Patent Publication Number: US-10315432-B2

Title: Discharging apparatus and method of discharging fluid

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a fluid discharging apparatus and a method of discharging a fluid. 
     2. Related Art 
     Various fluid discharging apparatuses that discharge a fluid from a discharge port are proposed. For example, JP-A-2002-282740 discloses a liquid droplet discharging apparatus in which a plunger rod is caused to perform reciprocation in a liquid chamber as an accommodation unit, and thus a liquid is discharged in a form of droplets by extruding the liquid from a discharge port. A discharging mechanism of a fluid, which uses a moving object such a plunger rod in JP-A-2002-282740 may be applied to, for example, an ink jet printer which is a printing device that produces a printout by discharging an ink, or a 3D printer which is a three-dimensional modeling device that models a three-dimensional object by discharging a liquid material. 
     In the above-described fluid discharging apparatus, after a fluid is discharged, the next fluid may be hindered from being discharged by the fluid which has adhered to a circumference of a discharge port. In the fluid discharging apparatus, a technique of suppressing a fluid from remaining on the circumference of the discharge port after the fluid is discharged may be improved more. 
     SUMMARY 
     The invention can be realized as the following aspects. 
     (1) According to a first aspect of the invention, there is provided a fluid discharging apparatus. The fluid discharging apparatus includes a storage chamber, a discharge port, a supply unit, a moving object, a pressure changing mechanism, and a control unit. The storage chamber stores a fluid. The discharge port communicates with the storage chamber and discharges the fluid. The supply unit supplies the fluid to the storage chamber by pressure. The moving object moves in a first direction toward the discharge port and a second direction away from the discharge port in the storage chamber. The pressure changing mechanism changes pressure of the fluid supplied to the storage chamber or pressure of the fluid in the storage chamber. The control unit controls driving of the moving object and driving of the pressure changing mechanism. The control unit performs discharging processing in which the discharge port is opened by moving the moving object from a closed position at which the discharge port is closed, in the second direction, and then the fluid is extruded and discharged from the discharge port by moving the moving object in the first direction. The control unit performs moving processing in which the moving object is moved in the second direction for a period when the fluid is discharged from the discharge port in the discharging processing. The control unit performs pressure control processing in which an increase in pressure of the storage chamber during the moving processing is suppressed by driving the pressure changing mechanism. 
     According to the fluid discharging apparatus in this aspect, the moving object is moved in a direction away from the discharge port during a period when the fluid is discharged from the discharge port, and thus a force which acts in a direction in which the fluid is drawn back from the discharge port into the storage chamber can be generated. With the generated force, it is possible to separate a fluid droplet which is required to be scattered toward a target from a fluid which has been extruded from the discharge port, and to bring the remaining fluid back into the storage chamber. Thus, an occurrence of a situation in which a redundant fluid is provided is at a circumferential portion of the discharge port after the fluid is discharged is effectively suppressed. According to the fluid discharging apparatus in this aspect, an occurrence of outflow of a fluid to the discharge port during the moving processing is suppressed by driving the pressure changing mechanism. Thus, the occurrence of a situation in which a redundant fluid is provided is at the circumferential portion of the discharge port after the fluid is discharged is more suppressed. 
     (2) In the fluid discharging apparatus of this aspect, the pressure changing mechanism may include a supply valve that controls a supply of the fluid to the storage chamber. The control unit may reduce a flow rate of the fluid flowing into the storage chamber by the supply valve in the process of the moving processing being performed, and thus may suppress an increase in pressure if the storage chamber. 
     According to the fluid discharging apparatus in this aspect, an occurrence of a situation in which pressure in the storage chamber is increased by pressure of supplied fluid by the supply unit in the process of the moving processing being performed is suppressed and an occurrence of a situation in which a redundant fluid flows out from the discharge port is suppressed. 
     (3) The fluid discharging apparatus of this aspect may further include a buffer room that communicates with the storage chamber and accommodates the fluid. The pressure changing mechanism may change the pressure of the storage chamber by changing a space volume of the buffer room. The control unit may cause the space volume of the buffer room to be increased in the process of the moving processing being performed, so as to suppress an increase in pressure of the storage chamber. 
     According to the fluid discharging apparatus in this aspect, it is possible to suppress an increase in pressure of the storage chamber and to suppress an occurrence of a redundant fluid flowing out from the discharge port, by moving a portion of the fluid accommodated in the storage chamber to the buffer room in the process of the moving processing being performed. 
     (4) In the fluid discharging apparatus of this aspect, the control unit may cause the space volume of the buffer room to be reduced in the process of the discharging processing being performed, so as to extrude the fluid to the storage chamber and accelerate flowing of the fluid to the discharge port. 
     According to the fluid discharging apparatus in this aspect, replenishment of a fluid into a region between the discharge port and the moving object is accelerated when the fluid is discharged from the discharge port. Thus, it is possible to efficiently perform the discharging processing. 
     (5) The fluid discharging apparatus of this aspect may further include outflow piping which is connected to the storage chamber. The pressure changing mechanism may include a control valve that controls a flow of the fluid in the outflow piping. The control unit may cause the flow rate of the fluid which flows out to the outflow piping to be increased by the control valve in the process of the moving processing being performed, so as to suppress an increase in pressure of the storage chamber. 
     According to the fluid discharging apparatus in this aspect, a portion of the fluid accommodated in the storage chamber is caused to flow out to the outflow piping through an outflow port in the process of the moving processing being performed. Thus, it is possible to suppress the increase in pressure of the storage chamber and to suppress the occurrence of a situation in which a redundant fluid flows out from the discharge port. 
     (6) According to a second aspect of the invention, there is provided a method of discharging a fluid from a discharge port which communicates with a storage chamber that stores the fluid. The method includes performing discharging processing in which a discharge port is opened by moving a moving object from a closed position at which the discharge port is closed, in a second direction away from the discharge port in the storage chamber, and then the fluid is extruded and discharged from the discharge port by moving the moving object in a first direction toward the discharge port, performing moving processing in which the moving object is moved in the second direction during a period when the fluid is discharged from the discharge port in the discharging processing, and performing pressure control processing in which a pressure changing mechanism that changes pressure of the fluid supplied to the storage chamber or pressure of the fluid in the storage chamber is driven to suppress an increase in pressure of the storage chamber, which occurs during the moving processing. 
     According to the fluid discharging apparatus in this aspect, an occurrence of a situation in which a redundant fluid is provided in a circumferential region of the discharge port after the fluid is discharged is efficiently suppressed by movement of the moving object in the moving processing. In addition, the occurrence of a situation in which the redundant fluid flows out from the discharge port during the moving processing is suppressed by the pressure changing mechanism. 
     All of a plurality of components provided in the above-described aspect of the invention are not necessary. In order to solve some or all of the above-described problems or to achieve some or all of effects described in this specification, appropriately, some of the plurality of components can be changed, removed, or replaced with other new components. In addition, some of limitation details for the components can be deleted. In order to solve some or all of the above-described problems or to achieve some or all of effects described in this specification, some or all of technical features provided in the above-described one aspect of the invention can be combined with some or all of technical features provided in the above-described another aspect of the invention, and the obtained combination can be used as a separate aspect of the invention. 
     The invention can be realized as various forms other than the fluid discharging apparatus and the method of discharging a fluid. For example, the invention can be realized as a printing device or a three-dimensional modeling device which includes the function of the fluid discharging apparatus, or a system which includes a function equivalent to that of the device, a control method of controlling the device or the system, a computer program for executing a method of discharging a fluid or the above control method, a non-volatile recording medium in which the above computer program is recorded, and the like. 
    
    
     
       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 diagram illustrating a configuration of a fluid discharging apparatus in a first exemplary embodiment. 
         FIG. 2  is a flowchart illustrating a flow of a discharging process in the first exemplary embodiment. 
         FIG. 3  is a diagram illustrating an example of a timing chart for moving a moving object, and opening and closing a supply valve in the discharging process in the first exemplary embodiment. 
         FIG. 4A  is a schematic diagram illustrating details of Process  1  in discharging processing in the first exemplary embodiment. 
         FIG. 4B  is a schematic diagram illustrating details of Process  2  in the discharging processing in the first exemplary embodiment. 
         FIG. 5A  is a schematic diagram illustrating details of Process  3  in moving processing in the first exemplary embodiment. 
