a location that is above the cavity  39 . The nozzle  25 , which communicates with the cavity  39 , is formed in the nozzle plate  35 . In other words, the ink distributed to the fluid ejecting heads  24  from the common ink chamber  30  through the branch channels  31  is held in the reservoir  36 , and is then supplied to the nozzles  25  from the reservoir  36  via the communication hole  38  and the cavity  39 . 
     The vibrating plate  33  is provided so as to be capable of vibrating vertically. The vibrating plate  33  is caused to vibrate vertically by the piezoelectric element  40  extending/shrinking due to the application of a driving signal thereto. When the vibrating plate  33  vibrates vertically, the volume of the cavity  39  expands/shrinks. When the volume of the cavity  39  shrinks, the ink within the cavity  39  is ejected from the nozzle  25  as an ink droplet Fb. The nozzle formation surface  24   a  of the fluid ejecting head  24  is configured of the bottom surface (base surface) of the nozzle plate  35 . In this embodiment, the diameter of each nozzle opening  25   a  is approximately 20 micrometers, and the thickness of the nozzle plate  35  in the vertical direction is approximately 100 micrometers. 
     Here, the ink cartridge  26  is provided in a position that is lower than the line head  13 . Accordingly, the region within the fluid ejecting head  24  (the ink flow channel) has a negative pressure of approximately −1 kPa due to head differential. This negative pressure is for suppressing the ink from dripping down from the nozzle  25  and for stabilizing ejection operations by forming a concave-shaped meniscus within the nozzle  25 . 
     Next, the maintenance unit  15  will be described. 
     The maintenance unit  15  includes a capping unit  41  for capping the nozzle formation surface  24   a  of the fluid ejecting head  24  (see  FIG. 4 ) and a wiping unit  42  for wiping the nozzle formation surface  24   a  (see  FIG. 5 ). The capping unit  41  and wiping unit  42  may be provided for each fluid ejecting head  24 , or the multiple fluid ejecting heads  24  may be capped and wiped at the same time. 
     In addition to being used for capping that prevents the nozzles  25  from drying, the capping unit  41  is used when executing suction cleaning, in which ink within the ink cartridge  26  is sucked from the nozzles  25 , thus discharging bubbles, thickened ink, and so on from the nozzles  25 . Furthermore, the capping unit  41  is also used for catching ink discharged from the nozzles  25  during pressure cleaning, in which ink within the ink cartridge  26  is discharged from the nozzles  25  by the pressure pump  28 . Meanwhile, the wiping unit  42  is used when wiping the nozzle formation surface  24   a  in order to remove objects stuck thereto, such as paper dust, ink, or the like, and when executing wiping for unifying the meniscuses of the nozzles  25 . 
     First, the capping unit  41  will be described. 
     As shown in  FIG. 4 , the capping unit  41  includes a closed-end square box-shaped cap  43 , a raising/lowering mechanism  44  that raises/lowers the cap  43 , and a suction mechanism  45 . A square frame-shaped sealing member  46 , configured of a flexible material, is provided on the entirety of the top surfaces of the circumferential walls of the cap  43 , whereas a discharge pipe  47  is provided protruding downward from the base wall of the cap  43 . 
     One end of a discharge tube  48 , which is composed of a flexible material and partially configures the suction mechanism  45 , is connected to the discharge pipe  47 . The other end of the discharge tube  48  is inserted into a waste ink tank  49 . The waste ink tank  49  contains a waste ink absorption member  50  that is composed of a porous member. 
     A tube pump  51  of which the suction mechanism  45  is partially configured is disposed between the cap  43  and the waste ink tank  49 . The tube pump  51  includes a cylindrical case  52 , a pump wheel  53  that is circular when viewed from above, a wheel shaft  54 , and a pair of pressure rollers  55 . The pump wheel  53  is housed within the case  52  so as to be capable of rotation central to the wheel shaft  54 , which in turn is provided central to the axis of the case  52 . The middle portion of the discharge tube  48  is housed within the case  52  so as to follow the inner circumference of the walls of the case  52 . 
     A pair of roller guidance grooves  56  having arc shapes are formed in the pump wheel  53  so as to oppose each other with the wheel shaft  54  therebetween. Each of the roller guidance grooves  56  has one end positioned on the inner side of the circumference of the pump wheel  53  and the other end positioned on the outer side of the circumference of the pump wheel  53 . In other words, the roller guidance grooves  56  extend so as to gradually become further from the wheel shaft  54  as the groove progresses from one end to the other end. The pair of pressure rollers  55  are insertedly supported in the roller guidance grooves  56  via rotational shafts  57 . Both rotational shafts  57  are capable of sliding freely within their respective roller guidance grooves  56 . 
     When the pump wheel  53  rotates in the forward direction (the clockwise direction, indicated by the arrow in  FIG. 4 ), the pressure rollers  55  in the outbound direction move to the other end of the roller guidance grooves  56  (that is, toward the outer circumferential side of the pump wheel  53 ), continuously pressing down the middle portion of the discharge tube  48  from the upstream side to the downstream side while rotating. Due to this rotation, the interior of the discharge tube  48  that is upstream from the tube pump  51  is depressurized. 
     However, when the pump wheel  53  rotates in the backward direction (that is, the counter-clockwise direction in  FIG. 4 ), the pressure rollers  55  return in the inbound direction to the one end of the roller guidance grooves  56  (that is, toward the inner circumferential side of the pump wheel  53 ). Due to this movement, the pressure rollers  55  make light contact with the middle portion of the discharge tube  48 , thus canceling the depressurized state of the interior of the discharge tube  48 . 
     The raising/lowering mechanism  44  includes a cam member  58  that makes contact with the cap  43  from below, a motor  59  for rotating the cam member  58 , and a driving force transmission mechanism  60 . When the motor  59  is driven in the forward direction, the cam member  58  is rotated via the driving force transmission mechanism  60 , and the cap  43  makes contact with the nozzle formation surface  24   a.    
     Accordingly, when the pump wheel  53  is driven in the forward direction while the cap  43  is in contact with the nozzle formation surface  24   a , negative pressure arises in a space R formed between the cap  43  and the nozzle formation surface  24   a . Through this, suction cleaning, in which ink is discharged from the nozzles  25 , is executed. The negative pressure in the space R is canceled when the pump wheel  53  is rotated in the backward direction. Thereafter, when the motor  59  of the raising/lowering mechanism  44  is driven in the backward direction, the cap  43  drops, thus removing the cap  43  from the transport path of the paper P. 
     Next, the wiping unit  42  will be described. 
     As shown in  FIG. 5 , the wiping unit  42  includes a wiping mechanism  61  and a raising/lowering mechanism  62  that raises/lowers the wiping mechanism  61 . 
     The wiping mechanism  61  includes a holder  63 , a lead screw  64  erected in the holder  63  so as to extend along the depth direction, a motor  65  for rotating the lead screw  64 , a support member  66 , and a plate-shaped wiper  67  configured of an elastic material such as rubber. The wiper  67  is supported by the support member  66  so as to be erect thereabove, and the support member  66  is supported by the lead screw  64 . A holding cavity  66   a  is formed in the upper surface side of the support member  66 . 
     The raising/lowering mechanism  62  includes a cam member  68  that makes contact with the holder  63  of the wiping mechanism  61  from below, a motor  69  for rotating the cam member  68 , and a driving force transmission mechanism  70 . When the motor  69  is driven in the forward direction, the cam member  68  is rotated via the driving force transmission mechanism  70 , and the wiping mechanism  61  rises to a position in which the wiper  67  makes contact with the nozzle formation surface  24   a.    
     When the motor  65  is driven in the forward direction and the lead screw  64  rotates in the forward direction, the wiper  67  slides along the nozzle formation surface  24   a  while moving along the depth direction with the support member  66 . Wiping, in which the nozzle formation surface  24   a  is wiped clean, is executed in this manner. At this time, ink, paper dust, and so on wiped off from the nozzle formation surface  24   a  fall along the wiper  67  and are held in the holding cavity  66   a.    
     Next, the pressure application mechanism  29  will be described. 
     As shown in  FIGS. 6A and 6B , the pressure application mechanism  29  includes a flow channel formation member  71  of a fixed shape. A connection portion  72  is provided on the left end of the flow channel formation member  71 , connecting to the ink supply tube  27  on the upstream side, whereas a connection portion  73  is provided on the right side of the flow channel formation member  71 , connecting to the ink supply tube  27  on the downstream side. A recessed portion  71   a , which is circular in shape when viewed from above, is formed in the upper surface side of the flow channel formation member  71 . An inflow channel  72   a  that allows the ink supply tube  27  on the upstream side to communicate with the recessed portion  71   a  is formed in the connection portion  72 . Meanwhile, an outflow channel  73   a  that allows the ink supply tube  27  on the downstream side to communicate with the recessed portion  71   a  is formed in the connection portion  73 . 
     A flexible film member  74  is affixed on the upper surface side of the flow channel formation member  71  in a flexible state so as to seal the opening of the recessed portion  71   a . Meanwhile, a disk-shaped depression plate  74   a  whose surface area is smaller than the area of the opening of the recessed portion  71   a  is affixed approximately in the center of the outer surface side of the film member  74 . A pressure chamber  75  is enclosed and formed by the film member  74  and the recessed portion  71   a . The pressure chamber  75  configures part of the fluid supply channel by communicating with the ink supply tube  27  through the inflow channel  72   a  and the outflow channel  73   a.    