         FIG. 5B  is a schematic diagram illustrating details of Process  4  in the moving processing in the first exemplary embodiment. 
         FIG. 6  is a schematic diagram illustrating a configuration of a fluid discharging apparatus in a second exemplary embodiment. 
         FIG. 7  is a flowchart illustrating a flow of a discharging process in the second exemplary embodiment. 
         FIG. 8  is a diagram illustrating an example of a timing chart for moving a moving object, and moving a valve body of a control valve mechanism in the discharging process in the second exemplary embodiment. 
         FIG. 9A  is a schematic diagram illustrating details of Process  1  and Process c in discharging processing in the second exemplary embodiment. 
         FIG. 9B  is a schematic diagram illustrating details of Process  2  in the discharging processing in the second exemplary embodiment. 
         FIG. 10A  is a schematic diagram illustrating details of Process  3  in moving processing in the second exemplary embodiment. 
         FIG. 10B  is a schematic diagram illustrating details of Process  4  and Process d in the moving processing in the second exemplary embodiment. 
         FIG. 11  is a schematic diagram illustrating a configuration of a fluid discharging apparatus in a third exemplary embodiment. 
         FIG. 12  is a flowchart illustrating a flow of a discharging process in the third exemplary embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     A. First Exemplary Embodiment 
       FIG. 1  is a schematic diagram illustrating a configuration of a fluid discharging apparatus  100  in a first exemplary embodiment of the invention.  FIG. 1  illustrates an arrow G which indicates a gravity direction (vertical direction) when the fluid discharging apparatus  100  is disposed in a general use state. In this specification, a direction described as “up” or “down” means a direction using the vertical direction as a reference, so long as particular statements are not made.  FIG. 1  illustrates arrows which indicate, respectively, a first direction D 1  and a second direction D 2  which will be described later. The arrows G, D 1 , and D 2  are appropriately illustrated in the drawings referring in this specification. 
     The fluid discharging apparatus  100  is a 3D printer which is a three-dimensional modeling device. The fluid discharging apparatus  100  models a three-dimensional object by discharging a fluid FL and piling a layer which has been obtained by curing the fluid FL. In this specification, “discharge” means that a fluid is released outwardly from a space in which the fluid is accommodated, by any force including gravity, and has a concept of including “ejection” of releasing a fluid by pressure. A specific example of a fluid FL which is discharged as a material of a three-dimensional object as a modeling target by the fluid discharging apparatus  100  will be described later. The fluid discharging apparatus  100  includes a discharging unit  10 , a supply unit  30 , a modeling stage  40 , a moving mechanism  45 , an energy applying unit  50 , and a control unit  60 . 
     The discharging unit  10  corresponding to a head unit in a 3D printer and discharges a fluid FL which is a material having fluidity, in a form of a fluid droplet. The “fluid droplet” means a particulate lump of a fluid and means a liquid droplet in a case where the fluid is a liquid. The shape of the fluid droplet is not limited. The shape of the fluid droplet may be spherical or may be a shape in which a spherical shape is extended in one direction, or a shape of, for example, a needle shape or a rod shape. The number of discharged fluid droplets for one discharge is not limited to 1 and a plurality of fluid droplets may be assumed to be discharged. The discharging unit  10  includes an accommodation unit  11 , a moving object  12 , a driving mechanism  13 , and a driving circuit  14 . 
     The accommodation unit  11  is configured as a hollow container and accommodates a fluid FL discharged by the discharging unit  10 . In the exemplary embodiment, the accommodation unit  11  has a shape which is substantially cylindrical, and is configured of, for example, stainless steel. A discharge port  15  which functions as a nozzle for discharging the fluid FL is provided in the bottom surface  11   b  of the accommodation unit  11 . 
     The discharge port  15  is provided as a through-hole which communicates with the internal space of the accommodation unit  11  and has an opening section having a substantially circle shape. In the exemplary embodiment, the discharge port  15  is opened in the vertical direction. An opening diameter of the discharge port  15  may be about 10 to 200 μm, for example. The length of the discharge port  15  in the vertical direction may be about 10 to 30 μm, for example. 
     The accommodation unit  11  includes a storage chamber  16 , a pressure chamber  17 , and a driving chamber  18 . The storage chamber  16  stores the fluid FL. The storage chamber  16  is connected to a flow passage  19  for receiving the fluid FL which is supplied from the supply unit  30  by pressure. The flow passage  19  is configured as a pipeline which penetrates an outer wall of the accommodation unit  11 . A tapered portion in which an inclined wall surface which is inclined downwardly toward the discharge port  15  has a diameter which is reduced downwardly is formed at a lower end of the storage chamber  16 . The tapered portion may be omitted and the bottom surface of the storage chamber  16  may be configured by a substantially horizontal surface. 
     The pressure chamber  17  is positioned under the storage chamber  16 . The pressure chamber  17  spatially continues to the storage chamber  16  and is opened at the lower end of the storage chamber  16 . The discharge port  15  is opened at a lower end of the pressure chamber  17 . As will be described later, the pressure chamber  17  is spatially separated from the storage chamber  16  by the moving object  12 , when the moving object  12  is disposed at a closed position at which the discharge port  15  is closed. The opening area of the pressure chamber  17  in a section which is perpendicular to an opening direction of the discharge port  15  is greater than the opening area of the discharge port  15 , and flow path resistance of the pressure chamber  17  is smaller than the flow path resistance of the discharge port  15 . 
     The driving chamber  18  is positioned over the storage chamber  16  and accommodates the driving mechanism  13 . The driving chamber  18  is spatially separated from the storage chamber  16  by a sealing member  21  which will be described later, such that the fluid FL stored in the storage chamber  16  is not entered. Thus, the driving mechanism  13  is protected from the fluid FL. 
     The moving object  12  is accommodated in the accommodation unit  11 . The moving object  12  is disposed over the discharge port  15 . In the exemplary embodiment, the moving object  12  is configured by a metal columnar member. The moving object  12  is disposed so as to cause the central axis of the moving object  12  to coincide with the central axis NX of the discharge port  15 . The shape of the moving object  12  is not limited to the columnar shape. The moving object  12  may have, for example, a substantially triangular pyramid shape or a substantially spherical shape. 
     The moving object  12  is disposed over the storage chamber  16  and the driving chamber  18 . The tip portion  12   a  of the moving object  12  is accommodated in the storage chamber  16 . The rear end portion  12   b  of the moving object is accommodated in the driving chamber  18 . In the exemplary embodiment, the tip portion  12   a  of the moving object  12  has a hemispherical shape. The rear end portion  12   b  of the moving object  12  has a substantially disc shape projected in a horizontal direction. The main body portion  12   c  of the moving object  12  between the tip portion  12   a  and the rear end portion  12   b  has a substantially columnar shape. The diameter of the main body portion  12   c  may be about 0.3 to 5 mm, for example. 
     An annular sealing member  21  which is configured by a resin O-ring is disposed at a boundary between the storage chamber  16  and the driving chamber  18 . The main body portion  12   c  of the moving object  12  is inserted into a through-hole at the middle of the sealing member  21 . The outer circumferential surface of the sealing member  21  is air-tightly in contact with the inner wall surface of the accommodation unit  11 . The inner circumferential surface of the sealing member  21  is air-tightly in contact with the main body portion  12   c  of the moving object  12 . Thus, the storage chamber  16  and the driving chamber  18  are spatially separated from each other, as described above. 
     The moving object  12  is disposed in the storage chamber  16  of the accommodation unit  11 , so as to be movable in a first direction D 1  toward the discharge port  15  and in a second direction D 2  away from the discharge port  15 . In the exemplary embodiment, the first direction D 1  and the second direction D 2  together are parallel to the central axis of the moving object  12  and are parallel to the vertical direction. In the exemplary embodiment, the moving object  12  moves back and forth in the vertical direction. The moving object  12  moves while rubbing the inner circumferential surface of the sealing member  21 . In the exemplary embodiment, the moving object  12  moves in a range of about 10 to 500 μm. 
     When being positioned at the lowest side position, the tip portion  12   a  of the moving object  12  comes into line-contact with the circumferential portion of an opening of the pressure chamber  17  in the storage chamber  16 . Thus, the discharge port  15  is closed against the storage chamber  16  and a spatial connection between the storage chamber  16  and the discharge port  15  is cut off. In this specification, the position of the moving object  12  at this time is referred to as “a closed position”. 
     The driving mechanism  13  applies a driving force for movement to the moving object  12 . The driving mechanism  13  includes a piezoelectric element  23  and an elastic member  24 . The piezoelectric element  23  has a configuration in which a plurality of piezoelectric materials is stacked. The length of the piezoelectric element  23  is changed in a direction in which the piezoelectric materials are stacked, in accordance with the level of a voltage applied to the piezoelectric materials. A voltage is applied to the piezoelectric element  23  from the driving circuit  14 . 
     The upper end portion of the piezoelectric element  23  is fixed to an upper wall surface of the driving chamber  18 . The lower end portion of the piezoelectric element  23  is in contact with the rear end portion  12   b  of the moving object  12 . The piezoelectric element  23  is stretched and a load is applied to the moving object  12 , and thus the moving object  12  moves in the first direction D 1 . 
     The elastic member  24  biases the moving object  12  in the second direction D 2 . In the exemplary embodiment, the elastic member  24  is configured by a disc spring. The elastic member  24  is disposed on a lower side of the rear end portion  12   b  of the moving object  12 , so as to surround the main body portion  12   c.  The elastic member  24  applies a force to the rear end portion  12   b  in the second direction. The elastic member  24  may be configured by a helical spring instead of the disc spring. When the piezoelectric element  23  is contracted, the moving object  12  moves in the second direction D 2  by the force applied from the elastic member  24 , so as to follow the lower end portion of the piezoelectric element  23 . 
     In the discharging unit  10 , the moving object  12  moves to reciprocate, and thus fluid droplets of the fluid FL are discharged from the discharge port  15 . A discharging mechanism of a fluid droplet in the discharging unit  10  will be described later. In the discharging unit  10 , a wall portion which constitutes the bottom surface  11   b  of the accommodation unit  11  and in which the discharge port  15  is not provided may be configured by a member which is detachable from the main body of the accommodation unit  11 . The above member is detached from the accommodation unit  11 , and thus, for example, cleaning or maintenance of the discharge port  15 , replacement or the like when deterioration or damage occurs is easily performed. In addition, replacement with various discharge ports  15  having different opening diameters (nozzle diameters) is possible. Further, in the discharging unit  10 , each of the components such as the moving object  12 , the sealing member  21 , and the elastic member  24 , which are accommodated in the accommodation unit  11  may be configured to be detachable from the accommodation unit  11 . Thus, maintenance of the discharging unit  10  or replacement of the component is easily performed. 
     The supply unit  30  supplies the fluid FL to the storage chamber  16  of the accommodation unit  11  through the flow passage  19  by pressure. The supply unit  30  includes piping  31 , a fluid storage unit  32 , a pressure generation unit  33 , and a supply valve  34 . The piping  31  connects the flow passage  19  of the accommodation unit  11  and the fluid storage unit  32 . The fluid storage unit  32  is a supply source of the fluid FL in the fluid discharging apparatus  100  and is configured by a tank for storing the fluid FL. In the fluid storage unit  32 , a solvent is mixed in the stored fluid FL, and thus viscosity of the fluid FL is maintained to be predetermined viscosity. The viscosity of the fluid FL may be about 50 to 40,000 mPa·s, for example. 
     The pressure generation unit  33  is configured by a pressing pump, for example. The pressure generation unit  33  applies pressure for supplying the fluid FL in the fluid storage unit  32  to the accommodation unit  11  through the piping  31  by pressure. The pressure generation unit  33  applies pressure of, for example, about 0.4 to 0.6 MPa to the fluid FL. In  FIG. 1 , the pressure generation unit  33  is provided on an upstream side of the fluid storage unit  32 . However, the pressure generation unit  33  may be provided on a downstream side of the fluid storage unit  32 . 
     The supply valve  34  is provided on the piping  31 , and controls a supply of the fluid FL to the storage chamber of the accommodation unit  11 . In the exemplary embodiment, the supply valve  34  is an on-off valve. Thus, when the supply valve  34  is in an open state, flowing of the fluid FL into the storage chamber  16  is permitted. When the supply valve  34  is in a closed state, flowing of the fluid FL into the storage chamber  16  is blocked. The supply valve is configured, for example, by a piezovalve. If the supply valve  34  is configured by a piezovalve, it is possible to obtain high responsiveness. Thus, a delay of a timing of opening and closing the supply valve  34  is suppressed. 
     The modeling stage  40  is disposed in the front of the opening direction of the discharge port  15  in the discharging unit  10 . The discharging unit  10  discharges the fluid FL to the modeling stage  40  as a target object. A three-dimensional object is modeled by fluid droplets of the fluid FL, which have been landed on the modeling stage  40 . In the exemplary embodiment, the modeling stage  40  is configured by a member having a flat plate shape, and is disposed substantially horizontally. The modeling stage  40  is disposed at a position which is separate vertically downwardly from the discharge port  15  by about 1.5 to 3 mm, for example. 
     The moving mechanism  45  includes a motor or a roller, a shaft, and various actuators which are used for displacing the modeling stage  40  with respect to the discharging unit  10 . The moving mechanism  45  displaces the modeling stage  40  relatively with respect to the discharging unit  10  in the horizontal direction and in the vertical direction, as represented by both the arrows X and Y in  FIG. 1 . Thus, the landed position of the fluid FL on the modeling stage  40  is adjusted. The fluid discharging apparatus  100  may have a configuration in which the modeling stage  40  is fixed and the discharging unit  10  is displaced with respect to the modeling stage  40 . 
     The energy applying unit  50  applies energy to the fluid FL landed on the modeling stage  40  so as to cure the fluid FL. In the exemplary embodiment, the energy applying unit  50  is configured by a laser device. The energy applying unit  50  applies light energy to the fluid FL by irradiation with laser. The energy applying unit  50  includes at least a laser light source, a condensing lens, and a galvano mirror (illustrations thereof are omitted). The condensing lens condenses laser emitted from the laser light source on the fluid FL landed on the modeling stage  40 . The galvano mirror is used for scanning with laser. The energy applying unit  50  scans a landed position of the fluid droplet on the modeling stage  40  with laser and causes light energy of the laser to sinter the powder material in the fluid FL. Alternatively, the powder material in the fluid FL is melted and combined. Accordingly, a material layer constituting a three-dimensional object is formed on the modeling stage  40 . 
     The energy applying unit  50  may cure the fluid FL by a method other than laser irradiation. The energy applying unit  50  may cure the fluid FL by irradiation with an ultraviolet ray or may remove at least a portion of a solvent of the fluid FL by heating of a heater and cure the powder material. 
     The control unit  60  is configured by a computer which includes a CPU  61  and a memory  62 . The CPU  61  conducts various functions for controlling the fluid discharging apparatus  100  by reading and executing a computer program in the memory  62 . The control unit  60  controls each of the discharging unit  10 , the supply unit  30 , the moving mechanism  45 , and the energy applying unit  50  which have been described above, to perform modeling processing for modeling a three-dimensional object. 
     The control unit  60  receives data MD for modeling a three-dimensional object from an external computer (illustration thereof is omitted) which is connected to the fluid discharging apparatus  100 . Data representing each of material layers which are stacked in a height direction of the three-dimensional object is included in the data MD. The control unit  60  determines a timing of discharging fluid droplets of the fluid FL to the discharging unit  10  or the size of the fluid droplet, based on the data MD. The control unit  60  determines a landed position of the fluid droplet of the fluid FL on the modeling stage  40 , or a laser irradiation position and an irradiation timing by the energy applying unit  50 , based on the data MD. The three-dimensional object modeled on the modeling stage  40  may be obtained through a sintering process in a heating furnace, if necessary. 
     The control unit  60  transmits a driving signal to the driving circuit  14  in the modeling processing, and thus controls moving of the moving object  12  and causes the fluid FL to be discharged to the discharging unit  10  in the discharging unit  10 . The control unit  60  controls an on-off operation of the supply valve  34  when the fluid FL is discharged to the discharging unit  10 . Control of the moving object  12  and control of the supply valve  34  by the control unit  60  in the discharging process of discharging the fluid FL will be described later. 