     A biasing member  76  that biases the film member  74  in a direction that expands the interior volume of the pressure chamber  75  is disposed within the pressure chamber  75 . The biasing member  76  can be configured from, for example, a coil spring, a plate spring, or the like. A cam member  77  that makes contact with the depression plate  74   a  is disposed above the depression plate  74   a . The cam member  77  is supported by a rotational shaft  78 , and rotates along with the rotational shaft  78  in accordance with the driving of a motor  79 . 
     Accordingly, when the motor  79  is driven in the forward direction in the state shown in  FIG. 6A , the cam member  77  rotates in the counter-clockwise direction in  FIG. 6A  against the biasing force of the biasing member  76 . As a result, as shown in  FIG. 6B , the film member  74  displaces in a direction that reduces the interior volume of the pressure chamber  75 , and the ink within the ink supply tube  27  is pressurized by the ink pushed out from the pressure chamber  75 . When the motor  79  is then driven in the backward direction in the state shown in  FIG. 6B , the cam member  77  rotates in the clockwise direction in  FIG. 6B . As a result, the film member  74  displaces in a direction that increases the interior volume of the pressure chamber  75  due to the biasing force of the biasing member  76 , and the interior of the ink supply tube  27  is depressurized by the ink being sucked into the pressure chamber  75 . 
     Next, maintenance operations in the printer  11  will be described. 
     In the printer  11 , missing dots occur when bubbles infiltrate the ink supply tube  27  when the ink cartridge  26  is replaced, and the nozzles  25  become clogged due to ink thickening when the printer  11  is left standing with the power turned off. In order to suppress a drop in printing quality caused by such missing dots and clogs, the printer  11  executes suction cleaning, pressure cleaning, and so on using the capping unit  41 . Hereinafter, cleaning in which ink is discharged from the nozzles  25  while supplying ink from the ink cartridge  26  will be referred to as “ink supply cleaning”. 
     In the case where paper dust and so on has stuck to the nozzle formation surface  24   a  due to the printing process, the nozzle formation surface  24   a  is wiped using the wiping unit  42 . Because discharged ink sticks to the nozzle formation surface  24   a , convex meniscuses are formed in the nozzle openings  25   a , and so on after ink supply cleaning, this wiping is carried out immediately after ink supply cleaning. 
     However, when such wiping is carried out, there are situations where the wiper  67  pushes air into the nozzles  25  and fine bubbles are produced in the nozzles  25 . These bubbles are much smaller compared to the bubbles that infiltrate when replacing the ink cartridge  26  and so on, and thus these bubbles often accumulate in the vicinity of the nozzles  25 . Accordingly, the printer  11  executes non-ink-supply cleaning using the pressure application mechanism  29  in order to discharge the fine bubbles in the vicinity of the nozzles  25 . 
     Next, the non-ink-supply cleaning performed by the pressure application mechanism  29  will be described in detail. 
     The non-ink-supply cleaning is configured of a pressurizing step, in which the pressure application mechanism  29  pressurizes the ink in the ink supply tube  27  and causes ink to swell from the nozzles  25 , and a depressurizing step, carried out after the pressurizing step, in which the pressure application mechanism  29  depressurizes the interior of the ink supply tube  27  while the ink is swelling from the nozzles  25 . In other words, in the pressurizing step, the pressure application mechanism  29  propagates pressure to within the nozzles  25  by expelling ink from the pressure chamber  75  all at once, thus dislodging bubbles that have stuck to the inner walls of the nozzles  25 , as shown in  FIG. 7A . As shown in  FIG. 7B , causing the ink to swell from the nozzles  25  pushes the bubbles toward the atmosphere side, which is the outside of the nozzle openings  25   a.    
     In the depressurizing step, the pressure application mechanism  29  causes the volume of the pressure chamber  75  to increase, thus pulling the volume of ink that has been pushed out back into the pressure chamber  75 . Through this, the ink that has swelled out in a convex shape from the nozzles  25  is collected back into the nozzles  25 , as shown in  FIG. 7C , before the ink droplets Fb are ejected, fall (drip), or the like from the nozzles  25 . When the bubbles are discharged, an air gap equivalent to the volume of the bubbles arises in the nozzles  25 , but the ink within the common ink chamber  30  feeds into the nozzles  25  as shown in  FIG. 7D  due to capillarity if the printer  11  is left standing for a short amount of time. 
     By executing this pressurizing and depressurizing in the non-ink-supply cleaning multiple times in repetition, even bubbles that are difficult to be discharged can be gradually moved to the outside. For example, in the case where the pressurizing and depressurizing are repeated multiple times, bubbles present in the fluid ejecting head  24 , the common ink chamber  30 , and so on can also be discharged, in addition to the bubbles within the nozzles  25 . Furthermore, even in the case where an air gap has been produced in the nozzles  25  due to the discharge of bubbles, the positions of the liquid surfaces of the nozzles  25  are gradually unified by repeating the pressurizing and the depressurizing. 