     With the above configuration, the fluid discharging apparatus  100  in the exemplary embodiment models a three-dimensional object which uses the fluid FL which is a discharging target, as a material. Specific examples of the fluid FL which is the material of the three-dimensional object will be described. In the exemplary embodiment, the fluid FL is a flowable composition which has a paste shape and includes a powder material and a solvent. The fluid FL may include a powder material and a solvent. Examples of the powder material may include single powder of magnesium (Mg), iron (Fe), cobalt (Co), chrome (Cr), aluminium (Al), titanium (Ti), copper (Cu), and nickel (Ni), alloy powder including one kind or more of the above metal (maraging steel, stainless steel, cobalt chromium molybdenum, titanium alloy, nickel alloy, aluminum alloy, cobalt alloy, and cobalt chromium alloy), and mixture powder obtained by mixing one or two kinds or more selected from the single powder or alloy powder. Examples of the solvent of the fluid FL may include water; (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether; acetic acid esters such as ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, and iso-butyl acetate; aromatic hydrocarbons such as benzene, toluene, and xylene; ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, ethyl-n-butyl ketone, diisopropyl ketone, and acetyl acetone; alcohols such as ethanol, propanol, and butanol; tetraalkyl ammonium acetates; sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; pyridine solvents such as pyridine, γ-picoline, and 2,6-lutidine; ionic liquids such as tetraalkyl ammonium acetate (for example, tetrabutyl ammonium acetate); and mixtures of one or two kinds or more selected from the above solvents. 
     The fluid FL may be a mixed material which is obtained by mixing a binder to the powder material and the solvent and has a slurry shape or a paste shape. Examples of the binder may include acrylic resin, epoxy resin, silicone resin, cellulose resin, other synthetic resins, or PLA (polylactic acid), PA (polyamide), PPS (polyphenylene sulfide), other thermoplastic resins. The fluid FL is not limited to a fluid including the powder material. Examples of the fluid FL may include a fluid in which resin such as general-purpose engineering plastics (for example, polyamide, polyacetal, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, and polyethylene terephthalate) is melted. In addition, the fluid FL may be resin such as engineering plastics (for example, polysulfone, polyimide, polyamide imide, polyether imide, and polyether etherketone). The fluid FL may include metal other than the above-described metal, ceramics, resin, or the like. The fluid FL may include a sintering aid. 
     The discharging process of the fluid FL in the fluid discharging apparatus  100  and control of the moving object  12  by the control unit  60  in the discharging process will be described with reference to  FIGS. 2 to 5B .  FIG. 2  is a flowchart illustrating an example of a flow of the discharging process of the fluid FL.  FIG. 3  is a diagram illustrating an example of a timing chart of moving the moving object  12 , and opening and closing the supply valve  34  in the discharging process. The position of the moving object  12  in a vertical axis of the timing chart in  FIG. 3  corresponds to the level of a voltage applied to the piezoelectric element  23  by the driving circuit  14 .  FIGS. 4A and 4B  are schematic diagrams illustrating details of the discharging processing performed in the discharging process.  FIGS. 5A and 5B  are schematic diagrams illustrating details of the moving processing performed in the discharging process. Each of  FIGS. 4A, 4B, 5A, and 5B  illustrates a form of a vicinity region of the discharge port  15  in the accommodation unit  11 . 
     The control unit  60  performs the discharging process of Processes  1  to  4  and Processes a and b in  FIG. 2  when a discharging timing of the fluid FL by the discharging unit  10  is reached in the modeling processing. Processes  1  to  4  are processes of control of moving the moving object  12  by the discharging unit  10 . Processes a and b are processes of controlling opening and closing of the supply valve  34 . If the discharging process is performed one time, fluid droplets of an amount as much as one dot are discharged. Firstly, the control unit  60  sequentially performs Process  1  and Process  2  as the discharging processing. 
     In Process  1 , the control unit  60  controls the driving circuit  14  to apply a voltage to the piezoelectric element  23  and thus causes the piezoelectric element  23  to be contracted (time points t 1  to t 2  in  FIG. 3 ). Thus, the moving object  12  moves from a closed position P C  at which the discharge port  15  is closed, in the second direction D 2 . The storage chamber  16  and the pressure chamber  17  are in a state of communicating with each other, and the discharge port  15  is opened ( FIG. 4A ). At this time, the supply valve  34  maintains an open state, and a supply of the fluid FL to the storage chamber  16  continues so as to cause internal pressure of the storage chamber  16  to be aimed pressure. In Process  1 , the moving object  12  reaches an open position P O  which is a position farthest from the discharge port  15  in a moving range of the moving object  12 . A moving period (time points t 1  to t 2 ) of the moving object  12  in the second direction in Process  1  may be about 50 to 400 μs, for example. 
     Then, the voltage applied to the piezoelectric element  23  is maintained during a short waiting time (time points t 3  to t 4  in  FIG. 3 ) which has been predetermined, and the moving object  12  is held at the open position P O . During the period, the fluid FL flows into a region between the tip portion  12   a  of the moving object  12  and the discharge port  15  by using the pressure of the storage chamber  16  as a driving force, and thus the fluid FL is replenished. The waiting time at this time may be appropriately determined in accordance with the viscosity of the fluid FL, pressure applied to the fluid FL by the pressure generation unit  33 , the volume of the storage chamber  16 , and the like. The waiting time may be about 100 to 300 μs, for example. 
     In Process  2 , the control unit  60  changes the voltage applied to the piezoelectric element  23  by the driving circuit  14  so as to stretch the piezoelectric element  23  (time points t 3  to t 4  in  FIG. 3 ). Thus, the moving object  12  moves in the first direction D 1 , the fluid FL is extruded from the discharge port  15  and discharging the fluid FL is started ( FIG. 4B ). In the exemplary embodiment, in Process  2 , the moving object  12  moves to the object  12  knocks on the inner wall surface of the accommodation unit  11 , and thus closes the discharge port  15 . Thus, flowing of the fluid FL into the pressure chamber  17  and the discharge port  15  can be temporarily blocked. Accordingly, accuracy of adjusting the amount of the discharged fluid FL is improved. 
     In Process  2 , a speed at which the moving object  12  moves in the first direction D 1  may be the same as or greater than a speed at which the moving object  12  moves in the second direction D 2  in Process  1 . In Process  2 , a load applied to the moving object  12  from the piezoelectric element  23  may be determined in accordance with aimed pressure of the fluid FL at the discharge port  15  when the fluid FL is discharged from the discharge port  15 . For example, in a case where the aimed pressure is about 900 to 1100 MPa, the load applied to the moving object  12  by the piezoelectric element  23  may be about several hundred N. 
     After discharging the fluid FL from the discharge port  15  is started by Process  2 , the control unit  60  starts the moving processing during a period when the fluid FL is discharged from the discharge port  15 . The “period when the fluid FL is discharged from the discharge port  15 ” means a period when the fluid FL is suspended from the discharge port  15  in a columnar shape and does not include a period after the tip portion of the columnar fluid FL is separated as a fluid droplet. That is, the period is a period after discharging of the fluid FL from the discharge port  15  is started and before a fluid droplet of the fluid FL is formed. This period varies depending on the viscosity of the fluid FL, pressure of the fluid FL at the discharge port  15 , or the like. The control unit  60  performs Process  2 , and then starts the moving processing at an elapsed time point which has been predetermined and at which it is expected that the fluid FL is in a state of being discharged from the discharge port  15 . For example, the control unit  60  may start the moving processing after a period of 0.001 to 0.04 s elapses from when Process  2  is performed. The control unit  60  sequentially performs Process a, Processes  3  and  4 , and Process b as the moving processing. Process a and Process b are processes of pressure control processing of changing the pressure of the fluid FL supplied to the storage chamber  16 . 
     In Process a, the control unit  60  closes the supply valve  34  and blocks the supply of the fluid FL to the storage chamber  16 . It can be interpreted that a state where the supply valve  34  and thus the supply of the fluid FL to the storage chamber  16  by pressure is stopped is a state where the flow rate of the fluid FL is reduced in comparison to that when the supply valve  34  is opened. Subsequently, in Process  3 , the control unit  60  controls the driving circuit  14  to apply a voltage to the piezoelectric element  23 , and thus causes the piezoelectric element  23  to be contracted again (time points t 5  to t 6  in  FIG. 3 ). Thus, moving of the moving object  12  in the second direction D 2  is started during the period when the fluid FL is discharged from the discharge port  15 . In the exemplary embodiment, in Process  3 , the moving object  12  moves to an intermediate position P M  between the closed position P C  and the open position P O  ( FIG. 5A ). 
     The moving object  12  is moved in the second direction D 2  in Process  3 , and thus a force from the discharge port  15  into the storage chamber  16  can be generated in the fluid FL discharged from the discharge port  15 . Thus, an inertial force and gravity at a time of discharging act on a portion of the fluid FL on a lower end side thereof which is suspended from the discharge port  15 , and a force which draws the fluid FL into the accommodation unit  11  acts on a portion of the fluid FL on an upper end side thereof. Accordingly, moving of the moving object  12  in the second direction D 2  causes the tip portion of the fluid FL on the lower end thereof which is suspended from the discharge port  15  to be separated as a fluid droplet and fly, as indicated by a broken line in  FIG. 5A . It can be interpreted that Process  3  is a process of moving the moving object  12  in the second direction D 2  and separating a fluid droplet from a columnar fluid FL. In addition, in Process  3 , the moving object  12  moves in the second direction D 2 , and thus an inertial force in a direction in which the fluid FL is drawn back into the accommodation unit  11  is generated and an occurrence of a situation in which the fluid FL remains at an outer portion of the discharge port  15  is suppressed. In particular, in the exemplary embodiment, the moving object  12  is moved from the closed position P C  in the second direction D 2 , and thus the force which brings the fluid FL back into the accommodation unit  11  is increased. Further, the occurrence of a situation in which the fluid FL remains at an outer portion of the discharge port  15  is more suppressed. 
     In Process  3 , as illustrated by a graph Ga of a two-dot chain line in  FIG. 3 , the moving object  12  may be moved to the open position P O . It is desirable that a moving distance of the moving object  12  in Process  3  is the same as or smaller than a moving distance of the moving object  12  in Process  1  (time points t 1  to t 2 ). Thus, an occurrence of a situation in which the moving distance of the moving object  12  is wastefully increased is suppressed and efficiency is increased. In particular, if the moving distance of the moving object  12  in Process  3  is smaller than the moving distance of the moving object  12  in Process  1 , an occurrence of a situation in which an outer air enters into the accommodation unit  11  from the discharge port  15  in Process  3  is suppressed. It is desirable that a period (time points t 6  to t 7  in  FIG. 3 ) after Process  3  until Process  4  is started is a period as short as the large amount of the fluid FL does not flow into a region between the tip portion  12   a  of the moving object  12  and the discharge port  15 . It is desirable that the period of time points t 6  to t 7  is a period shorter than the waiting time of the time points t 2  to t 3 . The period may be substantially omitted. Thus, an occurrence of a situation in which the fluid FL is extruded from the discharge port  15  in the next Process  4  is suppressed. 
     In Process  4 , the control unit  60  changes a voltage applied to the piezoelectric element  23  by the driving circuit  14 . Thus, the piezoelectric element  23  is stretched and the moving object  12  is brought back to the closed position P C  (time points t 7  to t 8  in  FIG. 3 ,  FIG. 5B ). Accordingly, a communication state between the discharge port  15  and the storage chamber  16  is cut off by the moving object  12  and an occurrence of leakage of the fluid FL from the discharge port  15  is suppressed. It is desirable that a speed when the moving object  12  is moved in the first direction D 1  in Process  4  is slower than a speed when the moving object  12  is moved in the first direction D 1  in Process  2 . Thus, an occurrence of a situation in which the fluid FL is discharged from the discharge port  15  by moving the moving object  12  in Process  4  is suppressed. It is possible to relieve an impact when the moving object  12  collides with the inner wall surface of the accommodation unit  11  at the closed position P C , and thus deterioration of the discharging unit  10  is suppressed. If Process  4  is completed, in Process b, the control unit  60  causes the supply valve  34  to be opened and causes the supply of the fluid FL to the storage chamber  16  to be started again. Thus, the internal pressure of the storage chamber  16  is restored. 
     In the exemplary embodiment, control of moving the moving object  12  in Processes  3  and  4  is performed during a period when the supply valve  34  is closed and transfer of pressure to the storage chamber  16  is blocked. Thus, the increase of the pressure in the storage chamber  16  is suppressed and flowing of the fluid FL to the discharge port  15  in the process of the moving processing being performed is suppressed in comparison to a case where the supply valve is maintained to be closed. Accordingly, at a time of moving processing, an occurrence of a situation in which the fluid FL is leaked from the discharge port  15  is suppressed. 
     A timing of performing Process a of closing the supply valve  34  may be not ahead of Process  3  and may be the same as a timing when moving of the moving object  12  in the second direction is started in Process  3 . The supply valve  34  may be closed during a period when the moving object  12  moves after moving of the moving object  12  in the second direction D 2  is started in Process  3 . The supply valve  34  may be closed during a short time between Process  3  and Process  4 . 
     A timing of performing Process b in which the supply valve  34  is opened again may be not after performing Process  4  is completed. Process b may be performed during a period when the moving object  12  moves in the first direction after moving of the moving object  12  in the first direction D 1  is started. The supply valve  34  may be opened just before the next discharging process is started. It is desirable that the supply valve  34  is opened at a timing at which the internal pressure of the storage chamber  16  can be restored to the predetermined aimed pressure for discharging the fluid FL in a period until the next discharging process. 
     As described above, according to the fluid discharging apparatus  100  and the method of discharging the fluid FL in the discharging process thereof in the exemplary embodiment, the moving object  12  is moved in the second direction D 2  during a period when the fluid FL is discharged from the discharge port  15 . Thus, separation of a fluid droplet from a columnar fluid FL which is suspended from the discharge port  15  is accelerated. With the moving processing in the discharging process, the redundant fluid FL discharged from the discharge port  15  is brought back into the accommodation unit  11 . Thus, the occurrence of a situation in which the fluid FL remains on the outside of the discharge port  15  after the discharging process is suppressed. In addition, the supply valve  34  is closed in the process of the moving processing being performed. Thus, flowing of the fluid FL to the discharge port  15  is suppressed and outflow of the fluid FL from the discharge port  15  is suppressed. Thus, an occurrence of a situation in which the redundant fluid FL is provided in the circumferential region of the discharge port  15 , which includes the discharge port  15 , and thus discharging of the next fluid FL is disturbed is suppressed. For example, an occurrence of a situation in which there is a mistake in the amount of the discharged fluid FL in the next discharging process or a situation in which a flying state of a fluid droplet of the fluid FL discharged in the next discharging process is deteriorated is suppressed. Thus, it is possible to smoothly and continuously perform discharging of a fluid droplet of the fluid FL. Since an occurrence of a situation in which the redundant fluid FL adheres to the circumferential region of the discharge port  15  is suppressed, it is possible to reduce the number of times of performing cleaning processing of the circumferential region of the discharge port  15 , and efficiency is increased. 
     Furthermore, according to the fluid discharging apparatus  100  and the method of discharging the fluid FL in the discharging process thereof in the exemplary embodiment, it is possible to obtain various advantages described in the above exemplary embodiment. 
     B. Second Exemplary Embodiment 
       FIG. 6  is a schematic diagram illustrating a configuration of a fluid discharging apparatus  100 A in a second exemplary embodiment. The fluid discharging apparatus  100 A in the second exemplary embodiment has a configuration which is substantially the same as that of the fluid discharging apparatus  100  ( FIG. 1 ) in the first exemplary embodiment except that the supply unit  30  does not include the supply valve  34 , and a buffer room  70  and a control valve mechanism  71  are added. For convenience, in  FIG. 6 , illustrations of the modeling stage  40 , the moving mechanism  45 , and the energy applying unit  50  are omitted. 
     The buffer room  70  communicates with the storage chamber  16  and accommodates the fluid FL flowing out from the storage chamber  16 . In the exemplary embodiment, the buffer room  70  is provided at a position which is adjacent to the storage chamber  16 , in the accommodation unit  11 . The buffer room  70  communicates with the storage chamber  16  through an outflow port  70 o which opens in a side wall surface of the storage chamber  16 . 
     The control valve mechanism  71  contracts a valve body  73  in the buffer room  70 , and thus controls the amount of the fluid FL accommodated in the buffer room  70  and changes the pressure of the storage chamber  16 . The control valve mechanism  71  includes a driving chamber  72 , a sealing member  74 , a driving mechanism  75 , and a driving circuit  76  in addition to the valve body  73 . The driving chamber  72  is provided at a position which is adjacent to the buffer room  70 , and accommodates the driving mechanism  75  for driving the valve body  73 . The valve body  73  is configured by a columnar member. A tip portion  73   a  of the valve body  73  is disposed in the buffer room  70  and a rear end portion  73   b  thereof is disposed in the driving chamber  72 . 