     In the depressurizing step, the volume that was reduced in the pressurizing step may be restored to its original volume, or the volume increased for the depressurizing may be smaller than a volume that has been reduced for the pressurizing. For example, in the case where comparatively large bubbles present within the common ink chamber  30  have been discharged by repeating the pressurizing and the depressurizing multiple times, there is also the risk of empty nozzles arising, in which the entire nozzle  25  is taken up by an air gap. When an empty nozzle has arisen in this manner, there are cases where it is difficult for the ink to fill through capillarity, and thus it is preferable to reduce the amount of ink that is sucked in, particularly during the final depressurization after pressurization and depressurization have been repeated multiple times. 
     Here, as shown in  FIG. 8 , it is preferable for a depressurizing time Td for which depressurizing is carried out during the depressurizing step to be set longer than a pressurizing time Ta for which pressurizing is carried out during the pressurizing step. If the pressurizing time Ta is too short, there is a risk of the ink droplets Fb being ejected due to the propagated pressure and ink being wastefully consumed, the depressurizing starting too early and causing the ink to be sucked back before the bubbles have been pushed out, and so on. Conversely, if the pressurizing time Ta is too long, there is a risk of the ink flow speed slowing and the bubbles not being dislodged from the inner walls of the nozzles  25 , the ink not being pulled back in a timely manner by the depressurizing and the ink being consumed, and so on. 
     On the other hand, if the depressurizing time Td is too long, there is a risk of the ink not being pulled back in a timely manner and the ink being consumed. Conversely, if the depressurizing time Td is too short, there is a risk of air being sucked in from outside of the nozzles  25 , producing bubbles. 
     A proper pressurizing time Ta for suppressing the ejection of ink droplets Fb and ensuring the discharge properties for bubbles is an extremely short amount of time, such as 0.05 to 0.5 seconds. On the other hand, carrying out depressurization in such a short amount of time will suck air in, and thus with a pressurizing time Ta from 0.05 to 0.5 seconds, it is preferable for the pressurizing time Ta to be less than the depressurizing time Td. 
     In this embodiment, the pressurization and depressurization are executed by causing the volume of the pressure chamber  75  to fluctuate to a degree at which ink droplets Fb are not ejected from the nozzles  25 . Accordingly, the appropriate values for the amount of ink pushed out due to the volume fluctuation caused by the pressurization (called a “pressurized ink amount Vd” hereinafter), the pressurizing time Ta, and the depressurizing time Td fluctuate depending on flow channel conditions, such as the number of nozzles  25 , fluid ejecting heads  24 , and so on that are installed. A range of appropriate values for the pressurized ink amount Vd, the pressurizing time Ta, and the depressurizing time Td, as well as the flow channel conditions, will be described next. 
     As shown in  FIG. 9 , the following can be given as an example of flow channel conditions of the printer  11  according to this embodiment (called “flow channel condition 1” hereinafter): an interior volume of the ink cartridge  26  (region No. 1) of approximately 50 cc; and an interior volume of the ink supply tube  27  from the ink cartridge  26  to the pressure chamber  75  (region No. 2) of approximately 3.5 cc. Furthermore, the volume of the pressure chamber  75  capable of fluctuating (region No. 3) is approximately 1.0 cc; the interior volume of the ink supply tube  27  downstream from the pressure chamber  75  (region No. 4) is approximately 1.9 cc; the interior volume of the common ink chamber  30  (region No. 5) is approximately 3.1 cc; and the total interior volume of the eight fluid ejecting heads  24  (region No. 6) is approximately 0.9 cc. 
     An appropriate range of the pressurized ink amount Vd when carrying out non-ink-supply cleaning under the flow channel condition 1 is illustrated in  FIG. 10A , whereas appropriate ranges for the pressurizing time Ta and the depressurizing time Td are illustrated in  FIG. 10B . 
     With respect to the pressurized ink amount Vd, it is preferable to carry out pressurization so that the approximately 1.0 cc volume of the pressure chamber  75  is reduced to a volume in the range of 0.22 cc≦Vd≦0.62 cc. If 0.22 cc&gt;Vd, there is a risk that sufficient pressurizing for discharging the bubbles cannot be obtained, whereas if 0.62 cc&lt;Vd, there is a risk of consuming ink. 
     In the case where 0.22 cc≦Vd≦0.62 cc, it is preferable for the pressurizing time Ta to be 0.05 seconds≦Ta≦0.5 seconds and for the depressurizing time Td to be 0.09 seconds≦Td≦0.7 seconds (assuming, however, that Ta&lt;Td). 