     An annular sealing member  74  which is configured by a resin O-ring is disposed at a boundary between the buffer room  70  and the driving chamber  72 . The valve body  73  is inserted into a through-hole at the center of the sealing member  74  and is held. The outer circumferential surface of the sealing member  74  is air-tightly in contact with the inner wall surface of the buffer room  70 . The inner circumferential surface of the sealing member  74  is air-tightly in contact with the side surface of the valve body  73 . Accordingly, the buffer room  70  and the driving chamber are air-tightly separated from each other, and thus entering of the fluid FL into the driving chamber  72  is suppressed and the driving mechanism  75  is protected. 
     A driving force is applied to the valve body  73  from the driving mechanism  75  in the driving chamber  72 , and thus the valve body  73  moves to reciprocate between the buffer room  70  and the driving chamber  72  while rubbing the inner circumferential surface of the sealing member  74 . Thus, the valve body  73  is stretched or contracted in the buffer room  70  and changes the space volume of the buffer room  70 . The space volume of the buffer room  70  corresponds to a value obtained by subtracting the volume of the valve body  73  accommodated in the buffer room  70  from the volume of a space surrounded by the sealing member  74  and the inner wall surface of the buffer room  70 . The space volume of the buffer room  70  indicates the volume of the fluid FL which can be accommodated in the buffer room  70 . 
     The driving mechanism  75  includes a piezoelectric element  75   a  and an elastic member  75   b.  The piezoelectric element  75   a  has a configuration in which a plurality of piezoelectric materials is stacked. The length of the piezoelectric element  75   a  is changed in a direction in which the piezoelectric materials are stacked, in accordance with the level of a voltage applied to the piezoelectric materials. A voltage is applied to the piezoelectric element  75   a  from the driving circuit  76 . The control unit  60  commands the driving circuit  76  to apply a voltage, and thus controls stretching and contraction deformation of the piezoelectric element  75   a.    
     One end portion of the piezoelectric element  75   a  in the stacking direction is fixed to a wall surface of the driving chamber  72  and the other end portion thereof is in contact with the rear end portion  73   b  of the valve body  73 . Since the piezoelectric element  75   a  is stretched and presses the rear end portion  73   b  of the valve body  73 , the valve body  73  moves toward the storage chamber  16 , and the length of the valve body  73  which protrudes into the buffer room  70  is extended. The length of the valve body  73  in the buffer room  70  is extended, and thus the space volume of the buffer room  70  is reduced. 
     The elastic member  75   b  biases the valve body  73  in a direction away from the storage chamber  16 . In the exemplary embodiment, the elastic member  75   b  is configured by a disc spring. The rear end portion  73   b  of the valve body  73  has a substantially disc shape and is projected in a diameter direction of the valve body  73 . The elastic member  75   b  is disposed on the tip portion  73   a  side from the rear end portion  73   b  of the valve body  73 , so as to surround the valve body  73 . The elastic member  75   b  is in contact with a projected portion of the rear end portion  73   b,  and thus applies an elastic force to the valve body  73 . The elastic member  75   b  may be configured by a helical spring instead of the disc spring. 
     When the piezoelectric element  75   a  is contracted, the valve body  73  follows the contraction of the piezoelectric element  75   a  and moves in the direction away from the storage chamber  16 , by the force applied from the elastic member  75   b.  Thus, the length of the valve body  73  which protrudes into the buffer room  70  is reduced. The length of the valve body  73  in the buffer room  70  is reduced, and thus the space volume of the buffer room  70  is increased. 
     In a discharging process which will be described below, the control unit  60  controls moving of the moving object  12  in the discharging unit  10 , and controls the control valve mechanism  71  with following the moving of the moving object  12  to change the space volume of the buffer room  70 . Thus, the fluid FL is caused to flow in a space between the storage chamber  16  and the buffer room  70 , and thus the pressure in the storage chamber  16  during the discharging process is changed. 
     The discharging process of the fluid FL in the fluid discharging apparatus  100 A and control of the control valve mechanism  71  by the control unit  60  in the discharging process will be described with reference to  FIGS. 7 to 10B .  FIG. 7  is a flowchart illustrating an example of a flow of the discharging process of the fluid FL in the fluid discharging apparatus  100 A in the second exemplary embodiment.  FIG. 8  is a diagram illustrating an example of a timing chart of moving the moving object  12  of the discharging unit  10  and moving the valve body  73  of the control valve mechanism  71  in the discharging process. The timing chart for the moving object  12  of the discharging unit  10  in  FIG. 8  is substantially the same as that in  FIG. 3 . The position of the valve body  73  in a vertical axis of the timing chart in  FIG. 8  corresponds to the level of a voltage applied to the piezoelectric element  75   a  by the driving circuit  76 .  FIGS. 9A and 9B  are schematic diagrams illustrating details of discharging processing performed in the discharging process.  FIGS. 10A and 10B  are schematic diagrams illustrating details of moving processing performed in the discharging process. Each of  FIGS. 9A, 9B, 10A, and 10B  illustrates a form of a vicinity region of the discharge port  15  including the buffer room  70 . 
     In the discharging process according to the second exemplary embodiment, in Processes  1  to  4 , the control unit performs control of the moving object  12  in a manner similar to Processes  1  to  4  ( FIG. 3 ) described in the first exemplary embodiment. In Processes c and d, the control unit  60  changes the space volume of the buffer room  70  by moving the valve body  73 . Process a and Process b are processes of pressure control processing in which the control valve mechanism  71  changes the pressure of the storage chamber  16 . 
     In Process  1 , the control unit  60  controls the moving object  12  to be moved from the closed position P C , in the second direction D 2  (time points t 1  to t 2  in  FIG. 8 ,  FIG. 9A ). After a predetermined waiting time (time points t 2  to t 3  in  FIG. 8 ), in Process  2 , the moving object  12  is moved in the first direction D 1  and discharging of the fluid FL from the discharge port  15  is started (time points t 3  to t 4  in  FIG. 8 ,  FIG. 9B ). 
     When the discharging processing of Processes  1  and is started, the valve body  73  of the control valve mechanism  71  is at a position P B  when the valve body  73  is contracted in maximum in the buffer room  70 , and the space volume of the buffer room  70  is in the maximum state (time point t 1  in  FIG. 8 ). The control unit  60  performs Process c at the timing of performing the above-described Process  1 , and the space volume of the buffer room  70  is reduced. In Process c, during Process  1  in which the moving object  12  is moved in the second direction D 2 , the control unit  60  moves the valve body  73  so as to cause the tip portion  73   a  of the valve body  73  to reach a position P A  which is nearest to the storage chamber  16 , and thus the valve body  73  is stretched in the buffer room  70  (time points t 1  to t 2  in  FIG. 8 ,  FIG. 9A ). Thus, the space volume of the buffer room  70 , and thus it is possible to cause a portion of the fluid FL in the buffer room  70  to flow into the storage chamber  16 . In addition, since the fluid FL is replenished in the storage chamber  16  before the fluid FL is discharged from the discharge port  15 , it is possible to reduce a time to increase the internal pressure. Process c may be performed during a period of the time points t 2  to t 3  when the moving object  12  stops at the open position P O , instead of a period of the time points t 1  to t 2 . 
     In Process  3  of the moving processing, the control unit  60  moves the moving object  12  in the second direction D 2  during a period when the fluid FL is discharged from the discharge port  15  (time points t 5  to t 6  in  FIG. 8 ,  FIG. 10A ). Thus, a force which acts in a direction in which the fluid FL is drawn back from the discharge port  15  into the storage chamber  16  is generated. Accordingly, a fluid droplet (illustrated with a broken line in  FIG. 10A ) of the fluid FL is separated and the remaining fluid FL is attracted into the accommodation unit  11 . In Process  4 , the control unit  60  moves the moving object  12  in the first direction so as to reach the closed position P C , and thus the discharge port  15  is in the closed state. 
     The control unit  60  performs Process d at the timing of performing the above-described Process  3  in the process of the moving processing being performed. After the control unit  60  starts moving of the moving object  12  in the second direction D 2  in Process  3 , in Process d, the control unit  60  moves the valve body  73  of the control valve mechanism  71  so as to cause the tip portion  73   a  of the valve body  73  to reach a position P B  which is farthest from the storage chamber  16  (time points t 7  to t 8  in  FIG. 8 ,  FIG. 10B ). Thus, the valve body  73  in the buffer room  70  is contracted and the space volume of the buffer room  70  is increased. Therefore, it is possible to move a portion of the fluid FL in the storage chamber  16  to the buffer room  70 , and thus an increase of the internal pressure of the storage chamber  16  is suppressed. Accordingly, when the moving object  12  is moved in the first direction D 1 , it is possible to suppress flowing of the fluid FL to the discharge port  15 , and the occurrence of a situation in which a redundant fluid FL is discharged from the discharge port  15  is suppressed. 
     As described above, according to the fluid discharging apparatus  100 A and the method of discharging the fluid FL in the second exemplary embodiment, since the volume of the buffer room  70  which communicates with the storage chamber  16  is increased in the process of the moving processing being performed, flowing of the fluid FL to the discharge port  15  is suppressed. Thus, an occurrence of a situation in which the redundant fluid FL is discharged from the discharge port  15  in the process of the moving processing being performed is suppressed. In addition, according to the fluid discharging apparatus  100 A and the method of discharging the fluid FL in the second exemplary embodiment, since the fluid FL is replenished from the buffer room  70  into the storage chamber  16  in the process of the discharging processing being performed, it is possible to reduce a processing time for the discharging processing. Further, according to the fluid discharging apparatus  100 A and the method of discharging the fluid FL in the second exemplary embodiment, it is possible to exhibit various effects which are similar to those described in the first exemplary embodiment. 
     C. Third Exemplary Embodiment 
       FIG. 11  is a schematic diagram illustrating a configuration of a fluid discharging apparatus  100 B in a third exemplary embodiment. The fluid discharging apparatus  100 B in the third exemplary embodiment has a configuration which is substantially the same as that of the fluid discharging apparatus  100 A ( FIG. 6 ) in the second exemplary embodiment except that a communication passage  80  of the accommodation unit  11 , outflow piping  81 , and a control valve mechanism  82  are added instead of the buffer room  70  and the control valve mechanism  71 . For convenience, similar to  FIG. 6 , in  FIG. 11 , the illustrations of the modeling stage  40 , the moving mechanism  45 , and the energy applying unit  50  are omitted. 
     In the fluid discharging apparatus  100 B in the third exemplary embodiment, the communication passage  80  is provided in the accommodation unit  11 . The communication passage  80  is provided as a through-hole which is extended from the outside of the accommodation unit  11  to the storage chamber  16 . An outflow port which communicates with the communication passage  80  opens in a wall surface of the storage chamber  16 . The communication passage  80  is connected to the fluid storage unit  32  of the supply unit  30  through the outflow piping  81 . 
     The control valve mechanism  82  is provided in the outflow piping  81 , and controls the flow of the fluid FL in the outflow piping  81 . The control valve mechanism  82  causes the fluid FL to flow out from the storage chamber  16  through the outflow piping  81 , and thus changes a pressure state of the storage chamber  16 . The control valve mechanism  82  includes a control valve  83  and a pump  84 . The control valve  83  is an on-off valve and is opened or closed under control of the control unit  60 . The pump  84  is a suction pump which drives under the control of the control unit  60 . The pump  84  generates a driving force which causes the fluid FL in the outflow piping  81  to flow from the storage chamber  16  toward the fluid storage unit  32 . The pump  84  may be omitted. 
       FIG. 12  is a flowchart illustrating an example of a flow of a discharging process in the fluid discharging apparatus  100 B in the third exemplary embodiment. In the discharging process, the control unit  60  performs Processes  1  and  2  of discharging processing and Processes  3  and  4  of moving processing a manner similar to that described in the first exemplary embodiment. The control unit  60  performs Processes e and f of controlling the control valve mechanism with control of the moving object  12 , in the moving processing. Processes e and f correspond to pressure control processing in which the pressure of the storage chamber  16  is changed by driving the control valve mechanism  82 . 
     The control unit  60  performs Process  1  and Process  2  of the discharging processing, similar to that described in the first exemplary embodiment. The control unit  60  closes the control valve  83  during a period when Process  1  and Process  2  are performed. 
     In the moving processing, the control unit  60  opens the control valve  83  of the control valve mechanism  82  during a period when the fluid FL is discharged from the discharge port  15 , in Process e. The control unit  60  moves the moving object  12  in the second direction D 2  in a state where flowing of the fluid FL out into the outflow piping  81  is started, in Process  3 . The control unit  60  moves the moving object  12  in the first direction D 1  so as to close the discharge port  15  in Process  4 . Then, in Process f, the control unit  60  closes the control valve  83  of the control valve mechanism  82 . The control unit  60  drives the pump  84  so as to induce the fluid FL which has flowed out into the outflow piping  81 , into the fluid storage unit  32 . 
     As described above, since, when the moving processing is performed, the fluid FL in the storage chamber is caused to flow out into the outflow piping  81 , the increase of the pressure in the storage chamber  16  during the moving processing is suppressed, and flowing of the fluid FL to the discharge port  15  is suppressed. Thus, the occurrence of a situation in which a redundant fluid FL flows out from the discharge port  15  during the moving processing is suppressed. The fluid FL flowing out into the outflow piping  81  is circulated into the fluid storage unit  32  and is reused. Thus, a wasteful use of the fluid FL is suppressed. 
     A timing at which the control valve  83  is opened in Process e may be not a timing before moving of the moving object  12  in the second direction D 2  in Process  3  is started. The timing at which the control valve  83  is opened may be provided during a period when the moving object  12  moves in Process  3  or may be provided during a period when the moving object  12  moves in the first direction D 1  in Process  4 . A timing at which the control valve  83  is closed may be not a timing after the discharge port  15  is closed by the moving object  12 . The timing at which the control valve  83  may be provided before the discharge port  15  is closed by the moving object  12  or the control valve  83  may be closed just before the next discharging process is started. It is desirable that the control valve  83  is closed at a timing at which the internal pressure of the storage chamber  16  can reach the predetermined aimed pressure in a period until the next discharging process is started. 
     As described above, according to the fluid discharging apparatus  100 B and the method of discharging the fluid FL in the third exemplary embodiment, since the fluid FL in the storage chamber  16  is caused to flow out into the outflow piping  81  during the moving processing, flowing of the fluid FL to the discharge port  15  during the moving processing is suppressed. Thus, an occurrence of a situation in which the redundant fluid FL is discharged from the discharge port  15  in the process of the moving processing being performed is suppressed. In addition, according to the fluid discharging apparatus  100 B and the method of discharging the fluid FL in the third exemplary embodiment, since the fluid FL which has flowed out from the outflow piping  81  during the moving processing can be circulated and be reused, efficiency is increased. Further, according to the fluid discharging apparatus  100 B and the method of discharging the fluid FL in the third exemplary embodiment, it is possible to exhibit various effects which are similar to those described in the first exemplary embodiment and the second exemplary embodiment. 
     D. Modification Example 
     D1. Modification Example 1 
     The fluid discharging apparatus  100  in the first exemplary embodiment includes the supply valve  34  as the pressure changing mechanism that changes the pressure of the fluid FL supplied to the storage chamber  16 . The fluid discharging apparatus  100 A in the second exemplary embodiment includes the control valve mechanism  71  that changes the space volume of the buffer room  70 , as the pressure changing mechanism that changes the pressure in the storage chamber  16 . The fluid discharging apparatus  100 B in the third exemplary embodiment includes the control valve mechanism  82  that controls flowing of the fluid FL out from the storage chamber  16  into the outflow piping  81 , as the pressure changing mechanism that changes the pressure in the storage chamber  16 . On the other hand, the fluid discharging apparatus may include a pressure changing mechanism that changes the pressure of the fluid FL supplied to the storage chamber  16  or the pressure in the storage chamber  16  by using a method which is different from the method described in each of the exemplary embodiments. For example, the fluid discharging apparatus may include a pressure changing mechanism that temporarily branches a portion of the fluid FL from the piping  31  and temporarily reduces the pressure of the fluid FL supplied to the storage chamber  16 . The fluid discharging apparatus may include a pressure changing mechanism that changes the pressure in the storage chamber  16  in a manner that the wall surface of the storage chamber  16  is deformed to be bent by an actuator such as a piezoelectric element, and thus the space volume of the storage chamber  16  is changed. 