     With the non-ink-supply cleaning performed by the pressure application mechanism  29 , the risk of ink sticking to the nozzle formation surface  24   a  after the cleaning is executed is low, and the meniscuses of the nozzles  25  can be unified, which makes it unnecessary to carry out wiping as post-processing, as is the case with ink supply cleaning. Ink consumption can be reduced to nearly zero, and the cleaning can be carried out in an extremely short amount of time. 
     According to the embodiment described thus far, the following effects can be obtained. 
     (1) Some ink is caused to swell from the nozzles  25  by the pressure application mechanism  29  pressurizing the ink within the ink supply tube  27 , making it possible to push bubbles that have intermixed with the ink at the swollen area out to the atmospheric side, which is outside of the nozzle openings  25   a . The pressure application mechanism  29  depressurizes the interior of the ink supply tube  27  immediately after the pressurization, which then pulls the ink that has swollen from the nozzles  25  due to the pressurization back into the fluid ejecting heads  24 , so that the ink is not wastefully consumed by falling from the nozzle openings  25   a  or the like. Thus according to the non-ink-supply cleaning performed by the pressure application mechanism  29 , bubbles can be discharged while also suppressing the consumption of ink. 
     (2) By pressurizing for a short amount of time so as to ensure the bubble discharge properties while also making the depressurizing time Td longer than the pressurizing time Ta, it is possible to suppress bubbles from being sucked in through the nozzle openings  25   a.    
     (3) By the pressure application mechanism  29  reducing the volume of the pressure chamber  75 , an amount of ink equivalent to the reduced volume is pushed out, thus making it possible to transmit the pressure toward the nozzles  25 . Because depressurization is carried out by increasing the volume of the pressure chamber  75 , the depressurization can be carried out immediately after the pressurization by returning the volume, which has been reduced for pressurization, to its original state. 
     (4) When bubbles are discharged from the nozzles  25  through pressurization, an equivalent air gap is produced within the nozzles  25 ; however, by reducing the volume of the pressure chamber  75  increased for depressurization beyond the volume of the pressure chamber  75  reduced for pressurization, the occurrence of empty nozzles caused by the air gaps can be suppressed. 
     (5) The meniscuses of the nozzles  25  can be unified by adjusting the backpressure of the nozzles  25  in the common ink chamber  30 . For example, the flow of ink caused by pressurization and depressurization in the non-ink-supply cleaning is transmitted to the nozzles  25  through the common ink chamber  30 . Accordingly, even in the case where an air gap has been produced within a single nozzle  25  from which bubbles have been discharged, repeating the pressurization and depressurization unifies the position of the liquid surface with the other nozzles  25 . The pressure application mechanism  29  is provided upstream from the common ink chamber  30  in the ink flow channel, and thus increasing the number of fluid ejecting heads  24  does not complicate the configuration. 
     (6) The pressurizing time Ta for which the pressure application mechanism  29  carries out pressurization is, under the flow channel condition 1, between 0.05 and 0.5 seconds, and is thus extremely short; accordingly, it is possible to dislodge bubbles that have adhered to the inner walls of the nozzles  25  and discharge those bubbles. 
     Second Embodiment 
     Next, a second embodiment of the invention will be described based on  FIGS. 11 to 13 . 
     With the printer  11  according to the first embodiment, the regions No. 1 through No. 6 of which the ink flow channel is configured communicate with each other, and thus ink that has been pushed out of the pressure chamber  75  moves not only into the regions No. 3 through No. 6 that are downstream, but also into the regions No. 1 and No. 2 that are upstream. For this reason, the pressure extending to the nozzles  25  weakens by the amount by which the pressure is transmitted upstream. Accordingly, in the second embodiment, a printer  11 A capable of causing the ink that has been pushed out to flow downstream only will be described. 
     As shown in  FIG. 11 , the printer  11 A according to the second embodiment includes an ink supply unit  14 A in place of the ink supply unit  14  of the printer  11 . In the ink supply unit  14 A, a differential pressure regulating valve  80  and an on-off valve  81  are provided in the ink supply tube  27 . 
     The on-off valve  81  is a valve that can be opened or closed as desired, and is provided immediately upstream from the pressure application mechanism  29 . A solenoid valve, a valve that operates mechanically, or the like can be employed as the on-off valve  81 . When executing non-ink-supply cleaning, putting the differential pressure regulating valve  80  into a closed state causes the ink that has been pushed out from the pressure chamber  75  to flow downstream only. 
     The differential pressure regulating valve  80  is a diaphragm-type self-sealing valve that opens and closes using a differential pressure between the atmospheric pressure and the ink pressure, and is disposed between the ink cartridge  26  and the on-off valve  81 . In the printer  11 A, the ink cartridge  26  (the cartridge holder, which is not shown) is provided in a higher position than the line head  13 . Accordingly, the interior of the fluid ejecting head  24  has a negative pressure of approximately −1 kPa due to the differential pressure regulating valve  80 . 
     As shown in  FIG. 12A , the differential pressure regulating valve  80  includes a flow channel formation member  82  of a fixed shape. A connection portion  83  is provided on the left end of the flow channel formation member  82 , connecting to the ink supply tube  27  on the upstream side, whereas a connection portion  84  is provided on the right side of the flow channel formation member  82 , connecting to the ink supply tube  27  on the downstream side. A recessed portion  82   a , which is circular in shape when viewed from above, is formed in the upper surface side of the flow channel formation member  82 , and a single protruding portion  82   b  having a conical trapezoidal shape is formed in a location of the inner base surface of the recessed portion  82   a  that is shifted to the left of the center. An inflow channel  83   a  that allows the ink supply tube  27  on the upstream side to communicate with the recessed portion  82   a  is formed in the connection portion  83 , so that an opening into the recessed portion  82   a  is formed in the upper end surface of the protruding portion  82   b . Meanwhile, an outflow channel  84   a  that allows the ink supply tube  27  on the downstream side to communicate with the recessed portion  82   a  is formed in the connection portion  84 . 
     A flexible film member  85  is affixed on the upper surface side of the flow channel formation member  82  in a flexible state so as to seal the opening of the recessed portion  82   a . Meanwhile, a disk-shaped depression plate  86  whose surface area is smaller than the area of the opening of the recessed portion  82   a  is affixed approximately in the center of the inner surface side of the film member  85  that faces toward the recessed portion  82   a . A pressure chamber  87  is enclosed and formed by the film member  85  and the recessed portion  82   a.    
     A base section  88 , an arm member  89  supported by the base section  88  in a tillable state, and a biasing spring  90  that biases one end of the arm member  89  (the left end) toward the protruding portion  82   b  are housed within the pressure chamber  87 . Under the constant biasing force of the biasing spring  90 , the one end of the arm member  89  seals the opening of the inflow channel  83   a  provided in the upper end surface of the protruding portion  82   b , while the other end (the right end) pushes the depression plate  86  in the upward direction. Accordingly, the film member  85  is flexed in a direction that expands the interior volume of the pressure chamber  87 , and thus the pressure chamber  87  and the interior of the fluid ejecting head  24  positioned in an area downstream therefrom have a negative pressure of approximately −1 kPa. 
     Ink is supplied to the inflow channel  83   a  in a pressurized state by the pressure pump  28 , and the inflow of ink into the pressure chamber  87  is suppressed by the one end of the arm member  89 , which constantly receives the biasing force from the biasing spring  90 . The negative pressure within the pressure chamber  87  increases as ink is consumed by ejection from the nozzles  25  or outflow, and as shown in  FIG. 12B , the film member  85  flexes, against the biasing force of the biasing spring  90 , in a direction that reduces the interior volume of the pressure chamber  87 . Upon doing so, the other end of the arm member  89  tilts so as to press upon the film member  85  through the depression plate  86  and the one end opens the opening of the inflow channel  83   a , and as a result, the ink pressurized within the pressure chamber  87  flows in through the inflow channel  83   a.    
     As the negative pressure within the pressure chamber  87  decreases due to the inflow of ink, the arm member  89  and the film member  85  return to their original positions due to the biasing force of the biasing spring  90 . Accordingly, an amount of ink in accordance with the amount that has been consumed is supplied to the fluid ejecting head  24 . 
     Next, non-ink-supply cleaning according to this embodiment will be described. 
     This non-ink-supply cleaning is configured of a valve closing step in which the on-off valve  81  is closed, a pressurizing step of causing ink to swell from the nozzles  25  by the pressure application mechanism  29  carrying out pressurization after the valve closing step, and a depressurizing step of the pressure application mechanism  29  carrying out depressurization in a state in which the ink has swelled from the nozzles  25  as a result of the pressurization. 
     By carrying out the pressurizing step and the depressurizing step while the on-off valve  81  is closed in this manner, ink is not supplied from upstream from the on-off valve  81  and is thus not ejected and does not drip down from the nozzle openings  25   a ; accordingly, ink is not consumed during the non-ink-supply cleaning. 
     In the printer  11 A, it is assumed that the differential pressure regulating valve  80  is in a closed state when the non-ink-supply cleaning is executed (this state will be referred to as a “flow channel condition 2” hereinafter). Under the flow channel condition 2, of the regions illustrated in  FIG. 9 , the regions aside from the regions No. 1 and 2, or the regions No. 3 through 6, correspond to the range that is affected by the pressurization and depressurization. 
     An appropriate range of the pressurized ink amount Vd when carrying out non-ink-supply cleaning under the flow channel condition 2 is illustrated in  FIG. 13A , whereas appropriate ranges for the pressurizing time Ta and the depressurizing time Td are illustrated in  FIG. 13B . 