     D2. Modification Example 2 
     In the first exemplary embodiment, the supply valve  34  is configured by an on-off valve. On the other hand, the supply valve  34  may be configured by a flow-rate control valve which can control an opening thereof. In this case, the control unit  60  may reduce the opening of the supply valve  34  and reduce the flow rate of the fluid FL for the storage chamber  16  at a timing which has been described as the timing at which the supply valve  34  is closed in the first exemplary embodiment. The control unit  60  may increase the opening of the supply valve  34  and increase the flow rate of the fluid FL for the storage chamber  16  at a timing which has been described as the timing at which the supply valve  34  opens in the first exemplary embodiment. 
     D3. Modification Example 3 
     In the fluid discharging apparatus  100 A in the second exemplary embodiment, the valve body  73  is moved to reciprocate by the piezoelectric element  75   a,  and thus the valve body  73  is stretched or contracted in the buffer room  70 . On the other hand, in the fluid discharging apparatus  100 A in the second exemplary embodiment, the valve body  73  may be moved to reciprocate by the piezoelectric element  75   a.  For example, the valve body  73  may be moved by a solenoid mechanism or the valve body  73  may be moved by using pressure of the air. 
     D4. Modification Example 4 
     In the second exemplary embodiment, in the discharging processing of the discharging process, Process c is performed so as to reduce the volume of the buffer room  70  and to cause the fluid FL in the buffer room  70  to flow out into the storage chamber  16 . On the other hand, Process c may be not performed in the discharging processing of the discharging process. For example, Process c may be performed in a state where the discharge port  15  is closed after the moving processing is performed. 
     D5. Modification Example 5 
     In the second exemplary embodiment, the buffer room is provided at the position which is adjacent to the storage chamber  16 . On the other hand, the buffer room  70  may be provided at a position far from the storage chamber  16 . The buffer room  70  may communicate with the storage chamber  16  through piping or a pipeline such that the fluid FL in the storage chamber  16  can flow into the buffer room  70 . 
     D6. Modification Example 6 
     In the second exemplary embodiment, the valve body  73  operates to be stretched or contracted in the buffer room  70 , and thus the space volume of the buffer room  70  is increased or decreased and the pressure of the storage chamber  16  is changed. On the other hand, the space volume of the buffer room  70  may be increased or decreased by another method. The space volume of the buffer room  70  may be increased or decreased in a manner that the wall surface of the buffer room  70  is deformed by a piezoelectric element or the like. 
     D7. Modification Example 7 
     In the third exemplary embodiment, the control valve  83  is configured by an on-off valve. On the other hand, the control valve  83  may be configured by a flow-rate control valve which can control an opening thereof. In this case, the control unit  60  may reduce the opening of the control valve  83  and reduce the flow rate of the fluid FL out from the storage chamber  16  into the outflow piping  81  at a timing which has been described as the timing at which the control valve  83  is closed in the third exemplary embodiment. The control unit  60  may increase the opening of the control valve  83  and increase the flow rate of the fluid FL out from the storage chamber  16  into the outflow piping at a timing which has been described as the timing at which the control valve  83  opens in the third exemplary embodiment. 
     D8. Modification Example 8 
     In the fluid discharging apparatus  100 B in the third exemplary embodiment, the outflow piping  81  is connected to the fluid storage unit  32 , and thus the fluid FL which has flowed into the outflow piping  81  is circulated and is reused. On the other hand, the outflow piping  81  may be not connected to the fluid storage unit  32 . The fluid FL which has flowed into the outflow piping  81  may be stored in another storage unit. 
     D9. Modification Example 9 
     In each of the exemplary embodiments, the control unit  60  moves the moving object  12  to the closed position P C  in Process  2  of the discharging processing. On the other hand, the control unit  60  does not move the moving object  12  to the closed position P C  in Process  2  of the discharging processing, but may stop the moving object  12  at a position ahead of the closed position P C  and may move the moving object  12  in the second direction D 2  in Process  3 . 
     D10. Modification Example 10 
     In each of the exemplary embodiments, the control unit  60  may change a speed of moving the moving object  12  in the middle of each of Processes  1  to  4 . 
     D11. Modification Example 11 
     The configurations of the exemplary embodiments and the modification examples of the exemplary embodiments may be appropriately combined. For example, the configuration of the buffer room  70  and the control valve mechanism  71  in the second exemplary embodiment may be applied to the fluid discharging apparatus  100  in the first exemplary embodiment. Thus, in the discharging process, the control of the control valve mechanism  71  described in the second exemplary embodiment may be performed in addition to the control of the supply valve  34  described in the first exemplary embodiment. Similarly, the configuration of the outflow piping  81  and the control valve mechanism  82  in the third exemplary embodiment may be applied to the fluid discharging apparatus  100  in the first exemplary embodiment. Thus, in the discharging process, the control of the control valve mechanism  82  described in the third exemplary embodiment may be performed in addition to the control of the supply valve  34  described in the first exemplary embodiment. The outflow piping  81  and the control valve mechanism  82  in the third exemplary embodiment may be applied to the fluid discharging apparatus  100 A in the second exemplary embodiment. Thus, in the discharging process, the control of the control valve mechanism  82  described in the third exemplary embodiment may be performed in addition to the control of the control valve mechanism  71  described in the second exemplary embodiment. The configuration of the buffer room  70  and the control valve mechanism  71  in the second exemplary embodiment and the configuration of the outflow piping  81  and the control valve mechanism  82  in the third exemplary embodiment may be applied to the fluid discharging apparatus  100  in the first exemplary embodiment. Thus, in the discharging process, the control of the control valve mechanism  71  described in the second exemplary embodiment and the control of the control valve mechanism  82  described in the third exemplary embodiment may be performed in addition to the control of the supply valve  34  described in the first exemplary embodiment. 
     D12. Modification Example 12 
     In each of the exemplary embodiments, the discharging process are performed in the modeling processing of modeling a three-dimensional object. On the other hand, the discharging process may be performed at a time other than the time of the modeling processing. For example, the discharging process may be performed during flushing which is performed for maintenance of the discharging unit  10 . 
     D13. Modification Example 13 
     In each of the exemplary embodiments, the pressure chamber  17  of the accommodation unit  11  may be omitted. In this case, the tip portion  12   a  of the moving object  12  at the closed position P C  may come into contact with the inner circumferential portion of the discharge port  15  and may directly close the discharge port  15 . 
     D14. Modification Example 14 
     In each of the exemplary embodiments, the moving object  12  is displaced with applying a load in accordance with stretching or contracting of the piezoelectric element  23 . On the other hand, the moving object  12  may be displaced with applying a load by a method other than the method using the piezoelectric element  23 . For example, the moving object  12  may be displaced with applying a load by pressure of a gas. In each of the exemplary embodiments, the moving object  12  may be integrated with the piezoelectric element  23 . In addition, a configuration in which the tip portion of the piezoelectric element  23  moves to reciprocate in the accommodation unit  11 , as the moving object  12  may be made. 
     D15. Modification Example 15 
     The fluid discharging apparatus in each of the exemplary embodiments is realized as a three-dimensional modeling device that models a three-dimensional object. On the other hand, the fluid discharging apparatus may be not realized as the three-dimensional modeling device. For example, the fluid discharging apparatus may be realized as an ink jet printer that discharges an ink as the fluid or may be realized as a coating device that discharges a coating material or a working device that discharges an adhesive having fluidity. 
     D16. Modification Example 16 
     In each of the exemplary embodiments, some or all of the function and the processing realized by software may be realized by hardware. Some or all of the function and the processing realized by hardware may be realized by software. Various circuits such as an integrated circuit, a discrete circuit, or a circuit module obtained by combining the circuits can be used as the hardware. 
     The invention is not limited to the exemplary embodiments, the examples, and the modification examples which have been described above, and can be realized with various configuration in a range without departing from the gist of the invention. For example, the technical features in the exemplary embodiments, the examples, and the modification examples, which correspond to the technical features in the form described in the section of the summary can be appropriately replaced or combined in order to solve some or all of the above-described problems or to achieve some or all of the above-described effects. If the technical features thereof are not described as being necessary in this specification, the technical features can be appropriately removed. 
     The entire disclosure of Japanese Patent Application No. 2016-190761, filed Sep. 29, 2016 is expressly incorporated by reference herein.