     With respect to the pressurized ink amount Vd, it is preferable to carry out pressurization so that the approximately 1.0 cc volume of the pressure chamber  75  is reduced to a volume in the range of 0.18 cc≦Vd≦0.48 cc. In other words, because a loss in the pressure arising when ink flows toward the regions No. 1 and 2 is eliminated, bubbles can be discharged with a lower pressurized ink amount Vd under the flow channel condition 2 than under the flow channel condition 1. In this case, because 5,280 nozzles  25  are provided in a single line head  13 , a favorable ink swell range for a single nozzle is approximately 3.5×10 −5  cc to 9.0×10 −5  cc. It has been confirmed that particularly favorable results can be obtained by pressurizing at Ta=0.15 seconds and depressurizing at Td=0.35 seconds with Vd=0.33 cc. 
     In the case where 0.18 cc≦Vd≦0.48 cc, it is preferable for the pressurizing time Ta to be 0.025 seconds≦Ta≦0.2 seconds and for the depressurizing time Td to be 0.1 seconds≦Td≦0.5 seconds (assuming, however, that Ta&lt;Td). In other words, considering the flow channel conditions 1 and 2, it is preferable to set the pressurizing time Ta at which the pressure application mechanism  29  carries out pressurization in the pressurizing step to 0.025 seconds to 0.5 seconds. 
     According to the embodiment described thus far, the following effects can be obtained in addition to effects similar to those in the aforementioned (1) to (5). 
     (6) Some ink is caused to swell from the nozzles  25  by the pressure application mechanism  29  pressurizing the ink within the ink supply tube  27 , making it possible to push bubbles that have intermixed with the ink at the swollen area out to the atmospheric side, which is outside of the nozzle openings  25   a . Because the on-off valve  81  is closed at this time, ink is not supplied to nozzles from the ink supply tube  27  that is upstream from the on-off valve  81 . Accordingly, bubbles can be discharged from the nozzles  25  while suppressing the consumption of ink. 
     (7) Because the pressure application mechanism  29  depressurizes the interior of the ink supply tube  27  after pressurization while maintaining the closed state of the on-off valve  81 , ink that is swelling from the nozzles  25  can be pulled back into the fluid ejecting head  24  without being consumed wastefully due to dripping down from the nozzle openings  25   a  and so on. Accordingly, the meniscuses of the nozzles  25  can be suppressed from breaking, and the consumption of ink can be suppressed as well. The pressure can be increased by the amount of ink that is pulled back due to the depressurization, thus making it possible to improve the bubble discharge properties. 
     (8) Multiple pressure application mechanisms  29  are provided in accordance with the number of ink supply tubes  27  that are installed, thus making it possible to discharge bubbles for each of the ink supply tubes  27 . 
     (9) The pressurizing time Ta for which the pressure application mechanism  29  carries out pressurization is between 0.025 and 0.2 seconds, and is thus extremely short; accordingly, it is possible to dislodge bubbles that have adhered to the inner walls of the nozzles  25  and discharge those bubbles. 
     The aforementioned embodiments may be changed to the embodiments described hereinafter as well. 
     The pressure application mechanism  29  may have the configuration of a pressure application mechanism  29 A, as illustrated in  FIG. 14 . 
     The pressure application mechanism  29 A includes a flow channel formation member  91  of a fixed shape. A connection portion  92  is provided on the left end of the flow channel formation member  91 , connecting to the ink supply tube  27 , whereas a connection portion  93  is provided on the right side of the flow channel formation member  91 , connecting to the ink supply tube  27 . A recessed portion  91   a , which is circular in shape when viewed from above, is formed in the upper surface side of the flow channel formation member  91 . An inflow channel  92   a  that allows the ink supply tube  27  to communicate with the recessed portion  91   a  is formed in the connection portion  92 . Meanwhile, an outflow channel  93   a  that allows the ink supply tube  27  to communicate with the recessed portion  91   a  is formed in the connection portion  93 . 
     A piston  94  is housed in the recessed portion  91   a  of the flow channel formation member  91  so as to be capable of sliding. One end (the lower end) of the piston  94  configures a disk-shaped mobile portion  94   a  that in turn configures one wall surface of the pressure chamber  75 , whereas the other end (the upper end) of the piston  94  configures a disk-shaped pressure receiving portion  94   b . The pressure chamber  75  is enclosed and formed by the mobile portion  94   a  of the piston  94  and the recessed portion  91   a  of the flow channel formation member  91 . 
     The biasing member  76 , composed of a spring, is disposed between the upper surface side of the flow channel formation member  91  and the lower surface side of the pressure receiving portion  94   b . Accordingly, when the motor  79  is driven in the forward direction and the cam member  77  rotates in the counter-clockwise direction in  FIG. 14 , the mobile portion  94   a  of the piston  94  moves in a direction away from the rotational shaft  78 . Upon doing so, the volume of the pressure chamber  75  decreases, and the ink within the ink supply tube  27  is pressurized by the ink that has been pushed out from the pressure chamber  75 . When the motor  79  is driven in the backward direction and the cam member  77  rotates in the clockwise direction in  FIG. 14 , the mobile portion  94   a  of the piston  94  moves in a direction toward the rotational shaft  78  due to the biasing force of the biasing member  76 . Upon doing so, the volume of the pressure chamber  75  increases, and the inner of the ink supply tube  27  is depressurized by the ink that has been pulled into the pressure chamber  75 . 
     With respect to the pressure application mechanism  29 , the piston  94  of the pressure application mechanism  29 A may be configured of a movable core, and a solenoid may be provided in the periphery thereof. In this case, the piston  94  configured of the movable core can be moved by flowing a current to the solenoid and generating a magnetic field. 
     The pressure application mechanism may include a piezoelectric element, and the pressurization and depressurization may be carried out by changing the volume of the fluid supply channel using the piezoelectric element. 
     The ink supply tube  27  capable of elastic deformation may be pressurized by the cam member  77  pressing down thereupon. In this case, the flow channel formation member  71  need not be provided, which makes it possible to simplify the configuration. 
     For example, rather than including the common ink chamber  30 , one end of the ink supply tube  27  (a base end) may be connected to the ink cartridge  26 , and the other end (a leading end) of the ink supply tube  27  may be connected to the fluid ejecting head  24  via multiple branches. In this case, the pressure application mechanism  29  may be provided on the base end, or the pressure application mechanism  29  may be provided on the branched leading end. 
     The pressure application mechanism may be provided between the common ink chamber  30  and the reservoir  36 , or may be provided between the reservoir  36  and the cavity  39 . 
     The liquid flow channel may be configured of rigid tubing that does not easily experience elastic deformation. In this case, pressure fluctuations caused by the pressurization in the pressurizing step and the depressurization in the depressurizing step can be transmitted to the nozzles  25  without being absorbed by the elastic deformation of the tubing. 
     In the case where the flow channel conditions, the fluid that is ejected, or the like has been changed, the friction resistance, flow channel resistance, viscosity, and so on change, and it is thus preferable to adjust the pressurized ink amount Vd, the pressurizing time Ta, and the depressurizing time Td to values appropriate thereto. 
     The number of fluid ejecting heads  24 , nozzles  25 , nozzle rows N, and so on can be set as desired. 
     A non-removable ink tank may be employed for a fluid holding unit. 
     The invention may be realized using a full-line type line head printer having a long fluid ejecting head, a lateral printer, or a serial printer. 
     Although the fluid ejecting apparatus is embodied as an ink jet printer in the aforementioned embodiment, a fluid ejecting apparatus that ejects or discharges a fluid aside from ink may be employed as well, and the invention can be applied to various types of liquid ejecting apparatuses that include liquid ejecting heads or the like that discharge miniature-sized liquid droplets. “Droplet” refers to the state of the liquid ejected from the liquid ejecting apparatus, and is intended to include granule forms, teardrop forms, and forms that pull tails in a string-like form therebehind. The “liquid” referred to here can be any material capable of being ejected by the liquid ejecting apparatus. For example, any matter can be used as long as the matter is in its liquid state, including liquids having high or low viscosity, sol, gel water, other inorganic agents, organic agents, liquid solutions, liquid resins, and fluid states such as liquid metals (metallic melts); furthermore, in addition to liquids as a single state of a matter, liquids in which the molecules of a functional material composed of a solid matter such as pigments, metal particles, or the like are dissolved, dispersed, or mixed in a liquid carrier are included as well. Ink, described in the above embodiment as a representative example of a liquid, liquid crystals, or the like can also be given as examples. Here, “ink” generally includes water-based and oil-based inks, as well as various types of liquid compositions, including gel inks, hot-melt inks, and so on. The following are specific examples of liquid ejecting apparatuses: liquid ejecting apparatuses that eject liquids including materials such as electrode materials, coloring materials, and so on in a dispersed or dissolved state for use in the manufacture and so on of, for example, liquid-crystal displays, EL (electroluminescence) displays, front emission displays, and color filters; liquid ejecting apparatuses that eject bioorganic matters used in the manufacture of biochips; liquid ejecting apparatuses that eject liquids to be used as samples for precision pipettes; printing equipment and microdispensers; and so on. Furthermore, the invention may be employed in liquid ejecting apparatuses that perform pinpoint ejection of lubrication oils into the precision mechanisms of clocks, cameras, and the like; liquid ejecting apparatuses that eject transparent resin liquids such as ultraviolet light-curable resins onto a substrate in order to form miniature hemispheric lenses (optical lenses) for use in optical communication elements; and liquid ejecting apparatus that eject an etching liquid such as an acid or alkali onto a substrate or the like for etching. The invention can be applied to any type of these ejecting apparatuses.